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in recent years , the discussion of relativistic issues in the reactions involving the deuteron has become more and more important . some well known examples for a clear experimental evidence have been found in the electromagnetic disintegration @xcite . this results are supported by a recent analysis of polarization observables of the deuteron in a relativistic framework @xcite . also , the persistent difference between theory and experiment in polarization observables of proton deuteron scattering have been argued to be of relativistic origin @xcite . it is expected that the interpretation of new experimental results , e.g. , from tjnaf , also calls for a relativistic treatment . meanwhile the number of theoretical investigations devoted to this question and to tackle the relativistic aspects of few body systems is increasing . one may basically recognize two lines : on one hand the majority of approaches uses a nonrelativistic scheme of calculation and take into account some leading order corrections , such as nonnucleonic degrees of freedom like mesonic exchange currents , @xmath1-configurations , @xmath2-states and more . for a review see , e.g. , refs . @xcite which also contain an large number of references . note , however , that the problem of consistency arises as has been recently pointed out again , e.g. , by ref . @xcite in the context of electrodisintegration . the second line recognizes the importance of covariance @xcite . we follow the bethe - salpeter approach which is covariant by construction and properly defined @xcite . based on the field theory of particles this approach is also consistent and automatically takes into account all relativistic effects in the two nucleon system . because of the covariance of the bethe - salpeter equation the amplitudes ( or vertex functions ) may be written in any reference system , and one may chose a convenient one . however , practical applications are hampered by the difficulty of finding solutions of the bethe - salpeter equation , even in ladder approximation . nevertheless , the activity on solving the bethe - salpeter equation has increased in recent years @xcite , and by now parameterizations of the bethe - salpeter amplitudes in euclidean space are available @xcite . also , useful results have been achieved by a reduction of the bethe - salpeter equation to a three dimensional one . here , we examine the nonrelativistic reduction of the bethe - salpeter approach to compare with the results achieved by nonrelativistic calculations . since the problem has not been solved so far for the general case , we restrict ourself to a special process that is the disintegration of the deuteron.to this end we consider the threshold region only that exhibits already the main features to be discussed . also , this region is dominated by a single transition amplitude to the @xmath3 final state ( see , e.g. , ref . @xcite ) thus leading to some technical but not substantial simplifications . the extension to other partial amplitudes is straightforward but tedious , however beyond the scope of our present approach . indeed , the deuteron disintegration close to threshold energies has been a key reaction to establish subnucleonic degrees of freedom in nuclei @xcite and it attracts continuous attention from theoretical and experimental sides . it has been an excellent paradigm to examine nonnucleonic degrees of freedom and relativistic effects . it is well known that the nonrelativistic impulse approximation fails to describe the double differential cross section at momentum transfer squared @xmath4 @xmath5 . the experimental data do not indicate the deep minimum present in the calculations @xcite . to fill this minimum mesonic exchange currents have been introduced . the contributions of @xmath6- , @xmath7-currents , and @xmath8- configurations allow one to get a satisfactory agreement with the data @xcite . the question of a consistent inclusion of all relativistic corrections ( at least for the pion sector ) has recently been addressed by ref . @xcite and supports the above statement . nevertheless , some conceptional problems of the theory still remain open questions . among them is the problem of gauge invariance and the question of the nucleon form factor to be chosen in the exchange currents contributions @xcite . by now some relativistic methods identify corrections like meson exchange currents in the relativistic impulse approximation . it has been shown that in the framework of the light - cone approach the so - called extra components @xmath9 of the deuteron wave function , and @xmath10 of the @xmath3-wave function introduced in ref . @xcite give an expression in the nonrelativistic limit , that analytically equals to the contribution of the pair current @xcite . in this context the one iteration assumption that will be explained below for solving the dynamical equation is substantial . another important result in this context is the calculation of the static electromagnetic properties within the bethe - salpeter approach . it follows that the contribution of the @xmath0-states to the magnetic moment of the deuteron is numerically close to the contribution of mesonic currents and agrees in sign @xcite . it has already been noticed earlier in the context of covariant reductions of the bethe - salpeter equation to three dimensional ones that negative energy components in the wave function are responsible for pair current type contributions , see , e.g. , ref . @xcite . here we show that the suggested reduction procedure leads to the same _ analytical _ structure as the nonrelativistic pair current correction . the paper is organized as follows . section [ sec : nonrel ] contains the general formulas for the deuteron disintegration amplitude in different representations . the static approximation is also discussed . the one iteration approximation is formulated in section [ sec : oneit ] where we give reasons for its validity in simple models . the derivation of the main correction is done in the section [ sec : emc ] . we present and discuss our results in section [ sec : results ] , summarize and conclude in section [ sec : conclusion ] . because of lorentz covariance , transformation properties under parity and time reversal as well as current conservation , the general structure of the transition matrix element for the @xmath11 transition current near threshold can be written as @xcite @xmath12 where @xmath13 is the deuteron polarization four vector with projection @xmath14 , @xmath15 is the deuteron four momentum , @xmath16 is the four momentum transfer , @xmath17 is the squared total momentum of the @xmath18-pair , see fig . [ fig : diagram ] . the scalar function @xmath19 may be splitted into isovector dirac ( @xmath20 ) and pauli ( @xmath21 ) contributions @xmath22 the final state of the @xmath18-pair is supposed to be in a @xmath3-state . this is supported by nonrelativistic calculations @xcite . ( [ formc ] ) is valid in the any reference system and the functions @xmath23 depend on the scalars @xmath24 and @xmath25 only . current conservation is fulfilled because the tensor @xmath26 that appears in eq . ( [ formc ] ) is antisymmetric . to calculate the functions @xmath23 from the underlying dynamics in the bethe - salpeter approach , two representations of the bethe - salpeter amplitude may be used in concrete calculations : 1 ) the covariant representation and 2 ) the partial - wave representation . using the _ covariant representation _ for the initial and final states allows us to directly read off the functions @xmath27 from the proper current matrix elements . this has been done explicitly in ref . however , to study the relation to the nonrelativistic expressions it is more suitable to give the formulas for @xmath27 in terms of a _ partial - wave representation _ of the vertex functions . hence , the expressions for @xmath23 can be written as @xmath28 where the partial vertex functions @xmath29 represent the states @xmath30 , @xmath31 , @xmath32 , @xmath33 of the @xmath18-pair , and @xmath34 denote the states @xmath35 , @xmath36 , @xmath37 , @xmath38 , @xmath39 , @xmath40 , @xmath41 , @xmath42 of the deuteron . we use spectroscopic notation and ( @xmath43 , @xmath44 ) as @xmath7-spin quantum numbers @xcite . in general , the lengthy functions @xmath45 depend on lorentz scalars and the explicit expressions are omitted here . we will specify them below after having introduced appropriate approximations . the expressions for @xmath46 and @xmath47 are given in a formally covariant way , viz . @xmath48 where @xmath49 denotes the lorentz scalar product . we note that through the use of bethe - salpeter vertex functions the denominators of @xmath50 appearing in eq . ( [ a2 ] ) contain products of @xmath51 and @xmath52 , where @xmath53 , etc . that stem from the nucleon propagators ( see fig . [ fig : diagram ] ) . we evaluate the integrals in the laboratory system ( deuteron at rest ) . at threshold , because of the small deuteron binding energy , it is possible to utilize the static approximation @xcite that preserves the analytical structure of eq . ( [ a2 ] ) through the following equations @xmath54 here and in the following we use ( @xmath55 ) @xmath56 we illustrate the approximation by looking closer to the expressions involving the @xmath57 states . the full denominator of the integrand in eq . ( [ a2 ] ) leads to a complicated pole structure and reads explicitly @xmath58 using eq . ( [ eqn : static ] ) , then leads to a simple pole expression for the integrand involving the denominator @xmath59 thus , static approximation means in particular that @xmath60 ( no retardation ) and the lorentz boost transformation of the @xmath18-pair vertex functions is neglected . going beyond the static approximation can be achieved by expanding the full expression in terms of @xmath61 and @xmath62 that lead to additive corrections . the integration on @xmath63 can now be performed by choosing a proper integration contour and specifying the corresponding poles , e.g. , closing the upper half plane leads to poles for @xmath63 at @xmath64 . the vertex functions are then evaluated at @xmath65 . since in the reaction under consideration @xmath66 , we expand the vertex functions near @xmath67 for @xmath68 and @xmath69 respectively that allows us to derive analytical expressions in the one iteration approximation as will be shown in the next section . the analogous procedure holds for the other partial vertex functions . with this choice one the nucleons in the deuteron is taken on - shell . alternatively , it would have been possible to expand the functions , e.g. , near @xmath70 . however , the above advocated approach is more suitable , since it leads to an equation that allows for an analytical of @xmath63 . in eq . ( [ a2 ] ) we now perform the @xmath63 integration as explained above . the angular integration is simplified by taking @xmath71 along the @xmath72 axis and replace @xmath73 given in eq . ( [ qaoth ] ) via @xmath74 where @xmath75 . finally , to compare eq . ( [ a2 ] ) with the nonrelativistic limit we introduce a @xmath76-expansion excluding order @xmath77 ( i.e. @xmath78 ) . the resulting structure functions @xmath27 are then given by @xmath79 where @xmath80 , and @xmath81 , and @xmath82 is the legendre polynomial . the functions @xmath10 , @xmath83 , @xmath84 , @xmath85 , @xmath86 disappear in the above expressions after @xmath63 integration and because of the @xmath76 expansion . note , that within this approximation scheme we are left with the @xmath57 to @xmath57 and @xmath57 to @xmath87 transitions only . all other matrix elements , such as @xmath88 to all and @xmath87 to @xmath87 cancel , respectively . we now examine the expressions for @xmath27 given in eqs . ( [ v1nred],[v2nred ] ) more closely . to recover the nonrelativistic result , we neglect the vertex functions @xmath89 , @xmath90 , @xmath91 , @xmath92 that correspond to the negative @xmath7 spin components ( i.e. do not exist in the nonrelativistic scheme ) . if we replace the functions @xmath68 and @xmath93 by the nonrelativistic @xmath94 and @xmath95 wave functions and @xmath69 by the @xmath3 continuum wave function in the following way @xmath96 and insert these for the respective vertex functions into eqs . ( [ v1nred],[v2nred ] ) we obtain @xmath97 where we have introduced the magnetic isovector form factor @xmath98 . in co - ordinate space the respective integral is achieved using the following transformations , for the deuteron states ( @xmath99 , @xmath100 , @xmath101 ) @xmath102 where @xmath103 is spherical bessel function , and for the scattering state @xmath104 the resulting expression is @xmath105 this result reflects the so - called nonrelativistic impulse approximation and represents the lowest order nonrelativistic expansion of the transition form factors given in eqs . ( [ v1nred],[v2nred ] ) . the bethe - salpeter equation is commonly solved by iterations . after angular decomposition we are left with an integral equation for the radial parts of the vertex function @xmath106 . they are connected to the partial amplitudes @xmath107 which are used here for simplicity on the right hand side of the following equation by amputation @xcite , e.g. , for the @xmath57 components the relation is given by @xmath108 the integral equation read @xmath109 where @xmath110 denotes the type of exchanged meson , @xmath111 its coupling constant and @xmath112 is the transition matrix element between the states @xmath113 and @xmath114 given below . to get fast convergence to the solution of this equation one needs a good educated guess for the initial vertex function @xmath106 . this guess may be taken from the solution of the equivalent nonrelativistic problem . after several iterations one usually gets the exact solution . the initial vertex functions may be chosen along the lines given in ref . @xcite , generalizing eq . ( [ r2n ] ) @xmath115 all other wave functions are assumed to vanish in this order . note , that the numerators of eqs.([eqn : psi1],[eqn : psi3 ] ) are the nonrelativistic vertex functions . the ansatz given in eqs . ( [ eqn : psi1 ] ) and ( [ eqn : psi3 ] ) has been numerically verified for the deuteron consisting of two spinor nucleons that interact via the exchange of scalar mesons with mass @xmath116 . this interaction leads to a bound state for both , nonrelativistic and relativistic cases . in the _ nonrelativistic _ case and use of the schrdinger equation the kernel is of the form @xmath117 where the coupling constant @xmath118 leads to a binding energy of @xmath119 mev . the resulting wave function of the deuteron may be parameterized in the following form , @xmath120 with @xmath121 and a normalization constant @xmath122 . note , that for the scalar exchange model the @xmath95-wave function is zero , @xmath123 . these functions are then substituted as an educated guess into the system of equation ( [ bseq1 ] ) using the assumption of eqs . ( [ eqn : psi1],[eqn : psi3 ] ) . ( [ bseq1 ] ) is then solved in euclidean space ( @xmath124 ) using the ansatz amplitude eq . ( [ wfnr ] ) and the full kernel @xmath125 . @xmath126 to achieve the same deuteron binding energy as before , now using the bethe - salpeter equation ( [ bseq1 ] ) the coupling constant @xmath127 of the scalar interaction needs to be readjusted to get the same deuteron binding energy , viz . @xmath128 . in this framework we compare the full vertex function of the exact solution of eq . ( [ bseq1 ] ) to the result achieved by one iteration only but using the nonrelativistic solution as an educated ansatz . this will be called _ one iteration approximation _ in the following . as a demonstration for the quality of the approximation we show two vertex functions , for the @xmath35- and @xmath129-channels in fig . [ fig : compare ] . the upper two surfaces displayed correspond to the exact result and the one iteration approximation of the @xmath35-component . the difference between the two is rather small . in fact , in the relevant region @xmath130 gev and @xmath131 gev , where the amplitude has its major contribution to the normalization and to physical processes , the difference does not exceed 5% . the exact and the one iteration approximation for the @xmath129-channel that is relevant for the subsequent discussion of the electromagnetic properties are displayed as the lower two surfaces . we conclude that for the scalar model the shape of the exact solutions are already reproduced by one iteration . from that we argue that the one iteration approximation is a reasonable first step that may be utilized to solve the more complicated problem with realistic potentials . we now turn back to the discussion of the realistic deuteron implementing the full kernel with all spin dependences . by using eqs . ( [ bseq1 ] ) along with eqs . ( [ eqn : psi1],[eqn : psi3 ] ) the expressions for the @xmath132-channel , i.e. for the functions @xmath133 are now deduced analytically . if we consider the @xmath6-exchange kernel only and use the above given notation for the states ( @xmath134 ) then @xmath135 with legendre functions of the second kind @xmath136 , and @xmath137 . the @xmath63 integration can be performed yielding ( e.g. for the pionic exchange kernel ) @xmath138 the functions @xmath139 are obtained from @xmath140 by treating @xmath46 and @xmath63 as explained in sect . [ sec : nonrel ] . the explicit expressions for @xmath141 ( @xmath142 ) are given by : @xmath143 with @xmath144 . to simplify the notation the isospin factors have been omitted in @xmath141 and eq . ( [ bseq2 ] ) . the extension to other mesons of a one boson exchange kernel is straight forward . now using eqs . ( [ bseq2],[pot1 ] ) , the transformation eq . ( [ nr2k ] ) and the integral representations of the legendre functions @xmath145 we obtain following results for the vertex functions : @xmath146 where the isospin factor @xmath147 has now been shown explicitly . this is the analytical structure given after the first iteration . the inhomogeneous bethe - salpeter equation for the amplitudes in the @xmath3-channel reads @xmath148 here @xmath149 denotes the plane - wave function , @xmath150 where @xmath151 is the on - energy - shell momentum given by @xmath152 . for the subsequent discussion it is more convenient to split the system of equations into the following form : @xmath153 since the full vertex functions are related to the full amplitudes by amputation , the partial vertex functions @xmath154 are connected to the partial amplitudes @xmath155 via simple relations @xcite . as in the case of the deuteron channel we consider the one iteration approximation . to do so we chose a similar expression for the initial amplitudes as before to connect to the nonrelativistic solution , @xmath156 here @xmath157 is the nonrelativistic continuum wave function in @xmath3 channel given by @xmath158 and @xmath159 is nonrelativistic half - off - shell @xmath160-matrix for the @xmath3 channel normalized through the condition @xmath161 where @xmath162 is the phase shift , and @xmath163 . analogously to the deuteron case , we finally arrive at the first order corrections to the amplitudes in the @xmath3 channel , @xmath164 where @xmath165 is the isospin factor . we have shown in this section that choosing proper zero approximation wave function ( i.e. the nonrelativistic ones ) after one interaction additional partial amplitudes arise through the bethe - salpeter equation . they are connected to the interaction kernel and in electromagnetic processes give rise to the so called pair current correction as will be shown in the next section . we are now in the position to turn to the first order corrections to @xmath166 given in eq . ( [ vnrn ] ) . to this end we expand the expressions given in eqs . ( [ eqn : v12 ] ) , ( [ v1nred ] ) and ( [ v2nred ] ) into a power series of @xmath167 to extract the pionic contribution only . also we consider the @xmath0-states contribution only , i.e. components with one negative @xmath7 spin . the resulting expression for the transition form factor @xmath19 will be denoted by @xmath168 . substituting eqs . ( [ find ] ) and ( [ find1 ] ) as well as eqs . ( [ finp ] ) and ( [ finp1 ] ) into eqs . ( [ v1nred ] ) and ( [ v2nred ] ) and using the replacements of eq . ( [ r2n ] ) then eq . ( [ eqn : v12 ] ) reads @xmath169 the @xmath170-integration can be solved analytically . after doing so , we obtain @xmath171 here we have introduced the function @xmath172 where @xmath173 is given in eq . ( [ qaoth ] ) . this first order contribution in @xmath174 supplements the lowest order relativistic expansion as given in eq . ( [ vnrn ] ) of sect . [ sec : nonrel ] . we then arrive at the following expression for the transition form factor : @xmath175 this is our main result . starting from a fully covariant theory this result has been achieved using the lowest order relativistic contribution within the one iteration approximation . the relation between the nonrelativistic wave functions and the relativistic amplitudes given in eqs . ( [ eqn : psi1 ] ) , ( [ eqn : psi3 ] ) , and ( [ eqn : ph1 ] ) allows us to give the final expressions in terms of nonrelativistic wave functions . the lowest order in the @xmath176 coupling constant @xmath174 leads to an additional contribution from iterating the @xmath0-wave channel once . comparing this result to the one achieved within the nonrelativistic scheme that introduces mesonic exchange currents , we find find that the first term coincides analytically with the nonrelativistic impulse approximation contribution and the second one with the @xmath6-pair current contribution . to further illustrate the equivalence we connect our results to the nonrelativistic formalism describing the break - up process . more details are given , e.g in ref . the differential cross section for the @xmath177 - transition has the form ( nonrelativistic case ) @xmath178 where @xmath179 is the momentum transfer , @xmath180 . the momentum @xmath151 is related to the relative energy @xmath181 of the np system as given before @xmath182 and the relation between kinematical quantities is given by @xmath183 and @xmath184 , @xmath185 . in the general case , the current matrix element is a sum of nonrelativistic impulse approximation contribution , meson exchange currents contributions and retardation currents contributions . here we are interested in @xmath6-meson pair current part only and thus we may write for @xmath186 the following expression : @xmath187 where we introduced @xmath188 , which reflects the impulse approximation operator and @xmath189 , which is the @xmath6-meson pair ( contact ) operator . expressions for the matrix elements are given in ref . @xcite , see eq . ( 11 ) , and may be compared with eq . ( [ vnr : final ] ) . differences will be discussed below . we have shown in the previous section that the nonrelativistic reduction of the bethe - salpeter approach utilizing the one iteration approximation leads to results that exhibit the same _ analytical structure _ as the nonrelativistic result plus pair current corrections . some details differ as will be discussed below . one may now use the `` exact '' nonrelativistic wave functions to calculate the different contributions to the cross sections . this has been done here for an illustration . the formula for the cross section is given in eq . ( [ nr ] ) . the dominant m1 transition matrix element ( i.e. @xmath190 ) of the multipole decomposition given there directly corresponds to the nonrelativistic reduction of eq . ( [ formc ] ) given above . the contribution of the nonrelativistic impulse approximation given , e.g. in ref . @xcite coincides with the formula given in eq . ( [ vnrn ] ) if @xmath191 and @xmath192 are chosen as in eq . ( [ r2n ] ) . the analytical structure of the nonrelativistic pair current contribution equals to that of the @xmath0-state contribution derived from the bethe - salpeter approach given in eq . ( [ ve : final ] ) . we note that the nonrelativistic pionic pair current contribution given in ref . @xcite depends on the nucleon form factor @xmath193 . sometimes also the electric nucleon sachs form factor @xmath194 has been used ( see ref . the bethe - salpeter approach yields a different dependence on the nucleon form factor that is also consistent with current conservation and given by the function @xmath195 defined in eq . ( [ gamma ] ) . as an illustration of the different behavior we display the form factors @xmath193 ( solid line ) , @xmath196 ( dotted line ) , and the function @xmath195 ( dashed line ) in fig . [ fig : ffl ] . as a parameterization for the nucleon form factors we use the one given in ref . the form factor @xmath197 is larger than the form factor @xmath198 and the function @xmath195 and therefore the respective pionic pair current is expected to be larger than the one using the other form factors . since the function @xmath195 is in the middle of the other ones the respective contribution of the @xmath0-states in bethe - salpeter approach will be different from the nonrelativistic calculations normally using @xmath193 or @xmath196 . to investigate the influence of the nucleon form factors more closely we calculated the impulse approximation and pionic pair current contributions to the differential cross section . the calculation is performed with the paris @xmath199 potential @xcite at @xmath200 mev and @xmath201 . it is well known that some uncertainty is related to the hadron form factors . without dwelling too much on that point we would like to compare three different form factors to see how this uncertainty influences the result . introducing the hadron form factors change the expressions for the pair current contribution @xcite . three sets of hadron form factors ( for @xmath176-vertex ) have been utilized and are shown in figs . [ fig : iapc ] a - c ) , respectively : a monopole vertex @xcite with a cut - off mass of @xmath202 gev ( set a ) and @xmath203 gev ( set b ) . in addition a vertex inspired by a qcd analysis has been used with two parameters given chosen to be @xmath204 gev and @xmath205 gev @xcite ( set c ) . it is seen from fig . [ fig : iapc ] that there is a strong dependence of the differential cross section on the nucleon electromagnetic form factors . it is also seen that the minimum at @xmath206 @xmath5 in the impulse approximation contribution is shifted by pionic pair current to the region @xmath207 @xmath5 using @xmath198 , to @xmath208 @xmath5 using the function @xmath195 and to @xmath209 @xmath5 using @xmath193 as a form factor . the largest shift in the cross section is achieved by using @xmath193 in the calculations . the size of the shift and the behavior of the cross section considerably depends on the set of parameters as well as the type of the @xmath210-vertex used . this is illustrated in fig.[fig : iapc]d ) for calculations using @xmath193 only but for different parameterizations of the strong vertex . we investigate the electromagnetic current in the framework of the bethe - salpeter approach . the question addressed is the nonrelativistic reduction of the current transition amplitude . as a specific application we consider the deuteron disintegration near threshold energies in some detail . we present a method to reduce the amplitude to the nonrelativistic one . we summarize the basic steps of this method and the main approximations utilized . to arrive at our result , i.e. to compare the relativistic expressions to the pair current that appears in the nonrelativistic scheme , two main assumptions have been introduced : 1 ) the static approximation and 2 ) one iteration approximation . in the static approximation boost corrections are neglected . we emphasize that the latter contributions are not negligible and for the elastic form factors corrections can achieve 20 % . a discussion of this contributions in a noncovariant but consistent relativistic framework may be found in ref . @xcite . although important , a discussion of all these contributions in not the main issue of our present paper . in fact , we do not expect any substantial change in our present conclusions , since all corrections are of additive nature and will be taken into account as the scheme develops . the one iteration approximation is to some extent more subtle . it plays an essential role in connecting the bethe - salpeter amplitudes and the usual nonrelativistic wave functions . this approximation allows us to express the final result in terms of the usual @xmath94- and @xmath95-wave functions of the deuteron and the @xmath94-wave function of @xmath18-pair . although numerically verified for deuteron - like models , the one iteration approximation needs further investigation . we argue that the validity is due to the small binding energy for the deuteron . from inspection of the next iterations we find additive corrections only . therefore these assumptions can be loosen up and additional corrections can be taken into account . this way we have a possibility to calculate corrections in a more consistent way . this problem is present in both , electromagnetic and strong processes ( for @xmath211 and @xmath212 reactions , for instance ) . although the calculation of these corrections is important to arrive at definite conclusions about the covariant approach as a whole , our main issue here is to investigate the correspondence between the covariant approach and the mesonic exchange currents of the nonrelativistic approaches . we have shown the analytic correspondence of these different approaches . the pair correction plays an essential role in explaining the experimental data . an interesting result in this context is connected to the form factor entering in the pair current term . the overall form factor that is consistent with gauge independence and the relativistic ( covariant ) expansion neither coincides with @xmath213 nor with @xmath214 but requires an `` average '' between them . the authors wish to thank kaptari l.p . , titov a.i . and especially karmanov v.a . for useful and stimulating discussions . we thank semikh s.s . and suskov s.eh . for assistance in the numerical calculations . the authors are grateful to each others home institutions for extended hospitality during the respective visits . part of the work has been done during the research workshop on `` progress in current few body problems '' hosted by the bogoliubov laboratory of theoretical physics and supported by the heisenberg - 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( kyoto ) suppl . * 43 * , 1 ( 1969 ) . umnikov , l.p . kaptari , k.yu . kazakov , and f.c . khanna , phys . b * 334 * , 163 ( 1994 ) . t. nieuwenhuis , j.a.tjon , few - body syst . * 21 * 167 ( 1996 ) . umnikov a.yu . , z. phys . a * 357 * , 333 ( 1997 ) . h. arenhvel , lecture notes in physics , vol . 426 , eds l. mathelitsch and w. plessas ( 1995 ) p 1 . s. auffret _ et al . _ , lett . * 55 * 1362 ( 1985 ) ; r.g . et al . _ , c * 42 * , r1 ( 1990 ) . j.a . lock and l.l . foldy , ann . of phys . * 93 * , 276 ( 1975 ) . mathiot , nucl . phys . * a412 * , 201 ( 1984 ) . singh , w. leidemann , h. arenhvel , z. phys . a * 331 * , 509 ( 1988 ) . w. leidemann , and h. arenhvel , z. phys . a * 326 * , 333 ( 1987 ) . r. schiavilla , and d.o . riska , phys . c * 43 * , 437 ( 1991 ) . b. desplanques , v.a . karmanov , and j .- f . mathiot , nucl . phys . * a589 * , 697 ( 1995 ) ; j. carbonell , b.desplanques , v.a . karmanov , and j .- f . mathiot , phys . rep . to be published . kaptari l.p . , umnikov a.yu . bondarenko , k.yu . kazakov , f.c . khanna , and kmpfer b. , phys . c * 54 * , 986 ( 1996 ) . j. adam jr . , a. stadler , m.t . pena , and f. gross , nucl . a * 631 * 570c ( 1998 ) ; s. wallace _ ibid . _ s.g . bondarenko , v.v . burov , m. beyer , and s.m . dorkin , mpg - vt - ur 87/96 , _ e - print archive : nucl - th/9612047_. j.j . kubis , phys . rev . * 6 * , 547 ( 1972 ) . zuilhof and j.a . tjon , phys . c * 22 * , 2369 ( 1980 ) . burov , a.a . goy , s.eh . suskov , and yu.v . chubov , sov . * 59 * , 989 ( 1996 ) . mathiot , nucl.phys . * a412 * , 201 ( 1984 ) . g. hhler _ et al . _ , b114 * , 29 ( 1976 ) . r. machleidt , k. holinde , and ch . elster , phys.rep . * 149 * , 1 ( 1987 ) . m. gari and u. kaulfuss , nucl a408 * , 507 ( 1983 ) . burov , v.n . dostovalov , and s.eh.suskov , czech . j. of phys . * 41 * , 1139 ( 1991 ) . m. lacombe _ et al . _ , phys.rev . * c21 * , 861 ( 1980 ) . ( 20.00,60.00)(1,0)20.00 ( 40.00,60.00)(3,2)20.00 ( 20.00,60.00)(1,0)10 ( 40.00,60.00)(3,2)10 ( 35.00,40.00)(3,2)15.00 ( 35.00,40.00)(3,2)7.5 ( 50.00,50.00)(3,-2)14.00 ( 50.00,50.00)(3,-2)7.5 ( 35.00,38.00)(1,0)28.3 ( 35.00,38.00)(1,0)15.00 ( 20.00,40.00)(1,0)15.00 ( 20.00,38.00)(1,0)15.00 ( 25.00,41.00)(28.00,39.00)(28.00,39.00 ) ( 25.00,37.00)(28.00,39.00)(28.00,39.00 ) ( 35.00,39.00 ) ( 65.00,39.00 ) ( 66.6,40.00)(1,0)8.4 ( 66.6,38.00)(1,0)8.4 ( 75.00,40.00)(1,0)5.00 ( 75.00,38.00)(1,0)5.00 ( 40.00,60.00)(42.00,60.00)(42.00,58.00 ) ( 42.00,58.00)(42.00,56.00)(44.00,56.00 ) ( 44.00,56.00)(46.00,56.00)(46.00,54.00 ) ( 46.00,54.00)(46.00,52.00)(48.00,52.00 ) ( 48.00,52.00)(50.00,52.00)(50.00,50.00 ) ( 28.00,30.00)(0,0)[cc]d : @xmath215 ( 73.00,30.00)(0,0)[cc]np : @xmath216 ( 47.00,57.00)(0,0)[cc]@xmath217 ( 25.00,63.00)(0,0)[cc]@xmath218 ( 55.00,74.00)(0,0)[cc]@xmath219

we investigate the nonrelativistic reduction of the bethe - salpeter amplitude for the deuteron electrodisintegration near threshold energies . to this end , two assumptions have been used in the calculations : 1 ) the static approximation and 2 ) the one iteration approximation . within these assumptions it is possible to recover the nonrelativistic result including a systematic extension to relativistic corrections . we find that the so - called pair current term can be constructed from the @xmath0-wave contribution of the deuteron bethe - salpeter amplitude . the form factor that enters into the calculation of the pair current is constrained by the manifestly gauge independent matrix elements . # 1 * pacs : * 21.45.+v , 25.30.fj , 24.10.jv

the standard procedure to study the underlying event ( ue ) characteristics starts with defining regions of the azimuthal detector acceptance based on the direction of the leading charged jet @xcite or the leading track @xcite in an event . these regions , each of them covering an equal angle of @xmath0 are called towards , transverse and away . the toward and away regions are expected to contain the tracks that are produced by the fragmentation of the partons that took part in the hard scattering while the transverse region is expected to collect tracks from the ue . alice @xcite has characterized the ue in pp collisions at @xmath1 = 0.9 and 7 tev in @xcite by measuring the charged particle density , summed @xmath2 and azimuthal correlations ( between the leading track and the remaining tracks from the event ) in the above mentioned regions . this study presents an estimator for the multiplicity of the underlying event of proton - proton collisions and then uses it to characterize the properties of charged jets in different ranges of the underlying activity . thus , this study allows to characterize the interplay between the low momentum transfers related to the underlying activity and the hard partonic interactions that produce jets . the experimental results presented in this work are based on a sample of 172 million minimum bias pp collisions at @xmath1 = 7 tev . charged tracks were reconstructed using the inner tracking system ( its ) and the time projection chamber ( tpc ) . the combined information from the its and the tpc provide a uniform acceptance of tracks as well as good momentum resolution . details about the track selection used in the charged jet analysis in alice can be found in @xcite . the jet activity is identified using a jet finder algorithm . for this work we use the siscone jet finder @xcite which is a seedless infrared - safe cone algorithm . the jet finding is performed using charged particles with @xmath3 1 gev/@xmath4 and a cone radius of @xmath5=0.4 as input parameters for the algorithm . the minimum jet transverse momentum was set to 5 gev/@xmath4 . the ue definition is that it comprises all the activity in the event but that related to the hardest scattering in a pp collision . in this work we propose to use a jet finding algorithm to identify the orientation in the @xmath6 space of the products of the jet fragmentation and then characterize the underlying activity in the regions where the jet finder had not identified jet fragmentation activity . we developed a multiplicity estimator to characterize the um following a suggestion by frankfurt , strikman and weiss who discuss the transverse nucleon structure in @xcite . in that paper it is suggested to associate the multiplicity to the impact parameter of the pp collision . therefore we propose in this work to use a multiplicity estimator , that is not biased by the multiplicity created by the jet fragmentation , to access experimentally the centrality of the pp collision . this provides also a test of the implementation of pp centrality in modern mc generators , which contain simplifications such as the assumption of factorization of the parton @xmath7 and the impact parameter as well as the lack of information of the flavor and @xmath7 dependence of the proton s transverse composition as described in @xcite . definition of soft event multiplicity in jet events . the drawing represents the acceptance of the alice tpc in the @xmath8-@xmath9 space . the dark blue ( colors in the online version ) circle shows the jet area covered by the jet cone with radius @xmath5 . the grey rectangular area is the di - jet area . the width of the excluded di - jet area in the @xmath9 direction is 2@xmath5 and covers the whole acceptance in the @xmath8 direction . the dotted lines represent the maximum limits for the @xmath8 coordinate of the accepted jet axis , so the complete jet area falls inside the tpc acceptance . ] the um estimation is based on the separation of the event phase space into two regions : one that contains jet activity and the complementary region . the um is calculated using the charged tracks measured within the tpc acceptance ( @xmath10 0.9 and @xmath11 ) . the first classification of the tracks from the events is done by their transverse momentum . the @xmath2 cutoff of the jet finder ( 1 gev/@xmath4 ) has been chosen to allow for a gap between this cutoff and the transverse momentum of the tracks that are used in the multiplicity estimation . therefore we define as the total tpc multiplicity those tracks that have 150 mev/@xmath4 @xmath12 900 mev/@xmath4 . the second requirement to select tracks for the um comes from the geometry of the event , this selection can be easily explained using figure [ fig : figtpcacc ] . the figure shows the @xmath8 and @xmath9 acceptance of the alice tpc . to calculate the soft tpc multiplicity , that corresponds to the um measured in the alice central barrel , the tracks that fall into two areas of the acceptance are not taken into account in the multiplicity estimation . the first area is shown in figure [ fig : figtpcacc ] as a circle that corresponds to the jet cone with axis coordinates @xmath13=0.5 and @xmath14=@xmath15/2 in this example . the second area that is excluded is the di - jet area , centred at @xmath16=@xmath14+@xmath15 , having a width in the @xmath8 axis of @xmath17 and covering the whole acceptance in the @xmath9 direction . figure [ fig : figtpcsofttot ] shows the distribution of the mean values of the soft tpc multiplicity , shown with black markers , as a function of the total tpc multiplicity defined above . the figure shows as well , using a dashed line , the values of the soft tpc multiplicity that would be expected in the case that the reduction in the multiplicity is caused only by a geometrical exclusion . the experimental result shows that the soft tpc multiplicity is a fraction of the geometry expectation and increases linearly as a function of the total tpc multiplicity . soft tpc multiplicity as a function of the total tpc multiplicity . the figure shows the experimental measurements as well as the expectation values from a pure geometrical exclusion . ] the jet observable that is used in this work to characterize the fragmentation properties of the charged jets is called _ nt90_. _ nt90 _ was proposed in @xcite as an observable that can be used to discriminate jets originating from quark or gluon fragmentation . _ nt90 _ is constructed by selecting the tracks that are contained in the jet cone and that fulfil the same @xmath2 cutoff used during the jet finding . this set of tracks is then sorted according to their transverse momentum going from the highest to the lowest in magnitude . then one adds the @xmath2 of the sorted tracks until 90% of the total charged jet transverse momentum ( @xmath18 ) is recovered . _ nt90 _ is the minimum number of tracks necessary to recover 90% of the total @xmath18 . figure [ fig : fignt90qg ] shows the mean values of _ nt90 _ as a function of the @xmath18 obtained with pythia6 minimum bias events that include the detector simulation of alice . the figure shows the different distributions obtained for quark and gluon initiated jets separately as well as for the inclusive jet sample . one can notice that the mean value of _ nt90 _ at a fixed value of the @xmath18 is larger for gluon initiated jets than for quark initiated jets . this shows the known feature that the gluon jets have on average a softer fragmentation than quark jets at the same parton @xmath2 . mean values of _ nt90 _ as a function of the @xmath18 for a pythia6 simulation of pp collisions at @xmath1 = 7 tev . the triangles show the distribution obtained for gluon initiated jets while the squares show the distributions for quark initiated jets . the black circle distribution shows the results obtained for the inclusive jet sample . ] figure [ fig : fignt90ptdata ] shows the ratio of the mean values of _ nt90 _ from jet samples corresponding to two bins of the um as a function of the raw @xmath18 . the ratio is between a bin with low um , @xmath19__nt90__@xmath20 , and a bin with high um , @xmath19__nt90__@xmath21 . the bin with low um has a soft tpc multiplicity smaller than 0.4 times the mean soft tpc multiplicity @xmath12 900 mev/@xmath4 that are outside the areas related with jet fragmentation . ] and the one with high um is associated to a soft tpc multiplicity larger than 1.2 times the mean soft tpc multiplicity . from the figure one can see that the jet properties from the two jet samples are different . the mean values of the _ nt90 _ from the jets associated to high um are larger than those associated to low values of the um . this means that the jets in events with large um have a softer fragmentation compared to the jets associated to low values of the um . ratio of the mean values of _ nt90 _ obtained from two jet samples associate to different values of the um as a function of the raw @xmath18 . one jet sample is associated to values of the um smaller than the average soft tpc multiplicity ( lm ) while the other is from jets associated to values of the um larger than the average soft tpc multiplicity ( hm ) . the data is presented at the detector level . ] after looking at the differences in the properties of the charged jets from the two bins of um , figure [ fig : fignt90-functionjetpt - mc ] shows the results corresponding to those from figure [ fig : fignt90ptdata ] but now obtained from mc generators including full detector simulation . the left panel of figure [ fig : fignt90-functionjetpt - mc ] shows the results obtained with phojet @xcite , and the right panel shows the results obtained with a pythia6 @xcite simulation using the tune perugia 0 @xcite . as one can see from the figure the mc generators are able to reproduce a general trend observed in the data , i.e. a softer fragmentation of the jets associated to high values of the um compared to those associated to low um . @xmath22{ratio - phojet - zerosuppressed - nosystematics.eps } & \includegraphics[width=17pc]{ratio - pythia6-preliminary - nosystematics.eps } \\ [ 0.4 cm ] \end{array}$ ] a comparison of the experimental results and the predictions from the mc generators is presented in figure [ fig : fignt90-mult - datamc ] , which shows the mean values of _ nt90 _ as a function of the normalized um measured in the alice central barrel . @xmath22{comparison - mc - data-10to30gev - preliminary - ls.eps } & \includegraphics[width=17pc]{comparison - mc - data-30to65gev - preliminary - ls.eps } \\ [ 0.4 cm ] \end{array}$ ] the standard way to present results as a function of multiplicity is by plotting the observable as a function of fractions of the mean multiplicity . in this case the results are presented for different bins of um , @xmath19 tpc@xmath23 @xmath24 , normalized by the mean value of um , @xmath19 tpc@xmath25 @xmath24 , measured in the central barrel for each data sample . the data was separated into two ranges of @xmath18 . the left panel of figure [ fig : fignt90-mult - datamc ] shows the results obtained for 10 gev/@xmath4 @xmath26 30 gev/@xmath4 and in the right panel for jets with 30 gev/@xmath4 @xmath26 65 gev/@xmath4 . the results obtained from the mc generators are presented after the full alice detector simulation so they are directly comparable with the experimental results . for jets with 10 gev/@xmath4 @xmath26 30 gev/@xmath4 pythia6 shows a similar dependence with the multiplicity as the one observed in the experimental data , while phojet shows a flatter dependency . for jets with 30 gev/@xmath4 @xmath26 65 gev/@xmath4 one can observe a monotonic increase of the mean values of _ nt90 _ with increasing multiplicity for the experimental data . a similar trend is observed in the pythia6 results while phojet on the other hand shows an increase of the mean values of _ that seems to saturate after reaching the mean value of the um . we have presented an estimator of the underlying soft multiplicity in pp collisions . the characterization is done with the um , that uses the information from a jet finder to localize the regions of the detector acceptance that contain most of the jet fragmentation products . then we separated the collision data in bins of um and studied the charged jet fragmentation using the _ nt90 _ observable . we observe that events with high activity of the um are correlated to jets that undergo a softer fragmentation . the mc models pythia6 and phojet are able to reproduce the experimental observations for low momentum jets , while for intermediate jet transverse momentum phojet seems to fail for um above the mean values . the fact that the mc generators are able to describe the dependence of the jet fragmentation as a function of the um needs further studies given that the models contain a simplified approach to describe the nucleon - nucleon collision centrality . the author thanks c. blume for the collaboration in the analysis presented in this work and c. klein - bsing and m. van leeuwen for their comments and support . this work was supported by the helmholtz research school for quark matter studies . the alice collaboration 2012 _ jhep _ * 3 * 053 salam g p and soyez g 2007 _ preprint _ arxiv:0704.0292v2 frankfurt l , strikman m and weiss c 2011 _ phys . _ d * 83 * 054012 buckley a _ et al_. 2011 _ phys . rep . _ * 504 * 054012 145 - 233 pumplin j 1991 _ phys . _ d * 44 * 7 2025 - 32 roesler s , engel r and ranft j 2000 _ preprint _ arxiv : hep - ph/0012252v1 sjstrand , mrenna s and skands p 2006 _ jhep _ * 05 * 026 skands p 2012 _ phys . _ d * 82 * 074018

a preliminary study of the fragmentation properties of charged particle jets as a function of the underlying multiplicity ( um ) is presented . the um is defined such that it can be related to the global soft event characteristics by excluding the contribution due to jet fragmentation . the measurement of jet properties as a function of the um might be connected to the impact parameter dependence of the transverse nucleon structure as described via generalized parton distributions . the results from the studies are compared to monte carlo ( mc ) models .

it is well known that acute coronary syndrome ( acs ) is the most common cause of cardiac arrest . however , spontaneous subarachnoid hemorrhage ( sah ) is also a common neurological disorder that leads to out - of - hospital cardiac arrest . typical electrocardiogram ( ecg ) changes , such as st - segment elevation or depression and abnormal t wave morphologies , may mimic myocardial infarction or ischemia . furthermore , sah patients also have elevated troponin levels and myocardial regional wall motion abnormalities due to neurogenic stunned myocardium . these nonspecific findings can lead to misdiagnosis and incorrect therapeutic decisions in these cardiac arrest patients , such as thrombolytic therapy and percutaneous coronary intervention . in this article , we report a case of an out - of - hospital cardiac arrest survivor whose initial ecg indicated a st - segment elevation myocardial infarction ( stemi ) ; however , she was finally diagnosed with sah . compared with previous reports of cardiac arrest survivors with sah mimicking acute myocardial infarction ( ami ) , the ecg of this case was more distinct because of its st - segment elevations in the lateral leads and the reciprocal st - segment depression in the inferior leads indicating a typical stemi . we suggest that , even with signs of ami , clinicians should consider the possibility of sah as a cause of cardiac arrest in comatose resuscitated patients . a 48-year - old woman without any known history of disease suddenly collapsed and lost consciousness . she had no palpable pulse , and the initial ecg rhythm , determined by an automated external defibrillator , was asystole . ems providers continues cardiopulmonary resuscitation ( cpr ) and arrived at the emergency department about 30 minutes after the sudden collapse . in ed , cpr was performed in accordance with the current advanced cardiac life support guidelines of 2010 . after 4 minutes of resuscitation with a total of 2 mg epinephrine , she recovered spontaneous circulation . her vitals were as follows : blood pressure , 122/99 mmhg ; pulse rate , 144/min ; respiratory rate , 20/min . her glasgow coma scale score was 3 ; endotracheal intubation was performed for airway protection by an emergency physician . the initial 12-lead ecg showed sinus tachycardia and st - segment elevation in leads i , avl , v5 , and v6 with reciprocal st - segment depression in leads iii , avf , and v1 to v3 ( fig . results of the initial biochemical tests revealed followings : sodium 142 mmol / l , potassium 3.7 mmol / l , glucose 321 mg / dl , serum creatine kinase mb 4.5 u / l , and troponin - i 0.63 g / l . within 10 minutes after recovery of spontaneous circulation , a low blood pressure was documented ( 83/43 mmhg ) , and norepinephrine infusion was started in the mean time a cardiologist performed an emergent bedside echocardiography and decided to do an emergent coronary angiography because of regional wall abnormalities that suggested an ischemic insult of the left circumflex artery . at 30 minutes after recovery of spontaneous circulation , she underwent coronary angiography , which revealed normal coronary arteries without any evidence of stenosis . after admission into the cardiac care unit , a computed tomography scan of the brain was performed . twenty hours after the onset of the symptoms , the st - segment abnormalities disappeared and t - wave inversion was noted ( fig . serial values of the serum cardiac enzymes increased within 24 hours , and the peak values of creatine kinase mb and troponin - i were 28.3 u / l and 7.25 g / l , respectively . on the third day of hospitalization , the echocardiography showed akinesia of the left ventricle ( lv ) mid - walls with moderate to severe lv dysfunction ( ejection fraction , 36% ) , which implied a variant form of stress - induced cardiomyopathy . despite the administration of a vasopressor the shock progressed gradually , and on the 13th day of hospitalization , she was pronounced dead . many cases have been reported with cardiac manifestations following sah including ecg changes such as st - segment deviations , t - wave inversion , and qtc prolongation ; cardiac enzyme elevations ; and echocardiographic abnormalities . despite many reports , it is still a challenge for clinicians to distinguish intracranial hemorrhage from acs , especially among post - cardiac arrest survivors . a previous studies on cardiac manifestations of sah showed that cardiac abnormalities were found in 14.1% of patients with non - traumatic sah . the most common ecg finding was t - wave inversion and st - segment depression , suggesting subendocardial ischemia . they reported that 8 out of 10 patients had st - segment elevation in avr with st - segment depression in widespread leads , and three of these patients showed takotsubo - like regional lv dysfunction . to our knowledge , this is the first report describing an out - of - hospital cardiac arrest survivor whose initial ecg changes and echocardiographic findings strongly suggested stemi , but who was finally diagnosed with sah after the emergent coronary angiography revealed entirely normal coronary arteries . the ecg changes of lateral wall myocardial infarction typically present as st - segment elevation in leads i , avl , v5 , and v6 with reciprocal st - segment depression in leads ii , avf , v1 , and v2 . however , lateral wall infarction usually occurs in other territories of the myocardium such as the anterolateral and inferolateral areas . in our case , the st - segment elevation in the lateral leads was obvious , but the reciprocal changes of the st - segment depression were relatively obscure . in addition , there was no contiguous st - segment depression in the precordial leads and the upsloping st - segment depression was an unusual finding for ischemic myocardial injury . many interventions have been emphasized for improving post - cardiac arrest outcomes , including immediate thrombolysis and percutaneous coronary intervention . according to the current guidelines , regardless of the level of consciousness in cardiac arrest survivors , aggressive treatment such as percutaneous coronary intervention emergency physicians may also feel pressured to promptly initiate revascularization treatment due to the importance of door - to - balloon interval . thus , further studies will be needed to clarify the differences in the ecg findings of acs and sah . we believe that observations reported here have potentially significant implications for physicians making decisions of post - arrest care , for once successfully resuscitated patients . clinicians should consider an immediate brain computed tomography to exclude sah as a cause of cardiac arrest , even with st - segment elevation .

electrocardiogram changes in subarachnoid hemorrhage ( sah ) have been described as st - t changes that mimic acute coronary syndrome and even acute st - segment elevation myocardial infarction . elevation of cardiac enzymes and abnormality of regional myocardial wall motion have been reported frequently for sah . we report a case of an out - of - hospital cardiac arrest survivor with high suspicion of st - segment elevation myocardial infarction based on the electrocardiogram and bedside echocardiography , who had normal coronary arteries on emergent coronary angiography . the patient was ultimately diagnosed with sah as a cause of out - of - hospital cardiac arrest .

SECTION 1. PROGRAMS REGARDING EMPLOYEE OWNERSHIP AND PARTICIPATION. (a) Establishment of Program.--Not later than 180 days after the date of the enactment of this Act, the Secretary of Labor (referred to in this Act as the ``Secretary'') shall establish a program to facilitate the establishment of State programs to foster increased employee ownership and greater employee participation in business decisionmaking throughout the United States. (b) Purpose of Program.--The Secretary shall establish the program under subsection (a) to encourage State programs which focus on the following: (1) Activities involving education and outreach to inform individuals about the possibilities and benefits of employee ownership, gainsharing, and participation in business decisionmaking, including financial education. (2) Activities involving technical assistance to assist employee efforts to become business owners. (3) Training activities for employees and employers with respect to methods of employee participation in business decisionmaking. (4) Activities involving training other organizations to apply for funding under this section. (c) Program Details.--In focusing on activities referred to in subsection (b), the Secretary may include in the program provisions that would-- (1) in the case of activities under subsection (b)(1)-- (A) target key groups such as retiring business owners, unions, managers, trade associations, and community organizations; (B) encourage cooperation in organizing workshops and conferences; and (C) provide for the preparation and distribution of materials concerning employee ownership and participation; (2) in the case of activities under subsection (b)(2)-- (A) provide for the performance of prefeasibility assessments; (B) provide assistance in the funding of objective third party feasibility studies; and (C) provide a data bank to help employees find legal, financial, and technical advice in connection with company ownership; (3) in the case of activities under subsection (b)(3)-- (A) provide for courses on employee participation; and (B) provide for the development and fostering of networks of employee-owned companies to spread the use of successful participation techniques; and (4) in the case of activities under subsection (b)(4)-- (A) provide for visits to existing programs qualified under this Act by staff from new programs receiving funding under this Act; and (B) provide materials to be used by organizations qualified under this Act. (d) Regulations.--Regulations issued by the Secretary pursuant to this Act shall include provisions assuring that any program within the several States established for the purposes of this Act be-- (1) proactive in encouraging actions and activities that will promote and encourage employee ownership of companies and participation in decisionmaking in such companies; and (2) comprehensive in emphasizing both employee ownership of companies and employee participation in company decisionmaking so as to boost productivity and broaden capital ownership. (e) Grants.--Any program established pursuant to subsection (a) shall provide for grants to the program within the several States in accordance with section 4. SEC. 2. OFFICE OF EMPLOYEE OWNERSHIP AND PARTICIPATION. (a) Establishment.--The Secretary shall establish, within the Department of Labor, the Office of Employee Ownership and Participation (hereafter referred to as the ``Office'') to promote employee ownership, gainsharing, and employee participation in company decisionmaking. (b) Functions.--The functions of the Office are to-- (1) support programs within the several States approved by the Secretary as being in compliance with the program established pursuant to section 1; and (2) facilitate the formation of new programs within the several States for the purpose of accomplishing the goals of this Act. (c) Duties.--In carrying out its functions under subsection (b), the Office shall-- (1) in the case of activities under subsection (b)(1), support those programs within the several States that are designed to achieve the goals and purposes set forth in this Act and to provide such support by-- (A) making matching Federal grants under section 4; and (B) acting as a clearinghouse on techniques employed by the programs within the several States and disseminating information to such programs, or funding such information gathering and dissemination programs by groups outside the Office; and (2) in the case of activities under subsection (b)(2), facilitate the formation of new programs by encouraging the establishment of such programs in each of the 50 States, including the holding or funding of an annual conference to bring together representatives from States with existing programs and representatives from States without such existing programs. SEC. 3. ORGANIZATION OF THE OFFICE. (a) Director.--There shall be at the head of the Office a Director of Employee Ownership and Participation (hereafter referred to as the ``Director'') who shall be appointed by the Secretary. (b) Employees.--In carrying out the functions of the Office, the Director may select, appoint, employ, and fix the compensation of such employees as shall be necessary to carry out the functions of the Office. SEC. 4. GRANTS. (a) In General.--For the purpose of making grants authorized under the program established pursuant to section 1, the Office is authorized to make grants for use in connection with programs within the several States for any of the following activities: (1) Education and outreach. (2) Participation training. (3) Technical studies, including prefeasibility and feasibility studies. (4) Activities facilitating cooperation among employee ownership firms. (5) Training for newly formed organizations to be provided by existing organizations qualified under this Act, except that such funding shall not exceed 10 percent of the total grants under this Act. (b) Matching.-- (1) In general.--Except as provided in paragraph (2), grants under this section shall be made by the Office on a matching basis, $1 of Federal money for every 50 cents of non- Federal money. (2) Grants for certain training.--Grants for activities described in subsection (a)(5) shall not require non-Federal matching contributions. (c) Applications.--The Office shall prescribe the form and information necessary for applications for grants under this section. (d) Amounts and Conditions.--The Office shall determine the amounts and the conditions for grants made under this section. (e) Grants on Behalf of Other Entities.-- (1) State applications.--Each of the several States may sponsor and submit applications on behalf of units of State or local governments, State-supported institutions of higher education, and nonprofit organization programs meeting the requirements of this Act, but in no case shall the aggregate amounts of these grants made to any unit of State or local government, State-supported institutions of higher education, or nonprofit organization programs exceed the amount set forth in subsection (g). (2) Applications by entities.--In any case in which a State fails to establish a program pursuant to this Act during any fiscal year, the Secretary shall allow in the subsequent fiscal year entities described in paragraph (1) to make applications for grants on their own initiative. States may submit applications to the program in subsequent years but may not screen applications by such entities before submission to the program. (f) Annual Report.--Each grant recipient shall submit an annual report to the Office setting forth how all moneys from grants pursuant to this Act were expended during the 12-month period preceding the date of the submission of the report. (g) Limitations.--Grants to each of the recipients shall be limited for each fiscal year as follows: (1) Fiscal year 1995, not to exceed, in the aggregate $200,000. (2) Fiscal year 1996, not to exceed, in the aggregate $220,000. (3) Fiscal year 1997, not to exceed, in the aggregate $242,000. (4) Fiscal year 1998, not to exceed, in the aggregate $266,200. (5) Fiscal year 1999, not to exceed, in the aggregate $292,000. SEC. 5. AUTHORIZATIONS. (a) In General.--For the purpose of making grants pursuant to section 4, there are authorized to be appropriated the following: (1) For fiscal year 1995, $2,500,000. (2) For fiscal year 1996, $4,250,000. (3) For fiscal year 1997, $6,000,000. (4) For fiscal year 1998, $7,750,000. (5) For fiscal year 1999, $9,500,000. (b) Administrative Expenses.--For the purpose of funding the Office, there is authorized to be appropriated for each of the fiscal years 1995 through 1999 an amount not in excess of the lesser of-- (1) $250,000, or (2) 7.5 percent of the maximum amount available under subsection (a). SEC. 6. OFFICE REPORTING. Not later than the expiration of the 36-month period following the date of enactment of this Act, the Director shall report to the Congress on the progress of employee ownership and participation in businesses in the United States. The report shall include a critical cost and benefit analysis of program activities.

Directs the Secretary of Labor to establish a program to facilitate the establishment of State programs to foster increased employee ownership and greater employee participation in business decisionmaking. Requires the Secretary to establish the Office of Employee Ownership and Participation to support existing State programs and facilitate new State programs, including: (1) making of matching Federal grants; (2) acting as a clearinghouse for information; and (3) facilitating information exchange and promoting State programs. Authorizes appropriations. Requires the Director of the Office of Employee Ownership and Participation to report to the Congress.

solid solutions of quantum paraelectrics exhibit a variety of intriguing properties , which have been attracting scientists for a long period of time @xcite but , in spite of this fact , some important questions remain still under discussion . for example , it is known that the substitution of nb for ta in ktao@xmath0 results in the appearance of a strong temperature dielectric anomaly , which is regarded to a ferrolectric phase transition , but at the temperature of this anomaly and below manifestations of the glass - type behaviour have been often reported . we consider these effects in the framework of a random field approach combined with a percolation theory that includes zero - point quantum vibrations . new experimental data on the dielectric properties of the solid solution ktao@xmath0:nb ( ktn ) with @xmath1 ( ktn 1.8 ) have been obtained and discussed in connection with this problem . the quantum effect results in the following contribution to the soft mode frequency @xmath2 at zero wave vector * k * @xcite @xmath3 where @xmath4 is the bare frequency at zero temperature and zero wave vector , @xmath5 is polarization , @xmath6 is constant , @xmath7 is the impurity concentration , @xmath8 , @xmath9 is a constant responsible for anharmonic interactions , @xmath10 is the unit cell volume , and @xmath11 is the boltzmann constant . just below the phase transition , one can neglect @xmath12 in @xmath13 , due to a large spatial dispersion of the soft mode in ktao@xmath14 , and , in this case , the integral in ( 1 ) is proportional to @xmath15 . thus the temperature dependence of @xmath12 at @xmath16 is : @xmath17 , and at @xmath18 @xmath19 . it is seen that the currie - weiss law is violated not only in a small vicinity above @xmath16 as stressed in earlier studies @xcite but also below @xmath16 . quantum effects can be observed in ktn 1.8 if one suppresses the contribution connected with heterogeneities by applying a field cooling procedure ( see fig 1 ) . in this case a quadratic temperature decrease of @xmath20 is obtained . polarization in quantum ferroelectrics just below @xmath21 should behave as @xmath22 but at lower temperatures polarization should saturate due to the zero - point quantum vibrations @xcite . thus the zero - point quantum vibrations result in the saturation of the host - lattice polarization and dielectric permittivity in ferroelectrics at low temperatures . the above analysis holds only for homogeneous ferroelectrics . in our opinion , ktn 1.8 is not microscopically uniform due to disorder in the impurity ion distribution over the corresponding crystallographic positions @xcite . indeed , since the impurity concentration is very small , the average distance among the impurities is rather large ( e.g. in ktn 1.8 it is about 15.3 a that is about 4 lattice parameters ) . in this case the fluctuations of the average distance can be rather large also that leads to percolative clustering of impurity ions and finally influences the phase diagram of the corresponding solid solutions @xcite . below we will discuss this behavior in terms of the theory of percolation . the impurity ions being close each other are correlated at distances lower than @xmath23 where @xmath24 is proportional to the sum of the energies of the dipole - dipole and elastic impurity impurity interactions . at small impurity concentrations , which we consider in the present study , the impurity clusters can appear only at low temperatures where the cut - off radius is comparatively large . it explains the experiment performed with ktn under high pressure @xcite . when the pressure is normal the phase transition occurs at large temperatures , at which the nb clusters do not appear , and , as a result , a frequency dispersion of the dielectric permittivity is absent . when pressure is applied the soft mode frequency increases and the phase transition temperature is reduced to the region where the nb clusters can already appear ; as a result , there appears a frequency dispersion of the permittivity . the average cluster size @xmath25 for interacting spheres with fixed radii is usually given by a critical dependence @xcite . we consider the case when the interaction radius is temperature dependent . in order to take this fact into account we introduce the following dependence : @xmath26 where @xmath27 is a critical exponent ; @xmath28 is constant and can be calculated on the basis of the percolation theory for different lattices @xcite ( it equals 0.35 in the continual percolation approach ) ; the critical concentration can be found from : @xmath29 it is seen that the critical concentration can be very small if the cut - off radius is large enough . this finding corresponds to experimental data for dilute solid solutions of quantum paraelectrics according to which cluster phenomena appear in them already at a very small impurity concentrations @xcite that is a consequence of a large cut - off radius . note that the cut - off radius can increase not only due to a straight dipole - dipole and quadrupole - quadrupole interactions but also because of an indirect interaction over the soft mode . the latter interaction can even diverge if the soft mode frequency approaches zero but we do not consider this case here ( see @xcite ) . it follows from ( [ x_c ] ) that when the cut - off radius increases this can be considered as an increase of the unit volume ( at constant cut - off radius ) and the effective concentration also increases : @xmath30 . for us it is easier to consider the percolation for spheres with the same ( temperature independent ) radius but with the concentration of the spheres effectively dependent on temperature instead of considering a fixed impurity concentration but varying the sphere radius . in this case a temperature decrease results in an _ increase _ of the effective impurity concentration and due to this a percolation phase transition can happen at some temperature . after the substitution of the temperature dependent cut - off radius value to ( 2 ) one can see that at the phase transition point the average cluster size behaves as @xmath31(where @xmath32 and @xmath33 . the most interesting result is that the critical exponent @xmath27 known in the theory of percolation as the exponent for the critical _ concentration _ dependence coincides with the critical exponent for the critical _ temperature _ dependence . this exponent should be close to @xmath34 as obtained in the theory of percolation that can be a key to decide if the percolation approach is suitable or not to describe concrete experimental data . in reality expression ( [ < s > ] ) is invalid for finite - size heterogeneities . unfortunately there is no analytical description of such a situation although computations showed that the singularity is diffused in this case @xcite . in the vicinity of the singularity one can try using the expression : @xmath35 this expression differs from ( [ < s > ] ) only in a vicinity of the percolation threshold where the critical dependence is replaced by a diffused anomaly . similar to ( [ s_diff ] ) the dielectric permittivity has rather a rounding peak instead of a keen anomaly . it can be explained by reaching the correlation radius the heterogeneity size . the correlation radius , @xmath36 , is the characteristic size of the polarization fluctuation in the lattice . in uniform ferroelectrics , when lowering temperature approaching @xmath16 , this radius increases as @xmath37 . we consider locally nonuniform ferroelectrics in the regime where the main contribution to the dielectric permittivity stems from local heterogeneities ( for example in ktn these are regions enriched with nb ) and where these heterogeneities can be considered , at first glance , as independent . in this case the correlation radius _ is not able to exceed _ the heterogeneity size , which can be defined as the maximal size of the polar regions . it implies that the correlation radius will _ saturate _ at lower temperatures . such a reason for this saturation differs from the zero - point quantum vibrations : _ it is connected with a finite heterogeneity size_. there are different possibilities to interpolate the temperature dependence of the correlation radius described above from the curie - weiss dependence at high temperatures to the constant behavior at low temperatures . earlier we used the barrett formula for this purpose @xcite . it is important to notice that the considered saturation of the correlation radius is a general property of locally heterogeneous ferroelectrics : for example , we believe that it holds in relaxors like pmn . indeed , at temperatures above the burns temperature a curie - weiss behavior was evidenced but below the burns temperature and above the @xmath38 dielectric permittivity maximum temperature rather a quadratic temperature dependence was observed . we have found the following form of the dielectric permittivity suitable in the whole temperature region @xcite @xmath39 where @xmath40 is constant . at temperatures close to @xmath41 this expression gives a quadratic temperature dependence , which has zero derivative at @xmath42 . at high temperatures this expression gives the curie - weiss behavior . it is interesting to notice that the same expression can be considered as a sum of a linear temperature term , @xmath43 , and an inverse temperature term , @xmath44 . hence there is a temperature interval where the correlation radius reaches the heterogeneity size and saturates thereafter ( at lower temperatures ) . in this interval there is a deviation from the curie - weiss law due to the saturation of the correlation radius . additional ( hydrodynamic ) fluctuations appear at these temperatures , which we consider in the next subsection . the main difference of the dielectric response in a nonuniform dielectric media relative the uniform one , besides the appearance of precursors described above in subsection a , is the existence of _ added polarizability _ due to the polar microregions . this new feature of the nonuniform media manifests itself by a very peculiar temperature dependence of the dielectric permittivity below @xmath16 . in fig . 2 we plot the temperature dependence of the inverse dielectric permittivity of ktn 1.8 obtained on heating . it is seen that the low - temperature behavior is given by a straight line , the inclination of which is noticeably lower than one for the high - temperature branch but according to the theory of ferroelectrics @xcite , below @xmath16 , it should be two times larger than above @xmath16 . this contradiction can be explained if one takes into account the saturation of the correlation radius at @xmath21 and a contribution of the polar microregions to the dielectric permittivity below @xmath16 . the latter contribution can originate from ordering of the polar region dipole moments in external field and due to the interactions among the polar regions . indeed , consider random fields * e * ( see for definitions and experimantal studies of the random fields refs . @xcite ) and merged to their directions local dipole moments @xmath45 . in the field @xmath46 , where * * e**@xmath47 is the external field and * p * being the polarization , the dipole moments are directed along * e * + * e*. it results in the following polarization @xmath48 } = \\ \\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\ , = \left\ { { { \begin{array}{*{20}c } { n\mu ( 1 - e^2 / 3e^2 ) } \hfill & { e > e } \hfill \\ { 2n\mu e / 3e } \hfill & { e < e } \hfill \\ \end{array } } } \right . \\ \end{array}\ ] ] where @xmath49 . it follows from this result that the susceptibility of nonineracting polar regions can be found from the expression ( see fig . [ random ] ) : @xmath50 where @xmath51 is the dipole ( heterogeneity ) concentration . the temperature dependence of the dipole moment can be found from the expression : @xmath52 $ ] where @xmath53 is the dipole moment magnitude . this derivation explains the existence of the large contribution to the dielectric permittivity of ktn 1.8 below @xmath16 due to the nb related heterogeneities . in the presence of macroscopic polarization the linear susceptibility depends on the @xmath54 value , which can be found from : @xmath55 and it appears at the condition @xmath56 , which provides @xmath57 . at large @xmath58 the contribution of the polar region dipole moments to the dielectric permittivity rapidly decreases , as @xmath59 . this explains the absence of this contribution in our experimental data when the sample was field cooled . obviously the macroscopic polarization obtained on field cooling is larger than one got on zero field cooling . hence the appearance of macroscopic polarization suppresses the additional contribution connected with the polar microregions . it implies that the new phenomenon seen in the dielectric data of ktn 1.8 at low temperatures can be explained by a very low value of macroscopic polarization appeared on zero field cooling below @xmath16 because of clustering the nb impurities but without the appearance of the connected cluster on the one hand and because of quantum effects leading to suppression of the polarization growth at low temperatures on the other hand . this peculiar situation results in a random distribution of the local polarization over the polar microregions merged to local random field directions and , as a consequence , in an additional contribution to the dielectric permittivity connected with the ordering of the polar region dipole moments . our experimental data show a hysteresis phenomenon at low temperatures , which can be explained within a landau - type theory if one assumes the existence of strong electrostriction interaction in ktn 1.8 in agreement with experimental finding @xcite . the final hamiltonian can be written in the form @xmath60 where @xmath61 , @xmath62 is the electrostriction constant and @xmath63 being the elastic constant . a large value of the electrostriction constant leads to negative values of the nonlinearity constant @xmath64 and , consequently , to the phase transition of the first order . to take into account the scattering of the random field magnitude we used the following distribution function for a reorientable part of the random fields @xcite @xmath65 by integrating ( [ suscept ] ) with this distribution function we obtained at @xmath66 @xmath67\ ] ] it is seen that the bare susceptibility ( [ suscept ] ) decreases with the width of the distribution function ( [ distr ] ) and with polarization @xmath5 . the phase transition in the system consisting of polar regions can be whether of the glass - type or ferroelectric . in order to decide , which type of the phase transition will occur one can employ the percolation technique again but on the next , nanoscale level ( see also a consideration in the framework of a random - field - random - bond model in @xcite ) . one can introduce a cut - off interaction radius for interactions among the polar regions and obtain that if the polar region concentration exceeds a critical concentration then a connected cluster appears and the steady state is ferroelectric but in the reverse case only finite clusters made of polar regions exist and the steady state is of the glass nature . our experimental data show a strong frequency dependence of the dielectric permittivity at @xmath16 . we regard this finding to potential barriers separating different positions of the random fields . for example for li impurities a six - well model can be suitable to describe this situation @xcite . this model considers dipoles embedded into elongated random fields having six possible directions , which provides a description of a phase transition when temperature or field are changed . in the electric field this model gives a critical point . one can consider the random fields coupled to the soft vibrations and these random fields can be polarized by external field according to the distribution function ( [ distr ] ) . the existence of the potential barriers for the local random fields results in the following frequency dependence of the dielectric permittivity @xcite : @xmath68 where @xmath69^{-1}$ ] . we introduced here the cole - cole type frequency dependence bearing in mind a relaxation time distribution . here @xmath62 is a coupling constant . expression ( [ eps - freq ] ) at large temperature above @xmath16 shows the curie - weiss behavior but at low temperatures there is frequency dependent contribution , which is sufficiently enlarged by the coupling of the local random fields with the soft modes . besides the cole - cole contribution to the dielectric permittivity dispersion we have found that even at large temperatures in ktn 1.8 there is universal dispersion of the form @xmath70 with the @xmath51 value only slightly less than 1 ( fig . 4 ) . this frequency dependence can arise because of the existence of nb related heterogeneities or noncentrality even at large temperatures . there can be also some influence of space charge on this dispersion . we showed that the striking dielectric properties of ktn 1.8 can be understood and described on the basis of assumption that in highly polarizable quantum paraelectrics even a small concentration of dipolar impurity centres can form nano - scale polar regions ( clusters ) . the main addition to the dielectric permittivity at high temperatures originates from these local heterogeneities . at high temperatures , when the correlation radius is larger than the heterogeneity radius , the heterogeneities provide a curie - weiss law and an average over the bulk curie temperature governs the temperature dependence of the total dielectric permittivity . when approaching the curie temperature the correlation radius increases but it saturates when reaching the heterogeneity size . together with quantum effects this leads to the appearance of an intermediate state , in which the dielectric permittivity is saturated . the orientation of the cluster dipole moments as well as local random fields in an external field results in the appearance of an additional contribution to the dielectric permittivity in the low temperature ferroelectric phase as it has been observed for ktn 1.8 . we thank nato ( pst . clg.977348 ) 541 , rfbr grants 00 - 02 - 16875 and 01 - 02 - 16029 . v.t . thanks daad for support .

new experimental data on solid solutions of quantum paraelectrics with ktao@xmath0:nb as an example are considered within a framework of a quantum theory of ferroelectric phase transitions . in order to describe the effect of local heterogeneities a percolation type theory together with a random field approach were employed .

SECTION 1. SHORT TITLE. This title may be cited as the ``Tax Lien Simplification Act''. SEC. 2. FINDINGS AND PURPOSE. (a) Findings.--Congress makes the following findings: (1) The present decentralized system for filing Federal tax liens in local property offices, which was established before the advent of modern computers, the Internet, and e-government programs, is inefficient, burdensome, and expensive. (2) Current technology permits the creation of a centralized Federal tax lien filing system which can provide for enhanced public notice of and access to accurate tax lien information in a manner that is more efficient, more timely, and less burdensome than the existing tax lien filing system; which would expedite the release of liens; and which would be less expensive for both taxpayers and users. (b) Purpose.--The purpose of this Act is to simplify and modernize the process for filing notices of Federal tax liens, to improve public access to tax lien information, and to save taxpayer dollars by establishing a nationwide, Internet accessible, and fully searchable filing system for Federal tax liens which would replace the current system of local tax lien filings. SEC. 3. NATIONAL TAX LIEN FILING SYSTEM. (a) Filing of Notice of Lien.--Subsection (f) of section 6323 of the Internal Revenue Code of 1986 is amended to read as follows: ``(f) Filing of Notice; Form.-- ``(1) Filing of notice.--The notice referred to in subsection (a) shall be filed in the Federal tax lien registry operated under subsection (k). The filing of a notice of lien, or a certificate of release, discharge, subordination, or nonattachment of lien, or a notice of withdrawal of a notice of lien, in the Federal tax lien registry shall be effective for purposes of determining lien priority regardless of the nature or location of the property interest to which the lien attaches. ``(2) Form.--The form and content of the notice referred to in subsection (a) shall be prescribed by the Secretary. Such notice shall be valid notwithstanding any other provision of law regarding the form or content of a notice of lien. ``(3) Other national filing systems.--Once the Federal tax lien registry is operational under subsection (k), the filing of a notice of lien shall be governed by this title and shall not be subject to any other Federal law establishing a place or places for the filing of liens or encumbrances under a national filing system.''. (b) Refiling of Notice.--Paragraph (2) of section 6323(g) of the Internal Revenue Code of 1986 is amended to read as follows: ``(2) Refiling.--A notice of lien may be refiled in the Federal tax lien registry operated under subsection (k).''. (c) Release of Tax Liens or Discharge of Property.-- (1) In general.--Section 6325(a) of the Internal Revenue Code of 1986 is amended by inserting ``, and shall cause the certificate of release to be filed in the Federal tax lien registry operated under section 6323(k),'' after ``internal revenue tax''. (2) Release of tax liens expedited from 30 to 20 days.-- Section 6325(a) of such Code is amended by striking ``not later than 30 days'' and inserting ``not later than 20 days''. (3) Discharge of property from lien.--Section 6325(b) of such Code is amended-- (A) by inserting ``, and shall cause the certificate of discharge to be filed in the Federal tax lien registry operated under section 6323(k),'' after ``under this chapter'' in paragraph (1), (B) by inserting ``, and shall cause the certificate of discharge to be filed in such Federal tax lien registry,'' after ``property subject to the lien'' in paragraph (2), (C) by inserting ``, and shall cause the certificate of discharge to be filed in such Federal tax lien registry,'' after ``property subject to the lien'' in paragraph (3), and (D) by inserting ``, and shall cause the certificate of discharge of property to be filed in such Federal tax lien registry,'' after ``certificate of discharge of such property'' in paragraph (4). (4) Discharge of property from estate or gift tax lien.-- Section 6325(c) of such Code is amended by inserting ``, and shall cause the certificate of discharge to be filed in the Federal tax lien registry operated under section 6323(k),'' after ``imposed by section 6324''. (5) Subordination of lien.--Section 6325(d) of such Code is amended by inserting ``, and shall cause the certificate of subordination to be filed in the Federal tax lien registry operated under section 6323(k),'' after ``subject to such lien''. (6) Nonattachment of lien.--Section 6325(e) of such Code is amended by inserting ``, and shall cause the certificate of nonattachment to be filed in the Federal tax lien registry operated under section 6323(k),'' after ``property of such person''. (7) Effect of certificate.--Paragraphs (1) and (2)(B) of section 6325(f) of such Code are each amended by striking ``in the same office as the notice of lien to which it relates is filed (if such notice of lien has been filed)'' and inserting ``in the Federal tax lien registry operated under section 6323(k)''. (8) Release following administrative appeal.--Section 6326(b) of such Code is amended-- (A) by striking ``and shall include'' and insert ``, shall include'', and (B) by inserting ``, and shall cause the certificate of release to be filed in the Federal tax lien registry operated under section 6323(k),'' after ``erroneous''. (9) Withdrawal of notice.--Section 6323(j)(1) of such Code is amended by striking ``at the same office as the withdrawn notice'' and inserting ``in the Federal tax lien registry operated under section 6323(k)''. (10) Conforming amendments.--Section 6325 of such Code is amended by striking subsection (g) and by redesignating subsection (h) as subsection (g). (d) Federal Tax Lien Registry.--Section 6323 of the Internal Revenue Code of 1986 is amended by adding at the end the following new subsection: ``(k) Federal Tax Lien Registry.-- ``(1) In general.--The Federal tax lien registry operated under this subsection shall be established and maintained by the Secretary and shall be accessible to and searchable by the public through the Internet at no cost to access or search. The registry shall identify the taxpayer to whom the Federal tax lien applies and reflect the date and time the notice of lien was filed, and shall be made searchable by, at a minimum, taxpayer name, the State of the taxpayer's address as shown on the notice of lien, the type of tax, and the tax period. The registry shall also provide for the filing of certificates of release, discharge, subordination, and nonattachment of Federal tax liens, as authorized in sections 6325 and 6326, and may provide for publishing such other documents or information with respect to Federal tax liens as the Secretary may by regulation provide under paragraph (2)(C). ``(2) Administrative action.-- ``(A) In general.--The Secretary shall issue regulations or other guidance providing for the maintenance, reliability, accessibility, and use of the Federal tax lien registry established under paragraph (1). Such regulations or guidance shall address, among other matters, issues related to periods during which the registry may be unavailable for use due to routine maintenance or other activities. ``(B) Fees.--The Secretary may charge a taxpayer's account with a reasonable filing fee for each notice of lien and each related certificate, notice, or other filing recorded in the Federal tax lien registry with respect to such taxpayer, in an amount determined by the Secretary to be sufficient to defray the costs of operating the registry. The Secretary may also charge a reasonable fee to any person who requests and receives under section 6323(d)(1) information or a certified copy of a filing in the Federal tax lien registry to defray the costs of providing such information or copies. ``(C) Filing of other items on registry.--The Secretary may, by regulation, provide for the filing of items on the registry other than Federal tax liens, including criminal fine judgments under section 3613 of title 18, United States Code, and civil judgments under section 3201 of such title, if the Secretary determines that it would be useful and appropriate to do so.''. (e) Certified Copies of Information From Registry.--Section 6323 of the Internal Revenue Code of 1986, as amended by subsection (d), is amended by adding at the end the following new subsection: ``(l) Certified Copies of Information From Federal Registry.--The Secretary shall make available in a certificate that can be admitted into evidence in the courts of the United States without extrinsic evidence of its authenticity the following information to any person that submits a request in a form specified by the Secretary: ``(1) Whether there is on file in the Federal tax lien registry operated under subsection (k) at a date and time specified by the Secretary, but not a date earlier than 3 days before the creation of the certificate, any notice of a lien that-- ``(A) designates a particular taxpayer, ``(B) has not been fully satisfied, become legally unenforceable, or been released or withdrawn, and ``(C) if the request so states, has been fully satisfied, become legally unenforceable, or been released or withdrawn, and a record of which is maintained on the registry at the time of filing of the request, ``(2) the date and time of filing of and the information provided in each notice of lien, and ``(3) if the request so states, the date and time of filing of and the information provided in each certificate of release, discharge, subordination, or non-attachment and each notice of withdrawal recorded in the registry with respect to each notice of lien.''. (f) Effective Date; Implementation of Registry.-- (1) Effective date.--The amendments made by this section shall take effect on the date determined by the Secretary of the Treasury under paragraph (2)(E) and, except as provided in paragraph (2)(F), shall apply to notices of liens filed after such date. (2) Implementation of federal tax lien registry.-- (A) Pilot project.--Prior to the implementation of the Federal tax lien registry under section 6323(k)(1) of the Internal Revenue Code of 1986 (as added by this section), the Secretary of the Treasury, or the Secretary's delegate, shall conduct and shall complete by not later than 2 years after the date of the enactment of this Act 1 or more pilot projects to test the accessibility, reliability, and effectiveness of the electronic systems designed to operate the registry. (B) GAO review.--Within 3 months after the completion of such a pilot project, the Government Accountability Office shall provide a written evaluation of the project results and provide such evaluation to the Secretary of the Treasury, the Commissioner of Internal Revenue, and appropriate committees in Congress. The Secretary and Commissioner shall cooperate with, and provide information requested by, the Government Accountability Office to enable the evaluation to be completed by the date specified. (C) Nationwide test.--Upon the completion of 1 or more such pilot projects and after making a determination that the electronic systems designed to operate the Federal tax lien registry are sufficiently accessible, reliable, and effective, the Secretary of the Treasury, or the Secretary's delegate, shall conduct a nationwide test of the Federal tax lien registry to evaluate its capabilities and functionality. (D) Data protection.--Prior to the implementation of such registry, the Secretary of the Treasury, or the Secretary's delegate, shall take appropriate steps to-- (i) secure and prevent tampering with the data recorded in the registry, (ii) review the information currently provided in public lien filings and determine whether any such information should be excluded or protected from public viewing in such registry, and (iii) develop a system, after consultation with the States, industry, and other interested parties, and after consideration of search criteria developed for other public filing systems including Article 9 of the Uniform Commercial Code, that will enable users of the registry, when examining tax lien information for a taxpayer with a common name, to identify through reasonable efforts the specific person to whom such tax lien relates. (E) Declaration of registry effective date.--Upon the successful completion of a nationwide test of the Federal tax lien registry system, the Secretary of the Treasury shall determine and announce publicly a date upon which the registry shall take effect and become operational. (F) Orderly transition.--In order to permit an orderly transition to the Federal tax lien registry, the Secretary of the Treasury may by regulation prescribe for the continued filing of notices of Federal tax liens in the offices of the States, counties, and other governmental subdivisions after the determination of an effective date under subparagraph (E) under the provisions of section 6323(f) as in effect before such effective date, for an appropriate period not to exceed 2 years after such effective date.

Tax Lien Simplification Act - Amends the Internal Revenue Code to revise procedures for the filing of federal tax liens. Direct the Secretary of the Treasury to: (1) establish and maintain a federal tax lien registry, in lieu of filing tax liens in local jurisdictions, which would be accessible to and searchable by the public through the Internet at no cost; (2) take appropriate steps to secure and prevent tampering with the data recorded in the registry; and (3) review the information in the registry to determine whether information in the registry should be excluded or protected from public viewing. Establishes the priority of a federal tax lien based upon the date and time of the filing of a notice of lien in the federal tax lien registry. Reduces the period for releasing satisfied or unenforceable tax liens from 30 to 20 days.

due to the analogies between the nuclear forces and the van - der - waals interaction , the nuclear matter equation of state ( eos ) foresees the possible occurrence of phase transitions from the liquid to the vapour phases @xcite . already in the 80 s , these phenomena were linked to the experimentally observed multifragmentation mechanism , i.e. the sudden break up of an excited nuclear system into many pieces @xcite . however , in the search for signatures of a phase transition , one has to consider that nuclei are finite systems . new features may appear in addition to standard thermodynamics . moreover , the nuclear phase diagram is explored with the help of nuclear reactions , where out - of - equilibrium effects may also be present . these considerations have lead , from one side , to significant developments of the thermodynamics of finite systems and to new definitions of the phase transition , following the concepts of statistical physics @xcite . on the other hand , many efforts have been devoted to the study of the reaction dynamics and to the characterization of the fragmentation mechanism , also in connection with the possible appearance of the signals expected for a phase transition at thermodynamical equilibrium @xcite . it is generally believed that , in a heavy ion collision at fermi energies , due to the initial compression and/or thermal excitation , the composite nuclear system may expand and reach density and temperature values inside the co - existence region of the nuclear matter phase diagram @xcite . in violent collisions multifragment configurations are characterized by a large degree of chaoticity and a huge amount of the available phase space is populated . finally several features observed in the exit channel can be related to the thermodynamical ( equilibrium ) properties of phase transitions in finite systems , independently of the specific mechanism that has driven the whole process @xcite . however , there remain some aspects that reflect the nature of the reaction dynamics and of the fragmentation path , mostly related to out - of - equilibrium effects . indeed the interplay between the compression - expansion dynamics and the onset ( and nature ) of clusterization affects significantly the fragment kinematical properties and the appearance of collective flow effects . a thorough study of this dynamics also allows one to access information on the nuclear matter compressibility . moreover , the specific features of the fragmenting source , such as its mass , charge and excitation energy , are also strongly depending on the pre - equilibrium dynamics and on the time instant where clusterization sets in . hence , a quantitative understanding of multifragmentation data requires a careful investigation of the whole dynamical path . due to the complexity of the nuclear many - body problem , two main lines of approximations have been followed so far . on one side , the class of molecular dynamics ( md ) approaches employ , to represent a many - body state , a product of single - particle states , with or without antisymmetrization , where only the mean positions and momenta are time dependent @xcite . in almost all these approaches , the width is fixed and is the same for all wave packets . the use of localized wave packets induces many - body correlations ( analogous to those in classical dynamics ) in the particle propagation in the nuclear field , as well as in hard two body scattering , that is treated stochastically . on the other side , mean - field approaches ( and stochastic extensions ) follow the time evolution of the one - body distribution function ( the semi - classical analog of the wigner transform of the one - body density matrix ) , according to approximate equations where higher order correlations are neglected ( mean - field approximation ) , apart from the correlations introduced by the residual two - body collisions . in the stochastic extension of the model , a fluctuation source term is added to the average collision integral , to account for the stochastic nature of two - body scattering @xcite . a comparison of the predictions given by models of the two classes , concerning multifragmentation scenarios at fermi energies ( 30 - 50 mev / nucleon ) , has been recently undertaken @xcite . the models considered are : the stochastic mean - field ( smf ) model including momentum dependence @xcite and the antisymmetrized molecular dynamics ( amd ) model @xcite . it was observed that , while in the smf case fragment emission is more likely connected to the spinodal decomposition mechanism , i.e. to mean - field instabilities , in the amd approach many - body correlations have a stronger impact on the fragmentation dynamics , leading to the earlier development of density and momentum fluctuations . in the present paper we will discuss quantitatively the impact of the different approximations employed in the two models on several particle and fragment observables of experimental interest . this also allows one to establish up to which extent some of the observed features may be considered as more robust or general , i.e.not much depending on the details of the fragmentation path and of the models under consideration . by studying reactions with neutron - rich systems , we also investigate isospin observables , in connection to the density dependence of the symmetry energy and the underlying reaction dynamics . in both smf and amd approaches , the time evolution of the system is described in terms of the one - body distribution function @xmath0 ( or a slater determinant ) , as ruled by the nuclear mean - field ( plus coulomb interaction for protons ) and the residual interaction , i.e. hard two - body scattering . the equation can be represented in the form of so - called boltzmann - langevin equation @xcite @xmath1,f\ } + i[f ] + \delta i[f ] , \label{bl}\ ] ] where the coordinates of spin , isospin and phase space are not shown for brevity . @xmath2 $ ] is the self - consistent one - body hamiltonian , @xmath3 $ ] is the average two - body collision integral , and @xmath4 $ ] stands for the stochastic source term @xcite . the effect of the stochastic term @xmath4 $ ] is considered for the value of the distribution function @xmath5 in each phase space cell @xmath6 . for example , one may decompose the phase space into square cells of the volume @xmath7 . in the case of local equilibrium , the source term @xmath4 $ ] induces the fluctuation of @xmath5 , the variance of which is given by @xmath8 . the correlations between different cells are usually assumed to be small , but minimal correlations are introduced for the conservation laws . in the approximate treatment of smf presented in @xcite , the fluctuations are projected and implemented only onto the ordinary space , agitating the spatial density profile from time to time during the reaction after the local thermal equilibrium is reached . it should be noted that the variance @xmath8 with the average value @xmath5 is achieved by choosing @xmath9 and 0 with the probabilities @xmath5 and @xmath10 , respectively . namely the fluctuation will choose @xmath11 fully occupied phase - space cells , with @xmath11 being the number of nucleons in the system , while the remaining part of phase space becomes empty . amd represents this situation by using gaussian wave packets @xmath12 ( @xmath13 ) . each wave packet has the minimum uncertainty @xmath14 and therefore can be regarded as a phase space cell . the width parameter @xmath15 defines the shape of the cell in phase space . in amd , the right hand side of eq . ( [ bl ] ) is usually decomposed in a different way for the convenience in writing a stochastic equation for the wave packet centroids . the mean field effect is decomposed to the motion of the centroids and the change of the shape of the one - body distributions : @xmath16 . the first term @xmath17 is calculated by employing the fully antisymmetrized wave function @xcite , while @xmath18 is approximately calculated by using a test particle method @xcite . the stochastic source term is also separated as @xmath19 . the part @xmath20 is the stochastic effect included in the stochastic collisions ( @xmath21 ) , that move the centroids of the wave packets by choosing the scattering angle randomly . when a nucleon collides with another , @xmath22 randomly selects a gaussian wave packet from the single - particle state , that has been changing its shape according to @xmath18 , by splitting it into possibilities of gaussian wave packets ( quantum branching or decoherence ) @xcite . thus the main difference between the two models lies in the implementation of the stochastic term , i.e. , whether the fluctuation in the momentum space is integrated out ( in smf ) or not ( in amd ) . moreover , in amd , when a collision happens , two entire nucleons are moved to new wave packets in phase space , while it is not necessarily the case in smf . therefore the fluctuation is expected to have stronger impact on the collision dynamics in amd than in smf . the isospin and momentum dependent effective interaction employed in the smf model is derived via an asymmetric extension of the gbd force @xcite , leading to the bgbd potential @xcite . in the amd model , we employ the gogny interaction which are composed of finite - range two - body terms and a zero - range density - dependent term . the corresponding nuclear matter eos can be written as @xmath23 where the variable @xmath24 defines the isospin content , being @xmath25 ( @xmath26 = n , p ) the neutron or proton density and @xmath27 the total density . we use a soft equation of state for symmetric nuclear matter ( compressibility modulus @xmath28 mev for bgbd and @xmath29 mev for the gogny force ) . in fig . [ eos ] we report the eos , as a function of the density @xmath27 , for symmetric nuclear matter , @xmath30 , at zero temperature . we can easily adjust the parameters of the interaction in order to change the density dependence of symmetry energy ( @xmath31 ) without changing the eos of symmetric nuclear matter . the density behaviour of the symmetry energy , @xmath32 , is shown in fig . we remind that this quantity gets a kinetic contribution directly from basic pauli correlations and a potential part from the highly controversial isospin dependence of the effective interactions @xcite . for the bgbd force , we adopt two different parametrizations of the symmetry energy : `` asy - soft '' , that gives a flat behaviour around normal density , followed by a decreasing trend at large density , and `` asy - stiff '' , where the symmetry energy exhibits an almost linear increase with density @xcite . the gogny ( d1 ) force @xcite has a quite similar @xmath32 to the `` asy - soft '' parametrization of bgbd , while another parametrization @xcite of the gogny force has @xmath32 similar to the `` asy - stiff '' version of bgbd . hence , in the following we will use the labels `` asy - soft '' and `` asy - stiff '' for the gogny forces as well . 0.5 cm 1.cm within the considered form of the nuclear interaction , the isovector terms depend explicitely on the nucleon momentum @xmath33 , leading to the splitting of neutron and proton effective masses . the mean - field potential felt by neutrons and protons in asymmetric nuclear matter ( @xmath34 ) is presented in fig . 3 , as a function of the momentum @xmath35 , for three density values and for the adopted interactions ( asy - soft and asy - stiff ) . as an effect of the momentum dependence , the difference between neutron and proton potentials decreases with @xmath35 , becoming negative at high momenta , especially in the asy - soft case . this corresponds to the proton effective mass being smaller than the neutron one in neutron - rich matter . moreover , one can see that the difference between neutron and proton potentials is larger , at low density , in the asy - soft case , corresponding to the larger value of the symmetry energy ( see fig . [ esy ] ) , while the opposite holds above normal density . the results of the bgbd and gogny forces look very close to each other below and around the fermi momentum , for both neutrons and protons . however , due to the different shape of the momentum dependence in the bgbd interaction , with respect to the gogny force , at high momenta ( @xmath36 ) potential are less attractive in the bgbd case . this discrepancy should not affect our comparison since we are interested in reactions at fermi energies . ) at density @xmath37 ( panels ( a ) and ( b ) ) , @xmath38 ( panels ( c ) and ( d ) ) , @xmath39 ( panels ( e ) and ( f ) ) , as a function of the momentum @xmath35 . full lines correspond to the gogny forces while dashed lines are for the bgbd forces . left panels : asy - soft interaction . right panels : asy - stiff . ] as the two - nucleon collision cross sections ( @xmath40 and @xmath41 ) , we use the energy- and angle - dependent values in the free space with the maximum cut - off of 150 mb in both smf and amd calculations . we have confirmed that the degree of stopping reached in the reaction is similar for both calculations @xcite . however , it should be noticed that these cross sections are larger than those adopted by the amd calculation in ref . @xcite . 0.5 cm in the smf model , the reaction products are reconstructed by applying a coalescence procedure to the one - body density @xmath42 , i.e.connecting neighboring cells with density @xmath43 ( `` liquid '' phase ) . in this way one can also identify a `` gas '' phase ( @xmath44 ) , associated with particles that leave rapidly the system ( pre - equilibrium emission ) and/or are evaporated . once fragments are identified , from the knowledge of the one - body distribution function , it is possible to calculate their mass , charge and kinematical properties . this provides reasonable results for the description of the ground state of medium - heavy nuclei and for excited primary fragment properties . fragment excitation energies are calculated by subtracting the fermi motion , evaluated in the local density approximation , from the fragment kinetic energy ( taken in the fragment reference frame ) @xcite . in the amd model , for the state at a given time of the reaction , fragments are recognized by connecting two wave packets if the spatial distance between their centroids is less than @xmath45 . when fragments are recognized at a late time , such as @xmath46 fm/@xmath47 , we take @xmath48 fm , though the result does not depend on the choice except for extreme choices . when fragments are recognized at early times in order to characterize the dynamical evolution of the reaction , different choices of @xmath45 define different observables . we take a relatively small value of @xmath49 fm in figs . [ pre_eq_124 ] , [ pre_eq_112 ] , [ nzgas ] and [ z_a_liq ] , which allows an earlier recognition of particle emissions . alternatively , we can employ the same fragment recognition method that is applied to the smf calculation by applying a coalescence procedure to the density distribution @xmath50 calculated for the amd wave function . we have confirmed that the result well agrees with the usual method with @xmath48 fm for fragment charge distributions ( i.e. , for the separation of fragments ) , while the choice of @xmath49 fm better agrees with the coalescence procedure for the light particle emissions ( i.e. , for the separation of `` liquid '' and `` gas '' ) at early times . we discuss some features of the fragmentation path followed in violent collisions at fermi energies , as predicted by the smf and the amd models . to investigate isospin effects and the sensitivity of the results to the parametrization adopted for the symmetry energy , we will simulate central collisions of a neutron - poor and a neutron - rich system : @xmath51sn + @xmath51sn and @xmath52sn + @xmath52sn , at 50 mev / nucleon . within our study of fragmentation reactions , we expect to test the low - density behaviour of the symmetry energy . as we will see in the following , the isospin degree of freedom can also be used as a good tracer of the reaction dynamics . an ensemble of about 100 trajectories has been collected for both model calculations . the impact parameter has been set equal to 0.5 fm and the initial distance between the two nuclei ( at the time @xmath53 ) is 15 fm . density contour plots in the reaction plane , as obtained in the two models for one event of the @xmath51sn + @xmath51sn reaction , are shown in fig . [ contour_bgbd ] at several time steps . as one can see from the figure , for this kind of reactions , both models predict that the system is initially compressed . then expansion follows and multi - fragment breakup is observed . one can also observe that the expansion is faster in amd and that the amount of emitted nucleons ( the `` gas '' phase ) is larger in smf . .,title="fig : " ] 1.cm .,title="fig : " ] 0.5 cm in this section we summarize the main findings of ref . @xcite , concerning the trajectory followed by the system in the early stage of the dynamics , until fragmentation is observed . the reaction path can be characterized with the help of one - body observables , such as the radial density profile and the radial collective momentum . the radial density at a given distance @xmath54 is obtained by averaging the local density @xmath42 over the surface of a sphere of radius @xmath54 . the radial collective momentum is the projection of the collective momentum at the position @xmath55 along the radial direction , averaged over the surface of the sphere of radius @xmath54 . these quantities are further averaged over the ensemble events . in the smf calculations ( see fig . 5(a ) ) the behaviour of the radial density profile indicates that , after an initial compression ( t = 40 fm / c ) , the system expands and finally it gets rather dilute , due to the occurrence of a monopole expansion , generated by the initial compression . the matter appears mostly concentrated within a given interval of the radial distance ( see for instance the results at t = 100 fm / c ) , indicating the formation of bubble - like configurations ( see also fig . [ contour_bgbd ] ) , where fragments will appear , and the central region of the system is rapidly depleted . in amd calculations , the density profile in fig . 5(b ) shows the time evolution of the compression and expansion which is qualitatively similar to the smf case . however , we notice that amd shows broader average density distribution than smf as the system expands , pointing to a faster expansion in the amd , as indicated qualitatively by fig . [ contour_bgbd ] . this is confirmed also by the behavior of the collective momentum . an shown in ref . @xcite , in the smf case , after the development of an almost self - similar radial flow , the collective momentum decreases again at the surface of the system , indicating the occurrence of a counter - streaming flow , from the surface towards the interior , trying to recompact the system @xcite . correspondingly a bump is obtained in the radial density distribution ( see fig . 5(a ) at t = 100 fm / c ) . on the other hand , the collective momentum at the surface of the expanding system keeps almost unchanged in the amd calculations @xcite . the absence of deceleration effects may indicate that the system ceases to behave as homogeneous while it expands , corresponding to the situation , of rather low average density , in which fragments have already appeared and are distributed widely in space . this scenario is supported by the analysis of the density fluctuation variance , that reveals an earlier growth of density fluctuations ( leading to an earlier appearance of clusters ) in the amd case @xcite . this can be interpreted as the reason of the faster expansion in amd as observed in fig . [ contour_bgbd ] at later times . we notice that early fragment formation is observed also in other n - body treatments , belonging to the class of molecular dynamics models , as shown by the quasi - classical calculations performed in ref . @xcite . in conclusion , while in the smf case the system spends more time , as a nearly homogeneous source , at low density and fragments are formed most likely through the spinodal mechanism @xcite , in the amd case clustering effects may be present at an earlier stage . this influences significantly also the amount of particles emitted prior to fragment formation ( pre - equilibrim emission ) , as discussed in the following . , in the case of the reaction @xmath56 . dashed line : asy - soft parametrization . full line : asy - stiff parametrization . the dot - dashed lines represent the time evolution of the total number of neutrons and protons contained in emitted particles with @xmath57 , for the asy - soft parametrization . left panel : smf results . right panel : amd results . ] 1.0 cm , for the system @xmath58.,title="fig : " ] during the first stage of the reaction , hard two - body scattering plays an essential role and pre - equilibrium emission is observed , i.e. nucleons and light particles are promptly emitted from the system . this stage influences significantly the following evolution of the collision . in fact , the amount of particles and energy removed from the system affects the properties of the composite source that eventually breaks up into pieces . hence , when discussing multifragmentation mechanisms , a detailed analysis of this early emission is in order . figs . [ pre_eq_124 ] and [ pre_eq_112 ] show the time evolution of the total number of neutrons and protons contained in emitted nucleons and light particles , with mass number @xmath59 , as obtained in the two models , with the two asy - eos considered , and for the two reactions . it should be noticed that this ensemble is mainly composed of unbound nucleons in the smf case . as shown in these figures , these particles leave the system mostly in the time interval between @xmath60 fm/@xmath47 and @xmath61 fm/@xmath47 . at later times the emission rate is reduced ( see the change of slope in the lines of figs . [ pre_eq_124 ] and [ pre_eq_112 ] . as already pointed out in ref . @xcite , a striking difference between the two models concerns the amount of particles emitted , that is larger in the smf case . however , the average kinetic energy of this emission is similar , being 20.72 mev / nucleon in smf and 21.95 mev / nucleon in amd . the difference observed in the two models could be connected to the fact that clustering effects and many - body correlations are more efficient in amd , due to the nucleon localization , reducing the amount of mass that goes into free nucleons and very light clusters . this effect is connected also to the different compression - expansion dynamics in the two models , as discussed in the previous section . on the other hand , light imf s , with mass number @xmath62 , are more abundant in amd . this is observed in fig . [ pre_eq_124 ] , where the total amount of neutrons and protons contained in emitted particles with @xmath63 is also displayed as a function of time , in the case of the asy - soft interaction ( see the dot - dashed lines ) . in the amd case , the emission of light imf s starts already at around 70 fm/@xmath64 and , at the time t = 250 fm/@xmath47 , it represents a noticeable fraction of the particles emitted in the considered mass range ( @xmath63 ) , see the difference between dot - dashed and dashed lines . hence fragments are formed on shorter time scales in amd , on about equal footing as light - particle pre - equilibrium emission , while in smf this light imf emission sets in at later times and is much reduced . however , one can see that the total amount of emitted nucleons belonging to particles with @xmath63 ( including free nucleons ) is close in the two models ( compare the dot - dashed lines at the final time in the left and right panels of fig . [ pre_eq_124 ] ) . hence one expects to see a similar production of imf s with charge @xmath65 , as it will be discussed in the following . as general features , when comparing the two reactions ( fig . [ pre_eq_124 ] and fig . [ pre_eq_112 ] ) , it is seen that neutron ( proton ) emission is more abundant in the neutron - rich ( poor ) systems . moreover , figs . [ pre_eq_124 ] and [ pre_eq_112 ] also show that a larger ( smaller ) number of neutrons ( protons ) is emitted in the asy - soft case , as compared with the asy - stiff case , corresponding to a larger repulsion of the symmetry potential for the soft parametrization . this can be taken as an indication of the fact that pre - equilibrium particles are mostly emitted from regions that are below normal density ( i.e. after @xmath66 fm / c , during the expansion phase ) , where the symmetry energy is higher in the soft case ( see fig . 2 ) . now we move to discuss and compare the properties of primary fragments , as obtained in the two models . in fig . [ char_distri ] we present the charge distribution of primary imf s ( @xmath67 ) at two time instants : @xmath68 and 300 fm/@xmath47 . 1.0 cm , at @xmath68 fm/@xmath47 ( left ) and @xmath69 fm/@xmath47 ( right).,title="fig : " ] 1.0 cm between the fragment yield observed in the angular domain @xmath70 ( rescaled by a factor 2 ) and the total yield , as a function of the fragment charge , evaluated at @xmath71 fm/@xmath47 for the same system of fig . [ char_distri ] . notations are the same as in fig . [ char_distri].,title="fig : " ] some of the fragments identified by the clustering procedure at @xmath68 fm/@xmath47 have exotic ( elongated ) shapes and they break - up into pieces at later times . this effect is present in both models and explains the difference observed between the charge distributions calculated at @xmath68 and @xmath69 fm/@xmath47 . in the smf case the maximum yield corresponds to fragments having charge around @xmath72 , as expected within a fragmentation scenario associated with spinodal decomposition @xcite . the fragmentation mechanism may be connected also to the small yield of the light imf s that , as also discussed in section iii.b , is lower in smf , compared to amd . hence the total mass that belongs to the `` liquid '' phase ( imf s ) is reduced in smf . this is the counterpart of the more abundant pre - equilibrium emission . the production of sizeable clusters ( @xmath73 ) looks closer in the two calculations . this is true especially at @xmath69 fm/@xmath47 , where the tail at large @xmath74 , that is observed at @xmath68 fm/@xmath47 and is more pronounced in amd calculations , disappears . however , the emission of fragments with charge around 10 is slightly larger in smf , while bigger fragments ( with charge around 15 - 20 ) are more abundant in amd . it should be noticed that these differences may be smoothened by the secondary decay process , see the results of ref.@xcite for smf and ref.@xcite for amd . fragments are nearly isotropically distributed in space , in both models . this is shown in fig . 9 , where we display the ratio , @xmath75 , between the fragment yield observed in the angular domain @xmath70 ( rescaled by a factor 2 ) and the total yield , as a function of the fragment charge . apart from fluctuations of statistical origin , we notice a lack of small fragments in the selected angular domain in the smf case , pointing to a slightly lower degree of stopping , compared to amd , as also discussed in ref . we would like to stress that , especially in the case of smf calculations , the degree of stopping reached in the collision is crucial in determining the following reaction path . indeed , if the reaction time becomes too short , spinodal instabilities would not have enough time to develop @xcite . 1.0 cm , at @xmath69 fm/@xmath47 . full lines : imf s with charge @xmath67 are considered . dashed lines : imf s with charge @xmath73 are considered.,title="fig : " ] the larger total mass of the `` liquid '' phase obtained in amd is reflected also in the imf multiplicity , that is shown on fig . [ mult_distri ] . in fact , the multiplicity of imf s with charge @xmath76 is larger in amd . however , if one selects only sizeable fragments , with charge @xmath77 , closer multiplicities are obtained in the two models ( dashed lines ) , but still higher ( by about 1 unit ) in the amd case . this difference may be expected from the fact that the total number of nucleons contained in these imf s in amd is still larger by about 15 than in smf ( compare dot - dashed lines in fig . 1.0 cm fm/@xmath47 ( dashed lines ) and at @xmath78 fm/@xmath47 ( full lines ) , for the same reaction of fig . [ char_distri ] . the solid and hatched grey areas mark the change during this time interval for amd and smf , respectively . , title="fig : " ] as discussed above , the average kinetic energy of nucleons emitted at the pre - equilibrium stage of the reaction is nearly the same in the two codes . however , the larger amount of nucleons emitted in smf causes a considerable reduction of the energy available for the remaining fragmenting system . as a consequence , the energy ( kinetic + internal ) stored into imf s results to be larger in amd . more precisely , the fragment intrinsic excitation energy is close in the two models and amount to @xmath79 mev ( corresponding to temperatures @xmath80 mev ) , while according also to the different compression - expansion dynamics ( see section iii.a ) , the fragments have higher collective velocities in amd . the fragment average kinetic energy is represented as a function of the fragment charge in fig . [ ene_kin ] . the dashed lines correspond to the time instant @xmath68 fm/@xmath47 , while full lines are for fragments at @xmath78 fm/@xmath47 , where they have been accelerated by the coulomb repulsion . one can notice that in the amd case , these coulomb acceleration effects are not so pronounced , since fragments are rather distant from each other already at @xmath68 fm/@xmath47 ( see fig . [ contour_bgbd ] ) . the shape of the average kinetic energy , with an almost linear increase up to charges around @xmath81 , denotes the presence of a collective flow velocity , as also experimentally observed in similar reactions @xcite . fragments with larger size , that probably emerge from the coalescence of two or more smaller objects and are more likely located closer to the system center of mass , are slowed down . the difference between the final average kinetic energy per nucleon in the two models amounts to @xmath82 . it is very interesting to investigate also the isotopic content of pre - equilibrium and fragment emission , in connection with the asy - eos employed and the details of the dynamical models under investigation . differences between the two models are seen not only for the abundance of the pre - equilibrium emission , but also for its isotopic content . this is illustrated in fig . [ nzgas ] , that shows the time evolution of the @xmath83 ratio of emitted particles with @xmath59 , in both models , for the two iso - eos s and the two reactions considered . the different calculations present some common features . in fact , we observe in all cases that the two curves of different asy - eos s cross at times @xmath84 around 70 - 100 fm / c , which is more evident for the neutron - rich system . according to the compression - expansion dynamics followed by the composite nuclear system , the crossing is connected to the fact that the system gradually evolves from a compact shape ( compression , high density ) where the symmetry energy is larger and the system likes to emit more neutrons in the asy - stiff case , to a dilute configuration ( expansion , low density ) where the symmetry energy is larger in the asy - soft case . 1.0 cm content of the pre - equilibrium emission , as obtained in the two models ( left and right panels ) , for the @xmath85 and @xmath56 reactions . full lines : asy - stiff interaction . dashed lines : asy - soft.,title="fig : " ] 1.0 cm and @xmath56 reactions . full lines : asy - stiff interaction . dashed lines : asy - soft.,title="fig : " ] the results of fig . [ nzgas ] can be connected to the differences observed along the compression - expansion dynamics in the two models . in fact , as discussed in section iii.a , within the smf trajectory the composite nuclear system may enter lower density regions as a nearly homogeneous source and for a longer time , compared to the path followed in amd . hence the moderate @xmath83 of the pre - equilibrium emission observed in smf can be explained by the rather small value of the symmetry energy at lower density . this explanation is also consistent with the more abundant emission obtained in smf calculations , since particles are less bound at low density . on the other hand , the @xmath83 ratio in the amd case is much larger , especially for the neutron - rich @xmath86 reaction . due to the efficient clustering effects in amd , protons are trapped in fragments that appear at early times , optimizing the symmetry energy of the whole system . the same isospin effects can be also observed by looking at the isotopic content of fragments . figure [ z_a_liq ] shows the @xmath87 content of the `` liquid '' phase ( associated with the composite nuclear source at early times and with imf s at later times ) , as obtained in the two models and with the two parametrizations of the symmetry energy . as expected already from the results concerning nucleon and light cluster emission , the `` liquid '' is more neutron - rich in smf . one can notice that , for the neutron - poor system in fig . [ z_a_liq ] , the @xmath87 ratio starts to increase at early times , which is due to the repulsive effect of the coulomb interaction and is related to the observation in fig . [ nzgas ] that @xmath83 is smaller than the @xmath88 ratio of the total system . this increasing trend of @xmath87 is more pronounced in the smf model , due to the more abundant emission in this case . for the neutron - rich system , the initial increase of @xmath87 is weak and observed only in the smf case . the @xmath87 ratio turns to decrease approximately when fragments appear and neutrons are emitted , lowering the fragment symmetry energy ( isospin distillation @xcite ) . this effect is more pronounced in the soft case and happens at earlier times in amd . moreover , isospin distillation is stronger in the neutron - rich system . at the end , one can see from figs . [ nzgas ] and [ z_a_liq ] that the difference between the predictions of the two models is larger than the difference between the results associated with the two iso - parametrizations . this observation should be taken as a warning that the symmetry energy can not be extracted from merely the @xmath88 content of the reaction products in a model independent way . in this paper we have undertaken a quantitative comparison of the features observed in heavy - ion fragmentation reactions at fermi energies , as predicted by two transport models : smf and amd . as far as observables of experimental interest are concerned , one significant discrepancy between the two models is connected to the amount of pre - equilibrium emission , i.e. the energetic particles that leave the system at the early stage of the reaction . in amd clustering effects appear to be more relevant , reducing the amount of free nucleons emitted , compared to smf , in favour of a richer production of primary light imf s . the yield of sizeable primary imf s ( @xmath73 ) is close in the two models . however in smf fragments with charge around 10 are slightly more abundant , while in amd the tail at larger @xmath74 ( around 20 ) is more pronounced . the shape of the smf charge distribution is closer to the expectations of spinodal decomposition @xcite . however , it should be noticed that these differences can be smoothened by secondary decay effects @xcite . in fact , both models are able to fit ( final ) experimental charge distributions ( of imf s ) reasonably well @xcite . in smf fragment kinetic energies are smaller , compared to amd , by about 20@xmath89 . these observations corroborate the scenario of a faster fragmentation process in amd , while in smf the system spends a longer time as a nearly homogeneous source at low density , emitting a larger amount of nucleons prior to fragment formation . another interesting feature is that the @xmath88 ratio of the pre - equilibrium emission and of primary imf s is different in the two models . for a fixed parametrization of the symmetry potential , the isotopic content of the emitted particles is systematically lower in smf , where the emission is more abundant . as a consequence , imf s are more neutron - rich in smf than in amd . the latter observation leads to the conclusion that isotopic properties are largely affected by the reaction dynamics . this can be expected just from the fact that the symmetry energy is density dependent , so isospin observables should keep the fingerprints of the density regions spanned in the collision . however , the impact of the reaction path on these observables may be more intricate . from this point of view , isospin properties can be also considered as a good tracer of the reaction mechanism and may contribute to probe the corresponding fragmentation path . hence , the discrepancy between the two models may be ascribed essentially to the different compression - expansion dynamics and clusterization effects that , as shown by our results , affect isoscalar as well as isovector properties of the reaction products . therefore , the simultaneous analysis of several experimental observables in nuclear reactions at fermi energies should help to shed light on the underlying fragmentation mechanism and the corresponding role of mean - field and many - body correlations . in other words , a check of the global reaction dynamics could be a way to test the validity of the approximations employed in the dynamical models devised to deal with the complex many - body problem . one may look at suitable isoscalar observables such as fragment and particle yields and energy spectra , as well as at the isotopic content of the reaction products . as shown in fig . 6 , the sharing between the yields of light imf s and light particles ( @xmath59 ) is rather different in the two models , the latter being more abundant and less neutron - rich in smf . in particular , the study of pre - equilibrium emission , which is not influenced by secondary decay effects , could really help to probe the reaction dynamics , since the difference between amd and smf predictions is rather large , see the results of fig.s 6,7,12 . only when the model reliability has been established , one may undertake a deeper investigation of isospin observables , from which more detailed information on the symmetry energy and its density dependence can be accessed . indeed , as shown in fig.s 12 - 13 , the differences between predictions corresponding to two commonly employed symmetry energy parametrizations are smaller than the differences associated with the two models considered here . finally , it would be appealing to extend our comparison of multi - fragmentation reactions to other approaches introduced to follow the many - body dynamics @xcite . in such a context , new developments of stochastic mean field models , in the direction of introducing fluctuations in full phase space @xcite and enhancing the role of correlations , are also of interest . we thank m.di toro for useful comments and discussions . we also would like to acknowlegde the european center for theoretical studies in nuclear physics and related areas ( ect * , trento , italy ) for inspiring discussions during workshops on numerical simulations of heavy ion reactions . this work is supported by grant - in - aid for scientific research ( kakenhi ) 21540253 from japan society for the promotion of science , and partly by high energy accelerator research organization ( kek ) as a supercomputer project . b. borderie , m.f . rivet , progr . in part . and nucl . phys . * 61 * ( book series ) , 551 ( 2008 ) . bowman , g.f . peaslee , r.t . desouza , et al . rev . lett . * 67 * , 1527 ( 1991 ) g. bertsch and p.j . siemens , phys . b126 * , 9 ( 1983 ) ph . chomaz and f. gulminelli , nucl . phys . * a647 * , 153 ( 1999 ) p. chomaz , f. gulminelli , eur . phys.j . * a30 * , 317 ( 2006 ) j.b . elliott et al . , phys . lett . * 88 * , 042701 ( 2002 ) m. dagostino et al . , nucl . phys . * a699 * , 795 ( 2002 ) g. tabacaru et al . , eur . phys.j . * a18 * , 103 ( 2003 ) h. s. xu _ et al . 85 * , 716 ( 2000 ) . e. geraci _ et al . _ , nucl . phys . * a732 * , 173 ( 2004 ) . t. furuta , a. ono , phys . rev . * c79 * , 014608 ( 2009 ) a.h . raduta , m.colonna , v.baran and m.di toro , phys . rev . * c74 * , 034604 ( 2006 ) ; a.h . raduta , m.colonna , m.di toro , phys . rev . * c76 * , 024602 ( 2007 ) a. ono , phys . rev . * c59 * , 853 ( 1999 ) j. aichelin , phys . rep . * 202 * , 233 ( 1991 ) h. feldmeier , nucl . a515 * , 147 ( 1990 ) . a. ono , h. horiuchi , toshiki maruyama and a. ohnishi , phys . * 68 * , 2898 ( 1992 ) ; a. ono , h. horiuchi , toshiki maruyama and a. ohnishi , prog . . phys . * 87 * , 1185 ( 1992 ) . m. papa , t. maruyama , a. bonasera , phys . rev . * c64 * , 024612 ( 2001 ) m. colonna and ph . chomaz , phys . b436 * , 1 ( 1998 ) . n. wang , z.x . wu et al . , phys . rev . * c69 * , 034608 ( 2004 ) . s. ayik , c. gregoire , phys . lett . * b212 * , 269 ( 1998 ) , and refs . therein . j. randrup and b. remaud , nucl . * a514 * , 339 ( 1990 ) j. rizzo , p. chomaz , m. colonna , nucl . phys . * a806 * , 40 ( 2008 ) j.rizzo , m.colonna , a.ono , phys . rev . * c76 * , 024611 ( 2007 ) j. rizzo , m. colonna , m. di toro , v. greco , nucl.phys . * a732 * , 202 ( 2004 ) , and refs . therein . a. guarnera , m. colonna . chomaz , phys . lett . * b373 * , 267 ( 1996 ) a. ono , s. hudan , a. chbihi , j. d. frankland , phys . rev . * c66 * , 014603 ( 2002 ) . a. ono and h. horiuchi , prog . * 53 * , 501 ( 2004 ) . c.gale , g.f.bertsch , s.das gupta , phys.rev . * c41 * , 1545 ( 1990 ) . v. greco , diploma thesis ( 1997 ) ; + v. greco , a. guarnera , m. colonna , m. di toro , phys.rev . c59 , 810 ( 1999 ) ; + nuovo cimento * a111 * , 865 ( 1998 ) , eds . bao - 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we undertake a quantitative comparison of multi - fragmentation reactions , as modeled by two different approaches : the antisymmetrized molecular dynamics ( amd ) and the momentum - dependent stochastic mean - field ( smf ) model . fragment observables and pre - equilibrium ( nucleon and light cluster ) emission are analyzed , in connection to the underlying compression - expansion dynamics in each model . considering reactions between neutron - rich systems , observables related to the isotopic properties of emitted particles and fragments are also discussed , as a function of the parametrization employed for the isovector part of the nuclear interaction . we find that the reaction path , particularly the mechanism of fragmentation , is different in the two models and reflects on some properties of the reaction products , including their isospin content . this should be taken into account in the study of the density dependence of the symmetry energy from such collisions .

the prospective study was performed between november 2011 and may 2012 at the department of otorhinolaryngology , tartu university hospital . the study group consisted of 22 consecutive patients ( 16 male and 6 female with median age of 32 , range 1474 ) with pta , undergoing bilateral tonsillectomy . the diagnosis of pta was based on the clinical evaluation , confirming pus collection in the peritonsillar space ( table 1 ) . the following clinical and demographic data were obtained : age , gender , type of antimicrobial therapy before admission , axillary temperature with an accuracy of 0.1c , history of previous episodes of recurrent tonsillitis , and length of previous history of tonsillitis . in addition , macroscopic oropharyngeal signs were evaluated and the index of tonsillitis ( it ) was calculated as described in our previous studies ( 12 , 13 ) . macroscopic oropharyngeal signs were evaluated on tonsill in the opposite side of pta and they were as follows : tonsillar sclerosis , obstruction of the tonsillar crypts , scar tissue on tonsils , cryptic debris , and lymphatic tissue aggregates . tonsillar sclerosis was defined as increased tightness of the tonsillar and peritonsillar tissue together with fixation of the palatine tonsil in the tonsillar fossa . obstruction of the tonsillar crypts was documented when narrowing of the crypt mouth was observed , resulting in the loss of clear cryptic pattern of the tonsillar surface . scar tissue on the tonsils was defined as white tissue spots or streaks on the tonsillar surface . cryptic debris was described as any white or yellow matter in the crypts or in the supratonsillar cleft . multiple round or elongated yellow - coloured patches on the retropharyngeal mucosa were described as lymphatic tissue aggregates , which are presumably due to enlargement of normal lymphatic structures in the throat . the it score was calculated by multiplying the number of tonsillitis episodes per year by the morbidity period in years ( 14 ) . basically , it represents the total number of tonsillitis episodes the patient has ever had . after removal of a tonsil , a tissue biopsy sample was taken from the tonsillar fossa for microbiological analysis . the tissue sample was immediately placed into stuart transport medium ( oxoid , basingstoke , uk ) . within 5 min of the removal of the first tonsil ( the tonsil at the side of the abscess ) , the peripheral blood cultures were drawn aseptically into bactec plus aerobic / f and bactec plus anaerobic / f blood culture bottles ( becton dickinson , maryland , sparks , usa ) . all materials were cultured semi - quantitatively in the anaerobic box with loop ( 10 l ) . blood agar plates ( oxoid , basingstoke , uk ) were employed for aerobes , chocolate agar plates for haemophilus sp . , tryptic soy - serum - bacitracin - vancomycin agar ( tsbv ; oxoid ) for aggregatibacter sp . , and fastidious anaerobe agar ( faa ; lab m , heywood , uk ) for anaerobes . the plates were incubated at 36.6c either aerobically for 2 days ( blood agar ) , in a co2-enriched atmosphere for 5 days ( chocolate and tsbv agar ) , or anaerobically for 7 days using the anaerobic glove box ( faa ) . bacterial count was evaluated semiquantitatively : the growth in the first sector ( + ) , in the second sector ( + + ) , in the third sector ( + + + ) , and in the fourth sector ( + + + + ) . another amount of pus was inoculated into blood culture bottles ( bactec pediatric , plymouth , uk ) . identification of isolated microorganisms was performed using the maldi biotyper ( bruker daltonics , bremen , germany ) . all blood culture bottles were promptly taken to the laboratory and incubated at 36c in a fully automated blood culture instrument ( bactec 9050 , becton dickinson ) . when evidence of growth was noted , gram staining and subculture were performed on the relevant plates . for antibiotic susceptibility testing only the opportunistic pathogens were selected . the selected microorganisms were streptococcus pneumoniae , s. pyogenes , s. parasanguinis , s. anginosus , s. intermedius , s. constellatus , rothia mucilaginosa , and fusobacterium necrophorum . antimicrobial sensitivity testing was performed for antimicrobials , which included first and second line antibiotics for treating pta : penicillin , ampicillin / sulbactam , cefuroxime , clindamycin , erythromycin , ciprofloxacin , and metronidazole . minimum inhibitory concentrations ( mics ) were assessed using the e - test method and the guideline breakpoint tables for interpretation of mics and zone diameters from the european committee on antimicrobial susceptibility testing ( version 5.0 , 2015 ; www.eucast.org ) ( 15 ) . exact mic values , which were used to determine sensitivity for each specimen , were as follows : s. parasanguinis penicillin , ampicillin / sulbactam ( mic susceptible0.25 ; resistant>2 ) ; clindamycin ( mic susceptible0.5 ; resistant>0.5 ) ; s. milleri group ( smg ) penicillin , ampicillin / sulbactam ( mic susceptible0.25 ; resistant>2 ) ; clindamycin ( mic susceptible 0.5 ; resistant>0.5 ) ; s. pneumoniae penicillin ( mic susceptible0.06 ; resistant>2 ) ; ampicillin / sulbactam ( mic susceptible0.5 ; resistant>2 ) ; cefuroxime , erythromycin ( mic susceptible0.25 ; resistant>0.5 ) ; clindamycin ( mic susceptible0.5 ; resistant>0.5 ) ; ciprofloxacin ( mic susceptible0.125 ; resistant>2 ) ; s. pyogenes penicillin , ampicillin / sulbactam ( mic susceptible0.25 ; resistant>0.25 ) ; clindamycin ( mic susceptible0.5 ; resistant>0.5 ) ; f. necrophorum penicillin ( mic susceptible0.25 ; resistant>0.5 ) ; ampicillin / sulbactam ( mic susceptible4 ; resistant>8 ) ; clindamycin ( mic susceptible4 ; resistant>4 ) ; metronidazole ( mic susceptible4 ; resistant>4 ) . the prospective study was performed between november 2011 and may 2012 at the department of otorhinolaryngology , tartu university hospital . the study group consisted of 22 consecutive patients ( 16 male and 6 female with median age of 32 , range 1474 ) with pta , undergoing bilateral tonsillectomy . the diagnosis of pta was based on the clinical evaluation , confirming pus collection in the peritonsillar space ( table 1 ) . the following clinical and demographic data were obtained : age , gender , type of antimicrobial therapy before admission , axillary temperature with an accuracy of 0.1c , history of previous episodes of recurrent tonsillitis , and length of previous history of tonsillitis . in addition , macroscopic oropharyngeal signs were evaluated and the index of tonsillitis ( it ) was calculated as described in our previous studies ( 12 , 13 ) . macroscopic oropharyngeal signs were evaluated on tonsill in the opposite side of pta and they were as follows : tonsillar sclerosis , obstruction of the tonsillar crypts , scar tissue on tonsils , cryptic debris , and lymphatic tissue aggregates . tonsillar sclerosis was defined as increased tightness of the tonsillar and peritonsillar tissue together with fixation of the palatine tonsil in the tonsillar fossa . obstruction of the tonsillar crypts was documented when narrowing of the crypt mouth was observed , resulting in the loss of clear cryptic pattern of the tonsillar surface . scar tissue on the tonsils was defined as white tissue spots or streaks on the tonsillar surface . cryptic debris was described as any white or yellow matter in the crypts or in the supratonsillar cleft . multiple round or elongated yellow - coloured patches on the retropharyngeal mucosa were described as lymphatic tissue aggregates , which are presumably due to enlargement of normal lymphatic structures in the throat . the it score was calculated by multiplying the number of tonsillitis episodes per year by the morbidity period in years ( 14 ) . basically , it represents the total number of tonsillitis episodes the patient has ever had . after removal of a tonsil , a tissue biopsy sample was taken from the tonsillar fossa for microbiological analysis . the tissue sample was immediately placed into stuart transport medium ( oxoid , basingstoke , uk ) . within 5 min of the removal of the first tonsil ( the tonsil at the side of the abscess ) , the peripheral blood cultures were drawn aseptically into bactec plus aerobic / f and bactec plus anaerobic / f blood culture bottles ( becton dickinson , maryland , sparks , usa ) . all materials were cultured semi - quantitatively in the anaerobic box with loop ( 10 l ) . blood agar plates ( oxoid , basingstoke , uk ) were employed for aerobes , chocolate agar plates for haemophilus sp . , tryptic soy - serum - bacitracin - vancomycin agar ( tsbv ; oxoid ) for aggregatibacter sp . , and fastidious anaerobe agar ( faa ; lab m , heywood , uk ) for anaerobes . the plates were incubated at 36.6c either aerobically for 2 days ( blood agar ) , in a co2-enriched atmosphere for 5 days ( chocolate and tsbv agar ) , or anaerobically for 7 days using the anaerobic glove box ( faa ) . bacterial count was evaluated semiquantitatively : the growth in the first sector ( + ) , in the second sector ( + + ) , in the third sector ( + + + ) , and in the fourth sector ( + + + + ) . another amount of pus was inoculated into blood culture bottles ( bactec pediatric , plymouth , uk ) . identification of isolated microorganisms was performed using the maldi biotyper ( bruker daltonics , bremen , germany ) . all blood culture bottles were promptly taken to the laboratory and incubated at 36c in a fully automated blood culture instrument ( bactec 9050 , becton dickinson ) . when evidence of growth was noted , gram staining and subculture were performed on the relevant plates . for antibiotic susceptibility testing only the opportunistic pathogens were selected . the selected microorganisms were streptococcus pneumoniae , s. pyogenes , s. parasanguinis , s. anginosus , s. intermedius , s. constellatus , rothia mucilaginosa , and fusobacterium necrophorum . antimicrobial sensitivity testing was performed for antimicrobials , which included first and second line antibiotics for treating pta : penicillin , ampicillin / sulbactam , cefuroxime , clindamycin , erythromycin , ciprofloxacin , and metronidazole . minimum inhibitory concentrations ( mics ) were assessed using the e - test method and the guideline breakpoint tables for interpretation of mics and zone diameters from the european committee on antimicrobial susceptibility testing ( version 5.0 , 2015 ; www.eucast.org ) ( 15 ) . exact mic values , which were used to determine sensitivity for each specimen , were as follows : s. parasanguinis penicillin , ampicillin / sulbactam ( mic susceptible0.25 ; resistant>2 ) ; clindamycin ( mic susceptible0.5 ; resistant>0.5 ) ; s. milleri group ( smg ) penicillin , ampicillin / sulbactam ( mic susceptible0.25 ; resistant>2 ) ; clindamycin ( mic susceptible 0.5 ; resistant>0.5 ) ; s. pneumoniae penicillin ( mic susceptible0.06 ; resistant>2 ) ; ampicillin / sulbactam ( mic susceptible0.5 ; resistant>2 ) ; cefuroxime , erythromycin ( mic susceptible0.25 ; resistant>0.5 ) ; clindamycin ( mic susceptible0.5 ; resistant>0.5 ) ; ciprofloxacin ( mic susceptible0.125 ; resistant>2 ) ; s. pyogenes penicillin , ampicillin / sulbactam ( mic susceptible0.25 ; resistant>0.25 ) ; clindamycin ( mic susceptible0.5 ; resistant>0.5 ) ; f. necrophorum penicillin ( mic susceptible0.25 ; resistant>0.5 ) ; ampicillin / sulbactam ( mic susceptible4 ; resistant>8 ) ; clindamycin ( mic susceptible4 ; resistant>4 ) ; metronidazole ( mic susceptible4 ; resistant>4 ) . the 22 patients who were hospitalized due to pta included 16 males and 6 females with a median age of 32 ( range 1474 ) . fifteen patients out of 22 ( 68.2% ) had a fever , but only nine patients ( 40.9% ) had a fever greater than 38c at presentation . only 6 patients out of 22 ( 27.3% ) had not been treated with antibiotics . antibiotics that were prescribed usually by general doctors before hospitalization were penicillin v , amoxicillin , cefadroxil , and clindamycin . three patients took a second course of antibiotics before hospitalization ; the second choice was always clindamycin . seven patients ( 31.8% ) had one to three episodes a year and only one patient had tonsillitis episodes more often than three times a year . the highest it score was 36 , but the median value was 0 ( range 036 ) and the mean value was 4.04 . after excluding the one person with the it score of 36 , the mean value of it dropped to 2.16 ( table 1 ) . the most common macroscopic oropharyngeal sign was cryptic debris that occurred in 83.3% of patients . tonsillar sclerosis and scar tissue on tonsils was present in 72.2% of cases , obstruction of the tonsillar crypts in 61.1% , and lymphatic tissue aggregates on the retropharyngeal mucosa in 55.6% of the patients . the examination was performed before tonsillectomy on a scale of 05 and the median value was 4 ( range 05 ) . the pus cultures were positive in 16 ( 72.7% ) out of 22 patients and the cultures of the tonsillar fossa samples were positive in all cases . at the same time , only 2 out of 22 blood samples were positive . in total , 62 different organisms were found from tonsillar fossa , pus , and blood samples , which belonged to 5 different phyla and 18 different families ( table 2 ) . among them , 32 different organisms were discovered from the pus specimens , 49 different organisms from the tonsillar fossa , and 3 organisms from the blood samples ( table 2 ) . the median number of different organisms found in all tonsillar fossa biopsies was six ( range 110 , mean 5.7 sd 2.5 ) and in all pus samples it was three ( range 09 , mean 2.7 sd 2.7 ) ( fig . microorganisms isolated from the pus , tonsillar fossa , and blood of peritonsillar abscess patients in the tonsillar fossa , the most frequent bacteria found were streptococcus spp . , whereas the most frequent specimens were s. parasanguinis ( 12/22 ) and s. pneumoniae ( 12/22 ) . was followed by neisseria spp . and actinomyces spp . in the tonsillar fossa biopsy we found six staphylococcus spp . in addition , r. mucilaginosa was present in seven ( 31.8% ) tonsillar fossa biopsies , but was never found in the pus . in pus samples , bacteria from the smg , consisting of s. anginosus , s. intermedius , and s. constellatus , were isolated from the pus in 12 cases and from the tonsillar fossa in four cases . among the 16 positive pus samples , smg was present in nine ( 56.2% ) . a single organism was cultured in four ( 18.2% ) pus cultures , and multiple organisms were present in 12 ( 54.5% ) pus cultures . out of 22 patients , 6 ( 27.3% ) had no microbiological growth in the pus . s. pyogenes was a monoculture in the pus of two patients ; s. constellatus and f. necrophorum were each a single organism in the pus culture of one patient . in 9 patients out of the 16 with positive pus samples ( 56.2% ) , the same organisms that were found in the pus were also present in the tonsillar fossa biopsy samples ( altogether 20 isolates ) ( fig . 2 ) . at the same time , all except one pus sample had one or more specimens in the pus that were not found in the tonsillar fossa biopsy . the bacteria found from blood cultures were s. mitis and s. oralis in one patient and peptostreptococcus anaerobius in another . antibiotic susceptibility of opportunistic bacteria s , susceptible ; r , resistant ; i , intermediate ; p , penicillin ; sam , ampicillin / sulbactam ; cxm , cefuroxime ; cd , clindamycin ; e , erythromycin ; cip , ciprofloxacin ; mtz , metronidazole . we also determined the minimum inhibitory concentration ( mic ) values for r. mucilaginosa : 0.016 and 0.125 for penicillin ; 0.047 , 0.094 , 0.5 , and 0.38 for cefuroxime ; and 0.75 , 2 , and 6.2 for ciprofloxacin . these data were not included in the table since no mic cut - off values exist for r. mucilaginosa susceptibility and resistance . the 22 patients who were hospitalized due to pta included 16 males and 6 females with a median age of 32 ( range 1474 ) . fifteen patients out of 22 ( 68.2% ) had a fever , but only nine patients ( 40.9% ) had a fever greater than 38c at presentation . only 6 patients out of 22 ( 27.3% ) had not been treated with antibiotics . antibiotics that were prescribed usually by general doctors before hospitalization were penicillin v , amoxicillin , cefadroxil , and clindamycin . three patients took a second course of antibiotics before hospitalization ; the second choice was always clindamycin . seven patients ( 31.8% ) had one to three episodes a year and only one patient had tonsillitis episodes more often than three times a year . the highest it score was 36 , but the median value was 0 ( range 036 ) and the mean value was 4.04 . after excluding the one person with the it score of 36 , the mean value of it dropped to 2.16 ( table 1 ) . the most common macroscopic oropharyngeal sign was cryptic debris that occurred in 83.3% of patients . tonsillar sclerosis and scar tissue on tonsils was present in 72.2% of cases , obstruction of the tonsillar crypts in 61.1% , and lymphatic tissue aggregates on the retropharyngeal mucosa in 55.6% of the patients . the examination was performed before tonsillectomy on a scale of 05 and the median value was 4 ( range 05 ) . the pus cultures were positive in 16 ( 72.7% ) out of 22 patients and the cultures of the tonsillar fossa samples were positive in all cases . at the same time , only 2 out of 22 blood samples were positive . in total , 62 different organisms were found from tonsillar fossa , pus , and blood samples , which belonged to 5 different phyla and 18 different families ( table 2 ) . among them , 32 different organisms were discovered from the pus specimens , 49 different organisms from the tonsillar fossa , and 3 organisms from the blood samples ( table 2 ) . the median number of different organisms found in all tonsillar fossa biopsies was six ( range 110 , mean 5.7 sd 2.5 ) and in all pus samples it was three ( range 09 , mean 2.7 sd 2.7 ) ( fig . microorganisms isolated from the pus , tonsillar fossa , and blood of peritonsillar abscess patients in the tonsillar fossa , the most frequent bacteria found were streptococcus spp . , whereas the most frequent specimens were s. parasanguinis ( 12/22 ) and s. pneumoniae ( 12/22 ) . was followed by neisseria spp . and actinomyces spp . in the tonsillar fossa biopsy we found six staphylococcus spp . in addition , r. mucilaginosa was present in seven ( 31.8% ) tonsillar fossa biopsies , but was never found in the pus . in pus samples , bacteria from the smg , consisting of s. anginosus , s. intermedius , and s. constellatus , were isolated from the pus in 12 cases and from the tonsillar fossa in four cases . among the 16 positive pus samples , smg was present in nine ( 56.2% ) . a single organism was cultured in four ( 18.2% ) pus cultures , and multiple organisms were present in 12 ( 54.5% ) pus cultures . out of 22 patients , 6 ( 27.3% ) had no microbiological growth in the pus . s. pyogenes was a monoculture in the pus of two patients ; s. constellatus and f. necrophorum were each a single organism in the pus culture of one patient . in 9 patients out of the 16 with positive pus samples ( 56.2% ) , the same organisms that were found in the pus were also present in the tonsillar fossa biopsy samples ( altogether 20 isolates ) ( fig . , all except one pus sample had one or more specimens in the pus that were not found in the tonsillar fossa biopsy . the bacteria found from blood cultures were s. mitis and s. oralis in one patient and peptostreptococcus anaerobius in another . antibiotic susceptibility of opportunistic bacteria s , susceptible ; r , resistant ; i , intermediate ; p , penicillin ; sam , ampicillin / sulbactam ; cxm , cefuroxime ; cd , clindamycin ; e , erythromycin ; cip , ciprofloxacin ; mtz , metronidazole . we also determined the minimum inhibitory concentration ( mic ) values for r. mucilaginosa : 0.016 and 0.125 for penicillin ; 0.047 , 0.094 , 0.5 , and 0.38 for cefuroxime ; and 0.75 , 2 , and 6.2 for ciprofloxacin . these data were not included in the table since no mic cut - off values exist for r. mucilaginosa susceptibility and resistance . in the present study , we found mixed aerobic and anaerobic microbiota either in the tonsillar fossa or in the pus evacuated from the peritonsillar space . we demonstrated that the tonsillar fossa specimen is a better material for microbiological analyses , because it reveals more bacteria per culture . altogether 49 species were recovered from the tonsillar fossa , which is significantly more than the 32 species recovered from the pus cultures . the most common microorganisms were streprococcus species , particularly the smg ( s. anginosus , s. intermedius , and s. constellatus ) . although the smg is normally found on the oropharyngeal mucosa , it has been recognized as the aetiological agent of the abscesses in the head and neck region ( 1618 ) . we found smg microorganisms in up to 56.2% of positive cultures . in our previous study , in addition to streptococcus species , the anaerobic bacteria were the second most common bacteria found in the tonsillar fossa of patients with recurrent tonsillitis ( kasenmm et al . this finding is not in accordance with recent studies where the importance of anaerobes in the aetiology of pta , particularly f. necrophorum , has been questioned ( 3 , 610 ) . we found f. necrophorum only in one pus culture and in two tonsillar fossa specimens . on the other hand , s. pyogenes , the most important aetiological agent of acute tonsillitis , was recovered from four tonsillar fossa specimens and from six pus cultures out of 22 ( 27.2% ) . interestingly , in our previous study on recurrent tonsillitis we recovered no s. pyogenes from tonsillar core specimens by the culture method , but found it in 29% of cases when using more sensitive pcr . it has been demonstrated that s. pyogenes has a great ability to conceal itself intracellularly , to prevent immune response ( 19 ) . our data may suggest that in the case of acute infection , as well as in pta , s. pyogenes may escape from epithelial cells and play an important role in the pathogenesis of the disease . the bacteria isolated from blood cultures were viridans streptococci ( s. mitis and s. oralis ) and p. anaerobius . in other studies , the percentage of positive blood cultures has been higher ( 20 ) . in our previous study , the rate of positive blood cultures during tonsillectomy was as high as 44% ( 12 ) . in the present study , we used the same culture media and the same protocol for collecting blood cultures during tonsillectomy . therefore , we suggest that the significantly lower rate of positive blood cultures is related to preoperative antibacterial therapy . in our previous study , the study group consisted of patients with recurrent tonsillitis in whom tonsillectomy was performed in their relatively healthy state , without preoperative antibiotics . in comparison , among the pta patients on the other hand , these data also demonstrate that the use of antibiotics prior to acute tonsillectomy for pta may be beneficial so as to reduce bacterial translocation and avoid more serious complications . antibiotics that were used were penicillin v , amoxicillin , cefadroxil , and clindamycin . because there are no common guidelines for the treatment of pta in estonia , the antibiotics spectrum varies . according to our study the commonly used antibiotics penicillin and other beta - lactam antibiotics are suitable as empirical treatment . antibiotic resistance to penicillin and other beta - lactam is higher only among f. necrophorum . however f. necrophorum was not a very common pathogen in our population . in a further analysis we studied the it value in pta patients . we found that only one patient with pta out of 22 had an it score of 36 or higher . the median it value was 0 ( range 036 ) and the average was 4.04 . when that single patient with the it score of 36 was excluded , the average it value dropped to 2.16 . this is a much lower value than in the patients with recurrent tonsillitis in our previous study ( 13 ) , where the median it score was 30 ( range 6138 ) . there we found that the it score of 36 is an optimal prediction for impaired defensive function of palatine tonsils for a patient with recurrent tonsillitis and tonsillectomy was recommended . these data suggest that patients with pta usually have no , or very few , previous tonsillitis episodes . we also estimated the presence of five different macroscopic oropharyngeal signs ( tonsillar sclerosis , scar tissue on the tonsils , obstruction of tonsillar crypts , cryptic debris , and lymphatic tissue aggregates ) in pta patients on the opposite side . the same macroscopic signs were used in a previous study , where a strong correlation between the occurrence of those signs and the development of tonsillar scarring was demonstrated ( 12 ) . in the present study , the median rate of macroscopic oropharyngeal signs in pta patients was 4 out of 5 . this finding shows that even when patients had only a few tonsillitis episodes or none at all , most of them had signs characteristic of recurrent inflammation in the tonsillar tissue . ongoing inflammation in the tonsillar tissue leads , in the long term , to tonsillar scarring and a lower protective function of the tonsils ( 12 ) . this finding may partially explain the development of pta despite the absence of recurrent tonsillitis symptoms in these patients . pta patients have mixed anaerobic and aerobic microbiota both in the tissue of the tonsillar fossa and the pus of the peritonsillar space , with s. pyogenes and members of the smg being the most common isolated species . our results indicate that tonsillar fossa specimens should be preferred over pus sampling during abscess tonsillectomy in order to reveal a possible pathogen . second , pta patients usually have a low number of tonsillitis episodes in their previous history , but a relatively high number of macroscopic oropharyngeal signs , indicating the sclerotic process in palatal tonsils and low immune response that may support the development of mixed oropharyngeal infections . the authors have not received any funding or benefits from industry or elsewhere to conduct this study .

objectivethe first aim of this study was to compare the microbiota of different locations ( pus , tonsillar fossa , blood ) in peritonsillar abscess ( pta ) patients in order to optimize the sampling scheme . the second aim was to estimate the occurrence of tonsillitis episodes and macroscopic oropharyngeal signs characteristic of recurrent tonsillitis in pta patients.methodsthe study group consisted of 22 consecutive patients with pta undergoing bilateral tonsillectomy . the pta was punctured ; pus and tonsillar fossa biopsy samples and the peripheral blood cultures were collected . the index of tonsillitis was calculated by multiplying the number of tonsillitis episodes per year by the morbidity period in years . macroscopic oropharyngeal signs were evaluated and they were as follows : tonsillar sclerosis , obstruction of the tonsillar crypts , scar tissue on tonsils , cryptic debris , and lymphatic tissue aggregates.resultsthe cultures of the pus were positive in 16 out of 22 patients and the cultures of the tonsillar fossa samples were positive in all cases . in total , 62 different organisms were found from tonsillar fossa , pus , and blood samples , which belonged to 5 different phyla and 18 different families.in the tonsillar fossa , the most frequent bacteria found were streptococcus spp . in pus samples , the most frequently found bacteria were streptococcus spp . and bacteria from the streptococcus milleri group.conclusionpta patients had mixed anaerobic and aerobic microbiota both in the tissue of the tonsillar fossa and the pus of the peritonsillar space . we demonstrated that the tonsillar fossa specimen is a better material for microbiological analyses , because it reveals more bacteria per culture . pta patients usually have a low number of tonsillitis episodes in their previous history , but a relatively high number of macroscopic oropharyngeal signs , indicating the sclerotic process in palatal tonsils .

hyponatremia can be asymptomatic or can cause a variety of symptoms such as nausea , vomiting , malaise , lethargy , confusion , headache , decreased level of consciousness , seizures , and coma , depending on its severity . in their study on hyponatremia in hospitalized cancer patients and its impact on clinical outcomes , doshi et al . concluded that hyponatremia in a patient with cancer is associated with longer hospital stay and higher mortality . patients referred for palliative care have multiple symptoms and tiredness or fatigue is one of the most frequent symptoms in palliative care . hyponatremia can be counted as one of the many contributing factors for fatigue in these patients . hyponatremia can be classified , according to volume status , as - hypovolemic hyponatremia : decrease in total body water with greater decrease in total body sodium , euvolemic hyponatremia : normal body sodium with increase in total body water , hypervolemic hyponatremia : increase in total body sodium with greater increase in total body water . hyponatremia can be further sub - classified according to effective osmolality as hypotonic hyponatremia , isotonic hyponatremia , and hypertonic hyponatremia . hypovolemic causes of hyponatremia include acute corticosteroid withdrawal , cerebral salt wasting , diuretic use , gastrointestinal loss , iatrogenic ( insufficient volume , use of hypotonic solutions ) , and skin loss . normovolemic causes include adrenal insufficiency , drug - induced : selective serotonin reuptake inhibitors , opioids , and oxytocin . hypothyroidism and syndrome of inappropriate secretion of antidiuretic hormone ( siadh ) are other important causes of normovolemic hyponatremia . hypervolemic causes of hyponatremia include acute renal failure , cirrhosis , and congestive heart failure . in cancer patients , which form a majority of palliative care patients cancers of the lung , breast , head and neck are the ones commonly associated with hyponatremia caused mostly by siadh . among these , lung cancer has the worst prognosis which can be compounded by the increase in mortality caused by hyponatremia . establishing the cause of hyponatremia in palliative care patients is often not undertaken as they have multiple co - morbidities and there could be several factors involved . in a developing country like india , financial implication is a major factor that contributes to physician 's reluctance in ordering multitude of tests required to establish the exact cause of hyponatremia such as serum osmolality , urine osmolality , and imaging studies . a literature search reveals that hyponatremia is prevalent in patients and often is an incidental finding which is undertreated . a retrospective manual analysis of charts of consecutive patients , who were referred to the department of pain and palliative medicine , st . john 's medical college hospital , bengaluru for a total of 5 years , was carried out . all patients whose sodium levels were below 135 meq / l were included in the analysis . statistical package spss 16 ( ibm spss statistics ) was used for analysis of data . hyponatremia was recorded in 222 which is 28.8 % of the patients whose sodium levels were documented . patients age varied from 3 to 94 years , and 125 men and 97 women demonstrated hyponatremia [ figure 1b ] . ( a ) documentation of sodium levels , ( b ) demographics of the 28.8% of patients , who had documented hyponatremia , 61.1 % had malignant disease compared to 39.9 % with nonmalignant disease [ figure 2 ] . prevalence of hyponatremia in malignant and nonmalignant diseases in the malignant group , gastrointestinal cancers showed the highest percentage ( 36.7% ) , followed by hematological cancers ( 16.1% ) , genitourinary cancers ( 14.7% ) , lung cancers ( 12.5% ) , head and neck cancers ( 8.8% ) , breast cancers ( 5.1% ) , and endocrine , renal and soft tissue cancers ( 5.7% ) forming the remaining group [ figure 3 ] . types of cancers with hyponatremia the nonmalignant group of patients had different diseases such as fractures , amputations , stroke , peripheral vascular disease , renal failure , cardiac failure , and chronic obstructive pulmonary disease . of the 222 patients , who had hyponatremia , 117 ( 52.7% ) had mild hyponatremia with a sodium of 130134 meq / l , 65 ( 29.2% ) had moderate hyponatremia with a sodium of 125129 meq / l , and 40 ( 19.1% ) had severe hyponatremia with a sodium value of 124 meq / l and less [ figure 4a ] . ( a ) grades of hyponatremia , ( b ) percentage of malignant and nonmalignant diseases in different grades of hyponatremia malignant patients formed 88.8% in the mild hyponatremia group , 75.4% in the moderate group , and 82.5 % in the severe hyponatremia group . the nonmalignant patients formed 11.2% , 24.6% , and 17.5 5% in the mild , moderate , and severe hyponatremia group , respectively [ figure 4b ] . hyponatremia was recorded in 222 which is 28.8 % of the patients whose sodium levels were documented . patients age varied from 3 to 94 years , and 125 men and 97 women demonstrated hyponatremia [ figure 1b ] . of the 28.8% of patients , who had documented hyponatremia , 61.1 % had malignant disease compared to 39.9 % with nonmalignant disease [ figure 2 ] . in the malignant group , gastrointestinal cancers showed the highest percentage ( 36.7% ) , followed by hematological cancers ( 16.1% ) , genitourinary cancers ( 14.7% ) , lung cancers ( 12.5% ) , head and neck cancers ( 8.8% ) , breast cancers ( 5.1% ) , and endocrine , renal and soft tissue cancers ( 5.7% ) forming the remaining group [ figure 3 ] . types of cancers with hyponatremia the nonmalignant group of patients had different diseases such as fractures , amputations , stroke , peripheral vascular disease , renal failure , cardiac failure , and chronic obstructive pulmonary disease . of the 222 patients , who had hyponatremia , 117 ( 52.7% ) had mild hyponatremia with a sodium of 130134 meq / l , 65 ( 29.2% ) had moderate hyponatremia with a sodium of 125129 meq / l , and 40 ( 19.1% ) had severe hyponatremia with a sodium value of 124 meq / l and less [ figure 4a ] . ( a ) grades of hyponatremia , ( b ) percentage of malignant and nonmalignant diseases in different grades of hyponatremia malignant patients formed 88.8% in the mild hyponatremia group , 75.4% in the moderate group , and 82.5 % in the severe hyponatremia group . the nonmalignant patients formed 11.2% , 24.6% , and 17.5 5% in the mild , moderate , and severe hyponatremia group , respectively [ figure 4b ] . true occurrence of hyponatremia in various clinical settings is difficult to determine . a literature search ( cochrane database and embase ) for the prevalence of hyponatremia in palliative care patients did not yield any result . this is true , especially with elderly patients . in their study looking at predictors of inpatient mortality in an acute palliative care unit , elsayem et al . correlation of hyponatremia to patient mortality was not done in the present study . in their study on prevalence , incidence , and etiology of hyponatremia in elderly patients with fragility fractures , they found that dehydration and prescription of thiazide diuretics and proton pump inhibitors were the potential causative factors and not siadh . in the present study too , the prevalence of hyponatremia was significant at 28.8% with a p value of 0.000 . in another study , shapiro et al . found that the prevalence of severe hyponatremia in elderly hospitalized person was significant with a p < 0.001 . they found that it was more frequent in women and multifactorial in etiology in 50% of the cases . in their group of patients , they found that it is most commonly caused by siadh . in the present study , more men ( 125 ) were found to have hyponatremia compared to women ( 97 ) . states that hyponatremia is a predictor of mortality in the general population independently of age , gender , and co - morbid conditions . a study on ambulatory patients with mild hyponatremia followed up over a period of 8 years , found that the prevalence was 6.9% and was significantly associated with age , black ethnicity , presence of cirrhosis , cardiac failure or cancer and use of antiepileptic drugs and serotonin reuptake inhibitors . in the present study , 61.10% of patients with malignant diseases and 39.9% of patients with nonmalignant diseases were found to have hyponatremia . in a study that looked at hyponatremia in acute medical admissions this could indicate that hyponatremia might be a cause of acute admissions . in another study that looked at diagnostic codification of hyponatremia on patients admitted under internal medicine , the authors found that there was a low prevalence of hyponatremia codification and stated that hyponatremia was underreported and undertreated in spite of numerous studies showing devastating effects of hyponatremia . cancer patients form the majority of palliative care patients and cancer in itself and its different manifestations cause hyponatremia . an aging population also has more prevalence of cancer , thereby increasingly seeking palliative care . hyponatremia can be found associated with siadh in 1015% of patients with small cell lung cancer . in their article on tumor related hyponatremia , onitilo et al . hyponatremia may be detected by routine laboratory testing or by the manifestation of neurological symptoms in cancer patients . hospitalized cancer patients are prone to have a higher rate of hyponatremia when compared to hospitalized noncancer patients with the outcome in the cancer patients being poor . in a study result from the international metastatic renal cell cancer database consortium , hyponatremia was found to be independently associated with a worse outcome in metastatic renal cell cancer patients . most of the patients referred for palliative care in the present study population were cancer patients . worldwide , cancer patients still form the majority of palliative care patients . with an already bad prognosis , it is tough for patients to bear the added burden of hyponatremia and its complications . it is time that we recognized and treated hyponatremia diligently so that the patients and their relatives suffer less from the added burden . even today substantial amount of work needs to be done to assess the causes and management outcomes of hyponatremia in palliative care patients . prevalence of hyponatremia is significant in palliative care patients . although this study showed that hyponatremia is more in cancer patients , it can not be generalized , as the number of cancer patients included in the study was proportionately more than noncancer patients . the causes and clinical outcomes associated with hyponatremia in palliative care patients warrant analysis of a prospective cohort .

introduction : hyponatremia is an undertreated finding in clinical practice . it is the most common electrolyte abnormality . hyponatremia can be asymptomatic or can cause symptoms ranging from nausea and lethargy to convulsions and coma . palliative care patients have a multitude of symptoms and there are several contributing factors towards this . hyponatremia could be one of the contributing factors . looking at the prevalence of hyponatremia would highlight the magnitude of the problem and would prompt healthcare professionals to investigate and treat hyponatremia in palliative care patients , which in turn might reduce symptoms such as fatigue and nausea . this could improve the quality of life in palliative care patients.aim:to assess the prevalence of hyponatremia among patients referred for palliative care in a tertiary care hospital.methodology:this is a descriptive study , with retrospective analysis of consecutive patient charts for 5 years . the sodium levels at the time of referral for palliative care , was reviewed . inferential statistics for the result was calculated using the z-test.results:of the 2666 consecutive patient charts that were reviewed , sodium values were recorded in 796 charts . among the recorded charts , 28.8 % of patients showed hyponatremia at the time of referral which was significant with a p value of 0.000 ( < 0.05 ) . of these , 61.1 % had malignancy as their diagnosis and the rest had nonmalignant diseases , ranging from trauma to chronic obstructive pulmonary disease.conclusions:prevalence of hyponatremia is significant in palliative care patients . a prospective study looking at the causes and clinical outcomes associated with hyponatremia in palliative care patients is needed .

Friday is the one day of the year when you don't have to be blue to be a cookie monster. It's National Cookie Day, an unofficial but delicious celebration of the sweet snack. The observance was reportedly launched in the 1980s by the Blue Chip Cookie Co., and it's still going strong today. Get your weekend started early by scoring a free cookie at one of these stores offering deals Friday: • At Insomnia Cookies, get one free chocolate chunk cookie with any purchase. Delivery minimums still apply, but the deal runs through 3 a.m. • At Great American Cookies locations, you can nab a free regular chocolate chip cookie. Photo: Getty Images • At Whole Foods stores, you can get up to three chocolate chip cookies for 25 cents each. This promotion extends through Tuesday. • At ROCS convenience stores, you can get a free cookie if you sing "Jingle bell, jingle bell, jingle bell ROCS. Jingle bells play on National Cookie Day!" • At Food City stores, you can get a freshly baked in-store cookie for free and two dozen cookies for $5 through Tuesday. • At Hot Box Cookies in Columbia, Missouri, you can get two free chocolate cookies if you follow the company on social media. The deal runs from 10 a.m. to 6 p.m. • At Christie Cookies in Nashville, you can get free cookies from 8 a.m. to 4 p.m. • At the Rockefeller Center Christmas Tree in New York City, DoubleTree by Hilton hotel elves will be giving out cookies to tourists from 1 p.m. to 4 p.m. • In Baltimore, GalleyFoods is giving out free gourmet cookies starting at 1 p.m. All you have to do is request one through the iPhone app. • At any Canada Subway location, get a free cookie when you claim the offer on Facebook. Can't get there in person on Friday? There are at least three online retailers running deals that just happen to coincide with Friday's holiday: • On the Blue Chip Cookies website, specials and gift certificates are 12 percent off with the coupon Joyful15. • On the Cheryl's website, everything is 15 percent off with the promo code CHERYL15 through the end of the year. • On the Mrs. Fields website, shipping is only $5 with the code DECDEALS. ||||| Pepperidge Farm Milano double chocolate cookies. Pepperidge Farm sued Trader Joe's for trademark infringement over a cookie product it says closely resembles Milano. (Photo: Pepperidge Farm) A line of cookies sold at Trader Joe's looks a little too familiar to Pepperidge Farm. Pepperidge Farm, a division of Campbell Soup, sued the popular grocery chain for trademark infringement over a product called Crispy Cookies that it says too closely resembles both the look and package design of Pepperidge Farm's iconic Milano cookies — a line of oval-shaped sandwich cookies with chocolate filling. Pepperidge Farm accused Trader Joe's of deceptive marketing and diluting the value of Milano with Crispy Cookies, according to a complaint filed Wednesday in Connecticut federal district court. "Trader Joe’s has willfully sought to trade on Pepperidge Farm’s reputation and the reputation of the Milano cookies," the company wrote in the complaint, which asks that Trader Joe's be prohibited from selling the cookies and seeks damages for Pepperidge Farm. Pepperidge Farm first notified Trader Joe's of potential trademark infringement in August, according to the document. Pepperidge Farm has a trademark for Milano cookies, which were launched in 1956. Pepperidge Farm says it has generated "hundreds of millions of dollars" in Milano cookie sales in the last ten years. Reached by USA TODAY, Trader Joe's spokeswoman Alison Mochizuki said the company doesn't comment on pending litigation. Read or Share this story: http://usat.ly/1XOldrT ||||| This Guy Found a Trap Door In His New Apartment What He Found Is Hauntingly Awesome - Duration: 6:05. You Should Know ? Recommended for you

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thanks to the outstanding work by n. walborn and collaborators over the last 30 years , a detailed classification scheme for ob - stars of solar metallicity has been developed , based on the morphology of the line spectrum . for the specific case of o - type stars , an alternative scheme relying on quantitative criteria has been provided by conti & alschuler @xcite and mathys @xcite as well . consequently , the classification of galactic ob stars is rigorously defined . the classification of extragalactic stars , on the other hand , is still somewhat problematic . in particular , the calibration between spectral types and physical parameters differs as a function of metallicity when criteria for milky way stars are applied . with respect to b - stars , this point has been extensively discussed by various authors ( e.g. , monteverde et al . @xcite , lennon @xcite , urbaneja et al . @xcite ) who pointed out that the use of the mk classification criteria for stars with metallicities different than solar can significantly influence the derived spectral types and luminosity classes . unlike b - type stars , where the relative strengths of metal to he i optical lines are used for classification purposes , o - type stars are generally classified by comparing the strengths of he i and he ii lines ( see , e.g. , conti & alschuler @xcite ; mathys @xcite , walborn @xcite ; walborn & fitzpatrick,@xcite ) . thus , one might conclude that there should be no problem to employ the standard classification schemes of either walborn or conti to o - type stars in various metallicity environments . however , theoretical considerations predict that helium line strengths should also depend , though indirectly , on metallicity , due to the processes of mass - loss and euv line - blocking / blanketing ( e.g. , abbott & hummer @xcite , sellmaier et al . @xcite , herrero et al . @xcite ) . whilst in stars with weaker winds ( e.g. , dwarfs ) the effect is controlled , to a major extent , by the blanketing alone , in stars with stronger winds ( e.g. , supergiants ) , the processes of wind emission and additional wind - blanketing seem to be of similar or even dominating impact ( e.g. , repolust et al . as noted in the previous section , the classification of o - type stars in the optical band relies either on the walborn or on the conti classification schemes , both developed to be used at solar metallicity . in the walborn scheme visual estimates of individual line strengths or line strength ratios of strategic helium transitions are used as classification criteria , while in the conti scheme the logarithm of the equivalent width ( ew ) ratio of he i 4471 to he ii 4541 is used instead . given that an eye - estimated ratio is roughly equivalent to the logarithmic ratio of the corresponding ews , these two approaches should lead to similar results ( but see heap et al . @xcite ) . to address the metallicity issue regarding the spectral classification of o - type stars , we developed the following strategy . as a first step and using the fastwind code ( puls et al . @xcite ) , we constructed 6 model grids , corresponding to two values of metallicity , solar , @xmath1 , and 0.3 @xmath1 , of about -0.5 was found , corresponding to an average metallicity of about 0.3 ( for more information , see efremova et al . @xcite and references therein ) . ] , and three luminosity classes : dwarfs ( dws ) , giants ( gs ) and supergiants ( sgs ) . by means of these models we investigated the predicted variations in helium line strengths , caused by the adopted change in metallicity , as a function of and luminosity class . subsequently , we evaluated the shifts in spectral type ( and ) and luminosity class , that would eventually appear if galactic classification criteria were used to o - type stars of metallicity 0.3 . our model grids comprise 64 nlte , line - blanketed models with stellar winds . for all models and independent of metallicity , stellar parameters ( , , and ) were taken from the empirical calibrations of martins et al . @xcite for galactic stars of luminosity classes i , iii and v. we used a solar chemical composition as derived by asplund et al.@xcite , subsequently scaled to z=0.3 @xmath2 . a standard @xmath3-velocity law with @xmath3=0.9 was adopted for all models . terminal velocities , , for solar metallicity models were determined by means of the spectral type - calibration from kudritzki & puls @xcite . the effects of metallicity on were taken into account by employing the scaling relation from leitherer et al . @xcite , namely @xmath4 . mass - loss rates were calculated using the mass - loss recipe from vink et al . a microturbulent velocity of 10 was used to calculate the atmospheric structures , whilst values of 5 , 10 and 15 were assumed for calculating the emergent spectrum . based on these model grids , the ew variations of several strategic he i ( e.g. , he i 4026 , he i 4471 and he i 4387 ) and he ii ( e.g. , he ii 4200 , he ii 4541 and he ii 4686 ) lines were investigated , as a function of metallicity ( and 0.3 ) , and luminosity class . our results , partly illustrated in figures [ he_lines ] and 3 , indicate that in the o - star temperature domain he i and he ii are both influenced by metallicity . the effect is opposite to that for metal lines , i.e. , while metal lines become weaker due to the lower metal content , the helium line strengths are predicted to increase in absorption . moreover , individual lines react differently . members of the he i singlet series are more sensitive to metallicity than those of the triplet series , which in turn are more sensitive than he ii transitions ( except for he ii 4686 , see next section ) . in addition , the effect depends on and , being more pronounced in hotter sgs ( where mass loss effects are strongest ) , and almost negligible ( within @xmath510% ) at intermediate and cooler temperature dws . our findings imply that , due to the lower metal content , the optical helium line spectrum of low metallicity o - stars would appear somewhat different from that of their galactic conterparts . in particular , at z=0.3 and if the strength of the primary classification lines , he i 4471 and he i 4387 , were to be considered , these lines would resemble those of a galactic star with _ lower _ ( assuming the same and ): about 2 kk lower for sgs and up to 1 kk lower for dws . vice versa , if compared to galactic counterparts with the _ same observed _ ews in he i , stars with a lower metal content should be hotter . for the strategic he ii 4200 and he ii 4541 transitions we find the following situation : for intermediate and low temperature dws ( 39 @xmath6 @xmath6 32 kk ) and cooler sgs ( below 34kk ) , the corresponding lines strengths are predicted to remain rather unaffected by metallicity , whilst at higher they are amplified by up to 20 percent , mimicking the lines of a galactic star of _ higher _ . the effect of metallicity on the spectral classification of o - stars can be evaluated by investigating the behaviour of he i / he ii line ratios instead of individual line strengths . thus , we have calculated and compared the logarithmic he i(+ii ) 4026/he ii 4200 , he i 4471/he ii 4541 and he i 4387/he ii 4541 line ratios , as a function of , for the cases of dws , gs and sgs and for the two values of metallicity , and 0.3 . the results of these calculations are partly illustrated in figure [ he_ratio ] , where the lower and upper limits of the line strength ratios from the mathys @xmath7 - spectral type calibration are overplotted as vertical lines . the x - position of each of these lines has been placed at the appropriate -value following from the martins et al . empirical calibration for the corresponding spectral type . apparently , this criterion to classify o - stars with z=0.3 would lead to temperature differences that increase with and luminosity class . in particular , for sgs these differences are predicted to range from about 1 to about 2 kk ( i.e. about one sub - type ) , while for dws the expected values are a factor of 2 smaller . another important result to be noted is that whilst for galactic dws a good correspondence between the calculated and the calibrated values of the he i 4471/he ii 4541 line ratios is found , for cooler sgs ( subtypes later than o7 ) the calculated values are systematically smaller . this discrepancy results from the ( still not understood ) so - called `` generalized dilution effect '' , which makes the synthetic he i 4471 lines in low temperature sg models weaker than observed ( see repolust et al . @xcite and references therein ) . since this effect seems to be independent on metallicity , it is not expected to influence our general findings though . in the walborn classification scheme , the main luminosity criterion is he ii 4686 . in sgs this line appears only in emission , while in dws it is observed as a pure absorption feature . since the amount of emission depends on the wind properties , which in turn depend on metallicity , one expects the strength of he ii 4686 to depend on metallicity as well ( see , e.g. , massey et al . @xcite ) . in figure 3 the behaviour of the he ii 4686 ews ( positive for emission and negative for absorption ) are shown as a function of , for two luminosity classes ( sgs and dws ) and for z= and 0.3 . expectedly , our calculations for solar metallicity models produce he ii 4686 in emission for sgs and in absorption for dws . interestingly , however , our calculations predict that the metallicity effects on this line can be so strong that at z=0.3 its sensitivity to luminosity vanishes almost completely , and he ii 4686 appears in absorption for all calculated models . [ heii4686 ] finally let us note that although an increase in microturbulent velocity ( from 5 to 15 ) is predicted to shift the assigned spectral types by half ( for dws ) to one ( for sgs ) subtype towards later spectral types , this effect does not seem to depend on metallicity . due to this reason model predictions corresponding to = 10 only are shown throughout this paper . based on a grid of nlte , line blanketed model atmospheres with stellar winds as calculated by means of fastwind , we found that @xmath8 in o - stars the optical helium spectrum can be significantly influenced by metallicity effects , where a decrease in metal content results in stronger he line absorptions _ from both ionization stages _ , where lines from he i are more severely affected than those from he ii . individual lines react differently in dependence of and luminosity class , but do not depend on microturbulence . this result is particularly important when _ individual line strengths _ are used to classify stars , as it is the case for the walborn scheme where the detection of weak he i 4471 and he i 4387 is used to fix the subtypes o4 and o6 , respectively . according to our calculations at @xmath9=0.3 , the use of these lines as classification indicators would shift the assigned spectral types by up to one subtype to the later side , provided the detection threshold is the same . @xmath8 furthermore , our calculations showed that not only individual helium lines , but helium line ratios are also varying with metallicity . in particular , the use of the he i 4471/he ii 4541 ratio to classify o - stars of @xmath9=0.3 would shift the derived temperature scale by up to 2 kk ( i.e. , about one sub - type ) for sgs , and up to 1 kk ( i.e. , about half a sub - type ) for dws to the hotter side . the latter result is consistent with the predictions by mokiem et al . @xcite , who found , using cmfgen ( hillier & miller @xcite ) , that variations in the metal content from z=2 to z=0.1 can change the spectral type of a hot dw by up to one and a half sub - type . extended extragalactic surveys of hot massive stars showed that o - stars in low metallicity environment are systematically hotter than their galactic counterparts with the same spectral type ( e.g. , mokiem et al . @xcite , massey et al . @xcite , efremova et al . 2009 ) , thus confirming our principal predictions . however , the observed shifts in are significantly larger than those predicted to appear from a shift in the assigned spectral types , as calculated here and in other work . in particular , for o - type dws temperature differences of 3 to 4 kk , i.e. , a factor of 3 to 4 larger than those predicted by mokiem et al . @xcite were established between objects in our galaxy and in the smc ( z=0.2 ) would result in a shift of only 1 kk in of a hot dw , i.e. , about half a subtype . ] . the corresponding results for dws in ngc 6822 are roughly the same ( efremova et al . @xcite ) . thus , only part ( @xmath1025 to 30 percent ) of the observed differences in of o - type dws in the smc and in ngc 6822 could be explained by metallicity effects on the spectral type indicators , while the rest must be attributed to other , more `` physical''reasons , such as , e.g. , different stellar structures as a function of metallicity or differences between observed and theoretical wind parameters etc . additional calculations are required to separate and evaluate these effects . @xmath8 our calculations predict that the amount of wind emission in he ii 4686 diminishes towards lower metallicities , so that at @xmath00.3 this line would appear only in absorption and could no longer serve as a reliable luminosity indicator . in particular , using this line to classify stars in low metallicity environments might artificially increase the number of low luminosity ( dws and gs ) o - stars identified in galaxies with lower metallicity , on the expense of the number of o - sgs . some hints about such effects seem to have been established already . for instance , massey et al . @xcite recently noted that in several of their mc targets the he ii 4686 emission is weaker than it might be expected , given their absolute magnitudes , . and although one might argue that a discrepantly high could be due to spectroscopic binarity , an alternative explanation in terms of metallicity effects is also possible , accounting for our present results . moreover , the number of sgs identified in the smc appears to be less than expected ( d. lennon , priv . comm . ) , in agreement with what might be expected from our calculations . _ acknowledgments : _ part of this work was performed during a visit of nm at the dept . of physics and astronomy of the johns hopkins university . the work was supported by nasa grant nag5 - 9219 ( nra-99 - 01-ltsa-029 , pi bianchi ) . j.p . acknowledges a travel grant by the dfg ( under grant pu 117/6 - 1 ) and by the bg nsf ( under grant f-1407/2004 ) .

based on an exteded grid of nlte , line blanketed model atmospheres with stellar winds as calculated by means of fastwind , we have investigated the change in the strengths of strategic helium transitions in the optical as caused by a 0.3 decrease in metallicity with respect to solar abundances . our calculations predict that only part of the observed increase in of o - type dwarfs could be explained by metallicity effects on the spectral type indicators , while the rest must be attributed to other reasons ( e.g. , different stellar structures as a function of metallicity or differences between observed and theoretical wind parameters etc . ) . in addition , we found that using the he ii 4686 line to classify stars in low metallicity environments ( @xmath0 0.3 ) might artificially increase the number of low luminosity ( dwarfs and giants ) o - stars , on the expense of the number of o - supergiants .

although peripartum cardiomyopathy ( ppcm ) was first described in 1880 , much is still unknown about its etiology , epidemiology , characteristics , and clinical outcome . the disease has a wide geographic spread , and is an important cause of heart failure ( hf ) in northern nigeria ; it is responsible for as high as 18.7% of all hf cases , and is as important as hypertension as a cause of hf among women . it is believed that left ventricular ( lv ) function recovers in 2341% of ppcm patients over time , and mortality rates also vary widely and could be as high as 16% at 6 months . however , robust outcome data from many parts of the world with high disease prevalence is still lacking . it is , therefore , imperative to study the disease in northern nigeria which has a modest health care capacity , in an attempt to better understand the disease . therefore , the present study aimed to describe the 1-year survival and left ventricular reverse remodeling ( lvrr ) in a cohort of ppcm patients from three referral hospitals in kano , nigeria . this was a longitudinal study carried out in three referral hospitals in kano , nigeria . before the commencement of the study , the research protocol was approved by the research ethics committees of the study centers and kano state hospitals management board . the study conformed to the ethical guidelines of the declaration of helsinki , on the principles for medical research involving human subjects . patients ' inclusion criteria were : ( i ) new diagnosis of ppcm before commencement of medical treatment ; ( ii ) onset of hf symptoms between last few months of pregnancy and first 5 months postpartum ; ( iii ) presenting between last few months of pregnancy and first 9 months postpartum ; ( iv ) at least 18 years of age ; ( v ) contact telephone number , except patients who gave reassurance that they were willing to attend the follow - up visits ; and ( vi ) giving written informed consent . ppcm was defined according to the recommendations of the hf association of the european society of cardiology working group on ppcm , and lv systolic dysfunction was defined as left ventricular ejection fraction ( lvef ) < 50% . at the study sites , physicians and obstetricians were approached and requested to refer all patients with suspected ppcm to the principal investigator ( pi ) for further evaluation at no cost . hospital in - patients with ppcm were clinically evaluated and underwent investigations within the first 48 h of admission . demographic data , relevant aspects of history and physical signs , results of investigations , medications , co - morbid conditions , and complications were included in a detailed questionnaire . for patients who did not have contact telephone number but who agreed to participate , attending the 1 month follow - up with the supervising physician was used as evidence of commitment and for inclusion . all patients were given appointment cards as a reminder , and were also telephoned to be informed of the 6 and 12 months follow - up visits . at the recruitment visit , each subject underwent a 12-lead electrocardiogram ( ecg ) at rest and transthoracic echocardiogram at the study centers according to standard recommendations . the echocardiographic examination was carried out using sonoscape s8 doppler ultrasound system ( shenzhen , china , 2010 ) . other baseline investigations recommended for the management of patients with ppcm were carried out in the laboratories of the study center , including plasma hemoglobin ; serum urea , electrolytes and creatinine ; blood counts ; liver enzymes ; and serum albumin . the pi re - evaluated the patients at 6 and 12 months follow - up , using the same protocol as at recruitment including ecg and echocardiogram examinations , but blood tests were not repeated . systemic hypertension was defined using standard cut - off values for systolic blood pressure ( sbp ) 140 mmhg and or diastolic blood pressure 90 mmhg . anemia was defined as hemoglobin < 12 g / dl , according to the recommendation of the world health organization in nonpregnant women , renal impairment as serum creatinine > 176 mol / l ( > 2 mg / dl ) , hyponatremia as serum sodium < 135 mmol / l , and hypoalbuminemia as serum albumin < 35 g / l . of the standard echocardiographic recordings obtained , lvrr was defined as the presence of both absolute increase in lvef 10.0% and decrease in left ventricular end - diastolic dimension indexed to body surface area ( lveddi ) 33.0 mm / m , while recovered lv systolic function as lvef 55% , at 12 months follow - up . lv diastolic function was defined and graded using transmitral flow and lv myocardial tissue doppler imaging velocities at the mitral annular level as follows : normal lv diastolic function : e : a ratio 12 , deceleration time ( dt ) 160230 ms and e / e ' < 8.grade i left ventricular diastolic dysfunction ( lvdd ) ( impaired myocardial relaxation ) : e : a < 1.0 and dt > 240 ms.grade ii lvdd ( pseudonormalized pattern ) : e : a 11.5 , dt 160230 ms , e ' < 7 cm / s , and e / e ' > 15.0.grade iii lvdd ( restrictive filling ) : e : a > 2.0 , dt < 160 ms , e ' < 7 cm / s , and e / e ' > 15.0 . normal lv diastolic function : e : a ratio 12 , deceleration time ( dt ) 160230 ms and e / e ' < 8 . grade i left ventricular diastolic dysfunction ( lvdd ) ( impaired myocardial relaxation ) : e : a < 1.0 and dt > 240 ms . grade ii lvdd ( pseudonormalized pattern ) : e : a 11.5 , dt 160230 ms , e ' < 7 cm / s , and e / e ' > 15.0 . grade iii lvdd ( restrictive filling ) : e : a > 2.0 , dt < 160 ms , e ' < 7 cm / s , and e / e ' > 15.0 . frequencies , mean , median , and inter - quartile ranges ( iqr ) were used to describe patients ' characteristics . chi - squared , fisher 's exact , student t and mann whitney u - tests were used to compare categorical and continuous variables as appropriate . spearman correlation coefficient and logistic regression models were used to assess potential associations between lvrr or mortality and variables of interest . two - sided p < 0.05 was considered as the minimum level of statistical significance . before the commencement of the study , the research protocol was approved by the research ethics committees of the study centers and kano state hospitals management board . the study conformed to the ethical guidelines of the declaration of helsinki , on the principles for medical research involving human subjects . patients ' inclusion criteria were : ( i ) new diagnosis of ppcm before commencement of medical treatment ; ( ii ) onset of hf symptoms between last few months of pregnancy and first 5 months postpartum ; ( iii ) presenting between last few months of pregnancy and first 9 months postpartum ; ( iv ) at least 18 years of age ; ( v ) contact telephone number , except patients who gave reassurance that they were willing to attend the follow - up visits ; and ( vi ) giving written informed consent . ppcm was defined according to the recommendations of the hf association of the european society of cardiology working group on ppcm , and lv systolic dysfunction was defined as left ventricular ejection fraction ( lvef ) < 50% . at the study sites , physicians and obstetricians were approached and requested to refer all patients with suspected ppcm to the principal investigator ( pi ) for further evaluation at no cost . hospital in - patients with ppcm were clinically evaluated and underwent investigations within the first 48 h of admission . demographic data , relevant aspects of history and physical signs , results of investigations , medications , co - morbid conditions , and complications were included in a detailed questionnaire . for patients who did not have contact telephone number but who agreed to participate , attending the 1 month follow - up with the supervising physician was used as evidence of commitment and for inclusion . all patients were given appointment cards as a reminder , and were also telephoned to be informed of the 6 and 12 months follow - up visits . at the recruitment visit , each subject underwent a 12-lead electrocardiogram ( ecg ) at rest and transthoracic echocardiogram at the study centers according to standard recommendations . the echocardiographic examination was carried out using sonoscape s8 doppler ultrasound system ( shenzhen , china , 2010 ) . other baseline investigations recommended for the management of patients with ppcm were carried out in the laboratories of the study center , including plasma hemoglobin ; serum urea , electrolytes and creatinine ; blood counts ; liver enzymes ; and serum albumin . the pi re - evaluated the patients at 6 and 12 months follow - up , using the same protocol as at recruitment including ecg and echocardiogram examinations , but blood tests were not repeated . systemic hypertension was defined using standard cut - off values for systolic blood pressure ( sbp ) 140 mmhg and or diastolic blood pressure 90 mmhg . anemia was defined as hemoglobin < 12 g / dl , according to the recommendation of the world health organization in nonpregnant women , renal impairment as serum creatinine > 176 mol / l ( > 2 mg / dl ) , hyponatremia as serum sodium < 135 mmol / l , and hypoalbuminemia as serum albumin < 35 g / l . of the standard echocardiographic recordings obtained , lvrr was defined as the presence of both absolute increase in lvef 10.0% and decrease in left ventricular end - diastolic dimension indexed to body surface area ( lveddi ) 33.0 mm / m , while recovered lv systolic function as lvef 55% , at 12 months follow - up . lv diastolic function was defined and graded using transmitral flow and lv myocardial tissue doppler imaging velocities at the mitral annular level as follows : normal lv diastolic function : e : a ratio 12 , deceleration time ( dt ) 160230 ms and e / e ' < 8.grade i left ventricular diastolic dysfunction ( lvdd ) ( impaired myocardial relaxation ) : e : a < 1.0 and dt > 240 ms.grade ii lvdd ( pseudonormalized pattern ) : e : a 11.5 , dt 160230 ms , e ' < 7 cm / s , and e / e ' > 15.0.grade iii lvdd ( restrictive filling ) : e : a > 2.0 , dt < 160 ms , e ' < 7 cm / s , and e / e ' > 15.0 . normal lv diastolic function : e : a ratio 12 , deceleration time ( dt ) 160230 ms and e / e ' < 8 . grade i left ventricular diastolic dysfunction ( lvdd ) ( impaired myocardial relaxation ) : e : a < 1.0 and dt > 240 ms . grade ii lvdd ( pseudonormalized pattern ) : e : a 11.5 , dt 160230 ms , e ' < 7 cm / s , and e / e ' > 15.0 . grade iii lvdd ( restrictive filling ) : e : a > 2.0 , dt < 160 ms , e ' < 7 cm / s , and e / e ' > 15.0 . frequencies , mean , median , and inter - quartile ranges ( iqr ) were used to describe patients ' characteristics . chi - squared , fisher 's exact , student t and mann whitney u - tests were used to compare categorical and continuous variables as appropriate . spearman correlation coefficient and logistic regression models were used to assess potential associations between lvrr or mortality and variables of interest . two - sided p < 0.05 was considered as the minimum level of statistical significance . a total of 72 patients were referred to the investigators with a diagnosis of ppcm based on clinical features and findings on chest radiograph . after further evaluation including echocardiography , 18 subjects ( 25.0% ) were excluded and the remaining 54 ( 75.0% ) were confirmed to have ppcm , and all were of hausa fulani ethnic group [ figure 1 ] . of these 54 patients , 29 had contact phone numbers and were contacted and the remaining 25 ( 46.3% ) did not have contact phone numbers , 4 ( 16.0% ) of whom qualified for follow - up . overall , therefore , 33 patients were followed up as shown in figure 1 . when the 21 patients who did not have contact phone numbers and did not attend follow - up were compared with the 33 followed up patients , their baseline characteristics were similar ( p > 0.05 ) except for the lower mean hemoglobin in the former group ( 11.5 2.0 g / dl ) compared with the latter group ( 12.8 1.6 g / dl ) ( p = 0.026 ) . flowchart of recruitment and follow - up of patients the age of the patients ranged between 18 and 45 years with a mean of 26.6 6.7 years , and 19 of them ( 35.2% ) were between 18 and 20 years , 24 ( 44.5% ) between 20 and 30 years , and the remaining 11 ( 20.4% ) were older than 30 years . no patient had a history of smoking , diabetes mellitus , alcohol drinking , stroke , or morbid arrhythmias . one patient had lv thrombus and developed lower limb gangrene needing bilateral below knee amputations . screening for human immunodeficiency virus was not carried out and none of the recruited patients was known to have the disease . patients ' body mass index ( bmi ) < 18.5kg / m ( under - weight ) was found in 14 ( 25.9% ) , 18.524.9 kg / m ( normal body weight ) in 29 ( 53.7% ) , 25.029.9 kg / m in 8 ( 14.8% ) , and 30.05 kg / m in only 2 ( 3.7% ) patients . nine ( 16.7% ) patients had hypotension ( sbp < 100 mmhg ) and 25 ( 46.3% ) had pregnancy - induced hypertension at presentation . two patients became pregnant again before the 6 months follow - up , and both survived follow - up ; their lvef increased from 43.5 5.0% at baseline to 52.5 5.0% and 54.5 3.5% at 6 and 12 months follow - up , respectively . of the 17 survivors at 12 months follow - up , 5 ( 29.4% ) had recovered lv systolic function ( lvef 55% ) , 10 ( 58.8% ) had increased lvef of at least 10% , and 8 ( 47.1% ) had reduced lveddi 33.0 mm / m [ table 1 ] . there was no relationship between the use of angiotensin converting enzyme inhibitors ( acei ) , angiotensin ii receptor blockers ( arb ) , beta - blockers ( p = 0.203 ) , other medications or echocardiographic variables ( p > 0.05 ) and lvrr ( p = 0.325 ) , in binary logistic regression models . characteristics of patients with and without lv reverse remodeling of note , mean lvef , lvedd , as well as left atrial ( la ) size and new york heart association ( nyha ) functional class all significantly improved at 6 months ( p < 0.05 ) , but the differences between the 6 and 12 months follow - upvalues were not statistically significant ( p > 0.05 ) [ figure 2a ] . furthermore , patients with lvrr had significantly shorter qrs duration than those without ( p = 0.003 ) . at 12 months , qrs duration correlated negatively with lvef ( r = 0.602 ; p = 0.018 ) and positively with left ventricular mass index ( lvmi ) ( r = 0.612 ; p = 0 , 012 ) . however , these associations were not significant ( p > 0.05 ) at baseline or 6 months follow - up . ( a)pattern of changes in left ventricular ejection fraction and end - diastolic dimension , left atrial dimension , and symptoms in peripartum cardiomyopathy patients over 1-year , ( b ) pattern of changes in left ventricular diastolic dysfunction in peripartum cardiomyopathy patients over 1-year the pattern and changes over 1-year of the lvdd are illustrated in figure 2b . at baseline , lvdd was found in a total of 48 patients ( 88.9% ) and 6 ( 11.1% ) had normal function . of the patients with lvdd , 44 ( 91.7% ) had grade iii , 1 ( 2.1% ) had grade ii , while the remaining 3 ( 6.3% ) had grade i lvdd . at 6 months follow - up , 12 patients ( 48.0% ) had normal lv diastolic function and 13 ( 52.0% ) had lvdd ( p = 0.003 compared with baseline results ) , while at 12 months 6 patients ( 35.3% ) had normal lv diastolic function and 11 ( 64.7% ) had lvdd ( p = 0.02 compared with baseline results ) . however , the prevalence of lvdd at 6 and 12 months follow - ups did not differ ( p = 0.414 ) . of the 33 patients followed up , 12 died ( 36.4% ) , 8 ( 66.7% ) within the first 6 months and the remaining 4 ( 33.3% ) before the 12 months follow - up , four patients were lost to follow - up ( 12.1% ) , and 17 ( 51.5% ) completed the follow - up [ figure 1 ] . the baseline characteristics of the 17 survivors ( 58.6% ) were similar to the deceased ( 41.4% ) except for lower serum albumin and lvmi , and higher plasma hemoglobin ( p < 0.05 ) [ table 2 ] . the mean nyha class for survivors reduced from 2.53 0.80 at baseline to 1.47 0.62 at 1-year follow - up ( p < 0.001 ) . none of these or other variables including lvrr predicted mortality in the regression models ( > 0.05 ) . the median survival time from diagnosis for the deceased patients was 20.0 ( iqr = 926 ) weeks . the age of the patients ranged between 18 and 45 years with a mean of 26.6 6.7 years , and 19 of them ( 35.2% ) were between 18 and 20 years , 24 ( 44.5% ) between 20 and 30 years , and the remaining 11 ( 20.4% ) were older than 30 years . no patient had a history of smoking , diabetes mellitus , alcohol drinking , stroke , or morbid arrhythmias . one patient had lv thrombus and developed lower limb gangrene needing bilateral below knee amputations . screening for human immunodeficiency virus was not carried out and none of the recruited patients was known to have the disease . patients ' body mass index ( bmi ) < 18.5kg / m ( under - weight ) was found in 14 ( 25.9% ) , 18.524.9 kg / m ( normal body weight ) in 29 ( 53.7% ) , 25.029.9 kg / m in 8 ( 14.8% ) , and 30.05 kg / m in only 2 ( 3.7% ) patients . nine ( 16.7% ) patients had hypotension ( sbp < 100 mmhg ) and 25 ( 46.3% ) had pregnancy - induced hypertension at presentation . two patients became pregnant again before the 6 months follow - up , and both survived follow - up ; their lvef increased from 43.5 5.0% at baseline to 52.5 5.0% and 54.5 3.5% at 6 and 12 months follow - up , respectively . of the 17 survivors at 12 months follow - up , 5 ( 29.4% ) had recovered lv systolic function ( lvef 55% ) , 10 ( 58.8% ) had increased lvef of at least 10% , and 8 ( 47.1% ) had reduced lveddi 33.0 mm / m [ table 1 ] . there was no relationship between the use of angiotensin converting enzyme inhibitors ( acei ) , angiotensin ii receptor blockers ( arb ) , beta - blockers ( p = 0.203 ) , other medications or echocardiographic variables ( p > 0.05 ) and lvrr ( p = 0.325 ) , in binary logistic regression models . characteristics of patients with and without lv reverse remodeling of note , mean lvef , lvedd , as well as left atrial ( la ) size and new york heart association ( nyha ) functional class all significantly improved at 6 months ( p < 0.05 ) , but the differences between the 6 and 12 months follow - upvalues were not statistically significant ( p > 0.05 ) [ figure 2a ] . furthermore , patients with lvrr had significantly shorter qrs duration than those without ( p = 0.003 ) . at 12 months , qrs duration correlated negatively with lvef ( r = 0.602 ; p = 0.018 ) and positively with left ventricular mass index ( lvmi ) ( r = 0.612 ; p = 0 , 012 ) . however , these associations were not significant ( p > 0.05 ) at baseline or 6 months follow - up . ( a)pattern of changes in left ventricular ejection fraction and end - diastolic dimension , left atrial dimension , and symptoms in peripartum cardiomyopathy patients over 1-year , ( b ) pattern of changes in left ventricular diastolic dysfunction in peripartum cardiomyopathy patients over 1-year the pattern and changes over 1-year of the lvdd are illustrated in figure 2b . at baseline , lvdd was found in a total of 48 patients ( 88.9% ) and 6 ( 11.1% ) had normal function . of the patients with lvdd , 44 ( 91.7% ) had grade iii , 1 ( 2.1% ) had grade ii , while the remaining 3 ( 6.3% ) had grade i lvdd . at 6 months follow - up , 12 patients ( 48.0% ) had normal lv diastolic function and 13 ( 52.0% ) had lvdd ( p = 0.003 compared with baseline results ) , while at 12 months 6 patients ( 35.3% ) had normal lv diastolic function and 11 ( 64.7% ) had lvdd ( p = 0.02 compared with baseline results ) . however , the prevalence of lvdd at 6 and 12 months follow - ups did not differ ( p = 0.414 ) . of the 33 patients followed up , 12 died ( 36.4% ) , 8 ( 66.7% ) within the first 6 months and the remaining 4 ( 33.3% ) before the 12 months follow - up , four patients were lost to follow - up ( 12.1% ) , and 17 ( 51.5% ) completed the follow - up [ figure 1 ] . the baseline characteristics of the 17 survivors ( 58.6% ) were similar to the deceased ( 41.4% ) except for lower serum albumin and lvmi , and higher plasma hemoglobin ( p < 0.05 ) [ table 2 ] . the mean nyha class for survivors reduced from 2.53 0.80 at baseline to 1.47 0.62 at 1-year follow - up ( p < 0.001 ) . none of these or other variables including lvrr predicted mortality in the regression models ( > 0.05 ) . the median survival time from diagnosis for the deceased patients was 20.0 ( iqr = 926 ) weeks . the present study describes the 1-year mortality and lvrr of a cohort of ppcm patients recruited from three referral hospitals in kano , nigeria . of the 33 patients ( 80% < 30 years old ) followed up , 47.1% had lvrr and 29.4% recovered lv systolic function . of the 29 remaining patients after excluding the four lost to follow - up , 17 survived ( 58.6% ) and 12 died ( 41.4% ) during the follow - up period , with a median survival time of 20 weeks . of the 17 survivors at 12 months follow - up , 47.1% satisfied the criteria for lvrr while 29.4% recovered lv systolic function . there was no relationship between the use of hf medications or other variables and lvrr in the regression models . in addition , significant improvement in mean lvef , lvedd , la size , lvdd , and nyha functional class had already manifested at 6 months , with no further significant improvement at 12 months follow - up . lvdd was similar ; showing a maximum fall in its prevalence from 89% at baseline to 52% at 6 months follow - up . therefore , lv recovery in our ppcm patients involved both systolic and diastolic functions , with maximum improvement achieved at 6 months follow - up in most patients , independent of aceis , arbs , and beta - blockers . however , almost all the patients were treated with frusemide , spironolactone , and digoxin , as a treatment for hf . our findings on lvrr seem to be similar to those previously reported from south africa ( 21% ) and haiti ( 28% ) but lower than what was reported from usa ( 54% ) likely because of the differences in the level of health care between the three countries . furthermore , the achievement of maximum recovery within 6 months in our cohort of patients is also supported by fett et al . and elkayam . finally , our inability to identify predictors of recovery of lv function or reverse remodeling , including hf medications , was similarly reported by fett et al . however , blauwet et al . found older age and smaller lv end - systolic dimension to be significant predictors of lv recovery among south africans . in addition , our results show that patients with lvrr had significantly shorter qrs duration than those without , and qrs duration correlated with lvef and with lvmi , but only at 1-year follow - up . thus , aside from mechanical remodeling , our results also show that electrical remodeling does occur in ppcm , and is likely related to the progression or otherwise of the lv disease . similar observations were previously made by shamim et al . among patients with dilated and ischemic cardiomyopathies . progressive lv disease eventually results in increased myocardial stiffness and a rise in diastolic pressures . the resulting increase in lv filling pressures and consequent ischemia of the subendocardium depolarization delay , which if prolonged could result in subendocardial fibrosis and permanent conduction disturbance . thus , in dilated and dysfunctioning ventricles , progressive broadening of the qrs complex can be taken as a marker of worsening of the ventricular disease . of the 29 patients with complete 12 months follow - up , 58.6% had significantly lower serum albumin and lvmi , and higher plasma hemoglobin than the deceased . however , none of these or other variables could predict mortality in regression models . two - thirds of the deaths occurred within 6 months of diagnosis while the remaining one - third died before the 12 months follow - up . much lower mortality rates of 13.0% over 6 months in south africa , 15.3% over 2 years in haiti , and 28.0% over 5 years in usa , respectively , have been reported . although some researchers did not identify any predictors of mortality in agreement with our finding , others reported inconsistent predictors of mortality including younger age at diagnosis , lower bmi , and echocardiographic variables . it is clearly difficult to compare mortality results between studies given the varying follow - up times and several other challenges including the possible strong influence of sociopolitical crises on the mortality . similar to our findings , 53.3% of those who died in the haiti study did so within 60 days after diagnosis . whitehead et al . also reported that in a cohort of ppcm patients in the usa , 18% of deaths occurred within 1-week and 87% within 6 months of diagnosis . therefore , most of the mortality in ppcm , as well as recovery , seem to occur within 6 months of diagnosis . although the reasons for these observations are not clear , they seem to give hope to patients of better outcomes once they survive the first 6 months of the disease . it is , therefore , imperative that patients are supported with optimal medical treatment to be able to survive the first 6 months of the disease . first , natriuretic peptides and other biomarkers of hf were not assessed because the tests were not readily available at the study centers . second , 21 out of 54 patients could not be followed up because they lacked phone numbers and so could not be contacted , and did not turn up for follow - up in spite of adequate counseling . however , these patients had similar baseline characteristics as those followed up except for their lower mean hemoglobin levels . of the 17 survivors at 12 months follow - up , 47.1% satisfied the criteria for lvrr while 29.4% recovered lv systolic function . there was no relationship between the use of hf medications or other variables and lvrr in the regression models . in addition , significant improvement in mean lvef , lvedd , la size , lvdd , and nyha functional class had already manifested at 6 months , with no further significant improvement at 12 months follow - up . lvdd was similar ; showing a maximum fall in its prevalence from 89% at baseline to 52% at 6 months follow - up . therefore , lv recovery in our ppcm patients involved both systolic and diastolic functions , with maximum improvement achieved at 6 months follow - up in most patients , independent of aceis , arbs , and beta - blockers . however , almost all the patients were treated with frusemide , spironolactone , and digoxin , as a treatment for hf . our findings on lvrr seem to be similar to those previously reported from south africa ( 21% ) and haiti ( 28% ) but lower than what was reported from usa ( 54% ) likely because of the differences in the level of health care between the three countries . furthermore , the achievement of maximum recovery within 6 months in our cohort of patients is also supported by fett et al . and elkayam . finally , our inability to identify predictors of recovery of lv function or reverse remodeling , including hf medications , was similarly reported by fett et al found older age and smaller lv end - systolic dimension to be significant predictors of lv recovery among south africans . in addition , our results show that patients with lvrr had significantly shorter qrs duration than those without , and qrs duration correlated with lvef and with lvmi , but only at 1-year follow - up . thus , aside from mechanical remodeling , our results also show that electrical remodeling does occur in ppcm , and is likely related to the progression or otherwise of the lv disease . similar observations were previously made by shamim et al . among patients with dilated and ischemic cardiomyopathies . progressive lv disease eventually results in increased myocardial stiffness and a rise in diastolic pressures . the resulting increase in lv filling pressures and consequent ischemia of the subendocardium depolarization delay , which if prolonged could result in subendocardial fibrosis and permanent conduction disturbance . thus , in dilated and dysfunctioning ventricles , progressive broadening of the qrs complex can be taken as a marker of worsening of the ventricular disease . of the 29 patients with complete 12 months follow - up , 58.6% had significantly lower serum albumin and lvmi , and higher plasma hemoglobin than the deceased . however , none of these or other variables could predict mortality in regression models . two - thirds of the deaths occurred within 6 months of diagnosis while the remaining one - third died before the 12 months follow - up . much lower mortality rates of 13.0% over 6 months in south africa , 15.3% over 2 years in haiti , and 28.0% over 5 years in usa , respectively , have been reported . although some researchers did not identify any predictors of mortality in agreement with our finding , others reported inconsistent predictors of mortality including younger age at diagnosis , lower bmi , and echocardiographic variables . it is clearly difficult to compare mortality results between studies given the varying follow - up times and several other challenges including the possible strong influence of sociopolitical crises on the mortality . similar to our findings , 53.3% of those who died in the haiti study did so within 60 days after diagnosis . whitehead et al . also reported that in a cohort of ppcm patients in the usa , 18% of deaths occurred within 1-week and 87% within 6 months of diagnosis . therefore , most of the mortality in ppcm , as well as recovery , seem to occur within 6 months of diagnosis . although the reasons for these observations are not clear , they seem to give hope to patients of better outcomes once they survive the first 6 months of the disease . it is , therefore , imperative that patients are supported with optimal medical treatment to be able to survive the first 6 months of the disease . , natriuretic peptides and other biomarkers of hf were not assessed because the tests were not readily available at the study centers . second , 21 out of 54 patients could not be followed up because they lacked phone numbers and so could not be contacted , and did not turn up for follow - up in spite of adequate counseling . however , these patients had similar baseline characteristics as those followed up except for their lower mean hemoglobin levels . this study has described the lvrr and 1-year survival of ppcm in three referral hospitals in kano , nigeria . lvrr occurred in almost half the patients at 6 months but was not predicted by any clinical or echocardiographic variable . our results also showed that lvrr was associated with shorter qrs duration which correlated with lvef and lvmi at 1-year follow - up , thus signifying electrical remodeling in ppcm . finally , none of the variables predicted the 41.4% mortality , of which two - thirds occurred before the first 6 months follow - up . the authors feel strongly that further studies should be carried out to better understand the disease .

background : peripartum cardiomyopathy ( ppcm ) is common in north - western nigeria . this study aimed to describe the 1-year survival and left ventricular reverse remodeling ( lvrr ) in a group of patients with ppcm from three referral hospitals in kano , nigeria.methods:ppcm was defined according to recommendations of the heart failure ( hf ) association of the european society of cardiology working group on ppcm . lvrr was defined as absolute increase in left ventricular ejection fraction ( lvef ) by 10.0% and decrease in left ventricular ( lv ) end - diastolic dimension indexed to body surface area 33.0 mm / m2 , while recovered lv systolic function as lvef 55% , at 12 months follow-up.results:a total of 54 newly diagnosed ppcm patients with mean age of 26.6 6.7 years , presented with classical features of predominantly left - sided hf and 33 of them qualified for follow - up . of the 17 survivors at 12 months , 8 patients ( 47.1% ) satisfied the criteria for lvrr , of whom 5 ( 29.4% ) had recovered lv systolic function ( lvef 55% ) , but lvrr was not predicted by any variable in the regression models . the prevalence of normal lv diastolic function increased from 11.1% at baseline to 35.3% at 12 months ( p = 0.02 ) . at 1-year follow - up , 41.4% of patients had died ( two - thirds of them within the first 6 months ) , but mortality was not predicted by any variable including lvrr.conclusions:in kano , ppcm patients had modest lvrr but high mortality at 1-year . further studies should be carried out to identify reasons for the high mortality and how to curb it .

in the investigation of the properties of vortices and vortex lattices in type - ii superconductors , direct imaging of the vortex positions at the surface of the material can be a useful tool . for magnetic fields of practical interest the distance between vortex lines becomes small ( roughly 50 nm at 1 t ) and scanning tunnelling microscopy ( stm ) gains an advantage over magnetic imaging techniques since stm is only sensitive to the vortex cores . a disadvantage of the technique is that the sample surface needs to be clean and conducting . for crystals , this can be done by breaking or cleaving , which has been successful for such materials as nbse@xmath2 @xcite or bi@xmath2ca@xmath2srcu@xmath2o@xmath3 @xcite . for thin films no such simple preparation method exists and since surfaces easily oxidize , reports on vortex imaging on superconducting films are relatively few . one way to overcome this problem is to protect the film surface with a thin capping layer of a noble metal such as au . as we showed before , this works well on films of @xmath0-mo@xmath1ge , a weakly pinning superconductor , capped with 3 nm au and clear images of the vortex structure could be obtained by mapping the proximity - induced gap at the au surface @xcite . the au layer should be flat , which means that au should be wetting the surface during deposition , and the interface should be transparent . neither condition is always met . for instance , although a reasonably flat au film forms on films of strongly pinning nbn , spectroscopy shows very unclear vortex images , presumably because the rough nbn surface causes a bad nbn / au interface . this can be overcome by depositing a thin ( 20 nm ) film of @xmath0-mo@xmath1ge followed by the au protection layer . clear vortex contrast could again be obtained , and showed the nbn vortex lattice ( vl ) to be completely disordered @xcite . + this use of a @xmath0-mo@xmath1ge / au template layer assumes that the vortex positions as fixed by the nbn layer are transferred in true fashion to the au surface , which should be the case when the @xmath0-mo@xmath1ge layer is too thin to yield appreciable bending or rearrangement of the vortex cores . in this work we further address this issue , which consists of two parts . the first involves the vortex - vortex interactions within the template layer , which might lead to reorientation of the vortices in that layer or , more specifically , to the recurrence of the well - ordered @xmath0-mo@xmath1ge vl . the second question is with respect to the coupling of the vortices in the two superconducting layers . if the interface has a metallic character , the proximity effect will play a major role in coupling the vortices ; if the surface of the host superconductor is insulating , as is often the case in oxide materials , the coupling may become of the josephson type , or merely electromagnetic , and this can allow freedom for the vortex in the template to move with respect to the one in the host . + the structure of the paper is as follows . we first introduce the experimental techniques and the data analysis process , in particular the use of the autocorrelation function . then we address the question of the length scale on which the disorder injected by the nbn layer is healed in the @xmath0-mo@xmath1ge template layer , by measuring samples with different ( template ) thicknesses @xmath4 of the @xmath0-mo@xmath1ge - layer . we show data on the variation of the autocorrelation functions as function of @xmath4 , and we discuss them by considering the bending modes of vortex lines in @xmath0-mo@xmath1ge . then we present experimental results on the issue of coupling , by studying heterostructure samples with a badly conducting or insulating interface layer . in the discussion , we consider the strength of the electromagnetic and josephson coupling forces which couple the vortex segments in the two superconducting layers . this coupling is in competition with the inter - vortex forces within the template layer , which tend to reorient the vortices to their triangular arrangement . in this work @xmath0-mo@xmath1ge is used as a template layer because of its suitable properties . with a ginzburg - landau parameter @xmath5 it is a strong type - ii superconductor , while its amorphous structure makes it a relatively weakly pinning material . furthermore , its large london penetration depth @xmath6 yields a small tilt modulus @xmath7 , which means that the vl retains a two - dimensional ( 2d ) character up to quite large thicknesses , as will be discussed below . finally , amorphous materials show very flat surface characteristics . the @xmath0-mo@xmath1ge layers were rf - sputtered from a composite mo / ge target in ar atmosphere . the film thickness ranged from 25 nm to 100 nm . when necessary , we denote the thickness by @xmath0-mo@xmath1ge(x ) , with x the thickness in nm . during sputtering the substrate was water - cooled and after each minute of sputtering , and interruption of 1 minute was made to prevent heating and possible recrystallization of the films . the sputtering rate was chosen as @xmath8 nm / minute . the superconducting transition temperature @xmath9 was 5.7 k for the 25 nm films , increasing up to @xmath10 k for @xmath11 nm , after which @xmath9 became constant . the critical current for onset of vortex motion for a 500 nm thick film was found to be or the order of @xmath12 a / m@xmath13 . also relevant is the value of the critical field @xmath14 at the measurement temperature of 4.2 k , which was about 4.2 t for @xmath4 = 25 nm , increasing to 5.2 t for @xmath4 = 50 nm and beyond . the stm measurements were performed in fields up to 1 t , which means maximum reduced fields @xmath15 0.2 - 0.3 . + the strongly pinning nbn films ( @xmath16 a / m@xmath13 ) were reactively rf - sputtered from a nb target in an ar / n@xmath2 atmosphere on si substrates . throughout the study , we used a thickness of 67 nm . the films are polycrystalline , as is known from high resolution transmission electron microscopy studies @xcite . the rms - roughness of the films was determined by afm to be 1.5 nm , measured on a fresh nbn surface area of 1 @xmath17 1 @xmath18 m . the films showed a @xmath9 of 11.4 k and a superconducting coherence length @xmath19 nm . + protective au films were rf - sputtered in two steps . first , about 2 nm was sputtered in a pure ar atmosphere ; next , oxygen ( partial pressure 5 % ) was mixed in the sputtering gas , and another layer of 2 nm was sputtered . this o@xmath2-addition promotes the formation of smaller au grains which improves the resolution of the measurements . + i/@xmath20v for two samples , acquired at t = 4.2 k and b = 0.3 t. ( a ) sample nbn / moge(50)/au(6 ) ; ( b ) sample nbn / moge(50)/au(10),width=321 ] the stm - setup was the same as in a previous report @xcite , with the sample immersed in liquid he after it was mounted in air . in this procedure field - cooled measurements are not possible , since the level of the liquid is higher than the magnet . all data were therefore taken by zero - field - cooling the sample , and then increasing the magnetic field . for all experiments we employed full current(i)-voltage(v ) spectroscopy , with a single curve consisting of 200 - 300 points . the voltage range was chosen such that a good fit could be made to the ohmic resistance outside the gap region , in practise typically @xmath21 mv . several curves were taken per pixel , and images typically contained 128 @xmath17 128 pixels . the total acquisition time for such an image was of the order of 30 minutes to 1 hour , depending on the surface quality . the maximum scan size , for the given grid , is determined by the vortex core size . the vortex signature is visible in a region with a diameter of roughly 4 @xmath22 , and needs about 3 pixels in this region for a proper determination . this yields 7 nm per pixel , and a scan size of maximally 0.9 @xmath18 m . the vortex positions were found by taking the ratio of the zero - bias and high - bias slopes , as obtained by numerical differentiation . theoretically , this is a value between 0 ( full gap ) and 1 ( no gap ) . in practise the gap is not well developed due to the finite temperature and the proximizing au layer and in the gap regime the ratio is of the order 0.8 . the resulting range ( 0.8 to 1 ) is then translated into a grey scale . [ fig1:gaps ] shows the effect of the thickness of the au layer by comparing the gaps for two samples nbn / moge(50)/au , where the first one has a au layer thickness of 6 nm , while the au layer of the second one is almost two times thicker . + m @xmath17 1.2 @xmath18 m . the raw data were smoothed with a gaussian filter of 1 pixel width ; ( b ) triangulation representation of the vl . the lines represent bonds , the symbols denote deviations from the 6-fold coordination of the perfect trangular lattice ( triangles ( squares ) : 7-fold ( 5-fold ) coordination ) ; ( c ) normalized autocorrelation map . ( d ) cross - section of the autocorrelation map along the white line in ( c ) . the inset gives the central part of the 2d - fourier transform of the direct - space image given in ( a),width=302 ] a useful way of determining the amount of correlation of vortex positions is to compute the two - dimensional autocorrelation function @xmath23 for a given image , defined as @xmath24 . the function computes the overlap of the image with a copy of itself which is displaced by a vector @xmath25 . in the actual calculation , the result is normalised in order to correct for the decreasing amount of datapoints available with increasing @xmath26 . [ fig2:vl - autocorr ] gives the result of this procedure for a vl imaged on a @xmath0-mo@xmath1ge - film of 48 nm thick at an applied field @xmath27 of 0.8 t. triangulation ( fig . [ fig2:vl - autocorr]b ) shows that the vl is quite free of defects . the autocorrelation map of @xmath23 ( fig . [ fig2:vl - autocorr]c ) shows very little blurring towards the edges , and makes evident that the vl has both high translational and rotational bond order . by making a cross - section along a direction from the center of the image through one of the points of the hexagon , the loss of correlations can be quantified . [ fig2:vl - autocorr]d ) shows such a cross - section , plotted in units @xmath28 and normalized to the value at @xmath29 . here , @xmath30 the intervortex distance given by @xmath31 . it appears that @xmath32 ( somewhat arbitrarily defined as the displacement vector where the autocorrelation function does not show lattice periodicity anymore ) is larger than 16 @xmath30 @xcite . in contrast , the vl in nbn is almost completely disordered , as shown in fig . [ fig3:nbn ] for a 50 nm film with a au capping layer . in this case , we find @xmath33 and almost no orientational correlation . note also the relatively poor quality of the vortex image , due to the fact that no @xmath0-mo@xmath1ge - template layer is present . next we shall investigate how this disorder propagates through an intervening @xmath0-mo@xmath1ge layer . in order to investigate on what length scale the vl disorder starts to approach the @xmath0-mo@xmath1ge hexagonal lattice again , we recorded vortex images at three field values ( 0.2 t or 0.3 t , 0.7 t or 0.8 t , and 1 t ) for nbn/@xmath0-mo@xmath1ge / au samples with @xmath4 = 0 , 25 , 50 and 100 nm . -mo@xmath1ge(d@xmath34)/au , with @xmath4 = 25 nm , 50 nm , 100 nm acquired at t = 4.2 k and fields of either b = 0.7 t or 0.8 t as indicated . the lower right - hand corner shows real space data.,width=302 ] in fig . [ fig4:autocorr - d ] we show the autocorrelation ( acr ) results computed from the raw vortex images as measured in either @xmath35 or @xmath36 t , for the samples with @xmath4 = 0 , 25 , 100 nm , together with one real image for @xmath4 = 50 nm as a sample of the data quality . since the contrast and the noise - level of the data are affected by the varying experimental conditions the relevance lies in the the periodicity of the structures . the gray - scale of the acr - images is chosen such that the structure of the data is clearly visible . from the data it appears that for the thinnest @xmath0-mo@xmath1ge layer , the vortex positions are basically unchanged . the first ring at @xmath37 stands out more clearly , but that is simply due to the better data quality . there is also some increased intensity at the hexagon corners , indicating the onset of orientational order . on increasing the thickness of the @xmath0-mo@xmath1ge layer we find that both the transversal and orientational order develops more and more . this is better followed in the cross - sections of the acr - images presented in fig . [ fig5:cross - d ] . -mo@xmath1ge(d@xmath34)/au , with @xmath4 = 0 nm , 25 nm , 50 nm , and 100 nm acquired at t = 4.2 k and fields of either b = 0.7 t or 0.8 t as indicated . , width=321 ] clearly , the reordering occurs but slowly . for @xmath4 = 25 nm , @xmath38 at all fields . for 100 nm , this has increased to about 4 ( in the 0.8 t data ) or maybe 6 ( in the 1 t data ) . although the signature for healing therefore is unequivocally present , the order at a @xmath0-mo@xmath1ge thickness of 100 nm is still far less than in the unconstrained vortex lattice . in order to understand this length scale , we next consider the length over which a vortex line can bend . this involves both tilting the line and shearing it with respect to the whole vl . starting from a 2d collectively pinned vl , we can estimate the film thickness where the first bending starts to be relevant . the extent to which deformations can develop in the transverse and longitudinal direction depends on the balance of the tilt and shear energy densities @xmath39 which are given in the elastic limit by @xmath40 for shear deformations ( with @xmath41 the shear modulus of the vl ) and @xmath42 ( with @xmath7 the tilt modulus of the vl ) for tilt deformations of a vortex in a medium where @xmath43 and @xmath44 respectively are the transversal and longitudinal axis of the cigar - shaped surface with constant displacement @xmath45 ( with @xmath46 in order to be in the linear regime ) . the energy balance leads to a relation for the ratio between @xmath43 and @xmath44 : @xmath47 this means that if we set the typical length scale for longitudinal deformations to the film thickness ( @xmath48 ) , the typical transverse length scale @xmath43 is set by the square root of the ratio of the elastic constants . the smallest transverse length scale is simply given by @xmath49 . the thickness @xmath50 where these deformations start to be relevant can be obtained by neglecting the very small dispersion of @xmath41 and taking for @xmath51 : @xmath52 where @xmath53 ; in the last step we made use of the fact that @xmath54 , as well as that @xmath55 ( making a field correction for @xmath56 unnecessary ) . since @xmath56 is very large , we use the non - local expression . the wavevector @xmath57 for tilt deformations runs from 0 to @xmath58 , the brillouin zone boundary . in a circular approximation the brillouin zone boundary is given by @xmath59 . in principle one should integrate over all the values for @xmath57 , but from eq . [ c44 ] we find that the large @xmath60-contributions dominate , leading to the approximation : @xmath61 in case of a given vortex length @xmath20 the wavevector @xmath62 for tilt deformations is quantized : @xmath63 with @xmath64 . since we are looking for the case that the vortex line just starts to bend , we are interested in the case where the @xmath65 mode becomes relevant , which leads to the expression @xmath66 it can easily be seen that the relevance of higher order terms goes down with @xmath67 . together with eq . [ elasticbalance ] we have an expression for the maximum film thickness @xmath50 for which deformations of the vortex line by bending are absent . the dependence of @xmath50 on @xmath68 is plotted in fig . [ fig6:bending ] using the parameters for @xmath0-mo@xmath1ge . we find that in the experimental regime of @xmath69 for having a 2d system the thickness of the @xmath0-mo@xmath1ge film should be smaller than @xmath70 nm . + going back to the data , it appears that at 100 nm the first bending mode becomes relevant , especially for @xmath71 . this was not to be expected immediately . for a vortex lattice with strong disorder the length at which the first bending mode appears might actually be much larger , due to the strong renormalization of the elastic constants resulting from the forced disorder . still , the conclusion is that apparently this consideration is less important , and the scale on which healing starts to appear can be estimated by considering the first bending mode , while , on the other hand , more modes are needed to fully restore the vl . , the maximum film thickness for which ( tilt ) deformations are absent in @xmath0-mo@xmath1ge - films , on the reduced magnetic field @xmath68,width=226 ] in order to investigate how the interface between nbn and @xmath0-mo@xmath1ge affects the vortex postions , we prepared a variety of samples with a nbn layer of 67 nm , a 50 nm thick @xmath0-mo@xmath1ge layer and a @xmath723.5 nm au layer , where we gradually reduced the interface transparency . next to a reference sample , we first prepared a sample for which the nbn layer was exposed to pure o@xmath2 gas ( @xmath73 mbar for 15 minutes ) prior to the deposition of the @xmath0-mo@xmath1ge / au layers . the oxidized layer produced in this way is very thin ; oxidation in air at temperatures of 180 @xmath74c or less is known to oxidize only the first one or two atomic layers @xcite . to reduce the interface transparency even more we deposited an insulating al@xmath2o@xmath75 interface layer of 1 nm or 4 nm thick in between the nbn layer and the @xmath0-mo@xmath1ge layer . + in figs . [ fig7:acr - interfaces ] , [ fig8:cross - interfaces ] we present a selection of the acr - images and cross - sections as produced from the raw - data vortex images measure at 4.2 k for various values of @xmath27 . -mo@xmath1ge(50)/au , taken at 0.7 t ; ( middle ) nbn(67)/al@xmath2o@xmath75(1)/@xmath0-mo@xmath1ge(50)/au , taken at 0.7 t ; ( right ) nbn(67)/al@xmath2o@xmath75(4)/@xmath0-mo@xmath1ge(50)/au , taken at 0.3 t.,width=321 ] from the acr - data it can be clearly seen that on changing the interface from perfect and thin to insulating and thick the decoupling of the vortex lattices in the two superconducting layers rapidly sets in , showing already a clear structure for the sample with the oxidized nbn surface . -mo@xmath1ge(50/au , nbn(67)/nbno/@xmath0-mo@xmath1ge(50)/au , nbn(67)/al@xmath2o@xmath75(1)/@xmath0-mo@xmath1ge(50)/au , and nbn(67)/al@xmath2o@xmath75(4)/@xmath0-mo@xmath1ge(50)/au , taken at 0.3 t , at different magnetic fields as indicated . in the left - hand panel , the data on nbn(67)/au were taken at 0.2 t , all others at 0.3 t.,width=321 ] from the cross - sections , for the oxided surface we find a value for @xmath76 of about 4 , for the 1 nm al@xmath2o@xmath75 about 7 , and for the 4 nm al@xmath2o@xmath75 larger than 8 ( the maximum for this image size ) , in other words , the 4 nm insulating interface has completely decoupled the @xmath0-mo@xmath1ge vortex lattice from the one in the nbn . + to gain some qualitative understanding for this behavior , we assume that the vortex positions in the template layer are the result of a competition between two forces . one is the josephson coupling force , which keeps the vortices in the template in registry with the those on the other side of the interface . the other is the elastic force which wants to restore the ordered abrikosov lattice , and which we equate to the shear force necessary to displace a vortex line from its equilibrium position in the lattice . in principle , also the electromagnetic force works to maintain registry , but a simple estimate shows that the electromagnetic coupling is much smaller than the josephson coupling for the very thin interfaces under consideration . we refer this point to the end of the discussion . + starting with the shear force , for small displacements @xmath77 from the ideal lattice positions ( the elastic limit ) the typical force @xmath78 necessary to move a single vortex line inside the template layer of length @xmath4 over a distance @xmath45 is given by @xmath79 where the extrapolation formula of brandt @xcite is used for the elastic modulus @xmath41 . this approach does not take into account that the vl may be disordered ( not in equilibrium ) , and may contain defects which soften the lattice , so it should be considered as an upper limit . by rewriting @xmath80 , with @xmath81 and using the fact that @xmath82 , we can also write @xmath78 in terms of the quantity @xmath83 as @xmath84 for the josephson coupling force , we start from the expressions for the josephson energy @xmath85 as function of a displacement of the vortex segment @xmath45 , given in ref . @xcite : @xmath86 + here , the josephson length @xmath87 is given by @xmath88 , with @xmath89 the thickness of the insulating layer and @xmath90 the anisotropy parameter of the system defined by @xmath91 = @xmath92 = @xmath93 . these expressions for @xmath85 are derived from fitting the numerical solutions of a model which consist of two stacks of pancake vortices in an anistropic superconductor ( characterised by its anisotropy parameter @xmath90 ) , displaced with respect to each other by @xmath45 . for very small displacements , the expression for @xmath85 is equivalent to an earlier one given by koshelev and vinokur : @xmath94 @xcite . for larger displacements , @xmath85 becomes linear in @xmath45 , which means the josephson force @xmath95 becomes constant and is simply given by @xmath96 we use this expression as an estimate for the maximum josephson force @xcite . comparing it to the shear force of eq . [ eq : shear ] , the condition for @xmath97 becomes @xmath98 not surprisingly , the result says that the necessary displacement for the shear force to win from the josephson coupling force is inversely proportional to the length of the vortex in the template layer ( @xmath4 ) , and also inversely proportional to the anisotropy parameter . for our experiments , typical values are @xmath4 = 50 nm and b = 0.3 t , which corresponds to @xmath30 = 89 nm and @xmath99 1 , leading to @xmath100 . assuming a value of @xmath101 0.3 for full disorder , the template layer will become ordered due to shear stress for @xmath90 @xmath102 20 this is a very reasonable number for the 4 nm al@xmath2o@xmath75 interface layer . in a study on multilayers of @xmath0-mo@xmath1ge / ge @xcite , the following values for @xmath103 are quoted : ( 4.5 nm , 7 ) ; ( 5.5 nm , 13 ) , ( 6.5 nm , 22 ) . the strong increase with @xmath89 obviously reflects the exponential dependence of the coupling through an insulating interface , and the numbers given above make it quite reasonable to expect that decoupling has not yet been achieved for al@xmath2o@xmath75(1 ) , but occurs for al@xmath2o@xmath75(4 ) . also , the result indicates that the field dependence of the shear modulus is hardly important in comparison with the dependence on the interface thickness and for given @xmath89 , either coupled or decoupled behavior can be expected for all fields , as is indeed observed . + with the expression for the josephson coupling force , it is simple to show that the electromagnetic coupling force between two vortex segments can be neglected in our considerations . it was shown by clem @xcite that , for two superconductors characterized by penetration depths @xmath104 , with thickness @xmath105 ( @xmath106 ) , separated by an insulating layer of thickness @xmath89 ( ( @xmath107 ) , the _ maximum _ force @xmath108 as function of the displacement of the vortex segments with respect to each other is given by @xmath109 here we neglected a weak field dependence which occurs in the regime of interacting vortices , which would lower @xmath108 further . writing eq . [ eq : em ] as @xmath110 , we find that @xmath111 = @xmath112 . with @xmath20 of order 50 nm and @xmath56 of order 500 nm for both nbn and @xmath0-mo@xmath1ge , @xmath108 is an order of magnitude lower than @xmath95 at the thickness @xmath89 where @xmath78 starts to win from @xmath95 . we should note , however , that this may not be the case for superconductors with smaller values for @xmath56 . in conclusion , we have used the technique of vortex core imaging by low - temperature stm to study the restoring of initial disorder in a vortex lattice . the disorder was engineered by depositing a weakly pinning superconducting thin film of @xmath0-mo@xmath1geon a strongly pinning layer of nbn . by varying the thickness of the weakly pinning layer , and the interface conditions between both layers , we could reach several conclusions with respect to the healing mechanisms . for clean interfaces we found that the thickness where reordering of the vortex lattice is first observed can be linked to the first bending mode of the vortex lines , without the need to renormalize the elastic constants in the presence of such strong disorder . for our @xmath0-mo@xmath1ge layers , this thickness is around 75 nm . we then used layers with a thickness well below this value in order to investigate the restoration of the vortex lattice when making the interface more insulating . here we find that the results can be understood in a straightforward way by comparing the josephson force working to align vortex segments over the interface with the elastic restoring forces inside the weakly pinning layer . this work is part of the research program of the `` stichting voor fundamenteel onderzoek der materie ( fom ) '' , which is financially supported by nwo . we are grateful to a. e. koshelev for making us aware of the results of ref . @xcite . 99 h. f. hess , r. b. robinson , r. c. dynes , j. m. valles and j. v. waszczak , phys . lett . * 62 * , 214 ( 1989 ) . a. m. troyanovski , j. aarts and p. h. kes , nature * 399 * , 665 ( 1999 ) . renner , b. revaz , k. kadowaki , i. maggio - aprile and . fischer , phys . lett . * 80 * 3606 ( 1998 ) . fischer et al . g. j. c. v. baarle , a. m. troianovsky , t. nishizaki , p. h. kes and j. aarts , appl . . lett . * 82 * , 1081 ( 2003 ) . a. pruymboom , w.h.b . hoondert , h.w . zandbergen and p.h . kes , jpn . * 26 , suppl . 26 - 3 , 1529 ( 1987 ) . @xmath32 is equivalent to the 2d correlation length in the vortex lattice for the overlapping vortex regime ( @xmath68 @xmath102 0.3 ; see e. h. brandt , phys . * 57 * , 1347 ( 1986 ) ) r.p . frankenthal , d.j . siconolfi , w.r . sinclair , d.d . bacon , j. electrochem . * 130 , 2056 ( 1983 ) . brandt , phys . status solidi b*77 * , 551 ( 1976 ) . y. y. goldschmidt and s. tyagi , phys . b * 71 * , 014503 ( 2005 ) . koshelev , v.m . vinokur , phys . b * 57 , 8026 ( 1998 ) . in ref . @xcite the case is considered of a kink in a line of pancake vortices , and a correction is proposed to the expression for the josephson energy in order to take proper account of the fact that the line is not stiff and the kink will be spread over several pancake segments . in our case the line segments are stiff , and the correction would not be appropriate . w. r. white , a. kapitulnik and m. r. beasley , phys . b * 50 * , 6303 ( 1994 ) . j. r. clem , phys . b * 12 * , 1742 ( 1975 ) .

in a sandwich consisting of two superconducting films , one weakly pinning and one strongly pinning , the vortex positions in both films are determined by the strongly pinning material and the vortex lattice is disordered in both films . we used ( strongly pinning ) nbn and ( weakly pinning ) @xmath0-mo@xmath1ge and studied , by directly imaging the vortex core positions with a scanning tunnelling microscope , how this disorder is restored with increasing thickness of @xmath0-mo@xmath1ge layer or when the interface is made insulating . for clean interfaces we find that the first reordering of the vortex lattice is found at a layer thickness wich is compatible with the first bending mode of the vortex lines . making the interface insulating we find that order is restored quickly . we argue that this is can be understood from the competition between the josephson force working on the vortex segments on the one hand , and the elastic restoring forces inside the weakly pinning layer on the other hand .

here we describe a plasma configuration whose exact asymptotic solution can be obtained in a strong coupling limit . the solution is given by the ion sphere result presented by salpeter @xcite plus a simple smaller correction . this is accomplished by using the effective plasma field theory methods advocated by brown and yaffe @xcite . in this field - theory language , the old salpeter result corresponds to the tree approximation and our new correction is the one - loop term . in usual perturbative expansions , the tree approximation provides the first , lowest - order term for weak coupling . here , on the contrary , the tree approximation provides the leading term for strong coupling , with the corrections of higher order in the _ inverse coupling_. this is the only example of which we are aware in which the tree approximation yields the strong coupling limit . this strongly coupled system is interesting from a theoretical point of view and our results can be used to check numerical methods . the plasma consists of very dilute `` impurity '' ions of very high charge @xmath0 , @xmath1 , in thermal equilibrium with a classical , one - component `` background '' plasma of charge @xmath2 and number density @xmath3 , at temperature @xmath4 . the background plasma is neutralized in the usual way , and it is dilute . we use rationalized electrostatic units and measure temperature in energy units so that the background plasma debye wave number appears as @xmath5 the internal coupling of the background plasma is described by the dimensionless coupling parameter @xmath6 the assumed weak coupling of the dilute background plasma is conveyed by @xmath7 although the internal coupling of the background plasma to itself is assumed to be very weak and the impurity ions are assumed to be so very dilute that their internal interactions are also very small , we shall require that the ionic charge @xmath8 is so great that the coupling between the impurity ions and the background plasma is very large . to make this condition more precise , we define @xmath9 which is the magnitude of the impurity charge measured in units of the dilute background ionic charge . then the explicit condition that we require is that @xmath10 since the limit that we use may appear to be obscure , we pause to clarify it . even though @xmath11 , we assume that @xmath12 is sufficiently small that @xmath13 . we may , for example , take @xmath14 with @xmath15 , and @xmath16 in the interval @xmath17 . then @xmath18 while @xmath19 . standard methods express the grand canonical partition function in terms of functional integrals . brown and yaffe @xcite do this , introduce an auxiliary electrostatic potential , and integrate out the charged particle degrees of freedom to obtain the effective theory . this technique will be described in more detail in sec . [ rem ] below . the saddle point expansion of this form for the grand partition function yields a perturbative expansion , with the tree approximation providing the lowest - order term . here , on the contrary , we express the _ impurity ion number _ in terms of an effective field theory realized by a functional integral . the saddle point of this form of the functional integral involves a classical field solution driven by a strong point charge . the result for the impurity ion number reads @xmath20 here @xmath21 is the number of impurity ions defined by the chemical potential @xmath22 in the absence of the background plasma ; keeping this chemical potential fixed , the background plasma alters this number to be @xmath23 . the added @xmath24 stand for corrections to the analytical evaluation of the classical action displayed in the @xmath25 and @xmath26 terms of eq . ( [ num ] ) . the sizes of these omitted corrections are compared to the exact numerical evaluation of the action in fig . [ ratio ] below . this figure shows that the relative sizes of these terms are small ( @xmath27 ) in the limit in which we work ( @xmath28 ) . the constant @xmath29 . the final @xmath30 term in the exponent is the relatively small one - loop correction . as shown in detail in the discussion leading to eq . ( [ correct ] ) below , the error in the result ( [ num ] ) is of the indicated order @xmath31 and is thus negligible in the limit @xmath32 that concerns us . the number correction ( [ num ] ) can be used to construct the grand canonical partition function @xmath33 for the combined system by integrating the generic relation @xmath34 for @xmath35 and using the boundary condition that @xmath36 as @xmath37 . since @xmath23 depends upon the chemical potential @xmath22 only in the factor @xmath38 , this integration gives @xmath39 here we have identified the constant of integration , the constant that remains when @xmath23 vanishes , to be @xmath40 , the number of background plasma particles in the absence of the impurity ions . in our limit in which the background plasma is very weakly coupled , @xmath41 is just the number of non - interacting particles of chemical potential @xmath42 . the equation of state can be found from the well - known relation for a grand canonical ensemble with partition function @xmath33 , @xmath43 however , the grand canonical partition function @xmath33 is a function of the temperature and chemical potentials and , to obtain the equation of state , we must re - express it in terms of the observed , physical particle numbers rather than their chemical potentials . to do this , we need to express @xmath41 in terms of the true number of background particles @xmath44 , a number that differs from @xmath40 because of the presence of the impurity ions . there is a significant difference because , although the impurity ions are few in number , they are assumed to be extremely highly charged . we again use the general formula ( [ number ] ) , but this time to compute @xmath44 using the solution ( [ solution ] ) : @xmath45 the measured impurity number @xmath46 does depends upon @xmath47 because it entails the dimensionless coupling parameter @xmath12 defined in eq . ( [ gee ] ) . for simplicity of exposition , in that definition we used a debye wave number @xmath48 that was defined in terms of the true background density @xmath3 . although the distinction is not important for the leading terms that concern us , we nevertheless note that the correct wave number that appears in our functional integral formalism involves the ` bare ' number density @xmath49 , with @xmath50 , and so @xmath51 hence , @xmath52 using this relation to determine @xmath40 in terms of the physical quantities @xmath44 and @xmath46 places relationship ( [ pressure ] ) of the pressure to the partition function ( [ solution ] ) in the proper form of an equation of state . to simply bring out the main point , we include here only the leading terms , to obtain @xmath53 although the fraction of impurity ions in the plasma @xmath54 may be quite small , there may be a significant pressure modification if @xmath55 is very large . note that the free particle contribution , an additional term of @xmath23 , is omitted here since it is not multiplied by the large factor in the term that we have retained . the number result ( [ num ] ) also directly yields the plasma correction to a nuclear fusion rate , since @xmath56 where @xmath57 is the nuclear reaction rate for a thermal , maxwell - boltzmann distribution of the initial ( 1,2 ) particles in the absence of the background plasma . we use the notation @xmath58 to denote an effective particle that carries the charge @xmath59 . this formula was obtained in a different guise by dewitt , graboske , and cooper @xcite . the relation of the form ( [ xrated ] ) that we use to previous results is discussed in detail in the appendix . the formula holds when the coulomb barrier classical turning point of the nuclear reaction is small in comparison with the plasma debye length . this is spelled out in detail in a recent work by brown , dooling , and preston @xcite who also show that the result ( [ xrated ] ) is valid even if the background plasma involves quantum corrections . the conditions needed for the formula ( [ xrated ] ) to hold are also discussed in the work of brown and sawyer @xcite , although sometimes in a rather implicit fashion . this work does show , however , that the result ( [ xrated ] ) is valid if @xmath60 , where @xmath61 is the debye wave number and @xmath62 is the turning point radius defined by @xmath63 where @xmath64 is the imaginary time frequency associated with the temperature @xmath65 . it should be remarked that dewitt , graboske , and cooper @xcite assumed that the nuclear reaction rate formula ( [ xrated ] ) held only if the background plasma had a classical character , but that the work of brown , dooling , and preston @xcite shows that it is valid even if the plasma involves quantum effects . our result ( [ num ] ) for the number corrections presents the plasma correction to the fusion rate for our special case as @xmath66 \right\ } \nonumber\\ & & \,\ , \exp\left\ { \left({\,9\ , \over g}\right)^{1/3 } { \cal c } \left [ \left(\bar z_{1}+\bar z_{2}\right)^{2/3 } - \bar z_{1}^{2/3 } - \bar z_{2}^{2/3 } \right ] \right\ } \ , . \nonumber\\ & & .\end{aligned}\ ] ] the first line agrees with salpeter s calculation @xcite ; the second is new . again the correction can be large . we turn now to describe the basis for these results in detail . to begin , we need to review a simple case of the general plasma effective field theory formulation presented by brown and yaffe @xcite . first we note that the grand canonical partition function for a one - component classical plasma may be expressed as the functional integral ( which are discussed in detail , for example , in the first chapter of the book by brown @xcite ) , @xmath67 \ , \exp\bigg\ { - \int ( d^3{\bf r } ) \big [ { \beta \over 2 } \ , \big ( \nabla \chi({\bf r } ) \big)^2 \nonumber\\ & & \qquad\qquad\qquad -g_s\,\lambda^{-3 } e^{\beta\mu } \ , e^{ize\beta \ , \chi({\bf r } ) } \big ] \bigg\ } \ , . \label{fun}\end{aligned}\ ] ] here @xmath68 defines the thermal wave length @xmath69 of the plasma particles of mass @xmath70 . these particles have a chemical potential @xmath42 and spin weight @xmath71 so that their density in the free - particle limit is given by @xmath72 we use rationalized gaussian units so that , for example , the coulomb potential appears as @xmath73 . we shall be a little cavalier about the uniform , rigid neutralizing background that we tacitly assume to be present . we shall explicitly include its effects when needed . the validity of the functional integral representation ( [ fun ] ) is easy to establish . the second part in the exponential is written out in a series so as to produce the fugacity expansion @xmath74 \ , \exp\bigg\ { - \int ( d^3{\bf r } ) \big [ { \beta \over 2 } \ , \big ( \nabla \chi({\bf r } ) \big)^2 \nonumber\\ & & \qquad\qquad + i ze \beta \chi({\bf r } ) \ , \sum_{a=1}^n \ , \delta ( { \bf r } - { \bf r}_a ) \big ] \bigg\ } \,.\end{aligned}\ ] ] this gaussian functional integral can be performed by the functional integration field variable translation @xmath75 since @xmath76 and the laplacian @xmath77 can be freely integrated by parts in the quadratic form @xmath78 , after the translation a gaussian functional integration appears with quadratic form @xmath79 with no coupling linear in @xmath80 . the original measure @xmath81 = [ d\chi']$ ] is taken to include factors such that this remaining purely gaussian function integral is simply unity . for pedagogical clarity , we make use of the definition ( [ lambda ] ) of the thermal wavelength to write the result of these manipulations as @xmath82\right\ } \ , . \nonumber\\ & & \end{aligned}\ ] ] this is precisely the familiar fugacity expansion of the classical grand canonical partition function . the diagonal sum where @xmath83 in the coulomb potential must be deleted . this omission of the infinite self - energy terms is automatic if the dimensional regularization scheme is employed as advocated by brown and yaffe @xcite . here we shall instead regulate the theory by ( at first implicitly ) replacing the point source @xmath84 with a source @xmath85 that has a small extent about @xmath86 and ( at first implicitly ) removing the self energy terms , with the limit @xmath87 finally taken in the subtracted theory . the derivative of the logarithm of a grand canonical partition function with respect to a chemical potential ( times @xmath88 ) gives the particle number conjugate to that chemical potential . thus , if we temporarily add another particle species @xmath89 of charge @xmath90 to the previous functional integral , take the described derivative , and then take the limit in which this new species is very dilute , we get the desired functional integral representation for the background plasma correction to the new species free particle number relation in the presence of plasma interactions , @xmath91 e^ { i z_p e \beta \chi({\bf 0 } ) } \exp\bigg\{\ ! - \ ! \int ( d^3{\bf r } ) \big [ { \beta \over 2 } \ , \big ( \nabla \chi({\bf r } ) \big)^2 \nonumber\\ & & \qquad - n \ , \bigg ( e^{ize\beta \ , \chi({\bf r } ) } - 1 - ize \beta \ , \chi({\bf r } ) \bigg ) \ , \big ] \bigg\ } \ , . \label{clever}\end{aligned}\ ] ] to express this more precisely , in eq . ( [ clever ] ) @xmath92 , where the subscript @xmath89 is used to indicate that these are the properties of the sparsely populated ` impurity ' ions of charge @xmath90 , with @xmath93 denoting the system volume . ( [ clever ] ) describes the background plasma correction to the free - particle chemical potential number relationship for these @xmath89 ions immersed in the weakly - coupled , one - component plasma . the original chemical potential derivative that leads to this result entailed a volume integral . in virtue of the translational invariance of the background plasma , the result is independent of the particular value of the spatial coordinate in the electric potential @xmath94 in the initial factor , and this coordinate may be placed at the origin ( as we have done ) , giving the factor @xmath95 shown . the volume integral then combines to form the total free - particle number @xmath96 that appears as a prefactor . we have now subtracted terms from the second exponential , the exponential of the action functional of the background plasma , to remove an overall number contribution and to include the effect of the rigid neutralizing background . these same subtractions must now be made in the normalizing partition function @xmath33 that appears in the denominator of eq . ( [ clever ] ) . thus @xmath97 is defined by the functional integral of the second exponential that appears in eq . ( [ clever ] ) . the effect of the uniform neutralizing rigid background charge is contained in the term @xmath98 that is subtracted from the exponential @xmath99 . the additional @xmath100 is subtracted from this exponential for convenience . to simplify the notation , we write eq . ( [ clever ] ) as simply @xmath101 \ , e^{-s[\chi ] } \ , , \label{compact}\ ] ] where the effective action @xmath102 $ ] contains all the terms in both exponents in eq . ( [ clever ] ) . the loop expansion is an expansion about the saddle point of the functional integral . at this point , the action @xmath102 $ ] is stationary , and thus the field @xmath103 at this point obeys the classical field equation implied by the stationarity of the action . the tree approximation is given by the evaluation of @xmath102 $ ] at the classical solution @xmath104 namely @xmath105 = - \int ( d^3{\bf r } ) \bigg\ { { \beta \over 2 } \,\big(\nabla \phi_{\rm cl}({\bf r } ) \big)^2 \nonumber\\ & & + n \left [ e^{- \beta ze \ , \phi_{\rm cl}({\bf r } ) } - 1 + \beta ze \ , \phi_{\rm cl}({\bf r } ) \right ] - \beta z_pe \delta({\bf r } ) \ , \phi_{\rm cl}({\bf r } ) \bigg\ } \ , , \nonumber\\ & & \label{action}\end{aligned}\ ] ] whose stationary point defines the classical field equation @xmath106 + z_p e \ , \delta({\bf r } ) \ , . \label{obey}\ ] ] this equation defining the classical potential @xmath107 is of the familiar debye - hckel form , and it could have been written down using simple physical reasoning . however , we have placed it in the context of a systematic perturbative expansion in which the error of omitted terms can be ascertained . in particular , we shall describe the one - loop correction that is automatically produced by our formalism . moreover , we shall prove that higher - order corrections may be neglected . our approach using controlled approximations in which the error is assessed , and making precise evaluations of a well defined perturbative expansions in terms of correctly identified coupling parameters , differs in spirit from much of the traditional work in plasma physics . for example , although previous work has been done by vieillefosse @xcite on the solution of the non - linear debye - hckel equation , this work was not done in the context of a systematic , controlled approximation . the one - loop correction to this first tree approximation is obtained by writing the functional integration variable as @xmath108 and expanding the total action in eq . ( [ compact ] ) to quadratic order in the fluctuating field @xmath80 . since @xmath109 obeys the classical field equation , there are no linear terms in @xmath80 and we have , to quadratic order , @xmath110 & = & s[i\phi_{\rm cl } ] \nonumber\\\ & + & { \beta \over 2 } \ , \int ( d{\bf r } ) \ , \chi'({\bf r } ) \ , \left [ - \nabla^2 + \kappa^2 \ , e^ { - \beta ze \ , \phi_{\rm cl}({\bf r } ) } \right ] \ , \chi'({\bf r } ) \ , , \nonumber\\ & & \end{aligned}\ ] ] where @xmath111 is the squared debye wave number of the mobile ions . the resulting gaussian functional integral produces an infinite dimensional , fredholm determinant . in this same one - loop order , the normalizing partition function @xmath33 is given by the same determinant except that it is evaluated at @xmath112 . hence , to tree plus one - loop order , @xmath113 \over { \rm det}^{1/2 } \left [ - \nabla^2 + \kappa^2 \ , e^{-\beta ze \ , \phi_{\rm cl } } \right ] } \ , \exp\left\{- s[i \phi_{\rm cl } ] \right\ } \,.\ ] ] to solve the classical field equation ( [ obey ] ) in the large @xmath8 limit , we first note that the classical potential must vanish asymptotically so as to ensure that the resulting total charge density vanishes at large distances form the ` external ' point charge @xmath90 , @xmath114 \to 0 \ , . \label{neut}\ ] ] since @xmath115 vanishes asymptotically , its defining differential equation ( [ obey ] ) reduces at large distances to @xmath116 and thus , for @xmath117 large , @xmath118 since this is exponentially damped , the coordinate integral of the left - hand side of eq . ( [ obey ] ) vanishes by gauss theorem , and we obtain the integral constraint @xmath119 = z_p \ , . \label{intc}\ ] ] for small @xmath120 , the point source driving term in the classical field equation dominates , giving the coulomb potential solution @xmath121 thus we write @xmath122 where @xmath123 and the point driving charge @xmath124 is now conveyed in the boundary condition @xmath125 the other boundary condition is the previously noted large @xmath126 limit ( [ large ] ) which now appears as @xmath127 the action ( [ action ] ) corresponding to the classical solution is divergent since it includes the infinite self - energy of the point charge @xmath128 impurity . this self - energy must be subtracted to yield the finite , physical action . following standard practice in quantum field theory , the divergent classical action ( [ action ] ) and the self - energy are first regularized rendered finite by replacing the point charge with a finite source . the self - energy is then subtracted , and finally the point source limit is taken . regularization is achieved by the replacement @xmath129 , where @xmath130 is a smooth function of compact support . the regularized action obtained by making this substitution in the action @xmath131 $ ] defined by eq . ( [ action ] ) will be denoted as @xmath132 . the regularized self field @xmath133 is the solution of @xmath134 and it defines the self - action @xmath135 the identity @xmath136 which is easily verified through partial integration and use of the field equation obeyed by @xmath137 can be used to write the self - energy action ( [ tocast ] ) as @xmath138 which is just the impurity s field energy divided by the temperature . it is convenient to use this form ( [ alt ] ) in subtracting off the self - energy from @xmath132 and to also subtract the identity @xmath139 proved in the same manner as eq . ( [ alt ] ) . the point source limit @xmath140 can now be taken to secure the well - defined result @xmath141 \to s_{\rm sub}[i\phi_{\rm cl } ] = \nonumber\\ & & - \beta \int \left ( d^3{\bf r } \right ) \ , { 1\over2 } \ , \left [ \nabla \big ( \phi_{\rm cl}({\bf r } ) - \phi^p_{\rm self}({\bf r } ) \big ) \right]^2 \nonumber\\ & & - n \int \left ( d^3{\bf r } \right ) \ , \left [ e^{- \beta ze \ , \phi_{\rm cl}({\bf r } ) } - 1 + \beta ze \ , \phi_{\rm cl}({\bf r } ) \right ] , \label{sub}\end{aligned}\ ] ] where @xmath142 is the point - source limit of the self - field . using the form ( [ udef ] ) for the classical solution we have , remembering that @xmath143 , @xmath144 ^ 2 \nonumber\\ & & = { ( z_p e)^2 \over 4\pi } \ , \left [ { du(r ) \over dr } - { 1 \over r } \ , \big ( u(r ) - u(0 ) \big ) \right]^2 \nonumber\\ & & = { ( z_pe)^2 \over 4\pi } \ , \left\ { \left ( { du(r ) \over dr } \right)^2 - { d \over dr } \ , \left [ { 1 \over r } \ , \big ( u(r ) - u(0 ) \big)^2 \right ] \right\ } \ , . \nonumber\\ & & \end{aligned}\ ] ] the final total derivative that appears here gives a null result since the end - point contributions vanish . hence the subtracted action ( [ sub ] ) now appears as @xmath145 = - \int_0^\infty dr \bigg\ { { \beta \over 2 } \ , { z_p^2 e^2 \over 4\pi } \ , \left ( { du \over dr } \right)^2 + 4\pi r^2 \ , n \nonumber\\ & & \qquad \left [ \exp\left\ { - { \beta z_p z e^2 \over 4\pi r } \ , u \right\ } - 1 + { \beta z_p z e^2 \over 4\pi r } \ , u \ , \right ] \bigg\ } \,.\end{aligned}\ ] ] changing variables to @xmath146 and using the previously defined plasma coupling constant @xmath147 gives @xmath148 & = & - \int_0^\infty d\xi \bigg\ { { \bar z_p^2 g \over 2 } \ , \left ( { du(\xi ) \over d\xi } \right)^2 \nonumber\\ & + & { \xi^2 \over g } \ , \left [ \exp\left\ { - { \bar z_pg \over \xi } \ , u(\xi ) \right\ } - 1 + { \bar z_p g \over \xi } \ , u(\xi ) \ , \right ] \bigg\ } \ , . \nonumber\\ & & \label{aaction}\end{aligned}\ ] ] requiring that this new form of the action be stationary produces the classical field equation @xmath149 \ , . \label{equation}\ ] ] note that the integral constraint ( [ intc ] ) now reads @xmath150 = \bar z_p \ , . \label{intcc}\ ] ] in the large @xmath55 limit which concerns us , the short distance form ( [ short ] ) ( multiplied by @xmath151 ) is large ( compared to one ) over a wide range of @xmath117 , and the boltzmann factor @xmath152 is quite small in this range . we are thus led to the `` ion sphere model '' brought forth some time ago by salpeter @xcite . this model makes the step - function approximation @xmath153 placing this in the integral constraint ( [ intcc ] ) determines the ion sphere radius @xmath154 to be given by @xmath155 in the ion sphere model , the classical field equation ( [ equation ] ) becomes @xmath156 and this has the solution , obeying the initial condition @xmath157 , @xmath158 \ , , & \mbox{$ \xi < \xi_0 \ , , $ } \\ 0 \ , , & \mbox{$ \xi > \xi_0 \ , . $ } \end{array } \right . \label{answer}\ ] ] here the term linear in @xmath159 , a solution of the homogeneous equation , has been determined by the continuity at the ion sphere surface , the condition that @xmath160 . [ without this constrain an additional @xmath161 would appear on the right - hand side of eq . ( [ sphereeq ] ) . ] the nature of this `` ion - sphere '' solution @xmath162 together with the exact solution @xmath163 obtained by the numerical integration of eq . ( [ equation ] ) , as well as the first correction described below , are displayed in fig . [ uofxi ] . ( solid line ) , ion sphere model @xmath162 ( short - dashed line ) , and the first correction @xmath164 ( long - dashed line ) . for @xmath165 , @xmath166 ; here @xmath167.,width=264,height=151 ] we have appended the subscript @xmath168 to indicate that this is the solution for the ion sphere model . placing this solution in the new version ( [ aaction ] ) of the action gives @xmath169 = { 3 \bar z_p \over10 } \ , ( 3 g \bar z_p)^{2/3 } - \bar z_p \ , . \label{sphact}\ ] ] the final @xmath170 that appears here comes from the @xmath171 $ ] term in the action ( [ aaction ] ) along with the integral constraint ( [ intcc ] ) . this additional @xmath170 simply adds a constant to the chemical potential . since a constant has no dependence on the thermodynamic parameters , this addition has no effect on the equation of state , the internal energy density , or any other measurable thermodynamic quantity . moreover , the contributions of such constants clearly cancels in the ratio ( [ xrated ] ) that yields the background plasma correction to the nuclear reaction rate . to find the leading correction to the ion sphere model result , we first cast the exact equations in a different form . we start by writing the full solution @xmath163 as @xmath172 where @xmath162 is the solution ( [ answer ] ) to the ion sphere model ( [ sphereeq ] ) . the exact differential equation ( [ equation ] ) now reads @xmath173 \ , . \nonumber\\ & & \label{neweq}\end{aligned}\ ] ] since @xmath174 is fixed ( reflecting the presence of the large , ` impurity ' point charge @xmath124 ) , and since the solution must vanish at infinity , the proper solution to the non - linear differential equation ( [ neweq ] ) is defined by the boundary conditions @xmath175 on substituting the decomposition ( [ vdef ] ) into the action ( [ aaction ] ) , the cross term may be integrated by parts with no end - point contributions in virtue of the boundary conditions ( [ bc ] ) on @xmath176 . we take advantage of this to move the derivative of @xmath176 over to act upon @xmath162 so that we now have @xmath177 . using eq . ( [ sphereeq ] ) for this second derivative and identifying the ion sphere part then gives @xmath148 & = & s_0[i\phi_{\rm cl } ] - { \xi_0 \over g } \ , \int_{\xi_0}^\infty d\xi \ , \xi \ , v(\xi ) \nonumber\\ & & \qquad - { \xi_0 ^ 2 \over 2 g } \ , \int_0^\infty d\xi \ , \left ( { dv(\xi ) \over d\xi } \right)^2 \ , . \label{aaaction}\end{aligned}\ ] ] thus far we have made no approximations . to obtain the leading correction to the ion sphere result , we note , as we have remarked before , that the factor @xmath178 is very small for @xmath179 , and so it may be evaluated by expanding @xmath162 about @xmath180 . using the result ( [ answer ] ) , we find that the leading terms yield @xmath181 this approximation is valid for all @xmath159 because when @xmath159 is somewhat smaller than @xmath182 and our expansion near the end point breaks down , the argument in the exponent is so large that the exponential function essentially vanishes . indeed , since we consider the limit in which @xmath182 is taken to be very large and the gaussian contribution is very narrow on the scale set by @xmath182 , we may approximate @xmath183 here the delta function accounts for the little piece of area that the gaussian provides near the ion sphere radius since @xmath184 with this approximation , an approximation that gives the leading correction for the large @xmath185 limit in which we work , eq . ( [ neweq ] ) becomes @xmath186 \ , . \nonumber\\ & & \label{diffeq}\end{aligned}\ ] ] it is easy to see that the first correction @xmath187 does not alter the integral constraint ( [ intcc ] ) . placing the decomposition ( [ vdef ] ) in the constraint ( [ intcc ] ) and using the leading - order form ( [ leader ] ) together with @xmath176 replaced by @xmath187 can be used to express the putative change in the constraint ( [ intcc ] ) in the form @xmath188 \bigg\ } \ , . \nonumber\\ & & \end{aligned}\ ] ] but eq . ( [ diffeq ] ) and partial integration together with the boundary conditions ( [ bc ] ) now show that @xmath189 the @xmath190 in eq . ( [ diffeq ] ) requires that @xmath191 and @xmath192 since @xmath193 and since @xmath194 , we have @xmath195 where @xmath196 is a constant that is yet to be determined . for large @xmath159 , @xmath187 is small and thus obeys the linearized version of eq . ( [ diffeq ] ) , @xmath197 giving @xmath198 since this damps rapidly on the scale set by @xmath199 , the leading correction @xmath187 that we seek is given by the solution to @xmath200 which is the previous differential equation ( [ diffeq ] ) in this region , but with the explicit factors of @xmath201 and @xmath202 replaced by @xmath100 . this new approximate second - order , non - linear differential equation is akin to a one - dimensional equation of motion of a particle in a potential with @xmath159 playing the role of time , and @xmath187 playing the role of position . thus there is an `` energy constant of the motion '' . namely , if we multiply eq . ( [ ddiffeq ] ) by @xmath203 , we obtain a total derivative with respect to @xmath159 whose integral gives @xmath204 where the constant @xmath205 that appears on the right - hand side follows from the limiting form as @xmath206 . it is easy to show that @xmath207 since asymptotically @xmath187 decreases when @xmath159 increases , we must choose the root @xmath208 } \ , . \label{slope}\ ] ] the different functional forms for @xmath187 in the two regions @xmath209 and @xmath165 are joined by the continuity constraint ( [ con ] ) , which we write simply as @xmath210 together with the slope jump ( [ discon ] ) which , using eq . ( [ slope ] ) , now requires that @xmath211 } = \sqrt{\pi \over 2 } \ , e^{- v_1(\xi_0 ) } - { v_1(\xi_0 ) \over \xi_0 } \,.\ ] ] since we require that @xmath212 , the second term on the right - hand side of this constraint may be neglected , which results in a transcendental equation defining @xmath213 , whose solution is @xmath214 we are now in a position to evaluate the leading contribution to the action ( [ aaaction ] ) . since @xmath187 damps rapidly on the scale set by @xmath182 , in computing the leading term we can set @xmath215 in the integral that is linear in @xmath187 . the leading correction is given by @xmath216 \simeq s_0[i\phi_{\rm cl } ] + s_1 \,,\ ] ] in which @xmath217 where @xmath218 here we have omitted the portion @xmath219 because it is parametrically smaller it is of relative order @xmath220 to the leading terms that we retain . we change variables from @xmath159 to @xmath164 via @xmath221 and use the result ( [ slope ] ) for the derivative . hence @xmath222 } } \nonumber\\ & & + { 1\over2 } \ , \int_0^{v_1(\xi_0 ) } dv_1 \ , \sqrt { 2 \ , \left [ e^ { - \ , v_1 } + v_1 - 1 \right ] } \end{aligned}\ ] ] is a pure number , @xmath223 in summary , recalling that @xmath224 , we now find that @xmath225 + \bar z_p & = & { 3 \bar z_p \over 10 } \ , \left ( 3g\bar z_p \right)^{2/3 } \ , \left\ { 1 + { 10 \ , { \cal c } \over 3 g \bar z_p } \right\ } \ , , \nonumber\\ & & \label{next}\end{aligned}\ ] ] with the leading correction to the ion sphere model exhibited as being of relative order @xmath226 . [ ratio ] displays the exact numerical evaluation of the action compared with the ion sphere approximation [ the leading term in eq . ( [ next ] ) ] and the corrected ion sphere model [ the entire eq . ( [ next ] ) ] . - \bar z_p$ ] for the ion sphere model result ( [ sphact ] ) [ short - dashed line ] and the corrected ion sphere model ( [ next ] ) [ long - dashed line ] to corresponding difference with the action ( [ aaction ] ) for the exact numerical solution @xmath163 as functions of @xmath227.,title="fig:",width=264,height=151 ] + the one - loop correction for the background plasma with no `` impurity '' ions present is given by @xcite @xmath228 = \exp\left\ { \int ( d^3{\bf r } ) \ , { \kappa^3 \over 12 \pi } \right\ } \,.\ ] ] since we assume that the charge @xmath55 of the `` impurity '' ions is so large that not only @xmath229 , but also @xmath230 as well , @xmath231 , and the ion sphere radius @xmath232 is large in comparison to the characteristic distance scale for spatial variation in the background plasma , the debye length @xmath233 . in this case , the term @xmath234 in the one - loop determinant that enters into the background plasma correction to the `` impurity '' number , @xmath235\ ] ] can be treated as being very slowly varying essentially a constant except when it appears in a final volume integral . we conclude that in this case of very strong coupling , @xmath236 \over { \rm det}^{1/2 } \left [ - \nabla^2 + \kappa^2 \ , e^{- \beta ze \phi_{\rm cl } } \right ] } \nonumber\\ & = & \exp\left\{- { \kappa^3 \over 12 \pi } \ , \int ( d^3{\bf r } ) \ , \left [ 1 - \exp\left\ { - { 3\over2 } \beta ze \phi({\bf r } ) \right\ } \right ] \right\ } \nonumber\\ & = & \exp\left\{- { \kappa^3 \over 12 \pi } \ , { 4\pi \over 3 } \ , r_0 ^ 3 \right\ } = \exp\left\ { - { 1\over3 } \ , g \bar z_p \right\ } \ , , \label{oneloop}\end{aligned}\ ] ] where in the second equality we have used the ion sphere model that gives the leading term for large @xmath55 . this result is physically obvious . the impurity ion of very high @xmath55 carves out a hole of radius @xmath232 in the original , background plasma , a hole that is a vacuum as far as the original ions are concerned . the original , background plasma is unchanged outside this hole . this ion sphere picture gives the leading terms for very large impurity charge @xmath55 . the corrections that smooth out the sharp boundaries in this picture only produce higher - order terms . the original , background plasma had a vanishing electrostatic potential everywhere , and the potential in the ion sphere picture now vanishes outside the sphere of radius @xmath232 . thus the grand potential of the background plasma is now reduced by the amount that was originally contained within the sphere of radius @xmath232 , and this is exactly what is stated to one - loop order in eq.([oneloop ] ) . this argument carries on to the higher loop terms as well , but we shall now also sketch the application of the previous formal manipulations to them as well . as shown in detail in the paper of brown and yaffe @xcite , @xmath3-loop terms in the expansion of the background plasma partition function with no impurities present involve a factor of @xmath237 which combines with other charge and temperature factors to give dimensionless terms of the form @xmath238 with the very high @xmath55 impurity ions present , each factor of @xmath48 is accompanied by @xmath239 whose spatial variation can be neglected except in the final , overall volume integral . thus , in the strong coupling limit of the type that we have set , we have the order estimate @xmath240 \nonumber\\ & & \qquad\qquad \sim g^{n-1 } \ , \kappa^3 r_0 ^ 3 \sim g^n \ , \bar z_p \ , . \label{correct}\end{aligned}\ ] ] again , since we assume that @xmath12 is sufficiently small so that although @xmath241 , @xmath242 , all the higher loop terms may be neglected . in this discussion , we have glossed over the powers of @xmath243 that enter into the higher - order terms as well as the quantum corrections that can occur in higher orders . they vanish in our strong coupling limit . we thank hugh e. dewitt and lawrence g. yaffe for providing constructive comments on preliminary versions of this work . we write the result ( [ xrated ] ) in the form used by brown , dooling , and preston @xcite ( bdp ) which is not the notation of dewitt , graboske , and cooper @xcite ( dgc ) . in the grand canonical methods employed by bdp , the temperature and chemical potentials are the basic , fundamental parameters . thus , in this grand canonical description , the effect of the background plasma on nuclear reaction rates appears in terms of number changes with the chemical potentials held fixed . on the other hand , in the canonical ensemble description employed by dgc , the temperature and particle numbers are the basic , fundamental parameters . to connect the two approaches , for the relevant case in which `` impurity '' ions @xmath89 are dilutely mixed in a background plasma , we first note the general structure in the grand canonical method . since the impurities are very dilute , the effect of the background plasma on their number is entirely contained in the first term of the fugacity expansion , the linear term in @xmath244 . in the free - particle limit where there is no coupling of the impurities to the background plasma , the impurity number density chemical potential connection reads @xmath245 where @xmath246 and @xmath247 are the impurities spin weight and thermal wavelength , respectively . thus the effect of the background plasma appears as @xmath248 where we have chosen to write the plasma correction in terms of an exponential . the only feature of the correction @xmath249 that we need note is that it is independent of the impurity fugacity @xmath250 since we are working in the @xmath251 limit . in summary , the correction in the grand canonical description appears as @xmath252 with the total number @xmath253 , where @xmath93 is the volume of the system . the grand canonical partition function @xmath33 for the complete system including the various impurity ions defines the thermodynamic potential @xmath254 via @xmath255 and the particle number @xmath256 of species @xmath257 with chemical potential @xmath258 is given by @xmath259 hence , since generically @xmath260 , this can be integrated to produce @xmath261 where @xmath262 is the thermodynamic potential of the background plasma in the absence of the extra impurity ions and where , as we have just shown , @xmath263 the canonical partition function @xmath264 defines the helmholtz free energy @xmath265 via @xmath266 with the connection @xmath267 since @xmath268 the helmholtz free energy for a free gas of impurities is thus given by @xmath269 \,.\ ] ] the additional ionic impurities change the background plasma free energy from @xmath270 where the sum runs over all the particles in the plasma except for the impurity ions , to @xmath271 using eq s . ( [ fb ] ) , ( [ f ] ) , and ( [ ob ] ) produces @xmath272 and , since @xmath22 is fixed in terms of the free gas number densities @xmath273 , we find that @xmath274 thus , in the canonical ensemble approach employed by dgc @xcite , the previous number ratio is expressed in terms of a helmholtz free energy change , @xmath275 these authors sometimes write this in terms of a ` chemical potential ' . however , within the grand canonical description that we always employ , a chemical potential is an independent variable that is not changed as interactions are altered , and so in the context that we use this nomenclature is not suitable ..

the ion sphere model introduced long ago by salpeter is placed in a rigorous theoretical setting . the leading corrections to this model for very highly charged but dilute ions in thermal equilibrium with a weakly coupled , one - component background plasma are explicitly computed , and the subleading corrections shown to be negligibly small . this is done using the effective field theory methods advocated by brown and yaffe . thus , corrections to nuclear reaction rates that such highly charged ions may undergo can be computed precisely . moreover , their contribution to the equation of state can also be computed with precision . such analytic results for very strong coupling are rarely available , and they can serve as benchmarks for testing computer models in this limit .

ever since hubble s famous paper outlined his classification system @xcite , morphological classification in conjunction with physical measurement has become an important tool in extragalactic astrophysics . a number of quantitative classifiers have been developed or extended over the years to probe the structure of galaxies . there are parametric classifiers like radial multi - gaussian deconvolution @xcite , bulge - disk decomposition @xcite , etc . , and the nonparametric ones such as the c - a system @xcite , artificial neural nets trained from visual classification sets @xcite , gini coefficient @xcite and so on . as one of the main quantitative criteria and a function of the hubble classification , the bulge - disk decomposition has now been widely used as an effective method to examine galaxy structures and morphological properties , ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * etc ) . the variations of galaxy physical properties with morphology and environment are crucial in our understanding of the evolution of galaxies @xcite . numbers of properties such as the integrated birthrate variation @xcite , the optical and infrared photometric properties @xcite , the star formation properties of galaxies in clusters @xcite , the circumnuclear h@xmath9 luminosity and bar structures @xcite , etc , which have been investigated present regularity or correlation along different morphological types . through substantial former investigations , it is known that as a result of different stellar populations and the amount of dust and gas for the environment of star - forming , the early - type galaxies ( ellipticals and lenticulars ) exhibit rather different properties compared with the late - type ones ( spirals , irregulars and so on ) . as we know , averagely one third of the total luminosity from normal galaxies is absorbed and re - radiated by dust @xcite , and even higher fraction from galaxies with the most active star - forming activity ( e.g. luminous infrared galaxies ( ligs ) , * ? ? ? * ; * ? ? ? . both the infrared space observatory ( iso - * ? ? ? * ) and _ spitzer _ space telescope @xcite continued to explore the importance of dust . studies of dusty starburst galaxies @xcite have shown that , most of the activities ( e.g. , star - formation and/or agn emission ) in these galaxies are hidden by dust , and the bolometric luminosities of the active systems are mostly emitted in the infrared . this suggests that the infrared emission is a sensitive tracer of the young stellar population and star formation rates ( sfrs ) , and suffers weaker extinction . the mir dust emissions mainly consist of polycyclic aromatic hydrocarbons ( pahs ) emission and the continuum emission feature of warm dust component . both of these two components have been investigated as reliable measures of the sfrs of galaxies as a whole @xcite . whereby studies in the mir properties will certainly improve our understanding of the galaxies which have been well studied in the optical bands , and give an insight into the details of their star formation histories . this work tries to explore the relationships between the morphology and the mir properties , for a flux - limited sample of normal galaxies which were selected from the galaxies of sdss - dr4 @xcite cross - correlated with the _ spitzer _ swire @xcite . considering that the _ spitzer _ irac ( fazio et al . 2004 ) @xmath10 band covers the strongest pah feature ( @xmath11 ) , and the mips ( rieke et al . 2004 ) @xmath4 band covers the continuum emission of very small grains ( vsgs ) free of pah features , we tried to employ the irac bands and mips @xmath4 band to investigate the mir dust properties of entire galaxies . we performed elliptical aperture photometric analysis in both the optical and mir bands . the @xmath10 dust and @xmath4 dust luminosity and their dust - to - star ratios are used to quantitatively investigate the mir properties of our sample galaxies . two ways to classify the morphologies of the sample galaxies were adopted : the @xmath6 type of the revised hubble classification system @xcite by visual inspection , and the quantitative parameter of @xmath2 by the bulge - disk decomposition . in 2 , we describe the infrared and optical data , the sample construction , and the elliptical aperture photometry . the morphological classifications are presented in 3 . in 4 , we analyze the optical and mir colors , and give the statistical results of the mir dust properties against galaxy morphological types and the corresponding discussions . the conclusions are presented in 5 . throughout this paper , we assume a hubble constant @xmath12 and @xmath13 , @xmath14 in calculating the distance and the luminosity . we used the irac @xmath15 and the mips @xmath4 images from the northern swire fields of lockman hole , elais - n1 , and elais - n2 . the bcd ( basic calibrated data ) images of the four irac bands were obtained from _ spitzer _ science center , which include flat - field corrections , dark subtraction , linearity and flux calibrations @xcite . the irac images ( in all four bands ) were mosaiced from the bcd images after pointing refinement , distortion correction and cosmic - ray removal with the final pixel scale of @xmath16 as described by @xcite and @xcite ; likewise the mips @xmath4 images were mosaiced in the similar way with the final pixel scale of @xmath17 @xcite . sources detected by sextractor @xcite in irac four bands and mips @xmath4 were matched with the two micron all sky survey ( 2mass ) sources to achieve astrometric uncertainties of around @xmath18 . the sdss data provide full coverage of the swire fields of lockman and elais - n2 but cover only one third of elais - n1 field . the @xmath19 corrected frames of spectroscopically observed galaxies were taken from the sdss - dr4 . the pixel scale of sdss images is @xmath20 @xcite . the sdss - dr4 @xmath19 spectrophotometric catalogue was cross - correlated with swire mir catalogue measured by sextractor @xcite by a radius of @xmath21 . the total survey area of the three northern swire fields is @xmath2224 deg@xmath23 , of which the overlap with sdss is @xmath2215 deg@xmath23 . to obtain the reliable morphological classification @xcite , 163 bright galaxies with petrosian magnitude @xmath24 were selected . only four sdss galaxies were not matched with swire mir sources by 2@xmath25 , since the sdss fiber observations mistakenly pointed to the off - nucleus regions rather than the nuclear regions of galaxies . this provides a preliminary sample of 159 galaxies . we excluded further five galaxies in our magnitude limited sample of 159 galaxies , because they failed in either the sky - background subtraction or the bulge - disk decomposition , or were severely contaminated by nearby bright stars . this led to a sdss @xmath1band flux - limited final sample of 154 galaxies . 142 of this sample have been imaged by irac four bands and 137 have been imaged by mips 24@xmath26 m band . finally , a sub - sample of 125 galaxies has images in all five mir bands , and is used for further statistical discussion in [ subsec : statistics ] . all of theses objects are local , with redshift less than 0.13 . in our sample , six galaxies were with the absolute b magnitude fainter than -18 , and thus classified as dwarf galaxies @xcite . here , the b magnitude can be obtained from the sdss @xmath0 and @xmath1 magnitudes @xcite . the distributions of sdss @xmath1band petrosian magnitudes , the redshift , and b - band absolute magnitudes for the 154 sample galaxies as well as those for the 125 sub - sample galaxies are plotted in figure [ fig : properties ] . all these distributions show that the sub - sample can well represent the flux - limited sample . among the 154 sample galaxies , 133 with emission line detections could be classified with the traditional @xmath27(/h@xmath28)-@xmath27(/h@xmath9 ) diagnostic diagram @xcite . the emission line fluxes were derived from the catalogue of @xcite . the criteria given by @xcite was adopted to distinguish the potential star - forming galaxies from agns , as is shown in figure [ fig : bpt ] . to obtain the accurate photometry , sky background fitting and subtraction were done @xcite on both the sdss corrected frames and the _ spitzer _ images . all objects detected by sextractor were masked to generate a background - only image , and the fitting sky - background was then subtracted . photometry was performed on the background - subtracted images by iraf task ellipse @xcite . to embrace almost all the flux of these extended sources in the different bands , an elliptical isophote with the b - band surface brightness of 26 mag @xmath29 was adopted as the photometric aperture , based on the sdss @xmath0band images . with such elliptical apertures , the total fluxes were measured in all the wavelengths including the sdss @xmath19 , the irac four bands and the mips @xmath4 band ( see sample apertures marked in figure [ fig : sample ] ) with iraf task polyphot . note that the point source functions ( psfs ) of mips @xmath4 are rather extended , therefore further aperture corrections were performed on this band . for objects with the equivalent radius of the elliptical apertures smaller than @xmath30 , aperture corrections were applied to calibrate the integrated flux to an equivalent radius of @xmath30 . the photometric accuracies of these different bands are quite small , less than 0.03 mag on average . flux calibration accuracies of the irac four bands @xcite and mips @xmath31 band @xcite are less than @xmath32 . the final errors include both the above errors . the galactic extinction in each sdss filter from sdss - dr4 catalogue was adopted , and then intrinsic extinction was derived from the balmer decrement @xcite . the photometric @xmath33-correction was calculated using the method of ( * ? ? ? * kcorrect v4 - 1 - 4 ) . no extinction correction has been performed on photometric results in the mir bands since extinction effect is rather negligible in the infrared compared with optical wavelength . due to the fact that our sample are all low redshift galaxies and , as of this work , there are no reliable @xmath33-correction for these mir spectral ranges available yet , we applied no @xmath33-correction to the mir photometry . all the measurements were converted to ab magnitudes @xcite . although pah and vsg emissions dominate @xmath10 and @xmath4 bands for the majority of our sample , there is still a stellar continuum in these bands , especially for the early - type galaxies . herewith a subtraction of the stellar contribution using the @xmath5 luminosity was adopted , with a scale factor of 0.232 for the @xmath3 band and 0.032 for the @xmath4 band @xcite . hereafter , we denoted the 8@xmath34(dust ) and 24@xmath34(dust ) representing the dust emissions after subtracting the stellar contribution @xcite . we conducted the morphological classification by two methods : visual inspection and bulge - disk decomposition with gim2d ( galaxy image 2d : * ? ? ? * ; * ? ? ? * ) . gim2d is a two - dimensional photometric decomposition fitting algorithm which fits each image to a superposition of an bulge component with a srsic profile , and a disk component with an exponential profile @xcite . gim2d was employed to obtain the structural parameters of galaxies in our sample . the bulge component of the model is a profile of srsic form @xcite : @xmath35\ } \label{eqn : sersic.profile}\ ] ] where @xmath36 is the surface brightness at a radius @xmath37 and @xmath38 is the characteristic value ( i.e. the effective surface brightness ) , defined as the brightness at the effective radius @xmath39 . parameter @xmath40 is related to the srsic index @xmath41 and chosen equal to @xmath42 so that @xmath39 remains the projected radius enclosing half of the light in this component @xcite . the disk component is an exponential profile of the form : @xmath43 where @xmath44 is the central surface brightness , and @xmath45 is the disk scale length . decomposition was performed based on this model , with a gaussian psf . a total of twelve parameters were adjusted in fitting the galaxy image and retrieved as output from our decomposition : the total luminosity @xmath46 , the bulge fraction @xmath2 , the bulge effective radius @xmath39 , the bulge ellipticity @xmath47 , the bulge position angle @xmath48 , the disk scale length @xmath45 , the disk inclination angle @xmath49 , the disk position angle @xmath50 , the centroiding offsets @xmath51 and @xmath52 , the s@xmath53rsic index @xmath41 , and the residual sky background level @xmath54 . the @xmath2 which is defined as the fraction of the total flux in the bulge component has been extracted as a quantitative indicator of morphology . @xmath55 corresponds to a pure bulge , while @xmath56 to a pure disk . with all the objects detected by sextractor flagged except the galaxy of interest , the @xmath0band mask images were adopted not only in @xmath0band but also in @xmath1band , throughout the decomposition fitting with gim2d . figure [ fig : sample ] shows example ( science , mask , model , and residual ) images of different morphological types in gim2d fitting . the returned @xmath57 values of @xmath0 and @xmath1band fitting have the mean values of 1.14 and 1.18 with deviations of 0.26 and 0.33 respectively , representing rather convincing fitting results . to check the results obtained , we compared the parameters @xmath2 of the 154 galaxies estimated from @xmath0 and @xmath1band in figure [ fig : gim2d ] . the @xmath2 values obtained from both bands agree well with small amount of deviation . among the three most deviated sources , sdss j161222.61 + 525827.9 is an early - type galaxy with highly centralized surface brightness distribution in bluer band . sdss j151723.30 + 593517.0 is a peculiar galaxy and ugc5888 is an irregular . we adopted @xmath2 values derived from @xmath1band images throughout the following investigation since the decomposition results in the two sdss bands hold quite good agreement . the morphological types of revised hubble sequence @xcite of our sample galaxies were classified by visual inspection based on features like bulge ratios , the presence of spiral arms and/or bars , signs of interaction , multiple nuclei etc . all galaxies in our sample were classified into six morphological classes : @xmath58(e or s0 ) , 1(sa ) , 3(sb ) , 5(sc ) , 7(sd ) , and 9(irr ) . notice that we assigned an additional class 10 corresponding to galaxies with peculiar morphology possibly related to galactic interactions , mergers , etc . we performed the visual classification in both sdss @xmath0 and @xmath1band images . the classifications done independently by the four of us , agree in over 90% of the sample . the classifications were verified for 36 of those galaxies whose morphological types were found in the nasa / ipac extragalactic database ( ned ) and were found to be accurate to @xmath59 . considering the possible effects that inclinations and bar structures may cause , we further divided sample galaxies into 3 types : barred galaxies , edge - on galaxies , and the rest defined as general galaxies for further consideration . note that when defining edge - on galaxies , we adopted a standard of gim2d fitted disk inclination angle @xmath60 . table [ tab : mor.class ] shows the numbers and corresponding fractions of different morphological types in our sample . in table [ tab : mor.spitzer ] , we present the numbers of galaxies observed by different mir bands in each morphological type . it can be drawn from table 2 that the morphological fractions e / s0 : s(sa - sd ) : irr of optical-@xmath10 and optical-@xmath4 samples are 0.47 : 0.51 : 0.014 and 0.44 : 0.54 : 0.016 respectively . both are consistant with e(e / s0-s0 ) : s(s0a - sdm ) : i m of 0.40 : 0.57 : 0.014 obtained from an optically selected sample of sdss galaxies @xcite . a comparison between hubble @xmath6 type and the bulge - to - total ratio @xmath2 has been carried out , as is shown in figure [ fig : t.bratio ] . except for the peculiar galaxies which exhibit a diversity of @xmath2 , there is a smooth inclination in @xmath2 along hubble sequence from @xmath61 to @xmath58 , i.e. , for normal galaxies , except the peculiar , the late - types exhibit lower @xmath2 than the early - type ones . hence @xmath2 does act as a reliable measure of morphological types for normal galaxies in our sample . in order to statistically examine the properties of our sample , galaxies have been divided into two morphological types : the early - type ( e / s0 ) with t=0 , and the late - type ( sa , sb , sc , sd , and irr ) with t from 1 to 9 . consequently , according to @xcite , such a classification roughly corresponds to the division of @xmath62 . 128 out of the 144 normal sample objects coincide with their morphological types classified with @xmath6 . the divisions are shown in figure [ fig : t.bratio ] . since as a whole , divisions with the two methods agree with each other , we have adopted t type to divide the sample galaxies into either the early - type or the late - type in the following statistics . the optical - mir color - color diagrams are shown in the left panels of figure [ fig : color ] , and there are anti - correlations between optical and mir colors , which is consistent with the result of @xcite . such a trend can be explained rather naturally : the optically blue color is related to the recent star formation , indicating the existence of notable amount of dust , and the mir dust emissions can be shown in both @xmath10 and @xmath4 bands . on the other hand , optically red galaxies are always too old to contain plenty of dust , and hence present weak mir dust emissions . the right panels of figure [ fig : color ] show the relationship between mir colors . it can be detected that [ 3.6]-[4.5 ] colors in our sample are quite blue , with an average of around -0.52 , indicating that there is no extremely active galactic nuclei ( qso etc . ) in our sample , because both the emissions of @xmath5 and @xmath63 of normal galaxies are dominated by decreasing stellar continuum of the old stellar population . yet these two bands of very active galaxies like quasars are dominated by the power law spectra of quasars and consequently should exhibit redder [ 3.6]-[4.5 ] colors . both colors of [ 3.6]-[8 ] and [ 3.6]-[24 ] can roughly characterize the relative strengths of the mir dust emissions of pahs and vsgs . the stronger the dust emissions , the redder the colors . therefore , it is not surprised to find that most of the peculiar galaxies of our sample at the redder part of these panels because they contain large amount of dust for their violent star formation @xcite . the luminosity of @xmath5 band is often treated as a tracer of stellar component ( * ? ? ? * ; * ? ? ? * etc ) as well as a test of validity of mass determination @xcite . furthermore @xcite has compared the mass of clumps in arp 82 derived from _ r _ band fluxes and broadband colors against luminosities of @xmath5 , and has found strong correlation between them . hereby the relationship between the stellar mass and the @xmath5 luminosity of our sample galaxies is examined . based on the optical photometries as described in [ subsec : photometry ] , we calculated the stellar mass of our sample , following @xcite : @xmath64 \label{eqn : mass.bell}\ ] ] where @xmath65 is the @xmath1band absolute magnitude , @xmath66 is the rest - frame color in the ab magnitude system . the coefficients @xmath67 and @xmath68 come from table 7 of @xcite . a @xcite stellar mass initial function ( imf ) has been adopted with @xmath69 and @xmath70 . the distribution of the stellar mass for our sample galaxies is presented in figure [ fig : properties ] , in a range between @xmath71 and @xmath72 , with the average mass around @xmath73 , as intermediate mass galaxies . a tight correlation of the stellar mass against the luminosity of @xmath5 is detected for our sample , as is shown in figure [ fig : i1.mass ] . our result is consistent with that found by @xcite but with smaller scatters , thus it confirms the capability of the @xmath5 luminosity as a measure of the stellar mass of galaxies . based on our 145 galaxies and 24 clumps in arp 82 @xcite , we fit the relation between the stellar mass and the @xmath5 luminosity , and obtain a nearly linear correlation : @xmath74}{l_{\odot } } ) \label{eqn : i1.mass}\ ] ] as is pointed out by @xcite and @xcite , the mass - to - infrared light ratio is relatively insensitive to the star formation history , and remains very close to unity , independent of either galaxy colors or hubble types . this relation is probably due to the fact that in the near - infrared , older stellar populations may dominate both the galaxy luminosities and the stellar masses . therefore such a correlation provides a proxy way to estimate the stellar mass of galaxies directly from the integrated @xmath5 luminosity . figure [ fig : mor.lum ] shows the @xmath10 and @xmath4 dust luminosities as the function of different morphological types in our sample . for normal galaxies , except the dwarfs , along either the hubble @xmath6 types or the @xmath2 ratios , there exist obvious declinations of the mir luminosities from the late - type to the early - type galaxies , especially showing a steep change around the division of the late - type and the early - type galaxies . all the peculiar galaxies show relatively higher mir luminosities , independent of their @xmath2 ratios . the phenomenon could be attributed to the fact that early - type galaxies are dominated by older population and are deficient of dust , resulting in lower mir dust luminosities , while the late - type contain larger amount of young stars and more dust thus present stronger mir emissions . peculiar galaxies which are undergoing strong star forming activities contain great amount of dust and thereby show averagely high mir luminosities . as @xcite has pointed out , both the @xmath10 and @xmath4 dust luminosities can be used as measures of sfrs of entire galaxies ; therefore , the correlations between the mir dust luminosities and morphological types reflect a consequent relationship between the galactic sfrs and morphological types . this also confirms the previous results of @xcite , @xcite , etc . as for the six dwarf galaxies , because they all have low mass of around @xmath75 ( from the previous mass determination ) , so they contain less dust and thus show lower mir dust emissions @xcite . the mir dust - to - star ratios are also plotted against different morphological types , in figure [ fig : mor.ratio ] . the prominent correlations are also detected between the mir dust - to - star ratios and both the hubble @xmath6 types and the @xmath2 ratios . furthermore , such correlations seem to be more obvious than those between the mir luminosities and morphological types . since both the @xmath10 and @xmath4 dust luminosities possess correlations with sfrs for normal galaxies , and the @xmath5 luminosity is a reliable tracer of stellar component , such ratios can be treated as the dust - to - star ratios . the correlations between the mir dust - to - star ratios and the morphological types could represent the distribution of sfrs per unit stellar mass @xcite over different morphologies . contrary to the behavior in figure [ fig : mor.lum ] , the dwarf galaxies are roughly consistent with the other late - type galaxies within the error bars , but still present a little lower dust - to - star ratios . this could be explained with the fact that the gravitation potentials of these low mass galaxies may not be strong enough to retain as much dust and gas against the radiation fields as those of the normal - mass galaxies , and hereby all the dwarf galaxies show slightly lower mir dust - to - star ratios . almost all the peculiar galaxies present higher mir dust - to - star ratios . the ratio of the @xmath10 dust luminosity to the @xmath4 dust luminosity is compared with different morphological types in figure [ fig : mor.dust ] . considering the @xmath10 dust emissions mainly represent emission of pahs heated by b type stars while @xmath4 dust emissions stand for emissions from hot dust mostly heated by o type stars @xcite , the ratio can be treated as the estimation of ratio between these two components . in general , @xmath10(dust)-to-@xmath4(dust ) ratios remain constant on average along the hubble sequence , while the larger scatter in distribution of the early - type probably arises from existence of nuclear agns which destroy pah emissions presumably due to photodestruction of the pah molecules by euv / x - ray photons @xcite or the outer diffuse pah emissions heated by the older stars @xcite . this can also be seen in later discussion in figure [ fig : sf.agn ] where agns present lower @xmath10(dust ) luminosities . it should be noted that the two dwarf irregular galaxies exhibit lower @xmath3(dust)-to-@xmath4(dust ) ratios than the most of the late - type do , possibly due to their low metallicities and @xmath76 respectively , about @xmath77 and @xmath78 the solar value @xcite . ] @xcite . the above result indicates that for the normal galaxies except the dwarfs , the ratio of these two dust components does not vary much against morphology . therefore the @xmath10(dust ) luminosities are as capable to trace the galaxy sfrs as the @xmath4(dust ) luminosities as @xcite has pointed out . in order to compare the statistical mir properties of different types of sample galaxies , we performed all the following statistics on the sub - sample of 125 galaxies which have photometric information for all the optical and mir bands . since from figure [ fig : properties ] and k - s test results this sub - sample does not exhibit notable differences from the 154-galaxy sample , we suggest that the following statistical discussions are representative of all the sample galaxies . distributions of the mir luminosities and dust - to - star ratios for both the early - type and the late - type galaxies in the sub - sample are presented in figure [ fig : early.late ] . it is clear that , in general , the late - type galaxies exhibit quite different mir properties to early - type ones , presenting a distinct and statistically higher mir luminosities and dust - to - star ratios . the gaussian fitting is performed on each distribution , and the lines crossing intersection points of the two gaussian distributions are presented as the division of the two morphological types . in part a of table [ tab : type ] , the median values and the mean values together with scatters of distributions of the early - type and the late - type galaxies are listed . probabilities that the distributions of these two types can match are all smaller than @xmath79 , indicating that they present quite distinct properties . therefore , both the mir luminosities and dust - to - star ratios can be used to separate the early - type galaxies from the late - type ones . table [ tab : type.division ] displays specific values of divisions and the reliability of such classifications . we define the reliability of classification as the fraction of galaxies from the subsample that are selected by hubble @xmath6 types . for example , out of the 117 normal galaxies which have images in all irac bands , the t type criterion selects 64 late - type galaxies and 53 early - types . 47 of the 64 late - type galaxies have @xmath80 and thus are consistently classified as late - type , while 47 of the 53 early - types have @xmath81 and thus are classified as early - type . therefore the @xmath82 maintains reliability of 73% for selecting late - type galaxies and 89% for early - types . correspondingly , @xmath83 gives a reliability of 70% for the late - type and 77% for the early - type ; @xmath84 can give a 88% for the late - type and 83% for the early - type ; and @xmath85 can give a 84% for the late - type and 85% for the early - type ; hereby the mir dust luminosities especially the mir dust - to - star ratios can be effective tools to divide the early - type galaxies from the late - type ones . the comparisons between mir properties of star - forming galaxies and agns ( see [ subsec : sample ] ) are shown in figure [ fig : sf.agn ] . generally , star - forming galaxies present stronger mir emissions than those possess agn activities . from part b of table [ tab : type ] , the star - forming galaxies and agns show the probability of matching each other in @xmath10 and @xmath4 dust luminosites and dust - to - star ratios with less than @xmath86 , indicating quite different mir properties , although not so distinct as these between the early - type and late - type ones . some of the sample galaxies are edge - on galaxies and some are barred galaxies . will the galaxies in edge - on view or with bars present different mir properties ? we compare the distributions of the mir dust luminosities and the mir dust - to - star ratios between edge - on galaxies , barred galaxies and normal galaxies in figure [ fig : edge.on ] and figure [ fig : bar ] . the statistical results are listed in part c and d of table [ tab : type ] , with the probabilities in matching each by few to tenth percent , indicating rather resembling distributions . thus , neither galaxies in edge - on view nor galaxies with bars present statistical differences from the other normal galaxies in both mir properties . furthermore , although based on limited data points , one can still find out in figure [ fig : edge.on ] that the edge - on galaxies can also be classified into early - type and late - type ones with the division criteria described in table [ tab : type.division ] . therefore , the inclination of galaxies and the existence of bars do not affect our previous results . we have also checked the distributions of total sample of 154 galaxies in the above parameters and type comparisons , and yielded quite similar results , therefore the selection of this sub - sample does not affect the reliability of our statistical results . we investigated the correlations between the morphological types and the mir properties of a local optically flux - limited sample of galaxies selected from the spectroscopic catalogue of galaxies in sdss - dr4 , cross - correlated with the lockman hole , elais - n1 and elais - n2 of _ spitzer _ swire survey . aperture photometry has been performed on all these galaxies in all optical and mir bands . morphological classifications have been performed by both visual inspection and the bulge - disk decomposition with gim2d . our major results are as follows : \(1 ) the presented analysis clearly shows that the bulge - to - total ratio @xmath2 obtained by the bulge - disk decomposition is proved a qualified quantitative measure of the hubble @xmath6 types . galaxies with earlier morphological types possess larger bulge ratios while later type ones have more dominant disk structures . \(2 ) the @xmath5 luminosity presents a tight correlation with the stellar mass , and this provides us a new tool to estimate the stellar mass . the empirical formula to calculate the stellar mass by the @xmath5 luminosity is given in equation [ eqn : i1.mass ] . \(3 ) except for the dwarf galaxies and a few peculiar objects , the mir dust luminosities of @xmath10 and @xmath4 exhibit correlations with either hubble @xmath6 type or the bulge - to - total ratio @xmath2 . such correlations are much more obvious if we used the mir dust - to - star ratios ( either @xmath87/\nu l_{\nu}[3.6\mu m]$ ] or @xmath88/\nu l_{\nu}[3.6\mu m]$ ] ) instead of the mir luminosities . \(4 ) the mir dust luminosity ratios of @xmath89/\nu l_{\nu}[24\mu m(dust)]$ ] turn to be roughly constant against the morphological types , especially for the late - type galaxies . therefore , on average , the @xmath10(dust ) luminosity can as reliably measure the global sfrs of normal galaxies as the @xmath31(dust ) luminosity can , regardless of the morphological types . \(5 ) distributions of the mir dust luminosities and the mir dust - to - star ratios of both the early - type and the late - type galaxies are very different . the late - type galaxies present higher mir dust luminosities and mir dust - to - star ratios than the early - type galaxies . the mir dust luminosities of @xmath10 and @xmath4 and especially the mir dust - to - star ratios of @xmath90/\nu l_{\nu}[3.6\mu m]$ ] and @xmath91/\nu l_{\nu}[3.6\mu m]$ ] can provide an effective tool to distinguish the late - type galaxies from the early - types . \(6 ) the star - forming galaxies and agns also present different statistical mir properties , with the former showing higher mir luminosities and mir dust - to - star ratios . the statistical results show that either galaxies in edge - on view or galaxies with bars do not present quite different mir properties from other sample galaxies . the authors would like to appreciate the anonymous referee for helpful comments and suggestions , and we are grateful for the help of d.b . sanders , s. mao , z .- zhou , x .- y . xia , z .- g . deng , z. wang , j .- s . huang , c .- liu and j .- l . this project was supported by the national science foundation of china through grants 10273012 , 10333060 and 10473013 . funding for the sdss and sdss - ii has been provided by the alfred p. sloan foundation , the participating institutions , the national science foundation , the u.s . department of energy , the national aeronautics and space administration , the japanese monbukagakusho , the max planck society , and the higher education funding council for england . the sdss is managed by the astrophysical research consortium for the participating institutions . the participating institutions are the american museum of natural history , astrophysical institute potsdam , university of basel , cambridge university , case western reserve university , university of chicago , drexel university , fermilab , the institute for advanced study , the japan participation group , johns hopkins university , the joint institute for nuclear astrophysics , the kavli institute for particle astrophysics and cosmology , the korean scientist group , the chinese academy of sciences ( lamost ) , los alamos national laboratory , the max - 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we explore the correlation between morphological types and mid - infrared ( mir ) properties of an optically flux - limited sample of 154 galaxies from the forth data release ( dr4 ) of sloan digital sky survey ( sdss ) , cross - correlated with _ spitzer _ swire ( _ spitzer _ wide - area infrared extragalactic survey ) fields of elais - n1 , elais - n2 and lockman hole . aperture photometry is performed on the sdss and _ spitzer _ images to obtain optical and mir properties . the morphological classifications are given based on both visual inspection and bulge - disk decomposition on sdss @xmath0 and @xmath1band images . the average bulge - to - total ratio ( @xmath2 ) is a smooth function over different morphological types . both the @xmath3(dust ) and @xmath4(dust ) luminosities and their relative luminosity ratios to @xmath5 ( mir dust - to - star ratios ) present obvious correlations with both the hubble @xmath6 type and @xmath2 . the early - type galaxies notably differ from the late - types in the mir properties , especially in the mir dust - to - star ratios . it is suggested that the mir dust - to - star ratio of either @xmath7/\nu l_{\nu}[3.6\mu m]$ ] or @xmath8/\nu l_{\nu}[3.6\mu m]$ ] is an effective way to separate the early - type galaxies from the late - type ones . based on the tight correlation between the stellar mass and the @xmath5 luminosity , we have derived a formula to calculate the stellar mass from the latter . we have also investigated the mir properties of both edge - on galaxies and barred galaxies in our sample . since they present similar mir properties to the other sample galaxies , they do not influence the mir properties obtained for the entire sample .

. (a) Arbitration.-- (1) In general.--The Secretary shall establish within the Forest Service an arbitration program as an alternative dispute resolution process in lieu of judicial review for the projects described in subsection (b). (2) Notification to objectors.--On issuance of an appeal response to an objection filed with respect to an ecosystem restoration project subject to an objection at the project level under part 218 of title 36, Code of Federal Regulations (as in effect on the date of enactment of this Act), the Secretary shall notify each applicable individual or entity that submitted the objection (referred to in this section as the ``objector'') that any further appeal may be subject to arbitration in accordance with this section. (b) Description of Projects.--The Secretary, at the sole discretion of the Secretary, may designate the following types of ecosystem restoration projects for arbitration: (1) Projects developed through a collaborative process (within the meaning of section 603(b)(1)(C) of the Healthy Forest Restoration Act of 2003 (16 U.S.C. 6591b(b)(1)(C))). (2) Projects identified in a community wildfire protection plan. (3) For each applicable calendar year, not more than 2 other types of ecosystem restoration projects for each region of the Forest Service. (c) Arbitrators.-- (1) Appointment.--The Secretary shall develop and publish a list of not fewer than 20 individuals eligible to serve as arbitrators for the program under this section. (2) Qualifications.--In order to be eligible to serve as an arbitrator under this subsection, an individual shall be currently certified by the American Arbitration Association. (d) Initiation of Arbitration.-- (1) In general.--Not later than 7 days after the date of receipt of a notice of intent to file suit challenging an ecosystem restoration project, the Secretary shall notify each applicable objector and the court of jurisdiction that the project has been designated for arbitration in accordance with this section. (2) Demand for arbitration.-- (A) In general.--An objector that sought judicial review of an ecosystem restoration project that has been designated by the Secretary for arbitration under this section may file a demand for arbitration in accordance with-- (i) sections 571 through 584 of title 5, United States Code; and (ii) this paragraph. (B) Requirements.--A demand for arbitration under subparagraph (A) shall-- (i) be filed not later than the date that is 30 days after the date of the notification by the Secretary under paragraph (1); and (ii) include an alternative proposal to the applicable ecosystem restoration project that describes each modification sought by the objector with respect to the ecosystem restoration project. (e) Selection of Arbitrator.--For each arbitration commenced under this section, the Secretary and each applicable objector shall agree on a mutually acceptable arbitrator from the list published under subsection (c)(1). (f) Responsibilities of Arbitrator.-- (1) In general.--An arbitrator selected under subsection (e)-- (A) shall address each demand filed for arbitration with respect to an ecosystem restoration project under this section; but (B) may consolidate into a single arbitration all demands for arbitration by all objectors with respect to an ecosystem restoration project. (2) Selection of proposals.--An arbitrator shall make a decision regarding each applicable demand for arbitration under this section by selecting-- (A) the ecosystem restoration project, as approved by the Secretary; or (B) an alternative proposal submitted by the applicable objector. (3) Limitations.-- (A) Administrative record.--A decision of an arbitrator under this subsection shall be based solely on the administrative record for the ecosystem restoration project. (B) No modifications to proposals.--An arbitrator may not modify any proposal contained in a demand for arbitration of an objector under this section. (g) Deadline for Completion of Arbitration.--Not later than 90 days after the date on which a demand for arbitration is filed under subsection (d)(2), the arbitration process shall be completed. (h) Effect of Arbitration Decision.--A decision of an arbitrator under this section-- (1) shall not be considered to be a major Federal action; (2) shall be binding; and (3) shall not be subject to judicial review, except as provided in section 10(a) of title 9, United States Code. SEC. 107. BONDING REQUIREMENTS FOR JUDICIAL REVIEW. (a) Bond Requirement.-- (1) In general.--The judicial review of an action challenging an ecosystem restoration project under this title (referred to in this section as an ``action'') shall be subject to the bonding requirements of this section. (2) Bond or security.-- (A) In general.--As soon as practicable after the date on which a complaint or appeal is filed to initiate an action, each plaintiff shall post a bond or other security acceptable to the court in an amount equal to the anticipated costs, expenses, and attorney fees of the Secretary as a defendant in the action, in accordance with a reasonable estimate of the Secretary. (B) Requirement.--All proceedings in an action shall be stayed until the bond or security required under subparagraph (A) is posted. (b) Recovery of Litigation Costs, Expenses, and Attorney Fees.-- (1) Motion for payment.--If the Secretary prevails in an action, the Secretary shall submit to the court a motion for payment from the bond or other security posted under subsection (a), of the reasonable costs, expenses, and attorney fees incurred by the Secretary as a defendant in the action. (2) Maximum recovery.--The total amount of costs, expenses, and attorney fees recovered by the Secretary under paragraph (1) may not exceed the amount of the bond or other security posted in the action. (3) Return remainder.--Any funds remaining from the bond or other security posed under subsection (a) after the payment of costs, expenses, and attorney fees under paragraph (1) shall be returned to the plaintiff that posted the bond or security in the action. (c) Return of Bond to Prevailing Plaintiff.--If the applicable court rules, in a final enforcement judgment, in favor of a plaintiff on all causes of each action of the plaintiff, the court shall return to the plaintiff any bond or security posted by the plaintiff under subsection (a), plus any interest accruing during the period beginning on the date on which the bond or security was posted. (d) Effect of Settlement.-- (1) In general.--If an action in which a bond or security was posted is resolved by settlement between the Secretary and the plaintiff, the settlement agreement may provide for sharing of the costs, expenses, and attorney fees incurred by the parties to the action. (2) Deferral.--A settlement agreement under paragraph (1) may defer the resolution of costs, expenses, and attorney fees to-- (A) further negotiation; or (B) decision by the court. SEC. 108. PERFORMANCE MEASURES; ANNUAL REPORTS. (a) Performance Measures.--The Secretary shall annually evaluate the degree to which the Secretary is achieving-- (1) the purposes of this title, including-- (A) the number of acres covered by ecosystem restoration projects; (B) the number of acres treated by mechanical methods under ecosystem restoration projects; (C) the number of acres treated using stewardship contracts and stewardship agreements under ecosystem restoration projects; (D) the number of acres treated using timber sales under ecosystem restoration projects; (E) the number of acres treated by prescribed fire, mowing, and other noncommercial product producing activities under ecosystem restoration projects; and (F) to the extent practicable, a summary of acres receiving more than 1 type of treatment; and (2) the acreage requirements established under section 104(a). (b) Annual Reports.--Not later than 1 year after the date of enactment of this Act, and annually thereafter, the Secretary shall submit to the Committee on Energy and Natural Resources of the Senate and the Committee on Natural Resources of the House of Representatives-- (1) a report that describes, with respect to the preceding year, the results of evaluations using the performance measures described in subsection (a); and (2) a report that describes, with respect to the preceding year-- (A) the number and substance of ecosystem restoration projects that are subject to arbitration under section 106; and (B) the outcomes of the arbitrations under that section. TITLE II--CATEGORICAL EXCLUSIONS SEC. 201. DEFINITIONS. In this title: (1) Catastrophic event.--The term ``catastrophic event'' means any natural disaster (such as hurricane, tornado, windstorm, snow or ice storm, rain storm, high water, wind- driven water, tidal wave, earthquake, volcanic eruption, landslide, mudslide, drought, or insect or disease outbreak), or any fire, flood, or explosion, regardless of cause. (2) Categorical exclusion.--The term ``categorical exclusion'' means an exception to the requirements of the National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.) for a project or activity relating to the management of National Forest System land. (3) Collaborative process.--The term ``collaborative process'' means a process relating to the management of National Forest System land by which a project or activity is developed and implemented by the Secretary through collaboration with interested persons, as described in section 603(b)(1)(C) of the Healthy Forests Restoration Act of 2003 (16 U.S.C. 6591b(b)(1)(C)). (4) Forest management activity.--The term ``forest management activity'' means a project or activity carried out by the Secretary on National Forest System land, consistent with the forest plan covering that land. (5) Forest plan.--The term ``forest plan'' means a land and resource management plan prepared by the Forest Service for a unit of the National Forest System pursuant to section 6 of the Forest and Rangeland Renewable Resources Planning Act of 1974 (16 U.S.C. 1604). (6) Salvage operation.--The term ``salvage operation'' means a forest management activity carried out in response to a catastrophic event, the primary purpose of which is-- (A) to prevent wildfire as a result of the catastrophic event, or, if the catastrophic event was wildfire, to prevent a reburn of the fire-impacted area; (B) to provide an opportunity for use of forest materials damaged as a result of the catastrophic event; or (C) to provide a funding source for reforestation and other restoration activities for the National Forest System land impacted by the catastrophic event. (7) Secretary.--The term ``Secretary'' means the Secretary of Agriculture (acting through the Chief of the Forest Service). SEC. 202. CATEGORICAL EXCLUSION TO EXPEDITE CERTAIN CRITICAL RESPONSE ACTIONS. (a) Availability of Categorical Exclusion.--A categorical exclusion is available to the Secretary to develop and carry out a forest management activity on National Forest System land in any case in which the primary purpose of the forest management activity is-- (1) to address an insect or disease infestation; (2) to treat land at risk of insect or disease infestation; (3) to reduce hazardous fuel loads; (4) to protect a municipal water source; (5) to maintain, enhance, or modify critical habitat to protect the habitat from catastrophic disturbances; (6) to increase water yield; or (7) any combination of the purposes specified in paragraphs (1) through (6). (b) Acreage Limitations.-- (1) In general.--Except in the case of a forest management activity described in paragraph (2), a forest management activity covered by the categorical exclusion granted by subsection (a) may not contain harvest units exceeding a total of 5,000 acres. (2) Larger areas authorized.--A forest management activity covered by the categorical exclusion granted by subsection (a) may not contain harvest units exceeding a total of 15,000 acres if the forest management activity is-- (A) developed through a collaborative process; (B) proposed by a resource advisory committee (as defined in section 201 of the Secure Rural Schools and Community Self-Determination Act of 2000 (16 U.S.C. 7121)); or (C) covered by a community wildfire protection plan. SEC. 203. CATEGORICAL EXCLUSION TO EXPEDITE SALVAGE OPERATIONS IN RESPONSE TO CATASTROPHIC EVENTS. (a) Availability of Categorical Exclusion.--A categorical exclusion is available to the Secretary to develop and carry out a salvage operation as part of the restoration of National Forest System land following a catastrophic event. (b) Acreage Limitations.--A salvage operation covered by the categorical exclusion granted by subsection (a) may not contain harvest units exceeding a total of 5,000 acres. (c) Additional Requirements.-- (1) Road construction.--A salvage operation covered by the categorical exclusion granted by subsection (a) may not include any permanent road construction. (2) Stream buffers.--A salvage operation covered by the categorical exclusion granted by subsection (a) shall comply with the standards and guidelines for stream buffers contained in the applicable forest plan, unless the standards and guidelines are modified for a specific salvage operation as part of a categorical exclusion by the Regional Forester. (3) Reforestation plan.--A reforestation plan shall be developed under section 3 of the Act of June 9, 1930 (commonly known as the ``Knutson-Vandenberg Act'') (16 U.S.C. 576b), as part of a salvage operation covered by the categorical exclusion granted by subsection (a). SEC. 204. CATEGORICAL EXCLUSION TO MEET FOREST PLAN GOALS FOR EARLY SUCCESSIONAL FORESTS. (a) Availability of Categorical Exclusion.--A categorical exclusion is available to the Secretary to develop and carry out a forest management activity on National Forest System land in any case in which the primary purpose of the forest management activity is to modify, improve, enhance, or create early successional forests for wildlife habitat improvement and other purposes, in accordance with the applicable forest plan. (b) Acreage Limitations.--A forest management activity covered by the categorical exclusion granted by subsection (a) may not contain harvest units exceeding a total of 5,000 acres. SEC. 205. ALTERNATIVE AGENCY CONSULTATION PROCEDURES. (a) Forest Management Activities.-- (1) In general.--Subject to paragraph (2), for each forest management activity covered by a categorical exclusion granted by this title, the Secretary shall satisfy the applicable interagency consultation obligations under section 7 of the Endangered Species Act of 1973 (16 U.S.C. 1536) by achieving compliance with the alternative consultation procedures established in subpart D of part 402 of title 50, Code of Federal Regulations (or successor regulations). (2) References.--For purposes of this subsection, all references contained in subpart D of part 402 of title 50, Code of Federal Regulations (or successor regulations)-- (A) to the term ``U.S. Environmental Protection Agency'' or ``EPA'' shall be considered to be a reference to the Secretary; and (B) to the term ``FIFRA action'' shall be considered to be a reference to a forest management activity covered by a categorical exclusion granted by this title. (b) Interim Timelines.--Until the date on which an alternative consultation agreement under subpart D of part 402 of title 50, Code of Federal Regulations (or successor regulations), is entered into with respect to a forest management activity under subsection (a)-- (1) any formal or informal interagency consultation regarding the forest management activity shall be completed by not later than the date that is 30 days after the date on which the Secretary submits a written request for consultation; and (2) a biological opinion or letter of concurrence, as appropriate, shall be issued by not later than the date that is 10 days after the date of completion of that consultation.

National Forest Ecosystem Improvement Act of 2015 This bill directs the Department of Agriculture (USDA), acting through the Forest Service, to identify, prioritize, and carry out ecosystem restoration projects on National Forest System land in accordance with applicable land and resource management plans, if any, to accomplish one or more of the following objectives: restore terrestrial habitat; sustain water quality, water flows, or watershed health and function; create, improve, or increase early seral habitat; carry out a needed timber stand improvement; reduce the risk or extent of insect or disease infestation; reduce wildland fire severity potential; implement a community wildfire protection plan; or establish, recover, or maintain ecosystem resiliency. USDA may not carry out an ecosystem restoration project on any area of System land in the National Wilderness Preservation System or on which removal of vegetation is prohibited by law. USDA must accomplish restoration treatments throughout the National Forest System on 1 million acres using certain mechanical treatment methods and on another 1 million acres using prescribed fire. USDA shall prepare an environmental assessment in accordance with the National Environmental Policy Act of 1969 (NEPA) for each ecosystem restoration project that accomplishes one or more objectives of this Act. USDA shall study, develop, and describe in each ecosystem restoration project both the proposed action and a no-action alternative. USDA shall establish within the Forest Service an arbitration program as an alternative dispute resolution process in lieu of judicial review for specified types of ecosystem restoration projects. The judicial review of an action challenging an ecosystem restoration project under this Act shall be subject to specified plaintiff bonding requirements. A categorical exclusion is made available to USDA for certain forest management activities in order to: (1) expedite specified critical response actions, (2) expedite salvage operations in response to catastrophic events, and (3) meet forest plan goals for early successional forests. (A &quot;categorical exclusion&quot; under NEPA is a category of actions which do not individually or cumulatively have a significant effect on the human environment and which have been found to have no such effect in procedures adopted by a federal agency in implementing environmental regulations and for which, therefore, neither an Environmental Assessment nor an Environmental Impact Statement is required.) For each forest management activity covered by a categorical exclusion granted by this title, USDA shall satisfy the interagency consultation obligations under the Endangered Species Act of 1973 by achieving compliance with certain alternative consultation procedures established by federal regulation.

spontaneous intracerebral hemorrhage ( ich ) accounts for ~15% of all strokes and induces a 30-day mortality rate of ~40% [ 15 ] . the rupture of small vessels damaged by chronic hypertension or amyloid angiopathy induces primary ich , creating a space - occupying hematoma within the brain parenchyma . hematoma volume directly correlates with neurological deterioration and patient mortality [ 2 , 69 ] and neurosurgical clot evacuation produces more favorable outcomes in subsets of ich patients ; however , many patients are not amenable to surgical intervention due to hematoma location or concurrent intraventricular hemorrhage . as such , conservative management remains a clinical mainstay , reinforcing the notion that ich is the least treatable form of strokes and stressing the need for novel therapeutic approaches . vascular injury and inflammatory activation are predictive markers of hematoma enlargement , development of vasogenic edema , and acute neurological deterioration [ 11 , 12 ] . apoptosis of cerebral endothelial cells increased blood - brain barrier ( bbb ) permeability , vasogenic edema , and neurological impairment after hemorrhagic stroke [ 13 , 14 ] . furthermore , activation of the proinflammatory transcription factor , nfb , correlated with apoptotic cell death within perihematomal blood vessels after ich thus , a reduction in neurovascular injury may improve outcomes after ich ; however , the underlying mechanisms remain poorly defined and contribute to the lack of medical treatment options after ich . hemolysis of extravasated erythrocytes triggers the release of proinflammatory mediators in and around the hematoma core . along these lines , inflammatory activation correlates with increased hematoma expansion , neurological deterioration , and a poor functional recovery after ich [ 12 , 1517 ] . notably , elevated plasma concentrations of the proinflammatory mediator , tumor necrosis factor- ( tnf- ) , clinically correlated with acute hematoma enlargement , edema development , and patient outcome following ich [ 1822 ] . similarly , tnf- expression was acutely increased within the perihematoma tissue using multiple species and models of experimental ich [ 2328 ] . coupled with our finding that neurovascular injury directly correlated with tnf- expression after ich in mice , tnf- may induce acute neurological injury after ich ; however , the mechanisms underlying tnf--induced neurovascular injury after ich remain poorly defined . recent evidence suggests that tnf- induces necroptosis , a novel form of cell death that exhibits features of apoptosis , necrosis , and type 2 autophagic death [ 2932 ] . although the role of necroptotic cell death after ich remains unexplored , we first reported that hemin , a hemoglobin oxidation byproduct that accumulates within intracranial hematomas , induced tnf- expression and promoted necroptotic cell death in cultured astrocytes . receptor interacting protein kinase 1 ( ripk1 ) is a multifunctional protein kinase that interacts with tnf- receptor ( tnfr ) to promote nfb and to activate necroptotic cell death [ 3537 ] . herein , we hypothesized that necrostatin-1 ( nec-1 ) , a novel and highly selective ripk1 inhibitor , improves neurological outcomes following ich . animal studies were reviewed and approved by the committee on animal use for research and education at georgia regents university ( protocol number 2008 - 0166 ) , in compliance with nih guidelines . male cd-1 mice ( 810 weeks old ; charles river , wilmington , ma , usa ) were anesthetized with a cocktail of 8 mg / kg xylazine and 60 mg / kg ketamine . throughout all surgical procedures , body temperature was maintained at 37c by using a small - animal temperature controller ( david kopf instruments , tujunga , ca , usa ) . mice were placed into a stereotactic frame and a 0.5 mm diameter burr hole was drilled over the parietal cortex , 2.2 mm lateral to the bregma . a 26-gauge hamilton syringe , loaded with 0.04 u of bacterial type iv collagenase in 0.5 l saline , was lowered 3 mm deep from the skull surface directly into the left striatum . the syringe was depressed at a rate of 450 nl / min and left in place for 10 minutes after the procedure to prevent solution reflux and excess diffusion . sham animals underwent the same surgical procedure , except that saline was stereotactically injected rather than collagenase . after the syringe was removed , bone wax was used to close the burr hole , the incision was surgically stapled , and mice were kept warm until recovery of the righting reflex . this entire procedure was detailed previously by our structural analog ( nec-1inactive ) ( tocris , ballwin , mo , usa ; see figure 1 ) , or saline ( placebo ) was administered via the intracerebroventricular ( icv ) route at the time of injury . this dose of nec-1 and route of administration were based on previous studies showing efficacy in preclinical models of stroke and traumatic brain injury [ 37 , 38 ] . hematoma volume was spectrophotometrically quantified by the quantichrom hemoglobin assay kit ( bioassay systems , hayward , ca , usa ) , as per the manufacturer 's recommendations and as routine to our laboratory . the amount of hemoglobin in each hemisphere was calculated using the following : [ ( optical density of sample / optical density of calibrator)100 ] . bbb permeability was quantified following administration of evans blue ( 20 mg / ml in pbs , i.v . ) blood ( 100 l ) was obtained by cardiac puncture and centrifuged , and then the plasma was diluted in n , n - dimethylformamide ( 1 : 1000 ) . following perfusion with saline , brains were weighed , solubilized in n , n - dimethylformamide , and then incubated at 78c for 18 h. absorbance was then determined in brain and blood samples at 620 nm using a synergy ht plate reader ( bio - tek , winooski , vt , usa ) . the concentration of evans blue ( g/l ) in each sample , a measure of bbb permeability , was calculated using a standard curve , and permeability was equal to [ ( evans blue concentration of brain / weight of brain)/(evans blue concentration of plasma / circulation time ) ] , as reported previously by our group [ 39 , 40 ] . brain water content , an established measure of cerebral edema , was quantified in 2 mm coronal tissue sections of the ipsilateral or corresponding contralateral striatum , as routine to our laboratory [ 3942 ] . the percentage of water content in each sample was calculated as follows : % brain water content = [ ( ( wet weightdry weight)/wet weight)100 ] . total rna was isolated ( sv rna isolation kit , promega , madison , wi , usa ) and qrt - pcr was performed on a cepheid smartcycler ii ( cepheid , sunnyvale , ca , usa ) using a superscript iii platinum sybr green one - step qrt - pcr kit ( invitrogen , carlsbad , ca , usa ) , as per our laboratory [ 34 , 39 , 4143 ] . product specificity was confirmed by melting curve analysis and visualization of a single , appropriately sized band on a 2% agarose gel . gene expression levels were quantified using a cdna standard curve and data was normalized to rps3 , a housekeeping gene that is unaffected by the experimental manipulations . brains were removed and postfixed in 4% paraformaldehyde overnight at 4c and then transferred into 30% sucrose . tissue sections ( 20 m ) were direct - mounted onto glass slides and stained using a primary antibody against glial fibrillary acidic protein ( gfap ; dako , 1 : 200 ) , as detailed by our laboratory [ 41 , 44 ] . after labeling with an alexa - fluor tagged secondary antibody , immunoreactivity propidium iodide ( pi , 150 ng ) was administered via tail vein five hours prior to sacrifice . the number of pi positive cells was quantified by cell counts in three specified regions within the perihematomal regions . neurological injury was determined using a modified 24-point scale , as detailed previously by our laboratory and others [ 39 , 40 , 45 , 46 ] . this scale comprised six behavioral tests , each of which was graded from 0 ( performs with no impairment ) to 4 ( severe impairment ) . a composite score was calculated as the sum of the grades on all six tests . one - way analysis of variance ( anova ) followed by student - newman - keuls or two - way anova followed by tukey 's post hoc test was used for multiple group comparisons . administration of nec-1 significantly reduced hematoma volume within the ipsilateral hemisphere at 72 h after ich ( figure 2 ) . specifically , hemoglobin content was increased within the injured hemisphere from 26.5 2.6 mg / dl in sham - operated mice to 80.8 9.9 mg / dl following ich ( p < 0.001 versus sham ) . intrastriatal delivery of nec-1 at the time of ich reduced hemispheric hemoglobin content to 37.3 8.1 mg / dl ( p < 0.001 versus ich , not significantly different from sham ) . administration of nec-1inactive also reduced hemoglobin content after ich ( 48.6 7.2 mg / dl ; p < 0.05 versus sham- , ich- , and nec-1-treated mice ) . the effect of nec-1 on hematoma volume was mirrored by brain lesion volume , as assessed by hematoxylin and eosin staining ( data not shown ) . consistent with this finding , nec-1 reduced the number of propidium iodide positive ( pi ) cells within the perihematomal tissue by 48% , as compared to ich only mice ( p < 0.01 ) ( figure 3 ) . in contrast , nec-1inactive reduced the number of pi cells by 6.3% ( not significantly different from placebo treated after ich ) . astrogliosis , a conserved response to brain injury [ 47 , 48 ] , was similarly reduced by nec-1 treatment . administration of nec-1 reduced gfap expression after ich , as assessed by western blotting and by immunohistochemistry , consistent with the attenuation of cellular injury ( figure 4 ) . coupled with our observation that nec-1 attenuated proinflammatory gene expression , including reduced tnf- expression ( mek and kmd , unpublished observations ) , these findings suggest that necroptosis contributes to glial reactivity after ich . cerebral edema is a major cause of patient deterioration after ich . over the first 24 h after ich , a significant increase in evans blue extravasation , a sensitive measure of blood - brain barrier disruption , this breach in the blood - brain barrier was maximal between 3 and 12 h after injury , with spontaneous resealing observed at 24 h. administration of nec-1 at the time of injury significantly reduced evans blue extravasation at all time points ( figure 5 ) . in contrast , nec-1inactive did not significantly reduce blood - brain barrier opening at any time point , as compared to placebo - treated mice , suggesting a specific effect of nec-1 . bbb opening contributes to the development of vasogenic edema ; thus , the effect of nec-1 on edema development was next assessed . as was observed with evans blue extravasation , nec-1 reduced brain water content at all time points up to 5 days after ich . the maximal effect of nec-1 was noted at 24 h after ich whereby brain water content was reduced from 80.3 0.2% in placebo - treated ich mice to 76.8 0.4% following nec-1 administration as was observed with bbb opening , nec-1inactive was without effect on brain edema development after ich ( 82.7 0.7% ; p < 0.05 versus nec-1 , not significantly different from placebo ) . no significant differences were observed between groups in the contralateral hemispheres . in line with a reduction in cell death and reduced edema development , necrostatin-1 improved neurological outcomes after ich . specifically , necrostatin-1 significantly improved the outcomes using a 24-point scale across the first 72 h after injury , as compared to either placebo- or nec-1inactive - treated mice after ich ( p < 0.001 versus placebo- , nec-1inactive - treated ich mice ) ( figure 7 ) . ich , the most common form of hemorrhagic stroke , is associated with the highest mortality and the worst long - term neurological outcomes of all stroke subtypes . one - year mortality rates are > 60% and of the ~67,000 americans suffering an ich annually , < 20% recover functional independence after six months [ 1 , 2 , 49 ] . notably , the incidence of ich is expected to double over the next several decades due to an aging population and to changes in racial demographics . these data emphasize the devastating nature of ich and indicate the need for improved treatment options . extravasation of erythrocytes creates a space - occupying hematoma within the brain parenchyma [ 69 , 5054 ] . hematoma growth continues over the ensuing hours due to rebleeding from the ruptured arteriole , bleeding in surrounding compressed vessels , and/or local clotting defects after vessel rupture [ 6 , 8 , 50 ] . the persistent or recurrent bleeding exacerbates the mass lesion , induces local compression of the microvasculature , and contributes to subsequent neurovascular dysfunction [ 3 , 68 , 5053 , 55 , 56 ] . hemolysis promotes spontaneous hematoma resolution ; however , the concurrent production of hemoglobin degradation metabolites induces the release of proinflammatory mediators within and around the hematoma core . along these lines , acute increases in tnf- within the cerebrospinal fluid and plasma of spontaneous ich patients correlated with patient mortality . furthermore , increased expression of fasl and a corresponding decrease in s - fas ( an inhibitor of fas activation ) were detected in perihematomal brain tissue from ich patients , as compared to control patients . although the functional significance of the inflammatory response remains incompletely understood , acute expression of both fasl and tnf- was associated with cellular injury and with edema formation after ich [ 19 , 57 , 58 ] . these findings suggest a detrimental role for the early inflammatory response after ich , yet the precise mechanisms whereby inflammation contributes to poor patient outcomes remain elusive . cell death is an important component of neurological injury after ich , although the form(s ) of cell death after ich remain poorly defined . features of both apoptotic and necrotic cell death appear within six hours of injury in perihematomal neurons and glia in preclinical ich models and in postmortem human studies , with peak injury noted at three days [ 5962 ] . similarly , loss of plasmalemma integrity , a phenotypic hallmark of necrotic cell death , increased over the first three days after collagenase - induced ich in mice , further suggesting a prominent role for necrosis after ich . in contrast to the view of necrosis as a passive , irreversible form of cell death , necroptosis is a newly described form of programmed necrosis that is induced by fasl and/or tnf- . as activation of the proinflammatory transcription factor , nfb , was associated with cell death after ich , we hypothesized that necroptosis may contribute to neurovascular injury after a brain hemorrhage . to test this possibility , we investigated whether nec-1 , a novel small molecule inhibitor of necroptosis , could reduce neurological injury after ich . herein , we identified a novel role for nec-1 in reducing cell death , attenuating hematoma expansion , limiting blood - brain barrier disruption , and restricting edema development after ich . our findings , which are in agreement with a recent report showing nec-1 on apoptotic and autophagic cell death after collagenase - induced ich , extend these findings using clinically relevant endpoints and suggest a potential role for targeting cell death pathways after ich . although the mechanism(s ) whereby nec-1 limited neurological injury were not explored in this study , it is notable that the biologically inactive , structural analog of nec-1 did not exert the same protective effects of nec-1 with respect to bbb opening , edema development , and behavioral outcomes ; however , it is noteworthy that nec-1inactive attenuated hematoma volume to a similar magnitude as compared to nec-1 . whereas these data suggest that the actions of nec-1 may be selective rather than due to a nonspecific antioxidant effect , it remains unclear how nec-1inactive selectively exerted this effect on hematoma volume . notably , a recent report suggested that nec-1inactive exerts biological activity on some necroptosis assays and sensitizes mice to lethality during systemic inflammatory response syndrome . these interesting results suggest that caution should be taken in the use of nec-1inactive as a true biologically inactive control to nec-1 . receptor interacting protein 1 ( rip1 ) , the proposed molecular target of nec-1 , is a serine / threonine protein kinase implicated in nfb activation as well as in the initiation of necroptotic cell death . inflammatory activation at the time of admission was associated with early neurological deterioration in ich patients and nfb activation was sustained over the first several days in a preclinical ich model . we and others reported that nfb activation stimulates the expression of inflammatory mediators associated with necroptosis ( e.g. , tnf- ) , induces blood - brain barrier permeability , increases edema development , and exacerbates neurobehavioral deficits after experimental ich [ 15 , 17 , 39 ] . furthermore , we reported that the nfb inhibitor , curcumin , promoted hematoma resolution and improved neurological outcomes after collagenase - induced ich in mice . taken together , these results raise the unexplored possibility that rip1 mediates acute neurological injury after ich . future work by our laboratory will characterize this interesting mechanism in further detail . nuclear blebbing and karyorrhexis were observed in glial cells within the white matter after intraventricular hemorrhage in preterm infants . astrocytic loss temporally preceded vascular injury after experimental ich [ 28 , 62 ] and focal astrocyte loss increased microvascular damage and induced transient bbb opening . although the cellular targets of nec-1 after ich were beyond the scope of the present study , these findings raise the possibility that the beneficial effects of nec-1 observed herein may involve , at least in part , maintenance of glial function . astrocytes are the primary source of the nonenzymatic antioxidant , glutathione , within the brain . we first reported that hemin rapidly depleted intracellular glutathione and induced caspase - independent cell death in murine astrocytes via an inflammatory mechanism . interestingly , this cellular injury was reversed by nec-1 , suggesting a role for necroptosis after hemorrhagic injury . our finding is consistent with a subsequent report demonstrating that glutathione depletion enhanced the release of neurotoxic substances , including tnf- from human astrocytes . similarly , nec-1 prevented glutamate - induced glutathione depletion and caspase - independent cytotoxicity in ht-22 cells . coupled with our recent finding that astrocyte - derived glutathione reduced hemorrhagic injury in cerebral microvessels , nec-1 may improve neurological outcomes by limiting astrocytic dysfunction . necroptosis is a novel form of programmed cell death that is initiated by proinflammatory mediators , such as tnf-. the model of ich utilized in this study involves the intrastriatal injection of bacterial collagenase . although this model best recapitulates the spontaneous intracerebral bleeding and evolving hematoma expansion observed in patients , collagenase may induce an exaggerated inflammatory response . nonetheless , cells exhibiting both apoptotic and/or necrotic phenotypes characteristic of necroptosis are observed in postmortem human brain sections , suggesting the validity of the protection observed in this study . another limitation of the present study is that the mechanisms of nec-1 protection remain undetermined . although regarded as a highly specific rip1 inhibitor , several in vitro studies suggest a possible direct antioxidant role for nec-1 . furthermore , nec-1 also may block indoleamine-2,3-dioxygenase ( ido ) , which catabolizes tryptophan into kynurenine . the inclusion of nec-1inactive is consistent with a selective effect of nec-1 as this analogue does not reportedly exhibit antioxidant activity nor does it inhibit mouse ido , although a recent conflicting report suggests that nec-1inactive may attenuate human ido activity . thus , the possibility that some or all of the beneficial actions of nec-1 are mediated via rip1-independent mechanisms after ich can not be excluded . future work by our laboratory will further characterize the specific therapeutic role of rip1 targeting after brain hemorrhage . regardless of the precise cellular mechanism , the necroptosis inhibitor , nec-1 , reduced neurovascular injury and improved outcomes when administered at the time of injury in a preclinical model of ich . these data suggest that therapeutic targeting of programmed necrosis may improve patient outcomes after a brain hemorrhage . future work with more selective necroptosis inhibitors will establish the therapeutic window for improving neurovascular outcomes after ich , providing a framework for potential clinical translation of these findings .

intracerebral hemorrhage ( ich ) is the most common form of hemorrhagic stroke , accounting for 15% of all strokes . ich has the highest acute mortality and the worst long - term prognosis of all stroke subtypes . unfortunately , the dearth of clinically effective treatment options makes ich the least treatable form of stroke , emphasizing the need for novel therapeutic targets . recent work by our laboratory identified a novel role for the necroptosis inhibitor , necrostatin-1 , in limiting neurovascular injury in tissue culture models of hemorrhagic injury . in the present study , we tested the hypothesis that necrostatin-1 reduces neurovascular injury after collagenase - induced ich in mice . necrostatin-1 significantly reduced hematoma volume by 54% at 72 h after - ich , as compared to either sham - injured mice or mice administered an inactive , structural analogue of necrostatin-1 . necrostatin-1 also limited cell death by 48% , reduced blood - brain barrier opening by 51% , attenuated edema development to sham levels , and improved neurobehavioral outcomes after ich . these data suggest a potential clinical utility for necrostatin-1 and/or novel necroptosis inhibitors as an adjunct therapy to reduce neurological injury and improve patient outcomes after ich .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Unlawful Internet Gambling Enforcement Clarification and Implementation Act of 2008''. SEC. 2. CONGRESSIONAL FINDINGS AND PURPOSE. (a) Findings.--Congress finds the following: (1) Prior to the passage of the Unlawful Internet Gambling Enforcement Act of 2006 (hereafter in this section referred to as the ``UIGEA''), Public Law 109-347, on October 13, 2006, Federal law was both vague and outdated regarding Internet gambling activities, as Federal criminal gambling statutes were passed decades before the commercial use of the Internet. (2) To date, all Federal Internet gambling prosecutions have involved sports betting, creating a lack of authoritative court decisions on the applicability of other federal criminal statutes to Internet poker and casino-style gambling. (3) Sports betting, which is illegal in 49 of the 50 States, is viewed as particularly harmful because its potential adverse impact on the integrity of professional and amateur sports, and is the one form of gambling where there is settled Federal case law clarifying it as illegal on the Internet. (4) Many European Internet gambling companies offering services not including sports betting to persons in the United States were fully listed on the London Stock Exchange, and thereby subject to high standards of transparency and scrutiny, but upon receiving clarification of United States law regarding Internet gaming through the enactment of the UIGEA, these companies closed their sites to persons in the United States. (5) Continued legal jeopardy for companies that made a good faith effort to comply voluntarily with clarified United States law following the passage of the UIGEA punishes behavior that the law intended to foster and inadvertently rewards continued noncompliance by other foreign entities. (6) In light of the foregoing and in deference to long- standing constitutional requirements of fair notice and transparency in the criminal law, the Congress finds it necessary to clarify that criminal statutes applicable to gambling do not apply to any person who offered Internet gambling services that did not include sports betting prior to October 13, 2006, and who ceased offering Internet gambling services to persons in the United States upon passage of the UIGEA. (7) To effect the purposes and intent of the UIGEA, it is the sense of the Congress that the Attorney General should focus any prosecutorial efforts on those persons who-- (A) offer Internet sports betting in the United States; or (B) process payments for illegal Internet sports betting in the United States. SEC. 3. UIGEA CLARIFICATION AND IMPLEMENTATION. (a) In General.--Subchapter IV of chapter 53 of title 31, United States Code, is amended by adding at the end the following new section: ``Sec. 5368. Voluntary compliance ``(a) In General.--Notwithstanding any other provision of law-- ``(1) except as provided in paragraphs (2) and (3), no person shall be subject to criminal liability arising out of-- ``(A) the offering, receipt or facilitation of bets or wagers by means of the Internet; ``(B) financial transactions in connection with or involving the consideration for, or proceeds of, bets or wagers by means of the Internet; ``(C) the administration, advising, audit, direction, operation, lending, management, marketing or supplying of a business or services involving activities or transactions referred to in subparagraph (A) or (B); or ``(D) the banking, brokerage, custody, issuance, placement, promotion, sale or transfer of shares or proceeds from a business involving activities or transactions referred to in subparagraph (A), (B), or (C); ``(2) paragraph (1) shall not apply to any person who knowingly-- ``(A) offered illegal bets or wagers to, or received bets or wagers from, any person within the United States by means of the Internet after October 13, 2006; ``(B) in violation of section 1084 of title 18, United States Code, used the Internet for the transmission in interstate or foreign commerce of bets or wagers on any sporting event or sporting contest, or information assisting in the placing of bets or wagers on any sporting event or contest, by any person within the United States; or ``(C) processed or facilitated financial transactions in connection with or involving the consideration for, or proceeds of, involving activities or transactions referred to in subparagraph (A) or (B); and ``(3) paragraph (1) shall not apply to conduct that violated sections 1956 or 1957 of title 18, United States Code, by a financial or monetary transaction, or the transfer or transportation of funds, with the intent to promote unlawful activity other than the offering, receipt, or facilitation of bets or wagers by means of the Internet, or to conceal or disguise the nature, location, source, ownership, or control of the proceeds of unlawful activity other than the offering, receipt, or facilitation of bets or wagers by means of the Internet. ``(b) Criminal Liability Defined.--For purposes of subsection (a), the term `criminal liability' includes actions against real or personal property that arise from or depend upon the allegedly criminal nature of the bet or wager or of the transmission or receipt of funds in connection with that bet or wager.''. (b) Clerical Amendment.--The table of sections for subchapter IV of chapter 53 of title 31, United States Code, is amended by inserting after the item relating to section 5367 the following new item: ``5368. Voluntary compliance.''. SEC. 4. RULE OF CONSTRUCTION. No provision of this Act, or any amendment made by this Act, shall be construed as clarifying or implying that Internet bets or wagers, other than sports bets or wagers, which were accepted subsequent to October 13, 2006, are in violation of Federal law.

Unlawful Internet Gambling Enforcement Clarification and Implementation Act of 2008 - Expresses the sense of Congress that the Attorney General should focus prosecutorial efforts on persons who: (1) offer Internet sports betting in the United States; or (2) process payments for illegal Internet sports betting in the United States. Amends federal law governing prohibited funding of unlawful Internet gambling to declare that no person shall be subject to criminal liability arising out of certain bets or wagers by means of the Internet. Defines criminal liability to include actions against real or personal property that arise from or depend upon the allegedly criminal nature of the bet or wager or of the transmission or receipt of funds in connection with that bet or wager.

NASHVILLE, Tenn. (WKRN) – Nearly two weeks since the disappearance of missing Maury County teen Elizabeth Thomas, there are claims from her father that suggest she once hid from Tad Cummins at her workplace. One of the Thomas family’s attorneys told News 2 Elizabeth’s father said Cummins went into Elizabeth’s work and she begged a co-worker to tell him she wasn’t there. Elizabeth reportedly hid in the bathroom while Cummins was in the business. PHOTOS: AMBER Alert for Elizabeth Thomas Elizabeth’s friend Ashlee Riggins told News 2 she just hopes she makes it home safely. “She’s helped me through so many things, she’s been there with me through the hard times. I want her back, I want my best friend back,” said Ashlee. Elizabeth Thomas was last seen on March 13 after she was dropped off at the Shoney’s in Columbia by a friend around 8 a.m. She was reported missing later that same day by her parents and is believed to be in the company of 50-year-old Tad Cummins, who is believed to be armed with two handguns. Thomas is a 15-year-old white female, with hazel eyes, stands 5 feet tall and weighs 120 pounds. She was last seen wearing a flannel shirt and black leggings. Cummins is a white male, who stands 6 feet tall, weighs approximately 200 pounds, and has brown hair and eyes. He was last seen driving a Silver Nissan Rogue with TN license plate 976ZPT. Anyone who spots the SUV and can verify the license plate should call 911. Cummins faces kidnapping in the AMBER Alert case and is also charged with sexual contact with a minor after he allegedly kissed Thomas at school earlier this year. Anyone with information on their whereabouts should call 1-800-TBI-FIND. As of Saturday afternoon, the TBI had received 985 tips, with 116 still open and being pursued. Click here for more on the AMBER Alert for Elizabeth Thomas. ||||| Tad Cummins and Elizabeth Thomas (Photo: ABC) ABC News ) -- As law enforcement officers across the country continue to hunt for Tennessee teen Elizabeth Thomas and her former teacher Tad Cummins --- the 50-year-old man who allegedly kidnapped the 15-year-old -- investigators have shed light on their relationship, revealing that emails between the pair have uncovered a "romantic interest in each other." Thomas and Cummins wrote emails to each other but did not send them -- instead they would save the email in the drafts folder of Cummins' school email account, the Maury County District Attorney and the Sheriff's Office revealed Friday. "They would write the message and let it save as a draft," Maury County District Attorney Brent Cooper explained to ABC affiliate WAAY in Huntsville, Alabama. "The other person would log in, read the message and then delete it and then write another message that was saved as a draft." Investigators said the pair wrote inappropriate messages to each other, but Cooper declined to elaborate. "If you read them you would immediately recognize you are reading messages between two people who have a romantic interest in each other," Cooper said. The lead investigator on the case shared one of the emails with WAAY. NEW PICTURE: Here's Tad Cummins and Elizabeth Thomas at school in January, days before his alleged inappropriate contact with her. pic.twitter.com/BzyIz8KPpY — TBI (@TBInvestigation) March 21, 2017 "'I saw you standing next to you backpack this morning' and [Cummins] makes a reference to a body part of hers and how nice that looked," said Marcus Alright with the Maury County Sheriff's Department. UPDATE: We have determined the purchase of hair dye by Tad Cummins was not part of his intended plan for #ElizabethThomas. #TNAMBERAlert pic.twitter.com/mzrPlhvOhQ — TBI (@TBInvestigation) March 21, 2017 Chandler Anderson, a nurse practitioner in Columbia, Tennessee, first met Cummins in 1998. Prior to being a teacher he was a respiratory therapist. Anderson says he's worried about Thomas. "You've got to do something to motivate people to be more vigilant about trying to find this young girl, because this is not going to end well if we don't get her home, and get her home soon," he said. © 2017 ABC News

– Elizabeth Thomas, the 15-year-old girl believed to have been abducted by teacher Tad Cummins two weeks ago, once hid from Cummins when he turned up at her workplace, her family says. One of the Thomas family's lawyers tells News 2 that, according to Elizabeth's father, she hid in the bathroom when the 50-year-old teacher visited the business and begged co-workers to tell him that she wasn't there. Investigators say they've uncovered emails that make it clear there was some kind of romantic connection between the pair, who posted cryptic messages on Instagram before they disappeared March 13, reports WHAS 11. Maury County DA Brent Cooper says that instead of sending emails to each other, Cummins and Elizabeth would both use Cummins' school email account and leave messages to each other saved in the draft folder. "If you read them you would immediately recognize you are reading messages between two people who have a romantic interest in each other," Cooper says. NBC News reports that on Sunday, Thomas' family released a video of the girl in the hopes someone would recognize the girl's voice, and Cummins' wife, Jill, again urged him to turn himself in. "You know you can't hide forever," she said. "For your sake and for Beth's sake, please go to the police or please just drop Beth off somewhere safe."

Photo: New York Post When the New York Post isn’t devoting their journalistic resources to targeting individual homeless people over and over again, they’re churning out provocative pieces specifically engineered to take over the internet outrage cycle for the day. Take “Women are not capable of understanding ‘GoodFellas’” (by one-man troll factory Kyle Smith), or “Hey, ladies — catcalls are flattering! Deal with it.” Today’s such story, which they decided was groundbreaking enough to run on the cover, is titled “Why I Won’t Date Hot Women Anymore.” It’s a trend piece about men and women who say they’ve stopped dating the hottest women and men — who apparently only work as swimsuit models or in the finance industry — in favor of people of “substance.” And hoo boy, are people getting mad about it online. If you need to throw up fast, might I suggest this article? https://t.co/w7qOkfDw9F via @nypost — John Iadarola (@johniadarola) April 13, 2017 This story, shorter: Pretty women are terrible and stupid and all men are great and smart. https://t.co/y0i4E4vUyP — Molly Beck (@MollyBeck) April 13, 2017 I don't believe in heaven or hell but this makes me feel like some people are bad https://t.co/bv439RQAvk — Margarita Noriega (@margarita) April 13, 2017 Let’s review who loses in this article: First, Dan Rochkind — the man who they used for the lede image — who says he’s sworn off dating models even though … well, you can judge the photo for yourself. Then, Rochkind’s fiancée, who, for some reason, agreed to be in an article about a man who’s decided to date less attractive women than he used to. There’s also this guy, who shows up shirtless and playing the violin for some reason. Hot people in general lose because of unfair stereoty- … wait no, haha, scratch that. But most of all, we lose — while, as always, the Post wins. ||||| The New York Post ran an article titled “Why I won’t date hot women anymore” last night, which has been relentlessly mocked and dragged to shreds. However, just as we took a moment to question the reasoning behind the infamous “Why I’ll Never Date a Feminist,” The Mary Sue looks out into the distance again to wonder: Are there legitimate reasons not to date hot women? Is Dan Rochkind, in this article that introduces his fiancé as “isn’t a bikini model” before it mentions her name, actually onto something? Here are some reasons for not dating a hot woman: Hot girls take a lot of selfies. Their arms are strong. They will overpower and destroy you. You’re suspicious of her hotness. What if it’s not “real” beauty, but a manufactured hotness? Like, what if she’s actually an ivory statue brought to life by the goddess Aphrodite, and you’re not really into that? Looks will fade. Everything will fade. We’re only a small dot in the universe. She looks different in the morning than she does at night. You haven’t read up on your Arthurian legends and when asked whether you want a bride that’s beautiful during the day or night you forgot to give her sovereignty. This is really on you. Cooties, again. Maintaining hotness means keeping to certain routines and diets, and you’re a carnivorous creature from the underworld that feeds on livestock. Incompatible lifestyles. You like taking baths and you don’t appreciate hot girls making a mess by bathing in the blood of virgins every night. When you go swimming, hot girls can’t really sink. They only float. This puts a big damper on your family’s yearly scuba trips. Maybe you just suck, like, as a person. (Image: Universal Pictures) Want more stories like this? Become a subscriber and support the site! —The Mary Sue has a strict comment policy that forbids, but is not limited to, personal insults toward anyone, hate speech, and trolling.— Follow The Mary Sue on Twitter, Facebook, Tumblr, Pinterest, & Google+. ||||| When it came to dating in New York as a 30-something executive in private equity, Dan Rochkind had no problem snagging the city’s most beautiful women. “I could have [anyone] I wanted,” says Rochkind, now 40 and an Upper East Sider with a muscular build and a full head of hair. “I met some nice people, but realistically I went for the hottest girl you could find.” He spent the better part of his 30s going on up to three dates a week, courting 20-something blond models, but eventually realized that dating the prettiest young things had its drawbacks — he found them flighty, selfish and vapid. “Beautiful women who get a fair amount of attention get full of themselves,” he says. “Eventually, I was dreading getting dinner with them because they couldn’t carry a conversation.” According to new research, Rochkind’s ideas about sexy bikini babes are correct. A multipart study from Harvard University, University of La Verne and Santa Clara University researchers found that beautiful people are more likely to be involved in unstable relationships. In one part, the researchers looked at the top 20 actresses on IMDb and found that they tend to have rocky marriages. In another, women were asked to judge the attractiveness of 238 men based on their high school yearbook photos from 30 years ago. The men who were judged to be the best-looking had higher rates of divorce. Looking to avoid such a fate, Rochkind started dating a woman who isn’t a bikini model, Carly Spindel, in January 2015. The two are now happily engaged. The two met after Spindel’s mother, matchmaker Janis Spindel, scouted Rochkind at a gym. “I gave him my card and said I have the perfect girl for him,” recalls Janis, founder of Serious Matchmaking, based in Midtown. “Successful men who are in shape have the pickings when it comes to dating, [but] eventually they want a woman of substance.” Rochkind found that in Carly, 30, a lovely brunette who’s the vice president of her mother’s matchmaking company and a Syracuse University graduate. Rochkind proposed to her last May in Central Park. He loves that Carly isn’t like the swimsuit models he used to go for. “[She] is a softer beauty, someone you can take home and cuddle with, and she’s very elegant,” Rochkind says. “And she’s 5-foot-2, so she can’t be a runway model, but I think she’s really beautiful and is prettier than anyone I’ve dated.” Carly has no qualms about how her future husband views her compared with his exes. “When men get to a certain age, they realize that it’s important to meet a life partner that they connect with,” she says. “Looks fade.” Some great-looking people say they’re given a bad rap unfairly. “When men see beautiful women, they are more concentrated on how she looks because they want to ‘have’ her, and so they don’t want to go deeper and get to know her,” says Isabell Giardini, a 22-year-old Italian beauty signed with Major Models. “And that’s why at the end of a date they wonder, ‘Oh that girl is so beautiful but so empty.’ That’s happened to me often.” Others say the stereotypes about pretty people being shallow are true, even if they’re hotties themselves. “From my personal experience, people who are better looking are less likely to pursue advanced degrees, or play an instrument or learn other languages,” says Benedict Beckeld, a 37-year-old Brooklyn writer with a doctorate in philosophy and the body of an Adonis. But he’s quick to note that he’s not just a great set of abs — he also plays the violin and speaks seven languages. After dating an athletic banker with model good looks for two years, Sonali Chitre, 34, has sworn off hotties. “He was a Nazi about his diet and would work out hard-core and cared more about his body than just living life,” says Chitre, who broke up with the finance guy last October. ‘When men get to a certain age, they realize that it’s important to meet a life partner that they connect with. Looks fade.’ - Carly Spindel Chitre, an environmental lawyer and the founder of Priyamvada Sustainability Consulting, considers herself “a 9 or a 10,” but she says she’s done with gorgeous guys. Now, she’s more interested in “superballer” men with high-paying careers. “I still want someone who’s in decent shape, but it’s more important to find a guy who’s goal-oriented,” she says. “[Beautiful men] are very into their bodies and don’t really care about people that much, or make time for their family.” Megan Young, a 23-year-old p.r. woman from Hoboken, NJ, also changed her dating habits. The svelte, blue-eyed brunette used to exclusively date 6-foot-tall dudes who looked like Calvin Klein models. “As a person who’s always been complimented on [my] ‘stunning beauty’ … I’d been searching for a ‘hot’ guy to match the label I had always been given,” says Young. “But after a date or two, they’ll have problems hanging out with you and then will ghost.” Last year, she stopped putting looks at the top of her dating criteria on Bumble, instead opting for guys who traveled a lot and were “make the most out of their lives” types. In August 2016, she met Christopher Argese, a 27-year-old security technician. Unlike the square-jawed bachelors who disrespected her, Argese is more boy-next-door in the looks department. But he’s kind and attentive. “He’s not a model, but he’s so much more attractive in who he is as a person,” Young says. And best of all, she says, Argese doesn’t just see her as a status symbol. “When I asked him why he loves me, he said that he loves my drive and my passion,” Young says. Rochkind is equally enthusiastic about his decision to give up high-maintenance hotties. “There’s something to be said about sowing your wild oats and getting them out of your system,” says Rochkind, who will marry Carly in June at a “Tuscan-romantic” ceremony at the Wölffer Estate Vineyard in the Hamptons. But he doesn’t regret his past. “You don’t want to be the first to leave the party, but you don’t want to leave the party too late either,” he says. “Carly came at exactly the right time.” ||||| The New York Post published an article Wednesday evening entitled , “Why I Won’t Date Hot Women Anymore,” which profiles enlightened New York daters who’ve realized it’s possible to form personal connections with people who aren’t extremely hot. The piece follows 40-year-old Dan Rochkind who very heroically decided to give up dating just “the prettiest young things.” NYPost A screenshot of the article. “Beautiful women who get a fair amount of attention get full of themselves,” Rochkind told the Post. “Eventually, I was dreading getting dinner with them because they couldn’t carry a conversation.” Rochkind is described as having “a muscular build and a full head of hair” who is engaged to a non-bikini model (an actual distinction made in the article!) Carly Spindel. Spindel is described as “merely beautiful,” a clear demotion from Rochkind’s pinnacle of hot. “[She] is a softer beauty, someone you can take home and cuddle with, and she’s very elegant,” Rochkind said. “And she’s 5-foot-2, so she can’t be a runway model, but I think she’s really beautiful and is prettier than anyone I’ve dated.” Spindel, the vice president of her mother’s matchmaking company, was confused by how she was described in the article: When the @nypost tells you you're not a swimsuit model, I'm not sure if I should be flattered or insulted!? A post shared by Carly Spindel (@carlyspindel1) on Apr 12, 2017 at 5:01pm PDT Is Carly okay? Should we save Carly? I feel like we should do a Go Fund Me for Carly, Dan Rochkind's girlfriend. https://t.co/X2f6sWTuIg — katie rosman (@katierosman) April 13, 2017 The article also features several interviews with individuals who are “great-looking people” that believe they’ve been “given a bad rap unfairly.” There’s the 37-year-old Brooklyn writer, Benedict Beckeld, who is described as having “a doctorate in philosophy and the body of an Adonis.” “From my personal experience, people who are better looking are less likely to pursue advanced degrees, or play an instrument or learn other languages,” Beckeld says. There’s also Sonali Chitre, an environmental lawyer who is “done with gorgeous guys” and is looking for a “superballer.” Where did the Post find these people?! As if we didn’t have enough proof that the New York dating scene is a vacuous cesspool of hell and misery, this article only reinforces it. How this article was published and isn’t classified as satire is truly incredible. And Twitter agrees: as an extremely hot woman i'm feeling personally attacked by that nypost article — Jessica Roy (@JessicaKRoy) April 13, 2017 .@LE_Scrawls and I just talked about how exhausting it is to live w/constant awareness of rape but now I know what real suffering looks like pic.twitter.com/Dppq8oOvgv — Bailey (@the_author_) April 13, 2017 Because hot women won't date you anymore. Next question. pic.twitter.com/k8CxdSNgQu — Zach Heltzel (@zachheltzel) April 13, 2017 The thing I love about this NYP article is it is full of people who deserve each other — Shane (@shaneferro) April 13, 2017 To be clear the NY Post article guy has absolutely never dated a swimsuit model in his life. He once went out with a girl who owned a bikini — Amanda Mull (@amandamull) April 13, 2017 A 40 Y.O. man now realizes that women can be both beautiful and full of substance. He spent decades CHOOSING not to see them this way. — Morgan Jerkins (@MorganJerkins) April 13, 2017 "Beautiful women get full of themselves" says this guy who is totally not full of himself. pic.twitter.com/485RKwNZH4 — MatzohNoSheTwitnt (@OhNoSheTwitnt) April 13, 2017 You're all making fun of that article, but it's because you can't empathize with us hot people, us hotties. — Kevin Nguyen (@knguyen) April 13, 2017 this caption is so savagely written this has to be a piece of satire pic.twitter.com/yqL59UMkTO — Gideon Resnick (@GideonResnick) April 13, 2017 Feel like it took the guy I used to work with a few hours to come up with his "I don't date hot women anymore...because I'm married" FB joke — Jason Diamond (@imjasondiamond) April 13, 2017 Some people even had commentary about the iconic photographs in the article: @fivefifths I'm here for the other dude they feature, with his casual photo shoot. Just readin' some books, playin' my fiddle. pic.twitter.com/G89n603A3C — Anil Dash (@anildash) April 13, 2017 I just read the hot ppl article and my big q is why does that guy play violin shirtless — Jen Doll (@thisisjendoll) April 13, 2017 Rochkind assures readers that with his new fiance, he’s “enthusiastic about his decision to give up high-maintenance hotties.” Please put “high-maintenance hottie” on my tombstone? ||||| I am a hot woman. I don’t have a name because I never needed one because I’m so hot. (Like a lot of hot women, I don’t even have a social security number. Just a card that says “HOT” followed by a series of 10s.) Earlier today, I read (or had someone read to me, because remember, I am hot) the New York Post article about the average-looking, uninteresting man who is no longer dating hot women because we are too boring and now I can’t stop crying hot tears from my hot hot eyes. When 40-year-old Dan Rochkind, an “Upper West Sider with a muscular build and a full head of hair,” told the Post that “beautiful women who get a fair amount of attention get full of themselves,” I was like, Oh, my God. He is so right. How have I been disappointing Rochkind with my ego for so long? What will I do now? When he added,“Eventually, I was dreading getting dinner with them because they couldn’t carry a conversation,” it was the killing blow. It’s true. Because I am hot, I am also very stupid and have nothing to say because all I can think about is your money and how much I want it. Either that or I get distracted by my own reflection and think Wow, she’s hot. Oh, wait. That’s just me. And then I think about that for a little while. To be fair, I also have a hard time forming words with my very hot mouth and when I try I only make orgasm sounds, so it’s not all my fault. Dan, I am so sorry that I, a hot model in my early 20s, have been boring you, a man two decades older than me. As an executive in private equity (so rare in New York!), you are inherently interesting and I should have been more engaged as you talked to me about NOT boring things like your definition of the term “umami,” the great time you and your bros had at the LCD Soundsystem reunion show, and how you just don’t “get” Melissa McCarthy. Advertisement It says more about me, Hot Woman, than you, Dan Rochkind, and I really hope you’ll consider dating me and my hot 20-something friends again. Really, we’re all so broken up over you taking yourself off the market to date a 30-year-old who you merely describe as “a softer beauty.” I have a similar plea for Benedict Beckeld, the Brooklyn writer in his late 30s (again, such a rare gem!) who told the Post that in his experience, “people who are better looking are less likely to pursue advanced degrees, or play an instrument or learn other languages.” I actually have the same degree from Harvard Business School that Tyra Banks got (literally the same one, she gave it to me because, as two hot women, we really get along). I also, like a lot of 20-something models, speak multiple languages, a necessary skill because a lot of us emigrate and it’s also a necessity of our trade. But anyway, yes, these older men have me and my hot young friends pegged. We are too hot for college and too hot for “learning,” unlike Beckeld, a man with a philosophy degree and “body of an Adonis” who quotes Nietzsche in his Instagram thirst pics. How could we ever be good enough for that? Honestly, it is admirable that you are willing to date women who are only very decent looking and 10-12 years younger than you, but at the same time... come back? We’ve experienced what the world is like with you two hunks off the market and frankly, it’s horrible. Just stroll down Elizabeth Street or visit the Soho Whole Foods and tell me what you see! You’ll barely be able to take a step without stumbling over 6 foot tall, blonde 23-year-old Dutch model—drawn to America by the promise of your penis—collapsed in the Kombucha aisle in a heap of grief. Cross the river into Brooklyn, take the elevator to the top of the Wythe Hotel and hear the high pitch wails that echo from the surrounding Williamsburg penthouses. It’s deafening. Advertisement Please, Dan. Please, Benedict. We’re so, so hot, so, so boring, and so, so lost without you. ||||| Dan Rochkind (left), who is quoted in the story, and his fiancee, Carly Spindell. A New York Post story with the headline “Why I won’t date hot women anymore” went viral Thursday morning — because of course it did. The piece was based on a study out of Harvard, University of La Verne, and Santa Clara University that found that “those rated as more attractive in high school yearbooks were married for shorter durations and more likely to divorce.” Advertisement Like many who read it, I did the mother of all eye rolls when I got to the point where a man named Dan Rochkind is quoted as saying that he’s really happy about marrying his fiancee — even though she isn’t a bikini model. How kind of him, right? He must be very deep! Get The Weekender in your inbox: The Globe's top picks for what to see and do each weekend, in Boston and beyond. Sign Up Thank you for signing up! Sign up for more newsletters here I paused later in the story when I realized that Rochkind’s fiancee's name — Carly Spindel — was familiar. Carly’s mom, Janis, a professional matchmaker who’s also quoted, contacted me a few times years ago. Back then, I assumed she was reaching out because I write an advice column (Love Letters) and figured she wanted to pitch a story about her dating service. But then I realized her notes seemed unduly interested in my marital status. “So you are supposed to be BEYOND AWESOME and SINGLE?” she wrote. Advertisement I inferred that she wanted to set me up. I didn’t respond. Thursday morning, though, after I read the Post story, I gave Janis a call to find out what she thought of the article, which by midmorning was drawing a lot of attention and backlash. Janis was quick to point out that the Post’s take wasn’t quite right. She said that the story suggests that Rochkind is settling, when, in fact, he’s always been attracted to her daughter — and that no one meant to imply that Carly isn’t beautiful. “My daughter is gorgeous, gorgeous, gorgeous,” Janis said. (For the record, Janis also says that the Post is wrong about Rochkind living on the Upper West Side; he’s on the Upper East.) Janis said that when she was interviewed about setting Rochkind up with her daughter she tried to make the point that looks aren’t everything. Without substance, she said, “it’s a deal-breaker.” But, she added, “Beauty is still the No. 1 priority.” She didn’t define “beauty.” Spindel’s Serious Matchmaking company is based in New York, but also does work in Boston, which Janis said is her second most popular city. She said she’s made a few marriages here. She’s set men up with “gorgeous” women, she said. “Beautiful.” I had to ask whether I was right to assume that when she contacted me years ago, she was recruiting me — for men. “You were single, right?” “Um . . . ” “Are you still single?” “Um . . . ” “See? You didn’t answer then. . . . Now we’ll find you a husband.” “Oh . . . thanks anyway,” I said. I think we were both a little confused, but then I remembered that she lives in a world where everyone wants one.

– Hoo-boy. The New York Post ran a story Wednesday titled "Why I won't date hot women anymore" featuring an interview with a 40-year-old private equity executive who boasts he "could have [anyone] I wanted." Dan Rochkind says he used to go on multiple dates a week with "20-something blond models," but he eventually realized these hot women were all "flighty, selfish, and vapid." They were "full of themselves" and "couldn't carry a conversation," he adds. And that's why he's now engaged to a 30-year-old woman, despite the fact that she's a "softer beauty" who's far too short to be a runway model. Understandably, people had some strong feelings on the article. Here are some of them: New York says the article is the Post's "greatest troll yet," ably accomplishing the paper's usual goal of angering the internet for a day or two. A hot woman responds on Jezebel while "crying hot tears from my hot hot eyes" because she can no longer date the "average-looking, uninteresting man" from the article. It only gets more brutal from there. A reporter for the Wisconsin State Journal sums up the story on Twitter: "Pretty women are terrible and stupid and all men are great and smart." The Huffington Post, which sarcastically refers to Rochkind as a hero, rounds up some of the other great Twitter reactions to the piece. Rochkind's fiancee, Carly Spindel, doesn't appear too pleased with the article, accusing the Post on Instagram of "making me look beyond unattractive." Spindel's mom, who runs a matchmaking site and set up Rochkind with her daughter, called out what she saw as some of the article's flaws in an interview with the Boston Globe. ("My daughter is gorgeous, gorgeous, gorgeous.") Finally, the Mary Sue offers its own list of reasons not to date hot women, including that hot women have scary strong arms from taking selfies all the time; may actually be statues brought to life rather than merely statuesque; and, of course, cooties.

SECTION 1. ELIMINATING BARRIERS TO JOBS FOR LOAN ORIGINATORS. (a) In General.--The S.A.F.E. Mortgage Licensing Act of 2008 (12 U.S.C. 5101 et seq.) is amended by adding at the end the following: ``SEC. 1518. EMPLOYMENT TRANSITION OF LOAN ORIGINATORS. ``(a) Temporary Authority To Originate Loans for Loan Originators Moving From a Depository Institution to a Non-Depository Institution.-- ``(1) In general.--Upon employment by a State-licensed mortgage company, an individual who is a registered loan originator shall be deemed to have temporary authority to act as a loan originator in an application State for the period described in paragraph (2) if the individual-- ``(A) has not had an application for a loan originator license denied, or had such a license revoked or suspended in any governmental jurisdiction; ``(B) has not been subject to or served with a cease and desist order in any governmental jurisdiction or as described in section 1514(c); ``(C) has not been convicted of a felony that would preclude licensure under the law of the application State; ``(D) has submitted an application to be a State- licensed loan originator in the application State; and ``(E) was registered in the Nationwide Mortgage Licensing System and Registry as a loan originator during the 12-month period preceding the date of submission of the information required under section 1505(a). ``(2) Period.--The period described in paragraph (1) shall begin on the date that the individual submits the information required under section 1505(a) and shall end on the earliest of-- ``(A) the date that the individual withdraws the application to be a State-licensed loan originator in the application State; ``(B) the date that the application State denies, or issues a notice of intent to deny, the application; ``(C) the date that the application State grants a State license; or ``(D) the date that is 120 days after the date on which the individual submits the application, if the application is listed on the Nationwide Mortgage Licensing System and Registry as incomplete. ``(b) Temporary Authority To Originate Loans for State-Licensed Loan Originators Moving Interstate.-- ``(1) In general.--A State-licensed loan originator shall be deemed to have temporary authority to act as a loan originator in an application State for the period described in paragraph (2) if the State-licensed loan originator-- ``(A) meets the requirements of subparagraphs (A), (B), (C), and (D) of subsection (a)(1); ``(B) is employed by a State-licensed mortgage company in the application State; and ``(C) was licensed in a State that is not the application State during the 30-day period preceding the date of submission of the information required under section 1505(a) in connection with the application submitted to the application State. ``(2) Period.--The period described in paragraph (1) shall begin on the date that the State-licensed loan originator submits the information required under section 1505(a) in connection with the application submitted to the application State and end on the earliest of-- ``(A) the date that the State-licensed loan originator withdraws the application to be a State- licensed loan originator in the application State; ``(B) the date that the application State denies, or issues a notice of intent to deny, the application; ``(C) the date that the application State grants a State license; or ``(D) the date that is 120 days after the date on which the State-licensed loan originator submits the application, if the application is listed on the Nationwide Mortgage Licensing System and Registry as incomplete. ``(c) Applicability.-- ``(1) Any person employing an individual who is deemed to have temporary authority to act as a loan originator in an application State pursuant to this section shall be subject to the requirements of this title and to applicable State law to the same extent as if such individual was a State-licensed loan originator licensed by the application State. ``(2) Any individual who is deemed to have temporary authority to act as a loan originator in an application State pursuant to this section and who engages in residential mortgage loan origination activities shall be subject to the requirements of this title and to applicable State law to the same extent as if such individual was a State-licensed loan originator licensed by the application State. ``(d) Definitions.--In this section, the following definitions shall apply: ``(1) State-licensed mortgage company.--The term `State- licensed mortgage company' means an entity licensed or registered under the law of any State to engage in residential mortgage loan origination and processing activities. ``(2) Application state.--The term `application State' means a State in which a registered loan originator or a State- licensed loan originator seeks to be licensed.''. (b) Table of Contents Amendment.--The table of contents in section 1(b) of the Housing and Economic Recovery Act of 2008 (42 U.S.C. 4501 note) is amended by inserting after the item relating to section 1517 the following: ``Sec. 1518. Employment transition of loan originators.''. SEC. 2. AMENDMENT TO CIVIL LIABILITY OF THE BUREAU AND OTHER OFFICIALS. Section 1513 of the S.A.F.E. Mortgage Licensing Act of 2008 (12 U.S.C. 5112) is amended by striking ``are loan originators or are applying for licensing or registration as loan originators.'' and inserting ``have applied, are applying, or are currently licensed or registered through the Nationwide Mortgage Licensing System and Registry. The previous sentence shall only apply to persons in an industry with respect to which persons were licensed or registered through the Nationwide Mortgage Licensing System and Registry on the date of the enactment of this sentence.''. SEC. 3. EFFECTIVE DATE. This Act and the amendments made by this Act shall take effect on the date that is 18 months after the date of the enactment of this Act.

. (Sec. 1) This bill amends the S.A.F.E. Mortgage Licensing Act of 2008 to temporarily allow loan originators that meet specified requirements to continue to originate loans after moving: (1)&nbsp;from one state to another, or (2) from a depository institution to a non-depository institution. (Sec. 2) The bill revises the Act's civil liability immunity provisions.

t dwarfs are brown dwarfs that exhibit methane absorption bands at 1.6 and 2.2 @xmath1 @xcite , and thus have effective temperatures t@xmath3 @xmath4 1200 - 1300 k @xcite . the prototype for this class , gl 229b @xcite , was identified as a cool companion to the nearby m1v star gl 229a . recently , seven field objects @xcite and another companion object @xcite have also been identified as t dwarfs . the rapid discovery of these cool brown dwarfs has been driven by new sky surveys , such as the two micron all sky survey ( * ? ? ? * hereafter 2mass ) and the sloan digital sky survey @xcite ; and deep near - infrared surveys , such as the eso new technology telescope deep field @xcite . the t dwarfs identified to date are remarkably similar to gl 229b , with colors in the range @xmath50.2 @xmath4 j - k@xmath6 @xmath4 0.2 . near - infrared spectra are correspondingly similar @xcite , likely due to the saturation of h@xmath7o and ch@xmath2 bands that dominate this wavelength regime . subtle differences in the magnitudes and shapes of h- and k - band flux peaks are observed , due to increased ch@xmath2 , h@xmath7o , and h@xmath7 collision - induced absorption ( cia ) toward cooler effective temperatures @xcite , and variations in the depths of near - infrared h@xmath7o and ch@xmath2 bands are discerned when compared to gl 229b @xcite . nonetheless , the similarity of the near - infrared spectra suggests that either the objects thus far identified are very similar in temperature , around 1000 k @xcite , or that near - infrared features are fairly insensitive to temperature , making the definition of a t dwarf spectral sequence in this wavelength regime a difficult proposition , at least at low resolution . we report the discovery of a t dwarf by 2mass which is unique among its counterparts , as it shows significant differences in its near - infrared features while retaining defining ch@xmath2 bands . this object , 2massi j0559191 - 140448 ( hereafter 2mass j0559 - 14 ) , is also 0.4 mag brighter than gl 229b and more than 1 mag brighter than the field t dwarfs discovered thus far . it is the first brown dwarf to be identified by the newly commissioned cornell massachusetts slit spectrograph ( * ? ? ? * hereafter cormass ) , mounted on the palomar 60-inch telescope . in @xmath82 we discuss the selection of 2mass j0559 - 14 from 2mass data and its spectral identification by cormass . in @xmath83 we discuss the observed spectral features and argue that 2mass j0559 - 14 is a warm t dwarf , possibly close to the transition temperature between l and t spectral classes . we discuss the brightness of this object and its role in future spectroscopic investigation of the t dwarf class in @xmath84 . 2mass j0559 - 14 was initially selected as a t dwarf candidate from the 2mass point - source working database . details on the selection criteria for 2mass t dwarfs are discussed in @xcite . using the palomar 60-inch infrared camera @xcite , we successfully re - imaged this candidate on 23 september 1999 ( ut ) at j - band , confirming it as a bona - fide candidate ( i.e. , not a minor planet or artifact ) . 2mass j0559 - 14 is the brightest 2mass t dwarf candidate confirmed to date , with j = 13.83@xmath00.03 ( table 1 ) ; it is also the reddest candidate confirmed , with j - k@xmath6 = 0.22@xmath00.06 . optical serc - ej @xcite and j - band 2mass images of the 2mass j0559 - 14 field are shown in figure 1 ; no optical counterpart is seen to b@xmath9 @xmath10 23 . low - resolution near - infrared spectral data of 2mass j0559 - 14 were obtained on 24 october 1999 ( ut ) using cormass . this newly commissioned instrument is an r @xmath10 300 prism cross - dispersed near - infrared spectrograph , with a 256 @xmath11 256 nicmos3 array and a 40 lines mm@xmath12 grating , blazed at 4.8 @xmath1 . cormass was designed primarily for the spectral classification of candidate low - mass objects color - selected from the 2mass database . the instrument s echelle format provides simultaneous coverage of the _ z_jhk bands , for 0.8 @xmath4 @xmath13 @xmath4 2.5 @xmath1 . the fixed slit has a width of 2@xmath14 and a length of 15@xmath14 . further details on this instrument can be found in @xcite . conditions during the observations were not photometric , and estimated seeing was @xmath10 1@xmath155 , with variable thin cirrus throughout the night . total on - source time was 2400 seconds divided into sets of 300-second integrations , nodding @xmath10 5@xmath14 along the slit between exposures . spectra were reduced using standard iraf routines . after correction for bad pixels , flat field and flux calibration images were corrected for nicmos3 reset - decay bias ( also known as shading ) as follows : a quadratic was fit to a row - by - row clipped median of the top quarter of the array , the portion unused by the spectrograph . the fit was extrapolated to 128 rows for the top two quadrants , duplicated for the bottom two quadrants , and subtracted row - by - row from all pixels . all images were flat - fielded with a pixel responsivity solution from the apflatten task using dome flats from all five nights of the run summed together . nodded image pairs for the science object were subtracted against each other to remove sky background and reset - decay bias . the apall task was used for spectral extraction . wavelength calibration was accomplished using spectral observations of the planetary nebula ngc 7027 obtained on 25 october 1999 ( ut ) . flux calibration was done by dividing by the reduced spectrum of the a2v standard hd 77281 @xcite , which was observed at similar airmass as 2mass j0559 - 14 and hand corrected for stellar h paschen and brackett recombination lines . the ratio was then multiplied by a 8810 k @xcite blackbody to complete the flux calibration . finally , all 300-second observations for each order were weighted by the spectra mean and combined with the scombine task using a trimmed average . orders were stitched together with scombine after hand deletion of noisy data at the ends of the orders . the spectrum of 2mass j0559 - 14 is shown in figure 2 , along with optical ( 0.87 - 1.0 @xmath1 ; burgasser et al . 2000b ) and near - infrared ( 1.0 - 2.35 @xmath1 ; strauss et al . 1999 ) data for sdssp j162414.37 + 002915.6 ( hereafter sdss 1624 + 00 ) . the combined sdss 1624 + 00 spectrum was smoothed to the resolution of cormass . spectra for both objects are normalized to one at 1.27 @xmath1 ( j - band peak ) . close up views of 0.88 - 1.01 and 1.15 - 1.345 @xmath1 are shown in figure 3 . table 2 summarizes the spectral features detected in 2mass j0559 - 14 , with identifications from @xcite , @xcite , @xcite , and @xcite . only major absorption bands of h@xmath7o and ch@xmath2 are tabulated . the characteristic ch@xmath2 bands at 1.6 and 2.2 @xmath1 are present , as are bands at 1.1 and 1.3 @xmath1 identified from laboratory data @xcite which are blended with h@xmath7o bands at the same wavelengths . an feh feature is seen at 0.9896 @xmath1 ( 0 - 0 band of a@xmath16@xmath17-x@xmath16@xmath17 ) which has also been identified in sdss 1624 + 00 @xcite . we do not detect the higher order 0 - 1 feh band at 1.191 @xmath1 , which is seen to weaken in the latest l dwarfs @xcite . two sets of k i doublets are noted at 1.1690 & 1.1773 @xmath1 ( 4p @xmath18p@xmath19 @xmath5 3d @xmath18d ) and 1.2432 & 1.2522 @xmath1 ( 4p @xmath18p@xmath19 @xmath5 5s @xmath18s ) , as is cs i at 0.8943 @xmath1 ( 6s @xmath18s@xmath20 @xmath5 6p @xmath18p@xmath20 ) . we do not detect the 2 - 0 x@xmath21@xmath22@xmath23-x@xmath21@xmath22@xmath23 band of co at 2.3 @xmath1 . comparison between 2mass j0559 - 14 and sdss 1624 + 00 reveals significant differences in spectral morphology . in figure 2 , it is apparent that the slope between 0.9 and 1.05 @xmath1 is shallower in 2mass j0559 - 14 , likely due to decreased absorption by the pressure - broadened k i doublet at 0.7665 and 0.7699 @xmath1 @xcite . ch@xmath2 and h@xmath7o features are generally weaker in 2mass j0559 - 14 , as noted by the significantly weakened 1.1 - 1.2 @xmath1 trough between @xmath24- and j - band peaks . the decreased ch@xmath2 opacity noticeably affects the shape of the j - band peak near 1.27 @xmath1 , as the weak ch@xmath2 wings at 1.24 and 1.30 @xmath1 carve out less flux on either side of the peak . in figure 2 , a significant flux offset is readily apparent at the base of the 1.6 @xmath1 ch@xmath2 band in 2mass j0559 - 14 , and relative enhancement of flux at both h- and k - bands in this object is almost certainly due to decreased h@xmath7 cia ( 1 - 0 quadrupole ) , h@xmath7o , and ch@xmath2 opacity . the weak ch@xmath2 bands seen in 2mass j0559 - 14 are unique among the current sample of t dwarfs , and the reduced opacity can be most readily explained if this object is warmer than other known t dwarfs . at higher effective temperatures , the dominant carbon - bearing species changes from co to ch@xmath2 at small optical depth , so that the ch@xmath2 column density will be less than that of cooler t dwarfs , and observed band strengths correspondingly weaker . increased thermal flux will also be seen at the base of these bands , particularly at 1.6 @xmath1 , which is unaffected by h@xmath7o absorption . the lower ch@xmath2 column density directly affects the h@xmath7o column density , via the reaction co + 3 h@xmath7 @xmath25 ch@xmath2 + h@xmath7o , leading to shallower bands at 1.1 and 1.45 @xmath1 . water can also be heated and dissociated by dust layers deep in the photosphere @xcite . finally , decreased h@xmath7 cia opacity at k - band , congruous with reduced ch@xmath2 and h@xmath7o opacity , will result in redder j - k@xmath6 colors with warmer t@xmath3 . these features are observed in 2mass j0559 - 14 , and its warm temperature is independently supported by the detection of the 0.9896 @xmath1 feh band , which is present but weakening in the latest l dwarfs @xcite . a similar argument has been made for sdss 1624 + 00 by @xcite , which was one of only three t dwarfs in that paper to show this feature . sdss 1624 + 00 has been shown to be a warm object via optical continuum measurements between broadened na i and k i features @xcite , while @xcite argue that this object is both warmer and dustier than gl 229b based on its shallower ch@xmath2 and h@xmath7o bands . by analogy , 2mass j0559 - 14 should be warmer still . the detection of excited k i lines at j - band , which are seen to weaken in the latest l dwarfs @xcite , is further evidence of the warmth of this object . the spectral features in 2mass j0559 - 14 suggest that it is close to the l / t transition temperature . the lack of co detection at 2.3 @xmath1 is not necessarily contradictory to this hypothesis , as overlying ch@xmath2 absorption beyond 2.2 @xmath1 may mask this weaker feature . naturally , metallicity , dust , and gravity could also play roles in the band strengths seen in 2mass j0559 - 14 ; however , temperature is likely to be the dominant determinant given the concordance of spectral features as discussed above . we can make a conservative t@xmath3 constraint for this object based on the temperature of gl 229b , which is clearly cooler , and a temperature estimate of the l8v companion dwarf gl 584c @xcite ; this translates into a range of 1000 @xmath4 t@xmath3 @xmath4 1300 k. parallax and bolometric luminosity measurements of this object would allow a direct determination of temperature . the relative brightness of 2mass j0559 - 14 as compared to other t dwarfs suggests that it may be a nearby brown dwarf . we can estimate its distance using simple scaling arguments based on gl 229b = 5.77@xmath00.04 pc @xcite , t@xmath3 = 960@xmath070 k @xcite , r @xmath26 r@xmath27 = 7.1 @xmath11 10@xmath28 cm @xcite , j = 14.32@xmath00.05 , l = ( 6.6@xmath00.6 ) @xmath11 10@xmath29 l@xmath30 , and bc@xmath9 = 2.2@xmath00.1 @xcite . ] . first , if we assume this object has the same intrinsic luminosity as gl 229b , we estimate its distance to be 4.6 pc . however , 2mass j0559 - 14 is probably a warmer object than gl 229b , so it should be more distant . an alternate estimate can be made if we adopt a radius r @xmath26 r@xmath31 and bounding t@xmath3 @xmath4 1300 k , so that l @xmath4 2.2 @xmath11 10@xmath32 l@xmath30 . using a gl 229b bolometric correction , we obtain m@xmath9 @xmath33 14.2 and thus @xmath34 @xmath4 8.4 pc . note , however , that an l8v has m@xmath9 = 15.0 @xcite , implying that our bc@xmath9 value may be too high ; indeed , bc@xmath9 may be only 1.3 for an l8v @xcite . adopting a smaller bc@xmath9 yields a smaller distance . therefore , barring multiplicity , 2mass j0559 - 14 is probably 5 - 8 pc distant , and likely falls within the 8 pc nearby star sample defined by @xcite . the brightness of this object allows substantial follow - up over a broad wavelength range , particularly for @xmath13 @xmath35 2.5 @xmath1 , where the fundamental absorption bands of h@xmath7o ( 2.7 @xmath1 ) , nh@xmath36 ( 3.0 @xmath1 ) , ch@xmath2 ( 3.3 @xmath1 ) , h@xmath7s ( 3.8 @xmath1 ) , and co ( 4.7 @xmath1 ) are found . the latter 1 - 0 x@xmath21@xmath22@xmath23-x@xmath21@xmath22@xmath23 band of co can aid in constraining its atmospheric abundance @xcite , essential in testing hypotheses of mixing @xcite and transparency @xcite in t dwarf atmospheres . deuterated molecules , such as ch@xmath36d , are of interest for study in the 3 - 5 @xmath1 range , as they yield information on the deuterium burning history of these brown dwarfs . mid - infrared wavelengths ( 8 - 14 @xmath1 ) are sensitive to vibration - rotation bands of alkali chlorides and sulfides , which are more abundant than their atomic alkali counterparts at low temperatures and high pressures @xcite and may serve as excellent temperature discriminants . this region also contains the strong fundamental @xmath37@xmath7 band of nh@xmath36 ( 10.5 @xmath1 ) and various silicate features . additionally , optical spectra shortward of 0.9 @xmath1 are critical in determining the behavior of the alkalis in cool brown dwarfs , particularly pressure - broadened na i ( 0.5890 & 0.5896 @xmath1 ) and k i ( 0.7665 & 0.7699 @xmath1 ) doublets , and cs i lines at 0.8521 and 0.8943 @xmath1 , which may also be used as temperature discriminants @xcite . while these features have been seen in t dwarfs such as sdss 1624 + 00 @xcite , detailed investigation of li i ( 0.6708 @xmath1 ) and rb i ( 0.7800 & 0.7948 @xmath1 ) lines have been hampered by the lack of detectable flux at these wavelengths . investigation in this spectral regime is currently underway . we thank m. strauss for the kind use of the sdss 1624 + 00 near - infrared spectrum and acknowledge useful discussions with c. griffith and m. marley . we thank our anonymous referee for helpful comments and suggestions . we also recognize the efforts of the 2mass staff and scientists in creating a truly incredible astronomical resource , and the expert assistance of the palomar observatory staff during imaging and spectroscopic observations . a. j. b. , j. d. k. , and j. e. g. acknowledge the support of the jet propulsion laboratory , california institute of technology , which is operated under contract with the national aeronautics and space administration . j. c. w. acknowledges support by nasa grant nag5 - 4376 . observations from palomar observatory were made as part of a continuing collaboration between the california institute of technology and cornell university . the digitized sky survey was produced at the space telescope science institute under us government grant nag w-2166 . serc - ej data were scanned by dss from photographic data obtained using the uk schmidt telescope , operated by the royal observatory edinburgh , with funding from the uk science and engineering research council . dss images were obtained from the canadian astronomy data centre , which is operated by the herzberg institute of astrophysics , national research council of canada . iraf is distributed by the national optical astronomy observatories , which are operated by the association of universities for research in astronomy , inc . , under cooperative agreement with the national science foundation . this publication makes use of data from the two micron all sky survey , which is a joint project of the university of massachusetts and the infrared processing and analysis center , funded by the national aeronautics and space administration and the national science foundation . arnouts , s. , dodorico , s. , cristiani , s. , zaggia , s. , fontana , a. , & giallongo , e. , , 341 , 641 auman , j. , jr . 1967 , , 14 , 171 basri , g. , mohanty , s. , allard , f. , hauschildt , p. h. , delfosse , x. , martn , e. l. , forveille , t. , & goldman , b. 2000 , , in press burgasser , a. j. , et al . 2000a , , 531 , l57 burgasser , a. j. , kirkpatrick , j. d. , reid , i. n. , liebert , j. , gizis , j. e. , & brown , m. e. 2000b , , 120 , in press burgasser , a. j. , et al . 1999 , , 522 , l65 burrows , a. , marley , m. s. , & sharp , c. m. 2000 , , 531 , 438 burrows , a. , & sharp , c. m. 1999 , , 512 , 843 burrows , a. , & liebert , j. 1993 , rev.mod 65 , 301 cuby , j. g. , saracco , p. , moorwood , a. f. m. , dodorico , s. , lidman , c. , comern , f. , & spyromilio , j. 1999 , , 349 , l41 danielson , r. e. 1966 , , 143 , 949 elias , j. h. , frogel , j. a. , matthews , k. , & neugebauer , g. 1982 , , 87 , 1029 fegley , b. , jr . , & lodders , k. 1996 , , 472 , l37 fink , u. , & larson , h. p. 1979 , , 233 , 1021 griffith , c. a. , & yelle , r. v. 1999 , , 519 , l85 gunn , j. e. , & weinberg , d. h. 1995 , in wide - 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( washington , d. c. : gpo ) wilson , j. c. , et al . 2000 , , in preparation cs i & 0.8943 & 6s @xmath18s@xmath20 @xmath5 6p @xmath18p@xmath20 & @xcite + k i & broadened up to @xmath10 0.9 & 4s @xmath18s@xmath20 @xmath5 4p @xmath18p@xmath38 & @xcite + h@xmath7o & 0.925 - 0.95 & @xmath37@xmath7 = 0 , @xmath37@xmath39 + @xmath37@xmath36 = 3 & @xcite + h@xmath7o & 0.95 - 0.985 & @xmath37@xmath7 = 2 , @xmath37@xmath39 + @xmath37@xmath36 = 2 & @xcite + feh & 0.9896 & 0 - 0 band of a@xmath16@xmath17-x@xmath16@xmath17 & @xcite + h@xmath7o & 1.07 - 1.11 & @xmath37@xmath7 = -1 , @xmath37@xmath39 + @xmath37@xmath36 = 3 & @xcite + ch@xmath2 & 1.1 - 1.24 & 3@xmath37@xmath36 & @xcite + h@xmath7o & 1.11 - 1.16 & @xmath37@xmath7 = 1 , @xmath37@xmath39 + @xmath37@xmath36 = 2 & @xcite + h@xmath7o & 1.16 - 1.23 & @xmath37@xmath7 = 3 , @xmath37@xmath39 + @xmath37@xmath36 = 1 & @xcite + k i & 1.1690 & 4p @xmath18p@xmath19 @xmath5 3d @xmath18d & @xcite + k i & 1.1773 & 4p @xmath18p@xmath19 @xmath5 3d @xmath18d & @xcite + k i & 1.2432 & 4p @xmath18p@xmath19 @xmath5 5s @xmath18s & @xcite + k i & 1.2522 & 4p @xmath18p@xmath19 @xmath5 5s @xmath18s & @xcite + ch@xmath2 & 1.3 - 1.5 & @xmath37@xmath7 + 2@xmath37@xmath36 & @xcite + h@xmath7o & 1.33 - 1.43 & @xmath37@xmath7 = 0 , @xmath37@xmath39 + @xmath37@xmath36 = 2 & @xcite + h@xmath7o & 1.43 - 1.52 & @xmath37@xmath7 = 2 , @xmath37@xmath39 + @xmath37@xmath36 = 1 & @xcite + ch@xmath2 & 1.6 - 1.8 & 2@xmath37@xmath36 & @xcite + h@xmath7o & 1.71 - 1.80 & @xmath37@xmath7 = -1 , @xmath37@xmath39 + @xmath37@xmath36 = 2 & @xcite + h@xmath7o & 1.80 - 2.08 & @xmath37@xmath7 = 1 , @xmath37@xmath39 + @xmath37@xmath36 = 1 & @xcite + ch@xmath2 & 2.2 - 2.6 & @xmath37@xmath7 + @xmath37@xmath36 & @xcite + h@xmath7 & centered at 2.4 & 1 - 0 quadrupole ( cia ) & @xcite +

we report the discovery of a bright ( j = 13.83@xmath00.03 ) methane brown dwarf , or t dwarf , by the two micron all sky survey . this object , 2massi j0559191 - 140448 , is the first brown dwarf identified by the newly commissioned cormass instrument mounted on the palomar 60-inch telescope . near - infrared spectra from 0.9 - 2.35 @xmath1 show characteristic ch@xmath2 bands at 1.1 , 1.3 , 1.6 , and 2.2 @xmath1 , which are significantly shallower than those seen in other t dwarfs discovered to date . coupled with the detection of an feh band at 0.9896 and two sets of k i doublets at j - band , we propose that 2mass j0559 - 14 is a warm t dwarf , close to the transition between l and t spectral classes . the brightness of this object makes it a good candidate for detailed investigation over a broad wavelength regime and at higher resolution .

recent successful preparation of a single layer of graphene has generated a lot of interest in this system as experimental and theoretical studies have shown that the nature of quasiparticles in this two - dimensional system is very different from those of conventional two - dimensional electron gas ( 2deg ) systems realized in semiconductor heterostructures . graphene has a honeycomb lattice of carbon atoms . the quasiparticles in graphene have a band structure in which electron and hole bands touch at two points in the brillouin zone . at these dirac points the quasiparticles obey the massless dirac equation . in other words , they behave as massless , chiral dirac fermions leading to a linear dispersion relation @xmath1 ( with the characteristic velocity @xmath2 . this difference in the nature of the quasiparticles in graphene from a conventional 2deg has given rise to a host of new and unusual phenomena such as the anomalous quantum hall effect@xcite with profound effects on transport in these systems . the transport properties of graphene are currently being explored in the presence of nonuniform potentials , such as in @xmath3 junctions@xcite , as well as in periodic potentials . effects of periodic potential on electron transport in 2d electron systems has been the subject of continued interest , where electrical modulation of the 2d system can be carried out by depositing an array of parallel metallic strips on the surface or through two interfering laser beams@xcite . more recently in graphene , electrostatic@xcite and magnetic@xcite periodic potentials have been shown to modulate its electronic structure in unique ways leading to fascinating physics and possible applications . periodic potentials are induced in graphene by interaction with a substrate@xcite or controlled adatom deposition@xcite . in addition , it was shown that periodic ripples in suspended graphene also induces a periodic potential in a perpendicular electric field@xcite . epitaxial growth of graphene on top of a prepatterned substrate is also a possible route to modulation of the potential seen by the electrons . in this work , we complement these recent studies to discuss the effects of a weak electric modulation on the electrical conductivity in a graphene monolayer subjected to an external magnetic field perpendicular to the graphene plane . electric modulation introduces a new length scale , period of modulation , in the system giving rise to interesting physical effects on the transport response . commensurabiliy ( weiss ) oscillations , in addition to shubnikov de hass ( sdh ) oscillations , are found to occur as a result of commensurability of the electron cyclotron diameter at the fermi energy and the period of the electric modulation . in @xcite , on the same subject , diffusive contribution to magnetoconductivity was considered whereas in the present work we determine collisional and hall contibutions as well . this makes this paper a complete study of electric modulation induced effects on electrical conductivities / resistivities in a graphene monolayer in the presence of a magnetic field . in the next section , we present the formulation of the problem and derive expressions for electrical conductivities in a graphene monolayer . in section iii , results of numerical work are presented and discussed , followed by the conclusions in section iv . we consider a graphene sheet in the @xmath4 plane . the magnectic field @xmath5 is applied along the @xmath6 direction . the system is also subjected to a 1d weak periodic modulation @xmath7 in the @xmath8 direction . the one electron hamiltonian reads@xmath9 where @xmath10 is the momentum operator , @xmath11 are pauli matrices and @xmath12 characterizes the electron velocity in graphene . in the absence of modulation , i.e. for @xmath13 and for the vector potential chosen in the landau guage @xmath14 , the normalized eigenfunctions of eq . ( [ 1 ] ) are given by @xmath15 where @xmath16 and @xmath17 are the harmonic oscillator wavefunctions centred at @xmath18 . @xmath19 is the landau level index , @xmath20 the magnetic length and @xmath21 the length of 2d graphene system in the @xmath22 direction . the corresponding eigenvalue is @xmath23 where @xmath24 . the modulation potential is approximated by the first fourier component of the periodic potential @xmath25 where @xmath26 , @xmath27 is the period of modulation and @xmath28 is the constant modulation amplitude . this potential lifts the degeneracy of landau levels ( lls ) and the energy becomes dependent on the position@xmath29 of the guiding centre . thus energy eigenvalues for weak modulation ( @xmath30 ) , using first order perturbation theory , are@xmath31 where @xmath32 $ ] with @xmath33 , @xmath34 the laguerre polynomials and @xmath35 . we note that the electric modulation induced broadening of the energy spectrum is nonuniform . the landau bandwidth @xmath36 oscillates as a function of @xmath19 since @xmath33 are oscillatory functions of index @xmath19 . @xmath37 at the fermi energy can be approximated , using an asymptotic expression for @xmath38 appropriate for low magnetic - field range relevant to the present study , as @xmath39 where @xmath40 is the classical cyclotron orbit , @xmath41 and @xmath42 is the electron number density . the above expression shows that @xmath43 oscillates with @xmath44 through @xmath45 and the width of landau bands @xmath46 becomes maximum at@xmath47 and vanishes at@xmath48 which is termed the flat band condition . the oscillations of the landau bandwith is the origin of the commensurability ( weiss ) oscillations and , at the same time , are responsible for the modulation of the amplitude and the phase of the shubnikov - de hass ( sdh ) oscillations . to calculate the electrical conductivity in the presence of weak modulation we use kubo formula @xcite . the diffusive contribution to conductivity which arises due to the scattering induced migration of the larmor circle center has already been determined for a graphene monolayer in @xcite . our focus , in this work , will be the calculation of the collisional contribution to the conductivity and the the hall conductivity . to obtain collisional contribution to conductivity , we assume that electrons are elastically scattered by randomly distributed charge impurities as it has been shown that charged impurities play a key role in the transport properties of graphene near the dirac point@xcite . this type of scattering is dominant at low temperature . the collisional conductivity when spin degeneracy is considered is given by @xcite@xmath49 where @xmath50^{-1}$ ] is the fermi dirac distribution function with @xmath51 @xmath52 for elastic scattering , @xmath53 is the boltzmann constant and @xmath54 the chemical potential . @xmath55 is the transmission rate between the one - electron states @xmath56 and @xmath57 , @xmath58 the volume of the system , @xmath59 the electron charge , @xmath60 the relaxation time and @xmath61 @xmath56 the mean value of the @xmath62 component of the position operator when the electron is in state @xmath63 . collisional conductivity arises as a result of migration of the cyclotron orbit due to scattering by charge impurities . the scattering rate @xmath64 is given by@xmath65 the fourier transform of the screened impurity potential is @xmath66 where @xmath67 and @xmath68 are the position of electron and of impurity respectively ; @xmath69 is the screening wave vector , @xmath70 is the dielectric constant of the material . by performing an average over random distribution of impurities , ( @xmath71 impurity density ) , the contribution of the unperturbed part of the wavefunction,@xmath72 , to the scattering rate is@xmath73 with@xmath74 \delta _ { k_{y}-k_{y}^{\prime},q_{y } } \label{9}\ ] ] and@xmath75 ^{2};n^{\prime}\leq n. \label{10}\ ] ] here @xmath76 is the area of the graphene monolayer and @xmath77 with @xmath78 . inserting eq . ( [ 8 ] ) in eq . ( [ 6 ] ) we obtain@xmath79 ^{2}q_{y}f_{n , k_{y}}(1-f_{n , k_{y}})\delta(e_{n , k_{y}}-e_{n^{\prime},k_{y } } ) \label{11}\ ] ] with @xmath80 , the fermi dirac distribution function . taking @xmath81 and @xmath82 , @xmath83 in eq . ( [ 11]),we obtain@xmath84 ^{2}d\gamma\delta(e_{n , k_{y}}-e_{n^{\prime},k_{y } } ) . \label{12}\ ] ] using the following integral identity @xcite:@xmath85 ^{2}d\gamma=\overset{\infty}{\underset{0}{\int}}\gamma e^{-\gamma}\left [ l_{n}(\gamma)\right ] ^{2}d\gamma=(2n+1 ) \label{13}\ ] ] where for @xmath86 , @xmath87 ^{2}=e^{-\gamma}\left [ l_{n}(\gamma)\right ] ^{2}$ ] with the result@xmath88 ^{2}d\gamma=\overset{\infty}{\underset{0}{\int}}\gamma e^{-\gamma}\left [ l_{n-1}(\gamma)\right ] ^{2}d\gamma=(2n-1 ) \label{14}\]]@xmath89 \left [ l_{n-1}(\gamma)\right ] d\gamma=0 . \label{15}\ ] ] finally , replacing the @xmath90 function by a lorentzian of zero shift and constant width @xmath91 , @xmath92 , @xmath93 and performing the sum on @xmath94 , keeping only the dominant term @xmath95 in eq . ( [ 12 ] ) , we obtain the following result@xmath96 for completeness , we also present the result for diffusive conductivity which was determined in@xcite,@xmath97_{_{e = e_{n}}}[l_{n}(u)-l_{n-1}(u)]^{2 } \label{17a}\ ] ] where @xmath98 is the constant scattering time and @xmath99^{2}$ ] . now @xmath100 . the nondiagonal contribution to conductivity @xcite is given by@xmath101 since @xmath102 and @xmath103 we obtain@xmath104 since the @xmath62 and @xmath22 components of velocity operator are @xmath105 and @xmath106 when @xmath107 . therefore , @xmath108 and @xmath109 . hence@xmath110 and@xmath111 substituting the values of the matrix elements of velocity in eq . ( [ 18 ] ) yields@xmath112 since @xmath113 where @xmath23 and @xmath114 $ ] we obtain@xmath115 ^{2 } \label{22}\ ] ] where@xmath116 substituting eq . ( [ 22 ] ) in eq . ( [ 21 ] ) we obtain the hall conductivity in graphene as@xmath117 ^{2 } } \label{24}\ ] ] elements of the resistivity tensor @xmath118(@xmath54,@xmath119=@xmath62,@xmath22 ) can be determined from those of the conductivity tensor @xmath120 , obtained above , using the expressions : @xmath121 @xmath122 @xmath123 , @xmath124 @xmath125 @xmath123 and @xmath126 @xmath127 @xmath123 where @xmath128 @xmath125 @xmath129 @xmath130 @xmath131 with @xmath132 @xmath133 . the above expressions for the ( collisional , diffusive and hall ) conductivities , eqs . ( [ 16 ] ) , ( 17 ) and ( [ 24 ] ) are the principal results of this work . the integrals appearing in these equations are evaluated numerically and the results are presented in figure ( 1a ) at temperature @xmath134 @xmath135 for a graphene monolayer with electron density @xmath136 , electric modulation strength @xmath137 with period @xmath138 . in addition , the following parameters were employed @xcite : @xmath139 @xmath140 , @xmath141 , impurity density @xmath142 and @xmath143 ( using sio@xmath144 as the substrate material ) . we observe that sdh oscillations are visible in collisional conductivity @xmath125 whereas the hall conductivity @xmath131 decreases with increasing magnetic field , @xmath0 . furthermore , weiss oscillations superimposed on sdh oscillations are seen in @xmath145 to highlight the effects of modulation , we also calculate the correction to the conductivity ( change in conductivity ) as a result of modulation which is expressed as @xmath146 and is shown in figure ( 1b ) . electric modulation acting on the system results in a positive contribution to @xmath147 and a negative contribution to @xmath148whereas @xmath149 oscillates around zero . we find that @xmath150 , which is a consequence of the fact that @xmath151 has only collisional contribution , while @xmath147 , in addition to the collisional part , has contributions due to band conduction which are much larger . it is also seen that the oscillations in @xmath151 and @xmath147 are @xmath152 out of phase . to determine the effects of temperature on magnetoconductivities , comparison of conductivities and corrections to the conductivities at two different temperatures @xmath153 ( solid curve ) and @xmath154 ( broken curve ) are presented in figures ( 2 ) and ( 3 ) respectively . @xmath151 shows strong temperature dependence which is a clear signature that sdh oscillations are dominant here . oscillations in @xmath147 show comparitively weaker dependence on temperature as weiss oscillations , that are weakly dependent on temperature , play a more significant role in @xmath145 furthermore , weiss oscillations are also seen in @xmath149 and they are weakly sensitive to temperature a low magnetic fields ( that is when @xmath155 ) . in graphene system , the value of @xmath0 defining the boundary between sdh and weiss oscillations is quite low ( it lies between @xmath156 and @xmath157 ) . for smaller values of @xmath44 the amplitude of weiss oscillations remain essentially the same at various temperatures . when @xmath0 is large , sdh oscillations dominate and the amplitude of oscillations gets reduced considerably at comparatively higher temperatures . however , oscillatory phenomenon still persists . it can be seen from figure ( 1a ) , ( 2a ) and ( 2b ) that amplitude of sdh oscillations remains large at those values of the magnetic field where the flat band condition is satisfied i.e at @xmath158 when @xmath159 in eq.([5 ] ) while is supressed at the maximum bandwidth / broad band condition , i.e at @xmath160 for @xmath161 in eq.([4 ] ) . furthermore , zeros in @xmath162 appear in close agreement with values predicted from the flat band condition . the amplitude of @xmath151 and @xmath147 becomes maximum at the broad band condition(as seen in figure ( 3 ) ) , whereas the amplitude of @xmath149 crosses the zero level at the broad band conditon and than a phase change of amplitude occurs . components of the resistivity tensor @xmath118 have also been computed and shown in figure ( 4a ) as a function of @xmath0 for @xmath153 ( solid curve ) and @xmath163 ( broken curve ) respectively . the correction ( change ) in @xmath118 due to the modulation is shown in figure ( 4b ) . to verify our results , we compare them in the absence of modulation with the unmodulated experimental results presented in @xcite . in order to carry this out , we note that the number density @xmath164is related to the gate voltage ( @xmath165 ) through the relationship @xcite@xmath166 , where @xmath167 and @xmath168 are the permitivities for free space and the dielectric constant of graphene , respectively . @xmath59 is the electron charge and @xmath169 the thickness of the sample . it yields @xmath170 for @xmath171 . we find that the results for magnetoresistivities obtained in this work are in good agreement with the values given in reference @xcite for the unmodulated case at @xmath170 . we observe in figure ( 4 ) , that the dominant effect of weiss oscillations appears in @xmath172 as it is proportional to @xmath122 whereas the amplitude of oscillations in @xmath173 show a monotonic increase in ampitude with magnetic field signifying dominance of sdh in @xmath174 in figure ( 5 ) , we observe that the oscillations in @xmath175 and @xmath176 are out of phase and the amplitude of the oscillation in @xmath175 is greater than the amplitude of oscillation in @xmath177 . the out of phase character of the oscillations can be understood by realizing that the conduction along the modulation direction , which contributes to @xmath178 occurs due to hopping between landau states and it is minimum when the density of states at the fermi level is minimum . oscillations in @xmath172 are much larger than those in @xmath173 as a new mechanism of conduction due to modulation contributes to @xmath172 . to highlight temperature effects on the modulated system , we present in figure ( 6 ) , corrections to magnetoresistivities at two different temperatures ( @xmath179 , solid curve and @xmath163 , broken curve ) . these results exhibit sdh oscillation when @xmath0 becomes greater than @xmath180 as seen in figures ( 5 ) and ( 6 ) . the weiss oscillations in @xmath175 are in phase with those of @xmath181 . from figure ( 5c ) one might infer that hall resistivity is not affected by modulation . this is not so , as even hall resistivity carries modulation effects and that is seen if we draw the slope of @xmath182 as a function of magnetic field ( figure ( 7 ) ) . in order to quantatively analyze the results presented in the figures we consider the density of states ( dos ) of this system . at finite temperature , the oscillatory part of resistivities ( @xmath183 ) are proportional to the oscillatory part of the density of states ( dos ) at the fermi energy , @xmath184 where @xmath185 @xmath186 is the dos and @xmath187 is resistivity in the absence of magnetic field , respectively@xcite . for not too small magnetic fields ( @xmath188 ) , @xmath189 to a good approximation , where @xmath190 represents conductivity at zero magnetic field and @xmath98 is the relaxation time . the analytic expression for the density of states ( dos ) of a graphene monolayer in the presence of a magnetic field subjected to electric modulation has been derived in the appendix . the dos at energy @xmath191 is given as@xmath192dt\exp(-2\pi k\eta)\right ] \label{25}\\ & = d_{o}\left [ 1 + 2\underset{k=1}{\overset{\infty}{\sum}}\cos(2\pi k\varepsilon)j_{o}(2\pi kv_{b})\exp(-2\pi k\eta)\right ] \nonumber\end{aligned}\ ] ] where @xmath193 , @xmath194 and @xmath195 @xmath196 is the bessel function of order zero . since @xmath197 for weak magnetic fields , it is usually a good approximation to keep only the @xmath198 term in the sum : @xmath199 with@xmath200 to determine the effects of an external magnetic field on the conductivities / resistivities of the system we consider eq.(26 ) . with a decrease in @xmath0 , @xmath201 oscillates periodically with respect to @xmath202 around @xmath203 , increasing its amplitude proportionaly to @xmath204 [ eq . ( [ 3 ] ) ] . the function @xmath205 decreases from @xmath206 with an increase of @xmath207 and than changes its sign . therefore the oscillations of @xmath208 takes a minimum amplitude at the maximum bandwith conditions while @xmath209 stays less than @xmath210 ; it disappears when a maximum of @xmath209 touches at @xmath211 ; it reappears with an inverted sign for @xmath209 larger than @xmath210 . therefore , if we assume that @xmath212 $ ] @xmath213 holds , we can find the position where oscillations of @xmath212 $ ] vanish . that occurs at @xmath214 . we can also find the period of oscillations in conductivities / resistivities from eq . ( [ 25 ] ) as follows . we have @xmath215 . since @xmath216 . the period of oscillation can be estimated by equating the increment of the cosine argument with @xmath217,@xmath218 which leads to@xmath219 in our work ( @xmath220 and @xmath138 ) , therefore the period of oscillations comes out to be 1.933@xmath221 @xmath222 which is in good agreement with the results shown in the figures . damping of these oscillations with temperature can also be discussed . in ref . @xcite , the temperature scale for damping of weiss oscillations is given by @xmath223 where @xmath224 and @xmath225 whence the result@xmath226 to determine the damping temperature for sdh oscillations we , following ref.@xcite and @xcite , use asymptotic expression for magnetoconductivity . for this , we use dos ( eq . [ 25]),@xmath227 . \label{28b1}\ ] ] in the asymptotic limit of weak magnetic fields when many filled landau levels occur , we take @xmath228 @xmath229 and replace @xmath230 by @xmath231 and inserting the continuum approximation @xmath232 in eq . [ 17a ] , we obtain the following result@xmath233 \label{28b2}\ ] ] where @xmath234 $ ] is the contribution of weiss oscillations and @xmath235/\sinh[4\pi^{2}e_{f}k_{b}t/(\hbar\omega_{g})^{2}]$ ] is the amplitude of the sdh oscillations . therefore , the characteristic temperature of sdh oscillations is given by@xmath236 the amplitude of oscillations is given by @xmath237 , where @xmath238 . the amplitude of weiss oscillations at @xmath239 are @xmath240 and @xmath241 at @xmath153 and @xmath154 , respectively the corresponding amplitudes for sdh oscillations are @xmath242 and @xmath243 . the sdh amplitude decreases by @xmath244 percent whereas the amplitude of weiss ocillations decreases by @xmath245 percent for @xmath246 change in temperature . in figures ( 2 ) , ( 3 ) , ( 5 ) and ( 6 ) ; the sdh amplitude decreases by @xmath247 percent when temperature is changed from @xmath153 to @xmath154 , and it is in good agreement with the results obtained from eqs . ( [ 28a ] ) and ( [ 28b ] ) . it is due to the fact @xmath248 that the weiss oscillations are more robust against temperatue changes . finally , we compare the results obtained for the conductivity/ resistivity of graphene with those of a 2deg given in @xcite . the characteristic damping temperatures for weiss and sdh oscillations in 2deg are @xmath249 and @xmath250 respectively . in contrast , the corresponding damping temperatures in graphene are given by eqs ( 30 ) and ( 33 ) . on comparing the two temperature scales , we find that the damping temperatures of both oscillations in graphene are higher than that of a 2deg . the ratio is found to be @xmath251 ; where @xmath252 is the electron mass in a 2deg and @xmath253 is the critical temperature of a 2deg ; which implies that a comparatively higher temperature is required for damping of oscillations in graphene . this is due to the higher fermi velocity of dirac electrons in graphene compared to standard electrons in a 2deg systems . it is evident from the numerical results that both , sdh and weiss - type oscillations , are more enhanced and more robust against temperature in graphene . to conclude , we have investigated the effects of a weak periodic electric modulation on the conductivity of a graphene monolayer subjected to a perpendicular magnetic field . as a result of modulation a new length scale , period of modulation , enters the system leading to commensurability oscillations in the diffusive , collisional and hall contributions to conductivities / resistivities . these modulation induced effects on graphene magnetotransport are discussed in detail in this work . here we derive the expression for the density of states , eq . ( [ 25 ] ) in the text . we consider monolayer graphene subjected to a uniform quantizing magnetic field @xmath254 in the presence of an additional weak periodic modulation potential . the energy spectrum in the quasi classical approximation , i.e. when many landau bands are filled may be written as@xmath255 where @xmath32 $ ] with @xmath33 , @xmath34 the laguerre polynomials and @xmath35 . for large @xmath256 @xmath257 and @xmath258 . using the asymptotic expression for the laguerre polynomials@xcite ; @xmath259 and taking the continuum limit @xmath260 , where @xmath261 we get @xmath262@xmath263 to obtain a more general result which will lead to the result that we require as a limiting case we consider impurity broadened landau levels . the self energy may be expressed as@xmath264 which yields@xmath265 @xmath266 is the broadening of the levels due to the presence of impurities . the density of states is related to the self energy through @xmath267 . \label{33}\ ] ] the residue theorem has been used to sum the series@xmath268sumof residues of @xmath269at all poles of @xmath270@xcite . here @xmath271 with @xmath272 , @xmath273 and @xmath274 . the function @xmath275 has a pole at @xmath276 and the residue of ( @xmath269 ) at the pole is @xmath277 . hence @xmath278 and we obtain@xmath279@xmath280\right ) .\ ] ] separating @xmath281 into real and imaginary parts @xmath282 eq . ( [ 34 ] ) takes the form@xmath283 where@xmath284 \label{37}\]]@xmath285@xmath286 = \frac{2\pi\gamma_{o}^{2}e}{(\hbar\omega_{g})^{2}}{\displaystyle\int\limits_{0}^{a } } \frac{dx_{o}}{a}\frac{\sinh2v}{\cosh2v-\cos2u}=\frac{2\pi\gamma_{o}^{2}e}{(\hbar\omega_{g})^{2}}{\displaystyle\int\limits_{0}^{a } } \frac{dx_{o}}{a}(1 + 2\underset{k=1}{\overset{\infty}{\sum}}\cos(2ku)\exp(-2kv ) . \label{39}\ ] ] if we define dimensionless variables @xmath287 , @xmath288 and @xmath289 the density of states is obtained as@xmath290\exp(-2\pi k\eta)\ } \label{40}\ ] ] where @xmath291 . let @xmath292 in the above expression results in @xmath293dt\exp(-2\pi k\eta)\}. \label{41}\ ] ] solving the integeral yields@xmath294 y. zheng and t. ando , phys . rev . b * 65 * , 245420 ( 2002 ) ; v. p. gusynin and s. g. sharapov , phys . rev . lett . * 95 * , 146801 ( 2005 ) ; n. m. r. perez et . b _ _ * 73 * , 125411 ( 2006 ) ; m. i. katsnelson _ et.al_ , nat . phys . * 2 * , 620 ( 2006 ) ; k. s. novoselov _ et al._,nat . phys . * 2 * , 177 ( 2006 ) b. huard _ et al . _ , lett . * 98 * , 236803 ( 2007 ) ; b. ozyilmaz _ et al . _ , lett . * 99 * , 166804 ( 2007 ) ; j. r. williams , l.di carlo , and c. m. marcus , science * 317 * , 638 ( 2007 ) ; a. f. young and p. kim , nature phys . 5 , 222 ( 2009 ) ; n. stander _ et al . lett__. _ _ * 102 * , 026807 ( 2009 ) . d. weiss , k. v. klitzing , k. ploog , and g. weimann _ _ , _ _ europhys . lett . , * 8 * , 179 ( 1989 ) ; r. w. winkler , j. p. kotthaus , and k. ploog , _ _ phys . rev . lett . * 62 * , 1177 ( 1989 ) ; r. r. gerhardts , d. weiss , and k. v. klitzing , _ _ phys . lett . * 62 * , 1173 ( 1989 ) ; f. m. peeters and p. vasilopoulos , phys . b * 47 * , 1466 ( 1993 ) ; ( b ) j. shi and f. m. peeters , k. w. edmonds and b. l. gallagher , phys . rev . b * 66 * , 035328 ( 2002 ) ; ( c ) p. vasilopoulos , f. m. peeters , superlattices and microstructures * 7 * , 393 ( 1990 ) ; ( d ) f. m. peeters and a. matulis , phys . rev . b * 48 * , 15166 ( 1993 ) ; ( e ) d. p. xue and g. xiao , phys . rev . b * 45 * , 5986 ( 1992 ) ; ( f ) p. de ye , d. weiss , r. r. gerhardts , m. seeger , k. v. klitzing , _ _ k. eberl and h. nickel , phys . lett . * 74 * , 3013 ( 1995 ) ; ( g ) j. h. ho , y. h. lai , y. h. chui and m. f. lin , nanotechnology * 19 * , 035712 ( 2008 ) . c. bai and x. zhang , phys . b * 76 * , 075430 ( 2007 ) ; m. tahir , k.sabeeh and a. mackinnon , j. phys.:condens . matter * 19 , * 406226 ( 2007 ) ; c. -h park _ et.al_ , nat . * 4 * , 213 ( 2008 ) ; m. barbier , f. m. peeters , p. vasilopoulos , j. m. pereira , phys . rev . b * 77 * , 115446 ( 2008 ) ; c. -h park _ et.al_ , nano lett . 8 , 2920 ( 2008 ) ; c. -h park _ et.al_ , phys . rev * 101 * , 126804 ( 2008 ) ; l.brey and h. a. fertig , phys . lett . * 103 * , 046809 ( 2009 ) ; l.brey and h. a. fertig , phys . lett . * 103 * , 046809 ( 2009 ) ; c. -h park _ et.al_ , phys lett . * 103 * , 046808 ( 2009 ) ; m. tahir and k.sabeeh , phys . b * 77 * , 195421 ( 2008 ) ; m. ramzanimasir , p. vasilopoulos , and f. m. peeters , phys . rev . b * 79 * , 035409 ( 2009 ) , l. dell anna and a. demartino , phys . rev . b * 79 * , 045420 ( 2009 ) ; s. ghosh and m. sharma , j. phys.:condens . matter * 21 , * 292204 ( 2009 ) ; i. snyman , phys . b * 80 * , 054303 ( 2009 ) . l.l . moseley and t. lukes , _ am j.phy_. * 46 * , 6 ( 1978 ) ; f. m. peeters and p. vasilopoulos , phys b * 46 * , 4667 ( 1992 ) ; p.vasilopoulous and f.m . peeters , phys . lett . * 63 * , 19 ( 1989 ) ; m. charbonneau _ _ k. m. van vliet and p. vasilopoulos , _ _ j. math * 23 * , 318 ( 1982 ) .

we have performed a detailed investigation of the electrical properties of a graphene monolayer which is modulated by a weak one dimensional periodic potential in the presence of a perpendicular magnetic field . the periodic modulation broadens the landau levels into bands which oscillate with @xmath0 . the electronic conduction in this system can take place through either diffusive scattering or collisional scattering off impurities . both these contributions to electronic transport are taken into account in this work . in addition to the appearance of commensurability oscillations in both the collisional and diffusive contributions , we find that hall resistance also exhibits commensurability oscillations . furthermore , the period and amplitude of these commensurability oscillations in the transport parameters and how they are affected by temperature are also discussed in this work .

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In his unorthodox campaign for the Republican nomination for president, Mr. Trump has portrayed himself as a teller of difficult truths, whose wealth unburdens him from the careful pronouncements of ordinary candidates. “Politicians,” he has said, “are all talk.” Hundreds of pages of sworn testimony by Mr. Trump over the past decade show something less flattering. Some of his claims, made under oath, and under pressure, are shown to be hyperbolic overstatements, and others to be shadings of the truth or even outright misstatements. And in rare instances, he turns boorish and demeaning. The testimony, drawn from a series of lawsuits since 2007, reveals much about the personal preoccupations and business tactics of the developer-turned-candidate. It showcases Mr. Trump’s fixation with his image as a financial success, and lays bare his hypersensitivity to any suggestion of failure. It chronicles his methodical cultivation — and elbows-out defense — of a brand name he has licensed around the world for millions of dollars in fees; and it at times displays a lack of sympathy for ordinary consumers who have lost money on the purchase of Trump-branded products. In the Beck deposition, he said that home buyers who had forfeited their down payments in a building bearing his name were “very lucky” that the project failed because, he asserted, they would have lost more had the project proceeded after the financial crisis of 2008. Advertisement Continue reading the main story “Congratulate your clients,” Mr. Trump told Ms. Beck and her husband and co-counsel, Jared Beck, whose clients had alleged that they lost tens of thousands of dollars each. A lawyer for Mr. Trump, Alan Garten, said the depositions showed that “Mr. Trump, unlike the other candidates (all of whom are career politicians), is a determined businessman who stands up for what he believes, speaks his mind and talks from the heart.” Above all, the testimony suggests that Mr. Trump’s relationship with the truth can be tenuous — especially when it involves claims about his business. “Have you ever exaggerated in statements about your properties?” one lawyer asked him. “I think everyone does,” Mr. Trump replied. “Does that mean that sometimes you’ll inflate the value of your properties in your statements?” the lawyer tried a moment later. “Not beyond reason,” he answered. Case by case, lawyers deposing Mr. Trump examined his public statements. Advertisement Continue reading the main story Was he the developer of Trump-branded condominium towers in Tampa and Fort Lauderdale, Fla., and in Mexico, as marketing materials led some buyers to believe? Nope. (“I’m a builder in New York,” he said. “Generally, when I venture outside of New York, I do a form of a license.”) Was he really paid $1 million for a 2005 speech, as he had boasted on television? He was not. (It was $400,000; in testimony, he said he counted efforts to promote the talk as a form of payment.) Did his debts ever reach $9 billion in the 1990s, as he said in two of his books to dramatize his eventual financial comeback? They did not. (“That is a mistake,” Mr. Trump said, “and I don’t know how it got there.”) But, he said, it hardly mattered. “Frankly, whether it’s $9 billion or $3.6 billion,” Mr. Trump said, “I don’t think makes any difference to anybody if they hear the story.” In words that echo now that he is a candidate, Mr. Trump compared his own inclination toward blurring the facts to a strategy he learned from America’s elected officials. “I’m no different from a politician running for office,” he said. “You always want to put the best foot forward.” The lawsuits for which Mr. Trump was deposed stemmed largely from real estate deals that went bust. In two of the cases, Mr. Trump was accused of misleading home buyers about his role as a developer of condominium towers in Florida when he was in fact licensing his name to the projects. In a third case, he was the accuser, leveling claims of defamation against Timothy O’Brien, a reporter for The New York Times at the time who asserted in a book that Mr. Trump’s net worth was far less than he had publicly claimed. (Mr. Trump settled with plaintiffs in one condo case; he won the other. He failed to prove his case against Mr. O’Brien.) For Mr. Trump, a man accustomed to luxurious private planes and a solicitous staff, the dozens of hours of tedious testimony represented a humbling and, at times, aggravating concession to the American legal system. His temper sometimes flared. Under questioning by Ms. Beck in 2011 in the Florida real estate case, he was insulting. “Do you even know what you’re doing?” he challenged her. But when Ms. Beck insisted on pausing for an hour to pump breast milk, Mr. Trump, in the words of her husband, had “a meltdown” during a break in the deposition. In a letter at the time, Mr. Beck said Mr. Trump had called his wife “uptight” as well as “disgusting.” Mr. Garten, the Trump lawyer, did not dispute Mr. Beck’s account of Mr. Trump’s language, but said it “was in no way a statement about her decision to breast-feed or pump.” “It was solely the fact that she was appearing to do it in the middle of a deposition,” he said — although no one involved suggested that she had gone beyond displaying the pump. Continue reading the main story First Draft Newsletter Subscribe for updates on the 2016 presidential race, the White House and Congress, delivered to your inbox Monday - Friday. Mr. Garten added: “In my 20 years of legal practice, I’ve never seen more bizarre behavior at a deposition. That is what led to his remark.” Advertisement Continue reading the main story Advertisement Continue reading the main story Mr. Garten said that “every accommodation” had been made for Ms. Beck to take breaks, but that he believed she was seeking to buy time to come up with new questions for Mr. Trump. The Becks lost one of their cases against Mr. Trump and are appealing. The depositions also expose other intriguing details about the habits and preferences of a man whose public persona can have a one-dimensional quality. Alcohol? He does not touch it, Mr. Trump testified. Television? “I don’t have a lot of time,” he said, “for listening to television.” Text messages? Not for him. For a candidate who says he is an authority on modern business, Mr. Trump is slow to adopt technology. In 2007, he said he had no home or office computer. “Does your secretary send emails on your behalf?” he was asked. His secretary generally typed letters, Mr. Trump said. “I don’t do the email thing.” By 2013, Mr. Trump was still not sold on email. “Very rarely, but I use it,” he said under questioning. Perhaps the most striking revelations surround Mr. Trump’s fluid evaluations of his own financial portfolio, which he declared in a deposition can fluctuate based on his “feelings.” “Yes, even my own feelings,” Mr. Trump testified, “as to where the world is, where the world is going, and that can change rapidly from day to day.” In the deposition for the defamation lawsuit, lawyers for Mr. O’Brien asked Mr. Trump to explain the role his feelings played in valuing a parcel of land in Westchester County, N.Y. He had stated it was worth $80 million one year and then $150 million the next. “Was it your view of the value of the property that changed from 2005 to 2006?” he was asked. “Yeah, that the value of the property has gone up substantially,” Mr. Trump said. “Did you have any appraisal done?” he was asked a moment later. “I don’t believe so, no.” “Did you have any basis for that view other than your own opinion?” a lawyer followed up. “I don’t believe so, no,” he said. That unconventional approach may raise questions about Mr. Trump’s public claim this month that he is worth $10 billion. Pressed repeatedly in depositions about optimistic financial figures, Mr. Trump sounded, even years ago, like a man who was weighing a campaign for elected office. “I didn’t confirm or deny,” Mr. Trump joked at one point, “as a politician would say.” But not just any politician, the depositions suggest. In 2013, when a lawyer asked Mr. Trump how he chose his business partners, Mr. Trump made clear the level of office he had in the back of his mind. “You get references and opinions of people, and you go on that,” Mr. Trump said. “That’s true with the president of the United States.” The lawyer questioning Mr. Trump seemed perplexed. “Did we have references for the president of the United States?” Before Mr. Trump could answer, his lawyer jumped in. “Objection.” ||||| Washington (CNN) Donald Trump distanced himself Tuesday from comments one of his top advisers made in an explosive interview while defending the Republican presidential candidate from a decades-old rape accusation. Michael Cohen, special counsel to Trump and an executive vice president at The Trump Organization, apologized Tuesday after telling the Daily Beast that legally "you cannot rape your spouse." The rape claim stems from an accusation Trump's then-wife Ivana Trump leveled at her husband during divorce proceedings in the early 1990s, an allegation she walked back Tuesday. "He's speaking for himself. He's not speaking for me, obviously," Trump said to CNN's Don Lemon Tuesday, which aired on "The Situation Room." Trump called The Daily Beast a "joke" desperate to remain relevant. "Michael was extremely angry because he knew (the alleged incident) never took place," Trump told Lemon. Marital rape has been illegal in all 50 states since 1993 and non-consensual sex between spouses does in fact constitute rape, said Scott Berkowitz, the president and founder of the Rape, Abuse & Incest National Network. Cohen apologized for his comments Tuesday, calling them "inarticulate," and said the reporter's question sent him into a tailspin. "As an attorney, husband and father there are many injustices that offend me but nothing more than charges of rape or racism. They hit me at my core. Rarely am I surprised by the press, but the gall of this particular reporter to make such a reprehensible and false allegation against Mr. Trump truly stunned me. In my moment of shock and anger, I made an inarticulate comment - which I do not believe -- and which I apologize for entirely," Cohen said in a statement to CNN. Cohen, who is one of Trump's top lawyers, threatened to sue the Daily Beast reporter and ruin the reporter's life. "I will make sure that you and I meet one day while we're in the courthouse. And I will take you for every penny you still don't have. And I will come after your Daily Beast and everybody else that you possibly know," Cohen said, according to the Daily Beast. "So I'm warning you, tread very f---ing lightly, because what I'm going to do to you is going to be f---ing disgusting. You understand me?" "Mr. Trump didn't know of his comments but disagrees with them," Trump campaign manager Corey Lewandowski told CNN, referring to Cohen's remarks to the Daily Beast. In a statement obtained by CNN, Ivana Trump said the Daily Beast story "is totally without merit." "I have recently read some comments attributed to me from nearly 30 years ago at a time of very high tension during my divorce from Donald. The story is totally without merit. Donald and I are the best of friends and together have raised three children that we love and are very proud of. I have nothing but fondness for Donald and wish him the best of luck on his campaign. Incidentally, I think he would make an incredible president," Ivana Trump said in the statement, which was verified by the Trump campaign. The campaign also distanced itself from Cohen, who has spent weeks appearing on multiple television news shows, including CNN's "New Day," to play up Trump's candidacy for president and defend the campaign from attacks from Trump's primary opponents. "Michael Cohen is a corporate employee and is not affiliated with the campaign in any way.=," Lewandowski told CNN. When asked whether Cohen would continue to make television appearances and behave as a surrogate for Trump, he dismissed the question, saying the campaign and Trump's company are separate enterprises. "This would be like asking Nike what they think of Reebok," Lewandowski said. JUST WATCHED Trump adviser backs controversial Huckabee comments Replay More Videos ... MUST WATCH Trump adviser backs controversial Huckabee comments 01:29 "Mr. Trump speaks for Mr. Trump and nobody but Mr. Trump speaks for him," a campaign source told CNN on Tuesday morning. A second campaign source toed the same line and pushed back against the notion that Cohen is a surrogate for the campaign. "He is speaking as someone who has great insight into Mr. Trump's skills as an executive," the source said. Both sources emphasized that Cohen is employed by the Trump Organization and not the campaign. Cohen has not only repeatedly appeared on TV to support Trump's presidential campaign, but he has also provided statements in response to political reporters' inquiries about Trump campaign controversies. Cohen sent CNN a statement via email earlier this month when Trump's official Twitter account posted photo of men in Nazi uniforms. In a deposition during divorce proceedings, Ivana Trump accused her husband of raping her during a 1989 incident, an accusation that was first revealed in the 1993 book by former Newsweek reporter Harry Hurt III, "Lost Tycoon: The Many Lives of Donald J. Trump." CNN could not obtain a copy of the deposition. As the book was about to be published, Ivana Trump wrote a statement that was printed on the first page of that book: "I felt violated, as the love and tenderness, which he normally exhibited towards me, was absent," she said in the statement. "I referred to this as a 'rape,' but I do not want my words to be interpreted in a literal or criminal sense." A Trump campaign spokesperson said in a statement that the rape accusation "is old news and it never happened." "It is a standard lawyer technique, which was used to exploit more money from Mr. Trump especially since he had an ironclad prenuptial agreement," the spokesperson said. Democrats quickly pounced on Cohen's remarks, with Democratic National Committee Chairwoman Debbie Wasserman-Schultz calling Cohen's comments "a new low" in a statement Tuesday morning and telling Republicans to take a stand. "Rape is rape. Full stop. End of story. There is no difference or division between 'forcible', 'legitimate', 'marital' or any other label Republicans slap on before the word 'rape'. All rape is a disgusting violation, and Americans have fought too long and hard for that to be acknowledged to still have it questioned in 2015," Wasserman-Schultz said in the statement. "It's a pattern of outrageous comments that must stop, and Republicans should call it what it is - despicable." Ivana Trump is Donald Trump's first wife and mother to his three oldest children: Ivanka, Eric and Donald, Jr. who are all top officials at The Trump Organization. Trump is now married to his third wife, Melania Trump.

– The New York Times has pored over hundreds of pages of Donald Trump testimony from his many lawsuits over the last decade and found a lot of what it describes as "hyperbolic overstatements" and "outright misstatements," as well as some instances of truly obnoxious behavior—like the time he told a lawyer who wanted to take a break to pump breast milk that she was "disgusting." That happened during a 2011 hearing in a Florida real estate case, the Times reports, when lawyer Elizabeth Beck asked for a medical break to pump milk for her 3-month-old daughter, holding up the pump to make a point when the Trump team objected. "You're disgusting," Trump said, per the Times, and walked out of the room, ending proceedings for the day. Trump lawyer Alan Garten doesn't dispute the events, but he tells the Times that "disgusting" wasn't a statement on breastfeeding—it was on Beck displaying the pump. "In my 20 years of legal practice, I've never seen more bizarre behavior at a deposition," the lawyer says. "That is what led to his remark." Another Trump lawyer, Michael Cohen, has apologized for falsely claiming that "by the very definition, you can't rape your spouse." He tells CNN that the remark was made in a "moment of shock and anger" when a Daily Beast reporter brought up a decades-old allegation. The Trump campaign tells CNN that Trump "didn't know of his comments but disagrees with them" and that Cohen is a Trump corporate employee not affiliated in any way with the campaign.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Portable Generator Safety Act''. SEC. 2. FINDINGS. The Congress finds the following: (1) Portable generators are frequently used to provide electricity during temporary power outages. These generators use fuel-burning engines that emit carbon monoxide gas in their exhaust. (2) In the last several years, hundreds of people nationwide have been seriously injured or killed due to exposure to carbon monoxide poisoning from portable generators. From 1990 through 2003, 228 carbon monoxide poisoning deaths were reported to the Consumer Product Safety Commission. (3) Virtually all of the serious injuries and deaths due to carbon monoxide from portable generators were preventable. In many instances, consumers simply were unaware of the hazards posed by carbon monoxide. (4) Since at least 1997, a priority of the Consumer Product Safety Commission has been to reduce injuries and deaths resulting from carbon monoxide poisoning. Although the Commission has attempted to work with industry to devise voluntary standards for portable generators, and despite Commission staff statements that voluntary standards were ineffective, the Commission has not promulgated mandatory rules governing safety standards and labeling requirements. (5) The issuance of mandatory safety standards and labeling requirements to warn consumers of the dangers associated with portable generator carbon monoxide would reduce the risk of injury or death. SEC. 3. SAFETY STANDARD. Not later than 180 days after the enactment of this Act, the Consumer Product Safety Commission shall promulgate regulations, pursuant to section 7 of the Consumer Product Safety Act (15 U.S.C. 2056), requiring, at a minimum, that every portable generator sold to the public for purposes other than resale shall be equipped with an interlock safety device that detects the level of carbon monoxide in the areas surrounding such portable generator and automatically turns off power to the portable generator before the level of carbon monoxide is capable of causing serious bodily injury or death to people. SEC. 4. LABELING AND INSTRUCTION REQUIREMENTS. Not later than 180 days after the enactment of this Act, the Consumer Product Safety Commission shall promulgate regulations, pursuant to section 7 of the Consumer Product Safety Act (15 U.S.C. 2056), requiring, at a minimum, the following: (1) Warning labels.--Each portable generator sold to the public for purposes other than resale shall have a large, prominently displayed warning label on the exterior packaging, if any, of the portable generator and permanently affixed on the portable generator regarding the carbon monoxide hazard posed by incorrect use of the portable generator. The warning label shall include the word ``DANGER'' printed in a large font, and shall include the following information, at a minimum, presented in a clear manner: (A) Indoor use of a portable generator can kill quickly. (B) Portable generators should be used outdoors only and away from garages and open windows. (C) Portable generators produce carbon monoxide, a poisonous gas that people cannot see or smell. (2) Pictogram.--Each portable generator sold to the public for purposes other than resale shall have a large pictogram, affixed to the portable generator, which clearly states ``POISONOUS GAS'' and visually depicts the harmful effects of breathing carbon monoxide. (3) Instruction Manual.--The instruction manual, if any, that accompanies any portable generator sold to the public for purposes other than resale shall include detailed, clear, and conspicuous statements that include the following elements: (A) A warning that portable generators emit carbon monoxide, a poisonous gas that can kill people. (B) A warning that people cannot smell, see, or taste carbon monoxide. (C) An instruction to operate portable generators only outdoors and away from windows, garages, and air intakes. (D) An instruction to never operate portable generators inside homes, garages, sheds, or other semi- enclosed spaces, even if a person runs a fan or opens doors and windows. (E) A warning that if a person begins to feel sick, dizzy, or weak while using a portable generator, that person should shut off the portable generator, get to fresh air immediately, and consult a doctor. D23/

Portable Generator Safety Act - Instructs the Consumer Product Safety Commission to promulgate regulations requiring that every portable generator sold to the public for purposes other than resale be equipped with an interlock safety device that detects the level of carbon monoxide in the areas surrounding the generator and automatically turns off power to it before the level of carbon monoxide is capable of causing serious bodily injury or death to people. Requries such regulations also to require that every such portable generator: (1) prominently display a permanently affixed warning label regarding the carbon monoxide hazard posed by its incorrect use, including the word "DANGER" printed in a large font; and (2) have affixed to it a large pictogram which clearly states "POISONOUS GAS" and visually depicts the harmful effects of breathing carbon monoxide.

CLOSE Fashion model Hanne Gaby Odiele is teaming up with the non-profit organization, InterACT Advocates for Intersex Youth. Odiele recently revealed that she is intersex and is hoping to give a voice to people who are often in the shadows. USA TODAY NETWORK Hanne Gaby Odiele attends the 2015 CFDA Fashion Awards at Alice Tully Hall at Lincoln Center on June 1, 2015, in New York. (Photo: Larry Busacca, Getty Images) Hanne Gaby Odiele is a fearless fashion star known for putting herself out there in a bold and striking take on street style. Now, the veteran of the runway and city sidewalks is revealing a more intimate piece of herself: Odiele is intersex. “It is very important to me in my life right now to break the taboo,” says the 29-year-old supermodel from Kortrijk, Belgium, in an exclusive interview with USA TODAY. “At this point, in this day and age, it should be perfectly all right to talk about this,” says Odiele, one of the first high-profile people to disclose her intersex status and share her story. Intersex individuals are born with sex characteristics such as genitals or chromosomes that do not fit the typical definitions of male or female. Up to 1.7% of the population is born with intersex traits, according to the United Nations — a figure roughly equivalent to the number of redheads. Beyond giving a voice to people who are often in the shadows, Odiele is making this disclosure to spotlight medical procedures intersex children undergo without their consent in a misguided effort to make a child appear more typically male or female. “I am proud to be intersex,” she says, “but very angry that these surgeries are still happening.” More coverage:What it means to be intersex and how common is it? Odiele was one of those children. She was born with an intersex trait known as Androgen Insensitivity Syndrome (AIS) in which a woman has XY chromosomes more typically found in men. She also had internal, undescended testes, and her parents were told that if she did not have her testicles removed, “I might develop cancer and I would not develop as a normal, female girl,” she says. At 10, she had surgery to remove her testes, an experience she could barely process at the time. “I knew at one point after the surgery I could not have kids, I was not having my period. I knew something was wrong with me.” At 18, Odiele — whose modeling career took root when she was discovered a year earlier at a music festival in Belgium — underwent an equally distressing procedure in the form of vaginal reconstructive surgery. “It’s not that big of a deal being intersex,” she says. But the anguish of the two surgeries is an issue for her that is still troubling today. “If they were just honest from the beginning... It became a trauma because of what they did.” AWARENESS AND OUTRAGE Kimberly Zieselman, executive director of interACT Advocates for Intersex Youth, says Odiele will be a powerful champion for the intersex community and will help thrust medical procedures that try to “fix” intersex kids into the harsh focus they deserve. Zieselman says Odiele will partner with her advocacy group. “I think her speaking out, having her voice added to the mix is going to culturally raise awareness in the mainstream,” she says, noting that groups such as the U.N. and the World Health Organization already condemn these surgeries as human rights violations. It will “help in raising awareness – and raising outrage.” Zieselman, now 50, had an experience as searing as Odiele’s. At 15, a reproductive oncologist at Massachusetts General Hospital told her parents she had a partially formed uterus and ovaries that needed to be removed so they would not become cancerous. Her parents consented. When the married mother of adopted twin girls was 40 and struggling with a hernia problem, she obtained her medical records. Zieselman was stunned to find the surgery she had as a teen removed internal, undescended testes. Zieselman never had a uterus, ovaries — or cancer; she was intersex. “My story quite frankly is not unique,” says Zieselman, whose group’s No. 1 priority is ending irreversible procedures. “Hundreds of women have a similar story. Hiding the truth conjures up feeling like a freak.” A fear of non-binary bodies — not a pressing medical need — is often what drives surgical interventions on intersex children, says Sue Stred, a professor of pediatrics at SUNY Upstate Medical University. When a newborn’s genitals do not appear “typical,” parents can be compelled to have their child undergo cosmetic surgery to appear more ordinary. As for concerns about cancer, Stred says there is not “good, long-term data” on whether someone with a condition such as AIS may develop cancer if testicles are not removed. “The possible percentage chance of cancer is vastly overwrought,” says Stred, who specializes in pediatric endocrinology. LIFELONG REPERCUSSIONS The consequence of removing gonads is a lifelong dependence on hormone replacement medications, Stred says, and permanent infertility. Other physical issues are reduced sexual sensations, urinary tract infections and incontinence. The psychological repercussions of these medical procedures can also be devastating, Stred says. “There is a sense of betrayal when teens or young adults find out. Some individuals leave medical care altogether because they are so angry at what physicians did to them before they were the age of consent.” And there is tremendous resentment of parents, she says. Kids think “something was done to me; you felt I wasn’t perfect; I had to be fixed.” Awareness of intersex issues is slowly evolving, says Zieselman, who notes that many people don't even know what intersex means. Being intersex relates to biological sex characteristics. It is not the same as transgender: someone whose gender identity — how they feel inside — does not correspond with their birth sex. An intersex individual can be straight, gay, lesbian, bisexual. “It’s amazing to me just in the last two years to see the difference in how many intersex young people are willing and comfortable to speak out at earlier ages. It is largely thanks to the LGBT movement ahead of us,” Zieselman says. It is that group that may also carve a path on the issue of unneeded surgeries, she says. The transgender community “is doing it right,” she says. “No surgical treatment until (individuals) have psychological support. That’s a model we can use.” Above all, Stred says there should be no surgery until an intersex child is at an age of consent and can weigh the benefits and risks. “You wouldn’t do a nose job on a 7-year-old,” she says. A PASSIONATE VOICE When Odiele’s career was at the starting gate in 2006, she was slammed by a car that ran a red light on the streets of New York, leaving her with two broken legs and multiple fractures. After several surgeries and physical therapy, she was back on the catwalk — just 10 months later. She says the experience grounded her in her career choice and “gave me something to fight for.” Now she is hoping to take that fighting spirit to the next level by being a passionate advocate for intersex youth. “It is an important part of my life to talk about this,” says Odiele, whose story will also appear in the issue of Vogue magazine that hits newsstands Wednesday. Odiele has been more open about her status in the past year with close friends and trusted associates — particularly during chats about periods or having babies — but this is her first public announcement. She says she doesn't fear any backlash from colleagues in the fashion industry. "They will see me as they have before," she says. "Nothing should change." Today Odiele loves to lounge in her husband’s clothes as her “go-to day to day” just as much as getting “glammed up.” She says being intersex has given her a forward-thinking perspective on fashion. “I didn’t have to fit into certain roles,” she says. “I was able to kind of have a sense of being more of an individual.” Her husband, model John Swiatek, says he is “incredibly proud and happy” his wife is speaking out. “I am very impressed with her decision to advocate for intersex children in order to give them an opportunity to make up their own minds about their bodies, unlike the lack of options and information Hanne and her family (and many others) were given,” he says. Last summer, the fashion star who has been in front of cameras for the industry’s A-list photographers and poses for brands from Dior to Alexander Wang, married Swiatek in an outdoor bash infused with countryside cool in upstate New York. She wore a hooded cape draping a sheer lace dress, with cargo pants and a bra top peeking through. Bridesmaids strolled barefoot through fields in shimmering lavender slip dresses. It was trademark Odiele. Odiele, who calls her innovative style “just being myself; no rules,” has the same message for intersex youth today: “You can be whoever you want. It doesn’t matter.” Follow Miller on Twitter @susmiller Read or Share this story: http://usat.ly/2jPBxiH ||||| To answer this question in an uncontroversial way, you’d have to first get everyone to agree on what counts as intersex —and also to agree on what should count as strictly male or strictly female. That’s hard to do. How small does a penis have to be before it counts as intersex? Do you count “sex chromosome” anomalies as intersex if there’s no apparent external sexual ambiguity? (Alice Dreger explores this question in greater depth in her book Hermaphrodites and the Medical Invention of Sex.) Here’s what we do know: If you ask experts at medical centers how often a child is born so noticeably atypical in terms of genitalia that a specialist in sex differentiation is called in, the number comes out to about 1 in 1500 to 1 in 2000 births. But a lot more people than that are born with subtler forms of sex anatomy variations, some of which won’t show up until later in life. Below we provide a summary of statistics drawn from an article by Brown University researcher Anne Fausto-Sterling. The basis for that article was an extensive review of the medical literature from 1955 to 1998 aimed at producing numeric estimates for the frequency of sex variations. Note that the frequency of some of these conditions, such as congenital adrenal hyperplasia, differs for different populations. These statistics are approximations. Not XX and not XY one in 1,666 births Klinefelter (XXY) one in 1,000 births Androgen insensitivity syndrome one in 13,000 births Partial androgen insensitivity syndrome one in 130,000 births Classical congenital adrenal hyperplasia one in 13,000 births Late onset adrenal hyperplasia one in 66 individuals Vaginal agenesis one in 6,000 births Ovotestes one in 83,000 births Idiopathic (no discernable medical cause) one in 110,000 births Iatrogenic (caused by medical treatment, for instance progestin administered to pregnant mother) no estimate 5 alpha reductase deficiency no estimate Mixed gonadal dysgenesis no estimate Complete gonadal dysgenesis one in 150,000 births Hypospadias (urethral opening in perineum or along penile shaft) one in 2,000 births Hypospadias (urethral opening between corona and tip of glans penis) one in 770 births Total number of people whose bodies differ from standard male or female one in 100 births Total number of people receiving surgery to “normalize” genital appearance one or two in 1,000 births We were recently asked to update these frequency figures, and a lively discussion arose between two staff members. ||||| 1 / 6 Expand __SLIDE_TITLE__ __SLIDE_CAPTION__ __SLIDE_CREDIT__ See more photos of: Read Caption __SLIDE_TITLE__ __SLIDE_CAPTION__ __SLIDE_CREDIT__ Vogue may earn compensation on these sales through affiliate programs. See more photos of: Expand Photo: Courtesy of Kasia Struss / @kasiastruss See more photos of: Expand Photo: Courtesy of Alana Zimmer / @zimzimzimmer See more photos of: Expand Photo: Courtesy of Esteban Cortazar / @ecortazar See more photos of: Expand Photo: Courtesy of Simon Rasmussen / @simonrasmussen See more photos of: Expand Photo: Courtesy of Grace Mahary / @gracemahary See more photos of: Expand Photo: Courtesy of Nicholas Grasa / @nicholasgrasa See more photos of: What happens when a crew of self-proclaimed “bad girl” models get together to celebrate a fellow catwalker’s wedding? Well, as you might expect, it’s a major throw-down. This past weekend, Hanne Gaby Odiele, the leggy model known for her outré street style married her longtime boyfriend and fellow model John Swiatek in a charming, bucolic bash in upstate New York. Odiele, a staple on Alexander Wang’s runway and campaigns, wore white low-slung trousers and a bra top from the designer with a lace overlay and an ivory silk cape thrown over for a bride-to-be effect. Swiatek looked especially dapper in a matching white suit. Bridesmaids included models Kasia Struss, Anna Ewers, Sheila Marquez, and Alanna Zimmer, as well as makeup artist Tracy Alfajora, all of whom wore slinky lavender slip dresses and went barefoot. Guests included Ladyfag, who hung on a tractor in a slashed-up green leopard-print skirt and bustier tank, while Mica Arganaraz wore an artfully floppy plaid shirt and hip bone–hanging flares and Julia Nobis punctuated the rainy weather in a bright graphic jacket and sneakers. Louise du Toit, who officiated the ceremony, wore a blush pink robe and a violet stole. Though many of those attending the wedding may have looked slightly more formal than their usual, late-night, partying selves, some habits are hard to break—or as Alexander Wang pointed out in his video of Odiele and crew strutting, “When u walk the runway down the aisle.” And that, ladies and gentlemen, is how a model wedding is done. ||||| Crawl of outlinks from wikipedia.org started March, 2016. These files are currently not publicly accessible. Properties of this collection. It has been several years since the last time we did this. For this collection, several things were done: 1. Turned off duplicate detection. This collection will be complete, as there is a good chance we will share the data, and sharing data with pointers to random other collections, is a complex problem. 2. For the first time, did all the different wikis. The original runs were just against the enwiki. This one, the seed list was built from all 865 collections. ||||| CLOSE At least 1 in 5,000 U.S. babies are born each year with intersex conditions _ ambiguous genitals because of genetic glitches or hormone problems. Secrecy and surgery are common. But some doctors and activists are trying to change things. (April 17) AP Hanne Gaby Odiele attends the 2015 CFDA Fashion Awards at Alice Tully Hall at Lincoln Center on June 1, 2015, in New York. (Photo: Larry Busacca, Getty Images) Model Hanne Gaby Odiele is one of the first high-profile people to disclose that she is intersex. The 29-year-old supermodel from Kortrijk, Belgium, said she is speaking out because she wants to "break the taboo" surrounding intersex people. But what does it mean to be intersex? Here's a quick explainer: Intersex individuals are born with sex characteristics such as genitals or chromosomes that do not fit the typical definitions of male or female. "A girl may be born with a noticeably large clitoris, or lacking a vaginal opening, or a boy may be born with a notably small penis, or with a scrotum that is divided so that it has formed more like labia. Or a person may be born with mosaic genetics, so that some of her cells have XX chromosomes and some of them have XY," according to the Intersex Society of North America. While intersex can be discovered at birth, some people may not realize they are intersex until later in life when they reach puberty or find they are infertile, according to the Intersex Society of North America. How common is intersex? Up to 1.7% of the population is born with intersex traits, according to the United Nations — a figure roughly equivalent to the number of redheads. What happens to children that are born intersex? People born intersex may go through surgical procedures to make their genitals appear more male or female. Odiele was born with an intersex trait known as Androgen Insensitivity Syndrome (AIS) in which a woman has XY chromosomes more typically found in men. She also had internal, undescended testes, and her parents were told that if she did not have her testicles removed, “I might develop cancer and I would not develop as a normal, female girl,” she says. At 10, she had surgery to remove her testes, an experience she could barely process at the time. “I knew at one point after the surgery I could not have kids, I was not having my period. I knew something was wrong with me.” Are intersex people identified as male or female on their birth certificates? In December, 55-year-old Sara Kelly Keenan received what is believed to be the first intersex birth certificate in the U.S., NBC reported. Keenan was born in New York City with male genes, a mix of male and female reproductive organs and female genitalia, according to the news outlet. She was classified as a male for three weeks and then issued a female birth certificate and was unaware she was intersex until adulthood. Read or Share this story: http://usat.ly/2kj2Hez

– She's used to putting herself on display, but Belgian model Hanne Gaby Odiele exposed herself in a different way on Monday. The 29-year-old sat with USA Today and revealed something that "should be perfectly all right to talk about ... in this day and age": Odiele is intersex, having been born with undescended testes and Androgen Insensitivity Syndrome, meaning she has XY chromosomes. Odiele, whom Vogue refers to as an Alexander Wang staple, says being intersex is "not that big of a deal," but she can't say the same for the two surgeries she has undergone, one at age 10 to remove those testes, which doctors told her parents could lead to cancer. USA Today calls her "one of the first high-profile people" to reveal intersex traits, which an LGBT initiative associated with the UN Human Rights Office estimates are present in 0.05% to 1.7% of people. (The Intersex Society of North America digs into the frequency question in a much more detailed way.) Now married to fellow model John Swiatek, Odiele says she's "very angry that these surgeries are still happening." A professor of pediatrics at SUNY Upstate Medical University tells the paper parents are often pressured into agreeing to subject their intersex kids to surgery when there is no medical necessity, but rather to produce more "normal" children. Odiele's story will appear in the next issue of Vogue; she plans to work with the interACT Advocates for Intersex Youth.

Ahmed Abu Khattala at his arriagnment hearing at the US. District Court, where he appeared for less than five minutes before entering a plea of not guilty on June 28, 2014. (Illustration by Richard Johnson/The Washington Post) Ahmed Abu Khattala, one of the suspected ringleaders of the 2012 attacks in Benghazi, Libya, voiced opposition to the presence of a U.S. facility there in the days before the assault and organized the attacks out of a sense of ideological fervor, according to government prosecutors. After the attack on the U.S. diplomatic mission in Benghazi, Abu Khattala and other armed men entered and looted the compound, then returned to a camp to begin preparations for an attack on a nearby CIA annex, prosecutors said in court documents filed late Tuesday. The two attacks resulted in the deaths of four Americans, including U.S. Ambassador J. Christopher Stevens. Abu Khattala, who was indicted Saturday on a charge of conspiracy, will appear Wednesday morning in U.S. District Court in Washington for a detention hearing before Magistrate Judge Deborah A. Robinson. “There is no condition or combination of conditions that will reasonably assure the defendant’s appearance in court and assure the safety of any person and the community,” U.S. Attorney Ronald C. Machen Jr. wrote in a motion in favor of pretrial detention. U.S. officials said they consider the conspiracy charge, which carries a maximum penalty of life imprisonment, a “place holder” to avoid revealing more evidence in the case while a search for witnesses continues. In the coming weeks, a superseding indictment is expected to bring additional charges, including ones that carry the death penalty. Abu Khattala has pleaded not guilty. Ahmed Abu Khattala, Libyan militia leader and alledged mastermind behind the deadly 2012 Benghazi attack, pled not guilty to terror charges in a U.S. District Court Saturday. (Reuters) Tuesday’s court filing is a preview of the case that prosecutors are building against Abu Khattala, the only suspect in the Benghazi attacks to be apprehended and one of the most significant terrorism suspects to face U.S. trial in recent years. According to a U.S. official who has reviewed the case against Abu Khattala, the evidence includes photographs and video from the attacks, testimony from witnesses, and evidence of the attacks’ planners boasting of their involvement. Abu Khattala was seized June 15 in Benghazi by U.S. Special Operations forces, 21 months after the fiery attacks on the U.S. facilities there. In the new court documents, prosecutors said for the first time that Abu Khattala was armed with a loaded handgun when he was detained. He was taken to a U.S. Navy warship, where he was questioned by intelligence and law enforcement officials. While aboard the vessel, the USS New York, Abu Khattala spoke freely with his interrogators both before and after he was read his Miranda rights, U.S. officials said, although they have declined to describe the nature of any information he provided. He was later transferred by helicopter to the Washington area. The exact cause of the attacks in Benghazi became the source of a bitter political dispute in Washington, in part because U.S. officials initially said it had begun as one of a number of spontaneous anti-U.S. street demonstrations sweeping across the Arab world as protesters denounced an anti-Muslim Internet video. The Obama administration later labeled what happened in Benghazi a terrorist attack. In their motion, prosecutors alleged that Abu Khattala’s motivation to attack the U.S. facilities sprang from his extremist anti-Western views. “In the days before the Attack, the defendant voiced concern and opposition to the presence of an American facility in Benghazi,” prosecutors stated. They said many of his associates in the Ansar al-Sharia militia have been identified as being among a group of 20 or more armed men who gathered outside the U.S. mission on Sept. 11, 2012, and who later “aggressively breached the gate” before entering the facility, setting fire to the property and stealing a U.S. vehicle. After the attack, according to the court documents, Abu Khattala “supervised the exploitation of material from the scene by numerous men.” In the days that followed the Benghazi attacks, prosecutors said, Abu Khattala tried to obtain equipment and weapons to defend himself from possible U.S. retaliation. U.S. Special Operations forces have captured Ahmed Abu Khattala, an alleged ringleader of the 2012 attacks on the U.S. diplomatic compound in Benghazi, Libya. Here is what is known about Khattala. (The Washington Post) Late last year, he expressed anger that U.S. forces had captured Nazih Abdul-Hamed al-Ruqai, also known as Anas al-Libi, in Tripoli in connection with the 1998 bombings of the U.S. embassies in Kenya and Tanzania. According to prosecutors, Abu Khattala then took steps to retaliate against the United States by targeting American interests in the region. He allegedly has extensive contacts with senior members of extremist groups in Libya, including close associates who participated in the Benghazi attacks. He also increased his personal security, the court document said, because he was afraid that U.S. forces might try to capture him in Libya, as they eventually did. Abu Khattala is being held in the Alexandria detention center. Wednesday’s pretrial detention hearing is scheduled for 11 a.m. Rachel Weiner contributed to this report. ||||| Providing more fuel for the extremely politicized debate over whether the 2012 attack on the U.S. consulate in Benghazi was planned by terrorists or grew out of spontaneous protests, new documents released in the case of Ahmed Abu Khattala, the suspected ringleader captured in Libya last month, make no mention of the anti-Muslim YouTube video that sparked the demonstrations. In court papers filed on Tuesday, federal prosecutors say that Abu Khattala complained about the presence of an American facility in Benghazi several days prior to the attack, and was "motivated by his extremist ideology." Prosecutors added that he has "repeatedly expressed his hatred of Americans and his efforts to target American and Western interests." The document, which is intended to convince a judge that the man the State Department designated as a terrorist shouldn't be released prior to his trial, provides a brief overview of the case against Abu Khattala. According to the prosecution, on the night of September 11, 2012, "a group of twenty or more armed men" gathered outside the U.S. mission in Benghazi, then "aggressively breached" the gate and set the fire that led to the deaths of Ambassador Christopher Stevens and Information Management Officer Sean Patrick Smith. The papers claim that Abu Khattala is a leader in Ansar al-Sharia, and many of the initial attackers were part of the terrorist group. After the first attack, Abu Khattala allegedly "entered the compound and supervised the exploitation of material from the scene by numerous men, many of whom were armed." Then he returned to an AAS camp, where members were assembling for the attack on a second U.S. facility, in which two more Americans were killed. Afterward, Abu Khattala became worried that the U.S. was trying to capture him, and "attempted to obtain various types of equipment, including weapons, to defend himself from feared American retaliation." He also continued to make unspecified "efforts to target American personnel and property." While Abu Khattala pleaded not guilty to a single count of conspiracy "to provide material support and resources to terrorists resulting in death," last week, the government says its claims are supported by physical evidence and "numerous witnesses." According to the New York Times, Abu Khattala has not incriminated himself in the killing of the four Americans, but prosecutors say that since his capture he's given "voluntary statements corroborating key facts." The conspiracy charge carries a maximum sentence of life in prison, but U.S. officials are expected to add additional charges that carry the death penalty in the coming weeks.

– In newly released court documents, prosecutors laying out the case against alleged Benghazi mastermind Ahmed Abu Khattala allege that he was "motivated by his extremist ideology"—and make no mention, New York observes, of that infamous anti-Muslim YouTube video US officials initially blamed for the attack. Prosecutors say Khattala had complained of the consulate's presence in Benghazi days earlier. They allege that he is a leader of the Ansar al-Sharia terror group, and that several members of that group took part in the attack. Once they were through the consulate walls, Khattala allegedly "supervised the exploitation of material from the scene by numerous men." The document, which is intended to convince the judge to keep Khattala in custody until his trial, offers a rough sketch of the case against him, but prosecutors say they expect to add more charges, the Washington Post reports. It also reveals for the first time that Khattala was armed with a handgun when he was captured. Prosecutors also say he spoke freely with interrogators both before and after he was read his Miranda rights.

recent progress in semiconductor technology now allows the fabrication of artificially structured atoms in semiconductors called quantum dots , in which electrons are trapped in a small localized region of space of a few hundred angstrms . in these nanostructures the electron wavelength is of the same length scale as the confinement so that quantum effects are important , which results in the quantization of single - electron energy levels with excitation energy of several mev ( see for review @xcite ) . a prominent feature of a fermi - system which is confined to a finite region of space is the emergence of shell effects in the single - particle spectrum as is well known in nuclear physics @xcite and more recently for large metallic clusters ( @xcite-@xcite and references therein ) . in the present work we address this problem to mesoscopic systems like quantum dots which contain a small number of electrons . the electron states of few - electron quantum dots subjected to a strong magnetic field have been studied extensively in @xcite-@xcite . the electrodynamic response of an interacting electron system in the presence of a confining potential is expected to be dominated by the many - body effects of the electrons . sikorski and merkt @xcite found experimentally the surprising result that the resonance frequencies in the magneto - optical spectrum are independent of the number of electrons in the quantum dot . the systems which are experimentally realized extent much less in the the @xmath3direction than in the @xmath4plane . this has led to a simple description of the far - infrared resonance ( fir ) frequencies @xcite as the energy levels of a two - dimensional harmonic oscillator potential in the presence of a magnetic field @xcite . it was interpreted as a consequence of kohn s theorem @xcite which has been generalized for a parabolic potential @xcite . according to this theorem , the total hamiltonian can be divided into two parts , the center - of - mass motion ( cm ) and the relative motion which contains the electron - electron interaction . since the radiation of an external electric dipole field couples only to the cm motion and does not affect the relative motion , the dipole resonance frequencies for the interacting system should be exactly the same as those of the noninteracting system and be independent of the electron - electron interaction . a full understanding of the experimental results needs an analysis of many - body effects . microscopic calculations using hartree approximation for electron numbers @xmath5 @xcite neglected the exchange and correlation effects . the direct numerical diagonalization @xcite have been performed only for three- and four electron systems . the more complicated resonance structure observed in @xcite raised the question as to the validity of kohn s theorem for quantum dots . in order to describe the experimental data it was assumed that , in real samples , there is a deviation of the confining potential from the parabolic form , and different corrections have been introduced @xcite . also , the important role of the combined effect of the coulomb forces and spin interaction leading to a redistribution of single - electron levels was demonstrated for the whole energy spectrum , especially for the low - lying single - electron states in the homogeneous magnetic field @xcite . the ground state transitions predicted in this way have been observed experimentally @xcite . it seems therefore natural to assume that the properties of the electron states close to the fermi level are determined by an effective mean field . it is true that the external field is the dominant part of the mean field , and thus the effective confining potential should reflect the main features of it . yet it must also contain the effect of the interplay between coulomb forces and the external fields which are governed by the charges in the adjacent layers and gates and the magnetic field . due to these considerations , we assume that the confining potential should also take into account the changes that affect the properties of the single - electron states owing to a variation of the homogeneous magnetic field as well as the slab thickness . based on the results discussed in @xcite we conclude that the harmonic oscillator potential can serve as one of the phenomenological effective confining potentials in real samples , at least for small electron numbers . in this paper we study a simple model of a three - dimensional quantum dot in an arbitrarily oriented magnetic field for electron numbers for which the assumption of a parabolic type potential is still physically reasonable . our procedure invokes an effective dependence of the parameters of the confining potential on the magnetic field . in this way , we accommmodate the different mechanisms mentioned above and we allow the system to adjust and change its shape under variation of the applied magnetic field and the particle number . we assume that the electron system behaves like an isolated yet confined droplet ( see also discussion in @xcite ) . one of the major result is a dependence of the single - electron states on the slab thickness . such dependence shows in the fir frequencies on which our analysis is focussed . we also report on transition strengths in absorption experiments and on the spatial extension of the confining potential in a quantum dot . preliminary results have been reported in @xcite . we consider the hamiltonian for @xmath6 noninteracting electrons moving in an effective mean field , i.e. a three - dimensional harmonic oscillator @xmath7 with @xmath8/2 $ ] being the vector potential associated with the homogeneous magnetic field @xmath9 . the model does not explicitly take into account spin degrees of freedom . in other words , the system is assumed to be in a fixed spin state of an arbitrary degree of polarisation . only the orbital motion is affected by the magnetic field . using quantum mechanical equations of motion yip @xcite calculated resonance frequencies for this model . our approach is similar in spirit to @xcite , but we first solve the classical problem , from which all quantum mechanical results easily follow . in contrast to @xcite where the fir frequencies are completely determined by the external potential , the effective mean field responds in our approach to the change of the magnetic field and particle number and thus affects the properties of single - particle excitations . we determine the frequencies @xmath10 by minimizing the total energy for a given number of electrons @xmath6 . in this way we allow the system to adjust the shape of the confining potential under the influence of the applied magnetic field and the particle number . the classical equations of motion for the cartesian components of the momentum and position coordinates read @xmath11 where @xmath12 and @xmath13 are combined to the six dimensional column vector denoted below as @xmath14 . the matrix @xmath15 is given by @xmath16 where the notation @xmath17 is used . denoting the eigenvalues of @xmath15 by @xmath18 we obtain from the form @xmath19 the classical solution @xmath20 where @xmath21 . while the classical orbits are of little interest in the present context , the eigenmodes @xmath22 and the system of eigenvectors listed in the matrix @xmath23 are essential for the quantum mechanical treatment . the eigenmodes which are usually referred to as the normal modes are obtained from the secular equation @xmath24 with @xmath25 denoting the six - dimensional unit matrix . the above equation turns out to be a third order polynomial in @xmath26 and has also been found by @xcite . the column vectors of @xmath23 are the ( complex ) right hand eigenvectors of @xmath27 ( note that @xmath27 is not symmetric , hence neither @xmath23 nor @xmath28 are unitary , yet @xmath29 ) . we denote the column vectors of @xmath23 by @xmath30 , they obey the equations @xmath31 which can be solved as an inhomogeneous system by choosing for instance the sixth component of @xmath30 equal to unity and then determining the normalisation as described in appendix a. with the proper normalisation the classical hamilton function of eq.([ham ] ) is cast into the quantum mechanical form @xmath32 the normal mode boson operators @xmath33 and @xmath34 are related to the quantised version of the classical coordinates by @xmath35 where we denote by @xmath36 a column vector which is the transpose of the vector @xmath37 . the properties of the matrix @xmath38 guarantee the commutator @xmath39=i\hbar \,\delta _ { k , k'}$ ] as a consequence of @xmath40=i\hbar \,\delta _ { i , j}$ ] . we note that eq.([qam ] ) is the exact quantised equivalent of eq.([ham ] ) . the total energy of an @xmath6-particle system associated with the hamiltonian eq.([qam ] ) is given by @xmath41 the occupation numbers @xmath42 are the eigenvalues of @xmath43 and take the values @xmath44 . the ground state is determined by filling the single - particle levels @xmath45 from the bottom . we take care of the electron spin only in obeying the pauli principle which allows two particles in one level . it is clear that different sets of normal modes yield different sets of occupation numbers . the normal modes depend on the three components of the magnetic field and on the harmonic oscillator frequencies . from our assumption that the system adjusts itself under the influence of the magnetic field by minimising @xmath46 , a variation of the magnetic field strength leads to a corresponding change of the confining effective potential which is given by the oscillator frequencies . in other words , for a given magnetic field , we must seek the minimum of @xmath46 under variation of the oscillator frequencies . the variation can not be unrestricted as the confining potential encloses a fixed number of electrons , and assuming that the electron density does not change we are led to a fixed volume constraint which translates into the subsidiary condition @xmath47 with @xmath48 fixed . denoting the lagrange multiplier by @xmath49 we solve the variational problem @xmath50 where @xmath51 denotes the ground state as described above . from eq.([var ] ) we obtain , after differentiation with respect to the frequencies and using feynman s theorem @xcite @xmath52 the useful condition @xmath53 which must be obeyed at the minimum of @xmath46 . in this paper we restrict ourselves to consideration of a thin slab which extents essentially in two dimensions . this is achieved by varying only @xmath54 and @xmath55 in the minimization procedure while keeping @xmath56 fixed at a value which is , say , five times larger than the other two frequencies . in this case only @xmath57 can be fulfilled . choosing different ( fixed ) values of @xmath56 allows to study the dependence of the results on the slab thickness . it is known from the two - dimensional isotropic harmonic oscillator that shell closing occurs for fermions at the numbers @xmath58 . at these numbers strong shell effects manifest themselves as the most stable quantum configurations . as a consequence , for @xmath59 and @xmath60 we must expect the minimum of @xmath46 at the symmetric condition @xmath61 for such electron numbers . in the mean field approach , the breaking of spherical symmetry of the potential gives rise to a deformed shape ( jahn - teller effect @xcite ) . for example , rotational spectra of nuclei and fine structure in the mass spectra of metallic clusters are explained as a consequence of deformed equilibrium potentials of these systems ( see @xcite ) . therefore , for numbers between the shell numbers a deformed configuration ( @xmath62 ) can be expected ; we note that there are always two symmetric solutions : @xmath63 and @xmath64 . the condition @xmath59 ensures that we have a genuine two - dimensional problem in that no particle occupies a quantum mode in the @xmath65-direction @xmath66 . however , if the slab is made thicker ( @xmath56 smaller ) , the occupation of the first mode @xmath67 will occur at the top end of the occupied levels , which could mean that we find then the symmetric minimum at @xmath68 , since two particles are occupying the @xmath65-mode that has become available . the distinction between a slab , that is sufficiently thin so as to prevent occupation of the first mode in the @xmath65-direction , and the slab which can accommodate the first mode is seen physically in the degeneracy of the two lowest normal modes at @xmath60 . an estimate for @xmath69 ( see appendix b ) which is the frequency that just forbids occupation of a @xmath65-mode is given by @xmath70 with @xmath71 being the average of @xmath54 and @xmath55 . the level spacing @xmath72 of the oscillator potential is determined by equating the fermi energy @xmath73 of a free electron gas with the potential energy @xmath74 . assuming that the radius of a quantum dot grows with @xmath75 we have @xmath76 . consequently , we have chosen @xmath77 where the fermi energy is obtained from the mean radius @xmath78 and effective mass of typical quantum dots ; for gaas , @xmath78=320and @xmath79 yield @xmath80mev . throughout the paper we use mev as energy units , for length and tesla for the magnetic field strengths . the three normal modes which can be discerned experimentally as excitation energies in fir - spectroscopy @xcite behave in a distinctly characteristic way when the magnetic field is switched on . we recall that the values for @xmath54 and @xmath55 are fixed by minimizing @xmath46 . in fig . 1 we display typical patterns for two different electron numbers . in both cases , @xmath56 is chosen so large that @xmath81 remains zero . note that , when the magnetic field is switched on , the occupation numbers @xmath82 refer to the normal modes and can no longer necessarily be associated with an @xmath83- , @xmath84- or @xmath65-direction . = 2.8 in 0.2 cm the degeneracy for @xmath85 is clearly seen at @xmath60 whereas three distinct modes , corresponding to a deformed shape , are seen at @xmath60 for @xmath86 . the behaviour is shown for values of @xmath87 and @xmath88 . for @xmath89 the third mode ( the highest at @xmath60 ) does not interact with the applied field , therefore there is a level crossing at about @xmath90 . this becomes a level repulsion for @xmath91 as now all modes are affected by the magnetic field . as a consequence , the @xmath92-dependence is strongly pronounced for the two upper modes , while such dependence is insignificant for the lowest mode . here we find quite naturally an interpretation of avoided level crossing observed in the experiments @xcite associated with shape variations in a tilted magnetic field . we have also investigated the @xmath93-dependence of the normal modes , which is expected to become significant only for large values of @xmath94 ; the differences are small , they can not be seen in fig . we return to a particular situation where the @xmath93-dependence is important . = 2.8 in 0.2 cm there are windows of magnetic field strength for which the normal modes are virtually constant . they are discernible especially at smaller values of the magnetic field strength and are a reflection of shape changes . for @xmath85 the system is rotationally symmetric at @xmath60 . at @xmath95 it changes into a deformed shape ( @xmath62 ) which is associated with the larger derivatives of the two lower normal modes . the symmetric shape ( @xmath61 ) is now being restored in a continuous fashion when @xmath96 is further increased , the two normal modes are virtually constant during this smooth transition . the constancy of the normal modes holds strictly only for @xmath89 and can be shown analytically ; this is deferred to appendix c. at @xmath97 , where the system has eventually re - gained its symmetric shape , a second shape transition occurs for @xmath98 , which is reflected by the second sharp decrease / increase of the first / second normal mode . this pattern continues , yet it is less and less pronounced with increasing field strength . it remains to be seen whether these shape changes can be dissolved experimentally ; finite temperature could disturb this pattern . making the slab thicker , that is choosing @xmath56 smaller so as to allow occupation of the next level of the third mode ( @xmath99 ) , invokes distinct changes which could possibly be dissolved experimentally . in fig . 2 we display the effect of varying the slab thickness for @xmath85 . for clarity we focus on smaller magnetic field strength and we display only results for @xmath89 . the top figure is to facilitate comparison ; the results are a repeat of fig.(1b ) . in the middle figure the slab thickness has been decreased in such a way that the third mode becomes occupied when the field is switched on while it is unoccupied for zero field strength . as a consequence , the shape transition occurs for smaller field strength , it is here directly associated with the switch from @xmath100 to @xmath99 which is induced by the magnetic field in this particular case . the bottom figure refers to the case where @xmath99 throughout . the major effect is the lifting of degeneracy for @xmath101 . since there are effectively only 28 particles occupying the two lower modes , the confining potential is deformed . with increasing field strength the potential changes into a symmetric shape which is attained at about @xmath102 where it again undergoes a transition to a deformed shape in line with the discussion above . in this context we note that an increase of @xmath56 beyond the values used in the results presented , which means an even thinner slab , pushes the upper level further away . a truly two - dimensional setting should therefore yield only two observable levels . = 2.8 in 0.2 cm the effective occupation in the two lower modes can also be demonstrated by using @xmath103 or @xmath104 . for @xmath99 this yields the effective numbers 20 or 30 in the planary motion with the expectation that the energy minimum is adopted for a symmetric shape . this is nicely confirmed and demonstrated in fig . 3 where results for @xmath104 are presented . the top and bottom figures illustrate the cases where @xmath100 and @xmath99 , respectively . the interpretation is selfexplanatory after the previous discussions . in all the examples we see quantum mechanics nicely at work . despite the simplicity of the model , these effects should be seen in an experiment . the actual observation of the three modes is achieved by electromagnetic transitions , for instance in absorption experiments . within the single - particle model considered here transition matrix elements between the ground state and single - particle excitations are available for any single - particle operator . the electric dipole transition is expected to feature prominently . we note that this transition rules out a spin flip , which is in line with our assumption about fixed spin states . we interpret the three observed frequencies @xcite as the three normal modes . if no photon polarisation is measured in the initial and final states , the dipole transition strength is given by @xmath105 since the electric dipole operator is proprtional to @xmath13 . using eq.([lin ] ) the matrix elements are given by a sum over the appropriate entries of the matrix @xmath23 . the selection rules allow only transitions with @xmath106 by which all accessible final states are determined . note that the configuration @xmath107 is different for different magnetic field strength . we list some results in table 1 . they refer to @xmath89 and @xmath100 for the ground state . these figures do change as a function of @xmath94 , electron number and slab thickness . the results demonstrate that there is a redistribution of dipole strength due to variation of these parameters and therefore of the shape of the system . this aspect could be the subject of further experimental analysis . @xmath108 & @xmath109 & @xmath108 & @xmath110 + @xmath111 & 1.0 & 2.0 & 1.0 & 2.1 & 0.7 & 9.2 + @xmath112 & 0.7 & 1.2 & 1.2 & 3.5 & 0.7 & 9.2 + @xmath113 & 0.07 & 0.3 & 0.7 & 9.2 & 1.1 & 12.4 + * table 1 . * dipole strengths @xmath108 for various values of the magnetic field . the associated frequencies are indicated next to the strengths . the numbers are normalised to the lowest frequency transitions at zero field . the calculation of matrix elements of @xmath114 and @xmath115 which are characterized by the shape of the effective confining potential follows similar lines as for the dipole matrix elements . in table 2 we give a few values for @xmath85 and @xmath89 . note the strong deformation at @xmath116 . for larger field strengths the mean values decrease , since the effective frequencies of the confining potential are augmented by the larmor frequency ; this effect also enhances a symmetric shape to an increasing extent for increasing field strength . we stress that these values all obey the condition eq.([cond ] ) . for @xmath117 the pattern remains essentially the same except for the fact , that the shape is not symmetric for large field strength but deformed ; the degree of deformation depends on @xmath94 . this is again understood from the larmor frequencies which are now different for the different directions . this argument is nicely confirmed when using @xmath117 and @xmath118 ; now the symmetry is guaranteed by the choice @xmath119 , and , in fact , the system settles down to a symmetric configuration for large field strength . for @xmath120 the mean values are 1015 and 1069 , respectively , while for @xmath118 they are both equal to 1044 . note that such pattern for large field strength is independent of the particle number . for instance , irrespective of the strongly deformed shape for @xmath86 at @xmath60 , we find at @xmath113 also a symmetric shape for @xmath118 but a slight deformation for @xmath121 and @xmath122 . again we stress that the figures depend on the slab thickness in the spirit of the previous paragraph . @xmath123 + @xmath60 & 1167 & 1167 + @xmath116 & 770 & 1773 + @xmath113 & 981 & 981 + * table 2 . * mean square values of the extension in the @xmath4plane of the quantum dot under variation of the magnetic field strength . in view of the good qualitative agreement with experimental data @xcite we think that the model gives a fair account about the essential features of quantum dots on semiconductor interfaces . the simplicity of the soluble model allows consideration of an arbitrarily oriented magnetic field . the minimal energy requirement invokes a re - arrangement of the quantum configuration which is manifested as shell effects and hence shape changes of the quantum dot . by this mechanism we find an effective @xmath6-dependence of the fir frequencies in quantum dots ( see fig.@xmath1241 ) . an interesting aspect of the model is the constancy of the fir frequencies ( the normal modes ) under variation of the magnetic field as long as the potential is deformed . as is discussed in section 4 the system responds to the increasing magnetic field strength by changing the confining potential towards a spherical shape rather than by changing its energy . this is shown analytically in appendix c for @xmath89 where it strictly holds . it is interesting to note that for @xmath91 the statement still holds to high accuracy . as long as the shape of the effective confining potential is similar for different electron numbers , the splitting of the fir frequencies due to the magnetic field should be equally alike . when the tilting angle @xmath92 is switched on , all three modes are globally affected by the magnetic field leading to an avoided level crossing or anticrossing @xcite . a thorough experimental analysis of a variation of slab thickness , tilted angle and strength of the magnetic field , which leads to the manifestation of quantum effects such as shape variations for fixed and different numbers of electrons , could assess the reality and limitations of the model . the authors acknowledge financial support from the foundation for research development of south africa which was provided under the auspices of the russian / south african agreement on science and technology . r.g.n . is thankful for the warm hospitality which he experienced from the whole department of physics during his visit . after submission of the present paper a report about recent experiments , which confirm essential aspects of this investigation , has appeared in physical review letters , vol . 77 , 3613 ( 1996 ) by s. tarucha , d.g . austing , t.honda , r.j . van der hage and l.p . the hamilton function of eq.([ham ] ) can be written in matrix form @xmath125 where @xmath126 we aim at the quantum mechanical form @xmath127 where @xmath128 exploiting the fact that @xmath129 where @xmath25 is a 3 by 3 unit matrix , it follows that , up to normalisation factors , the matrix @xmath130 can be written as @xmath131 this implies that @xmath132 is in fact skew - diagonal as in eq.([skew ] ) , and therefore @xmath23 can be normalised such that @xmath133 . using eq.([lin ] ) , eq.([bos ] ) follows . consider the energy of the three - dimensional oscillator @xmath135 where @xmath136 . the condition @xmath137 ensures that we have a genuine two dimensional problem in that no particle occupies a quantum mode in the @xmath65-direction @xmath138 , i.e. the first level with @xmath139 lies higher than the ones which are filled for given particle number . from the condition @xmath140 it follows @xmath141 for a two - dimensional system the number of particles ( two particles per level ) is @xmath142 where @xmath143 is the shell number of the last filled shell . therefore , from the equations above it follows @xmath144 substituting eq.([nperp ] ) into eq.([wz ] ) , we obtain @xmath145 for @xmath89 the normal modes are @xmath146 the last equation shows that the largest mode @xmath147 is independent of the magnetic field strength , since @xmath56 is kept fixed . from the first two equations we obtain a relation between two sets of frequencies @xmath148 and @xmath149 which yield the same normal modes for different field strength . with the notation @xmath150 , where @xmath151 and @xmath152 refer to the different field strengths @xmath153 and @xmath154 , we obtain from the requirements @xmath155 @xmath156 to ensure that @xmath157 and @xmath158 are real , @xmath159 must obey the condition @xmath160 this means that the normal modes _ must _ change with the magnetic field strength for a spherical shape ( @xmath161 ) as is established by the results . in turn , it is possible that @xmath162 and @xmath163 do not change under variation of @xmath96 as long as @xmath164 . further , if the magnetic field strength has increased up to the value where condition ( [ ineq ] ) becomes an equality , then the spherical shape ( @xmath165 ) is attained . recall that throughout this transition from deformed to spherical shape the normal modes ( eq.([sol ] ) ) have not changed . it remains to show that this solution is in fact the minimal energy solution . for @xmath89 the explicit expressions for @xmath166 and @xmath167 read @xmath168\nonumber\\ \\ \langle g|y^2|g\rangle = { 1\over { 2m}}\left[\frac{\sigma_1}{e_1 } + \frac{\sigma_2}{e_2 } + \frac{\omega_y^2 -\omega_x^2 + 4\omega_z^2}{e_1 ^ 2 - e_2 ^ 2 } \left(\frac{\sigma_1}{e_1 } - \frac{\sigma_2}{e_2}\right)\right]\nonumber\end{aligned}\ ] ] where @xmath169 denotes the sum over all occupied single - particle levels . suppose the condition eq.([cond ] ) is fulfilled for the confining frequencies @xmath170 and @xmath171 for the value of the magnetic field @xmath172 . substituting eqs.([til ] ) into eq.([cond ] ) and taking into account that @xmath173 , we obtain @xmath174 = 0.\ ] ] from eqs.([omeg ] ) it follows @xmath175 using the result of eqs.([til]),([qur ] ) and ( [ pol ] ) , and the fact that @xmath176 and @xmath177 remain the same , we obtain @xmath178 = \nonumber\\ ( \omega_{2x}^2 - \omega_{2y}^2 ) \left[\frac{\sigma_1}{e_1 } + \frac{\sigma_2}{e_2 } + \frac{\omega_{1x}^2 + \omega_{1y}^2 + 4\omega_{1z}^2 } { e_1 ^ 2 - e_2 ^ 2 } \left(\frac{\sigma_1}{e_1 } - \frac{\sigma_2}{e_2}\right)\right]\equiv 0\end{aligned}\ ] ] where @xmath179 denotes the ground state referring to the frequencies @xmath149 and the magnetic field @xmath154 . this means that eq.([cond ] ) is fulfilled . 99 t.chakraborty , comments condens . matter phys . * 16 * 35 ( 1992 ) . kastner , rev.mod.phys . * 64 * , 849 ( 1992 ) . johnson , j.phys . : condens.matter * 7 * 965 ( 1995 ) . a. bohr and b. r. mottelson , _ nuclear structure _ ( benjamin , new york , 1975 ) , vol.2 . h. nishioka , k. hansen , and b. r. mottelson , phys . rev . * b42 * , 9377 ( 1990 ) . w. a. de heer , rev . * 65 * , 611 ( 1993 ) ; m. brack , _ ibid _ * 65 * , 677 ( 1993 ) . w.d . heiss and r.g . nazmitdinov , phys . rev . lett.*73 * , 1235 ( 1994 ) ; w.d . heiss , r.g . nazmitdinov and s. radu , phys . rev . * b51 * , 1874 ( 1995 ) ; w.d . heiss , r.g . nazmitdinov and s. radu , phys . rev . * c52 * , 3032 ( 1995 ) . comments at.mol.phys . * 31 * nos . 3 - 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a model for quantum dots is proposed , in which the motion of a few electrons in a three - dimensional harmonic oscillator potential under the influence of a homogeneous magnetic field of arbitrary direction is studied . the spectrum and the wave functions are obtained by solving the classical problem . the ground state of the fermi - system is obtained by minimizing the total energy with regard to the confining frequencies . from this a dependence of the equilibrium shape of the quantum dot on the electron number , the magnetic field parameters and the slab thickness is found . a simple shell model for quantum dots in a tilted magnetic field w.d . heiss@xmath0 and r.g . nazmitdinov@xmath1 @xmath0 centre for nonlinear studies and department of physics + university of the witwatersrand , po wits 2050 , johannesburg , + south africa + @xmath2 bogoliubov laboratory of theoretical physics + joint institute for nuclear research , 141980 dubna , russia minus.1pt pacs numbers : 73.20 dx , 73.23.ps

being a subject of practical importance , elasto - plastic deformation of dense granular media has been under the focus of engineering research for many decades if not a century @xcite . the state of geotechnical theories , however , remains confusing for outsiders : innumerable models compete , employing strikingly different expressions . in a recent book on soil mechanics , gudehus employed metaphors such as _ morass of equations _ and _ jungle of data _ to describe the situation @xcite . granular dynamics is frequently modeled employing the strategy of _ rational mechanics _ , by postulating a function @xmath0 , such that the constitutive relation , @xmath1 holds , whereby @xmath0 is a function of the cauchy stress @xmath2 , strain rate @xmath3 ( the symmetric part of the velocity gradient ) and density @xmath4 . ( more generally , @xmath5 is to be replaced by an objective derivative , such as jauman here and below . ) together with mass and momentum conservation , it forms a closed set of equations for @xmath6 and the velocity @xmath7 . hypoplasticity @xcite is such a theory , same as barodesy @xcite . both use a single constitutive equation , without the recourse to yield or potential surfaces . although elasto - plastic theories are somewhat different , einav showed that the latter can be seen as a special case of the former . all these models yield realistic accounts of the complex elasto - plastic motion , providing us with vast amount of highly condensed and intelligently organized empirical data . we concentrate on comparing gsh to hypoplasticity here , because elasto - plastic theories , with its case separations , are not easy to deal with analytically , and because a comparison to barodesy already exists . typically , the _ hypoplastic model _ starts from the rate - independent constitutive relation , @xmath8 with @xmath9 and @xmath10 functions of stress and density . though continually improving functional dependence is being proposed for them , some known and systematic shortcomings remain : 1 . the applicability of hypoplasticity is confined to uniform systems . lacking a characteristic length scale , it does not account for shear band or evanescent creep flow ( ie . the exponentially decaying penetration of flows into the static region ) . there have been two main approaches to ameliorate this : introduction of gradient terms @xcite , or addition of variables to account for the crosserat rotation and couple stress @xcite . the latter works well , but leads to a rather more complex theory . and it provokes questions about the underlying physics : if couple stress is indeed important in the shear band , because it is fluid , why then is it not important in the uniformly fluid and gaseous state of granular media or , coming to think of it , in nematic liquid crystals @xcite ? 2 . in hypoplasticity , rate - independence is an input . yet it is not a robust feature of granular behavior . fast dense flow is rate - dependent , as is the critical stress in the presence of external perturbations ( such as given by tapping ) . rate - independence needs to be explained , understood , and the extent to where it is valid clarified . elastic waves exist in granular media . yet if one tries to account for them employing eq.([3b-1 ] ) , one finds falsely that they should always be over - damped . more generally , granular media appear softer and more dissipative during elasto - plastic motion than in many other circumstances foremost elastic waves , but also incremental stress - strain relations and ratcheting . focusing on the former , hypoplasticity struggles to account for any of the latter . ( see however works on intergranular strains @xcite . ) fast dense flow and collisional flow are not accounted for . finally , hypoplasticity lacks energetics . one does not know whether a given state is stable because it has an energy minimum , or instable because the energy turns concave . nor do we know how much energy is being dissipated say in the critical state . moreover , @xmath11 has 36 elements , @xmath12 six , all functions of a tensor and a scalar . these are a lot of functions to choose . so it would be helpful if the second derivative of the energy were related to @xmath11 and/or @xmath12 ( contradicting in fact the name _ hypoplasticity _ ) . granular solid hydrodynamics ( gsh ) is derived from basic principles of physics , including conservation laws and the second law of thermodynamics , by employing _ the hydrodynamic procedure _ the result is a continuum - mechanical theory @xcite that leaves relatively little leeway , with a handful of scalar parameters to fit experiments . the most important one is the energy @xmath13 , chosen such , first of all , that elastic waves , incremental stress - strain relation and static stress distributions are well accounted for . second , @xmath13 contains the information that no stable static stress distribution exists if the density @xmath4 is too small for enduring contacts , or if the shear stress is too large for the given pressure . third , by reducing gsh to eq.([3b-1 ] ) for slow , uniform shear rates , @xmath13 s second derivative is found to yield @xmath11 and @xmath12 . the thermodynamic consistency of hypoplasticity has been demonstrated independently by fang et al , see @xcite . this was done generally , without specifying an expression for @xmath13 . the energy @xmath13 is taken as a function of the density @xmath4 , granular temperature @xmath14 and elastic strain @xmath15 . the state variable @xmath15 accounts for _ the slowly - varying , large - scaled elastic deformations of the grains , _ with the elastic stress given by the hyper - elastic relation , @xmath16 the state variable @xmath14 quantifies _ the fast fluctuating elastic and kinetic energy of the grains_. it is frequently proportional to the shear rate , @xmath17 , and a useful indicator for the system s behavior , from the quasi - static via the dense flow to the collisional one . for collisional and fast dense flow , with a shear rate of @xmath18/s and more , there is vigorous jiggling and aggitation , so @xmath14 is obviously important . for elasto - plastic motion ( usually referred to as quasi - static " but see below ) , with shear rates around @xmath19/s , @xmath14 may seem irrelevant : aside from an occasional slip , grains only participate in the motion dictated by the macroscopic shear rate , with no perceptible deviations that may contribute to @xmath14 . nevertheless , such slips lead to vibrations in the region that imply a @xmath14 still many orders of magnitude larger than the true temperature of the grains . more importantly , as we shall see , these vibrations are what lead to plasticity . if @xmath20 is yet smaller , below @xmath21/s , gsh predicts a rate - dependent transition , to irrelevance of @xmath14 and diminishing plasticity . this is supported by recent experiments @xcite . here , the system becomes truly quasi - static , better , _ quasi - elastic _ , until statics reigns , @xmath22 . in what follows , we shall briefly present gsh in sec.[gsh ] , first its three coupled relaxation equations and an expression for the elastic energy , followed by a discussion of how best to understand @xmath14 and @xmath15 , and why a second @xmath14 for the fluctuating elastic energy alone is counter - productive . in sec.[hypoplastic motion ] , we obtain the critical state as the steady - state solution of the three relaxation equations . the approach to the state , for both high and low initial densities , is given by a simple analytic solution . in addition , gsh accounts for the variously observed fact that disturbing the critical state with some tapping , its stress becomes highly rate - dependent . we then compare gsh in detail to hypoplasticity and neo - hypoplasticity , and discuss how the observed proportional paths and goldscheider rule are natural results of gsh s equations . finally , we compare four more recently proposed elastic energies , showing that all four appear to agree well , though their second derivatives differ close to yield . in sec.[aging ] , we consider remifications of gsh if the stress is held constant , stressing the difference to rate - controlled experiments , explaining why a soft spring is useful for the latter , and a triaxial apparatus for the former . then we calculate creep , shear band , angle of repose and stability ( for the infinite , uniform geometry ) . finally , we demonstrate the similarity of gsh to kamrin s nonlocal kcr model . in sec.[quasiela ] , we discuss the transition to the quasi - elastic regime for extremely slow rates . a complete set of state variables is one that uniquely determines a macroscopic state , including its energy and stress . gsh s state variables are the density @xmath4 , velocity @xmath23 , the granular temperature @xmath14 and the elastic strain @xmath15 . the latter two quantify , respectively , the temporally fluctuating elastic and kinetic energy of the grains and their slowly - varying large - scaled deformations . @xmath14 is increased by viscous heating @xmath24 , decreased by relaxation , and its balance equation is @xmath25,\ ] ] with @xmath26 the relaxation rate , and @xmath27 accounting for @xmath14-diffusion . ( the strain rate is @xmath28 , its traceless part @xmath29 , and @xmath30 . ) @xmath31 is the ambient temperature " maintained by tapping or a sound field . for a steady , uniform @xmath32 , we have @xmath33 implying @xmath34 if there is no external perturbation , and @xmath35 if the shear rate is zero . as is easy to see from eqs.([dot u],[dot u2 ] ) below , it is @xmath34 that leads to rate - independence . the easiest way to destroy it is therefore to introduce some @xmath31 , see sec.[external perturbation ] . the importance of @xmath14 in the collisional state is easy to accept . recent progresses show it exists equally in the turbulent flows of rapid dry granular avalanches @xcite . that @xmath14 is relevant even in elasto - plastic motion may surprise , yet as already discussed in the introduction , this is a result of @xmath14 , many orders of magnitude larger than the true temperature , being the physics underlying plasticity , see the next few paragraphs . the elastic strain @xmath15 alone suffices to account for elasticity and plasticity . to understand this , one needs two steps : first , granular stresses relax with a variable relaxation time . second , this relaxation is closely related to plasticity . the free surface of a granular system at rest is frequently tilted . when perturbed , when the grains jiggle and @xmath36 , the tilted surface will decay and become horizontal . the stronger the grains jiggle and slide , the faster the decay is . we take this as indicative of a system that is elastic for @xmath37 , transiently elastic for @xmath36 , with a stress relaxation rate @xmath38 . a relaxing stress is typical of any viscous - elastic or transiently elastic systems , such as polymers @xcite . in granular media , the relaxation rate is not a material constant , but a function of the state variable @xmath14 a behavior that we name _ variable transient elasticity_. for given @xmath4 , the stress @xmath39 is a monotonic function of @xmath15 ( as long as the energy @xmath13 is stable and convex , @xmath40 ) . therefore , there is no principle difference in considering either relaxation . yet since strain is a geometric quantity , stress a physical one that includes material parameters such as the stiffness ( stress dependent and highly anisotropic in granular media ) , considering strain relaxation is simpler . we take the equation of motion for @xmath15 such to reflect _ variable transient elasticity _ , finding that it suffices to capture elasto - plasticity . starting from pure elasticity , @xmath41 , adding a relaxation term , @xmath42 , we allow for two tensorial coefficients , @xmath43 and @xmath44 , to parameterize the efficacy of relaxation and deformation rate , @xmath45 if stress anisotropy changes appreciably , convective terms ( or the so - called objective time derivative ) become important , then one needs the substitution ( see the derivation in @xcite ) @xmath46 since @xmath47 , and @xmath48 , see eq.([fvs ] ) , this simple equation possesses the full hypoplastic structure , with @xmath49 given the equality of structure , gsh is as capable of accounting for elastoplasticity as hypoplasticity , if an appropriate energy expression can be found . ( allowing the density to vary yields slightly more complicated expressions . ) next , dividing @xmath15 into its trace @xmath50 and traceless part @xmath51 , denoting @xmath52 , and specifying the two tensors with two elements each , @xmath53 , we arrive at @xmath54 which may equivalently be rewritten as two relaxation equations , @xmath55 , \quad u_c\equiv\frac{1-\alpha}{\lambda f},\,\,\frac{\delta_c}{u_c}\equiv\frac{\alpha_1}{\lambda_1f } , \\\label{eqd } \partial_t\delta&+(1-\alpha)v_{\ell\ell}=-\lambda_1t_g\left[\delta-\delta_c\hat v_{ij}\hat u_{ij}\frac{fv_s}{t_g}\frac{u_s}{u_c}\right].\end{aligned}\ ] ] eqs.([tg2],[equ],[eqd ] ) are the three relaxation equations of gsh . they contain three inverse time scales : @xmath56 , a length scale @xmath57 , and the parameters @xmath58 . in dense media , @xmath26 is large , of order @xmath59/s or more . with @xmath60 , the scales @xmath61 are , for the shear rates typical of soil - mechanical experiments , orders of magnitude smaller , around 1/s for @xmath62/s the length scale @xmath57 is a few to a few tens granular diameters in dense media . the steady state solution : @xmath60 , @xmath63 and @xmath64 , implying constant elastic strain and stress at given shear rate , is clearly the critical state , see sec . [ critical state ] below . conservation of momentum and mass , @xmath65 close the set of equations , where the cauchy stress @xmath66 is @xmath67 , \quad p\equiv\sigma_{\ell\ell}/3,\end{aligned}\ ] ] see @xcite for derivation . the ( off - diagonal onsager ) coefficients @xmath68 , a necessary consequence of the same coefficients in eqs.([2c-7],[2c-8 ] ) , soften and mix the stress components . the term preceded by @xmath69 is smaller by one order in the small elastic strain @xmath15 and may usually be neglected ( though not in sec . [ hypoplasticity ] ) . @xmath68 are functions of the density for elasto - plastic motion , though they vanish identically for static stresses , see eq.([alphaela ] ) . the pressure @xmath70 is exerted by jiggling grains , and the last term is the viscous stress . both are @xmath71 for @xmath20 and relevant only for fast collisional and dense flows , giving rise to bagnold scaling there . an explicit expression for the stress via eqs.([u - stress],[sigma ] ) , is delivered by the energy @xmath13 that we take to be @xmath72 . the part relevant for elasto - plastic flow is @xmath73 . ( @xmath74 , important for collisional and dense flow , is neglected here . ) denoting @xmath75 with @xmath76 the respective traceless tensors , we take @xmath73 as @xmath77 given by the energy of linear elasticity multiplied by @xmath78 , this form is clearly inspired by the hertzian contact , though its connection to granular elasticity goes far beyond that . it includes both _ stress - induced anisotropy _ and the _ convexity transition _ ( see below ) . in addition , the expression for the elastic stress @xmath79 has been validated for : * static stress distribution in three classic geometries : silo , sand pile , point load on a granular sheet , calculated employing @xmath80 , see @xcite . * incremental stress - strain relation at varying static stresses @xcite . * propagation of anisotropic elastic waves at varying static stresses @xcite . the gsh framework is general enough that one may employ any energy expression one deems appropriate . in fact , the above expression has been chosen for simplicity and manipulative ease , with a more realistic one given in @xcite . in sec . [ constrel ] , we shall show and compare a number of different elastic energy expressions for realistic modeling . _ stress - induced anisotropy _ : in linear elasticity , @xmath81 , the velocity of elastic waves @xmath82 does not depend on @xmath83 , or equivalently , the stress . for any exponent other than two , the velocity depends on the stress , and is anisotropic if the stress is . _ convexity transition _ : there are values of stress and density in granular media for which elastic solutions do not exist : first , for densities smaller than the random loose packing density , @xmath84 , at which the grains start to loose contact with one another , no static elastic states can be maintained . second , static elastic states collapse when the shear stress is too large for the given pressure . on a tilted plane , the angle at which this happens is frequently referred to as the angle of stability , @xmath85 . the actually measured angle varies with the spacial dependence of the stress components and does not have a unique value . but in an infinite geometry , for uniform stresses , elastic solutions fail at a well - defined value . note that @xmath85 , accounting for collapses of static stresses at @xmath37 , is unrelated to the critical state , which exists only in the presence of a finite granular agitation , @xmath86 . in sec . [ sapc ] , we shall identify the angle of repose @xmath87 with the critical angle . again , the measured angle may vary because the stress is not uniform . in the space spanned by the density and stress components , the surface where the second derivative of the elastic energy changes its sign ( turning from convex to concave ) is a divide : on one side elastic solutions are stable , with grains at rest , on the other elastic solutions are instable , infinitesimal perturbations suffice to destroy any solution , and the grains are always agitated . the elastic energy of eq ( [ 2b-2 ] ) is convex only for @xmath88 it turns concave when this condition is violated . ( the second condition may be derived by considering eq ( [ 2b-1 ] ) , showing @xmath89 is minimal for @xmath90 . ) on a plane inclined by the angle @xmath91 , with @xmath92 the depth of the granular layer on the plane and @xmath93 directed along the slope , we take the stress to be @xmath94 , @xmath95 , @xmath96 . integrating @xmath97 assuming a variation only along @xmath92 , we find @xmath98 and @xmath99 . the angle of stability @xmath85 ( for infinite geometry ) is reached when the energetic instability of eqs.([2b-3 ] ) is breached . with @xmath100 denoting the yield shear stress , it is @xmath101 modifications from the proximity to walls or floor are not included here . for the parameterization of the coefficients @xmath102 , we need a second characteristic density , the _ random - close _ one , @xmath103 . it is the highest density at which grains may remain uncompressed . assuming @xmath104 is density - independent ( typically 5/3 ) , and denoting @xmath105 , we take @xmath106^{0.15},\ ] ] with @xmath107 a constant . this expression accounts for three granular characteristics : * the elastic energy is concave for @xmath84 , rendering all elastic solutions instable . * the energy is convex between @xmath108 and @xmath103 , ensuring the stability of elastic solutions in this region . in addition , the density dependence of sound velocities ( as measured by harding and richart @xcite ) is well rendered by an expression @xmath109 . ( the usual formula used to report the resuslts of @xcite implies an unphysically concave energy . ) * the elastic energy diverges , slowly , for @xmath110 , approximating the observation that the system becomes quite a bit stiffer there . because there is no space for granular rearrangements at the closed - packed density @xmath103 , plastic motions can not take place and the system should be fully elastic . taking @xmath111 for @xmath110 in eqs.([2c-7],[2c-8],[sigma ] ) , reduces gsh to simple elasticity , @xmath112 close to @xmath103 , the dependence on @xmath113 is more sensitive than any on @xmath4 directly . hence we take , with @xmath114 and @xmath115 : @xmath116 granular media should also be fully elastic for @xmath117 , see the discussion at the end of the introduction , and in sec.[quasiela ] . in this limit , the stress increases steeply with the shear rate , until the yield stress is reached , at which point the system collapses . there is no stress relaxation , hence neither a critical state . as @xmath14 and @xmath15 are novel variables that entail conceptual subtleties , a discussion is useful for those who want to look beyond the present equations . it is also useful because sun qichen and coworkers @xcite have variously proposed a twin - granular - temperature theory " that we find necessary to comment on . in a uniform medium ( such as water or copper ) there are two length scales , macro- and microscopic . all degrees of freedom may be divided into one of the two groups . a hydrodynamic theory takes the degrees of freedom from the first group as explicit variables , including mass , momentum and energy density , also the strain field in the case of solids . all degrees of freedom from the second group are taken summarily , with their contribution to the energy lumped together as heat , and characterized by the temperature @xmath118 . in granular media , there is an intermediate group , consisting of momentum and deformation of each grain . in the kinetic theory or dem , these are taken as independent variables . but a summary inclusion again suffices here , with the associated energy lumped into granular heat , characterized by @xmath14 . as the kinetic energy changes rapidly into an elastic one , and back , during a collision , both types of energy interact , equilibrate , and must be lumped into one single macroscopic variable @xmath14 . on the other hand , distinguishing @xmath14 from @xmath118 is necessary : @xmath14 is many orders of magnitude higher than @xmath118 in elasto - plastic motion , and when this is the case , granular stress relaxes , giving rise , as discussed , to plasticity . there are also grain - sized deformations , such as in force chains , that are static or slowly varying in time . their contribution is not included in @xmath14 , but in that of @xmath15 , see below . accounting for the macroscopic elastic stress that varies slowly in space , the elastic strain is also slowly varying . as energy is positive and conserved , the macroscopic energy density @xmath13 is the sum of all ( slowly varying ) mesoscopic contributions , @xmath119 . in other words , @xmath13 is the coarse - grained mesoscopic one , @xmath120 , and since the latter includes the contribution from the force chains , the former also does . it is important to realize that the elastic strain can not be obtained by coarse - graining , @xmath121 . this is because both the energy and the elastic stress are coarse - grained quantities : @xmath120 and @xmath122 . with @xmath123 and @xmath124 , we conclude : @xmath121 . sun and coworkers have written a number of papers @xcite proposing a generalization of gsh by introducing two granular temperatures , @xmath125 and @xmath126 , with @xmath125 taking account of the kinetic , and @xmath126 the elastic energy ( including contributions from force chains ) . it should be clear from the last two sections that neither is a well - behaved macroscopic variable . the temporally fast varying elastic energy from collisional deformation is necessarily part of @xmath14 , while the slowly varying contribution from force chains are part of @xmath15 . with the differential equations given and the energy density specified , gsh is a fairly well - defined theory . it contains clear ramifications and provides little leeway for retrospective adaptation to observations . as we shall see in the rest of the paper , a wide range of granular phenomena is well encoded in these equations . the three relaxation equations , ( [ tg2],[equ],[eqd ] ) , possess a steady state solution : @xmath60 , @xmath63 , @xmath64 , which is simply the critical state . with it given , we may consider the relaxation dynamics either at given shear rate , or holding the shear stress constant . in the first case , because of the small relaxation time @xmath127 , we have @xmath60 practically instantly , rendering @xmath14 dependent . then the strain relaxation equation is manifestly rate - independent , displaying the mathematical structure of hypoplasticity . the rich phenomenology observed in triaxial apparatus is then well accounted for by hypoplasticity and gsh alike . the relaxation dynamics at constant shear stresses gives rise to phenomena such as creeping , shear band , angle of repose all beyond hypoplasticity . they are considered in sec.[aging ] . the physics of the critical state is : deformed grains give rise to an elastic stress . when grains are sheared past one another , they rattle and jiggle . and when they do , the deformation and stress is slowly lost , because of the loosen contact to their neighbors . as a consequence , a shear rate not only increases the deformation , as in any elastic medium , but also decreases it . a steady state exists in which both processes balance , such that the elastic deformation and stress remain constant over time . this is the critical state . moreover , the critical stress is rate - independent , because ( 1 ) the increase in deformation is @xmath128 , ( 2 ) the relaxation is @xmath38 , and ( 3 ) @xmath20 in @xmath14 s steady state . taking @xmath129 in eqs.([tg2],[equ],[eqd ] ) for @xmath130 const , @xmath131 , we have @xmath132 with @xmath64 , @xmath133 and @xmath4 being constant , so is the associated elastic stress @xmath134 . the stress value is obtained by inserting eqs.([cs1],[cs2 ] ) into eqs.([2b-2a],[2b-2b],[2b-1 ] ) , @xmath135 the loci of the critical states thus calculated ( though employing the slightly more general energy of @xcite ) greatly resembles those calculated using either hypoplasticity or barodesy @xcite same as the coulomb yield of eq ( [ sb12 ] ) , the critical ratio @xmath136 is also frequently associated with a friction angle . since the former is relevant for vanishing @xmath14 , while the latter requires an moderately elevated @xmath20 , it is appropriate to identify one as the static friction angle , or yield angle , and the other as the dynamic one , or the critical angle . in sec . [ sapc ] , we shall present reasons why the critical angle should be identified with the angle of repose @xmath87 , the angle at which granular flows will come to a halt for uniform stress . textbooks on soil mechanics frequently state that the friction angle is independent of the density although they do not usually distinguish between the dynamic and the static one . we shall assume , for lack of better information , that both are . solving eqs.([tg2],[equ],[eqd ] ) for @xmath137 , at constant @xmath138 , with the initial conditions : @xmath139 ( same as @xmath140 ) , the relaxation into the critical state is given as @xmath141 this is an exponential decay for @xmath83 , and a sum of two decays for @xmath142 . it is useful , and quite demystifying , that a simple , analytical solution exists . typically , we take @xmath143 , as the decay of @xmath83 and @xmath144 are faster than that of @xmath145 . the prefactor @xmath145 may be negative , and @xmath146 is then non - monotonic . the associated pressure and shear stress are those of eqs ( [ 3b-4a],[3b-3c],[3b-3ca ] ) . for a negative @xmath145 , neither the pressure nor the shear stress is monotonic . for the system to complete the approach to the critical state , the yield surface of eq.([2b-3 ] ) must not be breached during the non - monotonic path . frequently , the critical state is approached at constant pressure @xmath147 , or a stress eigenvalue @xmath148 . the circumstances are then more complicated . as @xmath149 approach @xmath150 , the density compensates to keep @xmath151 const . along with @xmath4 , the coefficients @xmath152 ( all functions of @xmath4 ) , also change with time . in addition , with @xmath4 changing , the compressional flow @xmath153 no longer vanishes ( though it is still small ) . analytic solutions do not seem feasible , but numerical ones are , see fig [ fig3a ] . the parameters , labeled as i and ii , are : * @xmath154 gpa,@xmath155 , @xmath156 , * @xmath157,@xmath158,@xmath159,@xmath160 , * @xmath161 , @xmath162 , @xmath163 . if one perturbs the system , say by exposing it to weak vibrations , or by tapping it periodically , such as in a recent experiment @xcite , the critical state is modified , and a strong rate - dependence of the critical shear stress is observed . the stress decreases with the tapping amplitude , and increases with the shear rate , such that the decrease is compensated at high rates . clearly , any theory with built - in rate - independence can not account for this observation . in gsh , on the other hand , rate - independence is a result of @xmath164 , and expected to be destroyed by any ambient temperature @xmath165 , see eq.([fvs ] ) . the steady state values are then reduced to @xmath166 , @xmath167 , @xmath168 , see eqs.([equ],[eqd ] ) , implying a rate - dependence via eq.([fvs ] ) , @xmath169 if there is no tapping , @xmath170 , we retrieve the unperturbed values , @xmath171 , @xmath172 , @xmath173 . with tapping , @xmath174 decrease for increasing @xmath31 , and increase with increasing shear rate @xmath175 . see fig [ fig3b ] . by vibration as given by eq.([3b-8 ] ) [ assuming @xmath176 , see @xcite for details ] . inset is the experimental curve of @xcite , with the torque @xmath177 denoted as @xmath118 , as in @xcite . ( the stress dip at large @xmath178 , neglected here , is explained in @xcite . ) ] ( note we have only considered the critical state at given shear rate , not the approach to it . so the result holds both at given density and pressure . ) the above consideration is the basic physics of the observation of @xcite . it helps to put rate - independence , frequently deemed a fundamental property of granular media , into the proper context . a quantitative comparison is unfortunately made difficult by the highly nonuniform experimental geometry . nevertheless , some comparison , even if unabashedly qualitative , may still be useful . in @xcite , the torque @xmath177 on the disk on top of a split - bottom shear cell is observed as a function of its rotation velocity @xmath178 and the shaking acceleration @xmath179 . now , @xmath180 , @xmath181 , @xmath182 are clearly related pairs . assuming the lowest order terms suffice in an expansion , we take @xmath183 , @xmath184 . if @xmath32 were uniform , @xmath185 would also hold . since it is not , @xmath186 , @xmath187 seems plausible , because with additional degrees of freedom such as position and width of the shear band , the system has ( for given @xmath178 ) more possibilities to decrease its strain rate @xmath32 . we take @xmath188 with @xmath189 [ replacing @xmath190 with @xmath191\omega$ ] in eq.([3b-8 ] ) ] to fit fig [ fig3b ] , emphasizing that qualitative agreement exists irrespective of the fit . inserting @xmath192 , @xmath131 into eqs ( [ equ],[eqd ] ) , keeping the shear rate along one direction and allowing reversal , @xmath193 , we have @xmath194 and conclude that the reason for the difference in apparent stiffness : @xmath195 and @xmath196 , between load and unload , is that @xmath197 turns negative when the shear rate @xmath198 is reversed . the strain then relax towards the new stationary values , with a simple relaxation dynamics not at all _ history - dependent_. that loading ( @xmath199 ) and unloading ( @xmath200 ) have different slopes is frequently referred to as _ incremental nonlinearity _ in soil mechanics . it is the reason why no backtracing takes place under reversal of shear rate . the stress components @xmath201 are calculated employing eqs ( [ 2b-2b ] ) for given @xmath202 and @xmath4 . the change of the elastic shear strain @xmath203 with the total strain @xmath204 , as given by eq ( [ 3b-3 ] ) . ] as discussed around eqs.([dot u],[dot u2 ] ) , gsk possesses the hypoplastic structure for given shear rates , @xmath60 . so , this is a lucky instance in which a comparison may be made directly , by comparing the coefficients where one set is proposed from accumulated knowledge of granular behavior , while the other is given by the second derivative of the elastic energy . this is done in sec [ hypoplasticity ] . then we show that all recent hyperelastic models , either given as an elastic energy or a legendre potential , are rather similar if properly transformed . the main difference in fact stems from whether or not there are elastic instabilities . barodesy , a recent model again proposed by kolymbas @xcite , has a rather more complicated rate dependence than the one shared by hypoplasticity and gsh . but our comparison of gsh and barodesy did yield essentially quantitative agreement . the idea of barodesy is to have a more modular and better organized structure than hypoplasticity , with different parts in the constitutive relation taking care of specific aspects of granular deformation , especially that of _ proportional paths _ as summed up by the goldscheider rule . in sec . [ pep ] , we shall focus on the latter showing how the goldscheider rule and proportional paths naturally arise from gsh . writing the hypoplastic model as @xmath205 we have the dimensionless coefficients @xmath206 that are functions of @xmath4 and the 3 stress invariants : @xmath207 , @xmath208 , @xmath209{\sigma _ { ij}^*\sigma _ { jk}^*\sigma _ { ki}^*}$ ] . in @xcite , the authors present the parameter values for more than forty different granular media , with @xmath210 characterized by three functions @xmath211 and one constant @xmath212 , given as @xmath213 where @xmath214^{\beta } \frac{h_{s}}{n } \frac{e_{i}+1}{e_{i } } \left[\frac{3p}{h_{s}}\right ] ^{1-n } \left [ 3+a^{2}-\sqrt{3}a\left ( \frac{e_{i0}-e_{d0}}{e_{c0}-e_{d0}}\right ) ^{\alpha } \right ] ^{-1 } , \\ e_{d}&=e_{d0}f_{e } , \quad e_{c}=e_{c0}f_{e},\quad e_{i}=e_{i0}f_{e } , \quad f_{e}=\exp \left [ -\left ( \frac{3p}{h_{s}}\right ) ^{n}\right ] , \end{aligned}\ ] ] contain eight material constants , with @xmath215 the critical frictional angle , and @xmath216 denoting the densest , critical and loosest void ratio . for the _ stuttgart sand _ , these are given as @xmath217 note @xmath2 is here negative from that in @xcite ; note also that the stress invariant @xmath218 in @xmath219 and @xmath220 will be approximated below with @xmath221 , ie . @xmath222 , valid for axial compressions . returning to gsh , see eqs.([equ],[eqd ] ) with @xmath60 , we have four dynamic coefficients , @xmath223 and two static coefficient @xmath224 and @xmath225 . defining an operator that is valid for any function @xmath226 such as the stress @xmath66 , @xmath227we rewrite @xmath228 in the form of eq.([hyp1a ] ) to obtain @xmath229 we first parameterize the static coefficients . using the expression for the energy , eqs.([2b-2],[2b-4 ] ) , we take @xmath230 and @xmath231 , with @xmath232 , @xmath233 , @xmath234 given by table [ table ] . ( the bulk density @xmath235 does not enter the formula . ) next , we take the dynamic coefficients to be @xmath236 , where @xmath237 ; @xmath238 ; and @xmath239 . finally , we take @xmath240 ( because with @xmath241 , we obtain @xmath242 , in agreement with @xmath91 as given in table [ table ] . ) we note that the time scale @xmath243 and length scale @xmath57 of eq.([tg2 ] ) are not contained in the hypoplastic model , and their values therefore not needed for the comparison . comparison of the coefficients @xmath206 between gsh and hpm : ( 1 ) as functions of @xmath244 , at given @xmath245 and @xmath147 ; ( 2 ) as functions of @xmath147 , at given @xmath245 and @xmath246 ; ( 3 ) as functions of @xmath245 , at given @xmath147 and @xmath246 . note @xmath247 for hpm . for comments see text . ] although qualitative agreement is obvious from fig [ hypopla ] , a quantitative one is lacking . we do not take this as a serious defect of gsh , for three reasons . first , complete agreement of coefficients is probably an unnecessarily difficult task : different coefficients frequently yield similar experimental curves . second and more importantly , the parameterization of gsh , especially its energy , has been chosen stressing manipulative ease and simplicity of expressions . gsh s robust and qualitative result is the fact that hypoplastic coefficients may be obtained from the second derivative of a material - dependent scalar potential . third , starting with the gibbs potential and choosing @xmath248 , @xmath249^{1-\frac{n+\alpha}2 } , \quad u_{ij}=\frac{\partial g}{\partial\pi_{ij}},\ ] ] niemunis , grandas tavera and wichtmann most recently use its second derivative to obtain the coefficient @xmath250 of eq.([3b-1 ] ) a model that they call _ neo - hypoplasticity _ this is clearly a step that we highly welcome . calibrating the coefficients using incremental stress - strain relations , they found good agreement with observation . the next three sections are about comparing four more recent hyperelastic models , to help optimize the choice of the energy . elatic constitutive relations that possess an explicit elastic energy or gibbs potential is usually termed a hyperelastic theory . engineers tend to look for appropriate gibbs potentials , because they prefer the stress as variable . on the other hand , only the energy is conserved and useful for the hydrodynamic procedure . although one can obtain one from the other , simple energy expressions typically possess complicated gibbs potentials , and vice versa . in this section , we collect some general results connecting both , starting with the basic one of the legendre transformation:@xmath251 assuming the elastic energy is a homogeneous function of degree @xmath252 , we have @xmath253with @xmath254 a constant . this leads immediately to @xmath255(where prime @xmath256 means derivative ) . the legendre transformed gibbs potential is then @xmath257with @xmath258 taken as functions of @xmath259 , especially @xmath260 a remarkble property of the above energy expression is the simple relation , @xmath261as a result , the gibbs potential also has the factorized form:@xmath262where the dimensionless shearing factor @xmath263 is @xmath264for the hertz contact @xmath265 , we have @xmath266 . we compare four hyperelastic models , @xmath267with @xmath268 a density independent constant . gsh s elastic energy ( with @xmath212 unspecified ) was proposed and considered in 2003 , see @xcite . in our later works , we concentrated on @xmath269 , the hertz contact value , to be definite , and because hertz contact seems the appropriate granular picture . three works on hyperelastic models appeared since , all of the form eq.([w = f ] ) , by houlsby , amorosi and rojas @xcite , einav and puzrin @xcite , and , as already mentioned , as neo - hypoplasticity , by niemunis et al @xcite . we first note that the power of the `` spheric part '' @xmath270 of eq.([w = w(pi ) ] ) ) are 1.5 for both einav - puzrin and houlsby - amorosi - rojas , 1.4 for neo - hypoplasticity , and @xmath271 for gsh , ie . 5/3 for a=0.5 , and again 1.5 for a=1 . calculating the stress - strain relations for the two energies and their inverse , we have @xmath272the shearing factor @xmath273 for these models are therefore , see eq.([im = f ] ) , @xmath274 \theta ^{\frac{2+a}{-1-a } } , \\ \text{einav - puzrin } & f /f _ { 0}=\left ( 1+\widehat{\pi } _ { s}^{2}/b\right ) , \\ \text{houlsby - amorosi - rojas } & f /f _ { 0}=\left ( 1+\widehat{\pi } % _ { s}^{2}/b\right ) ^{1/2 } , \\ \text{neo - hypoplasticity } & f /f _ { 0}=\left ( 1+\widehat{\pi } % _ { s}^{2}/3\right ) ^{1-\frac{n+\alpha } { 2}},% \end{array } \label{gsh - other - im}\]]with @xmath275 and @xmath276the shearing factor of gsh explicitly shows the elastic instability that it contains : the dimensionless shear stress is restricted to @xmath277 . the root becomes imaginary at the right edge and instability sets in . the other three models remain stable for all @xmath278 . to account for the instability of a strictly static slope that is too steep , since there is no dynamics , one has only the energy to work with . a convex - concave transition very much in analogy to the van de waals theory of the liquid - gas phase transition is an appropriate candidate . therefore , we prefer to use the elastic energy that contains these instabilities . one may alternatively use brute force and put in the end of elasticity by hand . but then an abrupt transition is forced onto the system , and one can not account for any precursors . circumstances are similar if one aims to account for the lack of elastic solutions at low densities , @xmath279 , relevant for the transition from elasto - plastic motion to fast flows . ( we stress that the angle of repose is given by the critical value , see sec.[sapc ] . if connected with the appropriate dynamics , all four models can accounted for it . ) ) , and their first , second derivatives . ] taking @xmath280 , all four models have essentially the same dependence on @xmath281 , and the same ratio @xmath282 . then we only need to compare the shearing factor @xmath273 . ( we take @xmath283 for einav - puzrin and houlsby - amorosi - rajas . ) employing appropriate values for @xmath284 , we can fit the shearing factor of gsh to that of the other three , see ( a ) of fig.([neohypo ] ) , although the second derivative of gsh diverges , see ( c ) , laying bare the precursor of instabilities . as stressed in the last section , an important advantage of the energy expression , eq.([2b-2 ] ) , is its built - in shear instability , eq.(2b-3 ) , that accounts for granular media s inability to sustain arbitrarily large _ static shear stresses_. humrickhouse observed that this instability occurs too early , as compared to the _ angle of stability _ ( the angle up to which a static layer of sand will remain at rest ) . and he proposed adding a term given by the third invariant of the elastic strain , @xmath285 , to increase the predicted angle of stability@xcite , @xmath286.\ ] ] unfortunately , considering only negative values of @xmath287 , he came to the erroneous conclusion that this term does not yield any improvement . we subsequently found that it is possible to yield a realistic angle of stability of approximately @xmath288 with a positive @xmath287 . what is more , incremental stress - strain relations and granular acoustics also support the same @xmath287 @xcite . barodesy s starting point are the proportional paths as summed up by the goldscheider rule ( gr ) . taking p@xmath289p and p@xmath290p to denote proportional strain and stress paths , they are * a p@xmath289p starting from zero shear stress @xmath246 is associated with a p@xmath290p . * the same p@xmath289p starting from an arbitrary @xmath291 leads asymptotically to the same p@xmath290p obtained when starting at @xmath246 . any constant strain rate @xmath292 is a p@xmath289p : in the principal strain axes @xmath293 , a constant @xmath292 means the system moves with a constant rate along its direction , with @xmath294 , independent of time . gr states there is an associated stress path that is also a straight line in the principal stress space , that there are pairs of strain and stress paths . and if the initial stress value is not on the right line , it will converge onto it . to understand gr using gsh , we need the stationary solution for an arbitrary p@xmath289p , ie . we need to generalize the stationary solution as given by eq.([cs1],[cs2 ] ) to include @xmath295 . using the superscript @xmath296 to mean non - isochoric , we have @xmath297 where the approximate sign holds because @xmath298 . we also note that the deviatoric stress , elastic strain and strain rate share the same direction , @xmath299 , see eqs.([sigma],[2b-1],[cs2 ] ) . if the strain path is isochoric , @xmath131 , these are simply the critical state , with both the deviatoric elastic strain and stress being constant . they are hence dots that remain stationary in their respective space , given by @xmath300 and @xmath301 . if however @xmath295 , with the density @xmath302 $ ] changing accordingly , @xmath303 and @xmath304 will also change , but not the direction @xmath305 , making the dots walking down a straight line along @xmath305 . this would indeed be the first rule , except that gr states that it is the total ( and not the deviatoric ) stress that possesses a p@xmath290p . this is a slightly more involved point . with @xmath306p_\delta(\rho)[\delta_{ij}+(\pi_s / p_\delta)\hat v_{ij}],\ ] ] we again have a density dependent prefactor , @xmath307p_\delta(\rho)$ ] , multiplied by @xmath308 this factor is a constant direction , giving rise to a p@xmath290p , if we assume that the system is already in the critical state as discussed in sec.[stationary elastic solution ] ) , @xmath309 does not depending on the density . otherwise , we need to rely on @xmath309 being only weakly density dependent . the second rule is much easier to understand . given an initial elastic strain deviating from that prescribed by eq ( [ eq74 ] ) , @xmath310 , @xmath311 , eqs ( [ equ],[eqd ] ) clearly state that any deviating component will relax toward zero , implying the elastic strain and the associated stress will converge onto the prescribed line . in this section , we examine the ramification of gsh if , instead of the shear rate , the stress or elastic strain is being held constant . as we shall see , taking @xmath312 in eq.([equ ] ) results in a creep motion of the magnitude @xmath313 , such that an initial @xmath14 will co - relax with @xmath32 , at the altered rate @xmath314 . moreover , @xmath20 relax back to the equilibrium value @xmath315 only for @xmath316 , growing without bounds for @xmath317 , though a shear band solution is stable for @xmath317 . note hypoplasticity is not applicable here . this behavior has implications for the angle of repose @xmath87 ( for uniform stresses ) : as long as the shear stress is held below the critical one , @xmath316 , the @xmath20-relaxation will run its course , and the system is in a static , mechanically stable state afterwards . for @xmath318 , however , the system does not come to a standstill . therefore , defining @xmath87 same as in eq.([sb12 ] ) , but employing the critical rather than yield value , we have@xmath319 the inequality holds because the critical state is an elastic solution , while @xmath85 of eq.([sb12 ] ) is the angle at which all elastic solutions become unstable . stress - controlled experiments can not be performed in a conventional triaxial apparatus possessing stiff steel walls , because the correcting rates employed by the feedback loop to keep the stress constant are usually too strong . as a result , too much @xmath14 is excited that distorts its relaxation . the situation is then more one of consecutive constant rates , less of constant stress . instead , one may employ a soft spring to couple the granular system with its driving device , to enable small - amplitude stress corrections without exciting much @xmath14 . typical examples of stress - controlled experiments are creep ( both uniform in space and exponentially decreasing ) , shear band , also flow on an inclined plane or in a rotating drum . the flow either comes to a halt , becomes jammed at the angle of repose @xmath87 , or starts flowing from that jammed state , becomes fluidized at the angle of stability @xmath85 . for @xmath37 , the system is static , @xmath320 const , and there is no dynamics , only a stable , static elastic solution . but if @xmath36 initially , both @xmath14 and the elastic strain will relax according to eqs.([tg2],[equ],[eqd ] ) , and with them also the stress @xmath321 . maintaining a constant @xmath83 , or @xmath321 , therefore requires a compensating shear rate @xmath32 , which is observed as creep . as we shall see , the characteristic time of @xmath14 is then @xmath322 , hence rather long close to the critical stress . so the accumulated shear strain @xmath323 can be expected to be large . in a recent experiment involving a fan submerged in sand , nguyen et al . @xcite pushed the system to a certain shear stress at a given ( and fairly fast ) rate , producing an elevated @xmath14 . then , switching to maintaining the shear stress , they observed the accumulation of a large total strain @xmath324 that appears to diverge logarithmically . they called it _ creeping_. in the experiment , a very soft spring was used to couple the fan and the motor . this fact we believe is essential why the experiment turned out as observed . usually , triaxial apparatus with stiff steel walls and a feedback loop is used to keep the stress constant . the correcting rates are strong , and much @xmath14 is excited that distorts its relaxation . the situation is hence more that of consecutive constant rates , less of constant stress . a soft spring coupling the granular system with its driving device has much lower correcting rates . because of the fan , the stress distribution in the experiment is rather nonuniform , rendering a quantitative comparison to gsh difficult . nevertheless , the experiment s new and structurally robust results are worth closer scrutiny . and we shall employ gsh assuming uniformity to yield a qualitative understanding . also , we shall assume it is the elastic shear strain @xmath83 that is being kept constant , not the shear stress @xmath325 , as both cases will turn out to be rather similar . the relevant equations are still eqs ( [ tg2],[equ],[eqd ] ) ( with @xmath170 ) . at the beginning , as the strain is being ramped up to @xmath83 employing the constant rate @xmath326 , granular temperature acquires the initial value @xmath327 . starting at the time @xmath328 , the elastic strain @xmath83 is being held constant . inserting @xmath329 into eq ( [ equ ] ) , we have @xmath330 with @xmath32 the rate needed to compensate the stress relaxation . inserting this into eqs ( [ tg2],[eqd ] ) , we arrive at @xmath331 , \\\label{3b-9 } \partial_t t_g= -r_t[(1-u_s^2/u_c^2)t_g^2-\xi_t^2t_g\nabla^2t_g],\end{aligned}\ ] ] with the effective @xmath14-relaxation rate reduced from @xmath243 to @xmath332.\ ] ] assuming uniformity , both equations may be solved analytically , if the coefficients are constant . being functions of the density , they are if the density is . the stress @xmath333 will then change with time , as will @xmath146 . the first equation accounts for the exponential decay of @xmath142 , from both below and above , to the steady state value @xmath334 the relaxation is faster the more elevated @xmath14 is . employing the initial condition @xmath335 at @xmath328 , the solution to the second equation is @xmath336 because of eq ( [ 3b-7a ] ) , the same solution also holds for the shear rate , @xmath337 , with @xmath338 , @xmath339 , implying a logarithmically divergent total shear strain , @xmath340 however , we note that @xmath341 does not actually diverge , because as @xmath117 , it enters the quasi - elastic regime , see eq.([elatran ] ) below , where its relaxation becomes exponential . so even if creep is large close to @xmath342 , it comes to a halt eventually , and the system is mechanically stable . assuming a large @xmath343 , @xmath142 is quickly relaxed . fixing @xmath83 is then equal to fixing the shear stress , @xmath344 . in addition , with @xmath345 , one may rewrite the factor in @xmath346 as @xmath347 the @xmath14-relaxation is slower the closer @xmath321 is to @xmath348 , infinitely so for @xmath349 . then @xmath63 , @xmath64 , with @xmath350 a constant that does not relax . this is indistinguishable from the rate - controlled critical state , which , clearly , may be maintained also at given stress . for @xmath317 , the relaxation rate is negative , and @xmath20 will grow , or explode , seemingly without bound , see the next two sections , each with a possibility of what happens next . only a @xmath14 sufficiently large will explode , destabilizing a static shear stress exceeding @xmath348 , an infinitesimal @xmath14 will not . this is because the critical stress diverges for @xmath117 [ as can be seen calculating the critical stress employing eq.([elatran ] ) below ] , and the window between @xmath348 and @xmath351 vanishes . therefore , a static shear stress remains metastable for @xmath37 , turning instable only at the yield stress , @xmath352 , as given in eq.([sb12 ] ) . to summarize , as long as @xmath316 , both the temperature and the shear flow will relax to zero , with the rate @xmath353 $ ] . for @xmath349 , we have the rate - independent critical state . for @xmath354 , the system is meta - stable , and easily perturbed into developing a shear band as given in the next section , [ nsb ] . for @xmath355 , the stress necessarily has the full form of eq.([sigma ] ) , containing both the gaseuous pressure , viscous stress , and also the elastic part that is always in the critical state , see sec.[sapc ] . for @xmath356 , a stable , localized steady - state solution exists that we may identify as the shear band : taking @xmath357 in eq.([3b-9 ] ) , the steady - state solution for @xmath358 is @xmath359 , \\ v_s / v_s^0&=t_g / t_g^0=\sin(\pi x/\xi_{sb}).\label{nsb2}\end{aligned}\ ] ] the velocity difference across the band is @xmath360 , hence @xmath361 this is to be combined with @xmath362 for @xmath363 and @xmath364 . we note that although @xmath14 and @xmath32 are continuous at @xmath365 , neither is differentiable there . also , the density @xmath4 must be lower in the band , because only than can the shear stress @xmath321 ( that has to be uniform ) be smaller than the critical stress @xmath366 in the quiescent region , but larger in the band . if the system stays uniform at a shear stress exceeding the critical one , @xmath317 , the variables @xmath20 will grow with @xmath346 , until the gaseous pressure and viscous stress become relevant , see eq.([sigma ] ) , while the elastic stress stays in the critical state , @xmath367 this is the stress expression for fast dense flow , again a stable and uniform solution , though no longer rate - independent . we shall not dwell on it here , see @xcite for results . on a tilted plane with a ongoing granular flow and a stress as given by eq.([sigma2 ] ) , reducing the inclination angle will reduce both the shear stress and the shear rate @xmath32 . and the flow will come to a stop , @xmath368 , if the stress drops below the critical one , as discussed in sec . [ tgrelaxation ] . hence the angle of repose ( for uniform stress ) is @xmath369 , see eq.([dynfriang ] . given a static elastic state on a plane inclined by the angle @xmath91 , the angle of stability @xmath85 ( again for uniform stress ) is reached when the energetic instability of eqs.([2b-3 ] ) is breached , and the static elastic state collapses . therefore , @xmath370 , see eq.([sb12 ] ) . finally , we consider the coexistence between fast dense flow , @xmath60 , and one of static elastic stress , @xmath315 . some @xmath14 will diffuse into the static region , giving rise to an exponentially decreasing creep , as observed by komatsu et al @xcite , crassous et al @xcite . we take this liquid - solid boundary " to be at @xmath371 , with @xmath372 being solid . in the fluid phase @xmath373 , the shear rate is a constant , as is @xmath14 , providing the boundary conditions for the solid part . pressure @xmath147 and shear stress @xmath321 are uniform , as is @xmath374 , but @xmath4 is discontinuous at @xmath371 , though constant otherwise . ( the liquid density needs to be lower than that of the solid one , such that the same stress exceeds the critical one in the liquid , but is below it in the solid . ) the variable @xmath60 varies along @xmath375 . these circumstances are similar to that of sec [ tgrelaxation ] , though variation is in space rather than time . given stationarity of eqs ( [ equ],[eqd ] ) , we have @xmath376 see eqs.([3b-7a],[3b-11 ] ) . with @xmath149 fixed , so are @xmath201 , where especially @xmath377 if @xmath349 . note that the above relations imply @xmath378 . and since @xmath379 increases monotonically with @xmath380 , see eq.([2b-1 ] ) , the friction @xmath381 decreases for increasing @xmath382 . the balance equation for @xmath14 with @xmath357 , see eq.([3b-9 ] ) , yields an evanescent creep , @xmath383 , \\\label{cr2 } v_s / v_s^{0}&= t_g / t_g^{0}= \exp(-x/\xi_{cr}).\end{aligned}\ ] ] ( @xmath384 and @xmath385are the liquid values at @xmath371 . ) that the decay length @xmath386 diverges for @xmath349 is not surprising , because the whole solid region turns critical then . kamrin et al @xcite proposed a constitutive relation ( kcr ) to account for the steady flow in the split - bottom cell @xcite . a key ingredient of the theory is a new variable _ fluidity _ : @xmath387 , with @xmath388 and @xmath389 . it is taken to obey the equation @xmath390 as @xmath391 for @xmath392 , this relation is rather similar to eq.([cr1 ] ) , with @xmath393 assuming the role of @xmath14 , and the decay length diverging at the critical stress . for @xmath394 , the system is fluid , and @xmath395 essentially constant . again , @xmath14 is constant in the liquid region . kcr is well capable of accounting for the steady flow in the split - bottom cell . this is fortunate , because again , there is a symbiotic relation relation between gsh and kcr , similar to that between gsh and hypoplasticity . but there are also three differences . first , kcr assumes @xmath317 in the liquid and @xmath316 in the solid , with @xmath348 a constant . this violates momentum conservation , as the stress is continuous across the solid - fluid interface ( see also the discussion in sec.[nsb ] and [ creep motion ] ) . second , we have , for gsh , @xmath396 in liquid , and @xmath397 in solid ; yet @xmath398 on both sides for kcr . third , kamrin and bouchbinder constructed a `` two - temperature continuous mechanics '' in a recent paper @xcite , defining a configuration temperature @xmath399 and one for the vibrational degrees of freedom @xmath400 . ( microscopic degrees of freedom are not considered . there would be three temperatures if one did . ) they hypothesize that the fluidity @xmath393 may be related to @xmath399 . we disagree here . as discussed above , @xmath393 is essentially @xmath14 of gsh , which is closer to @xmath400 . _ quasi - static _ is what many in soil mechanics call the rate - independent elasto - plastic motion . the implication is : being the slowest one possible , elasto - plastic motion stays as is however slow the rate . we believe there is , at very small @xmath14 and very low rates possibly @xmath401/s , or @xmath402 ( where @xmath403 is the inertial number of the @xmath404 rheology ) , _ a rate - dependent transition to another rate - independent regime . _ if true , only the latter should be called quasi - static , or _ quasi - elastic_. the reasons for our believe are the following six points [ see also sec.[elasticlimit ] and the list after eq.([2b-1 ] ) ] : 1 . we have @xmath37 in static stress distributions , which is well accounted for by the fully elastic eqs.([sigmaela ] ) . this should remain so for very slow stress changes . the fact that cyclic load or ratcheting are less dissipative than hypoplasticity predicts @xcite may well be interpreted as the onset of a transition to quasi - elasticity . one does not need to invoke intergranular strain here . 3 . quasi - static motion a consecutive visit of static , equilibrium states should occur at @xmath37 , and be reversible . yet elasto - plastic motion occurs at elevated @xmath14 , is strongly dissipative and irreversible . reactive and dissipative terms are comparable in size , being exactly equal in the critical state . ( this is obvious only within the context of gsh , but one can identify the reactive and dissipative terms in hypoplasticity by comparing it to gsh . then the same holds true there . ) rate - independence is a hallmark of quasi - static motion . yet the rate - independence of elasto - plastic motion is ( as discussed in sec.[external perturbation ] ) easily destroyed . @xmath14 is essentially zero in elastic waves , since there is not enough time to excite appreciable amount of it . waves are well accounted for by the elastic eqs.([sigmaela ] ) , but not by hypoplasticity as they should if there were only the elasto - plastic regime . employing hypoplasticity , one finds that waves are always over - damped : starting from momentum conservation , @xmath405 , or @xmath406 , one inserts eq.([3b-1 ] ) to find the term @xmath407 yielding the velocity and the one @xmath408 damping . both terms are of the same order in @xmath409 , and given the values of the two tensors appropriate for elasto - plastic motion , they are also comparable in size , implying that elastic waves are always over - damped . ( in solids , the damping term is an order in the wave vector @xmath409 higher than the velocity term , rendering it much smaller for long enough wave lengths . this is the reason elastic waves propagate there . ) . in fact , elastic waves are a fast yet quasi - static phenomenon , same as incremental stress - strain relations . 6 . happily and perhaps most convincingly , peng zhen et al . have most recently observed indications of a rate - dependent transition away from the elasto - plastic regime @xcite . faced with the quasi - elastic response of sound waves and ratcheting , a frequent suggestion is to take a small strain increment to be elastic and free of dissipation , but a large one as elasto - plastic and dissipative . unfortunately , this is not compatible with the notion of quasi - static motion , a consecutive visit of equilibrium , static states : starting from an arbitrary static state of given stress , applying a small incremental strain that is elastic , the system ends up in another static state , with a slightly higher stress . this second state , as static as the first , is again a valid starting point any static state is . and the next small increment must again be elastic . many consecutive small increments yield a large change in strain , and if the small ones are not dissipative , neither can their sum be . in gsh , it is the strain rate , not the strain amplitude , that decides whether the response is elastic or elasto - plastic . small strain increments produced with a brief puls of shear rate will produce an elastic response , if @xmath14 does not have time to get to a sufficiently high value . there are at least two ways to observe the elusive quasi - elastic behavior , both by fixing the stress rate and keeping a low @xmath14 : note that a given stress rate may be associated with either of two shear rates , a high , elasto - plastic one at elevated @xmath14 and a low , elastic one at vanishing @xmath14 . the first method is to slowly incline a plane supporting a layer of grains . in such a situation , the shear rate remains very small , and the system starts flowing only when the yield stress is breached . a second method is to insert a soft spring between the granular medium and the driving device . if the spring is softer by a large factor @xmath212 than the granular medium ( which is itself rather soft ) , it will serve as a `` stress reservoir , '' and absorb most of the displacement , leaving the granular medium deforming at a rate smaller by the same factor @xmath212 . ( employing a feedback loop in a triaxial apparatus with stiff steel walls to maintain a stress rate will not usually work , because the correcting motion typically has strain rates that are so high , that the system slips into an elasto - plastic motion quickly . ) to account for the transition to quasi - elasticity , we need to specify how , in eqs.([2c-7],[2c-8],[sigma ] ) , @xmath410 vanish . there are scant data to rely on , but one possibility would be @xmath411 for @xmath412 , we have @xmath413 , ensuring rate - independence for the elassto - plastic regime ; for @xmath414 , we have @xmath415 vanishing with @xmath14 . instead of taking @xmath416 with @xmath14 , we choose to generalize @xmath417 to @xmath418 because this was a natural result arising during the derivation of gsh , see @xcite . for @xmath419 , we have @xmath420 quadratically small in @xmath32 , and with it also the relaxation rates @xmath38 . the ratio , in eqs.([2c-7],[2c-8 ] ) , between the irreversible , plastic term ( @xmath71 ) and the reversible , elastic term ( @xmath128 ) diminishes with @xmath421 , as has been observed in dem @xcite . taking the stress increment as a function of density , strain rate and the stress itself , the eq.(1 ) this paper starts from to set up a constitutive model , is an appropriate and physically sound way to come to terms with the complexity of triaxial results . a rather broader view of granular behavior are captured by introducing a pair of internal state variables , the elastic strain field @xmath15 and the granular temperature @xmath14 , with the first accounting for the coarse - grained deformation of the grains , and the latter accounting for their quickly changing elastic and kinetic energy . the theory that does it is called gsh , and the phenomena accounted for include static stress distributions , creep , shear band , angle of repose and stability , also the critical state under tapping , all in addition to the trixial results . kolymbas d. barodesy : a new constitutive frame for soils . geotechnique letters 2 , 1723 , ( 2012 ) , http://dx.doi.org/10.1680/geolett.12.00004 ; barodesy : a new hypoplastic approach . international journal for numerical and analytical methods in geomechanics ( 2011 ) . doi:10.1002/nag.1051 ; sand as an archetypical natural solid . in mechanics of natural solids , kolymbas d , viggiani g ( eds . ) . springer : berlin , ( 2009 ) ; 126 ; chung fang , yongqi wang , kolumban hutter . _ a unified evolution equation for the cauchy stress tensor of an isotropic elasto - visco - plastic material _ continuum mech . ( 2008 ) 19 : 423440 doi 10.1007/s00161 - 007 - 0062 - 9 chung fang , cheng - hsien lee . _ a unified evolution equation for the cauchy stress tensor of an isotropic elasto - visco - plastic material ; ii . normal stress difference in a viscometric flow , and an unsteady flow with a moving boundary _ continuum mech . 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accounting for elasto - plastic motion in granular media , hypoplasticity is a state - of - the - art constitutive model derived from data accumulated over many decades . in contrast , gsh , a hydrodynamic theory , is derived from general principles of physics , with comparatively few inputs from experiments , yet sporting an applicability ranging from static stress distribution via elasto - plastic motion to fast dense flow , including non - uniform ones such as a shear band . comparing both theories , we find great similarities for uniform , slow , elasto - plastic motion . we also find that proportional paths and the goldscheider rule used to construct barodesy , another , more recent constitutive model , are natural results of gsh s equations . this is useful as it gives these constitutive relations a solid foundation in physics , and in reverse , gsh a robust connection to reality . the same symbiotic relation exists between gsh and kcr , or kamrin s non - local constitutive relation , a model that was successfully employed to account for a wide shear band in split bottom cells . * notations : * + [ cols="<,>",options="header " , ]

an 1-month - old , 4 kg , male patient was admitted for left inguinal herniorrhaphy . his prenatal and birth history were uncomplicated and past medical history and family history were unremarkable . his vital signs were pulse rate : 160 beats per minute , respiratory rate : 42 per minute , and body temperature : 37.3. he was not premedicated . on the operating table , we began intraoperative monitoring including electrocardiography , blood pressure , and pulse oximeter . assisted ventilation with enflurane 5 vol% and oxygen 5 l / min was performed without any problem by a facemask attached to a mapleson d circuit , which was connected to the auxiliary common gas outlet of a datex - ohmeda aestiva/5 compact anesthesia machine . after muscle relaxation had been sufficiently achieved , endotracheal intubation was performed using a standard 4.5 mm internal diameter uncuffed tracheal tube . for the first 5 minutes , enflurane 2.5 vol% , nitrous oxide 2 l / min , and oxygen 2 l / min were used for maintenance of anesthesia . sevoflurane was planned to be used for rapid awakening after the surgery . from the anesthesia machine , the tec 7 enflurane vaporizer was removed from the anesthesia machine , and in its place , a sevoflurane vaporizer ( drager vapor 2000 ) was mounted . the mapleson d circuit was replaced with the semi - closed circuit and methancial ventilation with the anesthesia ventilator was started . after about 1 minute , the oxygen saturation dropped to below 90% . at this stage , the partial pressure of end - tidal carbon dioxide and heart rate were higher than before switching to sevoflurane . partial pressure of end - tidal carbon dioxide was at least 60 mmhg , and the heart rate was 160 - 170 beats per minute . the reservoir bag was not filling sufficiently , therefore , the apl valve was adjusted and the oxygen was flushed , so that the reservoir bag would fill while we raised the respiratory rate and tidal volume . then partial pressure of end - tidal carbon dioxide slowly fell to 50 - 60 mmhg . oxygen saturation was maintained at a minimum of 90% , but the capnographic waveform showed an inhaled carbon dioxide concentration greater than zero , and it seemed as if inhalation of exhaled gas caused an increase in inspired carbon dioxide . even after adjusting the apl valve , the reservoir bag did not properly fill . we continued oxygen flushing to fill the reservoir bag to supply gas while checking the machine . we checked the carbon dioxide absorber and the unidirectional valve , which were working normally . the breathing circuit was observed , but no leakage was found . the pressure of the gas supplied by the central piping system was in the normal range . if a circuit inside the anesthesia machine was leaking , a positive - pressure leak test was performed , and there were n't leaks . the breathing circuit was replaced with the mapleson d circuit again and the reservoir bag was still filled only by oxygen flushing . five minutes of checking the anesthesia machine did not help in finding the cause , so the anesthesia machine was replaced with another anesthesia machine with a sevoflurane vaporizer mounted . then breathing gas was supplied with ease . the patient 's oxygen saturation was 98% , and partial pressure of end - tidal carbon dioxide was maintained at 28 - 32 mmhg . the sevoflurane vaporizer was found to have slightly tilted to one side . when seen from the front , the right side of the sevoflurane vaporizer appeared to be slightly lifted . after attaching to the test lungs , oxygen 5 l / min was delivered , but the test lungs had barely inflated , so we could see that there was an interruption of the gas flow . after mounting the vaporizer , when seen from the front , the right side of the vaporizer was raised , as in the present case ( fig . the locking lever of the sevoflurane vaporizer was turned back , allowing for the vaporizer to be used . the vaporizer 's concentration control dial was set to 3.0 vol% and oxygen 2 l / min and nitrous oxide 2 l / min were delivered , but the test lung barely inflated . around the vaporizer , the smell of the anesthetic gas could be slightly smelled . the carbon dioxide / anesthetic agent sampling tube ( datex capnomac ultima datex - ohmeda , finland ) was disconnected from the breathing system and placed around the connection between the vaporizer and the manifold . the anesthesia monitor ( datex - ohmeda s/5 anesthesia monitor , ge healthcare , usa ) showed that nitrous oxide and sevoflurane were detected . the vaporizer was tilted at a different angle and secured , and the gas concentration was measured around the vaporizer and at the y connector . depending on the angle of the tilt , there were large differences in the concentrations of sevoflurane , oxygen , and nitrous oxide . between adjacent vaporizers , the interlock system worked fine . therefore the isoflurane vaporizer 's concentration control dial on the side could n't be turned to the on position . the anesthesia machine was reinspected by specialists on anesthesia machines , but they did not find anything functionally wrong . we trained anesthesia residents not to replace the vaporizer during surgery and to pretest the anesthesia machine thoroughly . the selectatec system and a plug - in system from drager medical are widely - used detachable mounting systems . the selectatec system consists of a pair of port valves for the positioning of each vaporizer ( fig . each vaporizer has a special mounting bracket ( containing two plungers ) which fits over the port valves . often times , vaporizers can not be exchanged between the selectatec and plug - in systems . however , the drager vapor 2000 can be compatible with various mounting systems , depending on types of mounting brackets . in the present case , the vapor 2000 had the mounting bracket plug - in s 2000 adapter , which is suitable for the selectatec system . the vapor 2000 of the present case has a locking lever , which locks the vaporizer in place so that it does not move or separate from the manifold . when it is not locked , the lever is engaged in the concentration control dial , so that it is impossible to turn on the concentration control dial . only after swinging the locking lever clockwise 90 degrees to secure the vaporizer on the manifold , the weight of the vaporizer and an o - ring around each port valve creates a seal between the mounting system and the vaporizer . when the vaporizer is turned on , the two plungers move downward , opening the valve ports and connecting the vaporizer into the fresh gas flow . when the vaporizer is turned off , it is isolated from the fresh gas flow . there are three reported cases of anesthetic vapor leakage from unlocked vaporizers . in two of them , penlon sigma delta anesthetic vaporizers were used and even when the locking lever was not locked , it was impossible to turn on the concentration control dial . on the other hand , drager vapor 2000 vaporizers and tec 7 vaporizers ' control dials can not be turned unless the locking lever is locked , increasing their safety . in the present case , however , although the vaporizer was not properly fitted on the selectatec manifold , the locking lever turned , and the concentration control dial was on . when the incident was reproduced , sevoflurane and nitrous oxide were detected near the vaporizer , suggesting a port valve opening and the leak of fresh gas containing anesthetic vapor , despite the malposition of the vaporizer . a leak from a vaporizer or its mount should be suspected if a vaporizer appears to require filling with unusual frequency , if an odor can be detected , or if there is a loss or reduction in the fresh gas flow into the breathing system after the vaporizer is turned on . when a gas leak is suspected near the vaporizer , a carbon dioxide / anesthetic agent sampling tube can be placed near the vaporizer to check if there is a leak . the effects of a leak on a vaporizer will depend on the size and location of the leak and whether or not there is a check valve at the vaporizer outlet . in addition to affecting the fresh gas composition and flow , leaks may pollute the operating room air . with a leak in a vaporizer or its mount , the machine will often function normally until the vaporizer is turned on . at that point , fresh gas flow from the machine will be lost through the leak , and the total flow will be reduced . the leak may contain little or no vapor , especially if it is in the mounting mechanism . in adults , the minimum alveolar concentration ( mac ) of sevoflurane is 1.71 , and macawake is 0.5 mac . however , the mac of a 1-month - old baby is higher than of an adult , so the possibility that the patient in the present case may have experienced awareness with recall is very high , though not provable . if there was a monitoring method for measuring the intraoperative anesthetic depth , it would have helped . however , at the present , there are still no reliable devices for monitoring anesthetic depth in infants , as in our case . although partial pressure of end - tidal carbon dioxide technically does not clearly show alveolar carbon dioxide concentration in infants , especially when using the mapleson circuit , as in our case , we suspect that hypercapnia occurred , considering the partial pressure of end - tidal carbon dioxide and the capnographic waveforms . because the reservoir bag did not fill properly and the oxygen flush bypassing the vaporizer was able to fill the respiratory bag , it was assumed that hypoventilation or rebreathing likely occurred from the reduction in the fresh gas flow , which lead to hypercapnia and low oxygen saturation on the pulse oximeter . before replacing the vaporizer , the anesthesia machine worked fine with adequate fresh gas flow and a supply of oxygen . therefore , although the gas supply was poor after having replaced the vaporizer , none of the features usually associated with hypercapnia were apparent during anesthesia : the color of the blood in the surgical field was normal ; there was no increase of a wound bleeding or oozing ; peripheral vasodilatation was not visible ; and there was no arrhythmia , except for the tachycardia , which had been present from induction . when the above situation was re - enacted , after the breathing circuit and reservoir bag were filled and the gas supply was interrupted during manual ventilation , abnormality in the reservoir bag could soon be sensed . however , there was hardly any change in the amount of air in the bellow of the anesthetic ventilator within the first 1 minute of the mechanical ventilation . afterwards the initially set tidal volume of 44 - 45 ml could be supplied for over 3 minutes . in clinical practice in a normal situation without a leak , even if the ventilator of the anesthesia machine sets the tidal volume at the constant rate , it is said that each respiratory cycle can have a difference in ventilation by dozens of ml . it is difficult to immediately notice problems when the tidal volume is small in mechanical ventilation . firstly , check that the vaporizer for the required volatile agent is fitted correctly to the anesthesia machine and that any back bar locking mechanism is fully engaged . secondly , check that the vaporizer is not tilted . when the top of the vaporizer is seen from the side , if the vaporizers are all the same model , their heights must be the same . when some vaporizers are tipped sufficiently , there is the danger of leakage of anesthetic vapor , as happened in the present case . in addition , liquid from the vaporizing chamber may get into the bypass or outlet . if this occurs , a high concentration will be delivered when the vaporizer is first used . if a vapor 2000 is operated at an angle of more than 30 degrees with the control dial not at the t setting , uncontrolled concentrations may occur . however , in the present case and reenactment , it did not appear to have tilted more than 30 degrees . fourthly , the vaporizer is located in the low pressure circuit from the flow control valves to the common gas outlet , so a leak test on the low pressure circuit must be taken . most datex - ohmeda machines , including aestiva , have a check valve , which is located just upstream of each machine 's fresh gas outlet and separates the low pressure circuit from the breathing circuit , so positive - pressure leak test does not work in detecting vaporizer leaks . instead , negative - pressure leak test should be performed . in a negative - pressure leak test one must check to see if the suction bulb can stay squeezed for at least 10 seconds . even in drager machines which do not have check valves , negative - pressure leak tests are more sensitive than positive pressure leak tests in finding low - pressure circuit leaks . the low - pressure circuit leak test should be performed daily , and each time the vaporizer is changed , performing the test is advised . many newer anesthesia workstations are capable of performing self - testing procedures , which , in some cases , may eliminate the need for the conventional negative - pressure leak testing . however , it is of importance that anesthesia care providers understand that these self - tests may not detect internal vaporizer leaks on systems with add - on vaporizers . for the self - tests to determine whether an internal vaporizer leak is present , the leak test must be repeated with each vaporizer sequentially while its concentration control dial is turned to the on position . when a vaporizer 's concentration control dial is set in the off position , it may not be possible to detect even large internal leaks . even after a proper preuse check , if anything is pushed under the vaporizer and the vaporizer is lifted even slightly from its mount , a leak may occur . we experienced a case where the vaporizer was not correctly fitted to the back bar of the anesthesia machine and the flow of fresh gas containing the anesthetic agent was interrupted . the same situation as the original event could be reenacted after we inspected the vaporizer . we were alerted that human error can reoccur , and anesthetic equipment , including the vaporizer , should not be replaced during a case , if possible . whenever a vaporizer is mounted on an anesthesia machine , a thorough checkout

we report a case of interruption in the supply of breathing gas during general anesthesia caused by malposition of the drager vapor 2000 vaporizer , which was accidentally tilted and lifted off the selectatec manifold of the anesthesia machine . because the patient was an 1-month - old infant , we could n't check if he had experienced awareness with recall . we emphasize the importance of checking the anesthetic vaporizer after mounting it on the back bar of the anesthesia machine .

according to quark models ( qm s ) @xcite , baryons can be described as the bound states of three constituent quarks . these are effective degrees of freedom that mimic the three valence quarks inside baryons , with a sea of gluons and @xmath0 sea pairs . the light baryons can then be ordered according to the approximate su@xmath1(3 ) symmetry into the multiplets @xmath2_a \oplus [ 8]_m \oplus [ 8]_m \oplus [ 10]_s$ ] . qm s explain quite well several properties of baryons , such as the strong decays and the magnetic moments . nevertheless , they predict a larger number of states than the experimentally observed ones ( the missing resonances problem ) and states with certain quantum numbers appear in the spectrum at excitation energies much lower than predicted @xcite . the problem of the missing resonances @xcite has motivated the realization of several experiments , such as cb - elsa @xcite , taps @xcite , graal @xcite , saphir @xcite and clas @xcite , which only provided a few weak indications about some states . indeed , even if several experiments have been dedicated to the search of missing states , just a small number of new resonances has been included into the pdg @xcite . there are two possible explanations to the puzzle of the missing resonances : 1 ) there may be resonances very weakly coupled to the single pion , but with higher probabilities of decaying into two or more pions or into other mesons @xcite . the detection of such states is further complicated by the problem of the separation of the experimental data from the background and by the expansion of the differential cross section into many partial waves ; 2 ) alternately , it is possible to consider models that are characterized by a smaller number of effective degrees of freedom with respect to the three quarks qm s and to assume that the majority of the missing states , not yet experimentally observed , simply may not exist . this is the case of quark - diquark models @xcite , where two quarks are strongly correlated and thus the state space is heavily reduced . in quark - diquark models , the effective degrees of freedom of diquarks are introduced to describe baryons as bound states of a constituent diquark and quark @xcite . the notion of diquark dates back to 1964 , when its possibility was mentioned by gell - mann @xcite in his original paper on quarks . since then , many papers have been written on this topic ( for a review see ref . @xcite ) and , more recently , the diquark concept has been applied to various calculations @xcite . important phenomenological indications for diquark - like correlations have been collected @xcite and indications for diquark confinement have also been provided @xcite . this makes plausibly enough to make diquarks a part of the baryon s wave function . in ref . @xcite , one of us developed an nonrelativistic interacting quark - diquark model , i.e. a potential model based on the effective degrees of freedom of a constituent quark and diquark . in ref . @xcite , it was `` relativized '' and reformulated within the point form formalism @xcite . in ref . @xcite , we used the wave functions of ref . @xcite to compute the nucleon electromagnetic form factors . here , we intend to improve the `` relativized '' model @xcite and compute the non strange baryon spectrum within point form dynamics . even if our previous results for the non strange baryon spectrum @xcite were in general quite good , here we intend to show how the introduction of a spin - isospin transition interaction , inducing the mixing between quark - scalar diquark and quark - axial - vector diquark states in the nucleon wave function , can further improve them , as already suggested in ref . scalar and axial - vector diquarks are two correlated quarks in @xmath3 wave with spin 0 or 1 , respectively @xcite . in a following paper , we will use the new wave functions , obtained by solving the eigenvalue problem of the mass operator of the present model , to compute the nucleon electromagnetic form factors and the elicity amplitudes . we consider a quark - diquark system , where @xmath4 is the relative coordinate between the two constituents and @xmath5 is the conjugate momentum to @xmath4 . we propose a relativistic quark - diquark model , based on the following baryon rest frame mass operator @xmath6 where @xmath7 is a constant , @xmath8 and @xmath9 respectively the direct and the exchange diquark - quark interaction , @xmath10 and @xmath11 stand for diquark and quark masses , where @xmath10 is either @xmath12 or @xmath13 according if the part of the mass operator diagonal in the diquark spin [ i.e. the whole mass operator of eq . ( [ eqn : h0 ] ) without the interaction @xmath14 acts on a scalar or an axial - vector diquark @xcite , @xmath15 is a contact interaction and @xmath16 is a spin - isospin transition interaction . the direct term is a coulomb - like interaction with a cut off plus a linear confinement term @xmath17 one needs also an exchange interaction @xcite , since this is the crucial ingredient of a quark - diquark description of baryons . we have @xmath18 ~~ , \label{eqn : vexchs1}\end{gathered}\ ] ] where @xmath19 and @xmath20 are the spin and the isospin operators . moreover , we consider a contact interaction similar to that introduced by godfrey and isgur @xcite @xmath21 where @xmath22 ( @xmath23 = 1 , 2 ) , @xmath24 and @xmath25 are parameters of the model . finally we consider a spin - isospin transition interaction , @xmath16 , in order to mix quark - scalar diquark and quark - axial - vector diquark states . @xmath16 is chosen as @xmath26 where @xmath27 and @xmath28 are free parameters . the matrix elements of the spin transition operator , @xmath29 , are defined as : @xmath30 } \left| s_1 , m_{s_1 } \right\rangle \neq 0 \mbox { for } s_1 ' \neq s_1 \mbox { } , \ ] ] where @xmath31 @xmath32 and the same holds for those of the isospin transition operator , @xmath33 . thus one has : @xmath34 where @xmath35 stands for the spatial wave function of the generic state , @xmath36 . the mass formula of the previous version of the relativistic quark - diquark model @xcite is @xmath37 ~~. \end{array}\ ] ] the main difference between the mass operator of eq . ( [ eqn : h0 ] ) and that of eq . ( [ eqn : rmf ] ) @xcite is the presence of the spin - isospin transition interaction @xmath38 in eq . ( [ eqn : h0 ] ) . @xmath16 is introduced to improve the description of the electromagnetic elastic form factors of the nucleon @xcite . indeed , @xmath16 makes it possible to have a nucleon wave function with a quark - axial - vector diquark component in addition to the quark - scalar diquark one . at the same time , @xmath16 significantly improves the description of the non strange baryon spectrum @xcite ( see fig . [ fig : spectrum3e4 ] ) . one can also notice that the values of the model parameters change significantly from those of ref . @xcite after the introduction of the interaction ( [ eqn : vtr(r ) ] ) into the mass formula . in particular , one can see that the masses of the two constituents ( the quark and the diquark ) are now smaller than before , which is good in a relativistic qm , and the mass difference between the scalar and the axial - vector diquark is smaller too ( it goes from 350 mev to 210 mev ) . the same happens for the string tension , that goes from 2.15 @xmath39 to 1.57 @xmath39 . it is worth noting that the number of model parameters increases only by one , since there are two new parameters , @xmath27 and @xmath28 [ see eq . ( [ eqn : vtr(r ) ] ) ] , while the parameter @xmath40 of the contact interaction [ see eqs . ( [ eqn : vcont(r ) ] ) and ( [ eqn : rmf ] ) ] has been removed . llllll + @xmath41 & @xmath42 mev & @xmath43 & @xmath44 mev & @xmath45 & @xmath46 mev + @xmath47 & @xmath48 & @xmath49 & @xmath50 & @xmath51 & @xmath52 + @xmath53 & @xmath54 mev & @xmath55 & @xmath56 mev & @xmath57 & @xmath58 mev + @xmath59 & @xmath60 & @xmath61 & @xmath62 mev & @xmath25 & @xmath63 @xmath64 + @xmath65 & @xmath66 & @xmath67 & @xmath68 mev & @xmath28 & @xmath69 @xmath70 + + finally , it has to be noted that in the present work all the calculations are performed without any perturbative approximation , as in ref . @xcite . the eigenfunctions of the mass operator of eq . ( [ eqn : h0 ] ) can be thought as eigenstates of the mass operator with interaction in a bakamjian - thomas construction @xcite . the interaction is introduced adding an interaction term to the free mass operator @xmath71 , in such a way that the interaction commutes with the non interacting lorenz generators and with the non interacting four velocity @xcite . the dynamics is given by a point form bakamjian - thomas construction . point form means that the lorentz group is kinematic . furthermore , since we are doing a point form bakamjian - thomas construction , here @xmath72 where @xmath27 is the noninteracting four - velocity ( whose eigenvalue is @xmath73 ) . the general quark - diquark state , defined on the product space @xmath74 of the one - particle spin @xmath75 ( 0 or 1 ) and spin @xmath76 ( 1/2 ) positive energy representations @xmath77 or @xmath78 and @xmath79 of the poincar group , can be written as @xcite @xmath80 where @xmath81 and @xmath82 are the four - momenta of the diquark and the quark , respectively , while @xmath83 and @xmath84 are , respectively , the @xmath85-projections of their spins . we introduce the velocity states as @xcite @xmath86 where the suffix @xmath87 means that the diquark and the quark three - momenta @xmath88 and @xmath89 , called internal momenta , satisfy : @xmath90 following the standard rules of the point form approach , the boost operator @xmath91 is taken as a canonical one , obtaining that the transformed four - momenta are given by @xmath92 and satisfy the point form relation @xmath93 where @xmath94 is the observed nucleon four - momentum and @xmath95 is its mass . it is worthwhile noting that eq . ( [ eqn : velocity - states ] ) redefines the single particle spins . having applied canonical boosts , the conditions for a point form approach @xcite are satisfied . therefore , the spins on the left hand state of eq . ( [ eqn : velocity - states ] ) perform the same wigner rotations as @xmath96 and @xmath97 , allowing to couple the spin and the orbital angular momentum as in the non relativistic case @xcite , while the spins in the ket on the right hand of eq . ( [ eqn : velocity - states ] ) undergo the single particle wigner rotations . in point form dynamics , ( [ eqn : h0 ] ) corresponds to a good mass operator since it commutes with the lorentz generators and with the four velocity . we diagonalize eq . ( [ eqn : h0 ] ) in the hilbert space spanned by the velocity states . finally , instead of the internal momenta @xmath98 and @xmath99 we use the relative momentum @xmath100 , conjugate to the relative coordinate @xmath101 , thus considering the following velocity basis states : @xmath102 and @xmath103 non strange baryon resonances ( up to 2 gev ) and the experimental masses from pdg @xcite ( boxes).,width=264 ] figure [ fig : spectrum3e4 ] and table [ tab : spectrum ] show the comparison between the experimental data @xcite and the results of our quark - diquark model calculation , obtained with the set of parameters of table [ tab : resultingparameters ] . in addition to the experimental data from pdg @xcite , we also consider the latest multi - channel bonn - gatchina partial wave analysis results , including data from crystal barrel / taps at elsa and other laboratories @xcite . in particular , these data differ from those of the pdg @xcite in the case of the @xmath104 . ccccccccc + resonance & status & @xmath105 & @xmath106 & @xmath107 & @xmath3 & @xmath75 & @xmath108 & @xmath109 + & & ( mev ) & & & & & & ( mev ) + + + @xmath110 @xmath111 & * * * * & 939 & @xmath112 & @xmath113 & @xmath114 & 0,1 & 0 & 939 + @xmath115 @xmath111 & * * * * & 1420 - 1470 & @xmath112 & @xmath113 & @xmath114 & 0,1 & 1 & 1412 + @xmath116 @xmath117 & * * * * & 1515 - 1525 & @xmath118 & @xmath119 & @xmath114 & 0,1 & 0 & 1533 + @xmath120 @xmath121 & * * * * & 1525 - 1545 & @xmath122 & @xmath119 & @xmath114 & 0,1 & 0 & 1533 + @xmath123 @xmath121 & * * * * & 1645 - 1670 & @xmath122 & @xmath119 & @xmath124 & 1 & 0 & 1667 + @xmath125 @xmath126 & * * * * & 1670 - 1680 & @xmath127 & @xmath119 & @xmath124 & 1 & 0 & 1667 + @xmath128 @xmath129 & * * * * & 1680 - 1690 & @xmath130 & @xmath131 & @xmath114 & 0,1 & 0 & 1694 + @xmath132 @xmath117 & * * * & 1650 - 1750 & @xmath118 & @xmath119 & @xmath124 & 1 & 0 & 1667 + @xmath133 @xmath111 & * * * & 1680 - 1740 & @xmath112 & @xmath113 & @xmath114 & 0,1 & 2 & 1639 + @xmath134 @xmath135 & * * * * & 1700 - 1750 & @xmath136 & @xmath131 & @xmath114 & 0,1 & 0 & 1694 + @xmath137 @xmath117 & * * * & 1820 - 1920 & @xmath118 & @xmath119 & @xmath114 & 0,1 & 1 & 1866 + @xmath138 @xmath111 & * * & 1835 - 1905 & @xmath112 & @xmath113 & @xmath114 & 0,1 & 3 & 1786 + @xmath139 @xmath121 & * * & 1880 - 1910 & @xmath122 & @xmath119 & @xmath114 & 0,1 & 1 & 1866 + @xmath140 @xmath135 & * * * & 1875 - 1935 & @xmath136 & @xmath113 & @xmath124 & 0 & 0 & 1780 + missing & & & @xmath136 & @xmath131 & @xmath114 & 0,1 & 1 & 1990 + @xmath141 @xmath129 & * * & 1950 - 2150 & @xmath130 & @xmath131 & @xmath114 & 0,1 & 1 & 1990 + + @xmath142 @xmath143 & * * * * & 1230 - 1234 & @xmath136 & @xmath113 & @xmath124 & 1 & 0 & 1236 + @xmath144 @xmath143 & * * * & 1500 - 1700 & @xmath136 & @xmath113 & @xmath124 & 1 & 1 & 1687 + @xmath145 @xmath146 & * * * * & 1600 - 1660 & @xmath122 & @xmath119 & @xmath114 & 1 & 0 & 1600 + @xmath147 @xmath148 & * * * * & 1670 - 1750 & @xmath118 & @xmath119 & @xmath114 & 1 & 0 & 1600 + @xmath149 @xmath150 & * & 1708 - 1780 & @xmath112 & @xmath113 & @xmath114 & 1 & 0 & 1857 + @xmath151 @xmath146 & * * & 1840 - 1920 & @xmath122 & @xmath119 & @xmath114 & 1 & 1 & 1963 + @xmath152 @xmath153 & * * * * & 1855 - 1910 & @xmath130 & @xmath131 & @xmath124 & 1 & 0 & 1958 + @xmath154 @xmath150 & * * * * & 1860 - 1920 & @xmath112 & @xmath131 & @xmath124 & 1 & 0 & 1958 + @xmath155 @xmath143 & * * * & 1900 - 1970 & @xmath136 & @xmath131 & @xmath124 & 1 & 0 & 1958 + @xmath156 @xmath157 & * * * & 1900 - 2000 & @xmath127 & @xmath119 & @xmath124 & 1 & 0 & 2064 + @xmath158 @xmath148 & * * & 1940 - 2060 & @xmath118 & @xmath119 & @xmath114 & 1 & 1 & 1963 + @xmath159 @xmath160 & * * * * & 1915 - 1950 & @xmath161 & @xmath131 & @xmath124 & 1 & 0 & 1958 + + ccc & & + @xmath12 @xmath162 & @xmath163 @xmath162 & source + & & + + 730 & 210 & bloch _ et al . _ @xcite + 750@xmath164860 & 10@xmath164170 & oettel _ @xcite + - & 290 & wilczek @xcite + - & 210 & jaffe @xcite + 600 & 350 & ferretti _ et al . _ @xcite + 852 & 224 & galata and santopinto @xcite + - & 200@xmath164300 & lichtenberg _ et al . _ @xcite + 770 & 140 & de castro _ et al . _ @xcite + 420 & 520 & schfer _ et al . _ @xcite + 692 & 330 & cahill _ et al . _ @xcite + 595 & 205 & lichtenberg _ et al . _ @xcite + 737 & 212 & burden _ et al . _ @xcite + 688 & 202 & maris @xcite + - & 360 & orginos @xcite + 750 & 100 & flambaum _ et al . _ @xcite + 590 & 210 & + - & 162 & babich _ et al . _ @xcite + - & 270 & eichmann _ et al . _ @xcite + 740 & 210 & hecht _ et al . _ @xcite + - & 135 & santopinto and galata @xcite + 710 & 199 & ebert _ et al . _ @xcite + & 183 & chakrabarti _ et al . _ @xcite + 780 & 280 & roberts _ et al . _ @xcite + 150 & 210 & this work + + the spin - isospin transition interaction of eq . ( [ eqn : vtr(r ) ] ) mixes quark - scalar diquark and quark - axial - vector diquark states , i.e. states with @xmath165 ( @xmath166 ) and @xmath167 ( @xmath168 ) , whose total spin ( isospin ) is @xmath169 ( @xmath170 ) . thus , in this version of the model the nucleon state , as well as states such as the @xmath171 , the @xmath172 and the @xmath173 , contains both a @xmath165 and a @xmath167 component . in particular , the nucleon state , obtained by solving the eigenvalue problem of eq . ( [ eqn : h0 ] ) , in a schematic notation can be written as : @xmath174 where @xmath175 and @xmath176 stand for the scalar and axial - vector diquarks , respectively , and @xmath177 for the quark . the radial wave functions ( in momentum space ) of the quark - scalar diquark [ @xmath178 and quark - axial - vector diquark [ @xmath179 systems of eq . ( [ eqn : nucleon.state ] ) , obtained by solving the eigenvalue problem of eq . ( [ eqn : h0 ] ) , can be fitted by harmonic oscillator wave functions the introduction of the interaction of eq . ( [ eqn : vtr(r ) ] ) determines an improvement in the overall quality of the reproduction of the experimental data ( considering only @xmath185 and @xmath103 resonances ) , with respect to that obtained with the previous version of this model @xcite . in particular , the roper resonance , @xmath115 @xmath111 , is far better reproduced than before and the same holds for @xmath128 @xmath129 . the present version of the relativistic quark - diquark model predicts only one missing state below the energy of 2 gev ( see tab . [ tab : spectrum ] ) , while three quarks qm s give rise to several missing states @xcite . for example , capstick and isgur s model @xcite has 5 missing states up to 2 gev , the hypercentral qm @xcite has 8 , glozman and riska s model has 4 @xcite and the u(7 ) model has 17 @xcite . the only missing resonance of our model , @xmath186 , lies at the same energy of the three star state @xmath141 @xmath129 , which was previously a two star state of the pdg @xcite . indeed the two resonances , @xmath186 and @xmath141 @xmath129 , have the same quantum numbers , except for the total angular momentum , because their spin ( @xmath114 ) and orbital angular momentum ( 2 ) are coupled to @xmath187 or @xmath130 . thus , to split the two resonances one should take a spin - orbit interaction into account . while the absolute values of the diquark masses are model dependent , their difference is not . comparing our result for the mass difference @xmath163 between the axial - vector and the scalar diquark to those reported in tab . [ tab : massediquarkaltri ] , it is interesting to note that our estimation is comparable with all the others . such evaluations come from phenomenological observations @xcite , lattice qcd calculations @xcite , instanton liquid model calculations @xcite , applications of dyson - schwinger , bethe - salpeter and faddeev equations @xcite and constituent quark - diquark model calculations @xcite . the whole mass operator of eq . ( [ eqn : h0 ] ) is diagonalized by means of a numerical variational procedure , based on harmonic oscillator trial wave functions . with a variational basis made of @xmath188 harmonic oscillator shells , the results converge very well . we think that the present paper can be helpful to the experimentalists in their analysis of the properties of the @xmath189 and @xmath190-type resonances . our quark - diquark model results may be compared to those of three quarks qm s , showing a larger number of missing resonances . our results may then help the experimentalists to distinguish between the two interpretations for baryons . finally , in the future we will use our quark - diquark model wave functions to compute the nucleon electromagnetic form factors and the helicity amplitudes of baryon resonances @xcite . m. ferraris , m. m. giannini , m. pizzo , e. santopinto and l. tiator , phys . b * 364 * , 231 ( 1995 ) ; m. m. giannini , e. santopinto and a. vassallo , eur . phys . j. a * 12 * , 447 ( 2001 ) ; e. santopinto , a. vassallo , m. m. giannini and m. de sanctis , phys . c * 76 * , 062201 ( 2007 ) ; phys . c * 82 * , 065204 ( 2010 ) . l. y. .glozman and d. o. riska , phys . * 268 * , 263 ( 1996 ) ; l. y. .glozman , w. plessas , k. varga and r. f. wagenbrunn , phys . rev . d * 58 * , 094030 ( 1998 ) ; r. f. wagenbrunn , s. boffi , w. klink , w. plessas and m. radici , phys . b * 511 * , 33 ( 2001 ) ; s. boffi , l. y. glozman , w. klink , w. plessas , m. radici and r. f. wagenbrunn , eur . j. a * 14 * , 17 ( 2002 ) . a. v. anisovich , v. v. anisovich , m. a. matveev , v. a. nikonov , a. v. sarantsev and t. o. vulfs , int . j. mod . a * 25 * , 2965 ( 2010 ) [ int . j. mod . a * 25 * , 3155 ( 2010 ) ] . j. ferretti , a. vassallo and e. santopinto , phys . c * 83 * , 065204 ( 2011 ) ; j. ferretti , int . j. mod . * 26 * , 1460117 ( 2014 ) . f. e. close and a. w. thomas , phys . b * 212 * , 227 ( 1988 ) . m. neubert and b. stech , phys . b * 231 * , 477 ( 1989 ) ; phys . rev . d * 44 * , 775 ( 1991 ) . a. bender , c. d. roberts and l. von smekal , phys . b * 380 * , 7 ( 1996 ) . w. h. klink , phys . rev . c * 58 * , 3617 ( 1998 ) ; phys . c * 58 * , 3587 ( 1998 ) ; r. f. wagenbrunn , s. boffi , w. klink , w. plessas and m. radici , phys . b * 511 * , 33 ( 2001 ) ; e. p. biernat , w. h. klink and w. schweiger , few body syst . * 49 * , 149 ( 2011 ) ; w. n. polyzou _ et al . _ , few body syst . * 49 * , 129 ( 2011 ) . v. v. flambaum , a. holl , p. jaikumar , c. d. roberts and s. v. wright , few body syst . * 38 * , 31 ( 2006 ) . r. babich , n. garron , c. hoelbling , j. howard , l. lellouch and c. rebbi , phys . d * 76 * , 074021 ( 2007 ) . g. eichmann , i. c. cloet , r. alkofer , a. krassnigg and c. d. roberts , phys . c * 79 * , 012202 ( 2009 ) . d. b. lichtenberg , phys . rev . * 178 * , 2197 ( 1969 ) . m. m. giannini , e. santopinto and a. vassallo , eur . j. a * 12 * ( 2001 ) 447 . l. y. glozman , d. o. riska , phys . * 268 * ( 1996 ) 263 ; l. y. glozman , w. plessas , k. varga , r. f. wagenbrunn , phys . rev . d * 58 * ( 1998 ) 094030 .

the relativistic interacting quark - diquark model of baryons , recently developed , is here extended to introduce a spin - isospin transition interaction into the mass operator . the refined version of the model is used to calculate the non strange baryon spectrum . the results are compared to the present experimental data .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Fairness for the Military Reserve Act of 1999''. SEC. 2. FINDINGS. Congress finds the following: (1) There are approximately 1,382,000 members of the seven reserve components of the Armed Forces (the Army Reserve, the Army National Guard of the United States, the Naval Reserve, the Marine Corps Reserve, the Air Force Reserve, the Air National Guard of the United States, and the Coast Guard Reserve). (2) During fiscal year 1998, reserve component members performed 13,000,000 person-days of military duty, roughly double the level performed during 1994 and the equivalent of 35,000 active component members. (3) Reserve component members are being called upon to serve in a greater number of overseas peacekeeping, humanitarian, and similar missions, and for longer periods of time, than ever before in peacetime, as shown by the following: (A) 8,338 reserve component personnel served in Haiti during the period from September 1994 through September 1999, constituting up to 6 percent of the Armed Forces personnel participating in Operation Support/Uphold Democracy during that period. (B) 32,022 reserve component personnel served in Bosnia during the period from December 1995 through September 1999, constituting up to 33 percent of the Armed Forces personnel participating in Operation Joint Endeavor/Guard/Forge during that period, and in January 2000, an Army National Guard brigadier general will assume command of Task Force Eagle in Tuzla, Bosnia- Herzegovina. (C) 9,752 reserve component personnel served in Iraq during the period from October 1997 through September 1999, constituting up to 5 percent of the Armed Forces personnel participating in Operation Northern and Southern Watch during that period. (D) 9,576 reserve component personnel served in Kosovo during the period from April 1999 through September 1999, constituting up to 22 percent of the Armed Forces personnel participating in Operation Allied Force during that period. (4) Recent reports and studies have noted the importance of the reserve components, as shown by the following: (A) The report of the Department of Defense Quadrennial Defense Review conducted in 1997 stated that ``Reserve components have become an ever larger percentage of the Total Force and are essential participants in the full spectrum of operations, from the smallest of smaller-scale contingency operations to major theater war . . . Reserve forces are part of all war plans. No major operation can be successful without them.''. (B) The National Defense Panel, in its report issued in 1997, called for the ``full integration'' of the reserve components with active duty forces and specifically called on the Army to rely more upon its reserve components to ``reduce pressure on the active Army''. (C) The Reserve Component Employment 20005 Study, issued on August 8, 1999, concludes that ``while much progress has been made in recent years to ensure equity in the benefit packages that are provided to AC [active component] and RC [reserve component] personnel, the study determined that disparities continue to exist for RC personnel.''. (5) Secretary of Defense William Cohen has made ``quality of life'' issues for all servicemembers a major priority for the Department of Defense. (6) The significant recent increase in overseas active-duty assignments for reserve component members warrants enhancement of military benefits for the Nation's citizen soldiers. (7) Those enhancements should include-- (A) extending eligibility of reserve component members for space available (``Space-A'') travel on military aircraft to travel outside the continental United States (``OCONUS''); (B) providing for reserve component members traveling away from their homes for inactive-duty training to be eligible for billiting in military quarters on the same basis as members on active duty; (C) raising the annual reserve retirement point maximum from 75 to 90; and (D) extending the legal services provided by the Department of Defense to reserve component members. SEC. 3. TRAVEL BY RESERVES ON MILITARY AIRCRAFT OUTSIDE CONTINENTAL UNITED STATES. (a) Space-Required Travel for Travel to Duty Stations OCONUS.--(1) Subsection (a) of section 18505 of title 10, United States Code, as added by section 517(a) of the National Defense Authorization Act for Fiscal Year 2000 (Public Law 106-65), is amended-- (A) by inserting ``annual training duty or'' before ``inactive-duty training'' both places it appears; and (B) by inserting ``duty or'' before ``training if''. (2) The heading of such section is amended to read as follows: ``Sec. 18505. Reserves traveling to annual training duty or inactive- duty training OCONUS: authority for space-required travel''. (b) Space-Available Travel for Members of Selected Reserve and Gray Area Retirees.--Chapter 1805 of such title is amended by adding at the end the following new section: ``Sec. 18506. Space-available travel: Selected Reserve and reserve retirees under age 60; dependents ``(a) Eligibility for Space-Available Travel.--The Secretary of Defense shall prescribe regulations to allow persons described in subsection (b) to receive transportation on aircraft of the Department of Defense on a space-available basis under the same terms and conditions (including terms and conditions applicable to travel outside the United States) as apply to members of the armed forces entitled to retired pay. ``(b) Persons Eligible.--Subsection (a) applies to the following persons: ``(1) A person who is a member of the Selected Reserve in good standing (as determined by the Secretary concerned). ``(2) A person who is a member or former member of a reserve component under age 60 who, but for age, would be eligible for retired pay under chapter 1223 of this title. ``(c) Dependents.--A dependent of a person described in subsection (b) may be provided transportation under this section on the same basis as dependents of members of the armed forces entitled to retired pay.''. ``(d) Limitation on Required Identification.--Neither the ``Authentication of Reserve Status for Travel Eligibility'' form (DD Form 1853), nor or any other form, other than the presentation of military identification and duty orders upon request, or other methods of identification required of active duty personnel, shall be required of reserve component personnel using space-available transportation within or outside the continental United States.''. (2) The table of sections at the beginning of such chapter is amended by striking the item relating to section 18505 and inserting the following new items: ``18505. Reserves traveling to annual training duty or inactive-duty training OCONUS: authority for space- required travel. ``18506. Space-available travel: Selected Reserve and reserve retirees under age 60; dependents.''. (c) Effective Date.--Regulations under section 18506 of title 10, United States Code, as added by subsection (a), shall be prescribed not later than 180 days after the date of the enactment of this Act. SEC. 4. BILLETING SERVICES FOR RESERVE MEMBERS TRAVELING FOR INACTIVE DUTY TRAINING. (a) In General.--(1) Chapter 1217 of title 10, United States Code, is amended by adding at the end the following new section: ``Sec. 12604. Attendance at inactive-duty training assemblies: billeting in Department of Defense facilities ``(a) Authority for Billeting on Same Basis as Active Duty Members Traveling Under Orders.--The Secretary of Defense shall prescribe regulations authorizing a Reserve traveling to inactive duty training at a location more than 50 miles from that Reserve's home to be eligible for billeting in Department of Defense facilities on the same basis as a member of the armed forces on active duty who is traveling under orders away from the member's duty station. ``(b) Proof of Reason for Travel.--The Secretary shall include in regulations under subsection (a) means for establishing that a Reserve seeking billeting in Department of Defense facilities under that subsection is traveling for attendance at inactive duty training at a location more than 50 miles from that Reserve's home.''. (2) The table of sections at the beginning of such chapter is amended by adding at the end the following new item: ``12604. Attendance at inactive-duty training assemblies: billeting in Department of Defense facilities.''. (b) Effective Date.--Section 12604 of title 10, United States Code, as added by subsection (a), shall apply with respect to periods of inactive duty training beginning more than 180 days after the date of the enactment of this Act. SEC. 5. INCREASE IN MAXIMUM NUMBER OF RESERVE RETIREMENT POINTS THAT MAY BE CREDITED IN ANY YEAR. Section 12733(3) of title 10, United States Code, is amended by striking ``but not more than'' and all that follows and inserting ``but not more than-- ``(A) 60 days in any one year of service before the year of service that includes September 23, 1996; ``(B) 75 days in the year of service that includes September 23, 1996, and in any subsequent year of service before the year of service that includes the date of the enactment of the Reserve Component Equity Act of 1999; and ``(C) 90 days in the year of service that includes the date of the enactment of the Reserve Component Equity Act of 1999 and in any subsequent year of service.''. SEC. 6. AUTHORITY FOR PROVISION OF LEGAL SERVICES TO RESERVE COMPONENT MEMBERS FOLLOWING RELEASE FROM ACTIVE DUTY. (a) Legal Services.--Section 1044(a) of title 10, United States Code, is amended-- (1) by redesignating paragraph (4) as paragraph (5); and (2) by inserting after paragraph (3) the following new paragraph (4): ``(4) Members of a reserve component not covered by paragraph (1) or (2), but only during a period, following a release from active duty under a call or order to active duty for more than 29 days under a mobilization authority (as determined by the Secretary of Defense), that is not in excess of twice the length of time served on active duty.''. (b) Dependents.--Paragraph (5) of such section, as amended by subsection (a), is amended by striking ``and (3)'' and inserting ``, and (4)''. (c) Implementing Regulations.--Regulations to implement the amendments made by subsections (a) and (B) shall be prescribed not later than 180 days after the date of the enactment of this Act.

Directs the Secretary of Defense to prescribe regulations to allow the following persons to receive transportation on Department of Defense (DOD) aircraft on a space-available basis under the same terms and conditions that apply to members of the armed forces entitled to retired pay: (1) members of the Selected Reserve in good standing; (2) a former reserve member under 60 years of age who would be eligible for retired pay except for being under such age; and (3) dependents of the above. Limits the required identification for such travel. Directs the Secretary to prescribe regulations authorizing a reserve member traveling to inactive duty training at least 50 miles from home to be eligible for billeting (housing) in DOD facilities on the same basis as active-duty personnel traveling under orders away from such member's duty station. Requires proof of the reason for such travel. Increases the maximum number of reserve retirement points that may be credited in a year for reserve service from 75 to 90 for years during and subsequent to the date of enactment of the Reserve Component Equity Act of 1999. Authorizes the Secretary of the military department concerned to provide civil legal services to reserve personnel (and their dependents) not otherwise entitled to such services, but only during a period following a release from active duty under a call or order to such duty for more than 29 days under a mobilization authority that is not in excess of twice the length of the duty period served.

the ultrastructural effects of mineral dusts on a macrophagelike cell line ( p388d1 ) were studied by transmission electron microscopy . the cells were found to contain virus particles which probably did not exert a cytopathic effect toward the cells . during mitosis the asbestos fibers appeared to be pushed to the periphery of the cell . the distribution of the asbestos in the p388d1 cells was similar to that seen previously in cultured peritoneal macrophages , and it was concluded that the cytotoxic effect of asbestos towards the cells was due to mechanical effects , e.g. , by penetrating structures such as the nucleus or phagosomes , by preventing the ordered movement of organelles with the cell or by disrupting the cytoskeletal framework of the cell.imagesfigure 1.figure 2.figure 3.figure 4.figure 5.figure 6 .

OKLAHOMA CITY (AP) — A man fired from an Oklahoma food processing plant beheaded a woman with a knife and was attacking another worker when he was shot and wounded by a company official, police say. Employees and friends wait behind a tape for word of loved ones as police investigate an incident at Vaughn Foods on Thursday, Sept. 25, 2014 in Moore, Okla. Police Friday a man who had been fired from... (Associated Press) Trucks are parked in a parking lot at Vaughn Foods in Moore, Okla., Friday, Sept. 26, 2014, the site of an incident where a man beheaded a woman with a knife and was attacking another worker when he was... (Associated Press) This photo provided by the Oklahoma County Sheriff’s Office shows reserve sheriff's Deputy Mark Vaughan. Authorities said Friday, Sept. 26, 2014, a man fired from an Oklahoma food processing plant beheaded... (Associated Press) This Oct. 18, 2011 photo provided by the Oklahoma Department of Corrections shows Alton Nolen, of Moore, Okla. Prison records indicate that Nolen, the suspect in the beheading of a co-worker at an Oklahoma... (Associated Press) Moore, Okla., Police Sgt. Jeremy Lewis talks Friday, Sept. 26, 2014 about a man fired from a Moore, Okla., food processing plant that beheaded a woman with a knife and was attacking another worker when... (Associated Press) Employees and friends look on for loved ones as police investigate an incident at Vaughn Foods on Thursday, Sept. 25, 2014 in Moore, Okla. Police said Friday a man who had been fired from the food processing... (Associated Press) Employees wait in the parking lot as police investigate a shooting at Vaughn Foods on Thursday, Sept. 25, 2014 in Moore, Okla. Police said Friday a man who had been fired from the food processing plant... (Associated Press) This March 21, 2011 photo provided by the Oklahoma Department of Corrections shows Alton Nolen, of Moore, Okla. Prison records indicate that Nolen, the suspect in the beheading of a co-worker at an Oklahoma... (Associated Press) Employees wait in the parking lot as police investigate an incident at Vaughn Foods on Thursday, Sept. 25, 2014 in Moore, Okla. Police said Friday a man who had been fired from the food processing plant... (Associated Press) In this Wednesday, Oct. 20, 2010 photo, Vaughan Foods President Mark Vaughan poses for a photo at the food processing plant, in Moore, Okla. Authorities said Friday, Sept. 26, 2014, a man fired from an... (Associated Press) Moore Police Sgt. Jeremy Lewis said his department is waiting until Alton Nolen, 30, regains consciousness to arrest him on unspecified charges. He said Nolen severed the head of 54-year-old Colleen Hufford during Thursday's attack at the Vaughn Foods plant in Moore, a suburb of Oklahoma City. "Yes, she was beheaded," Lewis told The Associated Press. Lewis said Nolen then stabbed Traci Johnson, 43, a number of times before Mark Vaughan, a reserve sheriff's deputy and the company's chief operating officer, shot him. "This was not going to stop if he didn't stop it. It could have gotten a lot worse," Lewis said. Lewis said his department asked the FBI to help investigate after co-workers told investigators that Nolen had recently started trying to convert several employees to Islam. He said police asked the FBI to look into Lewis' background because of the nature of the attack, which followed a series of high-profile videotaped beheadings by Islamic State militants. In a statement, FBI Special Agent in Charge James E. Finch said the motive for the attack had not been determined, but that there is no reason to believe there was a threat to anyone else. A law enforcement official familiar with the investigation told the AP that there was indication that Nolen was a Muslim convert and was trying to convert others to Islam. However, the officials said there is thus far no connection to terrorism and no evidence of any suspicious travelling Nolen might have done. The official, who spoke on condition of anonymity because the investigation is ongoing, said Nolen had a Facebook page that was of potential interest to investigators, but that "there doesn't appear to be any nexus to terrorism right now." But the official also said investigators were still looking into Nolen's background. Johnson and the suspect were hospitalized and in stable condition Friday, Lewis said. According to Oklahoma Department of Corrections records, Nolen served time in prison and is on probation for assault and battery of a police officer. He also was convicted of cocaine possession with the intent to distribute in 2011. The records show that Nolen has what appear to be religious tattoos, including one referencing Jesus and one in Arabic that means "peace be with you." Lewis said Nolen was fired in a building that houses the company's human resources office, then immediately drove to the entrance of the business. He said he didn't know why Nolen was fired. A company spokeswoman said the company was "shocked and deeply saddened" by the attack. ___ Associated Press writer Eric Tucker in Washington contributed to this report. ||||| UPDATED 9/29/2014 6:50 P.M. MOORE, Okla. – Cleveland County District Attorney Greg Mashburn says his office will be ready to file official charges on Alton Nolen Tuesday afternoon. MOORE, Okla. – Police are charging a man accused of beheading a woman at Vaughan Foods in Moore, Okla. The Moore Police Department says charges filed against Alton Alexander Nolen will include first-degree murder and assault with a deadly weapon. Law enforcement will officially file the paperwork in the District Attorney’s office Monday. Alton Nolen is also accused of stabbing another woman before being shot himself by an Oklahoma County Sheriff’s Office reserve deputy, Mark Vaughan, who is also the company CEO. Nolen, a recent convert to Islam, allegedly attacked a woman Thursday at a Vaughan Foods processing plant, soon after he learned he’d lost his job there. Police said he walked into the front office and attacked one of the first people he encountered, Colleen Hufford, 54. He severed her head with a knife and then attacked 43-year-old Traci Johnson. Johnson has been released from the hospital after being treated for numerous wounds. Nolen, 30, was interviewed by investigators on Friday. Police have not revealed what he said. The FBI said there are no indications linking Thursday’s attack to terrorism. In the Middle East, ISIS, which calls itself the Islamic State, has drawn world attention with videotaped beheadings. Click here to read more on the FBI’s findings. Vaughan Foods released the following statement on Monday: “Employees are returning to work at Vaughan Foods. Each shift begins with group gatherings. These conversations allow us to come together as a team and draw strength from each other. Company leadership and crisis counselors are taking this opportunity to reinforce the importance of each employee’s well-being. The loss of our Vaughan Foods family member remains very much in our hearts and minds. We are encouraged by the strength and resilience we see in our team. Employees continue to make a conscious effort to process last week’s tragedy by seeking out our trained crisis counselors, who remain available at any time.” Please enable Javascript to watch this video MOORE, Okla. - Officials with the Moore Police Department say the FBI is now involved in the investigation related to a brutal attack of workers at a food distribution plant. Sgt. Jeremy Lewis says the alleged suspect, 30-year-old Alton Nolen had just been fired when he drove to the front of the business, hit a vehicle and walked inside. He walked into the front office area where he met 54-year-old Colleen Hufford and began attacking her with a knife. Sgt. Lewis confirms the type of knife used in the attack is the same kind used at the plant. Lewis confirms that Hufford was stabbed several times and that Nolen "severed her head." At that point, Lewis claims Nolen met 43-year-old Traci Johnson and began attacking her with the same knife. Officials say at that point, Mark Vaughan, an Oklahoma County reserve deputy and a former owner of the business, shot him as he was actively stabbing Johnson. "He's, obviously, a hero in this situation," Sgt. Lewis said, referring to Vaughan. "It could have gotten a lot worse." Authorities say it appears Nolen was attacking employees at random. The Medical Examiner confirmed Hufford's cause of death on Friday. "Ms. Hufford’s cause of death is decapitation due to multiple sharp force trauma to neck. Manner of death is homicide," said Amy Elliott with the Medical Examiner's Office. Johnson was released from the hospital on Saturday. Family members say she is "sore" but is doing well. The FBI is now looking into Nolen's background after his former co-workers said he tried to convert them to Islam after converting to the religion himself. Lewis says the FBI is working in conjunction with the Moore Police Department, especially when it comes to the religious aspect of the case. At this time, it is not known if the suspect's beliefs played a role in the attack. Adam Soltani, the executive director of the Council on American Islamic Relations in Oklahoma, says Nolen's actions are condemned by the Muslim community and his faith should not be connected to this horrific crime. "It's really unfortunate that there's a lot of attention on Muslims these days for actions of people who are either part of extremist groups or who have extreme ideas. However, Islam is clear on what it stands for. Islam stands for peace, Islam stands for justice, Islam stands for love for humanity, compassion and mercy. What this gentleman did in Moore, which is inhumane and barbaric, is definitely not a representation of what our faith teaches and we hope and pray that justice will be brought against the perpetrator soon, so that the victims and their families can find some sort of solace in that justice," he said. Soltani added that what Nolen did is the "antithesis of every teaching of the Islamic faith." Vaughan Foods released the following statement about the attack: "On behalf of everyone at Vaughan Foods, we are shocked and deeply saddened by the events of today. Our thoughts and prayers go out to the families and friends of the team member we lost and all those affected. Our focus is on the safety and well-being of our employees. We will provide counseling and support for our team members and support each other through this difficult time. We are working with authorities on this active investigation and ask that you direct your questions to local law enforcement." Danielle Katcher, spokesperson from Vaughan Food, added to the company's statement saying: "Today, we mourn the loss of an extraordinary member of the Vaughan Foods family, and continue to support both the physical and emotional healing process of all those impacted by this week's violence. Our focus remains on the safety and healing of our employees. Since Friday morning, trained counselors have been available to all employees at our Moore facility. This confidential counseling service is providing individualized assistance to those struggling to make sense of this painful experience. We will continue to work through this extremely difficult time together, as a team, and are grateful for our strong network of family, friends and co-workers. We would like to thank law enforcement for their swift response, and the community for the continued outpouring of support and condolences." The Moore Police Department released the 911 tapes associated with the attack. Please enable Javascript to watch this video 911 Caller: "Shut the door, shut the door!" Dispatcher: "Moore 911, where is your emergency?" 911 Caller: "Vaughan Foods, Moore, Oklahoma, 216 N.E. 12th St. We have.." Dispatcher: "What's going on there?" 911 Caller: "We have someone attacking someone in the building. I was just informed. I'm in the.." Dispatcher: "Okay, where are they at?" 911 Caller: "Inside, are they in the office? They're in the office, front office of the building. Yeah, we can hear a lot of screaming. We're actually in a different office but someone just came in here yelling." Dispatcher: "315. Okay, do you know where they're at in the building?" 911 Caller: "In the front of the building, there's our main entrance." Dispatcher: "Okay, do you know where he is at in the plant?" 911 Caller: "We know that he's loose. He has stabbed someone." Dispatcher: "Yeah, we've got medical en route for them. 911 Caller: "Okay." Dispatcher: "Is anybody with him or do you know?" 911 Caller: "Hold on, my (garbled.) Dispatcher: "Respond on lacerations. Vaughan Foods, 216, go ahead sir, N.E. 12th." 911 Caller: "I'm going to put you on speakerphone for one second, okay?" Dispatcher: "Standby on a map. Page 1608, time out." 911 Caller: "Okay, so we don't know where the person went and he went through our front office, went through the shipping office and stabbed a woman in our customer service department." Dispatcher: "Okay, did he know her? Do you know, is that who he was arguing with? Is she an employee?" 911 Caller: "She is an employee, yeah." Dispatcher: "Okay, thank you." 911 Caller: "Lock that door." Dispatcher: "Yeah, go ahead lock everybody in there if you can." 911 Caller: "Yeah, we're trying. Okay, can you hear this in the background?" (yelling) Dispatcher: "Is that him? He's back?" 911 Caller: "Yeah, it sounds like he's running around out here." (loud bangs) 911 Caller: "And that, that's a gun shot." Dispatcher: "Got a gun shot. Units responding to Vaughan Foods, be advised we do now have gunshots. Okay, do you know where he's at now?" 911 Caller: "He's in the hallway, outside of the center of the building." Dispatcher: "Maybe in the hallway in the center of the building. And how many more shots have you heard?" 911 Caller: "We've heard three." Dispatcher: "Three shots?" 911 Caller: "Now I'm hearing somebody yelling in the hallway, stay down." Dispatcher: "There's another subject yelling in the hallway. Units be advised that there's another subject yelling in the hallway. Still same amount of injuries." 911 Caller: "Stay down, stay down." UPDATE 9/26 2:48 p.m.: Sheriff John Whetsel, with the Oklahoma County Sheriff's Office, is speaking out about the deadly attack at a food distribution facility in Moore on Thursday. On Friday afternoon, Whetsel released the following statement: "Today, my thoughts and prayers are with family and friends of the innocent victim who was murdered and the second innocent victim who was injured in violent knife attacks at Vaughan Foods in Moore, Oklahoma on September 25, 2014. These were heinous criminal acts that were ended by the quick response of Oklahoma County Reserve Deputy Sheriff Mark Vaughan. I am extremely proud of the actions of Deputy Vaughan and I am convinced those actions saved the lives of several other employees. Mr. Vaughan, who serves as CEO of Vaughan Foods, was at work and when he was alerted that a man was attacking employees with a knife, Mark didn't hesitate. He quickly responded. Mark put an end to the threat by shooting the suspect and saving the life of a second victim who was being actively attacked by the suspect. There is every reason to believe that the lives of untold others were saved who would have been targeted by the suspect if it hadn't been for Deputy Vaughan's actions. Mark Vaughan has been with the Oklahoma County Sheriff's Office since June 2010. During that time he has completed the 10-month Reserve Deputy Basic Academy as well as other extensive law enforcement training. Mark is currently assigned to the Patrol Division, is a member of the FAST Team (Fast Action Support Team) and is a highly trained member of the Tactical Team. Reserve Deputies serve a very important role in the ability of the Oklahoma County Sheriff's Office to provide law enforcement services and protection to the citizens of Oklahoma County. Reserve Deputies are citizens who attended rigorous law enforcement training and volunteer their time to serve. Mark Vaughan is an example of just how significant these men and women are to our citizens. Yesterday lives were saved and a criminal threat ended by the quick and unselfish response of Mark Vaughan. Only one word can express my feelings of the actions of Reserve Deputy Mark Vaughan. Without regard to himself or his safety, yesterday Mark Vaughan became a "HERO" while doing the job he was sworn to do- protecting others." In addition to Whetsel's statement, the Federal Bureau of Investigation's Oklahoma City Division released its own statement on the incident. "The FBI will continue to assist the Moore Police Department and will provide whatever resources are necessary in this investigation. The motive is undetermined at this time and until all the facts have been gathered, we are not in a position to comment further. There is no information currently in our possession to indicate there is any additional threat to the citizens of Oklahoma related to this incident." ||||| The man on the 911 call spoke in an urgent voice, the terror still unfolding around him. “Shut the door. Shut the door,” the man can be heard saying. “What is your emergency?” the dispatcher asks. “We have someone attacking someone in the building,” the man says. It was 4:05 Thursday, a sunny and warm fall afternoon. Alton Alexander Nolen, a 30-year-old ex-convict, had been fired from his job just moments before at Vaughan Foods, a food processing company located at 216 NE 12 in Moore. Now, police say, an angered Nolen was taking his vengeance. Nolen stormed out of the human resources office, located in a separate building on the southeast side of the property, got in his car and drove the short distance to the processing plant’s main warehouse building, striking another vehicle along the way, police said. He entered the warehouse. There he encountered Colleen Hufford, a 54-year-old grandmother, who last year lost her home in the May 20 Moore tornado. A family friend said Hufford had worked in the office at Vaughan Foods for about five years. “She was a very kind, forgiving person. Friendly. Little shy, but once she got to know you, she’d talk your leg off,” said family friend Joe Weinzetl. Nolen, described by authorities as a practicing Muslim who had recently been trying to convert co-workers, stabbed Hufford and then beheaded her. He used a knife that police said he may have used at his job cutting lettuce and vegetables. Next, he turned on another employee, Traci Johnson, 43, of Oklahoma City, slashing her with the same knife. From inside a locked office, the caller tells the 911 operator, “We can hear a lot of screaming.” “We know that he’s loose. He has stabbed someone.” Now another employee got on the line, telling the 911 operator that the attacker had gone through the front office, shipping office and customer service department where he’d stabbed one of the employees. By now, three minutes had passed. On the recording of the 911 call, a man, believed to be Nolen, can be heard yelling in the background. “Is that him?” the dispatcher asks. “He’s back?” “Yeah, it sounds like he’s running around out here,” the caller tells her. Moments later, at least two loud pops and a woman’s frightened voice can be heard. “And that, that’s a gunshot,” the caller tells the dispatcher. Lives saved Shortly after Nolen stormed out of the human resources office, an employee had telephoned the on-site office of Mark Vaughan, the company’s chief operating officer, telling Vaughan that Nolen was out of control. Vaughan, an Oklahoma County reserve deputy sheriff, arrived at the main building carrying a rifle. There, Vaughan confronted Nolen, then shot and wounded him. Authorities say Vaughan’s quick actions saved the life of Johnson and possibly others. Moore police responded to what they believed was an active-shooter situation. Once they arrived, they found the victims and evacuated the building. The department’s tactical team then searched the building. Sgt. Jeremy Lewis said Moore police responded rapidly and followed procedures “to a T.” Both Johnson and Nolen were taken to OU Medical Center Thursday. Authorities said Friday their injuries were not life-threatening. Traci Johnson’s grandfather, Carroll McGinnis, of Cushing, said Friday that he heard from other family members that his granddaughter was doing well after Thursday’s attack. “I think she’s going to be OK. They cut her on the face and stabbed her a time or two,” McGinnis said. He said Johnson is from Cushing but had lived in Oklahoma City for several years. He didn’t think she had been working at Vaughan Foods very long. Nolen will remain under police guard until doctors approve his release. Once released, he will be taken to the Cleveland County jail, Moore Police Sgt. Lewis said. Friday night, the Office of the Chief Medical Examiner issued a statement saying Hufford‘s death was a homicide, the result of decapitation due to multiple sharp force trauma to the neck. FBI called Moore police have asked the FBI to help investigate the case, including looking into Nolen’s background, in part because of his religious activities. It’s unclear when Nolen converted to Islam, but prison records list his religious affiliation as Islam. Nolen has the words “as-salaamu alaikum,” Arabic for “peace be with you,” tattooed on his abdomen, according to Corrections Department records. He has “Jesus Christ” tattooed on his chest, “Judah” on his left arm and praying hands on his right arm. On a Facebook page where Nolen calls himself Jah’Keem Yisrael, the main photo shows several heavily armed Islamic fighters. The page also includes several pictures of Osama bin Laden as well as a photo posted March 7 of a beheading. James E. Finch, special agent in charge of the FBI’s Oklahoma City office, said a motive for Thursday’s attacks remains undetermined. “There is no information currently in our possession to indicate there is any additional threat to the citizens of Oklahoma related to this incident,’’ Finch said. The Islamic Council of Oklahoma condemned Thursday’s attacks, saying Oklahoma Muslims are “shocked, horrified and saddened about the loss of innocent life and the injuries.” “Workplace and school killings are tragic but are unfortunately becoming more common in America,” the organization said in a prepared statement. “Every loss is felt by family, friends and strangers. Scholars and everyday Muslims maintain that no religious or political goal is ever achieved by these acts.” Saad Mohammad, a spokesman for the Islamic Society of Greater Oklahoma City, said leaders of the society’s mosque in northwest Oklahoma City are on alert and taking security precautions to protect against retaliation. Mohammad said anti-Muslim sentiment could be heightened due to several recent beheadings of Westerners and other violence being perpetrated overseas by the Islamic extremist group, ISIS. “They have this ISIS thing on their minds and now this guy has brought it to America,” Mohammad said. On Friday afternoon, a few delivery trucks entered and exited the Vaughan Foods facility. Television satellite trucks and media vehicles parked along the east side of the property but weren’t allowed on site. A few employees could be seen entering and leaving the premises, occasionally standing under a canopy to smoke cigarettes and talk with co-workers. The company offered trained counselors to all employees at the Moore facility Friday. In a written release Friday night, the company stated, “We will continue to work through this extremely difficult time together, as a team … We would like to thank law enforcement for their swift response, and the community for the continued outpouring of support and condolences.” Criminal past Court records show that Nolen has three felony convictions. In the latest case, he pleaded guilty in 2011 to assaulting a highway patrol officer while fleeing arrest. It took four law enforcement agencies, two helicopters and 12 hours to apprehend Nolen who fled into a wooded area. The two other convictions involved drug crimes. Corrections Department spokesman Jerry Massie said Nolen had no misconduct record during his time in the Oklahoma prison system. He was discharged in March 2013, but is still on probation. On Facebook, Paige Nolen, who is believed to be Alton Nolen’s sister, wrote: “He is alive and doing well. Thanks to all praying warriors out there friends and family. To god be the glory! My bro is alive and just know that the devil is a lie. Please continue prayers.” Contributors: Staff Writers Graham Lee Brewer, Jane Glenn Cannon, Nolan Clay, Andrew Knittle, Jennifer Palmer and Jonathan Sutton

– As horrific as yesterday's beheading of an office worker was in Oklahoma, police say they would have had more more victims had a company executive not stepped in to stop the assailant, reports NewsOK. Mark Vaughan, chief operating officer of Vaughan Foods in Moore, also happens to be a reserve deputy sheriff. When he learned of the attack, he left his office, saw a man stabbing a second woman, and shot the assailant twice with a rifle, police say. Suspect Alton Nolen, 30, survived and is under police watch at a hospital. Police say he earlier killed and decapitated 54-year-old Colleen Hufford and was attacking a second employee when he got shot. The second woman suffered non-life-threatening injuries. Nolen had gotten fired from the company moments before the attack occurred. The police have brought in the FBI to help investigate the killing because employees say that Nolen was a Muslim convert who had been trying to convert others to Islam, reports AP. Authorities haven't confirmed that and haven't made a connection between the suspect's religious beliefs and the attack. “It’s really unfortunate that there’s a lot of attention on Muslims these days for actions of people who are either part of extremist groups or who have extreme ideas," the executive director of the Council on American Islamic Relations in Oklahoma tells KFOR-TV. "What this gentleman did in Moore, which is inhumane and barbaric, is definitely not a representation of what our faith teaches." Nolen previously served time in prison for assaulting a police officer, reports AP.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Defense Worker Dislocation Act''. SEC. 2. RETRAINING. (a) In General.--Section 325(a) of the Job Training Partnership Act (29 U.S.C. 1662d(a)) is amended-- (1) in the first sentence, by striking ``From the'' and inserting ``(1) From the''; (2) by inserting after the first sentence the following: ``The Secretary may make the grants in any State in which the Governor has received a notification regarding a closure, cancellation, or reduction under section 4201(b) of the Defense Economic Adjustment, Diversification, Conversion, and Stabilization Act of 1990, and in which eligible employees have received notification of warning from their employer regarding the closure, cancellation, or reduction.''; and (3) by striking the last sentence and inserting the following: ``(2) To be eligible to receive a grant, an entity referred to in paragraph (1) shall submit an application to the Secretary at such time, in such manner, and containing such information as the Secretary may require, including the date on which the entity anticipates that the eligible employees affected will lose employment, and information relating to the notifications described in paragraph (1). ``(3) The Secretary shall approve or deny the application not later than the later of-- ``(A) 15 days after the date described in paragraph (2); or ``(B) 30 days after submission of the application.''. (b) Use of Funds.--Section 325 of such Act is amended by striking subsection (c) and inserting the following new subsection: ``(c)(1) Grants under subsection (a) may be used-- ``(A) to provide retraining, as described in section 314(d) or to update existing skills, with respect to an eligible employee described in subsection (f)(3)(A); and ``(B) notwithstanding any other provision of this Act, to pay for the Federal share of providing such retraining with respect to an employee of eligible defense contractors or eligible defense subcontractors if-- ``(i) the employee is currently involved in defense work; ``(ii) the retraining is designed to enable employee to achieve placement and retention in unsubsidized employment that involves nondefense work and in which the employee has not previously been substantially engaged; and ``(iii) the employer certifies that the employee would have become an eligible employee described in subsection (f)(3)(A), without the retraining. ``(2) The Federal share of providing the retaining described in paragraph (1)(B) shall be 75 percent.''. (c) Administration.--Section 325 of such Act is amended by-- (1) redesignating subsection (d) as subsection (e); and (2) by inserting after subsection (c) the following new subsection: ``(d)(1)(A) Not later than 15 days after the approval of an application of an entity under subsection (a)(3), the Secretary shall make available to the entity 50 percent of the amount of the grant. ``(B) On submission of the report described in subparagraph (C), the Secretary shall make available to the entity the remainder of the grant. ``(C) Each recipient of a grant under this section shall prepare and submit to the Secretary a report containing such information as the Secretary may require regarding eligible employees participating in the program, and the current education skill levels and occupational abilities of the employees. ``(D) Grants made under this section may be used to reimburse an entity for funds expended under another provision of this title for the purposes described in subsection (c). ``(E) Grants made under this section to an entity shall be in addition to assistance under any other provision of this title, and shall be made without regard to whether the entity has expended funds available under such provision. ``(2)(A) For purposes of the requirements of title I, and in particular of section 141(a), an eligible employee shall be deemed to be a person who can benefit from, and is most in need of, services provided under this section. ``(B) Notwithstanding any other provision of this Act, in prescribing performance standards under section 106 for this section, the Secretary shall prescribe standards solely based on placement and retention in unsubsidized employment. Services provided to eligible employees under this section consistent with individual readjustment plans shall be presumed to be in compliance with such standards unless any person demonstrates that the services are not in compliance.''. (d) Definitions.--Section 325 of such Act is amended by adding at the end the following new subsection: ``(f) For purposes of this section: ``(1) The term ``eligible defense contractor'' means a person that is-- ``(A) awarded a contract by the Department of Defense; and ``(B) affected by a notification issued under section 4201(b) of the Defense Economic Adjustmnent, Diversification, Conversion, and Stabilization Act of 1990. ``(2) The term ``eligible defense subcontractor'' means a subcontractor-- ``(A) for a person awarded a contract by the Department of Defense; ``(B) that is affected by such a notification; and ``(C) that is certified by a State agency described in section 3306(e) of the Internal Revenue Code of 1986. ``(3) The term `eligible employee' means-- ``(A) an eligible dislocated worker, including such a worker of an eligible defense contractor or eligible defense subcontractor, who has been terminated or laid off, or has received a notice of termination or layoff, as a consequence of reductions in expenditures by the United States for defense or by closures of United States military facilities, as determined in accordance with regulations of the Secretary; and ``(B) an employee described in subsection (c)(1)(B). ``(4) The term `employer' includes an eligible defense contractor and an eligible defense subcontractor.''.

Defense Worker Dislocation Act - Amends the Job Training Partnership Act (JTPA) to revise eligibility requirements for the Defense Conversion Adjustment Program (program). Authorizes the Secretary of Labor to make program grants to specified types of eligible entities in any State in which: (1) the Governor has received a notification regarding a closure, cancellation, or reduction under the Defense Economic Adjustment, Diversification, Conversion, and Stabilization Act of 1990; and (2) eligible employees have received a notification of warning from their employer regarding such closure, cancellation, or reduction. Allows use of program grant funds for retraining or to update existing skills with respect to an eligible dislocated worker, including an employee of an eligible defense contractor or subcontractor, who has been terminated or laid off, or received notice of termination or layoff, as a consequence of reductions in U.S. expenditures for defense or by closures of U.S. military facilities. Allows program grant funds also to be used to pay for the Federal share (75 percent) of such retraining with respect to an employee of eligible defense contractors or subcontractors if: (1) the employee is currently involved in defense work; (2) the retraining is designed to enable the employee to achieve placement and retention in unsubsidized employment that involves nondefense work and in which the employee has not been previously engaged; and (3) the employer certifies that the employee would have become an eligible dislocated worker without such retraining. Revises program administration provisions. Allows program grants to be used to reimburse an entity for funds expended under JTPA provisions for Dislocated Workers. Provides that program grants shall be: (1) in addition to assistance under any other JTPA Dislocated Worker provision; and (2) made without regard to whether the entity has expended funds available under such other provision. Deems to be an eligible employee (for purposes of JTPA general requirements) a person who can benefit from, and is most in need of, program services. Directs the Secretary to prescribe program performance standards solely on the basis of placement and retention in unsubsidized employment (notwithstanding other JTPA provisions for performance standards).

silicon photomultipliers ( sipm ) are arrays of microcells of avalanche photo diodes ( apd ) connected in parallel and operated in geiger mode . they are characterized by timing of the order of @xmath4ns , with recovery times comparable to those of conventional phototubes . their gain factors of @xmath5 make them proper detectors for the detection of single photons hitting their active surface . their compactness and robustness allow to easily deploy sipm sensors on wide area telescope focal planes . their endurances to the night sky background light will allow to extend the telescope duty cycles acquiring quality data also during bright moon nights . sipm are therefore ideal sensors to equip the cta telescope cameras . sipm sensors have been developed by fbk@xcite in cooperation with infn as a proposal to equip the focal plane of cta telescopes . the latest sensor technology is based on 6x6mm@xmath6 p@xmath7-n sipms with microcell area of 30x30@xmath8 , sensitive to uv light and with breakdown voltages of @xmath428v , named high density nuv ( nuv - hd , figure[fig : sipm ] ) . the sensors have been characterized in the clean room and laboratory tests with pulsed uv sources and in dark conditions , using a transimpedence amplifier asd - ep - eb - n developed by advansid for the evaluation of the fbk sensor performances@xcite . the devices show competitive performances with respect to commercial devices , with a photon detection efficiency ( pde ) better than 40% in the expected uv signal range , single photoelectron noise rate below 100khz / mm@xmath9 at operating temperature and an optimal signal / noise for single photoelectron detection ( figure[fig : perf ] ) . the nuv - hd sipm sensors described in the previous section have been selected to assemble a possible upgrade of the focal plane camera of the prototype schwarzschild - couder telescope ( psct)@xcite , a cta medium size telescope ( mst ) prototype that will be operated at the fred lawrence whipple laboratory in arizona ( us ) in 2017 . the current camera design is based on hamamatsu s12642 - 0404pa-50(x ) mppc modules . the improved sensitivity measured for the nuv - hd sipm sensors has driven the efforts to integrate this technology to the psct camera . infn together with italian universities has designed and developed multi - sipm modules compatible with the already existing psct camera mechanics and readout . each module is made of four independent units ( or quadrants ) , each equipped with 16 nuv - hd sipms . the units have been designed to cover a 26.9x26.9mm@xmath9 area , corresponding to 53.8x53.8mm@xmath9 area of each module . each 64 sipm module will be arranged in a chessboard geometry with a module - module distance of 200@xmath10 m . the mechanical layout of the 16 sipm pcb is shown in figure[fig : pcb ] . with this configuration , the module pitch is 54 mm , while the sensor pitch is 6.75 mm , equally distributed all over the camera area . the nominal distance between sensor edges amounts to 510@xmath10 m . the bias voltage is applied at the back common cathode of all the 16 sensors , while the signal of each sensor is individually readout through a wire - bond connection between a conductive pad placed on the sensor edges and a bonding pad placed on the pcb and in conductive connection with the back of the pcb . before the placement of sipms , the pcb are thermally coupled to the copper blocks used as mechanical structure of the pcb and to radiate excess heat produced by the electronics . this step is crucial to achieve the best possible alignment of the modules when assembled in the camera mechanics . custom mechanical holders with holes and position pins allow to achieve a 50@xmath10 m accuracy for the alignment in the xy plane . a pick & place " machine is used to dispense the conductive glue to the pcb top layer metal pads and place the sipm sensors on the pcb . some examples of the products of assembly tests are shown in figure[fig : matrix ] . preliminary tests to validate the accuracy of the pick & place machine have shown a sensor alignment better than @xmath11 and a board flatness better than @xmath12 , well within the requirements ( figure[fig : alignment ] ) . after the sipm placement , the 16 sensor bonding pads are wire bonded to the pcb bonding pads and then tested to check the quality of the conductive connections . the characteristic current - voltage ( iv ) curves of each sensor of the unit are measured in series using a custom switching matrix with digital control of the multiplexer . an example of iv curves for 16 sensors of one unit is shown in figure[fig : iv ] . + a layer of uv transparent epoxy is finally dispensed over the sipm to protect the wire bonds and the sensor surface . since the uv light absorption probability increases with depth , the epoxy layer has to be dispensed with the highest possible level of uniformity over all the module , avoiding border effects . preliminary tests of epoxy deposition and transmittance are currently ongoing , with encouraging prospectives . to validate the camera concept , 9 quadrants of the psct camera will be initially equipped with the camera solution described in the previous section . a total of 100 modules , corresponding to 1600 sipm sensors , will be tested in the infn laboratories and a selection of 36 modules will be mounted on the psct camera . a daq system based on a 16-channel charge amplifier has been developed for this purpose . a pole - zero cancellation circuit , optimized to achieve a 20 ns pulse with an amplitude of 4mv / p.e . and to minimize the electronics signal offset , is applied to reshape the signal@xcite . the output signal of the preamplifier board is subsequently readout with a v792 qdc module . preliminary tests of the preamplifier performances have been performed on a 16-channel prototype unit using a pulsed 380 nm light@xcite . the response of each single sensor has been studied by covering all other channel with a custom mask . the results show an evident quantization of the signal down to the single photoelectron , with a signal / noise ratio of @xmath45 . subsequently , the whole daq system has been tested illuminating the whole unit and acquiring the 16 signals with the qdc module . the signal is integrated over a time window of 100ns . each adc channel corresponds to a charge of @xmath4100pc . the results show a good uniformity in the response of the 16-channel unit , with a slightly lower gain and signal / noise ratio probably introduced by the intrinsic impedences of the setup ( see figure[fig:16chan ] ) . further efforts are ongoing to optimize and calibrate the daq setup towards the massive 1600 sensor tests . sipm sensors present suitable properties to equip the focal planes of imaging air cherenkov telescope cameras , allowing to improve the camera performance with respect to the use of standard photomultipliers . the latest technology achieved in the sipm sensors produced by fbk has driven the design of a possible upgrade of the focal plane camera of the psct cta telescope , whose current design is using an older generation of hamamatsu mppc . modules made of 16 sipm sensors have been designed to be compatible with the current camera mechanics and readout , and are currently being assembled . preliminary tests and verifications have confirmed the quality of the assembly and of the performance of the modules . in 2017 at least 36 units of 16 sensors each will be ready for integration with the psct telescope camera and tested on site . 00 g. maier et al . , arxiv:1508:06042 www.cta-observatory.org ( 2016.04.06 ) t. hassan et al . , arxiv:1508:06075 https://www.fbk.eu http://advansid.com a.n . otte et al , arxiv:1606.05186 a.n . otte et al , arxiv:1509.02345 c. bonavolont et al . , `` development of a charge preamplifier to improve nuv - hd sipm performance '' , cris 2016 d. simone et al . , `` development of a sipm based camera for cherenkov telescope array '' , cris 2016

the cherenkov telescope array ( cta ) consortium is developing the new generation of ground observatories for the detection of ultra - high energy gamma - rays . the italian institute of nuclear physics ( infn ) is participating to the r&d of a possible solution for the cherenkov photon cameras based on silicon photomultiplier ( sipm ) detectors sensitive to near ultraviolet ( nuv ) energies . the latest nuv - hd sipm technology achieved by the collaboration of infn with fondazione bruno kessler ( fbk ) is based on @xmath0 micro - cell sensors arranged in a @xmath1 area . single sipms produced by fbk have been tested and their performances have been found to be suitable to equip the cta cameras . currently , infn is developing the concept , mechanics and electronics for prototype modules made of 64 nuv - hd sipms intended to equip a possible update of the cta prototype schwarzschild - couder telescope ( psct ) telescope . the performances of nuv - hd sipms and the design and tests of multi - sipm modules are reviewed in this contribution . = 1 the analysis of the properties of high energy cosmic ray photons with energies above 100gev provide important information for the understanding of the high energy astrophysical phenomena and for investigating unsolved problems of particle physics , like the nature of dark matter and the mechanisms after which cosmic rays are accelerated up to 10@xmath2ev energies . the cherenkov telescope array ( cta ) consortium is developing the new generation of imaging atmospheric cherenkov telescopes ( iacts ) detectors . iacts detect the uv cherenkov light produced in the atmospheric showers initiated by cosmic rays : the analysis of the cherenkov light at ground allows to identify electromagnetic showers initiated by cosmic ray photons and @xmath3 with energies above 10gev and to measure the energy and incoming direction of such cosmic rays . the cta collaboration aims to extend the flux sensitivity of the current iact telescope generation by at least one order of magnitude in the core energy range and to extend the energy range beyond 100 tev to explore the gamma - ray sky at the highest energy regime and below 100gev to overlap with the current space - borne gamma - ray detectors . to achieve this goal , the cta collaboration will install telescopes with different acceptances and configurations in two arrays , one in southern and one in the northern hemisphere to maximize the coverage of the sky . ( see figure[fig : cta ] ) the cta observatory will be operated as a proposal - driven observatory , openly accessible to a large scientific community .

likert , and likert - type , responses are popular psychometric item scoring schemes for attempting to quantify people s opinions on different issues . the likert scale originated with rensis likert ( 21 ) , and has a long history of use in kinesiology research ( 13 , 14 , 24 ) . the long - running issue with likert - type scales and ordinal responses is the appropriate statistical treatment of these data . if the data are ordinal , then non - parametric statistics are typically considered the most appropriate option for analysis . this includes not only likert - type scales but also other ordinal measures such as the rating of perceived exertion ( rpe ) . for example , investigators have published research on the rating of perceived exertion ( 3 , 4 ) , with almost all treating these data as interval rather than ordinal ( 1 , 2 , 1012 , 15 ) . whereas the classic likert - scale items had 5 possible responses , the rpe scale as 14 choices ( 3 ) and the modified rpe has 10 ( 4 ) . this is an issue because parametric statistics are generally perceived as being more statistically powerful than non - parametric statistics . knapp argues that this is not the case , regardless of perception ( 19 ) . however , the simplicity of non - parametric tests ( e.g. , the signed - ranks test ) , biases some to assign a higher status to parametric analyses than to non - parametric . most importantly , the goal of research is to produce valid results useful for advancing the field , and valid statistical conclusions require valid statistical analyses . the purpose of this research note is to review current thinking on the treatment of data generated from likert - type , and other ordinal responses and provide evidence for using alternatives . in a likert - response item with choices varying from agree to strongly agree , it would appear to be in the mind of the research participant whether or not there is an equal distance between each of these choices ( 9 ) . note that the above response options are balanced in that the items to the left of neutral have an equal number of counterparts to the right of neutral . if the response choice is unbalanced to either side , the possibility of that item being an interval measurement seems greatly diminished . with rpe , there is no issue of balance , but there remains the question of the consistency of the interval between rpe ratings . for example we might expect respondents to be very sensitive to the change between rest ( rpe = 6 ) and fairly light exercise ( rpe = 11 ) to be a larger difference than the difference between hard knapp gives a useful illustration of the potential problems of likert responses which could also be applied to rpe responses . if a response has choices , strongly disagree , disagree , neutral , agree , and strongly agree , knapp suggests that these could readily be assigned numerical values of 1 , 2 , 3 , 4 , 5 , as is often done . knapp further argues that other numbers could be assigned such as 1 , 3 , 5 , 7 , 9 , or any other linear transformation , and this would not impact the data or its analysis . in fact , knapp points out , any ordered non - linear numerical assignment , 3 , 11 , 17 , 23 , 31 could also be made and preserves the ordinal nature of the data ; however , this latter non - linear choice would have an impact on group means and whether or not parametric statistics should be used ( 19 ) . but , as knapp illustrates , if the terms never , seldom , occasionally , always were used , the two middle values could be argued as being very similar , with perhaps much less distance between seldom and occasionally than between never and seldom , or between occasionally and always . knapp even suggests that some would argue the two middle terms should be reordered ( 19 ) . with rpe , there is less ambiguity , but it is likely that the lower parts of the scale are further apart than the upper parts of the scale , especially for those less experienced with very hard exertion . ( 20 ) made the observation that no investigator would express the mean of a likert - response item as but , after these descriptors are converted to numbers , investigators are comfortable doing just that ; in fact the results might be ( improperly ) expressed as they suggest the following possibility for the means of a coded 5-item likert - type response to a series of questions : regardless of group size , the mean for the two groups will be identically equal to 3 , yet the two responses are obviously quite different with large difference in variance . however , it is noteworthy that this same issue could arise regardless of the type of measurement if information about the variance is not reported . it has been long acknowledged that the extremes of a likert - type response tend to get less use than the more central choices causing an anchor effect ( 16 ) . therefore , the intervals near the extremes may be further apart , than those near the center . carifio and perla ( 5 , 6 ) are among the strongest supporters for treating likert - type responses as interval data , going so far as to suggest that the likert - responses approximate ratio data . they do make the important distinction between likert scales compared to the answers to individual questions using likert - type responses . in their view , all true scales must necessarily include multiple - questions on a given topic whose summative score reflects the scale or measurement , and contend that a minimum of six items is necessary to create a reliable scale that measures some construct . any particular item comprising this scale can have a response format which might or might not be a likert - type response . carifio and perla ( 5 , 6 ) also argue that much of the criticism of likert scales confuses the response format from the actual multi - component measurement ( i.e. likert scale ) . in their view the individual items in a scale are not independent and autonomous , but rather must be connected in such a way as to yield a single unified result . this unified result ( scale ) will be more reliable and reflect the underlying construct better than will any individual item . they make the useful explanatory observation that a likert scale need not use likert - type responses to its individual questions , but could use a visual analog response ( var)(5 , 6 ) . consequently , carifio and perla ( 5 , 6 ) make a strong argument against the statistical or interpretive analysis of individual responses , suggesting that the summative assessment of a series of items is the proper item of analysis and that such a summative assessment yields interval or ratio data . surprisingly , carifio and perla ( 5 , 6 ) also tout vickers ( 25 ) as having made a strong case for the advantages of the likert - type response assessment even though the vickers study only used a one - item survey of pain , and not a proper scale by their definition given above ( 5 , 6 ) . are typically one - question measures and analyzed individually , so the six - or - more - item requirement is violated ( 5 , 6 ) . however , it is noteworthy that any measurement with only 5 or 7 possible discrete answers will in all likelihood , score better reliability than a measurement with 100 possible answers on a continuous measurement , i.e. , if a scale or an individual item had only a single choice , it would be perfectly reliable . in a similar fashion , vickers ( 25 ) reported that the likert - type response to their single question of pain yielded a higher mean value than the same question posed to the same group using a vas , and concluded that this meant that the likert - type response was a more responsive measure . in a likert - response item with choices varying from strongly disagree to disagree to neutral , to agree to strongly agree , it would appear to be in the mind of the research participant whether or not there is an equal distance between each of these choices ( 9 ) . note that the above response options are balanced in that the items to the left of neutral have an equal number of counterparts to the right of if the response choice is unbalanced to either side , the possibility of that item being an interval measurement seems greatly diminished . with rpe , there is no issue of balance , but there remains the question of the consistency of the interval between rpe ratings . for example we might expect respondents to be very sensitive to the change between rest ( rpe = 6 ) and fairly light exercise ( rpe = 11 ) to be a larger difference than the difference between hard ( rpe = 15 ) and maximum knapp gives a useful illustration of the potential problems of likert responses which could also be applied to rpe responses . if a response has choices , strongly disagree , disagree , neutral , agree , and strongly agree , knapp suggests that these could readily be assigned numerical values of 1 , 2 , 3 , 4 , 5 , as is often done . knapp further argues that other numbers could be assigned such as 1 , 3 , 5 , 7 , 9 , or any other linear transformation , and this would not impact the data or its analysis . in fact , knapp points out , any ordered non - linear numerical assignment , 3 , 11 , 17 , 23 , 31 could also be made and preserves the ordinal nature of the data ; however , this latter non - linear choice would have an impact on group means and whether or not parametric statistics should be used ( 19 ) . but , as knapp illustrates , if the terms never , seldom , occasionally , always were used , the two middle values could be argued as being very similar , with perhaps much less distance between seldom and occasionally than between never and seldom , or between occasionally and always . knapp even suggests that some would argue the two middle terms should be reordered ( 19 ) . with rpe , there is less ambiguity , but it is likely that the lower parts of the scale are further apart than the upper parts of the scale , especially for those less experienced with very hard exertion . 20 ) made the observation that no investigator would express the mean of a likert - response item as but , after these descriptors are converted to numbers , investigators are comfortable doing just that ; in fact the results might be ( improperly ) expressed as strongly agree.523 . they suggest the following possibility for the means of a coded 5-item likert - type response to a series of questions : regardless of group size , the mean for the two groups will be identically equal to 3 , yet the two responses are obviously quite different with large difference in variance . however , it is noteworthy that this same issue could arise regardless of the type of measurement if information about the variance is not reported . it has been long acknowledged that the extremes of a likert - type response tend to get less use than the more central choices causing an anchor effect ( 16 ) . therefore , the intervals near the extremes may be further apart , than those near the center . carifio and perla ( 5 , 6 ) are among the strongest supporters for treating likert - type responses as interval data , going so far as to suggest that the likert - responses approximate ratio data . they do make the important distinction between likert scales compared to the answers to individual questions using likert - type responses . in their view , all true scales must necessarily include multiple - questions on a given topic whose summative score reflects the scale or measurement , and contend that a minimum of six items is necessary to create a reliable scale that measures some construct . any particular item comprising this scale can have a response format which might or might not be a likert - type response . carifio and perla ( 5 , 6 ) also argue that much of the criticism of likert scales confuses the response format from the actual multi - component measurement ( i.e. likert scale ) . in their view the individual items in a scale are not independent and autonomous , but rather must be connected in such a way as to yield a single unified result . this unified result ( scale ) will be more reliable and reflect the underlying construct better than will any individual item . they make the useful explanatory observation that a likert scale need not use likert - type responses to its individual questions , but could use a visual analog response ( var)(5 , 6 ) . consequently , carifio and perla ( 5 , 6 ) make a strong argument against the statistical or interpretive analysis of individual responses , suggesting that the summative assessment of a series of items is the proper item of analysis and that such a summative assessment yields interval or ratio data . surprisingly , carifio and perla ( 5 , 6 ) also tout vickers ( 25 ) as having made a strong case for the advantages of the likert - type response assessment even though the vickers study only used a one - item survey of pain , and not a proper scale by their definition given above ( 5 , 6 ) . are typically one - question measures and analyzed individually , so the six - or - more - item requirement is violated ( 5 , 6 ) . however , it is noteworthy that any measurement with only 5 or 7 possible discrete answers will in all likelihood , score better reliability than a measurement with 100 possible answers on a continuous measurement , i.e. , if a scale or an individual item had only a single choice , it would be perfectly reliable . in a similar fashion , vickers ( 25 ) reported that the likert - type response to their single question of pain yielded a higher mean value than the same question posed to the same group using a vas , and concluded that this meant that the likert - type response was a more responsive measure . despite their strong support for likert - scales ( as opposed to individual likert - type item , or , in the kinesiology case , other unequal - interval response ) , carifio and perla concede that pearson correlations and statistical derivatives ( multiple regression , factor analysis , multivariate anova , and discriminant analysis ) are not very tolerant of uses of ordinal data , whereas f - tests generally are robust with regard to ordinal data ( 5 , 6 , 19 ) . regardless of where one stands on the use of f - tests of likert scales or other non - equal interval measures , in any situation in which pearson correlation - based analyses are planned , then using a var , or other alternative , seems to be a more conservative approach with no clear reason for not using such a scale . in the end , it seems the most important thing to keep in mind , is that statistical analyses are not an end in themselves , but rather a means to an end . statistics are a tool to enable investigators to think about the data , and ultimately , the population . statistics are not a substitute for thinking about what data truly mean , and what data are showing about the population . along these lines , hopkins ( 17 , 18 ) is known for insisting that effect sizes be presented along with p - values . for example , when studying elite athletes , sample sizes may be small , but small effects may have great practical significance for this population , but the probability of making a type ii error is large . conversely in situations with very large sample sizes , statistical power can be so high that impractically small changes ( effects ) are statistically significant but not of meaningful ( practical ) importance . it seems indefensible to offer an unbalanced likert scaled item , or any other single - measurement item as an interval measure , especially when other measurement options are available . whether or not a balanced scale is viewed as an interval scale , alternatives to the likert scaled , and similar items are available . some investigators have abandoned the likert - type response in favor of a simple visual analog scale ( vas ) . the vas typically has descriptive anchors only at the two extremes , although there has not been any published research on vas with multiple anchors . when sample sizes are small , the participants can physically mark a 100 mm line with appropriate anchors at either end . the participant is free to mark the scale at any point desired resulting in a continuous interval measurement with scores constrained between 0 and 100 , though certainly longer scales can be used . the scale can be scored by manually measuring the participant s chosen mark from the left end . a modified measure of perceived exertion using a vas could be developed with verbal anchors only on the two extremes . one objection to the use of vas responses is the challenges of doing this on computerized questionnaires . reips and funke ( 22 ) recommend their website , http://www.vas.com/ , which generates vas usable on the computer . they also offer information on the precision of these scales along with others ( 8 , 22 ) . this should alleviate some of the issues of large scale computerized measurements . despite that many psychometricists insist the data are interval ( 5 , 6 , 25 ) this can hardly be considered a conservative approach . again , if pearson correlation or analyses of variance are planned , then likert - type or other non - interval responses should not be used . given the recent innovations in var responses , there seems little reason to use likert - type , or other non - interval responses in most research applications ( 22 ) .

likert , likert - type , and ordinal - scale responses are very popular psychometric item scoring schemes for attempting to quantify people s opinions , interests , or perceived efficacy of an intervention and are used extensively in physical education and exercise science research . however , these numbered measures are generally considered ordinal and violate some statistical assumptions needed to evaluate them as normally distributed , parametric data . this is an issue because parametric statistics are generally perceived as being more statistically powerful than non - parametric statistics . to avoid possible misinterpretation , care must be taken in analyzing these types of data . the use of visual analog scales may be equally efficacious and provide somewhat better data for analysis with parametric statistics .

primary urethral cancer ( puc ) is a very rare disease with an annual age - standardized ratio of 1.5 per million women . the most common histological type is transitional cell carcinoma ( 55% ) , squamous cell carcinoma ( 22% ) , and adenocarcinoma ( 16% ) . these include papillary / micropapillary adenocarcinoma , clear cell adenocarcinoma , adenocarcinoma with intestinal differentiation , and unspecified adenocarcinoma [ 1 , 2 ] . primary urethral cancer presents with symptoms such as dysuria and later hematuria or regular bleeding . due to the female anatomy , the surgical approach depends on tumor stage and anatomic location and often results in major surgery with a pelvic exenteration . radiotherapy is an alternative to surgery and include external beam radiotherapy ( ebrt ) , brachytherapy alone , or a combination of the two modalities [ 4 , 6 , 7 ] . this case report describes a case of puc treated with ebrt followed by image guided adaptive interstitial bt ( igabt ) using the gec - estro ( groupe europen de curiethrapie [ gec ] and european society for radiotherapy & oncology [ estro ] ) adaptive target concept originally designed for locally advanced cervical cancer ( lacc ) [ 8 , 9 ] . previous , a supravaginal hysterectomy was performed due to a fibroma , but apart from that , she was without comorbidity . a gynecological examination in general anesthesia , showed an exophytic tumor in the area of the orificium externum urethra ( figure 1 ) . the tumor was infiltrating into the anterior vaginal wall , but mobile in relation to the pubic bones . the tumor dimensions were 2 cm in height and 4.5 cm in width and thickness . a ) clinical examination showed an exophytic tumor infiltrating the anterior wall of the vagina . b ) fdg pet - ct was with metabolic activity in the vulvar region in relationship to the urethra . c , d ) t2 weighted mri showed a hyper intense tumor with expansive growth pattern invading the distal part of the vagina biopsy showed an adenocarcinoma , with an immune profile that was positive for cdk20 + , cdx2 + , cea+ , suggesting a primary origin from the large bowel . a subsequent cystoscopy and computed tomography ( pet - ct ) showed intense metabolic activity in the vulvar region in relation to the urethra , but no lymph node or distant metastasis . magnetic resonance imaging ( mri ) showed a solid tumor at the urethral meatus measuring 4.5 x 1.4 x 2.5 cm with an expansive growth pattern . the tumor was adhered to the urogenital diaphragm and involved the vagina ( figure 1 ) . due to the clinical and radiological findings , it was concluded that the tumor was originating from the skene glands and classified as a puc . the tumor was considered operable with a complete cystectomy followed by construction of an ileal conduit . apart from surgery , chemotherapy during or after radiotherapy was not considered because of lack of evidence in this rare disease . the patient was presented for the different treatment options and agreed to go for an organ sparing strategy with radiotherapy . the elective target for ebrt ( clinical target volume [ ctv]-e ) included pelvic and inguinal lymph nodes and ctv - t , i.e. the gross tumor volume at diagnosis ( gtv - td ) with a margin of 1 cm respecting natural anatomical borders . during contouring , it was ensured that the whole urethra and vagina was included in the ctv - e . this volume included the gtv - td with a 1 cm isotropic margin respecting the ctv - e . external beam radiotherapy was delivered with volumetric modulated arc therapy ( vmat ) . during optimization , it was aimed to cover the target with 95 - 107% of prescribed dose and keep doses to organ at risk ( oar ) as low as possible without compromising the target coverage . homogeneous-45 was used for optimization to achieve a uniform dose of 45 gy in the area where bt would be delivered . after completion of ebrt , a gynecological examination in general anesthesia was made with insertion of an mri compatible dummy mupit ( martinez universal perineal interstitial template , varian medical systems , inc . , palo alto , ca , usa ) into the vagina . t2 weighted mri ( 3 tesla ) in para - transversal , -coronal and -sagittal planes were performed ( figure 2 ) for preplanning of the implant . during the preplanning procedure , the gec - estro targets ( gtvbt , ctvhr , ctvir ) and oar ( whole urethra , bladder , rectum , and sigmoid ) were defined . . then gtvbt was contoured on the basis of areas with high signal intensity on the mri within the tumor volume . the ctvhr included the gtvbt , and surrounding grey zones in the vagina and para - vaginal space , respecting the clinical findings at the gynecological examination . the ctvir included the initial tumor volume , and was generated based on information from mri and clinical examination at time of diagnosis [ 8 , 9 ] . finally , the pubic bones were contoured to avoid interference between needles and bone during implantation . pre - implant treatment planning was performed on brachyvision ( varian medical systems , inc . a , b ) t2 weighted mri with a dummy mupit in situ was done for virtual preplanning of the implantation . the gtvbt , ctvhr , ctvir , and organs at risk ( oar ) were contoured and preplanning of the subsequent application was conducted . c , d ) a post - implant ct - scan was conducted and based on clinical information and imaging the ctvhr and ctvir as well as organs at risk was contoured for brachytherapy planning . during manual dose optimization , it is aimed to deliver a physical dose of at least 30 gy to the ctvhr and avoid double dose volumes between the needles as well as respect the constraints for each oar after bowel preparation , the actual implantation was performed under general anesthesia . on the day of implantation the implantation was carried out according to the pre - implant treatment plan using the varian mupit template and sharp end steel needles . the target volumes ( ctvhr and ctvir ) were redefined using the information from clinical examination , pre - planning mri , and post - implant ct . organs at risk ( bladder , urethra , rectum , and sigmoid ) were again outlined as they appeared on the post - implant ct ( figure 2 ) . planning aim of pdr - bt was to deliver a physical dose of 30 gy in 50 hourly pulses to ctvhr . the cumulative dose of ebrt and bt was calculated into equivalent dose in 2 gy fractions ( eqd2 ) using = 10 gy for tumor , and = 3 gy for normal tissues , and a repair half - time of 1.5 h. treatment planning was based on manual dose optimization with the aim of reaching a total ebrt and bt dose of d90 > 80 gy in the ctvhr and d90 > 60 gy in the ctvir . for oar , the dose to d2cc and the d0.1cc were recorded . the oar constraints used were 70 gy for d2cc rectum and sigmoid , 80 gy for d2cc bladder , and 98 gy for d0.1cc urethra . basal dose was evaluated in the central plane of the ctvhr as the average dose across all basal dose points in the central plane . it was aimed to avoid double dose ( 60 gy ) volumes between the needles ( figure 2 ) . radiotherapy was well tolerated with only mild side effects including erythema in the vulvar and inguinal regions . first follow - up was conducted 3 months after the treatment with a clinical examination and imaging . during the gynecological examination , no late effects were diagnosed and the patient had not experienced any changes in urination . primary urethral cancer is a rare disease without any common guideline for the treatment . in this case report , the patient was selected for an organ sparing approach with radiotherapy that included vmat and igabt . development in ebrt with imrt - technique gives an opportunity to treat a relatively large volume and at the same time , decrease the dose to oar , thus reducing acute side effects during treatment as well as the risk for late morbidity . for brachytherapy other developments have taken place . the gec - estro guidelines were designed for lacc using intracavitary or combined intracavitary / interstitial implants [ 8 , 9 ] . studies have shown improvement in local control and limited morbidity after introduction of the gec - estro adaptive target concept . these findings have resulted in attempts to adapt the guidelines into the treatment of other tumors . one study reported outcome of image and laparoscopic guided interstitial brachytherapy for locally advanced primary or recurrent gynecological cancer using the adaptive gec - estro target concept . this study found an encouraging lc - rate of 92% at 3 years and only limited morbidity in 28 patients . in the present case report , it was possible to adapt the gec - estro target concept and define different target volumes at time of bt , which corresponds to gtvbt , ctvhr , and ctvir . furthermore , it was possible to fulfil the planning aims for the target volumes with a d90 of 79.1 gy and 64.8 gy for ctvhr ( volume 6.1 cm ) and ctvir ( volume 17.3 cm ) , respectively . evaluation of doses to oar showed that we were able to respect the dose constraints that were defined with a d2cc of 45.7 gy , and 44.9 gy , for bladder and rectum , respectively . the d0.1cc for urethra was 85.6 gy . these findings indicate that the gec - estro adaptive target concept can be used in the treatment of puc and result in good clinical results . the literature on urethral cancer is limited , but recently a series of 10 women treated with high dose rate interstitial brachytherapy for urethral cancer ( 5 primary and 5 recurrent ) was published . in most patients , the treatment strategy employed ebrt and image guided ( ct ) interstitial bt . all 5 patients with primary tumors were squamous cell histology and treatment results were acceptable with one local and one nodal recurrence , and acceptable morbidity during follow - up . the case report highlights the use of ebrt and igabt in the treatment of urethral cancer and illustrate that modern radiotherapy is a feasible option with a curative potential and limited morbidity , and should be considered in patients with puc . however , more experience is warranted in more patients with longer follow - up to confirm the satisfying results . the present case report shows that ebrt with an image guided adaptive interstitial brachytherapy boost is an attractive treatment of puc with a possibility to provide local control , and at the same time , organ preservation with limited morbidity .

primary urethral cancer ( puc ) is a very rare disease . this case report illustrates a successful treatment approach of a 67-year - old woman with a urethral adenocarcinoma selected for an organ preserving treatment with external beam radiotherapy ( ebrt ) and interstitial brachytherapy ( bt ) boost , using the gec - estro target concept originally designed for locally advanced cervical cancer ( lacc ) . treatment included ebrt with 45 gy in 25 fractions followed by image guided adaptive interstitial bt ( igabt ) with a pulsed - dose - rate ( pdr ) bt boost with 30 gy in 50 hourly pulses . the d90 for ctvhr was 79.1 gy in eqd23 . at 24 months follow - up , the patient was recurrence free and without treatment related side effects .

prior to our experiments , the samples are gently stirred to prevent any size segregation due to sedimentation , although for our high volume fractions sedimentation and size segregation are exceedingly slow . to try to ensure that the sample does not slip , where the sample comes into contact with the glass plates , we add a coating of scotchgard ( 3 m ) . the sample wets the scotchgard , pinning the sample to the coated region and ensuring a no - slip boundary condition at each plate . we do not observe the behavior of purely slipping emulsions in any of our experiments [ s1 ] . we study the sample at depths @xmath85 and 60 @xmath1 m , relative to @xmath39 defined at the stationary bottom plate . at each height we compute the mean amplitude @xmath40 . we find @xmath86 where @xmath42 is the local strain amplitude and @xmath87 is a slip length . @xmath58 does not extrapolate to 0 at @xmath39 , but rather at negative values ranging from @xmath88 to @xmath89 @xmath1 m . the local strain is always smaller than the applied strain . this suggests that the emulsion partially slips at the top plate , or possibly has a shear band somewhere where the local strain is significantly higher . unfortunately , our confocal could not image deeply enough to observe the behavior at the top plate . we emphasize that the mean strain is uniform throughout within the the volume we image . see the table for further information about each particular experiment . given the dependence of the decay length @xmath90 on @xmath91 ( as discussed in the main text ) , it suggests that perhaps the variation we see for samples with different @xmath92 in the table is perhaps more due to the variability in @xmath42 for those data . .volume fraction @xmath92 , observed local strain amplitudes @xmath42 for different volume fractions @xmath92 , observed slip length @xmath87 , and the characteristic length scales @xmath82 and @xmath83 . the macroscopic applied strain amplitude is @xmath93 for all experiments . the uncertainties for all listed lengths are @xmath94 @xmath1 m . [ cols="^,^,^,^,^",options="header " , ] [ s1 ] s. p. meeker , r. t. bonnecaze , and m. cloitre , phys . lett . * 92 * , 198302 ( 2004 ) .

we study dense and highly polydisperse emulsions at droplet volume fractions @xmath0 . we apply oscillatory shear and observe droplet motion using confocal microscopy . the presence of droplets with sizes several times the mean size dramatically changes the motion of smaller droplets . both affine and nonaffine droplet motions are observed , with the more nonaffine motion exhibited by the smaller droplets which are pushed around by the larger droplets . droplet motions are correlated over length scales from one to four times the mean droplet diameter , with larger length scales corresponding to higher strain amplitudes ( up to strains of about 6% ) . amorphous solids are intriguing in that they have a liquid - like structure yet do not flow like liquids . window glass is the most common example , and we have some understanding of plastic flow of glass @xcite . glass is not the only amorphous solid ; other examples include piles of sand , dense colloidal pastes , and shaving cream foams , which are disordered on the scale of microns or millimeters . categorizing these as solid - like is reasonable as these materials deform elastically ( below a yield stress ) , rather than flowing . if a stress is applied above the yield stress , then molecules in a glass or particles in a sand pile can rearrange . to make progress , most prior studies used samples comprised of particles of one size or two similar sizes @xcite . the picture that has developed is that the sample flows by having small local groups of particles rearrange . however , many natural materials of interest are highly polydisperse , with particle sizes varying by factors of ten or more . the flow of such materials has been less widely studied @xcite . differences noted from the monodisperse case include a lower strain amplitude required for viscous flow @xcite and diminished sample viscosity @xcite . the causes of these differences are not well understood . m to the left during the half - cycle ) ; this is the affine component of the motion . the white arrows indicate the total displacement of each droplet from the peak - to - peak of one half oscillation cycle , with the mean displacement subtracted off ; this is the nonaffine component of the motion . for easier visualization , all arrows are twice their actual length , including the affine displacement arrow . the image corresponds in time to the mid - point of this half - cycle . the width of the image is 56 @xmath1 m . the depth is @xmath2 @xmath1 m , the strain amplitude is @xmath3 , and the volume fraction is @xmath4 . , width=264 ] in this letter , we study the shear of highly polydisperse emulsions and show that the microscopic picture of these samples is quite different from cases where the droplets are all similar - sized . our emulsions are composed of oil droplets in water , stabilized by a surfactant , and are at sufficiently high volume fractions ( @xmath0 ) that the samples act as amorphous solids @xcite . we subject the samples to low amplitude oscillatory shear and follow the droplet motion in the interior of the sample via confocal microscopy @xcite . most droplets rearrange elastically @xcite and move sinusoidally . however , these motions are not necessarily affine , as shown in fig . [ droplets ] , where the affine motion has been subtracted off ( a uniform displacement to the right for all droplets , indicated by the large arrow ) . in particular , our main finding is that in a highly polydisperse emulsion , the smaller droplets frequently undergo reversible but highly nonaffine droplet motion . unlike the shear of monodisperse samples @xcite , large droplets allow for `` cross - talk '' between layers at different heights which have different mean velocities . the motions of droplets are correlated over large length scales , up to four times the mean droplet radius , with longer range correlations found for higher applied strain amplitudes . our observations form a sharp contrast to the localized irreversible rearrangements seen in less polydisperse amorphous samples @xcite . we use the shear - rupture method of ref . @xcite to create decane - in - water emulsion droplets stabilized with sds , skipping the fractionation step . the continuous phase is a 65:35 volume ratio of water and glycerol to index match the decane droplets . volume fractions are tuned to the range @xmath5 by centrifugation and dilution . macroscopically , our samples do not flow on their own , indicating they possess a yield stress at these volume fractions @xcite . we place the samples in a parallel - plate shear cell @xcite . the gap of the cell is fixed at @xmath6 @xmath1 m . the lower glass plate is fixed , and the top plate is driven sinusoidally at a frequency @xmath7 hz . @xmath8 is chosen to be in the low - frequency limit for this sample , where sample behavior is dominated by elastic properties @xcite . the amplitude is typically @xmath9 @xmath1 m , leading to a macroscopic strain amplitude of @xmath10 . our experiments are conducted at volume fractions and strain amplitudes over which the droplets remain fairly spherical . the sample is imaged from below through the stationary plate using a confocal microscope . fluorescein dye is added to the continuous phase to visualize the droplets as shown in fig . [ droplets ] . to quantify the size distribution of our system we acquire three - dimensional ( 3d ) image stacks from a static sample of size @xmath11 @xmath1m@xmath12 . to observe the dynamics when sheared , we take data as rapidly as possible using only two - dimensional ( 2d ) images . for the 2d experiments , images of size @xmath13 @xmath1m@xmath14 are acquired at a rate of 90 images per second for 33 s. using the 3d data from static samples , we determine the droplet radii using custom software implementing the method of ref . @xcite . the size distribution obtained from this method is shown in fig . [ histo ] . the mean droplet radius is 1.2 @xmath1 m , the standard deviation is 0.6 @xmath1 m , and the sauter mean radius @xmath15 is 2.3 @xmath1 m . while large droplets with @xmath16 @xmath1 m are uncommon , they account for a nontrivial portion of the volume , as can be seen by the volume - weighted probability distribution shown in the inset to fig . [ histo ] . sample . droplets with radius @xmath17 @xmath1 m are fit to an exponential ( dashed line ) with decay length 0.5 @xmath1 m . the data for @xmath18 @xmath1 m correspond to only three observed droplets , thus the true shape of the distribution is ill - defined for larger droplets . the inset shows the same data , with the probability weighted by @xmath19 and plotted on a linear scale . , width=264 ] for 2d data analysis , we use a slightly different analysis technique . we identify droplets using the 2d - hough transform @xcite , which lets us identify the droplets radii and positions in each image . from that data , we then use conventional techniques to track their corresponding trajectories @xcite . both standard tracking and the iterative image tracking technique described in ref . @xcite are used to reconstruct each trajectory . note that for each droplet , because our observation is only in 2d , we do not know the true radius @xmath20 . however , we observe that droplets are not distinguishable in 2d slices when they are viewed more than @xmath21 away from their center . this is due to the tilt of the droplet interface : the droplet radius changes significantly within the optical section of the 2d confocal image ( @xmath22 @xmath1 m ) , so the edge of the droplet is blurred in these cases and can not be clearly determined with our image analysis , and these droplets are not tracked . accordingly , for each droplet we track , the droplet radius @xmath23 we apparently observe is in the range @xmath24 . when an oscillatory strain is applied to the emulsion , the majority of droplets rearrange reversibly and periodically at the driving frequency . the droplet - averaged displacement field is @xmath25 ( with no motion on average in @xmath26 and @xmath27 ) . it is this average motion we term the `` affine motion '' in the sense that the position predicted by @xmath28 is an affine transformation of the original positions . ( this differs from some prior work where affine motion was determined locally in space and time @xcite . ) in fig . [ droplets ] the droplet - averaged displacement during the time interval pictured is indicated by the large black displacement arrow . this average motion has been subtracted off from all of the droplets , and the remainder ( the non - affine component ) is indicated by the white arrows . the largest droplets ( @xmath29 @xmath1 m ) move sinusoidally , following @xmath30 , reflected by their short displacement vectors in fig . [ droplets ] . in contrast , smaller droplets move in a variety of directions . this variety of displacements for the smaller droplets is due to the largest droplets . at the equator of a large droplet , it moves with the expected motion for that height @xmath27 , that is , @xmath28 . the droplets deform little and thus move as fairly rigid spheres , and thus the top of a large droplet moves with an amplitude @xmath31 too small relative to the expected velocity at height @xmath32 . likewise , at height @xmath33 the large droplet moves faster than the mean velocity for that height . two large droplets that are nearby but with centers at different @xmath27 do not have the same velocities , and as they move back and forth sinusoidally , they push and pull on the smaller droplets between them . these smaller droplets thus have apparently random motions . in practice , the larger droplets are rarer and so less likely to influence each other . moreover , they move based on the average influence of the smaller droplets surrounding them , and so their motion tends to follow the average motion @xmath28 . the contrast in motion between large and small droplets in a highly polydisperse sample differs qualitatively from cases where large - scale flows cause non - affine motion , and which typically require large amplitude strain @xcite . over the 33 s movies , approximately 8% of the droplets make an irreversible rearrangement at some point this only occurs with smaller droplets , @xmath34 @xmath1 m . before and after the irreversible rearrangement , the droplets move periodically . the rarity of plastic rearrangements in our data is similar to a prior study of a more monodisperse emulsion @xcite . our typical forcing amplitude for the shear cell ( @xmath9 @xmath1 m ) was chosen to limit the amount of plastic rearrangements . at this point we only study droplets whose trajectories are reversible ( elastic ) and thus periodic . we respectively denote as @xmath35 and @xmath36 the components of a trajectory parallel and perpendicular to the shear axis at time @xmath37 . a least squares fit is applied to each component with functional forms : @xmath38 using the known driving frequency @xmath8 . these functional forms provide a good fit to the particle trajectories . we take data at several depths @xmath27 , relative to @xmath39 defined at the stationary bottom plate . at each height we compute the mean amplitude @xmath40 . for all data , we find a linear relationship between @xmath41 and @xmath27 , and from this linear relationship we define the local strain @xmath42 by @xmath43 ; see supplemental material for further details about determining local strain . ) and perpendicular ( @xmath44 ) amplitude components . ( b ) probability distributions of the phase angles . ( c - e ) scatter plots of the droplet amplitudes as a function of their radii @xmath23 . ( c ) shows @xmath45 , ( d ) shows @xmath44 , and ( e ) shows @xmath46 . the horizontal dashed lines in ( c , d ) are at zero , indicating the expected value for purely affine motion . data are from a @xmath4 emulsion with @xmath47 , @xmath2 @xmath1 m . the data for @xmath48 are centered around @xmath49 @xmath1 m . @xmath50 is arbitrary as it depends on when we set @xmath51 , although note that the distribution for @xmath52 is centered around the mean value of @xmath53 . the lack of symmetry in these distributions is due to the finite number of droplets . , width=302 ] the distributions of the fitting parameters @xmath54 , @xmath55 , @xmath56 and @xmath57 are quite broad , as shown in fig . [ pdfs ] . while many droplets move with the mean amplitude @xmath58 as appropriate for that height , several have amplitudes that differ by 0.5 @xmath1 m or more from the mean . negative values of @xmath45 indicate droplets moving with smaller amplitudes than might be expected , and likewise positive values indicate droplets moving with larger amplitudes . these results are equally true in the direction of the applied strain [ fig . [ pdfs](a ) ] and perpendicular to this direction [ fig . [ pdfs](b ) ] , showing many droplets have significant nonaffine motion . note that @xmath44 from our fits ( eqns . [ sines ] ) is positive : to get values @xmath59 , we assume that all droplets move in phase , and so droplets with phase angles @xmath52 that appear @xmath60 out of phase with the dominant motion are adjusted , @xmath61 . in general we find @xmath62 , as expected by symmetry . the broad amplitude distributions we see in fig . [ pdfs](a , b ) are qualitative similar to those seen in utter and behringer s study of sheared 2d bidisperse materials @xcite . the widths of the amplitude distributions are in agreement with the argument given above : if a large droplet with @xmath63 @xmath1 m pushes on a smaller droplet located at a height @xmath23 away from the center of the large droplet , then the anomalous motion should be @xmath64 @xmath1 m for these data . figure [ pdfs](c - e ) shows a scatter - plot of the data of fig . [ pdfs](a ) , as a function of the droplet radii @xmath23 . the amplitudes associated with bigger droplets are found at the central peaks of @xmath48 and @xmath65 . the outliers are more likely to be associated with smaller sized droplets . figure [ pdfs](e ) in particular shows the total nonaffine amplitude for each droplet , with the larger values of this amplitude generally being seen for smaller droplets although also some small droplets move nearly affinely . to understand the spatial character of the particle behavior , fig . [ dropletplots ] shows images colored based on the values of @xmath66 ( left ) and @xmath44 ( right ) . droplets with similar @xmath54 or @xmath55 tend to be close together . this is also apparent in fig . [ droplets ] , where nearby droplets have nonaffine displacement vectors in similar directions . ( color online ) droplets which move elastically , drawn at their mean position . the color code indicates the parallel ( left picture ) and perpendicular ( right picture ) amplitude of each droplet . the color bar denotes the amplitude scale in @xmath1 m , where 0 denotes the mean amplitude for these data ( @xmath49 @xmath1 m , and using 0 @xmath1 m for the @xmath44 data ) . the images correspond to the data shown in fig . [ pdfs ] . , width=302 ] ( solid symbols ) and @xmath44 ( open symbols ) . the strain amplitudes are @xmath67 ( circles ) and @xmath68 ( squares ) . the correlation functions are normalized by their value at @xmath69 @xmath1 m . the data are from the same sample as figs . [ pdfs ] and [ dropletplots ] . ( b ) values of the decay lengths for this sample as a function of strain amplitude . the uncertainty of @xmath42 is 6% . the error bars are the standard deviations found from multiple experiments . the data shown are taken at depth @xmath2 @xmath1 m . lines are guides to the eye . , width=302 ] to gain further insight into the spatial clustering of droplets with similar characteristics , we identify droplet pairs which are separated by a surface - to - surface distance @xmath70 , that is , droplets separated by a center - to - center distance @xmath71 , where @xmath72 is the radius of droplet @xmath73 in the 2d image . then , we compute a spatial correlation function for the amplitude @xmath66 ( and similar for @xmath44 ) : @xmath74 where @xmath75 is the number of neighboring droplets , and @xmath76 and @xmath77 are the @xmath78-amplitudes of droplets @xmath73 and @xmath79 . the average @xmath58 is for all droplets comprised by @xmath75 and @xmath80 corresponds to the variance of the distribution of @xmath54 . the choice of using the surface - to - surface distances rather than center - to - center is perhaps not obvious . however , each individual droplet moves as a solid object , thus completely correlated with itself ( distances @xmath81 ) . examining the surface - to - surface motion lets us avoid considering this artificially correlated solid - body motion , and instead probe the properties of the effective medium between droplets . if we consider center - to - center separations , the results are noisy and do not have a simple dependence on the distance . figure [ corfig](a ) shows these correlation functions for @xmath66 ( solid symbols ) and @xmath44 ( open symbols ) , for one sample at two different strain amplitudes . the correlation functions exhibit exponential decay with decay lengths in the range of 8 - 15 @xmath1 m ; the decay lengths for different samples are provided in the supplemental material and do not vary systematically with volume fraction . these lengths are comparable to the sizes of the larger droplets in the sample . figure [ corfig](a ) shows that correlations in the larger strain case ( squares ) decay slower than than in the small strain case ( circles ) . we find @xmath82 and @xmath83 depend on @xmath42 as shown in fig . [ corfig](b ) for this @xmath4 sample . we have studied dense polydisperse emulsions , and observed highly complex droplet motion when our samples are sinusoidally sheared . most droplets move periodically , but different droplets have different amplitudes and phases . large droplets push small droplets out of their way , although nearly all of this motion is reversible . in fact , a key point is that the complex droplet motions occur at low strain amplitudes where the behavior is elastic , rather than requiring large amplitude plastic flow . we find length scales over which droplet motions are correlated . these length scales range from 1 to 4 times the mean droplet diameter , with the largest values found for the highest strains ( @xmath84 ) . overall , our results suggest that the flow of highly polydisperse systems is richer than that of monodisperse samples . theoretical descriptions derived for less polydisperse systems will likely not apply or need to be modified @xcite . preliminary observations of steadily sheared polydisperse emulsions suggest that these results carry over in a qualitative respect , with the largest droplets moving in straightforward fashion under steady shear , and the smallest droplets moving in highly variable trajectories . we thank g. w. baxter , r. besseling , c. crane , r. gonzalez , c. hollinger , and w. c. k. poon for helpful discussions . funding from the national science foundation ( grants dmr-0603055 and dmr-1336401 ) , the petroleum research fund ( administered by the american chemical society , grant 47970-ac9 ) , and the swiss national foundation ( grant pbfr2 - 116930 ) is gratefully acknowledged . 27 natexlab#1#1bibnamefont # 1#1bibfnamefont # 1#1citenamefont # 1#1url # 1`#1`urlprefix[2]#2 [ 2][]#2 , * * , ( ) . , , , * * , ( ) . , , , * * , ( ) . , , , , , * * , ( ) . , , , , , , * * , ( ) . , , , , * * , ( ) . , * * , ( ) . , , , , * * , ( ) . , , , * * , ( ) . , , , * * , ( ) . , * * , ( ) . , , , , , * * , ( ) . , * * , ( ) . , , , , , * * , ( ) . , , , * * , ( ) . , * * , ( ) . , * * , ( ) . , * * , ( ) . , , , , , * * , ( ) . , * * , ( ) . , * * , ( ) . , * * , ( ) . , , , , * * , ( ) . , * * , ( ) . , , , , * * , ( ) . , , , * * , ( ) . , * * , ( )

we are interested here in uncovering relationships between the appearances of pairs of objects , and particularly in modeling the human notion of which objects complement each other and which might be seen as acceptable alternatives . we thus seek to model what is a fundamentally human notion of the visual relationship between a pair of objects , rather than merely modeling the visual similarity between them . there has been some interest of late in modeling the visual style of places @xcite , and objects @xcite . we , in contrast , are not seeking to model the individual appearances of objects , but rather how the appearance of one object might influence the desirable visual attributes of another . there are a range of situations in which the appearance of an object might have an impact on the desired appearance of another . questions such as ` which frame goes with this picture ' , ` where is the lid to this ' , and ` which shirt matches these shoes ' ( see figure [ fig : brownloaferquery ] ) inherently involve a calculation of more than just visual similarity , but rather a model of the higher - level relationships between objects . the primary commercial application for such technology is in recommending items to a user based on other items they have already showed interest in . such systems are of considerable economic value , and are typically built by analysing meta - data , reviews , and previous purchasing patterns . by introducing into these systems the ability to examine the appearance of the objects in question we aim to overcome some of their limitations , including the ` cold start ' problem @xcite . the problem we pose inherently requires modeling human visual preferences . in most cases there is no intrinsic connection between a pair of objects , only a human notion that they are more suited to each other than are other potential partners . the most common approach to modeling such human notions exploits a set of hand - labeled images created for the task . the labeling effort required means that most such datasets are typically relatively small , although there are a few notable exceptions . a small dataset means that complex procedures are required to extract as much information as possible without over - fitting ( see @xcite for example ) . it also means that the results are unlikely to be transferable to related problems . creating a labeled dataset is particularly onerous when modeling pairwise distances because the number of annotations required scales with the square of the number of elements . we propose here instead that one might operate over a much larger dataset , even if it is only tangentially related to the ultimate goal . thus , rather than devising a process ( or budget ) for manually annotating images , we instead seek a freely available source of a large amount of data which may be more loosely related to the information we seek . large - scale databases have been collected from the web ( without other annotation ) previously @xcite . what distinguishes the approach we propose here , however , is the fact that it succeeds despite the indirectness of the connection between the dataset and the quantity we hope to model . we have developed a dataset suitable for the purposes described above based on the amazonweb store . the dataset contains over @xmath0 million relationships between a pool of almost 6 million objects . these relationships are a result of visiting amazonand recording the product recommendations that it provides given our ( apparent ) interest in the subject of a particular web page . the statistics of the dataset are shown in table [ tab : stats ] . an image and a category label are available for each object , as is the set of users who reviewed it . we have made this dataset available for academic use , along with all code used in this paper to ensure that our results are reproducible and extensible . we label this the _ styles and substitutes _ dataset . the recorded relationships describe two specific notions of ` compatibility ' that are of interest , namely those of _ substitute _ and _ complement _ goods . substitute goods are those that can be interchanged ( such as one pair of pants for another ) , while complements are those that might be purchased together ( such as a pair of pants and a matching shirt ) @xcite . specifically , there are 4 categories of relationship represented in the dataset : 1 ) ` users who viewed x also viewed y ' ( 65 m edges ) ; 2 ) ` users who viewed x eventually bought y ' ( 7.3 m edges ) ; 3 ) ` users who bought x also bought y ' ( 104 m edges ) ; and 4 ) ` users bought x and y simultaneously ' ( 3.4 m edges ) . critically , categories 1 and 2 indicate ( up to some noise ) that two products may be substitutable , while 3 and 4 indicate that two products may be complementary . according to amazon s own tech report @xcite the above relationships are collected simply by ranking products according to the cosine similarity of the sets of users who purchased / viewed them . note that the dataset does not document users preferences for pairs of images , but rather amazon s estimate of the set of relationships between pairs objects . the human notion of the visual compatibility of these images is only one factor amongst many which give rise to these estimated relationships , and it is not a factor used by amazonin creating them . we thus do not wish to summarize the amazondata , but rather to use what it tells us about the images of related products to develop a sense of which objects a human might feel are visually compatible . this is significant because many of the relationships between objects present in the data are not based on their appearance . people co - purchase hammers and nails due to their functions , for example , not their appearances . our hope is that the non - visual decision factors will appear as uniformly distributed noise to a method which considers only appearance , and that the visual decision factors might reinforce each other to overcome the effect of this noise . [ cols="<,>,>,>,>",options="header " , ] ] ] for each category , we consider the subset of relationships from @xmath1 that connect products within that category . after generating random samples of non - relationships , we separate @xmath1 and @xmath2 into training , validation , and test sets ( 80/10/10% , up to a maximum of two million training relationships ) . although we do not fit hyperparameters ( and therefore do not make use of the validation set ) , we maintain this split in case it proves useful to those wishing to benchmark their algorithms on this data . while we did experiment with simple @xmath3 regularizers , we found ourselves blessed with a sufficient overabundance of data that overfitting never presented an issue ( i.e. , the validation error was rarely significantly higher than the training error ) . to be completely clear , our protocol consists of the following : 1 . each category and graph type forms a single experiment ( e.g. predict ` bought together ' relationships for women s clothing ) . 2 . our goal is to distinguish relationships from non - relationships ( i.e. , link prediction ) . relationships are identified when our predictor ( eq . [ eq : prob ] ) outputs @xmath4 . we consider _ all _ positive relationships and a random sample of non - relationships ( i.e. , ` distractors ' ) of equal size . thus the performance of a random classifier is 50% for all experiments . all results are reported on the test set . results on a selection of top - level categories are shown in table [ tab : toplevel ] , with further results for clothing data shown in table [ tab : clothing ] . recall when interpreting these results that the learned model has reference to the object images only . it is thus estimating the existence of a specified form of relationship purely on the basis of appearance . in every case the proposed method outperforms both the category - based method and weighted nearest neighbor , and the increase from @xmath5 to @xmath6 uniformly improves performance . interestingly , the performance on compliments vs. substitutes is approximately the same . the extent to which the @xmath6 results improve upon the wnn results may be seen as an indication of the degree to which visual similarity between images fails to capture a more complex human visual notion of which objects might be seen as being substitutes or compliments for each other . this distinction is smallest for ` books ' and greatest for ` clothing shoes and jewelery ' as might be expected . we have no ground truth relating the true human visual preference for pairs of objects , of course , and thus evaluate above against our dataset . this has the disadvantage that the dataset contains all of the amazon recommendations , rather than just those based on decisions made by humans on the basis of object appearance . this means that in addition to documenting the performance of the proposed method , the results may also be taken to indicate the extent to which visual factors impact upon the decisions of amazon customers . the comparison across categories is particularly interesting . it is to be expected that appearance would be a significant factor in clothing decisions , but it was not expected that they would be a factor in the purchase of books . one possible interpretation of this effect might be that customers have preferences for particular genres of books and that individual genres have characteristic styles of covers . finally we evaluate the ability of our model to personalize co - purchasing recommendations to individual users , that is we examine the effect of the user personalization term in ( eqs . [ eq : personal1 ] and [ eq : personal2 ] ) . here we do not use the graphs from tables [ tab : toplevel ] and [ tab : clothing ] , since those are ` population level ' graphs which are not annotated in terms of the individual users who co - purchased and co - browsed each pair of products . instead for this task we build a dataset of co - purchases from products that users have _ reviewed_. that is , we build a dataset of tuples of the form @xmath7 for pairs of products @xmath8 and @xmath9 that were purchased by user @xmath10 . we train on users with at least 20 purchases , and randomly sample 50 co - purchases and 50 non - co - purchases from each user in order to build a balanced dataset . results are shown in table [ tab : personal ] ; here we see that the addition of a user personalization term yields a small but significant improvement when predicting co - purchases ( similar results on other categories withheld for brevity ) . ] recall that each image is projected into ` style - space ' by the transformation @xmath11 , and note that the fact that it is based on pairwise distances alone means that the embedding is invariant under isomorphism . that is , applying rotations , translations , or reflections to @xmath12 and @xmath13 will preserve their distance in ( eq . [ eq : styledist ] ) . in light of these factors we perform k - means clustering on the @xmath14 dimensional embedded coordinates of the data in order to visualize the effect of the embedding . figure [ fig : pca ] shows images whose projections are close to the centers of a set of selected representative clusters for men s and women s clothing ( using a model trained on the ` also viewed ' graph with @xmath6 ) . naturally items cluster around colors and shapes ( e.g. shoes , t - shirts , tank tops , watches , jewelery ) , but more subtle characterizations exist as well . for instance , leather boots are separated from ugg ( that is sheep skin ) boots , despite the fact that the visual differences are subtle . this is presumably because these items are preferred by different sets of amazon users . watches cluster into different color profiles , face shapes , and digital versus analogue . other clusters cross multiple categories , for instance we find clusters of highly - colorful items , items containing love hearts , and items containing animals . figure [ fig : whiteshoe ] shows a set of images which project to locations that span a cluster . although performance is admittedly not outstanding for a category such as books , it is somewhat surprising that an accuracy of even 70% can be achieved when predicting book co - purchases . figure [ fig : pca_books ] visualizes a few examples of style - space clusters derived from books data . here it seems that there is at least some meaningful information in the cover of a book to predict which products might be purchased together children s books , self - help books , romance novels , and comics ( for example ) all seem to have characteristic visual features which are identified by our model . in figure [ fig : nav ] we show how our model can be used to navigate between related items here we randomly select two items that are unlikely to be co - browsed , and find a low cost path between them as measured by our learned distance measure . subjectively , the model identifies visually smooth transitions between the source and the target items . figure [ fig : stylegraph ] provides a visualization of the embedding of boys clothing achieved by setting @xmath15 ( on co - browsing data ) . sporting shoes drift smoothly toward slippers and sandals , and underwear drifts gradually toward shirts and coats . ] we here demonstrate that the proposed model can be used to generate recommendations that might be useful to a user of a web store . given a query item ( e.g. a product a user is currently browsing , or has just purchased ) , our goal is to recommend a selection of other items that might complement it . for example , if a user is browsing pants , we might want to recommend a shirt , shoes , or accessories that belong to the same style . here , amazon s rich and detailed category hierarchy can help us . for categories such as women s or men s clothing , we might define an ` outfit ' as a combination of pants , a top , shoes , and an accessory ( we do this for the sake of demonstration , though far more complex combinations are possible our category tree for clothing alone has hundreds of nodes ) . then , given a query item our goal is simply to select items from each of these categories that are most likely to be connected based on their visual style . specifically , given a query item @xmath16 , for each category @xmath17 ( represented as a set of item indices ) , we generate recommendations according to @xmath18 i.e. , the minimum distance according to our measure ( eq . [ eq : u ] ) amongst objects belonging to the desired category . examples of such recommendations are shown in figures [ fig : brownloaferquery ] and [ fig : outfits ] , with randomly chosen queries from women s and men s clothing . generally speaking the model produces apparently reasonable recommendations , with clothes in each category usually being of a consistent style . an alternate application of the model is to make assessments about outfits ( or otherwise combinations of items ) that we observe ` in the wild ' . that is , to the extent that the tastes and preferences of amazoncustomers reflect the zeitgeist of society at large , this can be seen as a measurement of whether a candidate outfit is well coordinated visually . to assess this possibility , we have built two small datasets of real outfits , one consisting of twenty - five outfits worn by the hosts of _ top gear _ ( jeremy clarkson , richard hammond , and james may ) , and another consisting of seventeen ` before ' and ` after ' pairs of outfits from participants on the television show _ what not to wear _ ( us seasons 9 and 10 ) . for each outfit , we cropped each clothing item from the image , and then used _ google _ s reverse image search to identify images of similar items ( examples are shown in figure [ fig : topgear ] ) . next we rank outfits according to the average log - likelihood of their pairs of components being related using a model trained on mens / women s co - purchases ( we take the average so that there is no bias toward outfits with more or fewer components ) . all outfits have at least two items . figure [ fig : topgear ] shows the most and least coordinated outfits on _ top gear _ ; here we find considerable separation between the level of coordination for each presenter ; richard hammond is typically the least coordinated , james may the most , while jeremy clarkson wears a combination of highly coordinated and highly uncoordinated outfits . a slightly more quantitative evaluation comes from the television show _ what not to wear _ : here participants receive an ` outfit makeover ' , hopefully meaning that their made - over outfit is more coordinated than the original . examples of participants before and after their makeover , along with the change in log likelihood are shown in figure [ fig : wnw ] . indeed we find that made - over outfits have a higher log likelihood in 12 of the 17 cases we observed ( @xmath19 ; log - likelihoods are normalized to correct any potential bias due to the number of components in the outfit ) . this is an important result , as it provides external ( albeit small ) validation of the learned model which is independent of our dataset . we have shown that it is possible to model the human notion of what is visually related by investigation of a suitably large dataset , even where that information is somewhat tangentially contained therein . we have also demonstrated that the proposed method is capable of modeling a variety of visual relationships beyond simple visual similarity . perhaps what distinguishes our method most is thus its ability to model what makes items _ complementary_. to our knowledge this is the first attempt to model human preference for the appearance of one object given that of another in terms of more than just the visual similarity between the two . it is almost certainly the first time that it has been attempted directly and at this scale . we also proposed visual and relational recommender systems as a potential problem of interest to the information retrieval community , and provided a large dataset for their training and evaluation . in the process we managed to figure out what not to wear , how to judge a book by its cover , and to show that james may is more fashionable than richard hammond . + * acknowledgements . * this research was supported by the data 2 decisions cooperative research centre , and the australian research council discovery projects funding scheme dp140102270 .

humans inevitably develop a sense of the relationships between objects , some of which are based on their appearance . some pairs of objects might be seen as being alternatives to each other ( such as two pairs of jeans ) , while others may be seen as being complementary ( such as a pair of jeans and a matching shirt ) . this information guides many of the choices that people make , from buying clothes to their interactions with each other . we seek here to model this human sense of the relationships between objects based on their appearance . our approach is not based on fine - grained modeling of user annotations but rather on capturing the largest dataset possible and developing a scalable method for uncovering human notions of the visual relationships within . we cast this as a network inference problem defined on graphs of related images , and provide a large - scale dataset for the training and evaluation of the same . the system we develop is capable of recommending which clothes and accessories will go well together ( and which will not ) , amongst a host of other applications .

in the early universe @xmath10 , x - rays from compact sources might have had an important contribution to the heating of the intergalactic medium ( igm ) during the epoch of reionization @xcite . the direct study of these high - redshift x - ray sources is untenable due to the spatial resolution and large observation times that would be required . instead , we study local analogs to the first , low - metallicity galaxies in the early universe to infer their properties . blue compact dwarf ( bcd ) galaxies have been suggest as the best local analogs to such galaxies @xcite . it has been found that the bcds have x - ray emission dominated by high mass x - ray binaries ( hmxbs ) @xcite . many recent studies @xcite have found enhanced populations of hmxbs in the extremely metal poor galaxies relative to star formation rate ( sfr ) . these results match predictions from simulations done by linden et al . ( 2010 ) who showed a dramatic increase in bright hmxbs below 20 percent solar metallicity . linden et al . ( 2010 ) explain that the mechanism driving this bright hmxb population increase is due to an increase in the fraction of binaries accreting through roche lobe overflow ( rlo ) as opposed to wind accretion systems . we further explore the relation between x - ray emission and star formation rate for high - redshift , star - forming galaxies . as discussed by @xcite , it is not certain that all early galaxies were small , metal - deficient galaxies , for which the bcds are analogues . instead , there may have been larger , gas - rich proto - galaxies starting to form during the epoch of reionization , particularly at later times . these objects would have properties similar to the galaxies that have been observed using the lyman break technique @xcite . again , because these galaxies are undetectable in x - rays , except for the longest of observation times , we turn to local analogues . in this study , we observed a sample of ten lyman break analogues ( lbas ) . these galaxies are part of a rare population of local galaxies which have properties that match the high - redshift , star - forming lyman break galaxies ( lbgs ) with regards to stellar mass , star formation rate , and metallicity @xcite . we measured the x - ray flux for each galaxy in our sample and converted this to a luminosity ( see section [ sect : procedure ] for details ) . star formation rates were calculated from ir and uv data , as described in section [ sect : sfr ] . @xcite ( hereafter , m12 ) provided a linear fit to the x - ray luminosity plotted against sfr for their sample of near - solar metallicity galaxies . they found a relation of , @xmath11 which has been used in simulations to estimate the x - ray contribution to heating and reionization in the early universe ( e.g. , * ? ? ? * ; * ? ? ? equation ( [ eqn : mineo1 ] ) is the relation for resolved galaxies . for unresolved galaxies , @xcite estimated that including the diffuse emission increased the x - ray luminosity such that , @xmath12 m12 employ a specific sfr cutoff of @xmath13 for their sample selection in order to statistically select for hmxb - dominated starburst galaxies . the sample of lba galaxies discussed in this paper also meet this criterion ( see table [ tab : results ] ) . as with the blue compact dwarf galaxies , the lba x - ray luminosity is expected to be enhanced with respect to star formation rate due to relatively low metal content @xcite . the sample of galaxies we use have gas - phase metallicities in the range @xmath14 . in this range , population synthesis predicts at most a factor of a few enhancement of x - ray emission @xcite and observational studies of ulx populations have confirmed this prediction ( e.g. , * ? ? ? * ; * ? ? ? determining the @xmath9/sfr relation for this sample of analogues will allow us to better understand the role of hmxbs in the early universe . in section [ sect : sample ] , we outline the selection constraints for our sample of lbas . the observations used to derive @xmath9 , sfr , and @xmath15 are described in section [ sect : observations ] . in section [ sect : procedure ] , we provide detailed descriptions about the methods used to derive x - ray luminosities from the chandra data . we also explain and compare two separate methods used to determine sfrs . results are given in section [ sect : results ] along with a discussion of the possibility of a @xmath9sfr metallicity relation . this is followed by discussion , summary and conclusions in sections [ sect : discussion ] and [ sect : conclusions ] . all errors are at the 68% level , unless otherwise stated . the sample of lbas considered here are drawn from the uv imaging survey performed by the _ galaxy evolution explorer ( galex)_. @xcite defined a set of supercompact , uv - luminous galaxies ( scuvlgs ) at @xmath16 that have similar properties to the more distant lbgs . the sample was defined as having fuv luminosities such that @xmath17 , and was later refined by adding the supercompact constraint for surface brightness , @xmath18 kpc@xmath19 @xcite . from this sample of lbas , five had been observed by chandra : @xcite studied haro 11 and @xcite observed four more lbas for their study . we utilized the _ chandra x - ray observatory _ to observe five more lbas , bringing our sample size to ten . we required the lbas to be pure starbursts according to the optical line emission criteria of @xcite ( bpt - diagram ) , thereby limiting the likelihood of agn contamination ( see figure [ fig : agn ] ) . we also used 1.4 ghz spectral luminosities @xcite to look for clear agn candidates with @xmath20 w hz@xmath21 @xcite . we found values for six out of ten lbas , all below the agn cutoff with @xmath22 w hz@xmath21 . using sfr estimates from @xcite and @xmath9/sfr relation of @xcite , we estimated @xmath9 and selected the four brightest , non - composite lbas with @xmath23 and one with near - solar @xmath24 . optical spectra and images confirm that the lbas are similar to lbgs in their sfr , physical size , stellar mass , gas velocity dispersion , and metallicity . high resolution uv imaging shows that uv emission originates in highly compact burst regions in small , clumpy galaxies that are morphologically similar to lbgs @xcite . many studies have now established these galaxies as the best known local analogues to lbgs @xcite . + throughout the paper , we use the 29 star - forming spiral and irregular galaxies found in table 1 of m12 as a comparison sample for the @xmath9sfr relation . in section [ sect : plane ] , we examine the possible metallicity dependence of the @xmath9sfr relation . m12 does not directly provide metallicity measurements for their data , so in this case we compare with the results of @xcite , who found reported metallicities for 19 of the galaxies in m12 . the sample of @xcite consists of galaxies from two main sources : @xcite and @xcite . the @xcite subset of m12 galaxies ( 19 out of the original 29 ) , shown in our figures as blue squares , have gas - phase metallicities of @xmath25 . the remaining set of galaxies in @xcite are mainly bcds from @xcite , and are shown in our figures as green circles ( black triangles for those that only have @xmath9 upper limits ) , and have @xmath26 . [ cols="<,<,<,^,^,^,^,^,^ " , ] [ tab : results ] + @xmath27 source region ellipse for haro 11 encompasses all three knots of bright emission . + @xmath28 http://wwwmpa.mpa-garching.mpg.de/sdss/dr7/ from our derived results for x - ray luminosity and sfrs , which are summarized in table [ tab : results ] , we determined the @xmath9sfr relation using a logarithmic least squares fitting technique , assuming a linear relation ( i.e. , we apply least - squares fitting to the logarithmic values of @xmath9/sfr ) . we find the relation @xmath29 with a dispersion of @xmath4 dex ( see figure [ fig : lx_sfr ] ) . in this case , the x - ray luminosity was calculated from the net counts in the @xmath3 kev range using @xmath30 plus the galactic absorption along the line of sight ( see table [ tab : results ] ) . we wish to compare these results to the results of m12 , but their @xmath1sfr relation uses only resolved xrb point sources , whereas our results use the total , unresolved x - ray emission from the galaxies . in a follow - up paper , @xcite determined the x - ray contribution from the unresolved , diffuse component of their sample of galaxies . they found that this also correlates linearly with sfr such that , @xmath31 with a dispersion of @xmath32 dex . @xmath33 is the unresolved emission , from which the contribution of backgrounds and unresolved hmxbs was subtracted . the sample consisted of a subset of 21 out of the original 29 galaxies used in the m12 paper i. expanding this relation to the @xmath3 kev range , using the two - component thermal plus power law model discussed in @xcite , we find a conversion factor of 1.17 . we can add this to the resolved xrb @xmath1sfr relation of m12 to get , @xmath34 with dispersion @xmath32 dex ( figure [ fig : lx_sfr ] ) . thus , our result shows a factor of @xmath35 increase in x - ray luminosity with respect to sfr . we have seen that the sample of lba galaxies exhibit an elevated @xmath9/sfr relation as compared to the results for spiral and irregular starburst galaxies @xcite . comparing these two samples we calculate the significance of this elevated x - ray luminosity using the two - sample t - test method ( welch statistic ) , assuming the null hypothesis ( no difference in mean values ) . we compare our results @xmath36 with m12 @xmath37 and get a probability of @xmath38 that the two samples are drawn from the same population . comparing the difference between the observed values of @xmath9/sfr for the 10 lbas and the 29 galaxies from m12 , we find a one - tailed significance of 98.2% using a permutation test @xcite , consistent with the t - test result . therefore , the lba population does show significant enhancement of @xmath9/sfr compared to that for m12 . if we restrict ourselves to the metallicity range @xmath39 , the common ground for the lbas and m12 sample , we find a reduced significance of @xmath40% from the two - sample t - test . this may suggest an @xmath9/sfr enhancement in the lbas not attributable to metallicity effects . + in this section we discuss a possible plane describing the x - ray luminosity of a star - forming galaxy dominated by hmxb @xmath41 . m12 did not publish associated metallicities for their sample . however , @xcite found metallicities for 19 out of 29 galaxies using sdss optical data consistent with the measurement technique used in this paper . @xcite compared the @xmath9/sfr of bcds found in @xcite and star - forming galaxies in m12 versus metallicity and found an enhancement of a factor of ten . we use the sample of @xcite as our comparison sample for metallicity dependence . we split the sample into the @xmath25 m12 subset ( blue squares ) and the remaining galaxies ( @xmath42 ) , which consist mostly of bcds found in @xcite ( green circles , black triangles ( @xmath9 upper limits only ) ) . the errors on luminosity @xmath43 for the comparison sample are estimated from threshold luminosity and measured luminosity ( table 1 in @xcite ) , assuming poisson errors . all data from @xcite have been corrected to be consistent with the measurement techniques used in this paper , as described in the previous section . we exclude data that have only upper limits on @xmath9 from our fitting procedure . testing for a correlation between metallicity and @xmath9/sfr over all 39 galaxies in the combined data set , we find a negative correlation at the 99.9% significance level , based on a spearman s rank correlation test . we then fit a @xmath9sfr metallicity relation of the form @xmath44 where @xmath9 is measured in the @xmath3 kev range and @xmath45 , @xmath46 , and @xmath47 with @xmath48 . the dispersion about this best fit is @xmath49 dex . since @xmath50 is consistent with being linear , we force the @xmath9sfr relation to be linear by setting @xmath51 . doing this we find @xmath52 , @xmath53 , and @xmath54 with a dispersion of @xmath49 dex . this model provides an equally good fit as the model with @xmath50 as a free parameter . the lower plot in figure [ fig : plane_results ] shows this result . thus , we confirm that @xmath9 is linearly , positively correlated with sfr and we find that @xmath9 is negatively correlated with metallicity . @xcite find a fit , with @xmath50 set to unity , where @xmath55 and @xmath56 . correcting for unresolved vs. resolved emission , their fit corresponds to @xmath57 which is consistent with our result . the upper right plot in figure [ fig : plane_results ] shows a projection of the @xmath9sfr metallicity plane for which sfr is forced to be linear . the red , dashed line is a projection of our fitting result and the gray , dot - dashed line is that of @xcite . the solid black line shows the prediction of @xcite , which provides a fit with @xmath58 with a dispersion of @xmath59 dex . @xcite used population synthesis to show that for star forming regions with @xmath60 , the bright hmxb population would be enhanced . @xcite also used population synthesis and simulations to show that the x - ray luminosity per sfr increases by nearly a factor of ten for metallicities less than 10 per cent solar . @xcite fit a polynomial to the x - ray luminosity per sfr as a function of metallicity . using their parameters and solar values of @xmath61 and @xmath62 , we calculated an expected mean value of @xmath63/sfr@xmath64 in the @xmath65 kev range . this is completely consistent with our results . the possible existence of a @xmath9sfr metallicity plane is intriguing but not unexpected from simulations @xcite . from figure [ fig : sfr_metal ] , one can see that the three distinct populations of galaxy types ( bcds , spirals , lbas ) occupy three distinct regions of the sfr metallicity space . thus the existence of a plane may arise from different @xmath9sfr relations for these galaxy types and not necessarily the metallicity . the fact that lbas have marginally enhanced x - ray emission relative to the m12 sample in the same metallicity range may suggest that other galactic properties , such as hi gas fraction , affect the @xmath9sfr relation . a study of bcds or lbas over a wider range in metallicity and sfr ( unsampled regions of figure [ fig : sfr_metal ] ) could shed light on whether the @xmath9sfr metallicity relation holds or if other properties need to be considered . expanding the metallicity range of each galaxy type would allow for a better test of the correlations seen between x - ray luminosity , sfr , and metallicity as it provides a more uniform sample . we find that the @xcite prediction ( black line , figure [ fig : plane_results ] ) provides a fit that is not significantly worse than the power law relation ( red dashed line ) . from figure [ fig : plane_results ] one can see that this is not surprising since the fragos prediction straddles the straight power law fit . neither the power law model nor the fragos model are physically motivated but instead are parameterized fits . previous studies of local analogues to early universe galaxies have shown enhanced x - ray binary populations @xcite and enhanced total x - ray luminosities @xcite relative to the sfr of the respective galaxies . we continued this line of study by examining the x - ray luminosity per sfr of a sample of ten local analogues to the high redshift lyman break galaxies . five of the lbas we studied had been previously observed and analysed by @xcite . the other five lbas were observed by chandra specifically for this study . our results may be summarized as follows : 1 . the @xmath9/sfr relation for our sample is given by @xmath66 with a dispersion of @xmath4 dex . compared to the m12 result for unresolved sources @xmath67 , we find a factor of @xmath35 increase in @xmath9/sfr with a chance probability of 0.018 that these two samples were drawn from the same population ( a significance of @xmath7 ) . we find that when including gas - phase metallicity , the above result is consistent with the prediction of @xcite based on populations synthesis models ( figure [ fig : lx_sfr ] ) . for an average metallicity of @xmath68 or @xmath69 , @xcite predicts a value for @xmath70/sfr@xmath64 , assuming a solar oxygen abundance of @xmath71 . this is consistent with our observed value of @xmath72 . 3 . fitting the @xmath9sfr metallicity relation with the form @xmath73 gives @xmath74 , @xmath75 , and dispersion @xmath32 dex . these three results provide further evidence that metallicity plays a major role in the evolution of the @xmath9/sfr relation for galaxies . using local galaxies as analogues suggests that the large , proto - galaxies and the small dwarf galaxies of the early universe had enhanced x - ray emission due mainly to their low metallicities . the effects of enhanced x - ray emission before and during the epoch of reionization would be increased heating of the intergalactic medium , thereby resulting in an earlier onset in the rise of the 21 cm power during this epoch . many simulations have been done to predict these effects on the redshifted 21 cm line ( e.g. , * ? ? ? * ; * ? ? ? * ) . using the results of @xcite ( see their figure 2 ) , a factor of ten increase in the @xmath9/sfr relation ( as suggested by the results of @xcite and consistent with the predictions of @xcite ) would result in a weakening of the redshifted 21 cm brightness temperature by a factor of 2 - 3 ( or @xmath76 ) . this also results in an earlier onset of the rise of x - ray heating with @xmath77 . understanding the effects of metallicity on hmxb formation is important for understanding future 21 cm observations of the epoch of reionization . we thank the anonymous referee for helpful comments and suggestions that greatly improved the manuscript . the scientific results reported in this article are based on observations made by the chandra x - ray observatory . support for this work was provided by the national aeronautics and space administration through chandra award number g04 - 15085x issued by the chandra x - ray observatory center , which is operated by the smithsonian astrophysical observatory for and on behalf of the national aeronautics space administration under contract nas8 - 03060 .

the source of energetic photons that heated and reionized the early universe remains uncertain . early galaxies had low metallicity and recent population synthesis calculations suggest that the number and luminosity of high - mass x - ray binaries are enhanced in star - forming galaxies with low metallicity , offering a potentially important and previously overlooked source of heating and reionization . lyman break analogue ( lba ) galaxies are local galaxies that strongly resemble the high - redshift , star - forming lyman break galaxies and have been suggested as local analogues to these metal - deficient galaxies found in the early universe . we studied a sample of ten lbas in order to measure the relation between star formation rate and x - ray luminosity . we found that for lbas with metallicities in the range @xmath0 , the @xmath1sfr relation was @xmath2 } ) = 39.85(\pm 0.10)$ ] in the @xmath3 kev band with a dispersion of @xmath4 dex . this is an enhancement of nearly a factor of @xmath5 in the @xmath6sfr relation relative to results for nearby , near - solar metallicity galaxies . the enhancement is significant at the 98.2% level ( @xmath7 ) . our enhanced @xmath8 relation is consistent with the metallicity - dependent predicted value from population synthesis models . we discuss the possibility of a @xmath9sfr metallicity plane for star - forming galaxies . these results are important to our understanding of reionization and the formation of early galaxies . [ firstpage ] galaxies : starburst x - rays : galaxies

the structure of the impurity band of semiconductors has been widely studied during the last two decades both theoretically and experimentally ( see monograph@xcite ) . in the early theoretical studies the spin structure of the impurity band was completely ignored . recent experiments suggest that the spin structure is very important for the variable range hopping conductivity , especially near the metal - non - metal transition@xcite . the exchange interaction must be the main mechanism of the spin - spin interaction in the impurity band . it appears as a result of the overlap of the wave functions of different states . the scale of this interaction decreases exponentially with increasing distance between the states . thus , this interaction becomes the most important one near the metal - non - metal transition . in this region the scale of the interaction is of the order of the binding energy of a single impurity . in this paper we study the spin structure of the impurity band created by coulomb impurities in both two and three dimensional cases in the limit of low density of impurities . in the two - dimensional case the impurities may be located either outside or inside the plane of electron gas . we assume that all impurities are occupied by one electron . in this case we can consider the coordinates of the occupied centers as random variables without any correlations . our study of the spin structure is based upon the heisenberg hamiltonian which takes into account the spin - spin interaction of the electrons localized at different randomly distributed impurities . @xmath5 where @xmath6 is spin 1/2 operator , @xmath7 is a unit matrix , and @xmath8 denote different impurity atoms . the sum is over all pairs of impurities . the density of impurities is assumed to be small . this problem has a long story@xcite . the following important results have been obtained : + 1 . the ground state of the system consists of local singlets . rosso@xcite , thomas and rosso@xcite , andres _ et al._@xcite used different selfoconsistent approaches to get the distribution of the excitation energies of the singlet - triplet transitions . bhatt and lee@xcite worked out a computational scaling approach which is exact at small density of impurities . they have also mentioned a drastic difference between the heisenberg and ising models . as far as we know all previous authors used simplified versions for the function @xmath9 . our paper pursues the following goals : + 1 . we analyze the existing methods to find the distribution of excitation energies and propose a new modification for one- , two- and three - dimensional cases . our approach is exact at low densities and it allows to get an approximate analytical expression for this distribution . + 2 . to get an estimate for the energy of spin ordering one needs a reliable calculation of the coefficients @xmath10 which are defined here as @xmath11 of the singlet - triplet splitting for the two states corresponding to the impurities @xmath12 and @xmath13 . we have performed these calculations for a pair of the coulomb centers at a distance @xmath14 . the result of the computations is a function @xmath9 which is reliable at all distances from zero to infinity . the paper is organized as follows . in section 2 we consider hamiltonian eq.([ham ] ) in the case of small impurity density . we show that the ground state mostly consists of independent singlets . we show that the problem of finding these singlets can be reduced to a non - trivial geometric problem . we solve it in a mean field approximation and by computer modeling . the solution of this problem gives the distribution function @xmath15 for the energies of the singlet - triplet transitions for a given function @xmath9 . in section 3 we calculate @xmath9 and its inverse function @xmath16 . for the @xmath17-case we present interpolated formulae which are based upon the results of well - known calculations for two hydrogen atoms . these calculations include analytical results for large distances@xcite , numerical calculations at intermediate distances , and known results for the singlet - triplet splitting of the he atom . similar interpolated formulae are presented for the @xmath18-case . they are based upon our original calculations given in the appendices . we present an analytical expression for @xmath9 at large distances , a numerical result for @xmath19 , and variational calculations for a `` two - dimensional he atom '' . in the conclusion we discuss the distribution function of singlet - triplet splittings @xmath20 , where @xmath21 , and the density of free spins @xmath22 at finite temperature @xmath23 . these two functions are the final results of our paper . we find the ground state and excited states of the hamiltonian eq.([ham ] ) using the following properties of @xmath10 . * all @xmath24 , which means an antiferromagnetic interaction . * the density of impurities @xmath25 is assumed to be small , so that the average distance between them is larger than the characteristic length of the exponential decay of @xmath10 . this means there is a very large dispersion of @xmath10 . in fact we shall assume that if @xmath26 , then @xmath27 . thus , we ignore the cases when the distance @xmath14 is very close to the distance @xmath28 , assuming that these two pairs are not very far from each other . to understand the physics of the problem it is very helpful to consider the hamiltonian ( [ ham ] ) with four impurities only ( fig . from a general principle one can conclude@xcite that the energy spectrum consists of six levels , one level with spin @xmath29 , three levels with @xmath30 , and two levels with @xmath31 . let us assume that @xmath32 is much larger than all other @xmath10 in this problem . then the ground state wave function describes two singlets at sites ( 1,2 ) and ( 3,4 ) . it is easy to write the energy of the ground state and the first excited state assuming @xmath33 where the sum includes all @xmath10 except @xmath32 and @xmath34 . the ground state energy @xmath35 and the energy of the first excited state @xmath36 are given by the equations @xmath37 the physical meaning of eq . ( [ en ] ) is simple . two singlets ( 1,2 ) and ( 3,4 ) do not interact with each other if condition ( [ in ] ) is fulfilled . the @xmath38 terms come from the first term in the hamiltonian ( [ ham ] ) . in this approximation the excitation energy is @xmath39 . the ground state has a total spin @xmath31 while the first excited state has @xmath30 . bhatt and lee@xcite take into account the next approximation for the excitation energy @xmath40 since @xmath32 is the largest term , the second term should be small . it looks like it can change the ground state from singlet to triplet if @xmath34 is unusually small . however , such configurations are extremely rare . it happens because in the case of small @xmath34 one should consider fig.1b with 6 spins rather than fig.1a . indeed , very small @xmath34 means a long distance between impurities 3 and 4 . it is more likely that in this situation some other strong singlet ( 5,6 ) is the nearest neighbor of the impurity 4 rather than the singlet ( 1,2 ) . in this 6-spin system we have 2 strongly connected groups of spins , namely 1,2,3 and 4,5,6 . assume that @xmath32 and @xmath41 provide the strongest bonds in each group . suppose there is no interaction between the groups . then , the ground state in each of them is a degenerate doublet . altogether the system is 4-fold degenerate . if one takes into account @xmath34 the degeneracy of the ground state will be lifted . one gets a singlet and a triplet with the energy splitting @xmath42 . on the other hand , the general 6-spin problem can be solved assuming that both @xmath32 and @xmath41 are infinite . in this approximation one gets the same result : the ground state is a singlet and the excitation energy @xmath39 . it follows that the other bonds connecting the two groups , like @xmath43 may contribute to the excitation energy only in the second order of perturbation theory . this contribution will contain a small dimensionless coefficient like @xmath44 and it may be neglected . thus , it is not necessary to take into account the renormalization of the weak bonds due to their strong neighbors in the limit of small density . bhatt and lee also mention@xcite that their computations show the triplet ground state in very rare cases . thus , we assume that the ground state energy of any even number of impurities has @xmath31 and the system can be split into localized singlets . to find the pairs of impurities which form the singlet in the ground state we propose the following geometric problem . + 1 . for every impurity in the system find its nearest neighbor . take the pair with the smallest distance . generally , the nearest neighbor of a site a does not have site a as its nearest neighbor . but for the closest pair this is the case . this closest pair forms a singlet with the largest binding energy . to find all other singlets remove both sites of the first pair . go to point 1 and continue until all the singlets will be found . + the same geometric problem has been proposed by thomas and rosso@xcite for three - dimensional case . assuming that all neighboring @xmath10 are very different one can write the total energy of the lowest state in the form @xmath45 where the first sum includes all pairs which form singlets and the second one includes all other pairs . one can prove that the distribution of singlets , obtained as a solution of the problem above , gives the minimum of total energy . suppose , for example , that the solution prescribes the configuration of singlets ( 1,2 ) , ( 3,4 ) and ( 5,6 ) , for impurities with the numbers from 1 to 6 . one can show that any other location of singlets at the same impurities , like ( 1,3 ) , ( 2,5 ) and ( 4,6 ) , has larger energy . we mention first that the contribution to the energy from all other impurities like 7,8 ... is the same at all configurations of singlets of six chosen impurities . suppose now that @xmath46 . then all other @xmath10 connecting the six impurities are also less than @xmath32 . indeed , if one of them were larger , it would be used to form a singlet instead of @xmath32 . thus , any rearrangement of the pairs within 6 impurities that destroys singlet ( 1,2 ) increases the total energy . in the same way one can show that rearrangement of singlets in the system of four impurities 3,4,5,6 also increases the total energy . the same consideration can be done for any even number of impurities . thus , the solution of the above geometric problem gives the ground state of the system . we start with the simplest mean field approximation . suppose we are at the stage where all pairs with distance less than @xmath1 are removed and we want to find the residual impurity density @xmath47 . the crucial point of the mean field approximation is that we neglect correlations in the positions of the remaining impurities except that they can not be closer to one another than @xmath1 . we start with the two - dimensional case . let us draw a circle around each impurity with the radius @xmath1 . there will be no other impurities inside the circles . now increase the radii from @xmath1 to @xmath48 and calculate how many impurities occur in the rings between @xmath1 and @xmath48 . the total number of these impurities gives the decrease of @xmath49 , where @xmath50 and @xmath51 is the total area of the system . thus , one gets the equation @xmath52 here @xmath53 is the density of the impurities outside the circles . it is slightly larger than @xmath47 ( see below ) , but in the simplest mean field approximation we ignore this difference . it is convenient to introduce the dimensionless coordinate @xmath54 and the normalized number of particles ( or density ) @xmath55 . here @xmath56 is the initial concentration of particles . the differential equation for @xmath57 at @xmath58 has the form @xmath59 the solution of this equation with the condition @xmath60 is @xmath61 where @xmath62 is the two - dimensional density . similar calculations for the three- and one - dimensional cases give @xmath63 here @xmath64 at @xmath65 and @xmath66 at @xmath67 . this distribution has been obtained by rosso@xcite for @xmath65 . one can show that at small @xmath68 the above results are exact , including @xmath69-corrections . bhatt@xcite has pointed out that it is not exact at large @xmath68 . we believe that the exact distribution has a following form at large @xmath68 @xmath70 where the coefficient @xmath71 and it depends on the dimensionality of space @xmath72 . it follows from eq.([b ] ) that the average density @xmath47 is independent of @xmath73 at large values of @xmath1 and it is of the order of @xmath74 . this is because the average distance between impurities can not be smaller than @xmath1 by definition , and there are no reasons for it to be substantially larger than @xmath1 . that is why we believe that eq.([b ] ) is exact at large @xmath68 . our computer modeling confirms this point and it gives us the values @xmath75 . we propose an improved mean field approach which takes into account the fact that the density @xmath76 outside the circles is slightly larger than the average density @xmath47 , because there are no impurities inside the circles . for example , at @xmath77 , one gets @xmath78 where @xmath79 is the excluded area inside @xmath80 circles . we have introduced a free parameter @xmath81 , which takes into account the overlap of the circles . its value can be extracted from comparison with numerical computations . ( [ nimpr ] ) can be generalized for any @xmath72 to get a differential equation in @xmath82 @xmath83 the solution is given by the following transcendental equation : @xmath84 with @xmath85 . it is worth mentioning that if we would neglect the `` circles '' overlapping ( @xmath86 ) , then the solution of eq . ( [ corr ] ) is @xmath87 which is an underestimate for large distances . in the general case , for @xmath88 , the analytical solution of the transcendental equation ( [ corr ] ) can be obtained only for large and small values of @xmath68 . @xmath89 we performed computer simulations of this problem for the one- , two- and three - dimensional cases . the results are shown in fig . 2 ( a ) together with the simple mean field approximation of eq . ( [ n3 ] ) . we found that fitting our numerical data using eq . ( [ corr ] ) shows excellent agreement if we choose @xmath90 . it would be natural to think that the simple mean field approach with @xmath91 becomes exact for large values of @xmath72 . unfortunately , eq . ( [ corr ] ) does not have an analytical solution for all @xmath68 and so it is not convenient for our purpose . we found that the simple interpolated formula @xmath92 which resembles eq.([1stappr ] ) , describes the residual density well for the whole range of distances . the comparison of this formula with the results of computer modeling is shown in fig . 2 ( b),(c),(d ) for d= 1,2,3 . below we use only eq . ( [ inrho ] ) with the values of @xmath75 obtained above . the spin - spin interaction constant is the splitting energy between the ground states for total spin @xmath30 and @xmath31 @xmath93 for hydrogen - like molecule , where nuclei are represented by two impurities . hereafter we use effective atomic units ( a.u . ) which means that all distances are measured in units of the effective bohr radius @xmath94 , and energies in units of @xmath95 , where @xmath96 is the effective carrier mass , and @xmath97 is the dielectric constant . we propose a simple interpolated formula for the exchange constant based on the most accurate numerical calculations of the hydrogen molecule @xcite and the following asymptotic expression@xcite for large @xmath1 : @xmath98 we found @xmath99 from the data for the singlet - triplet splitting of the helium atom@xcite . @xmath100 the numerical data@xcite show that the behavior of the logarithm of the exchange constant for small @xmath1 is well described by a second order polynomial . to obtain the interpolated formula we match the second derivative of @xmath101 . in two regions it has the following behavior @xmath102 where @xmath103 is the matching constant . the simplest formula that satisfies both conditions is @xmath104 after integrating twice we obtain @xmath105 where @xmath106 and @xmath107 are connected by equation @xmath108 this interpolated formula has one fitting parameter @xmath107 and the correct asymptotic behavior . the parameter @xmath107 has to be chosen to match small distances in an optimal way . the least square method gives @xmath109 . the final equation is @xmath110 for further calculations we need the inverse function @xmath16 as well . because of the exponential character of the exchange constant , the inverse function depends on energy logarithmically therefore , we performed interpolation for the function @xmath111 , where @xmath112 . the result is @xmath113 the interpolated curves and all available data are shown in fig . we are unaware of any calculations of @xmath9 for the two - dimensional case . we have considered a general problem when the motion of the electrons is confined to a plane , but the coulomb impurities are at distances @xmath114 and @xmath115 outside the plane . however , in this paper only the calculations for in - plane impurities ( @xmath116 ) are presented . the results for the general case will be published elsewhere@xcite . the case of the in - plane impurities corresponds to a @xmath18 hydrogen - like molecule with the hamiltonian @xmath117 when @xmath118 the singlet - triplet splitting constant is calculated by making use the semiclassical approach @xcite ( see appendix [ apc ] ) . we obtained the following result : @xmath119 to provide the point @xmath2 we performed variational calculations for the two - dimensional helium atom . we found that ( see appendix [ aphel ] ) @xmath120 finally , we performed numerical calculations based on the method described in @xcite for the point @xmath121 . using the same method as in the @xmath17-case we get the following interpolated formulas for @xmath9 and @xmath122 : @xmath123 these results are shown in fig . 3b . we obtained an analytical expression ( [ inrho ] ) for the dimensionless density of impurities which form singlet pairs with a distance larger than @xmath1 . we have also calculated the strength of the spin - spin interaction @xmath124 and obtained analytical expressions for the function @xmath16 for the three - dimensional ( [ r3d ] ) and the two - dimensional ( [ r2d ] ) cases . combining eq . ( [ inrho ] ) with eqs . ( [ r3d ] ) or ( [ r2d ] ) one can calculate an analytical expression for the density of singlet pairs @xmath125 that has a singlet - triplet energy splitting smaller than @xmath126 . at finite temperature @xmath23 the pairs with @xmath127 are destroyed by a thermal motion . therefore , at a given temperature the function @xmath128 at @xmath129 gives the density of free spins in the system which contribute to the curie susceptibility . thus , we obtain an analytical expression for the density of free spins @xmath130 . we have also calculated the distribution function of excitation energy in a logarithmic scale . it is defined as follows @xmath131 where @xmath132 . the analytical expression for @xmath133 based on eqs . ( [ inrho ] ) , ( [ r3d ] ) , ( [ r2d ] ) is quite cumbersome . in the two limits of large and small energies ( or small and large distances ) the behavior of @xmath134 in the leading order is @xmath135^{-3 } , & \qquad \varepsilon \longrightarrow 0 ; \end{array}\right.\ ] ] @xmath136 ^ 2 , & \qquad \varepsilon\longrightarrow 1\\ \frac{9}{1.15\pi n_0 a_b^3}\left[\ln(1/\varepsilon)\right]^{-4 } , & \qquad \varepsilon \longrightarrow 0 . \end{array}\right.\ ] ] our results for @xmath137 are shown by the full lines in fig . 4 ( a ) , ( b ) for the two - dimensional and the three - dimensional cases . we choose two different dimensionless densities @xmath73 for each case . they are @xmath138 and 0.025 for @xmath18 and @xmath139 and 0.016 for @xmath17 . the dependence of the dimensionless distribution function @xmath140 for the two - dimensional and the three - dimensional cases for the same two donor densities @xmath73 are presented on fig . 4 ( c ) , ( d ) by the full lines . the most important features of both functions are the long logarithmic tails in the regions of low temperature and low energy . similar behavior has been obtained by bhatt and lee@xcite . note that @xmath141 decreases with increasing density @xmath73 . this is not the case for the distribution function . larger density corresponds to larger distribution function @xmath134 at large energies . this is because the derivative @xmath142 is larger for larger density @xmath73 at small @xmath1 . however , the dimensionless distribution function @xmath143 is normalized to 1/2 . that is why the functions for different densities cross each other at some energy . thus , at small energies the larger distribution function corresponds to smaller density . to clarify the role of the functions @xmath9 , which have been found here , we have calculated the density of free spins @xmath22 and the distribution function @xmath133 for a simplified function @xmath144 used in ref.@xcite . @xmath145 in these calculations we used our residual density @xmath146 . the results are shown in fig . 4 by the dashed lines . one can see that the difference is large . the distribution function for our more accurate form of the exchange constant became narrower and the decline in the beginning is steeper . this comes from the different behaviors at small distances . it is interesting to compare the numerical scaling calculations by bhatt and lee@xcite with our method of calculation @xmath47 . we have found that at the smallest density used in ref . @xcite both methods give similar results , but for larger densities there is a small deviation . we think that both methods are exact in the limit of small densities , but the method of bhatt and lee works in a wider range , because they take into account the renormalization of weak bonds caused by their strong neighbors . however , the great advantage of our method is that it gives an analytical expression for @xmath128 . this work is supported by the australian research council and by the seed grant of the university of utah . a. l. efros and v. v. flambaum are grateful to the center for theoretical physics in trieste for hospitality during the work on this project . a. l. efros is grateful to r. bhatt , d. mattis , and b. sutherland for helpful discussions . i. ponomarev acknowledge fruitful discussions with m. kuchiev and g. gribakin . the exchange constant for the hamiltonian ( [ h1 ] ) is determined by @xmath147 because of the fermi statistics the two - electron wave function is antisymmetric with respect to permutation . therefore , the symmetric coordinate wave function corresponds to spin @xmath31 and the antisymmetric one corresponds to @xmath30 . let us consider the more general hamiltonian @xmath148 where @xmath149 and @xmath150 are effective potentials of interaction between the electron and the corresponding atomic residue , which is of the coulomb type far from the atoms : @xmath151 . the electron energy @xmath152 is accurate up to terms @xmath153 . here @xmath154 and @xmath155 are electron binding energies in the given `` atom '' . when @xmath118 the most appropriate method for determination of the energy terms splitting due to the spin - spin interaction is the gorkov - pitaevskii method @xcite . since @xmath9 is exponentially small as @xmath156 , @xmath157 and @xmath158 are solutions of the same schrdinger equation , and therefore , with exponential accuracy their combinations @xmath159 are also the solutions of the same schrdinger equation with the hamiltonian ( [ h12d ] ) . they correspond to the states of `` distinguishable '' particles , when , e.g. for @xmath160 , the first electron is principally located near the first ion at @xmath161 and the second electron near the second ion with @xmath162 . here @xmath163 is the distance between `` nuclei '' , which we place at the points @xmath164 on the @xmath165 axis . in the main region of the electron distribution , the wave functions @xmath166 are products of the atomic single - particle wave functions with the asymptotic behavior of the radial atomic wave functions of the electron in the coulomb field of the atomic residue being determined by the formulas @xmath167 indeed , for large @xmath168 the potential is @xmath169 , and the single - particle wave function of the electron obeys the equation @xmath170 it has the asymptotic solution ( [ assymh ] ) up to @xmath171 accuracy . the coefficients @xmath172 are determined by the behavior of the wave functions of the electron inside the atoms . it is possible to show@xcite that @xmath173_{x_1=x_2}~dx_2~dy_1~dy_2.\ ] ] our main purpose is to find the wave function @xmath166 . let us suppose that @xmath166 has the form @xmath174 where @xmath175 have the behavior of ( [ assymh ] ) and @xmath176 is a slowly varying function of @xmath177 and @xmath178 . substituting @xmath179 into the wave equation and neglecting the second derivatives of @xmath176 , we obtain @xmath180\chi = 0.\ ] ] equation ( [ chieq ] ) is valid under the conditions @xmath181 the general solution of ( [ chieq ] ) is @xmath182 where @xmath183 are integrals of the motion of the ordinary differential equations : @xmath184^{-1}.\ ] ] hence @xmath185^{\frac{1}{\alpha+\beta } } } { [ a - x_1]^{1/\alpha}[a+x_2]^{1/\beta}}f\left ( \frac{x_1}{\alpha}+ \frac{x_2}{\beta}\right ) , \ ] ] where the unknown function @xmath186 is determined from the fact that @xmath187 when @xmath188 is arbitrary , or when @xmath189 and @xmath190 is arbitrary . finally , after expanding @xmath191 in the exponent , we obtain @xmath192\chi(\vec{r}_1,\vec{r}_2),\\ \chi(x_1,x_2,y_{12})&=&\nonumber\end{aligned}\ ] ] @xmath193^{\frac{1}{\alpha } } \alpha^{-\frac{\alpha}{(\alpha+\beta)\beta } } \left[\frac{\beta ( a+x_1)+\alpha ( a+x_2)}{a+x_2}\right]^{\frac{1}{\beta } } \left[\frac{\sqrt{(x_1-x_2)^2+y_{12}^2}-x_1+x_2 } { \sqrt{\left(\beta ( a+x_1)+\alpha ( a+x_2)\right)^2+(\alpha y_{12})^2 } + \beta ( a+x_1)+\alpha ( a+x_2)}\right]^{\frac{1}{\alpha+\beta } } \\ e^{-\frac{a - x_{2}}{2a\beta } } \left[\frac{2a}{a+x_2}\right]^{\frac{1}{\beta } } \beta^{-\frac{\beta}{(\alpha+\beta)\alpha } } \left[\frac{\beta ( a - x_1)+\alpha ( a - x_2)}{a - x_1}\right]^{\frac{1}{\alpha } } \left[\frac{\sqrt{(x_1-x_2)^2+y_{12}^2}-x_1+x_2 } { \sqrt{\left(\beta ( a - x_1)+\alpha ( a - x_2)\right)^2+(\beta y_{12})^2 } + \beta ( a - x_1)+\alpha ( a - x_2)}\right]^{\frac{1}{\alpha+\beta } } \end{array}\right.\ ] ] here the upper expression is given for @xmath194 , and the lower expression for @xmath195 . substituting ( [ wffin ] ) in eq . ( [ jvsint ] ) , and differentiating only the exponential we obtain @xmath196_{x_1=x_2=x}\ , d\,x\,d\,y_1d\,y_2\ ] ] introducing the notations @xmath197 and @xmath198 and taking into consideration the fact that at the approximation ( [ chicon ] ) @xmath199 ^ 2+(\beta y_{12})^2 } + ( \beta+\alpha)(a - x)\approx 2(\beta+\alpha)(a - x).\ ] ] the formula ( [ jgen ] ) transforms to @xmath200,\ ] ] where @xmath201 is the following function : @xmath202 in the case @xmath203 it is independent of @xmath1 : @xmath204 and @xmath205 for the two - dimensional hydrogen molecule ( @xmath206 ) it gives @xmath207 to find @xmath99 one should consider the singlet - triplet splitting of two impurities which are at a distance much smaller than the bohr radius of one impurity state . the motion of electrons is restricted by the plain , so this is as a `` two - dimensional helium atom '' . in this case the variational approach is the most appropriate . the hamiltonian is : @xmath208 and schrdinger s variational principle is @xmath209 the most important thing is the correct choice of the coordinate system . namely , it is better to choose as independent variables those that the potential energy depends on . these are the three sides of the triangle @xmath177 , @xmath178 , @xmath210 between the nucleus and two electrons@xcite . the hamiltonian and , as we expect , the wave functions for @xmath51 terms do not depend on the orientation of the triangle in the space : @xmath211 @xmath212 therefore , the volume element @xmath213 is @xmath214 finally , we introduce the `` elliptic '' coordinates @xmath215 which reflect the symmetry of two - particle eigenfunction : the wave function has to be an even function of @xmath216 for total spin @xmath31 , and an odd function of @xmath216 for @xmath30 . thus , @xmath217 the factor @xmath218 can be omitted , and if we take into consideration the fact that @xmath219 we can restrict the integration region by the inequalities : @xmath220 the potential energy in the new coordinates is @xmath221\,d\tau= \nonumber\\ & = & \int_0^{\infty}ds\int_0^s du\int_0^u\left ( \frac{u(s^2-t^2)}{\sqrt{(s^2-u^2)(u^2-t^2)}}\left [ \left(\frac{\partial\psi}{\partial s}\right)^2 + \left(\frac{\partial\psi}{\partial t}\right)^2 + \left(\frac{\partial\psi}{\partial u}\right)^2\right]\right.+\nonumber\\ & + & \left . 2\frac{\partial\psi}{\partial u}\left [ s\sqrt{\frac{u^2-t^2}{s^2-u^2}}\frac{\partial\psi}{\partial s}+ t\sqrt{\frac{s^2-u^2}{u^2-t^2}}\frac{\partial\psi}{\partial t } \right]\right)dt \end{aligned}\ ] ] where @xmath226 and @xmath227 are defined by eqs . ( [ vsp]),([poten ] ) , and ( [ kinen ] ) correspondingly . here , in order to find @xmath228 we used the values of the following integrals : @xmath229^{\mp 1/2}dt&=&\frac{\pi}{2}\left\ { \begin{array}{ll } i_0\left(b\right ) & \qquad \mbox{(see \cite{rizhik } , 3.534.2 ) } \\ i_1\left(b\right)/b , & \end{array}\right . \nonumber\\ \int_0^{\infty}x^{n-1}e^{-x}\frac{i_{\nu}(cx)}{c^{\nu}}dx & = & ( -1)^{n-1}\frac{\partial^{n-1}}{\partial p^{n-1}}\left[\frac { ( p+\sqrt{p^2-c^2})^{-\nu}}{\sqrt{p^2-c^2}}\right]_{p=1 } \quad \mbox { ( see \cite{prud } , 2.15.3)}\nonumber\end{aligned}\ ] ] thus , the energy is @xmath230 we can also rewrite it in the form : @xmath231 the minimum value of the energy is realized for values of @xmath232 and @xmath107 which satisfy the equations @xmath233 or @xmath234 eliminating @xmath232 , we get the equation in @xmath107 @xmath235 it has the solution @xmath236 . then , @xmath237 the corresponding values of @xmath238 and @xmath239 are @xmath240 for comparison we also represent the results for the one - parameter wave function @xmath241 : @xmath242 thus , the difference between these two ground state energies ( [ e2par ] ) and ( [ e1par ] ) is @xmath243 . taking into consideration the screening effect of the electrons we construct our trial wave function from an antisymmetric combination of the @xmath245-electron in a field of the charge @xmath246 and the orthogonal @xmath247-electron state in a field of the charge @xmath248 : @xmath249 or rewriting in @xmath250 , @xmath216 variables : @xmath251,\\ \alpha & = & \frac{\alpha_1+\alpha_2}{2},\nonumber\\ \beta&=&\frac{\alpha_1-\alpha_2}{2}. \end{aligned}\ ] ] performing a procedure similar to , though more tedious than , the @xmath252 case we obtain the following results ( @xmath253 ) : @xmath254 here @xmath255 from minimizing @xmath256 we find @xmath257 which correspond to the effective charges @xmath258 and @xmath259 . for these values of @xmath260 and @xmath232 we get the energy @xmath261 it is worthwhile to note that for the wave function with @xmath262 and @xmath263 the energy @xmath264 is only higher by @xmath265 ! b. i. shklovskii , a. l. efros , `` electronic properties of doped semiconductors '' , springer - verlag , berlin heidelberg , 1984 . i. s. shlimak , in _ hopping and related phenomena _ , edited by h. fritzsche and pollak ( world scientific , singapore , 1990 ) p. dai , y. zhang , m. p. sarachik , phys . * 69 * , 1804 ( 1992 ) . d. simonian , s. v. kravchenko , m. p. sarachik , v. m. pudalov , phys . rev . , * 79 * , 2304 ( 1997 ) . s. ishida , k. oto , s , takaoka , k. murase , s. shirai , and t. serikawa , phys ( b ) * 205*,161 ( 1998 ) . i. s. shlimak , s. i. khondaker , j. t. nicholls , m. pepper , and d. a. ritchie , unpublished . k. m. mertes , d. simonian , s. v. kravchenko , t. m. klapwijk , preprint cond - mat/9903179 . m. rosso , phys . lett . , * 44 * , 1541 ( 1980 ) . r. n. bhatt , phys . * 48 * , 707 ( 1982 ) . r. n. bhatt , p. a. lee , j. appl . physics , * 52 * , 1703 ( 1981 ) . k. andres , r. n. bhatt , p. goalwin , t. m. rice , and r. e. walstedt , phys . b * 24 * , 244 ( 1981 ) . r. n. bhatt , p. a. lee , phys . lett . , * 48 * , 344 ( 1982 ) . p. a. thomas , m. rosso , phys . b , * 34 * , 7936 ( 1986 ) . r. n. bhatt , d. s. fisher , phys . , * 68 * , 3072 ( 1992 ) . m. j. hirsh , d. f. holcomb , r. n. bhatt , m. a. paalanen , phys . * 68 * , 1418 ( 1992 ) . g. staszewska and l. wolniewicz , j. mol . specroscopy , 1999 ( to be published ) ; w. kolos and l. wolniewicz , chem . lett . , * 24 * , 457 ( 1974 ) ; l. wolniewicz , jcp * 99 * , 1851 ( 1993 ) l. p. gorkov and l. p. pitaevskii , soviet phys . doklady , * 8 * , 788 ( 1964 ) ; c.herring and m. flicker , phys . rev . , * 134 * , a362 ( 1964 ) . b. m. smirnov and m. i. chibisov , soviet phys . jetp , * 21 * , 624 ( 1965 ) . v. v. flambaum , i. v. ponomarev , and o. p. sushkov phys . b , * 59 * , 4163 ( 1999 ) a. a. radtsig and b. m. smirnov , parameters of atoms and atomic ions , energoatomizdat , moscow , 1986 . a. l. efros , v. v. flambaum , and i. v. ponomarev , unpublished i. s. grandshteyn and i. m. ryzhik , table of integrals , series , and products , academic press , inc , 1980 . a. p. prudnikov , _ et al . , _ integrals and series , v.2 , nauka , moskow , 1983 . h. a. bethe and e. e. salpeter , quantum mechanics of one and two electron systems , springer , berlin , 1957 .

the exchange interaction between electrons located at different randomly distributed impurities is studied for small density of impurities . the singlet - triplet splitting @xmath0 is calculated for two coulomb centers at a distance @xmath1 . interpolated formulas are found which work for all distances @xmath1 from zero to infinity . the data from atomic physics are used for the interpolation in three - dimensional case . for two - dimensional case the original calculations are performed to find asymptotic behavior of the splitting at large @xmath1 , the splitting for the `` two - dimensional helium atom '' ( @xmath2 ) and the splitting at @xmath3 , where @xmath4 is the effective bohr radius . the spin structure of impurity band is described by the heisenberg hamiltonian . the ground state of a system consists of localized singlets . the new results are obtained for the distribution of the singlet pairs in the ground state . these results are exact at low density . the problem is reduced to a non - trivial geometric problem which is solved in the mean field approximation and by computer modeling . the density of free electrons is found as a function of temperature and the distribution function of the singlet - triplet transitions energies is calculated . both functions are given in an analytical form .

massive hemoptysis is a life - threatening pulmonary emergency and has a variety of underlying conditions . transcatheter bronchial artery embolization ( bae ) is a well - established and effective non - surgical procedure for the management of massive hemoptysis ( 1 ) . recently , non - bronchial systemic arteries have been reported as an important source of bleeding with massive hemoptysis . computed tomography ( ct ) and computed tomography angiography ( cta ) we herein report a rare case of massive hemoptysis in a patient with focal bronchiectasis and right inferior phrenic artery - to - right pulmonary artery fistula diagnosed by ct and cta . an 82-year - old woman was transferred to our hospital because of dyspnea and massive hemoptysis . the patient had a history of bronchial asthma that was well - controlled with bronchodilator medications . she suffered from severe hypoxemia ( ph 7.362 , pco2 35.1 mmhg , po2 61.0 mmhg , hco3 20.1 mmhg , be -5.5 mmhg , spo2 90.5% , under 10 l o2/min , reservoir mask ) . a chest ct further demonstrated multiple consolidations and ground glass opacity and focal bronchiectasis in right segment 4 ( s4 ) ( fig . since there was no active hemorrhaging from the tracheal tube , she was then extubated . computed tomography showed multiple consolidation and ground glass opacities . to determine the origin of bleeding , she underwent contrast - enhanced ct , which showed bronchiectasis in right s4 and regression of the infiltration . cta revealed an abnormal vascular anastomosis between the right inferior phrenic artery and right pulmonary artery beside the focal bronchiectasis at the right middle lobe ( fig . 3 ) , which led us to suspect it as the possible source of the massive hemoptysis . three weeks after the embolization , she was successfully discharged and has been free from recurrent hemoptysis for three years . a : a high - resolution computed tomography ( ct ) image showing focal bronchiectasis in the right middle lung ( s4 ) . b : ct angiography showing a vessel entering the bronchiectasis lesion arising from the right inferior phrenic artery . c : three - dimensional ct depicting the right inferior phrenic artery - to - right pulmonary artery fistula . right inferior phrenic artery angiogram confirmed the right inferior phrenic artery - to - right pulmonary artery fistula ( arrow ) in an intrapulmonary portion . the present case report describes an elderly woman who had right inferior phrenic artery - to - pulmonary artery fistula with focal bronchiectasis leading to life - threatening hemoptysis . however , recurrent hemoptysis after successful bae is not rare , and non - bronchial arteries can function as sources of bleeding in some cases ( 3 ) . in the present case , we planned bae to prevent recurrent hemoptysis and performed high - resolution ct and cta before bae . cta revealed the right inferior phrenic artery - to - pulmonary artery fistula , not the bronchial arteries , as the source of the bleeding . the bronchial arteries are responsible for bleeding in more than 90% of cases with massive hemoptysis . in the remaining 10% of cases , the internal mammary , intercostal , and inferior phrenic artery are typically involved in hemoptysis ( 3,4 ) . in most of the reported cases of inferior phrenic artery origin , the lower lobe of the lung was affected with chronic inflammation and found to be the site of bleeding ( 5 - 8 ) . transpleural systemic - pulmonary artery anastomoses may develop in patients with bronchiectasis , cystic fibrosis , tuberculosis , or chronic pneumonia ( 5 ) . in the present case , a right inferior phrenic artery - to - right pulmonary artery fistula was the origin of bleeding in the right middle lobe , instead of the lower lobe . the present paper demonstrates that , for effective bae in patients with massive hemoptysis , ct and cta should be performed beforehand to precisely identify the culprit lesion for bleeding .

massive hemoptysis is a medical emergency and needs immediate treatment . it occurs in a wide variety of pulmonary diseases and typically originates from the bronchial arteries . we herein report a very rare case of a patient bleeding from a right phrenic artery - to - pulmonary artery fistula accompanied with focal bronchiectasis in the right middle lobe of the lung . in this case , multi - detector computed tomography was useful for clarifying the etiology and the abnormal anastomosis and facilitated effective angiographic embolization .

long - term monitoring of sgr a * has thus far resulted in the discovery of several near - ir @xcite and x - ray flares @xcite from this object . one of the most recent events , observed with _ xmm - newton _ in 2004 , has produced compelling evidence of a significant modulation in the x - ray lightcurve with a quasi - period @xmath2 minutes @xcite . similar periodic fluctuations had also been seen earlier in the near - ir events . a period of @xmath2 minutes is rather intriguing because simple considerations @xcite would place the corresponding emission region at roughly 3 schwarzschild radii ( @xmath3 ) for a black hole ( bh ) mass of @xmath4 m@xmath5 @xcite . it is not yet understood , however , why the keplerian radius corresponding to this period is actually less than @xmath6 . it could be that the difference is due to the spin of the bh , which moves the inner disk radius inwards for prograde rotation . or it could be that the so - called stress edge the location where the inspiralling material actually detaches from the rest of the magnetized disk is dynamically important in establishing where the disk emission terminates @xcite . part of the uncertainty is due to the fact that the structure of the disk surrounding sgr a * is itself not fully understood yet . we have recently begun to simulate the behavior of the hot , magnetized disk during a disruptive event that may be responsible for the flares , under the assumption that the instability is induced by low angular momentum clumps of plasma raining " inwards towards the keplerian region ( tagger & melia 2006 ; see also chan et al . this scenario is motivated by extensive hydrodynamic @xcite and mhd @xcite simulations which show that for the stellar - wind fed conditions at the galactic center , the average specific angular momentum of gas captured gravitationally by sgr a * is too small to sustain a ` conventional ' ( i.e. , typically large @xmath7 ) disk . instead , only clumps of plasma with relatively small angular momentum venture inwards and merge with essentially , ` rain ' onto the compact disk at the circularization radius , which for sgr a * is @xmath8 ( see also * ? * ; * ? ? ? these mhd simulations @xcite did indeed establish the result that the merger of an infalling blob with the existing keplerian flow induces a rossby wave instability ( rwi ) leading to the total disruption of the disk on a timescale relevant to the sgr a * flare phenomenon . but unless the ensuing x - ray modulation is due to a qpo response in the inspiralling matter ( see chan et al . 2006 ) , one can not escape the fact that general - relativistic effects are essential in producing a periodicity in the lightcurve due to radiation by an azimuthally asymmetric emitter . the pattern of modulation over one complete cycle would be the result of several influences , including a doppler shift , light - bending , and lensing effect near the bh s event horizon ( e.g. , * ? ? ? * ) . in this _ letter _ , we take the results from the ( non - relativistic ) mhd simulation of @xcite and carry out a full ray - tracing calculation of the lightcurve produced by the disruption for direct comparison with the _ xmm - newton _ data . an inspection of fig . 5 in @xcite shows that the effects of gravitational light - bending , lensing , doppler effect and travel time delay may have helped to shape the folded lightcurves from the 2004 august 31 event . one can not yet discount the possibility that an actual periodic dynamical effect may have also contributed to the modulation seen in the emissivity , but this is necessarily model - dependent and the signature may not be unique . for example , tagger & melia ( 2006 ) found that a quasi - periodic modulation could be excited by non - linearities in the evolution of the spiral - rossby pattern , which would sit on top of the modulation one would see due to general relativistic effects . for the purposes of this _ letter _ , we will adopt the simplest assumption that the modulation is due predominantly to general relativistic effects . the 210 kev folded curve from the 2004 august 31 event ( see fig . [ fig : fig3 ] ) looks broader and , except for one significant datum standing well away from the rest , looks more like a continuous , relatively smooth modulation rather than the sharp changing profile produced by an orbiting hot spot ( see e.g. , * ? ? ? it is partially for this ( phenomenological ) reason that the rossby wave instability is promising and worth investigating further here , because the disruption it causes is global , offering the possibility of producing a gradual modulation in the lightcurve when general relativistic effects are included . the instability we have simulated with our mhd code has a long history , dating back to @xcite , who showed that a disk presenting an extremum of a quantity @xmath9 ( later dubbed vortensity ) was subject to a local instability of rossby vortices . the requirement of an extremum is similar to that giving rise to the kelvin - helmholtz instability of sheared flows . more recently , @xcite renamed it the rossby wave instability ( rwi ) and developed the theory and numerical simulation . in isothermal , unmagnetized disks , @xmath9 is the specific vorticity averaged across the disk thickness , @xmath10 where @xmath11 is the disk s surface density , @xmath12 its rotation frequency , and @xmath13 is the epicyclic frequency squared . the extremum of @xmath9 appears to be due to an extremum in the radial density profile . to understand how the instability is driven , we note that rossby waves in disks form normal modes trapped near the extremum of @xmath14 . in the mhd form of the rwi , the disk is threaded by a vertical ( poloidal ) magnetic field @xmath15 . its properties are essentially the same as those discussed above , except that here the critical quantity is @xmath16 and the growth rate can be higher because of the long - range action of the lorentz force coupling the rossby vortices . a typical profile of the inner disk during the rossby wave growth is shown in fig . 3 of @xcite . in this paper , we present the lightcurve and images associated with this disruption , from the vantage point of an observer at infinity . the calculation is carried out with a fully general relativistic ray - tracing code . the rwi arises in the compact accretion disk surrounding the ( schwarzschild ) bh , and we describe its morphology using coordinates in the co - rotating frame ( @xmath17 ) . the modeled accretion disk is thin and the rwi may be considered to lie in the equatorial plane ( @xmath18 ) of the compact object . the observer is located at infinity with viewing angle _ i _ relative to the @xmath19-axis in the non - rotating frame , at ( observer ) polar coordinates ( @xmath20 ) . the deflection angle of a photon emitted by plasma in the rossby - unstable region is @xmath21 , and varies periodically with @xmath22 . these emitted photons are deflected by the bh and intersect the observer s detector plane at infinity . the distance between the line - of - sight and the point at which the photon reaches the detector is defined as the impact parameter _ b_. using this geometry , the deflection angle of the photon s trajectory may be obtained with the light - bending relation between @xmath23 ( the angle between the emission direction of the photon and the direction from the center of the bh to the location of the emitter ) and @xmath21 from the geodesic equation @xmath24\;. \label{eq : psi}\ ] ] this procedure yields the impact parameter @xmath25 of the photons in terms of the emitting radius @xmath26 , and ultimately allows us to calculate the flux at infinity . a detailed description of this geometry is provided in , e.g. , @xcite , and @xcite . in our derivation , we shall use the same notation and geometry described in @xcite , though pertaining to a localized region ( or clump ) in the disk . the system of units is chosen such that @xmath27 ; in this standard coordinate system , the bh s horizon occurs at the schwarzschild radius @xmath28 , where @xmath29 is the mass of the compact object . in the simulations we report here , the emitting region is geometrically thin , and generally optically thin as well . our rays include an integration through the whole emitting depth , but because most of the emissivity is concentrated near the disk s plane , we effectively have a situation in which the rays themselves appear to begin very close to this plane . rays leaving the disk in directions that eventually take them around the bh , heading toward the observer , contribute much less to the overall flux and we ignore them here . the general - relativistic effects to be considered are now : ( _ i _ ) light - bending ( see above ) , ( _ ii _ ) gravitational doppler effect defined as ( 1+z ) , ( _ iii _ ) gravitational lensing effect , @xmath30 ( with @xmath31 the distance to the source ) , expressed through the impact parameter , and ( _ iv _ ) the travel time delay . we calculate the relative time delay between photons arriving at the observer from different parts of the disk , using the geodesic equation . the first photon reaching the observer is the photon emitted at phase @xmath32 , on the closest radius ( @xmath33 ) to the observer . we set this reference time , @xmath34 , equal to zero . the observed flux at energy @xmath35 is @xmath36 , where @xmath37 is the radiation intensity observed at infinity and @xmath38 is the solid angle on the observer s sky including relativistic effects . using the relation @xmath39 , a lorentz invariant quantity that is constant along null geodesics in vacuum , the intensity of a light source integrated over its effective energy range is proportional to the fourth power of the redshift factor , @xmath40 , @xmath41 being the intensity measured in the rest frame of the clump @xcite . although our magnetohydrodynamic simulation , and corresponding ray - tracing calculation , are quite sophisticated , they are nonetheless still somewhat restricted in that we have not allowed for a completely self - consistent coupling between the plasma and the radiation . the infalling plasma radiates inefficiently , so this is not a serious deficiency as far as the dynamics is concerned . furthermore , properly modelling the compression of the gas would require fully 3-d simulations , which mhd codes are still unable to handle in the conditions ( a disk threaded by a near - equipartition vertical field ) that we use . for simplicity , the mhd simulation was thus carried out assuming isothermal conditions . however the electron temperature , which dominates the radiative emission , responds to the compression of the gas and we model this here with an ad - hoc prescription , from the compression obtained in the simulation . this is sufficient to provide the main result of the present work , which is the form of the light curve that the spiral pattern and general relativistic effects generate . also , we have not included non - local effects arising , e.g. , from inverse compton scattering . in determining the surface emissivity , it therefore makes sense to take a simplified approach in which we include principally the parameter scalings , rather than their absolute values . this procedure will give us correct amplitudes in the lightcurve , though not the absolute value of the flux per se . using the perfect gas law for an _ adiabatic _ flow ( since the gas is radiatively inefficient ) , we can invoke a polytropic equation of state with @xmath42 and write the temperature as @xmath43 . this assumes further that the radiation pressure is negligible and @xmath44 is not so high that the particles are strongly relativistic . although the disk is not in full hydrostatic equilibrium , we can still argue that on average , we should have for a steady thin disk the gas density @xmath45 , where @xmath11 is the column density , and @xmath46 is the disk height . these give @xmath47 ( using @xmath26 to denote the radius in the equatorial plane ) and @xmath48 . the synchrotron emissivity is therefore @xmath49 , where the nonthermal particle energy is roughly in equipartition with the thermal . we argue that the plasma is fully ionized and resistivity is minimal , so @xmath50 is frozen into the gas , which means that @xmath51 . we therefore infer that @xmath52 . now the x - rays are produced via inverse compton scattering from the seed photon number flux . thus , with @xmath53 , where @xmath54 is the synchrotron emissivity in units of energy per unit volume per unit time , the soft photon flux scales as the emitted power divided by the characteristic area . that is , @xmath55 , which is going to be roughly the same scaling as the seed photon density , so @xmath56 . the inverse compton scattering emissivity is therefore @xmath57 . thus , @xmath58 , and the surface intensity is @xmath59 , which gives finally @xmath60 . the core physics in this expression is the surface density @xmath61 , which we take from the mhd simulation in @xcite . in order to evaluate the flux at a given azimuthal angle @xmath62 and radius @xmath26 , we first compute numerically @xmath63 , and then calculate the dopper shift , lensing effects , and finally the flux @xmath64 as a function of the arrival time , including all the travel time delays described above . the simulation is carried out on a polar grid with @xmath65 and @xmath66 points , extending from @xmath67 to @xmath68 . in this pass through the problem , in order to clearly separate the general relativistic modulation from the complex dynamical behaviour observed during the simulation , we have chosen to take a representative snapshot and rotate it at the frequency measured in the simulation . a full treatment of the whole simulation will be presented in @xcite . our principal results are presented graphically below , and may be understood with reference to the simulated images shown in fig . [ fig : fig1 ] . these are intensity maps projected onto the plane of the sky , for the ray - traced perturbed disk in @xcite , at three different inclination angles : @xmath69 in the top row , @xmath70 in the middle , and @xmath71 for the bottom row . the four columns are snapshots taken at 4 ( equally - spaced ) phases of one complete pattern revolution . the general relativistic distortions depend strongly on inclination angle , which we employ in our search for the best fit to the modulation in the x - ray lightcurve . this variation is demonstrated quantitatively in fig . [ fig : fig2 ] , which shows the lightcurves corresponding to the three inclinations illustrated in fig . [ fig : fig1 ] . note that at small inclination , we detect a gradual , broad modulation , whereas for the higher inclinations , we begin to see the effects of a two - spiral arm emitting region . interestingly , the period associated with the pattern rotation in the @xcite simulation is about 50 minutes . though this calculation was not optimized to fit the observed period , the fact that we see a bimodal modulation from the two spiral arms suggests that one cycle in the data may in fact correspond to half a revolution of the pattern . in this figure , we therefore also show the calculated lightcurve folded over half a pattern period , corresponding to about 25 minutes . the true test of relevance for this simulation lies in a direct comparison between the data and the inclination - dependent lightcurves . we emphasized in the introduction that the various relativistic effects produce a unique profile , not easily confused with other periodic modulations , most of which tend to be sinusoidal . as we demonstrate in fig . [ fig : fig3 ] , the shape of the calculated lightcurve , particularly its amplitude , is quite sensitive to the inclination angle , which again , is most easily understood with reference to fig . [ fig : fig1 ] . for example , this figure includes 3 curves , corresponding to inclinations of @xmath72 , @xmath73 , and @xmath71 . the middle curve produces the best fit ( @xmath74 ) , and it should be noted that the correspondence to the data is excellent , not only in terms of the modulation amplitude , but also for the shape of the lightcurve itself . note that the simulated lightcurve corresponds to the bolometric flux emission . we have therefore compared the theoretical curve with the observed 210 kev lightcurve , rather than individually in different energy bands , as presented in blanger et al . ( 2006 ) . there are several new ideas that we can take away from this work . first , if the periodic modulation seen in some flares from sgr a * by both ir and x - ray instruments is real , it is not at all obvious that the periodicity is due to an underlying keplerian period . one must be very careful , therefore , in over - interpreting these periods in terms of a bh spin . second , the shape of the x - ray lightcurve in this particular flare is too broad for it to correspond easily to a highly localized hot spot on the disk , which instead would produce a more strongly peaked profile like that investigated earlier by @xcite . instead , our work here argues for a more global disruption in the disk , at least for some events , like the 2004 , august 31 flare observed with _ xmm - newton_. in this regard , the driving mechanism is likely to be an infall of clumps of plasma that merge with the existing compact disk and induce a rossby - type of instability . finally , the observed power density spectrum shows that the ( quasi)-period is quite clean , without any evidence that the emission region is spread over a large range in keplerian periods . this has been taken as some evidence that the disturbance must therefore be highly localized , probably near the marginally stable orbit . but as we have shown here , the disturbance need not be that close to the event horizon in order to produce a modulation with a period of only @xmath77 minutes . one may still get a narrow peak in the power density spectrum , as long as the modulation is due to a pattern rotation , rather than to motion along an orbit . but this will only work as long as the pattern has multiple components , such as the two spiral arms we have modeled in this paper . the research was partially supported by the french space agency ( cnes ) and nsf grant ast-0402502 at the university of arizona . fm is grateful for the hospitality of the apc in paris , where most of this work was carried out .

near - ir and x - ray flares have been detected from the supermassive black hole sgr a * at the center of our galaxy with a ( quasi)-period of @xmath0 minutes , suggesting an emission region only a few schwarzschild radii above the event horizon . the latest x - ray flare , detected with _ xmm - newton _ , is notable for its detailed lightcurve , yielding not only the highest quality period thus far , but also important structure reflecting the geometry of the emitting region . recent mhd simulations of sgr a * s disk have demonstrated the growth of a rossby wave instability , that enhances the accretion rate for several hours , possibly accounting for the observed flares . in this _ letter _ , we carry out ray - tracing calculations in a schwarzschild metric to determine as accurately as possible the lightcurve produced by general relativistic effects during such a disruption . we find that the rossby wave induced spiral pattern in the disk is an excellent fit to the data , implying a disk inclination angle of @xmath1 . note , however , that if this association is correct , the observed period is not due to the underlying keplerian motion but , rather , to the pattern speed . the favorable comparison between the observed and simulated lightcurves provides important additional evidence that the flares are produced in sgr a * s inner disk .

DAWSON CITY, Yukon Territory—"You can drink it fast, you can drink it slow. But the lips have gotta touch the toe." So goes the regular incantation here in the Downtown Hotel's Sourdough Saloon, in the heart of Dawson City—itself the heart of the Klondike's new gold rush. Robert Service, the bard of the Yukon, wrote that "There are strange things done in the midnight sun/By the men who moil for gold." Few are stranger than the saga of the Sourtoe Cocktail. Garnished with a preserved human toe, this digital drink is administered nightly to crowds of tourists, trappers and miners. Many are chasing down Dawson's new gold rush, which has seen roughly 50,000 new claims staked in the region in the past two fiscal years, up from just a couple thousand claims per year previously. This city of 1,800 now swells to roughly 4,000 during the summer since gold prices spiked. And the Sourtoe—a local attraction that has gained notice and travel-guide mentions over the past 39 years—is drawing a new generation of those eager to prove themselves true Yukoners (or, in local parlance, "sourdoughs") by downing the tawdry tipple. The idea was born in 1973, when riverboat captain Dick "River Rat" Stevenson found a severed big toe preserved in a pickle jar in a cabin outside of town. Capt. Dick, as he is known, says he came up with the original rules for the drink over the course of a drunken evening with friends: take a beer glass full of champagne, drop in the toe, tip the glass back…and the toe must touch the lips. In September 1973, eight people participated in the first attempt; nearly four decades later, the Sourtoe Cocktail Club has an estimated 100,000-plus members. You can now "do" the Sourtoe with any beverage (Yukon Jack whisky liqueur preferred). It costs $5. There is a ceremony performed by the night's "toe captain," a logbook to sign and a certificate of membership awarded. While it may sound unsanitary, the toes are pickled for months in medical alcohol and then packed in dry salts. "There is no issue with the toe," says Patricia Living, communications director for Yukon Health and Social Services. "The risk of freezing on the way to the bar or being attacked by a pack of wolves would be higher." "I think the aesthetics are more worrisome than the health aspect," said Stephen S. Morse, professor of clinical epidemiology at Columbia University's Mailman School of Public Health. "I doubt there's much that anyone would catch from it." "The Sourtoe would be shut down most anywhere else," says Capt. Dick, now 82 and retired to the Yukon's capital city, Whitehorse. He says the toe is his proudest accomplishment—that and organizing a nude beauty contest on an island in the Yukon River. He recently shipped a toe-shaped urn up to Dawson City, so his ashes can someday sit in the Sourdough Saloon. "It's hard to become famous," Capt. Dick says. "It's much easier to become infamous." And if people come looking for anything (other than gold) in Dawson City—center of the 1896 Klondike rush, just south of the Arctic Circle and roughly 300 miles from nowhere—it is a little bit of infamy. "This is the coolest thing I've ever done," said Levi Wiebe, 23, of Coaldale, Alberta, after downing the Sourtoe Cocktail on a recent night. "I got it in my mouth a little," said a chilled Caleigh Miller, 30, of Whitehorse. "It's a bit gross looking," said Chris Quickfall, 19, of Prince George, British Columbia, who heard about the toe from a hitchhiker and decided to do it for his birthday. "It tastes like plastic." There are, of course, those who can't be persuaded to partake. "Heck no, I want to live until I'm 90," said Carolyn Wingard, 64, a retired soldier from St. Augustine, Fla. "But I'll tell people I did." "We've had people throwing up, we've had people gagging on their drinks," says Dick Van Nostrand, manager at the Downtown Hotel. Real trouble, however, is when someone gets overenthusiastic. "You never know when some fool is going to do something stupid," Mr. Van Nostrand says. "And then we'll be without a toe." Indeed, many toes have been lost. The original toe touched roughly 725 pairs of lips before it was swallowed in the summer of 1980 by a placer miner. A replacement toe was swallowed in 1983. Other toes have been damaged by overzealous patrons. Despite the toes' propensity to walk away, donors keep stepping forward. After the first toe was swallowed, a woman in Fort Saskatchewan, Alberta, sent in a middle toe she had had amputated years earlier due to an inoperable corn. One toe was donated by a trapper who had lost it to frostbite. Another came by way of lawn mower accident. Steve White, 42, a chain-link fence installer in Whitehorse, got his pinkie toe amputated in January 2000 after developing hammertoe—and, having heard the story of the Sourtoe, asked the doctor to save it. Mr. White didn't get around to donating until April 2002. "The call came out from Dawson, they had no toes going into the season," Mr. White recalls. Before that, he had had it in a jar in his freezer. "My wife wasn't very happy with me," he says. Mr. White sent the toe up to Dawson City and later drove up to "do the toe" for the first time—with his own toe. "I always tell people I left a little piece of me in Dawson," he says. Next September will mark the 40th anniversary of the Sourtoe. In addition to donating his ashes, Capt. Dick wants to have a wax figurine made of himself, which would wear his captain's gear and preside over the toe in perpetuity. Still, he is worried about the future. "At this point, you can't get away with this stuff," he says. "Things are really going to hell…It's still a frontier, but not like it was." Printed in The Wall Street Journal, page A1 A version of this article appeared November 5, 2012, on page A1 in the U.S. edition of The Wall Street Journal, with the headline: No Way to Tiptoe Around It: This Drink Can Be Hard to Swallow. ||||| Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period.

– Olives, limes, maraschino cherries, and pickled toes? That's right: In the Yukon Territory, one Dawson City saloon serves a drink garnished with a human toe. The tradition began in 1973, after a riverboat captain found a toe preserved in a pickle jar and decided it would be a good idea to drop the digit into a big glass of champagne then take a drink. Since then, more than 100,000 people are estimated to have taken part in the Sourtoe Cocktail ritual at the Downtown Hotel's Sourdough Saloon. The one rule: "The lips have gotta touch the toe." Sometimes the lips touch the toe and vomiting or at least gagging ensues, the hotel manager tells the Wall Street Journal. Other times, drinkers get a little overly enthusiastic: After 725 go-rounds, the first toe was swallowed by a miner; replacement toes have also since been damaged or swallowed. But the replacements keep coming in: one from a trapper who lost a toe to frostbite, one that was the victim of a lawn mower incident, another that was amputated and saved for years in a freezer. But no matter where the current toe hails from, you needn't worry about hygiene: The toes are pickled in medical alcohol for months then placed in dry salts. "The risk of freezing on the way to the bar or being attacked by a pack of wolves would be higher," a Health and Social Services worker tells the Journal.

authors thank gleb kozlov for fruitful discussions . we acknowledge the financial support by the deutsche forschungsgemeinschaft and the russian foundation of basic research in the frame of the icrc trr 160 ( rfbr project no . 15 - 52 - 12016 nnio_a ) . the project ` spangl4q ' acknowledges financial support from the future and emerging technologies ( fet ) programme within the seventh framework programme for research of the european commission , under fet - open grant no . fp7 - 284743 . thanks the russian foundation of basic research for partial financial support ( contract no . 14 - 02 - 31735 mol_a ) . s.v.p . and i.a.yu . acknowledge partial financial support from the russian ministry of science and education ( contract no . 11.g34.31.0067 ) and spbu ( grant no . 11.38.213.2014 ) . m.b . acknowledges support from the russian ministry of science and education ( contract number 14.z50.31.0021 ) . we consider optical excitation of an inhomogeneous ensemble of two - level systems by two short laser pulses with central frequency @xmath11 close to the average frequency of the ensemble @xmath71 . for each individual two - level system the incident electromagnetic field induces optical transitions creating a coherent superposition of states . let @xmath72 denote the ground state and @xmath73 denote the dipole active , excited state . the temporal evolution of the density matrix is described by the lindblad equation : @xmath74+\gamma.\ ] ] here @xmath46 , where @xmath47 is the hamiltonian of the unperturbed system . @xmath42 describes relaxation processes phenomenologically . @xmath75 is the perturbation operator describing the interaction with the electromagnetic wave of a pulse : @xmath76 , @xmath6 is the dipole moment of the optical transition to state @xmath73 , @xmath77 is the envelope of the electric field of the pulse . here the rotating wave approximation is used . for simplicity , we consider pulses with rectangular shape of amplitude @xmath5 and assume that the pulse duration , @xmath49 , is significantly shorter than all relaxation processes . at the end of a short pulse , the density matrix elements are @xcite : _ 00(_p)&=&_00(0)- _ p + & + & ( 1- _ p ) , + _ 11(_p)&=&_11(0)+ _ p + & - & ( 1- _ p ) , + _ 01(_p)&= & ( i_p ) . [ eq : eq5a ] here , @xmath12 is the detuning between the optical frequency @xmath11 and the resonance frequency of the individual two - level system @xmath13 . @xmath78 is proportional to the smooth envelope of the pulse : @xmath79 in the rectangular pulse approximation , @xmath78 is constant during the pulse action , thus , @xmath80 , where @xmath16 is the rabi frequency . let us consider now the interaction of the two - level system with two pulses separated by the time , @xmath2 . we assume that before excitation with the first pulse all two - level systems are in the ground state @xmath72 and , therefore , only @xmath81 . the density matrix elements after this first pulse are @xcite : _ 00(_p)&=&_00(0 ) -(1-_1 _ p ) , + _ 11(_p)&= & ( 1-_1 _ p ) , + _ 01(_p)&= & ( i_p ) f_1^*_00(0)2_1 ^ 2 . [ eq : eq5a ] here the index @xmath82 indicates the first pulse . after the pulse , the elements of the density matrix relax with different characteristic times . we assume that @xmath83 describing the optical coherence relaxes with the dephasing time @xmath84 : @xmath85\exp\big[-(t-\tau_p)/t_{2}\big]$ ] . after the action of the second pulse we need only the following term in @xmath83 for calculation of the photon echo : _ 01(_12 + 2_p ) & & ( i_p ) . finally , after two pulses : _ 01(t ) & & + & & ^2(_2_p/2 ) . the measured photon echo signal from the ensemble of two - level systems is proportional to the sum over all @xmath13 : @xmath86 , where @xmath87 is the distribution function of the ensemble . if the distribution function is gaussian with a central frequency @xmath88 and a dispersion @xmath10 , this gives the following form of the echo signal : & & . + [ p_pe_abs ] in order to calculate the two - dimensional fourier spectrum ( 2dfs ) of a photon echo ( pe ) , we integrate the pe field over the two temporal varaibles that determine the delay between the laser pulses , @xmath89 , and the laboratory time , @xmath90 . to that end we rewrite eq.([p_pe_abs ] ) : figure [ som_fig ] demonstrates the results of corresponding 2dfs calculation after eq.([2dfts ] ) for tls ensemble excitation with different areas , @xmath64 of the first pulse . the 2dfs spectra are normalized to unity . the first case shown in fig . [ som_fig](a ) accords with a traditional hahn echo , for which no temporal shift of the pe is expected . here , the 2dfs has only a real part . note that the weak fringes in the plot are an artifact due to taking the fourier transform over finite intervals . in case of weak excitation ( linear regime ) of a strongly inhomogeneous system similar to the one studied experimentally , the temporal shift of the pe gives rise to a significant imaginary part of the 2dfs with a dispersive shape and a sign reversal along the diagonal , as shown in fig . [ som_fig](b ) . when increasing the power of the first excitation pulse further to a @xmath23-pulse , see fig . [ som_fig](c ) , also the real part of the 2dfs undergoes strong changes : its sign becomes reversed compared to the weak power regime and it shows a double peak structure , while the imaginary part of the spectrum is now the dominant contribution . ) for three different cases : ( a ) hahn - echo ; ( b ) linear excitation regime with weak intensity of the first pulse , @xmath91 ; ( c ) excitation in the non - linear regime with the first pulse being a @xmath23-pulse . the 2dfs spectra are normalized to unity . left and right panels denote the real and imaginary parts of the @xmath92 spectra , respectively , plotted in the same scaling . other parameters in the calculations are : @xmath93 mev , @xmath94 ps . ]

an ensemble of quantum dot excitons may be used for coherent information manipulation . due to the ensemble inhomogeneity any optical information retrieval occurs in form of a photon echo . we show that the inhomogeneity can lead to a significant deviation from the conventional echo timing sequence . variation of the area of the initial rotation pulse , which generates excitons in a dot sub - ensemble only , reveals this complex picture of photon echo formation . we observe a retarded echo for @xmath0 pulses , while for @xmath1 the echo is advanced in time as evidenced through monitoring the rabi oscillations in the time - resolved photon echo amplitude from ( in , ga)as / gaas self - assembled quantum dot structures and confirmed by detailed calculations . manipulation of electronic states by laser pulses requires precise timing of the pulse sequence . a particular example is ultrafast coherent control of exciton complexes confined in semiconductor nanostructures @xcite which may be used for manipulating quantum states @xcite or even storing quantum information @xcite . for an inhomogeneous ensemble of two - level systems ( tls ) such as quantum dots ( qds ) the information retrieval induces echoes for the recovered signal @xcite . to be of practical use , the echo formation time needs to be determined with high accuracy . the scenario is well established when a weakly inhomogeneous ensemble of tls is resonantly addressed by ultrashort laser pulses whose spectrum covers the distribution of optical transitions in the ensemble . in this conventional picture of a photon echo ( pe ) , a first excitation pulse creates a macroscopic polarization which subsequently dephases due to inhomogeneity . a second subsequent optical rephasing pulse retrieves the macroscopic polarization @xcite with subsequent emission of a pe pulse delayed by a time exactly equal to the interval between the rephasing and excitation pulse , @xmath2 . typically the temporal profile of the pe pulse has a gaussian shape reflecting the inhomogeneous frequency distribution of the excited ensemble . in semiconductors this picture may be complicated by several features : ( 1 ) due to the many - body interactions a description by a distribution of independent tls is as a rule not appropriate , but complex coherent transients are recorded @xcite . however , localization of excitons strongly reduces exciton - exciton interactions @xcite . therefore , qds with particularly strong three - dimensional localization can be often reasonably well considered as tls with long coherence times . indeed , rabi oscillations of exciton complexes were demonstrated in qds using various techniques @xcite . ( 2 ) in addition , fluctuations in qd size , shape and composition lead to a considerable inhomogeneous broadening of the optical transitions in qds . simultaneously excitation with ultrashort pulses having a broader spectrum than the inhomogeneity in many cases is prohibited because of the demand of addressing a specific optical transition . the relatively narrow energy spacing of different electronic excitations limits the spectral width that the laser pulses may have , to avoid excitation of multiple transitions . therefore a careful consideration of the optical frequency detuning with respect to the tls optical resonance is mandatory when considering the pe transient formation , even in the limit of small excitation levels . generally , it is expected that for strongly inhomogeneous tls ensembles the pe temporal profile may undergo significant distortion compared to the standard @xmath3 sequence , showing either retarded or advanced echo pulses @xcite . this is due to the non - negligible inhomogeneity - induced dephasing of oscillators during the optical excitation pulse , so that the finite pulse duration should be taken into account . surprisingly , these variations of the pe transients in tls were only reported in ruby @xcite , where the characteristic excitation and depolarization times are in the range of tens of nanoseconds , i.e. orders of magnitude longer than in semiconductor nanostructures . so far , the pe transients in qds were considered in the conventional @xmath3 picture only . the most interesting from the standpoint of applications is the non - linear regime , when the inhomogeneous system under study may be considered as an ensemble of two - level systems ( tls ) coherently driven by the optical field , so that even rabi oscillations can be observed @xcite . this regime is characterized by the following relation for the saturation factor : t_2 1 , [ satfactor ] where @xmath4 is the rabi frequency expressed via laser pulse amplitude @xmath5 and transition dipole moment @xmath6 , @xmath7 is the decoherence time of an individual oscillator , and @xmath8 is planck constant . during the process of optical excitation , coherent evolution of an individual oscillator from an ensemble with a gaussian distribution of frequencies @xmath9 with standard deviation @xmath10 directly depends on its detuning from the light frequency @xmath11 : @xmath12 , where @xmath13 is the oscillator frequency . hence , the generalized rabi frequency is defined by @xmath14 . while generalized rabi frequency increases with the detuning , the maximum possible population of the tls has the following dependence : , maximum possible population corresponds to the envelope function of population inversion @xmath15 . ] w()=-1 . [ population ] . here , two limiting cases are feasible , as outlined in fig . [ experimental_data ] . when @xmath16 is significantly larger than the inhomogeneity parameter @xmath10 , detuning plays insufficient role , and emission of the pe pulse occurs precisely at @xmath17 by the analogy with the hahn echo @xcite , as shown in fig . [ experimental_data](a ) . on the bloch sphere , in the reference frame rotating at the light frequency @xmath11 , the horizontal drift due to detuning during the excitation is negligible . in the case , when the inhomogeneous ensemble is relatively broad , which is often the case for semiconductor qd ensembles , as compared with atoms and rare - earth crystals , the magnitude of the rabi frequency limits the fraction of the ensemble interacting with the pulse , see fig . [ experimental_data](b ) . . ( b ) theoretical modeling of the data from ( a ) using eq . ( [ pdet ] ) with the following parameters : pump duration @xmath18 ps , inhomogeneity @xmath19 mev , and rephasing pulse area @xmath20 . in the colormaps , dark - blue indicates the zero level , dark - red corresponds to maximum signal . ( c ) pl spectrum of the sample with the energy position of excitation , @xmath21 , indicated by the arrow . ( d ) time - integrated ( ti ) modulus of the pe amplitude measured as function of the first pulse amplitude . ( e ) pe transients for @xmath22 , @xmath23 and @xmath1 , respectively . ] in this letter , we demonstrate that the pe transients are strongly influenced by the inhomogeneity of a qd ensemble . we study the dynamics of the pe from an ensemble of ( in , ga)as / gaas semiconductor qds excited by picosecond laser pulses . by varying the amplitude of the first excitation pulse we find a complex evolution of rabi oscillations in the amplitude of the pe , deviating strongly from the @xmath24 expectation . namely , we observe temporal shifts of the pe pulse relative to the expected pe arrival time . we analyze the experimental results measured on excitons using a transparent analytical model . the pe experiment was carried out on a sample with a single layer of ( in , ga)as qds which is inserted into a gaas @xmath25-microcavity . the qd density is about @xmath26 @xmath27 and the barrier contains a si @xmath10-layer with donor density @xmath28 @xmath27 , separated from the qd - layer by 10 nm . the bragg mirrors consist of alternating gaas and alas layers with thicknesses of 68 nm and 82 nm , respectively . they have 5 and 18 such pairs in the top and bottom mirror , respectively . with a microcavity @xmath29-factor of @xmath30 , the photon lifetime is much shorter than the laser pulse duration of several picoseconds . therefore , the main influence of the microcavity is to enhance the light - matter interaction for those qds with optical frequency in resonance with the cavity mode . further , the broad exciton photoluminescence ( pl ) spectrum from the qds with a width of 30 mev is convoluted with the relatively narrow photon cavity mode to result in a relatively narrow emission band with full - width of 6.5 mev . the energy of the cavity mode depends on the sample spot due to the wedged cavity design . a pl spectrum measured at the studied sample spot discussed subsequently is shown in fig . [ experimental_data](c ) . to study the pe dynamics , a degenerate transient four - wave - mixing ( fwm ) experiment was performed in reflection geometry . the sample was placed into a helium bath cryostat and cooled down to a temperature of @xmath31 k. we used a tunable mode - locked ti : sa laser as source of the optical pulses with duration of about 2.5 ps and repetition rate of about 76 mhz . we implemented an interferometric heterodyne detection using a reference beam to detect the absolute value of the fwm amplitude with temporal resolution . the excitation pulses were linearly cross - polarized resulting a linearly polarized pe signal.4-density matrix formalism in order to account for the linear polarizations as shown in ref . @xcite . it was checked , however , that the effect of the pe shifts demonstrated here is valid for any polarization configuration . ] a detailed description of the experimental technique can be found elsewhere @xcite . in the experiment , the temporal profiles of the pe were measured as a function of the laser pulse amplitude . figure [ experimental_data ] summarizes the experimental data obtained when the amplitude of the first excitation pulse is varied . this pulse amplitude is proportional to @xmath32 , where @xmath33 is the time - integrated intensity of the laser pulses . the delay between the centers of rephasing and excitation pulses is set to 66.7 ps . clearly , footprints of rabi oscillations are observed in fig . [ experimental_data](a ) . most strikingly , sizable temporal shifts of the pe maxima for @xmath0 and @xmath1-excitation pulses ( around 0.8 mw@xmath34 and 1.8 mw@xmath34 , respectively ) as well as a splitting of the pe profile around @xmath23-pulse amplitude ( around 1.3 mw@xmath34 ) become evident in fig . [ experimental_data](e ) , where the corresponding pe transients are plotted . the time - integrated pe signal also manifests rabi oscillations , as seen from fig . [ experimental_data](d ) , but the oscillations are much less pronounced than in the time - resolved data . note , that variation of the second pulse amplitude does not lead to any additional modification of the pe temporal profile . in order to describe the pe from a qd ensemble we calculate the temporal evolution of a set of 2@xmath352 density matrices interacting with two sequent laser pulses and analyze the resulting macroscopic polarization of the medium , @xmath36 , given by the mean value of the dipole moment operator @xmath37 : p = tr ( ) . here , @xmath38 is the density matrix of the tls and @xmath39 is the trace of the matrix . the temporal evolution of the density matrix is described by the lindblad equation : @xmath40+\gamma$ ] , where @xmath41 is the hamiltonian of the system and @xmath42 describes relaxation processes phenomenologically . we consider the case , when the individual oscillator coherence time @xmath43 , which is justified by @xmath7 being ultimately limited by the exciton lifetime of about 0.5 ns . thus , the only consequence of relaxation in the system is the pe exponential decay @xmath44 . therefore , we will neglect relaxation considering @xmath45 , for simplicity . in our model , the hamiltonian consists of two parts : @xmath46 , where @xmath47 describes the unperturbed system and @xmath48 gives the interaction with light . we assume rectangular shaped pulses , each with with duration @xmath49 . during the optical excitation , we calculate the ensemble dephasing due to the detuning of every individual oscillator with frequency @xmath13 from the light frequency @xmath11 : @xmath12 . in the rotating - wave approximation , this defines the optical nutation of the tls on the bloch sphere with a generalized rabi frequency @xmath14 , where @xmath50 is proportional to the optical field amplitude @xmath5 . accordingly , the analysis of the coherent optical response of the system includes the following steps : first , we calculate the interaction of the unperturbed system with the first excitation pulse ( @xmath51 ) acting during time @xmath49 , then the system evolves freely in absence of excitation ( @xmath52 ) during the time interval @xmath2 , followed by the excitation with the second rephasing pulse ( @xmath53 ) during time @xmath49 . finally , we analyze the macroscopic polarization of the qds that is available for pe pulse formation by integrating the individual responses over the inhomogeneous ensemble of tls , defined by a gaussian distribution with standard deviation @xmath10 . within these approximations , it is possible to perform the analysis analytically and calculate the following expression for the modulus of the detected excitation - dependent part of the pe amplitude ( see appendix a containing details of the theoretical approach . ) : @xmath54 d\delta\bigg| . \label{pdet}\end{aligned}\ ] ] here @xmath55 , and @xmath56 are the generalized rabi frequencies of the first and the second pulse , respectively . in this notation , delay between the exciting pulse centers used in experiment is @xmath57 and expected pe arrival time according to the standard treatment is @xmath58 . this equation is similar to the one obtained for spin echoes measured in highly inhomogeneous fields @xcite . it can be easily seen , that variation of the second , rephasing pulse amplitude and , hence , @xmath59 does not affect the symmetry of the pe profile . therefore , we will consider only the effect coming from variation of the first , excitation pulse amplitude . using eq . ( [ pdet ] ) for two different ensemble with different inhomogeneity @xmath10 : ( a ) @xmath60 ; and ( b ) @xmath61 . the time scale is normalized by the pulse duration . dark - blue corresponds to zero signal level , dark - red gives the maximum value . ] figure [ simulations ] shows results of theoretical calculations performed using eq . ( [ pdet ] ) for two ensembles with different widths of the inhomogeneity : @xmath60 and 1.2 . for an ensemble broadening much narrower than the pulse spectrum , @xmath60 , clean rabi oscillations are seen in the pe temporal profile as function of the excitation pulse area @xmath62 , shown in fig . [ simulations](a ) . in particular the photon echo arrives as expected at twice the separation between rephasing and excitation pulse . this case is equivalent to an ideal hahn echo , where the echo signal is generated at @xmath63 . when , however , the inhomogeneous ensemble width becomes comparable with the pulse spectral width ( @xmath61 ) , strong modifications of the temporal pe profile appear , as can be seen in fig . [ simulations](b ) . the key feature of these modifications is the effective temporal shift of the pe amplitude that is particularly prominent for the first two maxima of the rabi oscillations when increasing the excitation power : for a @xmath0-pulse the pe maximum is retarded relative to the expected pe arrival time , while for a @xmath1-pulse the pe is advanced . these shifts do not depend on the pulses delay time @xmath2 in the limit of negligible damping and decrease with further increasing @xmath64 . -pulse : case of hahn echo . ( b ) @xmath0-pulse : retarded echo . ( c ) @xmath1-pulse : advanced echo . the colored lines on the bloch spheres ( left panels ) denote different trajectories of the bloch vectors of individual oscillators with different detuning from the laser frequency in directions indicated by the arrows . the right panels show the temporal evolution of the modulus of the macroscopic polarization , @xmath65 , after excitation pulse action . the dashed lines denote extrapolation of @xmath65 to @xmath66 . ] the temporal shifts of the pe can be qualitatively explained using the bloch sphere representation , as outlined in fig . [ drift_explanation ] . in fig . [ drift_explanation](a ) , the ideal case of a hahn echo is given as a reference , where excitation with a negligibly short excitation @xmath0-pulse results in an unshifted echo signal . when the excitation pulse has a finite duration , as shown in fig . [ drift_explanation](b ) , oscillators experience dephasing during pulse action , so that the excitation distributes the oscillators along the equator of the bloch sphere followed by their precession in the equatorial plane . this precession extrapolated to negative times results in focusing all the bloch vectors on the same meridian , which corresponds to a situation where the maximum macroscopic polarization is shifted to @xmath66 . in case of excitation by a @xmath1-pulse as shown in fig . [ drift_explanation](c ) , after pulse action all oscillators proceed along the equator towards each other , which leads to a shift of the macroscopic polarization maximum to @xmath67 . since the rephasing pulse , which is not necessarily a @xmath23-pulse , acts essentially as a refocusing pulse , which in effect reverses the temporally coherent evolution of the ensemble oscillators , the dynamics of the macroscopic dipole moment around the expected echo arrival time , @xmath68 , is similar to a mirrored copy of its dynamics around the time @xmath69 , as shown by the right panels of fig . [ drift_explanation ] . thus , the pe pulse is retarded for the a @xmath0-excitation pulse and advanced for a @xmath1-pulse , when the ensemble dephasing during pulse action is sufficiently strong . this can be achieved either by high inhomogeneity in the excited ensemble and/or long pulse duration . the analysis of the experimental data in fig . [ experimental_data](a ) was performed using the theoretical modeling of the pe effect at varying excitation pulse amplitudes after eq . ( [ pdet ] ) . the adjustable parameters are @xmath10 and @xmath49 . the theoretical fit depicted in fig . [ experimental_data](b ) gives a pulse duration @xmath70 ps and an inhomogeneous ensemble full - width at half - maximum @xmath19 mev . this broadening is much smaller than the pl linewidth of the qd structure ( 6.5 mev ) indicating that a much narrower sub - ensemble contributes to the pe compared to the ensemble contributing to the pl emission . the origin of this discrepancy will be subject of further studies . a possible reason might be the interaction with the microcavity . the evident rabi oscillations pattern in the pe sequence tells that qd structures under resonant excitation can be well described by tls . in conclusion , the importance of the oscillator detuning from the optical frequency in forming the macroscopic coherent response in semiconductor qds was addressed in literature already before @xcite . however , no consequence of the timing of the associated pe had been reported . the essential consequence of our study is that even significantly inhomogeneous semiconductor systems still demonstrate a comprehensible coherent behavior , but great care needs to be exercised to consider the consequences of the inhomogeneity in detail . when doing so , such systems are very well suited candidates for the coherent manipulations in coherent optoelectronics . in particular , the observed temporal shifts of the pe amplitude need to be taken into account when a precise timing of the optical signals matters . our findings have strong impact on interpretation of two - dimensional fourier transform images , which are currently widely used because of their intuitive visualization of underlying physics @xcite . the complex - valued envelope of the pe - transients from strongly inhomogeneous systems results in a changeover of the corresponding 2d image from a resonance profile in case of a hahn echo to a dispersive profile ( see appendix b ) .

SECTION 1. SHORT TITLE; TABLE OF CONTENTS. (a) Short Title.--This Act may be cited as the ``National Parks Capital Improvements Act of 1999''. (b) Table of Contents.--The table of contents of this Act is as follows: Sec. 1. Short title; table of contents. Sec. 2. Definitions. Sec. 3. Fundraising organization. Sec. 4. Memorandum of agreement. Sec. 5. National park surcharge or set-aside. Sec. 6. Use of bond proceeds. Sec. 7. Administration. SEC. 2. DEFINITIONS. In this Act: (1) Fundraising organization.--The term ``fundraising organization'' means an entity authorized to act as a fundraising organization under section 3(a). (2) Memorandum of agreement.--The term ``memorandum of agreement'' means a memorandum of agreement entered into by the Secretary under section 3(a) that contains the terms specified in section 4. (3) National park foundation.--The term ``National Park Foundation'' means the foundation established under the Act entitled ``An Act to establish the National Park Foundation'', approved December 18, 1967 (16 U.S.C. 19e et seq.). (4) National park.--The term ``national park'' means-- (A) the Grand Canyon National Park; and (B) any other national park designated by the Secretary that has an approved general management plan with capital needs in excess of $5,000,000. (5) Secretary.--The term ``Secretary'' means the Secretary of the Interior. SEC. 3. FUNDRAISING ORGANIZATION. (a) In General.--The Secretary may enter into a memorandum of agreement under section 4 with an entity to act as an authorized fundraising organization for the benefit of a national park. (b) Bonds.--The fundraising organization for a national park shall issue taxable bonds in return for the surcharge or set-aside for that national park collected under section 5. (c) Professional Standards.--The fundraising organization shall abide by all relevant professional standards regarding the issuance of securities and shall comply with all applicable Federal and State law. (d) Audit.--The fundraising organization shall be subject to an audit by the Secretary. (e) No Liability for Bonds.-- (1) In general.--The United States shall not be liable for the security of any bonds issued by the fundraising organization. (2) Exception.--If the surcharge or set-aside described in section 5(a) for a national park is not imposed for any reason, or if the surcharge or set-aside is reduced or eliminated, the full faith and credit of the United States is pledged to the payment of-- (A) the bonds issued by a fundraising organization under subsection (b) for that national park; and (B) the interest accruing on the bonds. SEC. 4. MEMORANDUM OF AGREEMENT. The fundraising organization shall enter into a memorandum of agreement that specifies-- (1) the amount of the bond issue; (2) the maturity of the bonds, not to exceed 20 years; (3) the per capita amount required to amortize the bond issue, provide for the reasonable costs of administration, and maintain a sufficient reserve consistent with industry standards; (4) the project or projects at the national park that will be funded with the bond proceeds and the specific responsibilities of the Secretary and the fundraising organization with respect to each project; and (5) procedures for modifications of the agreement with the consent of both parties based on changes in circumstances, including modifications relating to project priorities. SEC. 5. NATIONAL PARK SURCHARGE OR SET-ASIDE. (a) In General.--Notwithstanding any other provision of law, the Secretary may authorize the superintendent of a national park for which a memorandum of agreement is in effect-- (1) to charge and collect a surcharge in an amount not to exceed $2 for each individual otherwise subject to an entrance fee for admission to the national park; or (2) to set aside not more than $2 for each individual charged the entrance fee. (b) Surcharge in Addition to Entrance Fees.--A surcharge under subsection (a) shall be in addition to any entrance fee collected under-- (1) section 4 of the Land and Water Conservation Fund Act of 1965 (16 U.S.C. 460l-6a); (2) the recreational fee demonstration program authorized by section 315 of the Department of the Interior and Related Agencies Appropriations Act, 1996 (as contained in Public Law 104-134; 110 Stat. 1321-156; 1321-200; 16 U.S.C. 460l-6a note); or (3) the national park passport program established under title VI of the National Parks Omnibus Management Act of 1998 (Public Law 105-391; 112 Stat. 3518; 16 U.S.C. 5991 et seq.). (c) Limitation.--The total amount charged or set aside under subsection (a) may not exceed $2 for each individual charged an entrance fee. (d) Use.--A surcharge or set-aside under subsection (a) shall be used by the fundraising organization to-- (1) amortize the bond issue; (2) provide for the reasonable costs of administration; and (3) maintain a sufficient reserve consistent with industry standards, as determined by the bond underwriter. (e) Excess Funds.--Any funds collected in excess of the amount necessary to fund the uses in subsection (d) shall be remitted to the National Park Foundation to be used for the benefit of all units of the National Park System. SEC. 6. USE OF BOND PROCEEDS. (a) Eligible Projects.-- (1) In general.--Subject to paragraph (2), bond proceeds under this Act may be used for a project for the design, construction, operation, maintenance, repair, or replacement of a facility in the national park for which the bond was issued. (2) Project limitations.--A project referred to in paragraph (1) shall be consistent with-- (A) the laws governing the National Park System; (B) any law governing the national park in which the project is to be completed; and (C) the general management plan for the national park. (3) Prohibition on use for administration.--Other than interest as provided in subsection (b), no part of the bond proceeds may be used to defray administrative expenses. (b) Interest on Bond Proceeds.-- (1) Authorized uses.--Any interest earned on bond proceeds may be used by the fundraising organization to-- (A) meet reserve requirements; and (B) defray reasonable administrative expenses incurred in connection with the management and sale of the bonds. (2) Excess interest.--All interest on bond proceeds not used for purposes of paragraph (1) shall be remitted to the National Park Foundation for the benefit of all units of the National Park System. SEC. 7. ADMINISTRATION. The Secretary, in consultation with the Secretary of Treasury, shall promulgate regulations to carry out this Act.

Exempts the United States from liability for such bonds unless the surcharge is not imposed for any reason or if it is reduced or eliminated in which case the full faith and credit of the United States is pledged to bond payment. Authorizes the Secretary to: (1) permit the Superintendent of the park to charge and collect, in addition to the entrance fee, a surcharge of not to exceed $2; or (2) set aside not more than $2 for each entrance fee. Requires: (1) the surcharge or set-aside to be used by the organization to amortize the bond issue, to provide for the reasonable costs of administration, and to maintain a sufficient reserve consistent with industry standards; and (2) any excess funds to be remitted to the National Park Foundation (NPF) to be used for the benefit of all National Park System (NPS) units. Allows bond proceeds to be used for a park facility project that is consistent with: (1) the laws governing the NPS and the park; and (2) the general management plan for the park. Requires interest earned on bond proceeds to be: (1) used by the organization to meet reserve requirements and defray reasonable administrative expenses; and (2) remitted to the NPF for the benefit of all NPS units, to the extent funds are available in excess of the amount required for projects.

membranoproliferative glomerulonephritis ( mpgn ) refers to an immune complex glomerulonephritis characterized by diffuse mesangial proliferation and interposition of mesangial cells into glomerular capillary walls , with double - contoured appearance of glomerular basement membranes . mpgn is not a diagnostic label for one disease , but rather a description of a glomerular reaction to a variety of causes . periodic fever syndromes ( pfs ) are defined as diseases with recurrent episodes of systemic inflammation with spiking fever and spontaneous resolution . they are now classified as autoinflammatory disorders involving dysregulations of innate immunity . besides hereditary periodic fevers , the definition of pfs has been expanded to include other nongenetic disorders with similar clinical patterns including those of adult onset . we describe a case with adult - onset periodic fever and mpgn , which was resistant to conventional steroid therapy . the effect of rituximab on this case was impressive : although the nephrotic syndrome was remarkably ameliorated by rituximab treatment , the periodic fever was almost unchanged . a 36-year - old japanese woman was referred to a local hospital in august 2003 because of frequent asthmatic attacks , skin rash and periodic high - grade fever . her medical history was childhood asthma . despite repeated bacterial cultures , endoscopies , bone marrow examination and imaging studies including gallium scintigraphy and positron emission tomography , the cause of her fever could not be identified and antibiotics including isoniazid were ineffective . her periodic fever did not improve after her asthma had ameliorated by combination therapy of weekly intravenous methylprednisolone , oral cyclosporine and intramuscular gold sodium thiomalate . no recurrent fever was noted in her family . in november 2008 , she presented with facial edema and gain of body weight ( 52 to 60 kg ) , nephrotic - range proteinuria and hematuria , impaired renal function , hypocomplementemia and positivity of anti - proteinase 3 anti - neutrophil cytoplasmic autoantibody ( pr3-anca , 46.0 u / ml ; normal value < 10 u / ml ) . the patient was pale , febrile ( 38.7c ) and hypertensive ( 176/100 mm hg ) . examinations for skin eruption , ulcer in the oral cavity , splenomegaly and lymphadenopathy were negative . laboratory examinations , listed in table 1 , revealed a white blood cell count of 4,900/l ( with 3,800 neutrophils/l and 100 eosinophils/l ) , a hemoglobin level of 6.4 g / dl , and a platelet count of 20.0 10/l . biochemical investigations revealed a serum creatinine level of 1.71 mg / dl ( 151 mol / l ) , a bun level of 26 mg / dl ( 9.28 mmol / l ) , a serum total protein level of 5.6 g / dl and a serum albumin level of 2.8 g / dl . lowered serum iron ( 5 g / dl ) and transferrin saturation ( 2.3% ) were also observed . urinalysis showed proteinuria ( 5.7 g / day ; 6.1 g / g creatinine ) with dysmorphic hematuria ( > 30/hpf ) . anti - nuclear antibody titer was within normal range , and all of the following autoantibodies were negative : anti - ds dna , anti - sm , anti - ss - a , anti - ss - b , anti - cardiolipin ( igm and igg class ) and anti - gbm antibodies . 50% hemolytic unit of complement was markedly decreased ( < 11.0 u / ml ; normal range , 24.739.5 u / ml ) , as well as c3 ( 19 mg / dl ; normal range , 86160 mg / dl ) and c4 ( 10 mg / dl ; normal range , 1745 mg / dl ) . rheumatoid factor ( 1160 ; normal value , < 140 ) and immune complex ( c1q binding assay , 29.5 g / ml ; normal value , < 2.9 g / ml ) were detected . although igg - type cryoglobulinemia was detected , it was less than 1% in cryocrit . viral serology ( hepatitis b , hepatitis c and human immunodeficiency virus ) was negative . serum levels of igg , igg4 , iga , igd and ige were within normal range but igm was increased ( 414 mg / dl ; normal range , 46260 mg / dl ) . serum pr3-anca level was elevated ( 44.1 u / ml ; normal value , < 3.5 u / ml ) but mpo - anca level was within normal range . the patient did not fulfill american college of rheumatology criteria for systemic lupus erythematosus , granulomatosis with polyangiitis ( wegener 's ) , and churg - strauss syndrome . diffuse mesangial and endocapillary proliferative lesions , lobulation of the glomerular tuft and double contour of glomerular basement membrane were observed ( fig . 1a and b ) , with cellular or fibrocellular crescents in over 50% of glomeruli ( fig . in contrast , marginal segmental staining of igg , iga and igm ( not shown ) was observed . these findings were consistent with histopathological characteristics of mpgn type i rather than those of lupus nephritis or secondary mpgn by cryoglobulinemia . serum cryoglobulin turned negative in february 2010 , irrespective of the state of nephrotic syndrome . her fever was periodic ( fever spike of > 39c every 10 days to 2 weeks ) , associated with arthralgia and urticaria - like skin rash . her fever synchronized with elevation of c - reactive protein ( dashed line , fig . 2e ) and neutrophilia ( not shown ) . peripheral blood level of proinflammatory cytokines was elevated : tnf- , 21.2 pg / ml ( reference range , 0.62.8 pg / ml ) ; il-1 , 15 pg / ml ( reference value , < 10 pg / ml ) ; and il-6 , 97.6 pg / ml ( reference value , < 0.4 pg / ml ) . however , she did not have any disease - specific features such as prolonged fever pattern , cold - induced fever , deafness , deforming arthropathy , elevated igd , or monoclonal gammopathy . two diseases , familial mediterranean fever ( fmf ) and tnf receptor - associated periodic syndrome ( traps ) , are described as possibly being of adult onset among hereditary pfs . as for fmf , no mutation in exons 1 , 2 , 3 and 10 of the mefv gene was detected ( dr . the patient had a rare genotype ( c.625 + 10g / g ) in intron 6 of the tnf receptor gene tnfrsf1a , but no mutation in exons 2 , 3 , 4 , 6 and 7 ( dr . her disease was diagnosed as mpgn type i associated with unclassified adult - onset pfs . she was treated with 3 doses of intravenous methylprednisolone ( 500 mg / day ) followed by oral methylprednisolone ( 40 mg / day ) ( fig . although steroid therapy partially improved several parameters , nephrotic syndrome and renal function worsened as steroids were tapered ( fig . for the use of rituximab the patient 's written informed consent and approval of the bioethics committee of jichi medical university were obtained . rituximab ( 375 mg / m ) was given once a week for 4 consecutive weeks . proteinuria , serum albumin , renal function and hypocomplementemia rapidly ameliorated to baseline ( fig . proteinuria decreased to < 1 g / day and complement levels were within normal range , but her fever was unaltered until 1 year after administration of rituximab . we reported a case of mpgn type i with periodic fever and systemic inflammatory symptoms ( shivers , joint pain , and skin rash ) common in pfs . to date , over 10 pfs have been reported . they include fmf , traps , schnitzler 's syndrome , mevalonate kinase deficiency , the cryopyrin - associated periodic syndromes , deficiency of the interleukin ( il)-1-receptor antagonist , pyogenic arthritis , pyoderma gangrenosum and acne syndrome , periodic fever , aphthous stomatitis , pharyngitis and cervical adenitis syndrome and blau syndrome . three of these diseases can be of adult onset . because the characteristics of schnitzler 's syndrome ( monoclonal igm gammopathy and chronic urticarial rash ) were not found , the candidate diagnoses were fmf and traps . however , her disease may still be diagnosed as one of these syndromes , since incomplete fmf cases and traps - like cases without tnfrsf1a mutation have been reported [ 3 , 4 ] . because new genetic syndromes of periodic fever are still discovered at a rate of about 1 every 2 years , a new disease is another possible diagnosis . mpgn encompasses both idiopathic and secondary forms associated with infections , cryoglobulinemia , autoimmune diseases , neoplasms , and thrombotic microangiopathies . to review the literature , pubmed and web of science databases were searched combining the terms mpgn and periodic fever . to date , 2 cases of mpgn with pfs ( fmf ) were reported . one important aspect in the pathogenesis of mpgn is abnormalities in humoral immunity , especially those against the complement system . they are represented by the production of immune complexes and autoantibodies against proteins in the complement system such as c3 convertase or c1q . unfortunately , c3 nephritic factor was not examined , but increased serum immune complex measured by solid phase c1q binding assay ( table 2 ) and predominant deposition of c1q in glomeruli ( fig . we hypothesize that there is an etiologic relationship between periodic fever ( autoinflammation ) and mpgn in this case . during inflammation , the combination of the inflammatory mediators released from activated antigen - presenting cells and the increased expression of co - stimulatory molecules can have effects on priming lymphocytes . this can be the basis for a persistent hyperproduction of antibodies and the formation of immune complexes preferentially localizing to the subendothelial space of glomeruli . autoreactive lymphocytes also can be activated in these circumstances , particularly if tissue destruction by the inflammation leads to an increase in the availability of the self - antigen . shaw et al . described that the role of inflammasome in some autoimmune diseases is probable because inflammasome products such as il-1 play a role in shaping adaptive immunity through activation of t cells and b cells . this may result in the production of ( auto)antibodies possibly against complement factors or proteinases . regarding mpgn as the dysregulation of humoral immunity secondary to autoinflammation , it makes sense that rituximab created complete remission of mpgn but scarcely had an effect on periodic fever . a similar clinical course was reported in a case of acquired periodic fever , in which depletion of b cells by rituximab resulted in a dramatic reduction of immunoglobulin but did not have a beneficial effect on systemic inflammatory symptoms . pr3-anca is closely associated with systemic vasculitis , especially granulomatosis with polyangiitis ( wegener 's ) . the pathogenic roles and diagnostic values of anca are established . however , in several reports anca is also related to other inflammatory diseases , drug administration and infection . pr3-anca in this case did not correlate with renal function or urinary findings ( fig . this suggests that in our case the production of anca reflects neutrophil - activating conditions due to inflammation , not a state specific to vasculitis . after administration of rituximab , the level of pr3-anca slightly decreased from 4.7 u / ml to 3.7 u / ml . although the primary indication for rituximab is b - cell neoplasm , encouraging results have been observed in autoimmune diseases such as lupus nephritis , systemic vasculitis , and glomerular diseases . rituximab therapy has been applied for mpgns related to hcv , cryoglobulinemia , post transplantation , and b - cell tumors . clinical studies of rituximab in glomerulonephritis have been performed for lupus nephritis , vasculitis and membranous nephropathy , but rituximab is regarded as a future therapeutic strategy for mpgn . our case suggests the future use of rituximab as induction therapy in mpgn refractory to conventional therapies . in conclusion , we reported the case of an adult with periodic fever complicated by nephrotic syndrome 5 years after the onset of fever . the renal disease was diagnosed as mpgn type i. rituximab treatment led to complete remission of nephrotic syndrome but had virtually no effect on periodic fever . this unique pattern of effect implies that rituximab only improved immune dysregulation ( mpgn ) but did not improve its etiological background ( pfs or autoinflammation ) .

we report the case of a 36-year - old japanese woman with nephrotic syndrome due to membranoproliferative glomerulonephritis ( mpgn ) type i diagnosed after a 5-year history of periodic fever syndrome ( pfs ) . hypocomplementemia and elevation of anti - proteinase 3 anti - neutrophil cytoplasmic autoantibody ( pr3-anca ) were observed . hiv , and hepatitis b and c serology were negative . nephrotic syndrome and periodic fever did not respond to oral steroid and intravenous steroid pulse therapies combined with cyclosporine , dipyridamole , warfarin and losartan . we tried immunotherapy using rituximab , a human - mouse chimeric monoclonal antibody directed against the cd20 antigen on mature b cells . this therapeutic approach led to improvement of renal function and remission of nephrotic syndrome and hypocomplementemia . however , it did not have a beneficial effect on periodic fever . suspecting adult - onset hereditary pfs , we analyzed her genetic alteration of mefv and tnfrsf1a genes . a rare genotype in intron 6 of tnfrsf1a was revealed . the etiological relationship between periodic fever and mpgn is discussed . rituximab is a hopeful choice of induction therapy for refractory mpgn .

SECTION 1. SHORT TITLE; FINDINGS. (a) Short Title.--This Act may be cited as the ``PAC Elimination Act''. (b) Findings.--Congress finds the following: (1) Congress now faces a crisis of public confidence about its ability to conduct the people's business. (2) Members of Congress, their relatives, lobbyists, insider-controlled nonprofit organizations, and interest groups have been accused of acting surreptitiously and in concert to enrich themselves at the expense of the public. (3) A government of the people, by the people, and for the people cannot be a government where influence is purchasable. (4) Political action committees in particular represent a narrow fraction of the public viewpoint and generally have few ties, if any, to the State or district from which the member of Congress is elected. (5) The primary recipients of PAC contributions are incumbents, particularly the most powerful members of Congress. (6) The public objects to the establishment of a new political class, a privileged group with perks, amenities, and job security unavailable to average Americans. The public also objects to tilting the electoral landscape to the advantage of a few. (7) If Congress fails to respond appropriately to limit the costs of elections and the perks of power, it will become a legislative body in which the small businessman, the farmer, the day laborer, and the stay-at-home parent are only secondarily represented. (8) Campaign finance reform is the unfinished business of a Congress in disrepute. SEC. 2. BAN ON ACTIVITIES OF POLITICAL ACTION COMMITTEES IN FEDERAL ELECTIONS. (a) Ban on PACs.-- (1) In general.--Title III of the Federal Election Campaign Act of 1971 (2 U.S.C. 431 et seq.) is amended by adding at the end the following new section: ``ban on activities of political action committees ``Sec. 325. Notwithstanding any other provision of this Act, no person other than an individual or a political committee may make contributions, solicit or receive contributions, or make expenditures for the purpose of influencing an election for Federal office.''. (2) Revision of Definition of Political Committee.--Section 301(4) of such Act (2 U.S.C. 431(4)) is amended to read as follows: ``(4) The term `political committee' means-- ``(A) the principal campaign committee of a candidate; ``(B) any national, State, or district committee of a political party, including any subordinate committee thereof; ``(C) any local committee of a political party which-- ``(i) receives contributions aggregating in excess of $5,000 during a calendar year, ``(ii) makes payments exempted from the definition of contribution or expenditure under paragraph (8) or (9) aggregating in excess of $5,000 during a calendar year, or ``(iii) makes contributions or expenditures aggregating in excess of $1,000 during a calendar year; and ``(D) any committee jointly established by a principal campaign committee and any committee described in subparagraph (B) or (C) for the purpose of conducting joint fundraising activities.''. (b) Rules Applicable When Ban not in Effect.--For purposes of the Federal Election Campaign Act of 1971, during any period after the effective date of this Act in which the limitation on making contributions under section 325 of that Act (as added by subsection (a)) is not in effect-- (1) the amendments made by subsection (a) shall not be in effect; and (2) the limitation amount under section 315(a)(2)(A) of such Act shall be $1,000. SEC. 3. ADDITIONAL LIMITATIONS ON CONTRIBUTIONS BY POLITICAL ACTION COMMITTEES. (a) Alternative Limitation on Aggregate Amount of Contributions Made by Multicandidate Committee to Any Candidate.-- (1) In general.--Section 315(a)(2)(A) of the Federal Election Campaign Act of 1971 (2 U.S.C. 441a(a)(2)(A)) is amended by striking the semicolon at the end and inserting the following: ``, or an amount equal to 10 percent of the aggregate amount of contributions received by the candidate and the committees from all sources, whichever is lesser;''. (2) Return of excess contributions by candidates.--Section 315(f) of such Act (2 U.S.C. 441a(f)) is amended-- (A) by striking ``(f)'' and inserting ``(f)(1)''; and (B) by adding at the end the following new paragraph: ``(2) A candidate (or the authorized committees of a candidate) who receives a contribution from a multicandidate political committee in excess of the amount allowed under subsection (a)(2)(A) shall return the amount of such excess contribution to the contributor.''. (b) Limitation on Aggregate Amount of Contributions Made by Multicandidate Committee to All Candidates.--Section 315(a) of such Act (2 U.S.C. 441a(a)) is amended by adding at the end the following new paragraph: ``(9) Notwithstanding any other provision of this Act, during each two-year period beginning on January 1 of an odd-numbered year, the total amount of contributions of a nonparty multicandidate political committee to all candidates for Federal office and their authorized political committees shall not exceed $500,000.''. SEC. 4. REQUIRING NOT LESS THAN 80 PERCENT OF CANDIDATE FUNDS TO COME FROM IN-STATE INDIVIDUALS. Section 315 of the Federal Election Campaign Act of 1971 (2 U.S.C. 441a) is amended by adding at the end the following new subsection: ``(k) Percentage of Candidate Contributions Required to Come From in-State Individuals.--With respect to each reporting period for an election, not less than 80 percent of the total of contributions accepted by a candidate shall be from individuals-- ``(1) who are residents of the State involved or the State in which the Congressional district involved is located, in the case of a candidate for the office of Senator or Representative in the Congress; or ``(2) who are residents of the jurisdiction the candidate seeks to represent, in the case of a candidate for the office of Delegate or Resident Commissioner to the Congress.''. SEC. 5. EFFECTIVE DATE. The amendments made by this Act shall apply with respect to elections occurring after December 2006.

PAC Elimination Act - Amends the Federal Election Campaign Act of 1971 to prohibit any person, other than an individual or a candidate's or party's political committee, from making contributions, soliciting or receiving contributions, or making expenditures for the purpose of influencing an election for federal office. Provides for additional limitations on contributions by multicandidate political action committees. Requires at least 80% of candidate funds to come from in-state individuals.

the study was promoted by the tuscan reference centre for tropical diseases ( trctd ) and proposed to include all infectious diseases units ( n = 11 ) of tuscany . the trctd laboratory provides diagnostic support for some tropical diseases such as df to other tuscan health facilities . serological tests for df available at trctd are : ( 1 ) dengue igg capture elisa , panbio diagnostics ( brisbane , australia ) ; ( 2 ) dengue igm capture elisa , panbio diagnostics ; and ( 3 ) platelia dengue ns1 ag assay ( eia ) , bio - rad laboratories ( marnes la coquette , france ) . for this study , serological criteria for lcd cases were defined as presence of anti - denv igm antibodies and/or positivity for ns1 antigen . epidemiological , clinical , and laboratory characteristics of patients with lcd diagnosed in the period 2006 to 2012 were collected retrospectively by reviewing medical records . moreover , the lcd cases observed in the period 2006 to 2010 were then compared with patients classified with ofi . for the second aim , the exclusion criteria concerning both lcd and ofi patients were : ( 1 ) cases without available clinical data ; ( 2 ) positivity for dengue igg only ; ( 3 ) single dengue igg and dengue igm negative result on tests performed during the first 4 days from onset of symptoms ; ( 4 ) patients diagnosed with malaria ; and ( 5 ) patients whose onset of fever was > 15 days after return from travel . malaria was excluded considering that any returned traveler with fever is assumed to have malaria unless proven otherwise ; hence parasitological exams are performed before any other laboratory diagnostic test . the statistical analysis compared categorical variables between the two groups , lcd and ofi , using chi - square and fisher 's exact test when appropriate . odds ratio ( or ) was also evaluated for variables with p < 0.05 ( table1 ) . clinical , demographic , and epidemiological features of patients with laboratory - confirmed dengue ( lcd ) fever and other febrile illness ( ofi ) observed in tuscany ( italy ) in the period 2006 to 2010 or = odds ratio ; ye = yellow fever ; je = japanese encephalitis ; tbe = tick - borne encephalitis . p value has been determined by chi - square and fisher 's exact test when appropriate . ofi ( 42 undiagnosed fever in returning traveler , 5 pneumonia , 4 meningitis , 3 urinary tract infection , 3 bacterial sepsis , 2 epstein barr virus ( ebv ) acute infection , 2 paratyphoid fever , 1 cytomegalovirus ( cmv ) acute infection , 1 rickettsiosis , 1 pulmonary tuberculosis , 1 amebic dysentery , 1 measles , 1 visceral leishmaniasis ) . a total of 61 lcd cases were confirmed in tuscany in the period 2006 to 2012 . stratification of the 61 cases by province revealed that 32 cases were observed in florence , 10 in arezzo , 6 in leghorn , 3 in lucca , 3 in grosseto , 3 in siena , 2 in pistoia , and 2 in massa - carrara . according to the year of diagnosis , 2 cases were observed in 2006 , 5 in 2007 , 8 in 2008 , 8 in 2009 , 15 in 2010 , 12 in 2011 , and 11 in 2012 . a total of 30 lcd cases ( 58.8% ) were acquired in asia , 11 ( 21.5% ) in central america , 7 ( 13.7% ) in south america , 2 ( 3.9% ) in oceania , and 1 ( 1.9% ) in africa . in regard to the date of diagnosis , 32 cases ( 52.4% ) were diagnosed in the period of a. albopictus activity , which is between june 15 and november 30 , according to the italian ministry of health.10 in the comparison between lcd and ofi cases in the period 2006 to 2010 , samples from 193 patients were tested for suspected df at the trctd . among them , 90 were excluded ( 49 ofi and 2 lcd had no available clinical data , 23 had fever onset > 15 days after return , 9 had only igg positivity , 5 were igg and igm negative in the first 4 days after onset of symptoms and follow - up samples were not available , and 2 patients had malaria ) . a total of 36 lcd cases were observed , accounting for 19% of tested subjects . of those , 17 were igg positive / igm positive , 15 igg negative / igm positive , 2 ns1ag positive / igg negative / igm negative , 1 ns1ag positive / igg positive / igm negative , and 1 ns1ag positive / igg positive / igm positive . the comparison of epidemiological , clinical , and laboratory characteristics of lcd versus ofi is reported in table1 . as far as epidemiological features are concerned , males ( p = 0.015 ; or : 3.1 ) , traveling to visit family / friends ( p = 0.046 ; or : 3.8 ) and travel in a continent other than africa ( p < 0.001 ; or : 20.8 ) were more common in lcd patients rather than ofi patients . for clinical features , arthralgia / myalgia ( p = 0.0006 ; or : 4.4 ) , nausea / vomiting ( p = 0.0024 ; or : 3.6 ) , and skin rash ( p < 0.0001 ; or : 15.2 ) was more common in patients with lcd . in terms of laboratory findings , lcd patients most commonly had leukopenia ( p < 0.001 ; or : 9.8 ) and thrombocytopenia ( p < after malaria , df is the second - most common diagnosis made on febrile patients returning from tropical areas and a test for df must always be included in the diagnostic work - up in such subjects.4 physicians who manage febrile , returning travelers must always place priority on the differential diagnosis of conditions that are treatable , that may cause serious sequelae or death , and pose a risk to public health.11 df fulfills all the mentioned priority conditions . severe df has a fatality rate as high as 20% in absence of appropriate medical intervention.12 although a direct antiviral for denv is currently unavailable , supportive therapy for the management of df improves the outcome in the affected patients , if strictly implemented , by reducing the fatality to 1%.12 moreover , avoidance of nonsteroidal anti - inflammatory drugs and invasive procedures is recommended to prevent severe and even fatal hemorrhagic complications.13 from the public health point of view , a subject returning from a df - endemic area represents a risk for the emergence of autochthonous cases in areas where competent vectors are present . all patients included in this study were febrile from < 15 days and were returning from a dengue - endemic area . as reported in other studies conducted in europe , df is more often diagnosed in adult male tourists returning from asia , particularly thailand and india , or central and south america , mainly from brazil.12 in three cases , acute df was diagnosed by ns1 antigen detection , providing supportive evidence that this test is a valid tool for early diagnosis of dengue in travelers returning from endemic areas.14 in our series , three key clinical features ( arthralgia / myalgia , nausea / vomiting , and skin rash ) , two laboratory results ( leukopenia and thrombocytopenia ) , and one epidemiological feature ( travel in a continent other than africa ) significantly distinguished lcd from ofi , as previously reported.15 in addition , about 52% of dengue cases were diagnosed in the period of a. albopictus activity . as a. albopictus is present widely in tuscany , the reported dengue cases led to implementation of the regional surveillance program for arthropod - borne diseases that is based on home isolation and pest control methods around the patient 's house.10,16 this study however has a number of limitations . it was based on retrospectively collected data , included only febrile subjects evaluated at infectious diseases departments , and does not provide information on serotype as reverse - transcriptase polymerase chain reaction ( rt - pcr ) was not performed . moreover , the presence of anti - denv igm antibodies in a single specimen as a criterion to define a confirmed df case , although coupled with clinical and epidemiological information , does not completely rule out the possibility of a false - positive result . in conclusion , awareness of the main epidemiological and clinical features of df may help physicians to recognize df early on and diagnose the same in febrile travelers from df - endemic areas.3,13 an appropriate diagnostic approach is crucial to limit the risk of introduction and transmission of dengue virus in areas where a. albopictus or a. aegypti are present and in their period of activity . a rapid identification of an imported df case would allow for implementation of adequate control measures aimed at preventing local transmission . furthermore , travelers may act as sentinels for providing information regarding the emergence or reemergence of df in a region .

this report focuses on epidemiological and clinical features of dengue fever ( df ) in tuscany ( italy ) between 2006 and 2012 . sixty - one df cases were diagnosed , 32 of which were in the period of aedes albopictus activity . some clinical ( arthralgia / myalgia , nausea / vomiting , and skin rash ) , laboratory ( leukopenia and thrombocytopenia ) , and epidemiological characteristics ( travel in a continent other than africa ) significantly distinguished df cases from other febrile illnesses . our data stress the importance of increasing awareness on dengue in italy among clinicians in order to reach an early diagnosis in returning travelers and to implement appropriate clinical and public health interventions .

historical reports of drainage of chest empyema and ascites go back to the hippocratic era . however , abdominal drainage has always been a subject of controversy , practiced in confusion and subjected to local dogmas . a hundred years have passed during which operative surgery and supportive care techniques have progressed astonishingly ; but what about drainage ? is the practice of drainage any less controversial , more rational and less confusing today ? surgeons aim differently when using abdominal drainage , either for prophylaxis or therapy . for therapeutic reasons , drainage is used for established infection , e.g. peri - appendicular abscess or diffuse fecal peritonitis , and to control a source of infection that can not be controlled by other means by creating a controlled external fistula ( i.e. , a leaking duodenal suture line ) . drains are also placed to provide a passage for established intra - abdominal collections such as ascites , blood , bile , chyle , and pancreatic or intestinal juice . these collections might become potentially infected or , in the case of bile and pancreatic juice , toxic for adjacent tissue . because of the potential function of abdominal drains to signal early complications , such as postoperative hemorrhage and leakage of enteric suture lines , prophylactic drainage has gained wide acceptance as a useful method to prevent complications after gastrointestinal ( gi ) surgery . recently , some studies have called into question the benefit of routine drainage , , , . it is now established that prophylactic drainage is not needed after cholecystectomy for chronic calculous cholecystitis , . on the other hand , prophylactic drainage after acute calculous cholecystitis is still controversial , especially for cases with pericholecystic collections , excessive adhesions or empyema . multiple reviews , trials and retrospective studies , in particular randomized clinical trials , have dealt with the issue whether to drain or not to drain such cases . however , the results of these trials are contradictory , deal with non - complicated cases and did not answer the clinical question in acute or complicated conditions , , . this retrospective study was conducted to answer the question whether to drain or not to drain after cholecystectomy for acute calculous cholecystitis . a retrospective review of all patients who underwent cholecystectomy for acute calculous cholecystitis , between april 2010 and april 2012 , in aseer central hospital , abha , saudi arabia was done . aseer central hospital is an internationally accredited hospital in which more than 400 cholecystectomy operations are performed every year representing 23% of the general surgery load of operations . all operations were done by consultants of general surgery with experience in the field of laparoscopic cholecystectomy . the calculation was based on error of 0.05 , power of 0.80 with effect size 0.2 . whether a prophylactic drain was inserted or not during the operation , patients were allocated into two groups : group a ( n = 38 ) for patients with operative drain insertion and group b ( n = 65 ) for patients without drain insertion . we included all patients fulfilling the inclusion criteria to avoid bias of selection . according to the policy of our hospital , closed suction drainage was the type of drain used in all patients of group a. drains were removed after cholecystectomy if less than 50 ml serous / serousangionous fluid was collected during the preceding 24 hours . inclusion criteria were diagnosis of acute calculous cholecystitis confirmed by pathological report and patients with immediate cholecystectomy after their first episode of cholecystitis that was done in the same hospital admission . exclusion criteria included patients who need therapeutic drainage for biliary or pancreatic leakage , or with nearby organ injury . the protocol of the study was approved by the ethical committee of faculty of medicine , king khalid university ( rec # 2012 - 05 - 06 ) . preoperative data included clinical presentation , temperature , complete blood count , and ultrasonographic findings . operative data included excessive adhesions , bleeding , bile leak , drain insertion or not , and if they were complicated cases ( peri - cholecystic collection , mucocele or empyema ) . postoperative data included hospital stay , amount and nature of drained fluid , time of drain removal , drain site problems ( infection , ascites , fistula , and need for secondary closure ) and postoperative complications ( wound infection , collection and drainage whether radiological or surgical ) . the statistical analysis of data was done using the excel program for figures and spss ( spss , inc . , the description of the data was done in the form of mean sd for quantitative data and frequency and proportion for qualitative data . the primary endpoint was to determine if there was any difference in outcome in terms of postoperative complications ( wound infection , collection necessitating drainage and reoperation ) and hospital stay in cases of cholecystectomy for acute calculous cholecystitis with and without prophylactic drainage . for quantitative data , independent t - test was used to compare between two groups . for qualitative data chi risk adjusted analysis was done using the binary logistic regression for incidence of complications as a dependent variable and linear regression analysis for hospital stay as a dependent variable to determine the risk factors which affected the outcome if present . a retrospective review of all patients who underwent cholecystectomy for acute calculous cholecystitis , between april 2010 and april 2012 , in aseer central hospital , abha , saudi arabia was done . aseer central hospital is an internationally accredited hospital in which more than 400 cholecystectomy operations are performed every year representing 23% of the general surgery load of operations . all operations were done by consultants of general surgery with experience in the field of laparoscopic cholecystectomy . the calculation was based on error of 0.05 , power of 0.80 with effect size 0.2 . whether a prophylactic drain was inserted or not during the operation , patients were allocated into two groups : group a ( n = 38 ) for patients with operative drain insertion and group b ( n = 65 ) for patients without drain insertion . we included all patients fulfilling the inclusion criteria to avoid bias of selection . according to the policy of our hospital , closed suction drainage was the type of drain used in all patients of group a. drains were removed after cholecystectomy if less than 50 ml serous / serousangionous fluid was collected during the preceding 24 hours . inclusion criteria were diagnosis of acute calculous cholecystitis confirmed by pathological report and patients with immediate cholecystectomy after their first episode of cholecystitis that was done in the same hospital admission . exclusion criteria included patients who need therapeutic drainage for biliary or pancreatic leakage , or with nearby organ injury . the protocol of the study was approved by the ethical committee of faculty of medicine , king khalid university ( rec # 2012 - 05 - 06 ) . preoperative data included clinical presentation , temperature , complete blood count , and ultrasonographic findings . operative data included excessive adhesions , bleeding , bile leak , drain insertion or not , and if they were complicated cases ( peri - cholecystic collection , mucocele or empyema ) . postoperative data included hospital stay , amount and nature of drained fluid , time of drain removal , drain site problems ( infection , ascites , fistula , and need for secondary closure ) and postoperative complications ( wound infection , collection and drainage whether radiological or surgical ) . the statistical analysis of data was done using the excel program for figures and spss ( spss , inc . , the description of the data was done in the form of mean sd for quantitative data and frequency and proportion for qualitative data . the primary endpoint was to determine if there was any difference in outcome in terms of postoperative complications ( wound infection , collection necessitating drainage and reoperation ) and hospital stay in cases of cholecystectomy for acute calculous cholecystitis with and without prophylactic drainage . for quantitative data , independent t - test was used to compare between two groups . for qualitative data chi risk adjusted analysis was done using the binary logistic regression for incidence of complications as a dependent variable and linear regression analysis for hospital stay as a dependent variable to determine the risk factors which affected the outcome if present . they were allocated into two groups ; group a ( n = 38 ) for patients with operative drain insertion and group b ( n = 65 ) for patients without drain insertion . the number of patients preoperatively diagnosed as acute non - complicated cholecystitis was significantly ( p 0.001 ) higher in group b ( 80% in group b vs. 36.8% in group a ) . there were more patients who were diagnosed with mucocele or empyema of the gallbladder in the undrained group , but without statistical significance . group a : patients with operative drain insertion ; group b , patients without drain insertion . in regards to the operative data , operative time was found to be statistically longer in the drained group . all patients who were converted from laparoscopic to open cholecystectomy were in the drained group . patients in the drained group had a mean volume of drained fluid of 49.84 34.30 ml . the nature of the drained fluid was serous or serousangious in all cases . there was no significant difference between the two groups in incidence of postoperative abdominal collections necessitating drainage or wound complications . operative and postoperative data of the patients in both groups are shown in table 2 . univariate analysis revealed that patients in the non - drained group had significant shorter hospital stay compared to patients in the drained group ( 4.48 2.18 days in group a vs. 2.50 2.20 days in group b ) . however , multivariate analysis ( linear regression analysis of hospital stay as a dependent factor ) revealed that preoperative complications , which were significantly more in the drain group ( group a ) , were a significant factor ( p < 0.001 ) affecting hospital stay . binary logistic regression analysis of incidence of complications as a dependent factor revealed no significant effect of different associated risk factors affecting the net results . b : slope of the regression line ; wald : the weight in regression equation . prophylactic abdominal drains have been routinely used in various abdominal surgeries without clear scientific evidence . many surgeons still continue drainage for reasons based on traditional teaching and not on reliable facts and figures . the main motive behind this practice was the fear of missing complications such as postoperative bleeding and anastomotic leakage . regarding cholecystectomy , the major reason for drainage is the fear of bile leakage that may lead to bile peritonitis ; this is usually due to an aberrant bile duct and not slippage of the cystic duct ligature . nowadays , there is consensus that there is no indication to insert a prophylactic drain after elective laparoscopic or open cholecystectomy . however , regarding cholecystectomy for acute cholecystectitis , there is still debate regarding drain insertion , . being a retrospective study , it was not possible to know the surgeon 's justification for drain insertion , but statistical analysis revealed that the main factors which influenced the insertion of a drain were : ( 1 ) complicated acute cholecystitis , particularly with pericholecystic collection ; ( 2 ) prolonged operative time ; ( 3 ) conversion from laparoscopic to open cholecystectomy . the results of our study showed no benefit of inserting a drain in group a , whether for non - complicated or complicated cases , compared to group b ( with no drainage insertion ) . the presence of pericholecystic collection was treated safely in group b with thorough washing and aspiration of the washing fluid without drain insertion . we could not find evidence in the literature to support drain insertion for cases with prolonged operative time or after conversion to open cholecystectomy . the mean drainage volume in our study was 49.84 34.30 ml of serousanguinous fluid . post - cholecystectomy collections in the subhepatic recess are on the whole small , rapidly reabsorbed , and essentially similar in volume whether a drain is used or not . thiebe and eggert reported that the total number of abdominal collections was higher in drained patients ( 44% ) compared with non - drained patients ( 4.1% ) . they also suggested that the drain provokes leakage from superficial biliary ductules damaged by dissection and argued that without drainage it would rapidly wall off . in addition , drains sometimes provide a false sense of security as the drain does not guarantee either prevention or treatment of postoperative collections . the only case in this study that required postoperative ultrasound guided aspiration of subhepatic collection was from group with drain insertion . one justification for inserting a drainage tube after laparoscopic cholecystectomy is to deflate carbon dioxide to reduce postoperative pain , although the use of a drainage tube in these cases was found to intensify postoperative pain rather than relieving it , . many authors reported that surgically placed drains have some risk ; they have been associated with increased rates of intra - abdominal and wound infection , increased abdominal pain , decreased pulmonary function , and prolonged hospital stay , , . in this study , there was no significant difference between the two groups regarding wound complications . postoperative pain was not studied as it was not reported in the files of the patients . in regards to hospital stay , surgeons who inserted prophylactic drains waited at least 24 hours before its removal . in addition , fluid drained from the abdominal cavity was serousanguinous and was normally reabsorbed without problem . in addition , it increases the cost of operation , the utilization of hospital medical resources and prolongs the waiting list of operations . in our study , but multivariate analysis was essential to clarify whether the cause of longer hospital stay was because of the drain or because of the fact that many surgeons prefer to insert prophylactic drains in complicated cases . the multivariate analysis revealed that more difficult cases were included in the drainage group , which was the cause of longer hospital stay . however , this point should be further studied in a prospective clinical study . multivariate analysis with the incidence of postoperative complications as a dependant variable revealed no difference between the drained and non - drained group . this result clarifies the fact that prophylactic drainage added no benefit to the drained group . being a non - randomized , retrospective and a single center study are the main limitations of our study . logically , this potential bias would have been in favor of drain insertion , as drains are usually inserted in cases when complications are expected , but our study included patients with complicated and/or difficult cholecystectomies where no drains were inserted and no postoperative complications were reported . in contrast , the only case that needed postoperative drainage of collection was already in the group who had intraoperative drain insertion . in conclusion , there was no added benefit for prophylactic drain insertion after cholecystectomy for acute calculous cholecystitis in non - complicated or in complicated cases .

abstractmany surgeons practice prophylactic drainage after cholecystectomy without reliable evidence . this study was conducted to answer the question whether to drain or not to drain after cholecystectomy for acute calculous cholecystitis . a retrospective review of all patients who had cholecystectomy for acute cholecystitis in aseer central hospital , abha , saudi arabia , was conducted from april 2010 to april 2012 . data were extracted from hospital case files . preoperative data included clinical presentation , routine investigations and liver function tests . operative data included excessive adhesions , bleeding , bile leak , and drain insertion . complicated cases such as pericholecystic collections , mucocele and empyema were also reported . patients who needed therapeutic drainage were excluded . postoperative data included hospital stay , volume of drained fluid , time of drain removal , and drain site problems . the study included 103 patients allocated into two groups ; group a ( n = 38 ) for patients with operative drain insertion and group b ( n = 65 ) for patients without drain insertion . the number of patients with preoperative diagnosis of acute non - complicated cholecystitis was significantly greater in group b ( 80% ) than group a ( 36.8% ) ( p < 0.001 ) . operative time was significantly longer in group a. all patients who were converted from laparoscopic to open cholecystectomy were in group a. multivariate analysis revealed that hospital stay was significantly ( p < 0.001 ) longer in patients with preoperative complications . there was no added benefit for prophylactic drain insertion after cholecystectomy for acute calculous cholecystitis in non - complicated or in complicated cases .

Lawrence Tynes' wife took to Twitter on Wednesday to publicly refute the Tampa Bay Buccaneers' claim that her husband is "responding well" to treatment for MRSA, a serious staph infection that sidelined the veteran kicker earlier this month. The Buccaneers acknowledged last week that they treated their facility last week to prevent an MRSA outbreak after Tynes and Pro Bowl guard Carl Nicks contracted the infection. Buccaneers coach Greg Schiano said Tuesday that both players "are responding well" to treatment. Amanda Tynes posted a response on her Twitter account and posted a photo of her husband: I hear my husband is responding "well" to treatment. LOL! He's NOT responding at all yet. This is our #bucslife pic.twitter.com/Gy4z4OcAXA — Amanda Tynes (@AmandaTynes9) August 28, 2013 Several hours after her initial tweet, Tynes' wife posted a follow-up message: Thank you so much for all the well wishes. Lawrence finally has the right people in his corner. Right now he needs to rest and get healthy. — Amanda Tynes (@AmandaTynes9) August 28, 2013 Tynes underwent surgery last week to repair his infected toe. The Bucs signed kicker Rian Lindell on the same day Tynes had his surgery, in which the infection was scraped from his toe and his toe bone. Tynes sought a second opinion after what originally was identified as an ingrown toenail failed to heal and became infected. Doctors at the New York Hospital for Special Surgery confirmed a diagnosis of MRSA. Tynes has not participated in training camp. The New England Patriots, who hosted the Buccaneers earlier this month for joint practices and scrimmages, also have treated their facility for MRSA, a league source told ESPN on Wednesday. Information from ESPN's Chris Mortensen and Adam Schefter was used in this report. ||||| The Tampa Bay Buccaneers said Friday that a third player had a MRSA infection, a thorny strain that has been a concern in N.F.L. locker rooms over the past decade. The team did not release the name of the player. The other two players are guard Carl Nicks, whose infection earlier this season recently resurfaced, and kicker Lawrence Tynes, who is seeking treatment away from the team and is on the team’s reserve list with a nonfootball injury. The announcement came two days before the Buccaneers were to host Philadelphia and several years after some Cleveland Browns players who had the infection claimed the team misdiagnosed their problems and failed to clean its facilities properly. The Buccaneers have been working with Dr. Deverick J. Anderson, co-director of the Duke Infection Control Outreach Network, since September to identify the infections and review protocols for preventing them. Anderson said that the first two cases were unrelated and that the third case had not been fully diagnosed. He said he did not know why three Buccaneers had the infection and no players on other teams appeared to have it. Advertisement Continue reading the main story “The reality is we all get exposed to MRSA pretty regularly, but because we have intact skin, we don’t run into any problems with it,” Anderson said. ||||| TAMPA — Bucs rookie cornerback Johnthan Banks was worried about a sore on his body Thursday. As he had been instructed, he brought it to the attention of team doctors. A culture was taken and revealed what everyone likely feared: MRSA, the severe staph infection resistant to most antibiotics that continues to infect members of the Buccaneers. On Friday, less than 24 hours after the team announced guard Carl Nicks had a recurrence of the staph infection in his left foot, general manager Mark Dominik neither confirmed nor denied multiple media reports that Banks was the third Buc to contract MRSA over the past two months. But Banks was the only player absent from practice Friday who previously had not been on the injury report. He is listed as questionable for Sunday's game against the Eagles with an "illness." "This player did a great job of alerting us," Dominik said. But the latest MRSA case called into question if One Buc Place is a safe work environment and had the NFL players' union gathering facts to make sure conditions are safe for Sunday's game at Raymond James Stadium. In an effort to allay fears of players, coaches and employees, the Bucs flew in Dr. Deverick Anderson, co-director of the Duke Infection Control Outreach Network. "We're here to, obviously, report we did have a third case of MRSA within this organization," Dominik said in a joint news conference Friday with Anderson. Two Bucs contracted MRSA in August. Kicker Lawrence Tynes was told after seeking a second opinion on an ingrown toenail from a New York hospital. He is still receiving antibiotics via an intravenous line. Nicks missed all of the preseason and the first two regular-season games. Nicks was told Thursday his infection had recurred. Anderson said in cases such as Nicks', surgery is often a necessity. "The reality is oftentimes when MRSA gets into the bone, then therapy alone is not enough to actually cure it," he said. "So typically in that scenario … that indicates you may require a surgical procedure to definitively remove that infection." Although he has not examined Tynes, Anderson said Tynes and Nicks did not spread the infection to each other. But Anderson said he did not have enough information to determine if Banks' infection is similar to the strain contracted by Tynes and Nicks. MRSA can spread through barely noticeable skin openings or shared equipment or towels that come into contact with skin. Last week, the players union filed a grievance against the Bucs on behalf of Tynes, who was placed on the nonfootball injury list instead of injured reserve. While Tynes is being paid his salary, he is not receiving benefits such as matching 401(k) contributions nor accruing service time toward a pension. The grievance addresses "significant concerns about the manner in which that player and perhaps other players' safety was handled by the team," union executive director DeMaurice Smith said last week. It alleges Tynes was not cultured for MRSA by the team, causing a delay in treatment of more than two weeks. Nicks was placed on a battery of antibiotics immediately. "This underscores the need for a leaguewide, comprehensive and standardized infectious disease protocol," Smith said. "It also calls for improved accountability measures on health and safety issues by the NFL over the clubs." Bucs players said Friday's question-and-answer session with Anderson was helpful. "Of course, something so serious like this, you're scared and concerned," cornerback Leonard Johnson said. "But we had one of the top doctors come in and talk with us. That put a lot of guys' minds at ease, especially mine." Despite having the only three known players diagnosed with MRSA among 32 NFL teams, Anderson said Bucs players were at no more risk than other teams. "Based on my observations, I didn't think there was anything very high risk," Anderson said. "I think that football in and of itself, there's a known risk factor for MRSA and MRSA infection in general. So the fact that a case or even two and now three cases occurred does not necessarily mean in and of itself that this is at any higher risk than any other football location in the country. "I can say I believe that it is a safe environment for players and staff." Asked why the Bucs are the only team with three MRSA cases, Anderson said: "I don't know." Smith said the union is working with the NFL to assess the situation. Most likely, Sunday's game will be played. Anderson said he doesn't believe there is any additional danger to players. "We have been involved in an ongoing review of the MRSA incidents in Tampa Bay initiated by the concerns we had about the manner in which team officials responded to these cases," Smith said in a statement Friday. "We advised the NFL and the Tampa Bay Buccaneers that an outside expert should be brought in to assess the situation and we are pleased with their decision to take that recommendation. We have also been in regular contact with the player representatives from Tampa Bay. We will reach out to the Philadelphia Eagles player representatives today and provide them with our best medical guidance and regular updates from the outside experts." Banks, a second-round pick from Mississippi State, has seen playing time when opponents use three receivers. Nicks, a Pro Bowl guard, could be looking at missing more games or possibly the rest of the season if surgery is required. Tynes likely is out for the season. "They're concerned for each other," Bucs coach Greg Schiano said. "Out of anything, good can come. This team's coming together, and we're going to stick behind our guys that are sick, stick together for each other. "Adversity reveals character, and I think some good character is coming out of this." Times staff writer Greg Auman contributed to this report. ||||| After the MRSA (methicillin-resistant Staphylococcus aureus) results came in, the National Football League Players Association will not advise the Tampa Bay Buccaneers and Philadelphia Eagles against playing their Week 6 game. Adam Schefter of ESPN passed along the initial report, which was originally conveyed to colleague Trey Wingo by the NFLPA: NFLPA tells @wingoz that, depending on what MRSA containment report says, the NFLPA could advise Bucs-Eagles not to play this weekend. — Adam Schefter (@AdamSchefter) October 11, 2013 According to CDC.com, MRSA is "a bacteria that is resistant to many antibiotics. In the community, most MRSA infections are skin infections. In medical facilities, MRSA causes life-threatening bloodstream infections, pneumonia and surgical site infections."

– Game called on account of staph infection? The Buccaneers and Eagles are playing tomorrow as scheduled, but the NFL players' union considered telling members to skip it after a third Tampa player was diagnosed this week with a nasty MRSA infection, reports Bleacher Report. Rookie Johnthan Banks is the unlucky one, with teammates Carl Nicks and Lawrence Tynes diagnosed previously, reports the Tampa Bay Times. MRSA is resistant to most types of antibiotics, and the league, the team, and the NFLPA are trying to figure out why Bucs players are falling victim. “This underscores the need for a leaguewide, comprehensive and standardized infectious disease protocol,” says DeMaurice Smith, executive director of the union. MRSA infections have cropped up before in the NFL over the last decade, notes the New York Times, in part because of the ideal conditions for it: It's a physical game that causes cuts and bruises, which the players then bring into the locker room. Kicker Tynes was diagnosed over the summer, and his case got a dose of publicity when his wife took to Twitter to refute a team statement that he was "responding well" to treatment.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Contractors and Federal Spending Accountability Act of 2008''. SEC. 2. DATABASE FOR CONTRACTING OFFICERS AND SUSPENSION AND DEBARMENT OFFICIALS. (a) In General.--Subject to the authority, direction, and control of the Director of the Office of Management and Budget, the Administrator of General Services shall establish and maintain a database of information regarding integrity and performance of persons awarded Federal contracts and grants for use by Federal officials having authority over contracts and grants. (b) Persons Covered.--The database shall cover any person awarded a Federal contract or grant if any information described in subsection (c) exists with respect to such person. (c) Information Included.--With respect to a person awarded a Federal contract or grant, the database shall include information (in the form of a brief description) for at least the most recent 5-year period regarding the following: (1) Each civil or criminal proceeding, or any administrative proceeding, with respect to the person during the period to the extent that such proceeding results in the following dispositions and the payment of a monetary fine, penalty, reimbursement, restitution, damages, or settlement to a government of $5,000 or more, concluded by the Federal Government or any State government against the person: (A) In a criminal proceeding, a conviction. (B) In a civil or administrative proceeding, a finding of liability. (C) In a civil or administrative proceeding, a disposition of the matter by consent or compromise if the proceeding could have led to either of the outcomes specified in subparagraph (A) or (B). (2) Each Federal contract and grant awarded to the person that was terminated in such period due to default. (3) Each Federal suspension and debarment of the person in that period. (4) Each Federal administrative agreement signed with the person in that period if the proceeding concerned could have led to either of the outcomes specified in subparagraph (A) or (B) of paragraph (1). (5) Each final finding by a Federal official in that period that the person has been determined not to be a responsible source under either subparagraph (C) or (D) of section 4(7) of the Office of Federal Procurement Policy Act (41 U.S.C. 403(7)). (d) Requirements Relating to Information in Database.-- (1) Direct input and update.--The Administrator shall design and maintain the database in a manner that allows the appropriate officials of each Federal agency to directly input and update in the database information relating to actions it has taken with regard to contractors or grant recipients. (2) Timeliness and accuracy.--The Administrator shall develop policies to require-- (A) the timely and accurate input of information into the database; (B) notification of any covered person when information relevant to the person is entered into the database; and (C) an opportunity for any covered person to append comments to information about such person in the database. (e) Availability.-- (1) Availability to all federal agencies.--The Administrator shall make the database available to all Federal agencies. (2) Availability to the public.--The Administrator shall make the database available to the public by posting the database on the General Services Administration website. (3) Limitation.--This subsection does not require the public availability of information that is exempt from public disclosure under section 552(b) of title 5, United States Code. SEC. 3. REVIEW OF DATABASE. (a) Requirement to Review Database.--Prior to the award of a contract or grant, an official responsible for awarding a contract or grant shall review the database established under section 2. (b) Requirement To Document Present Responsibility.--In the case of a prospective awardee of a contract or grant against which a judgment or conviction has been rendered more than once within any 3-year period for the same or similar offences, if each judgment or conviction is a cause for debarment, the official responsible for awarding the contract or grant shall document why the prospective awardee is considered presently responsible. SEC. 4. DISCLOSURE IN APPLICATIONS. (a) Requirement.--Not later than 180 days after the date of the enactment of this Act, Federal regulations shall be amended to require that in applying for any Federal grant or submitting a proposal or bid for any Federal contract a person shall disclose in writing information described in section 2(c). (b) Covered Contracts and Grants.--This section shall apply only to contracts and grants in an amount greater than the simplified acquisition threshold, as defined in section 4(11) of the Office of Federal Procurement Policy Act (41 U.S.C. 401(11)). SEC. 5. ROLE OF INTERAGENCY COMMITTEE. (a) Requirement.--The Interagency Committee on Debarment and Suspension shall-- (1) resolve issues regarding which of several Federal agencies is the lead agency having responsibility to initiate suspension or debarment proceedings; (2) coordinate actions among interested agencies with respect to such action; (3) encourage and assist Federal agencies in entering into cooperative efforts to pool resources and achieve operational efficiencies in the Governmentwide suspension and debarment system; (4) recommend to the Office of Management and Budget changes to Government suspension and debarment system and its rules, if such recommendations are approved by a majority of the Interagency Committee; (5) authorize the Office of Management and Budget to issue guidelines that implement those recommendations; (6) authorize the chair of the Committee to establish subcommittees as appropriate to best enable the Interagency Committee to carry out its functions; and (7) submit to the Congress an annual report on-- (A) the progress and efforts to improve the suspension and debarment system; (B) member agencies' active participation in the committee's work; and (C) a summary of each agency's activities and accomplishments in the Governmentwide debarment system. (b) Definition.--The term ``Interagency Committee on Debarment and Suspension'' means such committee constituted under sections 4 and 5 and of Executive Order 12549. SEC. 6. AUTHORIZATION OF INDEPENDENT AGENCIES. Any agency, commission, or organization of the Federal Government to which Executive Order 12549 does not apply is authorized to participate in the Governmentwide suspension and debarment system and may recognize the suspension or debarment issued by an executive branch agency in its own procurement or assistance activities. SEC. 7. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated to the Administrator of General Services such funds as may be necessary to establish the database described in section 2. SEC. 8. REPORT TO CONGRESS. (a) Report Required.--Not later than 180 days after the date of the enactment of this Act, the Administrator of General Services shall submit to Congress a report. (b) Contents of Report.--The report shall contain the following: (1) A list of all databases that include information about Federal contracting and Federal grants. (2) Recommendations for further legislation or administrative action that the Administrator considers appropriate to create a centralized, comprehensive Federal contracting and Federal grant database.

Contractors and Federal Spending Accountability Act of 2008 - Requires the Administrator of General Services to establish and maintain on a General Services Administration (GSA) website for use by officials of all federal agencies a database of information regarding the integrity and performance of persons awarded federal contracts and grants. Requires the database to include information on such persons for the last five years regarding: (1) any civil, criminal, or administrative proceeding resulting in payment of a monetary fine, penalty, reimbursement, restitution, damages, or settlement of $5,000 or more to the federal or a state government; and (2) each contract and grant terminated due to default; (3) each suspension and debarment; (4) each federal and state administrative agreement signed in a proceeding that could have led to a criminal conviction or a finding of liability; and (5) each federal determination that such a person is not a responsible source under the Office of Federal Procurement Policy Act. Requires disclosure of such information by applicants for grants or contracts exceeding the simplified acquisition threshold. Requires the Administrator to require: (1) notification of any covered person when information relevant to the person is entered into the database; and (2) an opportunity for such person to append comments to such information. Requires agency officials to: (1) review such database prior to awarding a contract or grant; and (2) document why a prospective awardee against whom a judgment or conviction for similar offences has been rendered more than once within any three-year period is considered presently responsible. Sets forth the role of the Interagency Committee on Debarment and Suspension, including to: (1) determine the agency responsible for initiating proceedings; (2) facilitate cooperative efforts among agencies in the suspension and debarment system; and (3) report to Congress on improvements to and each agency's activities in such system. Allows federal agencies, commissions, or organizations not currently participating in the federal suspension and debarment system to participate. Requires the Administrator to report to Congress on all databases that include information about federal contracting and grants and on creating a centralized federal contracting and grant database.

CARACAS May 7 Shortages of motorcycle parts in recession-hit Venezuela have become so acute that bikers are being killed for their vehicles, the leader of a local motorcyclists' association said. Socialist-run Venezuela is reeling from shortages of foods, medicines and machinery due in part to currency controls that crimp imports. That strain appears to have exacerbated theft in the already violence-plagued country where police officers are gunned down for their weapons, trucks ambushed for merchandise and commuters held up for cellphones. "They're killing those of us in the street to steal our bike because there are no bikes or spare parts," Jorge Montaño, a leader of Venezuela's National Socialist Federation of Motorbikers, said on Thursday. "Well-dressed women participate in the scam. They ask for a taxi ride, and when you arrive there is a thief waiting to rob you. Sometimes our companions don't want to hand over the motorcycle and they shoot them in the legs or they kill them." Bikers are prime targets because they zip en masse around the South American country's choked roads every day, added Montaño, who said the federation has millions of members. He had no national statistics on hand, but said some 17 people have been murdered for their motorbikes in his home state of Vargas this year alone. Venezuela's Interior Ministry did not immediately reply to requests for comment. Amid a tumble in oil prices, the cash-strapped OPEC member has prioritized food imports and debt servicing, leaving less hard currency for other purchases. Montaño said he was calling on President Nicolas Maduro to put the federation in charge of importing spare parts from China to prevent a further escalation of crime and alleviate the shortages. Fellow bikers echoed his worries, with one saying he was now heading home early and paying particular attention at red lights where holdups are common. "The situation is worsening," said another biker from the west side of Caracas who was held up at gunpoint for his vehicle. "You live life minute-to-minute." (Reporting by Corina Pons and Alexandra Ulmer, editing by G Crosse) ||||| And a United States Treasury Department investigation made public in March uncovered a money laundering ring that had moved $4.2 billion out of Venezuela though import-related schemes and other means. The investigators determined that at least $50 million had passed through the American financial system. Mr. Maduro, a leftist president who was elected by a narrow margin in 2013, has often come under pressure to attack government corruption. In December 2013, Mr. Maduro appointed the commission to investigate the import ploys, calling them “a fraud against the republic.” “I am going to reveal to the country the truth about what happened there, because it was a vulgarity,” Mr. Maduro said. Jesús Faría, a member of the commission and a governing party lawmaker, said in a television interview last month that in just a sampling of cases, the commission had found that more than 250 companies “had broken the law and that the prosecutor’s office had hundreds of companies to evaluate and investigate.” “Nevertheless, I have not seen that any of these companies have been punished,” he added. There appears to be only one criminal case in which prosecutors have charged a high-level official at the currency control agency with wrongdoing. The official, Francisco Navas, was arrested in 2013 and has yet to stand trial. He is charged with money laundering and conspiracy, accused of taking bribes to sign off on millions of dollars of payments to companies for bogus imports. According to the testimony of an agency vice president, Mr. Navas charged companies the equivalent of about 46 cents for each dollar he approved. His lawyer, Alonso Medina, said that Mr. Navas was a scapegoat, charged so that the authorities had someone to “hold responsible before public opinion.”

– Venezuela is running low on motorcycle parts, which is, in turn, likely only making its coffin shortage worse. Motorcycle riders are being gunned down for their bikes as a recession wreaks havoc on the South American country, reports Reuters. "They're killing those of us in the street to steal our bike because there are no bikes or spare parts," says Jorge Montaño, the leader of the country's National Socialist Federation of Motorbikers, which is said to have millions of members. He explains "well-dressed women" request a motorcycle taxi ride to a destination where a thief is waiting to steal the bike from its owner. "Sometimes our companions don't want to hand over the motorcycle and they shoot them in the legs or they kill them," he says. Montaño notes at least 17 people have been killed for their motorbikes in the state of Vargas so far this year. Some riders now say they don't stay out on their bikes late at night and are extra vigilant when stopped at red lights. "The situation is worsening," says a biker from Caracas, who was previously held up at gunpoint for his motorcycle. "You live life minute-to-minute." Though food imports and debt servicing are now the priority in Venezuela, Montaño hopes to press President Nicolas Maduro to import spare motorcycle parts from China in the hopes of cutting down on violence. The New York Times reports Venezuela is also short on milk, condoms, and shampoo amid a massive import fraud scandal that has seen billions drained from the country.

quantized vortices are topological defects in a superfluid , possessing quantized circulation of the superfluid around them . they play an important role in the transport phenomena in the superfluid such as the critical superflow and quantum turbulence @xcite . furthermore , they are responsible for the superfluid phase transition in two dimensions , where pairing of vortices with opposite circulation occurs below a critical temperature @xcite . in ultracold atom experiments , quantized vortices and related phenomena have been actively studied @xcite . they were first observed in rotating bose - einstein condensates ( becs ) @xcite and many aspects of their dynamic behavior have been investigated , including line defect deformation @xcite , instability of multiply charged vortices @xcite , and vortex dipole dynamics @xcite . recently , thermally activated vortices have been observed in two - dimensional ( 2d ) bose gases @xcite . at the core of a quantized vortex , superfluid density is depleted because of the diverging centrifugal potential . this distinctive feature is typically used for detecting the quantized vortices . in a trapped bec , however , the spatial extent of the vortex core , which is determined by the healing length of the condensate , is generally smaller than the wavelength of imaging light , and so its _ in situ _ optical detection is experimentally challenging . a conventional method to circumvent this difficulty is releasing the trap to let the condensate freely expand , where the vortex core also expands . free expansion of a bec containing a quantized vortex was theoretically studied , showing that the vortex core may expand faster than the condensate during the initial stage of the expansion @xcite , and further faster in the case of an oblate bec @xcite . in this paper , we study expansion dynamics of a quasi-2d , _ i.e. _ highly oblate bec containing quantized vortices . because the condensate expands fast along the tight confinement direction at the beginning of the free expansion , the atomic density and consequently the atom - atom interaction effects rapidly reduce in the expanding condensate . for this sudden quenching of the interactions , the density - depleted vortex core , which is maintained to be small in the trapped condensate by the interactions , will evolve differently from that in three - dimensional hydrodynamic expansion . we observe that the ring - shaped density ripples develop surrounding the vortex core in a freely expanding quasi-2d condensate and find that their time evolution is quantitatively well described by numerical simulations assuming no interactions . finally , we investigate the defocus effect in imaging of the vortex core , which is caused by the free fall of the condensate during the expansion time . we prepare a quasi-2d bose - einstein condensate containing quantized vortices as described in our previous publication @xcite . bose - einstein condensates of @xmath0na atoms in the @xmath1 state are generated in an optically plugged magnetic quadrupole trap @xcite , and transferred into a single optical dipole trap whose trapping frequencies are @xmath2(3.0 , 3.9 , 370 ) hz , where the @xmath3 direction is along the gravity . for a typical atom number of @xmath4 , the chemical potential is @xmath5 hz in the thomas - fermi ( tf ) approximation . this is less than the confining energy @xmath6 , and at low temperatures our sample constitutes a weakly interacting quasi-2d bec . the healing length is @xmath7 m ( @xmath8 is the atomic mass ) , which is the characteristic spatial extent of a density - depleted vortex core in the condensate . in order to induce vortex excitations , we intentionally displace the optical trap from the center of the plugged magnetic trap by about @xmath9 m in the horizontal direction , and carry out a rapid transfer of the condensate to the optical trap . the transfer is made by ramping up the optical trap and simultaneously ramping down the magnetic potential for 500 ms . during this transfer , the optical plug beam is kept on to let the condensate experience an obstacle as it flows into the optical trap . finally , the plug beam is linearly turned off for 400 ms . free expansion is initiated by suddenly turning off the optical trap , and the column density distribution is measured by taking an absorption image along the @xmath3 axis after an expansion time @xmath10 . right after being transferred into the optical trap , the condensate showed very complicated and random density modulations in expansion , indicating that it was strongly perturbed in the transfer process @xcite . we let this non - equilibrium state relax by holding the condensate in the optical trap . after long relaxation times over 15 s , density - depleted vortex cores were observed clearly in the expanding condensate ( fig . [ fig1 ] ) . at this moment , the temperature of the thermal component was about 50 nk and the core visibility in the center region of the condensate was above 70% . we note that such clear vortex cores were not observed when condensates were prepared in thermal equilibrium at this temperature , which is achieved by transferring thermal atoms into the optical trap and applying slow evaporative cooling . the density distributions of the vortex core for various expansion times are obtained by averaging several optical density images of the vortex cores located in the center region of the condensates [ fig . 1(c ) and ( d ) ] . it is observed that a noticeable density hump forms around the core and propagates outward in the course of free expansion . 17 ms and ( b ) 20 ms . the condensates are mechanically perturbed and prepared in nonequilibrium states ( see text for detail ) , and density - depleted vortex cores are observed in the freely expanding condensates . images of the vortex core for ( c ) @xmath1117 ms and ( d ) 20 ms , obtained by averaging several images like ( a ) and ( b ) , respectively.,width=211 ] = 1 ) vortex for various expansion times @xmath10 , where @xmath12 m . ( b ) ring radius @xmath13 versus expansion time @xmath10 for various phase winding numbers @xmath14 . the solid lines are for @xmath12 m and the shaded areas correspond to @xmath15 m . the dotted line denotes the critical radius to have a filled core in the defocused image for @xmath16 in fig . ( c , d ) radial profiles ( black diamond ) obtained by azimuthally averaging the images in fig . 1(c ) and ( d ) , respectively . the red lines are the numerical results taking into account the finite spatial resolution of the imaging system . , width=302 ] to understand the observed evolution of the vortex core , we perform numerical simulation of free expansion of a bec containing a quantized vortex at its center . here , in particular , we assume that the atom - atom interactions immediately vanish at the start of the expansion . in this non - interacting case , the axial motion in the @xmath3 direction is separable from the transverse motion in the @xmath17-@xmath18 plane , so we consider only the transverse expansion of the condensate . the initial condensate wave function is set as @xmath19},\ ] ] where the first part describes the vortex core structure with phase winding number @xmath14 @xcite and the second part corresponds to the tf density profile in a harmonic potential with central density @xmath20 and radius @xmath21 . because of the cylindrical symmetry of the condensate wave function , its non - interacting evolution can be expressed as @xmath22 where @xmath23 is the bessel function of the first kind of order @xmath14 , and @xmath24 is the @xmath25th zero of @xmath23 . the coefficients @xmath26 are determined by @xmath27 ^ 2}\int_{0}^{r}\psi_0(r ) j_l{(\beta_{nl}\frac{r}{r})}rdr$ ] . in our calculation , we set @xmath28 m and @xmath29 . figure [ fig2](a ) shows the results of the numerical calculation for the density distribution @xmath30 with @xmath12 m and @xmath31 . a multiple - ring structure develops and radially expands as observed in the experiment . furthermore , we find that the radial profiles obtained by azimuthally averaging the vortex core images in fig . [ fig1](c ) and ( d ) are in good quantitative agreement with the numerical results taking into account the finite spatial resolution of 5 @xmath32 m in our imaging system [ fig . [ fig2](b ) and ( c ) ] . this demonstrates that the interaction effects are negligible in the evolution of the vortex core in the freely expanding quasi-2d bose - einstein condensate . next , we numerically investigate the free expansion of a quasi-2d condensate containing multiply charged vortices with @xmath33 . a concentric , multiple - ring structure develops as in the @xmath31 case , but its expansion rate increases with higher @xmath14 . we characterize the time evolution of the concentric ripples with the radius @xmath13 of their first density - peak ring [ fig . 2(a ) ] , and find that the ring expansion is nicely fit to @xmath34m / ms@xmath35 for @xmath36 , respectively . the @xmath37-dependence can be understood from the continuity equation for 2d propagation , requiring @xmath38 . the dependence of the expansion rate @xmath39 on the initial core size , _ i.e. _ @xmath40 is very marginal . this seems to reflect the weak dependence of the kinetic energy of the vortex state on the core size , @xmath41 and suggests that the vortex charge number @xmath14 can be unambiguously determined from the radius @xmath13 for a given expansion time @xmath10 . . defocused images of a @xmath14=1 vortex core for various expansion times @xmath10 : ( b)-(d ) experimental data and ( e)-(g ) numerical calculations . ( h)-(j ) the corresponding radial profiles from the experimental data [ ( b)-(d ) , blue square ] and the numerically constructed defocused images [ ( e)-(g ) , red line ] . ( k ) radius @xmath42 ( @xmath43 ) of the first bright ( dark ) ring versus expansion time . the dashed line is the radius @xmath13 for @xmath31 [ fig . in our previous experiment @xcite , similar ring - shaped density ripples were observed in a mechanically perturbed and freely expanding quasi-2d condensate . based on the observation of their apparent ring symmetry and long lifetime , we interpreted them as vortex excitations induced by the mechanical perturbation . however , the core region was filled up after a certain expansion time and this is unexpected in vortex expansion dynamics because of the phase singularity at the vortex core . we find that it was caused by defocussing due to the free fall of the condensate during the expansion time . in this section , we present an analysis of the defocused images of the vortex cores . figure 3(a ) presents a schematic of the 4@xmath44 imaging system used in our experiments . when the condensate is released from the optical trap , it starts falling due to the gravity and its distance to the object plane of the imaging system increases as @xmath45 , where @xmath46 is the gravitational acceleration . then , the image recorded on the ccd camera is the near - field diffraction pattern of the probe beam after propagating by distance @xmath47 from the condensate . the depth of field in the imaging system is about 20 @xmath32 m , so the defocus effect due to the free fall becomes significant already at @xmath48 ms . the in - focus images in fig . [ fig1 ] were taken by adjusting the axial position of the ccd camera to have a smallest vortex core for a given expansion time . we numerically construct the defocused image from the calculated density distribution @xmath49 . ignoring the sample thickness @xmath50^{1/2}<60~\mu$]m for @xmath51 ms , we assume the probe beam after the sample to have a uniform phase and an intensity distribution of @xmath52 $ ] , where we set the central optical density @xmath53 as measured in experiment . from the fresnel diffraction theory @xcite , the beam intensity distribution @xmath54 after propagating by distance @xmath47 is given as @xmath55 where @xmath56 nm is the wavelength of the probe beam . finally , we convolute @xmath54 with a gaussian function with @xmath57 width of 5 @xmath32 m to take into account the finite imaging resolution . the constructed defocused images reveal the core - filling behavior consistent with the experimental observation [ fig . 3(e)-(g ) ] . furthermore , the radial profiles show good quantitative agreement with the experiment data over the whole range of the expansion time @xmath58 [ fig . 3(h)-(j ) ] . when we modify the density distribution @xmath59 deliberately , e.g. , to have no ripples but a constant value for @xmath60 , the resultant defocused images are significantly deviated from the experiment data . this shows that the defocused image is sensitive to the details of the density distribution . controlled defocussing might be used to probe small features below the spatial resolution of the imaging system . it is well known in the diffraction theory that when a light propagates through an aperture of size @xmath61 , its diffraction pattern after the aperture is determined by the fresnel number , @xmath62 , where @xmath47 is the propagation distance from the aperture . since the shape of the concentric ripples around the vortex core is almost preserved during expansion , we expect the core - filling behavior to occur when the normalized propagation distance @xmath63 . with @xmath64 and @xmath45 , @xmath65 , suggesting that the core - filling always occurs in the defocused image after a certain expansion time ( fig . 4 ) . we numerically find that the core region begins to have a local maximum at @xmath66 ms for @xmath36 , respectively , giving the critical value @xmath67 . = 2 ) for ( a ) @xmath118 ms and ( b ) 10.5 ms . the solid circles in fig . 2(b ) indicate the corresponding positions in the @xmath13-@xmath10 plane , where the point for ( b ) is below the dotted line so that the core region in the defocused image shows a local maximum.,width=226 ] we have studied the evolution of the quantized vortex core in a freely expanding quasi-2d bec . the quantitative agreement between the experiment data and the numerical results demonstrates that the free expansion of the quasi-2d condensate is well described as non - interacting ballistic expansion . we have investigated the defocus effect caused by the free fall of the condensate under gravity , and provided a quantitative explanation on the ring - shaped density ripples observed in our previous experiment @xcite . the defocus effect can affect the measurement of the power spectrum of the density fluctuations in a freely expanding 2d bose gas @xcite . recently , we performed in - focus measurements of the power spectrum and experimentally verified that the spectral peak positions are consistent with the theoretical prediction in ref . . one interesting extension of this work is to study free expansion of a quasi-2d bec containing a vortex - anti - vortex pair and investigate how large the pair should be to be detected by free expansion . vortex - pair excitations are important to understand 2d superfluidity @xcite . thermally activated vortex pairs prevail in a 2d superfluid and the superfluid - to - normal phase transition occurs when thermal breaking of the pairs into free vortices becomes energetically preferred . recently , we have succeeded in detecting thermal vortex pairs by applying a radial compression to enhance the visibility of vortex cores @xcite . however , it is still desirable to develop an experimental method to detect thermal vortices in a 2d bose gas in a less perturbative manner . we thank woo - jin kim for assistance in numerical simulation , and igor mazets and tim langen for helpful discussions . this work was supported by the nrf of korea ( 2011 - 0017527 , 2008 - 0062257 , 2013-h1a8a1003984 ) and the posco tj park foundation . r. j. donnelly , _ quantized vortices in helium ii _ ( cambridge university press , cambridge , 1991 ) . v. l. berezinskii , sov . jetp * 34 * , 610 ( 1972 ) ; 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we observe that a density - depleted vortex core evolves into concentric density ripples in a freely expanding quasi - two - dimensional bose - einstein condensate . the atomic density of the expanding condensate rapidly reduces due to the fast expansion along the tightly confining axial direction , and thus the transverse expansion of the condensate is not significantly affected by the atom - atom interactions . we find that the observed density profiles of the vortex cores are in good quantitative agreement with numerical simulations assuming no interactions . we analyze the defocused images of the vortex cores , where defocussing is caused by the free fall of the condensate during the expansion time . in the defocused images , the vortex core becomes magnified and appears to be filled after a certain expansion time which depends on the vortex charge number .

vitamin d has been proven to modulate the immune system through the stimulation of expression of anti - microbial peptides ( amps ) are integral in defense mechanism ( schwalfenberg , 2011 ) . several studies have shown that hypovitaminosis d to be associated with respiratory tract infections including tb ( laaksi et al . , 2007 ; nnoaham and clarke , 2008 ) . vitamin d has been shown to be important in maintaining b cell homeostasis therefore may be useful in the treatment of b cell - mediated autoimmune disorders ( chen et al . , 2007 ) . hypovitaminosis d is associated with an increased risk of cardiovascular disease as shown by the framingham study ( wang et al . , 2008 ) . it increases the risk of myocardial infarction independent of diabetes , hypertension and dyslipidaemia and other known cardiovascular risk factors ( giovannucci et al . , 2008 ) . vitamin d is proven to prevent nephrosclerosis and retard ckd progression through its anti inflammatory and anti proliferative properties and inhibition of renin production ( danescu et al . , 2009 ) . in patients with established ckd , treatment with calcitriol was associated with a trend towards a lower incidence of dialysis initiation and a decrease in overall mortality rates ( autier and gandini , 2007 ; doorenbos et al . , interestingly , vitamin d also has anti cancer properties by promoting cell differentiation and inhibiting cell proliferation and angiogenesis ( giovannucci et al . , 2005 ) . studies have shown patients with low levels of vitamin d to be associated with increased cancer incidence ( giovannucci , 2006 ) . recent studies worldwide have reported a high prevalence of vitamin d deficiency in the general population and is even more common in patients with chronic kidney disease ( ckd ) ( zadshir et al . , 2005 ; adams and hewison , 2010 ) . apart from a reduction in renal 1-hydroxylase activity , diabetes and proteinuria have also been implicated with vitamin d deficiency in ckd patients ( schiavi and kumar , 2004 ; holden et al . , 2010 ) . interestingly , urinary protein losses were reported to be a more important predictor of vitamin d deficiency than the degree of ckd ( mehrotra et al . , 2008 ) . there is poor consensus as to what constitutes the optimal level of vitamin d or what defines vitamin d insufficiency or deficiency . at present , most experts define vitamin d insufficiency as a 25(oh ) d level of less than 30 ng / ml and levels less than 15 ng / ml as vitamin d deficiency ( zadshir et al . , 2005 ; , it has been estimated that one billion people worldwide have either vitamin d deficiency or insufficiency ( lips et al . , 2006 ) . it was reported that among 15,390 adults in the united state , half had vitamin d deficiency ( zadshir et al . , 2005 ) . the prevalence of this condition increases with advancing age and is more predominant in hispanics and blacks compared to their white counterparts ( zadshir et al . , 2005 ; tareen et al . , 2005 ; yetley , 2008 ) a study in post - menopausal asian women reported , approximately 50 % of siamese and malaysian women had serum 25(oh)d of less than 30ng / ml and increased to 90 % in japanese and korean women ( lim et al . , 2008 ) . among the affected malaysian , it was more prevalent in the malay race compared to other races ( rahman et al . , 2004 ) . although failure of 1,25(oh)2d3 synthesis is the cause of vitamin d deficiency in patients with ckd , studies on vitamin d levels are still based on measurements of serum 25(oh)d ( zittermann , 2003 ; al - badr and martin , 2008 ) . this is because the former is difficult to measure given that it 's half - life is only 4 - 6 hours . compared to 25(oh)d in which is the most stable and plentiful metabolite of vitamin d in humans and has a half - life of about 3 weeks , making it the most suitable indicator of vitamin d status ( thacher and clarke , 2011 ) . furthermore , 1,25 ( oh)2d3 circulates at picogram concentrations that are 1000 times less than those of the precursor 25(oh)d . hence this metabolite must be extensively purified before being measured by radioimmunoassay ( thacher and clarke , 2011 ) . therefore , earlier stages of vitamin d deficiency can be missed by measuring 1 , 25(oh)2d3 . studies have found that circulating concentrations of 25(oh)d levels is a sensitive measurement of vitamin d status that reflects both intake and endogenous production in response to solar ultraviolet b exposure ( jones et al . , 2007 ; holick , 2007 ) . in view of the association of hypovitaminosis d with diseases and its implications , we decided to embark on this study to see the prevalence of hypovitaminosis d in our population . a cross - sectional study comparing patients with ckd ( attending follow - up at the nephrology clinic at our institution ) with the normal healthy population . the study was approved by the research and ethics committee with research grant ff-227 - 2010 . our exclusion criteria included : acute renal failure , end stage renal disease , chronic liver disease , malabsorption syndromes , granulomatous disease and patients who were on medications known to affect vitamin d absorption or metabolism such as anticonvulsants , isoniazid , rifampicin , theophylline , glucocorticoids , calcium and vitamin d supplements . the control group were volunteers from our institution and with no medical illness . estimated glomerular filtration rate ( egfr ) was calculated with the equation of the modification of diet in renal disease ( mdrd ) study group and categorized based on the nkf kidney disease outcomes quality initiative guidelines ( k / doqi guidelines , 2003 ) . weight and height were measured to calculate bmi and categorized based on the malaysian clinical practice guideline on management of obesity to : underweight ( < 18.5 kg / m ) , normal ( 18.5 to 22.9 kg / m ) , overweight ( 23.0 to 27.4 kg / m ) and obese ( 27.4 kg / m ) ( academy of medicine of malaysia ministry of health , 2004 ) . current smokers were defined as patients smoking at least one cigarette per day during the previous 6 months . 10 ml of fasting venous blood was collected for measurement of 25-hydroxyvitamin d ( 25(oh ) d , intact parathyroid hormone ( ipth ) and other routine blood tests . urine was collected for urine dipstick , microscopy and urine protein creatinine index ( upci ) . serum for 25 ( oh ) d assays was centrifuged at 3000 rpm for 10 minutes at room temperature and stored at -80 c until assayed . the 25(oh ) d was tested in duplicate , in a single laboratory and was assayed in a single batch to avoid inter assay variations . we used the 25(oh)d assay radioimmunoassay kit ( diasorin stillwater , minnesota , usa ) which has been used in several other studies ( ( del valle et al . for the purposes of analysis , 25(oh)d concentration was categorized based on current kidney disease outcomes quality initiative guidelines ( k / doqi guidelines , 2003 ) to : optimal level ( > 30 ng / ml ) , insufficient ( 15 - 30 ng / ml ) and deficient ( < 15 ng / ml ) . serum for 25 ( oh ) d assays was centrifuged at 3000 rpm for 10 minutes at room temperature and stored at -80 c until assayed . the 25(oh ) d was tested in duplicate , in a single laboratory and was assayed in a single batch to avoid inter assay variations . we used the 25(oh)d assay radioimmunoassay kit ( diasorin stillwater , minnesota , usa ) which has been used in several other studies ( ( del valle et al . , 2007 ; levin et al . , 2007 ; mehrotra et al . , 2008 ; holden et al . , 2010 ) . for the purposes of analysis , 25(oh)d concentration was categorized based on current kidney disease outcomes quality initiative guidelines ( k / doqi guidelines , 2003 ) to : optimal level ( > 30 ng / ml ) , insufficient ( 15 - 30 ng / ml ) and deficient ( < 15 ng / ml ) . data were analysed using the statistical package for social science ( spss ) software version 19 . normally distributed data were expressed as mean standard deviation ( sd ) and non - normally distributed data were expressed as median ( iqr ) . for normally distributed data student 's t - test or one - way anova were used and for non - normally distributed data , mann - whitney u or kruskal wallis tests were used . all statistical tests were two sided and an unadjusted p value of < 0.05 was considered significant . . as expected , the control group had a normal serum creatinine , thus higher egfr and a normal blood pressure . majority of the patients ( 58.0 % ) had ckd stage 3 , followed by fifteen ( 30.0 % ) with ckd stage 4 and six ( 12.0 % ) subjects with ckd stage 2 ( table 2(tab . , there was a trend towards an increasing age with advancing ckd stage ( p = 0.068 ) . the leading cause of ckd in our patient cohort was diabetic nephropathy in 31(62.0 % ) of the patients followed by chronic glomerulonephritis in 13 ( 26.0 % ) patients . all study subjects regardless of renal status were found to have hypovitaminosis d. their mean levels of 25(oh ) d were comparable in the control and ckd groups ( 15.3 4.2 ng / ml and 16.1 6.2 ng / ml ( p = 0.453 ) respectively . the proportion of subjects with 25(oh)d insufficiency and 25(oh)d deficiency were also comparable in both groups . however in 25(oh)d deficiency group , the mean levels of 25(oh)d was significantly lower in the ckd groups [ 11.2 ( 6.5 ) ng / ml vs 12.6 ( 3.7 ) , p = 0.039 ] . the serum 25(oh ) d levels were also not different across the different ckd stages ( p = 0.87 ) . a further sub - analysis was done to compare the serum 25(oh ) d levels amongst ckd patients with and without diabetes mellitus . the mean serum 25(oh ) d tended to be lower in diabetic patients compared with those in non - diabetics . additionally , more of the diabetic ckd patients were 25(oh)d deficient ( 16/31 vs 4/19 , p = 0.032 ) . female gender ( p < 0.001 ) , diabetic status ( p = 0.032 ) and lower serum haemoglobin levels ( p = 0.002 ) were significantly associated with hypovitaminosis d status . multivariate analysis showed female gender and diabetes were independent predictors for vitamin d deficiency in ckd patients ( table 3(tab . all study subjects regardless of renal status were found to have hypovitaminosis d. their mean levels of 25(oh ) d were comparable in the control and ckd groups ( 15.3 4.2 ng / ml and 16.1 6.2 ng / ml ( p = 0.453 ) respectively . the proportion of subjects with 25(oh)d insufficiency and 25(oh)d deficiency were also comparable in both groups . however in 25(oh)d deficiency group , the mean levels of 25(oh)d was significantly lower in the ckd groups [ 11.2 ( 6.5 ) ng / ml vs 12.6 ( 3.7 ) , p = 0.039 ] . the serum 25(oh ) d levels were also not different across the different ckd stages ( p = 0.87 ) . a further sub - analysis was done to compare the serum 25(oh ) d levels amongst ckd patients with and without diabetes mellitus . the mean serum 25(oh ) d tended to be lower in diabetic patients compared with those in non - diabetics . additionally , more of the diabetic ckd patients were 25(oh)d deficient ( 16/31 vs 4/19 , p = 0.032 ) . female gender ( p < 0.001 ) , diabetic status ( p = 0.032 ) and lower serum haemoglobin levels ( p = 0.002 ) were significantly associated with hypovitaminosis d status . multivariate analysis showed female gender and diabetes were independent predictors for vitamin d deficiency in ckd patients ( table 3(tab . all patients in both groups of our study cohort have hypovitaminosis d. the control subjects despite being younger , predominantly reproductive aged females and almost exclusively malay doctors and nurses of our hospital , their prevalence of hypovitaminosis d was no far better than the ckd group . their prevalence of vitamin d insufficiency ( 15 to 30 ng / ml ) was 46 % and vitamin d deficiency ( < 15 ng / ml ) was 54 % as opposed to 60 % with vitamin d insufficiency and 40 % with vitamin d deficiency in the ckd group . the reported prevalence of hypovitaminosis d has been consistently and unexpectedly high in almost all populations studied worldwide and across the age spectrum . a previous local study in primary school children aged 7 - 12 years old ( n = 402 ) showed the prevalence of hypovitaminosis d ( < 30 ng / ml ) to be 73 % ( khor et al . , 2011 ) . whereas , rahman et al . found in post - menopausal women aged 50 to 65 years the level of 25(oh ) d to be significantly lower in the postmenopausal malay women compared to chinese women(p < 0.05 ) ( rahman et al . , 2004 ) . however most studies used a serum 25(oh ) d level of less than 30 ng / ml to define hypovitaminosis d. nonetheless a recent united states guideline on dietary requirements for calcium and vitamin d suggested a serum 25(oh ) d levels of at least 20 ng / ml should be considered as an adequate vitamin d level which meets the requirements of at least 97.5 % of the population ( ross et al . , 2011 ) . using the same definition , the prevalence of hypovitaminosis d in our control and ckd group would be reduced to 86 % and 76 % respectively ( p = 0.202 ) . hypovitaminosis d ( < 30mg / ml ) has been shown to be associated with increased risk of cardiovascular disease and its risk factors i.e obesity , hypertension and diabetes ( martins et al . , 2007 ) . however at present the exact cut off between increased risk is not clear with some studies saying less than 20 mg / ml and also varies with different races ( holick , 2004 ) . as to what the optimum level we need to target to confer benefits is not clear although levels > 37 mg / ml has been suggested by one study ( martins et al . , 2007 ) . since the prevalence of hypovitaminosis d in both of our groups was high , it raised the question of what were the common similar factors in both groups . the two main determinants of vitamin d levels are sunlight exposure and dietary intake . in general , malaysian diet lacks good sources of vitamin d as they rarely take cereal ( fortified ) , margarine , milk or cheese regularly . previous studies have used a single 24 hour dietary recall ( holden et al . , 2010 ; mehrotra et al . , 2008 however this method is prone to recall bias and may not represent an individual 's general dietary intake and habits . sunlight exposure between studies is also non - consistent and often there is no objective measurement of sun exposure ( levin et al . , 2007 ; del valle et al . , 2007 ) . the validated measures of sun exposure has only been published very recently ( saliba et al . , 2012 ) . hypovitaminosis d of both normal and ckd subjects due to the lack of sun exposure is undeniably important as malaysia is a tropical country with a hot and humid climate . surprisingly , many other countries with a lot of sun exposure such as in the middle east also showed a similar prevalence of hypovitaminosis d ( sedrani , 1984 ; mcgrath et al . this may be explained by the fact that these muslim countries require women to be fully covered except for the hands and face thus reducing their exposure to sunlight . this finding has been supported by studies in european countries where the prevalence hypovitaminosis d is high in immigrants who are covered and veiled ( lowe et al . , 2010 ) . as our study also consists of predominantly muslim women ( 76 % in control group and 42 % in ckd group ) who shared similar attire code as their counterparts worldwide , this is likely to play a major part in contributing to the reduced serum vitamin d levels from sun exposure . the blacks and hispanics were reported to have higher prevalence of hypovitaminosis d compared to the caucasians ( gutirrez et al . , 2011 ) . south asian women had significantly higher serum pth and lower serum 25(oh)d concentrations than caucasian women in the uk ( lowe et al . , 2010 ) . however , this was not associated with higher levels of markers of bone resorption or reduced bone quality in the south asian women ( lowe et al . , 2010 ) . in the present study , female gender and diabetes mellitus were found to be independently associated with lower levels of 25(oh)d . female gender was found to have an inverse relationship with serum 25(oh)d levels in previous study ( mehrotra et al . , 2008 ) . this could explain the high prevalence of hypovitaminosis d in our population whereas in diabetes , there is emerging data showing vitamin d deficiency to be a contributing factor for the development of both type 1 and 2 diabetes . the cells of pancreas not only secrets insulin but also contains vitamin d receptor ( vdrs ) as well as 1- hydroxylase enzymes . it has been proven that treatment with vitamin d improves glucose tolerance and insulin resistance ( martin and campbell , 2011 ) . bmi and obesity have also been implicated with hypovitaminosis d. obesity reduces the availability of vitamin d due to sequestration of vitamin d in body fat ( holick , 2007 ) . these findings emphasize the need for appropriate interventions to address the problem of obesity in our younger population to reduce the risk of the metabolic syndrome later in life . as shown in our study , the control group was found to be overweight whereas in the ckd group were noted to be obese . in ckd , the loss of the renal1-hydroxylase is largely responsible for the hypovitaminosis d. several epidemiologic studies have reported patients with ckd stages 3 to 5 to have lower 25(oh ) d concentrations than the general population ( gonzlez et al . , 2004 ; levin et al . , 2007 ) . the identification of extrarenal 1-hydroxylase suggests that 25(oh)d status is an important consideration in patients with ckd ( gal - moscovici and sprague , 2007 ) . ideally , the serum levels of 1,25 ( oh)2d3 which is the biologically active form of vitamin d should be measured . however , low levels of the 25(oh)d itself may contribute to decreased levels of 1,25(oh)2d3 production , particularly in ckd patients with nephrotic range proteinuria ( levin et al . there is an association between lower serum 25(oh)d levels and poorer kidney function , higher bmi and higher albuminuria , lower serum calcium and higher serum phosphorus , intact parathyroid hormone ( ipth ) and alkaline phosphatase ( alp ) . nutritional factors associated with higher 25(oh)d levels were stable weight , higher albumin and hdl cholesterol ( holden et al . , 2010 ) . in our ckd patients , the serum levels of albumin , haemoglobin , calcium and high density lipoprotein - cholesterol ( hdl ) decreased proportionately with advancing ckd stage . whereas , the levels of serum phosphorus , alp and ipth rose significantly . once egfr drops to less than 30 ml / min/1.73 m ( ckd stage 4 ) , the 1-hydroxylase activity becomes impaired . this in turn will cause a significant decrease in intestinal calcium absorption leading to a reduction in circulating serum calcium . as a result , parathyroid hormone also causes increased phosphaturia , resulting in low - normal serum phosphorus . without an adequate calcium - phosphorus product , mineralization of the collagen matrix is diminished hence aggravating the renal bone disease in ckd . in view of such a high prevalence of hypovitaminosis d in ckd and its possible complications , we have proceeded with a further study to see the effects of vitamin d replacement in this group of patient .

introduction : hypovitaminosis d is reported to be associated with several medical complications . recent studies have reported a high worldwide prevalence of vitamin d deficiency in the general population ( up to 80 % ) . this is even higher in patients with chronic kidney disease ( ckd ) and increases with advancing stages of ckd.objectives : to determine the difference in serum vitamin d [ 25-hydroxyvitamin d , 25(oh ) d ] levels between ckd patients and normal healthy population . materials and methods : a prospective cross - sectional study involving 50 normal volunteers ( control ) and 50 patients with ckd stages 2 - 4 . their demographic profiles were recorded and blood samples taken for serum 25(oh ) d , intact parathyroid hormone ( ipth ) and other routine blood tests.results : all subjects regardless of renal status had hypovitaminosis d ( < 30ng / ml ) . the mean serum 25(oh ) d were comparable in the control and ckd groups ( 15.3 4.2 ng / ml vs 16.1 6.2 ng / ml , p = ns ) . however , within the vitamin d deficient group , the ckd group had lower levels of serum 25(oh ) d [ 12.6(3.7 ) ng / ml vs 11.2(6.5 ) ng / ml , p = 0.039 ] . female gender [ or 22.553 ; ci 95 % ( 2.16 - 235.48 ) ; p = 0.009 ] and diabetic status [ or 6.456 ; ci 95 % ( 1.144 - 36.433 ) ; p = 0.035 ] were independent predictors for 25(oh ) d deficiency . conclusions : vitamin d insufficiency and vitamin d deficiency are indeed prevalent and under - recognized . although the vitamin d levels among the study subjects and their control are equally low , the ckd group had severe degree of vitamin d deficiency . diabetic status and female gender were independent predictors of low serum 25(oh)d .

current density filament in a bistable semiconductor structure with s - shaped current - voltage characteristic is a high current density domain embedded in a low current density environment @xcite . typically filaments appear spontaneously due to spatial instability of the uniform current flow when the average current density corresponds to the falling branch of the current voltage - characteristic @xcite . a single filament survives after the transient ( the - winner - takes - all principle ) whereas multifilamentary states are unstable @xcite . a static current filament may undergo further bifurcations related to temporal and spatial instabilities @xcite . spontaneous onset of the lateral movement is an example of such a bifurcation which has been recently studied both experimentally and theoretically @xcite . this effect is of significant practical importance because the filament motion delocalizes the joule heating of a semiconductor structure operated in the current filamentation regime , and thus dramatically reduces the probability of thermal failure @xcite . traveling current density filaments bear deep similarities to other traveling spots in active media @xcite , in particular , to traveling wave segments in feed - back controlled light sensitive belousov - zabotinsky reaction @xcite . the latest exerimental observations of moving filaments @xcite have been made using a recently developed interferometric mapping technique @xcite . experiments show that in a device with a stripe - like geometry the filament travels in a soliton - like manner with a constant velocity @xmath0 and reflects from the device boundaries . both measurements and full - scale numerical simulations of the transport processes suggest that the filament motion is thermally driven and related to the joule self - heating @xcite . thermally driven self - motion is possible due to the negative effect of temperature on the impact ionization rate @xcite and may occur in a wide class of semiconductor structures whose bistability is caused by impact ionization @xcite . the temperature acts as an inhibitor which provokes translation instability of a steady filament and causes its self - sustained motion towards a cooler region @xcite . in this article we present an analytical investigation of the translation instability which occurs at the onset of thermally driven filament motion . using a recently suggested three - component reaction - diffusion model for current filamentation in presence of the joule self - heating @xcite , we perform a stability analysis of a static filament . we show that the translation invariance of a static filament in a large structure breaks in presence of the self - heating . this occurs with increase of the thermal relaxation time which depends on the heat capacity of the semiconductor structure and the efficiency of the external cooling . the instability threshold decreases when the effect of temperature on the vertical transport becomes stronger and increases with heat diffusion coefficient . current filamentation in bistable semiconductors can be described by a two - component activator - inhibitor model which consists of a nonlinear reaction - diffusion equation , accounting for the internal activator dynamics in a bistable semiconductor , and an integro - differential equation , accounting for the applied voltage . this model , originally developed for bulk semiconductors with so called overheating instability @xcite and layered semiconductor structures @xcite , proved to be efficient for a wide class of bistable semiconductors with various mechanims of bistability ( see ref . and references therein ) . we refer to refs . for comprehensive general formulation of this model . to decribe the thermally driven motion of a current density filament , the effect of temperature @xmath1 on the cathode - anode transport and the heat dynamics in the structure should be additionally taken into account . the respective extension of the conventional two - component model @xcite has been recently suggested in ref . : @xmath2 here @xmath3 acts as an activator , @xmath4 and @xmath1 as inhibitors . eqs.([master],[global ] ) are the same as in the conventional two - component model @xcite . the variable @xmath5 characterizes the internal state of the device , @xmath6 is the voltage over the device . the local kinetic function @xmath7 and the @xmath8 dependence contain the information about the vertical electron transport in the cathode anode direction and together determine the s - shaped local current - voltage characteristic ( fig.1 ) . the function @xmath9 has three zeros corresponding to the off , intermediate and on states , respectively , when the voltage @xmath4 is within the bistability range @xmath10 $ ] ( the upper insert in fig.1 ) . the diffusion coefficient @xmath11 characterizes lateral ( along the @xmath12 plane ) coupling in the spatially extended semiconductor structure . eq.([global ] ) is a kirchhoff s equation for the external circuit . @xmath13 is the load resitance switched in series with the semiconductor structure , @xmath14 is the total applied voltage , @xmath15 is the effective capacitance of the sample and the circuit , @xmath16 is the device area of the structure cross - section . in the following we consider the current - controlled regime . eq.([heat ] ) describes the heat dynamics in the structure . similar to the variable @xmath3 , the temperature @xmath17 depends only on the lateral coordinates @xmath18 and @xmath19 . @xmath20 is the temperature of the external cooling reservoir , @xmath21 is heat transfer coefficient , the termal relaxation time @xmath22 and diffusion length @xmath23 are given by @xmath24 where @xmath25 , @xmath26 and @xmath27 are specific heat , density and heat conductivity of the semiconductor material , respectively , and @xmath28 is the device thickness in the cathode - anode direction . the master equation ( [ master ] ) is coupled to the heat equation ( [ heat ] ) via the temperature dependence of the local kinetic function @xmath29 . since the heating suppresses impact ionization , the effect of temperature on the vertical transport is negative and @xmath30 @xcite . the direct dependence of the current density @xmath31 on @xmath1 is neglected . the characteristic size of a filament wall is @xmath32 @xcite . parameters @xmath33 and @xmath23 are diffusion lengths of the activator and inhibitor , respectively . for simplicity , in the following we take @xmath34 . next , we take into account only one lateral dimension @xmath18 , assuming that due to the stripe geometry of the semiconductor structure ( @xmath35 ) the current density distribution is uniform along the @xmath19 direction ( the lower insert in fig.1 ) . we also assume that the filament is located far from the edges of the stripe @xmath36 . current density and temperature profiles in a static filament are shown in the upper panel of fig.2 . for @xmath37 the temperature profile essentially follows the current density profile ( fig.2 , curve 1 in the upper panel ) . for @xmath38 the characteristic size of the hot area is much larger than the filament size ( fig.2 , curve 2 in the upper panel ) . antisymmetric ( with respect to the center of the filament ) fluctuations of the current density do not change the total current and therefore are not suppressed by the external circuit in the current - controlled regime . by increasing the current denisity on one side and decreasing on another such fluctuation effectively leads to a small shift of a filament , moving one of the filament edges to a cooler region and another to a hotter region . due to the heat inertia of the semiconductor structure the temperature does not follow the current density instantly . hence favorable conditions for the impact ionization ( production of the activator @xmath3 in terms of eq.([master ] ) ) appear at the one of the filament edges , whereas at another edge the impact ionization is suppressed . this leads to further shift of a filament and , for a sufficiently long delay of the temperature response , to a self - sustained filament motion . experiments @xcite show that in a high quality structure filaments start to move to the left and to the right with equal probability . this suggests that motion is triggered by nonequilibrium fluctuations of the current density . let us consider a stationary solution @xmath39 , @xmath40 , @xmath41 of the equations ( [ master],[heat],[global ] ) : @xmath42 here the prime @xmath43 denotes the derivative with respect to @xmath18 and angular brackets @xmath44 denote integration over the interval @xmath45 $ ] . linearization in the vicinity of the stationary solution with respect to the fluctiations @xmath46 leads to the eigenvalue problem @xmath47 here @xmath48 and all derivatives are computed at the steady state @xmath39 , @xmath40 , @xmath41 . let us briefly summarize the results of the stability analysis in the reference case of constant temperature @xmath50 @xcite . in this case eq.([master_stab1 ] ) is reduced to @xmath51 the eigenfunctions @xmath52 , @xmath53 of the self - adjoint operator @xmath54 correspond to eigenmodes of the stationary filament in the voltage - controlled regime @xmath55 ( fig.2 , lower panel ) . these eigenmodes are orthogonal and obey the oscillation theorem which says that @xmath56 has @xmath57 nodes inside the interval @xmath45 $ ] . due to the translation invariance for an infinitely large sample the spectrum of @xmath54 contains a neutral ( so called goldstone ) mode @xmath58 with @xmath59 . this mode corresponds to the translation of the filament along the @xmath18 axis . for a solitary filament @xmath39 has a single maximum . hence @xmath60 has one node and is identified as @xmath61 @xcite . since @xmath62 and @xmath63 , the first eigenvalue @xmath64 is positive . the first eigenmode @xmath65 corresponds to spreading or shrinking of the current filament . since @xmath66 is symmetric with respect to the center of the filament , the potential term " @xmath67 in the operator @xmath54 is also symmetric . hence @xmath65 and @xmath61 are symmetric and antisymmetric , respectively . the increase of @xmath65 is prevented by the global constraint ( [ global ] ) which effectively fixes the total current when the external resistance @xmath13 is sufficiently large @xcite . in contrast , for @xmath68 the last term in the eq.([global_stab1 ] ) vanishes due to the asymmetry of @xmath61 . hence in this case @xmath69 and @xmath70 are not coupled , and we can take @xmath71 . physically , it happens because @xmath61 does not change the total current and therefore the voltage @xmath4 also does not change . thus for the current - controlled regime the dynamics of @xmath61 is the same as in the voltage - controlled regime , and @xmath72 @xcite . we conclude that for the two - component model filaments have neutral stability with respect to translation when the lateral dimension of the semiconductor structure is large ( @xmath73 ) . we shall focus on the second eigenmode @xmath61 with @xmath62 and investigate whether for the extended model ( [ master],[heat],[global ] ) the respective increment @xmath74 departs from zero due to the coupling between the master equation ( [ master ] ) and the heat equation ( [ heat ] ) . as we argued above , in linear approximation the antisymmetric translation mode does not interact with external circuit and hence @xmath71 . the set of equations ( [ master_stab1],[heat_stab1],[global_stab1 ] ) reduces to @xmath75 for the model ( [ master],[heat],[global ] ) the translation goldstone mode @xmath76 has two components which are given by @xmath77 by taking the space derivative of eqs.([master_steady],[heat_steady ] ) we find that @xmath78 indeed satisfies eqs.([master_stab2],[heat_stab2 ] ) for @xmath79 : @xmath80 the increment @xmath74 of the translation mode can be found from eqs.([master_stab2],[heat_stab2 ] ) by means of the perturbation theory with respect to the isothermal case @xmath72 . substituting @xmath81 in eq.([heat_stab2 ] ) we obtain @xmath82 the solution @xmath83 $ ] determines the temperature response to the variation @xmath84 of the activator distribution and depends on both @xmath84 and @xmath74 . substitution of @xmath85 $ ] into eq.([master_stab2 ] ) leads to @xmath86.\ ] ] now note that according to eqs.([heat_stab3],[heatresponce ] ) @xmath87 can be presented as @xmath88.\ ] ] therefore according to eq.([master_stab3 ] ) @xmath89=0.\ ] ] substracting ( [ int2 ] ) from ( [ int1 ] ) , muliplying by @xmath84 and integrating over @xmath18 , we come to the equation for @xmath74 : @xmath90-\delta t[\zeta=0 , \delta a_g]\right ) a_0^{\prime } \rangle } { \langle ( a_0^{\prime})^2 \rangle}. \label{characteristic0}\ ] ] in the next two sections we find @xmath91 $ ] and solve the equation ( [ characteristic0 ] ) for the limiting cases @xmath37 and @xmath38 . in this section we consider the case @xmath37 when lateral diffusion of the internal parameter @xmath3 is much more efficient than the heat diffusion . in this case the temperature profile essentially follows the current density profile ( fig.2 , curve 1 in the upper panel ) . in the limiting case @xmath92 the solution of eq.([heatresponce ] ) is given by @xmath93 = \frac{u_{0 } \ , \partial_a j}{\gamma(\tau_t \zeta + 1 ) } \ ; \delta a_g . \label{heatresponce1}\ ] ] with this input eq.([characteristic0 ] ) yields @xmath94 two solutions @xmath95 and @xmath96 of this equation appear to intersect at @xmath97 in the degenerate case ( @xmath59 ) under consideration . the relevant branch can be chosen by starting from @xmath98 and taking the limit @xmath99 ( see appendix ) . this leads to the piecewise linear dependence : @xmath100 according to ( [ increments1 ] ) , for sufficiently small @xmath22 the filament remains neutral with respect to translation . the bifurcation from static to traveling filaments occurs with increase of @xmath22 at @xmath97 . note that in the limiting case @xmath22 = 0 the temperature @xmath1 instantly follows all changes of the current density . in this case @xmath1 is a local function of the parameter @xmath3 and can be eliminated by re - defining the local kinetic function according to @xmath101 in this way the three - component model is reduced back to the two - component model which with respect to the filament stability is equivalent to the isothermal model for @xmath50 . hence for @xmath102 filament has neutral stability , in agreement with eq.([increments1 ] ) . in the opposite case of slow self - heating ( @xmath103 ) the increment @xmath74 has the largest value @xmath104 . generally , the heat diffusion smoothes the temperature response @xmath105 $ ] , thus shifting the instability threshold to larger values of @xmath22 . in the opposite limiting case @xmath106 the lateral spreading of heat is more efficient than the lateral spreading of the current density ( fig.2 , curve 2 in the upper pannel ) . we restrict the analysis to a filament with a flat top ( fig.3 ) . such filaments are typical for large structures ( @xmath107 ) . the filament width and characteristic width of the filament wall are denoted as @xmath108 and @xmath109 , respectively . note that @xmath110 @xcite . in this case the translation mode @xmath111 is distinct from zero only within the filament walls where it has a characteristic value @xmath112 ( fig.3 , lower panel ) . taking into account the scale separation @xmath113 , we can approximate @xmath84 as @xmath114 , \label{translation}\ ] ] where @xmath115 is the delta - function , the center of the filament is taken at @xmath116 and the prefactor @xmath117 provides normalization @xmath118 . for @xmath84 given by ( [ translation ] ) the solution @xmath105 $ ] of eq.([heatresponce ] ) is @xmath119\right ] \exp\left(\frac{x+(w/2)}{\widetilde \ell_t}\right ) , \\ \nonumber & { \rm for } & \qquad x < - w/2 , \\ \nonumber \delta t & = & - m \widetilde \ell_t \exp \left[- \frac{w}{2 \widetilde \ell_t } \right ] \sinh \left(\frac{x}{\widetilde \ell_t } \right ) , \\ \nonumber & { \rm for } & \qquad -w/2 < x < w/2 , \\ \nonumber \delta t & = & - \frac{m \widetilde \ell_t}{2 } \left[1 - \exp \left[- \frac{w } { \widetilde \ell_t } \right]\right ] \exp\left(-\frac{x - ( w/2)}{\widetilde \ell_t}\right ) \\ \nonumber & { \rm for } & \qquad x > w/2,\end{aligned}\ ] ] where @xmath120 substituting @xmath121 $ ] into ( [ characteristic0 ] ) we obtain @xmath122 \right . \left . - m(0 ) \ , \ell_t \ , \left[1 - \exp\left(-\frac{w}{\ell_t}\right)\right ] \right).\end{aligned}\ ] ] taking into account that near the bifurcation point @xmath74 is small , we expand the right handside of eq.([characteristic2 ] ) over ( @xmath123 ) and come to the equation @xmath124 eq.([characteristic3 ] ) coincides with eq.([characteristic1 ] ) when @xmath125 is replaced by @xmath126 and @xmath22 by @xmath127 . hence the solutions have the same structure as in eq.([increments1 ] ) : @xmath128 for @xmath129 the condition for the onset of filament motion is given by eq.([increments1 ] ) and can be presented as @xmath130 in the opposite limiting case @xmath106 this condition is given by @xmath131 in both cases @xmath38 and @xmath37 the instability occurs when the thermal relaxation time @xmath22 is sufficiently large . this suggests that @xmath22 is a bifurcation parameter also in the intermediate case @xmath132 . the relation between @xmath133 and @xmath134 becomes transparent when @xmath135 and @xmath136 are considered as constants . ( note also that @xmath110 . ) in this case @xmath137 for wide ( @xmath138 ) and narrow ( @xmath139 ) filaments the expansion of @xmath140 over @xmath141 ( see eq.([characteristic3 ] ) ) leads to @xmath142 thus the threshold time @xmath143 exceeds @xmath144 by a factor which is always larger than @xmath145 . for @xmath106 the instability threshold has been previously obtained in ref . for the current density profile as shown in fig.3 . the argument is based on the finding that the velocity @xmath146 of the stationary filament motion is proportional to the difference of temperatures at the front and back filament edges @xmath147 : @xmath148 @xcite . this temperature difference , in turn , depends on the @xmath146 . hence the velocity of stationary motion can be found from the equation @xmath149 . since for @xmath150 the temperature profile is symmetric , @xmath151 . therefore @xmath150 is always a solution of this equation . however , this solution is unstable if @xmath152 increases faster than @xmath153 with increase of @xmath146 . in this case when @xmath146 deviates from @xmath150 , the `` overproduction '' of the the temperature difference @xmath147 leads to further increase of @xmath146 . the respective condition is given by @xcite @xmath154 here @xmath155 has the meaning of the upper limit of the filament velocity and @xmath156 is the thermal velocity . @xmath157 , @xmath158 and @xmath159 , @xmath160 are the current denisties and the values of the variable @xmath3 correspoding to the uniform on and off states at @xmath161 , respectively ( fig.3 ) . @xmath140 is exactly the same as in eq.([characteristic2 ] ) . the criterium ( [ stab3 ] ) can be re - written as @xmath162 taking into account that for a wide filament @xmath163 and considering the function @xmath135 as a constant , we find @xmath164 hence @xmath165 comparing eq.([stab2 ] ) and eq.([stab5 ] ) , we see that @xmath166 coincides with @xmath134 ( see eq.([stab2 ] ) if we approximate the partial derivative @xmath136 by the finite difference @xmath167 remarkably , the difference between the regimes of weak and strong heat diffusion , which is well - pronounced near the bifurcation from static to traveling filament , vanishes for fast self - sustained filament motion with velocity @xmath168 . in this regime the static thermal diffusion length @xmath169 should be replaced by @xmath170 , where @xmath171 is the time of the filament passage over its width @xmath108 and @xmath172 is thermal diffusivity . for @xmath173 the heat diffusion is negligible . this condition yields @xmath174 for typical filament width @xmath175 the condition ( [ conditionsqrt ] ) yields @xmath176 for si and @xmath177 for gaas ( @xmath178 and @xmath179 , respectively ) . if the condition @xmath173 is met togeter with the condition @xmath180 , the heating is not only local but also adiabatic . ( note that for @xmath181 these two conditions are equivalent . ) in this case the rate of temperature increase in each point is proportional to the local power dissipation . the velocity of such fast narrow filament has been obtained in ref . : @xmath182 substituting the definitions @xmath22 and @xmath155 ( see eqs.([thermal],[v_0 ] ) ) , we find that the filament velocity is proportional to the square root of the total joule power which is dissipated in the filament : @xmath183 where @xmath184 is specific heat per unit volume and the coefficient @xmath185 is given by @xmath186 alternative elementary derivation of the square root dependence is presented in ref .. apparently , the square root dependences ( [ sqrt1],[sqrt2 ] ) reflect the experimental situation which is favorable for observation of traveling filaments because large velocity corresponds to low instability threshold . it has been reported @xcite that the results of experimental measurements of the filament velocity in a si device ( @xmath187 , @xmath188 ) indeed obey the square root dependence . the piecewise linear dependence ( [ increments1],[increments2 ] ) of the increment @xmath74 on the bifurcation parameter @xmath189 as well as the square root behaviour of the filament velocity near the bifurcation point , predicted in ref . , are qualitatively the same as obtained in ref . for the three - component cubic " model for a traveling spot . these features seem to be typical for a degenerate drift pitchfork " bifurcation associated with @xmath59 . note that the mechanism of self - motion described here for one - dimensional spatial domains is also valid for two - dimensional domains . the difference between the model ( [ master],[heat],[global ] ) and three - component models for traveling spots studied in refs.@xcite has been discussed in ref .. generally , the self - motion of a current filament becomes possible when a semiconductor structure , apart from the activator mechanism which leads to bistability , posseses an internal mechanism of slow inhibition . as we described here , such mechanim can appear due to the effect of joule heating on the cathode - anode electron transport . another inhibitor mechanism of purely electrical origin has been discussed in refs.@xcite . for this mechanism inhibition is associated with the internal voltage drop across the plasma layer inside of the semiconductor structure . the regions of activation and inhibition are spatially separated . the effective reaction - diffusion model @xcite for such two - layer system has the same structure as ( [ master],[heat],[global ] ) . recent numerical simulations demonstrate that this mechanism leads to filament motion during the switching - off transients in power diodes @xcite . the applicability of this concept to thyristor - like @xmath190 structures discussed in @xcite should be considered in view of the latest studies @xcite which reveal complexity of the vertical transport processes in these multilayer structures . joule self - heating of a static current - density filament may lead to the translation instability and the onset of thermally driven self - motion . this may occur in a wide class of semiconductor devices whose bistability is caused by impact ionization because impact ionization coefficients decrease with temperature . the eigenvalue of the respective translation mode , which is zero when heating is neglected , becomes positive due to the suppressive effect of temperature on the electron transport in the cathode - anode direction . increments of the translation mode are found for the limiting cases of weak ( [ increments1 ] ) and strong ( [ increments2 ] ) heat diffusion . in both cases the instability threshold ( [ stab1],[stab2 ] ) is controlled by the thermal relaxation time @xmath22 and is directly proportional to @xmath135 . it scales as @xmath145 with increase of the thermal diffusion length @xmath23 . the author is grateful to a. alekseev for critical reading of the manuscript and the hospitality at the mathematical department of the university of geneva and to d. pogany for helpful discussions . this work has been supported by the swiss national science foundation . to indentify the physical branch of the solution of eq.([characteristic1 ] ) , we note that for @xmath98 this equation becomes @xmath191 smooth solution of this quadratic equation @xmath192 for @xmath99 tends to the piecewise linear dependence given by eq.([increments1 ] ) . note the similarity of eq.([appendix1],[appendix2 ] ) and eq.(9 ) in ref .. d. pogany , s. bychikhin , e. gornik , m. denison , n. jensen , g. groos , and m. stecher , _ moving current filaments in esd protection devices and their relation to electrical characteristics _ irps03 symp . , dallas , usa , 2003 , pp.241 - 248 m. denison , m. blaho , d. silber , p. rodin , d. pogany , m. stecher , and e. gornik , _ moving current filaments in integrated dmos transistors under short current stress _ , ieee transactions on electron devices , 2004 , in print . d. pogany , s. buchkihin , m. denison , p. rodin , n. jensen , g. groos , m. stecher and e. gornik , _ thermally - driven motion of current filaments in esd protection devices _ , solid state electronics , submitted . note that for neumann boundary conditions imposed on the activator @xmath3 , the functions @xmath61 and @xmath60 satisfy neumann and dirichlet boundary conditions , respectively , and therefore do not exactly coincide @xcite . this difference becomes important when @xmath194 is comparable to the filament size . then the eigenvalue @xmath195 becomes positive refelecting the attractive effect of boundaries on the filament . this effect decreases exponentially with @xmath194 and is not considered here .

we perform an analytical investigation of the bifurcation from static to traveling current density filaments in a bistable semiconductor structure with s - shaped current - voltage characteristic . joule self - heating of a semiconductor structure and the effect of temperature on electron transport are consistently taken into account in the framework of a generic reaction - diffusion model with global coupling . it is shown that the self - heating is capable to induce translation instability which leads to spontaneous onset of lateral self - motion of the filament along the structure . this may occur in a wide class of semiconductor structures whose bistability is caused by impact ionization due to the negative effect of temperature on the impact ionization rate . the increment of the translation mode and the instability threshold are determined analytically .

high temperature superconductivity ( hts ) in the quasi - two - dimensional cuprates is regarded as a fundamental phenomenon because of a number of reasons@xcite . we name just a few here . first , by doping the system with holes ( cf . fig . [ fig:0 ] ) , a series of quantum phase transitions appears , starting from an antiferromagnetic mott - hubbard insulator ( afi ) for the doping @xmath4 @xcite , through the hts phase ( often mixed with other phases up to an almost optimal doping@xcite ) , to the normal fermi - liquid - like state for @xmath5 @xcite . on microscopic level , in the high-@xmath3 regime hts disappears , most likely by a pair - correlation dilution in real space concomitant with an increased single - particle hopping via hole states . second , when the doping is low , the pairing also weakens and the non - bardeen - cooper - schrieffer ( non - bcs ) character of hts shows up @xcite in the form of the kinetic energy gain at the transition , which exemplifies the fact that the electronic - correlation effects are the strongest there . third , the electronic spectrum in the nodal direction ( @xmath6 in the two - dimensional brillouin zone ) exhibits a universal character@xcite . namely , in spite of changing the carrier concentration by doping ( which normally should lead to the corresponding changes in the fermi - surface volume ) , the value of the fermi velocity in the nodal direction remains almost unchanged in the whole doping range , where various phases such as superconducting , magnetically or charge - ordered can appear . fourth , the effective mass in the nodal direction also exhibits a universal behavior@xcite . these crucial features are regarded as representative to all the cuprate superconductors and our principal aim here is to address these and related properties in a fully quantitative manner . it is accepted that the coper - oxide ( cuo@xmath7 ) planes which appear in the crystal structure of hts are instrumental for achieving a stable paired phase@xcite . that is why the theoretical analysis of the cuprates often limits to models which describe a single cuo@xmath7@xcite plane . within such an approach one can eliminate the oxygen degrees - of - freedom via the zhang - rice singlet hypothesis @xcite or by perturbation expansion@xcite , which leads to an effective single - band model of correlated @xmath8 electrons due to cu atoms on a square lattice ( cf . one of the canonical models for the description within the paradigm of strong correlations is the t - j model,@xcite in which hts appears in the range @xmath9 in a natural manner already within the _ renormalized mean field theory _ rmft@xcite , also with the so - called _ statistical consistency constraints _ included explicitly ( sga method @xcite ) . the rmft approach in the sga version can be related directly to the slave - boson method @xcite ( for review see refs . ) . however , within the gutzwiller - type approach no extra bose fields are required , as the interelectronic correlations are evaluated directly . another model which is used in the theoretical analysis of hts is the single - band hubbard model which however requires more sophisticated calculation methods than rmft to obtain the paired phase stability . the difference between the approach based on the @xmath0-@xmath1 model and the one that starts from the hubbard model is that in the former case the intersite pairing corrections are included already via kinetic exchange whereas in the latter model one has to introduce them by including correlations beyond rmft , as discussed also below . recently , the full gutzwiller wave - function ( gwf ) solution for the superconducting state for both the @xmath0-@xmath1 @xcite and the hubbard@xcite models have been reported , in which rmft ( in the sga form ) , appears as the zeroth- order approximation to the full solution . within this approach one can track down the evolution of the results , by using the so - called diagrammatic expansion method@xcite ( de - gwf ) , starting from the mean - field theory as the zeroth order result and proceed with incorporating systematically the nonlocal correlations of increased range in higher orders . in such a manner , the exact gwf description is approached asymptotically step by step . here we apply the gwf solution to analyze the current approaches of strongly correlated electrons and single out the so - called @xmath0-@xmath1-@xmath2 model which may be regarded as an extended @xmath0-@xmath1 model with a relatively strong kinetic exchange and the direct coulomb interactions included at the same time . such combination of seemingly excluding each other processes requires a brief elaboration provided in the appendix . however , one should note st the start , that as the exchange interactions are coming mainly from the interband @xmath10-@xmath11 processes , they are related only indirectly to the split - hubbard - subband structure of 3@xmath10 states due to copper@xcite . as shown earlier , the @xmath0-@xmath1-@xmath2 model description leads to the antiferromagnetic ( af ) phase stability for @xmath12@xcite , which is in rough agreement with experiment@xcite . the appearance of both the af exchange interaction and the direct coulomb interaction within such approach brings into mind the competition between the spin - density - wave phase and the charge - density wave phase , the latter of which has been discovered in the cuprates recently@xcite . with the de - gwf solution we not only reproduce the results of the variational quantum monte carlo calculations @xcite , sometimes with a better accuracy , but also carry out calculations for infinite systems within a reasonable computing time . this last factor allowed us to test a number of theoretical models ( @xmath0-@xmath1 , @xmath0-@xmath1-@xmath2 , @xmath0-@xmath1-@xmath2-@xmath13 , hubbard ) and single out the one which reproduces quantitatively the principal experimental data . in brief , the principal aim of this paper is to confront the results obtained for the @xmath0-@xmath1-@xmath2 and related models with the experimental data for the hts state in a proper quantitative manner . explicitly , our purpose here is threefold : * ( i ) * not only to make a detailed comparison of selected experiments with theory , but first and foremost , to single out the universal characteristics such as fermi velocity @xmath14 , effective mass @xmath15 , fermi wave vector @xmath16 , and the non - bcs feature of the pairing , * ( ii ) * characterize whole class of theoretical single - band models based on strong correlations among the electrons and single out the one that allows for a quantitative predictions of selected dynamic properties ( at least within the de - gwf solution ) , and * ( iii ) * to demonstrate the indispensability of the approach going beyond any current mean field approach ( rmft ) on the example of de - gwf . from the formal point of view , we have reanalyzed the origin of the @xmath0-@xmath1 model@xcite . namely , since the principal contribution to the antiferromagnetic exchange @xmath1 comes from superexchange via @xmath17 states and the value of hubbard interaction @xmath2 to the bare bandwidth is not too high , @xmath18 , we have extended the concept of @xmath0-@xmath1 model by incorporating expilictly the coulomb interaction , allowing a small number of double occupancies , in addition to having a rather high value of @xmath1 what leads to the effective single - band model in the @xmath0-@xmath1-@xmath2 or even even @xmath0-@xmath1-@xmath2-@xmath13 form . the relevant microscopic interaction parameters of the starting model are schematically defined in fig . [ fig:0 ] . the intersite coulomb interaction @xmath19 has been disregarded in the main text , but its role is elaborated briefly in the concluding section . here , we concentrate only on the quantitative analysis of the pure superconducting ( sc ) phase . important issues which also can be tackled within the present approach , i.e. , the description of electrodynamics in an applied magnetic field , are listed at the end . the starting model is of the form of the extended hubbard hamiltonian with the antiferromagnetic exchange interaction@xcite @xmath20 where the primed summation means that @xmath21 and @xmath22 means that only pairs of nearest neighbors are taken into account . the first two terms represent the hubbard model ( consisting of the hopping and the intrasite repulsion terms , respectively ) , the third expresses the intersite coulomb interaction ( the part @xmath23 comes from the full expression for the exchange operator ) , and the last accounts for the antiferromagnetic exchange interaction ( in the strict one - band representation of correlated electrons the exchange integral is @xmath24 @xcite ) . in the bulk of the paper we have disregarded the third term , as it does not influence much the quality of the comparison with the discussed here experimental data ( see the discussion at the end of the paper ) . we should note that such a model has been introduced formally in ref . as interpolating between the hubbard- and @xmath0-@xmath1-model limits . the general form of the single - band model with all two - site interactions would require the inclusion of the pair - hopping and the so - called correlated hopping terms@xcite . however , those two terms should be small as @xmath2 is relatively large ; an additional check on their very small relevance , as well as of the three - site terms@xcite , eventually comes from the quality of our quantitative description of selected experimental results . the main task within our approach is to calculate the ground state energy and its properties for the full gutzwiller - wave - function solution . this is carried out in a direct analogy to an earlier treatment of both the hubbard@xcite and the t - j models@xcite . explicitly , the ground state energy per lattice site is of the form @xmath25 where @xmath26 is the number of lattice sites , @xmath27 is the gutzwiller - type wave function , defined with the help of the operator @xmath28 and the normalized uncorrelated state , @xmath29 ( taken as the uncorrelated paired state with nonzero anomalous real space average @xmath30 , for @xmath21 , when considering the sc phase ) . the @xmath28 operator is of the form @xmath31 where the variational parameters @xmath32 correspond to four states from the local basis @xmath33 , respectively . in our analysis we assume spatial homogeneity , so @xmath34 . moreover , we also limit to the spin - isotropic case , which means that @xmath35 . within the diagrammatic expansion method@xcite one imposes the condition that @xmath36 where @xmath37 is yet another variational parameter and @xmath38 , @xmath39 , with @xmath40 . all the @xmath41 parameters can be expressed with the use of the @xmath37 parameter due to ( [ eq : constraint ] ) and ( [ eq : gutz_operator ] ) , which means that we are left with only one variational parameter in the considered case . the expectation values of the consecutive terms which appear in the @xmath0-@xmath1-@xmath2 hamiltonian ( [ eq : h_start ] ) ( we omit the intersite coulomb repulsion term here ) can be expressed in the form of the power series @xmath42 where @xmath43 , @xmath44 , and @xmath45 . the primmed summation on the right hand side has the restrictions @xmath46 , @xmath47 for all @xmath11 , @xmath48 . next , by using the wicks theorem the non - correlated averages in eqs . ( [ eq : expectation_val_terms ] ) can be expressed in terms of @xmath49 and @xmath50 . due to the fact that the gutzwiller operator may change the norm of the noncorrelated wave function , one has to divide the above expressions by @xmath51 , while calculating the ground state energy . it is convenient to use the linked - cluster theorem@xcite to simplify the expressions obtained in the described manner . such approach allows us to evaluate the ground state energy to a sufficient accuracy by including the first @xmath52 orders of the diagrammatic expansion@xcite , depending on the model at hand . from the minimization condition of the ground state energy ( [ eq : ground_state_energy ] ) one can derive the effective hamiltonian , which for the case of pure superconducting phase has the form @xmath53 where the effective hopping and the effective superconducting gap parameters are defined through the corresponding relations @xmath54 for @xmath55 , the @xmath56 has an interpretation of an effective chemical potential . the expression for ground state energy functional per atomic site @xmath57 ( where @xmath58 and @xmath59 are the chemical potential and the number of particles per lattice site determined in the correlated state , respectively ) is obtained via the corresponding diagrammatic expansions of all the averages contained in it . it should be noted that within this approach one can also calculate the correlated superconducting gap parameter @xmath60 , which is analyzed in the main text . namely , the correlated and the effective gaps are expressed through the uncorrelated quantities @xmath61 , @xmath62 , and the variational parameter @xmath37 . in result , one has to solve a set of integral equations for @xmath61 , @xmath63 , @xmath58 , and @xmath37 , from which the electronic structure , the correlated gap @xmath64 , and the ground state energy are explicitly evaluated for given set of parameters @xmath65 , @xmath2 , @xmath1 , and the band filling @xmath66 . some methodological remarks are in place here . namely , the application of the wicks theorem allows us to express the elements of the sums in ( [ eq : expectation_val_terms ] ) as diagrams with the lattice sites playing the role of vertices and @xmath61 , @xmath62 being the edges connecting those vertices . in the obtained diagrammatic sums the site indices @xmath67 run over all the lattice sites . however , the @xmath61 and @xmath62 with significantly large distance @xmath68 lead to small contributions@xcite . therefore , during the calculations one may limit to terms with lines that correspond to distances smaller than some @xmath69 . moreover , it is convenient to introduce additional condition that a given diagram contribution is included in the calculations if the sum of all the lines length ( in the manhattan metrics ) which correspond to this diagram is smaller than some specified value @xmath70 . furthermore , beginning from some particular value of the expansion order @xmath71 one can neglect the terms of the summation in eqs . ( [ eq : expectation_val_terms ] ) . in such situation one includes diagrams with number of vertices up to @xmath72 ( @xmath73 ) corresponding to one- ( two- ) site terms of the hamiltonian ( [ eq : h_start ] ) . the order of the approach is then equal to @xmath74 . in practice , it is convenient to include diagrams with number of lines up to some particular value , @xmath75 . it should be noted that including only the zeroth - order diagrams leads to calculations which are equivalent to the sga version of the renormalized mean - field theory . all the presented results have been obtained for the calculation parameters set to @xmath76 , @xmath77 , and @xmath78 . the value of @xmath78 means that we include diagrams up to the fifth order and some additional diagrams which are of the sixth order . the set of integral equations for @xmath61 , @xmath62 , @xmath58 , and @xmath37 has been solved with the use of gsl numerical library with the typical accuracy set to @xmath79 . in our analysis we take into account both the nearest - neighbor and the next - nearest - neighbor hoppings , with the respective hopping integrals set to @xmath80 ev ( the value @xmath81 is taken as the energy unit , if not specified explicitly ) and @xmath82 . the intersite exchange integral is assumed as nonzero only for the nearest - neighbors @xmath83 , @xmath84 . below we analyze concrete measurable quantities and compare them o experiment in a quantitative manner . to set the stage - reference point of our analysis in fig . [ fig:1 ] we show the dispersion relation obtained experimentally for la@xmath85sr@xmath86cuo@xmath87 close to the fermi energy according to refs.@xcite . the universal fermi velocity @xmath14 in the nodal direction is estimated from the data by taking the slopes of the extreme curves as marked by the straight lines , what leads to the average result @xmath88 ev@xmath89(in these units @xmath90 , in physical units @xmath91 cm / s ) . this value is in very good agreement with the one determined theoretically here ( see below ) @xmath92 ev , what illustrates the quality of our approach , the results of which we discuss in detail next . to single out the model which describes properly the high temperature superconductivity , we have analyzed the hubbard , @xmath0-@xmath1 , @xmath0-@xmath1-@xmath2 , and @xmath0-@xmath1-@xmath2-@xmath13 models separately , all within the full gutzwiller wave function solution ( the parameters are visualized in fig . [ fig:0 ] ) . as we show below , the @xmath0-@xmath1-@xmath2 model reproduces the universal characteristics quantitatively . in figs . [ fig:2 ] a - c and [ fig:2_1 ] a , b we discuss one of the principal non - bcs features of the sc state , namely the kinetic energy gain in the superconducting state with respect to the normal paramagnetic ( pm ) state@xcite . this gain is defined as @xmath93 where the kinetic energy difference is taken between the sc and pm states . subscript g means that the average @xmath94 is taken in the gutzwiller state @xmath95 . note that the condensation energy , corresponding to the total ground - state - energy difference , @xmath96 , is always negative for the sc phase to be stable . in fig . [ fig:2]a we display the results for the hubbard model concerning the stability of the @xmath10-wave sc with respect to the normal ( pm ) state on the plane doping @xmath3 - intraatomic coulomb repulsion @xmath2 . the bcs - like ( with @xmath97 ) and non - bcs ( with @xmath98 ) regimes are separated in this case by an almost vertical dashed line which illustrates the fact that the latter regime appears as stable if only @xmath99 . the optimal doping ( i.e. , the doping with the maximal value of the transition temperature @xmath100 ) is denoted by @xmath101 and for a given @xmath2 is determined theoretically by taking the value of the doping which corresponds to maximal correlated gap , @xmath102 for @xmath103 ( where @xmath104 is the lattice constant ) . for comparison , in fig . [ fig:2 ] b and c the results for @xmath105 and the magnitude of the gap are displayed vs @xmath3 for the case of @xmath0-@xmath1 model . as shown in fig . [ fig:2]c , the non - bcs ( @xmath105<0 ) state appears only close to half filling for this model . however , it should be noted that the result differs from those obtained within the cluster dmft @xcite . as one can see , the decreasing of the value of @xmath1 leads to the appearance of the non - bcs behavior for slightly larger dopings , @xmath3 . nonetheless , it is impossible to fit the experimental data@xcite with a reasonable value of @xmath1 . one should note that for @xmath106 and @xmath107 the non - bcs behaviour appears in the whole doping range of the paired state stability , as we show at the end of this section ( cf . [ fig:4]b ) . it would be important to carry out a detailed comparison between the cdmft @xcite results and those presented here . note that none of the results shown in figs . [ fig:2]a - c do reflect the proper behavior of the experimental data , according to which the non - bcs behavior appears up to almost optimal doping@xcite ( as we also show explicitly below ) . in fig . [ fig:2_1]a and b we exhibit the phase diagram for the @xmath0-@xmath1-@xmath2 model for two values of the exchange integral , @xmath108 and @xmath109 , respectively . as can be seen , by including both @xmath2 and @xmath1 simultaneously one obtains the transition from the non - bcs to the bcs - like regime very close to the optimal doping ( @xmath110 ) for proper values of the model parameters . moreover , for @xmath109 the non - bcs region appears only up to the optimally doped case . the actual behavior of the data concerning the non - bcs regime appearance@xcite is displayed in fig . [ fig:3]a , where the blue and red continuous lines represent the gwf solution for @xmath0-@xmath1-@xmath2 model for ( @xmath109 , @xmath111 ) and ( @xmath112 , @xmath113 ) , respectively , whereas the experimental data are taken from ref.@xcite . for the sake of comparison , we plot the corresponding results ( the full gwf solution ) obtained for the @xmath0-@xmath1 model ( dot - dashed line ) and those for the @xmath0-@xmath1-@xmath2 model within the sga method ( dashed line ) , which is a more sophisticated form of the rmft . as one can see , we have obtained a good agreement with the experiment for the case of the @xmath0-@xmath1-@xmath2 model only for the solution going beyond the rmft method . in fig . [ fig:3]b and c we present , respectively , the values of the correlated real - space gap @xmath64 and the condensation energy @xmath114 for all the approaches considered in fig . [ fig:3]a and with the same values of respective parameters characterized by the corresponding colors of the curves . the superconducting state with the gap magnitude @xmath115 ( @xmath116 ) persists up to the doping @xmath117 , which is still substantially larger than the observed value @xmath118 . the inclusion of a weak intersite coulomb interaction ( @xmath119 ) diminishes @xmath120 to the experimental value . however , the influence of the last factor must be discussed in conjunction with a detailed analysis of other phases @xcite as such investigation involves a delicate balance of multiple coexisting orderings ( ferromagnetism , charge - density wave ) . in fig . [ fig:3_1 ] we plot the doping dependence of the fermi velocity in the nodal direction for the case of the @xmath0-@xmath1-@xmath2 model ( blue and red solid lines ) , as well as the results coming from either the full solution of the @xmath0-@xmath1 model ( dot - dashed line ) and from the renormalized mean - field ( sga ) solution of the @xmath0-@xmath1-@xmath2 model ( dashed line ) . again , only the full gwf solution of the @xmath0-@xmath1-@xmath2 model represents quantitatively the data trend for la@xmath121sr@xmath122cuo@xmath87 ( lsco)@xcite and bi@xmath7sr@xmath7cacu@xmath7o@xmath123 ( bscco)@xcite , though the results of gwf and sga coalesce in the overdoped region , which can be regarded as a universal bcs - like limit . for completeness , we have added few known points for the ybco@xcite , as marked by green crosses in the figure . the data for ybco and bscco are scarce , but the values are still close to those for lsco illustrating the universality of the @xmath14 value . furthermore , we fit a line @xmath124 to our results for lsco , to obtain the overall value @xmath125 ev , provided already in fig . [ fig:1 ] which agrees also very good with the value @xmath126ev@xmath89 obtained from independent experiments@xcite . these two sets of data are not only consistent with each other but also provide a strong support for the interpretation of the @xmath14 universality . note that the fits in figs . [ fig:3]a and [ fig:3_1 ] for lsco have been carried out for the same set of the parameters : @xmath80ev , @xmath82 , @xmath127 , @xmath128 ( blue solid lines ) . from the above results concerning @xmath14 independence of @xmath3 one can draw a very important conclusion . namely , the electronic structure in the nodal direction has a universal character in the sense that it survives the effect of the shrinking of the fermi surface with the diminishing carrier ( hole ) concentration . note also that the value of @xmath14 is the same , independently of the circumstance that other phases or pseudogap may appear in the system . thus , these subsidiary phenomena must also have a gap node in that direction , in which @xmath14 has been determined , so they do not influence directly the dispersion - relation gradient at @xmath129 . in fig . [ fig:35]a we provide a direct comparison of the experimentally determined@xcite value of the fermi wave vector @xmath130 ( in units of @xmath131 ) , with the theoretical results : gwf ( red solid line ) and sga ( dashed line ) . both of the approaches provide a correct trend , with a slight systematic deviation for @xmath132 with the gwf results being closer to the experiment . in fig . [ fig:35]b we present the calculated effective mass enhancement in the nodal direction by using the full gwf solution and the sga approximation ( red solid line and gray dashed line , respectively ) both as a function of doping in comparison with the corresponding values for lsco ( blue dots ) and ybco ( green dots ) measured by a combination of dc transport and infrared spectroscopy ( taken from ref . ) . one should note that the fermi velocity and the fermi wave vector are in direct relation to the effective mass through the relation @xmath133 , which allows us to determine the dynamical value of @xmath15 ( black inverted triangles ) by using arpes measurements of @xmath16 ( taken from ref . ) and @xmath14 ( taken from ref . ) . note the differences between the two experimental data sets for @xmath15 corresponding to lsco ( blue dots and black inverted triangles ) . nevertheless , one universal feature of the results presented in fig . [ fig:35]b is clearly visible . namely , the effective mass in the nodal direction is almost constant , and if we ignore the upper data set , the value is @xmath134 , which is in very good agreement with our theoretical results within the gwf solution for the @xmath0-@xmath1-@xmath2 model . this value corresponds to the maximal value of @xmath135 determined recently for ybco@xcite , where its distinct non - universal dependence has been observed . the question arises as to what extent the dome - like behavior shown in ref . can be related to charge - density - wave evolution in strong applied field . we have discussed already that the gain in the hopping ( kinetic ) energy is one of the crucial features differentiating between real - space - pairing models and singling out the @xmath0-@xmath1-@xmath2 model as the one that leads to a better agreement with experiment . however , according to the cdmft calculations@xcite also the @xmath0-@xmath1 model gives some similar results in this respect ( although they have not compared their results quantitatively to experiment ) . the agreement shown by us ( cf . figs . [ fig:3 ] , [ fig:3_1 ] , [ fig:35 ] ) is achieved only if the high - energy scale ( with @xmath136 ev ) , which is about three times larger than the bare bandwidth ( @xmath137 ev ) , is included in the analysis . to illustrate the role of such a high - energy resonant level , located at @xmath138 ev , we have plotted in fig . [ fig:4]a the value of @xmath64 and @xmath139 , both as a function of @xmath2 . the small value of @xmath140 , speaks in favor of the interpretation that the states in the upper hubbard subband may play minor but still relevant role of high - energy resonant states . this circumstance can be put in accord with the canonical approach based on the split hubbard subbands which are reproduced within the three band model - the original model describing the cu - o plane , as discussed in appendix . in fig . [ fig:4]b we show the doping dependence of the variational parameter @xmath37 , which is introduced in the constraint ( [ eq : constraint ] ) , also for the case of the @xmath0-@xmath1-@xmath2 model . for the half - filled situation we obtain the value @xmath141 , which corresponds to no double occupancy , in spite of having a finite value of the hubbard @xmath2 . this particular value of @xmath37 results from the fact that for the case with @xmath107 we have @xmath142 which leads directly to the relation @xmath143 ( cf . section model and method as well as ref . ) . hence , the @xmath0-@xmath1-@xmath2 both in the @xmath144 limit and for the half - filled case with the finite @xmath2 leads to the results equivalent to the one obtained for the @xmath0-@xmath1 model . in fig . [ fig:4]c we provide @xmath105 vs @xmath3 for the limiting case @xmath106 and @xmath145 , which may be regarded as the @xmath144 limit of both the hubbard and the @xmath0-@xmath1 models . one can see that even though the general shape of the curve in fig . [ fig:4]c is the same as that obtained for the @xmath0-@xmath1-@xmath2 model ( cf . [ fig:3]c ) , the corresponding values of @xmath146 are smaller by at least an order of magnitude . therefore , only by combining the two factors , nonzero @xmath147 ( finite @xmath2 ) and a relatively large value of @xmath1 , one can bring the theory in the quantitative accord with experiment , at least within the gutzwiller wave function solution . this required a generalization of the ideas of kinetic exchange as it comes out from a direct perturbation expansion of the hubbard model@xcite , as mentioned above . the fundamental question concerning the model is whether other methods of approach ( vmc , dmft and others ) can be applied to it and confirm the presented here results obtained within the de - gwf method . the affirmative answer to this question would constitute , in our view , a basis for comprehensive treatment of the pairing as applied to high temperature superconductors and other strongly correlated systems . the results presented in figs . [ fig:1 ] - [ fig:35 ] provide a consistent analysis for the same set of model parameters of the principal experimental properties of the cuprates within the combined concepts of real space pairing and strong interelectronic correlations . in carrying out our analysis we had to go beyond the renormalized mean field theory ( even in its statistically consistent version , sga@xcite ) , i.e. , discuss the results within the full gutzwiller wave function solution ( gwf ) to a relatively high order of the diagrammatic expansion . in particular , we have explained here the following ground - state characteristics : * ( i ) * the doping ( @xmath3 ) independence of the fermi velocity @xmath14 in the nodal direction , * ( ii ) * the kinetic energy gain in the sc phase @xmath105 , one of the main non - bcs features , * ( iii ) * the optimal doping value @xmath148 , * ( iv ) * the upper critical concentration for disappearance of the hts state , @xmath149 , and * ( v ) * the doping dependence of the fermi wave vector , @xmath150 . additionally , we have extracted the @xmath3 dependence of effective mass enhancement from the experimental data concerning @xmath150 and @xmath151 and have shown that @xmath152 agrees well with that obtained theoretically , as well as that determined from an independent experiments . the @xmath0-@xmath1-@xmath2 model taken at the start requires a slight modification of our thinking about hts as doped mott insulators in terms of either the hubbard or the original @xmath0-@xmath1 models @xcite . in this respect , one formal point of the model should be noted here . namely , the antiferromagnetic exchange is quite strong and must be coming from the @xmath153 superexchange via the antibonding @xmath154 states due to oxygen , as stated many times earlier @xcite . in effect , as the fitting to the experimental data provides us a posteriori with the hubbard interaction to the bare band - width ratio @xmath155 , the electronic correlations in the effective narrow band may not be regarded as extremely strong , particularly for @xmath156 , what results also in having a small but relevant double occupancy probability @xmath140 . the presence of the hubbard interaction term introduces in an explicit form the high energy scale @xmath157 ev to the problem , what results in comparable values of the effective coulomb energy @xmath158 mev and the exchange energy @xmath159 mev . moreover , the kinetic energy in the pm state , is also of the same order , @xmath160 mev for @xmath161 , constituting altogether a truly correlated state , in which all the three factors play a role . in connection with taking finite @xmath2 value it should be noted that the holon - doublon correction to the gutzwiller wave - function have also been considered @xcite . it would be interesting to see the connection between that extension and our approach . in our considerations we have disregarded the intersite coulomb repulsion ( the third term of eq . [ eq : h_start ] ) ) , as it does not influence much the quality of the comparison with the discussed here experimental data . explicitly , the lsco data displayed in figs . [ fig:3]a and [ fig:3_1 ] can be also fitted with the set of parameters : @xmath80ev , @xmath162 , @xmath163 , @xmath164 , @xmath165 , i.e. with @xmath166 . in effect , @xmath167 is small and can safely be disregarded here . however , the role of @xmath13 may become important when charge- and spin - density - wave states are included , but that requires a separate analysis@xcite . we have not addressed at all the system thermodynamical properties . the extension to the temperature @xmath168 is indispensable as the next step . in this respect , particularly important is the question of the pseudogap appearance@xcite . it is intriguing to ask whether the pseudogap is partly connected with the evolution of our effective gap @xmath169 in the antinodal direction or is it due to a different physical mechanism@xcite . a possible connection between the effective gap and the measured gap in the antinodal direction is supported by the intriguing coincidence that both of them increase with the decreasing doping@xcite . a similar behavior has already been obtained within sga by taking the bare ( not gutzwiller - projected ) value of the gap magnitude and fitting it to the experiment@xcite . furthermore , the appearance of other phases , such as spin- and charge - density - wave states on the superconducting phase diagram depicted in fig . [ fig:2_1 ] should be treated separately , together with singling out the role of the intersite coulomb interaction @xcite . the consistent scheme of analyzing concrete , though selected data for high-@xmath170 sc phase is not the last word by any means , also due to the following reasons . it would be interesting to compare the present results with those of other methods , which also go beyond the renormalized mean field theory . for example , an application of the plaquette or cluster dynamic mean - field theory@xcite to the present model could be of principal importance as an independent checkout on the validity of higher order corrections to rmft . furthermore , an extension of our approach to the situation with nonzero applied magnetic field would provide additional physical properties ( e.g. , doping dependence of the penetration depth ) for a further quantitative testing of the present approach . we should be able to see progress along these lines in the near future . the authors are grateful for the financial support of the national science centre ( ncn ) through grant maestro , no . dec-2012/04/a / st3/00342 . the discussions with profs . dirk van der marel from universit de geneve , adam kamiski from the iowa state university and the ames lab . , iowa , and alexander kordyuk from the national academy of ukraine , were useful and enlightening . we would like to estimate the physical relevance of the considered here @xmath0-@xmath1-@xmath2 model . in the canonically transformed extended hubbard model@xcite the antiferromagnetic exchange interaction is of the form @xmath171 and therefore no hubbard extra term should appear@xcite , if we are in the strong - correlation limit @xmath172 ( not only @xmath173 ) . namely , the contribution to the @xmath26-particle wave function coming from double occupancies is of the order of @xmath174@xcite . before discussing the application of that limit in real calculations , let us estimate its value by taking the standard microscopic - parameter : @xmath175ev , @xmath176ev , and @xmath177 . when neglecting @xmath13 in above formula for @xmath178 we obtain the value of @xmath179k at most . if the bare parameter @xmath13 is taken as @xmath180 ( maximum ) , then the value of @xmath1 increases by @xmath181 , which is still much lower than the typical value of measured @xmath182ev@xmath183k in the insulating phase@xcite ( note that here the values of @xmath1 are @xmath184 of those for the full exchange as there is no factor @xmath184 before the last term in ( [ eq : h_start ] ) ) . on the other hand , the bare bandwidth of the planar states is @xmath185ev@xmath186ev . therefore , the @xmath187 ratio is in the interval @xmath188 , which is not in the asymptotic limit of being @xmath189 . hence , one may expect that the double occupancy probability is not exactly vanishing , particularly for @xmath156 as then the admixture of double occupancy to the single - particle state is of the order@xcite of @xmath190 . in our calculations ( cf . [ fig:4 ] ) @xmath191 for @xmath161 and @xmath192 . such a small value does not influence at all the spin magnitude in the mott insulating state , since then @xmath193@xcite and the zero - point spin fluctuations are much more important . after mentioning the relevance of the hubbard term , the basic question still remains as to what is the dominant contribution to @xmath1 . as said earlier , this is due to the superexchange@xcite via @xmath11 orbitals with inclusion of the fact that hts are charge transfer insulators with the corresponding gap @xmath194ev and the @xmath195 hybridization magnitude @xmath196ev , as well as the @xmath195 coulomb interaction @xmath197 ev . in effect , the nearest neighbors superexchange can be estimated as@xcite @xmath198 a value close to that determined experimentally@xcite . this reasoning provides a direct support for the effective value of @xmath1 as not coming from the large-@xmath2 expansion of the hubbard model@xcite . one should note that the mechanism introduces also the kondo - type coupling between the @xmath11 holes and @xmath10 electrons with the corresponding kondo exchange integral @xmath199 this coupling causes a bound configuration of the hole and @xmath10-electron of cu@xmath200 ion composing the zhang - rice singlet@xcite . also , the hopping amplitude for @xmath10 electron between the nearest neighboring sites @xmath201 can be estimated as @xmath202 taking @xmath203ev and @xmath204ev , we obtain @xmath205ev , also a quite reasonable value . in effect , we have @xmath206 which is a reasonable ratio in view of simplicity of our estimates . in such a reduction procedure to the one - band model the effective hubbard interaction is @xmath207ev , if we take the value @xmath208ev for the original @xmath10 atomic states . in the fitting to experiment we have obtained a slightly larger value of @xmath209ev and @xmath210ev . this brief discussion summarizes the meaning of the starting hamiltonian ( [ eq : h_start])@xcite . the general 3-band model would include a direct single - particle hopping between the oxygen sites @xmath211 . under these circumstances , the kondo - type coupling ( [ eq : kondo ] ) between the oxygen and copper sites must be also taken into account explicitly and we end up in the emery - reiter type of model@xcite in the limit of localized @xmath8 electrons . in this respect , we have selected here the most general one - band model of correlated @xmath10 electrons with the zhang - rice singlet idea implicitly assumed . i. bozovic , g. logvenov , m. a. j. verhoeven , p. caputo , f. goldobin , and t. h. geballe , _ no mixing of superconductivity and antiferromagnetism in a high - temperature superconductor _ , nature * 422 * , 873 ( 2003 ) . v. v. valkov , d. m. dzebisashvili , m. m. korovushkin , and a. f. barabanov , _ stability of the superconducting @xmath216 phase in high - t@xmath212 superconductors with respect to intersite coulomb repulsion of holes at oxygen _ , jetp lett . * 103 * , 385 ( 2016 ) . b. edegger , v. n. muthukumar , and c. gros . , _ gutzwiller - rvb theory of high - temperature superconductivity : results from renormalized mean - field theory and variational monte carlo calculations _ adv . phys . * 56 * , 927 ( 2007 ) . m. abram , j. kaczmarczyk , j. jdrak , and j. spaek , _ d - wave superconductivity and its coexistence with antiferromagnetism in t - j - u model : statistically consistent gutzwiller approach _ , phys . b * 88 * , 094502 ( 2013 ) . r. randeria , r. sensarma , and n. trivedi , _ projected wavefunctions and high - t@xmath215 superconductivity in doped mott insulators _ , in : _ strongly correlated systems : theoretical methods _ , a. avella and f. macini ( springer verlag , berlin , 2012 ) chapter 2 , pp . 29 - 64 . a. a. kordyuk , s. v. borisenko , a. koitzsch , j. fink , m. knupfer , and berger , _ bare electron dispersion from experiment : self - consistent self - energy analysis of the experimental data _ , b * 71 * , 214513 ( 2005 ) . m. hashimoto et al . , _ doping evolution of the electronic structure in the single - layer cuprate bi@xmath7sr@xmath85lacuo@xmath219 . comparison with other single - layered cuprates _ , phys . b * 77 * , 094516 ( 2008 ) . t. yoshida et al . , _ universal versus material - dependent two - gap behaviors of the high-@xmath100 cuprate superconductors : angle - resolved photoemission study of la@xmath85sr@xmath86cuo@xmath87 _ , phys . lett . * 103 * , 037004 ( 2009 ) . m. abram , m. zegrodnik , and j. spaek , _ antiferromagnetism , charge density wave and d - wave superconductivity in the @xmath0-@xmath1-@xmath2-@xmath13 model of correlated electrons _ , arxiv : 1607.05399 ( 2016 ) . j. spaek , _ fermi liquid behavior and the metal - insulator transition of almost localized electrons : a brief theoretical review and an application to v@xmath7o@xmath217 system _ , j. solid state chem . * 88 * , 70 ( 1990 ) .

selected universal experimental properties of high temperature superconducting ( hts ) cuprates have been singled out in the last decade . one of the pivotal challenges in this field is the designation of a consistent interpretation framework within which we can describe quantitatively the universal features of those systems . here we analyze in a detailed manner the principal experimental data and compare them quantitatively with the approach based on a single band of strongly correlated electrons supplemented with strong antiferromagnetic ( super)exchange interaction ( the so - called @xmath0-@xmath1-@xmath2 model ) . the model rationale is provided by estimating its macroscopic parameters on the basis of the 3-band approach for the cu - o plane . we use our original full gutzwiller - wave - function solution by going beyond the renormalized mean field theory ( rmft ) in a systematic manner . our approach reproduces very well the observed hole doping ( @xmath3 ) dependence of the kinetic - energy gain in the superconducting phase , one of the principal non - bardeen - cooper - schrieffer features of the cuprates . the calculated fermi velocity in the nodal direction is practically @xmath3-independent and its universal value agrees very well with that determined experimentally . also , a weak doping dependence of the fermi wave - vector leads to an almost constant value of the effective mass in a pure superconducting phase which is both observed in the experiment and reproduced within our approach . an assessment of the currently used models is carried out and the results of the canonical rmft as a zeroth - order solution are provided for comparison to illustrate the necessity of introduced higher order contributions .

surgical valvotomy was the traditional method of treatment of congenital pulmonary valve stenosis ( pvs ) until 1982 . the technique of balloon pulmonary valvuloplasty was introduced initially by kan et al in 1982 . since then , many other workers have reported successful application of this technique to treat patients with moderate to severe pulmonary valve stenosis[2 , 3 ] . immediate , short and mid term results of bpv have been well documented[47 ] . however , there are limited data on long term outcomes[710 ] . the purpose of this report is to evaluate the results of long term follow up of balloon pulmonary valvuloplasty in 60 children . from june 1998 to january 2012 , 60 patients with moderate to severe pulmonary valve stenosis were considered for balloon pulmonary valvuloplasty . six patients were excluded because of dysplastic pulmonary valve in 4 cases and infundibular spasm and failure to cross the pulmonary valve with balloon catheter in 2 cases . therefore 53 patients ( 28 females , 25 males ) of mansd age 3.22.2 years ( range 0.48 years ) follow up at 24 hours , 3 months , 1 year and yearly ( meansd 7.12.5 years , median : 5.5 years ) thereafter included physical examination and doppler echocardiography . doppler echocardiography assessed the maximum peak instantaneous gradient across the pulmonary valve and pulmonary regurgitation . the procedure : informed consent was obtained from the parent of patients . all procedure was performed under general anesthesia . a 6-french pigtail catheter was inserted with seldinger technique , through the right or left femoral venous sheath into the right size of the heart for right ventriculography . right ventriculogram in anteroposterior ( a ) and left lateral ( b ) views showing severe pulmonary valve stenosis , thickened domed pulmonary valve and post stenosic dilatation of main pulmonary artery the diameter of the orifice and annulus of pulmonary valve was measured from hinge point to hinge point during systole from lateral view of the right ventricular angiogram . the maximal diameter of the tyshak balloon was chosen in accordance with the diameter of pulmonary valve annulus . the diameter of the balloon catheter was 10 - 20% larger than that of the pulmonary valve annulus . 6 french multipurpose a2 ( cordis ) catheter was introduced into the femoral venous sheath and advanced across the pulmonary valve and the tip of the catheter positioned in the distal left or right pulmonary artery branch and then multipurpose catheter was replaced with a tyshak balloon catheter . when the exchange wire was stabilized , balloon catheter was pulled back until the middle portion of the balloon was positioned just across the pulmonary valve . 2 ) . a : left lateral view of a partially inflated balloon catheter positioned across the pulmonary valve . as the balloon b : the balloon waist completely disappeared on the left lateral view , suggesting valvuloplasty had been effective statistical analysis : normally distributed continuous variables were expressed as mean standard deviation ( sd ) . pressure gradients before and immediately after balloon valvuloplasty and at long term follow up were compared by two tailed or paired t - tests . fifty four of sixty patients with an age range of 0.48 years ( meansd 3.22.2 years ) underwent pulmonary balloon valvuloplasty . the mean ( sd ) weight was 12.24.7 kg ( range : 6.324 kg ) . ten cases were infants , and remaining 44 cases were between 1 and 8 years old . the associated defects included : asd in two , patent ductus arteriosus in 3 and left pulmonary artery branch stenosis in one . demographic and catheterization data of patients sd : standard deviation ; pg : pressure gradient ; pv : pulmonary valve ; bbv : before balloon valvuplasty ; iabv : immediate after balloon valvuloplasty ; lfu : late follow up immediate , short , mid - term and long term follow up : the peak to peak systolic pressure gradient across the pulmonary valve was more than 50 mmhg in all patients before procedure . it reduced from 83.2832 ( range : 55170 mmhg ) before bpv to 19.314.2 ( range : 075 mmhg ) immediately after bpv ( p<0.005 ) , to 15.19.5 mmhg ) ( range : 0 - 48 mmhg ) at short term follow up ( defined as three months or less ) ( p<0.001 ) . the maximum peak instantaneous doppler pressure gradient also declined from 15.19.5 at short term to 13.02703 ( range 0 - 36 mmhg at intermediate- term ( as defined 3 months to 1 year ) ( p<0.001 ) and to 12.36.6 mmhg ( range : 0 - 32 ) at long - term follow up ( p=0.02 ) . two ( 3.8% ) of 53 patients had re - stenosis ( defined as a pressure gradient 50 mmhg or more ) at intermediate- term follow up . one of these patients underwent repeat balloon valvuloplasty at an interval of 3 months and one other at 3 years after initial balloon dilatation : peak to peak gradient was reduced from 75 to 42 mmhg and also in other one the peak instantaneous doppler gradient declined from 60 mmhg at midterm to 32 mmhg at long term follow up . there was one immediate death because of cardiac tamponade following rupture of right ventricular outflow tract . two to 12.5 years follow up ( median 5.5 years ) was available in 53 patients . the maximum peak instantaneous pressure gradient across pulmonary valve was 12.36.6 mmhg at long term follow up . it is significantly lower than the gradient seen before balloon dilatation , at short term ( p<0.001 ) and at intermediate pulmonary regurgitation was absent in 33 ( 62.2% ) cases , mild in 18 ( 34% ) and moderate in 2 ( 3.8% ) at short term follow up . incidence of pulmonary regurgitation by doppler echocardiography was lower ( p<0.001 ) at follow up , 20 ( 38% ) cases at short term versus 17 ( 32% ) cases at long term ) . on the basis of absence of right ventricular dilatation and the lack of paradoxical septal motion , surgical or trans - catheter pulmonary valve replacement for treatment of pulmonary regurgitation was not required . this study demonstrates that balloon pulmonary valvuloplasty provides long term relief of stenosis of the pulmonary valve in the majority of patients with moderate to severe pulmonary valve stenosis . a re - stenosis with gradient > 30 mmhg was observed only in 4 ( 7.5% ) patients at short term and in 2 ( 3.8% ) patients at intermediate and long term follow up . actuarial re - intervention free rates were 98% and 96% at intermediate and long- term follow up respectively . therefore in current study incidence of persistent stenosis was low which can be related to the use of large balloon ( 10%-20% ) excess of annulus diameter ) . while the initial recommendations were to use balloons that are 20 - 40% larger than the pulmonary valve annulus , recent reports of pulmonary insufficiency at late follow up , raised concern regarding balloon size . nowadays it is recommended that pediatric cardiologist strives for a balloon / annulus ratio of 1.1 - 1.2 instead of previously recommended 1.2 - 1.4 ratio . use of balloon 1.1 - 1.2 times larger than pulmonary valve annulus may produce optimal result while at the same time may help prevent significant pulmonary insufficiency at late follow up . in our study incidence of pulmonary valve dysplasia was 6.7% that is lower than in the study ( 8% ) by jarrar et al . we observed a further reduction in the total pressure gradient across pulmonary valve at short , intermediate and long term follow up , a finding comparable to other studies that report follow up data[810 , 1315 ] . in our study incidence of pulmonary regurgitation was low ( 38% ) at short term and ( 32% ) at long term follow up . it was 45% in the report by o'connor et al , 80% in the rao et al study and 85% in the mccrindle , et al and 95% in the hatem et al studies . perforation of right ventricular outflow tract was the major complication in one patient with fatal event . this complication is rare and it usually occurs in neonates or infants with critical pulmonary stenosis and hypoplastic pulmonary valve[1921 ] . in our study the patient was an infant with hypoplastic pulmonary valve . in current study rate of major complication ( perforation of rvot ) was 1.9%[19 , 22 ] , while in some studies it was higher ( 7.3%-16.6% ) than in our study , but it was lower in most studies[8 , 12 , 18 , 23 ] . our study shows balloon valvuloplasty is a safe and effective treatment of moderate and severe pulmonary valve stenosis . therefore pbv can be considered as the treatment of choice for children with valvar pulmonary stenosis . howere , longer - term ( 1520 years ) follow up results are unknown . also longer

objectiveimmediate , short and midterm outcome of balloon pulmonary valvuloplasty are well known , but there is limited information on long term results . we report long term results of 213 . 5 years follow up of balloon pulmonary valvuloplasty in children.methodsfrom june 1998 to january 2012 sixty consecutive patients ( 33 females , 27 males ) with moderate to severe valvar pulmonary stenosis ( right ventricular to pulmonary artery pressure gradient greater than 50 mmhg ) were considered for balloon valvuloplasty . the gradient was measured pre and immediately post valvuloplasty at catheterization , and then by echocardiography at follow up . follow up studies were performed 213.5 years ( meansd ; 7.12.5 years , median : 5.5 years ) after procedure , by doppler echocardiography in all patients and catheterization and angiography in two patients.findingsballoon pulmonary valvuloplasty bpv was successful in 53 of 60 ( 88.3% ) patients whereas surgical valvotomy was necessary in 6 to 60 ( 10% ) . there was one immediate death due to perforation of the right ventricular outflow tract . pulmonary valve systolic pressure gradient decreased from 83.332.1 to 19.314.2 mmhg immediately after bpv and to 12.36.6 mmhg at late follow up ( p<0.001 ) . pulmonary insufficiency was noted in 20 ( 38% ) patient at short term , but it was demonstrated in 17 ( 32% ) at late follow up . a second valvuloplasty was performed in two ( 3.8% ) patients presenting with re-stenosis.conclusionthe short , intermediate and long - term outcomes of pulmonary balloon valvuloplasty in children are excellent . therefore it can be considered as the treatment of choice for children with pulmonary valve stenosis .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Spacefaring Priorities for America's Continued Exploration Act'' or the ``SPACE Act''. SEC. 2. FINDINGS. Congress finds the following: (1) Russia is not a reliable partner.--(A) Unless Space Shuttle operations are extended beyond 2010, the United States will be heavily reliant on Russia to supply crew and possibly cargo transport services to the International Space Station during the gap period of 2010 through 2015. There will be no other way to fly our astronauts into space during this period. (B) The United States should not increase its reliance on Russia to transport American astronauts into space, given the increasingly divergent views and posturing from Russia. Russia opposes the United States plan to base an antimissile radar system in the Czech Republic and interceptor missiles in Poland to deal with the threat posed by the Iranian nuclear weapons and missile programs. Russia also suspended its participation in the Conventional Forces in Europe (CFE) treaty, one of the most significant arms control agreements of the Cold War years. Additionally, Russia continues to arm some of America's most hostile adversaries, Iran and Venezuela. Despite United States objections, Russia sold billions of dollars worth of weapons to the regime of Hugo Chavez in 2006. Such meddling is a possible violation of the Monroe Doctrine and a throwback to the Cold War era. Even more troublesome is the Russian history of weapons trading with Iran. Russia has supplied advanced conventional arms technology, missile technology, and nuclear technologies to this very anti-American regime. (2) Russia has abused past nasa cooperation agreements.-- (A) In the late 1990s, Russia fell short in fulfilling its commitment to the International Space Station. (B) The National Aeronautics and Space Administration (in this Act referred to as ``NASA'') was forced to transfer hundreds of millions of dollars to enable the Russians to complete the critical Space Station service module Zvezda, without which the International Space Station could not operate. (C) Russia delayed completion of the Zvezda service module for several years. Under the International Space Station agreement, the Russian government had committed to fund as well as build the Zvezda service module. Subsequent transfers from the United States, in order to complete the module, reflect serious Russian mismanagement in the field of space. (D) In 2000, while Russia was failing to meet its commitment to the International Space Station, Russia was diverting financial and human resources away from fulfilling its International Space Station commitments in order to keep the Russian's Mir Space Station aloft. (E) Russia's past shortcomings in fulfilling commitments to its international space partners should serve as a warning to the United States as we consider increased reliance on Russian space services in the future. It is not prudent for the United States to depend on Russia for access to space given our past experience with this relationship. (3) American space science should not be dependent on russian support.--(A) The United States has already invested billions of dollars in the International Space Station program since its inception. (B) There is much research of great value being conducted in space, and on the International Space Station, that may yield tremendous gains. Research being conducted on the International Space Station may help scientists back on Earth develop medicines to treat diseases and help us better understand the Earth's climate. Many scientists believe that the microgravity environment of space will enable the development of new drugs, vaccines, and other therapies. Equipment on the International Space Station will monitor stratospheric gases, and investigate ozone chemistry. (4) The united states must have assured access to space.-- (A) To ensure that the United States realizes the dividends from the considerable investment we have made in the International Space Station, we need to ensure continued access to space for our astronauts. However, NASA's plan for transport of crew to and from the International Space Station fails to provide necessary redundancies to provide assured access to space. (B) NASA anticipates that the Russian Soyuz spacecraft will be the only vehicle for astronaut crew rotation to the International Space Station after 2010. From 2011 until the planned operation of Orion in 2015, NASA likely has no other option for transporting American astronauts to space other than on Russian vehicles. (C) NASA has conceded that without the Space Shuttle, it will be unable to transport the Alpha Magnetic Spectrometer (AMS) to the International Space Station. Scientists involved in the development of the AMS acknowledge that it will enhance scientific discoveries. While the AMS has cost over $1,500,000,000 to develop and build, NASA has stated that the remaining Space Shuttle manifest does not allow for transport of the AMS and that it will not be an option to retrofit another launch vehicle in order to fly it into space. Only by extending Space Shuttle operations beyond 2010 will NASA be able to transport the AMS to the International Space Station. As long as the AMS meets all required standards to verify its validity and justify its transport on the Space Shuttle, NASA should fulfill its obligation to the Department of Energy and our international partners. (D) In addition, the Japanese Centrifuge Accommodation Module, which can only fly to the International Space Station on the Space Shuttle, will also be unable to reach the Space Station absent extending Space Shuttle operations. (5) A better approach.--(A) Due to NASA's lack of a backup plan for reliance on the Russians for transport of American astronauts to space, the United States needs a better approach. The best approach is the Space Shuttle, a proven, domestic source of space transport for assured access to space, including the International Space Station, for crew and cargo transport. (B) With 2 Shuttle missions per year during the human spaceflight program flight gap between Shuttle and Orion, currently scheduled from 2010 through 2015, we can replace our need to rely on the Russians for crew rotation for the International Space Station. (C) Savings from replacing Russian transport services to the International Space Station with the Space Shuttle would pay for a portion of the costs for flying 2 Space Shuttle missions per year. (D) Only by closing the gap between 2010 and 2015, or until the Orion is operational, will our Nation be able to keep our Nation's highly skilled and critically important spaceworkers and engineers gainfully employed, and mitigate the loss of critical skills. (E) By extending Space Shuttle operations, NASA may realize considerable savings by no longer having to pay retention bonuses to critical space workers. But retention bonuses would not be the only added costs associated with the end of Space Shuttle operations when critical skilled workers leave NASA or its contractors. Recruitment incentives for new workers and contract cost increases could also be incurred by NASA since the majority of the Kennedy Space Center's workforce are contractors. (F) The success of the Constellation program will depend on having the most skilled and experienced workforce possible. The workforce gap, as currently envisioned by NASA, will jeopardize this. NASA has acknowledged that thousands of critical space workers will lose their jobs in the transition from the Space Shuttle to the Constellation program. Continued operation of the Space Shuttle, but on a reduced flight requirement, while also integrating these workers into the Orion program, is the best way to retain many of these critical workers and skill sets. (G) An August 2007 study by the Government Accountability Office, ``NASA Progress Made on Strategic Human Capital Management, but Future Program Challenges Remain,'' stated that ``the agency as a whole faces challenges in recruiting and retaining highly experienced senior-level engineers in certain specialties. NASA's principal workforce challenge will be faced in the transition to the next generation of human space flight systems.''. (H) This Act authorizes for NASA additional funding under section 4 to fully restore the appropriation shortfalls in fiscal years 2007 and 2008 compared to the funds that were authorized for NASA. An additional $1,000,000,000 is authorized in section 4(b) to reimburse NASA for the costs incurred by NASA from the Space Shuttle return-to-flight efforts following the Space Shuttle Columbia disaster. SEC. 3. PROHIBITION ON USE OF RUSSIAN SPACE SERVICES. NASA shall not rely solely on the Russian government for astronaut transport or cargo resupply services. This prohibition does not apply to the current Soyuz emergency escape services for astronauts on the International Space Station. SEC. 4. ADDITIONAL FUNDING FOR NASA. (a) Additional Authorization for Fiscal Year 2007 Shortfall.--There are authorized to be appropriated to NASA $1,648,000,000, 41.6 percent of which shall be for Exploration Systems, and 28.7 percent of which shall be available for Space Operations. (b) Columbia Return-to-Flight.--There are authorized to be appropriated to NASA $1,000,000,000 for emergency funding to reimburse for Columbia return-to-flight costs, of which the Exploration Systems and Space Operations Accounts shall receive funding at the rate proportional to the amounts used to pay the costs associated with the Space Shuttle return-to-flight efforts. (c) Additional Authorization for Fiscal Year 2008 Shortfall.--There are authorized to be appropriated to NASA $1,064,000,000, 41.7 percent of which shall be for Exploration Systems. (d) Preservation of Funding for Programs.--NASA shall not take any funding from its Exploration Systems account or the Constellation program in order to fund the continued operation of the Space Shuttle program as required in this Act. SEC. 5. EXTENDING SPACE SHUTTLE OPERATIONS. (a) Use of Space Shuttle for Access to Space.--NASA shall fly at least 2 Space Shuttle missions per year for crew transport, instead of Russian crew and cargo services, for the period of 2010 through 2015, or until Orion is operational. There are authorized to be appropriated to NASA such sums as may be necessary, in addition to amounts otherwise authorized, to carry out this subsection, including for the production of more external tanks as may be needed. (b) Insufficient Funding.--Except as provided under subsection (c), the requirements of this Act shall have effect only to the extent that sufficient funding is appropriated, as authorized under subsection (a). Sufficient funding is defined as funds required to fully or partially comply with the requirements of this Act. (c) Report to Congress.--NASA shall report to Congress not later than 90 days after the date of enactment of this Act on the specific costs and actions needed to extend the operation of the Space Shuttle in accordance with this Act. (d) Operational Efficiencies.--As soon as possible, but no later than March 31, 2011, NASA shall investigate areas of reduced operations and enhanced cost savings and implement those that do not impinge the safe operation of the Space Shuttle program, including the following: (1) The possible retirement of one Space Shuttle orbiter, leaving 2 to remain operational, in a manner that ensures the safe operation of the Space Shuttle program. (2) Significantly reducing changes to the design of the Space Shuttle orbiters, in a manner that ensures the safe operation of the Space Shuttle program. This shall include changes to the Space Shuttle software systems. (3) Significantly reducing Space Shuttle orbiter configuration operations and payload configuration operations, in a manner that ensures the safe operation of the Space Shuttle program. (4) Maximizing the use of shared personnel between the continued operation of the Space Shuttle and Constellation and other NASA programs. (e) Facilities.--If conflicts arise in NASA's efforts to allocate facilities, personnel, and other resources in order to fly the Space Shuttle as well as continue the development of Constellation, then NASA shall identify in a report to Congress in advance such conflicts, along with recommendations as to how they can be mitigated. SEC. 6. SHUTTLE RECERTIFICATION. Not later than 6 months after the date of enactment of this Act, NASA shall define achievable and attainable requirements for operation of the Space Shuttle program beyond 2010, as recommended by the Columbia Accident Investigation Board. NASA shall transmit these requirements to Congress in the form of a report. NASA shall then immediately begin the process of satisfying these requirements and shall satisfy all requirements no later than March 31, 2010.

Spacefaring Priorities for America's Continued Exploration Act or SPACE Act - Prohibits the National Aeronautics and Space Administration (NASA) from relying solely on the Russian government for astronaut transport or cargo resupply services, except for the current Soyuz emergency escape services for astronauts on the International Space Station. Authorizes appropriations to NASA for: (1) exploration systems; and (2) emergency funding for Columbia return-to-flight costs. Requires NASA to fly at least two space shuttle missions per year for crew transport, instead of Russian crew and cargo services, for the period 2010-2015, or until Orion is operational. Authorizes appropriations to carry out such operations. Requires NASA to report to Congress on the specific costs and actions needed to extend the operation of the space shuttle. Requires NASA, by March 31, 2011, to investigate areas of reduced operations and enhanced cost savings and implement those that do not impinge on the safe operation of the space shuttle program. Directs NASA to define achievable and attainable requirements for the operation of such program beyond 2010, as recommended by the Columbia Accident Investigation Board. Requires: (1) NASA to report to Congress on such requirements; and (2) NASA to immediately begin satisfying those requirements and to satisfy all of them by March 31, 2010.

Image copyright PA Image caption Theresa May signs the letter to the EU confirming the UK's departure Theresa May has signed the letter that will formally begin the UK's departure from the European Union. Giving official notice under Article 50 of the Lisbon Treaty, it will be delivered to European Council president Donald Tusk later. In a statement in the Commons, the prime minister will then tell MPs this marks "the moment for the country to come together". It follows June's referendum which resulted in a vote to leave the EU. Mrs May's letter will be delivered at 12:20 BST on Wednesday by the British ambassador to the EU, Sir Tim Barrow. Image copyright AFP Image caption Sir Tim arrived in Brussels earlier clutching a briefcase containing the Article 50 letter The prime minister, who chaired an hour long cabinet meeting earlier, has left Downing Street to make a statement to MPs confirming the countdown to the UK's departure from the EU is under way. She will promise to "represent every person in the whole United Kingdom" during the negotiations - including EU nationals, whose status after Brexit has yet to be settled. "It is my fierce determination to get the right deal for every single person in this country," she will say. "For, as we face the opportunities ahead of us on this momentous journey, our shared values, interests and ambitions can - and must - bring us together." Attempting to move on from the divisions of June's referendum, Mrs May will add: "We are one great union of people and nations with a proud history and a bright future. "And, now that the decision has been made to leave the EU, it is time to come together." Labour leader Jeremy Corbyn said his party respected the decision to leave the EU and would hold the government to account "every step of the way". He said: "Britain is going to change as a result. The question is how." Mr Corbyn warned it would be "a national failure of historic proportions" if Mrs May does not secure protection for workers' rights. Chancellor Philip Hammond said the triggering of Article 50 was "a pivotal moment for Britain" and insisted the government "will get a deal". But he suggested on BBC Radio 4's Today programme that ministers would be prepared to compromise during the process, adding: "Everybody in the EU and the UK is going to go into this negotiation looking to protect their own interests... "We understand that we can't cherry-pick, we can't have our cake and eat it - that by deciding to leave the EU and negotiate a future relationship with the EU as an independent nation, there will be certain consequences of that and we accept those." He said EU citizens could still move to the UK and have their full rights while the UK remains "full members of the EU for the next two years". But crossbench peer Lord Gus O'Donnell, formerly Britain's top civil servant, likened the triggering of Article 50 to being "in a plane being flown by members of the EU and we're about to jump out and we have got a parachute designed by the people flying the plane - and they have designed it in a way to deter anyone else jumping out". Media playback is unsupported on your device Media caption Brexit divorce: 'Conscious uncoupling' or bitter breakup? Media playback is unsupported on your device Media caption Seven decades of the UK in Europe The PM will be outlining the next steps during a special half hour BBC One interview on Wednesday with Andrew Neil at 19:00 BST on "Britain after Brexit", to mark the triggering of Article 50. On Tuesday night, Mrs May spoke by telephone to Mr Tusk, EU Commission president Jean-Claude Juncker and German Chancellor Angela Merkel. Article 50 gives both sides two years to reach agreement, so unless both sides agree to extend the deadline for talks, the UK will leave on 29 March 2019. Negotiations are expected to begin in mid-May. The UK government says it wants to carry out both separation and trade talks at the same time, but EU chiefs say the two issues must be handled separately. The UK has said it wants an "early agreement" to guarantee the rights of EU citizens living in the UK and those of British nationals living abroad. Other issues which are likely to be discussed are things like cross-border security arrangements, the European Arrest Warrant, moving EU agencies which have their headquarters in the UK and the UK's contribution to pensions of EU civil servants - part of a wider "divorce bill" which some reports have suggested could run to £50bn. Up for discussion Trade: The UK will withdraw from the single market and seek a new customs arrangement and a free trade agreement with the EU The UK will withdraw from the single market and seek a new customs arrangement and a free trade agreement with the EU Expats: The government wants to secure an agreement with European countries "at the earliest opportunity" on the rights of EU nationals in the UK and Britons living in Europe The government wants to secure an agreement with European countries "at the earliest opportunity" on the rights of EU nationals in the UK and Britons living in Europe Brexit bill: The UK government has promised to honour its obligations as it leaves, but has brushed off claims these could run to £50bn The UK government has promised to honour its obligations as it leaves, but has brushed off claims these could run to £50bn Northern Ireland border: Aiming for "as seamless and frictionless a border as possible between Northern Ireland and Ireland" Aiming for "as seamless and frictionless a border as possible between Northern Ireland and Ireland" Sovereignty: Britain will leave the jurisdiction of the European Court of Justice but seek to set up separate resolution mechanisms for things like trade disputes Britain will leave the jurisdiction of the European Court of Justice but seek to set up separate resolution mechanisms for things like trade disputes Security: The UK government has said it wants to continue to cooperate on security and intelligence-sharing The UK government has said it wants to continue to cooperate on security and intelligence-sharing Transitional deal: An interim arrangement may be needed before the final arrangements come into force The Lib Dems claimed Mrs May was "pulling the trigger that will set in motion a chain of events which will change this country forever, and doing so without a proper plan", but the Leave Means Leave campaign congratulated her on sticking to her timetable of invoking Article 50 before the end of March. "Unpatriotic, pro-EU fanatics will continue to try to derail or, at the very least, delay Brexit," the group's co-chairman, Richard Tice, warned. The PM was forced to consult Parliament before invoking Article 50 after it lost a legal challenge in the Supreme Court, but it secured the backing of most MPs earlier this month. On Thursday the government is expected to publish details of its "Great Repeal Bill", which aims to convert EU law into domestic legislation and repeal the European Communities Act, which says EU law is supreme to the UK's. Get news from the BBC in your inbox, each weekday morning ||||| Britain's Prime Minister Theresa May, sitting below a painting of Britain's first Prime Minister Robert Walpole, signs the official letter to European Council President Donald Tusk, in 10 Downing Street,... (Associated Press) Britain's Prime Minister Theresa May, sitting below a painting of Britain's first Prime Minister Robert Walpole, signs the official letter to European Council President Donald Tusk, in 10 Downing Street, London, Tuesday March 28, 2017, invoking Article 50 of the bloc's key treaty, the formal start of... (Associated Press) LONDON (AP) — Britain is set to formally file for divorce from the European Union Wednesday, walking out on a 44-year relationship, enacting the decision made by U.K. voters in a referendum nine months ago and launching both Britain and the bloc into uncharted territory. Prime Minister Theresa May is due to tell House of Commons at lunchtime that she has invoked Article 50 of the EU's key treaty, the trigger for a two-year countdown to Britain's exit. Just before May's statement, scheduled for 1130 GMT (7:30 a.m. EDT), Britain's EU envoy, Tim Barrow, will hand-deliver a letter from May to EU Council President Donald Tusk in Brussels. Photos were released of May signing the letter late Tuesday in the Cabinet room at 10 Downing St., under a portrait of Britain's first prime minister, Robert Walpole. The letter, which is several pages long, was whisked to Brussels aboard a Eurostar train, British media reported. Barrow arrived at European Council headquarters carrying a briefcase Wednesday morning, before his appointment with Tusk. May's office said she will tell lawmakers that the U.K. is embarking on a "momentous journey" and should unite to forge a "global Britain." "It is my fierce determination to get the right deal for every single person in this country," she will say. Britain's Treasury chief, Philip Hammond, said that triggering Brexit was "a pivotal moment for Britain," but denied the country was taking a leap in the dark. "We all have the same agenda. We are all seeking to get the best possible deal for Britain," he told the BBC. Hammond said he was optimistic of forging "a relationship that will strengthen the U.K. and will strengthen the European Union as well." Gus O'Donnell, the U.K.'s former top civil servant, was less certain. "We are in a plane being flown by members of the EU and we're about to jump out and we've got a parachute that was designed by the people flying the plane and they designed it in a way to deter anybody else jumping out," he said. Britain and the EU have two years to unpick a tapestry of rules, regulations and agreements stitched over more than four decades since Britain joined what was then the European Economic Community in 1973. EU officials are due to circulate draft negotiating guidelines within days, and bloc leaders — minus May — will meet April 29 to adopt a common position. Britain says it's not turning its back on its neighbors and wants to remain friends. May has said that the U.K. will become "stronger, fairer, more united and more outward-looking" and will seek "a new, deep and special partnership with the European Union." But many British businesses fear the impact of leaving the EU's vast single market of some 500 million people. Senior British officials say they are confident of striking a close new free-trade relationship with the bloc — but a successful outcome to the complex and emotionally fraught negotiations is far from certain. Brexit has profound implications for Britain's economy, society and even unity. The divisive decision to leave the EU has given new impetus to the drive for Scottish independence, and undermined the foundations of Northern Ireland's peace settlement. It's also a major blow to the EU, after decades of expansion, to lose one of its largest members. Anti-EU populists including French far-right leader Marine Le Pen hope the impulses that drove Britain to turn its back on the EU will be repeated across the continent. ___ Associated Press writer Danica Kirka contributed to this story.

– The UK is preparing to say adios, au revoir, and auf wiedersehen to the European Union after 44 years of membership. Prime Minister Theresa May signed a letter Tuesday night invoking Article 50, and the EU received it Wednesday, formally triggering two years of negotiations leading up to Britain's departure from the bloc, the BBC reports. May was expected to address British lawmakers, calling the historic moment a "time for the country to come together" and promising to fight for "the right deal for every person in this country." Pro-Brexit British newspapers including the Sun, which beamed the message "Dover and Out" onto the famous white cliffs, are rejoicing, though others have sounded notes of caution, the AP reports. "We are in a plane being flown by members of the EU and we're about to jump out and we've got a parachute that was designed by the people flying the plane and they designed it in a way to deter anybody else jumping out," says former top civil servant Gus O'Donnell. EU budget commissioner Guenther Oettinger described the letter as "a negative message for Europe as a whole, for the UK especially" and predicted months of difficult negotiations ahead.

quasiperiodically driven mappings where the dynamics can be strange ( namely on fractal attractors ) but nonchaotic ( namely having a lack of sensitivity to initial conditions ) are of considerable current interest @xcite . strange nonchaotic attractors ( snas ) were first described by grebogi in 1984 @xcite , and are now known to be generic in quasiperiodically driven systems . such dynamics is paradoxical in some ways . the motion on snas is aperiodic , but over long times , nearby trajectories will coincide . the dynamics is almost always characterized by intermittency , which is indicative of the fact that such attractors are highly nonuniform and have a complicated interweaving of ( locally ) stable and unstable regions . external forcing allows for a additional means of probing nonlinear dynamical systems . if the forcing is periodic , then the motion of the system becomes either periodic or chaotic , but for quasiperiodic forcing ( for example when a system is modulated with two frequencies which are incommensurate with each other ) snas become possible . strange nonchaotic dynamics usually occurs in the vicinity of strange chaotic behavior and periodic or quasiperiodic ( nonstrange , nonchaotic ) behavior . as a result , such systems can show transitions between dynamical states and bifurcation phenomena which are similar to those in analogous autonomous systems ( for example the several scenarios @xcite such as the period - doubling route to chaos , intermittency , attractor crises , ) as those that are distinct from the bifurcations of unforced systems @xcite . these have been extensively studied in a number of different contexts : questions of interest range from the mechanisms through which snas are created @xcite , how they may be characterized @xcite , experimental systems where these might occur @xcite , etc . in this paper we examine the transitions between a number of different types of attractors in the quasiperiodically driven logistic map . in this prototypical driven system , the attractors can be strange and nonchaotic , in addition to being strange and chaotic or nonchaotic and regular ( torus attractors ) . studies of the driven logistic map have played an important role in the study of snas . kaneko @xcite first observed `` torus wrinkling '' in this system : this was eventually described as the fractalization route to snas @xcite . the creation of snas through the collision of stable period doubled tori with their unstable parent torus was also first studied in this system @xcite . one great advantage in studying the driven logistic mapping ( even though it is somewhat difficult to obtain analytic results ) is that the undriven logistic map has been extensively studied over the past few decades . many of the features of the driven system find their parallels in the undriven system . at the same time , however , since the dynamics in the logistic map is generic of a wide class , the behaviour that can be simply studied in the driven logistic map is characteristic of most driven nonlinear systems . some scenarios through which snas are formed in this and related systems have been reviewed recently @xcite . snas occur in several different parameter ranges , between regions of periodic or torus attractors and regions of chaotic attractors . there is a plethora of possible dynamical transitions , some of which have parallels in the undriven system , such as torus bifurcations , @xmath0 and others which do not , such as transitions from tori to snas @xmath1 @xmath2 snas merge in a manner similar to the case of reverse bifurcations , snas widen , in a manner similar to widening chaotic crises , and can transform from one type to another or from snas to chaotic attractors . the main focus of this paper , in addition to characterizing the above bifurcations and transitions in this system through the lyapunov exponent and its fluctuations , is also to examine the manner in which the invariant measure varies with the parameters of the system , and the effect that this has on the dynamics . in many instances , these bifurcations or transitions involve the lyapunov exponent going through zero , and can be analyzed in terms of symmetries in the tangent space dynamics . in section ii , we introduce the model , and discuss the analysis in terms of global and local lyapunov exponents , and the return map for stretch exponents . the the characteristic behavior of the lyapunov exponents at the various transitions to different attractors are discussed in sec . this is followed by a summary in sec . we study the logistic map with quasiperiodic modulation of the parameter @xmath3 , [ logistic ] x_n+1 & = & x_n ( 1 - x_n ) + _ n+1 & = & _ n + 1 , where @xmath4 is taken to be an irrational number ( usually the golden mean ratio , @xmath5 . successive iterates of @xmath6 will densely and uniformly cover the unit interval in a quasiperiodic manner , and the system therefore has _ no _ periodic orbits . as in our previous studies @xcite , we rescale the parameter @xmath7 for convenience , and study the system in the range @xmath8 and @xmath9 . the lyapunov exponent corresponding to the @xmath6-rotation is trivially zero ; however the other exponent , which is of most importance in determining the dynamics varies with the parameters . it can be calculated by averaging the _ stretch exponents _ tangential to the flow , namely [ stretch ] y_n = ( 1 - 2 x_n ) , which is the local derivative of the mapping along a trajectory . the local or @xmath10step lyapunov exponent is [ nlyap ] _ j=1^n y_j from which , asymptotically , one gets the global lyapunov exponent = _ n _ n. [ lyap ] the stretch exponents are negative in the region bounded by the curves [ xtheta ] x _ ( ) = 12 . any change in the dynamics such that the invariant measure is increased in the region @xmath11 $ ] will therefore lead to a decrease in the lyapunov exponent , and , conversely , depletion of measure in this region will naturally lead to an increase in the lyapunov exponent . note , however , that the invariant measure , @xmath12 , for this mapping is not known exactly ( except at @xmath13 ) . it is therefore determined numerically by partitioning the phase space @xmath14 into bins and examining the itinerary of a long trajectory . shown in fig . 1(a ) is an example of a sna ; the corresponding invariant measure is shown in fig . the solid line is the locus of @xmath15 , ( cf . ( [ xtheta ] ) ) , showing that the sna is largely located within the contracting regions in phase space , but also has considerable support in the unstable regions . local les , @xmath16 , depend on initial conditions but ( with probability 1 ) @xmath17 does not @xcite . in order to characterize the non uniformity of the attractor , it has proved instructive to examine the distribution of local lyapunov exponents . the probability density , p(n , ) d&= & probability that _ n lies between + & & and + d , has been seen to have characteristic limiting forms that depend on the nature of the attractor @xcite . of course , as @xmath18 , @xmath19 , but the nature of the finite size corrections and the approach to the limit are distinctive for different dynamical states . this analysis is relevant for the study of nonuniform attractors , particularly for different attractors across crisis points or at intermittency , when stretched exponentials often occur @xcite . in this section we study the variation of the dynamics through several transitions in the system as the parameters @xmath3 and @xmath20 are varied . phase diagrams for this system in different parameter ranges have been obtained in a number of previous studies @xcite , and it is known that there are two distinct regions of chaotic dynamics , corresponding , respectively to high driving ( large @xmath20 ) and large nonlinearity ( large @xmath3 ) . these are shown in fig . 2 as c@xmath21 and c@xmath22 @xcite , and they separate a region of quasiperiodic ( torus ) dynamics . strange nonchaotic motion occurs on the boundaries of these regions @xcite as shown in fig . 2 . in addition to the asymptotic nontrivial lyapunov exponent , we also examine the distribution of @xmath10step lyapunov exponents , and the variance of this distribution . the variation in with @xmath3 for fixed @xmath20 is shown in fig . although there are several bifurcations and transitions , these are not easily visible in the behavior of the lyapunov exponent . we therefore examine an approximate or partial bifurcation diagram which can be obtained for this system by plotting the values of @xmath23 that obtain within a narrow window in @xmath6 , namely in the interval ( @xmath24 ) . this will depend upon the choice of @xmath25 and also on the particular value of @xmath6 chosen , but qualitative features of the bifurcation diagram are not affected . the partial bifurcation diagram , fig . 3(b ) , shows some of the transitions clearly : the torus doubling , for instance , and the transition from torus attractors to fractal attractors . since singularities are dense in @xmath6 , a sna or a chaotic attractor shows up as a spread of points ( see fig . 3(b ) , for example ) , while a torus attractor appears as a point or a finite set of points . the distinction between a chaotic attractor or a sna is not evident in the bifurcation diagram , but examining figs . 3(a ) and ( b ) , and the change in the variance in , shown in fig . 3(c ) gives a complete picture of the different attractors that are present in the system . ( our calculations of the variance , @xmath26 , are from @xmath27 samples , each of total length @xmath28 iterations . ) quasiperiodic forcing converts the fixed points of the logistic map into tori . at the period doubling bifurcation , the lyapunov exponent is exactly zero , as in the unforced system , but with quasiperiodicity , the sequence of torus doublings is interrupted and leads to snas , either through the collision of stable and unstable tori as discussed by heagy and hammel @xcite , or through fractalization @xcite . this latter scenario is the most common route to sna , and since there is , apparently , no bifurcation involved , it is not clearly understood as to how a torus gets increasingly wrinkled and transforms into a fractal attractor in the process . other routes to sna are known , some of which , like intermittency @xcite , occur in this system and others , such as the blowout bifurcation route @xcite , which do not . as has been remarked earlier , several of the bifurcation phenomena of ( unforced ) chaotic dynamical systems find their parallels in quasiperiodically forced systems . for example , there are analogue of crisis phenomena . in the present system snas have a certain number of `` bands '' . @xmath29band snas are formed from @xmath29-tori via fractalization , or from 2@xmath29tori through the heagy hammel mechanism . additionally , one band snas can form from a 1torus @xcite or a 3torus @xcite due to saddle - node bifurcations . as parameters are further varied , snas themselves evolve and merge at quasiperiodic analogues of band merging crises or reverse bifurcations : @xmath29band snas transform to @xmath30band snas . through such a transition , when the dynamics remains nonchaotic and strange , is a good order parameter . sosnovtseva @xcite , who discovered an example of this transition in the driven hnon and circle maps , demonstrated the merging by examining the phase portrait . given the fairly narrow range over which snas exist in any system , such transitions also occurs in a restricted range , and often such crises can occur after the transition to chaotic attractors . however , the variation of does not follow a uniform pattern as in the unforced case @xcite . snas which are formed via fractalization may merge at negative . the lyapunov exponent _ decreases _ with increasing nonlinearity ; shown in fig . 4(a ) is the variation of at a band merging bifurcation ( shown by the arrow ) from a two band sna to a one band sna for @xmath31 . the critical value of the parameter is @xmath32 and the corresponding ` partial ' bifurcation diagram of each alternate iterate of @xmath23 is shown in fig . at merging crises in unforced systems , the lyapunov exponent usually does not show an increase ( unlike at widening crises ) while with forcing , the exponent actually decreases . this can be understood by examining the invariant density on the attractor before and after merging . the two bands of the two band sna straddle the region of phase space bounded by the curves @xmath15 , eq . [ xtheta ] . after the merging transition , the density is enhanced mainly in this region where the stretch exponents are all negative . as a consequence , the lyapunov exponent _ must _ decrease . ( a plot of the difference in the invariant density on the snas before and after merging is shown in fig . this appears to be the typical behaviour at the sna band merging transition @xcite , and is in contrast to the behaviour of the unforced system . widening crises also occur , where the sna abruptly changes size as a parameter is varied ( near w@xmath22 in fig . 2 ) . shown in fig . 5 is such an example , which occurs on the line @xmath33 . here , crisis sna , shown in fig . 5(b ) , is clearly larger than the pre crisis sna ( fig . 5(a ) ) which is created via fractalization . the signatures of the transition are evident in both and the variance [ figs . 5(c - d ) ] . the sudden expansion of the attractor seems to be due to collision with the unstable saddle ( which also gives rise to the intermittency transition to sna @xcite ) . this saddle is difficult to locate , but in the three dimensional extension of this system , namely the quasiperiodically driven hnon map , osinga and feudel have recently described similar crises in detail @xcite and have obtained the saddle there as well . in contrast to merging crises , the density is now enhanced in the unstable regions of phase space : therefore increases . the distribution of finite time les also has a stretched exponential tail which is characteristic of the crisis induced intermittency @xcite [ see fig . similar interior crises also take place for lower forcing , when a fractalized sna transforms to an intermittent sna . an example of this is shown in fig . 6 , near @xmath34 and @xmath35 ( w@xmath21 in fig . 2 ) , namely on the edge of region c@xmath21 . on variation of a parameter , a sna can be transformed into a chaotic attractor if the largest lyapunov exponent becomes positive . this transition , which is also not associated with any bifurcation , is not as dramatic as from the torus to a sna . typically there is a smooth variation in the lyapunov exponent . at the sna@xmath36 chaos transition , all the lyapunov exponents of the system are zero . since [ eq . ( [ lyap ] ) ] is a global average , it is of interest to know how the individual terms in eq . ( [ stretch ] ) cancel out so as to give a value zero . consider the partial finite sums @xcite , [ sum1 ] _ n^+ = 1 n_+ _ i y_i , y_i > 0 , and [ sum2 ] _ n^- = 1 n_- _ i y_i , y_i < 0 , namely the separate contributions to the local lyapunov exponent . these are obtained by partitioning a trajectory into @xmath37 points on expanding regions , where the stretch exponents are positive , and @xmath38 points on contracting regions where the stretch exponents are negative with @xmath39 . clearly @xmath40 , and with the limits _ n _ n^ ^ ( cf ( [ nlyap ] ) and ( [ lyap ] ) ) @xmath41 . if there are symmetries in the system @xcite , then @xmath42 and @xmath43 can equal each other and thereby yield @xmath44 . in such situations , there is a term by term cancelation of positive and negative stretch exponents @xcite . at torus bifurcations , for instance , or at the blowout bifurcation transition to snas @xcite this situation applies . on the other hand , there can be an `` accidental '' equality , namely , since both @xmath42 and @xmath43 will be functions of parameters @xmath3 and @xmath45 , it may happen that they are both equal in magnitude for some choice of parameters , and thereby lead to a zero value for the lyapunov exponent . at the sna to chaos transition , this latter situation obtains . lai @xcite investigated the transition from snas to chaotic attractors and found that this transition occurs only when the contraction and expansion rates for infinitesimal vectors along a typical trajectory on the attractor ( namely @xmath42 and @xmath43 ) become equal ; the le passes through zero _ linearly _ as in fig . there are , however , subtler effects that become apparent when examining fluctuations in the local lyapunov exponents . the variance of the distribution shows a small increase across the transition [ fig . there is an increase in the fluctuations in the transition from torus attractors to sna as well ( from essentially zero to some finite value ) . at the sna to chaos transition , the scale of fluctuations doubles , and is therefore noticeable on this scale . the sna @xmath46 chaotic attractor transition is not accompanied by any major change in the form or shape of the attractor , and the lyapunov exponent itself changes only from being negative to positive . yet the fluctuations on the chaotic attractor are always larger than those on the nonchaotic attractor . this enhancement in fluctuations in can be analyzed via the invariant density on the attractors . shown in fig . 8 is the _ difference _ in the invariant density on a sna and a chaotic attractor symmetrically placed about the sna @xmath46 chaos transition . while it is clear that the morphology of the attractor does not change significantly , it can also be seen that on the sna , the invariant density is enhanced in the regions where stretch exponents are mainly negative . since these span the range from @xmath47 to 0 within the region @xmath11 $ ] , they contribute significantly to the variance without greatly affecting the mean : the lyapunov exponent , thus , does not change significantly , but the fluctuations show an increase . crises which occur _ after _ the transition to chaos appear to be very similar to analogous phenomena in systems without forcing @xcite ; @xmath17 has a power law dependence on the parameter , @xmath48 . for example the widening crisis due to saddle node bifurcation along @xmath49 , across the transition point @xmath50 is observed where the value of @xmath51 is @xmath52 which is larger than the unforced case @xcite . in this paper we have studied different dynamical transitions that occur in the quasiperiodically driven logistic map , the main focus being on the quasiperiodic analogues of crisis phenomena . snas are formed via several different routes , and coexist with chaotic as well as other nonchaotic attractors . as a result there are interesting transformations of one type of attractor to another . the torus to sna transitions have been extensively described previously @xcite . fractalization , which is the most common scenario for the formation of snas is a `` p2c2e '' @xcite : no explicit bifurcation mechanism has been identified with this route . however , fractalized snas can be transformed into intermittent snas upon collision with an unstable torus in an analogue of the interior crisis , and also undergo merging at the analogue of a merging crisis . in all these transitions , the nontrivial lyapunov exponent is a good order parameter , and furthermore , its fluctuations the distributions of finite time exponents provide additional signatures for these transitions . in order to understand the nature of the variations of these quantities , however , it is necessary to study the the invariant measure on snas . we show that they have support even in regions which are locally unstable . at many of the transitions that involve such attractors , there is no particular change in form or morphology . however , by examining differences in the invariant density at different parameter values , it becomes clear that at these transitions , the manner in which the dynamics explores the attractor can change drastically , and small changes in the density can lead to significant effects in the fluctuation properties of such attractors . typical attractors in dynamical systems are nonuniform , both with respect to the natural invariant measure as well as in the rate at which nearby trajectories locally diverge or converge . if the measure on converging regions exceeds that on the diverging regions , then the attractor is asymptotically nonchaotic and will be characterized by a negative lyapunov exponent . external modulation can be one method of altering the invariant measure , and this method of creating nonchaotic dynamics @xcite therefore provides a new means of synchronization and control . in this context , therefore , studies of the bifurcations and transformations of snas give further insights into the interplay between global stability and local instability . * acknowledgment * this research was supported from the department of science and technology , india . 99 a. prasad and r. ramaswamy , to be published . j. p. eckmann and d. ruelle , rev . phys . * 57 * , 617 ( 1985 ) . c. grebogi , e. ott , s. pelikan , and j. a. yorke , . j. p. eckmann , rev . phys . * 53 * , 643 ( 1981 ) . a. prasad , v. mehra , and r. ramaswamy , . a. prasad , v. mehra , and r. ramaswamy , . e. ott , _ chaos in dynamical systems _ , ( cambridge university press , cambridge , england , 1994 ) . c. grebogi , e. ott , f. j. romeiras , and j. a. yorke , . f. j. romeiras , a. bondeson , e. ott , t. m. antonsen , and c. grebogi , . s. p. kuznetsov , a. s. pikovsky , and u. feudel , . j. f. heagy and s. m. hammel , . k. kaneko , prog . * 71 * , 1112 ( 1984 ) . t. nishikawa and k. kaneko , . t. yalinkaya and y. c. lai , . e. ott and j. c. sommerer , ; p. ashwin , j. buescu , and i. stewart , ; y. c. lai and c. grebogi , . y. c. lai , ; y. c. lai , u. feudel , and c. grebogi , . a. pikovsky and u. feudel , chaos , * 5 * , 253 ( 1995 ) . w. l. ditto , m. l. spano , h. t. savage , s. n. rauseo , j. heagy , and e. ott , . t. zhou , f. moss , and a. bulsara , . w. x. ding , h. deutsch , a. dinklage , and c. wilke , ; z. liu and z. zhu , int . j. bifurcation and chaos , * 6 * 1383 ( 1996 ) ; z. zhu and z. liu , ; a. j. mandell and k. a. selz , . except for systems which have multiple coexisting attractors , such as the double kicked rotor , duffing oscillator , a. prasad and r. ramaswamy , and references therein . a. prasad and r. ramaswamy , _ finite - time lyapunov exponents of strange nonchaotic attractors _ , in _ nonlinear dynamics : integrability and chaos _ eds . m daniel , k tamizhmani and r sahadevan ( narosa , new delhi , 2000 ) , pp . 22734 . a. witt u. feudel , and a. s. pikovsky , . k. kaneko , prog . 72 * , 202 ( 1984 ) . a. venkatesan , m. lakshmanan , a. prasad , and r. ramaswamy , phys . rev . e , in press 2000 . o. sosnovtseva , u. feudel , j. kurths , and a. pikovsky , . j. crutchfield , d. farmer , and b. huberman , phys . rep . , * 92 * , 45 ( 1982 ) . v. mehra and r. ramaswamy , . we have studied the forced ring map and hnon maps and find that at sna mergings in these systems , the largest lyapunov exponent decreases in a manner very similar to that in the logistic system . h. osinga and u. feudel , `` boundary crisis in quasiperiodically forced systems '' , physica d , in press 2000 . a. prasad and r. ramaswamy , `` can strange nonchaotic attractors be created through stochastic driving ? '' , proc . , in press 2000 . a. prasad , r. ramaswamy , i. i. satija and n. shah , . a. prasad , s. s. negi , s. datta and r. ramaswamy , in preparation . note that the symmetries can be hidden as in ref . @xcite or complicated , as at tangent bifurcations . a `` process too complicated to explain '' from s. rushdie , _ haroun and the sea of stories _ , penguin , 1990 , pp . j. w. shuai and k. w. wong , . 0.5 cm * figure 1 : * ( a ) a sna in the driven logistic map at @xmath53 . and @xmath54 , and ( b ) the corresponding invariant density ( scaled @xmath55 ) in the phase space . the solid lines ( in ( a ) ) and the dashed lines ( in ( b ) ) are the loci of @xmath15 , eqn . ( [ xtheta ] ) . + + * figure 2:*schematic phase diagram for a small region in parameter space , for the forced logistic map see details in ref .@xcite . t and c correspond to regions of torus and chaotic attractors . snas are mainly found in the shaded region along the boundary of t and c ( marked s ) . w denotes the region where widening crises occur ( see the txt ) . + + * figure 3 : * ( a ) variation of as a function of @xmath3 for fixed @xmath56 . note the highly oscillatory structure indicative of several transitions in the system . these are clearly shown in ( b ) which is a ` partial ' bifurcation diagram with @xmath57 and @xmath58 . the regions of torus attractors as well as strange behavior can be easily seen . ( c ) the variance in . the symbol t and c correspond to torus and chaotic attractors while s stands for sna . + + * figure 4:*variation of at a band merging bifurcation ( shown by the arrow ) from a two band ( fractalized ) sna to a one band ( heagy hammel ) sna along @xmath31 at @xmath59 . ( b ) the corresponding ` partial ' bifurcation diagram of the second iteration for @xmath23 in the interval ( @xmath60 ) , @xmath61 and @xmath62 , and ( c ) the difference in densities ( scaled @xmath63 ) after merging ( @xmath64 ) and sna before merging ( @xmath65 ) along @xmath31 . the subscripts 2bs and 1bs refer , respectively , to 2band and 1band snas . + + * figure 5 : * ( a ) the sna before widening along @xmath66 at @xmath67 and ( b ) the sna after the widening crisis at @xmath68 ; ( c ) the variation of lyapunov exponent , @xmath69 across the transition point @xmath70 ; ( d ) the variance in , and ( e ) the distribution of finite - time lyapunov exponents at @xmath68 , showing the stretched exponential tail which is characteristic of intermittency . + + * figure 6:*(a ) the fractalized sna ( before widening ) along @xmath71 at @xmath72 and ( b ) the intermittent sna after the widening crisis at @xmath73 . + + * figure 7:*the transition from sna to a chaotic attractor along @xmath74 . ( a ) the lyapunov exponent across the transition , and ( b ) its fluctuations . + + * figure 8:*the difference in densities ( scaled @xmath63 ) between a chaotic attractor ( @xmath75 ) and sna ( @xmath76 ) along @xmath74 . the plot of @xmath15 ( for @xmath76 ) of eqn . [ xtheta ] is superimposed as a dashed line .

we discuss several bifurcation phenomena that occur in the quasiperiodically driven logistic map . this system can have strange nonchaotic attractors ( snas ) in addition to chaotic and regular attractors ; on snas the dynamics is aperiodic , but the largest lyapunov exponent is nonpositive . there are a number of different transitions that occur here , from periodic attractors to snas , from snas to chaotic attractors , etc . we describe some of these transitions by examining the behavior of the largest lyapunov exponent , distributions of finite time lyapunov exponents and the invariant densities in the phase space . # 1#2#3 phys . rev . lett . * # 1 * , # 2 ( # 3 ) # 1#2#3_ibid . _ * # 1 * , # 2 ( # 3 ) # 1#2#3phys . lett . a * # 1 * , # 2 ( # 3 ) # 1#2#3phys . rev . e * # 1 * , # 2 ( # 3 ) # 1#2#3phys . rev . a * # 1 * , # 2 ( # 3 ) # 1#2#3phys . rev . * # 1 * , # 2 ( # 3 ) # 1#2#3j . phys . a * # 1 * , # 2 ( # 3 ) # 1#2#3j . chem . phys . * # 1 * , # 2 ( # 3 ) # 1#2#3j . . phys . * # 1 * , # 2 ( # 3 ) # 1#2#3j . phys . chem . * # 1 * , # 2 ( # 3 ) # 1#2#3physica d * # 1 * , # 2 ( # 3 ) # 1#2#3pramana j. phys . * # 1 * , # 2 ( # 3 ) i = -1.5 cm

It has now been close to a week since the dreaded Nipah virus outbreak hit Kozhikode in north Kerala. The state government would like the rest of the world to believe that its efforts to contain the virus to as small an area as possible have been successful. To a large extent, that claim does have merit. Even though one more person died on Saturday afternoon, the death was reported from Kozhikode itself. But more attention needs to be given to the question as to how the virus outbreak happened in this part of the world. This is an issue which baffles health experts. It is unclear how the virus landed up in Kozhikode, which is close to three thousand kilometers away from Siliguri in West Bengal, where the last such outbreak was reported way back in 2001. Bangladesh, which saw several Nipah cases till 2017, is also a huge distance away from Kozhikode. Health officials have been burning the midnight oil to ensure that the outbreak is contained. In a matter of further worry for them, test results from the National Institute of High Security Animal Diseases (NISHAD), Bhopal came in. These results were from samples of the bats found in the well of a house in Perambra which is believed to be the epicentre of the outbreak. The Nipah virus was not found in these samples. However, the bats whose samples were collected were insectivorous bats and not fruit bats, which are the only reported host carriers of Nipah till date. While another round of efforts is on to catch hold of fruit bats in the area to send their blood and salivary samples for testing, at present, confusion prevails on the cause of the disease. No such previous cases have ever been reported from anywhere in south India. So, this is perhaps for the first time that experts are faced with such an unprecedented situation. Doctor K Abdul Gafoor is an infectious disease specialist at the Apollo Specialty Hospital in Chennai and had been camping in Kozhikode for the past week trying to ascertain how the virus came here. “Of course, we have no idea at the moment. We need a detailed epidemiological study to get anywhere close to a conclusion. But one positive aspect is that all this seems to be linked to one place which we believe is the source. There has been no second source so far, which in itself is a huge relief. Had there been a second source, things would have been different," Dr Ghafoor told Firstpost. Dr Gafoor also added that the strength of the outbreak has decreased considerably and that the initial panic which the health officials faced has now given way to a new confidence that this is a disease which may not have a vaccine or a complete cure, but can be contained from spreading further. The primary source that the doctor had referred to was the house at Chengaroth village in Perambra panchayat, where three people from a family — two brothers and their aunt — had died. While the absence of a secondary source brings relief, many doctors have a word of caution. “This is why it is so important to find the source of this outbreak. Only if we answer the question of how the virus came to this part of the world can we put in place scientific measures to ensure that such an outbreak does not happen anywhere close by again. Otherwise, we cannot be sure of how and in which way this virus would spread in the future,’’ warns Dr Shimna Azeez, a medical officer at Malappuram, from where two confirmed cases of Nipah were reported apart from the ones at Kozhikode. Following is an overview of the possible ways in which the virus could have travelled to northern Kerala. From Bangladesh to Kerala? Even though it is well known that fruit bats are the host carriers of the virus, no evidence could be gathered from Kozhikode to prove that the same species of bats have played a role in this outbreak too. The assumption that fruit bats are the villains is based on the previous outbreaks that took place in Siliguri, Bangladesh, and Malaysia. But health officials say that as long as no conflicting evidence is received, it has to be believed that fruit bats are indeed the cause in Kozhikode too. But even that also does not answer the crucial question — how did the virus reach Kerala? Although some species of bats have been found to be migratory, scientists are not ready to believe that they would have flown thousands of miles to northern Kerala without showing such viral activity at any place on their way. There are a few who propose another theory. According to them, other large carnivorous migratory birds like eagles may have preyed upon an infected fruit bat and brought the virus with them in their bodies to Kerala. They may have then attacked a fruit bat in the state. Although this is theoretically possible, wildlife experts say it is improbable. “There has been no evidence so far to prove that such large migratory birds are capable of carrying the virus, simply because their body constitution does not support Nipah. This virus thrives in solutions which are high in sugar content, like the saliva of a fruit bat. That is why we say it cannot be even in insectivorous bats. We cannot at this moment think of any other bird as a host,’’ well known ornithologist Dr R Sugathan told Firstpost. Food source? But Sugathan has another interesting take. He says that it is possible that Nipah could have traveled in fruits like figs and dates from places like Bangladesh to Kerala. But here too, the role of the bats is the key. “There are lots of dates that come from outside. We all know that dates are very high in sugar content. There is a possibility that some infected fruit bat could have come in contact with dates while being packed. Since this virus has the capacity to survive for a number of days in a sugary medium, we cannot rule out this possibility,’’ added Sugathan. Sugathan’s theory also makes sense because it is the month of Ramzan, and in Kozhikode, dates arrive in huge quantities from a number of countries outside India. No outside source? While scientists are battling hard to find an external source of the virus, some believe that Nipah could have co-existed with the bats in Kozhikode for a long time only to be pushed out of the mammal in adverse circumstances. Dr Nameer PO is the head of the department at College of Forestry in Kerala Agricultural University, and is an expert on bats. He says that such viruses and ‘flying foxes’ have always been co-existing entities, and it was only a matter of time that they showed up to the rest of the world. “Viruses like Nipah have always been in the system of fruit bats. They have co-evolved for years. Such a disease becomes virulent when there is a stress on the animal. Such stress could be because of a loss of habitat, or not getting sufficient food for survival. So, when the animal is faced with such stress, it tends to expel these viruses. In other words, the virus tends to move out of animal. This could be what happened in Kozhikode. But unless we get conclusive evidence that such bats are the reason, we cannot be sure,’’ Nameer told Firstpost. Nameer also cites the example of the co-existence of migratory birds and the avian bird flu virus. According to him, since these birds are migratory in nature, they take it from one location to another. Scientists are also raising the question of mutation. In other words, they say that depending on changes in many external factors like temperature and water, some of the viruses may break up or even mutate into different forms and get transformed into a new and highly virulent one such as Nipah and lead to an outbreak. “There is a serious possibility that mutation could have been the reason for an outbreak in Kozhikode. But that can only be ascertained with an in-depth study, which will take a number of days,’’ added a senior doctor in the team of experts camping at Kozhikode. Some doctors say that while dealing with a disease which has recently become known like Nipah, confusion is an expected thing. The medical fraternity is yet to understand Nipah in its entirety. “It was first detected in 1998, which in the medical world means it is a new disease, about which there could be more things we don’t know than things we know. Remember, smallpox came to the world three thousand years ago, but we discovered a vaccine for it just 200 years ago. Nipah is a disease that was discovered just 20 years ago. The medical fraternity has recently started its research on it. But Kerala has done a commendable job in diagnosing it quickly,’’ said Dr PS Jinesh from Info Clinic. Travel records of the first victim, Muhammed Salih, were also checked on Saturday to ascertain whether he had visited any of the areas reported to have had Nipah outbreaks in the recent past. Apart from visiting Dubai a few months ago, it seems that the young man had not travelled anywhere out of Kozhikode. Meanwhile, the state has put in stringent control measures at the Kozhikode Government Medical College Hospital, where most of the Nipah cases have been reported. Only patients requiring emergency treatment are admitted at the hospital. Others are treated at the emergency section and discharged at the earliest to ensure that more patients do not come in contact with the virus. Perhaps the only way to get to the bottom of this is to check as many samples of fruit bats as possible, a much-needed but painfully slow process that will start on Monday. Till then, the question of Nipah’s origin in Kerala will remain a matter of speculation. ||||| More than a dozen people have died after an outbreak of a rare disease in southern India that health officials warn could cause a global epidemic. Health officials have imposed emergency measures in the southwestern state of Kerala after the more than 40 people were infected with the Nipah virus, which causes flu-like symptoms leading to an agonizing brain-swelling condition known as encephalitis, according to Sky News. There is no vaccine for Nipah, which has a mortality rate of 70 percent, and no treatment beyond supportive care to make patients comfortable. The virus is listed alongside Ebola and Zika as one of eight priority diseases the World Health Organization believes could cause a global epidemic. Health officials believe this outbreak began with someone infected by a fruit bat, a senior Health Ministry official told the Press Trust of India news agency. Subsequent infections are believed to have come from human-to-human contact, sometimes passing to relatives or medical workers caring for the sick. About 100 families where someone has had contact with infected people are being carefully monitored by health officials. RARE BAT VIRUS KILLS AT LEAST 10 IN INDIA AS OFFICIALS SCRAMBLE TO CONTROL OUTBREAK Tests have also been ordered after several bats were found dead at a secondary school in the state of Himachal Pradesh, according to Sky News. The examinations later found the bats were not carrying Nipah, but fear continues to run high across the country. Health officials advise that people should not eat fruits that have fallen to the ground or appear to feature tooth or claw marks, and travel to the affected states should be avoided. On Thursday, medical workers in white plastic suits and breathing masks buried the latest victim in the town of Kozhikode, placing his plastic-wrapped corpse in the red earth. People have also been told to avoid abandoned wells, as fruit bats eat dates from palm trees, and sometimes nest in wells. Health experts have been flown into the region to help contain the virus, according to Sky News. The Associated Press contributed to this report.

– The Nipah virus has now killed at least a dozen people in southern India and health workers fear it could become a global epidemic if it isn't tightly monitored. More than 40 other people have been infected with the virus, which has a mortality rate of around 75%, Fox News reports. Health officials believe the outbreak in Kerala state began with an infected fruit bat, with later infections coming from human-to-human contact. There's no known cure or vaccine for Nipah, which causes symptoms including fever, vomiting, and convulsions. To avoid being infected by fruit bats, citizens have been urged to ignore fallen fruit on the ground, especially if it has claw or tooth marks. Previous outbreaks of Nipah were recorded in West Bengal and Bangladesh, more than a thousand miles away from the current outbreak. Experts aren't sure how it ended up in Kerala, especially since no cases have been detected elsewhere in southern India and even migratory bats don't travel that far. Some experts believe it was spread through infected figs and dates, while others say pressures on fruit bat populations may have activated the virus. "This is why it is so important to find the source of this outbreak," a medical officer tells FirstPost. "Only if we answer the question of how the virus came to this part of the world can we put in place scientific measures to ensure that such an outbreak does not happen anywhere close by again. Otherwise, we cannot be sure of how and in which way this virus would spread in the future."

proton pump inhibitors ( ppis ) potently inhibit gastric acid secretion , and are widely used for prevention and treatment of various acid - related diseases including peptic ulcers and gastro - esophageal reflux diseases . although their acid inhibitor potency is far stronger than that of histamine h2 receptor antagonists ( h2ras ) , ppis are reported to have some weak points in comparison with those drugs . a disadvantage of the acid inhibitory effect of ppis is the strong influence of cyp2c19 , a hepatic drug metabolizing enzyme that degrades ppis . in patients with high activity of the cyp2c19 enzyme ( extensive metabolizers ) , the effect of ppi administration is not adequately strong , because of enzymatic degradation . on the other hand , in patients with a low cyp2c19 enzyme activity ( poor metabolizers ) , another disadvantage is slow onset of the acid inhibitory effect after ppi administration . to improve these weak points , new types of ppis rabeprazole is a new type of ppi that is not strongly influenced by cyp2c19 enzyme activity , because it is not mainly degraded by cyp2c19 . in addition , this drug is reported to inhibit acid secretion more quickly than first generation ppis including omeprazole and lansoprazole . another agent is esomeprazole , an s - isomer of omeprazole that is a mixture of s- and r - isomers . esomeprazole has also been reported to not be effectively degraded by cyp2c19 and its effect is not strongly influenced by its enzyme activity . the acid suppressing effects of rabeprazole ( 20 mg ) and esomeprazole ( 40 mg ) have been investigated , with those of the latter reported to be equal or superior to the former . the standard doses of rabeprazole and esomeprazole in japan are 10 and 20 mg , respectively , per day . those ppis at those doses have not been directly compared in regard to quickness of acid inhibition and acid inhibitory potency in cases with different cyp2c19 enzyme activities . it is considered that intra - gastric ph monitoring soon after acute single administration of a ppi is an ideal experimental design to investigate its quick acid inhibitory effects . in the present study , a single standard dose of rabeprazole or esomeprazole was administered to normal volunteers in a multicenter double - blind randomized prospective study with a cross - over design and their effects on intra - gastric ph were compared . fifty - seven healthy volunteers were enrolled at 9 university hospitals ; shimane university , hokkaido university hospital , gunma university hospital , nippon medical school , yokohama city university hospital , hamamatsu university school of medicine , osaka city university , osaka medical college , and saga medical school . their mean age was in the 20s and none of the subjects was infected by helicobacter pylori ( h. pylori ) , which was determined by testing for the presence of the h. pylori antibody in serum and urine samples . the cyp2c19 genotype was tested by a polymerase chain reaction - restriction fragment length polymorphism ( pcr - rflp ) assay , as previously reported . twenty - nine of the 57 enrolled volunteers were randomly enrolled in the pre - meal ppi administration protocol . the subjects were investigated by ph monitoring twice , once with 10 mg of rabeprazole and once with 20 mg of esomeprazole . the ppis were delivered in identical opaque gelatin capsules and discrimination between them was impossible during the study period . the identical opaque gelatin capsules containing 10 mg rabeprazole or 20 mg esomeprazole were prepared by an author pharmacist ( kn ) and packaged in marked bags , and then delivered to each participating hospital . the key code of the drugs was kept by kn and opened firstly after fixing the final ph data . the 2 ph monitoring examinations were separated by at least a 1-week interval . an intra - gastric ph monitoring sensor catheter ( zenetics medical , salt lake city , ut ) was introduced into the gastric body and monitoring was started at 17:00 , as previously reported . a single oral dose of the ppi was administered at 15 min before supper , at 18:45 . the subjects started eating their supper ( carbohydrates 112.8 g , protein 16.3 g , fat 27.3 g , calories 762 kcal ) at 19:00 and were asked to finish within 30 min . the subjects were then requested to lie on their bed from 23:00 to 7:00 next morning . breakfast ( carbohydrates 34 g , protein 5.8 g , fat 2.8 g , calories 85 kcal ) and lunch ( carbohydrates 74.4 g , protein 17.1 g , fat 11.4 g , calories 531 kcal ) were also consumed within 30 min , starting at 8:00 and 12:00 , respectively . all conditions were the same as above , except that rabeprazole or esomeprazole was administered orally 30 min after the end of supper at 20:00 . in the postprandial administration protocol , the supper ( carbohydrate 52.8 g , protein 8.8 g , fat 9.2 g , calorie 330 kcal ) and breakfast ( carbohydrate 94 g , protein 13.3 g , fat 20.9 g , calorie 617 kcal ) were also slightly different from those used in the pre - meal administration protocol . median ph for each monitored hour and the percentage of time at which intra - gastric ph was below 4.0 were calculated for the total 24-h period , as well as the daytime ( 7:0023:00 ) and nighttime ( 23:007:00 ) periods . statistical analysis was performed using a wilcoxon signed rank test when results of a friedman test showed significant differences . the chronological data shown in fig . 1 , 3 , 4 and 6 were analyzed by linear mixed models . the sample size of the study was calculated based on the previous studies comparing 40 mg esomeprazole and 20 mg rabeprazole on their first administration day . calculated the number of necessary subjects as 18 based on parametric assumption and found the statistically significant results in their study . therefore , in this study , 27 healthy subjects were enrolled in two different protocols ( administration before or after a meal ) . fifty - seven healthy volunteers were enrolled at 9 university hospitals ; shimane university , hokkaido university hospital , gunma university hospital , nippon medical school , yokohama city university hospital , hamamatsu university school of medicine , osaka city university , osaka medical college , and saga medical school . their mean age was in the 20s and none of the subjects was infected by helicobacter pylori ( h. pylori ) , which was determined by testing for the presence of the h. pylori antibody in serum and urine samples . the cyp2c19 genotype was tested by a polymerase chain reaction - restriction fragment length polymorphism ( pcr - rflp ) assay , as previously reported . twenty - nine of the 57 enrolled volunteers were randomly enrolled in the pre - meal ppi administration protocol . the subjects were investigated by ph monitoring twice , once with 10 mg of rabeprazole and once with 20 mg of esomeprazole . the ppis were delivered in identical opaque gelatin capsules and discrimination between them was impossible during the study period . the identical opaque gelatin capsules containing 10 mg rabeprazole or 20 mg esomeprazole were prepared by an author pharmacist ( kn ) and packaged in marked bags , and then delivered to each participating hospital . the key code of the drugs was kept by kn and opened firstly after fixing the final ph data . the 2 ph monitoring examinations were separated by at least a 1-week interval . an intra - gastric ph monitoring sensor catheter ( zenetics medical , salt lake city , ut ) was introduced into the gastric body and monitoring was started at 17:00 , as previously reported . a single oral dose of the ppi was administered at 15 min before supper , at 18:45 . the subjects started eating their supper ( carbohydrates 112.8 g , protein 16.3 g , fat 27.3 g , calories 762 kcal ) at 19:00 and were asked to finish within 30 min . the subjects were then requested to lie on their bed from 23:00 to 7:00 next morning . breakfast ( carbohydrates 34 g , protein 5.8 g , fat 2.8 g , calories 85 kcal ) and lunch ( carbohydrates 74.4 g , protein 17.1 g , fat 11.4 g , calories 531 kcal ) were also consumed within 30 min , starting at 8:00 and 12:00 , respectively . all conditions were the same as above , except that rabeprazole or esomeprazole was administered orally 30 min after the end of supper at 20:00 . in the postprandial administration protocol , the supper ( carbohydrate 52.8 g , protein 8.8 g , fat 9.2 g , calorie 330 kcal ) and breakfast ( carbohydrate 94 g , protein 13.3 g , fat 20.9 g , calorie 617 kcal ) were also slightly different from those used in the pre - meal administration protocol . median ph for each monitored hour and the percentage of time at which intra - gastric ph was below 4.0 were calculated for the total 24-h period , as well as the daytime ( 7:0023:00 ) and nighttime ( 23:007:00 ) periods . statistical analysis was performed using a wilcoxon signed rank test when results of a friedman test showed significant differences . the chronological data shown in fig . 1 , 3 , 4 and 6 were analyzed by linear mixed models . the sample size of the study was calculated based on the previous studies comparing 40 mg esomeprazole and 20 mg rabeprazole on their first administration day . calculated the number of necessary subjects as 18 based on parametric assumption and found the statistically significant results in their study . therefore , in this study , 27 healthy subjects were enrolled in two different protocols ( administration before or after a meal ) . of the 57 enrolled subjects , 2 in the preprandial administration group and 1 in the postprandial group were not analyzed because of intolerance to the second ph monitoring examination . there were no significant differences in regard to gender , age , height , body weight , bmi , and cyp2c19 genotypes between the administration protocol groups ( table 1 ) . when administered before the meal , the median intra - gastric ph after esomeprazole administration tended to be higher than after rabeprazole administration ( fig . 1 ) , whereas intra - gastric ph in the 2:003:00 time period was significantly higher after esomeprazole administration . we also calculated percent time of intra - gastric ph > 4.0 over the 24-h period , as well as during the daytime and nighttime periods . again , esomeprazole tended to show a stronger acid inhibitory effect , though differences with rabeprazole were not significant ( fig . 2 ) . when the data was separately calculated for different cyp2c19 genotypes , esomeprazole raised intra - gastric ph more effectively in rapid metabolizers at 4 time points in 24-h observation period ( fig . 3 ) , while there was no apparent difference between intra - gastric ph between rabeprazole and esomeprazole in the intermediate and poor metabolizers , except at a single time point in poor metabolizers . when the ppis were administered after meals , there were no apparent differences in median intra - gastric ph at any time point after either administration ( fig . 4 ) . furthermore , after calculating percent time of intra - gastric ph > 4.0 , there were no differences found during the daytime and nighttime periods ( fig . 5 ) . median intra - gastric ph was also calculated based on cyp2c19 genotype , and compared between rabeprazole and esomeprazole , with no significant difference found , except at a single time point in poor metabolizers ( fig . the present results show that the acid inhibitory effects of 10 mg of rabeprazole and 20 mg of esomeprazole after single oral doses were similarly potent , especially when administered after meals . four kinds of ppis , omeprazole , lansoprazole , rabeprazole , and esomeprazole , are available for clinical practice in japan , which can be divided into 2 groups based on their degradability by the hepatic drug metabolizing enzyme cyp2c19 . omeprazole and lansoprazole are easily degraded by cyp2c19 , while rabeprazole and esomeprazole are not . asian individuals are known to have heterogeneous cyp2c19 enzyme activity , as 30% are extensive metabolizers with high enzyme activity , 20% are poor metabolizers with low enzyme activity , and the remaining 50% are intermediate metabolizers . therefore , different from western countries , the acid inhibitory effects of omeprazole and lansoprazole are known to be diverse among individuals . in cases with a high level of cyp2c19 enzyme activity , the acid inhibitory effects of these drugs are expected to be limited . to improve uncertainty , the more stable ppis rabeprazole and esomeprazole are increasingly used in clinical practice for japanese patients , with standard oral doses of 10 and 20 mg , respectively . rabeprazole is a newly developed racemic mixture compound reported to resist cyp2c19 degradation , while esomeprazole is an s - isomer of omeprazole and similarly resistant to cyp2c19 . therefore , these ppis are considered to have a more consistent acid inhibitory effect irrespective of cyp2c19 enzyme activity . however , that of esomeprazole is considered to become submaximal when the drug is administered after a meal . there are 2 possible mechanisms regarding this weak point of esomeprazole to consider , decreased absorption and incomplete activation . the plasma concentration of esomeprazole was investigated and compared when administered during fasting and after meals . those results clarified that the plasma concentration of esomeprazole was higher when administered during fasting , though the precise mechanism related to that difference is not clear . all ppis need to be activated by the acidic environment in the secretory canaliculi of parietal cells . when administered after meals , an absorbed ppi will not be effectively activated because food - induced acid secretion and the highly acidic environment in the secretory canaliculi are nearly terminated when the plasma concentration of the drug reaches a peak level at 23 h after administration . mainly based on data obtained from esomeprazole trials in western countries , ppis are recommended to be administered 30 min before meals . on the other hand , the acid inhibitory effect of rabeprazole was shown to be not significantly influenced by timing of administration . in the present study , intra - gastric acidity after a single postprandial oral dose of rabeprazole ( 10 mg ) or esomeprazole ( 20 mg ) was similarly raised and remained nearly identical for 24 h. on the other hand , the acid inhibitory effect of the latter was slightly stronger than that of the former when each was administered before meals , though the difference was not statistically significant . these results confirm a previous report showing that esomeprazole had a stronger acid inhibitory effect when administered 30 min before meals . in the present study , direct comparisons of the acid inhibitory effects of the tested ppis between pre- and post - prandial administrations was difficult , since the foods taken during the monitoring periods were not identical . however , when we compared the pre- and post - prandial administrations , esomeprazole was stronger with pre - prandial administration , as previously reported , while rabeprazole was equally potent irrespective of the timing of administration . in japan , approximately 80% of physicians instruct their patients to take ppis after breakfast and approximately 10% after dinner . therefore , 90% of the patients take ppis after meals . in such an environment , the acid inhibitory effects of the present ppi administrations are considered to be nearly identical , though esomeprazole may show a statistically non - significant benefit when administered before meals . the first is lack of baseline intra - gastric ph data obtained without any drug administration . to more sensitively check the potency of any acid inhibitory effect , baseline ph data are necessary therefore , a comparison of the intra - gastric ph observed after rabeprazole and esomeprazole administrations is the only one possible in this study . therefore , we could not correlate the pharmacokinetic disposition of ppi with the intragastric ph . the influence of meal on the absorption of ppis and their acid inhibitory effects could not be made clear . another is the lack of ph data during chronic administration of the ppis , since these drugs are frequently used for chronic treatment . an additional study with chronic administrations of ppis as well as baseline data may be necessary in the future . in summary , we found that the intra - gastric ph values for 24 h after a single oral dose of rabeprazole ( 10 mg ) or esomeprazole ( 20 mg ) were nearly identical , especially when administered after meals . on the other hand the center for clinical research and the first department of medicine at hamamatsu university school of medicine have received grants from takeda pharmaceutical co. , ltd . , astrazeneca kk , eisai co. , ltd . , daiichi - sankyo co. , ltd . , and sugimoto m and furuta t have received lecture fees from takeda pharmaceutical co. , ltd . , astrazeneca kk , eisai co. , ltd . , daiichi - sankyo co. , ltd . kusano m received lecture fee and research grant from eisai co. , ltd . , and lecture fee from astrazeneca kk and daiichi - sankyo co. , ltd . , takeda pharmaceutical co. , ltd . , and astrazeneca kk and received research funds from eisai co. , ltd . , takeda pharmaceutical co. , ltd . , otsuka pharmaceutical co. , ltd . , astrazeneca kk , astellas pharmaceutical co. , ltd . , and daiichi - sankyo co. , ltd . higuchi h and fujimoto k received research grant and lecture fees from astrazeneca kk , eisai co. , ltd . , daiichi - sankyo co. , ltd . naora k received research grants from astrazeneca kk , eisai co. , ltd . , and takeda pharmaceutical co. , ltd . arakawa t received research grant from eisai co. , ltd . and otsuka pharm co. , and lecture fee from eisai co. , ltd . kinoshita y received research grants and lecture fees from astrazeneca kk , eisai co. , ltd .

comparisons between the acid inhibitory effects of rabeprazole and esomeprazole after single oral administration with standard doses have not been previously presented . we examined intra - gastric ph after oral administrations of these two proton pump inhibitors using 24-h ph monitoring . fifty - four normal volunteers not infected by helicobacter pylori were investigated . using a cross - over design , we administered 10 mg of rabeprazole or 20 mg of esomeprazole in 27 at 30 min after supper and in the remaining 27 subjects at 15 min before supper , and performed 24-h ph monitoring . intra - gastric ph data were nearly identical when the proton pump inhibitors were taken after meals . even if the data were compared in different cyp2c19 genotypes , rabeprazole and esomeprazole did not show the difference . in poor metabolizer , both of the drugs showed stronger acid inhibition . when taken before meals , intra - gastric ph after esomeprazole administration was slightly but not significantly higher than that observed after rabeprazole administration not only in daytime but also in nighttime period . in conclusion , rabeprazole and esomeprazole were similarly effective when administered after a meal .

hence , many researches have been developed to improve the bone - healing process ; these studies involve not only surgical technique but also the use of biological resources and molecular techiniques . the bone repair process involves a complex cascade of biological responses , is affected by local and external factors , and is regulated by the interaction of different mechanisms . increase or decrease in bone - repair capacity is directly related to changes in remodeling . bone regeneration is understood to be the replacement of damaged cells by other morphologically and functionally identical cells . bone lesions with small dimensions are repaired easily , while fibrous scar , as a peculiar characteristic of this type of fabric , needs a repair mechanism similar to that of embryonic osteogenesis . however , the regenerative capacity of bone tissue is limited by the extent of the injury , in this sense , extensive bone defects caused by trauma , tumors , infections , and developmental abnormalities do not regenerate spontaneously , posing a challenge to the scientific community . in any experimental study , a critical size defects ( csd ) should be established , which is defined as the smallest intraosseous defect that will not heal spontaneously throughout the animal 's life , affecting the formation of fibrous connective tissue rather than bone formation . in rodents , lesions with diameter lectins are a structurally heterogeneous group of proteins , glycosylated or not , non - immune origin that have the ability to recognize at least a reversible binding site specific monosaccharides or oligosaccharides . the cell surfaces are rich in glycoproteins ( glycosidic receptors ) that potentially interact with lectins by carbohydrates attained portion ; this lectin - cell interaction is the molecular basis that can trigger several changes in biological organisms . regarding the use of glucose - mannose lectins in the healing process , the lectins of canavalia brasiliensis , dioclea violacea , canavalia ensiformis , and cratylia mollis used in the treatment regimens proved to be effective therapeutic agents . the present study was aimed to evaluate the effectiveness of using the gel formulation of irradiated cratylia mollis lectin ( isoforms 1 and 4 ) in experimentally induced bone defects in rats , considering the reduction of time to repair tissue and the histological characteristics of repair process in relation to experimental treatment applied , assessment of serum biochemistry , and bone mineral measurement . carbopol was used as a vehicle suspended in boric acid buffer ( ph 6.0 ) at 25c . after extraction and purification , cramoll-1,4 solution was added in sufficient quantity to achieve the final concentration of 300 g in 100 l of the gel . all procedures related to the use of animals were submitted to and approved by the ethics committee on animal experimentation of federal university of pernambuco ( process 016036/2007 - 10 ) . we used 12 90-day - old female albino wistar rats ( rattus norvegicus ) , weighing 300 50 g , and produced two critical defects in each animal , where each rat was a control for herself , and 3 rats were euthanized at the end of each experimental period ( 15 , 30 , 45 , and 60 days , postoperatively ) . the animals were pre - anesthetized with atropine sulfate at a dose of 0.04 mg / kg / intramuscularly . after 10 min of anesthesia , a combination of 10% ketamine hydrochloride ( 90 mg / kg ) and 2% xylazine hydrochloride ( 10 mg / kg ) was applied intramuscularly . trichotomy was performed in mouse calvarial and antisepsis with an alcoholic solution of 10% iodine polivilpirrolidona , followed by local anesthesia with bupivacaine and section 2000 iu of skin and subcutaneous tissue . we produced two circular bone cavities ( in each parietal region ) using a trephine drill of 5 mm diameter [ figure 1 ] . critical defect : production of two circular bone cavities ( in the parietal region ) measuring 5 mm in diameter one of the cavities was filled with the experimental treatment , while the other was filled with a gel as a control excipient . later , the two cavities were covered by an absorbable cellulose membrane ( bionext ) , did not occur to the passage of material from one cavity to another . the animals were kept in an environment without air conditioning and subjected to heating by a light source , avoiding hypothermia , cardio - respiratory depression , and death , and taking care to protect the eyes with gauze moistened with 0.9% saline . also , analgesia was instituted immediately after surgery by administering dipyrone sodium ( 0.15 mg / kg ) intramuscularly and maintenance for 3 consecutive days , added to drinking water ( 40 mg / kg ) . the administration of antibiotics as a prophylactic measure was not carried out . to control the environment in the operating room , aseptic use of personal protective equipment suitable for sterile surgery and antisepsis of the area to be operated . animals were monitored daily for signs of pain ( hair bristling and anorexia ) , behavioral changes ( lethargy and drowsiness ) , or neurological ( ambulation and head deviation ) damage and/or infectious . although it is an invasive surgery , the animals showed normal behavior of the species and ingestion of food and water . in the pre - set from 8:00 am , with 2 h fasting , the animals were anesthetized and 4 ml of blood was collected from each animal by cardiac puncture into sterile test tubes . the animals were then given an overdose of thiopental sodium , intraperitoneally , for completion of euthanasia . the determination of calcium ( ca ) levels was performed by the arzenazo diasys iii method , the determination of phosphorus ( p ) by the mobilidato diasys uv method , and determination of magnesium ( mg ) by the xilidil diasys method . the determination of albumin ( alb ) and alkaline phosphatase ( alp ) was performed by using automation architect ( abbot diagnostics ) in blood serum . we reserved the left tibia of each animal , deposited individually in porcelain crucibles in an oven at a temperature of 100c for 2 h , and determined the proportion of ca , p , and mg using atomic absorption spectrometry ( shimadzu aa-6300 ) . the skullcap was removed , immersed in 10% formaldehyde solution in pbs ( isotonic saline solution buffered with sodium phosphate ) , ph 7.2 - 7.4 , for at least 24 h. after fixation , the caps were decalcified in a solution of 10% nitric acid for 2 h at 60c . they were then washed in distilled water , dehydrated in increasing battery of alcohol , cleared in xylene , and embedded in paraffin . the samples were sectioned in semi - serial cuts 5-m thick and stained with hematoxylin - eosin and masson 's trichrome . statistical analysis was conducted by using student 's t test for independent samples , adopting a 5% statistical significance ( p < 0.05 ) . carbopol was used as a vehicle suspended in boric acid buffer ( ph 6.0 ) at 25c . after extraction and purification , cramoll-1,4 solution was added in sufficient quantity to achieve the final concentration of 300 g in 100 l of the gel . all procedures related to the use of animals were submitted to and approved by the ethics committee on animal experimentation of federal university of pernambuco ( process 016036/2007 - 10 ) . we used 12 90-day - old female albino wistar rats ( rattus norvegicus ) , weighing 300 50 g , and produced two critical defects in each animal , where each rat was a control for herself , and 3 rats were euthanized at the end of each experimental period ( 15 , 30 , 45 , and 60 days , postoperatively ) . the animals were pre - anesthetized with atropine sulfate at a dose of 0.04 mg / kg / intramuscularly . after 10 min of anesthesia , a combination of 10% ketamine hydrochloride ( 90 mg / kg ) and 2% xylazine hydrochloride ( 10 mg / kg ) was applied intramuscularly . trichotomy was performed in mouse calvarial and antisepsis with an alcoholic solution of 10% iodine polivilpirrolidona , followed by local anesthesia with bupivacaine and section 2000 iu of skin and subcutaneous tissue . we produced two circular bone cavities ( in each parietal region ) using a trephine drill of 5 mm diameter [ figure 1 ] . critical defect : production of two circular bone cavities ( in the parietal region ) measuring 5 mm in diameter one of the cavities was filled with the experimental treatment , while the other was filled with a gel as a control excipient . later , the two cavities were covered by an absorbable cellulose membrane ( bionext ) , did not occur to the passage of material from one cavity to another . the animals were kept in an environment without air conditioning and subjected to heating by a light source , avoiding hypothermia , cardio - respiratory depression , and death , and taking care to protect the eyes with gauze moistened with 0.9% saline . also , analgesia was instituted immediately after surgery by administering dipyrone sodium ( 0.15 mg / kg ) intramuscularly and maintenance for 3 consecutive days , added to drinking water ( 40 mg / kg ) . the administration of antibiotics as a prophylactic measure was not carried out . to control the environment in the operating room , aseptic use of personal protective equipment suitable for sterile surgery and antisepsis of the area to be operated . animals were monitored daily for signs of pain ( hair bristling and anorexia ) , behavioral changes ( lethargy and drowsiness ) , or neurological ( ambulation and head deviation ) damage and/or infectious . although it is an invasive surgery , the animals showed normal behavior of the species and ingestion of food and water . in the pre - set from 8:00 am , with 2 h fasting , the animals were anesthetized and 4 ml of blood was collected from each animal by cardiac puncture into sterile test tubes . the animals were then given an overdose of thiopental sodium , intraperitoneally , for completion of euthanasia . the determination of calcium ( ca ) levels was performed by the arzenazo diasys iii method , the determination of phosphorus ( p ) by the mobilidato diasys uv method , and determination of magnesium ( mg ) by the xilidil diasys method . the determination of albumin ( alb ) and alkaline phosphatase ( alp ) was performed by using automation architect ( abbot diagnostics ) in blood serum . we reserved the left tibia of each animal , deposited individually in porcelain crucibles in an oven at a temperature of 100c for 2 h , and determined the proportion of ca , p , and mg using atomic absorption spectrometry ( shimadzu aa-6300 ) . the determination of calcium ( ca ) levels was performed by the arzenazo diasys iii method , the determination of phosphorus ( p ) by the mobilidato diasys uv method , and determination of magnesium ( mg ) by the xilidil diasys method . the determination of albumin ( alb ) and alkaline phosphatase ( alp ) was performed by using automation architect ( abbot diagnostics ) in blood serum . we reserved the left tibia of each animal , deposited individually in porcelain crucibles in an oven at a temperature of 100c for 2 h , and determined the proportion of ca , p , and mg using atomic absorption spectrometry ( shimadzu aa-6300 ) . the skullcap was removed , immersed in 10% formaldehyde solution in pbs ( isotonic saline solution buffered with sodium phosphate ) , ph 7.2 - 7.4 , for at least 24 h. after fixation , the caps were decalcified in a solution of 10% nitric acid for 2 h at 60c . they were then washed in distilled water , dehydrated in increasing battery of alcohol , cleared in xylene , and embedded in paraffin . the samples were sectioned in semi - serial cuts 5-m thick and stained with hematoxylin - eosin and masson 's trichrome . statistical analysis was conducted by using student 's t test for independent samples , adopting a 5% statistical significance ( p < 0.05 ) . the serum values of alb , alp , ca , p and mg were within the limits established by mitruka and rawnsley , showing a difference related to the values of alp ( 56.8 - 128 u / l ) , while , across the dosage of the trial period , alp was high ( 214.0 - 286.0 meansd of serum albumin , alkaline phosphatase , calcium , phosphorus and magnesium in animal experimental periods the levels of alp [ table 1 ] were not different when comparing the experimental periods . on an average , highest level of alp was found 45-days postoperatively . however , this level was higher than the established values by the hematology baseline and clinical chemistry values for charles river wistar rats for females aged 19 - 21 weeks ( 39 - 177 u / l ) and ( 39 - 216 u / l ) established by olfert et al . , which can be justified by the fact that collections were made after 15 days of induction of critical defect , which coincides with the production phase of the collagen matrix having a higher production of alkaline phosphatase . analyzing measurements of albumin [ table 1 ] in four experimental periods , it was observed that there was an increase in the average group of animals sacrificed at 30 days after the induction of critical defect as compared to that in other groups , but the difference was not statistically significant . the average albumin in all experimental periods ranged between 4.1 and 4.4 g / dl , with great variability in the group with 30 days of experimentation . at 30 days of the experiment , a mean of 10.7 mg / dl calcium was detected , and the difference was statistically significant as compared to groups with 15 days ( p = 0.050 ) and 60 days of the experiment ( p = 0.048 ) [ table 1 ] . evaluating the behavior , there was a significant increase of calcium at 30 days post - operatively , decreasing the concentration to 60 days after the start of the intervention . despite the variation found ( 10.7 mg / dl ) , calcium levels were maintained within the reference values established by mitruka and rawnsley ( 7.2 - 13 mg / dl ) . as the calcium concentration remained constant , only in extreme circumstances such as malnutrition or hyperparathyroidism , the serum concentration of this mineral in its ionized form , the amount of calcium should always be interpreted together with the concentrations of albumin . table 1 shows the relation of the changes in the levels of calcium and albumin in the experimental periods . phosphorus levels did not vary between different follow - up times , averaging a concentration between 5 and 6 mg / dl in all experimental groups , being within the parameters set as normal ( 5.3 to 8.3 mg / dl ) with the 2:1 ratio of calcium and phosphorus , appropriate to the species under study that allows a good calcium absorption at the intestinal balance to maintain homeostasis . the mean levels of magnesium concentration [ table 1 ] reduced when groups were evaluated with longer post - intervention . after the first 15 days of induction of critical defect , the average magnesium concentration was 3.1 mg / dl , which significantly reduced ( p = 0.001 ) as compared that after 30 days of monitoring . however , the levels found during the experimental period were above the levels considered normal by nichols ( 1.6 mg / dl ) . the relationship between bone mineral dose and the time of experimentation was not modified in any of the parameters , and remained 1.9 - 2.35% for calcium , 8.7 - 9.8% for phosphorus , and 0.17 - 0.21% for magnesium throughout the experimental period . the ratio of bone mineral measurement with a time of trial does not change in any of the parameters , remaining 1.9 - 2.35% for calcium , 8.7 - 9.8% for phosphorus , and 0.17 - 0.21% for magnesium throughout the experimental period . noteworthy is that , at 60-day follow - up , there was a reduction in the percentage of phosphorus and magnesium and an increase in the percentage of calcium . micrographs stained with hematoxylin - eosin of control animals [ figure 2 ] at 15 days postoperatively and treated [ figure 3 ] at 30-day postoperatively showed loose connective tissue with inflammatory infiltrate acute presence of fibroblasts and bone tissue with osteocytes , with no change in cellularity . it was also demonstrated that complete removal was promoted by loose connective tissue [ figures 2 and 3 ] that hijacked the implanted material , preventing direct contact of material with the bone interface and thereby hindering the stimulus that could be promoted by the action of the lectin to change cellularity . therefore , the use of proteins that bind to carbohydrate residues has been proposed for the development and modulation of events such as communication , cellular differentiation , and proliferation . micrograph of bone tissue of rats submitted to the critical defect in the parietal bone ( h and e stain , 100 ) : control animal group at 15 day postoperatively micrograph of bone tissue of rats submitted to the critical defect in the parietal bone ( h and e stain , 100 ) : treated animal group at 30 day postoperatively the principle of bone regeneration is that the process of bone repair occurs through competition between bone cells and connective tissue colonization and aimed at filling the critical defect , which represents one of the principles of tissue engineering . , evaluating the ability of bone repair in critical calvarial defect in rats using a pool of bovine bone morphogenetic proteins linked to synthetic absorbable microgranular hydroxyapatite , histogicamente observed that in periods 1 to 3 months , the defects were filled with fibrous connective tissue and numerous foci of granulomatous foreign body around clusters of hydroxyapatite that inhibited bone formation . according to almeida et al . , bringing non - osteogenic cells in the area of the surgical defect prevents the migration of cells with osteogenic potential , directly interfering in the process of bone repair . similar finding we observed in another study by almeida et al . , that evaluated the effect of plumbum metallicum 30ch , a homeopathic medicine , on bone repair in jaws of rats without using a mechanical barrier and in the presence of muscle tissue in various histological sections . the degree of damage to the loose connective tissue adjacent to the bone defect interferes with the experimental model of bone injury . although the loose connective tissue and animal species in the study area is very slim , the same degree of interference in the repair of bone tissue was extremely high , preventing the direct action of cramoll-1,4 on bone tissue . it is concluded that there were no significant changes in the biochemical serum and bone in relation to the effect of induced trauma . despite the proven efficacy of the use of lectins in experiments on skin repair , with respect to the repair of bone tissue , cramoll-1,4 ( in irradiated gel formulation at a concentration of 300 g ) did not cause stimulation favoring the bone repair process , since there was direct interference of repair connective tissue that prevented direct contact of the implant with the bone interface .

context : regeneration corresponds to the replacement of damaged cells with ones that have the same morphology and function . for experimental evaluation of materials that may favor the process of bone healing , defects are created with dimensions that prevent spontaneous regeneration . for the development and use of new drugs , it is necessary to study its effects in vitro , which depends on the formulation , concentration , and rate of irradiation in vivo and the route and frequency of administration ; thus , it is possible to characterize the physiological and molecular mechanisms involved in the response and cellular effects.objective:the objective of this study was to assess the effect of cramoll-1,4 on the process of bone repair.materials and methods : a formulation of biopharmaceutical lectin cramoll-1,4 at a concentration of 300 mg/100 ml was applied in a single application via gamma radiation and its effect on the process of bone repair in rats was assessed.results:histologically , it was observed that the bone defect is coated by loose connective tissue rich in fibroblasts , providing a range similar to the thick bone original and competing with site of new bone formation . this prevented direct contact between the formulation and experimental bone tissue , as , despite its proven effectiveness in experiments on the repair of skin lesions , the formulation used did not promote bone stimulation that would have promoted the tissue repair process.conclusion:because of the direct interference of loose tissue repair that prevented direct contact of the implant with the bone interface , the formulation did not promote bone stimulation .

neuroendocrine lung tumors arise from a population of neuroendocrine cells normally present in the bronchoalveolar structures and are characterized by secretory activity and ability to take up and decarboxylate the amine precursors ( apud system cells ) . these neuroendocrine phenotypical and morphological characteristics are present within a broad spectrum of histologies of lung neuroendocrine tumors ( nets ) , from relatively indolent typical carcinoids ( tcs ) to histologically high - grade , biologically aggressive tumors , as large - cell neuroendocrine carcinomas ( lcnec ) and small - cell lung cancers . the spectrum of pulmonary nets , according to the 2004 world health organization ( who ) categorization , includes 4 subtypes characterized by increasing biologic aggressiveness : tcs and atypical carcinoids ( acs ) are categorized together as carcinoids , lcnec is considered a subgroup of large - cell carcinomas and small - cell lung carcinoma ( sclc ) as an independent category . bronchopulmonary ( bp ) tcs and acs are uncommon , representing 1 - 2% of all pulmonary neoplasms ; these variants are associated with relatively slow growth , and generally show a favorable outcome . the tc subtype is predominant ( 80 - 90% ) , and occurs most frequently in the 5th and 6th decades of life . the most important difference between typical and atypical form is represented by the mitotic index . tcs have < 2 mitoses per mm in 10 high - power fields ( hpf ) without signs of necrosis , while acs are characterized by 2 - 10 mitoses per mm/10 hpf and/or foci of necrosis . the lcnec and sclc subtypes are the most malignant of neuroendocrine lung tumors with a 5-year survival that , up to date , remains very poor . in particular , for the sclc form the necrosis is typically extensive and the mitotic rate is very high with > 10 mitoses/2 mm . nevertheless , diagnosis of bp carcinoids can be difficult and they may be mistaken for sclc . a review of pathologic material by an experienced pathologist is important prior to diagnosis and specific treatments in this type of tumors . in combination with the histologic appearance , the cell proliferation characterized by low labeling index ki67 ( mib1 ) < 20% seems to be the most useful marker to distinguish the low - grade from the high - grade malignancy subgroups within the bp nets . in particular , the immunoreactivity for nuclear markers ( especially ki67 ) is easily accessible and may be helpful in the differential diagnosis between tcs / acs and sclcs , high - grade nets being characterized by a proliferative cell fraction much higher than that of carcinoids ( mib1 > 50% ) . several peptide and amine markers , including chromogranin a ( cga ) , neuron - specific enolase ( nse ) , serotonin , synaptophysin , and adrenocorticotropic hormone ( acth ) , can provide us with further tools in order to better establish a differential diagnosis . molecular genetic changes may be useful as an adjunctive element to differentiate tcs from acs . retinoblastoma gene ( 13q13 ) and p53 ( 17p13 ) mutations , multiple endocrine neoplasia ( men ) 1 gene activation ( 11q13 ) , and telomerase activity are particularly frequent in acs if compared with tcs . we report a case of a young woman with misdiagnosis of bp net which has heavily influenced her clinical story . a 41-year - old symptomatic female patient , nonsmoker , following the onset of cough and low - grade fever despite empirical antibiotic therapy , underwent chest radiogram , which revealed an uneven area in the right lung , near the hilum . because symptoms persisted after empirical antibiotic therapy thorax ct scan documented a nodule in the right lung , near the hilum , 2 millimetric nodules in the left lung , in the lower lobe , and subcarinal lymphadenopathies . cytological examination of fine - needle aspiration specimens showed atypical cells immunohistochemistry - positive for cytokeratin mnf116 , indicative of infiltration of small - cell lung cancer . after 5 cycles of chemotherapy with cisplatin and etoposide and radiotherapy on mediastinum , the patient was referred to surgery ( sleeve bilobectomy , pericardial resection and mediastinal lymphadenectomy ) . histological examination showed an ac tumor ( ki67 > 2% ) with pathological staging pt2 n2 . during the follow - up , the patient was subjected to ct scan every 6 months and then every year , to inspect the 2 millimetric nodules in the controlateral lung . after 8 years , ct scan documented an increase in the size of 1 of the 2 nodules in the lower lobe of the left lung , confirmed by pet ( suv5 ) . histological examination documented tc ( ki67 < 2% ) , pt1 n1 as pathologic staging . ct and pet were negative for cancer , but blood test showed hypercalcemia ( 14 mg / dl ) . therefore , neck ultrasound and thyroid scintigraphy were performed , and both revealed an increase in size of the right parathyroid gland . the presence of 3 distinct histological types of bp nets in the same subject is unusual . sporadic lung carcinoids may occur as a component ( ~5% ) of the familial endocrine cancer syndrome multiple neuroendocrine neoplasia 1 ( men1 ) ; in contrast , in poorly differentiated lung nets ( sclc and lcnec ) , this condition was rarely identified . analyzing the patient 's family history , we learned that her mother had zollinger - ellison syndrome , a cousin had pancreatic neuroendocrine carcinoma and parathyroid adenoma and an uncle underwent surgery for a parathyroid adenoma . thus , the patient and her children will be subjected to genetic counseling and evaluation for men1 gene mutation . consistent with our hypothesis , our histological review documented ac on the first cytological diagnosis , with immunohistochemical positivity for cga , synaptophysin and ki67 : 5.3% , while it confirmed the diagnosis of acs and tcs , after lung surgery , according to who classification ( fig . 1 , fig this case report demonstrates that diagnosis by cytologic sampling can be confounding and it alone does not allow a correct and complete characterization of pulmonary tumors . it is also important that the diagnostic iter must be followed , as far as possible , in a specialized center , especially when we are faced with rare neoplastic diseases , as in this case .

bronchopulmonary neuroendocrine tumors are an uncommon group of neoplasms , accounting for about 20% of all lung carcinomas , arising from stem cells of the bronchial epithelium known as kulchitsky cells . in the past , these tumors were grouped among benign or less aggressive malignant pulmonary tumors . currently , according to the 2004 world health organization categorization , these tumors are separated into 4 subtypes characterized by increasing biologic aggressiveness : low - grade ( typical carcinoid ; tc ) , intermediate - grade ( atypical carcinoid ; ac ) and high - grade ( large - cell neuroendocrine carcinoma , lcnec , and small - cell lung carcinoma , sclc ) . they differ by morphologic , immunohistochemical and structural features . at histopathologic analysis , these tumors share progressive increase in a number of mitotic figures per 10 high - power fields and in the extent of necrosis , with tc having the lowest values and sclc having the highest . tcs and acs make up approximately 12% of all primary lung tumors . differentiating acs from tcs or lcnec and sclc is clinically important because the treatment modalities and prognoses for these types of tumors are different . we report a case of misdiagnosis of bronchopulmonary neuroendocrine tumor in a young woman which has heavily influenced her clinical history .

a community of people where each person has a characteristic ( for example , an opinion on a particular subject and this opinion can be expressed in a binary form , in favor ( @xmath13 ) or against ( @xmath14 ) a particular issue in question , and this opinion can be influenced by the vicinity of this individual ) can be modeled using some simple models as the equilibrium ising model @xcite that has become an excellent tool to study models of social application @xcite . many works these nature are well described in a thorough review @xcite , a more recent summary by stauffer @xcite and the following papers in these special issues on sociophysics in this journal . the majority - vote model ( mvm ) of oliveira @xcite is a nonequilibrium model of social interaction : individuals of a certain population make their decisions based on the opinion of the majority of their neighbors . this model has been studied for several years by various researchers in order to model social and economic systems @xcite in regular structures @xcite and various other complex networks @xcite . there are also applications to real elections in which similar models of opinion dynamics have been explored in the literature , such as arajo _ _ @xcite . in the present work , we study the critical properties of mvm with random noise on a square lattice @xmath15 . here , we start with each individual or agent having their characteristic noise @xmath16 randomly selected within a range from 0 to @xmath0 . thus each agent does not have an opinion in the presence of a constant noise @xmath0 as in the traditional mvm @xcite , but instead each agent has intrinsic resistance , @xmath16 , to the opinion of their neighborhood on @xmath15 . the effective dimension using the exponents ratio @xmath2 and @xmath3 is also determined for mvm with random noise . finally , the critical exponents calculated for this model are compared with the results obtained by oliveira @xcite . in the mvm on @xmath15 , the system dynamics traditional is as follows . initially , we assign a spin variable @xmath17 with values @xmath18 at each node of the lattice . at each step we try to spin flip a node . the flip is accepted with probability @xmath19 , \label{eq_1}\ ] ] where @xmath20 is the sign @xmath18 of @xmath21 if @xmath22 , @xmath23 if @xmath24 . to calculate @xmath25 our sum runs over the @xmath26 nearest neighbors of spin @xmath27 on square lattice . ( [ eq_1 ] ) means that with probability @xmath28 the spin will adopt the same state as the majority of its neighbors . the control parameter @xmath29 plays a role similar to the temperature in equilibrium systems : the smaller @xmath0 , the greater the probability of parallel aligning with the local majority . here , in order to make the model more realistic in a social context we associate to each agent its characteristic noise _ @xmath16_. thus the agent has not only opinion , but also an individual resistance to the opinion of this neighborhood . therefore , the new rate of reversal of the spin variable is @xmath30 , \label{eq_2}\ ] ] where the noise parameter _ @xmath16 _ , associated with the site @xmath27 , satisfies the probability distribution @xmath31 and takes real values randomly in the interval [ 0 , q ] . to study the critical behavior of the model we define the variable @xmath32 ( @xmath33 ) . in particular , we are interested in the magnetization @xmath34 , susceptibility @xmath35 and the reduced fourth - order cumulant @xmath36 [ eq - def ] @xmath37 @xmath38 @xmath39 where @xmath40 stands for a thermodynamic average . the results are averaged over the @xmath41 independent simulations . these quantities are functions of the noise parameter @xmath0 and obey the finite - size scaling relations [ eq - scal ] @xmath42 @xmath43 @xmath44 where @xmath45 , @xmath46 , and @xmath47 are the usual critical exponents , @xmath48 are the finite size scaling functions with @xmath49 being the scaling variable . therefore , from the size dependence of @xmath34 and @xmath35 we obtained the exponents @xmath2 and @xmath3 , respectively . the maximum value of susceptibility also scales as @xmath50 . moreover , the value of @xmath51 for which @xmath35 has a maximum is expected to scale with the lattice size @xmath52 as @xmath53 therefore , the relations and may be used to get the exponent @xmath4 . we also have applied the calculated exponents to the hyperscaling hypothesis @xmath54 in order to get the effective dimensionality , @xmath55 , and to improve the @xmath2 and @xmath3 exponents ratio for @xmath56 on @xmath15 . we performed monte carlo simulation on @xmath15 with various lattice sizes @xmath52 ( 100 , 200 , 300 , 400 , 500 and 1000 ) . we took @xmath57 monte carlo steps ( mcs ) to make the system reach the steady state , and then the time averages are estimated over the next @xmath57 mcs . one mcs is accomplished after all the @xmath58 spins are investigated whether they flip or not . the results are averaged over @xmath41 @xmath59 independent simulation runs for each lattice size and for given set of parameters @xmath60 . in figs . [ f1 ] , [ f2 ] , and [ f3 ] we show the dependence of the magnetization @xmath34 , susceptibility @xmath35 , and binder cumulant @xmath36 on the noise parameter @xmath0 , obtained from simulations on @xmath15 with @xmath52 ranging from @xmath61 to @xmath62 lattice size ( @xmath63 to @xmath64 sites ) . the shape of @xmath65 , @xmath66 , and @xmath67 curve , for a given value of @xmath52 , suggests the presence of a second - order phase transition in the system . the phase transition occurs at the critical value @xmath68 of the noise parameter @xmath0 . this parameter @xmath68 is estimated as the point where the @xmath69 curves for different lattice sizes @xmath52 intercept each other @xcite . then , we obtain @xmath10 and @xmath11 for @xmath15 . in fig . [ f4 ] we plot the dependence of the magnetization @xmath70 vs. the lattice size @xmath52 . the slope of curve corresponds to the exponent ratio @xmath2 according to eq . the obtained exponent is @xmath71 for our @xmath15 . the exponent ratio @xmath3 at @xmath5 and @xmath72 is obtained from the slope of the straight line with @xmath73 and @xmath74 , respectively as presented in fig . [ f5 ] for @xmath15 . to obtain the critical exponent @xmath4 , we used the scaling relation ( 6 ) . the calculated value of the exponent @xmath4 are @xmath9 for @xmath15 ( see fig . we plot @xmath75 versus @xmath76 in fig . [ f7 ] using the critical exponents @xmath77 and @xmath7 for lattice size @xmath78,@xmath79 , @xmath80 , and @xmath62 for @xmath15 . the good collapse of the curves for five different lattice sizes corroborates the estimate for @xmath68 and the critical exponents @xmath2 and @xmath4 . in fig . [ f8 ] we plot @xmath81 versus @xmath76 using the critical exponents @xmath82 and @xmath9 for lattice size @xmath78 , 400 , 500 , and 1000 for @xmath15 . again , the good collapse of the curves for five different lattice size corroborates the extimation for @xmath68 and the critical exponents @xmath3 and @xmath4 . finally , we remark that our mc results obtained on @xmath15 for mvm with random noise show that critical exponent ratios @xmath7 and @xmath82 are different from the results of mvm for regular lattice @xmath83 and @xmath84 @xcite and equilibrium 2d ising model @xcite . on the other hand , we show also that the critical exponent @xmath9 and binder cumulant @xmath11 are similar to the mvm for regular lattice @xcite . we also showed that the effective dimension @xmath55 ( within error bars ) is close to @xmath85 . the agreement in @xmath55 and @xmath4 but not in the two exponent ratios @xmath2 and @xmath3 remains to be explained . the author thanks d. stauffer for many suggestion and fruitful discussions during the development this work and also for reading this paper . we also acknowledge the brazilian agency cnpq for its financial support . this work also was supported the system sgi altix 1350 in the computational park cenapad.unicamp-usp , sp - brazil . l. onsager , phys . 65 , 117 ( 1944 ) ; b. kaufmann , phys . rev . * 76 * , 1232 ( 1949 ) . r. j. baxter , _ exactly solved models in statistical mechanics _ , london , academic press ( 1982 ) . b. latan , _ am . psychologist _ * 36 * , 343 ( 1981 ) . c. castellano , s. fortunato and v. loreto , rev . physics * 81 * , 591 ( 2009 ) . d. stauffer , j. stat . phys . * 151 * , 9 ( 2013 ) . m. j. oliveira , _ * 66 * 273 ( 1992 ) . g. zaklan , f. westerhoff and d. stauffer , _ arxiv:0801.2980 . _ ( 2008 ) , = _ j. econ . interact . coordination _ * 4 * , 1 ( 2008 ) . g. zaklan , f. w. s. lima and f. westerhoff , _ physica a _ * 387 * , 5857 ( 2008 ) . f. w. s. lima , _ journal of physics : conference series _ * 246 * , 012033 ( 2010 ) . lima , _ theoretical economics letters _ * 02 * , 87 ( 2012 ) . f. w. s. lima , _ international journal of modern physics c _ * 23 * , 1250079 ( 2012 ) . m. a. santos , s. teixeira , _ j. stat _ * 78 * , 963 ( 1995 ) . f. w. s. lima and k. malarz , _ int . c _ * 17 * , 1273 ( 2006 ) . j. c santos , f. w. s. lima , and k. malarz , _ physica _ a , * 390 * , 359 ( 2011 ) . f. w. s. lima , _ physica . a _ , * 391 * , 1753 ( 2012 ) . p. r. campos , v. m. oliveira , and f. g. b. moreira , _ phys . e _ * 67 * , 026104 ( 2003 ) . e. m. s. luz , f. w. s. lima , _ int . c _ * 18 * , 1251 ( 2007 ) . l. f. c. pereira and f. g. b. moreira , _ phys . e _ * 71 * , 016123 ( 2005 ) . f. w. s. lima , u. l. fulco , and r. n. c. filho , _ phys . * 71 * , 036105 ( 2005 ) . f. w. s. lima , _ int . c _ * 17 * , 1257 ( 2006 ) . f. w. s. lima , _ communications in computational physics _ * 2 * , 358 ( 2007 ) . f. w. s. lima , a. o. sousa , and m. a. sumour , _ physica a _ * 387 * , 3503 ( 2008 ) f. w. s. lima , a. a. moreira , a. d. arajo , _ phys . e _ * 86 * , 056109 ( 2012 ) . n. a. m. arajo , j. s. andrade jr . , h. j. herrmann , `` tactical voting in plurality elections '' , plos one * 5*(9 ) ( 2010 ) : e12446 . f. w. s. lima , t. hadzibeganovic and d. stauffer , _ physica a _ * 388 * , 4999 ( 2009 ) . t. qiu , t. hadzibeganovic , g. chen , l .- x . zhong and x .- r . computer phys . comm . _ * 181 * , 2057 ( 2010 ) . d. stauffer , m. hohnisch and s. pittnauer , _ physica a _ * 370 * , 734 ( 2006 ) . see also p. holme and m. e. j. newman , _ phys . rev . _ * 74 * , 056108 ( 2006 ) ; a. e. allahveryan and k. g. petrosyan , _ europhysics letters _ * 75 * , 908 ( 2006 ) . in preparation , `` majority - vote model with 2 and 3 states on shp networks '' . k. binder and d. w. heermann , _ monte carlo simulation in statistical phyics _ , ( springer verlag , 1988 ) .

we study a nonequilibrium model with up - down symmetry and a noise parameter @xmath0 known as majority - vote model of m.j . oliveira @xmath1 with heterogeneous agents on square lattice . by monte carlo simulations and finite - size scaling relations the critical exponents @xmath2 , @xmath3 , and @xmath4 and points @xmath5 and @xmath6 are obtained . after extensive simulations , we obtain @xmath7 , @xmath8 , and @xmath9 . the calculated values of the critical noise parameter and binder cumulant are @xmath10 and @xmath11 . within the error bars , the exponents obey the relation @xmath12 and the results presented here demonstrate that the majority - vote model heterogeneous agents belongs to a different universality class than the nonequilibrium majority - vote models with homogeneous agents on square lattice .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Active Community Transportation Act of 2010''. SEC. 2. FINDINGS. Congress finds the following: (1) Nearly half of the trips taken in the United States are within a 20-minute bicycle ride, and a quarter of such trips are within a 20-minute walk. (2) Approximately 90 percent of public transportation trips are accessed by walking or bicycling. (3) More than 100 communities across the Nation have adopted complete streets policies, thereby proving the commitment of these communities to creating streets that are safe and convenient for users of all ages and abilities, including those who are walking, bicycling, taking public transportation, or driving. (4) Communities that invest in active transportation infrastructure experience significant increases in bicycling and walking rates over time, and such investments are in strong demand because they enhance the livability of communities. (5) The communities that perform best in encouraging active transportation create interconnected systems that make it convenient and safe to travel on foot or by bicycle to destinations on a routine basis. (6) Achieving a mode shift to active transportation within a community requires intensive, concentrated funding of active transportation systems rather than discrete, piecemeal projects. (7) Increased use of active transportation leads to reductions in traffic congestion, greenhouse gas emissions, vehicle miles traveled, oil dependence, air pollution, and obesity and diseases associated with physical inactivity. (8) Given the contribution that active transportation makes to these national policy goals, and the opportunity active transportation provides to accommodate short trips at the least cost to the public and individuals, funding of active transportation is one of the most strategic and cost effective Federal transportation investments available. SEC. 3. DEFINITIONS. In this Act, the following definitions apply: (1) Active transportation.--The term ``active transportation'' means mobility options powered solely by human energy, such as bicycling and walking. (2) Indian tribe.--The term ``Indian tribe'' has the meaning given that term in section 4(e) of Indian Self- Determination and Education Assistance Act (25 U.S.C. 450b(e)). (3) Program.--The term ``program'' means the active transportation investment program established under section 4. SEC. 4. ACTIVE TRANSPORTATION INFRASTRUCTURE INVESTMENT PROGRAM. (a) In General.--The Secretary of Transportation shall carry out an active transportation investment program in accordance with the requirements of this section. (b) Purpose.--The purpose of the program shall be to encourage a mode shift to active transportation within selected communities by providing safe and convenient opportunities to bicycle and walk for routine travel. (c) Selection of Communities.-- (1) Applications.--A community seeking to participate in the program shall submit to the Secretary an application that is in such form and contains such information as the Secretary may require. (2) Initial and additional selections.-- (A) Initial selections.--The Secretary shall select initial communities to participate in the program. Such communities shall participate in the program in each of fiscal years 2011 through 2015. (B) Additional selections.--Following the initial selections under subparagraph (A), the Secretary shall select additional communities to participate in the program. Such communities shall participate in the program in each of fiscal years 2013 through 2015. (3) Criteria.-- (A) In general.--In selecting communities to participate in the program, the Secretary shall consider, at a minimum, the extent to which a community-- (i) provides a plan for development of walking and bicycling infrastructure that is likely to contribute to a significant transportation mode shift to walking and bicycling; (ii) demonstrates broad community support that will facilitate successful and expeditious implementation; (iii) demonstrates a cohesive plan in which noninfrastructure elements, where proposed, reinforce achievement of the purpose of the program; (iv) provides evidence of regulatory or financial incentives or community design policies that facilitate significant increases in bicycling or walking; and (v) commits State, local, or eligible Federal matching funds, in addition to Federal funds made available under this section, to projects eligible for assistance under this section. (B) Strategic priorities that facilitate success.-- For purposes of subparagraph (A)(i), strategic priorities that facilitate success in increasing walking and bicycling include effective plans-- (i) to create a network of active transportation facilities connecting neighborhoods with destinations such as workplaces, schools, residences, businesses, recreation areas, and other community activity centers; (ii) to integrate active transportation facilities with transit services, where available, to improve access to public transportation; and (iii) to deliver safe, convenient, cost- effective mobility via walking and bicycling. (C) Indicators of community support.--For purposes of subparagraph (A)(ii), indicators of community support include-- (i) the use of public input in the development of transportation plans; and (ii) the commitment of community leaders to the success and timely implementation of projects eligible for assistance under this section. (d) Grants.-- (1) In general.--The Secretary shall make grants to each community selected to participate in the program. (2) Recipients.--A recipient of a grant representing a community under the program shall be a local or regional governmental organization, multi-county special district, or Indian tribe that the Secretary determines is suitably equipped and organized to carry out the objectives and requirements of this section. Such organizations include metropolitan planning organizations and other regional planning organizations. (3) Subrecipients.--A recipient of a grant under the program may suballocate funds from the grant to a nonprofit organization to carry out the purposes of the program. (4) Inclusion of certain communities.--To fulfill the Nation's need to achieve and document mode shift to bicycling and walking over time, the 4 communities that received pilot funding under section 1807 of SAFETEA-LU (119 Stat. 1460) may be among the communities selected by the Secretary under subsection (c). (5) Grants amounts.-- (A) In general.--The Secretary may make a grant as low as $5,000,000 and as high as $15,000,000 per fiscal year for a community participating in the program. The Secretary shall ensure that grant awards under the program are sufficiently high to enable a mode shift to active transportation. (B) Justification for larger grants.--Subject to the $15,000,000 per fiscal year limit set forth in subparagraph (A), the Secretary may justify a grant in a higher amount for a community under the program based on the population served, greater opportunities to shift trips to bicycling and walking, or use of innovative design features. (e) Eligible Projects.--Grants made to communities under this section shall be used for one or more of the following purposes: (1) To carry out projects to construct networks of active transportation infrastructure facilities, including sidewalks, bikeways, and pedestrian and bicycle trails, that connect people with public transportation, workplaces, schools, residences, businesses, recreation areas, and other community activity centers. (2) To carry out projects to provide for bicycle boxes, cycle tracks, bicycle boulevards, dual traffic signals, and bicycle sharing stations. (3) To carry out projects to restore and upgrade current active transportation infrastructure facilities. (4) To carry out projects to support educational activities, safety-oriented activities, and technical assistance to further the purpose of the program. (f) Program Measures.--In carrying out the program, the Secretary shall develop statistical information on changes in motor vehicle, active transportation, and public transportation usage in communities participating in the program and assess how the changes impact congestion and energy usage, impact the frequency of bicycling and walking, and impact health, safety, and the environment. In addition, the Secretary shall develop interim measures of progress, which may include indicators of public engagement, educational outcomes, and project advancement into planning and development. (g) Deadlines.-- (1) Request for applications.--Not later than 60 days after the date of enactment of this Act, the Secretary shall publish in the Federal Register a request for applications pursuant to subsection (c)(1). (2) Selection of initial communities.--Not later than 180 days after such date of enactment, the Secretary shall select initial communities to participate in the program under subsection (c)(2)(A). (3) Selection of additional communities.--Not later than September 30, 2012, the Secretary shall select additional communities to participate in the program under subsection (c)(2)(B). (4) Grants.--The Secretary shall make grants to selected to participate in the program under subsection (c)-- (A) for fiscal year 2011, not later than the later of-- (i) the 60th day after the date of the selection of communities under subsection (c)(2)(A); and (ii) the 30th day of the fiscal year; and (B) for each of fiscal years 2012 through 2015, not later than 30th day of the fiscal year. (h) Reports.-- (1) In general.--The Secretary shall submit to Congress-- (A) an interim report on progress made under the program not later than September 30, 2014; and (B) a final report on progress made under the program not later than September 30, 2016. (2) Contents.--Each report submitted under paragraph (1) shall include the Secretary's findings concerning the best practices of communities participating in the program and the impediments experienced by such communities relating to program development and achieving a mode shift to active transportation. (i) Funding.-- (1) Authorization of appropriations.--There is authorized to be appropriated out of the Highway Trust Fund (other than the Mass Transit Account) to carry out this section-- (A) $300,000,000 for fiscal year 2011; (B) $300,000,000 for fiscal year 2012; (C) $466,666,666 for fiscal year 2013; (D) $466,666,666 for fiscal year 2014; and (E) $466,666,668 for fiscal year 2015. (2) Contract authority.--Funds authorized to be appropriated by this section shall be available for obligation and administered in the same manner as if the funds were apportioned under chapter 1 of title 23, United States Code, except that the Federal share of the cost of a project carried out using the funds shall be 100 percent, and the funds shall remain available until expended and shall not be transferable. (3) Administrative costs.-- (A) Set aside.--Each fiscal year, the Secretary shall set aside not more than 1.5 percent of the funds made available to carry out this section to cover the costs of administrative, research, technical assistance, communications, and training activities under the program. (B) Contracts and other agreements.--The Secretary may enter into contracts with for-profit organizations, or contracts, partnerships, or cooperative agreements with other government agencies, institutions of higher learning, or nonprofit organizations, to perform activities with amounts set aside under subparagraph (A). The Federal share of the cost of such activities may be up to 100 percent. (C) Limitation on statutory construction.--Nothing in this paragraph may be construed to prohibit a community from receiving research or other funds under title 23 or 49, United States Code. (j) Treatment of Projects.-- (1) Noninfrastructure projects.--Noninfrastructure projects and infrastructure projects that do not involve or lead directly to construction assisted under this subsection shall not be treated as projects on a Federal-aid system under chapter 1 of title 23, United States Code. (2) Infrastructure projects.--Not later than one year after the date of enactment of this Act, the Secretary shall develop regulations or guidance (or both) for Federal-aid projects under this section that encourages the use of the programmatic categorical exclusion, expedited procurement techniques, and other best practices to facilitate productive and timely expenditure for projects that are small, low impact, and constructed within an existing built environment. (3) State processes.--The Secretary shall work with State departments of transportation to ensure that any guidance or regulation developed under paragraph (2) is being implemented by States and the Federal Highway Administration consistently to avoid unnecessary delays in implementing projects and to ensure the effective use of Federal dollars. (k) Assistance to Indian Tribes.--Notwithstanding any other provision of law, the Secretary may enter into grants agreements, self- determination contracts, and self-governance compacts under the authority of the Indian Self-Determination and Education Assistance Act (25 U.S.C. 450 et seq.) with eligible Indian tribes to carry out the purposes of this Act, and such grant agreements, self-determination contracts, and self-governance compacts shall be administered in accordance with that Act.

Active Community Transportation Act of 2010 - Directs the Secretary of Transportation to carry out an active transportation investment program to encourage a mode shift to active transportation within selected communities that have development plans that provide safe and convenient opportunities to travel by bicycling and walking. Requires the Secretary to make grants to communities through local or regional governmental organizations, multi-county special districts, or Indian tribes to carry out active transportation (bicycling and walking) infrastructure projects that connect people with public transportation, workplaces, residences, businesses, recreation areas, and other community activity centers.

adult education about several health care topics is essential to improve health care behavior and self - management as well as reduce risky behavior . such topics include fall prevention , nutrition , and alcohol use.13 according to the world health organization , health education not only means conveying verbal or written information but also means promoting the motivation , skills , and confidence of people so that they take action to improve their health.4 one of the health strategies of the european union , which supports this aspect of health education , is the empowerment of people.5 in older people , age - related conditions and the related decline in physical and cognitive functions require that they receive appropriate education to continue living as actively and independently as possible . however , health education in older people , especially in frail , older nursing home residents , is challenging . the first challenge is due to the cognitive decline observed in older people due to aging.6 according to the results of cognitive psychology research , older people process information more slowly , have less cognitive flexibility ( eg , are less willing to alter their judgments ) , and have lower abilities to think divergently ( ie , to generate alternative explanations or solutions ) . in addition , the working memory capacity and the ability to focus on specific information decline as people age.6 the second challenge to educating older people is that many prefer not to be actively involved in treatment , self - care , and decision making.79 this preference for the passive role may be their way of avoiding taking responsibility for undesirable events or incorrect decisions.10 in addition , older people commonly hold the opinion that undesirable events ( such as falls ) are inevitable and unavoidable.911 although many older people perform regular physical activity to stay active and have positive attitudes toward personal health care , some of them and especially frail nursing home residents believe that certain interventions ( such as bodily exercise ) are not effective due to reduced physical ability.12 for these reasons , a great deal of effort must be invested to support the empowerment of older people to increase their benefits from educational interventions . by becoming empowered , people can enjoy their life to the greatest extent possible on the basis of their own choices.13 to achieve empowerment , people must obtain knowledge that is related to individual needs and expectations.14,15 gibson defined empowerment as : a process of recognizing , promoting and enhancing people s ability to meet their own needs , solve their own problems and mobilize the necessary resources in order to feel in control of their own lives.16 a process of recognizing , promoting and enhancing people s ability to meet their own needs , solve their own problems and mobilize the necessary resources in order to feel in control of their own lives.16 empowerment based - interventions are based on strong guiding principles such as self - determination and autonomy.17 by providing empowering care , nurses help increase the residents independence and their feelings of autonomy.18 the nurses can not give them these feelings but can support the residents during the process of empowerment.15 in patient education , therefore , empowerment is both a process and an outcome . during the empowerment process , residents increase their abilities to act autonomously , think critically , and gain an enhanced sense of self - efficacy as a result.19 self - efficacy is a strong predictor of self - care behavior , which influences behavior both directly and indirectly by influencing goal setting , outcome expectations , and perception of facilitators and impediments.20 although the presence of empowerment care is a significant predictor of the quality of life,21 empowerment of nursing home residents is seldom discussed in research articles.22 however , focusing on empowerment may be the key to educating nursing home residents effectively . to the best of our knowledge , no systematic review is currently available that describes educational interventions used to specifically empower nursing home residents . a recent review was published on person - centered care in aged - care facilities , where a focus was placed on interventions to enhance residents autonomy , choices , sense of personal control , independence , and interactions , but staff training , organizational changes , and the creation of a positive atmosphere were primary goals rather than resident education.23 therefore , the aim of this research was to identify educational interventions that could be used to empower nursing home residents . the following research questions are asked : which educational interventions are used in intervention studies to empower nursing home residents and how effectively do educational interventions empower nursing home residents ? the pubmed , cinahl , central , psycinfo , and embase databases were screened to select articles that had been published during this century ( from january 1 , 2000 to april 1 , 2016 ) , selecting current studies that had been written in english or german . the search was limited to clinical trials ( eg , clinical trials , controlled clinical trials , and randomized clinical trials ) in order to target intervention studies . search terms ( shown in table 1 ) were used with truncations and the boolean operators or ( horizontal terms ) and and ( vertical combinations ) . the outcome terms were based on outcome measures that focused on empowerment in patient education.1419 in addition , a manual search of reference lists of selected papers and reviews on the topics of empowerment and patient education was performed to identify additional relevant articles.6,2325 to identify gray literature , a search was conducted in the sigle and google scholar to a page depth of 12 , using the keywords empower , self - efficacy , self - determination , autonomy , and resident . in order to be included , studies had to meet the following criteria : included older people ( from 65 years on)addressed residents living in nursing homes or similar long - term institutional settingsdescribed any educational intervention that implied that information was provided , and/or motivation , skills , and confidence necessary to take action to improve health were fostered4focused on outcomes related to empowerment through patient education , and specifically , on its influence on knowledge , self - efficacy , self - determination , autonomy , self - care behavior , self - care activity , self - care management , independency , mastery , empowerment , and outcome expectations . included older people ( from 65 years on ) addressed residents living in nursing homes or similar long - term institutional settings described any educational intervention that implied that information was provided , and/or motivation , skills , and confidence necessary to take action to improve health were fostered4 focused on outcomes related to empowerment through patient education , and specifically , on its influence on knowledge , self - efficacy , self - determination , autonomy , self - care behavior , self - care activity , self - care management , independency , mastery , empowerment , and outcome expectations . according to the types of studies identified through the literature review , an additional focus was placed on intervention studies ( clinical trials ) to investigate the effects of educational interventions on outcomes related to empowerment . studies were excluded if they were carried out in hospitals , institutions for mentally disabled people , or in community - dwelling populations . studies that were conducted in mixed settings ( eg , nursing homes and day centers ) were excluded if it was not possible to extract data about the population of interest . studies that described outcomes that were not explicitly related to empowerment , such as compliance with treatment or physical parameters ( eg , grip strength ) , and that did not consider self - care or independency were also excluded.24 interventions that could be used to empower or educate ( nursing ) staff exclusively were considered to be beyond the scope of this review and were excluded . intervention studies with a control group were assessed using the critical appraisal worksheet for therapy studies.26 the level of evidence was assigned according to the oxford centre for evidence - based medicine ( ocebm ) levels of evidence working group ( table 2).27 to appraise case - series studies , the three - minute checklist was used.28 there is no unity in the classification of case series ( also called time series ) . according to melnyk and fineout - overholt , they belong to quasi - experimental designs ( intervention studies ) ; in contrast , chan and bhandari assign them to observational studies.28,29 because they are mentioned in the evidence hierarchy of the ocebm levels of evidence working group , case series were handled as intervention studies in this review and not excluded.27 data were extracted about the design , participants , type of intervention ( including the application of the intervention ) , control of the intervention , outcome measures , and the duration of the study , using the cochrane review data extraction method , from each intervention study included.30 the results of the studies were grouped according to the main empowering outcomes identified , and the effects were presented as p - values ( if possible ) . in order to be included , studies had to meet the following criteria : included older people ( from 65 years on)addressed residents living in nursing homes or similar long - term institutional settingsdescribed any educational intervention that implied that information was provided , and/or motivation , skills , and confidence necessary to take action to improve health were fostered4focused on outcomes related to empowerment through patient education , and specifically , on its influence on knowledge , self - efficacy , self - determination , autonomy , self - care behavior , self - care activity , self - care management , independency , mastery , empowerment , and outcome expectations . included older people ( from 65 years on ) addressed residents living in nursing homes or similar long - term institutional settings described any educational intervention that implied that information was provided , and/or motivation , skills , and confidence necessary to take action to improve health were fostered4 focused on outcomes related to empowerment through patient education , and specifically , on its influence on knowledge , self - efficacy , self - determination , autonomy , self - care behavior , self - care activity , self - care management , independency , mastery , empowerment , and outcome expectations . according to the types of studies identified through the literature review , an additional focus was placed on intervention studies ( clinical trials ) to investigate the effects of educational interventions on outcomes related to empowerment . studies were excluded if they were carried out in hospitals , institutions for mentally disabled people , or in community - dwelling populations . studies that were conducted in mixed settings ( eg , nursing homes and day centers ) were excluded if it was not possible to extract data about the population of interest . studies that described outcomes that were not explicitly related to empowerment , such as compliance with treatment or physical parameters ( eg , grip strength ) , and that did not consider self - care or independency were also excluded.24 interventions that could be used to empower or educate ( nursing ) staff exclusively were considered to be beyond the scope of this review and were excluded . intervention studies with a control group were assessed using the critical appraisal worksheet for therapy studies.26 the level of evidence was assigned according to the oxford centre for evidence - based medicine ( ocebm ) levels of evidence working group ( table 2).27 to appraise case - series studies , the three - minute checklist was used.28 there is no unity in the classification of case series ( also called time series ) . according to melnyk and fineout - overholt , they belong to quasi - experimental designs ( intervention studies ) ; in contrast , chan and bhandari assign them to observational studies.28,29 because they are mentioned in the evidence hierarchy of the ocebm levels of evidence working group , case series were handled as intervention studies in this review and not excluded.27 data were extracted about the design , participants , type of intervention ( including the application of the intervention ) , control of the intervention , outcome measures , and the duration of the study , using the cochrane review data extraction method , from each intervention study included.30 the results of the studies were grouped according to the main empowering outcomes identified , and the effects were presented as p - values ( if possible ) . a total of 427 studies were identified as a result of the systematic database search . in addition , four studies were identified by screening the reference lists of the included studies and reviews . the sigle and google scholar search did not lead to the identification of additional relevant articles . after removing duplicates , 258 articles were excluded on the basis of their titles and abstracts because they did not address the research question or inclusion criteria . the full texts of the remaining 26 articles were examined in detail , eleven of which fulfilled the inclusion criteria . one study was subsequently excluded because no data on group comparison were presented in the results and the before-and-after comparison data described were not traceable.31 in total , ten studies were included that directly addressed the research question . a flow diagram of the study selection based on the prisma statement is presented in figure 1.32 of the ten intervention studies , seven were randomized controlled trials . four of the studies used cluster randomization,3336 another three used individual randomization,3739 and three were quasi - experimental studies : a clinical controlled trial without randomization and two case - series studies.4042 seven studies had been conducted with residents living in nursing homes,33,3742 and three , in assisted living facilities and residential care homes.3436 the sample size ranged from 21 to 1,042 residents . the majority of the residents included in the studies were female ( between 64 and 93 ) , and the mean age of the participants ranged from 77 to 88 years , with the exception of the study by bonanni et al where no mean age was described.42 in nearly all trials , residents with cognitive impairments ( including mild stages of dementia ) were included.33,3539,41,42 the interventions were performed every day ( integrated into nursing daily practice ) , one to two times a week , or five times over a 3-month period , and were made for periods of 3 weeks to 12 months . the interventions performed were all complex and differed to varying extents but also shared similarities . in two interventions , interactive group education sessions were held to provide knowledge on disease and self - management strategies.39,40 these were supported by customized counseling based on needs and preferences . in the group sessions described by park et al , personal experiences were also discussed.40 in three studies , restorative care interventions were used to educate residents , and in one study , function - focused care interventions.33,34,41,42 these interventions , which used motivational strategies , were designed to help residents attain and maintain their highest possible functional and physical status . in the intervention published by resnick et al , for example , residents were encouraged to do simple tasks by themselves , such as getting into bed . enough time was given to perform the tasks , give step - by - step cues on how to do them , and when needed , to guide the residents to facilitate their independent activity.33 motivational strategies such as positive feedback , motivational self - management tips , and motivational interviews were also core concepts of other interventions.39,40 another strategy that was commonly used was goal setting on the basis of residents needs and motivation levels and the development of an individually tailored plan to meet the goals.3336,3941 park et al also identified barriers that hindered the action plan.40 problem - solving skill training , helping residents identify problems , set goals , and solve problems in small steps , and training in reasoning strategies were main interventions used by williams et al to promote the self - care level.35 acquired reasoning strategies were applied during everyday situations and included scanning information , reading aloud , underlining or highlighting key information , and breaking information into smaller pieces.35 the interventions provided by andresen et al were based on the residents individual wishes , and therefore , difficult to extrapolate.37 printed educational material was used in addition to verbal education in three studies , and in two studies , posters were placed in the residents rooms to act as reminders and motivators.3335,40,41 most interventions were carried out by nursing staff . in the restorative care interventions as well as the function - focused care interventions , an emphasis was placed on educating nursing staff about motivational techniques based on self - efficacy and supplying nurses with specific training to support the nursing staff while introducing motivational interventions.33,34,41,42 a multi - professional approach , whereby the interdisciplinary team , residents , and families were educated , was used in the study by resnick et al.34 in one study , the intervention was also delivered by occupational therapists.36 the short descriptions of the studies included are given in table 3 . according to the levels of evidence , six studies were assigned as level 2 studies , two as level 3 studies , and two as level 4 studies.27 the quality of the included studies , which included control groups , is reported in table 4 , and the quality of the case - series studies , in table 5 . the randomization of residents / clusters to the groups was described in all level 2 studies . in two studies , randomization was conducted by the use of computer - generated random numbers , and in the others , by statistician - generated random numbers and by lot.3537,39 resnick et al did not describe how the randomization was conducted.33,34 allocation concealment was described in the studies of sackley et al , andresen et al , and park and chang.36,37,39 the baseline characteristics of the intervention and control groups were comparable in four level 2 studies.33,36,37,39 in the study by williams et al , significant differences between the groups were found in one primary outcome ( every day problems test for cognitively challenged elders score ) , but these were controlled in analysis models that were used to examine change over time.35 significant differences with regard to the outcomes expectations and number of diagnoses were detected in the study by resnick et al . according to authors , the results did not differ when the outcomes had been controlled.34 in all level 2 studies , there was no indication that participants in different groups received additional treatments apart from the interventions . in the study conducted by andresen et al , the authors mentioned that it might be challenging for the staff to distinguish participants from one another in terms of intervention , which may have biased the results.37 the analyses were conducted according to an intention - to - treat paradigm in several trials , but a comprehensible description of how the paradigm was performed was only available in two trials.34,37 the data analyses described in the remaining studies were designated as per - protocol analyses , since no descriptions of the intention - to - treat paradigm were made , and the dropouts were evidently not included in the follow - up analyses.33,35,36,38,39 blinding of the outcome assessor was described in four trials.33,36,37,39 the study by park et al was assigned as a level 3 study because no randomization was conducted . as there were no dropouts from this study , an intention - to - treat analytical method is presumed to have been used.40 the study by vinsnes et al had to be downgraded due to the presence of several serious flaws , such as the fact that no baseline characteristics were illustrated.38 there were several limitations to the study by bonanni et al , such as the lack of information about the inclusion and exclusion criteria and the number of residents included in the outcome analysis.42 empowering outcomes addressed in the intervention studies could be categorized into self - efficacy , self - care activities / management / behavior , autonomy , and outcome expectations . self - efficacy could be significantly improved by interventions that included interactive group education and individually tailored counseling based on needs and preferences.39,40 the restorative care and function - focused care interventions had no significant effects on residents self - efficacy.33,34,41 outcomes according to self - care were those most commonly examined in the intervention studies . these could also be significantly improved by group education and individual counseling , and in addition , self - care competencies and skills in everyday problem - solving improved significantly by conducting reasoning exercises and training in problem - solving.35,39,40 a long - term effect on physical function in activities of daily living ( adls ) could be detected as a result of function - focused care interventions , but the effect did not immediately take place after providing the intervention.34 bonanni et al reported an improvement in the performance of adls during the 3- and 6-month follow - up , but no p - value was stated.42 no significant improvement in self - care was observed as a result of restorative care interventions , occupational therapy intervention , and physical activity and adl training designed to enhance independency in toilet habits.33,36,38,41 neither perceived autonomy nor outcome expectations could be significantly improved by any educational intervention.33,34,37,41 the main results of the interventions are presented in table 6 . four of the studies used cluster randomization,3336 another three used individual randomization,3739 and three were quasi - experimental studies : a clinical controlled trial without randomization and two case - series studies.4042 seven studies had been conducted with residents living in nursing homes,33,3742 and three , in assisted living facilities and residential care homes.3436 the sample size ranged from 21 to 1,042 residents . the majority of the residents included in the studies were female ( between 64 and 93 ) , and the mean age of the participants ranged from 77 to 88 years , with the exception of the study by bonanni et al where no mean age was described.42 in nearly all trials , residents with cognitive impairments ( including mild stages of dementia ) were included.33,3539,41,42 the interventions were performed every day ( integrated into nursing daily practice ) , one to two times a week , or five times over a 3-month period , and were made for periods of 3 weeks to 12 months . the interventions performed were all complex and differed to varying extents but also shared similarities . in two interventions , interactive group education sessions were held to provide knowledge on disease and self - management strategies.39,40 these were supported by customized counseling based on needs and preferences . in the group sessions described by park et al , personal experiences were also discussed.40 in three studies , restorative care interventions were used to educate residents , and in one study , function - focused care interventions.33,34,41,42 these interventions , which used motivational strategies , were designed to help residents attain and maintain their highest possible functional and physical status . in the intervention published by resnick et al , for example , residents were encouraged to do simple tasks by themselves , such as getting into bed . enough time was given to perform the tasks , give step - by - step cues on how to do them , and when needed , to guide the residents to facilitate their independent activity.33 motivational strategies such as positive feedback , motivational self - management tips , and motivational interviews were also core concepts of other interventions.39,40 another strategy that was commonly used was goal setting on the basis of residents needs and motivation levels and the development of an individually tailored plan to meet the goals.3336,3941 park et al also identified barriers that hindered the action plan.40 problem - solving skill training , helping residents identify problems , set goals , and solve problems in small steps , and training in reasoning strategies were main interventions used by williams et al to promote the self - care level.35 acquired reasoning strategies were applied during everyday situations and included scanning information , reading aloud , underlining or highlighting key information , and breaking information into smaller pieces.35 the interventions provided by andresen et al were based on the residents individual wishes , and therefore , difficult to extrapolate.37 printed educational material was used in addition to verbal education in three studies , and in two studies , posters were placed in the residents rooms to act as reminders and motivators.3335,40,41 most interventions were carried out by nursing staff . in the restorative care interventions as well as the function - focused care interventions , an emphasis was placed on educating nursing staff about motivational techniques based on self - efficacy and supplying nurses with specific training to support the nursing staff while introducing motivational interventions.33,34,41,42 a multi - professional approach , whereby the interdisciplinary team , residents , and families were educated , was used in the study by resnick et al.34 in one study , the intervention was also delivered by occupational therapists.36 the short descriptions of the studies included are given in table 3 . according to the levels of evidence , six studies were assigned as level 2 studies , two as level 3 studies , and two as level 4 studies.27 the quality of the included studies , which included control groups , is reported in table 4 , and the quality of the case - series studies , in table 5 . the randomization of residents / clusters to the groups was described in all level 2 studies . in two studies , randomization was conducted by the use of computer - generated random numbers , and in the others , by statistician - generated random numbers and by lot.3537,39 resnick et al did not describe how the randomization was conducted.33,34 allocation concealment was described in the studies of sackley et al , andresen et al , and park and chang.36,37,39 the baseline characteristics of the intervention and control groups were comparable in four level 2 studies.33,36,37,39 in the study by williams et al , significant differences between the groups were found in one primary outcome ( every day problems test for cognitively challenged elders score ) , but these were controlled in analysis models that were used to examine change over time.35 significant differences with regard to the outcomes expectations and number of diagnoses were detected in the study by resnick et al . according to authors , the results did not differ when the outcomes had been controlled.34 in all level 2 studies , there was no indication that participants in different groups received additional treatments apart from the interventions . in the study conducted by andresen et al , the authors mentioned that it might be challenging for the staff to distinguish participants from one another in terms of intervention , which may have biased the results.37 the analyses were conducted according to an intention - to - treat paradigm in several trials , but a comprehensible description of how the paradigm was performed was only available in two trials.34,37 the data analyses described in the remaining studies were designated as per - protocol analyses , since no descriptions of the intention - to - treat paradigm were made , and the dropouts were evidently not included in the follow - up analyses.33,35,36,38,39 blinding of the outcome assessor was described in four trials.33,36,37,39 the study by park et al was assigned as a level 3 study because no randomization was conducted . as there were no dropouts from this study , an intention - to - treat analytical method is presumed to have been used.40 the study by vinsnes et al had to be downgraded due to the presence of several serious flaws , such as the fact that no baseline characteristics were illustrated.38 there were several limitations to the study by bonanni et al , such as the lack of information about the inclusion and exclusion criteria and the number of residents included in the outcome analysis.42 empowering outcomes addressed in the intervention studies could be categorized into self - efficacy , self - care activities / management / behavior , autonomy , and outcome expectations . self - efficacy could be significantly improved by interventions that included interactive group education and individually tailored counseling based on needs and preferences.39,40 the restorative care and function - focused care interventions had no significant effects on residents self - efficacy.33,34,41 outcomes according to self - care were those most commonly examined in the intervention studies . these could also be significantly improved by group education and individual counseling , and in addition , self - care competencies and skills in everyday problem - solving improved significantly by conducting reasoning exercises and training in problem - solving.35,39,40 a long - term effect on physical function in activities of daily living ( adls ) could be detected as a result of function - focused care interventions , but the effect did not immediately take place after providing the intervention.34 bonanni et al reported an improvement in the performance of adls during the 3- and 6-month follow - up , but no p - value was stated.42 no significant improvement in self - care was observed as a result of restorative care interventions , occupational therapy intervention , and physical activity and adl training designed to enhance independency in toilet habits.33,36,38,41 neither perceived autonomy nor outcome expectations could be significantly improved by any educational intervention.33,34,37,41 the main results of the interventions are presented in table 6 . only a few studies could be identified that described educational interventions to empower nursing home residents , citing mainly good - to - moderate evidence . however , despite the low number of studies identified , meaningful preliminary findings can be summarized . the results of our findings are shown in figure 2 in the form of preliminary recommendations . several intervention studies of good quality demonstrated that older nursing home residents can be effectively educated to achieve significant effects , mostly with regard to outcomes related to self - care behavior . effective interventions were quite variable , but all interventions were ( at least in part ) individually tailored , interactive , continuous ( ie , not conducted at a single time point ) , encouraging , and motivational . these seem to be the most important and effective strategies to use when educating older residents . one core strategy that was used in several studies was to motivate and encourage residents . providing positive feedback can strengthen the residents personal resource and reduce barriers that hinder their mastery of a task or independence.24 qualitative studies have shown that many nursing home residents lack confidence to do tasks by themselves , and that positive reinforcement is needed.9,10 in order to be able to motivate and encourage residents , nurses must be themselves motivated and empowered.43 education of the nursing staff on motivational and encouraging techniques was part of the intervention studies by resnick et al.33,34 however , these motivational and encouraging techniques alone can not significantly improve self - efficacy , as the studies by resnick et al have shown.33,34 by additionally setting individually tailored goals and developing strategic plans with residents based on their needs , significant improvement in self - efficacy could be reached.39,40 this combination of strategies may be crucial to affect self - efficacy . although the high - quality study by andresen et al did not report significant effects on perceived autonomy , the study showed that older nursing home residents are able to clearly express wishes.37 gaining insight into the older patients needs , priorities , and experiences is also mentioned and of high importance in reviews on principles of learning in older people.6,24,25 a fundamental skill that nurses should develop , in order to ensure resident - centeredness according to hage and lorensen , is to be able to listen to the older people and be willing to respect their experiences , values , interests , and goals.24 this requires nurses to treat all residents as equal , an ascribed behavior of nurses.44 providing resident - centered care , in turn , can positively impact the nurses job satisfaction and work conditions.23 interventions that were integrated into daily life had less significant outcomes than interventions that were based on regular meetings , including group sessions . the more highly structured approach may lead to more benefits for residents , as recent patient education research on diabetes and anaphylaxis has shown.45,46 group sessions , in addition , can stimulate communication and support feelings of social belonging , which facilitate empowerment.47 however , we note that trials with the more highly structured interventions had shorter follow - ups , and no long - term effects were generated . therefore , the long - term effects of these interventions are still unclear . in three studies , printed educational materials were used in addition to verbal education . by the provision of different types of education ( printed information , verbal education ) , older persons learning skills can be matched.25 this requires analyses of the learning styles / strategies of older people to be conducted during the educational process . none of the included studies measured empowerment using a scale that had been specifically developed for this task , although such scales are available , six of which are generic and one of which has been designed especially for older people.17,18,48,49 furthermore , none of the studies investigated the effects of educational interventions on overall knowledge . this is interesting because attainment of knowledge has been a primary outcome of educational interventions reported for other population groups.50 knowledge that helps people meet their needs , expectations , or preferences is seen as fundamental to becoming empowered.51 as the mean age of the participants in the studies was high , and several studies included cognitively impaired residents , knowledge tests were perhaps not considered appropriate for the target group . interestingly , the high - quality studies more frequently achieved significant results than studies with lower quality.38,41 the improved scores in the adl performance in the study by bonanni et al must be interpreted with caution because there were several flaws in the study design.42 the majority of the included studies were cluster - randomized trials , with facilities as clusters . there was no indication that the participants in the different groups were treated differently apart from the allocated interventions . however , because no information on the usual care or the level of standardization of care in the participating facilities was given , differences in the residents perception of the care received may have influenced the outcomes . neither the occupational therapist visits , which were described in a high - quality study by sackley et al nor the individual training to enhance autonomy in the very high - quality study performed by andresen et al resulted in observable empowerment.36,37 the intervention schedule used in the study by sackley et al , with mean five sessions over 3 months , could have been too infrequent for the frail nursing home residents , many of whom were cognitively impaired and severely depressed.36 in the study by andresen et al , no significant differences in the main outcome , perceived autonomy , were detected between groups , and this may have been due to problems encountered in distinguishing participants from one another in terms of the intervention.37 some limitations may have influenced the interpretation of these reported results . on the basis of the available evidence , no consensus on the outcomes of empowerment could be reached . during this study , we used the empowering outcomes described by heikkinen et al , gibson , aujoulat et al , falkner , and anderson and funell.1419 this list of terms may be further extended in future studies . according to the core principles of empowerment , self - care activities or self - care management should only be considered to be relevant outcomes of empowerment if they result from a process of self - determination , whereby residents choose their own goals and strategies to reach these goals.17 although the residents could help choose their goals in most of the intervention studies , the degree of self - determination needed to reach these goals was not measured in these studies . therefore , it is still unclear whether enhanced self - management skills lead to enhanced empowerment . some limitations may have influenced the interpretation of these reported results . on the basis of the available evidence , no consensus on the outcomes of empowerment could be reached . during this study , we used the empowering outcomes described by heikkinen et al , gibson , aujoulat et al , falkner , and anderson and funell.1419 this list of terms may be further extended in future studies . according to the core principles of empowerment , self - care activities or self - care management should only be considered to be relevant outcomes of empowerment if they result from a process of self - determination , whereby residents choose their own goals and strategies to reach these goals.17 although the residents could help choose their goals in most of the intervention studies , the degree of self - determination needed to reach these goals was not measured in these studies . therefore , it is still unclear whether enhanced self - management skills lead to enhanced empowerment . empowerment is as fundamental to people of all ages as dignity and contributes to successful learning in older nursing home residents . individually tailored , interactive , continuous , and clearly structured educational strategies , including group education , individual counseling , and the use of motivational and encouragement techniques , may effectively help nursing home residents become more highly empowered . preliminary findings have shown that empowering strategies used by nurses can support residents in their personal growth and facilitate their self - determination . educational interventions can be more effectively adapted to meet residents needs by analyzing the learning styles / strategies of older people . in particular , empowering scales should be used , and correlations between outcomes and measures of empowerment , such as self - determination , should be more carefully assessed .

purpose of the studyhealth education is essential to improve health care behavior and self - management . however , educating frail , older nursing home residents about their health is challenging . focusing on empowerment may be the key to educating nursing home residents effectively . this paper examines educational interventions that can be used to empower nursing home residents.methodsa systematic literature search was performed of the databases pubmed , cinahl , central , psycinfo , and embase , screening for clinical trials that dealt with resident education and outcomes in terms of their ability to empower residents . an additional , manual search of the reference lists and searches with sigle and google scholar were conducted to identify gray literature . two authors independently appraised the quality of the studies found and assigned levels to the evidence reported . the results of the studies were grouped according to their main empowering outcomes and described narratively.resultsout of 427 identified articles , ten intervention studies that addressed the research question were identified . the main educational interventions used were group education sessions , motivational and encouragement strategies , goal setting with residents , and the development of plans to meet defined goals . significant effects on self - efficacy and self - care behavior were reported as a result of the interventions , which included group education and individual counseling based on resident needs and preferences . in addition , self - care behavior was observed to significantly increase in response to function - focused care and reasoning exercises . perceptions and expectations were not improved by using educational interventions with older nursing home residents.conclusionindividually tailored , interactive , continuously applied , and structured educational strategies , including motivational and encouraging techniques , are promising interventions that can help nursing home residents become more empowered . empowering strategies used by nurses can support residents in their growth and facilitate their self - determination . further research on the empowerment of residents using empowerment scales is needed .

one of the outstanding problems facing high energy physics is the origin of electroweak symmetry breaking . although the usual higgs mechanism , which employs a single weak scalar isodoublet , is phenomenologically successful@xcite it is not theoretically satisfying . is it possible to generate the masses for the gauge bosons and fermions of the standard model(sm ) without encountering fine - tuning and naturalness issues as well as the associated hierarchy problem ? on the experimental side , we expect that the lhc should begin to probe for answers to these important questions over the next few years with potentially surprising results . while we wait , it is important for us to examine as many scenarios as possible which address these issues in order to prepare ourselves for these critically important terascale experimental results . grinstein , oconnell and wise(gow)@xcite have recently extended to the sm context an old idea by lee and wick(lw)@xcite based on higher - derivative theories . this model apparently solves the hierarchy problem and eliminates the quadratic divergence of the higgs boson mass that one ordinarily encounters in the sm . the most essential feature of the gow scenario is the introduction of negative - normed states into the usual sm hilbert space . in particular , one introduces a new massive degree of freedom ( or one vector - like pair in the fermion case ) for each of the conventional sm particles with the same spin . the resulting contributions of these exotic new particles to the higgs mass quadratic divergence then cancels those of the sm , partner by partner , leaving only safe logarithmic terms . in the gauge sector , , the following new fields are introduced : an @xmath1 octet of ` gluons ' , @xmath2 , with mass @xmath3 , an @xmath4 isotriplet of weak bosons , @xmath5 , of mass @xmath6 and a heavy neutral @xmath7 hypercharge field , @xmath8 , with mass @xmath9 . the interactions of these new fields with each other and with the familiar ones of the sm are given in detail in ref.@xcite . gow argue that due to naturalness requirements and the present direct@xcite and indirect@xcite experimental constraints on the existence of such particles , one should anticipate that their masses must lie not too far above @xmath10 tev . the implications of such a scenario have been examined in a number of recent works@xcite . within this context , the purpose of the present paper is to address a purely phenomenological issue . as long as such states are not too massive , since their interactions are very similar to those of their conventional sm counterparts , it is already clear that they will be produced _ and _ observed at the lhc based on the results of other existing analyses@xcite . due to their rather strange and unusual properties , one might imagine that it would be rather trivial for lhc experimental data to be used to uniquely identify such states as arising from the gow framework . however , it was shown in an earlier work@xcite that this is not the case in the gauge boson sector due to the possible ambiguities in the signs of the couplings of new gauge bosons to the sm fermions . the issue we want to address in this paper is whether or not this situation can be overcome at future @xmath0 colliders , , can we tell that we have unambiguously observed these negative - metric lw fields and not something else ? we will demonstrate that measurements of the bhabha scattering process will allow us to answer this question conclusively in the affirmative . since we will be considering @xmath0 collisions , our attention will be focused on the new neutral electroweak gauge bosons in the gow model . the essential phenomenological features of these new states is straightforward to summarize : ( @xmath11 ) the propagators and decay widths of the relevant lw particles , @xmath12 , have signs which are opposite to those of the familiar sm fields ; ( @xmath13 ) the couplings of these lw gauge fields to sm fermions are exactly those of the corresponding sm gauge fields ; ( @xmath14 ) in the limit that @xmath15 , as will be the case discussed below , the mixing between the sm and gow gauge bosons can be neglected . when ( @xmath11 ) and ( @xmath13 ) are taken together they imply a strong destructive interference between the sm and gow amplitudes that can be symbolically written as @xmath16 apart from other overall factors . in particular the width @xmath17 has exactly the same magnitude as would a heavy copy of the relevant sm gauge field . note that here we have assumed that the decays of these heavy gauge bosons into pairs of the lw partners of the sm fermions is not kinematically allowed . in this case , the width to mass ratio of these new gauge bosons is quite small @xmath18 . if such decays are allowed , only the widths of the new gauge states are modified and not their couplings to the sm fields which is what we wish to explore below . if decays to some of these fermions are allowed , we would still expect that @xmath19 or so . this overall situation is somewhat reminiscent of what happens in the sequential sm(ssm)@xcite or the case of flat , tev - scale extra dimensions where the fermions are confined to the origin of the fifth dimension ( apart from an additional numerical factor@xcite of @xmath20 which might be modified by the existence of brane - localized kinetic terms@xcite ) . a small , but important , difference here is that for the general case when @xmath21 , the two fields @xmath22 and @xmath8 will be the true mass eigenstates and we shall generally use this basis in what follows . to see this , we note that the angle describing the mixing between these two states is given by@xcite @xmath23^{-1}\,,\ ] ] where @xmath24 are the usual @xmath4 and @xmath7 sm couplings with @xmath25 the sm higgs vev . when @xmath9 and @xmath6 are substantially different , this mixing is quite small , , of order @xmath26 or less . however , when @xmath27 , a special case that we will consider below , the angle @xmath28 is large and is seen to be identical with the usual weak mixing angle , @xmath29 . clearly , mixing must be included in this case in any phenomenological analysis . before beginning our analysis let us remind the reader about the source of the ambiguities encountered at the lhc . due to our particular interests below we focus on the the neutral electroweak gauge boson sector though the same problems arise for all gauge sectors . the primary way to observe a new gauge field with sm - like couplings at the lhc is in the drell - yan channel@xcite . as an example , let us consider the production and decay of heavy @xmath30-like states at the lhc , comparing three possibilities : @xmath31 the new fields are exact but heavier duplicates of the ones in the sm and , as discussed above , might occur in models with extra dimensions , @xmath32 they are lw - type fields , or @xmath33 they are sm - like fields _ but _ the overall relative sign between , , the initial state quarks and the final state leptonic couplings is opposite to that of the sm . as discussed in our earlier work@xcite , it was noted that such a situation could arise in models@xcite where fermions are localized on two different branes bounding an extra flat dimension . note that for the following phenomemological discussion , these alternatives to the lw model are treated only as ` strawmen ' against which the lw predictions can be tested . in the resonance region(s ) these three scenarios are essentially identical producing resonances with exactly the same ( apparent ) widths and branching fractions and with the same angular distributions for the outgoing leptons . below the resonances , @xmath31 differs from @xmath32 and @xmath33 since there is strong destructive interference in this case whereas the other two scenarios lead to constructive interference with the sm photon and @xmath34 exchanges . thus case @xmath31 can be distinguished from cases @xmath32 and @xmath33 by measuring the cross section in this interference region . however , cases @xmath32 and @xmath33 are found to be indistinguishable ; algebraically , the corresponding amplitudes in these two cases differ only in the sign of the imaginary parts in the @xmath22 and @xmath8 contributions which are sufficiently small in comparison to other terms in the amplitude as to be impossible to observe@xcite even at very high lhc integrated luminosities . can we get around this problem at an @xmath0 collider and separate all three of these possibilities , uniquely establishing the identity of the lw states ? this is the issue to which we now turn . to begin our analysis and to be as general as possible let us first imagine that we have available to us an @xmath0 collider with an adjustable center of mass energy in the tev range which will follow in the wake of the lhc . consider the set of processes @xmath35 where @xmath36 is any sm fermion . then it is well known@xcite that for any ( massless ) fermion , @xmath37 , the born - level production differential cross section for unpolarized @xmath38 due to the @xmath39-channel exchange of any number of ( ordinary ) neutral gauge bosons can be written as @xmath40\,,\ ] ] where @xmath41 is a color factor , @xmath42 , the angle being between @xmath43 and @xmath36 , with @xmath44 with @xmath45 being the vector and axial vector couplings of @xmath46 and @xmath36 to the @xmath11th gauge boson and @xmath47[i\to j]}}\,,\ ] ] is the corresponding propagator factor . here @xmath48 are the mass ( width ) of the @xmath11th gauge boson . for polarized beams , a similar set of expressions can be written down to construct the left - right polarization asymmetry , @xmath49 ; to do this we make the replacements @xmath50 and then form the ratio @xmath51\,,\ ] ] where @xmath52 is the effective beam polarization . in the calculations below we will set @xmath53 for simplicity . let us now consider the three models @xmath54 in this environment ; the expressions above apply directly to cases @xmath31 and @xmath33 as the gauge fields in these two cases are ` ordinary ' . as at the lhc , we see that flipping the relative sign of the initial / final fermion couplings of the @xmath55 and @xmath56 will change the the cross section in the interference region both below and above the resonances . this is shown explicitly in figs . [ fig1 ] and [ fig1a ] for two representative spectrum cases assuming for simplicity that @xmath57 . to cover the case of lw gauge bosons , we must recall that now @xmath58 and rescale the equation for the @xmath59 : @xmath60 , where @xmath61 when both @xmath62 both correspond to sm or lw gauge fields but @xmath63 in all other cases where sm and lw exchanges interfere . it is clear from this exercise that the cross sections for scenarios @xmath32 and @xmath33 will differ by construction only in the sign of the terms proportional to the products @xmath64 . note that the resulting cross section for the lw case , @xmath32 , is also shown in fig . [ fig1 ] lying directly on top of that for scenario @xmath33 , repeating our lhc experience . we also find that a similar result is also observed to hold in the case of the angular - averaged values of @xmath65 , , cases @xmath32 and @xmath33 lead to virtually identical numerical results for @xmath65 . as a function of @xmath66 for scenario @xmath31 in green and for scenarios @xmath32 and @xmath33 in blue . the explicit gow results are shown as dashes inside of the blue curve . the sm prediction for comparison purposes is in red . in the top panel @xmath67 tev whereas in the bottom panel @xmath68 tev and @xmath69 tev.,width=283 ] as a function of @xmath66 for scenario @xmath31 in green and for scenarios @xmath32 and @xmath33 in blue . the explicit gow results are shown as dashes inside of the blue curve . the sm prediction for comparison purposes is in red . in the top panel @xmath67 tev whereas in the bottom panel @xmath68 tev and @xmath69 tev.,width=283 ] .,width=283 ] .,width=283 ] it is clear that we can always play this game with the signs of the couplings on the new gauge bosons when the initial state and final state fermions are _ different_. at the lhc , we attempted@xcite to circumvent this problem by looking at reactions in the qcd sector such as @xmath70 , which in this scenario is now also mediated by heavy lw gluons , and which produces the dijet final state . here , the initial and final state partons are _ the problem in such a case is that there are many processes which mediate dijet production , even at leading order . we showed in that work that is was essentially impossible to isolate the effects of the negative - normed lw exchanges . at @xmath0 colliders the situation is far simpler and we are directly led to consider bhabha scattering , @xmath71 , which has _ identical _ initial and final state fermions so that we can no longer play the coupling sign trick . this process will depend upon coupling combinations like @xmath72 and @xmath73 above but with @xmath74 . this means that a change in the sign of the electron s couplings to both @xmath55 and @xmath56 will leave the differential cross section and polarization asymmetries _ explicitly we obtain @xmath75\,,\ ] ] where @xmath76 and , generalizing the above relation , we now write @xmath77[(r - m_j^2)^2+\gamma_j^2m_j^2]}}\,.\ ] ] from these expressions it is clear that for bhabha scattering , cases @xmath31 and @xmath33 will yield identical cross section and asymmetry results while now case @xmath32 , the gow scenario , will be distinct . this is shown explicitly in figs . [ fig2 ] and [ fig2b ] for the same parameter choices as employed above in figs . [ fig1 ] and [ fig1a ] . here we see that the previously obtained ambiguities have been removed and that the lw gauge fields can be uniquely identified as desired . as a function of @xmath66 for scenarios @xmath31 and @xmath33 in green and for scenario @xmath32 in blue . the sm prediction for comparison purposes is in red . in the top panel @xmath67 tev whereas in the bottom panel @xmath68 tev and @xmath69 tev . a cut on @xmath78 has been applied , @xmath79 , to remove the large contribution from the forward photon pole.,width=283 ] as a function of @xmath66 for scenarios @xmath31 and @xmath33 in green and for scenario @xmath32 in blue . the sm prediction for comparison purposes is in red . in the top panel @xmath67 tev whereas in the bottom panel @xmath68 tev and @xmath69 tev . a cut on @xmath78 has been applied , @xmath79 , to remove the large contribution from the forward photon pole.,width=283 ] .,width=283 ] .,width=283 ] a weakness in the analysis above is that we may not have immediate access to a @xmath0 collider with energies above 1 tev so that it may be impossible to directly access the gauge boson excitation curves in bhabha scattering , as we have done above , for some time . this depends upon , , the potential relative schedules of the ilc and clic as well as many other known and unknown unknowns . however , it is clear that at the first stage of the ilc , we will likely be limited to values of @xmath80 gev so that the properties of these new gauge bosons can only be indirectly studied in bhabha scattering . obviously this is a more difficult situation than in the case where the resonance region(s ) of the new gauge bosons can be directly accessed . what can we learn at these lower energies below the resonances ? here the capability of the ilc to make precision measurements becomes of great importance . in the analysis below we will assume that the lhc has already determined the masses of the new gauge states and has made a relatively detailed study of their couplings to the sm fermions@xcite , determining that they are indeed sm - like . [ fig3 ] shows the results of this 500 gev ilc analysis below the resonance region where it has been assumed that @xmath81 tev . away from the forward and backward directions it is quite clear that identical constructive interference occurs for scenarios @xmath31 and @xmath33 while destructive interference occurs for the gow case @xmath32 . at this level of statistics , these two possibilities are now very easily distinguished in both the differential cross section as well as in @xmath82 . of course , as the masses of the two fields @xmath22 and @xmath8 are increased this distinguishing power goes down quite rapidly as can be seen in fig . [ fig4 ] where it has now been assumed that @xmath83 tev . here we see that the two predictions are somewhat closer but are still separable given the large statistics . certainly once we reach @xmath30 masses of order @xmath84 tev and above , at these assumed integrated luminosities , this separation is no longer possible and a higher energy @xmath0 collider will be required . in fact , we find that the overall separation reach scales roughly as @xmath85 for analyses performed below the lw resonance region . as a function of @xmath78 at @xmath86 gev for the various scenarios discussed in the text . the statistical errors in the measurements are shown . the black histogram is the sm result whereas the red data points are for scenarios @xmath31 or @xmath33 ; the blue ones are for the gow model . here , @xmath81 tev has been assumed as well as an integrated luminosity of 500 @xmath87 . isr has been included with a cut on the @xmath0 invariant mass @xmath88 gev ; beamstrahlung effects have been ignored for simplicity.,width=283 ] as a function of @xmath78 at @xmath86 gev for the various scenarios discussed in the text . the statistical errors in the measurements are shown . the black histogram is the sm result whereas the red data points are for scenarios @xmath31 or @xmath33 ; the blue ones are for the gow model . here , @xmath81 tev has been assumed as well as an integrated luminosity of 500 @xmath87 . isr has been included with a cut on the @xmath0 invariant mass @xmath88 gev ; beamstrahlung effects have been ignored for simplicity.,width=283 ] tev has been assumed.,width=283 ] tev has been assumed.,width=283 ] in this paper we have demonstrated that the neutral , negative - normed gauge boson states predicted by the gow model can be uniquely identified as such at future @xmath0 colliders through the bhabha scattering channel over a reasonably wide kinematic range . this overcomes the identification problem encountered for lw - type gauge bosons encountered by using data from the lhc alone . for @xmath0 colliders with direct access to the ( multi-)tev scale associated with the resonance region(s ) of these states , this identification is rather straightforward by using both cross section and polarization symmetry information that can be easily obtained . however , we also demonstrated that even at energies a factor of a few below such resonance masses , precision measurements of these same observables at @xmath0 colliders can be used to uniquely identify the lw nature of new states provided these gauge boson masses are already known from lhc data and provided sufficient integrated luminosity is available . we this conclude that with data from @xmath0 colliders the ambiguity issues associated with the production of lw gauge bosons can be easily resolved . # 1 # 2 # 3 mod . # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 nucl . phys . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 phys . lett . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 phys . rep . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 phys . rev . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 phys . lett . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 rev . # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 nuc . # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 z. phys . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 e. phys . j. * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 int . phys . * # 1 * , # 2 ( # 3 ) # 1 # 2 # 3 j. high en . phys . * # 1 * , # 2 ( # 3 ) the direct search lower limit on the masses of new @xmath89 gauge bosons with sm couplings is approaching 1 tev from run ii data at the tevatron . the lower bound on a sm - coupled @xmath90 is 923(965 ) gev from cdf(d0 ) . see , for example , p. savard , `` searches for extra dimensions and new gauge bosons at the tevatron , '' talk given at the _ xxxiii international conference on high energy physics _ , 26 july-2 august 2006 , moscow , russia ; t. adams , `` searches for new phenomena with lepton final states at the tevatron , '' talk given at rencontres de moriond electroweak interactions and unified theories 2007 , la thuile , italy 10 - 17 march 2007 ; a. abulencia _ et al . _ [ cdf collaboration ] , arxiv : hep - ex/0611022 . in the case of the lrm , the lower bound from indirect measurements may be somewhat larger : p. langacker and s. uma sankar , phys . d * 40 * , 1569 ( 1989 ) . b. grinstein , d. oconnell and m. b. wise , arxiv:0710.5528 [ hep - ph ] ; f. krauss , t. e. j. underwood and r. zwicky , arxiv:0709.4054 [ hep - ph ] ; t. r. dulaney and m. b. wise , arxiv:0708.0567 [ hep - ph ] ; b. grinstein , arxiv:0706.4185 [ hep - ph ] ; f. wu and m. zhong , arxiv:0705.3287 [ hep - ph ] ; j. r. espinosa , b. grinstein , d. oconnell and m. b. wise , arxiv:0705.1188 [ hep - ph ] . cms physics tdr , volume ii : cern - lhcc-2006 - 021 , atlas tdr , http://atlas.web.cern.ch/atlas/groups/physics/tdr/tdr.html . for a recent review and original references , see t. g. rizzo , arxiv : hep - ph/0610104 . for some classic reviews of new gauge boson physics , see a. leike , phys . * 317 * , 143 ( 1999 ) [ arxiv : hep - ph/9805494 ] ; j. l. hewett and t. g. rizzo , phys . rept . * 183 * , 193 ( 1989 ) ; m. cvetic and s. godfrey , arxiv : hep - ph/9504216 ; t. g. rizzo , `` extended gauge sectors at future colliders : report of the new gauge boson subgroup , '' econf * c960625 * , new136 ( 1996 ) [ arxiv : hep - ph/9612440 ] . i. antoniadis , phys . b * 246 * , 377 ( 1990 ) ; t. g. rizzo and j. d. wells , phys . d * 61 * , 016007 ( 2000 ) [ arxiv : hep - ph/9906234 ] ; k. m. cheung and g. landsberg , phys . d * 65 * , 076003 ( 2002 ) [ arxiv : hep - ph/0110346 ] ; a. strumia , phys . b * 466 * , 107 ( 1999 ) [ arxiv : hep - ph/9906266 ] ; a. delgado , a. pomarol and m. quiros , jhep * 0001 * , 030 ( 2000 ) [ arxiv : hep - ph/9911252 ] ; f. cornet , m. relano and j. rico , phys . d * 61 * , 037701 ( 2000 ) [ arxiv : hep - ph/9908299 ] ; c. d. carone , phys . rev . d * 61 * , 015008 ( 2000 ) [ arxiv : hep - ph/9907362 ] ; p. nath and m. yamaguchi , phys . d * 60 * , 116004 ( 1999 ) [ arxiv : hep - ph/9902323 ] ; a. muck , a. pilaftsis and r. ruckl , phys . d * 65 * , 085037 ( 2002 ) [ arxiv : hep - ph/0110391 ] ; g. polesello and m. prata , eur . phys . j. c * 32s2 * , 55 ( 2003 ) ; p. nath , y. yamada and m. yamaguchi , phys . lett . b * 466 * , 100 ( 1999 ) [ arxiv : hep - ph/9905415 ] ; h. davoudiasl and t. g. rizzo , arxiv : hep - ph/0702078 . m. carena , t. m. p. tait and c. e. m. wagner , acta phys . b * 33 * , 2355 ( 2002 ) [ arxiv : hep - ph/0207056 ] ; m. carena , e. ponton , t. m. p. tait and c. e. m. wagner , phys . d * 67 * , 096006 ( 2003 ) [ arxiv : hep - ph/0212307 ] ; h. davoudiasl , j. l. hewett and t. g. rizzo , phys . d * 68 * , 045002 ( 2003 ) [ arxiv : hep - ph/0212279 ] and phys . b * 493 * , 135 ( 2000 ) [ arxiv : hep - ph/0006097 ] ; f. del aguila , m. perez - victoria and j. santiago , jhep * 0302 * , 051 ( 2003 ) [ arxiv : hep - th/0302023 ] .

grinstein , oconnell and wise have recently presented an extension of the standard model ( sm ) , based on the ideas of lee and wick ( lw ) , which demonstrates an interesting way to remove the quadratically divergent contributions to the higgs mass induced by radiative corrections . this model predicts the existence of negative - norm copies of the usual sm fields at the tev scale with ghost - like propagators and negative decay widths , but with otherwise sm - like couplings . in earlier work , it was demonstrated that the lw states in the gauge boson sector of these models , though easy to observe , can not be uniquely identified as such at the lhc . in this paper , we address the issue of whether or not this problem can be resolved at an @xmath0 collider with a suitable center of mass energy range . we find that measurements of the cross section and the left - right polarization asymmetry associated with bhabha scattering can lead to a unique identification of the neutral electroweak gauge bosons of the lee - wick type . thomas g. rizzo _ stanford linear accelerator center , 2575 sand hill rd . , menlo park , ca , 94025 _

SECTION 1. SHORT TITLE. This Act may be cited as the ``Employee Ownership Act of 1999''. SEC. 2. OWNERSHIP POLICY FOR THE UNITED STATES. (a) Findings.--The Congress finds that-- (1) there is considerable evidence that employee-owned and employee-controlled corporations are more productive and provide more wealth to their employees than corporations not so owned, and (2) the workplace experience of employee-owned and employee-controlled corporations is proven to foster greater appreciation of the economic system of the United States that relies on ownership of private property and capitalism. (b) Policy.--It is the policy of the United States that by the year 2010, 30 percent of all United States corporations are owned and controlled by employees of the corporations. SEC. 3. TAX INCENTIVES RELATING TO EMPLOYEE-OWNED AND EMPLOYEE- CONTROLLED CORPORATIONS. (a) Trust of Employee-Owned and Employee-Controlled Corporation Exempt From Taxation.-- (1) In general.--Section 501(c) of the Internal Revenue Code of 1986 (relating to list of exempt organizations) is amended by adding at the end the following new paragraph: ``(28)(A) employee-owned and employee-controlled corporation trust. ``(B) For purposes of subparagraph (A), the term `employee- owned and employee-controlled corporation trust' means a trust which has as its primary assets the employer securities (within the meaning of section 409(l)) of an employee-owned and employee-controlled corporation. (2) Employee-owned and employee-controlled corporation defined.--Subsection (a) of section 7701 of such Code (relating to definitions) is amended by adding at the end the following new paragraph: ``(47) Employee-owned and employee-controlled corporation.--The term `employee-owned and employee-controlled corporation' means a corporation in which-- ``(A) more than 50 percent of the voting stock of such corporation is held by a trust for the benefit of the employees of that corporation, ``(B) in all matters requiring the vote of stock, including the election of the board of directors of the corporation, the trustee of such trust is obligated to vote the stock held in trust and allocated to participants in the trust in the manner in which the participants direct, on the basis of 1-employee 1-vote, and to vote any stock not so allocated as if it were so allocated, ``(C) at least 25 employees of such corporation are participants in and beneficiaries of such trust, ``(D) a minimum of 90 percent of the employees who work at least 1,000 hours annually for such corporation are participants in such trust, and ``(E) the trustee administers such trust for the benefit of the employees of such corporation and complies with all requirements of this title relating to employee stock ownership plans (as defined in section 4975(e)(7)) pertaining to independent appraisal of shares not readily tradable and distribution of those shares.''. (b) No Tax on Corporate Income of Employee-Owned and Employee- Controlled Corporation.--Subsection (a) of section 11 of such Code (relating to corporations in general) is amended by inserting before the period at the end the following: ``(other than any employee-owned and employee-controlled corporation)''. (c) Exclusion of Income From Sale of Employee-Owned and Employee- Controlled Corporation Stock by Employee Owner.-- (1) In general.--Part III of subchapter B of chapter 1 of such Code (relating to items specifically excluded from gross income) is amended by redesignating section 139 as section 140 and by inserting after section 138 the following new section: ``SEC. 139. INCOME FROM EMPLOYEE OWNER SALE OF EMPLOYER SECURITIES DISTRIBUTED FROM EMPLOYEE-OWNED AND EMPLOYEE-CONTROLLED CORPORATION TRUST. ``(a) In General.--In the case of an individual, gross income shall not include any proceeds from the qualified sale of employer securities. ``(b) Qualified Sale of Employer Securities.--The term `qualified sale of employer securities' means the sale of employer securities (as defined in section 409(l)) which were distributed to a participant in the employee-owned and employee-controlled corporation trust to-- ``(1) an employee of the employee-owned and employee- controlled corporation which issued such securities, ``(2) such corporation, or ``(3) such trust.''. (2) Clerical amendment.--The table of sections for part III of subchapter B of chapter 1 of such Code is amended by striking the item relating to section 139 and inserting after the item relating to section 138 the following new items: ``Sec. 139. Income from employee owner sale of employer securities distributed from employee-owned and employee-controlled corporation trust. ``Sec. 140. Cross references to other Acts.''. (d) Receipt of Stock in an Employee Owned and Controlled Corporation During 3-Year Transition Period.--Section 83 of such Code (relating to property transferred in connection with performance of services) is amended by adding at the end the following new subsection: ``(i) Receipt of Stock in an Employee Owned and Controlled Corporation During 3-Year Transition Period.-- ``(1) In general.--In the case of an employee, this section shall not apply to the transfer in lieu of compensation of employer securities in an employer owned and controlled corporation during the 3-year period beginning on the effective date of the election of a corporation to become an employee owned and controlled corporation. ``(2) Exception.--If, on the day after the end of the 3- year period referred to in paragraph (1), such corporation is not an employee owned and controlled corporation, paragraph (1) shall not apply and the following sum shall be included in the gross income of such employee: ``(A) an amount equal to the fair market value of all of such securities at the time of transfer (determined without regard to any restriction other than a restriction which by its terms will never lapse) to the employee in lieu of compensation for such period, plus ``(B) an amount equal to 10 percent of the amount determined under subparagraph (A).''. (e) No Tax on Gain on Sales or Transfers to Employee-Owned and Employee-Controlled Corporation Trust.-- (1) In general.--Part III of subchapter O of chapter 1 of such Code (relating to common nontaxable exchanges) is amended by adding at the end the following new section: ``SEC. 1046. SALE OF SECURITIES TO EMPLOYEE-OWNED AND EMPLOYEE- CONTROLLED CORPORATION TRUST. ``(a) Nonrecognition of Gain.--If the taxpayer elects the application of this section, in the case of the sale or transfer of employer securities (as defined in section 409(l)) to an employee-owned and employee-controlled corporation trust, gain on such sale or transfer shall not be recognized if the requirements of subsection (b) are met. ``(b) Requirements.-- ``(1) In general.--The requirements of this subsection are that-- ``(A) the employee-owned and employee-controlled corporation trust acquiring such securities from the taxpayer agrees-- ``(i) to hold such securities for the 3- year period beginning on the date of such transfer or sale, and ``(ii) to notify the taxpayer upon the transfer of such securities before the end of such period, and ``(B) the taxpayer agrees to the provisions of subsection (b). ``(2) Exceptions.--Paragraph (1) shall not apply-- ``(A) in a case where such securities are securities of an employee-owned and employee-controlled corporation which are distributed within such 3-year period to an employee of such corporation, and ``(B) in the case of the sale or transfer of stock of an employee-owned and employee-controlled corporation in connection with the sale or reorganization of such corporation, if such sale or reorganization is approved by the employees of such corporation in a vote held on a 1-employee 1-vote basis. ``(c) Recapture of Tax.--If, during any year within the 3-year period referred to in subsection (b)(1), securities subject to subsection (a) are sold or transferred in a manner that does not meet the requirements of subsection (b), then gain on the sale or transfer described in subsection (a) shall be recognized for the year in which such requirements are not met.''. (2) Clerical amendment.--The table of sections for part III of subchapter O of chapter 1 of such Code is amended by adding at the end the following new item: ``Sec. 1046. Sale of securities to employee-owned and employee- controlled corporation trust.''. (f) Credit For Transfer of Stock From Estate to Employee-Owned and Employee-Controlled Corporation.-- (1) In general.--Part II of subchapter A of chapter 11 of such Code (relating to credits against tax) is amended by redesignating section 2016 as section 2017 and by inserting after section 2015 the following new section: ``SEC. 2016. CREDIT FOR TRANSFER OF EMPLOYEE SECURITIES FROM ESTATE TO EMPLOYEE-OWNED AND EMPLOYEE-CONTROLLED CORPORATION TRUST. ``(a) General Rule.--The tax imposed by section 2001 shall be credited with the amount of employer securities considered to have been acquired from or to have passed from the decedent to an employee-owned and employee-controlled corporation trust. ``(b) Limitation.--Such credit may not exceed the tax imposed by section 2001, reduced under this part (other than by this section). ``(c) Value of Stock Not Readily Tradable.--No credit shall be allowed under subsection (a) in the case of employer securities which are not readily tradable on an established securities market unless the value of such employer securities is established by an independent appraiser. For purposes of the preceding sentence, the term `independent appraiser' means any appraiser meeting requirements similar to the requirements of the regulations prescribed under section 170(a)(1). ``(d) Definitions.--For purposes of subsection (a)-- ``(1) Acquired from or passed from a decedent.--Employer securities shall be considered to have been acquired from or to have passed from a decedent if the basis of such property in the hands of the employee-owned and employee-controlled corporation trust is determined under section 1014 by reference to paragraph (1), (2), (4), or (9) of subsection (b) of such section. ``(2) Employer securities.--The term `employer securities' has the meaning given such term by section 409(l)), except that such term shall not include any security which is not voting common stock.''. (2) Clerical amendment.--The table of sections for part II of subchapter A of chapter 11 of such Code (relating to credits against tax) is amended by striking the item relating to section 2016 and adding at the end the following new items: ``Sec. 2016. Credit for transfer of employee securities from estate to employee-owned and employee- controlled corporation trust. ``Sec. 2017. Recovery of taxes claimed as credit.''. (g) Effective Date.-- (1) In general.--Except as provided in paragraph (2), the amendments made by this section shall apply to taxable years beginning after the date of the enactment of this Act. (2) Credit for transfer of stock from estate to employee- owned and employee-controlled corporation.--The amendments made subsection (f) shall apply to estates of decedents dying after the date of the enactment of this Act. SEC. 4. STUDY OF GOVERNMENT POLICIES AFFECTING EMPLOYEE-OWNED AND EMPLOYEE-CONTROLLED CORPORATIONS. The Comptroller General of the United States shall-- (1) conduct a study of all Federal Government regulations and policies that might impact the creation and operation of an employee-owned and employee-controlled corporation as defined in section 7701(a)(47) of the Internal Revenue Code of 1986, (2) identify those regulations and policies that are barriers to employee ownership and control of such a corporation, and (3) not later than one year after the date of the enactment of this Act, submit a report on the findings of such study, together with such recommendations as the Comptroller General determines appropriate, to the Congress. SEC. 5. PRESIDENTIAL COMMISSION ON EMPLOYEE OWNERSHIP. (a) Establishment.--Not later than one year after the date of the enactment of this Act, the President shall establish a commission to be known as the ``Presidential Commission on Employee Ownership'' (hereafter in this section referred to as the ``Commission''). (b) Duties and Report.--The Commission shall-- (1) conduct a study concerning all issues that affect ownership of businesses in the United States, with a primary focus on the issues that affect employee ownership of such businesses, and (2) not later than two years after the date of its establishment, submit a final report to the President and the Congress which includes the findings and recommendations of the Commission. (c) Membership.--The Commission shall be composed of 15 members appointed by the President as follows: (1) Three individuals, each of whom is an employee of a corporation that has at least 50 percent of its voting stock in a trust for the benefit of employees and who is not an officer or senior manager of that corporation. (2) Three individuals, each of whom is an employee of a corporation that has at least 50 percent of its voting stock in a trust for the benefit of employees and who is an officer or senior manager of that corporation. (3) Three individuals, each of whom is a professor employed by an institution of higher learning. (4) Three individuals, each of whom is employed by a not- for-profit entity that has as its primary mission issues arising from employee ownership of businesses. (5) The Secretary of Labor, or his designee, the Secretary of the Treasury, or his designee, and the Director of the Office of Management and Budget, or his designee. (d) Staff.--The Commission shall have such number of staff as the President shall determine, except that such staff shall include not less than five full-time employees. (e) Gifts and Bequests.--The Commission may accept, use, and dispose of gifts or bequests or services or personal property for the purpose of aiding or facilitating the work of the Commission. Gifts or bequests of money and proceeds from sales of other property received as gifts or bequests shall be deposited in the Treasury and shall be available for disbursement upon order of the Commission.

(Sec. 3) Amends the Internal Revenue Code to provide for tax-exempt employee-owned and employee-controlled corporation (EOECC) trusts whose primary assets consist of the employer securities of an EOECC in which: (1) more than 50 percent of the voting stock is held by a trust for the benefit of the corporation's employees; (2) in all matters requiring the vote of stock, including the election of the corporate board of directors, the trustee of such trust is obligated to vote the stock held in trust and allocated to participants in the trust in the manner in which the participants direct, on the basis of one-employee one-vote (and vote any stock not so allocated as if it were so allocated); (3) at least 25 employees of such corporation are participants in and beneficiaries of such trust; (4) a minimum of 90 percent of the employees who work at least 1,000 hours annually for such corporation are participants in such trust; and (5) the trustee administers the trust for the benefit of the corporation's employees, complying with all Code requirements for employee stock ownership plans which pertain to independent appraisal of shares not readily tradable, and distribution of those shares. Declares that: (1) there shall be no tax on the corporate income of an EOECC; and (2) the gross income of an employee owner shall not include any proceeds from the qualified sale of EOECC securities. Exempts from inclusion in gross income of property transferred in connection with performance of services any transfer (in lieu of compensation) of EOECC securities during the three years following a corporation's election to become an EOECC. Mandates nonrecognition of gain in the case of the sale or transfer of EOECC securities to an EOECC trust. Establishes a credit against the estate tax for the amount of EOECC securities considered to have been acquired from or to have passed from a decedent to an EOECC trust. (Sec. 4) Directs the Comptroller General to study and report to Congress on Federal regulations and policies affecting EOECCs. (Sec. 5) Directs the President to establish a Presidential Commission on Employee Ownership to study and report on all issues that affect ownership of businesses in the United States, with a primary focus on the issues that affect employee ownership of such businesses.

orofaciodigital syndrome ( ofds ) ( omim 311200 ) is a general term for describing several distinctive developmental genetic diseases that are characterized by malformation of the mouth , face and digits . at least 13 different types of the syndrome have been recognized among which type 1 ( ofd1 ) is the most common form with an incidence of 1:50000 to 1:250000 live births ( 1 , 2 ) . the cardinal clinical features include craniofacial abnormalities ( facial asymmetry , hypertelorism , frontal bossing , microretrognathia , broadened nasal bridge , cleft palate , multi - lobulated tongue with nodules , and abnormal dentition ) , and digital abnormalities including brachydactyly , syndactyly , clinodactyly and pre- or post - axial polydactyly . in 60% of cases with ofd1 , brain structural abnormalities , developmental delay and intellectual disabilities have been identified ( 3 ) . majority of cases with onset older than 18 years , suffer from renal cystic disease ( 46 ) . the observation of multiple milia and hypotrichosis is remarkable skin abnormality for ofd1 which are not observed in other types of ofds ( 7 ) . mutations in the ofd1 gene , which is mapped on chromosome xp22 , are responsible for ofd syndrome type 1 . therefore , ofd syndrome type 1 is inherited in x - linked dominant pattern and has prenatal lethality in the male fetus ( 5 , 8 , 9 ) . a protein with 1011 amino acid expressed on the basal body of primary cilia and the centrosome is encoded by ofd1 gene . the protein also has a key role in the biogenesis of cilium and development by modulating wnt signaling pathways ( 1013 ) . to date , over 130 different mutations have been identified in ofd1 with many truncating mutations . about 75% of cases with ofd1 are sporadic , and there are some reports about correlation of genotype with phenotype ( 12 , 14 ) . mutations in ofd1 gene have also been identified in association with four recessive x - linked phenotypes : joubert syndrome , intellectual disability , type 2 simpson - golabi - behmel syndrome and retinitis pigmentosa ( 1519 ) . in this case study , we analyzed the sequences of the eight exons of the ofd1 gene in eight individuals from an iranian family with x - linked dominant ofd1 , and we identified a novel mutation . this family had a heterogeneous phenotypic findings ranging from being so mild in the mother that she was undiagnosed to severe neurodevelopmental delay , distinctive dysmorphic facial features , and multiple oral anomalies in her daughters . the study was approved by ethics committee of yazd university of medical sciences and informed written consent was obtained from the all subjects participating in the study . a female sibship was referred to the medical genetics department of yazd university of medical sciences due to craniofacial and oral dysmorphism in addition to neurodevelopmental delay . the patients were thoroughly examined and all their clinical records were reviewed by a physician . a three - generational pedigree for the family was constructed based on their family history obtained by a genetic counselor ( fig . the pedigrees of family with ofd1 syndrome .this pedigree shows two females with ofd1 syndrome ( black symbols ) , five miscarriages of male fetus ( slash lines ) , and mother with mild phenotype ( gray circle ) the first patient was a 9-year - old girl with a birth weight of 3200 g who was born to a family with non - consanguineous parents at 37 wk gestation , because of the fourth pregnancy . at birth , she had ventricular septal defect ( vsd ) diagnosed with fetal ultrasonography , and deformities of the mouth , jaw , and palate were remarkable . she also started to speak her first words at the age of two . at the time of the study , oral abnormalities included cleft palate , malaligned , abnormal dentition , macroglossia , ankyloglossia , multiple hyperplastic frenulums , and a bifid , lobulated tongue . facial abnormalities that could be seen in the patient were dolichocephaly , macrocephaly ( 54.3 cm- 88 percentile ) , saddle nose deformity , low set ears , downslant palpebral fissures , and thin hair and eyebrows ( fig . brain magnetic resonance imaging ( mri ) revealed heterotopia in right cingulate cortex and brain computed tomography ( ct ) scan showed ectopic gray matter in right posterior parasagittal ( fig . clinical features of case 1 & 2 ; a , b , e & f : distinctive facial features , c & g : malaligned dentition , d & h : bifid tongue & nodules in the lateral border of tongue brain magnetic resonance imaging ( mri ) findings of patient 1(iii iv ) , a & b : axial and coronal ( flair ) view indicates heterotopia in right cingulate cortex . c : computed tomography ( ct ) scan of the patient 1(iii iv ) shows ectopic gray matter in right posterior parasagittal . the second patient was a 4-yr - old girl born as the result of the seventh pregnancy at 36 wk of gestation with a birth weight of 3300 g. the patient could walk without support at 15 months . she had the following abnormalities : dolichocephaly , macrocephaly ( 51 cm- 66 percentile ) , multiple and malaligned dentition , cleft lip and palate , asymmetric , bifid and lobulated tongue , macroglossia , multiple hyperplastic frenulum , ankyloglossia , low set ears , downslant palpebral fissures , and thin hair and eyebrows ( fig . her brain mri and ct - scan had normal findings and no renal abnormalities such as polycystic kidney ( pkd ) were identified . she had a history of five abortions of malformed male fetuses ( iii - i , iii - ii , iii iv , iii v and iii vi ) . the abortions of all male fetuses happened during her third month of pregnancy . although the mother experienced consecutive abortions with two affected daughters , she did not attend any genetic counseling , which caused delay in diagnosis of the disease . we extracted genomic dnas from the peripheral blood samples using the reliaprep kit ( blood gdna miniprep system , promega ) . the mutational hotspot within 8 exons of ofd1 ( including exons 2 , 3 , 7 , 8 , 9 , 12 , 13 and 16 ) were amplified based on standard protocols . then , the study employed 3730 dna analyzer and bigdye terminator v3.1 cycle sequencing kit ( applied biosystems ) for sequencing of the pcr products in both directions . our genetic studies identified a novel 2-base pair deletion ( c.1964 - 1965delga ) in exon 16 of ofd1 leading to a frame shift ( p.arg654x ) in two patients and their mother ( fig . the mutation has not been previously reported , nor is present in the nhlbi exome sequencing project exome variant server ( september 2013 ) , complete genomics ( february 2012 ) , dbsnp ( 134137 ) , 1000 genomes ( may 2012 ) and exome aggregation consortium ( exac ) , cambridge , ma and as it was expected it was absent in the father and the brother of mother . the study was approved by ethics committee of yazd university of medical sciences and informed written consent was obtained from the all subjects participating in the study . a female sibship was referred to the medical genetics department of yazd university of medical sciences due to craniofacial and oral dysmorphism in addition to neurodevelopmental delay . the patients were thoroughly examined and all their clinical records were reviewed by a physician . a three - generational pedigree for the family was constructed based on their family history obtained by a genetic counselor ( fig . the pedigrees of family with ofd1 syndrome .this pedigree shows two females with ofd1 syndrome ( black symbols ) , five miscarriages of male fetus ( slash lines ) , and mother with mild phenotype ( gray circle ) the first patient was a 9-year - old girl with a birth weight of 3200 g who was born to a family with non - consanguineous parents at 37 wk gestation , because of the fourth pregnancy . at birth , she had ventricular septal defect ( vsd ) diagnosed with fetal ultrasonography , and deformities of the mouth , jaw , and palate were remarkable . she also started to speak her first words at the age of two . at the time of the study , oral abnormalities included cleft palate , malaligned , abnormal dentition , macroglossia , ankyloglossia , multiple hyperplastic frenulums , and a bifid , lobulated tongue . facial abnormalities that could be seen in the patient were dolichocephaly , macrocephaly ( 54.3 cm- 88 percentile ) , saddle nose deformity , low set ears , downslant palpebral fissures , and thin hair and eyebrows ( fig . brain magnetic resonance imaging ( mri ) revealed heterotopia in right cingulate cortex and brain computed tomography ( ct ) scan showed ectopic gray matter in right posterior parasagittal ( fig . clinical features of case 1 & 2 ; a , b , e & f : distinctive facial features , c & g : malaligned dentition , d & h : bifid tongue & nodules in the lateral border of tongue brain magnetic resonance imaging ( mri ) findings of patient 1(iii iv ) , a & b : axial and coronal ( flair ) view indicates heterotopia in right cingulate cortex . c : computed tomography ( ct ) scan of the patient 1(iii iv ) shows ectopic gray matter in right posterior parasagittal . the second patient was a 4-yr - old girl born as the result of the seventh pregnancy at 36 wk of gestation with a birth weight of 3300 g. the patient could walk without support at 15 months . she had the following abnormalities : dolichocephaly , macrocephaly ( 51 cm- 66 percentile ) , multiple and malaligned dentition , cleft lip and palate , asymmetric , bifid and lobulated tongue , macroglossia , multiple hyperplastic frenulum , ankyloglossia , low set ears , downslant palpebral fissures , and thin hair and eyebrows ( fig . her brain mri and ct - scan had normal findings and no renal abnormalities such as polycystic kidney ( pkd ) were identified . she had a history of five abortions of malformed male fetuses ( iii - i , iii - ii , iii iv , iii v and iii vi ) . the abortions of all male fetuses happened during her third month of pregnancy . although the mother experienced consecutive abortions with two affected daughters , she did not attend any genetic counseling , which caused delay in diagnosis of the disease . we extracted genomic dnas from the peripheral blood samples using the reliaprep kit ( blood gdna miniprep system , promega ) . the mutational hotspot within 8 exons of ofd1 ( including exons 2 , 3 , 7 , 8 , 9 , 12 , 13 and 16 ) were amplified based on standard protocols . then , the study employed 3730 dna analyzer and bigdye terminator v3.1 cycle sequencing kit ( applied biosystems ) for sequencing of the pcr products in both directions . our genetic studies identified a novel 2-base pair deletion ( c.1964 - 1965delga ) in exon 16 of ofd1 leading to a frame shift ( p.arg654x ) in two patients and their mother ( fig . 4 ) . the mutation has not been previously reported , nor is present in the nhlbi exome sequencing project exome variant server ( september 2013 ) , complete genomics ( february 2012 ) , dbsnp ( 134137 ) , 1000 genomes ( may 2012 ) and exome aggregation consortium ( exac ) , cambridge , ma and as it was expected it was absent in the father and the brother of mother . we found a novel 2-base pair deletion ( c.1964 - 1965delga ) in exon 16 of ofd1 gene causing abnormal phenotypes in two children and their mother , which affirmed the ofd1 syndrome . oral , facial and digital abnormalities are main criteria in the diagnosis of ofd1 . in spite of the severe phenotypic picture observed in the affected sisters , a suspected diagnosis ofds had not been suggested until thorough clinical examinations , in particular oral evaluation , of the sibling . the variable presentation of signs and symptoms in ofds makes the diagnosis of each type very difficult . we could not distinguish x - linked ofds from autosomal recessive variants just based on oral , facial and neurological features of the patients . the ofds type 1 was established only after clinical findings in the sibling and their mother , pedigree analysis and finally the genetic screening of the ofd1 gene . although the findings described for ofd1 overlap with those observed in other ofds types , in familial cases , it can be differentiated because of its x - linked dominant inheritance with multiple male lethality and absence of parental consanguinity from pedigree analysis ( 20 ) . unsurprisingly , affected individuals in this family did not display all traditionally key features of ofds , thus confirming once again the variable phenotypic spectrum of ofds . for instances , in this family neither of the patients have digital abnormalities which occur in 88% of patients with ofds ( 12 ) . in addition , polycystic kidney was not observed in the family which is almost present in all the affected individuals with ofds in their adulthood ( 21 ) . however , absence of the kidney features in the affected sisters can be due to their young age and there is a very high risk for pkd in the patients . since pkd leads to renal failure careful morphological assessments and biochemical monitoring of renal function in the family is necessary . structural brain malformation in patients with ofd1 has often been found in 88.7% among patients displaying neurological symptoms or / and cognitive / behavioral abnormalities . the most frequent anomalies of brain structure included disorders of neuronal migration and organisation , agenesis of the corpus callosum , intracerebral cysts , cerebellar malformations and porencephaly ( 3 ) . brain mri analysis of the older sister did not find any abnormalities and younger affected individual only presented malformation of cortical development ( mcd ) including grey matter heterotopias . although macrocephaly is a cardinal clinical feature in x - linked recessive ofd1 neurodevelopmental syndromes in males , it has never been reported in ofds type 1 . the mother of the patients was presented with a milder phenotype than that of her daughters ( 20 ) . clinical features in the mother of the patients were noticed only after presentation of severe symptoms in her daughters . milder phenotype in the mother and clinical variability in the affected children , which is common for ofd1 , poses challenges for accurate diagnosis and genetic counselling . it can be explained because of the different degree of somatic mosaicism x - inactivation ( 20 ) . modifier genes can also be important factor for variability in families with ofd1 patients ( 22 ) . male lethality in ofd1 usually occurs in the first or second trimester of pregnancy and only more than a dozen exceptional male cases with mutation in ofd1 have been reported to date . in this family mutation detection in ofd1 is necessary for definitive diagnosis , especially for genetic counselling , preimplantation genetic diagnosis ( pgd ) and/or prenatal diagnosis . 5 demonstrates the frequency of reported ofd1 mutations ( 6 , 10 , 1417 , 2230 ) . majority of mutations in ofd1 have been identified in exons 3 , 7 , 8 , 9 , 12 , 13 and 16 , which may represent mutational hotspots . the mutation identified in this family is a two base - pair deletion mutation , which has not been previously reported , in exon 16 causing frameshift . as with most of the mutations that have been described in the gene , it is predicted to cause premature truncation of the protein that would probably result in loss of function . however , a phenotypegenotype correlation between the location of mutations and some variable clinical features of ofd1 has been suggested . for example , intellectual disability is more associated with mutations in exons 3 , 8 , 9 , 13 and 16 ( 3 ) . square ( frame shift ) , triangle ( splice site ) , star ( nonsence ) , circle ( missense ) , diamond ( in - frame deletion ) and red symbols indicating mutations found in males with ofd1 x - linked recessive disorder . we identified a novel truncating mutation in ofd1 in three female members of a family displaying variable symptoms and severity of clinical manifestation of ofds type 1 . as observed in previous cases with ofd1 , phenotypic variability even within a family is possibly a rule rather than the exception . hence , this report emphasizes importance as well as the challenges of genetic counseling for ofd1 patients and their relatives . in cases of ofds , thorough physical examination , collecting the family history and genetic screening of the affected individuals and their female relatives , along with monitoring of renal function are mandatory . ethical issues ( including plagiarism , informed consent , misconduct , data fabrication and/or falsification , double publication and/or submission , redundancy , etc . ) have been completely observed by the authors .

oral - facial - digital syndrome as heterogeneous developmental conditions is characterized by abnormalities in the oral cavity , facial features and digits . furthermore , central nervous system ( cns ) abnormalities can also be part of this developmental disorder . at least 13 forms of ofds based on their pattern of signs and symptoms have been identified so far . type 1 which is now considered to be a ciliopathy accounts for the majority of cases . it is transmitted in an x - linked dominant pattern and caused by mutations in ofd1 gene , which can result in embryonic male lethality . in this study , we present a family suffering from orofaciodigital syndrome type i who referred to medical genetics research center , shahid sadoughi university of medical sciences in 2015 . two female siblings and their mother shared a novel 2-base pair deletion ( c.1964 - 1965delga ) in exon 16 of ofd1 gene . clinically , the sibling had oral , facial and brain abnormalities , whereas their mother is very mildly affected . she also had history of recurrent miscarriage of male fetus .

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Please click below to Get Started. ||||| Northern Virginia Bureau Chief Julie Carey reports on an upcoming investigation into the attack on Creigh Deeds and suicide of his son Tuesday. (Published Wednesday, Nov. 20, 2013) Virginia State Sen. Creigh Deeds was upgraded to good condition at the University of Virginia Medical Center Wednesday, one day after he was apparently stabbed by his son, News4 Northern Virginia Bureau Chief Julie Carey reported. The son, 24-year-old Austin "Gus" Deeds, died at the scene. An autopsy Wednesday confirmed that Gus Deeds died of a self-inflicted gunshot wound. "Based on the evidence we have right now, we are looking into this as an attempted murder and suicide," said Virginia State Police spokeswoman Corinne Geller. State police have stopped short of confirming what other sources had told News4: That 24-year-old Austin "Gus" Deeds stabbed his father and then killed himself. But state police did confirm that the two had an altercation outside Deeds' Bath County home, and that Creigh Deeds suffered multiple stab wounds to the head and upper torso. Deeds Improving at Hospital After Stabbing; Son Dead News4's Jackie Bensen is live in Charlottesville, where Va. Senator Creigh Deeds is recovering from stabbing wounds allegedly inflicted by his 24-year-old son Tuesday. (Published Tuesday, Nov. 19, 2013) Deeds, 55, was able to walk out of the home and down a hill on his property (seen in the picture below) to Route 42, where he was spotted and picked up by a cousin, who took the senator to his residence. Deeds was airlifted to UVa. Medical Center, where he was initially listed in critical condition and was treated in the intensive care unit. Police Believe Sen. Deeds' Son Attacked His Father Before Killing Himself Virginia State Sen. Creigh Deeds is improving in the hospital, Northern Virginia Bureau Chief Julie Carey reports. Police believe his son stabbed him before taking his own life. (Published Tuesday, Nov. 19, 2013) "I'm so relieved he's doing better, but the tragedy is that he'll be living with this for the rest of his life," said Va. Sen. Janet Howell, a friend and colleague of Deeds. Troopers and first responders attempted to treat Gus Deeds, but he died at the scene. His body was taken to the medical examiner in Roanoke for an autopsy. Investigators recovered a firearm at the scene. The autopsy indicated that the shot was fired from a rifle. Reaction to Va. State Senator Creigh Deeds' Stabbing Jim Vance gives an update on the stabbing of Virginia State Sen. Creigh Deeds, who is now listed in fair condition. Deeds' colleague Delegate Scott Surovell and outgoing Virginia Gov. Bob McDonnell gave their reactions to Deeds' stabbing. (Published Tuesday, Nov. 19, 2013) Police are not seeking any other suspects, Geller said. Virginia State Police said in a press conference Tuesday that they believe the incident happened shortly before 7:25 a.m., when the Bath County Sheriff's Department received the 911 call. They are not sure who placed the call. RAW VIDEO: 3 p.m. Deeds Stabbing News Conference Virginia State Police spokeswoman Corinne Geller held a press conference at 3 p.m. Tuesday on the ongoing investigation into the stabbing of Virginia State Sen. Creigh Deeds and the death of his son. (Published Tuesday, Nov. 19, 2013) Creigh Deeds has been able to speak to investigators, Geller said. The Bath County Sheriff's Department is assisting Virginia State Police with the investigation. The incident has raised new questions about the capacity of Virginia's mental health system. Tuesday, it was reported that hours before the attack Gus Deeds was the subject of an emergency custody order -- but a bed at a hospital or psychiatric treatment facility was not available, and he was released home. Sources: Son Stabs Va. Sen. Deeds, Fatally Shoots Self Virginia State Sen. Creigh Deeds was stabbed Tuesday morning by his son, Austin "Gus" Deeds, before the son fatally shot himself, Democratic sources tell News4. (Published Tuesday, Nov. 19, 2013) Now the Washington Post is reporting that three hospitals within a two-hour drive of Bath County did have beds available, and two of the three say they were never contacted by the Rockbridge County Community Services Board trying to find a placement for Deeds son. The state inspector general has now launched an investigation to find out what led to Gus Deeds' release after the custody order was issued. "Regardless of whether or not there were beds, there was not a system to determine if there were beds available," Howell said. "It seems to me we should have a clearinghouse of some kind so that when somebody needs a bed, there is a very efficient way to find out where one is available." RAW: Va. State Police Discuss Creigh Deeds Virginia State Sen. Creigh Deeds was stabbed Tuesday morning by his son, Austin "Gus" Deeds, before the son fatally shot himself, Democratic sources tell News4. (Published Tuesday, Nov. 19, 2013) The assault shocked many throughout the commonwealth. "The news from this morning is utterly heartbreaking," said Virginia Gov. Bob McDonnell. "Creigh Deeds is an exceptional and committed public servant who has always done what he believes is best for Virginia and who gives his all to public service." Four years ago, Deeds, a Democrat, lost badly to Republican McDonnell in the Virginia governor's race, although Barack Obama had carried the commonwealth just a year earlier. Larry Sabato, director of the University of Virginia's Center for Politics, said the loss was a reaction to Obama's election in 2008, and a harbinger of the Tea Party surge. But Deeds has held strong as a Democrat in a legislative district that encompasses both the urban center of Charlottesville and more rural, typically Republican areas of far western Virginia. Deeds has also been helped by his home turf of Bath County, which is typically Republican but turns out the vote for one of their own, Sabato said. Colleagues of Sen. Deeds said they've heard of difficulties with his son but never imagined an outcome like this. Gus Deeds withdrew from the College of William & Mary last month, the college said in a statement Tuesday afternoon. He had been enrolled there since 2007, although not continuously. He was a music major with "a strong academic record," according to the school. "Our hearts go out to the entire Deeds family," the school's statement read in part. The same year his father ran for governor, Gus Deeds, then 20, was arrested in Bath County for alcohol possession, according to the Virginian Pilot. "This is a truly sad day for Virginia and for the many people who know Creigh as the fine public servant and friend he is," said Virginia Gov.-elect Terry McAuliffe, whom Deeds defeated in the Democratic primary in 2009. "We join people across the Commonwealth and country in wishing him a full recovery." Mark Warner, who campaigned for Deeds in 2009, said: Stunning news from Bath County. I am praying for @CreighDeeds and his family at this very, very difficult time. — Mark Warner (@MarkWarner) November 19, 2013 That sentiment was echoed by Virginia Delegate David Toscano, who represents Albemarle County in the General Assembly: Our thoughts and prayers are with @CreighDeeds and his family. — David J. Toscano (@deltoscano) November 19, 2013 Creigh Deeds has been a Virginia state senator since 2001, representing Virginia's 25th District. He served in the House of Delegates for 10 years prior and ran unsuccessfully for attorney general of Virginia in 2005 before his run for governor in 2009. Deeds and his first wife, Pam, divorced after nearly 20 years of marriage in 2010. The couple also has three daughters. Deeds married his second wife in June 2012. She was not home at the time of the altercation. Stay with NBCWashington for more on this developing story. ALSO SEE: ||||| Over the years, Richmond.com has published several data projects using public information. Here's a sampling of some of those projects. - Our annual database of state employee salaries was recently updated with 2016-17 data. - Our salary database of local government employees was updated recently with the 2016-17 data.

– Virginia state Sen. Creigh Deeds is in critical condition after being stabbed in what state police are calling an "assault" at his rural home early this morning—with Democratic sources telling NBC Washington that his son, Gus, was the one who stabbed his father before turning a gun on himself. Virginia State Police further confirm that Austin "Gus" Deeds is dead of a gunshot wound, reports the Richmond Times-Dispatch, and will confirm only that they are not seeking other suspects at this time. The elder Deeds was airlifted to the University of Virginia for what a police rep describes as "serious" injuries; he was reportedly stabbed a number of times in the head and torso then walked down a private drive to a road where a cousin picked him up. It's unclear how the cousin was notified, but Deeds was taken to UVA from the cousin's farm. Daily Progress has this quote from Delegate David J. Toscano: "This is a terrible tragedy. Senator Deeds was very close to his son Gus, and has taken herculean efforts to help him over the years." The Daily Progress notes that Gus was the 2007 valedictorian of his high school, and went on to attend William & Mary. Deeds, a prominent statewide political figure who narrowly lost the 2005 attorney general's race and resoundingly lost the 2009 gubernatorial race, both to current Gov. Bob McDonnell, represents rural Bath County.

SECTION 1. FINDINGS AND PURPOSES. (a) Findings.--The Congress finds that-- (1) there are situated in the State of Tennessee the sites of several key Civil War battles, campaigns, and engagements; (2) certain sites, battlefields, structures, and areas in Tennessee are collectively of national significance in the history of the Civil War; (3) the Civil War Sites Advisory Commission, established by Congress in 1991, identified 38 sites in Tennessee as significant; (4) the preservation and interpretation of these sites will make an important contribution to the understanding of the heritage of the United States; (5) the preservation of Civil War sites within a regional framework requires cooperation among local property owners and Federal, State, and local government entities; and (6) partnerships between Federal, State, and local governments and their regional entities, and the private sector, offer the most effective opportunities for the enhancement and management of the Civil War battlefields and related sites located in Tennessee. (b) Purposes.--The purposes of this Act are-- (1) to preserve, conserve, and interpret the legacy of the Civil War in Tennessee; (2) to recognize and interpret important events and geographic locations representing key Civil War battles, campaigns, and engagements in Tennessee; (3) to recognize and interpret the effect of the Civil War on the civilian population of Tennessee during the war and postwar reconstruction period; and (4) to create partnerships among Federal, State, and local governments and their regional entities, and the private sector to preserve, conserve, enhance, and interpret the battlefields and associated sites associated with the Civil War in Tennessee. SEC. 2. DEFINITIONS. As used in this Act: (1) The term ``national heritage area'' means the Tennessee Civil War Heritage Area as designated pursuant to section 3. (2) The term ``Secretary'' means the Secretary of the Interior. (3) The term ``compact'' means the compact approved under section 4. (4) The term ``management plan'' means the management plan submitted under section 5. SEC. 3. TENNESSEE CIVIL WAR HERITAGE AREA. (a) Designation.--Upon publication by the Secretary in the Federal Register of notice that a compact regarding the Tennessee Civil War Heritage Area has been approved by the Secretary in accordance with this Act, there shall be designated the Tennessee Civil War Heritage Area. (b) Boundaries.--The Tennessee Civil War Heritage Area shall be comprised of areas of the State of Tennessee depicted on the map entitled ``Tennessee Civil War Heritage Area''. The map shall be on file and available for public inspection in the office of the Director of the National Park Service. (c) Administration.--The national heritage area shall be administered in accordance with the compact and the management plan. SEC. 4. COMPACT. (a) Compact.--The compact referred to in section 3(a) shall include information relating to the objectives and management of the area proposed for designation as a national heritage area. Such information shall include (but not be limited to) each of the following: (1) A delineation of the boundaries of the proposed National Heritage Area. (2) A discussion of the goals and objectives of the proposed national heritage area, including an explanation of the approach, proposed by the partners referred to in paragraph (4), to conservation and interpretation of resources. (3) An identification and description of the management entity that will administer the proposed national heritage area. (4) A list of the initial partners to be involved in developing and implementing the management plan for the proposed national heritage area, and a statement of the financial commitment of the partners. (5) A description of the role of the State of Tennessee. (b) Preparation of and Actions Called For in Compact.--The compact shall be prepared with public participation. Actions called for in the compact shall be likely to be initiated within a reasonable time after designation of the proposed national heritage area and shall ensure effective implementation of the State and local aspects of the compact. (c) Approval and Disapproval of Compacts.--(1) The Secretary, in consultation with the Governor of Tennessee, shall approve or disapprove the proposed compact not later than 90 days after receiving such compact. (2) If the Secretary disapproves a proposed compact, the Secretary shall advise, in writing, the reasons for the disapproval and shall make recommendations for revisions of the proposed compact. The Secretary shall approve or disapprove a proposed revision to such a compact within 90 days after the date on which the revision is submitted to the Secretary. SEC. 5. MANAGEMENT. (a) Management Plans.--A management plan submitted under this Act for the national heritage area shall present comprehensive recommendations for the conservation, funding, management, and development of the area. The management plan shall-- (1) be prepared with public participation; (2) take into consideration existing Federal, State, county, and local plans and involve residents, public agencies, and private organizations in the area; (3) include a description of actions that units of government and private organizations are recommended to take to protect the resources of the area; (4) specify existing and potential sources of funding for the conservation, management, and development of the area; and (5) include the following, as appropriate: (A) An inventory of the resources contained in the national heritage area, including a list of property in the area that should be conserved, restored, managed, developed, or maintained because of the natural, cultural, or historic significance of the property as it relates to the themes of the area. (B) A recommendation of policies for resource management that consider and detail the application of appropriate land and water management techniques, including (but not limited to) the development of intergovernmental cooperative agreements to manage the historical, cultural, and natural resources and the recreational opportunities of the area in a manner consistent with the support of appropriate and compatible economic viability. (C) A program, including plans for restoration and construction, for implementation of the management plan by the management entity specified in the compact for the area and specific commitments, for the first 5 years of operation of the plan, by the partners identified in the compact. (D) An analysis of means by which Federal, State, and local programs may best be coordinated to promote the purposes of this Act. (E) An interpretive plan for the National Heritage Area. (b) Management Entities.--The management entity for the national heritage area shall do each of the following: (1) Develop and submit to the Secretary a management plan not later than three years after the date of the designation of the area as a national heritage area. (2) Give priority to the implementation of actions, goals, and policies set forth in the compact and management plan for the area, including-- (A) assisting units of government, regional planning organizations, and nonprofit organizations-- (i) in conserving the national heritage area; (ii) in establishing and maintaining interpretive exhibits in the area; (iii) in developing recreational opportunities in the area; (iv) in increasing public awareness of and appreciation for the natural, historical, and cultural resources of the area; (v) in the restoration of historic buildings that are located within the boundaries of the area and relate to the themes of the area; and (vi) in ensuring that clear, consistent, and environmentally appropriate signs identifying access points and sites of interest are put in place throughout the area; and (B) consistent with the goals of the management plan, encouraging economic viability in the affected communities by appropriate means. (3) In developing and implementing the management plan for the area, consider the interests of diverse units of government, businesses, private property owners, and nonprofit groups within the geographic area. (4) Conduct public meetings at least quarterly regarding the implementation of the management plan for the area. (c) Clearing House.--The Congress recognizes the Center for Historic Preservation at Middle Tennessee State University as the clearing house for the Tennessee Civil War Heritage Area. SEC. 6. DUTIES AND AUTHORITIES OF FEDERAL AGENCIES. (a) Secretary of the Interior.--The Secretary-- (1) may provide technical assistance to units of government and private nonprofit organizations regarding feasibility studies and the compact and, upon request of the management entity for the national heritage area, regarding the management plan and its implementation; (2) may not, as a condition of the award of technical assistance under this section, require any recipient of such technical assistance to enact or modify land use restrictions; and (3) may not make limitations on fishing, hunting, or trapping a condition for the approval of the compact or the determination of eligibility for technical assistance under this section. (b) Duties of Other Federal Agencies.--Any Federal entity conducting any activity directly affecting the national heritage area shall consider the potential effect of the activity on the management plan for the area and shall consult with the Governor of Tennessee with respect to the activity to minimize the adverse effects of the activity on the area. SEC. 7. SAVINGS PROVISIONS. (a) Lack of Effect on Authority of Governments.--Nothing in this Act shall be construed to modify, enlarge, or diminish any authority of the Federal, State, or local governments to regulate any use of land as provided for by law or regulation. (b) Lack of Zoning or Land Use Powers of Entity.--Nothing in this Act shall be construed to grant powers of zoning or land use to any management entity for the national heritage area. (c) Fish and Wildlife.--The designation of the national heritage area shall not diminish the authority of the State of Tennessee to manage fish and wildlife, including the regulation of fishing and hunting within such area. SEC. 8. AUTHORIZATION OF APPROPRIATIONS. There is authorized to be appropriated such sums as may be necessary to carry out this Act.

Designates the Tennessee Civil War Heritage Area in Tennessee upon notification in the Federal Register by the Secretary of the Interior that a compact relating to the objectives and management of the Area has been approved by the Secretary. Requires the management plan to be developed and submitted to the Secretary by the management entity for the Area to present comprehensive recommendations for the conservation, funding, management, and development of the Area. Recognizes the Center for Historic Preservation at Middle Tennessee State University as the clearinghouse for the Area. Authorizes appropriations.

the cavities of elliptical / roundish planetary nebulae ( pne ) are not empty but instead filled - up with hot gas originating from the shock - heated fast stellar wind . space - born x - ray telescopes ( rosat , xmm - newton , chandra ) revealed that these wind - blown `` bubbles '' are the source of rather soft x - ray emission , with typical plasma temperatures between 1 and 3 mk ( see kastner 2012 ) . the low plasma temperature observed is substantially _ below _ the post - shock temperature of about 10 mk expected from the high observed velocities of the stellar wind . possible `` cooling '' processes are either heat conduction in the absence of magnetic fields ( soker 1994 ; steffen 2008 ) and/or dynamical mixing of matter across the bubble / nebula interface ( toal & arthur 2016 ) . the latest 2d simulations by @xcite suggest that heat conduction is indispensable for achieving the observed high x - ray emission measures . the case of bd+30@xmath03639 is special in three aspects : i ) a hydrogen - poor wind interacts with a nebular shell of normal , hydrogen - rich composition ; ii ) it is the brightest pn x - ray source , allowing to take high - resolution spectra ( yu 2009 ) ; iii ) it is a young , still unevolved nebula , obviously shortly after the conversion to a hydrogen - poor central star has taken place . a detailed analysis of the x - ray spectrum with respect to elemental abundance ratios and the existence of a possible abundance discontinuity within the bubble produced by heat conduction is thus very rewarding . all the existing spectral analyses of this nebula are based on simple plasma models with constant densities and temperatures . in their analysis of the bubble of bd+30@xmath03639 , @xcite and @xcite needed a two - temperature plasma ( 1.9 and 3.0 mk ) to account for the emission from species with different degree of ionisation . the derived chemical abundances appeared to be rather unusual : very high ratios of c / o and ne / o , exceeding by far the corresponding solar ratios . from the physical point of view , such a low - temperature plasma is fully inconsistent with its outer and inner boundary conditions , viz . the nebular shell and the fast stellar wind . in the following we report briefly on our new approach to analyse the x - ray emission from hot bubbles by means of a physically more sound model . details will be published in a forthcoming journal paper . our newly developed analysis tool is based on self - similar solutions for wind - blown bubbles formed by the interaction of two spherical winds with different densities and velocities , as developed by zhekov & perinotto ( 1996 , 1998 ) . these so - called zp96-bubbles contain heat conduction across the bubble from the reverse wind shock to the contact discontinuity / conduction front . the general properties of these bubbles can be characterised as follows : + _ inner boundary condition . _ power - law representation of the fast stellar wind from an evolving 0.595 m@xmath2 central star , time - dependent mass - loss rate and velocity , adapted for bd+30@xmath03639 according to @xcite . + _ outer boundary condition . _ constant slow wind with explored parameter ranges @xmath3 m@xmath2yr@xmath4 and 10 40 kms@xmath4 . + _ chemical composition . _ each bubble has either a hydrogen - deficient ( `` wr '' ; marcolino 2007 ) or hydrogen - rich ( `` pn '' ) chemical composition , with appropriate conduction coefficients . also , chemically inhomogeneous bubbles are constructed to allow for `` evaporated '' pn matter behind the conduction front . the wr composition is extremely helium- , carbon- , and oxygen - rich : he : c : o = 0.43:0.51:0.06 by mass ( marcolino 2007 ) . + _ x - ray emission . _ the x - ray spectrum is computed by means of the well - documented chianti code , v6.0.1 ( dere 2009 ) . altogether , about 1000 bubbles have been generated , spanning ages from 200 to 1000 years , corresponding characteristic x - ray temperatures , @xmath5 ( eq . 17 in steffen 2008 ) , between 1.1 and 3.9 mk ( wr ) or between 1.1 and 6.8 mk ( pn ) . wr - bubbles with ages of 400500 yr have sizes and x - ray luminosities which correspond well to the respective values observed for bd+30@xmath03639 . the structure of a bubble with a chemical discontinuity is displayed in fig.[fig1 ] . our analysis of the x - ray emission from bd+30@xmath03639 s bubble rests exclusively on the high - resolution observations reported in @xcite . we first used our zp96-bubbles with wr composition to fix the characteristic plasma temperature @xmath5 . the result is seen in fig.[tx ] . one sees that all bubbles nearly degenerate so that a unique plasma temperature can easily be derived from the oxygen and neon line ratios : @xmath6 mk . this temperature value , obtained from the zp96 bubbles , is also marginally consistent with magnesium . we emphasise that constant - temperature plasma models _ can not _ provide a unique value for @xmath5 ( fig.[tx ] , right ) ! for the further analysis , we have to check whether those bubbles from our grid that have the right temperature @xmath5 can also reproduce the observed line ratios of carbon and neon with respect to oxygen . however , it turns out that _ none _ of our bubbles with homogeneous wr composition is able to reproduce the observed line ratios ne / c and o / c ( fig.[consistence ] ) . the discrepancies amount to one order of magnitude , at least ! -1 mm the large discrepancy between models and observation seen in the right line ratio diagram in fig.[consistence ] can not be remedied by changing the input abundances of our wr composition because they are fixed by the analyses of the stellar wind of bd+30@xmath03639 ( e.g. marcolino 2007 ) , with the exception of neon whose abundance has been chosen by us . instead , one has to conclude that the bubble of bd+30@xmath03639 contains , as the consequence of `` evaporation '' , some hydrogen - rich pn matter immediately behind the conduction front . the pn - matter contains much less carbon ( and oxygen as well ) , so that even small amounts of pn matter will drastically change the carbon line strengths , and to a lesser degree those of oxygen and neon lines because the corresponding ions reside in the inner , hotter bubble regions . figure[consistence.2 ] illustrates how the inclusion of pn matter changes the relevant line ratios . the discrepancy in the abundance sensitive panel ( middle ) is substantially reduced , although there is still some disagreement between the models and the observations . the square represents our best - fit model as a compromise between the temperature criteria and the abundance ratios : @xmath7 with age = 500 yr ( cf . fig[fig1 ] ) , together with appropriate bubble size and x - ray luminosity . so far we have implicitly assumed that the bubble s ne abundance , which is not really constrained by photospheric / wind analyses , comes from the complete processing of cno matter into n , followed by conversion to ne during a thermal pulse on the agb . this leads to a mass fraction of 0.022 . by comparing the observed ne / o line ratio with the model predictions , we conclude that the ne abundance in the bubble of bd+30@xmath03639 must be higher by a factor of about 2.5 ( compared to oxygen ) , i.e. we have about equal amounts ( by mass ) of o and ne ( at least @xmath10.06 ) ! combined with a higher o / c ratio as proposed by @xcite , full consistency between both the temperature sensitive and abundance sensitive diagrams in fig.[consistence.2 ] is achieved . in this case , the ne content would be even higher ( up to 0.09 by mass ) . we have developed a new tool for analysing the x - ray emission from wind - blown bubbles with thermal conduction . application to existing high - resolution data for bd+30@xmath03639 shows that its x - ray line emission can only be explained if the bubble contains i ) helium- , carbon- , and oxygen - enriched matter as found in the stellar photosphere / wind , especially enriched by neon , and ii ) a shell of hydrogen - rich pn matter of about 3% by mass behind the conduction front . it appears that heat conduction is a viable option for explaining the diffuse x - ray emission from wind - blown bubbles . more high - resolution x - ray observations are urgently needed for further testing our analytical bubble models . of course , new analyses of existing low - resolution x - ray spectra would also benefit from our heat - conduction chemically stratified bubble models .

we developed a model for wind - blown bubbles with temperature and density profiles based on self - similar solutions including thermal conduction . we constructed also heat - conduction bubbles with chemical discontinuities . the x - ray emission is computed using the well - documented chianti code ( v6.0.1 ) . these bubble models are used to ( re)analyse the high - resolution x - ray spectrum of the hot bubble of bd+30@xmath03639 , and they appeared to be much superior to constant temperature approaches . we found for the x - ray emission of bd+30@xmath03639 that temperature - sensitive and abundance - sensitive line ratios computed on the basis of heat - conducting wind - blown bubbles and with abundances as found in the stellar photosphere / wind can only be reconciled with the observations if the hot bubble of bd+30@xmath03639 is chemically stratified , i.e. if it contains also a small mass fraction ( @xmath13% ) of hydrogen - rich matter immediately behind the conduction front . neon appears to be strongly enriched , with a mass fraction of at least about 0.06 .

binary stars represent perhaps the most valuable targets for stellar astrophysics . they have been a source of insight into the structure and evolution of stars , theory of radiative transfer , stellar magneto- and hydrodynamics , and the newtonian theory of gravity , to mention just a few major topics ( shore 1994 ) . after discovery of the first binary pulsar 1913 + 16 , these objects have become excellent gravitational laboratories for testing general relativity by using radio observations ( taylor 1992 , 1994 ) . nevertheless , optical observations of binary stars continue to remain one of the most important sources of getting qualitatively new astronomical information . the reason is that the amount of binary stars observable at optical wavelenghts overwhelmingly exceeds the number of objects accessible for radio , x - ray , and/or @xmath3-ray observations . moreover , distribution of the relative orientation of binary orbits ranging from the edge - on to the face - on , allows one to obtain valuable information in studying different stellar phenomena . therefore , increasing accuracy of optical measurements of binary stars is a real challenge for modern astronomy . this is why precision doppler measurements of stellar spectra implemented recently for the search of extrasolar planets could open a new direction in binary star research . traditional techniques in radial velocity measurements rarely achieve an accuracy better than about 200 m s@xmath4 given such an uncertainty , usually the _ linear _ doppler effect , i.e. the term of order of only @xmath5 could be only measurable . its measurement for the primary star of mass @xmath6 belonging to a binary system brings five classical keplerian parameters of the stellar orbit . they are : projected semimajor axis @xmath7 eccentricity @xmath8 orbital period @xmath9 longitude of the periastron @xmath10 and the epoch @xmath11 of the initial periastron passage . combination of these parameters makes it possible to calculate the mass function for the binary system : @xmath12 where @xmath13 is the companion mass , and @xmath2 is the inclination angle of the stellar orbit to the line of sight . obviously , the information which can be extracted from the linear doppler shift alone is incomplete to determine _ all _ orbital parameters of the binary , including the masses of its constituent stars . observations of additional relativistic effects are necessary . they include : relativistic advance of the periastron , quadratic doppler and gravitational redshifts , monotonous decrease of orbital period due to the emission of gravitational waves , and effects of deflection and retardation of electromagnetic waves in the companion s gravitational field . all of them have been observed in binary pulsars ( taylor 1992 ) but only relativistic advance of periastron could be measured with the use of conventional spectroscopic technique ( semeniuk & paczynski 1968 , guinan & maloney 1985 ) . ozernoy ( 1997a , 1997b ) pointed out that current accuracy of precision doppler measurements ( pdms ) using the iodine - based doppler technique ( valenti , butler & marcy 1995 , cochran 1996 ) is able to catch the second - order in @xmath5 effects . moreover , he also has shown , by taking into account special relativity alone , that binary stars offer a unique opportunity to disentangle the linear and quadratic in @xmath5 terms and extract such an important parameter as inclination angle . even without addressing any concrete applications , a coherent , unambiguous interpretation of pdms having an accuracy of @xmath141 m s@xmath15 or better , requires an adequate development of a relativistic theory . by present , the basic principles to construct such a theory have been well established . recently , they have been worked out in a series of publications by brumberg & kopeikin ( 1989a , 1989b , 1990 ) ( bk approach ) and damour , soffel & xu ( 1991 , 1992 , 1993 ) ( dsx approach ) . the main idea is to introduce one global and several local coordinate charts in a gravitating system consisting of @xmath16 bodies to describe adequately the properties of space - time curvature both on the global scale and locally in the vicinity of each body . the subsequent application of the mathematical technique to match the asymptotic expansions of the metric tensor in different coordinate systems allows one to obtain general relativistic transformations between these systems , which generalize lorentz transformations of special relativity . practical conclusions of two approaches are the same . in this paper , we use the bk approach to describe self - consistently the relativistic algorithm of pdms . the paper is organized as follows . in section 2 , seven appropriate coordinate frames are introduced . 3 deals with the doppler effect in special relativity , which can be important for interpretation of pdms in the situations , when effects of the gravitational field are negligibly small . the post - newtonian coordinate transformations are sketched in section 4 , along with the derivation of the equation for propagation of photons in a gravitational field . the doppler effect in general relativity is explored in section 5 . parameterization of the doppler effect and the explicit doppler shift curve are given in section 6 . section 7 outlines some observational implications of the theory . finally , section 8 contains discussion and our conclusions . the approach developed in this paper was earlier reported in kopeikin & ozernoy ( 1996 ) . a rigorous mathematical treatment of precision doppler observations of a binary star requires the use of seven ( 4-dimensional ) reference frames ( rfs ) : @xmath17 barycentric reference frame of our galaxy @xmath18 @xmath19 the solar system s barycentric reference frame @xmath20 @xmath21 the binary system s barycentric reference frame @xmath22 @xmath23 the star - centered reference frame denotes coordinate time in the star - centered reference frame and is not a wavelenght of photon . ] @xmath24 @xmath25 the earth s ( geocentric ) reference frame @xmath26 @xmath27 topocentric reference frame of terrestrial observer @xmath28 @xmath29 proper reference frame of a particle emitting light @xmath30here and hereinafter , the arrow above the letter denotes a spatial vector having three coordinates ; index 0 " relates to time coordinate , and small latin indices ( such as @xmath31 ) represent the spatial coordinates . the origin of each coordinate frame coincides with the center of mass ( barycenter ) of the respected system of gravitating bodies . for instance , the origin of the solar system rf is at the center of mass of the solar system , the origin of the emitting star s rf is at the center of mass of the star , and so on . the observer is regarded to be massless and placed at the origin of the topocentric rf . we assume that emission of light is produced by the atom placed at the origin of its own proper rf @xmath32 . each rf has its own coordinate time . these times are related to each other by means of relativistic time transformations ( brumberg & kopeikin 1989a , 1989b , 1990 ) . it is worth noting that the coordinate time of the topocentric rf coincides precisely with the proper time of the observer measured by the atomic clocks , and the coordinate time of the rf of the atom emitting light coincides with its proper time . the barycentric rf of our galaxy is considered to be asymptotically flat so that it covers all space - time . all other coordinate frames are not asymptotically flat , and they cover only restricted domains in space because of a non - zero space - time curvature . all coordinate systems are assumed to be nonrotating in the kinematical sense ( brumberg & kopeikin 1989a ) . it means that spatial axes of all rf s are aligned and anchored to the outermost quasars whose proper motions are negligibly small . to derive equations describing the doppler effect at the post - newtonian level of accuracy , we use the relativistic post - newtonian transformations between the coordinate frames . they have been formulated by kopeikin ( 1988 ) and brumberg & kopeikin ( 1989a , 1989b ) , and are discussed briefly in section 4 . however , for pedagogical reasons , it is useful to consider the doppler effect first in the framework of special relativity . the special relativistic approach is motivated by the fact that one can get the _ exact _ treatment of the problem under consideration , which will provide a guide of consistency for general relativistic calculations . it should be noted , however , that the special relativistic approach is not able to take into account the relativistic effects asssociated with an accelerated motion of bodies as well as influence of gravitational field . those efffects can be adequately considered only in framework of general relativity . the doppler effect in special relativity is usually considered only for two rfs : one is assumed to be at rest , and the other moves with respect to the first one with a constant velocity . here we discuss a more realistic situation when five coordinate systems @xmath33 and @xmath34 , introduced in the previous section , need to be considered . this situation is rather close to the real astronomical practices and it might be applied to the interpretation of spectral observations of binary stars if the influence of gravitational fields could be neglected . in this section , we abandon , for the sake of simplicity , the reference frames @xmath35 and @xmath36 . the reason is that , for the moment , we want to avoid the discussion of terms caused by the motion of the solar and binary systems about the center of our galaxy , as well as motions of the emitting particles with respect to the star . accounting for these effects will be done in later sections . the rf @xmath37 is the basic one which is considered to be at rest . the origins of the rfs @xmath38 and @xmath39 are moving with respect to @xmath37 with constant relative velocities @xmath40 and @xmath41 , respectively@xmath42 the rf @xmath39 is supposed to move with respect to the @xmath38 with a constant relative velocity @xmath43 note that , in the relativistic approach , @xmath44 the rfs @xmath45 and @xmath34 move with constant velocities @xmath46 and @xmath47 with respect to @xmath48 the relative velocity of the reference frame @xmath34 with respect to @xmath45 is @xmath49 ( again , @xmath50 @xmath51 three different approaches for discussion of doppler effect can be applied . they are based , accordingly , on the techniques of relativistic frequency transformation ( landau & lifshitz 1951 ) , successive lorentz transformations ( weinberg 1972 ) , and time transformations along with the equation of light propagation ( tolman 1934 , brumberg 1972 ) . let @xmath52 be the 4-vector of the electromagnetic wave propagating from the source of light to the observer . here and hereinafter , greek indices run from 0 to 3 , i.e. @xmath53 this is a null vector in the flat space - time . therefore , @xmath54 and @xmath55 where @xmath56 is the frequency of the electromagnetic wave and the unit spatial vector @xmath57 is tangent to the trajectory of the light ray . for convenience , it is chosen to be directed from the observer toward the point of emission . let @xmath58 be the vector of 4-velocity of a massive particle . the time component is @xmath59 and the spatial components are @xmath60 where @xmath61 is the ( constant ) lorentz - factor , @xmath62 and @xmath63 is a spatial velocity of the particle@xmath42 by contracting vectors @xmath64 and @xmath65 , one forms a scalar which is relativistically invariant as it is independent of the choice of reference frame : @xmath66 where the repeated spatial indices mean a summation from 1 to 3 . suppose that the source of light moves with respect to the observer with a constant speed @xmath67 the 4-velocity of the observer in its proper rf is defined as @xmath68 and the 4-velocity of the source of light is @xmath69 let the frequency of the emitted electromagnetic wave be @xmath70 and the received frequency be @xmath71 then , by applying equation ( [ a0 ] ) to the two different rf s one gets ( boldface letters denote spatial vectors , and the dot in between two spatial vectors stands for usual scalar product ) : @xmath72 which is a well - known result ( landau & lifshitz 1951 ) for the doppler shift of the frequency of light emitted by a moving source and received by the observer at rest . here the unit spatial vector @xmath73 is measured with respect to the observer s rf . while applying this formula , we will use slightly different notations : @xmath74 for the frequency of the emitted light and @xmath56 for the observed frequency , viz . , @xmath75 , and @xmath76 for the frequencies of light observed in reference frames @xmath77 and @xmath45 , respectively . let us also introduce a fractional frequency shift function , @xmath78 . succesive application of equation ( [ a1 ] ) yields @xmath79 here @xmath80 is the spatial unit vector tangent to the light ray and having components measured with respect to the coordinate system @xmath37 , and @xmath81 and @xmath82 represent the same tangent vector with the components measured relative to the systems @xmath38 and @xmath45 , respectively . equation ( [ a2 ] ) contains the dimensionless particle velocities @xmath83 , @xmath84 , @xmath85 , and @xmath86 . coordinates with the asterisk concern the point of emission of light , and coordinates without asterisk are related to the point of observation . it is worth noting that the components of vectors @xmath87 and @xmath88 do not coincide with those of vector @xmath89 because of the relativistic aberration of light . a remarkable feature of the formula ( [ a2 ] ) is that it represents the doppler effect as a product of four different multipliers . each factor describes transformation of frequency of light from one reference frame to another . it would be straightforward to generalize this result for the description of the doppler effect in the event of as many reference frames as necessary . because of importance of equation ( [ a2 ] ) , it is instructive to derive it by using different techniques and then to compare the results . lorentz transformations from the reference frame @xmath37 to @xmath38 is described by the matrix @xmath90 with the components ( weinberg 1972 , brumberg 1972 , 1991 ) : @xmath91 similarly , the lorentz transformation from the reference frame @xmath38 to @xmath39 is described by the matrix @xmath92 with the components : @xmath93 the lorentz transformations from the reference frame @xmath37 to @xmath94 and from @xmath45 to @xmath34 are given respectively by the matrices @xmath95 and @xmath96with the components : @xmath97 @xmath98 the relationship between time components of a light ray s 4-vector is given by the successive lorentz transformations ( the repeated greek indices imply summation from 0 to 3 ) : @xmath99 @xmath100 where @xmath101 and @xmath102 are components of the light ray vector referred to the rf s @xmath103 and @xmath34 , respectively@xmath42 by substituting the matrices of the lorentz transformations into equations ( [ a6]),([a7 ] ) and defining the null vector @xmath104 , we obtain after straightforward calculations the following result : @xmath105 at first sight , it looks quite different compared to equation ( [ a2 ] ) . however , by making relativistic transformation of vectors @xmath88 and @xmath87 to vector @xmath89 in equation ( [ a2 ] ) , one can readily show that both expressions are completely identical . in the rest of thid section , we derive , for the reader s convenience , the transformation law between vectors @xmath88 and @xmath89 . ( the transformation law between vectors @xmath87 and @xmath89 is obtained similarly by replacing index @xmath45 for @xmath38 and coordinates @xmath106 for @xmath107 ) the transformation between spatial coordinates of rfs @xmath37 and @xmath45 is given by ( weinberg 1972 , brumberg 1972 , 1991 ) : @xmath108 where the transformation matrix @xmath109 is defined in equation ( [ a5 ] ) . in its explicit form , the transformation ( [ ap1 ] ) reads @xmath110 \frac{{\bf v}_e\cdot ( { \bf x - v}_et)}{v_e^2}{\bf v}_e\;.\ ] ] let us express the coordinates of radius - vector @xmath88 connecting points of emission and observation in the rf @xmath45 through the coordinates of vector @xmath111 from eq . ( [ ap2 ] ) and equation ( [ d ] ) for light propagation one gets : @xmath112 and , as a consequence , @xmath113 now it is easy to obtain the relationship between vectors @xmath88 and @xmath89 , whisch is given by : @xmath114 .\ ] ] inversely , vector @xmath115 is obtained from equation ( [ ap5 ] ) after replacements @xmath116 , @xmath117 , and @xmath118 : @xmath119 .\ ] ] the transformations ( [ ap5 ] ) and ( [ ap6 ] ) represent , in fact , general expressions for the relativistic aberration of light rays . this can be seen from the relativistic law of addition of velocities ( weinberg 1972 , brumberg 1972 , 1991 ) . in case under consideration , it is given by : @xmath120 , \ ] ] where @xmath63 and @xmath121 are the relative velocities of a particle with respect to rfs @xmath45 and @xmath37 , respectively . for the light particle ( photon ) these velocities are @xmath122 and @xmath123 having substituted them to eq . ( [ ap7 ] ) , one obviously gets eq . ( [ ap6 ] ) . finally , using equations ( [ ap5 ] ) - ( [ ap7 ] ) , one obtains : @xmath124 one can see from equation ( [ ap9 ] ) and a similar expression for @xmath125 that equations ( [ a2 ] ) and ( [ a8 ] ) are identical . the advantage of eq . ( [ a8 ] ) over ( [ a2 ] ) is that only one vector @xmath89 enters eq . ( [ a8 ] ) , instead of three vectors @xmath126 and @xmath89 in eq . ( [ a2 ] ) . previous techniques used to derive the doppler equation have not taken into account an essential fact of separation of the two events emission and observation of light in space - time . in fact , we have implicitly assumed that the null vector @xmath64 is the same at the points of emission and observation of light . however , this is only true for a very special case of negligent gravitational field and propagation of light in vacuum . in general , this conditions are not met . therefore , a more advanced technique is required to tackle the doppler effect appropriately . such a technique , based on the integration of the equation for light propagation from the point of emission to the point of observation , establishes a relationship between coordinates of the 4-vector of a photon at these two events . transformation laws of time scales between different rfs are to be taken into account as well . this approach , being rather general and straightforward , can be applied to analyse any particular situation . in this section , we consider time transformation technique in special relativity only . its application to observations of binary stars in the framework of general relativity will be discussed in later sections . the equation of light propagation , in the absence of gravitational field and interstellar medium , is quite simple : @xmath127 @xmath128 where @xmath129 is the instant of photon emission and @xmath130 is the instant of observation of the photon , both measured as coordinate time of rf @xmath37 , in which @xmath131 is the point of emission , and @xmath132 is the point of observation . it is worth noting that , although the instants @xmath130 and @xmath133 belong to the same rf @xmath37 , their increments @xmath134 and @xmath135 are different because of a relative motion of the source of light and the observer . one can see from equation ( [ a9 ] ) that when the influences of gravitational field and the medium are both negligent , the components of the vector @xmath64 are constant everywhere on the light ray s trajectory . this makes clear why we do not care about a point in space - time in which earlier we calculated the doppler shift . however , in a more general situation , the equations ( [ a9 ] ) , ( [ d ] ) are not so simple , and this point has to be appropriately taken into consideration . doppler effect is described by the function @xmath136 where @xmath137 is the frequency of the emitted light , and @xmath138 is the observed frequency . by taking the time intervals to be infinitesimally small , we get a differential formula : @xmath139 which is nothing more but a simple rule for differentiation of an hierarchical function @xmath140 this result demonstrates as well that the doppler effect can be presented as a product of several multiplyers . a difference between equations ( [ e ] ) and ( [ a2 ] ) is that in ( [ e ] ) we use coordinate times of the respected rfs and distinguish explicitly the points of emission and observation of light . meanwhile in equation ( [ a2 ] ) only proper frequencies of the electromagnetic wave are considered . the advantage of eq . ( [ e ] ) is that , for its derivation , one needs to know only relativistic transformations between time scales , whereas transformation law between spatial coordinates is not required . as we shall see later on , this advantage is very helpful while tackling the doppler effect in general relativity . to calculate the time derivatives at the points of emission and observation , one needs incorporating time components of the lorentz transformations ( [ a3 ] ) - ( [ a5a ] ) between different rfs . they are : @xmath141 @xmath142 @xmath143 @xmath144 let us remind that observer is fixed with respect to the rf @xmath34 , and the source of light is fixed with respect to @xmath145 therefore , @xmath146 and @xmath147 velocities of the observer and the source of light relative to the rf @xmath37 are @xmath148 and @xmath149 , respectively ( it is important to note that @xmath150 and @xmath151 . therefore one obtains from ( [ a ] ) - ( [ c1 ] ) : @xmath152 @xmath153 @xmath154 @xmath155 in addition , differentiation of equation ( [ d ] ) gives : @xmath156 substitution of expressions ( [ f ] ) - ( [ i ] ) into eq . ( [ e ] ) gives for the doppler shift : @xmath157 this equation does not coincide apparently neither with ( [ a2 ] ) , nor with ( [ a8 ] ) . nethertheless , taking into account relativistic transformations between vectors @xmath88 , @xmath158 , and @xmath89 as well as the law of addition of spatial velocities one can readily show that all three expressions for the doppler effect are identical . indeed , with the use of equation ( [ ap7 ] ) it follows that @xmath159 and @xmath160 these relationships , along with ones obtained from ( [ ap8 ] ) - ( [ ap10 ] ) after replacement of indices @xmath34 to @xmath39 and @xmath45 to @xmath38 , allow to see that expression ( [ k ] ) for the doppler effect coincides with ( [ a8 ] ) and , consequently , with ( [ a2 ] ) . this completes the derivation of the exact equations for the doppler effect in special relativity . these equations could be expanded into powers of @xmath161 to get an approximate solution . unfortunately , we would not be able to apply directly those expressions to real astronomical practices since gravitational fields of the solar system , the binary system , and the galaxy give contributions comparable with the special relativistic quadratic doppler shift . thus , in order to explore the doppler effect in general relativity , it is important to elaborate approximative analytical methods . to tackle this problem , we apply the relativistic theory of astronomical reference frames developed by kopeikin ( 1988 ) and brumberg & kopeikin ( 1989a , 1989b ) . transformation laws between reference frames in general relativity generalize the lorentz transformations of special relativity . they can be derived in two steps . first of all , the explicit form of metric tensor in different rfs are obtained by solving the einstein equations with relevant boundary conditions . then , the general relativistic transformations between the rfs are derived using the method of matched asymptotic technique . a clear and simple introduction to this technique is given in brumberg & kopeikin ( 1990 ) . here we give the transformation laws in the form which is suitable for discussion of the doppler effect with a more than sufficient accuracy . to derive the doppler shift , we apply the technique based on time transformations ( sec . thus , there is no need for development of relativistic part of space - time transformation between spatial coordinates , which will be given hereinafter only in the newtonian approximation . this transformation law is given by : @xmath162 + o(c^{-4}),\ ] ] @xmath163 where @xmath164 and @xmath165 are geocentric spatial coordinates ( rf @xmath166 and velocity of the observer , respectively ; and @xmath167 is the geopotential at the observer s location site . it is worth noting that the quantity @xmath168 is constant on the geoid surface . in eq . ( [ 1 ] ) , the tidal gravitational potential of external bodies is not included since it is negligibly small . geocentric coordinates and observer s velocity both depend on time . once the observer ( spectrograph ) is at the surface of the earth , its @xmath169 and @xmath170 are precisely calculated using the data of the international earth rotation service ( iers ) . if the observer is on board of a satellite , its motion can be derived using the satellite monitoring service . this transformation is found in the form : @xmath171 + o(c^{-4})\;,\ ] ] @xmath172 where @xmath173 and @xmath174 are respectively the spatial coordinates ( rf @xmath175 and velocity of the geocentre relative to the barycenter of the solar system ; and @xmath176 is the gravitational potential of the solar system at the geocenter . if the external ( with respect to the earth ) bodies of the solar system are approximated by massive point particles , then @xmath177 where @xmath178 is mass of the body @xmath179 ; @xmath180 is the distance from the body @xmath179 to the geocentre , and the sum is taken over all the external bodies of the solar system . the potential @xmath167 is not included in @xmath176 , in accordance with general principles of construction of relativistic theory of astronomical reference frames ( kopeikin 1988 , brumberg & kopeikin 1989a , brumberg & kopeikin 1989b ) . the tidal gravitational potentials of the bodies external with respect to the solar system are not included either , because they are too small to be important in the calculations of the doppler effect . barycentric coordinates and velocities of the earth and other bodies of the solar system can be calculated using the contemporary numerical theories of their motions ( standish 1982 , 1993 ) . this transformation law reads : @xmath181 + o(c^{-4}),\ ] ] @xmath182 where @xmath183 and @xmath184 are spatial coordinates and velocity of the barycentre of the solar system with respect to the barycentre of our galaxy ; @xmath185 is the gravitational potential of the galaxy at the barycentre of the solar system ( the potentials @xmath167 and @xmath176 should not be included ) . the galactic coordinates , velocity of the solar system , and gravitational potential of the galaxy at the solar system barycentre are all not well known quantities so far . to measure them more accurately would be one of many practical implications of precision doppler measurements of stars . this transformation is similar to eq . ( [ 5 ] ) and is given by : @xmath186 + o(c^{-4}),\ ] ] @xmath187 where @xmath188 and @xmath189 are spatial coordinates and velocity of the barycentre of the binary system relative to the barycentre of our galaxy , respectively ; @xmath190 is the gravitational potential of the galaxy at the barycentre of the binary system ( gravitational potential of the binary system should not be included ) . this transformation is similar to eq . ( [ 3 ] ) and has the form : @xmath191 + o(c^{-4}),\ ] ] @xmath192 where @xmath193 and @xmath194 are spatial coordinates and velocity of the primary star relative to the barycentre of the binary system ; and @xmath195 is the gravitational potential of the companion star . gravitational potential of the primary star should not be included in @xmath195 for the same reason why the potential @xmath176 does not include geopotential @xmath167 . the potential @xmath195 is given by : @xmath196 where @xmath13 is the companion mass , and @xmath197 is the distance between the two stars in the binary . this transformation law is given by : @xmath198 + o(c^{-4}),\ ] ] @xmath199 where @xmath200 and @xmath201 are spatial coordinates and velocity of an emitting atom relative to the star , respectively ; @xmath202 is gravitational potential of the star at the point of the atom s location . obviously , coordinates and velocity of a single emitting atom can not be determined since the integral flux of the stellar radiation is only observed . motion of the atom and gravitational potential of the star both causs the broadening of spectral lines in the stellar spectrum . this unfortunately complicates the precise measurement of the doppler shift . in order to simplify discussion of this problem as much as possible , we assume here that @xmath203 , an average thermal velocity of atoms , is constant in time , and @xmath204 , gravitational potential of the star at the altitude of the spectral line formation , is also a constant . time transformation between instants of light emission and observation is obtained from the solution of equation for light propagation in vacuum , which is described by the equation of isotropic geodesic line ( weinberg 1972 ) . solution of this equation has a simple form in the galactic reference frame @xmath35 so that the time interval between the instants of light emission , @xmath205 , and observation , @xmath34 @xmath206 , is given by@xmath207 @xmath208 where @xmath209 are the galactic coordinates of the emitting atom at the instant of emission , and @xmath210 are the galactic coordinates of the observer at the instant of light observation . relativistic correction @xmath211 is of order of @xmath212 it describes the shapiro time delay ( shapiro 1964 ) in the gravitational field : @xmath213 where subscript @xmath214 stands for a body @xmath214 that deflects light rays , @xmath215 are its spatial coordinates taken at the moment @xmath216 of the closest approach of the photon to the body ( klioner & kopeikin 1992 , kopeikin et al . 1998 ) . it can be shown ( brumberg 1972 ) that the main term in the shapiro delay depends logarithmically upon @xmath217 , the impact parameter of the light ray ( for more detail see also the paper ( kopeikin 1997 ) ) . the contribution to the doppler shift caused by the shapiro delay is proportional to @xmath218 , where @xmath219 is the characteristic relative velocity , and @xmath220 is the gravitational radius of the deflector . this estimate makes it obvious that the contribution ( [ 11aa ] ) to the doppler shift produced by the shapiro delay can be only substantial in the nearly edge - on binary systems containing invisible relativistic companion a neutron star or a black hole . functions @xmath221 and @xmath222 can be decomposed into a sum of vectors @xmath223 @xmath224 where the relativistic terms come from the relativistic part of the transformation of spatial coordinates . in subsequent calculations of the doppler shift in general relativity , we will use eq . ( [ 11 ] ) coupled with these expansions . frequency of the emitted light is related to the proper time of the emitting atom as @xmath225 where @xmath226 is the period of the emitted electromagnetic wave . frequency of the observed light is @xmath227 where @xmath228 is the period of the received electromagnetic wave . the doppler shift @xmath229 in frequency is calculated as a product of the appropriate time derivatives : @xmath230 where @xmath231 @xmath232 @xmath233 are taken at the instant of observation ; @xmath234 @xmath235 @xmath236 are taken at the instant of emission ; and @xmath237 is calculated by finding the differential of the left and right hand sides of equation ( [ 11 ] ) for propagation of light . thus , equation ( [ 13 ] ) is not just the usual time derivative taken at the same point of space - time . on the contrary , this is a two - point function that relates two events separated in space and time and connected by an isotropic worldline . time derivatives at the point of observation are obtained by direct differentiation of equations ( [ 1 ] ) , ( [ 3 ] ) , and ( [ 5 ] ) , which describe relativistic transformations between different time scales in the solar system . all these derivatives are taken at the point of observation : @xmath238 + o(c^{-4}),\ ] ] @xmath239 + \frac 1{c^2}a_{{\rm e}}^k(x^k - x_{{\rm e}}^k)+o(c^{-4}),\ ] ] @xmath240 + \frac 1{c^2}\dot v_{{\rm s}}^k(x^k - x_{{\rm s}}^k)+o(c^{-4}).\ ] ] here @xmath241 is the acceleration of the geocentre relative to the barycentre of the solar system , and @xmath242 is the acceleration of the barycentre of the solar system with respect to the barycentre of our galaxy . calculations of time derivatives at the point of emission can be done with the help of equations ( [ 7 ] ) , ( [ 9 ] ) , and ( [ 1aa ] ) : @xmath243 + o(c^{-4}),\ ] ] @xmath244 -\frac 1{c^2}a_{{\rm c}}^k(z_{*}^k - z_{{\rm c}}^k)+o(c^{-4}),\ ] ] @xmath245 -\frac 1{c^2}\dot v_{{\rm b}}^k(x_{*}^k - x_{{\rm b}}^k)+o(c^{-4}).\ ] ] here @xmath246 is the acceleration of the emitting star with respect to the binary system barycentre , and @xmath247 is the acceleration of the barycentre of the binary system with respect to the barycentre of our galaxy ( all quantities are calculated at the point of emission ) . the function @xmath248 depends on two instants of time , _ viz . _ , emission and observation of light . we have found that it is more convenient to transform @xmath248 to the instant of emission alone so that to express the final result through the instantaneous relative velocity of the barycentre of the binary with respect to the barycentre of the solar system . it enables us to exclude from the final equation for the doppler shift the poorly known velocities of the binary and the solar systems with respect to the centre of mass of our galaxy . to complete this procedure , we introduce the notations as follows : * @xmath249 is the relative distance between the solar system and binary barycentres taken at the instant of emission ; * @xmath250 is the unit vector directed toward to the barycentre of the binary ( this vector slowly changes due to proper motion @xmath251 ; * @xmath252 is the relative velocity of the binary s barycentre relative to the barycentre of the solar system , taken at the moment of emission ; * @xmath253 is the radial velocity of the binary s barycentre ; * @xmath254 \right ] ^i={{{\mbox{\boldmath$\mu$ } } } } r$ ] is the transverse velocity of the binary s barycentre . the two - point time derivative @xmath248 can be found by means of calculation of differential of equations ( [ 11 ] ) , ( [ 11a ] ) , and ( [ 11b ] ) . this results in : @xmath255 @xmath256\;,\bigskip\ ] ] @xmath257\;,\ ] ] where @xmath258 @xmath259 , and @xmath260 are galactic velocities of the observer , source of light , and deflecting body @xmath214 , respectively ; @xmath261 ; @xmath262 ; @xmath263 ; and the unit vectors @xmath264 @xmath265 , and @xmath73 are defined as : @xmath266 @xmath267 @xmath268 furthermore , equation ( [ 13f ] ) is expanded into the powers of @xmath269 and it can be simplified using the relationships : @xmath270 @xmath271 @xmath272 @xmath273 where @xmath274=-[{\bf n}\times [ { \bf r}_a\times { \bf n}]]$ ] is the vector of impact parameter @xmath217 pointing from the deflector to the light ray : @xmath275 if we only take into account the shapiro effect in the binary system , then @xmath276 and equation ( [ 13f ] ) takes the form : @xmath277 we have neglected in ( [ 13fg ] ) all terms of the order of @xmath278 and higher , as well as those ` mixed ' terms from the differentiation of @xmath211 , which are of the order of @xmath279 @xmath280 and so on , where @xmath281 is the characteristic relative velocity of the companion relative to the primary , @xmath282 is gravitational radius of companion , and @xmath217 is the impact parameter of the light ray . to continue , we expand the function @xmath283 in eq . ( [ 11a ] ) into the time series near the instant @xmath205 : @xmath284 , \ ] ] and , instead of @xmath285 , we substitute the r.h.s . of equation ( [ 11 ] ) . the result is used to expand the unit vector @xmath89 from eq . ( [ 13 g ] ) into the powers of parallactic terms of the order of @xmath286 @xmath287 and so on . one gets : @xmath288 \right ] + o(\epsilon ^{-2})+o(\epsilon ^{-1}\pi ) + o(\pi ^2).\ ] ] here the term depending on the velocity @xmath289 describes the secular aberration . the binary orbital parallax @xmath290 ( caused by the orbital motion of the star ) as well as the annual parallax @xmath291 ( caused by the orbital motion of the earth ) are given by : @xmath292 \right ] , \ ] ] @xmath293 \right ] .\ ] ] in equation ( [ 13i ] ) , we also neglect , as currently unmeasurable , all terms of the order of @xmath294 and @xmath295 . similarly to decomposition of functions @xmath221 and @xmath296 , given by eqs . ( [ 11a ] ) and ( [ 11b ] ) , decomposition of velocities @xmath297 and @xmath298 can be done . then it is straightforward to show that @xmath299 after substitution of the intermediate equations of the previous subsection into the basic equation ( [ 13 ] ) , the final result for the doppler shift takes the form : @xmath300 where partial contributions are given by : @xmath301 @xmath302 @xmath303 _ { \mbox{constant}}-\frac 1{c^2}\left [ \frac{v_{{\rm e}}^2}2+u_{{\rm e}}-({\bf k\cdot v}_{{\rm e}})^2\right ] _ { \mbox{periodic}},\ ] ] @xmath304 @xmath305 @xmath306,\ ] ] @xmath307 here @xmath308 is the vector of proper motion of the binary s barycentre ; @xmath309 is the radius - vector of the primary star relative to its companion ; @xmath310 ; and we neglect all terms of the order of @xmath311 and higher . the nature of the partial components in eq . ( 76 ) is as follows : the term @xmath312 contains a linear doppler shift caused by the radial velocity of the emitting particle . it also includes both the quadratic doppler and the gravitational shifts caused by the relative motion of the binary and the gravitational potential of our galaxy , respectively . contribution from @xmath313 causes broadening spectral lines in the primary s spectrum . the geopotential term @xmath314 is constant in time , and all temporal variations of @xmath312 are expected to be caused by a radial acceleration of the binary and/or its proper motion . the term @xmath315 describes a linear doppler shift caused by the rotational motion of the terrestrial observer with velocity @xmath316 and the orbital motion of the earth s centre of mass with velocity @xmath317 this term includes the radial component of the binary s relative velocity . the term @xmath318 includes a sum of quadratic doppler and gravitational shifts caused , respectively , by the orbital motion of the earth relative to the barycentre of the solar system _ and _ the gravitational fields of the sun and planets . the term @xmath319 describes a linear doppler shift caused by the radial velocity of source of light @xmath320 relative to the star s centre and the radial component of the orbital velocity of the star s centre of mass @xmath321 this term , like @xmath315 , includes the relative radial velocity of the binary . the term @xmath322 is a sum of quadratic doppler and gravitational shifts caused by the orbital motion of the primary star with respect to the barycentre of the binary _ and _ by the gravitational field of the companion . the term @xmath323 represents a doppler shift caused by the shapiro delay in propagation of light in the companion s gravitational field . this effect can only be detected in the nearly edge - on bynary systems . its magnitude is generally negligibly small . the term @xmath324 describes a doppler shift caused by the effect of coupling of motions of the earth and the primary star . equation ( [ 14 ] ) as such can not be used for reduction of observational data . it should be re - written in a way which would clearly pinpoint the measurable parameters . we have also to assign the proper instant of time ( `` exposure mid - time '' @xmath130 ) to any particular observation of stellar spectrum ( cochran 1996 ) . moreover , the exposure mid - time should be properly referred to the instant of light emission . the determination of the exposure mid - time is a rather difficult technical problem and we do not discuss it here ( see cochran 1996 ) . as for the relationship between the exposure mid - time and the instant of light emission , it follows from the equation of light propagation ( [ 11 ] ) and has the well - known form extensively used , e.g. , in pulsar timing data reduction programs ( taylor & weisberg 1989 , doroshenko & kopeikin 1995 ) : @xmath325 here @xmath326 is the initial epoch of observations ; @xmath327 are respectively the rmer and einstein delays in the solar system ; and @xmath328 are , accordingly , the rmer , einstein , and shapiro delays in the binary system . their explicit expressions can be found in damour & taylor ( 1992 ) , taylor & weisberg ( 1989 ) , and doroshenko & kopeikin ( 1990 , 1995 ) . let us introduce a triad of the unit vectors @xmath329 attached to the barycentre of the binary system ( see fig.1 ) . the vector @xmath330 is directed from the solar system barycentre toward that of the binary system , and vectors @xmath331 are in the plane of the sky with @xmath332 directed to the east , and @xmath333 to the north celestial pole . two other sets of the unit vectors , @xmath334 and @xmath335 are also introduced , which are related to @xmath336 by means of two spatial rotations ( damour & deruelle , 1986b ) : @xmath337 in the above transformations , the angles @xmath338 @xmath339@xmath340 and @xmath2 @xmath341 designate the longitude of the ascending node of the primary s orbit and the inclination of the orbit to the plane of the sky , respectively . vector @xmath342 is directed to the ascending node of the binary s orbit , and vectors ( @xmath343 ) lie in the orbital plane in the sense of orbital motion . vector @xmath330 slowly changes due to a proper motion of the binary @xmath344 where @xmath130 is the current time , and @xmath326 is the initial epoch of observations . therefore , the relative velocity of the binary s barycentre with respect to the solar system is given by : @xmath345 where @xmath346 is the distance between the binary and the solar systems ; @xmath347 is the relative radial velocity ( @xmath348 at the initial epoch @xmath326 ; @xmath349 is the radial acceleration ; @xmath350 and @xmath351 are the respective components of the proper motion of the star in the sky . relativistic perturbations of the orbit of a binary system are described in klioner & kopeikin ( 1994 ) . using the damour - deruelle relativistic parameterization of the orbital motion ( damour & deruelle 1985 , see also klioner & kopeikin 1994 ) , we get with the necessary accuracy : @xmath352 + o(c^{-3}),\ ] ] @xmath353 where @xmath354 is the projection of the semimajor axis @xmath355 of the primary s orbit onto the line of sight ; and @xmath356 is angular frequency of the orbital motion ( @xmath357 being the orbital period ) given by @xmath358.\ ] ] here @xmath6 and @xmath13 are masses of the primary star and its companion , respectively , @xmath359 @xmath360 is the semimajor axis of the primary s relative orbit in harmonic coordinates ( damour & deruelle 1986b ) , and @xmath361 is the eccentricity of this orbit . the angle @xmath362 in eq . ( [ 17 ] ) is the longitude of periastron , which includes a contribution of its relativistic advance : @xmath363 where @xmath364 is the position of the periastron at the initial epoch , and @xmath179 is the post - keplerian parameter of relativistic advance of the periastron ( robertson 1938 , damour & schfer 1985 , kopeikin & potapov 1994 ) : @xmath365 as an example , for a binary system with the parameters @xmath366 @xmath367 and @xmath368 the magnitude of the relativistic advance is about @xmath369 @xmath370 @xmath371 @xmath370 and @xmath372 @xmath373 for the orbits which semimajor axes are @xmath374 cm , 10@xmath375 cm , and 10@xmath376 cm , respectively . the angle @xmath377 entering eq . ( [ 17a ] ) is the eccentric anomaly , which is related to the time through the true anomaly @xmath378 and the third kepler s law : @xmath379 , \ ] ] @xmath380 where @xmath381 is the ( constant ) orbital phase at the epoch of the first passage of the periastron . additional newtonian perturbations of the binary orbit ( whenever they are observationally important ) may be included into equation ( [ 17 ] ) using the usual approach based on the orbital osculating elements ( e.g. shore 1992 , p.34 ) . coupling of orbital and proper motions of the binary gives the term @xmath382 , \ ] ] where @xmath338 is the longitude of the ascending node of the orbit , and functions @xmath383 and @xmath384 are given by @xmath385 @xmath386 the quadratic doppler effect plus gravitational shift of the frequency in the companion s gravitational field are given by @xmath387}{a_r(1-e^2)(m_s+m_c)}-\frac{gm_c[m_s+2m_c]}{a_r(m_s+m_c)}\frac e{1-e^2}\cos a_e\;.\ ] ] comparision of equations ( [ 26 ] ) and ( [ 14e ] ) yields @xmath388 @xmath389 where a new relativistic post - keplerian parameter @xmath390 is given by @xmath391}{c^2a_r(m_s+m_c)}\frac e{1-e^2}.\ ] ] for the parameters of binary systems given below eq . ( [ 17b ] ) , the magnitude of @xmath390 is about @xmath392 and @xmath393 , respectively . finally , for the gravitational lens " term @xmath323 we obtain @xmath394\right\ } } { 1-e\cos u-\sin i\left [ \sin \omega ( \cos u - e)+(1-e^2)^{1/2}\cos \omega \sin u\right ] } , \ ] ] where the third relativistic post - keplerian parameter @xmath395 is defined as @xmath396 it is worth noting that the inclination angle @xmath2 defines the shape of the function ( [ 27a ] ) . therefore , it can be considered as the forth post - keplerian parameter ( taylor 1992 ) . the effect of gravitational lensing is , under usual circumstances , rather small and it will be problematic to measure it . for instance , if the binary system consists of a main sequence star @xmath397 and a relativistic companion @xmath398 on the orbit having the relative semi - major axis @xmath399 cm and eccentricity @xmath400 , the magnitude of @xmath323 is only @xmath401 @xmath402 and @xmath403 for the orbital inclinations @xmath404 @xmath405 , and @xmath406 , respectively . the set of equations derived in the previous section makes it possible to analyse pdm observations of binary stars on a quantitative basis . in this section , we explore how to disentangle various effects entering the basic equation ( 76 ) for the doppler shift and extract measurable parameters . in order to extract a pure effect caused by the primary s motions , the earth rotation and orbital motion have to be subtracted form the total doppler shift . it can be easily done using machine readable data on the earth rotation parameters ( iers annual report ) , the earth spatial coordinates and the geocentre s velocity ( standish 1982 , 1993 ) as well as position and proper motion of the binary star taken from the astrometric catalogue . since this paper only deals with principal topics , we do not develop here an exact technical framework for calculating @xmath407 and consider them in the following as well predictable functions of time . the effect of relative motion between the solar system and the binary star , has the main contribution of the order of @xmath408 , is associated with the radial velocity of the binary s barycentre and its radial acceleration . terms of the order of @xmath409 include the transversal velocity component @xmath410 squared and the acceleration of the solar system s barycentre relative to the barycentre of the galaxy @xmath411 in addition , the constant parts of the gravitational fields of our galaxy , the solar system , the binary system , and the geopotential as well as the quadratic doppler shift caused by the orbital motion of the earth and the primary star , all contribute at the level of @xmath412 the geopotential , the quadratic doppler shift caused by the orbital motion of the earth , and the constant part of the gravitational field of the solar system on the earth s orbit all can be calculated based on the gravimetric data and modern ephemerides with an accuracy which high enough to exclude those terms from the function @xmath413 the remaining terms can be used to extract an additional information on the distribution of gravitational field in our galaxy . the classical doppler effect associated with the orbital motion of a binary system is well known . it allows to measure five keplerian parameters : ( i ) @xmath414 , the frequency of the orbital motion ; ( ii ) @xmath415 , the initial orbital phase ; ( iii ) @xmath361 , eccentricity ; ( iv ) @xmath416 , initial position of the periastron ; and ( v ) @xmath354 , the projected semimajor axis of the primary s orbit . among these five parameters , two parameters , @xmath414 and @xmath417 , while combined together , make it possible to determine the mass function of the binary , @xmath418 . in the binary with an invisible ( compact ) companion , the knowledge of mass function sets up an upper limit to the mass of the companion . in the event when the doppler shift curve of the companion is also observable , this limit can be put even tighter . measurements of relativistic effects in the orbital motion can provide a unique tool to determine the masses of stars in the binary without bias . in binary pulsars , such a procedure is widely used to determine the masses of neutron stars ( taylor 1992 ) . the proper motion of the binary leads to a gradual secular change in the observable orbital elements @xmath419 and @xmath420 this situation is quite similar to that in the pulsar timing ( kopeikin 1994 , 1996 ; arzoumanian et al . indeed , one can see from equations ( [ 20 ] ) - ( [ 22 ] ) that , because of the smallness of proper motion , the term @xmath421 can be entirely absorbed into @xmath422 by means of redefinition of parameters @xmath419 and @xmath423 . as a result , the observable values @xmath424 and @xmath425 are shifted from their physically meaningful values @xmath419 and @xmath362 by @xmath426 where @xmath427 and @xmath428 it is important to emphasize that the parameter @xmath419 changes because of secular variation of the inclination angle @xmath2 due to proper motion . meanwhile the semimajor axis @xmath355 remains constant , because proper motion does not cause any dynamical force acting on the orbital plane . hence , equation ( [ e11 ] ) can be re - written in a form similar to ( [ f1 ] ) : @xmath429 the increments @xmath430 and @xmath431 depend on time linearly and can appear in observations as small secular variations of the keplerian parameters @xmath432 and @xmath420 specifically , one gets : @xmath433,\ ] ] @xmath434,\ ] ] where the values @xmath435 and @xmath351 are expressed in seconds ( @xmath436 ) and milliarcseconds per year ( mas / yr ) , respectively . it is worth noting that , for binary systems with a negligibly small eccentricity , the effect of a secular variation in @xmath362 ( along with the relativistic advance of periastron ) is absorbed by the re - definition of the orbital frequency and therefore , in such systems , it is not observable at all . indeed , whenever the eccentricity is negligibly small , the argument @xmath437 takes the form @xmath438 where @xmath439 is the observable value of the orbital period : @xmath440 .\ ] ] here @xmath357 is the physical value of the orbital period and we neglected in ( [ h2 ] ) all terms nonlinear in small parameters . if both the classical and relativistic perturbations of orbital motion are negligibly small , then as can be seen from eqs . ( [ g1 ] ) and ( [ h11 ] ) , the observable secular variations of @xmath419 and @xmath362 parameters could be used to determine both the ascending node of the binary s orbit and the inclination angle of the orbit , @xmath441 finally , it is worth noting that the term @xmath442 entering the function @xmath324 has the structure similar to the term @xmath421 . this does not include an explicit dependence on time and , therefore , only leads to a constant shift of the orbital parameters @xmath432 and @xmath362 , which therefore can not be determined . the post - keplerian parameters @xmath445 , and @xmath444 can be measured in binary systems having relativistic orbits . of the set of these parameters , the parameter @xmath390 contributes at the highest order @xmath409 . however , it can be only disentangled with difficulty from the classical parameter @xmath446 , similarly to what happens in binary pulsars ( brumberg _ et al . the separation is possible only if the relativistic advance of the periastron , @xmath179 , is high enough to measure the change in @xmath446 . it should be noted that the term @xmath447 that enters eq . ( 88 ) is constant in the systems with negligibly small orbital perturbations . it has a secular change as the parameter @xmath362 is not constant . the parameter @xmath179 contributes only at the level of @xmath448 but in a secular way . this makes it measurement both easy and accurate , which has been done in a number of photometric and spectroscopic binaries ( see , e.g. , shakura 1985 , khaliullin 1985 ) . if parameters @xmath390 and @xmath179 are both measurable , then along with the mass function this would allow to determine separately the masses of both stars and the orbital inclination . if the classical perturbation of parameter @xmath362 ( for instance , caused by the oblateness of stars ) is also substantial , then observations of parameter @xmath390 would allow to separate the relativistic contribution to the advance of periastron from the classical one . this could be used to infer the oblatenesses of the stars . the two remaining parameters @xmath395 and @xmath444 contribute , in a quasi - periodic way , at the level of @xmath448 . if it is done independently of the other parameters , @xmath395 and @xmath444 can only be measured in the nearly edge - on binary systems via the determination of the amplitude and the shape of function @xmath323 , in a manner similar to the pulsar timing ( taylor 1992)@xmath42 the range parameter @xmath395 defines the amplitude of @xmath449 and @xmath444 characterizes its shape . once the parameters @xmath395 and @xmath444 are determined , the masses of both stars can be obtained with the use of the mass function . for the reader s convenience , we summarize here the main conclusions of this paper , along with the references to relevant equations . \1 . as discussed in introduction , precision doppler measurements ( pdms ) , which provide accuracy better than a few meters per second , measure more than just the _ radial _ component of the velocity they also catch a contribution of the _ transverse _ component , i.e. the terms of the second order in @xmath5 . a source with perioically changing velocity components , such as a binary star , allows a disentangling different velocities and extracting additional ( post - keplerian ) parameters of the binary . to this end , a detailed relativistic theory of the doppler shift is required . \2 . in special relativity , the doppler shift of a spectral frequency from a binary is given by equation ( 4 ) or by equivalent expressions ( 11 ) and ( 32 ) . the calculated doppler shift includes the contributions from : ( i ) the motion of the binary s barycentre in the galaxy ; ( ii ) the motion of the primary star in the binary ; ( iii ) the motion of the solar system barycentre in the galaxy ; and ( iv ) the earth motion relative to the solar system s barycentre . \3 . in general relativity , accounting for additional effects is necessary , which includes , among others , gravitational field in the binary and acceleration of the primary star relative to the binary s barycentre . the total doppler shift is given by equation ( 76 ) , which partial components are presented by equations ( 77)(83 ) , with detailed comments about the physical meaning of each term given at the end of sec . 5 . presence of periodically changing terms in equation ( 76 ) enables us disentangling different terms and measuring , along with the well known keplerian parameters of the binary , four additional post - keplerian parameters ( @xmath443 and @xmath444 ) as well . the first three of them are given by equations ( 92 ) , ( 101 ) , and ( 103 ) , respectively . the @xmath179 parameter characterizes the relativistic advance of the periastron ; @xmath450 characterizes the quadratic doppler and gravitational shifts associated with the orbital motion of the primary relative to the binary s barycentre and with the companion s gravitational field , respectively ; @xmath451 characterizes the amplitude of the ` gravitational lensing ' contribution to the doppler shift given by equation ( 102 ) ; and @xmath2 is the usual inclination angle of the binary s orbit ( the value of @xmath2 defines the shape of the ` gravitational lensing ' term ) . the post - keplerian parameters @xmath443 and @xmath444 can be measured in binary systems , which are sufficiently close so as to make the relativistic effects measurable ( on the other hand , as discussed below , for too close binaries with very short periods and therefore with very high orbital velocities there is a potential problem with the determination of the exposure mid - time while performing pdms ) . feasibility of practical implementation of the theory developed in this paper , crucially depends on further progress in pdm techniques . analyzing the spectrum of a star with respect to the ` velocity metric ' based on the spectrum of the iodine absorption cell allows one to remove most of the wavelength drifts of the spectrograph and the detector . it can provide an ultimate precision in measuring radial velocity of a star attaining 1 m s@xmath452 or better ( cochran 1996 ) . it is interesting to compare this precision with that in millisecond pulsars timing technique . available data indicate that the limiting accuracy of pulsar timing measurements , @xmath453 with present techniques is a few microseconds , or less , over timespan of many years ( taylor 1992 ) . uncertainty in the velocity measurement is the product of radial acceleration of the body under consideration and the error in timing measurement . the star s radial acceleration with respect to the binary s barycentre is proportional to @xmath454 where @xmath455 is the radial component of orbital velocity , @xmath214 is the semimajor axis of the star s orbit , and @xmath2 is inclination angle of the orbit . thus , for the typical binary pulsar psr b1913 + 16 , where @xmath456 @xmath457s , @xmath458 s , and the ratio @xmath5 @xmath45910@xmath460 one gets the precision of timing velocity measurements @xmath461 @xmath462 m s@xmath4 thus , the pdms of binary stars based on iodine absorption cell technique can not currently be considered competitive with timing technique for binary pulsars as concerned the precise tests of relativistic gravity . nevertheless , relative accuracy of pdms ( @xmath463 ) is comparable with the magnitude of the second or ( in some cases ) even third order for relativistic perturbations in binary systems . therefore , implementation of relativistic theory for proper tackling with such precision measurements is inevitable . the prospects for pdms combined with the relativistic theory of doppler shift presented above seem to be even more bright if one takes into consideration that a new generation of instruments for pdms is currently emerging . among them is the use of fourier transform spectroscopy with the navy prototype optical spectrometer being built by the u.s . naval observatory ( armstrong et al . 1998 ) , which is projected to achieve in a near future a velocity resolution of only 0.3 m / s ( hajian 1998 ) . an accuracy with which the orbital parameters of a binary can be determined by applying the pdms is restricted by an uncertainty related to the determination of the exposure mid - time . it is interesting to compare pdms with pulsar timing where one can actually measure the arrival time of signals and not only the dopler shift . this allows a phase - connected solution for astrometric , spin , and orbital parameters of the pulsar which contains a fit to integer numbers . that is the reason for the high accuracy in pulsar timing experiment . more simply , the precision , with which the position of a pulsar on its orbit can be determined , is given by a relationship @xmath464 . let us assume , for convenience , that pdm gives an infinite precision in determination of stellar velocity but the exposure mid - time is determined with an error @xmath465 , which is about 1 s ( cochran 1996)@xmath42 then inaccuracy in determination of the star s orbital position is given by @xmath466 @xmath467 . a comparision of the two expressions above gives : @xmath468 where @xmath469 for binary systems having orbital parameters like those in psr 1913 + 16 with @xmath470 and @xmath471 @xmath457s one has @xmath472 km . however , it is worth emphasizing that since the accuracy of timing measurements has a low limit about 1 @xmath457s one can achieve a better determination of the orbits of binary systems in which @xmath473 i.e. for the systems with very long orbital periods . in this sense , pdms are much better suited to search for planets orbiting the extrasolar stars than pulsar timing . in this paper , we have only considered the post - newtonian theory for pdms of binaries consisting of a primary ( optical ) star and an ( invisible ) compact companion . although in many binaries , especially spectroscopic ones , measuring the doppler effect for both stars would provide additional possibilities for disentangling the orbital parameters , this kind of binary seems to be less appropriate for pdm measurements . indeed , in close binaries , where relativistic effects could be measurable with pdms , those effects would be severely contaminated by tidal interaction of the components and stellar winds , whereas in wide binaries the post - newtonian terms are expected to be rather weak . it is worthwhile to remind that normal stars subjected to the pdms , in most cases , can not be considered as point masses , unlike neutron stars or black holes . due to this reason , the classical perturbations will presumably be the most important sources of orbital parameters variations ( shore 1994 ) . however , even in the situation when the classical perturbations dominate , measuring of ( or proper taking into account ) the relativistic effects will serve as a tool to better understand the nature of the process(es ) responsible for the orbital parameters variations . in this respect , interesting observational targets for pdms might be massive main - sequence stars with radio pulsars in binary systems like psr b1259 - 63 ( wex et al . 1988 ) or psr j0045 - 7319 . timing observations reveal ( lai , bildstein & kaspi 1995 ) that it is possible to measure orbital evolution caused by hydrodynamical effects associated with the optical companion but induced by the tidal gravitational field of the companion ( the pulsar ) and/or intrinsic rotational motion of the primary star . pdms of such a system , to be done complementary to timing observations , would allow to measure tidal oscillations of the optical star and therefore to essentially improve our knowledge about these systems . another interesting application of pdms could be an anomalous binary systems like di her , where some discrepancy was found between the prediction based on general relativity and the observed motion of the periastron ( guinan & maloney 1985 ) . it also can be explained by the dynamical influence of tidally - generated oscillations on the orbital motion of stars but accuracy of the employed observational technique was not good enough to test this hypothesis . . l.o . acknowledges a partial support of this work by center for earth observing and space research , george mason university . kopeikin is thankful to m .- k . fujimoto and other members of national astronomical observatory of japan ( mitaka , tokyo ) , where this work was initiated , for long - term constant support , and is pleasured to acknowledge the hospitality of g. neugebauer and g. schfer and other members of the institute for theoretical physics of the friedrich schiller university of jena . we are grateful to n. wex who carefully read the manuscript and made a number of valuable comments which helped to improve the presentation of the paper . this work has been partially supported by the thringer ministerium fr wissenschaft , forschung und kultur grant no b501 - 96060 and max - planck - gesselschaft grant no 02160/361 . 99 armstrong , j. t. , mozurkewich , d. , rickard , l. j , hutter , d. j. , benson , j. a. , bowers , p. f. , elias , n. m. ii , hummel , c. a. , johnston , k. j. , buscher , d. f. , clark , j. h. iii , ha , l. , ling , l .- c . , white , n. m. , & simon , r. s. , 1998 , apj , * 496 * , 550 arzoumanian , z. , joshi , k. , rasio , f. a. , thorsett , s. e. , 1996 , `` pulsars : problems and progress '' , astronomical society of the pacific conference series , vol . 105 ; proceedings of the 160th colloquium of the international astronomical union held in sydney ; australia ; 8 - 12 january 1996 ; san francisco : astronomical society of the pacific ( asp ) ; 1996 ; edited by s. johnston , m.a . walker , and m. bailes . , p.525 brumberg , v. a. , & kopeikin , s. m. , 1989a , `` relativistic theory of celestial reference frames '' , in : reference frames in astronomy and geophysics , eds . j. kovalevsky , i. i. mueller , & b. kolaczek , kluwer : dordrecht , p. 115 cochran , w. , 1996 , `` precise measurement of stellar radial velocities '' , in : proc . workshop on high resolution data processing , eds . , m. iye , t. takata , and j. wampler , 1996 , subaru telescope techical report , naoj , no 55 , p. 30

the determination of velocities of stars from precise doppler measurements is described here using relativistic theory of astronomical reference frames so as to determine the keplerian and post - keplerian parameters of binary systems . seven reference frames are introduced : ( i ) proper frame of a particle emitting light , ( ii ) the star - centered reference frame , ( iii ) barycentric frame of the binary , ( iv ) barycentric frame of the galaxy , ( v ) barycentric frame of the solar system , ( vi ) geocentric frame , and ( vii ) topocentric frame of observer at the earth . we apply successive lorentz transformations and the relativistic equation of light propagation to establish the exact treatment of doppler effect in binary systems both in special and general relativity theories . as a result , the doppler shift is a sum of ( 1 ) linear in @xmath0 terms , which include the ordinary doppler effect and its variation due to the secular radial acceleration of the binary with respect to observer ; ( 2 ) terms proportional to @xmath1 , which include the contributions from the quadratic doppler effect caused by the relative motion of binary star with respect to the solar system , motion of the particle emitting light and diurnal rotational motion of observer , orbital motion of the star around the binary s barycenter , and orbital motion of the earth ; and ( 3 ) terms proportional to @xmath1 , which include the contributions from redshifts due to gravitational fields of the star , star s companion , galaxy , solar system , and the earth . after parameterization of the binary s orbit we find that the presence of periodically changing terms in the doppler schift enables us disentangling different terms and measuring , along with the well known keplerian parameters of the binary , four additional post - keplerian parameters , which characterize : ( i ) the relativistic advance of the periastron ; ( ii ) a combination of the quadratic doppler and gravitational shifts associated with the orbital motion of the primary relative to the binary s barycentre and with the companion s gravitational field , respectively ; ( iii ) the amplitude of the ` gravitational lensing ' contribution to the doppler shift ; and ( iv ) the usual inclination angle of the binary s orbit , @xmath2 . we briefly discuss feasibility of practical implementation of these theoretical results , which crucially depends on further progress in the technique of precision doppler measurements .

the recent major improvement in the observation of the deep universe , both with hst and ground - based telescopes of the new generation , has greatly increased our chance to probe the cosmological model by venturing to search for primeval galaxies . when observing in the optical or infrared range , however , we are probing restframe ultraviolet ( uv ) emission of high - redshift objects , and we should therefore rely on confident recognition criteria in this wavelength range in order to pick up distant galaxies and track their evolution back in time . because of atmosphere opacity , nearby galaxies are still poorly explored in the extreme uv range , and their data can not fully match high-@xmath3 observations ( lanzetta _ et al . _ 1996 ; massarotti _ et al . _ 2001a ) . in any case , such an empirical approach would neglect evolution , while sample selection and malmquist bias could give rise to a misleading interpretation of the high - redshift data ( buzzoni 1998 , 2001 ; adelberger and steidel 2000 ) . for all these reasons , galaxy models may prove to be a more effective tool to match primeval galaxy evolution , although within the limits of the established theoretical scenario . the observation of uv emission of star - forming galaxies at cosmological distances , in the hubble deep field ( williams _ et al . _ 1996 ) or in other deep surveys ( lilly _ et al . _ 1996 ; connolly _ et al . _ 1997 ) , has recently led to important advances in the study of the cosmic star formation ( madau _ et al . _ 1998 ; steidel _ et al . _ 1999 ; massarotti _ et al . _ 2001b ) fueling the current debate on the epoch of galaxy formation . in the light of these results , in this work my aim is to assess in more detail the expected uv properties of primeval galaxies . in particular , i focus on the theory of uv energetics in stellar populations , in order to explore its dependence on the star formation rate ( sfr ) and other main evolutionary parameters . this will rely on a previous theoretical framework for evolutionary population synthesis ( buzzoni 1989 , 1995 , 1998 ) . to some extent , my analysis is complementary to the work of leitherer _ et al . _ ( 1999 ) , as i track here late evolution of star - forming galaxies , when morphology begins to differentiate late- and early - type systems along the hubble sequence . my discussion will first consider , in sec . 2 , the uv evolution of a simple stellar population ( ssp ) . this will provide the basic theoretical tools to derive an absolute calibration of galaxy uv luminosity and actual sfr , and to study its possible dependence on metallicity . a possible scheme for the spectral evolution of star - forming galaxies of different morphological type is outlined in sec . 3 , where i compute a new set of synthesis models and compare , in sec . 4 , the theoretical output with iue observations and other uv data available for local galaxies . the problem of dust absorption is also reviewed in the latter section discussing its possible impact on the evolutionary scenario of high - redshift galaxies . our relevant conclusions are finally summarized in sec . contrary to the case of optical and infrared evolution , the ultraviolet luminosity of star - forming galaxies is largely dominated by short - lived stars of high mass ( kennicutt 1998 ) . this makes population synthesis models much simpler , because hot main sequence ( ms ) stars are the prevailing contributors to the galaxy energetic budget at short wavelengths . in a more refined analysis , however , the input from low - mass stars ( m @xmath4 m@xmath2 ) should also be conveniently sized up , since these stars smoothly cumulate over the entire galaxy life and could reach hot temperatures at some stage of the post - ms evolution . the ssp theory ( renzini and buzzoni 1986 ; buzzoni 1989 ) provides an effective tool to consistently assess the general uv properties of stellar populations . as we will see , the relevant results for the ssp case can also easily apply to the study of star - forming galaxies . an illustrative summary of the integrated luminosity emitted shortward of 3000 by ms stars of different spectral type is reported in fig . [ stars ] . the plot is based on the kurucz ( 1992 ) model atmospheres , adopting a standard temperature - luminosity - mass calibration for class v stars of solar metallicity as from allen ( 1973 ) . one sees from the figure that at least half the bolometric luminosity of stars more massive than @xmath5 m@xmath2 is spent in the ultraviolet . for stars earlier than @xmath6 ( m @xmath7 m@xmath2 ) , a simple @xmath8-@xmath9 calibration can be derived such as @xmath10 , with @xmath11 for @xmath0 ( expressing both @xmath8 and @xmath9 in solar units ) . at lower mass , the slope of the relation quickly steepens , and the uv contribution drops to nominal values for @xmath12 stars . as far as a ssp is considered , with stars distributed in mass according to a power - law imf such as @xmath13 ( @xmath14 for the salpeter standard case ) , the integrated ms luminosity results : @xmath15 where @xmath16 is a normalization factor that scales with the ssp total mass , while m@xmath17 is the lower limit for the imf . the integral is constrained by the mass of the turn - off ( to ) stars ( m@xmath18 ) , that leave the ms . this actually marks the `` clock '' of the ssp , giving the time dependence of @xmath19 . recalling that @xmath20 , and provided that @xmath21 and @xmath22 , after some appropriate substitutions we have : @xmath23 equation ( [ eq : lms ] ) simply relates total ms luminosity to the to luminosity of the evolving stars in the ssp . detailed ssp evolution for @xmath0 is computed in fig . [ uvfrac ] , where i extend to younger ages the original model sequence of buzzoni ( 1989 ) for a salpeter imf and solar metallicity . in this figure , i also single out the contribution from post - agb stars experiencing the planetary nebula event for @xmath24 gyr . as is well known , post - agb stars are important contributors to short - wavelength luminosity in old ssps , and may actually constrain the ultraviolet properties of present - day elliptical galaxies ( renzini and buzzoni 1986 ; burstein _ et al . _ 1988 ; greggio and renzini 1990 ; yi _ et al . _ 1999 ) . the ssp model of fig . [ uvfrac ] assumes a red horizontal branch ( hb ) morphology ; my choice relies on the fact that hb evolution quickly turns to redder colors with increasing star mass and/or metallicity . although stars with temperatures in excess of 10000 k are recognized in some old metal - poor galactic globular clusters ( cacciari _ et al . _ 1995 ) , a red hb is always to be expected at younger ages ( i.e. for @xmath25 gyr ; cf . fig . 4 of buzzoni 1989 ) . the resulting ssp luminosity evolution at three reference wavelength values , namely , 1600 , 2000 , and 2800 , is reported in table [ ssp ] for a salpeter imf with an upper cutoff mass of 120 m@xmath2 . insofar as ms contribution is the prevailing one in the uv energetic budget , the ssp luminosity evolution can be approximated by a simple analitical relation linking eq . ( [ eq : lms ] ) with the theoretical stellar clock . the ms lifetime for stars in the different range of mass and solar metallicity can be evaluated from a number of sets of theoretical models . i considered the work of becker ( 1981 ) , vandenberg ( 1985 ) , castellani _ et al . _ ( 1990 ) , lattanzio ( 1991 ) , schaller _ et al . _ ( 1992 ) , and bressan _ et al . _ ( 1993 ) . a useful fit to these data , which spans the whole range of mass , is @xmath26 ( cf . [ clock ] ) . by differentiating eq . ( [ eq : lms ] ) and eq . ( [ eq : fit_clock ] ) we obtain @xmath27 and @xmath28 , respectively . assuming that @xmath29 , this leads to @xmath30 the power index @xmath31 depends on @xmath32 and @xmath33 , so that it slightly changes with time and wavelength ( ssp luminosity fades more rapidly at shorter wavelength ) but , as a general case , we could verify from table [ ssp ] that @xmath34 for @xmath0 . this feature has important consequences when linking uv luminosity and galaxy sfr . in the case of a star - forming galaxy with constant sfr , for example , actual luminosity simply follows as @xmath35\ l_{tmin}^{ssp } \label{eq : lgal}\ ] ] where @xmath36 is the age of the system , and @xmath37 is the lifetime of the most massive stars in the imf . the previous equation confirms that galaxy uv luminosity eventually does not depend on age , but only on its actual sfr ( kennicutt 1998 , cf . his fig . 2 ) . as a consequence , a _ minimum _ uv luminosity is reached by a star - forming galaxy that is the luminosity of a ssp of total mass @xmath38 , where @xmath37 comes from eq . ( [ eq : fit_clock ] ) once entering the upper stellar mass of the imf ( @xmath39 ) . a straightforward relation exists between @xmath40 and the ssp scale factor @xmath16 in eq . ( [ eq : lms ] ) ( cf . e.g. eq . [ 3 ] in buzzoni 1989 ) ; making the relevant substitutions , we can write @xmath41 with @xmath42 in the previous equation , @xmath43 if @xmath44 and @xmath45 if @xmath46 , while @xmath47 is the to luminosity of stars of mass @xmath39 . lrrr 0.003 & 0.00 & 0.00 & 0.00 + 0.013 & 2.13 & 1.94 & 1.76 + 0.024 & 2.49 & 2.27 & 2.06 + 0.046 & 2.85 & 2.60 & 2.35 + 0.057 & 2.96 & 2.70 & 2.44 + 0.078 & 3.13 & 2.85 & 2.58 + 0.10 & 3.27 & 2.96 & 2.68 + 0.20 & 3.66 & 3.29 & 2.97 + 0.40 & 4.26 & 3.69 & 3.30 + 0.60 & 4.94 & 4.00 & 3.52 + 0.80 & 5.47 & 4.34 & 3.73 + 1.0 & 5.87 & 4.64 & 3.89 + 2.0 & 7.04 & 5.51 & 4.37 + 4.0 & 7.90 & 6.23 & 4.68 + 5.0 & 8.02 & 6.39 & 4.78 + 6.0 & 8.03 & 6.56 & 4.88 + 8.0 & 8.03 & 6.85 & 5.05 + 10.0 & 8.00 & 7.11 & 5.19 + 12.5 & 7.88 & 7.27 & 5.32 + 15.0 & 7.77 & 7.37 & 5.43 + [ ssp ] ccccc & + & + 1600 & 25.77 & 25.62 & 25.51 & 25.36 + 2000 & 25.71 & 25.56 & 25.45 & 25.30 + 2800 & 25.54 & 25.39 & 25.28 & 25.13 + & + & + 1600 & 27.92 & 27.60 & 27.37 & 27.04 + 2000 & 27.86 & 27.54 & 27.31 & 26.98 + 2800 & 27.68 & 27.36 & 27.13 & 26.80 + & + & + 1600 & 29.39 & 28.89 & 28.53 & 28.03 + 2000 & 29.33 & 28.83 & 28.47 & 27.97 + 2800 & 29.16 & 28.66 & 28.30 & 27.80 + [ zero ] the expected l@xmath48 vs. sfr calibration at 2800 is shown in fig . [ calib ] ; a fairly good agreement is found with the madau _ et al . _ ( 1998 ) results as l@xmath48 tracks the sfr via the relative number of high - mass stars , any non - standard imf could easily be accounted for . for example , a scalo ( 1986 ) mass distribution would closely resemble in fig . [ calib ] the case of a power - law imf with @xmath49 . table [ zero ] reports the values of @xmath50 at 1600 , 2000 , and 2800 for different imf slopes around the salpeter value . as metal enrichment is a direct by - product of star formation , one would expect primordial galaxies to be essentially metal - poor aggregates . for this reason , it is also relevant to assess the validity of our l@xmath48 vs. sfr calibration in case of a non - solar evolutionary scenario with @xmath51 . a change in metallicity would basically affect the ms fuel consumption , modulating the @xmath52 scaling factor in eq . ( [ eq : lmin ] ) via the term @xmath53 . this point is explored in fig . [ fuel ] , in which i compute the equivalent quantity fuel = l@xmath54 t@xmath55 from the padova ( bressan _ et al . _ 1993 ; fagotto _ et al . _ 1994 ) and geneva ( schaller _ et al . _ 1992 ) stellar tracks , and study its absolute and relative variation with changing @xmath56 . in the top panel of the figure , the fraction of initial stellar mass burnt during ms evolution is reported for the model sequences at solar metallicity and the corresponding metal - poor ones ( namely , @xmath57 for the geneva tracks and @xmath58 for the padova tracks ) . compared with the @xmath59 case , metal - poor stars increase their ms lifetime but decrease bolometric ( and uv ) luminosity ( cf . bottom panel ) . the two effects tend to nearly compensate , so that the factor @xmath53 remains almost constant over a wide range of stellar mass . this secures our l@xmath48 vs. sfr calibration within just a @xmath60 % uncertainty even for quite extreme deviations from the solar metallicity . relying on eq . ( [ eq : lmin ] ) , a convenient way to parameterize the luminosity evolution of a star - forming galaxy is @xmath61 in addition to the contribution of fresh star formation , the correcting factor @xmath62 in the equation takes into account the `` extra '' luminosity contributed by the bulk of unevolved low - mass stars that have been accumulating along the galaxy s life . it is interesting to theoretically evaluate this term in order to assess its real impact on galaxy spectral energy distribution ( sed ) for different star formation histories . in its general case , the total luminosity of a star - forming galaxy can be computed as a suitable convolution of ssp `` building blocks '' with the sfr at the different epochs : @xmath63 once @xmath64 is obtained from eq . ( [ eq : lgal ] ) , and @xmath65 from eq . ( [ eq : lmin ] ) , the @xmath66 residual luminosity simply derives from eq . ( [ eq : q ] ) . for the present experiment , it is useful to consider the case of a power - law time decay such as sfr @xmath67 . the major advantage of this simple parameterization is that it can easily account for a wide range of star formation histories in terms of an age - independent , sfr @xmath68 and its time average is @xmath69 . providing that @xmath70 , we always have @xmath71 , from which the value of @xmath72 directly follows , by definition . ] distinctive birthrate @xmath73 the value of @xmath74 can be tuned up in order to reproduce galaxy colors at present time . for a salpeter imf with stars between 0.1 and 120 m@xmath2 , its allowed range is between @xmath75 ( cf . sec . 3 ) . with these assumptions , the resulting @xmath66 correction is summarized in fig . [ q ] . after a sharp increase on a few @xmath37 timescale , @xmath76 tends to flatten and proceed steadily over the whole galaxy life . as expected , the luminosity correction becomes more important at longer wavelengths , and for a dwarf - dominated imf ( i.e. @xmath77 ) . however , for a salpeter imf , and even at 2800 , its value is less than @xmath78 dex , confirming that uv luminosity of star - forming galaxies is only marginally modulated by the past star formation history . when moving to shorter wavelengths , eq . ( [ eq : lmin ] ) always tends to a fair estimate of galaxy total luminosity , and sed will closely resemble that of the hottest composing stars ( as @xmath79 in the equation ) . as i showed in previous section , past star formation history is better traced by the galaxy sed at longer wavelengths . combining ultraviolet and optical observations , such as , for example , in the @xmath80 and @xmath81 bands , could therefore set valuable constraints on the stellar birthrate for galaxies along the whole hubble morphological sequence ( larson and tinsley 1978 ) . to further investigate this important issue , this section introduces a simple family of galaxy models consisting of a spheroid and disk stellar component . apart from minor details , this is basically the set of templates adopted by massarotti _ et al . _ ( 2001a , b , c ) for their study of the photometric redshift distribution in the hubble deep field . the reader could also be referred to these works of massarotti _ et al . _ for a full comparison of the present theoretical framework with the codes of bruzual and charlot ( 1993 ) and fioc and rocca - volmerange ( 1997 ) , extensively used in recent extragalactic studies ( see also buzzoni 1998 for an in - depth discussion in the context of high - redshift observations ) . here i particularly address the relevant uv features of the present theoretical output in the specific context of this discussion ; the complete data set is also available in electronic form at the author s web site.eps/home.html ] a major advantage of our theoretical approach over the previous synthesis codes ( with perhaps the only relevant exception of the arimoto and jablonka 1991 models ) resides in the fact that galaxy photometric evolution here comes as a result of the _ individual _ evolution of the disk and bulge sub - systems . as a general trend , disk luminosity is expected to slowly increase with time ( because low - mass stars are `` secularly '' cumulating in a galaxy ) , as opposed to those in the bulge , which will fade due to an increasing fraction of dead stars ( renzini and buzzoni 1986 ) . galaxy evolution back in time therefore results from the actual balance of these two different photometric trends ; as a consequence , one single sfr characteristic timescale , as usually assumed in other synthesis codes , may not be an adequate description of the system as a whole . luminosity partition between the two basic building blocks of our synthesis models ( i.e. , disk and spheroid components ) has been set empirically , relying on the kent ( 1985 ) galaxy decomposition profiles . these observations have been carried out in the gunn @xmath82 band and also provide a confident estimate of the bolometric partition ( buzzoni 1989 ) . from these data , for each hubble type i calibrated a bolometric morphological parameter defined as @xmath83 . according to the observations , the luminous mass of the disk remains roughly constant along the s0 @xmath84 i m sequence , while the bulge luminosity decreases in later type spirals ( arimoto and jablonka 1991 ; gavazzi 1993 ) . for the spheroid subsystem , a ssp evolution with solar metallicity has been adopted , according to buzzoni ( 1989 , 1995 ) . disk sfr is in the form of a power law , as discussed in the previous section , with stars between 0.1 and 120 m@xmath2 according to a salpeter imf . luminosity of the disk sub - system can be computed via eq . ( [ eq : lgal ] ) , in which i tune up the sfr index @xmath74 so as to reproduce the @xmath85 color of present - day galaxies along the whole hubble sequence . the extensive data samples of roberts and haynes ( 1994 ) and buta _ et al . _ ( 1994 ) have been used as a reference in this regard ( cf . [ bvst ] ) . a slightly subsolar mean metallicity ( i.e. @xmath86[fe / h]@xmath87 @xmath88 dex ) is assumed for the disk stellar population . this is meant to be a representative average of the whole stellar population at the different epochs . our choice agrees with arimoto and jablonka ( 1991 ) , who suggest a luminosity - weighted value of @xmath86[fe / h]@xmath89 dex for their later - type galaxy models at 15 gyr . the empirical age - metallicity calibration for the milky way by edvardsson _ et al . _ ( 1993 ) also provides a value of @xmath86[fe / h]@xmath90 dex when averaging on current stellar age . the conclusions of sec . 2.2 assure us , however , that metallicity is not a critical parameter for model predictions as far as uv evolution is concerned . table [ caliball ] gives a global summary of the adopted distinctive parameters for the different hubble types at 15 gyr ( cf . also table 1 in massarotti _ et al . _ 2001a for a synopsis with the output of other synthesis codes ) . figure [ birthrate ] displays the calibration of @xmath72 vs. de vaucouleurs `` t '' morphological type , and the current disk sfr expected for template galaxies of total mass m@xmath91 m@xmath2 . these results consistently compare with the empirical estimate of kennicutt _ et al . _ ( 1994 ) . lcrccccc @xmath92s0 & 0.0 & @xmath93 & 0.80 & 0.17 & 7.09 & @xmath94 & 0.90 + @xmath92sa & 0.2 & @xmath95 & 0.55 & 0.28 & 5.60 & @xmath96 & 0.75 + @xmath92sb & 0.5 & @xmath97 & 0.35 & 0.38 & 4.15 & @xmath98 & 0.63 + @xmath92sc & 0.9 & @xmath99 & 0.18 & 0.52 & 2.73 & @xmath100 & 0.53 + @xmath92sd & 1.3 & @xmath101 & 0.05 & 0.78 & 1.66 & @xmath102 & 0.47 + @xmath92irr & 1.8 & @xmath103 & 0.00 & 1.00 & 1.11 & @xmath104 & 0.43 + [ caliball ] theoretical evolution of galaxy color and luminosity , pertinent to the different hubble morphological types , is summarized in the series of tables [ e_tab ] to [ im_tab ] . all the color entries in the tables are given in ab magnitude scale , in the frequency domain , according e.g. to oke and schild ( 1970 ) ] including the johnson @xmath105 , while @xmath106 is given in erg s@xmath107hz@xmath107 and @xmath108 in erg s@xmath107 . total luminosity of late - type galaxy models is normalized so as to provide a disk sfr @xmath109 m@xmath2 yr@xmath107 at 15 gyr ; the template elliptical ( taken from buzzoni 1995 ) is scaled to a total mass of @xmath110 m@xmath2 . the corresponding value of m@xmath111 for the other galaxy templates is reported in each table . this value only refers to the amount of mass converted in stars ( that is m@xmath112 ) and therefore does _ not _ include residual gas . by definition , its value increases with time . absolute bolometric magnitude can be derived from the data as @xmath113 . cccccccc 1.0 & 6.68 & 3.76 & 2.34 & 1.05 & & 30.01 & 45.29 + 2.0 & 8.90 & 5.22 & 2.82 & 1.16 & & 29.72 & 45.06 + 4.0 & 10.34 & 6.31 & 2.89 & 1.27 & & 29.44 & 44.83 + 5.0 & 10.41 & 6.48 & 2.91 & 1.30 & & 29.35 & 44.76 + 6.0 & 10.25 & 6.72 & 2.97 & 1.33 & & 29.27 & 44.70 + 8.0 & 9.95 & 7.15 & 3.08 & 1.38 & & 29.15 & 44.61 + 10.0 & 9.65 & 7.57 & 3.22 & 1.41 & & 29.06 & 44.53 + 12.5 & 9.12 & 7.74 & 3.32 & 1.45 & & 28.97 & 44.46 + 15.0 & 8.66 & 7.81 & 3.41 & 1.47 & & 28.90 & 44.40 + [ e_tab ] cccccccc 1.0 & 2.12 & 2.02 & 1.87 & 0.89 & & 29.78 & 44.97 + 2.0 & 2.13 & 2.13 & 2.05 & 0.94 & & 29.53 & 44.77 + 4.0 & 2.13 & 2.16 & 2.10 & 0.98 & & 29.29 & 44.57 + 5.0 & 2.13 & 2.16 & 2.11 & 1.00 & & 29.22 & 44.51 + 6.0 & 2.13 & 2.17 & 2.14 & 1.01 & & 29.15 & 44.45 + 8.0 & 2.14 & 2.17 & 2.17 & 1.03 & & 29.05 & 44.37 + 10.0 & 2.14 & 2.18 & 2.21 & 1.04 & & 28.98 & 44.31 + 12.5 & 2.14 & 2.18 & 2.23 & 1.05 & & 28.90 & 44.24 + 15.0 & 2.15 & 2.19 & 2.25 & 1.06 & & 28.84 & 44.19 + [ sa_tab ] cccccccc 1.0 & 1.73 & 1.68 & 1.67 & 0.84 & & 29.27 & 44.44 + 2.0 & 1.63 & 1.65 & 1.73 & 0.85 & & 29.07 & 44.27 + 4.0 & 1.56 & 1.60 & 1.71 & 0.86 & & 28.89 & 44.11 + 5.0 & 1.54 & 1.59 & 1.71 & 0.87 & & 28.84 & 44.07 + 6.0 & 1.53 & 1.58 & 1.71 & 0.87 & & 28.79 & 44.03 + 8.0 & 1.53 & 1.57 & 1.72 & 0.87 & & 28.73 & 43.97 + 10.0 & 1.52 & 1.57 & 1.74 & 0.87 & & 28.68 & 43.93 + 12.5 & 1.52 & 1.57 & 1.74 & 0.88 & & 28.63 & 43.88 + 15.0 & 1.52 & 1.57 & 1.75 & 0.88 & & 28.59 & 43.85 + [ sb_tab ] cccccccc 1.0 & 1.61 & 1.58 & 1.60 & 0.83 & & 28.74 & 43.92 + 2.0 & 1.36 & 1.39 & 1.54 & 0.80 & & 28.61 & 43.79 + 4.0 & 1.22 & 1.26 & 1.45 & 0.77 & & 28.52 & 43.70 + 5.0 & 1.20 & 1.24 & 1.44 & 0.77 & & 28.51 & 43.68 + 6.0 & 1.19 & 1.23 & 1.44 & 0.76 & & 28.49 & 43.66 + 8.0 & 1.18 & 1.22 & 1.44 & 0.76 & & 28.48 & 43.65 + 10.0 & 1.18 & 1.23 & 1.45 & 0.76 & & 28.47 & 43.64 + 12.5 & 1.19 & 1.23 & 1.46 & 0.76 & & 28.46 & 43.64 + 15.0 & 1.20 & 1.24 & 1.47 & 0.76 & & 28.46 & 43.64 + [ sc_tab ] cccccccc 1.0 & 1.28 & 1.28 & 1.41 & 0.76 & & 28.14 & 43.28 + 2.0 & 1.00 & 1.05 & 1.27 & 0.70 & & 28.12 & 43.23 + 4.0 & 0.93 & 0.97 & 1.22 & 0.67 & & 28.18 & 43.28 + 5.0 & 0.93 & 0.98 & 1.22 & 0.67 & & 28.21 & 43.31 + 6.0 & 0.94 & 0.98 & 1.23 & 0.67 & & 28.24 & 43.34 + 8.0 & 0.96 & 1.00 & 1.25 & 0.68 & & 28.28 & 43.39 + 10.0 & 0.98 & 1.02 & 1.27 & 0.68 & & 28.32 & 43.43 + 12.5 & 1.01 & 1.05 & 1.30 & 0.69 & & 28.36 & 43.48 + 15.0 & 1.03 & 1.07 & 1.32 & 0.70 & & 28.39 & 43.52 + [ sd_tab ] cccccccc 1.0 & 0.42 & 0.48 & 0.80 & 0.50 & & 27.21 & 42.16 + 2.0 & 0.56 & 0.62 & 0.91 & 0.54 & & 27.50 & 42.49 + 4.0 & 0.70 & 0.75 & 1.03 & 0.58 & & 27.80 & 42.82 + 5.0 & 0.74 & 0.79 & 1.06 & 0.60 & & 27.89 & 42.93 + 6.0 & 0.77 & 0.82 & 1.09 & 0.61 & & 27.97 & 43.01 + 8.0 & 0.82 & 0.87 & 1.14 & 0.62 & & 28.09 & 43.15 + 10.0 & 0.86 & 0.91 & 1.17 & 0.64 & & 28.18 & 43.25 + 12.5 & 0.90 & 0.95 & 1.21 & 0.65 & & 28.28 & 43.36 + 15.0 & 0.93 & 0.98 & 1.23 & 0.66 & & 28.35 & 43.44 + [ im_tab ] a preliminary `` sanity check '' of our theoretical output is performed in fig . [ buta ] , which compare with the buta _ et al . _ ( 1994 ) empirical @xmath114 locus for over 2500 local galaxies in the rc3 catalog ( de vaucouleurs _ et al . _ it should be pointed out , in this regard , that this check is not completely independent , since i already used the buta _ et al . _ @xmath85 distribution to constrain the sfr ; this would actually `` recover '' any further internal mechanism modulating the galaxy sed . in any case , it is comforting to see from fig . [ buta ] that the previous @xmath85 vs. s / t calibration correctly accounts , within the internal scatter of the observations , also for the @xmath114 color trend vs. `` t '' morphological parameter . the models given in tables [ e_tab][im_tab ] better focus on `` late '' galaxy evolution , after the first gyr of life , when low - mass stars with m @xmath115 m@xmath2 dominate galaxy bolometric luminosity , and bulge and disk subsystems begin to differentiate morphology along the hubble sequence ( larson 1975 , 1976 ; firmani and tutukov 1992 ) . evolution is less univocally constrained at earlier epochs , where convection and mass loss via stellar winds ( both depending on metallicity ) play an important role in high - mass stars and affect , among other things , the luminosity partition between blue and red giant stars or the relative contribution of wolf - rayet stars ( see mass - hesse and kunth 1991 , cervio and mass - hesse 1994 , and especially cervio _ et al . _ 2002 for a quantitative assessment of these problems on the framework of stellar population synthesis ) . a complementary in - depth analysis of the first @xmath116 yrs in star - forming galaxies has been carried out by leitherer and heckman ( 1995 ) and leitherer _ et al . _ ( 1999 ) . their models take into account in some detail spectrophotometric evolution of high - mass stars in different theoretical environments including continuous star formation and ssp evolution . a match of our synthesis models and the leitherer _ _ output for @xmath59 and a salpeter imf is shown in fig . we see that ssp evolution consistently describes early - type systems at primeval epochs , while continuous sfr accounts for late - type and irregular galaxies . it is interesting to note , in addition , that colors of both ellipticals and late - type galaxies `` degenerate '' in the first few myr , that is , on a timescale comparable to @xmath37 , as expected from eq . ( [ eq : lmin ] ) . restframe evolution of the @xmath117 ab color for the different galaxy morphological types is displayed in fig . only ellipticals show a drastic color change becoming sensibly bluer at earlier epochs ; late - type systems remain on the contrary more or less the same , since they are dominated throughout by fresh star formation . the theoretical m / l ratio at 2000 for model ellipticals and irregulars is explored in fig . i have considered the actual total mass of the galaxies , m@xmath111 , in solar unit according to the previous definition , while the 2000 luminosity derives from table 4 and 9 as @xmath118 . the value has been converted to solar units assuming @xmath119 erg s@xmath107 hz@xmath107 for the sun at 2000 as from a kurucz ( 1992 ) @xmath120 model atmosphere . as a striking feature , note that at 2000 enhanced star formation makes i m galaxies nearly four orders of magnitude brighter than ellipticals , at comparable total mass . the role of late - type systems as powerful ( and possibly dominant ) contributors to the cosmic uv background has recently been emphasized by steidel _ et al . _ ( 2001 ) and bianchi _ et al . _ ( 2001 ) through their study of lyman - break galaxies . because of the intrinsic physical limits of atmosphere absorption , a study of local galaxies below 3500 perforce relies on a quite scanty set of data , mainly from iue observations and balloon - borne missions . the work of donas _ et al . _ ( 1987 ) , collecting 2000 photometry for 149 mainly late - type galaxies from the scap 2000 balloon - borne mission , provides an important reference in this regard . despite the large uncertainties in the original flux calibration , and the somewhat heterogeneous match between @xmath121 and ( external ) @xmath80 photometry , a comparison with our model predictions can be attempted in fig . [ donas1 ] . the original data have been corrected for milky way extinction , relying on the burstein and heiles ( 1984 ) reddening map to estimate the color excess for each galaxy in the sample . according to seaton ( 1979 ) , the reddening vector is @xmath122 , as displayed in the figure . three main features are worth of attention in the plot . _ i ) _ the data distribution spans a wider range in @xmath85 , with `` blue '' and `` red '' outliers with respect to the 15 gyr late - type model sequence . _ ii ) _ the `` thickness '' of the @xmath123 data distribution exceeds the internal photometric error [ reportedly @xmath124 mag ] , reaching a dispersion of @xmath125 mag for sa - sb types and @xmath126 mag for later types spirals and irregulars , as indicated by donas _ et al . _ ( 1987 ) . _ iii ) _ the observations tend to be @xmath127 mag `` redder '' in @xmath123 than the late - type model sequence with m@xmath128 m@xmath2 . a careful analysis of the data shows that the three blue outliers [ i.e. those galaxies with @xmath129 in fig . [ donas1 ] ] are all i m systems ( @xmath130 ) with active star formation . their integrated colors are consistent with a bulk of early - type stars ( i.e. of spectral type @xmath131 v or earlier ) and therefore indicate a younger age . this is confirmed by a better fit with our 1 gyr i m model , as reported in the figure . on the other side , the five `` red '' outliers [ i.e. those with @xmath132 in the plot ] are all early - type or bulge - dominated systems , and are in fact `` bluer '' outliers when compared with the @xmath123 color of the early - type template models . these data could easily be accounted for by the @xmath133 templates considering a weak ( @xmath78 m@xmath2yr@xmath107 ) residual star formation instead of a plain ssp evolution ( as assumed in our calculations , cf . table [ caliball ] ) . although also marginally detectable in the @xmath114 plot ( cf . [ buta ] ) , this feature more sensibly affects the 2000 luminosity by changing the uv vs. optical relative emission of the galaxies . in this sense , it is important to stress that uv colors of our @xmath133 models should be taken as redder ( upper ) limits , as indicated in fig . [ donas1 ] . concerning point _ ii ) _ , donas _ et al . _ ( 1987 ) ascribe most of the observed @xmath123 scatter to intrinsic galaxy - to - galaxy sfr variations . as expected , the effect should magnify at uv wavelengths , compared for example to the @xmath85 scatter . according to eq . ( [ eq : lmin ] ) , the intrinsic @xmath123 distribution implies a sfr dispersion of over a factor of two among galaxies of the same morphological type . table [ caliball ] helps translating this effect in term of @xmath85 variation . by doubling the disk birthrate , for example between the sc and the i m template , we have a change of @xmath134 mag in the galaxy integrated color ; this leads to a slope of roughly @xmath135 for the star - formation `` color vector '' of late - type systems . as a final point in our discussion , the `` redder '' offset of the @xmath123 color distribution with respect to the model sequence is open to different explanations ( apart from the comparable internal uncertainty in the @xmath121 photometric zero - point of the observations ) . according to table [ zero ] , a lower uv emission can be achieved either by decreasing the imf upper cutoff or with a steeper imf slope ( that is assuming a dwarf - dominated stellar population ) ; alternatively , we should call for a systematically lower stellar birthrate in the galaxies . in any case , the required change both in the imf slope and in the current sfr would also lead to an exceedingly redder @xmath85 ( buzzoni 1989 ) , while a lower value for m@xmath136 could better match the data by selectively reducing the 2000 emission alone , as shown in fig . [ donas1 ] . a further and possibly crucial issue in this regard , however , is the galaxy internal extinction ; the presence of dust would in fact act in the sense of a systematic bias toward redder uv colors . according to the calzetti ( 1999 ) attenuation law , we obtain a color vector @xmath137 , so that a typical ( internal ) color excess @xmath138 mag could fairly account for the observations . our models for galaxy spectral evolution do not explicitly include dust absorption . its effect on galaxy sed is in the sense of suppressing uv emission and enhancing infrared luminosity , as a consequence of the thermalization process . in addition to stellar extinction , when considering external galaxies we should also account for the contribution of grain scattering , as well as the geometry of dust distribution and its partition between diffuse and `` clumpy '' phases . while scattering could sensibly alleviate the uv extinction ( bruzual _ et al . _ 1988 ; witt _ et al . _ 1992 ) , a prevailing presence of dust segregated in interstellar clouds would act in the opposite sense ( calzetti _ et al . _ 1994 ; kuchinski _ et al . _ 1998 ) . a direct way to probe dust attenuation in the galaxy sed is to evaluate the flattening of the spectral slope at short wavelength , assuming @xmath139 ( kinney _ et al . _ 1993 ) . in agreement with leitherer s _ et al . _ ( 1999 ) calculations , our dust - free models predict for late - type galaxies a value of @xmath140 in the wavelength range 16002800 ( cf . tables 5 - 9 ) . this should be regarded as a lower limit to the observations , since @xmath141 will in general increase ( up to positive values ) in presence of dust absorption . note , by the way , that the spectral slope @xmath141 is basically equivalent to a measure of the ab color in the relevant wavelength range . from the @xmath142 and @xmath143 ab magnitudes we have , for instance , @xmath144 . and @xmath145 . replacing the ab color definition , @xmath146 , we finally obtain @xmath147 , where @xmath148 is the logarithm of the wavelength baseline on which i compute @xmath149 . ] the spectral slope for local galaxies along the whole hubble morphological type can be probed relying on the catalog of rifatto _ et al . _ ( 1995 ) . these authors collected homogeneous data for a wide sample of 400 galaxies , mainly from the iue database , reporting magnitudes in three photometric bands at 1650 , 2500 , and 3150 . although not perfectly coincident with our wavelength range , a consistent estimate of @xmath141 can be obtained for a total of 161 galaxies from the 1650 and 2500 magnitudes . in this regard , we preferred not to extrapolate the data to our 16002800 interval , since only a few galaxies in the rifatto _ et al . _ ( 1995 ) catalog have confident observations at 3150 , and this would have drastically reduced the useful sample for our analysis . figure [ rifatto ] summarizes the observed @xmath141 distribution for the late - type galaxy subsample ( 93 galaxies in total ) . to study a possible trend with galaxy morphology , data have been grouped in five bins according to the de vaucouleurs @xmath150 parameter , as indicated in the plots . in addition to the rifatto _ et al . _ ( 1995 ) sample , the figure also includes the relevant results for 19 starburst galaxies from gordon _ et al . _ ( 1997 ) with complete 7-band photometry between 1250 and 2895 ; this allowed a confident estimate of @xmath141 at the nominal wavelength range of the models . as a general trend , note from fig . [ rifatto ] that galaxy distribution always peaks , on average , at flatter uv slopes ( i.e. @xmath151 ) compared to our theoretical lower limit ; this indicates that some intervening absorption is systematically affecting the observations , with starburst and later - type galaxies ( type sd / im ) marginally more obscured with respect to sa / sb systems . the effect of dust reddening seems to exceed the internal uncertainty of the data , that is , @xmath152 for rifatto _ et al . _ ( 1995 ) and @xmath153 for gordon _ et al . _ ( 1997 ) . the gordon _ _ ( 1997 ) data were originally corrected for the average galactic extinction , and they better track the net effect of internal dust absorption . this is not the case for the rifatto _ et al . _ ( 1995 ) sample , where the uv flattening is a sum of both internal galaxy attenuation and milky way extinction . according to the seaton ( 1979 ) extinction law , the expected reddening vector for the 16002800 uv slope is @xmath154 , while the calzetti ( 1999 ) attenuation law suggests @xmath155 . an average flattening of @xmath156 , as shown by the data , therefore implies an internal color excess of @xmath157 mag , consistent with the donas _ et al . _ ( 1987 ) data . this is about a 2 mag extinction at 1600 , according to calzetti ( 1999 ) . the role of dust has raised to a central issue in the current cosmological debate , given its importance for a fair determination of the cosmic sfr through the uv observation of high - redshift galaxies ( hughes _ et al . _ 1998 ; steidel _ et al . _ 1999 ; massarotti _ et al . _ 2001b ; hopkins _ et al . _ 2001 ) . generally speaking , a large fraction of residual gas , such as in primeval galaxies , should call for a _ low _ amount of dust . the latter is in fact a natural output of stellar evolution ( mass loss and supernova events actually supply the basic ingredients for grain formation ) , and should therefore _ follow _ star formation not _ precede _ it . as a matter of fact , however , young starbursters certainly appear to be more dust - rich than old quiescent ellipticals ( calzetti _ et al . _ 1994 ) . the association of greater quantities of dust with strongly star - forming galaxies may perhaps be due to a shorter timescale for dust than for star formation , or more likely to a feedback process , by which starbursts preferentially occur in dense gas / molecular clouds already heavily contaminated by dust . both these arguments point to a tight relationship between dust absorption ( and its induced ir emission ) and galaxy uv luminosity , as found by meurer _ et al . _ ( 1999 ) ; apparently , this correlation is already in place at high redshift , as demonstrated by adelberger and steidel ( 2000 ) . a dominant contribution of the uv - selected galaxy population to the ir cosmic background is also in line with the results of massarotti _ et al . _ ( 2001b ) , who fully reconcile the scuba estimates for sfr density at high @xmath3 ( barger _ et al . _ 2001 ) with the hubble deep field optical observations . an important point that one should bear in mind , however , is that dust comes from cumulative processes inside galaxies , and its content should generally increase with time ; contrary to the observations , this would predict more heavily obscured systems at present time . in order to break this apparent dichotomy we need to `` split '' , at some point of galaxy evolution , the distribution of the luminous matter ( i.e. stars ) and dust . the case of our own galaxy might be explanatory in this sense . because of a higher velocity dispersion and supernova shock waves , young o - b associations leave parent molecular clouds and spread their b stars across the disk on a timescale of some @xmath1 yrs , a value comparable to the lifetime of stars of 5 - 10 m@xmath2 ( see , in this regard , the classical work of becker and fenkart 1963 , or the recent contribution of hoogerwerf _ et al . _ if this is the case also for external galaxies , then an increasing fraction of luminous matter would quickly escape the regions of harder and `` clumpy '' dust absorption ( _ la _ calzetti 1999 ) moving towards a milder and `` scattered '' dust environment ( _ la _ bruzual _ et al . _ this scenario would consistently explain , among other things , why dust attenuation seems to affect more severely gas clouds than stars even in starburst galaxies ( calzetti _ et al . _ in this paper i have explored some relevant features dealing with the uv luminosity evolution of primeval galaxies , in view of a direct application to high - redshift studies . this has been done via a new set of evolutionary population synthesis models that provided reference templates for different galaxy morphological types . theoretical seds for late- and early - type systems have been derived , together with detailed luminosity evolution at 1600 , 2000 , and 2800 . as expected , the galaxy uv luminosity below 3000 is largely dominated by the high - mass stellar component , and the distinctive properties of the integrated sed are nearly independent of both the total mass of the galaxy and its past star formation history . at every age , this leads to a direct relationship between galaxy uv luminosity and actual sfr ( cf . . [ eq : lmin ] and fig . [ calib ] ) . due to a faster evolution of the bulge stellar population ( basically a ssp with @xmath158 and @xmath34 ) , the high - redshift ancestors of present - day spirals should appear as sharply nucleated objects displaying scarce or no morphological structure . in addition , early galaxy evolution ( @xmath159 gyr ) could also display some color `` degeneracy '' in the uv range ( cf . [ lh ] ) loosing any clear relationship between photometric properties and galaxy morphology along the hubble sequence . this effect should not be neglected for its possible importance in a fair sampling of the galaxy population at high redshift ( buzzoni 1998 ) . the claimed role of late - type systems as prevailing contributors to the cosmic uv background is reinforced by our results ; at 2000 i m irregulars are found in fact nearly four orders of magnitude brighter than ellipticals , per unit luminous mass ( cf . [ ml ] ) . the uv wavelength range is especially sensitive to dust absorption ; this problem should be properly assessed in high - redshift studies . the sed of local starburst and late - type galaxies shows clear evidence of some intrinsic reddening systematically affecting galaxies in their active star - forming stage . the amount of luminosity extinction for these objects sensibly depends on the assumed dust environment and grain properties , but it may be as high as 2 mag at 1600 in the most typical cases . dust is expected to cumulate along the galaxy lifetime , so that the @xmath160 ratio should increase more than linearly with time for both spirals and ellipticals . however , the apparent lack of strong reddening in old quiescent systems at present time indicates that even in the uv range most of the luminous contribution comes from relatively unabsorbed stars . this would call for some evolution in the dust environment , where a pristine `` clumpy '' extinction regime , such as in the calzetti _ ( 1994 ) scheme , would quickly turn into a diffuse `` scattered '' reddening , as in the bruzual _ et al . _ ( 1988 ) models . it is a pleasure to thank the anonymous referee for his / her important suggestions that greatly helped tuning the original discussion . emanuele bertone is acknowledged for his precious help with the calculations of the kurucz model atmospheres , used in this work . this project received partial financial support from the italian murst under cofin98 02 - 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the ultraviolet luminosity evolution of star - forming galaxies is explored from the theoretical point of view , especially focusing on the theory of uv energetics in simple and composite stellar populations and its relationship to the star formation rate and other main evolutionary parameters . galaxy emission below @xmath0 directly correlates with actual star formation , not depending on the total mass of the system . a straightforward calibration is obtained , in this sense , from the theoretical models at 1600 , 2000 and 2800 , and a full comparison is carried out with iue data and other balloon - borne observations for local galaxies . the claimed role of late - type systems as prevailing contributors to the cosmic uv background is reinforced by our results ; at 2000 i m irregulars are found in fact nearly four orders of magnitude brighter than ellipticals , per unit luminous mass . the role of dust absorption in the observation of high - redshift galaxies is assessed , comparing model output and observed spectral energy distribution of local galaxy samples . similar to what we observe in our own galaxy , a quick evolution in the dust environment might be envisaged in primeval galaxies , with an increasing fraction of luminous matter that would escape the regions of harder and `` clumpy '' dust absorption on a timescale of some @xmath1 yr , comparable with the lifetime of stars of 510 m@xmath2 .

urolithiasis is a common disorder that affects approximately 3 - 5% of the population and is usually associated with metabolic abnormalities [ 1 - 3 ] . although both intrinsic and environmental factors contribute to urinary stone formation , the exact cause is not fully understood [ 2 - 7 ] . more precise knowledge about the etiology of urolithiasis may contribute to improvements in disease management and prevention . hypercalciuria has been considered to be the most common abnormality identified in calcium stone formers ( sfs ) . recent studies have suggested that a defect in phosphate balance , such as maximal reabsorption of phosphate by the glomerular filtration rate ( tmp / gfr ) , is a significant underlying cause of calcium urolithiasis [ 8 - 11 ] . reduced renal phosphate reabsorption leads to hypophosphatemia that , in turn , increases 1,25(oh)2-vitamin d synthesis and enhances the intestinal absorption of phosphate and calcium , resulting in hypercalciuria [ 12 - 14 ] . additionally , mutations in the genes that encode two renal sodium phosphate co - transporters , npt2a and npt2c , have been identified in patients with hyperphosphaturia . inactivation of the gene that encodes npt2a results in increased excretion of phosphate and calcium and bone demineralization . thus , there has been increasing interest in the role of renal phosphate handling and the associated hyperphosphaturia in stone formation . identification of modifiable risk factors for urolithiasis may result in new approaches to the treatment and prevention of this disorder . the present study was designed to assess whether phosphaturia relates to urinary metabolic abnormalities and recurrent stone formation . a database of calcium sfs who were diagnosed and treated between 1994 and 2008 at our institute was reviewed . the database included stone history , medication , and a metabolic evaluation that included serum chemistry , 24-hour urinary chemistry , and radiographic imaging of the urinary tract . a diagnosis of calcium stone formation was based on an abdominal radiograph and ultrasound examination . sfs with any of the following conditions were excluded from the analysis : pediatric patients ( < 16 years ) , incomplete 24-hour urine collection , impaired renal function ( serum creatinine > 1.5 mg / dl ) , staghorn calculi , urinary tract obstruction , malformation of the urological system , hypercalcemia , prior diagnosis of primary hyperparathyroidism , or other systemic diseases that might affect calcium and bone metabolism . medications that could affect biochemical parameters were discontinued 2 weeks before the 24-hour urine collection . sfs were told to continue their usual diet , and no patient had been placed on a low - calcium diet . thus , 1,068 consecutive calcium sfs [ 706 first - time stone formers ( fsfs ) and 362 recurrent stone formers ( rsfs ) ] with complete metabolic assessments were included in the final analysis . of these , sfs who had been followed up for more than 36 months or had stones during the follow - up period ( median , 46.0 months ; range , 5 - 151 months ) were eligible for analysis of stone recurrence . after informed consent was obtained , 106 healthy volunteers ( mean age : 42.212.8 years [ range , 17 to 72 years ] ; 67% male [ 69/106 ] ; 34.7% female [ 37/106 ] ) who had no evidence of stone disease as confirmed by abdominal radiograph and ultrasound examination , unimpaired renal function , no history of urological disease , and no medications were enrolled as controls . 95% of the subjects had a urinary phosphate excretion of less than 800 mg / day . because there is no universally accepted definition for hyperphosphaturia , any value for phosphaturia that was higher than 95% of the control values was defined as indicative of hyperphosphaturia . urinary metabolic abnormalities were classified into five categories as follows : low urine volume ( urine volume less than 2,000 ml hypercalciuria ( calcium greater than 300 mg in males and 250 mg in females ) , hyperoxaluria ( oxalate greater than 45 mg ) , hyperuricosuria ( uric acid greater than 800 mg in males and 750 mg in females ) , and hypocitraturia ( citrate less than 320 mg ) . stone recurrence was defined as the passage , extracorporeal removal , endoscopic or surgical removal , or radiographic appearance of stones that were not present on previous examination . the time to stone recurrence was measured from the date the patient was pronounced as being stone free at our institution to the date of stone relapse during the follow - up period or last follow - up . to investigate the effect of phosphaturia on urinary metabolites and recurrent stone formation differences in the urine variables between the subgroups were assessed by student 's t - tests . the kaplan - meier method was used to calculate the time to recurrence , and differences were assessed with log - rank statistics . the prognostic value for the status of phosphaturia on stone recurrence was studied with a cox proportional hazards regression model . all statistical analyses were performed with spss 12.0 software ( spss inc . , chicago , usa ) , and p - values<0.05 were considered statistically significant . a database of calcium sfs who were diagnosed and treated between 1994 and 2008 at our institute was reviewed . the database included stone history , medication , and a metabolic evaluation that included serum chemistry , 24-hour urinary chemistry , and radiographic imaging of the urinary tract . a diagnosis of calcium stone formation was based on an abdominal radiograph and ultrasound examination . sfs with any of the following conditions were excluded from the analysis : pediatric patients ( < 16 years ) , incomplete 24-hour urine collection , impaired renal function ( serum creatinine > 1.5 mg / dl ) , staghorn calculi , urinary tract obstruction , malformation of the urological system , hypercalcemia , prior diagnosis of primary hyperparathyroidism , or other systemic diseases that might affect calcium and bone metabolism . medications that could affect biochemical parameters were discontinued 2 weeks before the 24-hour urine collection . sfs were told to continue their usual diet , and no patient had been placed on a low - calcium diet . thus , 1,068 consecutive calcium sfs [ 706 first - time stone formers ( fsfs ) and 362 recurrent stone formers ( rsfs ) ] with complete metabolic assessments were included in the final analysis . of these , sfs who had been followed up for more than 36 months or had stones during the follow - up period ( median , 46.0 months ; range , 5 - 151 months ) were eligible for analysis of stone recurrence . after informed consent was obtained , 106 healthy volunteers ( mean age : 42.212.8 years [ range , 17 to 72 years ] ; 67% male [ 69/106 ] ; 34.7% female [ 37/106 ] ) who had no evidence of stone disease as confirmed by abdominal radiograph and ultrasound examination , unimpaired renal function , no history of urological disease , and no medications were enrolled as controls . 95% of the subjects had a urinary phosphate excretion of less than 800 mg / day . because there is no universally accepted definition for hyperphosphaturia , any value for phosphaturia that was higher than 95% of the control values was defined as indicative of hyperphosphaturia . urinary metabolic abnormalities were classified into five categories as follows : low urine volume ( urine volume less than 2,000 ml hypercalciuria ( calcium greater than 300 mg in males and 250 mg in females ) , hyperoxaluria ( oxalate greater than 45 mg ) , hyperuricosuria ( uric acid greater than 800 mg in males and 750 mg in females ) , and hypocitraturia ( citrate less than 320 mg ) . stone recurrence was defined as the passage , extracorporeal removal , endoscopic or surgical removal , or radiographic appearance of stones that were not present on previous examination . the time to stone recurrence was measured from the date the patient was pronounced as being stone free at our institution to the date of stone relapse during the follow - up period or last follow - up . to investigate the effect of phosphaturia on urinary metabolites and recurrent stone formation , subjects were classified as sfs with normophosphaturia or as sfs with hyperphosphaturia . differences in the urine variables between the subgroups were assessed by student 's t - tests . the kaplan - meier method was used to calculate the time to recurrence , and differences were assessed with log - rank statistics . the prognostic value for the status of phosphaturia on stone recurrence was studied with a cox proportional hazards regression model . all statistical analyses were performed with spss 12.0 software ( spss inc . , chicago , usa ) , and p - values<0.05 were considered statistically significant . the 1,068 patients were grouped according to whether or not they had hyperphosphaturia ( 80.1% of the sfs had normophosphaturia [ 856/1,068 ] ; 19.9% of the sfs had hyperphosphaturia [ 212/1,068 ] ) . the mean age was significantly different between the two groups . compared with fsfs , the incidence of hyperphosphaturia was more common in rsfs . sfs with hyperphosphaturia had greater urinary volume and higher levels of calcium , uric acid , oxalate , and citrate than did sfs with normophosphaturia . the mean urinary ph was lower in sfs with hyperphosphaturia than in sfs with normophosphaturia . subgroup analyses , grouped by stone episodes , also showed similar results ( table 2 ) . two hundred forty - seven ( 23.1% ) sfs were eligible for analysis of recurrent stone formation ( 21.1% of the fsfs [ 149/706 ] and 27.1% of the rsfs [ 98/362 ] ) . during the follow - up period , 62.3% ( 154/247 ) had recurrent stones ( 57.0% of the fsfs [ 85/149 ] vs. 70.4% of the rsfs [ 69/98 ] , p=0.034 ) . kaplan - meier estimates revealed significant differences in the prevalence of recurrent stone formation between patients with hyperphosphaturia and those with normophosphaturia ( log - rank test , p=0.032 ) ( fig . stratified by stone episodes , fsfs with hyperphosphaturia had a shorter time to stone recurrence than did fsfs with normophosphaturia ( log - rank test , p=0.010 ) ( fig . 1b ) , whereas the time to recurrence was not affected by hyperphosphaturia in the rsfs ( log - rank test , p=0.931 ) . multivariate cox regression analyses that included known clinical ( mean age at stone onset , sex , stone episodes , family history of stones , and stone multiplicity ) and metabolic ( low urine volume , hypercalciuria , hyperuricosuria , hyperoxaluria , and hypocitraturia ) risk factors for stone recurrence revealed that hyperphosphaturia ( hazard ratio [ hr ] : 1.718 ; 95% confidence interval [ ci ] : 1.090 - 2.707 ; p=0.020 ) was significantly associated with stone recurrence in sfs . stratified by stone episodes , hyperphosphaturia ( hr : 2.122 ; 95% ci : 1.100 - 4.097 ; p=0.025 ) was the only independent predictor for stone recurrence in fsfs . in contrast , hyperphosphaturia was not associated with stone recurrence in rsfs ( table 3 ) . the 1,068 patients were grouped according to whether or not they had hyperphosphaturia ( 80.1% of the sfs had normophosphaturia [ 856/1,068 ] ; 19.9% of the sfs had hyperphosphaturia [ 212/1,068 ] ) . the mean age was significantly different between the two groups . compared with fsfs , the incidence of hyperphosphaturia was more common in rsfs . sfs with hyperphosphaturia had greater urinary volume and higher levels of calcium , uric acid , oxalate , and citrate than did sfs with normophosphaturia . the mean urinary ph was lower in sfs with hyperphosphaturia than in sfs with normophosphaturia . subgroup analyses , grouped by stone episodes , also showed similar results ( table 2 ) . two hundred forty - seven ( 23.1% ) sfs were eligible for analysis of recurrent stone formation ( 21.1% of the fsfs [ 149/706 ] and 27.1% of the rsfs [ 98/362 ] ) . during the follow - up period , 62.3% ( 154/247 ) had recurrent stones ( 57.0% of the fsfs [ 85/149 ] vs. 70.4% of the rsfs [ 69/98 ] , p=0.034 ) . kaplan - meier estimates revealed significant differences in the prevalence of recurrent stone formation between patients with hyperphosphaturia and those with normophosphaturia ( log - rank test , p=0.032 ) ( fig . . stratified by stone episodes , fsfs with hyperphosphaturia had a shorter time to stone recurrence than did fsfs with normophosphaturia ( log - rank test , p=0.010 ) ( fig . 1b ) , whereas the time to recurrence was not affected by hyperphosphaturia in the rsfs ( log - rank test , p=0.931 ) . multivariate cox regression analyses that included known clinical ( mean age at stone onset , sex , stone episodes , family history of stones , and stone multiplicity ) and metabolic ( low urine volume , hypercalciuria , hyperuricosuria , hyperoxaluria , and hypocitraturia ) risk factors for stone recurrence revealed that hyperphosphaturia ( hazard ratio [ hr ] : 1.718 ; 95% confidence interval [ ci ] : 1.090 - 2.707 ; p=0.020 ) was significantly associated with stone recurrence in sfs . stratified by stone episodes , hyperphosphaturia ( hr : 2.122 ; 95% ci : 1.100 - 4.097 ; p=0.025 ) was the only independent predictor for stone recurrence in fsfs . in contrast , hyperphosphaturia was not associated with stone recurrence in rsfs ( table 3 ) . recently , several studies have shown that patients with idiopathic hypercalciuria have phosphaturia or renal phosphate leakage . renal phosphate leakage and the associated phosphaturia result in increased production of 1,25(oh)2-vitamin d3 , which causes increased intestinal phosphate and calcium absorption . the combination of hyperphosphaturia and hypercalciuria from the increased intestinal calcium absorption favors the formation of calcium phosphate complexes that can result in urolithiasis . in a previous study , 19% of sfs had renal phosphate leakage , defined as renal phosphate threshold values lower than 95% of the normal control population , which was associated with high urinary calcium excretion . similarly , our results showed that the incidence of hyperphosphaturia was 19.9% , which partly supports findings showing that renal phosphate leakage is frequently detected in patients with stone disease . studies of phosphate excretion have shown that phosphaturia plays a key role in stone formation . calcium phosphate crystals are injurious to cells of the proximal tubules and the collecting ducts . calcium phosphate crystals can interact with the renal epithelium , promote sites for crystal attachment , and then either grow into mature calcium phosphate stones or create sites for calcium oxalate crystal formation , allowing calcium oxalate crystals to grow into clinically significant kidney stones . in our study with long - term follow - up of patients , hyperphosphaturia significantly affected not only urinary metabolites but also recurrent stone formation . although the exact biological mechanism is still not known , the results of previous studies provide possible explanations [ 8,16 - 22 ] . more recently , several reports suggested that the renal phosphate transporters are an important cause of phosphaturia in patients with urolithiasis [ 17,20 - 22 ] . npt2a is present in the apical membrane of the renal proximal convoluted tubule and is responsible for reabsorption of 80% of the phosphates filtered at the glomerulus . regardless of the serum phosphate concentration , phosphate is freely filtered across the glomerulus and reabsorbed along the renal tubule , primarily the proximal tubule , through two distinct sodium phosphate transporters that are dependent on the sodium gradient . in addition , the sodium - hydrogen exchanger regulatory factor 1 ( nherf1 ) can interact with known amino acid sequences at the c - terminal end of npt2a , which induces alteration of npt2a targeting . targeted gene deletion of nherf1 provokes not only increased excretion of phosphate , calcium , and uric acid , but also interstitial deposition of calcium , primarily in the papilla of the kidney , which are prone to the formation of calcium stones , uric acid stones , or both . these findings support our results showing that hyperphosphaturia was significantly associated with increased urinary excretion of calcium and uric acid as well as stone recurrence . however , it is uncertain why hyperphosphaturia was associated with recurrent stone formation only in fsfs . there have been several reports of metabolic differences , such as urinary excretion of citrate , uric acid , and urine volume , between fsfs and rsfs . these differences may lead to the inconsistent effect of hyperphosphaturia on recurrent stone formation in fsfs and rsfs . our data also demonstrated that hyperuricosuria was an independent risk factor predicting recurrent stone formation in rsfs . uric acid crystals act as a nidus for calcium oxalate stone formation by altering the solubility or precipitation product of calcium and oxalate in solution . a recent study also indicated that nherf1 interacts with the mouse urate transporter 1 ( murat1 ) to regulate uric acid transport in the renal proximal tubule and that uric acid excretion is increased in nherf1-knockout mice . patients with gout display a significantly reduced tubular reabsorption of phosphate and renal phosphate threshold , which results in hyperphosphaturia . these observations support our findings of a close relationship between hyperphosphaturia and increased urinary excretion of uric acid . however , it is unclear why hyperphosphaturia was closely correlated with other urinary metabolites , such as urine volume , ph , oxalate , and citrate , in our results . these associations may be due to not only various loads of dietary phosphate , but also the existence of currently unidentified mechanisms or interactions . accordingly , this may cause the paradoxically increased excretion of citrates and urine volume , which are well - known urinary stone inhibitory factors , in sfs with hyperphosphaturia . setting , identification of meaningful , modifiable risk factors is useful for reducing the prevalence of recurrent stone formation . our results suggest that hyperphosphaturia is an independent , predictive determinant of stone recurrence . in this for example , administration of thiazide reduces calcium and phosphate excretion , whereas oxalate excretion increases significantly . because a calcium phosphate solid phase seems to be the initial mineralization event in patients with calcium oxalate stones , thiazide may prevent recurrent calcium oxalate stones by reducing calcium phosphate supersaturation . appropriate control of phosphaturia in patients with hyperphosphaturia may be a promising approach for restoring normal urine composition and reducing the number of stone episodes . the results of this study demonstrate that hyperphosphaturia is closely associated with urinary metabolic abnormalities .

purposerecent studies have suggested that renal phosphate leakage and the associated phosphaturia are significant underlying causes of calcium urolithiasis . the aims of this study were to assess whether phosphaturia relates to urinary metabolic abnormalities and recurrent stone formation.materials and methodsa database of patient histories and urine chemistries was analyzed for 1,068 consecutive stone formers ( sfs ) and 106 normal controls . urine values for phosphaturia that were higher than 95% of the normal control values were defined as indicating hyperphosphaturia , and the effect of phosphaturia on urinary metabolites and stone recurrence was determined . of these patients , 247 patients ( 23.1% ) who had been followed up for more than 36 months or had a recurrence of stones during follow - up ( median , 46.0 months ; range , 5 - 151 ) were included in the analyses for stone recurrence.resultsof the sfs , 19.9% ( 212/1,068 ) had increased urinary phosphate excretion . sfs with hyperphosphaturia had a greater urinary volume and higher levels of calcium , uric acid , oxalate , and citrate than did sfs with normophosphaturia . a multivariate cox regression model , stratified by stone episodes , revealed that hyperphosphaturia was an independent predictor of recurrent stone formation in first - time sfs ( hazard ratio [ hr ] : 2.122 ; 95% confidence interval [ ci ] : 1.100 - 4.097 ; p=0.025 ) . no association was detected between hyperphosphaturia and recurrent stone formation in recurrent sfs . kaplan - meier curves showed identical results.conclusionsthis study demonstrates that hyperphosphaturia is closely associated with urinary metabolic abnormalities . furthermore , hyperphosphaturia is a significant risk factor for stone recurrence in first - time sfs .

the hard - sphere system has been of central interest in the theory of fluids since the early work of boltzmann and is still an important model system in statistical physics . at low and intermediate densities the equilibrium pair structure and thermodynamics are theoretically well understood and the model can be regarded as solved , in the sense that the numerical results agree with simulation to an accuracy satisfactory for most applications . at high density the system undergoes a first - order liquid - solid transition to an fcc crystal @xcite the theoretical description of which remains an open problem . the challenge for theoretical treatments of the freezing transition is to obtain a unified description of both the amorphous fluid and the symmetry broken solid . the density functional theory of freezing provides a pragmatic approach to this problem in which the solid is regarded as a highly inhomogeneous fluid @xcite . by employing a seperate treatment of the fluid and solid branches of the free energy ( crystal symmetry is input to the theory by hand ) modern density functional approximations are able to locate the coexisting densities of the hard - sphere freezing transition in close agreement with simulation @xcite . nevertheless , a unified theory in which the crystal symmetry emerges spontaneously upon increasing the density is still lacking . one possible method of gaining insight into the emergence of crystalline order is to investigate in detail the microscopic structure of the fluid state at densities close to , but below , the freezing transition . recent simulations performed within this density range suggest the existence of precursor structures to freezing in the high density liquid state of hard - spheres in two and three - dimensions . it has been demonstrated @xcite using molecular dynamics simulations that the radial distribution function ( rdf ) of both the hard - disk and hard - sphere systems develops a shoulder feature in the second peak which first appears at packing fractions within roughly five percent of their respective freezing transitions . to facilitate visualization of configurations the analysis focused primarily on the hard - disk system for which a signature four - particle hexagonal - close - packed configuration of disks was identified as being responsible for the observed shoulder in the rdf . this distinct structural motif reflects the next - nearest - neighbour ordering of the hexagonal domains which develop as the density is increased towards freezing . an analogous scenario was also proposed for the hard - sphere system but not analyzed in detail . a careful simulation study of the three - dimensional case @xcite revealed six - membered ring configurations which flatten and increase in frequency close to freezing were identified as the relevant structural motif responsible for the shoulder observed in the simulation rdf . the existence of the shoulder has long been recognized and exploited by simulators as an empirical indicator for crystallization in hard particle systems , enabling expensive free - energy calculations to be avoided . as as result of the recent simulation studies @xcite the microscopic origin of this feature is now understood . considering more general interparticle interactions , it is natural to inquire whether similar precursor structures also occur in systems with an attractive component to the pair potential . in particular , hard - spheres with short - range attraction present a liquid - solid coexistence region which broadens dramatically with increasing attraction strength , leading to coexistence between low - density fluid and high - density solid phases . the possible existence of local crystalline ordering at statepoints in the vicinity of this more general freezing boundary remains to be investigated and raises the question whether the rdf shoulder may also be present at low density statepoints far removed from the hard - sphere transition point . the most powerful theoretical technique for calculating the pair correlations and thermodynamics of classical fluids in equilibrium is the method of integral equations , formed by approximate closures of the ornstein - zernike equation @xcite . for many model interaction potentials integral equations provide highly accurate structural information at low and intermediate coupling strength ( although difficulties do remain in the vicinity of critical points , when they occur @xcite ) . it is therefore surprising that none of the regularly applied integral equation theories for the pair structure are capable of describing the rdf shoulder of hard - spheres and miss completely this well established feature of the equilibrium fluid pair structure , despite their admirable success at fluid statepoints removed from freezing . this failure raises the fundamental question whether the method of integral equations is capable , either in practice or in principle , of indicating the existence of a fluid - solid transition . finding an integral equation theory which can correctly predict from first principles the detailed structure of the rdf in the high density liquid may thus shed some light on this important theoretical question @xcite . in this paper we address the issue of precursor structures using inhomogeneous integral equation theory . this class of theory is based upon the inhomogeneous ornstein - zernike equation @xcite in combination with closure relations between the inhomogeneous direct and total correlation functions . in contrast to their homogeneous counterparts , which involve relations between pair functions , inhomogeneous integral equation theories work at the level of the triplet correlations . as the problem of crystallization and the appearance of precursor structures is associated with an increased local orientational ordering in the system , it is reasonable to suppose that increasing the orientational resolution of the theoretical treatment , i.e. working at the triplet rather than the pair level , will better capture the relevant physics . while a general theory of the emergence of crystalline order is still highly desirable ( and we make no claims to provide this ) we demonstrate that inhomogeneous integral equation theory predicts the occurance of an rdf shoulder in the vicinity of freezing and thus yields indirect evidence for the existence of underlying precursor structures . by considering purely equilibrium fluid statepoints below the freezing transition we avoid the potential complications associated with metastable states . the remainder of the paper will be structured as follows : in section [ theoretical ] we outline the phenomenology of the shoulder in the hard sphere rdf as found in simulation , briefly review existing integral equation approaches and introduce the inhomogeneous integral equation theory to be employed in this work . in section [ hardspheres ] we present numerical solutions of the inhomogeneous theory for hard spheres and compare these with simulation data . in section [ attraction ] we consider the influence on the rdf of adding a short - range attraction to the hard - sphere pair potential . finally , in section [ discussion ] we will discuss our results and give an outlook for future work . [ theoretical ] the simulation results of truskett _ et al _ @xcite show that in both two and three - dimensions the shoulder in the simulation rdf first becomes apparent within approximately five percent of the freezing transition . for the purpose of the present work we restrict ourselves to the case of three - dimensional hard - spheres for which the relevant density range is @xmath0 . the packing fraction is given by @xmath1 for given number density @xmath2 and we take the sphere diameter @xmath3 as the unit of length . in figure.[fig1 ] we show the rdf obtained from monte - carlo simulation for @xmath4 @xcite , where the shoulder is most distict , together with that of the hard - sphere solid at the melting point , located at @xmath5 @xcite . within the high density fluid there exist ordered crystalline domains with a local structure similar to that of the solid phase at the melting point and which lend a significant statistical weight to the rdf @xcite . comparison of the coexisting fluid and solid structure in figure.[fig1 ] is indeed suggestive of local crystalline ordering . the fluid phase rdf is enhanced ( suppressed ) around the peaks ( troughs ) of the coexisting solid rdf relative to what would be expected on the basis of a simple extrapolation of the intermediate density fluid rdf up to freezing . the inset to figure.[fig1 ] shows more clearly the detailed structure of the second peak at freezing , in particular the shoulder which approximately spans the range @xmath6 . the most commonly used theories of the pair structure of classical fluids in equilibrium are based upon closures of the ornstein - zernike equation @xcite @xmath7 where @xmath8 is the bulk density and @xmath9 . eq.([oz ] ) serves to define the direct correlation function @xmath10 which is a function of simpler structure and shorter range ( for finite range potentials ) than @xmath11 . when supplemented by an independent relation between @xmath11 and @xmath10 , containing the details of the interaction potential , ( [ oz ] ) yields a closed integral equation for the pair correlations in the system . integral equation theories are non - perturbative in character and , although the approximations involved are largely uncontrolled , can produce excellent results for some model fluids . the classic closure approximations are the percus - yevick ( py ) @xcite and hyper - netted - chain ( hnc ) @xcite , both of which can be systematically derived using diagrammatic techniques @xcite . for hard - spheres these theories have been subsequently improved upon by closures such as the generalized - mean - spherical - approximation ( gmsa ) @xcite , martynov - sarkisov @xcite , ballone - pastore - galli - gazzillo @xcite , verlet - modified @xcite , rogers - young @xcite and modified - hyper - netted - chain @xcite . although these improved theories represent the state of the art in the theory of fluids , none of them captures the shoulder in the rdf close to freezing @xcite . in the inset to figure.[fig1 ] we show a representative example of this failure by comparing the gmsa theory with simulation at freezing . the triangular structure of the second peak from the gmsa theory is typical of integral equation theories based on ( [ oz ] ) , missing both the detailed structure of the second peak and incorrectly predicting both the location and depth of the first minimum . for @xmath12 all of the above mentioned theories are reliable and agree with simulation data to an acceptable level of accuracy . the primary advance of the theories described above is to improve the thermodynamic output with respect to the py and hnc closures by treating more accurately the rdf in the vicinity of contact . this is typically achieved by incorporating an additional parameter into the theory which can be determined by requirements of thermodynamic consistency . at statepoints removed from freezing this appears to be quite adequate and leads to a good description of the pair correlations at all seperations . in order to capture the high density shoulder a treatment which describes more accurately local packing effects is required . a natural extension of approaches based on ( [ oz ] ) is to use instead the inhomogeneous ornstein - zernike equation @xcite as a starting point and consider closure relations between the inhomogeneous direct and total correlation functions , @xmath13 and @xmath14 . the inhomogeneous ornstein - zernike equation is given by @xmath15 where @xmath16 is the spatially varying density in the presence of an arbitrary external field . in the absence of an external potential the system is translationally invariant , @xmath17 and @xmath18 , and we recover ( [ oz ] ) . as the inhomogeneous one and two - body distribution functions exhibit the same symmetries as the external potential it is possible to simplify ( [ ioz ] ) using integral transforms for the special cases of an external potential possessing either planar or spherical symmetry . in planar geometry hankel transformation reduces ( [ ioz ] ) to a one - dimensional integral @xcite . this simplification has enabled application of inhomogeneous ornstein - zernike theory to both adsorption at planar substrates and the liquid - vapour interface @xcite . in spherical geometry the factorization of ( [ ioz ] ) is achieved using legendre transforms @xcite . an arbitrary spherically inhomogeneous function @xmath19 can be expressed as a function of two scalar radial variables , @xmath20 and @xmath21 , and the cosine of the angle between them , @xmath22 . the legendre transform is thus given by @xmath23 where @xmath24 is the legendre polynomial of degree @xmath8 . the inverse transform is given by @xmath25 the practical advantage of using legendre transforms for such problems is that the rapid convergence of the series ( [ legendre_resolution ] ) allows numerical calculations to be performed using a finite number of polynomials . applying the legendre transformation to ( [ ioz ] ) yields @xcite @xmath26 where @xmath27 has been introduced for notational convenience . as for planar geometry the spherically inhomogeneous ornstein - zernike equation ( [ ioz_transform ] ) retains a one - dimensional integral . the transformed equation ( [ ioz_transform ] ) has been used to study the structural properties of a number of model fluids under conditions of spherical inhomogeneity @xcite . a special case of particular interest arises when the external potential is generated by a particle of the fluid fixed at the coordinate origin . in this test - particle limit the one - body density @xmath28 is related to the bulk rdf by the percus identity @xcite , @xmath29 , and a self - consistent theory for the pair and triplet correlations can be constructed . in order to provide a closed theory the spherically inhomogeneous ornstein - zernike equation ( [ ioz_transform ] ) must be supplemented by an equation for the one - body density @xmath28 and a closure relation between @xmath30 and @xmath31 . several exact relations exist which express @xmath28 as a functional of the inhomogeneous pair correlation functions . of particular importance are the first member of the yvon - born - green ( ybg ) hierarchy @xcite , the triezenberg - zwanzig ( tz ) equation @xcite and the lovett - mou - buff - wertheim ( lmbw ) equation @xcite . we choose to work with the lmbw equation @xmath32 where @xmath33 is the external potential in units of @xmath34 @xcite . in the test - particle limit the external potential is equal to the interparticle pair potential , @xmath35 , and the lmbw equation reduces to @xmath36 where @xmath37 enters as a result of the angular integrals . the ybg , tz and lmbw equations all yield exact relations between @xmath28 and @xmath38 , given the exact inhomogeneous correlation functions as input . if @xmath13 and @xmath14 are only known approximately , as is always the case in practice , then each of the three equations will yield a different @xmath28 for a given @xmath38 . this structural inconsistency is analogous to the thermodynamic inconsistency familiar from standard integral equation theories based on ( [ oz ] ) , where each of the three thermodynamic routes ( virial , compressibility and energy ) yields a different result for the pressure . that an additional inconsistency in the pair correlations occurs between the ybg , tz and lmbw equations is not surprising and simply reflects that we are working at a higher level in the hierarchy . our choice to use the lmbw equation is motivated by the fact that for many situations the derivative @xmath39 decays more rapidly than @xmath28 . this is advantageous for numerical implementation as the integral can be discretized over a smaller range . the exact equations ( [ ioz_transform ] ) and ( [ lmbw_spherical ] ) need to be supplemented by a closure relation between @xmath13 and @xmath14 . this closure represents the only approximation within our treatment . experience with approximate closures of the homogeneous ornstein - zernike equation ( [ oz ] ) has shown that for statepoints removed from freezing a suitably chosen _ local _ closure relation between the direct and total correlation function can produce reliable results for the pair structure . we adopt here the same strategy and consider applying the same local closure relations between the inhomogeneous functions as are usually applied between the corresponding homogeneous functions . in the case of the py and hnc equations such a generalization is natural as both theories follow from well defined diagrammatic resummations . the resummation procedure is not altered by the association of field points in the mayer cluster diagrams with the spatially varying one - body density @xmath16 @xcite . nevertheless , it is not clear that the fortuitous cancellation of errors which can occur when applying a given closure to ( [ oz ] ) ( e.g. hard - spheres in the py approximation ) will be retained when applying the same closure to ( [ ioz ] ) . moreover , application of thermodynamically consistent closures at the triplet level does not guarantee improved results , particularly for the description of structure in regions close to the source of inhomogeneity . despite these potential shortcomings the ultimate assessment of the validity of this approach can only be made from the numerical results , and these are currently very encouraging . studies of simple model fluids in planar @xcite and spherical @xcite geometry suggest that significant improvement over standard ( homogeneous ) integral equation theory can be achieved . in spherical geometry the formally exact closure relation is given by @xmath40 , \label{bridge}\end{aligned}\ ] ] where @xmath41 is the bridge function , an intractable sum of elementary diagrams @xcite . from among the various improved theories an accurate and computationally efficient approximation for the bridge function is provided by the spherically inhomogeneous generalization of the verlet - modified closure @xcite @xmath42\ , ) } , \label{verlet_mod}\end{aligned}\ ] ] where the function @xmath43 $ ] returns the largest of the two arguments and the renormalized indirect correlation function is given by @xmath44 where @xmath45 is the attractive part of the pair potential in units of @xmath34 . when ( [ verlet_mod ] ) is applied as a closure to ( [ oz ] ) for the hard - sphere system the parameter @xmath46 is usually taken to have the value @xmath47 @xcite . the motivation for this choice is that the thermodynamic inconsistency between the compressibility and virial routes to the pressure remains small ( within approximately two percent @xcite ) at all fluid packing fractions . while neglecting possible density dependence of @xmath46 only yields approximate thermodynamic consistency , it provides the computational advantage that the integral equation has only to be solved once for a given statepoint . the numerical demands of solving ( [ ioz ] ) make this an essential requirement for practical application of the inhomogeneous integral equation method . when ( [ verlet_mod ] ) is applied as a closure to the inhomogeneous ornstein - zernike equation ( [ ioz ] ) the value @xmath48 is no longer optimal for global thermodynamic consistency . for the hard - sphere system we find @xmath49 to be a better choice ( see the discussion in section [ hardspheres ] below ) and it is this value which is employed in all numercial calculations presented in this work . a full discussion of the merits of the closure ( [ verlet_mod ] ) as applied to ( [ oz ] ) can be found in @xcite . equations ( [ ioz_transform ] ) , ( [ lmbw_spherical ] ) , ( [ bridge ] ) and ( [ verlet_mod ] ) form a closed set which can be solved self - consistently for @xmath28 , @xmath31 and @xmath30 for given bulk density @xmath8 , temperature and pair potential @xmath38 . the rdf is easily obtained from the density profile using @xmath50 whereas the bulk triplet - rdf is simply related to the spherically inhomogeneous rdf , @xmath51 , by the expression @xmath52 we employ the notation @xmath53 to indicate that the inhomogeneity is due to a test - particle at the origin . eq.([triplet ] ) is essentially the extension of the percus identity to the next level in the hierarchy of correlation functions . within this framework the familiar kirkwood superposition approximation @xcite corresponds to @xmath54 . the set of equations ( [ ioz_transform ] ) , ( [ lmbw_spherical ] ) , ( [ bridge ] ) and ( [ verlet_mod ] ) were solved self consistently by standard iteration , applying broyles mixing @xcite to both the inhomogeneous pair correlation functions and the density profile . a mixing parameter between @xmath55 and @xmath56 was generally found to be sufficient to achieve steady convergence . the convergence rate can be improved by employing the mixing scheme of ng @xcite , but we find that the slight reduction in the nember of iterations does not compensate for the additional memory requirements associated with this method . the majority of computation time in numerical solution of the inhomogeneous equations is taken by calculation of the legendre transforms ( [ legendre_transform ] ) , ( [ legendre_resolution ] ) and the integral ( [ ioz_transform ] ) . in order to minimize computation time we have employed the discrete orthogonal legendre transform proposed by attard @xcite which is both efficient and prevents the build up of round - off errors during iteration . the mesh for the angular integration ( [ legendre_transform ] ) is defined by the roots of @xmath24 , where @xmath8 is the highest - order polynomial considered . a cut - off of @xmath57 was found to be sufficient for all calculations presented in the present work . corrections for the long range tails were made following the suggestions of @xcite whereby the inhomogeneous functions are replaced by their bulk counterparts far from the source of inhomogeneity . in order to obtain high accuracy solutions we employ a grid spacing @xmath58 and between @xmath59 and @xmath60 legendre polynomials in the sum ( [ legendre_resolution ] ) . for hard spheres at packing fractions @xmath61 accurate solutions can be obtained with a coarser mesh . at high density statepoints , for which the liquid is highly structured , it is necessary to work with such a large number of polynomials and a fine grid in order to ensure convergence . for further details of the numerical method we refer the reader to the original work of attard @xcite . [ results ] [ hardspheres ] we now consider application of equations ( [ ioz_transform ] ) , ( [ lmbw_spherical ] ) , ( [ bridge ] ) and ( [ verlet_mod ] ) to the hard - sphere system at packing fractions close to freezing . in the spirit of the the verlet - modified approximation @xcite we have determined the value of the parameter @xmath46 in ( [ verlet_mod ] ) by requiring that the pressures obtained from the virial and compressibility equations agree as closely as possible over the entire fluid density range . this is a numerically demanding procedure which requires solution of the integral equation on an @xmath62-grid covering the range @xmath63 for each trial value of @xmath46 . numerical accuracy is an issue when calculating the pressure , particularly via the compressibility route , and places limits on the accuracy to which @xmath46 can be tuned . we find that the value @xmath49 effectively minimizes the difference in the pressures obtained from the two routes , with a residual discrepancy around the one percent level . before working close to the freezing transition we first seek to establish the accuracy of our approach at dense fluid statepoints removed from freezing . monte - carlo simulations have been performed for the pair and triplet correlations of the hard sphere system at @xmath64 and serve as a useful benchmark for our theory @xcite . we find that at this packing fraction the rdf from the inhomogeneous integral equation theory lies perfectly within the error bars of the simulation data ( not shown ) . as the theory is apparently quasi - exact for the pair correlations we omit this comparison and focus instead on the triplet - rdf for which more significant deviations can be detected . in figure.[fig2 ] we show results for the quantity @xmath65 for a selection of specific configurations . the quantity @xmath66 measures deviations from the superposition approximation and is a sensitive indicator of errors in theoretical approximations for the triplet - rdf . figs.[fig2]a and [ fig2]b show @xmath67 as a function of @xmath68 for two different values of @xmath69 ( rolling geometries ) . given the high density , the level of agreement between theory and simulation is excellent and essentially all details of the simulation data are faithfully reproduced . it should be noted that use of the test - particle approach in combination with an approximate closure such as ( [ verlet_mod ] ) leads to a @xmath70 which does not respect the exact particle exchange symmetry expected of this function . we have investigated this discrepancy for each of the configurations shown in fig.[fig2 ] and find that the curves differ by at most a few percent , depending upon the location of the test particle in the triangle . this close agreement validates to some extent use of the closure ( [ verlet_mod ] ) as the approximate particle exchange symmetry is a non - trivial output of the theory . the data shown in fig.[fig2 ] were generated with the test particle at the lower left position in the schematic configurations shown . in figs.[fig2]c-[fig2]e we consider isosceles triangle configurations for three different triangle base lengths . for @xmath71 and @xmath72 the simulation data are well described by the theory . in particular , the increase of the contact value and development of a peak at @xmath73 in going from [ fig2]d to [ fig2]e are correctly captured . in the range @xmath74 there are slight discrepancies between theory and simulation as the first minimum is not correctly located . it is reassuring to note that the self - consistently obtained rdf appears insensitive to these fine details and remains accurate , despite modest errors in the underlying triplet structure . we can thus proceed with confidence to perform calculations closer to freezing . in fig.[fig3 ] we show results for the rdf at packing fractions @xmath75 and @xmath76 and compare with the results of molecular dynamics simulations @xcite . we concentrate on the range @xmath77 in order to focus attention on the second peak . at packing fraction @xmath78 the shoulder is just visible in the simulation rdf , marking the onset of local crystalline ordering in the fluid . remarkably , this behaviour is correctly captured by the present inhomogeneous integral equation theory . both the shape of the first minimum and the point of inflection which occurs between the first minimum and the second peak are accurately reproduced . as the density is increased the shoulder develops further and by @xmath4 is very pronounced . the present theory describes almost perfectly the evolution of this rich second peak structure as a function of density and captures the characteristic shape of the simulation curves , quite distinct from the triangular form typical of standard approaches based on ( [ oz ] ) . to the best of our knowledge these findings provide the first convincing evidence that the method of integral equations can indicate the existence of the freezing transition . moreover , the set of equations ( [ ioz_transform ] ) , ( [ lmbw_spherical ] ) , ( [ bridge ] ) and ( [ verlet_mod ] ) represent the first example of an approximate ornstein - zernike closure capable of reproducing from first principles the rdf shoulder . in order to demonstrate the relative insensitivity of our results to changes in the parameter @xmath46 we show in the inset to fig.[fig3 ] results for values above and below the optimal value @xmath49 . fig.[fig4]a and fig.[fig4]b allow a more detailed comparison to be made between theory and simulation , showing the rdf and its derivative at freezing . in fig.[fig4]a we compare the present theory with the result of both simulation and gmsa theory @xcite in order to emphasize the inability of such standard integral equation approaches to follow the detailed structure of the simulation curves . in fig.[fig4]b we compare the first derivative @xmath79 from the present theory with simulation and the gmsa . this comparison shows clearly the level of accuracy provided by the inhomogeneous theory . the only slight deviation of the theory from the simulation data occurs in the region in the immediate vicinity of the second peak . this should be contrasted with the gmsa theory which predicts an approximately constant slope over the range @xmath80 . in addition to the accurate description of the second peak we also find that the first peak and contact value of the rdf are in close agreement with simulation . the resulting virial pressure agrees very favourably with established results for the hard - sphere equation - of - state @xcite . [ attraction ] the simulation studies @xcite discussed in the introduction provide strong evidence connecting the appearance of a shoulder in the rdf of hard - spheres and hard - disks to the freezing transition . in the previous section we have shown that for hard - spheres the inhomogeneous integral equation theory yields an rdf consistent with this picture . it is therefore tempting to conclude that the appearance of a shoulder in the theoretical rdf can be used as an empirical indicator for locating the freezing transition . however , there remains the possibility that the occurrance of the shoulder and its apparent connection to the onset of freezing may be particular to the hard - sphere ( hard - disk ) system . we thus seek to investigate the generality of this connection by applying the inhomogeneous theory to a system interacting via a hard - sphere repulsion plus a short - range attraction . for such interaction potentials it is well known that when the range of the attractive interaction becomes sufficiently short - ranged the critical point of the liquid vapour transition becomes metastable with respect to freezing . this is a result of the rapid broadening of the fluid - solid coexistence region as a function of attraction strength which overlaps entirely with the liquid - vapour coexistence region . this novel phase diagram topology thus makes it possible to approach the freezing phase boundary by increasing attraction strength at fixed density . the confirmation of a shoulder in the rdf in the vicinity of this more general freezing phase boundary would considerably strengthen the argument for this empirical freezing indicator . a well studied pair - potential yielding the required phase diagram topology is that due to asakura , oosawa and vrij @xcite . the potential consists of a hard - sphere repulsion plus an attractive tail given by @xmath81 for @xmath82 and zero otherwise . the parameter @xmath83 sets the range of the potential and the amplitude @xmath84 determines the depth of the potential well at contact . this potential has stimulated much interest as it provides a simple approximation to the depletion potential between two hard - sphere colloids in a suspension with added non - adsorbing polymer @xcite . in this context @xmath84 is the packing fraction of polymer coils in a reservoir attached to the system . for the purpose of the present work @xmath84 may simply be regarded as a parameter determining the strength of the attractive interaction . the potential ( [ ao ] ) is convenient because there exist simulation data for the phase boundaries in the ( @xmath85 ) plane for several values of the range parameter @xmath83 . in fig.[fig5 ] we show the simulation phase diagram for @xmath86 @xcite . for this value of @xmath83 the liquid - vapour phase boundary is metastable , albeit weakly , with respect to freezing and the potential is only moderately short - range . for very short - range potentials ( @xmath87 ) resolution of the high and narrow first peak in the rdf requires a spatial grid finer than the @xmath58 presently employed and leads to unacceptable computational demands . the choice @xmath86 thus represents a reasonable compromise , being both numerically tractable and displaying the desired phase diagram topology . in order to analyse the structural predictions of the inhomogeneous theory for the potential ( [ ao ] ) we approach the freezing boundary along two distict paths in the phase diagram . the statepoints for which we present detailed results are indicated in fig.[fig5 ] . we consider first the packing fraction @xmath88 and investigate the rdf as a function of increasing @xmath89 , approaching the freezing boundary along a vertical path in the phase diagram . in fig.[fig6 ] we show the rdf in the vicinity of the second peak for four different statepoints . at statepoint ( a ) the rdf is simply that of hard - spheres ( @xmath90 ) and displays the expected oscillatory structure . as the attraction is increased ( statepoint ( b ) ) there is a notable increase in structure over that of pure hard - spheres . the shifting of the first minimum and second peak to smaller separations reflects the increased interparticle attraction which tends to pull the next - nearest - neighbours closer to the central particle . nevertheless , the results for statepoints ( a ) and ( b ) can still be well reproduced by standard integral equation closures . at statepoint ( c ) additional fine structure not captured by standard theories becomes evident in the second peak and a marginal point of inflection occurs . for slightly stronger attraction ( statepoint ( d ) ) this structure develops into a distict shoulder , reminiscent of that seen close to the freezing transition of pure hard - spheres . the development of the shoulder between statepoints ( c ) and ( d ) is consistent with the broadened freezing transition found in simulation , as shown in fig.[fig5 ] , and occurs over a relatively narrow range of attraction strengths ( @xmath91 ) . it may be inferred that the appearance of this attraction - driven shoulder reflects the existence of underlying precursor structures in the intermediate density fluid . in fig.[fig7 ] we consider approaching the freezing boundary at the lower packing fraction @xmath92 . increasing the attraction strength from statepoint ( e ) to ( g ) we observe the expected increase in fluid structure . statepoint ( h ) lies just below the freezing phase boundary and exhibits the onset of a weak shoulder which develops as the attraction strength is further increased to statepoint ( i ) . in accord with the findings for @xmath88 the onset of the shoulder occurs over a relatively narrow range of attraction strength and is consistent with the location of the simulation phase boundary . for this lower packing fraction the shoulder is less pronounced and is shifted to slightly smaller separations , indicating the decreased statistical weight of the locally ordered regions within the fluid . the striking correlation between the onset of the shoulder and the simulation phase boundary lead us to conclude that the rdf shoulder is a genuine freezing indicator for a broad class of model interaction potentials and not simply an artifact of the hard - sphere fluid at high density . [ discussion ] in this paper we have demonstrated that inhomogeneous integral equation theory provides a highly accurate description of the hard - sphere fluid rdf at densities up to the freezing transition . in agreement with simulation the theory displays the onset of a shoulder in the second peak which is associated with the formation of local crystalline regions in the dense fluid . when applied to a system of hard - spheres plus a short - range attraction the inhomogeneous theory predicts the development of a shoulder as a function of attraction strength consistent with the simulation freezing phase boundary . that the inhomogeneous integral equation theory is capable of capturing these subtle effects demonstrates the accuracy with which local packing constraints are treated . the fact that the present theory acknowledges the existence of the freezing boundary is a significant development beyond standard integral equation closures and validates the significant increase in computational resources required for numerical solution of the equations . although the present study is restricted to three dimensional systems we anticipate that application of the inhomogeneous theory in two dimensions would lead to broadly similar conclusions . for the purpose of this work we have focussed on fluid state structure in the vicinity of freezing . however , the inhomogeneous theory is also capable of a description of the liquid - vapour phase transition which occurs for systems with longer - range attraction than that considered here . for @xmath93 the potential ( [ ao ] ) exhibits a stable liquid - vapour transition . preliminary calculations for range parameter @xmath94 display a large increase in the compressibility along a locus of points in the phase diagram consistent with the simulation liquid - vapour phase boundary @xcite . we therefore feel justified in claiming the theory developed in this work to be the first example of an ornstein - zernike closure sensitive to both the second - order liquid vapour transition and the first - order freezing transition . this goes a step beyond existing integral equation approaches which at best display a line in the phase diagram upon which the compressibility either diverges ( spinodal ) or the theory breaks down ( no - solutions boundary ) @xcite and which show no indication of freezing . of particular interest would be the characterization of the spinodal for the present theory and the determination of the critical exponents which , given the nature of the closure , may be non - classical @xcite . empirical studies of the hard - sphere shoulder have been performed using extrapolations of simulation data , see s. labk and a. malijevsk , mol.phys . * 67 * 431 ( 1989 ) , a. malijevsk , s. labk and w.r . smith , _ ibid_. * 72 * 193 ( 1991 ) j.m.j . van leeuwen , j. groeneveld and j. deboer , physica * 25 * 792 ( 1959 ) , e. meeron , j.math.phys . * 1 * 192 ( 1960 ) , t. morita , prog.theor,phys . * 23 * 829 ( 1960 ) , g.s . rushbrooke , physica * 26 * 259 ( 1960 ) , l. verlet , il nuovo cimento * 18 * 77 ( 1960 ) r. kjellander and s. marcelja , j.chem.phys . * 82 * 2122 ( 1985 ) , r.a . mcgough and m.d . miller , phys.rev.a * 34 * 457 ( 1986 ) , m. plischke and d. henderson , j.chem.phys . * 84 * 2846 ( 1986 ) , i. omelyan , f. hirata and a. kovelenko , pccp * 7 * 4132 ( 2005 ) . a. malijevsky , s. sokoowsky and t. zientarski , j. chem . phys . * 125 * 114505 ( 2006 ) , e. lomba , s. jorge and m. lverez , phys.rev.e * 63 * 011203 ( 2000 ) , d. henderson and s. sokoowski , j.chem.phys . * 103 * 7541 ( 1995 ) , d. henderson and s. sokoowski , j.chem.phys . * 104 * 2971 ( 1996 ) , p. attard , j.chem.phys . * 91 * 3083 ( 1989 ) another potentially useful exact relation between the density derivative of the rdf and the integrated triplet - rdf is eq.(61 ) from the review by g.s . rushbrooke , in _ physics of simple liquids _ ( h.n.v . temperly , j.s . rowlinson and g.s . rushbrooke ) north - holland , amsterdam chapter.2 ( 1968 ) the original verlet - modified closure @xcite was developed for hard spheres but proved less successful for systems with attractive interactions . the improved version ( [ verlet_mod ] ) employed in this work was subequently proposed in @xcite to correct these failings . hard - sphere rdf from computer simulation at freezing , @xmath4 ( full line ) and at the melting point @xmath5 ( dashed line ) . the inset focuses on the shoulder in the second peak of the simulation rdf at freezing ( full line ) . the broken line is the result of gmsa theory and is representative of the inability of standard integral equation theories to capture the shoulder . + figure 2 . comparison of the results of inhomogeneous integral equation theory with the simulation results of mller and gubbins @xcite for the quantity @xmath66 for @xmath95 . the geometries are schematically shown in each figure . the separation @xmath68 is indicated by a line in each case . ( a ) and ( b ) are rolling geometries at @xmath96 and @xmath97 , respectively . ( c)-(e ) are isoceles triangle configurations with @xmath98 and the base length of the triangle fixed at @xmath99 , @xmath100 and @xmath101 , respectively . + figure 3 . the rdf of hard - spheres for packing fractions @xmath75 and @xmath76 ( from bottem to top ) . for clarity the data for @xmath102 and @xmath76 have been shifted vertically by @xmath103 and @xmath104 , respectively . solid lines are the results of the inhomogeneous integral equation theory . open circles are from molecular dynamics simulations @xcite . the inset shows the sensitivity of the second peak to changes in the parameter @xmath46 for @xmath4 . results are shown for the optimal value @xmath49 ( solid line ) , @xmath105 ( broken line ) and @xmath106 ( dotted line ) . + figure 4 . comparison of the inhomogeneous integral equation theory ( solid line ) for @xmath4 with simulation data ( open circles ) @xcite and the gmsa theory ( dashed line ) @xcite . ( a ) and ( b ) show the rdf and the first derivative of the rdf , respectively . + figure 5 . the simulation phase diagram calculated using the asakura - oosawa pair potential ( [ ao ] ) in the @xmath107 plane @xcite . the range of attraction is @xmath86 and @xmath84 represents the strength of the attraction . the solid line is the fluid - solid phase boundary and the dashed line indicates the ( metastable ) liquid - vapour transition . squares labelled a - d and circles labelled e - i mark the state points for which we present detailed results . + figure 6 . the rdf from inhomogeneous integral equation theory for the statepoints labelled a - d in fig.[fig5 ] . in each case the packing fraction @xmath88 . statepoint ( a ) @xmath90 ( dotted line ) , ( b ) @xmath108 ( dot - dashed line ) , ( c ) @xmath109 ( broken line ) and ( d ) @xmath110 ( full line ) . the development of the shoulder is consistent with the simulation freezing phase boundary presented in fig.[fig5 ] . + figure 7 . as for fig.[fig6 ] but for the statepoints labelled e - i in fig.[fig5 ] . in each case the packing fraction @xmath111 . statepoint ( e ) @xmath90 ( dotted line ) , ( f ) @xmath112 ( dot - dashed line ) , ( g ) @xmath113 ( double dot - dashed line ) , ( h ) @xmath114 ( broken line ) and ( i ) @xmath110 ( full line ) .

recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard - spheres at densities close to freezing and which is associated with local crystalline ordering in the dense fluid . we address this structural precursor to freezing using an inhomogeneous integral equation theory capable of describing local packing constraints to a high level of accuracy . the addition of a short - range attractive interaction leads to a well known broadening of the fluid - solid coexistence region as a function of attraction strength . the appearence of a shoulder in our calculated radial distribution functions is found to be consistent with the broadened coexistence region for a simple model potential , thus demonstrating that the shoulder is not exclusively a high density packing effect .

throughout the last four decades nonrelativistic conformal symmetries have been observed in wide area of physics ranging from condensed matter to high energy ( see for example @xcite and references therein ) . in many cases the symmetries are described by the groups extending the galilei symmetry group of nonrelativistic systems @xcite . those extended galilei groups are non - semisimple as the original galilei group . this may be an obstacle to develop systematic study of representations for such groups . the simplest conformal extension of the galilei group may be the schrdinger groups @xcite introduced in the studies of symmetry for free schrdinger equation . geometrical interpretation of the schrdinger group revealed that the ads / cft correspondence has its nonrelativistic analogue @xcite ( see also @xcite ) . supersymmetric extensions of the schrdinger group and its lie algebra have also been discussed in connection with various physical systems such as fermionic oscillator @xcite , spinning particles @xcite , nonrelativistic chern - simons matter @xcite , dirac monopole and magnetic vortex @xcite , many - body quantum systems @xcite and so on . some super schrdinger algebras were constructed from the viewpoint of infinite dimensional lie super algebra @xcite or by embedding them to conformal superalgebras @xcite . despite the numerous publications on the schrdinger algebra and its supersymmetric extensions , the representation theories of them are not studied well . especially there are a few works based on representation theoretic viewpoint . we mention the followings : projective representations of the schrdinger group in 3 spatial dimension were constructed in @xcite . irreducible representations of the schrdinger algebras up to 3 spatial dimension were investigated in @xcite . the author of @xcite studied the highest weight representations of the @xmath3 super schrdinger algebra in 2 spatial dimension ( `` exotic '' algebra in the terminology of @xcite ) . to apply the ( super ) schrdinger algebras for physical problems detailed study of irreducible representations of them will be helpful . in the present work , we provide a classification of the verma modules ( a lowest weight representations ) over the super schrdinger algebras for simple cases , namely , one and two spatial dimensions with @xmath4 supersymmetric extensions . the schrdinger algebra discussed in this paper is centrally extended one . the central term corresponds to the mass of a system . in general , the schrdinger algebra of fixed spacetime dimension has some distinct supersymmetric extensions even for fixed value of @xmath5 a systematic method to extend the schrdinger algebra in @xmath6 dimensional spacetime to arbitrary @xmath7 has developed in @xcite . we restrict our study of the representations to the super schrdinger algebras introduced in @xcite . we denote the centrally extended schrdinger algebra in @xmath6 dimensional spacetime by . the @xmath8 extension of are denoted by and , respectively . the @xmath9 extension of is also denoted by 21 . on the other hand there exist two @xmath10 extensions for . we denote one of them so - called standard by 22 and the another one so - called exotic by @xmath11 the superalgebra @xmath12 corresponds to the @xmath13 extended algebra in the notation of @xcite . the plan of this paper is as follows . we present the definition and structure of the super schrdinger algebras in the next section . after giving the verma modules in section 3 we give all the singular vectors and list of irreducible lowest weight modules without detailed calculation . the detailed proof is found in @xcite . the employed procedure in the references is the same one as @xcite . this shows that the standard method of representation theory for semisimple lie algebras is able to apply the super schrdinger algebras , too . the bosonic schrdinger algebra in @xmath6 dimensional spacetime is generated by the following transformations : time translation @xmath14 , space translations @xmath15 , galilei boosts @xmath16 , spatial rotations @xmath17 , dilatation @xmath18 , conformal transformation @xmath19 and the central element @xmath20 contrast to the relativistic conformal algebra , there exists only one conformal generator . in this section we give the definition of the super schrdinger algebras studied in this paper and their triangular decomposition which will be the key to study representations . the bosonic sector has six generators . their nonvanishing commutators are given by llll [ h , d ] = 2h , & = d , & = 2k , & = m , + [ h , g ] = p , & = g , & = p , & = g. [ s1bosonic ] the @xmath22 extension has three fermionic generators : @xmath23 they satisfy the anti - commutation relations lll \ { , } = -2h , & \ { , } = -2k , & \ { , } = -m , + \ { , } = -p , & \ { , } = -g , & \ { , } = -d . [ s1n1fermionic ] as seen from the relations none of them are nilpotent . nonvanishing bosonic - fermionic relations are listed below : llll [ , d ] = , & = , & = , & = , + [ , g ] = , & = . [ s1n1bs ] the @xmath10 extension has six fermionic generators @xmath24 and one additional bosonic generator @xmath25 corresponding to the @xmath25-parity . the generator @xmath25 commutes with all bosonic elements of . the nilpotent fermionic generators satisfy the anti - commutation relations lll \ { _ , _ } = - 2h , & \ { _ , _ } = - 2k , & \ { _ , _ } = -m , + \ { _ , _ } = -p , & \ { _ , _ } = -g , & \ { _ , _ } = - d r. [ s1n2fermionic2 ] bosonic - fermionic commutators are given by llll [ _ , d ] = _ , & = _ , & = _ , & = _ + [ _ , g ] = _ , & = _ , & = _ , [ s1n2bs2 ] where @xmath26 in this spacetime there exists one spatial rotation @xmath28 the bosonic algebra has nine generators . their nonvanishing commutators are given by llll [ h , d ] = 2h , & = d , & = 2k , & = 2 m , + [ h , g _ ] = p _ , & = g _ , & = p _ , & = g _ , + [ j , g _ ] = g _ , & = p_. & [ s2bosonic ] the @xmath9 extension 21 has four fermionic elements @xmath29 subject to the relations : lll \ { , } = -2h , & \ { , } = -2k , & \ { _ , _ } = -2 m , + \ { , _ } = -p _ , & \ { , _ } = -g _ , & \ { , } = -d . [ s2n1fermionic2 ] the generators @xmath30 are nilpotent , however , @xmath31 are not . nonvanishing bosonic - fermionic commutators are given by llll [ , d ] = , & = , & = , & = , + [ , g _ ] = _ , & = _ , & [ j , _ ] = _ . [ s2n1bs2 ] for there exist two distinct @xmath10 extensions , called _ standard _ and _ exotic_. the standard extension 22 has eight fermionic generators @xmath32 and additional bosonic @xmath25-parity operator . the fermionic sector is defined by the relations : lll \ { _ , _ } = - 2h , & \ { _ , _ } = - 2k , & \ { _ + + , _ } = -2 m , , + \ { _ + - , _ -+ } = -2 m , & \ { q _ , _ } = -p _ , & \ { _ , _ } = - g _ , + \ { _ , _ } = -d r , [ s2n2fermionic2 ] where @xmath33 nonvanishing bosonic - fermionic relations are listed below : llll [ _ , d ] = _ , & = _ , & = _ , & = _ + [ g _ , _ ] = - _ , & = - _ , & [ p _ , _ ] = _ , & = _ , + [ r , _ ] = _ , & = _ , & = _ , [ s2n2bs2 ] where @xmath34 the exotic extension has six fermionic generators @xmath35 and additional bosonic @xmath25-parity operator . the fermionic generators are subject to the relations : lll \ { _ , _ } = - 2h , & \ { _ , _ } = - 2k , & \ { _ , _ } = -m , + \ { _ , _ } = - p _ , & \ { _ , _ } = - g _ , & \ { _ , _ } = -d ( j + r ) , [ exotic - fermionic2 ] and those for the bosonic - fermionic sector are llll [ _ , d ] = _ , & = _ , & = _ , & = _ + [ _ , g _ ] = 2 _ , & = 2 _ , & [ j , _ ] = _ , & = _ , + [ r , _ ] = 2 _ , & & & [ exotic - bs2 ] where @xmath36 we remark that the @xmath25-parity operator for @xmath10 extensions also commute with all bosonic generators . the grading and triangular decomposition for introduced in @xcite are easily extended to the super schrdinger algebras discussed in this paper . we define the following degree for : & & = 2 , = = 1 , = = = 0 , + & & = = -1 , = -2 . [ degs11 ] it is immediate to see that is @xmath37-graded by this degree . according to the sign of the degree one may define the triangular decomposition of as follow : ( 1/1 ) & = & ( 1/1)^+ ( 1/1)^0 ( 1/1)^- + & = & \ { k , g } \ { d , m , } \ { p , } . [ s11tri ] appropriate definitions of degree for other algebras also enable us to define the triangular decomposition . below we give the decomposition . the algebras and 21 are @xmath38-graded : @xmath39 \mathfrak{s}(1/2)^0 & & d ( 0,0 ) , \ r ( 0,0 ) , \ m ( 0,0 ) \\[5pt ] \mathfrak{s}(1/2)^- & & h ( -2,0 ) , \ p ( -1,0 ) , \ \q_+ ( -1,1 ) , \ \q_-(-1,-1 ) , \ \x_- ( 0,-1 ) \\ \midrule \mathfrak{s}(2/1)^+ & \quad & k ( 2,0 ) , \ g_+ ( 1,1 ) , \ g_- ( 1,-1 ) , \ \s ( 1,0 ) , \ \x_+ ( 0,1 ) \\[5pt ] \mathfrak{s}(2/1)^0 & & d ( 0,0 ) , \ j ( 0 , 0 ) , \ m ( 0,0 ) \\[5pt ] \mathfrak{s}(2/1)^- & & h ( -2,0 ) , \ p_+ ( -1,1 ) , \ p_- ( -1,-1 ) , \ \q ( -1,0 ) , \ \x_- ( 0,-1 ) \\ \bottomrule \end{array}\ ] ] while the algebras 22 and are @xmath40-graded : @xmath41 & & \s_- ( 1,0,-1 ) , \ \x_{++ } ( 0,1,1 ) , \ \x_{+- } ( 0,1,-1 ) \\[5pt ] \mathfrak{s}(1/2)^0 & \quad & d ( 0,0,0 ) , \ j ( 0 , 0 , 0 ) , \ m ( 0,0,0 ) , \ r ( 0,0,0 ) \\[5pt ] \mathfrak{s}(1/2)^- & \quad & h ( -2,0,0 ) , \ p_+ ( -1,1,0 ) , \ p_- ( -1,-1,0 ) , \ \q_+ ( -1,0,1 ) \\[5pt ] & & \q_- ( -1,0,-1),\ \x_{-+ } ( 0,-1,1 ) , \ \x_{-- } ( 0,-1,-1 ) \\ \midrule \hat{\mathfrak{s}}(2/2)^+ & \quad & k ( 2,0,0 ) , \ g_+ ( 1,1,0 ) , \ g_- ( 1,-1,0 ) , \\[5pt ] & & \s_+ ( 1,-1,2 ) , \ \s_- ( 1,1,-2 ) , \ \x_+ ( 0,0,2 ) \\[5pt ] \hat{\mathfrak{s}}(1/2)^0 & \quad & d ( 0,0 , 0 ) , \ j ( 0 , 0 , 0 ) , \ m ( 0,0 , 0 ) , \ r ( 0,0,0 ) \\[5pt ] \hat{\mathfrak{s}}(1/2)^- & \quad & h ( -2,0,0 ) , \ p_+ ( -1,1,0 ) , \ p_- ( -1,-1,0 ) , \\[5pt ] & & \q_+ ( -1,-1,2 ) , \ \q_- ( -1,1,-2 ) , \ \x_- ( 0,0,-2 ) \\ \bottomrule \end{array}\ ] ] one can introduce an algebra anti - automorphism for the super schrdinger algebras . it is defined for the bosonic generators of by ( p ) = g , ( h ) = k , ( d ) = d , ( m ) = m , ( r ) = r , [ omega1-even ] and those for the algebras in @xmath1 dimension by ( p_a ) = g_-a , ( h ) = k , ( d ) = d , ( m ) = m , ( j ) = j , ( r ) = r. [ omega1-even2 ] the mapping of the fermionic elements of is given by ( ) = , ( ) = . [ omega1-odd1 ] all the fermionic elements of the other algebras are obey the same transformation rule together with all the signature of the suffices being changed , e.g. , @xmath42 the mapping is involutive : @xmath43 let @xmath44 be one of the superalgebras considered in this paper and let us denote its triangular decomposition by @xmath45 then one see that @xmath46 the algebras under consideration admit the triangular decomposition . this allows us to define the lowest weight modules for the algebras . the lowest weight vector @xmath47 is defined by x v_0 = 0 ^x ^- , x v_0 = ( x ) v_0 ^x ^0 , [ lwvdef ] where @xmath48 is an eigenvalue of @xmath49 the verma module over @xmath50 is defined by v^ = u(^+ ) v_0 , [ vmdef ] where @xmath51 is the enveloping algebra of @xmath52 reducibility of the verma modules may be investigated by singular vectors as in the cases of semisimple lie algebras and the bosonic schrdinger algebras @xcite . a singular vector @xmath53 is defined as a homogeneous element of @xmath54 such that @xmath55 and @xmath56 in this section we provide explicit formulae of the singular vectors and reducibility of the verma modules for _ massive _ case , that is , the generator @xmath57 has nonvanishing eigenvalues . here we give only the outline of the calculation . detailed proof for @xmath21 dimensional algebras is found in @xcite and for @xmath1 dimension will be published separately @xcite . we start with . the lowest weight condition ( [ lwvdef ] ) for yields & & v_0 = p v_0 = 0 , + & & d v_0 = -d v_0 , m v_0 = m v_0 , v_0 = v_0 , [ lwvs11 ] where @xmath58 is the conformal weight and the minus sign is for later convenience . the variable @xmath59 is of odd parity relating to the mass eigenvalue by the relation @xmath60 the verma module ( [ vmdef ] ) for is given by v^d = \ { g^k k^ v_0 , g^k k^ v_0 | k , _ 0 } . [ vds11 ] it is easy to see that the generator @xmath61 is diagonal on the basis given in ( [ vds11 ] ) . it follows that @xmath62 is decomposed into a direct sum of the subspaces @xmath63 spanned by the vectors @xmath64 satisfying @xmath65 the singular vector @xmath53 belongs to @xmath66 one may set v_s = _ k a_k v_k^(n ) , v_k^(n ) v_n^d , [ ansatzsv ] and impose the conditions v_s = p v_s = 0 . [ condsv ] this yields some relations for @xmath67 then by solving the relations one may determine the singular vectors up to overall constant . [ prop1 ] the verma module @xmath62 over has precisely one singular vector iff @xmath68 and it is given by v_s = ( g^2 - 2mk)^d+1/2 ( g-2 ) v_0 . [ svn1 ] when the verma module has singular vectors one find invariant subspaces constructed on the singular vector @xmath69 thus the module is reducible . to find irreducible modules one may consider the quotient module @xmath70 then seeks singular vectors in the quotient module . in the present case it turns out that there is no singular vector in the quotient module . therefore @xmath70 is irreducible . [ prop2 ] all irreducible lowest weight modules over are listed as follows : 1 . the verma module @xmath62 for @xmath71 2 . the quotient module @xmath70 for @xmath72 all irreducible modules given are infinite dimensional . we now turn to the superalgebra . the lowest weight vector @xmath47 is defined by & & _ v_0 = p v_0 = _ - v_0 = 0 , [ lws2 ] + & & d v_0 = -d v_0 , m v_0 = m v_0 , r v_0 = r v_0 . the verma modules over are given by v^d , r = \ { g^k k^ _ + ^a _ -^b _ + ^c v_0 | k , _ 0 , a , b , c \ { 0 , 1 } } . [ vms2 ] the same procedure as leads us to the following propositions : [ prop3 ] the verma module @xmath73 over has precisely one singular vector iff @xmath74 and it is given by & & v_s^p = ( g^2 - 2mk)^d-1/2 u_0 , + & & u_0 = ( g _ - _ + + m _ + _ - + 2mk ) v_0 + ( g^2 - 2mk ) v_0 . [ svn2 ] [ prop4 ] all irreducible lowest weight modules over are listed as follows : 1 . the verma module @xmath73 for @xmath75 2 . the quotient module @xmath76 for @xmath77 where @xmath78 is the invariant submodule constructed on the singular vector ( [ svn2 ] ) : @xmath79 all irreducible modules given are infinite dimensional . more involved in this case , however , one may use the same procedure as @xmath21 dimensional algebras to study the reducibility of the verma modules . we start with the superalgebra 21 . the lowest weight for 21 is defined by & & v_0 = p _ v_0 = _ - v_0 = 0 , + & & d v_0 = -d v_0 , j v_0 = -j v_0 , m v_0 = m v_0 . [ lws21 ] the verma modules are constructed on the lowest weight vector : v^d , j = \ { g_+^k g_-^h k^ ^a _ + ^b v_0 | k , h , _ 0 , a , b \ { 0 , 1 } } . [ vms21 ] the verma modules contain a singular vector for discrete values of @xmath80 [ prop5 ] the verma module @xmath81 over 21 has precisely one singular vector iff @xmath82 and it is given by v_s = ( g_+ g_- - 2mk)^d+1 ( g_- _ + - 2 m ) v_0 . [ sv21 ] it turns out that the factor modules by the invariant submodule constructed on @xmath83 do not contain any singular vectors . we thus have a classification of irreducible modules over 21 . [ prop6 ] all irreducible lowest weight modules over 21 are listed as follows : 1 . the verma module @xmath81 for @xmath84 2 . the quotient module @xmath85 for @xmath86 where @xmath78 is the invariant submodule constructed on the singular vector ( [ sv21 ] ) : @xmath87 all irreducible modules given are infinite dimensional . next we investigate the standard @xmath88 extension 22 . the lowest weight vector for 22 is defined by & & _ v_0 = _ -+ v_0 = _ v_0 = 0 , + & & d v_0 = -d v_0 , j v_0 = -j v_0 , r v_0 = r v_0 , m v_0 = m v_0 , [ lws22 ] and application of a element of @xmath89 on @xmath47 generates a basis of a verma module over 21 : v^d , j , r = \ { g_+^k g_-^h k^ _ + ^a_1 _ -^a_2 _ + + ^b_1 _ + -^b_2 v_0 | k , h , _ 0 , a_i , b_i \ { 0 , 1 } } . [ vms22 ] reducibility of the verma modules is similar to the other cases . we can show the following proposition on the existence of singular vectors . [ prop7 ] the verma module @xmath90 over 22 has precisely one singular vector iff @xmath91 and it is given by & & v_s = ( g_+ g_- - 2mk)^d ( g_- _ + - 2 m ) u_0 , + & & u_0 = \ { g_-^2 _ + + _ + - - 2 m g_- ( _ + _ + - - _ - _ + + ) + 4m^2 ( _ + _ - + k ) } v_0 . [ svs22 ] further search of singular vectors in the quotient modules conclude the following classification of irreducible modules : [ prop8 ] all irreducible lowest weight modules over 22 are listed as follows : 1 . the verma module @xmath90 for @xmath92 2 . the quotient module @xmath93 for @xmath94 where @xmath78 is the invariant submodule constructed on the singular vector ( [ svs22 ] ) : @xmath95 all irreducible modules given are infinite dimensional . we now turn to investigation of the exotic @xmath10 extension . the singular vectors and irreducible modules have been studied in @xcite . here we give a closed form expression of the singular vectors and more precise classification of irreducible modules . the lowest weight vector @xmath96 and the verma modules @xmath97 are defined as usual : & & _ v_0 = _ - v_0 = 0 , + & & d v_0 = -d v_0 , j v_0 = -j v_0 , r v_0 = 2r v_0 , m v_0 = m v_0 . [ lwexo ] v^d , j , r = \ { g_+^k g_-^h k^ _ + ^a _ -^b _ + ^c v_0 , | k , h , _ 0 , a , b , c \ { 0 , 1 } } . [ vmexo ] the classification of irreducible modules is summarized in the following two propositions . [ prop9 ] the verma module @xmath90 over has precisely one singular vector iff @xmath91 and @xmath98 it is given by & & v_s = ( g_+ g_- - 2mk)^d u_0 , + & & u_0 = ( g_- _ - _ + + m _ + _ - + 2 m k ) v_0 . [ svexo ] [ prop10 ] all irreducible lowest weight modules over are listed as follows : 1 . the verma module @xmath90 if @xmath92 nor @xmath99 2 . the quotient module @xmath93 if @xmath94 and @xmath100 where @xmath78 is the invariant submodule constructed on the singular vector ( [ svexo ] ) : @xmath101 all irreducible modules given are infinite dimensional . we investigate the lowest weight representations of the super schrdinger algebras in @xmath102 and @xmath27 dimensional spacetime with @xmath4 extensions . our main result is a classification of irreducible lowest weight modules for nonvanishing mass . this was done by the use of singular vectors . all irreducible modules are infinite dimensional . finite dimensional irreducible modules appear when the mass is set equal to zero @xcite . one may introduce a bilinear form analogous to the shapovalov form @xcite of the semisimple lie algebra to the verma modules . let @xmath44 be a super schrdinger algebra discussed in this paper and @xmath103 be a verma module over it . we define the bilinear form @xmath104 by the relations : ( x v_0 , y v_0 ) = ( v_0 , ( x ) y v_0 ) , ( v_0 , v_0 ) = 1 , x , y u(g ) [ shaform ] by the bilinear form one may define unitary representations of the super schrdinger algebras . it is also easy to see that if @xmath105 have different weight of the generator @xmath61 , then they are orthogonal with respect to this form : ( v_m , v_n ) = 0 . [ ortho ] it follows that a singular vector of @xmath106 is orthogonal to any other vectors in @xmath107 this is the same property as semisimple case . thus one may analyze the reducibility of the verma modules also via the bilinear form . one may use the singular vectors to obtain invariant partial differential equations . this is an analogy to the cases of semisimple lie algebras @xcite and the bosonic schrdinger algebras @xcite . in the latter case the obtained partial differential equations are a hierarchy of free schrdinger equations . to obtain the invariant equations we need a vector field representation of the algebra . vector field representations for and are found in @xcite . another link of the present work to physical problem is a a supersymmetric extension of the group theoretical approach to nonrelativistic holography discussed in @xcite . it may also require vector field representations of the super schrdinger algebras . we restrict ourselves to the super schrdinger algebras in this work . however there exist other algebras which may be regarded as nonrelativistic analogue of conformal algebras @xcite ( see also @xcite ) and their supersymmetric extensions @xcite . physical importance of such algebras has been recognized widely @xcite , however , representation theory of such algebras are far from completion . it is an important issue to develop representation theory for the algebras along the line of the present work . we announce that it has been done for one of the so - called conformal galilei algebras in @xcite .

we investigate the lowest weight representations of the super schrdinger algebras introduced by duval and horvthy . this is done by the same procedure as the semisimple lie algebras . namely , all singular vectors within the verma modules are constructed explicitly then irreducibility of the associated quotient modules is studied again by the use of singular vectors . we present the classification of irreducible verma modules for the super schrdinger algebras in @xmath0 and @xmath1 dimensional spacetime with @xmath2 extensions .

despite the fact that a fundamental description of _ m_-theory has so far remained elusive , it is nevertheless possible to describe interesting and predictive aspects of its effective phenomenology . this is possible because , whatever _ m_-theory turns out to be , it should relate at low energy to eleven - dimensional supergravity . this statement is actually quite powerful , especially when eleven - dimensional spacetime has a topology involving a compact orbifold factor , owing to rigorous constraints derivable from requirements imposed by field theory gauge and gravitational anomaly cancellation . there has been quite a lot of recent interest in @xmath2-theory on @xmath3 holonomy seven - manifolds for the construction of @xmath0 supersymmetric theories in four dimensions @xcite . in this paper we describe , in microscopic detail , a particular @xmath0 model associated with a particularly interesting _ m_-theory orbifold . although our model involves compactification on a seven - manifold , it has the structure of a @xmath4 orbifold ( admitting a calabi - yau resolution , @xcite ) times a closed interval @xmath5 . such an orbifold with boundary " falls outside of the class of @xmath3-resolvable orbifolds of @xmath6 studied by joyce @xcite . nevertheless , by compactification on this orbifold we do obtain a four - dimensional , @xmath0 , chiral super yang - mills theory from eleven - dimensional supergravity via explicit cancellation of anomalies . in our analysis , we impose strict anomaly cancelation at each point in the eleven - dimensional spacetime . this is a substantially more restrictive criterion than that implied by anomaly cancellation on smaller spaces obtained when compact dimensions shrink to zero size . the latter circumstance accesses only what we call the collective anomaly , whereas our approach involves a more microscopic " picture of the localized states . admittedly , in our approach we are able to compute only those chiral states needed to cancel anomalies . any additional localized states which can be added without introducing additional anomalies are invisible to our analytic probe . typically , this redundancy is of very limited scope , however . in this paper we describe a consistent microscopic description of the localized states in one particular orbifold . furthermore , as explained in @xcite , one expects a hierachy of consistent solutions for the gauge group and representation content associated with a given orbifold compactification of _ m_-theory . typically , sets of such consistent solutions are linked by phase transitions , often mediated by fivebranes and small instanton transformations . in this paper we discuss only one particular solution ; we fully expect that this solution describes only one corner of a more robust and interesting moduli space . having said this , we remark that the particular _ m_-theory orbifold analyzed in this paper had been previously mentioned in @xcite as an interesting n=1 model , where it appeared as model ( c,c ) . however , in that paper no attempt was made to describe the associated spectrum from a microscopic point of view . the fact that the gauge group described in that paper differs from ours is not particulaly troubling either , since we are describing a different corner of moduli space . it would be an interesting exercise to provide a microscopic description of the models described in @xcite . to the best of our knowledge this current paper is the only extant microscopic description of a @xmath7 @xmath0 model derived from _ m_-theory . the reason why anomaly cancellation is important in the context of _ m_-theory orbifolds is that the the lift of the action of the orbifold quotient group to the gravitino field generically serves to project that field chirally onto even - dimensional fixed - point loci . on fixed - planes of dimensionality ten or six this projection induces gravitational anomalies , owing to the chiral coupling of the gravitino to currents which are classically conserved due to classical reparameterization invariance of the fixed - planes . however , since all local anomalies must cancel , the presence of gravitino - induced fixed - plane anomalies allows one to infer additional structure , such as yang - mills supermultiplets living on the fixed - planes , or specialized electric and magnetic sources of @xmath8 flux , is the four - form field strength living in the bulk supergravity multiplet . ] since these supply necessary contributions to the overall anomaly , either quantum mechanically or as inflow " , so as to render the theory consistent . in generic situations orbifold fixed - point loci can be complicated , involving fixed - planes of various dimensionalities which can intersect . as a result there are additional concerns owing to gauge anomalies and mixed anomalies induced by chiral projection of the gaugino fields in the yang - mills supermultiplets onto fixed - plane intersections . because of this , the cancellation of all anomalies typically involves an elaborate conspiracy of quantum contributions and inflow contributions . in a previous series of papers @xcite , much of the technology needed for implementing anomaly matching in orbifolds with intersecting fixed - planes was developed . complementary aspects and several physical observations about these orbifolds were also addresed by other authors , @xcite and @xcite in particular . this work extended the ideas and technology implemented in simpler orbifolds involving only isolated ( i.e. non - intersecting ) fixed - planes described by hoava and witten @xcite and by dasgupta and mukhi @xcite . until now , the only orbifolds with intersecting fixed - planes which have been analyzed are those corresponding to topologies @xmath9 in which the @xmath10 factor degenerates to a global orbifold @xmath11 , for the four possible cases @xmath12 and @xmath13 . the effective theory in these previously studied cases , obtained in the limit that the radii of the compact dimensions becomes very small , are uniformly six - dimensional . in this paper we describe a new example of an _ m_-theory orbifold which has a four - dimensional effective description , and also has four dimensional fixed - planes . this model exhibits a pretty feature in that each four - dimensional fixed - plane lies at the mutual intersection of three orthogonal six - dimensional fixed - planes , each of which is a sub - manifold of a ten - dimensional fixed - plane . what is nice about this feature is that the constraints imposed by ten- and six - dimensional gravitational anomaly cancellation impinge directly on the structure of the effective field theory in four dimensions , despite the fact that there are no gravitational anomalies specifically in four dimensions . this is possible because the four - planes in question are very special sub - manifolds of the fixed ten - planes and also of the fixed six - planes . this introduces gravitational anomalies into four dimensional physics in a novel manner . thus , despite the fact that the model which we present is not of immediate phenomenological interest , it does indroduce a powerful formalism for deriving four - dimensional physics from _ m_-theory . in our model , eleven - dimensional spacetime has topology @xmath14 . this orbifold is of the hoava - witten variety , since it includes @xmath5 as a factor , and has quotient group @xmath15 . since the orbifold is of the hoava - witten variety , in order to cancel the ten - dimensional anomaly , the fixed ten - planes , of which there are two , each support @xmath16 yang - mills supermultiplets . in this case , however , there are additional gravitational anomalies induced on the six - planes . in order to cancel these , it is necessary to introduce hypermultiplets living on these six - planes . furthermore , it is necessary that the ten - dimensional @xmath16 gauge group is broken to a subgroup @xmath17 on the six - dimensional fixed - plane corresponding to the element @xmath18 of @xmath15 . this symmetry breakdown is codified by the action of the quotient group on the @xmath16 root lattice and is , in effect , a description of a small @xmath16 gauge instanton which is localized on the fixed - plane . in our model , the cancellation of anomalies on the ten - dimensional fixed - planes and also on the six - dimensional fixed - planes proceeds exactly as described in @xcite for the case of the @xmath19 compactification . this is because these planes are locally identical to the analogs in that simpler construction . the novel feature of the @xmath15 model , however , derives from the fact that the six - planes intersect each other at four - planes . as a result of this , there are important consistency requirements which control the ultimate breakdown patterns of @xmath16 as one approaches first a six - plane and then moves along that six plane and lands on the four plane intersection . in this paper , we present an explicit consistency analysis which enables us to compute the complete set of twisted states and the gauge group localized on the four - dimensional fixed - planes . we do not review the hoava - witten analysis @xcite which explains the ten - dimensional anomaly cancellation nor do we review the cancellation of the six - dimensional anomalies . the interested reader is referred to @xcite for a comprehensive description of these cases . section 2 addresses the global geometric aspects of our model , describing the explicit action of @xmath15 which gives rise to our orbifold of @xmath6 . in the next section , the analysis of the local anomaly for the @xmath20 orbifold in @xcite is extended to this case . although the story for the ten - planes is quite analogous , the six - planes require more subtle methods . for this reason we introduce `` branching tables '' and `` embedding diagrams '' for determining which projections in the @xmath16 root lattice are compatible with the orbifold quotient group action . in sections 4 and 5 we use this data to determine the spectrum seen by the four - dimensional intersection which arises from the ten - dimensional @xmath16 fields , and discuss further twisted states which we need to introduce to cancel the six - dimensional anomalies . finally , following a synopsis , we indicate why the four - dimensional gauge anomaly does not arise for our orbifold , and summarize the representation content of the chiral multiplets in our model ( `` model 1 '' ) in table 7 . further models with @xmath7 and @xmath0 susy , based on both abelian and non - abelian orbifolds , will be discussed in forthcoming work . consider a spacetime with topology @xmath21 , where the compact @xmath6 factor is described by the quotient @xmath22 with lattice @xmath23 . parameterize the compact dimensions using three complex coordinates @xmath24 and one real coordinate @xmath25 . the orbifold which defines our model is obtained from this torus by making additional identifications described by parity flips as shown in table [ modone ] . the sole condition on the lattice @xmath23 in @xmath26 is that these parity flips induce lattice automorphisms . a minus sign in that table implies a relative overall sign change of the indicated coordinate ( the column header ) by the indicated element ( the row header ) . each row in table [ modone ] describes a generator of the full quotient group , which is @xmath15 . .the action of the quotient group @xmath15 on the compact coordinates @xmath27 corresponding to the model described in the text . [ cols="^,^,^,^,^ " , ] + in this paper , we have shown explicitly how a four dimensional @xmath0 yang - mills theory can be determined from anomaly matching on the fixed - planes of an _ . one interesting aspect of this analysis is the manner in which constraints from gravitational anomalies impinge on the four dimensional spectrum , despite the fact that there are no gravitational anomalies in purely four dimensional field theories . in our on - going work we are developing a systematic scan of all possible orbifolds obtained as quotients @xmath28 for each possible lattice @xmath23 and for each possible choice of quotient group @xmath29 . for a given orbifold constructed in this way we select those which have supercharges preserved on the fixed - planes , and then ascertain the fixed - plane twisted spectra needed to cancel all local anomalies . the more interesting cases involve non - abelian quotients . the orbifold described in this paper is the abelian orbifold of smallest possible group order yielding @xmath0 susy in four dimensions . one purpose of this paper has been to present a context for some of the rudiments of the larger algorithm which we are implementing on larger class of orbifolds , in the hopes of finding a phenomenologically compelling effective field theory limit of _ m_-theory . + m.f . would like to thank dieter l " ust for warm hospitality at humboldt university where a portion of this manuscript was prepared , and also the organizers of the workshop _ dualities : a math / physics collaboration _ , itp , santa barbara . 99 b.s.acharya , _ on realising n=1 super yang - mills in _ m _ theory _ , hep - th/0011089 . m.atiyah and e.witten , _ _ m_-theory dynamics on a manifold of @xmath3 holonomy _ , hep - th/0107177 . d.joyce , _ on the topology of desingularizations of calabi - yau orbifolds _ , math.ag/9806146 . r.gopakumar and s.mukhi , _ orbifold and orientifold compactifications of f - theory and m - theory to six and four dimensions _ , hep - th/960705 . m.faux , d.lst and b.a.ovrut , _ intersecting orbifold planes and local anomaly cancellation in _ m_-theory _ , nucl.phys . * b*554 ( 1999 ) 437 - 483 , hep - th/9903028 . m.faux , d.lst and b.a.ovrut , _ local anomaly cancellation , _ m_-theory orbifolds and phase - transitions _ , hep - th/0005251 . m.faux , d.lst and b.a.ovrut , _ an @xmath2-theory perspective on heterotic @xmath10 orbifold compactifications _ , hep - th/0010087 . , m. faux , d.lust , b.a . ovrut , hep - th/0011031 . v. kaplunovsky , j. sonnenschein , s. theisen , s. yankielowicz , _ on the duality between perturbative heterotic orbifolds and m - theory on @xmath30 _ , hep - th/9912144 . adel bilal , jean - pierre derendinger , roger sauser , _ m - theory on @xmath31 : new facts from a careful analysis _ , hep - th/9912150 . p.hoava and e.witten , _ heterotic and type i string dynamics from eleven dimensions _ , nucl.phys . * b*475 ( 1996 ) 94 - 114 , hep - th/9510209 . p.hoava and e.witten , _ eleven - dimensional supergravity on a manifold with boundary _ , nucl.phys . * b*460 ( 1996 ) 506 - 524 , hep - th/9603142 . k.dasgupta and s.mukhi , _ orbifolds of _ m_-theory _ , nucl.phys . * b*465 ( 1996 ) 399 - 412 , hep - th/9512196 . r.slansky , _ group theory for unified model building _ , phys.rep . 79 ( 1981 ) 1 - 128 . w.g.mckay and j.patera , tables of dimensions , indices , and branching rules for representations of simple lie algebras , marcel dekker , inc . , 1981 .

gravitational and gauge anomalies provide stringent constraints on which subset of chiral models can effectively describe _ m_-theory at low energy . in this paper , we explicitly construct an abelian orbifold of _ m_-theory to obtain an @xmath0 , chiral super yang - mills theory in four dimensions , using anomaly matching to determine the entire gauge and representation structure . the model described in this paper is the simplest four dimensional model which one can construct from _ m_-theory compactified on an abelian orbifold without freely - acting involutions . the gauge group is @xmath1 .

CLOSE Democratic Sen. Dick Durbin says he personally heard President Donald Trump use "vile and racist" remarks during an immigration meeting with lawmakers. USA TODAY President Trump (Photo: Evan Vucci, AP) WASHINGTON – Facing a global and congressional firestorm of criticism, President Trump appeared Friday to deny using a vulgar term to describe Haiti, El Salvador and African countries, and instead sought to redirect the focus on what he called unacceptable Democratic proposals on immigration. "The language used by me at the DACA meeting was tough, but this was not the language used," Trump tweeted. "What was really tough was the outlandish proposal made - a big setback for DACA!" The language used by me at the DACA meeting was tough, but this was not the language used. What was really tough was the outlandish proposal made - a big setback for DACA! — Donald J. Trump (@realDonaldTrump) January 12, 2018 Trump ignored questions about the incident during a White House event on Friday: A proclamation to honor the Dr. Martin Luther King, Jr. holiday, which comes on Monday, and used the opportunity to speak about diversity and equality. "No matter what the color of our skin or the place of our birth, we are all created equal," Trump said. More: 5 other times President Trump's remarks sparked controversy over race More: ‘Sh**hole countries,’ UN respond to Trump's ‘Sh**hole countries’ comments The attempt to clarify came after The Washington Post reported that Trump questioned in a meeting with lawmakers on Thursday why the U.S. would accept immigrants from "shithole countries" like Haiti or in Africa rather than in places like Norway. Trump had met the previous day with the prime minister of Norway. "Why are we having all these people from shithole countries come here?" Trump reportedly told lawmakers during negotiations over DACA: Deferred Action for Childhood Arrivals, a program designed to block deportation of young people brought to the United States illegally by their parents. In a subsequent tweet, Trump denied saying anything derogatory of Haiti in particular. "Never said anything derogatory about Haitians other than Haiti is, obviously, a very poor and troubled country," he said, and suggested he would record future meetings. Never said anything derogatory about Haitians other than Haiti is, obviously, a very poor and troubled country. Never said “take them out.” Made up by Dems. I have a wonderful relationship with Haitians. Probably should record future meetings - unfortunately, no trust! — Donald J. Trump (@realDonaldTrump) January 12, 2018 Trump has threatened to kill the DACA program unless Democrats agree to a host of new security measures designed to block illegal immigration, including a wall along the U.S.-Mexico border. More: Report: Trump uses crude term while attacking protections for immigrants More: 'Divisive,' 'elitist,' 'racist': Reactions to Trump's immigration comments Yet upcoming negotiations between the White House and Congress on immigration are likely to be shadowed by the reported presidential comments, which some lawmakers and human rights officials denounced as racist. "The President’s statement is shameful, abhorrent, unpresidental, and deserves our strongest condemnation," said Michelle Lujan Grisham, D-N.M., chair of the Congressional Hispanic Caucus. "We must use our voices to ensure that our nation never returns to the days when ignorance, prejudice, and racism dictated our decision making." Rep. Mia Love, R-Utah, a daughter of Haitian immigrants, demanded Trump apologize, calling his comments "unkind, divisive, (and) elitist," and that they "fly in the face of our nation’s values." The government of Haiti has demanded that U.S. officials provide an explanation of the president's remarks, and the government of El Salvador lodged a protest. "El Salvador demands respect for the dignity of its noble and brave people," it said in a statement. Rupert Colville, a human rights spokesman for the United Nations, said: "If confirmed, these are shocking and shameful comments from the president of the United States, I'm sorry but there is no other word for this but racist." During his Friday tweet storm, Trump also rejected a bipartisan congressional proposal on DACA, saying it lacked funding for the U.S.-Mexico wall and did not end programs like "chain migration." The president's criticism came a day after discussing immigration ideas with a bipartisan delegation that included Sens. Dick Durbin, D-Ill., and Lindsey Graham, R-S.C. While some Republicans supported various compromise proposals, Trump put the blame on Democrats. Saying he wanted a "merit based" immigration system that blocks drug dealers and criminals, Trump said the bipartisan proposal would somehow force the United States to "take large numbers of people from high crime countries which are doing badly." The so-called bipartisan DACA deal presented yesterday to myself and a group of Republican Senators and Congressmen was a big step backwards. Wall was not properly funded, Chain & Lottery were made worse and USA would be forced to take large numbers of people from high crime..... — Donald J. Trump (@realDonaldTrump) January 12, 2018 ....countries which are doing badly. I want a merit based system of immigration and people who will help take our country to the next level. I want safety and security for our people. I want to stop the massive inflow of drugs. I want to fund our military, not do a Dem defund.... — Donald J. Trump (@realDonaldTrump) January 12, 2018 Democrats said Trump's goal, reflected in his alleged comment, is to allow immigration from predominantly white countries and block it from predominately black and brown countries. "He is making it very clear that it is LEGAL immigration he opposes if the people look a certain way or come from certain countries (like countries that are not Norway)," tweeted Rep. Luis V. Gutierrez, D-Ill. Some congressional Democrats have threatened to block a new government spending plan unless the DACA program for young people is addressed, risking a government shutdown that also drew Trump's ire. "Sadly, Democrats want to stop paying our troops and government workers in order to give a sweetheart deal, not a fair deal, for DACA," Trump tweeted. "Take care of our Military, and our Country, FIRST!" If it happens, a government shutdown would not cut off funding for troops or military operations; only non-essential personnel would be affected. Some Republicans implicitly rebuked Trump, while others stayed largely silent. Sen. Marco Rubio, R-Fla., tweeted out a series of contributions to America made by people of Haitian descent, from doctors and lawmakers to University of Georgia star football running back Sony Michel. In one post, Rubio tweeted out a Bible verse: "Slander no one ... be peaceable, considerate, exercising all graciousness toward everyone Titus 3 1-2." Sen. Jeff Flake, a Republican from Arizona who is leaving the Senate after this year, was more direct concerning Trump: "The words used by the President, as related to me directly following the meeting by those in attendance, were not 'tough,' they were abhorrent and repulsive." CLOSE President Trump is denying a report he used the word 'shithole' to describe African countries and Haiti. Nathan Rousseau Smith (@FantasticMrNate) has his statement. Buzz60 Read or Share this story: https://usat.ly/2mltdH3 ||||| Assistant Columbia bureau chief Adcox returned to The Post and Courier in October 2017 after 12 years covering the Statehouse for The Associated Press. She previously covered education for The P&C.; She has also worked for The AP in Albany, N.Y., and for The Herald in Rock Hill.

– President Trump honored the memory of Martin Luther King Jr. during a White House event on Friday with a strong statement: "No matter what the color of our skin or the place of our birth, we are all created equal." But as USA Today notes, headlines about Trump using the term "shithole countries" about certain nations during an immigration meeting threatened to overshadow the moment. The president ignored questions about the incident during the event, but there were plenty of other developments: To clarify: Jake Tapper of CNN reports that Trump referred to African nations as "shithole countries" but did not use the term about Haiti. Trump did, however, ask, "Why do we need more Haitians?" and asked that they be taken out of any immigration deal. The two different Trump remarks have been conflated a bit, perhaps explaining why Trump specifically denied saying anything "derogatory" about Haiti. Senator's view: Tim Scott of South Carolina, the lone black Republican in the Senate, says he spoke to Sen. Lindsey Graham, who attended the meeting, and Graham told him the "shithole countries" stories are "basically accurate," reports the Post and Courier. If so, that's "incredibly disappointing," says Scott, adding that America's strength is the "ability to weave together multiple communities for one nation." (Democrat Dick Durbin also confirmed that Trump used the term.)

in the present study we have analyzed the degradome of wt ( col and ler ) and tsn1tsn2 arabidopsis seedlings under specific ( control or stress ) conditions . to this end , plants were grown vertically on ms agar plates under a 16/8-h light / dark cycle and a light intensity of 150 e m s for 5 days . for heat stress , plates with 5-day - old seedlings were incubated for 40 min on a thermoblock at 39 c . for control condition , 5-day - old plants were directly harvested from the plate . finally , root tissue was collected and used to purify uncapped and total mrnas . total mrna was isolated using rneasy mini kit ( qiagen ) following the manufacturer 's instructions . uncapped mrna purification was performed as previously described , using a method based on the rna ligase - mediated 5 rapid amplification of cdna ends ( rlm 5-race ) , . briefly , t4 rna ligase ( ambion ) was used to add an rna adaptor to poly(a ) rna having a free 5 monophosphate ( uncapped mrnas ) . this adaptor was subsequently used for affinity purification and selective double - strand cdna synthesis from uncapped mrnas ( dsdna - uncapped ) . all rna samples used in this study were subjected to a quality control analysis . to this end , an electrophoretic analysis via the 2100 bioanalyzer ( agilent technologies ) and photometrical measurement with the nanodrop 2000 spectrophotometer ( thermo scientific ) were performed for determination of the rna integrity number ( rin ) and detection of potential contaminants . the dsdna - uncapped along with total mrna samples were sent to oaklabs ( germany ) , where total mrna samples were reverse transcribed and the second strand cdna ( dsdna - total ) was synthesized using agilent 's liqa kit . both dsdna - uncapped and dsdna - total were used to synthetize fluorescent crna ( complementary rna ) by in vitro transcription . subsequently the crna samples were labeled using cyanine 3-ctp ( cy-3 ) dye and hybridized on arabidopsis arrayxs thaliana chips ( http://www.oak-labs.com/ ) following the manufacturer 's protocol . fluorescence signals on microarray were detected by using the surescan microarray scanner ( agilent technologies ) , which results in the raw data output ( provided as txt files within gsm1551500 - 23 ) . briefly , the mean signal of each target was ranked relative to all other targets . so the highest value in all samples became the mean of the highest , the second highest value became the mean of the second highest values , and so on . in the present study we have analyzed the degradome of wt ( col and ler ) and tsn1tsn2 arabidopsis seedlings under specific ( control or stress ) conditions . to this end , plants were grown vertically on ms agar plates under a 16/8-h light / dark cycle and a light intensity of 150 e m s for 5 days . for heat stress , plates with 5-day - old seedlings were incubated for 40 min on a thermoblock at 39 c . for control condition , 5-day - old plants were directly harvested from the plate . finally , root tissue was collected and used to purify uncapped and total mrnas . total mrna was isolated using rneasy mini kit ( qiagen ) following the manufacturer 's instructions . uncapped mrna purification was performed as previously described , using a method based on the rna ligase - mediated 5 rapid amplification of cdna ends ( rlm 5-race ) , . briefly , t4 rna ligase ( ambion ) was used to add an rna adaptor to poly(a ) rna having a free 5 monophosphate ( uncapped mrnas ) . this adaptor was subsequently used for affinity purification and selective double - strand cdna synthesis from uncapped mrnas ( dsdna - uncapped ) . all rna samples used in this study were subjected to a quality control analysis . to this end , an electrophoretic analysis via the 2100 bioanalyzer ( agilent technologies ) and photometrical measurement with the nanodrop 2000 spectrophotometer ( thermo scientific ) were performed for determination of the rna integrity number ( rin ) and detection of potential contaminants . the dsdna - uncapped along with total mrna samples were sent to oaklabs ( germany ) , where total mrna samples were reverse transcribed and the second strand cdna ( dsdna - total ) was synthesized using agilent 's liqa kit . both dsdna - uncapped and dsdna - total were used to synthetize fluorescent crna ( complementary rna ) by in vitro transcription . subsequently the crna samples were labeled using cyanine 3-ctp ( cy-3 ) dye and hybridized on arabidopsis arrayxs thaliana chips ( http://www.oak-labs.com/ ) following the manufacturer 's protocol . fluorescence signals on microarray were detected by using the surescan microarray scanner ( agilent technologies ) , which results in the raw data output ( provided as txt files within gsm1551500 - 23 ) . briefly , the mean signal of each target was ranked relative to all other targets . so the highest value in all samples became the mean of the highest , the second highest value became the mean of the second highest values , and so on . this study provides a complete view of uncapping - mediated mrna degradation under control and heat stress condition in wt ( col and ler ) and tsn1tsn2 plants . notably , our results analyze the mrna degradome after pb and sg appearance in order to figure out whether mrnas are selectively decapped in these cytoplasmic mrnp complexes . these dataset has been used in a study that shows the importance of tsn presence in mrna catabolism . in this work , the abundance of uncapped mrnas was compared with the levels of the corresponding total ( uncapped and capped ) mrnas . this analysis furnished lists of transcripts that were either enriched or depleted in uncapped from in the individual genetic backgrounds .

recently , we have showed that tudor staphylococcal nuclease ( tsn or tudor - sn ) proteins ( tsn1 and tsn2 ) are localized in cytoplasmic messenger ribonucleoprotein ( mrnp ) complexes called stress granules ( sg ) and processing bodies ( pb ) under heat stress in arabidopsis . one of the primary functions of these mrnp complexes is mrna decay , which generates uncapped mrnas by the action of endonucleases and decapping enzymes ( thomas et al . , 2011 ) [ 1 ] . in order to figure out whether tsn proteins could be implicated in mrna decay , we isolated uncapped and total mrnas of wild type ( wt ; col and ler ) and tsn double knock - out ( tsn1tsn2 ) seedlings grown under heat stress ( 39 c for 40 min ) and control ( 23 c ) conditions . here , we provide the experimental procedure to reproduce the results ( ncbi geo accession number gse63522 ) published by gutierrez - beltran et al . ( 2015 ) in the plant cell [ 2 ] .

the topology of a space - time manifold @xmath4 can have important implications for the construction of classical and quantum fields . to see the physical effects of topology , one could relax the curvature effects by studying quantized fields in multiply connected _ flat _ space - times . field theory in space - times carrying a non - trivial fundamental group ( authomorphic fields ) has been studied previously through different approaches [ 1 - 4 ] . the effect of of mass is studied for scalar fields in the context of casimir energy in toroidal space - times [ 5 ] . the effects of multiple connectedness of the space - time manifolds for massless fields in various topological spaces are studied by dewitt , hart and isham [ 4 ] . following their work , tanaka and hiscock [ 6 ] evaluated vacuum expectation value of the stress tensor @xmath5 for free massive scalar fields in four dimensional space - time manifolds of the type @xmath6 . + in what follows we extend the above studies to the case of free massive spinor fields . the minkowski vacuum state is assumed to be the natural vacuum in all space - times considered . we shall describe the expectation value of the stress tensor @xmath7 in this vacuum state and in case there is no global timelike killing vector field , as in misner space - time , we will discuss how the default vacuum state could be taken to be that of the minkowski space - time [ 7 ] . + misner space has closed timelike curves ( ctcs ) in bounded regions ( nonchronal regions ) of the space - time which are separated from the ctc free regions ( chronal regions ) by a special type of cauchy horizon the so called _ chronology horizon _ , the null surface beyond which ctcs first form . it is believed that nature will not allow the formation of ctcs and this is embodied in hawking s `` chronology protection conjecture : the laws of physics do not allow the appearance of closed timelike curves '' [ 8 ] . the main impediment found to the appearance of such curves is the divergence of the vacuum stress - energy tensor of the quantized fields on the chronology horizon . it is believed that the gravitational backreaction to these diverging stress - energy tensor would alter the space - time in such a way as to prevent the formation of ctcs . in previous studies [ 6 - 13 ] , it has been shown that the divergence of @xmath5 for massless scalar fields on various space - times with chronology horizons can not be generally avoided . here we will show that the same thing is true for massive spinor field on misner space . + the outline of the paper is as follows : in section ii we review the spin structure in curved space - times . a general procedure for calculating the vacuum expectation value of @xmath7 for a free massive spinor field in a flat multiply connected space - time is described in section iii . we apply this method to orientable and non - orientable space - times with different spin structures in section iv . the vacuum stress - energy tensor for massive spinor fields and their massless limit in misner space are discussed in section v. conclusions will be discussed in the last section . to define a spinor field on a manifold @xmath4 , it must be equipped with a riemannian ( or pseudo riemannian ) metric , together with a bundle of orthonormal frames @xmath8 over the patches @xmath9 which are employed giving the bundle a lorentzian structure group . in an overlap we shall assume @xmath10 , where @xmath11 , @xmath12 is the transition function , @xmath13 in which @xmath14 is the lorentz transformation which preserves the direction of time . the transition functions @xmath15 certainly satisfy the consistency condition @xmath16 a spin structure on a lorentzian 4-manifold @xmath17 is defined by the transition function @xmath18 such that @xmath19 , where @xmath20 is the double covering of the lorentz group . because of the ambiguity in choosing any of the two coverings @xmath21 , it is not clear that @xmath22 can be chosen consistently to satisfy the consistency conditions ( 1 ) as @xmath15 does . if this can be done , the structure group of the tangent bundle of @xmath17 is said to be _ lifted _ from the lorentz group to the @xmath23 group and @xmath17 is equipped with a spin structure . choosing different frames @xmath24 in @xmath25 could in principle lead to different spin structures . to see this , suppose that @xmath26 is in a patch @xmath25 covered by a lorentzian frame field @xmath24 . if we take the frame @xmath27 and transport it around any closed curve @xmath28 , @xmath29 lying in @xmath25 , on returning to the same frame @xmath30 we can compare @xmath31 with @xmath32 as follows : identify all frames @xmath24 at points of @xmath25 with the single frame @xmath24 at @xmath26 . then by comparing @xmath31 with @xmath33 we find @xmath34 , in other words we have traced out a closed curve @xmath35 in lorentz group . if @xmath17 has a spin structure , i.e @xmath23 is its tangent bundle structure group , and we transport a frame @xmath36 around any closed path @xmath37 in @xmath17 , upon returning to the same lorentzian frame we can decide whether the frame has made an even or an odd number of complete rotations!. this is so , because by considering the @xmath23 frame bundle to @xmath17 , the curve @xmath37 in @xmath17 is covered by a unique curve in this frame bundle starting at @xmath38 , defined by @xmath36 . upon returning to the starting point of @xmath37 , the lifted curve will return to its starting point , corresponding to an even number of rotations , or to a point in the frame bundle related to the initial point by @xmath39 , corresponding to an odd number of rotations [ 14 ] . + not all manifolds admit spin structure . in fact the necessary and sufficient condition for the existence of such a structure is the topological restriction that the second stiffel - whitney class of @xmath4 , @xmath40 , vanishes [ 4,14 ] . if @xmath4 has a spin structute , the dirac spinor bundle is simply the vector bundle associated with the @xmath23 tangent bundle through the @xmath41 representation @xmath42 of @xmath23 , @xmath43\eqno(2)\ ] ] this spinor bundle is the bundle whose cross sections @xmath44 are known as spinor fields ( wave functions ) . as @xmath23 spin frame bundle is trivial , existence of different spin structures does not lead automatically to twisted spinor fields . instead this fact reflects itself in the different spin connections _ pulled back _ by the different maps @xmath45 to give a connection @xmath46 on @xmath47 tangent bundle , where @xmath48 is the connection form for the lorentzian tangent bundle . the associated connection in spinor bundle is given by @xmath49 , which is employed to construct covariant derivative of spinor fields in the spinor bundle . it is also shown that the lagrangian associated with different spin structures can not be made equal by a spinor field gauge transformation and lead to different physical results [ 4 ] . in a curved space , the action and stress - energy for a free spinor field @xmath44 are given by ; , we assume the spinor field to be neutral and represented by a majorana spinor . ] @xmath50 = { i\over 2}\int g^{1/2}(\bar{\psi}\gamma^\rho \psi_{;\rho } - \bar{\psi}_{;\rho}\gamma^\rho\psi -m\bar{\psi}\psi ) d^4 x \eqno(3)\ ] ] and @xmath51\eqno(4)\ ] ] the latter of which could be written in the following form , @xmath52 - \gamma^{(\mu}\left[{\psi},\bar { \psi}^{;\nu ) } \right])\eqno(5)\ ] ] where @xmath53 and trace is over the suppressed spinor indices . the transition from classical to quantum fields is made by replacing the classical fields by field operators . these quantities diverge when their vacuum expectation values are taken . to obtain the finite , physical contribution to @xmath5 , we employ the manifestly covariant _ point separation _ regularization method [ 15 - 16 ] . based on schwinger s proper time technique , this method gives equivalent results to other methods such as the dimensional and zeta - function regularization schemes . each term in ( 5 ) is constructed out of products of either field operators or their derivatives at _ the same space - time point_. taking this to be the prime source of divergent terms , the calculations in this method are done by first moving one operator in each product to a nearby point and then let them to coincide at the end . in other words , we split the point @xmath54 into @xmath54 and @xmath55 and take the coincidence limit @xmath56 , e.g. for a typical commutation relation in ( 5 ) we have , @xmath57 = \lim_{\tilde{x}\rightarrow x}{1\over 2 } \left\ { \left[\psi^{;\nu^\prime},\bar{\psi}\right ] + \left[\psi^{;\nu},\bar{\psi}\right ] \right\}\eqno(6)\ ] ] the primed derivatives are taken with respect to @xmath55 . expressing the point - separated @xmath5 in terms of the so called spinor hadamard elementary functions , @xmath58|0 > \eqno(7)\ ] ] we find @xmath59 the spinor hadamard function , on the other hand , could be written in terms of the scalar hadamard function as @xmath60 in which @xmath61 satisfies @xmath62 . therefore , ( 8) takes the following new form , @xmath63 @xmath64 \gamma^\sigma \nabla_\sigma g^{(1)}(x,\tilde{x } ) \eqno(10)\ ] ] the hadamard function for a massive scalar field in minkowski space could be written as a function of the half squared geodesic distance , @xmath65 , between two points @xmath54 and @xmath55 in the form of [ 17 ] , @xmath66 where @xmath67 is a step function and @xmath68 and @xmath69 are the modified bessel functions of the first and second kind respectively . since the space - times we are going to consider are flat multiply connected , each could be constructed by a topological identification out of minkowski space with metric given by @xmath70 consequently field theory in them could be built up from field theory in minkowski space - time by using the method of images . in this method , all inequivalent spacelike paths connecting two point @xmath54 and @xmath55 are taken into account , for they can not be deformed continuously to each other . the images of @xmath55 , which we label them with integer @xmath71 and are located at @xmath72 , are connected to the point @xmath54 through @xmath73 . the renormalized vacuum stress - energy tensor , @xmath74 , is given by the renormalized hadamard function @xmath75 , which has a contribution from each image charge , except that of @xmath76 which is divergent and is associated with the minkowski vacuum state , i.e. , @xmath77 one can obtain an algebraic expression for @xmath74 by following the steps below , + - finding an appropriate identification of the points in minkowski space , + - choosing local frames on @xmath4 , + - since the frames in @xmath54 and @xmath78 are related through a lorentzian transformation , the frame in may not be the usual minkowski frame . as spinor fields obey the appropriate transformation law under change of frame , it translates into the spinors as @xmath79 , where @xmath80 is the spinor at @xmath78 with respect to the transformed frame . topological identifications demand us to impose a suitable condition on spinor fields , i.e. @xmath81 , which simply compensates for the transformation , and makes covariant and ordinary derivatives coincide , + - computing the derivatives , + - and taking the limit as the separated points are brought together . by following the above steps , the vacuum expectation value @xmath74 of the stress - energy tensor of a free massive spinor field is evaluated in four dimensional orientable space - times with @xmath82 topology . we try to find every possible spin structure in each case , including the twisted and untwisted spin connections . the first topology to consider is @xmath83 . the periodicity represented by @xmath84 is oriented in spatial @xmath85 direction , and the identical points in this topology are @xmath86 where @xmath71 is an integer and cartesian coordinates @xmath87 are used in @xmath17 . the half squared geodesic distance , @xmath88 , between the point @xmath54 and the @xmath71-th image charge at @xmath55 is given by @xmath89\eqno(15)\ ] ] due to the fact that in all space - times considered we have periodicity in spatial section of @xmath4 , the intervals between the image charges are always spacelike , that is @xmath90 and consequently only the first term in ( 11 ) will concern us . we choose the local frames to be everywhere parallel to the cartesian axis . we will choose such a local frame to obtain untwisted spin connections in all space - times considered . one can see that in orientable space - times in which the geodesic distance between the points @xmath54 and @xmath91 is a function of @xmath92 , we have @xmath93 , and equation ( 10 ) reduces to @xmath94 so that the vacuum stress tensor for untwisted massive spinor fields on @xmath95 is @xmath96\right\ } \eqno(17)\ ] ] where @xmath97 . the vacuum stress tensor is seen to have the opposite sign , and twice the magnitude of , the scalar stress - energy tensor given in reference [ 6 ] ( equation ( 11 ) ) . the sign and magnitude changes are respectively due to fermionic statistics and degrees of freedom . exactly the same relation holds between vacuum expectation values of massless scalar and spinor fields [ 4 ] . the next natural step would be to consider space - times with spatial topology @xmath98 , which are closed in two directions @xmath85 and @xmath99 . the identified points are ( again in the cartesian coordinates ) @xmath100 the @xmath71-th image charge of @xmath55 is located at @xmath101 and the half squared geodesic distance between point @xmath54 and @xmath101 is given by @xmath102\eqno(19)\ ] ] again we can write @xmath93 , and for untwisted spin connection we have @xmath103\right\ } \eqno(20)\ ] ] where @xmath104 . the last example of the space - times whose stress - energy tensor for free spinor fields can be read off that of scalar fields is a space - time with spatial topology @xmath105 obtained through the following identification of minkowski space @xmath106 where @xmath107 and @xmath108 are integers and @xmath109 and @xmath110 are the periodicities in the @xmath111 and @xmath112 directions , respectively . the half squared geodesic distance , @xmath113 , is given by @xmath114\eqno(22)\ ] ] and the resulting vacuum expectation value of stress - energy tensor is @xmath115\right\ } \eqno(23)\ ] ] where @xmath116 . comparing equations ( 20 ) and ( 23 ) with those obtained for massive scalar fields in [ 6 ] we note that the same relation holds between their signs and magnitudes as in the case of @xmath95 topology . twisted spin connections in the preceding topologies of are simply obtained by choosing local frames on @xmath4 such that they rotate smoothly through @xmath117 about some chosen axis as one goes from @xmath54 to its image . to _ undo _ the effect of rotation _ locally _ , the anti - periodicity conditions are forced in each case such that the odd and even modes appear with different signs . in the simplest case of @xmath118 the antiperiodicity on @xmath119 is given by , @xmath120 the same antiperiodicity condition is introduced into @xmath121 by inserting the factor of @xmath122 in ( 13 ) such that its twisted version is given by @xmath123 three inequivalent twisted connections are introduced on @xmath124 by inserting @xmath125 and @xmath126 into the related summand . similarly , we have seven different twisted connections in @xmath127 , whose corresponding expectation values are obtained by inserting @xmath125 and @xmath128 or any combination of them into the summand . all the space - times considered are orientable and it is the connection that can be twisted , not the spinor fields themselves . as discussed in [ 18 ] , for static space - times @xmath129 . the usual covariance arguments require that @xmath74 be proportional to the minkowski metric , however , point identification in minkowski space - time will modify the topological properties of infinite flat space - time , which in general , will destroy global poincare invariance . of course , it will exist as a local invariance but this is not enough . plots of energy density @xmath130 as a function of the field mass @xmath131 for the untwisted and twisted connections in @xmath95 , @xmath132 and @xmath133 topologies are shown in figures 1 - 3 respectively . compared to the massless case , the effect of mass on the energy density is to reduce its magnitude . the energy density magnitudes in the massless @xmath134 case are obtained from ( 17 ) in the limit @xmath135 as , @xmath136 @xmath137 for the untwisted and twisted spin connections respectively . these are in complete agreement with the results obtained in [ 4 ] . an interesting feature in the twisted @xmath127 case is that the energy density could be positive and for equal periodicities its maximum is shifted from @xmath138 ( fig . the non - orientability of manifold affects the spin structure , in that the local frames can not be defined globally . in a non - orientable manifold , transport around the closed spatial directions or going from @xmath54 to any of its images may change the handedness of the local frame . therefore , imposing a condition on @xmath119 is necessary to construct a consistent spinor structure on these manifolds . a four dimensional mobius strip @xmath139 is a non - orientable space - time manifold which can be constructed by the following identification in minkowski space - time @xmath140 the half squared geodesic distance @xmath88 is equal to @xmath141\eqno(29)\ ] ] if we choose local frames parallel to the coordinate axes , with going from @xmath54 to @xmath78 ( @xmath71 odd ) , the direction of the local @xmath99 axis reverses . since the transformation that relates the local frame in @xmath54 to the one in @xmath78 is parity , a suitable condition on spinor fields must relate @xmath119 to @xmath80 through a transformation @xmath142 that induces the reversal of @xmath99 as the magnitude of the coordinate @xmath85 increases by @xmath143 . therefore @xmath142 should be a @xmath41 representation of @xmath23 such that @xmath144 . by the above discussion the condition @xmath145 must be considered for all integers @xmath71 , and we have @xmath146 . the spinor stress - energy tensor may now be computed from equation ( 10 ) , where , in view of the above condition , we have @xmath147\eqno(31)\ ] ] since the trace of an odd number of @xmath148- matrices vanishes , taking the trace reveals that the second sum in equation ( 31 ) make no contribution and we immediately regain the result given for the topology , @xmath149 with periodicity @xmath150 in the @xmath85 direction , i.e. , we will have the same result as in ( 17 ) but now with @xmath151 . this is not unexpected as the mobius strip manifold is locally @xmath95 . it is seen that twisted spin connection has no effect on the stress - energy tensor , as it just changes the sign of the second term in ( 31 ) . the next example of a non - orientable manifold is the klein bottle , @xmath152 , which is obtained by the following identification of points in minkowski space , @xmath153 where now the half squared geodesic distance is given by , @xmath154\eqno(33)\ ] ] again , due to the non - orientability of klein bottle , we impose the following condition on @xmath119 , @xmath155 as in the case of mobius strip , by taking the trace , the odd @xmath71 terms make no contribution . therefore , neither the mobiosity nor twisted spin connection in the @xmath85 direction , will affect spinor vacuum stress tensor and we obtain , @xmath156\right\ } \eqno(35)\ ] ] where @xmath157^{1/2}$ ] , which is identical to that for @xmath158 , with spatial periodicities doubled in both directions . in the massless limit it may now be compared with that obtained in [ 4 ] . although @xmath159 depends on @xmath160 , even after the coincidence limit is taken , ( 35 ) is a coordinate independent result . this is in sharp contrast to the results obtained in the massive scalar case where energy density contains coordinate dependent terms , oscillatory in the @xmath99 direction [ 6 ] . this feature is retained in the twisted case as the twisted spin connection in the @xmath99 direction only inserts the extra factor @xmath161 in the summand . plots of the untwisted energy densities for orintable and nonorientable manifolds are shown in fig . misner space is somewhat different from the space - times we have examined so far , though it shares some of their characteristics which makes it an interesting case for the calculation of @xmath74 . it has flat kasner metric and @xmath95 topology . in the misner coordinates , @xmath162 , the metric is given by , @xmath163 the flatness of misner space becomes obvious by transforming to a new set of coordinates @xmath164 defined by , @xmath165 it is a simply connected space , which could be constructed with a topological identification of minkowski space . in misner coordinates , the required identification is @xmath166 this is equivalent to the identification of timelike hypersurfaces @xmath167 , where @xmath71 is an integer . in cartesian coordinates , it becomes @xmath168 where it shows that the adjacent periodic boundaries are moving toward each other at a constant speed @xmath169 in the @xmath85 direction in the minkowski space . to calculate @xmath74 , we need an appropriate vacuum state for misner space . although it does have local timelike killing vector field everywhere , the nature of the topological identification is such that the local solutions can not be patched together to form a global timelike killing vector . however , each interval in misner space is identical to a portion of minkowski space and , provided the space - time is in the minkowski vacuum state , a geodesic observer will not detect any particle . if we try to introduce local frames parallel to the coordinate axes , then the condition governing the identification of points forces us to lorentz boost by velocity @xmath170 to a new frame in the @xmath85 direction every time the misner coordinate @xmath171 is increased by an amount @xmath172 . this can be undone by the following condition on the spinor field @xmath173 for all integers @xmath71 . the bracket behind @xmath80 , induces the lorentz boost in the @xmath85 direction at a speed @xmath174 . expressed in terms of @xmath75 , it translates into @xmath175\eqno(41)\ ] ] the misner space vacuum stress tensor calculation is straightforward . in the misner coordinates the non - zero components are , @xmath176\eqno(42)\ ] ] @xmath177\eqno(43)\ ] ] @xmath178 where @xmath179 misner space contains nonchronal regions , where the roles of @xmath180 and @xmath171 are switched . the boundaries separating the chronal and nonchronal regions are null hypersurfaces , @xmath181 , called _ chronology horizons_. examination of the vacuum stress - energy tensor shows that every component grows proportional to @xmath182 as @xmath180 approaches zero and then find the energy momentum components as @xmath183 . ] at the chronology horizon . in the limit as @xmath184 , the resulting components of the vacuum stress- energy tensor for a spinor field are @xmath185 @xmath186 @xmath187 the asymptotic form of the @xmath74 components for the massive field , expanded about @xmath188 , to the leading order are identical to the components given in equations ( 46 - 48 ) . the ratio of each of these components for the massive field to that of the massless field approaches the unity near the chronology horizon . this ratio quickly decreases as @xmath180 increases , for the stress - energy components of the massive field decrease faster than those of the massless field . the ratio of the energy densities of massive to massless fields near @xmath188 is shown in fig.5 . using the point separation regularization method we have calculated the vacuum stress - energy tensor for massive spinor fields in flat space - times with nontrivial topolgies including orientable and nonorientable manifolds . both untwisted and twisted spin connections are taken into account it is shown that the spinor vacuum stress - energy tensor has the opposite sign and twice the magnitude of , the massive scalar stress - energy tensor . to consider the implications of spinor vacuum stress - energy tensor for the chronology protection conjecture we have calculated @xmath74 for the misner space - time which contains closed time like curves . it is shown that the vacuum stress - energy tensor diverges like @xmath189 as @xmath190 at the chronology horizon . one should note that while it appears that the vacuum stress - energy tensor of quantized free fields does diverge as a chronology horizon is approached , the strength of the divergence may not be sufficient for the backreaction on the metric to prevent the formation of ctcs . however the ultimate mechanism for the chronology protection ( assuming its existence ) , should the present attempts fail , is a propoerly constructed theory of quantum gravity . the authors would like to thank university of tehran for supporting this project under the grants provided by the research council . 18 j. isham proc . a362 , 383 ( 1978 ) . s. dowker and r. critchley , j. phys . a : math . gen . 9 , 535(1976 ) . r. banach and j. s. dowker , j. phys . a : math . gen.12 , 2527 ( 1979 ) . ; r. banach and j. s. dowker , j. phys . a : math . gen . 12 , 2545 ( 1979 ) b. s. dewitt , c. f. hart , and c. j. isham , physica 96a , 197 ( 1979 ) . j. ambjorn and s. wolfram , ann . 147 , ( 1983 ) 1 . ; k. kirsten and e. elizalde , phys . b , 365 ( 1996 ) 72 . tsunefumi tanaka and william a. hiscock , phys . d 52 , 4503 ( 1995 ) . w. a. hiscock and d. a. konkowski , phys . rev . d 26 , 1225 ( 1982 ) . s. w. hawking , phys . rev . d 46 , 603 ( 1992 ) . s. w. kim and k. s. thorne , phys . d43 , 3929 ( 1991 ) . d. g. boulware , phys . rev . d 46 , 4421(1992 ) . j. d. e. grant , phys . d47 , 2388 ( 1993 ) . s. v. sushkov , class . quantum grav . 14 , 523 ( 1997 ) . william a. hiscock , gr - qc/0009061 . t. frankel , the geometry of physics : an introduction ( cambridge university press , cambridge , england , 1997 ) . b. s. dewitt , physics reports , * 19 * , 6 , 295 ( 1975 ) . s. m. christensen , phys . d , 14 , 2490 ( 1976 ) ; s. m. christensen , phys . d , 17 , 946 ( 1978 ) . s. a. fulling , aspects of quantum field theory in curved spacetime , cup , 1989 . j. s. dowker and g. kennedy , j. phys . a : math . gen.11 895 ( 1978 ) . i.s . gradshteyn and i.m . ryzhik ; ( a.jeffrey , editor ) , the table of integrals , series and products , 5-th ed . , academic press , 1994 , p 971 .

the vacuum expectation value of the stress - energy tensor is calculated for spin @xmath0 massive fields in several multiply connected flat space - times . we examine the physical effects of topology on manifolds such as @xmath1 , @xmath2 , @xmath3 , the mobius strip and the klein bottle . we find that the spinor vacuum stress tensor has the opposite sign to , and twice the magnitude of , the scalar tensor in orientable manifolds . extending the above considerations to the case of misner space - time , we calculate the vacuum expectation value of spinor stress - energy tensor in this space and discuss its implications for the chronology protection conjecture .

in a stylized financial market , the price of a european option can be computed from a solution to the well - known black scholes linear parabolic equation derived by black and scholes in @xcite , and , independently by merton ( cf . kwok @xcite , dewynne _ et al . _ @xcite , hull @xcite ) . a european call ( put ) option is the right but not obligation to purchase ( sell ) an underlying asset at the expiration price @xmath0 at the expiration time @xmath1 . in contrast to european options , american style of options can be exercised anytime in the temporal interval @xmath2 $ ] with the specified time of obligatory expiration at @xmath3 . a mathematical model for pricing american put options leads to a free boundary problem consisting in construction of a function @xmath4 together with the early exercise boundary profile @xmath5\to \r$ ] satisfying the following conditions : 1 . @xmath6 is a solution to the black scholes partial differential equation : @xmath7 defined on the time dependent domain @xmath8 where @xmath9 . here @xmath10 is the volatility of the underlying asset price process , @xmath11 is the interest rate of a zero - coupon bond . a solution @xmath4 represents the price of an option if the price of the underlying asset is @xmath12 at the time @xmath13 $ ] ; 2 . @xmath6 satisfies the terminal pay - off condition : @xmath14 3 . and boundary conditions for the put option : @xmath15 for @xmath16 and @xmath17 . here @xmath18 denotes the positive part of @xmath19 . if the diffusion coefficient @xmath20 in ( [ nonlinear - bs ] ) is constant then ( [ nonlinear - bs ] ) is a classical linear black scholes parabolic equation derived by black and scholes in @xcite . if we assume the volatility coefficient @xmath20 is a function of the solution @xmath6 then equation ( [ nonlinear - bs ] ) with such a diffusion coefficient represents a nonlinear generalization of the black scholes equation . we recall that the american style of the put option has been investigated by many authors ( c.f . kwok @xcite and references therein ) . accurate analytic approximations of the free boundary position have been derived stamicar , evovi and chadam @xcite , evans , kuske and keller @xcite , and by s. p. zhu and lauko and evovi in recent papers @xcite and @xcite dealing with analytic approximations on the whole time interval . in this paper we focus our attention to the case when the diffusion coefficient @xmath21 may depend on the asset price @xmath22 and the second derivative @xmath23 of the option price . more precisely , we will assume that @xmath24 i.e. @xmath10 depends on the product @xmath25 of the asset price @xmath22 and the second derivative ( gamma ) of the option price @xmath6 . recall that the nonlinear black scholes equation ( [ nonlinear - bs ] ) with the volatility @xmath10 having the form of ( [ doplnky - c - sigma ] ) arises from option pricing models taking into account nontrivial transaction costs , market feedbacks and/or risk from a volatile ( unprotected ) portfolio . the linear black scholes equation with constant @xmath10 has been derived under several restrictive assumptions like e.g. , frictionless , liquid and complete markets , etc . such assumptions have been relaxed in order to model the presence of transaction costs ( see e.g. , leland @xcite , hoggard _ et al . _ @xcite , avellaneda and paras @xcite ) , feedback and illiquid market effects due to large traders choosing given stock - trading strategies ( frey @xcite , frey and patie @xcite , frey and stremme @xcite , schnbucher and wilmott @xcite ) , imperfect replication and investor s preferences ( barles and soner @xcite ) , risk from unprotected portfolio ( kratka @xcite , jandaka and evovi @xcite or @xcite ) . in the leland model ( generalized for more complex option strategies by hoggard _ et al . _ ) the volatility is given by @xmath26 where @xmath27 is the constant historical volatility of the underlying asset price process and @xmath28 is the so - called leland number . another nonlinear black scholes model has been derived by frey _ ( see @xcite ) . in this model the asset dynamics takes into account the presence of feedback effects due to a large trader choosing his / her stock - trading strategy ( see also @xcite ) . the diffusion coefficient @xmath10 is again non - constant : @xmath29 where @xmath30 are constants . recently , explicit solutions to the black scholes equation with varying volatility ( [ doplnky - c - frey ] ) have been derived by bordag and chankova @xcite . our last example of the black scholes equation with a non - constant volatility is the so - called risk adjusted pricing methodology model proposed by kratka in @xcite and revisited by jandaka and evovi in @xcite . in the risk adjusted pricing methodology model ( rapm ) the purpose is to optimize the time - lag between consecutive portfolio adjustments in such way that the sum of the rate of transaction costs and the rate of a risk from unprotected portfolio is minimal . in this model , the volatility is again non - constant : @xmath31 by @xmath27 we denoted the constant historical volatility of the asset price returns and @xmath32 where @xmath33 are nonnegative constants representing the transaction cost measure and the risk premium measure , respectively . ( see @xcite for details ) . another important contribution in this direction has been presented in the paper @xcite by amster , averbuj , mariani and rial , where the transaction costs are assumed to be a non - increasing linear function of the form @xmath34 , ( @xmath35 ) , depending on the volume of traded stocks @xmath36 that is needed to hedge the replicating portfolio . a disadvantage of such a transaction costs function is the fact that it may attain negative values when the amount of transactions exceeds the critical value @xmath37 . in the model studied by amster _ _ @xcite the volatility function has the following form : @xmath38 the nonconstant transaction cost model has been generalized to more realistic transaction cost function by evovi and itansk in the recent paper @xcite . in @xcite bakstein and howison investigated a parametrized model for liquidity effects arising from the asset trading . in their model the volatility function is a quadratic function of the term @xmath39 : @xmath40 the parameter @xmath41 corresponds to a market depth measure , i.e. it scales the slope of the average transaction price . the parameter @xmath42 models the relative bid ask spreads and it is related to the leland number through relation @xmath43 . finally , @xmath44 transforms the average transaction price into the next quoted price , @xmath45 . notice that if additional model parameters ( e.g. , le , @xmath46 ) are vanishing then all the aforementioned nonlinear models are consistent with the original black scholes equation , i.e. @xmath47 . furthermore , for call or put options , the function @xmath6 is convex in the @xmath22 variable . the paper is organized as follows . in the next section we recall mathematical formulation of the perpetual american put option pricing model . we furthermore present the explicit solutions for the case of the constant volatility derived by merton . in section 3 we prove the existence and uniqueness of a solution to the free boundary problem . we derive a single implicit equation for the free boundary position @xmath48 and the closed form formula for the option price . the first order expansion of the free boundary position with respect to the model parameter is also derived . we construct suitable sub and supper solutions based on merton s explicit solutions . in section 4 we present results of numerical computations of the free boundary position , option price and their dependence on the model parameter . in this section we analyze the problem of pricing the so - called perpetual put options . by definition , perpetual options are options with a very long maturity @xmath49 . notice that both the option price and the early exercise boundary position depend on the remaining time @xmath50 to maturity only . suppose that there exists a limit of the solution @xmath6 and early exercise boundary position @xmath51 for the maturity @xmath49 . recently , stationary solutions to generalized black scholes equation have been investigated by grossinho _ _ in @xcite . for american style put option the limiting price @xmath52 and the limiting early exercise boundary position @xmath53 of the perpetual put option is a solution to the stationary nonlinear black scholes partial differential equation : @xmath54 and @xmath55 the purpose of this paper is to analyze the system of equations ( [ perpetual])([perpetual - bc ] ) . in what follows , we will prove the existence and uniqueness of a solution pair @xmath56 to ( [ perpetual])([perpetual - bc ] ) . in the rest of the paper , we will assume the function @xmath57 is nondecreasing and @xmath58 . then there exists the inverse function @xmath59 such that @xmath60 which is an @xmath61 continuous and nondecreasing function such that @xmath62 . notice that the transformation @xmath63 is a useful tool when analyzing nonlinear generalizations of the black scholes equations . for example , using this transformation the fully nonlinear black scholes equation with a volatility function @xmath64 can be transformed into a quasilinear equation for the new variable @xmath65 ( see @xcite and @xcite for details ) . [ rem-1 ] typically , the nonlinear volatility function @xmath66 is an increasing function satisfying the bounds : @xmath67 for some constants @xmath27 and @xmath68 . then it is easy to verify that , for any @xmath69 , there are constants @xmath70 such that @xmath71 the estimates ( [ betabound ] ) imply that the integral @xmath72 of a perpetual american put option for the parameters : @xmath73 and constant volatility @xmath74 and @xmath75.,scaledwidth=45.0% ] in the case of a constant volatility @xmath76 the free boundary value problem ( [ perpetual])([perpetual - bc ] ) for the function @xmath6 and the limiting early exercise boundary position @xmath48 has a simple explicit solution discovered by merton ( c.f . kwok @xcite ) . the closed form solution has the following form : @xmath77 where @xmath78 a graph of a perpetual american put option with the constant volatility is shown in fig . [ obr - amer - perpetual ] . in this section we will focus our attention on existence and uniqueness of a solution of the problem ( [ perpetual])([perpetual - bc ] ) . since @xmath79 is the inverse function to @xmath80 the pair @xmath56 is a solution to ( [ perpetual ] ) if and only if @xmath81 let us introduce the following transformation of variables : @xmath82 since @xmath83 the function @xmath84 is a solution to the initial value problem @xmath85 the latter initial condition easily follows from the smooth pasting conditions @xmath86 and @xmath87 . equation ( [ ueq ] ) can be easily integrated . we have the following result : [ lemma-1 ] the solution @xmath88 to the initial value problem ( [ ueq])-([uinit ] ) is uniquely given by @xmath89 where @xmath90 the useful properties of the function @xmath91 are summarized in the following lemma : [ lemma-2 ] the function @xmath92 is nondecreasing and @xmath93 . suppose there exist constants @xmath94 such that * @xmath95 for all @xmath96 . then @xmath97 ; * @xmath98 for all @xmath99 . then @xmath100 , where @xmath59 is the inverse function to the function @xmath101 . henceforth we will assume that the inverse function @xmath79 satisfies the growth assumptions from lemma [ lemma-2 ] and so @xmath102 and , consequently , @xmath103 . since @xmath104 we obtain , by taking into account the boundary condition @xmath105 , that the solution to equation ( [ perpetual ] ) is given by @xmath106 using the substitution @xmath107 we have @xmath108 as @xmath109 the expression for @xmath110 can be simplified as follows : @xmath111 using the expression ( [ vexpression ] ) we can derive a single implicit integral equation for the free boundary position @xmath48 . clearly , @xmath112 if and only if @xmath113 as @xmath114 we obtain @xmath115 therefore the free boundary position @xmath48 is a solution to the following implicit equation : @xmath116 in this section we summarize the previous results and state the main result on existence and uniqueness of a solution to the perpetual american put option pricing problem ( [ perpetual])([perpetual - bc ] ) . [ th-1 ] suppose that the volatility function @xmath117 is @xmath61 smooth , @xmath58 and such that @xmath118 is increasing and it has the inverse function @xmath79 . suppose that the inverse function @xmath79 satisfies @xmath119 for some positive constants @xmath94 . then the perpetual american put option problem ( [ perpetual])([perpetual - bc ] ) has a unique solution @xmath56 where the free boundary position @xmath48 is a solution to the implicit equation @xmath120 and the option price @xmath110 is given by @xmath121 p r o o f. equation ( [ rhoeq ] ) is equivalent to ( [ theo - rho ] ) . hence it suffices to prove that ( [ theo - rho ] ) has the unique solution @xmath48 . for the auxiliary function @xmath122 we have @xmath123 and @xmath124 hence equation ( [ theo - rho ] ) has the unique solution @xmath125 . clearly , @xmath126 because the right hand side of ( [ veq ] ) is positive . since the @xmath48 is a solution to ( [ rhoeq ] ) we have @xmath112 . moreover , as @xmath127 ( see ( [ transformation ] ) ) we obtain , for @xmath128 , @xmath129 hence @xmath6 is a solution to the perpetual american put option pricing problem ( [ perpetual])([perpetual - bc ] ) , as claimed . @xmath130 [ rem-2 ] in the case of a constant volatility function @xmath131 we have @xmath132 . it follows from equation ( [ theo - rho ] ) that @xmath133 and @xmath134 because @xmath135 , and so @xmath136 . hence the solution is identical with merton s explicit solution . in this section we will investigate dependence of the free boundary position on model parameters . we consider the volatility function of the form : @xmath137 as @xmath138 . here @xmath139 and @xmath140 are model parameters . our goal is to find the first order expansion of the free boundary position @xmath48 considered as a function of a parameter @xmath141 , i.e. @xmath142 . first , we derive expression for the derivative @xmath143 of the inverse function @xmath79 . for @xmath144 we have @xmath145 and so @xmath146 for @xmath147 we have @xmath148 . therefore @xmath149 the derivative of the free boundary position @xmath142 can be deduced from the implicit equation ( [ theo - rho ] ) . we have @xmath150 since , for @xmath147 we have @xmath151 we conclude @xmath152 in summary we have shown the following result : [ theo - sensitivity ] if the volatility function @xmath66 has the form @xmath153 as @xmath138 , where @xmath154 , then the free boundary position @xmath142 of the perpetual american put option pricing problem has the asymptotic expansion : @xmath155 in the case @xmath156 we have @xmath157 it corresponds to the constant volatility model . thus @xmath158 where @xmath159 . hence @xmath160 as claimed by theorem [ theo - sensitivity ] . in this section our aim is to derive sub and super solutions to the perpetual american put option pricing problem . throughout this section we will assume a stronger assumption on monotonicity of the volatility function . namely , we will assume that the function @xmath161 is nondecreasing . clearly , such an assumption implies that @xmath162 is an increasing function . let @xmath163 be positive constant . by @xmath164 we will denote the explicit merton solution presented in section [ sec - merton ] , i.e. @xmath165 where @xmath166 it means that the pair @xmath167 is the explicit merton solution corresponding to the constant volatility @xmath168 ( see ( [ explicit - solution ] ) ) . then , for the transformed function @xmath169 we have @xmath170 clearly , @xmath171 next we will construct a super solution to the solution @xmath172 of the equation @xmath173 by means of the merton solution @xmath174 where @xmath175 is the unique root of the equation @xmath176 since @xmath177 we obtain @xmath178 by taking the inverse function @xmath79 we finally obtain @xmath179 with regard to ( [ u - eq ] ) we conclude that @xmath180 similarly , we will construct a merton sub solution @xmath181 satisfying the opposite differential inequality . let @xmath182 be given by @xmath183 i.e. @xmath184 . then @xmath185 and so , by taking the inverse function @xmath79 we obtain @xmath186 . then , from ( [ u - eq ] ) we conclude that @xmath187 and @xmath188 corresponding to constant volatilities @xmath189 and @xmath190 for model parameters : @xmath73.,scaledwidth=40.0% ] in fig . [ obr - amer - perpetual - bounds ] we plot merton s solutions @xmath191 corresponding to @xmath192 ( @xmath193 ) and @xmath194 ( @xmath195 ) where @xmath196 . in what follows we will prove the inequalities @xmath197 where @xmath48 is the free boundary position for the nonlinear perpetual american put option pricing problem ( [ perpetual])([perpetual - bc ] ) . denote @xmath198 the inverse function to the function @xmath199 . as @xmath200 we have @xmath201 for any @xmath202 . since @xmath203 we conclude @xmath204 . on the other hand , let @xmath205 be the inverse function to the function @xmath206 . then , for @xmath207 we have @xmath208 therefore , for @xmath207 we have @xmath209 and arguing similarly as before we obtain the estimate @xmath210 and so the inequalities ( [ rhobounds ] ) follows . for initial conditions we have @xmath211 and so @xmath212 using the comparison principle for solutions of ordinary differential inequalities we have @xmath213 . taking into account the explicit form of the function @xmath110 from theorem [ th-1 ] ( see ( [ theo - v ] ) ) we conclude the following result : [ theo - comparison ] let @xmath56 be the solution to the perpetual american pricing problem ( [ perpetual])([perpetual - bc ] ) . then @xmath214 and @xmath215 where @xmath216 are explicit merton s solutions corresponding to constant volatilities . a graphical illustration of the comparison principle is shown in fig . [ obr - freyrapm - perpetual ] . in this section we propose a simple and efficient numerical scheme for constructing a solution to the perpetual put option problem ( [ perpetual])([perpetual - bc ] ) . using transformation @xmath217 , i.e. @xmath218 and @xmath219 we can rewrite the equation for the free boundary position ( see ( [ theo - rho ] ) ) as follows : @xmath220 similarly , the option price ( [ theo - rho ] ) can be rewritten in terms of the @xmath65 variable as follows : @xmath221 with this transformation we can reduce computational complexity in the case when the inverse function @xmath79 is not given by a closed form formula . results of numerical calculation for the rapm model and frey - stremme model are summarized in table [ tab2 ] . we show the position of the free boundary @xmath48 and the perpetual option value @xmath6 evaluated at exercise price @xmath222 . the results are computed for various values of the model @xmath141 for the frey stremme model and the rapm model . other model parameter were chosen as : @xmath73 and @xmath74 . for the frey - stremme model.,title="fig:",scaledwidth=40.0% ] for the frey - stremme model.,title="fig:",scaledwidth=40.0% ] c|ccccccc @xmath141 & 0.00 & 0.01 & 0.05 & 0.10 & 0.15 & 0.20 & 0.22 + @xmath48 & 68.9655 & 68.2852 & 65.7246 & 62.8036 & 60.1175 & 57.6177 & 56.6627 + @xmath223 & 13.5909 & 13.8005 & 14.6167 & 15.5961 & 16.5389 & 17.4510 & 17.8083 + in the frey stremme model the nonlinear volatility function has the form : @xmath224 ( see ( [ doplnky - c - frey ] ) ) . the range of the parameter @xmath141 is therefore limited to satisfy the strict inequality @xmath225 . however , using the identity @xmath226 we can approximate the frey stremme volatility function as follows : @xmath227 where @xmath228 is sufficiently large . in computations shown in fig . [ obr - sensitivity - frey2 ] and tab . [ tab2b ] we present results of the free boundary position and the perpetual american put option price @xmath223 for @xmath229 and larger interval of parameter values @xmath230 $ ] . notice that the results for small values @xmath231 computed from the original frey stremme volatility ( [ doplnky - c - frey ] ) and ( [ frey - modif ] ) coincide . for the modified frey stremme model.,title="fig:",scaledwidth=40.0% ] for the modified frey stremme model.,title="fig:",scaledwidth=40.0% ] c|ccccccc @xmath141 & 0.00 & 0.10 & 0.50 & 1.00 & 2.00 & 4.00 & 8.00 + @xmath48 & 68.9655 & 62.8037 & 45.3007 & 31.0862 & 16.3126 & 8.3818 & 5.4556 + @xmath223 & 13.5909 & 15.5961 & 22.4529 & 29.5719 & 41.0654 & 56.1777 & 70.2259 + in our next computational example we consider the risk adjusted pricing methodology model ( rapm ) . in computations shown in fig . [ obr - sensitivity - rapm ] , a ) and tab . [ tab3 ] we present results of the free boundary position and the perpetual american put option price @xmath223 for the rapm model ( see fig . [ obr - sensitivity - rapm ] , b ) ) . we also show comparison of the free boundary position @xmath142 and its linear approximation derived in theorem [ theo - sensitivity ] ( see fig . [ obr - sensitivity - rapm ] , c ) ) . for the rapm model the comparison of the free boundary position and its linear approximation c).,title="fig:",scaledwidth=40.0% ] for the rapm model a , b ) . the comparison of the free boundary position and its linear approximation c).,title="fig:",scaledwidth=40.0% ] \a ) 4truecm b ) for the rapm model a , b ) . the comparison of the free boundary position and its linear approximation c).,scaledwidth=40.0% ] c ) c|ccccccc @xmath141 & 0.00 & 0.10 & 0.50 & 1.00 & 2.00 & 4.00 & 8.00 + @xmath48 & 68.9655 & 66.7331 & 59.6973 & 53.3234 & 44.5408 & 34.0899 & 23.6125 + @xmath223 & 13.5909 & 14.5761 & 17.9398 & 21.3434 & 26.6857 & 34.3393 & 44.1774 + for the frey - stremme model ( left ) with @xmath231 and the rapm model ( right ) with @xmath232 . sub- and super- solutions @xmath233 and @xmath234 are depicted by dashed curves . the model parameters : @xmath73 and @xmath74.,title="fig:",scaledwidth=40.0% ] for the frey - stremme model ( left ) with @xmath231 and the rapm model ( right ) with @xmath232 . sub- and super- solutions @xmath233 and @xmath234 are depicted by dashed curves . the model parameters : @xmath73 and @xmath74.,title="fig:",scaledwidth=40.0% ] in the last examples shown in fig . [ obr - freyrapm - perpetual ] we present comparison of the option price @xmath110 and the free boundary position @xmath48 for the frey stremme model ( left ) and the risk adjusted pricing methodology model ( right ) with closed form explicit merton s solutions corresponding to the constant volatility . in this paper we analyzed the free boundary problem for pricing perpetual american put option when the volatility is a function of the second derivative of the option price . we showed how the problem can be transformed into a single implicit equation for the free boundary position and explicit integral expression for the option price . this research was supported by the european union in the fp7-people-2012-itn project strike - novel methods in computational finance ( 304617 ) , the project cemapre multi/00491 financed by fct / mec through national funds and the slovak research agency project vega 1/0780/15 . fabiao , r. f. , grossinho , m. r. , and simoes , o. : positive solutions of a dirichlet problem for a stationary nonlinear black - scholes equation , nonlinear analysis , theory , methods and applications , 71 ( 2009 ) , 46244631 . jandaka , m. , and evovi , d. : on the risk adjusted pricing methodology based valuation of vanilla options and explanation of the volatility smile . _ journal of applied mathematics _ , 3 ( 2005 ) , 235258 .

we investigate qualitative and quantitative behavior of a solution to the problem of pricing american style of perpetual put options . we assume the option price is a solution to a stationary generalized black - scholes equation in which the volatility may depend on the second derivative of the option price itself . we prove existence and uniqueness of a solution to the free boundary problem . we derive a single implicit equation for the free boundary position and the closed form formula for the option price . it is a generalization of the well - known explicit closed form solution derived by merton for the case of a constant volatility . we also present results of numerical computations of the free boundary position , option price and their dependence on model parameters . _ ams mos 2000 _ primary : 35r35 , secondary : 91b28 , 62p05 _ _ keywords and phrases _ _ option pricing , nonlinear black - scholes equation , perpetual american put option , early exercise boundary

originally , the three gap theorem was the conjecture of h. steinhaus . subsequently , several proofs were proposed by @xcite @xcite @xcite @xcite @xcite @xcite @xcite . the proof proposed in this paper is a presentation of the proof completely fomalized in the coq proof asssistance system @xcite . this formal proof is based on tony van ravenstein s @xcite . this kind of demostration , which involves geometrical intuition , is a real challenge for proof assistance systems . that is what motivated our work . therefore , the interest of such an approach is to understand , by means of an example , if the coq system allows us to prove a theorem coming from pure mathematics . + in addition , this development allowed us to clarify some points of the proof and has led to a more detailed proof . first , we will define the notations and definitions used for stating and proving this theorem.the second part deals with different states of the theorem and with the proof itself . finally , the last part presents advantages of the formal proof stating the main differences between our proof and tony van ravenstein s proof . we can refer to figure [ cercle ] . * @xmath2 is the natural numbers set . * @xmath3 is the real numbers set . * the integer part of a real number r is noted @xmath4 . * the fractional part of a real number @xmath5 , ie @xmath6 , is written @xmath7 . * the first point on the circle is the point @xmath8 . * unless explicitly mentioned , we consider @xmath0 points distributed around the circle . these are numbered from @xmath8 to @xmath9 . * we consider the circle of * unit circumference * and with a clockwise orientation . * @xmath1 is counted in turns of the circle ( and not in radian ) ; then @xmath10 . * the first point ( @xmath11 if @xmath121 ) on the right of @xmath8 is written @xmath13 . @xmath13 is a function from the natural numbers to the natural numbers . * the last point ( @xmath140 if @xmath121 ) before @xmath8 is written @xmath15 . @xmath15 is a function from the natural numbers to the natural numbers . * @xmath16 is equivalent to @xmath17 . the distance from point @xmath8 to point n is @xmath18 . the following definitions are valid for all @xmath1 , rational or irrational . [ first ] if @xmath19 then there exists an integer @xmath20 s.t . @xmath21 and @xmath22 if @xmath23 then @xmath24 + by induction on @xmath0 . + - @xmath25 : in this case @xmath26 . + - suppose the lemma to be holds for @xmath0 : then there exists @xmath20 s.t . @xmath21 and @xmath22 if @xmath23 then @xmath24 ; + let us show that there exists @xmath27 s.t . @xmath28 and @xmath22 if @xmath29 then @xmath30 . + by cases : - if @xmath31 then @xmath32 . - if @xmath33 then @xmath34 . @xmath35 [ last ] if @xmath19 then there exists an integer @xmath36 s.t . @xmath37 and @xmath22 if @xmath23 then @xmath38 + symmetrical proof with respect to first . @xmath35 the successor of a point on the circle ( @xmath39 ) verifies the following property : [ points ] @xmath40 if @xmath41 then we have : 1 . there exists an integer @xmath42 s.t . @xmath43 and @xmath44 and @xmath22 if @xmath45 and if @xmath46 then @xmath47 + or 2 . @xmath22 if @xmath45 then @xmath48 + by induction on @xmath0 . + - @xmath49 : @xmath8 verifies the property . + - suppose lemma to holds for @xmath0 and prove it for @xmath50 : the induction hypothesis is the following : + either + 1 . there exists an integer @xmath51 s.t . @xmath52 and @xmath53 and @xmath22 if @xmath45 and if @xmath46 then @xmath54 + or + 2 . @xmath22 if @xmath45 then @xmath48 + we prove that : + either \1 . there exists an integer @xmath55 s.t . @xmath56 and @xmath57 and @xmath22 if @xmath58 and if @xmath46 then @xmath59 + or \2 . @xmath22 if @xmath58 then @xmath48 + by cases : - if @xmath60 we are in case 1 and we continue by cases : - if @xmath61 then @xmath62 . - if @xmath63 then @xmath64 . - if @xmath65 we are in case 2 and the proof is immediate by induction hypothesis . @xmath35 [ after ] for all points n on the circle , the point @xmath66 verifies the property of points ( lemma [ points ] ) for @xmath67 and is defined such that : + if we are in case 1 . then @xmath68 + if we are in case 2 . then @xmath69 . statement in natural language : [ theorem1 ] let @xmath0 points be placed consecutively around the circle by an angle of @xmath1 . then for all irrational @xmath1 and natural @xmath0 , the points partition the circle into gaps of at most three different lengths . as shown by theorem [ theorem1 ] the points are numbered in order of apparition ; now , if we do more than one revolution around the circle , new points appear between the former points . then , when the last point @xmath70 is placed , it is possible to number them again consecutively and clockwise . in this new numeration , we use only the definitions of @xmath71 , @xmath72 and @xmath39 , from lemmas [ first ] and [ last ] , and of the definition [ after ] . if we set @xmath73@xmath74@xmath73=@xmath75 , then the distance of a point @xmath76 from its successor @xmath66 is given by @xmath73@xmath77@xmath73 . in order to show that this function can have at most three values , we show that the function @xmath78 can itself have at most three values . + so , proving theorem [ theorem1 ] comes to the same thing as showing the following mathematical formulation , which we will prove in the next paragraph . [ letheoreme ] @xmath79 + 1 . this transcription means that the circle of @xmath0 points is divided into + @xmath80 gaps of length @xmath73@xmath81 , + @xmath82 gaps of length @xmath73@xmath83 and + @xmath84 gaps of length @xmath73@xmath81+@xmath73@xmath83 . 2 . theorem [ letheoreme ] is true for @xmath1 rational and irrational . here , however , we present only the proof for @xmath1 irrational . indeed , most of the intermediate results are false for @xmath1 rational ( among other reasons because @xmath71 , @xmath72 and @xmath39 are no longer functions ) . moreover , the theorem is trivially true for @xmath1 rational : if @xmath85 then the circle may include one or two lengths of gap - depending on whether @xmath86 or @xmath87 . we recall that the proof is detailed for @xmath1 irrational and @xmath19 . + [ inter1 ] if @xmath88 @xmath89 + 1 . case @xmath90 : + for @xmath91 , by definition of first we have @xmath92 . + + we want to prove that @xmath93 is the successor of @xmath94 . + let us first show that @xmath93 belongs to the circle of @xmath0 points : if @xmath95 then + @xmath96 . + + now , let us show that : if @xmath97 is any point of the circle ( @xmath98 ) then we have either @xmath99 or @xmath100 . + by reductio ad absurdum and by cases : + let us suppose that @xmath101 + * if @xmath102 then @xmath103 therefore + @xmath104 which contradicts the definition of first , since @xmath105circle because @xmath106 . + * if @xmath107 then @xmath108 therefore @xmath109 which contradicts the definition of first(n ) , since @xmath110circle because @xmath111 . + + in these two former cases @xmath112 if @xmath113 . + let us show this by reductio ad absurdum : + if @xmath114 then + @xmath115 + therefore by definition of @xmath71 @xmath116 which is absurd because @xmath117 for @xmath19 . + 2 . case @xmath118 : + for @xmath119 , by definition of @xmath72 we have @xmath120 . + + we want to prove that @xmath121 is the successor of @xmath94 . + let us first show that @xmath121 belongs to the circle of @xmath0 points : if @xmath122 then + @xmath123 because @xmath124 . + + now , let us show that : if @xmath97 any point of the circle ( @xmath98 ) then we have either @xmath99 or @xmath125 . + by reductio ad absurdum and by cases : + let us suppose that @xmath126 + * if @xmath127 then @xmath128 therefore @xmath129 which contradicts the definition of last , since @xmath130circle because @xmath131 . + * if @xmath132 then + @xmath133 + therefore @xmath134 + which contradicts the definition of last , since @xmath135circle because @xmath136 . + + in these two former cases @xmath137 if @xmath138 . + as @xmath1 is irrationnal and by definition of @xmath72 we have @xmath139 therefore @xmath140 and we have effectively @xmath141 , since @xmath142 . [ irrat ] the fact of @xmath1 is irrational is essential for showing that @xmath143 . indeed , as in this case we have @xmath144 therefore @xmath143 . let us show this by contradiction . + in order to do so , let us suppose @xmath145 . + then @xmath146 therefore @xmath147 and as only an integer number has a fractional part equal to zero we have @xmath148 , @xmath149 from which we conclude that @xmath150 which contradicts @xmath1 irrationnal . @xmath35 let us prove now the general case . + let us set for the rest of the proof @xmath151 . [ lenm ] @xmath152 . + by reductio ad absurdum . we suppose @xmath153 and we show that , in this case , the point @xmath154 is situated either before @xmath71 , or after @xmath72 , which contradicts their definition . + let us show , therefore , that either @xmath155 or @xmath156 : + let us consider the following cases : 1 . @xmath157 : + since for @xmath19 @xmath117 we can write that + @xmath158 thus that + @xmath156 . @xmath159 : + in the same way we can write , using the fact that @xmath160 , that @xmath161 thus that + @xmath155 . @xmath35 [ firstnm ] @xmath162 . + by definition of @xmath71 , we know that for all @xmath163 and @xmath164 s.t . @xmath165 we have that if @xmath166 then @xmath167 . + let us take @xmath168 and @xmath167 and then we have for all @xmath164 s.t . @xmath169 if @xmath170 then @xmath171 + now , it is sufficient to show that @xmath170 @xmath172 , @xmath169 : + for @xmath173 it is the definition of @xmath71 ( lemma [ first ] ) . + for @xmath174 by the reductio ad absurdum : let us suppose that @xmath175 + as @xmath176 we have immediately that + @xmath177 and @xmath178 + and by definition of @xmath71 and @xmath72 that @xmath179 and @xmath180 . + therefore we have , owing to the hypothesis of contradiction and to lemmas [ first ] and [ last ] that : + @xmath181 and + @xmath182 which implies that + @xmath183 thus that + @xmath184 . but , as shown in remark [ irrat ] this equality compels @xmath1 to be rational if @xmath185 which is the case . @xmath35 [ lastnm ] @xmath186 . + symmetrical proof with the previous . @xmath35 [ afternm ] for all @xmath76 s.t . @xmath187 and @xmath188 we have @xmath189 . + we proceed by cases : 1 . case @xmath187 : + using the irrationality of @xmath1 ( counterpart of remark [ irrat ] ) we have that to prove this lemma is equivalent to @xmath190 which is also equivalent to + @xmath191 and @xmath192 . + let us proceed by cases and by reductio ad absurdum : * case @xmath191 : + let us suppose that @xmath193 . + according to lemma [ points ] , we show immediately the following property : + @xmath194 , if @xmath195 and if @xmath196 then @xmath197 . let us use this property with + @xmath198 . we directly get the contradiction on condition that : * * @xmath16 i.e. @xmath199 ; true by case 1 . * * @xmath200 i.e. @xmath201 true using lemma [ inter1 ] . * * @xmath202 by definition of after ( lemma [ points ] and definition [ after ] ) + lemma [ inter1 ] ( in order to show that @xmath203 ) . * * @xmath204 true by hypothesis of contradiction . * case @xmath192 : + let us suppose that @xmath205 . we use the same property taking @xmath206 and @xmath168 ( except in @xmath207 ) . case @xmath188 : the proof is done with the same way . @xmath35 for @xmath76 situated in the third gap , the value of @xmath66 is given from the following lemma : [ cas3 ] for all @xmath76 , @xmath208 there does not exist @xmath209 s.t . . + reduction ad absurdum . + let us suppose there exists one @xmath209 s.t . + @xmath210 . + this @xmath207 verifies one of the three following cases ( total order on the real numbers ) : 1 . if @xmath211 : + then @xmath212 which contradicts the definition of the function @xmath39 . 2 . if @xmath213 : + according to lemmas [ inter1 ] and [ firstnm ] @xmath214 . but , as @xmath1 is irrationnal , we ought to have @xmath215 which contradicts the hypothesises @xmath216 and @xmath217 ( using lemma [ lenm ] ) . 3 . if @xmath218 : + we use the already seen property @xmath219 , if @xmath220 and if @xmath221 then @xmath222 with @xmath168 , @xmath223 . + then we have , using principally lemma [ inter1 ] that + @xmath224 which contradicts the hypothesis . @xmath35 + let us suppose that the circle includes @xmath225 points . then , we know how to show the theorem ( lemma [ inter1 ] ) . now , it is sufficient `` to remove '' the @xmath226 points which are too many . 1 . if @xmath227 then : + according to lemma [ lenm ] we have @xmath228 . using lemmas [ firstnm ] , [ lastnm ] , [ afternm ] and [ inter1 ] we immediately get the result . 2 . if @xmath208 then : + using lemma [ cas3],we show that the @xmath226 points from @xmath0 do not exist and by definition of @xmath39 ( lemma [ points ] and definition [ after ] ) we get the result . 3 . if @xmath229 then : + as in case 1 . the proof given in this paper has been developped from a proof completely formalized in the system coq @xcite . with a mathematical theorem such as this , the interest is twofold : the first consists in indicating the possible limits of the proof assistance system in order to improve it ; second , is the emphasizing the basic mathematical properties or hypotheses used implicitly during the demonstration . + this proof is based on geometrical intuitions and the demostration of these intuitions often requires , for example , basic notions about the fractional parts . even so , these notions are neither easy to formalize nor to prove in a system where real numbers are not naturally found , unlike other types which can be easily defined inductively . so , one challenge was to prove this theorem from a simple axiomatization of the real numbers . the formulation of real numbers used for this will be discussed further . moreover , it is interesting to notice that the theorem shown is , in some sence , stronger than that which was stated initially . indeed , not only do we show that there are at most three different lengths of gaps , but we can also give their value and their place on the circle . this modified statement is due to @xcite . + from the proof completely formalized in coq , we can , for instance , compare this informal proof resulting from the formal proof with that of tony van ravenstein . + * two possibilities exist to describe the real numbers : we can construct the reals or axiomatize them . we chose an axiomatical development for reasons of simplicity and rapidity . we can refer to @xcite and @xcite for constructions from cauchy s sequences or dedekind s cuts . most properties of the real numbers ( commutative field , order , the archimedian axiom ) are first order properties . on the other hand , the completeness property is a second order property , as it requieres to quantify on the sets of real numbers . instead of this axiom , we can put an infinity of first order axioms , according to which any odd degree has a root in @xmath3 . hence , we get the `` real closed field '' notion . we thus chose axiomatization at the _ second order _ based on the fact that @xmath3 is a * commutative ordered archimedian and complete field*. for these notions , we based our work on @xcite and @xcite . * the formal proof showed us that the axiom of completeness of the real numbers was not necessary . therefore , the statement and the proof of this theorem are true in all the commutative ordered and archimedean fields . + archimedes axiom could also be replaced by a weaker axiom making it possible to define only the fractional part . + in the same way , e.fried and v.t.sos have given a generalization of this theorem for groups @xcite . many intermediate lemmas had to be proved . the formal proof , for instance , made it possible to identify four lemmas concerning the fractional part , which had remained implicit in tony van ravenstein s proof , and are at the heart of the proof . @xmath1 irrational is hypothesis used by tony van ravenstein , but the formalization shows precisely where this hypothesis is used ( cf remark [ irrat ] ) . in particular , if @xmath1 is rational , the points can be mingled , and @xmath39 , for example , is not then a function . during tony van ravenstein s informal proof , we see that we can tolerate an inaccuracy in the dependence of @xmath71 , @xmath72 and @xmath39 to @xmath0 or @xmath225 . although this is not a mistake , the formal proof showed the necessity of proving these lemmas , which are not trivial ( lemmas [ firstnm ] , [ lastnm ] and [ afternm ] ) . the formal proof makes it possible to say precisely where those lemmas are used . the formal proof carried out in the system coq - from the axiomatization of real numbers as a commutative , ordered , archimedian and complet field - is a classical proof seeing that an intuitionist reading of the total order involves the decidability of the equality of the real numbers , which obviously , is not the case . therefore , we can raise the question of the existence of a constructive proof of the three gap theorem . + we could probably give an intuitionistic proof for each of the two cases , according to whether @xmath1 is rational or irrational because we know exactly the length of the gaps between two points of the circle . but , the two cases can not be treated at the same time . thus in our proof it should be supposed that @xmath1 is rational or not and we do not see , so far how to avoid this distinction . +

we deal with the distribution of @xmath0 points placed consecutively around the circle by a fixed angle of @xmath1 . from the proof of tony van ravenstein @xcite , we propose a detailed proof of the steinhaus conjecture whose result is the following : the @xmath0 points partition the circle into gaps of at most three different lengths . + we study the mathematical notions required for the proof of this theorem revealed during a formal proof carried out in coq .

Fashion victim: rhabdomyolysis and bilateral peroneal and tibial neuropathies as a result of squatting in ‘skinny jeans’ Karmen Wai 1 , Philip Douglas Thompson 2 , Thomas Edmund Kimber 2 1 Neurology Unit , Royal Adelaide Hospital , Adelaide, South Australia , Australia 2 Neurology Unit, Royal Adelaide Hospital and Department of Medicine , University of Adelaide , Adelaide, South Australia , Australia Correspondence to Associate Professor, Thomas Edmund Kimber, Neurology Unit, Royal Adelaide Hospital and Department of Medicine, University of Adelaide, North Terrace, Adelaide, SA 5000, Australia; thomas.kimber{at}health.sa.gov.au Received 22 March 2015 22 March 2015 Revised 21 April 2015 21 April 2015 Accepted 5 May 2015 5 May 2015 Published Online First 23 June 2015 A 35-year-old woman presented with severe weakness of both ankles. On the day prior to presentation, she had been helping a family member move house. This involved many hours of squatting while emptying cupboards. She had been wearing ‘skinny jeans’, and recalled that her jeans had felt increasingly tight and uncomfortable during the day. Later that evening, while walking home, she noticed bilateral foot drop and foot numbness, which caused her to trip and fall. She spent several hours lying on the ground before she was found. On examination, her lower legs were markedly oedematous bilaterally, worse on the right side, and her jeans could only be removed by cutting them off. There was bilateral, severe global weakness of ankle and toe movements, somewhat more marked on the … ||||| Painfully Skinny Jeans Land A Woman In The Hospital Enlarge this image toggle caption iStockphoto iStockphoto If you've wondered whether there's a downside to wearing superskinny jeans, this story's for you. A 35-year-old Australian woman wound up in the hospital after wearing skinny jeans while helping a family member move. The move involved "many hours of squatting while emptying cupboards," according to a report published Monday in the journal Neurology, Neurosurgery & Psychiatry. As the day went on, those jeans were making her increasingly uncomfortable. But it wasn't until that evening that the situation went south. As she walked home, the woman found herself struggling to lift her increasingly numb feet. She fell to the ground, and lay there for several hours before she was found and taken to the Royal Adelaide Hospital. At the hospital, the woman's legs were so swollen that staff had to cut off her jeans. Neurologists tried to figure out what had gone wrong. Tests revealed that she had almost no muscle strength in her ankles and toes, while the muscles of her hips and knees were normal. A CT scan of her legs showed signs of muscle damage in the calves. Tests of the tibial nerves, which provide movement and sensation to the calf and foot, and the peroneal nerves, which run from the outside of the knee down to the foot and ankle, showed they weren't sending signals properly. That was the clue. Nerve damage can be caused by pressure. In the case of the peroneal nerves, that can include pressure from crossing the legs, wearing high boots or squatting. (Previous research refers to "strawberry pickers' palsy.") "The wearing of 'skinny' jeans had likely potentiated the tibial neuropathies by causing a compartment syndrome as the lower leg swelled," the report concluded. Not good. The swelling of compartment syndrome can lead to permanent muscle and nerve damage, or amputation. In this case, the victim fared better. After four days in the hospital on intravenous fluids, she regained her ability to walk and went home. No word on whether she's ever donned skinny jeans again. This isn't the first time we've reported on the perils of excessively tight trousers. In 2011, a doctor in Tarrytown, N.Y., told us about a 15-year-old soccer player who had numbness and tingling in her leg caused by wearing compression shorts. In some cases, the only damage tight clothes will do is to your wallet. Last fall, the Federal Trade Commission ordered to two companies to stop selling caffeine-infused shapewear, saying that the amped-up skivvies would not, as one firm claimed, "reduce the size of your hips by up to 2.1 inches and your thighs by up to one inch, and would eliminate or reduce cellulite and that scientific tests proved those results." The FTC disputed that claim, and ordered the companies to fork over $1.5 million to customers who had been lured in by the promise of effortless shrinkage. ||||| Squatting in 'skinny' jeans for a protracted period of time can damage muscle and nerve fibres in the legs, making it difficult to walk, reveals a case study published online in the Journal of Neurology Neurosurgery & Psychiatry. Doctors describe a case of a 35 year old woman who arrived at hospital with severe weakness in both her ankles. The previous day she had been helping a relative move house, and had spent many hours squatting while emptying cupboards. She had been wearing tight 'skinny' jeans and recalled that these had felt increasingly tight and uncomfortable as the day wore on. Later that evening, she experienced numbness in her feet and found it difficult to walk, which caused her to trip and fall. Unable to get up, she spent several hours lying on the ground before she was found. Her calves were so swollen that her jeans had to be cut off her. She couldn't move her ankles or toes properly and had lost feeling in her lower legs and feet. Investigations revealed that she had damaged muscle and nerve fibres in her lower legs as a result of prolonged compression while squatting, which her tight jeans had made worse, the doctors suggest. The jeans had prompted the development of compartment syndrome--reduced blood supply to the leg muscles, causing swelling of the muscles and compression of the adjacent nerves. She was put on an intravenous drip and after 4 days she could walk unaided again, and was discharged from hospital. ###

– "Rhabdomyolysis and bilateral peroneal and tibial neuropathies" are as uncomfortable as they sound, and they can be caused by wearing skinny jeans for the wrong jobs, doctors say. According to a case study in the journal Neurology, Neurosurgery & Psychiatry, an Australian woman who wore skinny jeans while helping a family member move—a job that involved hours squatting on the floor emptying cupboards—ended up hospitalized and unable to walk for four days, NPR reports. The 35-year-old had apparently ignored increasing discomfort but ultimately "noticed bilateral foot drop and foot numbness" that led her to trip and fall while walking home, per the study. She was stranded for hours until someone found her and called an ambulance. A press release explains her calves were swollen to such a degree that her jeans had to be cut off; she didn't have normal movement in her ankles and toes, and the feeling was gone from her lower legs and feet. Doctors discovered she had muscle and nerve damage, apparently caused by reduced blood supply to the leg muscles. Dr. Thomas Kimber of the Royal Adelaide Hospital tells the AP that the long periods of squatting in the tight jeans caused a surprisingly severe amount of damage of a kind that hasn't been linked to skinny jeans before, although the woman was able to walk after four days and later made a full recovery. He says part of the problem with the jeans could be their "non-stretchy nature," which leads to nerves and muscles being squeezed. (The jeans can cause another problem.)

the most massive galaxies may place interesting constraints on models of galaxy formation ( e.g. de lucia et al . 2006 ; almeida et al . 2007 ) . but which observable one should use as a proxy for mass is debatable . if luminosity is a good proxy , then the brightest cluster galaxies should be the most massive galaxies ; this has led to considerable interest in their properties ( scott 1957 ; sandage 1976 ; thuan & romanishin 1981 ; malumuth & kirschner 1981 ; hoessel et al . 1987 ; schombert 1987 , 1988 ; oegerle & hoessel 1991 ; lauer & postman 1994 ; postman & lauer 1995 ; crawford et al . 1999 ; laine et al . 2003 ; lauer et al . 2007 ; bernardi et al . 2007a ) . however , velocity dispersion is sometimes used as a surrogate for mass ( the virial theorem has mass @xmath8 ) , so it is interesting to ask if a sample selected on the basis of velocity dispersion also contains the most massive galaxies . such a sample is also interesting in view of the fact that black hole mass correlates strongly and tightly with velocity dispersion ( ferrarese & merritt 2000 ; gebhardt et al . 2000 ) , so galaxies with large @xmath3 are expected to host the most massive black holes . with this in mind , bernardi et al . ( 2006 ) culled a sample of @xmath9 objects with @xmath10 km s@xmath1 from the first data release of the sload digital sky survey ( sdss dr1 ; abazajian et al . the total area from which these objects were selected is about 2000 deg@xmath11 ; for a spatially flat universe with @xmath12 and hubble constant @xmath13 km s@xmath1 , which we assume in what follows , this corresponds to a comoving volume of about @xmath14 mpc@xmath15 out to @xmath16 . some of these objects turned out to be objects in superposition , evidence for which came primarily from the spectra ( see bernardi et al . 2006 for details ) . a random subset of the others , 43 objects in all , was observed with the high resolution camera of the advanced camera system on board the hubble space telescope ( hst - acs hrc ) . on the basis of this high - resolution imaging , we have been able to separate out the true singles from those which are objects in superposition . as a result , we are now able to study the properties of objects with large @xmath3 . we describe the hst observations , our identification of the truly single objects , our classification of their isophotal shapes , and how we combine the hst imaging with sdss data to determine the environments of these objects in section [ hst ] . the isophotal shapes of these objects are compared with those of bcgs in section [ shapes ] . various scaling relations , size - luminosity , the fundamental plane , etc . are presented in section [ scaling ] . while these relations are different from those defined by the bulk of the early - type galaxy population , we show that they can actually be derived from the early - type scaling relations simply by studying what these relations look like at fixed velocity dispersion . these analyses show that our sample appears to contain two distinct types of objects : the more luminous objects tend to be round , have large sizes as well as velocity dispersions , and tend to be in crowded fields . indeed , they are rounder than other objects of similar luminosities , so it is possible that they are prolate , and viewed along the long axis . the less luminous objects are not round , have abnormally small sizes and are not necessarily in crowded fields ; even if rotational motions have compromised the sdss velocity dispersion estimates , these objects may be amongst the densest galaxies for their luminosities . a final section summarizes our findings and discusses some implications of the bimodal distribution we have found , as well as of the fact that no galaxy appears to have a velocity dispersion larger than @xmath17 km s@xmath1 . in a companion paper ( hyde et al . 2008 ) , we study the surface brightness profiles of the objects classified as singles in much more detail , placing them in the context of other hst - based studies of early - type galaxies ( e.g. laine et al . 2003 ; ferrarese et al . 2006 ; lauer et al . the analysis below is based on observations taken between august 2004 and june 2005 as part of a cycle 13 snapshot survey . the target list for the snapshot survey contained 70 objects , all of which were selected from the sdss as described in paper i ; i.e. , they all had reported velocity dispersions larger than 350 km s@xmath1 , and none were identified from the imaging , the line profiles or the cross - correlation analyses described in paper i as being multiple . of these 70 objects , 43 were observed . the following observing sequence was adopted for each target galaxy : + -the center of each galaxy was positioned close to the hrc aperture . + -a total integration time of 1200 s in the f775w ( which resembles sdss @xmath2 ) filter , split into four exposures of 300 s , was used . + -each visit used the line - dither pattern to allow removal of most cosmic ray events . + data reduction details and analysis of the photometric profiles are presented in hyde et al . ( 2008 ) . in the present context , the great virtue of hst is its angular resolution ( @xmath18 arcsec / pixel ) : at the median redshift of our sample , @xmath19 , scales down to about 95 pc are resolved . ( this scale , for sdss imaging , is about sixty times larger . ) therefore , a simple visual inspection of the f775w images allowed a classification into three groups : + ( i ) 23 targets showed no evidence for superposition - we call these single galaxies ; + ( ii ) 15 targets appear to be superpositions of two galaxies - we call these doubles ; + ( iii ) 5 targets show evidence for more than two components - we call these multiples . figures [ a1][a6 ] show density contours ( isophotes ) obtained from the acs f775w images of these objects . two panels are shown for each object . the panels on the left show fields - of - view that are approximately @xmath20 arcsec@xmath11 ( north is up , east is to the left ) , and the contours are linearly spaced in magnitude ( logarithmically spaced in flux ) . the solid circle shows the angular size of the sdss fiber ( 3 arcsec in diameter ) . this is the scale within which the velocity dispersion was measured ( this measured value is aperture corrected to @xmath21 - see bernardi et al . 2006 for details ) . light from objects outside the circle is very unlikely to affect the velocity dispersion and absorption line - index measurements . the panels on the right show the central arcsecond , and the contours are linearly spaced in flux . in these panels , we specify if the object was classified as a single . these figures illustrate that the classification into singles , doubles and multiples is relatively straightforward . table [ tab : classify ] provides details of these classifications . .the 43 objects with velocity dispersions larger than 350 km s@xmath1 from bernardi et al . ( 2006 ) which have hst images . id@xmath22 identifies the single objects whose properties are given in table 2 . n@xmath23 gives the number of objects inside a circle of 3 arcsec in diameter . env = 0,1 means low- , high - density ( see text for details ) . prof = c , p , d means core , power - law , obvious presence of dust ( from hyde et al . 2008 ) . + [ cols="^,^,^,^,^ " , ] we would like to thank the referee for suggestions which improved the paper . we thank the hst support staff during cycles 13 and 14 during which the snap-10199 and snap-10488 programs were carried out . support for programs snap-10199 and snap-10488 was provided through a grant from the space telescope science institute , which is operated by the association of universities for research in astronomy , inc . , under nasa contract nas5 - 26555 . j. h. , a.f . and m.b . are grateful for additional support provided by nasa grant ltsa - nng06gc19 g . funding for the sloan digital sky survey ( sdss ) and sdss - ii archive has been provided by the alfred p. sloan foundation , the participating institutions , the national science foundation , the u.s . department of energy , the national aeronautics and space administration , the japanese monbukagakusho , and the max planck society , and the higher education funding council for england . the sdss web site is http://www.sdss.org/. the sdss is managed by the astrophysical research consortium ( arc ) for the participating institutions . the participating institutions are the american museum of natural history , astrophysical institute potsdam , university of basel , university of cambridge , case western reserve university , the university of chicago , drexel university , fermilab , the institute for advanced study , the japan participation group , the johns hopkins university , the joint institute for nuclear astrophysics , the kavli institute for particle astrophysics and cosmology , the korean scientist group , the chinese academy of sciences ( lamost ) , los alamos national laboratory , the max - planck - institute for astronomy ( mpia ) , the max - planck - institute for astrophysics ( mpa ) , new mexico state university , ohio state university , university of pittsburgh , university of portsmouth , princeton university , the united states naval observatory , and the university of washington .

we study a sample of 43 early - type galaxies , selected from the sloan digital sky survey ( sdss ) because they appeared to have velocity dispersions of @xmath0350 kms@xmath1 . high - resolution photometry in the sdss @xmath2 passband using the high - resolution channel of the advanced camera for surveys on board the hubble space telescope shows that just less than half of the sample is made up of superpositions of two or three galaxies , so the reported velocity dispersion is incorrect . the other half of the sample is made up of single objects with genuinely large velocity dispersions . none of these objects has @xmath3 larger than @xmath4 km s@xmath1 . these objects define rather different size- , mass- and density - luminosity relations than the bulk of the early - type galaxy population : for their luminosities , they are the smallest , most massive and densest galaxies in the universe . although the slopes of the scaling relations they define are rather different from those of the bulk of the population , they lie approximately parallel to those of the bulk _ at fixed @xmath3_. this suggests that these objects are simply the large-@xmath3 extremes of the early - type population they are not otherwise unusual . these objects appear to be of two distinct types : the less luminous ( @xmath5 ) objects are rather flattened , and their properties suggest some amount of rotational support . while this may complicate interpretation of the sdss velocity dispersion estimate , and hence estimates of their dynamical mass and density , we argue that these objects are extremely dense for their luminosities , suggesting merger histories with abnormally large amounts of gaseous dissipation . the more luminous objects ( @xmath6 ) tend to be round and to lie in or at the centers of clusters . their circular isophotes , large velocity dispersions , and environments are consistent with the hypothesis that they are bcgs . models in which bcgs form from predominantly radial mergers having little angular momentum predict that they should be prolate . if viewed along the major axis , such objects would appear to have abnormally large velocity dispersions for their sizes , and to be abnormally round for their luminosities . this is true of the objects in our sample once we account for the fact that the most luminous galaxies ( @xmath7 ) , and bcgs , become slightly less round with increasing luminosity . thus , the shapes of the most luminous galaxies suggest that they formed from radial mergers , and the shapes of the most luminous objects in our big-@xmath3 sample suggest that they are the densest of these objects , viewed along the major axis . [ firstpage ] galaxies : elliptical and lenticular , cd galaxies : evolution galaxies : kinematics and dynamics galaxies : structure galaxies : stellar content

in order to improve healthcare quality for patients with several chronic conditions , the patient protection and affordable care act of 2010 instituted penalties for hospital reimbursement if a patient admitted for myocardial infarction , congestive heart failure , or pneumonia was readmitted to the institution within 30 days of the original discharge ( patient protection affordable care act 2010 ) . as such , hospitals have been faced with identifying patients in these cohorts who may be at high risk for hospital readmission and implementing interventions in hopes of improving patient care and reducing penalties that may be incurred by early readmission [ 1 , 2 ] . multicomponent interventions that feature early assessment of discharge needs have been found to be beneficial in reducing readmission rates . these multicomponent interventions have made use of education , timely transfer to primary care teams , post - acute followup between 24 and 72 hrs by nurse of physician , and appropriate referrals to support services such as rehabilitation programs and the use of home exercise programs . although these programs may be effective , the extensive time and staffing needed for their implementation and success can limit their feasibility . alternatives to one - on - one patient to healthcare provider interaction have begun to be developed to potentially allow for a greater implementation of such interventions . various telemedicine approaches , such as smartphone applications , are being considered as potential tools for allowing healthcare professionals to implement and monitor patients remotely . smartphone applications are inexpensive and , unlike other forms of telemedicine , do not require home installation . smartphone applications can be utilized not just for accessing and tracking health information but also as a tool allowing practitioners and the patient 's social support system to become more involved in his / her care without being physically present and in educational content delivery . areas where wireless health monitoring has been found to have succeeded in monitoring and tracking patients ' health have been in patients with heart failure . patient 's weight , blood pressure , and symptoms have been successfully monitored remotely by several telemedicine or structured telephone support systems . however , these studies utilized multifaceted systems that provided and received information by more than just a smartphone application . also the adoption of patients to utilize telemedicine systems found that recently discharged patients with heart failure had poor adherence of using the telemedicine system given to them after discharge . given the age and demographics of heart failure patients , it is not clear whether a strictly smartphone application would be well adopted or demonstrate similar adoption problems as other telemedicine systems . although there are potential benefits of utilizing smartphone technology for monitoring patients who are at high risk for being readmitted , the feasibility of monitoring heart failure patients or postmyocardial infarction patients via a strictly smartphone application has not yet been well documented . to our knowledge , there has been no report on the frequency of application use or potential barriers these patients may have in utilizing such technology after hospitalization . the purpose of this study was to investigate the feasibility and acceptability of a smartphone ios application to monitor and assist with patient medication compliance , education , home exercise , symptom changes , and transition to outpatient care team after hospitalization . the aim of this study was to determine the frequency of application use , potential barriers of use , and potential dropout rate in collecting this type of data in such population . this study was a qualitative study discussing the home - based feasibility and acceptability of utilizing a smartphone application to collect health information and interact with patients with chf or cad around discharge . the ios application administered daily educational material , medication reminders , doctor appointment reminders , and monitored activity level . process measurements , such as user engagement , daily task completion , and perceived value of the application to the patient , were recorded . secondary outcome measures were activity level , medication compliance , follow - up care , enrollment into support programs such as cardiac or pulmonary rehabilitation program when applicable , and 3060 day readmission rates in our population . patients were given the usual standard of care throughout the study and the ios application was only used to supplement outpatient discharge instructions and compliance , not to be used in place of the usual standard of care . patients were instructed to follow all of their doctors ' and nurses instructions and if there were any questions or confusion to contact their physician . all treating physicians were notified of their patient 's participation in the study . hospitalized patients with a diagnosis of coronary artery disease ( cad ) or congestive heart failure ( chf ) were recruited . patients were not considered for enrollment until clinical staff informed the study personnel that the patient would be eligible for discharge within the next 3 days . study exclusion criteria consisted of a lack of described diagnosis , inability to perform physical activity , unstable angina , neurological deficit that makes the individual unable to understand and follow directions , being illiterate , non - english - speaking , and no home wifi connection . physicians and nurses working on the inpatient cardiac units identified 180 patients for the study team who were admitted with a primary diagnosis of cad or chf and were eligible for discharge . the study team then approached the patients and screened them for patient interest and eligibility . the study staff made it clear that participation was completely voluntary and all usual care would continue regardless of study participation . if the patient demonstrated interest in participation , the study staff informed the patient of what study participation would involve and received his / her consent to participate . all participants signed informed consent prior to participating . once patients consented to participating in the study , either the ios application ( wellframe application by wellframe , cambridge , ma ) was uploaded to their smartphone or , if the patient did not own a device that could operate an ios application , an ipod touch ( ipod touch model a1367 , apple inc . , cupertino , ca ) was lent to the participant for the duration of the study . a one - page instruction sheet was also given to the patient and the patient was instructed to practice using the application during their hospital stay . study staff then followed up with the patient prior to discharge to ensure that there were no further questions regarding the use of the application . figure 1 demonstrates the study personnel follow - up phone call protocol to collect information on rehospitalization , symptoms , and connection with outpatient care team . each day the participants received reminders to take their medication at self - selected times , brief condition specific educational videos , and readings , and when relevant participants received reminders for upcoming appointments with healthcare providers . additionally , participants could report changes in symptoms ( e.g. , dyspnea ) and biometric measurements ( e.g. , heart rate ) and track their physical activity through the ios application 's pedometer . patients were considered compliant if greater than 50% of the daily to - do tasks were completed . figure 2 depicts an example of the application 's daily to - do tasks . the time of day the patient takes his or her medication was programmed into the application . each day , at the programmed time , a medication reminder would appear on the patient 's smart phone or ipod touch . if the patient selected yes , then a second reminder would appear on the phone or ipod touch an hour later . educational material was given to the patient daily via the patient 's daily to - do 's . the patient would be prompted to click on the educational reading material or video . once the patient viewed the educational material , a check would appear on his or her to - do list to demonstrate that task had been completed . the educational material consisted of disease management , smoking sensation , importance of attending cardiac or pulmonary rehab programs , and potential psychosocial issues associated with heart disease . the patients were also sent daily messages encouraging him or her to perform daily walking , stretches , and light strengthening exercises ( home based cardiac rehabilitation program ) [ 12 , 13 ] . when the patient tapped the prompt on his / her to - do list to perform his / her daily exercises , he / she was then taken to a second screen that included instructions for the exercises , videos for the stretches and light strengthening exercises , and a pedometer for walking . at the end of the exercise regimen , the patient was asked to enter his / her level of breathlessness based on a modified borg scale of perceived exertion . for safety , the research team monitored the patient 's exercises remotely and if a patient reported a level of breathlessness higher than 4 ( somewhat severe ) , reported a heart rate exceeding 150 bpm , or had any adverse symptoms ( e.g. , dizziness , nausea , headache , chest discomfort , lightheadedness , drop in blood pressure , unusual heartbeat , or palpitations ) the medical director of the cardiac and pulmonary rehabilitation program here at new york presbyterian hospital was alerted and a plan was in place to contact the patient . patients were instructed to forgo the exercise program if they began a cardiac rehabilitation program . daily survey questions were asked regarding breathlessness , overall control of health , ease of using the application , medication side effects , and biometric measurements . biometric measurements included weight , blood pressure , and heart rate . during the weekly phone calls , the study staff would ask the patient if he or she had been enrolled in a cardiac rehabilitation program or had any upcoming doctor appointments . if the patient responded in the affirmative , then the staff would ask for the dates and times and enter the appointments into the patient 's application via the dashboard . staff also surveyed the patient to if he or she found the application useful and how is it most helpful . lastly , the staff would inquire if the patient has seen his / her physician during the past week and if he or she has been recently hospitalized ( if yes , then why ) . if the patient could not be reached after three attempts ( over the course of 3 days ) , then a person the patient had designated as an acceptable emergency contact person for the study was contacted to confirm the patient 's safety and if he or she had been hospitalized . patient data was uploaded to a remote dashboard for the study staff to view and send messages to the patient via a secure server ( approved by columbia university information technology department as a hippa compliant and secure server approval forms attached ) . data was uploaded real time and the study staff would contact the patient via the application 1 - 2 times per week to provide encouragement . the study team could also request a response from a patient via the messaging system on the dashboard and modify a patient 's medication reminders or exercise protocol if necessary via the dashboard or by contacting wellframe . demographics , anthropometry , and ejection fraction and information about the patient 's hospital stay were obtained by reviewing the electronic hospital chart . information about any complications during the patient 's stay , breath sounds by physical exam , and medications were retrieved from the physicians and/or nursing notes . for day of discharge information , notes within 24 hrs of discharged were considered acceptable and data from that note were retrieved . the pain scale and resting dyspnea scores were collected from the physical therapist 's note on the day of discharge or the day prior to discharge if there was no physical therapy note provided at the day of discharge . sleep quality and self - report description of healthy values were obtained via the wellframe application at the day of discharge . all patients were asked to respond to the daily beat questions on the day of discharge so that the study team could ensure that the application was working properly . we tested the feasibility of using this application in patients with chf or cad after hospitalization by collecting data on the frequency of application use , usage barriers described by the patient population , study dropout rate , and type of data patients were more or less likely to provide . we selected to analyze standard ethnographic and user data . application usage was described by analyzing the frequency of response to symptom and biometric data survey questions , medication reminders , clicks on educational content , pedometer readings , and clicks of stretches and strengthening exercise videos . the logging in of system usage to detect adherence has been utilized in other telemedicine studies [ 11 , 16 , 17 ] . acceptability was tested by collecting data on application usage and types of questions patients choose to respond to about their health . to better define the type of patients that may be more or less likely to utilize the application , objective health parameters and self - described health status were collected . nonnumeric variables ( insurance , dyspnea , breath sounds , and description of health ) were coded by severity . a linear regression test was used to determine whether any of the variables collected had a relationship with the amount with which a patient utilized the application . twenty - two patients who were identified as eligible for the study were not approached because they were asleep or with a treating physician when study personnel attempted recruitment . in all of these occurrences the study personnel attempted to return to the patient 's room for recruitment ; however , the patient had been discharged . figure 3 depicts the breakdown of patients approached , declined participation , met exclusion criteria , and included . of the 158 patients approached , 16 were enrolled in the study ( 12 m , 4 f , age 55 18 years ) . of the 16 patients , two were african american , one was asian , one was hispanic , and twelve were caucasian . . table 2 describes each patient 's demographics , diagnosis , and socioeconomic status based on insurance provider . ten of the patients who participated in the study had a diagnosis of cad and were hospitalized for a cardiac intervention . the number of days patients interacted with the application after discharge and the characteristics of the patient 's health are described in table 3 . the five patients who were readmitted to the hospital during the study duration ( average of 7 days after discharge ) did not utilize the application once discharged from the hospital . of the remaining patients , all who were not readmitted , the application was utilized between 1 day and the complete 60 days . the reported estimated ejection fractions by echo ( ef ) ( taken after intervention when applicable ) revealed that the majority of our patients had an ef of > 55% except for 4 patients who had efs of < 45% . of note , the patients who did not interact with the application were also the patients with more severe complications and complaints during their hospital stay , with the exception of one . this may reflect that sicker patients were less likely to utilize the application . during the study , five patients ( 31% ) were readmitted to the hospital , with the average readmission time of 7 days . of note , all five patients only interacted with the application while being in the hospital and did not interact with the application once discharged . of the 11 other patients , who were not readmitted during the course of the study , 8 interacted with the application within the first day after discharge , 1 interacted with the application 3 days after discharge , and 2 interacted with the application greater than 1 week after discharge ( table 1 ) . ten patients withdrew from the study prior to day 60 ; however , of these ten patients , five agreed to participate in the 60-day follow - up survey to verify if he or she had been hospitalized within 60 days after discharge . retrospective chart review confirmed that all four patients were not readmitted to the hospital within 60 days of discharge . results demonstrated that patients with unstable health after discharge had a lack of application use . all patients who were readmitted during the study did not utilize the application once discharged . these results are not suggesting a causational relationship but a correlative relationship , where application use may be a good indicator of overall health status . other correlatives of application use were breath sounds by physical exam within 24 hrs of discharge and the patient 's self - report of health status at the day of discharge ( table 4 ) . analysis revealed that decreased breath sounds or crackles by physical exam within 24 hrs of discharge had a significant relationship with application use ( r = 0.370 , p = 0.021 ) . the patient 's self - report of his or her health status at the day of discharge also had a significant relationship with application use ( r = 0.335 , p = 0.038 ) . breath sounds and self - report of health were independent predictors of application use and could explain 79% of the variability in application use when modeled together ( r = 0.625 , p = 0.02 ) . the patients that found the application helpful also utilized the application the most and remained in the study the longest . reasons patients gave to why the application was not helpful were the inability to change medication reminder times , the inability to enter doctor 's appointments or other reminders themselves ( the study team would have to enter these reminders into the dashboard and then the patient would receive the reminder ) , the pedometer would stop counting if another application on the device was opened ( this is a limitation of ios software design ) , and the general inconvenience of being asked to use the application on a regular basis . unfortunately , the inconvenience of entering data for a research study is a common limitation to participant compliance . positive responses to application use were the usefulness of the medication reminders , the educational information provided in the daily beat , and the stretching and exercise videos . sixty - nine percent of the patient population utilized the application during week one ; however , the percent of relative frequency of use diminished to only 19% by week 7 , demonstrating poor adherence over time ( figure 4(a ) ) . during week 1 , the patients answered the application questions with a median of 42% of the time . over time , compliance diminished to a nadir of 27% ( figure 4(b ) ) . on average , those patients utilized the medication reminders 37% of the time , read education material 44% of the time , answered survey questions through the application 55% of the time , and performed the recommended physical activity 25% of the time . four patients completed 3160 days of the trial and utilized medication reminders 53% of the time , read education material 53% of the time , answered survey questions through the application 93% of the time , and performed the recommended physical activity 42% of the time . the data reveals that the patients who completed 3160 days of the trial utilized the application more than those who withdrew prior to day 31 . patients who answered most of the survey questions continued to answer most of the survey questions throughout the study protocol . patients who answered fewer than half of the survey questions in the first week proceeded to drop out to the study the following week . a common theme of patients who completed greater than 31 days was the presence of a family member during study recruitment . it appeared that when the patient 's family support valued the patient utilizing the application , the patient was more likely to utilize the application for > 31 days and be more compliant with the use of the application . both groups participated with the survey tool that requested the patient to rate his or her breathlessness , take his or her pulse , enter his or her weight , describe his or her health that day , and respond to the ease of using the application 's feature ( table 4 ) . the patients who remained in the study the longest were the most compliant in answering these survey questions . patients were more likely to answer the questions about shortness of breath , entering their weight and describing their health , and least likely to answer the questions regarding the ease of using the application or how in control of their health they felt they were ( table 4 ) . in the patients who withdrew prior to day 31 , they utilized the educational material the most and the physical activity aspect of the application the least . the patients who completed 3160 days of the trial utilized the medication reminders and educational material equally . this study has shown that collecting information regarding postdischarge compliance and patients ' health status via smartphone application in patients with heart failure or coronary artery disease may be feasible but not without limitation . our results indicate that patients who were medically stable were more likely to utilize the application than patients who are unstable . results also demonstrated that patients were more likely to respond to medication compliance questions , read education content , and respond to a few survey questions but not all and were less likely to report physical activity through the application ( table 5 ) . reported a smart phone application median compliance rating of 41% in their population of women undergoing treatment for breast cancer . reported a 90% adherence in telemonitoring use in a population of patients with heart failure during the first week of the study but adherence decreased to ~55% by week 26 . the low application compliance reported by this and other studies may reflect that although remote monitoring is convenient , the sample sizes needed for such research may be larger than those of other forms of survey tools or interventions . therefore , future research in the field of remote monitoring may want to consider this low compliance rate when calculating desired sample sizes . compliance results also revealed higher acceptability rate in patients who remained in the study for greater than 31 days versus those who withdrew prior to 31 days . this relationship revealed a subset of patients who were more likely to utilize smart phone applications than others . . found that cellular network , time of day , and previous app use are all highly related to application usage . hospitals that are seeking to utilize this kind of technology to track and interact with high risk patients may want to take into account these factors to optimize usage . companies seeking to design applications for this use may also want to take into account these factors when designing their application . factors that impacted acceptability or barriers for usage were reported to be the inability to interact with the application as much as the individual required . as the patient 's health and needs evolved , the application needed to be able to evolve . these findings demonstrated a utility with smartphone applications to identify patients that need a care team to intervene rather than relying on technological remote monitoring . , remote monitoring of patient 's with hf health does not appear to impact the course of the patient 's health unless monitoring dictates an action . even when the remote monitoring dictates an action , study results have not always been positive . telemonitoring did not appear to provide a benefit over usual care when used to decrease rehospitalization . therefore , remote monitoring appears to be most useful in highlighting changes in behavior , rather than eliciting changes in outcomes . thus , data collected by remote monitoring may be most useful for hospitals that are looking to allocate resources towards the patients who are most likely to be readmitted , rather than replacing usual care . these results are not suggesting a causational relationship but an associative relationship between health status and application use . it is important to stress that smartphone applications may be most successful in helping to bridge the communication between care team and patient rather than be used to replace the need for one - to - one in - person interaction . a novelty of this application to the growing telemedicine market was the immediate feedback mechanism via the application to a dashboard the clinician can log into , rather than other immediate feedback systems such as phone or video conference . additionally , the telemedicine systems that involve home setup can cause a delay in information being received by the hospital . the average readmission time in our patient population was 7 days and mode was 3 days , and thus there was value in the ability to follow patients ' status upon immediate discharge . for the above reasons , more of the remote monitoring market is moving to application use . the results from this study can help guide researchers , administrators , and companies in what aspect of the application appeared to be valued by the patient , such as medication reminder and educational content , and what aspects were underutilized , such as the pedometer and ability to communicate with the study team via the application . a barrier to utilizing certain telemedicine devices discussed in prior research has been the barrier of training staff and patients on how to use the technology appropriately and in a timely fashion . some physicians expressed frustration with the time and level of technological sophistication needed to utilize certain technology . a benefit to this particular application was the intuitive and simple user interface that took almost no training . however , this application was very limited in the information the clinician can gain from it . perhaps future versions or application will include interfacing with diagnostic equipment that can provide a pulse rate , distinguish an arrhythmia , and allow for photographs to be uploaded to the dashboard . this would expand the use of the application beyond distinguishing the patient 's general health state . described the incremental costs of using some telemedicine systems as being greater than the benefit in some settings . with each interface that an application builds , the cost increases . also the ethics of attempting to replace in - person interaction with a multidisciplinary team in high risk patient populations , such as the one studied , should be considered . however , the use of such applications as a tool to extend the reach of the care team , rather than a replacement , may allow for an inexpensive and manageable technique to identify patients who are in need of such in - person care . our patient population was not representative of the average patient here at new york presbyterian as our initial version of the application was only in english . since the completion of the study a spanish version has been developed . further research is needed to determine if these findings can be extrapolated to the spanish speaking population . it is our suggestion that future work should consider a data plan that allows the patient to utilize the device with or without wifi , although this feature does add a further expense . future work in a larger and more diverse population may be beneficial to confirm the relationships reported in these findings and allow for findings to be extrapolated to other patient populations . lastly , the use of such application as a survey tool was useful however limited . as a test of feasibility , the survey tool demonstrated that patients would respond to the daily questions and what questions the patients preferred ; however , the applicability of these responses was limited . this study demonstrated the feasibility and acceptability of utilizing an ios application to monitor outpatient behavior in a group of patients considered to be at high risk for readmission . findings demonstrated that patients with stable health utilized the application more than patients with unstable health . there remains a need to better define aspects of smart phone applications that will result in optimal patient compliance ; however , these results demonstrated that usage alone may be a useful tool to highlight patients in need of closer monitoring .

the purpose of this study was to determine the feasibility and acceptability of utilizing a smartphone based application to monitor compliance in patients with cardiac disease around discharge . for 60 days after discharge , patients ' medication compliance , physical activity , follow - up care , symptoms , and reading of education material were monitored daily with the application . 16 patients were enrolled in the study ( 12 males , 4 females , age 55 18 years ) during their hospital stay . five participants were rehospitalized during the study and did not use the application once discharged . seven participants completed 130 days and four patients completed > 31 days . for those 11 patients , medication reminders were utilized 37% ( 130-day group ) and 53% ( > 31-day group ) of the time , education material was read 44% ( 130 ) and 53% ( > 31 ) of the time , and physical activity was reported 25% ( 130 ) and 42% ( > 31 ) of the time . findings demonstrated that patients with stable health utilized the application , even if only minimally . patients with decreased breath sounds by physical exam and who reported their health as fair to poor on the day of discharge were less likely to utilize the application . acceptability of the application to report health status varied among the stable patients .

the traditional narrow definition of health ( in terms of mortality and serious morbidity ) has been replaced by a much broader definition which encompasses " physical , mental and social well - being , and not merely the absence of disease or infirmity " . steadily decreasing maternal and perinatal mortality rates in developed countries over the last few decades have led to a growing expectation that pregnancy and childbirth should at the very least result in a live mother and baby . while such outcomes are expected in many countries , they can never be taken for granted , and the corresponding levels of dissatisfaction when the clinical outcome is poor have resulted in rising levels of complaints and litigation . nevertheless , the focus of antenatal care in developed countries has expanded from its traditional aim of preventing , detecting and managing problems and factors which might adversely affect the health of mother and/or baby . it now includes broad aims such as " to support and encourage a family 's healthy psychological adjustment to childbearing " , and " to promote an awareness of the sociological aspects of childbearing and the influences that these might have on the family " . this broader approach echoes the development of ' quality of life'-focussed assessments in the wider field of health care . within maternity care , one of the main areas of interest to researchers has been women 's satisfaction levels with their care . however , this reliance on gauging satisfaction levels for both antenatal and postnatal care has recently been criticised , particularly when this approach is used as a driver for planning the future provision of services . perhaps surprisingly , given the growth of quality of life scales in other areas of health care , there has until recently been no tool specifically devised for general use in the maternity care setting . this situation has been rectified recently with the development of the mother - generated index . some of the hesitation in developing such a tool may have stemmed from the slightly ambivalent position of maternity care in developed countries . perhaps uniquely in the health care setting , the context is generally not one of disease but of normal physiology . however , despite this lack of a specific tool , a number of studies have commented on women 's quality of life , particularly during pregnancy . this paper now reviews articles identified by medline , cinahl and bids which contained the terms ' quality of life ' and either ' pregnancy ' , ' antenatal ' or ' postnatal ' in their abstract or title . dow et al assessed quality of life and treatment outcome among three breast cancer patients treated with conservative surgery and radiation in the usa . they compared the results for these women , who had become pregnant , with those of 23 matched patients who had not become pregnant . ferrans and powers ' quality of life index was used in conjunction with the adaptation to surviving cancer profile , and the parenting stress index . ferrans claims that " quality of life depends on the unique experience of life for each person . individuals are the only proper judge of their quality of life , because people differ in what they value . " dow et al concluded that family issues had the greatest impact on quality of life , and that women who became pregnant following breast cancer treatment were not at higher risk for parental stress than the normal population . shulman et al report a case study of one woman with parkinson 's disease in the usa who became pregnant . they used quantitative neurologic and quality - of - life scales in the antenatal , intrapartum , and postnatal periods , but do not specify in the abstract which qol scale was used . magee et al report the development in canada of a 30-item 4-domain health - related quality of life questionnaire for women suffering nausea and vomiting in pregnancy . the four domains are physical symptoms / aggravating factors , fatigue , emotions , and limitations . their study population consisted of 500 women who had called a telephone help line for those experiencing nausea and vomiting in pregnancy . feeny et al compared the health - related quality of life scores of 126 women undergoing either chorionic villus sampling or amniocentesis in canada . they conducted a series of interviews ( at 8 , 13 , 18 , and 22 weeks gestation ) , but do not specify in their abstract which tool was used for this , and again this journal was unavailable to the author . coffey et al examined the impact of pregnancy ( as well as of dietary restrictions and preoperative diagnosis [ ulcerative colitis vs. familial adenomatous polyposis ] ) on 64 patients undergoing ileal pouch - anal anastomosis in ireland . they concluded that women who had pregnancies after this surgery had the lowest quality of life scores ( as measured by the cleveland global qol score ) , reflecting the importance of non - pouch - related factors after ileal pouch formation . the only report of a tool specifically devised for use related to pregnancy or the period following childbirth is one devised and tested in two phases in scotland by the author ( study samples were n = 103 and n = 102 ) . the mother - generated index is devised for use in the postnatal period ; in this single - sheet three - step questionnaire the mother identifies what is most important to her quality of life having had a baby , and scores these areas . based on the patient - generated index , the idea of this tool is to get away from pre - defined lists of variables or symptom checklists , and instead ask the mother what she thinks . the intention is to identify her experience and reflect her sense of values about those aspects of her life which she says are important . intended for use along with standard checklists of physical or psychological well - being , the belief is that this approach will encourage a more holistic view of the woman in question . a number of studies have examined quality of life ( qol ) through the perspective of other assessments of well - being , the most frequently cited tool being the sf-36 . this is described by the medical outcomes trust as a ' generic instrument ' , as opposed to its six identified qol tools which cover ' condition - specific ' areas adult asthma , pediatric asthma , 24-hour migraine , migraine - specific qol , angina , and urinary incontinence . the sf-36 's eight sub - scales are : limitations in physical activities because of health problems ; limitations in usual role activities because of physical health problems ; bodily pain ; general health perceptions ; vitality ( energy and fatigue ) ; limitations in social activities because of physical or emotional problems ; limitations in usual role activities because of emotional problems ; and mental health ( psychological distress and well - being ) . quality of life may be affected by any or all of these , but is not specifically mentioned . looking specifically at pregnant and newly - delivered women with hiv , larrabee et al aimed to describe perceived quality of life and functional status . their study of 21 asymptomatic hiv - positive women ( and 21 hiv - negative controls ) in the usa used an abbreviated 30-item version of the sf-36 . they concluded that perceived quality of life is lower in hiv - positive women , less so in the antenatal period , but increasingly so as " pregnancy , the disease process , and other life events specific to delivery and the postpartum period interact . " hueston and kasik - miller used the sf-36 ( " a standard quality - of - life measure " ) in a longitudinal study of 125 pregnant women in the usa , referring to " serial assessments of health - related functional status " . they found that only the scores relating to physical measures of health changed significantly during pregnancy , a finding of uncertain significance in terms of quality of life for a population who are essentially healthy . schover et al , in their us survey of 43 men and 89 women with cancer , describe the sf-36 as a " standardized measure of health - related quality of life . " the generally good sf-36 scores ( compared with normative data for healthy americans of similar age ) are ascribed to these patients having survived cancer and being disease - free . this study only refers to pregnancy in terms of some women fearing that it may trigger a recurrence of the cancer . maclennan et al used the 1998 south australian health omnibus survey to determine the prevalence of pelvic floor disorders . they found that these were strongly associated with the female gender , ageing , pregnancy , parity , instrumental delivery , and quality of life scores . they used the sf-36 to assess these , although this is not stated in the abstract . ciardi et al claim that the sf-36 " was used to describe general health status and quality of life " in their us study of eight pregnant women involved in an assessment of an antenatal exercise programme , although they make no claim about quality of life in their abstract results or conclusions . rumbold & crowther aimed to identify any reduction in perceived quality of life in australian women diagnosed with gestational diabetes . they used the sf-36 ( a " health survey " ) together with the six - item short - form of the spielberger state - trait anxiety inventory and the edinburgh postnatal depression scale . they found that women who screened positive for gestational diabetes had lower health perceptions than women who tested negative . they were also more likely to rate their own health at a lower level , and less likely to rate their health as ' much better than one year ago ' . however , the authors ' conclusions are that it was these women 's perception of their own health that was adversely affected , rather than their quality of life being affected . attard et al used the sf-36 ( which they refer to as the ' short form-36 qol survey ' ) in an observational , multi - centre prospective cohort study of canadian women with nausea and vomiting in pregnancy . they found that scores for these women were lower in all eight domains , and that the degree of limitation was associated with symptom severity . apart from the sf-36 , other tools have been used as an indicator of quality of life . hunfeld et al claimed in their dutch study that pregnant women with a previous pregnancy loss ( n = 24 ) had a lower quality of life than pregnant women who had not had such a loss ( n = 26 ) . this assessment was made before and after mid - trimester ultrasound scan ; quality of life was " revealed " by feelings of social isolation , negative emotional reactions , and pain , although they do not specify in the abstract which tool(s ) they used , and this article was unobtainable . aslan et al used the international prostate symptom score ( ipss ) , a seven - symptom assessment scale of urinary symptoms , in an assessment of 256 pregnant and 230 non - pregnant healthy women in turkey . their abstract mentions no other tools , and yet the abstract refers to quality of life findings . this article was unavailable to the author , and i could not ascertain whether such a finding was supported by any measurement other than urinary symptoms . simko and mcginnis sought to describe the quality of life in 124 patients in the usa with congenital heart disease ( chd ) , hypothesising that advances in health care mean there are more adult survivors with chd , and that pregnancy concerns are pertinent to this group . this is described as a " behaviorally - based , health status questionnaire " , covering everyday activities in 12 categories . these are sleep and rest ; emotional behavior ; body care and movement ; home management ; mobility ; social interaction ; ambulation ; alertness behavior ; communication ; work ; recreation and pastimes ; and eating . from their findings these authors claim that the sickness impact profile can be used to assess " quantitative and subjective quality of life " in adults with chd . a number of articles used the term ' quality of life ' in their abstract , but did not address it specifically . it has frequently been used in a relatively loose manner , with the assumption made that from the existence of certain circumstances one could deduce that quality of life had been improved or hindered . a number of these articles referred to a prolonged life expectancy from a radical therapy or a previously fatal condition . frde reports a norwegian study of 65 pregnant women which examined the incidence and significance of minor ailments during pregnancy . the abstract notes that " pregnant women 's ailments may cause anxiety and reduce the quality of life " . the findings indicated that certain women ( notably those with psychosocial problems and heavy physical work ) were more likely to report a higher number of ailments , and the author concludes that when such ailments are volunteered by women , clinicians should consider the need for psychosocial support . in this case there is an assumption that an increased number of ailments equates with a lower quality of life , although quality of life as such is not formally assessed . morita et al assessed pregnancy outcome in japanese women who had undergone renal transplantation . they claim from their analysis of eight pregnancies that " female renal allograft recipients have a better quality of life because they can safely deliver a child if they observe the criteria for pregnancy [ which have been ] established for renal allograft recipients . similarly , jordan & pugh report a case study of one 22-year old woman who safely delivered a healthy infant four years after receiving a donor heart . they state that longer - term survival in heart transplant recipients has improved their quality of life , and that pregnancy once thought to be contraindicated can now be considered . miniero et al claim that improvements in surgical techniques and immunosuppression have improved both survival and quality of life in patients who have undergone organ transplantation . this has meant that women of child - bearing age who have been the recipients of an organ transplant are now more likely to have the option of planning a pregnancy . this italian study examined pregnancy outcome in the case of 42 women who had received a donor kidney . crude outcome measures ( type of delivery ; number of live births ; infant birthweight ) were collected and compared with population means . the authors concluded that these women were more likely to experience spontaneous abortion and preterm delivery , and to have babies of low birthweight . however , in this study no congenital defects were identified , and infant development appeared to be normal . this study appears to equate longer survival in these patients , and their improved chance of carrying a pregnancy to a successful conclusion , with improved quality of life . there is no report of a subjective assessment of these women , or how they interpreted these outcomes . in a similar vein , yamamoto et al note that both life expectancy and quality of life have improved for people with spina bifida , and that as a result pregnancy is becoming more common in adolescent and adult female patients . from their analysis of six deliveries in japan above , the very possibility of a pregnancy resulting in a live birth seems to have been taken as recognition that quality of life has been improved for these patients . also in this vein , anselmo et al describe the cases of six women in italy with hodgkin 's disease who , following chemotherapy and/or radiotherapy experienced precocious menopause , and yet managed to carry a pregnancy successfully to term . this was thanks to oocyte donation , in vitro fertilization and intrauterine embryo transfer or oocyte intracytoplasmic insemination . the authors assert that they " set the goal of improving the quality of life of these patients " , and imply again that a pregnancy followed by a live birth represents success in these terms . skordis et al similarly describe a cypriot study of pregnancy outcomes in 62 women with thalassaemia . that 81 of the 90 pregnancies ended successfully is taken as encouraging evidence of the prospect of an improvement in quality of life for this group of patients . shimaoka et al sought to investigate " the quality of life during and after pregnancy of ... patients who had undergone kasai operation . " their study involved a survey of 134 institutions affiliated to the japanese biliary atresia society . their results indicated that even when patients with biliary atresia had made a successful recovery after kasai surgery , unexpected complications still occurred when they become pregnant . quality of life issues for these patients are inferred from the reports of clinical practitioners regarding pregnancy and delivery complications . thomas and napolitano report a case study of one 23 year - old primigravid woman in the usa who , despite opiate analgesia , was incapacitated by severe and chronic pelvic pain . acupuncture was successfully employed , with the authors claiming that by allowing her to maintain normal activity her quality of life had been improved . while it is difficult to argue with this conclusion , again no specific quality of life measurement appears to have been made . mrkved et al used a self - report of urinary incontinence as a cipher for quality of life assessment in a study of 301 pregnant women in norway . as with the thomas and napolitano study , it is difficult to deny that the clinical condition described ( in this case urinary incontinence ) is indeed a debilitating condition which impacts adversely on a person 's quality of life , but again there is no formal quality of life approach . while the studies in the above section discussed actual pregnancy outcomes , for a number of other studies it is the possibility of pregnancy and childbirth , rather than their occurrence , which is taken as the outcome measure . in one sense these articles are very similar in approach , in that they discuss an outcome which , thanks to advances in medical and surgical treatment , can now be considered . gantt describes a study of 13 women with congenital heart disease ( chd ) in the usa . similar to the simko and mcginnis study reported above , it relates the concerns of young women with chd about the possibility of pregnancy , but rather than using an established tool ( simko and mcginnis used the sickness impact profile ) , gantt used a grounded theory approach to address the question of ' quality of life issues ' . geldmaker claims that " medical advances in disease management have improved quality of life for women with cystic fibrosis and now enables them to consider pregnancy . " having assumed that quality of life has been improved , the author goes on to describe how grounded theory and a ' complementarity research technique ' were used to survey twelve women who had been recruited over the internet and through a cystic fibrosis newsletter . the tools used in this study were questionnaires for demands of illness and self - care of cystic fibrosis , followed by semi - structured telephone interviews . the above section examined research studies that had addressed the possibility of pregnancy in certain identified groups . a number of other articles concern the possibility of pregnancy , but do not approach this from the point of view of a single study . gulati and van poznak carried out a medline review of reported pregnancies in women who had undergone bone marrow transplantation . they note that high - dose chemotherapy and radiation treatment are associated with gonadal dysfunction , and that questions of fertility are important because these patients " are often young people who wish to resume a normal quality of life , which for many patients involves the desire to have children " . here the equation is made between having children and quality of life . they examined the " aetiology , epidemiology , diagnosis , clinical course , treatment and prognosis of peripartum cardiomyopathy , " noting that improvements in medical care and treatment have significantly improved the quality of life and survival of those experiencing this serious complication . schover conducted a literature review concerning " cancer survivors ' concerns about infertility and childbearing " , as a means of generating hypotheses . among these are that survivors diagnosed in adolescence will be more anxious about parenthood ; that women will be more distressed over infertility and more concerned about their children 's health than men ; and that survivors who rate their overall quality of life more negatively will be less concerned about infertility and more apt to decide to forego parenthood . arsenault et al conducted a medline and cochrane database review to examine the evidence - based management of nausea and vomiting in pregnancy . they concluded that this condition has a profound effect on women 's health and quality of life during pregnancy , as well as a financial impact on the health care system . trachter et al present a general description of concerns of women with inflammatory bowel disease and how this impacts on their quality of life , with particular reference to partner relationships and sexual health . they include case studies as a way of revealing some of these concerns , and , in order to improve the quality of life and well - being of these women , they call for additional research to evaluate their relationship difficulties , sexual comfort , and sexual behaviours . several articles refer to quality of life issues in pregnancy in a very general way . an article by kaneko entitled ' pregnancy and quality of life in women with epilepsy ' does not mention quality of life in the abstract , instead reporting that pregnant women who have epilepsy have legitimate concerns regarding the effects of antiepileptic drugs on the fetus . in this case it seems to be assumed that concerns about teratogenic effects indicate a reduced quality of life . barry claims that " ballet dancers have been observed to have increased difficulties in pregnancy and labour " , and goes on to present an anatomical , physiological and social analysis . the conclusion is that with appropriate intervention from certain health care practitioners ( nutritionists , doctors , nurses and midwives ) , " the ballet dancers ' quality of life , health status and professional performance can be improved . " ostgaard notes that backpain is very common in pregnancy , and claims that this " lowers the quality of life " , as well as causing absence from work . the author defines back pain and suggests a method for classifying back pain in pregnancy into two different pain types . rosenn and miodovnik describe diabetic complications in pregnancy , claiming that these " may have a tremendous impact on ... quality of life and ... ultimate prognosis . " hassey notes that " pregnancy and parenthood after treatment for breast cancer are quality of life issues that are a growing concern for long - term survivors of cancer " , and calls for " a critical review of traditional opinion against pregnancy after treatment for breast cancer " . hou discusses pregnancy in women with renal insufficiency and end - stage renal disease . the author notes the possibility of transplantation , and anticipates that increasing experience in this area will lead to more successful outcomes . if this is so , then " the possibility of parenthood will be added to the improved quality of life in these women . " graham et al note that there is a lack of awareness about the extent and effect of high levels of reproductive morbidity on the health and quality of life of women in the developing world . they go on to describe methodologies currently being developed for raising awareness at national , community , and individual levels . dow et al assessed quality of life and treatment outcome among three breast cancer patients treated with conservative surgery and radiation in the usa . they compared the results for these women , who had become pregnant , with those of 23 matched patients who had not become pregnant . ferrans and powers ' quality of life index was used in conjunction with the adaptation to surviving cancer profile , and the parenting stress index . ferrans claims that " quality of life depends on the unique experience of life for each person . individuals are the only proper judge of their quality of life , because people differ in what they value . " dow et al concluded that family issues had the greatest impact on quality of life , and that women who became pregnant following breast cancer treatment were not at higher risk for parental stress than the normal population . shulman et al report a case study of one woman with parkinson 's disease in the usa who became pregnant . they used quantitative neurologic and quality - of - life scales in the antenatal , intrapartum , and postnatal periods , but do not specify in the abstract which qol scale was used . magee et al report the development in canada of a 30-item 4-domain health - related quality of life questionnaire for women suffering nausea and vomiting in pregnancy . the four domains are physical symptoms / aggravating factors , fatigue , emotions , and limitations . their study population consisted of 500 women who had called a telephone help line for those experiencing nausea and vomiting in pregnancy . feeny et al compared the health - related quality of life scores of 126 women undergoing either chorionic villus sampling or amniocentesis in canada . they conducted a series of interviews ( at 8 , 13 , 18 , and 22 weeks gestation ) , but do not specify in their abstract which tool was used for this , and again this journal was unavailable to the author . coffey et al examined the impact of pregnancy ( as well as of dietary restrictions and preoperative diagnosis [ ulcerative colitis vs. familial adenomatous polyposis ] ) on 64 patients undergoing ileal pouch - anal anastomosis in ireland . they concluded that women who had pregnancies after this surgery had the lowest quality of life scores ( as measured by the cleveland global qol score ) , reflecting the importance of non - pouch - related factors after ileal pouch formation . the only report of a tool specifically devised for use related to pregnancy or the period following childbirth is one devised and tested in two phases in scotland by the author ( study samples were n = 103 and n = 102 ) . the mother - generated index is devised for use in the postnatal period ; in this single - sheet three - step questionnaire the mother identifies what is most important to her quality of life having had a baby , and scores these areas . based on the patient - generated index , the idea of this tool is to get away from pre - defined lists of variables or symptom checklists , and instead ask the mother what she thinks . the intention is to identify her experience and reflect her sense of values about those aspects of her life which she says are important . intended for use along with standard checklists of physical or psychological well - being , the belief is that this approach will encourage a more holistic view of the woman in question . a number of studies have examined quality of life ( qol ) through the perspective of other assessments of well - being , the most frequently cited tool being the sf-36 . this is described by the medical outcomes trust as a ' generic instrument ' , as opposed to its six identified qol tools which cover ' condition - specific ' areas adult asthma , pediatric asthma , 24-hour migraine , migraine - specific qol , angina , and urinary incontinence . the sf-36 's eight sub - scales are : limitations in physical activities because of health problems ; limitations in usual role activities because of physical health problems ; bodily pain ; general health perceptions ; vitality ( energy and fatigue ) ; limitations in social activities because of physical or emotional problems ; limitations in usual role activities because of emotional problems ; and mental health ( psychological distress and well - being ) . quality of life may be affected by any or all of these , but is not specifically mentioned . looking specifically at pregnant and newly - delivered women with hiv , larrabee et al aimed to describe perceived quality of life and functional status . their study of 21 asymptomatic hiv - positive women ( and 21 hiv - negative controls ) in the usa used an abbreviated 30-item version of the sf-36 . they concluded that perceived quality of life is lower in hiv - positive women , less so in the antenatal period , but increasingly so as " pregnancy , the disease process , and other life events specific to delivery and the postpartum period interact . " hueston and kasik - miller used the sf-36 ( " a standard quality - of - life measure " ) in a longitudinal study of 125 pregnant women in the usa , referring to " serial assessments of health - related functional status " . they found that only the scores relating to physical measures of health changed significantly during pregnancy , a finding of uncertain significance in terms of quality of life for a population who are essentially healthy . schover et al , in their us survey of 43 men and 89 women with cancer , describe the sf-36 as a " standardized measure of health - related quality of life . " the generally good sf-36 scores ( compared with normative data for healthy americans of similar age ) are ascribed to these patients having survived cancer and being disease - free . this study only refers to pregnancy in terms of some women fearing that it may trigger a recurrence of the cancer . maclennan et al used the 1998 south australian health omnibus survey to determine the prevalence of pelvic floor disorders . they found that these were strongly associated with the female gender , ageing , pregnancy , parity , instrumental delivery , and quality of life scores . they used the sf-36 to assess these , although this is not stated in the abstract . ciardi et al claim that the sf-36 " was used to describe general health status and quality of life " in their us study of eight pregnant women involved in an assessment of an antenatal exercise programme , although they make no claim about quality of life in their abstract results or conclusions . rumbold & crowther aimed to identify any reduction in perceived quality of life in australian women diagnosed with gestational diabetes . they used the sf-36 ( a " health survey " ) together with the six - item short - form of the spielberger state - trait anxiety inventory and the edinburgh postnatal depression scale . they found that women who screened positive for gestational diabetes had lower health perceptions than women who tested negative . they were also more likely to rate their own health at a lower level , and less likely to rate their health as ' much better than one year ago ' . however , the authors ' conclusions are that it was these women 's perception of their own health that was adversely affected , rather than their quality of life being affected . attard et al used the sf-36 ( which they refer to as the ' short form-36 qol survey ' ) in an observational , multi - centre prospective cohort study of canadian women with nausea and vomiting in pregnancy . they found that scores for these women were lower in all eight domains , and that the degree of limitation was associated with symptom severity . apart from the sf-36 , other tools have been used as an indicator of quality of life . hunfeld et al claimed in their dutch study that pregnant women with a previous pregnancy loss ( n = 24 ) had a lower quality of life than pregnant women who had not had such a loss ( n = 26 ) . this assessment was made before and after mid - trimester ultrasound scan ; quality of life was " revealed " by feelings of social isolation , negative emotional reactions , and pain , although they do not specify in the abstract which tool(s ) they used , and this article was unobtainable . aslan et al used the international prostate symptom score ( ipss ) , a seven - symptom assessment scale of urinary symptoms , in an assessment of 256 pregnant and 230 non - pregnant healthy women in turkey . their abstract mentions no other tools , and yet the abstract refers to quality of life findings . this article was unavailable to the author , and i could not ascertain whether such a finding was supported by any measurement other than urinary symptoms . simko and mcginnis sought to describe the quality of life in 124 patients in the usa with congenital heart disease ( chd ) , hypothesising that advances in health care mean there are more adult survivors with chd , and that pregnancy concerns are pertinent to this group . this is described as a " behaviorally - based , health status questionnaire " , covering everyday activities in 12 categories . these are sleep and rest ; emotional behavior ; body care and movement ; home management ; mobility ; social interaction ; ambulation ; alertness behavior ; communication ; work ; recreation and pastimes ; and eating . from their findings these authors claim that the sickness impact profile can be used to assess " quantitative and subjective quality of life " in adults with chd . a number of articles used the term ' quality of life ' in their abstract , but did not address it specifically . it has frequently been used in a relatively loose manner , with the assumption made that from the existence of certain circumstances one could deduce that quality of life had been improved or hindered . a number of these articles referred to a prolonged life expectancy from a radical therapy or a previously fatal condition . frde reports a norwegian study of 65 pregnant women which examined the incidence and significance of minor ailments during pregnancy . the abstract notes that " pregnant women 's ailments may cause anxiety and reduce the quality of life " . the findings indicated that certain women ( notably those with psychosocial problems and heavy physical work ) were more likely to report a higher number of ailments , and the author concludes that when such ailments are volunteered by women , clinicians should consider the need for psychosocial support . in this case there is an assumption that an increased number of ailments equates with a lower quality of life , although quality of life as such is not formally assessed . morita et al assessed pregnancy outcome in japanese women who had undergone renal transplantation . they claim from their analysis of eight pregnancies that " female renal allograft recipients have a better quality of life because they can safely deliver a child if they observe the criteria for pregnancy [ which have been ] established for renal allograft recipients . similarly , jordan & pugh report a case study of one 22-year old woman who safely delivered a healthy infant four years after receiving a donor heart . they state that longer - term survival in heart transplant recipients has improved their quality of life , and that pregnancy once thought to be contraindicated can now be considered . miniero et al claim that improvements in surgical techniques and immunosuppression have improved both survival and quality of life in patients who have undergone organ transplantation . this has meant that women of child - bearing age who have been the recipients of an organ transplant are now more likely to have the option of planning a pregnancy . this italian study examined pregnancy outcome in the case of 42 women who had received a donor kidney . crude outcome measures ( type of delivery ; number of live births ; infant birthweight ) were collected and compared with population means . the authors concluded that these women were more likely to experience spontaneous abortion and preterm delivery , and to have babies of low birthweight . however , in this study no congenital defects were identified , and infant development appeared to be normal . this study appears to equate longer survival in these patients , and their improved chance of carrying a pregnancy to a successful conclusion , with improved quality of life . there is no report of a subjective assessment of these women , or how they interpreted these outcomes . in a similar vein , yamamoto et al note that both life expectancy and quality of life have improved for people with spina bifida , and that as a result pregnancy is becoming more common in adolescent and adult female patients . from their analysis of six deliveries in japan they note that careful urological and obstetric surveillance is required . as with the study above , the very possibility of a pregnancy resulting in a live birth seems to have been taken as recognition that quality of life has been improved for these patients . also in this vein , anselmo et al describe the cases of six women in italy with hodgkin 's disease who , following chemotherapy and/or radiotherapy experienced precocious menopause , and yet managed to carry a pregnancy successfully to term . this was thanks to oocyte donation , in vitro fertilization and intrauterine embryo transfer or oocyte intracytoplasmic insemination . the authors assert that they " set the goal of improving the quality of life of these patients " , and imply again that a pregnancy followed by a live birth represents success in these terms . skordis et al similarly describe a cypriot study of pregnancy outcomes in 62 women with thalassaemia . that 81 of the 90 pregnancies ended successfully is taken as encouraging evidence of the prospect of an improvement in quality of life for this group of patients . shimaoka et al sought to investigate " the quality of life during and after pregnancy of ... patients who had undergone kasai operation . " their study involved a survey of 134 institutions affiliated to the japanese biliary atresia society . their results indicated that even when patients with biliary atresia had made a successful recovery after kasai surgery , unexpected complications still occurred when they become pregnant . quality of life issues for these patients are inferred from the reports of clinical practitioners regarding pregnancy and delivery complications . thomas and napolitano report a case study of one 23 year - old primigravid woman in the usa who , despite opiate analgesia , was incapacitated by severe and chronic pelvic pain . acupuncture was successfully employed , with the authors claiming that by allowing her to maintain normal activity her quality of life had been improved . while it is difficult to argue with this conclusion , again no specific quality of life measurement appears to have been made . mrkved et al used a self - report of urinary incontinence as a cipher for quality of life assessment in a study of 301 pregnant women in norway . as with the thomas and napolitano study , it is difficult to deny that the clinical condition described ( in this case urinary incontinence ) is indeed a debilitating condition which impacts adversely on a person 's quality of life , but again there is no formal quality of life approach . while the studies in the above section discussed actual pregnancy outcomes , for a number of other studies it is the possibility of pregnancy and childbirth , rather than their occurrence , which is taken as the outcome measure . in one sense these articles are very similar in approach , in that they discuss an outcome which , thanks to advances in medical and surgical treatment , can now be considered . gantt describes a study of 13 women with congenital heart disease ( chd ) in the usa . similar to the simko and mcginnis study reported above , it relates the concerns of young women with chd about the possibility of pregnancy , but rather than using an established tool ( simko and mcginnis used the sickness impact profile ) , gantt used a grounded theory approach to address the question of ' quality of life issues ' . geldmaker claims that " medical advances in disease management have improved quality of life for women with cystic fibrosis and now enables them to consider pregnancy . " having assumed that quality of life has been improved , the author goes on to describe how grounded theory and a ' complementarity research technique ' were used to survey twelve women who had been recruited over the internet and through a cystic fibrosis newsletter . the tools used in this study were questionnaires for demands of illness and self - care of cystic fibrosis , followed by semi - structured telephone interviews . the above section examined research studies that had addressed the possibility of pregnancy in certain identified groups . a number of other articles concern the possibility of pregnancy , but do not approach this from the point of view of a single study . gulati and van poznak carried out a medline review of reported pregnancies in women who had undergone bone marrow transplantation . they note that high - dose chemotherapy and radiation treatment are associated with gonadal dysfunction , and that questions of fertility are important because these patients " are often young people who wish to resume a normal quality of life , which for many patients involves the desire to have children " . here the equation is made between having children and quality of life . they examined the " aetiology , epidemiology , diagnosis , clinical course , treatment and prognosis of peripartum cardiomyopathy , " noting that improvements in medical care and treatment have significantly improved the quality of life and survival of those experiencing this serious complication . schover conducted a literature review concerning " cancer survivors ' concerns about infertility and childbearing " , as a means of generating hypotheses . among these are that survivors diagnosed in adolescence will be more anxious about parenthood ; that women will be more distressed over infertility and more concerned about their children 's health than men ; and that survivors who rate their overall quality of life more negatively will be less concerned about infertility and more apt to decide to forego parenthood . arsenault et al conducted a medline and cochrane database review to examine the evidence - based management of nausea and vomiting in pregnancy . they concluded that this condition has a profound effect on women 's health and quality of life during pregnancy , as well as a financial impact on the health care system . trachter et al present a general description of concerns of women with inflammatory bowel disease and how this impacts on their quality of life , with particular reference to partner relationships and sexual health . they include case studies as a way of revealing some of these concerns , and , in order to improve the quality of life and well - being of these women , they call for additional research to evaluate their relationship difficulties , sexual comfort , and sexual behaviours . several articles refer to quality of life issues in pregnancy in a very general way . an article by kaneko entitled ' pregnancy and quality of life in women with epilepsy ' does not mention quality of life in the abstract , instead reporting that pregnant women who have epilepsy have legitimate concerns regarding the effects of antiepileptic drugs on the fetus . in this case it seems to be assumed that concerns about teratogenic effects indicate a reduced quality of life . barry claims that " ballet dancers have been observed to have increased difficulties in pregnancy and labour " , and goes on to present an anatomical , physiological and social analysis . the conclusion is that with appropriate intervention from certain health care practitioners ( nutritionists , doctors , nurses and midwives ) , " the ballet dancers ' quality of life , health status and professional performance can be improved . ostgaard notes that backpain is very common in pregnancy , and claims that this " lowers the quality of life " , as well as causing absence from work . the author defines back pain and suggests a method for classifying back pain in pregnancy into two different pain types . rosenn and miodovnik describe diabetic complications in pregnancy , claiming that these " may have a tremendous impact on ... quality of life and ... ultimate prognosis . " hassey notes that " pregnancy and parenthood after treatment for breast cancer are quality of life issues that are a growing concern for long - term survivors of cancer " , and calls for " a critical review of traditional opinion against pregnancy after treatment for breast cancer " . hou discusses pregnancy in women with renal insufficiency and end - stage renal disease . the author notes the possibility of transplantation , and anticipates that increasing experience in this area will lead to more successful outcomes . if this is so , then " the possibility of parenthood will be added to the improved quality of life in these women . " graham et al note that there is a lack of awareness about the extent and effect of high levels of reproductive morbidity on the health and quality of life of women in the developing world . they go on to describe methodologies currently being developed for raising awareness at national , community , and individual levels . the most striking aspect of reviewing the available literature is the lack of tools designed specifically for use in the general maternity care setting . indeed , the absence of any such tool was one of the drivers for developing the mother - generated index , which may itself now be adapted for use during pregnancy . its subjective nature allows a wide range of topics to be raised and assessed , reflecting the belief that it is important to try and record " the total well - being of the patient " rather than focus on clinically measurable biomedical features " . magee et al devised a health - related quality of life instrument for nausea and vomiting in pregnancy . their approach was certainly thorough , using four sources : a focus group of women experiencing this condition was conducted by the manufacturers of a drug used in its treatment ; the authors conducted a medline search ; they incorporated the views of 17 health professionals experienced in this area ; and reviewed several generic measures including the sf-36 and sickness impact profile . it is possible to argue that , despite what seems to be a comprehensive approach , this still results in a ' closed list ' , which might exclude issues important to some people 's quality of life . several studies did make use of existing explicit quality of life tools , but rather more relied on more generic instruments whose relationship with quality of life is more debatable . the various descriptions of the sf-36 ( which ranged from a " health survey " to " a standard quality - of - life measure " ) reveal an inconsistent approach which itself reflects the difficulty with defining quality of life . it is revealing that the medical outcomes trust has itself produced several quality of life tools and yet refers to the sf-36 as a ' generic measure ' . staniszewska notes that the term ' quality of life ' is often used interchangeably with ' health - related quality of life ' , ' subjective health status ' and ' functional status ' . however , all of these approaches risk defining the issues for an individual at the expense of allowing that individual to describe what is most important to him or her . we have tried to get around this difficulty by devising a tool which allows the woman in question her own subjective and qualitative evaluation of her life , while at the same time providing a quantitative assessment . this approach is advocated by muldoon et al , who suggest that qol scales should measure both objective functioning and subjective well - being . if several studies explicitly measured what they took to be quality of life , many others used the term in a very loose way , simply equating improved or reduced quality of life with a certain clinical outcome . as noted earlier , it is hard to argue that the existence of urinary incontinence does not diminish quality of life , and yet using this term without addressing its complexities more specifically is perhaps not very helpful . the individual ( indeed unique ) nature of quality of life is obscured by an assumption that a particular clinical outcome or condition is de facto good or bad for one 's quality of life . we found when testing the mgi that although different women would cite similar examples ( such as tiredness ) , the range of scores assigned to this aspect of their life was wide ; in addition mothers rated them very differently in terms of their importance . we believe this approach helps to get away from a reliance on ' symptom checklists ' which can overstate a problem or result in a medically - derived diagnosis with which the woman might disagree . the author was invited to submit a review on mothers ' prenatal and postnatal quality of life , and carried out the literature review referred to in this article .

backgroundcontemporary broad descriptions of health and well - being are reflected in an increasing appreciation of quality of life issues ; in turn this has led to a growing number of tools to measure this.methodsthis paper reviews articles cited in medline , cinahl and bids which have addressed the concept of quality of life in pregnancy and the period following childbirth.resultsit describes five groups of articles : those explicitly assessing quality of life in this area ; those using broader health assessments as an indicator of quality of life ; those articles equating quality of life with certain pregnancy outcomes in identified groups of patients ; those studies which identify the possibility of pregnancy as an outcome measure and infer from this that quality of life has been improved ; and those articles which are themselves reviews or commentaries of pregnancy and childbirth and which identify quality of life as a feature.conclusionsthe term ' quality of life ' is used inconsistently in the literature . there are few quality of life tools specifically designed for the maternity care setting . improved or adversely affected quality of life is frequently inferred from certain clinical conditions .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Electronic Privacy Protection Act''. SEC. 2. PROHIBITIONS RELATING TO INFORMATION COLLECTION DEVICES. (a) Prohibition.--It is unlawful for any person to knowingly make, import, export, distribute, sell, offer for sale, install, or use an information collection device in a manner that violates any regulation issued under subsection (b). (b) Regulations.-- (1) In general.--Not later than 120 days after the date of the enactment of this Act, the Federal Trade Commission shall issue regulations that make it unlawful under subsection (a) for any person-- (A) to knowingly make, import, export, distribute, sell, or offer for sale an information collection device, unless the device has a label that discloses in a manner that is readily apparent and understood that the device may transmit from a computer information that is identifiable to that computer, to a primary user of that computer, or to an individual who operates that computer but is not a primary user thereof; (B) to knowingly install an information collection device on a computer that is not under general management and control of that person, unless that person in accordance with regulations issued under paragraph (2)-- (i) has given a primary user of that computer notice of such installation; and (ii) after providing such notice to a primary user, has obtained the consent of the primary user to such installation; or (C) to knowingly use an information collection device to transmit from a computer that is not under general management and control of that person, any information that is identifiable to that computer, to a primary user of that computer, or to an individual who operates that computer but is not a primary user thereof, unless that person in accordance with regulations issued under paragraph (2)-- (i) has given a primary user of that computer notice that the device may transmit such information; and (ii) after providing such notice to a primary user, has obtained consent by the primary user to such a transmission. (2) Notice and consent.--For purposes of notice and consent required by paragraph (1), regulations shall require that-- (A) notice be given and consent be obtained for each instance of installation or use of an information collection device; and (B) consent is effective only if the person obtaining the consent has a good faith belief that the person giving the consent-- (i) has attained 18 years of age; and (ii) has authority to give such consent. (c) Limitation on Application of Regulations.--Regulations issued under subsection (b)(1)(A) shall not prohibit the making, importation, exportation, distribution, sale, or offer for sale of any information collection device made before the date of the enactment of this Act. (d) Penalty.-- (1) In general.--Subject to paragraph (2), whoever violates this section shall be fined $500 for the first such violation and $1,500 for each subsequent violation. (2) Information about minors.--Whoever commits a violation of a regulation issued under subsection (b)(1)(C) shall be fined twice the amount of the fine that would otherwise apply under this subsection if such violation results in the transmission from a computer of information that is identifiable to-- (A) an individual who operates that computer and has not attained 18 years of age; or (B) that computer if a primary user of that computer is an individual who has not attained such age. (3) Subsequent violations.--Each violation of a regulation issued under subsection (b)(1), including each transmission of information in violation of subsection (b)(1)(C), constitutes a separate violation for purposes of this subsection. (e) Definitions.--For purposes of this section: (1) Computer.--The term ``computer'' means a programmable electronically activated device that-- (A) is capable of accepting information, applying prescribed processes to the information, and supplying the results of those processes with or without human intervention; and (B) consists of a central processing unit containing extensive storage, logic, and control capabilities. (2) Information collection device.--The term ``information collection device'' means any device that-- (A) is a computer program that is capable of collecting and transmitting from a computer to a person other than a primary user of that computer, information that is identifiable to that computer, to a primary user of that computer, or to an individual who operates that computer but is not a primary user thereof; and (B) does not consist of only a simple identifying string of computer code, commonly referred to as a ``cookie''. (3) Primary user.--The term ``primary user'' means any individual with general authority over management and use of a computer or any person on whose behalf an individual exercises such general authority.

Sets forth civil penalties for violations of this Act.

studying the mass distribution of massive clusters at high redshifts is important as their existence puts strong constraints on possible cosmological models ( e.g. eke et al . 1996 ; bahcall & fan 1998 ; donahue et al . 1998 ) . furthermore , these systems may be young and thus much can be learned about the formation of massive clusters of galaxies . massive structures in the universe induce a systematic distortion of the images of faint background sources , providing a powerful diagnostic to study their mass distributions ( e.g. mellier 1999 ) . the weak lensing signal allows us to map the projected mass surface density of the lens ( e.g. kaiser & squires 1993 ) , and determine its mass . although the weak lensing mass estimate does not require assumptions about the dynamical state or geometry , it does require a good estimate for the redshift distribution of the faint sources . since tyson , wenk , & valdes ( 1990 ) succesfully measured the systematic distortion of faint galaxies by a foreground cluster , many massive clusters of galaxies have been studied ( e.g. bonnet , mellier , & fort 1994 ; fahlman et al . 1994 ; squires et al . these studies concentrated on massive clusters with redshifts @xmath8 . smail et al . ( 1994 ) tried to measure the weak lensing signal for the optically selected , high redshift cluster cl 1603 + 43 @xmath9 . its observed velocity dispersion is @xmath10 km / s ( postman , lubin , & oke 1998 ) . smail et al . ( 1994 ) used source galaxies down to a limiting magnitude of @xmath11 , but failed to detect a signal . their results are consistent with a lower mass for the cluster . this is supported by the cluster s x - ray luminosity of @xmath12 ergs / s ( castander et al . 1994 ) , which is an order of magnitude lower than the x - ray luminosity of the brightest , high redshift , x - ray selected clusters the x - ray emission of clusters of galaxies provides an efficient means to select massive clusters of galaxies . since the work of smail et al . ( 1994 ) , several high redshift , x - ray luminous clusters have been discovered from einstein ( gioia & luppino 1994 ) and rosat observations ( henry et al . 1997 ; ebeling et al . 1999 ; rosati et al . 1998 ) . luppino & kaiser ( 1997 ; lk97 hereafter ) successfully detected the weak lensing signal from the x - ray selected , high redshift cluster ms 1054 - 03 using deep ground based imaging . clowe et al . ( 1998 ) reported on the detection of weak lensing signals for the x - ray selected , high redshift clusters ms 1137 + 66 and rxj1717 + 67 , from deep keck imaging . however , these studies suffered from the lack of knowledge of the redshift distribution of the faint sources . lensing studies of high redshift clusters are difficult because the lensing signal is low and most of the signal comes from small , faint galaxies . this is the regime where hst observations have great advantage over ground based imaging , because the background galaxies are much better resolved . as a result , higher number densities of sources can be reached , the images are not crowded , and more importantly the correction for the circularization by the psf is much smaller . especially for high redshift clusters , where the redshift of the lens approaches that of the sources , the lensing signal depends strongly on the redshift distribution of the sources . in this paper we present our weak lensing analysis of the cluster ms 1054 - 03 using a mosaic of deep wfpc2 images . it is the second cluster we studied using a mosaic of deep hst observations . in hoekstra ( 1998 , hfks98 hereafter ) we presented the analysis of cl 1358 + 62 , a rich cluster of galaxies at a redshift of @xmath13 . ms 1054 - 03 @xmath14 is the most distant cluster in the einstein extended medium sensitivity survey ( gioia et al . 1990 ; gioia & luppino 1994 ) . it is extremely rich and has a restframe x - ray luminosity , @xmath15=0.3 and @xmath16 . this gives a scale of @xmath17 kpc at the distance of ms 1054 . ] @xmath18 ergs / s ( donahue et al . 1998 ) , which makes it one of the brightest x - ray clusters known . from their asca observations donahue et al ( 1998 ) find a high x - ray temperature of @xmath19 kev . our space based observations allow us to study the cluster mass distribution in much more detail than lk97 . photometric redshift distributions inferred from the hubble deep field north ( fernndez - soto , lanzetta , & yahil 1999 ) and south ( chen et al . 1998 ) give a good approximation of the redshift distribution of the sources used in this weak lensing analysis . as a result it is possible to obtain well calibrated mass estimates for high redshift clusters of galaxies from multi - colour imaging , even if the availability of spectroscopic redshift data for the sources is limited . the observations and data reduction are outlined in section 2 . in section 3 we briefly discuss the method we use to analyse the galaxies . section 4 deals with the light distribution of the cluster . in section 5 we present the measurements of the lensing induced distortions of the faint galaxies and the reconstruction of the projected mass surface density . section 6 deals with the redshift distribution of the faint galaxies . our mass determination is presented in section 7 . in this section we also discuss several effects that complicate accurate mass determinations . the results for the mass - to - light ratio are given in section 8 . in section 9 we examine in more detail the substructure of the cluster . the lensing signal due to the cluster galaxies themselves is studied in section 10 . in this analysis we use wfpc2 images taken with the hubble space telescope ( go proposal 7372 , pi franx ) . figure [ layout ] shows the layout of the mosaic constructed from the 6 pointings of the telescope . the integration time per pointing was 6400s in both the @xmath20 and @xmath21 filter . for the weak lensing analysis we omitted the data of the planetary camera because of the brighter isophotal limit . the total area covered by the observations is approximately 26 arcmin@xmath22 . for each pointing the exposures of a given passband were split into two sets . the images in each set were offset from each other by integer pixels ( @xmath23 pixels ) . both sets were reduced and combined separately , resulting in two images ( for details see van dokkum et al . 1999 ; van dokkum 1999 ) . these two images were designed to be offset by 5.5 pixels , to allow the construction of an interlaced image ( e.g. fruchter & hook 1998 ; van dokkum 1999 ) , which has a sampling that is a factor @xmath24 better than the original wfpc2 images . except for the images in the first pointing in f814w , all offsets were within 0.1 pixel of the requested value . we found that we had to omit the shape measurements in the @xmath21 band for pointing 1 , because of the deviating offset for this exposure . however , we could use the @xmath20 image , and as the noise in the shear estimate is dominated by the intrinsic ellipticities of the galaxies , the loss in signal - to - noise is minimal . our analysis technique is based on that developed by kaiser , squires , & broadhurst ( 1995 ; ksb95 hereafter ) and lk97 , with a number of modifications which are described in hfks98 . the first step in the analysis is the detection of the galaxy images , for which we used the hierarchical peak finding algorithm from ksb95 . we selected objects with a significance @xmath25 larger than @xmath26 over the local sky . the detected objects were analysed , yielding estimates for the sizes , magnitudes and shapes of the objects . the detection and analysis were done per wfpc2 chip and filter . as a new feature , our software computes an estimate for the error on the polarization from the data . this error estimate is discussed in appendix a. the resulting catalogs were inspected visually in order to remove spurious detections , like diffraction spikes , hii regions in resolved galaxies , etc . 4402 objects were detected in the @xmath20 images , whereas the @xmath21 images yielded 4290 stars and galaxies . the combined catalog consisted of 5848 stars and galaxies , of which 2844 were detected in both filters . for all detected objects we estimated the apparent magnitude using an aperture with a diameter of @xmath27 pixels ( where @xmath28 is the gaussian scalelength of the object as given by the peak finding algorithm ) . we converted the measured counts to @xmath20 and @xmath21 magnitudes , zero - pointed to vega , using the zeropoints given in the hst data handbook ( stsci , baltimore ) . we added 0.05 magnitude to the zero - points to account for the charge transfer efficiency ( cte ) effect . figure [ objects ] shows the apparent magnitude versus the half light radius of the object . moderately bright stars are easily identified as they are located in the vertical locus . bright stars saturate and hence their measured sizes increase . using figure [ objects ] we selected a sample of moderately bright stars , which were used to examine the psf . to obtain a catalog of galaxies we removed the stars from the catalog . at faint levels the discrimination between stars and galaxies is not possible , but by extrapolating the number counts of moderately bright stars to faint magnitudes , we find that the stars contribute less than 2% to the total counts . we attempted to determine colours for all detected objects ( including galaxies detected in only one filter ) , using the same aperture in both filters . the software failed to determine colours for some of the galaxies . most of these were extremely faint , and detected only in the @xmath21 band . for the weak lensing analysis we only used galaxies for which colours were determined . due to this selection we lost 30% of the galaxies fainter than @xmath29 ( 533 galaxies ) . the shape parameters of the galaxies were corrected for the psf ( cf . section 3.1 ) and the camera distortion we used the estimated errors on the shape measurements ( cf . appendix a ) to combine the results from the @xmath20 and @xmath21 images in an optimal way , resulting in a final catalog of 4971 galaxies . the better sampling of the interlaced images improved the object detection and analysis significantly . hfks98 showed that due to the poor sampling of wfpc2 images only the shapes of galaxies with sizes @xmath30 could be measured reliably . the images used here allow us to use all detected galaxies . hfks98 found a number density of 79 galaxies arcmin@xmath31 from 3600s exposures in both @xmath20 and @xmath21 . the observations presented here yield a number density of 191 galaxies arcmin@xmath31 . this higher number density is due to both the longer integration time , and the improved sampling of the interlaced images . an analysis of the effect of small pointing errors in the interlaced images shows that these are not important for our analysis ( cf . appendix b ) . figure [ counts ] shows the observed number counts of galaxies in our observations versus apparent magnitude . for comparison we also show the counts from the hdf - north ( williams et al . this indicates that our catalog of galaxies is complete down to @xmath32 and @xmath33 . several observational effects systematically distort the images of the galaxies . to obtain an accurate and unbiased estimate of the weak lensing signal these effects have to be corrected for . to do so , we follow the scheme outlined in ksb95 , lk97 , and hfks98 . hfks98 showed that the psf of wfpc2 is highly anisotropic at the edges of the chips . we selected a sample of moderately bright stars from the observations of ms 1054 . figure [ psf814 ] shows the observed polarization of these stars in the f814w band . the anisotropy pattern is similar to the pattern presented in hfks98 . because the psf changes slightly with time , we fitted the shape parameters of our new observations to a scaled model of the psf polarization measured from the globular cluster m4 and added a first order polynomial : @xmath34 this procedure gave excellent fits to the observed psf anisotropy in our observations of ms 1054 . the psf also circularizes the images of the small , faint galaxies , thus lowering the amplitude of the lensing signal . compared to ground based observations , the small faint galaxies are much better resolved in hst observations , resulting in much smaller corrections for the circularization by the psf . this allows us to measure a well calibrated lensing signal . to obtain estimates for the real shapes of the faint galaxies , we determined the pre - seeing shear polarizability @xmath35 ( lk97 ; hfks98 ) . the measurements of @xmath35 for individual galaxies are rather noisy , and therefore we binned the data as a function of size of the object . the results are presented in figure [ corfac ] , which shows the required correction factor to obtain the true ellipticity of a galaxy from the observed polarization . the upper panel shows the cumulative number of objects as a function of object size . the objects for which the peak finder assigned a size smaller than the psf were analysed with a weight function matched to the psf . these objects end up in the bin corresponding to the smallest objects . the correction for objects with sizes comparable to the size of the psf is large . the psf in ground based images is much larger , and therefore large correction factors are required for objects that are still well resolved in hst images . from a @xmath36 deep ground based image we found that @xmath37 for galaxies of @xmath38 , whereas galaxies of similar brightness in our hst images have @xmath39 . as a test of our procedure we compared the distortion measured from the @xmath20 images and the @xmath21 images ( which included the correction for the circularization ) using only objects for which shape parameters could be measured in both images . we compared the average tangential distortions and found that the results for the two filters agree well to one another ( we found @xmath40 from the @xmath20 data and @xmath41 for the @xmath21 images ) . recently it has been found that the charge transfer efficiency problem for wfpc2 has worsened . this can systematically change the shapes of the faint galaxies , as charge is smeared along the ccd columns . this could result in a detectable change in the shapes of the galaxy images . we compared the shapes of the objects in the regions where the pointings overlap ( cf . figure [ layout ] ) . unfortunately the number of objects was low , and the contribution of shot noise to the shape estimates substantial . we did not detect a systematic change in the shapes , but we can not put strong constraints on the size of the effect . we also simulated the effect , assuming that the change in shape increased linearly with row number for each chip , with no change at low row numbers and a shear of 10% at high row numbers . we found that this resulted in a neglegible change in our mass estimate . figure [ colmag ] shows a plot of the colour of the galaxies versus their @xmath21 magnitude . the cluster is visible as the concentration of galaxies with @xmath42 . the galaxies on this colour - magnitude relation are generally early type galaxies , which are among the reddest objects in the cluster . we selected 324 galaxies brighter than @xmath43 , lying close to the colour - magnitude relation , to study the cluster light distribution . this catalog was compared to the spectroscopic catalog ( van dokkum 1999 ) . the contamination by field galaxies is small , and we removed galaxies with redshifts incompatible to that of the cluster . many of these belong to a small group at @xmath44 ( van dokkum 1999 ) . we have use sextractor ( bertin & arnouts 1996 ) to determine total magnitudes for these galaxies . figure [ lumdis ] shows grey scale plots of the luminosity and number density weighted light distributions . the images have been smoothed with a gaussian with a fwhm of 20 arcseconds . the galaxy number density and the luminosity weighted distributions look quite similar . the cluster light distribution is elongated east - west , and three clumps can be identified . figure [ lumdis ] also shows gray scale images of the smoothed number density when we split the sample of all detected galaxies into a bright ( @xmath45 ) and a faint sample ( @xmath46 ) . the cluster is clearly visible in the bright sample , but does not show up in the number counts of the faint galaxies ( which have been corrected for the area covered by large bright galaxies ) . figure [ lumdis]d shows several significant peaks , indicative of some clustering at high redshift . we estimate the luminosity in the redshifted @xmath47 band following van dokkum ( 1999 ) . the direct transformation from the hst filters to the passband corrected @xmath47 band is given by @xmath48 where @xmath49 denotes the passband corrected @xmath47 band magnitude . the luminosity is given by @xmath50 where @xmath51 is the solar absolute @xmath47 magnitude , @xmath52 is the distance modulus , and @xmath53 is the extinction correction in the @xmath21 filter towards ms 1054 - 03 . the redshift of @xmath54 for ms 1054 gives a distance modulus of @xmath55 . taking galactic extinctions from burstein & heiles ( 1982 ) we use a value of 0.03 for @xmath53 . at faint magnitudes , the colour - magnitude relation is less clearly defined . to estimate the total light of the cluster , an estimate of the amount of light contributed by galaxies fainter than @xmath43 is required . to do so , we fitted a luminosity function to the sample of bright , colour selected cluster galaxies . we found that a schechter function with @xmath56 and @xmath57 @xmath58 could fit the observed counts of the sample of bright , colour selected cluster galaxies . for nearby clusters one typically finds @xmath59 ( eg . binggeli , sandage , & tammann 1988 ) , indicating that the galaxies in ms 1054 - 03 are approximately twice as bright as nearby cluster galaxies . this is in good agreement with the results of van dokkum et al . ( 1998 ) who studied the fundamental plane in ms 1054 - 03 . the luminosity function indicates that we miss approximately 5% of the light when not including the faint galaxies . ms 1054 - 03 is a high redshift cluster and one might expect a relatively high fraction of blue cluster galaxies , which are too blue to be included in our colour selected sample of cluster galaxies . comparison of our sample to a sample of bright , spectroscopically confirmed members ( van dokkum 1999 ) indicates that we miss 16% of the total light in the @xmath47 band . the cumulative light profile as a function of radius from the centre for the sample of bright galaxies is presented in figure [ lumprof ] . the profile is multiplied by a factor @xmath60 to account for the light from the faint cluster galaxies and the bluest galaxies . the solid line corresponds to the observed profile , whereas the dashed line shows a isothermal profile for comparison . we estimate the total luminosity within an aperture of 1 @xmath2 mpc to be @xmath61 . due to the intrinsic ellipticities of the galaxies , their individual shape estimates are very noisy measurements of the lensing induced distortion . we therefore need to average the measurements of a large number of galaxies to obtain a useful estimate for the distortion @xmath62 . to estimate the average distortion , we weight each object with the inverse square of the uncertainty in the distortion , which includes the contribution of the intrinsic ellipticies of the galaxies and the shot noise in the shape measurement ( cf . appendix a ) : @xmath63 selecting galaxies with @xmath64 and @xmath65 ( the source sample from table [ table1 ] ) , and smoothing using a gaussian with a fwhm of 20 arcsec , we obtain the distortion field presented in figure [ shearfield ] . the sticks indicate the direction of the distortion , and the length is proportional to the amplitude of the distortion . it shows that on average the faint galaxies tend to align tangentially to the ( elongated ) cluster mass distribution , as expected from gravitational lensing . the average tangential distortion @xmath66 in radial bins is a useful measure of the lensing signal . it is defined as @xmath67 , where @xmath68 is the azimuthal angle with respect to the assumed centre of the mass distribution . we assume that the position of the brightest cluster galaxy defines the centre of the cluster . at large radii from the cluster centre , where we do not have data on complete circles , we account for possbile azimuthal variation of @xmath66 by fitting @xmath69 to the observed distortions . this procedure gives the correct value for an ellipsoidal mass distribution . although the cluster appears elongated , no large azimuthal variations in the tangential distortion were found . the average tangential distortion as a function of radius is presented in figure [ gtall]a . in the absence of lensing , the points should scatter around zero . the figure shows a systematic tangential alignment of the sources . the dependence of the signal on radius is quite complicated , indicative of a complex mass distribution . the results of the two - dimensional mass reconstruction ( cf . section 5.1 ) show that the sharp decrease in the tangential distortion around 40 is due to substructure in the cluster mass distribution . as a test , figure [ gtall]b shows the results when the phase of the distortion is increased by @xmath70 ( i.e. rotating the sources by @xmath71 ) . in this case the signal should vanish if it is due gravitational lensing , as is observed . we divide our sample of galaxies in several subsamples , based on their apparent magnitude and colours . table [ table1 ] lists some details of the subsamples . it shows that even our bright sample in fact consists of rather faint galaxies . [ cols="<,^,^,^,^,^ " , ] combining measurement of the mass with the estimate of the total light in the passband corrected @xmath47 band within an aperture of 1 @xmath2 mpc radius ( cf . section 4 ) yields @xmath72 . this result has to be corrected for luminosity evolution in order to compare it to values found for lower redshift clusters . studies of the fundamental plane of clusters of galaxies at various redshifts have quantified the luminosity evolution ( e.g. van dokkum & franx 1996 ; kelson et al . 1997 ; van dokkum et al . 1998 ) . the fundamental plane of ms 1054 was studied by van dokkum et al . they found that the mass - to - light ratio of early type galaxies in ms 1054 - 03 is @xmath73 lower than the present day value . under the assumption that the total luminosity of the cluster has changed by the same amount , the corrected mass - to - light ratio of ms 1054 is @xmath74 . the resulting mass - to - light ratio depends on the cosmological parameters . in table [ tableml ] the observed mass - to - light ratios in the passband corrected @xmath47 band are listed ( column ( 4 ) ) . column ( 5 ) lists the mass - to - light ratio corrected for luminosity evolution as determined from the evolution of the fundamental plane for ms 1054 - 03 for the various cosmologies considered here ( van dokkum et al . 1998 ) . hfks98 measured a mass - to - light ratio of @xmath75 for cl 1358 + 62 , which changes to @xmath76 after correction for luminosity evolution . carlberg , yee , & ellingson ( 1997 ) studied a sample of 16 rich clusters of galaxies , and they find a value of @xmath77 for the average mass - to - light ratio . using @xmath78 as found for nearby early type galaxies ( jrgensen , franx , & kjaergaard 1995 ) this transforms to @xmath79 in the @xmath47 band . this comparison indicates that the mass - to - light ratio of ms 1054 is similar to what is found from other studies , suggesting that the range in cluster mass - to - light ratios is rather small . lk97 argued that ms 1054 - 03 might be a relatively dark cluster , but our analysis does not confirm their results . we also studied the radial dependence of the mass - to - light ratio using equation [ eqzetac ] and an estimate for the average surface density in the control annulus . this allows us to estimate the average mass - to - light ratio @xmath80 as a function of radius . to avoid confusion with the clumps in the mass distribution , we present the results for radii larger than 50 arcseconds in figure [ moverlbar ] ( solid points ) . the open circles indicate the mass - to - light ratios measured for the three clumps in the mass distribution , using the results listed in table [ tableclump ] . the results indicate that the light is more concentrated towards the centre of the cluster than the mass . the data enable us to study the observed substructure in the cluster mass distribution in detail . figure [ masscen]a shows the mass reconstruction of the central 3.3 by 2.7 arcminute of the hst mosaic . the origin coincides with the assumed cluster centre . figure [ masscen]b is the overlay of the reconstruction and the @xmath21 image . to allow a direct comparison of the mass reconstruction with the light distribution , we also present the overlay of the smoothed light distribution in figure [ masscen]c . this shows that the projected mass distribution compares well with the light distribution . next we estimate the masses of the three clumps from the observed distortions ( see table [ tableclump ] ) . we use two measures : * a simultaneous fit of three isothermal spheres to the full distortion field ; * the @xmath81-statistic ( equation [ eqzetac ] ) . a simultaneous fit of three sis models to the observed distortion shows that the masses of the three clumps are similar , with corresponding velocity dispersions of @xmath82 km / s . comparison with the estimate of the total cluster mass indicates that most of the mass is in the three clumps . for the @xmath81 statistic we need to estimate the average dimensionless surface density in a control annulus around each clump ( we use @xmath83 and @xmath84 as at these radii the effect of the substructure is expected to be small ) . to do so , we assume that the surface density profile at large radii is isothermal with a velocity dispersion of @xmath85 km / s as found above . the results are listed in table [ tableclump ] . the results from the @xmath81-statistic correspond to the total projected mass in the aperture , which also includes mass from the other clumps . therefore we consider the results of the fitting procedure ( column ( 1 ) ) as the best estimates for the mass . however , to estimate the average mass - to - light ratio of the clumps within a radius of 250 @xmath2 kpc we do use the @xmath81 statistic , as both mass and light are measured in the same aperture . the mass - to - light ratios are around @xmath86 , somewhat lower than the average mass - to - light ratio within an 1 @xmath2 mpc radius aperture around the cluster centre . new x - ray telescopes like chandra or xmm will have the sensitivity to study the x - ray properties of high redshift clusters in detail . ms 1054 - 03 will be an interesting target as we know how the mass is distributed . thus high resolution measurements of the x - ray emission and temperature gradients can provide important information about the thermodynamics of cluster formation . the redshift catalog of van dokkum ( 1999 ) enables us to study the velocity structure of the cluster . the galaxies more that 100 west of the centre show a velocity difference of about 800 km / s with respect to the average velocity . however , their contribution to the total velocity dispersion is small . the three clumps are located closer to the centre , and can not be separated in velocity . therefore the radial motion of the clumps appears to be small compared to the velocity dispersion of the cluster . both outer clumps in the mass distribution are in projection 500@xmath2 kpc away from the central clump . if we assume that all motion is perpendicular to the line of sight , and using a relatively slow approach ( 500 km / s ) we estimate the timescale for relaxation to be on the order of 1 gyr . therefore the cluster should be relaxed at a redshift of @xmath87 . if the physical separations of the clumps are larger , the relaxation time increases correspondingly . to study the mass distribution of ms 1054 - 03 , we concentrated on the lensing signal on relatively large scales . however , the cluster galaxies themselves introduce a small signal as well . measuring this galaxy - galaxy lensing signal can be used to study the halo properties of field galaxies ( e.g. brainerd , blandford , & smail 1996 ; schneider & rix 1997 , hudson et al . 1998 ) . a robust method to examine the cluster galaxies is to measure the average tangential distortion around an ensemble of cluster members . the results are not very sensitive to the precise cluster mass distribution , provided one confines the analysis to small radii . due to the clustering of the lenses , the signal at large radii is dominated by the smooth cluster signal . when measuring the signal out to large radii , a careful removal of the cluster signal is required . we subtracted the contribution of the smooth cluster mass distribution from the observed distortion using the two - dimensional mass reconstruction , and computed the shear @xmath88 taking the @xmath89 correction into account . we used a sample of galaxies brighter than @xmath90 @xmath91 , with colours close to the cluster colour - magnitude relation to study the masses of the cluster galaxies . to minimize the effect of the large scale cluster mass distribution , we excluded galaxies near the centres of the three clumps , resulting in a sample of 241 galaxies . in total , 4300 cluster galaxy - background galaxy pairs were used to measure the distortion . massive galaxies produce a larger distortion than less massive galaxies and therefore we normalized the amplitudes of the signals from the various galaxies correspondingly . to do so , we assumed that the shear @xmath92 , i.e. we assumed a faber - jackson scaling relation . the results are presented in figure [ galgal ] . a fit of a singular isothermal model to the data , yielded a detection of the lensing signal at the 99.8% confidence limit . we found for the einstein radius of an @xmath5 galaxy ( @xmath93 for ms 1054 - 03 ) a value of @xmath94 arcseconds , which corresponds to a velocity dispersion of @xmath95 km / s . the mass - to - light ratio within a radius of @xmath96 kpc is @xmath97 . correcting this result for luminosity evolution yields @xmath98 . if we neglect the effect of the smooth cluster contribution , we find a slightly higher mass for the galaxies : @xmath99 km / s . this indicates that the mass estimate determined using the direct averaging method is indeed robust . natarayan & kneib ( 1998 ) studied the halo properties of the cluster galaxies in ac 114 . they used a maximum - likelihood analysis to constrain the mass and the extent of the galaxy halos . constraining the extent of the halos of the cluster galaxies in ms 1054 is a delicate task which has not been attempted here . it requires a careful analysis of the smooth cluster mass distribution in a maximum likelihood analysis . we have measured the weak gravitational lensing of faint , distant galaxies by ms 1054 - 03 , a rich cluster of galaxies at @xmath0 . the data consist of a two - colour mosaic of 6 interlaced images taken with the wfpc2 camera on the hubble space telescope . the expected lensing signal is low for high redshift clusters , and most of the signal comes from small , faint galaxies . compared to ground based observations , these galaxies are much better resolved in hst observations . high number densities of sources are reached , and the correction for the circularization by the psf is much smaller . this enables us to measure an accurate and well calibrated estimate of the lensing induced distortion of the faint background galaxies . several effects complicate an accurate analysis when the distortions or the surface density are non - neglegible ( e.g. in the cluster cores ) . we do not measure the shear , but the distortion @xmath62 . neglecting the effect of a non - zero surface density results in an overestimate of the lensing signal . furthermore , the method used ( ksb95 ; lk97 ) underestimates the distortion when it is larger than @xmath100 . although we correct for these effects , it is best to restrict the analysis to the weak lensing regime , where the convergence @xmath101 is low , and the distortions are small . converting the lensing signal into a mass estimate requires knowledge of the redshift distribution of the faint sources . we have explored the use of photometric redshift distributions inferred from the northern ( fernndez - soto et al . 1999 ) and southern ( chen et al . 1998 ) hubble deep fields . comparison of the results for the two fields suggest field to field variations which lead to a 10% systematic uncertainty in the mass estimate for ms 1054 - 03 . our results for the mass and mass - to - light ratio of ms 1054 - 03 agree well with other estimators , suggesting that these photometric redshift distributions are a fair approximation of the true distribution . this gives us confidence that we are able to measure a well calibrated weak lensing mass for this high redshift cluster . using the @xmath81 statistic ( clowe et al . 1998 ) , we find a mass @xmath102 within an aperture of 1 @xmath2 mpc radius . under the assumption of an isothermal mass distribution , this corresponds to a velocity dispersion of @xmath3 km / s . a fit of an isothermal sphere model to the observed tangential distortion at large radii , yields a velocity dispersion of @xmath103 km / s . however , this result depends on the assumed radial surface density profile . the uncertainties in the mass estimates only reflect the contribution from the intrinsic ellipticities of the sources . the weak lensing mass estimate is in good agreement with the x - ray estimate from donahue et al . ( 1998 ) and the observed velocity dispersion ( tran et al . 1999 ; van dokkum 1999 ) . the observed average mass - to - light ratio in the passband corrected @xmath47 band is @xmath104 ( measured within a 1 @xmath2 mpc radius aperture ) . we use the results from van dokkum et al . ( 1998 ) to correct our estimate for luminosity evolution . the resulting mass - to - light ratio of @xmath105 can be compared to results obtained for nearby clusters , and is in excellent agreement with the findings of carlberg et al . ( 1997 ) . our high resolution mass reconstruction shows three distinct peaks in the mass distribution , which are in good agreement with the irregular light distribution . the results of lk97 lacked the resolution to detect this substructure . in projection the clumps are approximately 500 @xmath2 kpc apart , and we estimate the timescale for virialization to be at on the order of @xmath106 1 gyr . thus the cluster should be virialized at a redshift @xmath107 . we found that the clumps are of roughly equal mass , with corresponding velocity dispersions of @xmath108 km / s . to study the masses of the cluster members , we have measured the average tangential shear around a sample of 241 bright cluster galaxies . assuming the faber - jackson scaling relation we find a velocity dispersion of @xmath7 km / s for an @xmath5 galaxy ( @xmath109 for ms 1054 - 03 ) . the mass - to - light ratio within a radius of @xmath96 kpc is @xmath97 . correcting this result for luminosity evolution yields @xmath98 . the number of known massive high redshift clusters of galaxies is increasing rapidly . the results presented here demonstrate that these systems can be studied with sufficient signal - 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ph/9906152 williams , r.e . , 1996 , aj , 112 , 1335 willick , j.a . 1999 , preprint , astro - ph/9904367 the weak lensing signal is obtained by averaging the shape measurements of a number of faint galaxies . the noise in the shape estimate differs from object to object , and therefore it is important to weight the measurements properly . for bright galaxies the error on the shear measurement is dominated by the intrinsic ellipticity distribution of the galaxies . at fainter magnitudes , shot - noise increases the uncertainty in the measurements . as these galaxies require large seeing corrections , the measurement error on the distortion can be quite high . this is illustrated in figure [ scatter ] . figure [ scatter]a shows the observed scatter in the polarization as a function of apparent magnitude in the @xmath21 band . as fainter objects suffer more from the circularization by the psf one would expect the scatter to decrease towards fainter magnitudes . however , the increasing contribution by shot noise ( indicated by the solid line ) cancels out the effect of the circularization . figure [ scatter]b shows the observed scatter in the ellipticities ( shear ) of the objects . the scatter at faint magnitudes increases rapidly due to the combination of shot noise and large psf corrections . the solid line indicates the expected scatter due to the combination of shot noise and psf correction . we estimate the weighted mean of the distortion using : @xmath110 where the weight @xmath111 is the inverse of the variance of the distortion : @xmath112 where @xmath113 is the scatter due to the intrinsic ellipticity of the galaxies , @xmath114 is the pre - seeing shear polarizability and @xmath115 is the error estimate for the polarization , which is derived below . this procedure , however , gives only the optimal estimate for the average ellipticity , but does not account for the fact that the nearby bright galaxies are lensed less efficiently than faint high redshift galaxies . to get the best lensing estimate it is therefore also necessary to weight with @xmath116 as well this is demonstrated in figure [ weight]a , where we show the weight function as a function of apparent magnitude ( solid line ) . the dashed line shows the weight function hen we include the strength of the lensing signal . this effectively decreases the weight of bright ( nearby ) galaxies and increases the relative weight of the faint ( distant ) galaxies . it is also interesting to see which magnitude range contributes most to the measurement of the distortion . in figure [ weight]b we plot the weight function for each magnitude bin times the number of galaxies in that bin . this gives the total contribution of each bin to the measurement of the distortion . although the bright galaxies have the highest weight function ( cf . figure [ weight]a ) , they are not so numerous to contribute significantly to the lensing signal . at the faint end both incompleteness and increasing noise causes the contribution to decrease rapidly . figure [ weight]b also shows that including the strength of the lensing signal @xmath117 changes the profile only slightly . it shows that galaxies with @xmath21 magnitudes between 24 and 26.5 contribute most to the lensing signal . here we derive an expression to estimate the error on the polarization measurement , using the observations . the observed quadrupole moments are given by : @xmath118 which are combined to form the two - component polarization . @xmath119 due to noise , the true image @xmath120 is changed to the observed image @xmath121 : @xmath122 where we take @xmath123 . the first term in equation a5 gives the true image , the second term is the noise in the background , and the third contribution comes from the shot noise due to the image . we therefore observe quadrupole moments given by : @xmath124 as @xmath125 , this shows that @xmath126 . thus noise does not introduce a bias in the average measurement of the quadrupole moments . however , it does introduce a neglegible bias in the polarization . we now can estimate the variance in the observed quadrupole moments using equation a6 and noting that @xmath127 , @xmath128 , and @xmath129 , where @xmath130 is the dirac delta function . this yields : @xmath131 we now want to estimate the errors on the measurements of the polarizations @xmath132 and @xmath133 and express them in terms of the errors on the quadrupole moments . this finally gives : @xmath134\end{aligned}\ ] ] and @xmath135.\end{aligned}\ ] ] from simulations and real images we find that the errors on both @xmath132 and @xmath133 are similar . this estimate for the error on the polarization can be calculated from the observations and allows us to properly weight the signals of the galaxies using equation a2 . the images of small , faint galaxies in wfpc2 observations are poorly sampled . hfks98 showed that as a result the smallest objects can not be corrected reliably for the psf effects . however , several techniques can be used to improve the sampling of wfpc2 observations by dithering the exposures ( fruchter & hook 1998 ) . when the shifts are half pixel in both @xmath136 and @xmath137 ( modulo integer pixel shifts ) one can construct an interlaced image ( fruchter & hook 1998 ) which has a @xmath24 better sampling . interlaced images were constructed from the observations of ms 1054 - 03 . doing so , we assumed that the offsets were exactly half pixel . due to pointing errors and the camera distortion the real offsets are slightly different . in this section we examine the effect of imperfect offsets on the shape measurements . to do so , we examine the change in the shape of a model psf . although interlacing is not a convolution , it affects large objects ( as these are well sampled even before interlacing ) less than small objects . by examining the effects on the psf , we study a worst case scenario . the effects should be less for most of the galaxies used in the weak lensing analysis . we use a ten times oversampled model psf calculated using tiny tim . this psf is shifted and rebinned to wfpc2 sampling and convolved with the pixel scattering function , in order to realistically mimic the wfpc2 psf . we start with a reference image in which the star is centered exactly on a pixel . this image is shifted @xmath138 and an interlaced image is created assuming the shift was exactly ( 0.5 , 0.5 ) pixels . the resulting image is analysed and the measured ellipticities are compared to the correct value . the change in ellipticity as a function of the applied offset is presented in figure [ interlace ] ( left panel ) . when the reference star is placed at the intersection of four pixels the results are different , as is indicated in figure [ interlace ] ( right panel ) . these two extreme cases should cover the full range of possible configurations . in figure [ interlace ] we also plot the observed offsets for our data . the open circles represent the offsets of the @xmath21 images , and the solid triangles show the offsets for the @xmath20 images . only one @xmath21 pointing has such a deviating offset that the shape measurements can not be used for our weak lensing analysis . in all other images the offsets are such that no significant bias is introduced by the interlacing . even if the offset is perfect in the centre of the image , telescope distortions will result in imperfect offsets at the edges . we simulated the amplitude of the effect using the coefficients for the telescope distortions from holtzman et al . ( 1995 ) . figure [ interlace2 ] shows the introduced ellipticity for our worst offset ( 5.71 , 5.89 ) . the bias in the observed ellipticities is clear in this case . these data ( the @xmath21 image of the first pointing ) were not used in the weak lensing analysis . the second worse offset ( 5.53 , 5.60 ) is also shown in this figure . the ellipticity introduced in this case is small . only at the edges of the chips the camera distortion introduces a small effect . as the effect is even smaller for galaxies , we feel certain that we can use the interlaced images for our weak lensing analysis .

we have measured the weak gravitational lensing of faint , distant background galaxies by ms 1054 - 03 , a rich and x - ray luminous cluster of galaxies at a redshift of @xmath0 , using a two - colour mosaic of deep wfpc2 images . the small corrections for the size of the psf and the high number density of background galaxies obtained in these observations result in an accurate and well calibrated measurement of the lensing induced distortion . the strength of the lensing signal depends on the redshift distribution of the background galaxies . we used photometric redshift distributions from the northern and southern hubble deep fields to relate the lensing signal to the mass . the predicted variations of the signal as a function of apparent source magnitude and colour agrees well with the observed lensing signal . the uncertainty in the redshift distribution results in a 10% systematic uncertainty in the mass measurement . we determine a mass of @xmath1 within an aperture of radius 1 @xmath2 mpc . under the assumption of an isothermal mass distribution , the corresponding velocity dispersion is @xmath3 . for the mass - to - light ratio we find @xmath4 after correcting for pass - band and luminosity evolution . the errors in the mass and mass - to - light ratio include the contribution from the random intrinsic ellipticities of the source galaxies , but not the ( systematic ) error due to the uncertainty in the redshift distribution . however , the estimates for the mass and mass - to - light ratio of ms 1054 - 03 agree well with other estimators , suggesting that the mass calibration works well . the reconstruction of the projected mass surface density shows a complex mass distribution , consistent with the light distribution . the results indicate that ms 1054 - 03 is a young system . the timescale for relaxation is estimated to be at least 1 gyr . we have also studied the masses of the cluster galaxies , by averaging the tangential shear around the cluster galaxies . using the faber - jackson scaling relation , we find the velocity dispersion of an @xmath5 galaxy ( @xmath6 for ms 1054 - 03 ) is @xmath7 km / s .

this paper continues the comparison between lines of minima and teichmller geodesics begun in @xcite . let @xmath2 be a hyperbolizable surface of finite type and @xmath7 be the space of @xmath2 . let @xmath0 and @xmath1 be two measured laminations that fill up @xmath2 . the associated _ line of minima _ is the path @xmath8 , where @xmath9 is the unique hyperbolic surface that minimizes the length function @xmath5 on @xmath7 , see @xcite and section [ sec : linesofm ] below . lines of minima have significance for hyperbolic @xmath10-manifolds : infinitesimally bending @xmath4 along the lamination @xmath0 results in a quasifuchsian group whose convex core boundary has bending measures in the projective classes @xmath0 and @xmath1 and in the ratio @xmath11 , see @xcite . in this paper we prove : [ thm : qgeo0 ] the line of minima @xmath4 , @xmath12 , is a quasi - geodesic with respect to the metric . in other words , there are universal constants @xmath13 , depending only on the topology of @xmath2 , such that for any @xmath14 with @xmath15 , we have @xmath16 where @xmath17 is the distance . an obvious way to approach this would be to compare the time-@xmath18 surface @xmath4 with the corresponding surface @xmath19 on the geodesic whose horizontal and vertical foliations at time @xmath18 are respectively , @xmath20 and @xmath21 @xcite . in @xcite , we did just this . we showed that if neither surface @xmath4 nor @xmath19 contains short curves , that is , they are both contained in the thick part of space , then the distance between them is bounded above by a uniform constant that is independent of @xmath18 . more generally , we showed that the set of curves which are short on the two surfaces coincide . we also showed , however , that the ratio of lengths of the same short curve on the two surfaces may be arbitrarily large , so that the path @xmath4 may deviate arbitrarily far from @xmath19 . it is therefore not immediately obvious how to derive theorem [ thm : qgeo0 ] from @xcite . to explain our method , we first summarize the results of @xcite in more detail . it turns out that on both @xmath4 and @xmath19 , a curve @xmath22 is short if and only if at least one of two quantities @xmath23 and @xmath24 is large . these quantities depend on the topological relationship between @xmath22 and the defining laminations @xmath0 and @xmath1 . they relate to the modulus of a maximal embedded annulus around @xmath22 ; the modulus of a _ flat _ annulus is approximately @xmath23 and the modulus of an _ expanding _ annulus is approximately @xmath25 , see @xcite and sections [ sec : flat ] and [ sec : estimates ] below . we say that a curve is _ extremely short _ if it is less than some prescribed @xmath26 depending only on the topology of @xmath2 , see section [ sec : background ] . the essential results in @xcite were the following estimates ( see section [ sec : background ] for notation ) : [ thm : glshort ] let @xmath22 be a simple closed curve on @xmath2 . if @xmath22 is extremely short on @xmath19 then @xmath27 while if @xmath22 is extremely short on @xmath4 then @xmath28 [ @xcite theorem 7.15 ] [ thm : gldistance ] the distance between @xmath4 and @xmath19 is given by @xmath29 where the maximum is taken over all simple closed curves @xmath22 that are extremely short in @xmath19 . in particular , the distance between the thick parts of @xmath4 and @xmath19 is bounded . it follows from these results , that along intervals on which either there are no short curves , or on which @xmath30 dominates for all short curves @xmath22 , the surfaces @xmath4 and @xmath19 remain a bounded distance apart . however the path @xmath4 may deviate arbitrarily far from @xmath19 along time intervals on which @xmath24 is large and dominates @xmath30 . the situation is complicated by the fact that as we move along @xmath4 , the family of curves which are short at a given point in time will vary with @xmath18 , so that the intervals along which different curves @xmath22 are short will overlap . in addition to the above results from @xcite , there are two main ingredients in the proof of theorem [ thm : qgeo0 ] . the first is a detailed comparison of the rates of change of @xmath31 and @xmath30 with @xmath18 . some simple estimates are made in lemmas [ lem : kdecay ] and [ lem : dandk ] , with more elaborate consequences drawn in lemma [ lem : hldistance ] and especially lemma [ lem : dichotomy ] . these results use minsky s product regions theorem ( see theorem [ thm : minskyproduct ] ) , which allows us to reduce calculations of distance in regions of space in which a given family of curves is short , to straightforward estimates in @xmath32 . to apply minsky s theorem , we need not only to compare lengths but also twists . we rely on the bounds on twists proved in @xcite and reviewed in theorems [ thm : gtwist ] and [ thm : ltwist ] ; these enter in a crucial way into the proof of lemma [ lem : hldistance ] . the second main ingredient is control of distance along intervals along which @xmath24 is large . consider the surface @xmath33 obtained by cutting @xmath2 along a short curve @xmath22 and replacing the two resulting boundary components by punctures . the following rather surprising result , proved in section 4 , states that on intervals along which @xmath24 is large , we can estimate the distance by restricting to the space of the surface @xmath33 . in other words , the contribution to distance in minsky s formula [ thm : minskyproduct ] due to the short curve @xmath22 itself may be neglected , see theorem [ thm : klarge ] for a precise statement . [ thm : klarge0 ] if @xmath24 is sufficiently large for all @xmath34 $ ] , the distance in @xmath35 between the restrictions of @xmath36 and @xmath37 to @xmath33 is equal to @xmath38 , up to an additive error that is bounded by a constant depending only on the topology of @xmath2 . the proof of theorem [ thm : qgeo0 ] requires estimating upper and lower bounds for @xmath39 over very large time intervals @xmath40 $ ] . given the first of the two ingredients above , the upper bound is relatively straightforward . the lower bound depends on theorem [ thm : klarge0 ] . the actual application involves a rather subtle inductive procedure based on lemma [ lem : dichotomy ] which shows that at least one term in minsky s formula [ thm : minskyproduct ] always involves a contribution comparable to @xmath38 . the paper is organized as follows . section 2 gives standard background and introduces the twist @xmath41 of a lamination @xmath42 about a curve @xmath22 with respect to a hyperbolic metric @xmath43 . we give the main estimates about twists from @xcite . in section 3 , we recall from @xcite the definitions of @xmath23 and @xmath24 and derive some elementary results about their rates of change with @xmath18 . in section 4 we prove theorem [ thm : klarge0 ] and in section 5 we prove theorem [ thm : qgeo0 ] . we would like to thank the referee for helpful comments . since we will be dealing mainly with coarse estimates , we want to avoid heavy notation and keep track of constants which are universal , in that they do not depend on any specific metric or curve under discussion . for functions @xmath44 we write @xmath45 to mean that there are constants @xmath46 , depending only on the topology of @xmath2 and the fixed constant @xmath47 ( see below ) , such that @xmath48 we use @xmath49 and @xmath50 to mean that these inequalities hold with @xmath51 and @xmath52 , respectively . the symbols @xmath53 , @xmath54 , @xmath55 , etc . , are defined similarly . in particular , we write @xmath56 to indicate @xmath57 is bounded above by a positive constant depending only on the topology of @xmath2 and @xmath47 . let @xmath58 denote the set of isotopy classes of non - trivial , non - peripheral simple closed curves on @xmath2 . the length of the geodesic representative of @xmath59 with respect to a hyperbolic metric @xmath60 will be denoted @xmath61 . in our dealings with short curves we will have to make various assumptions to ensure the validity of our estimates , which all require that the length @xmath61 of a ` short ' curve be less than various constants , in particular less than the margulis constant . we suppose that @xmath26 is chosen once and for all to satisfy all needed assumptions , and say a simple closed curve @xmath22 is _ extremely short _ in @xmath62 if @xmath63 . we denote the space of measured laminations on @xmath2 by @xmath64 and write @xmath65 for the hyperbolic length of a measured lamination @xmath66 . for @xmath67 , we denote the underlying leaves by @xmath68 . suppose that @xmath69 fill up @xmath2 , meaning that the sum of ( geometric ) intersections @xmath70 for all @xmath66 . kerckhoff @xcite showed that the sum of length functions @xmath71 has a unique global minimum on @xmath72 . moreover , as @xmath18 varies in @xmath73 , the minimum @xmath74 of @xmath75 for the measured laminations @xmath76 and @xmath77 varies continuously with @xmath18 and traces out a path @xmath6 called the _ line of minima @xmath78 of _ @xmath79 . a pair of laminations @xmath69 which fill up @xmath2 also defines a geodesic @xmath80 . the time-@xmath18 surface @xmath81 is the unique riemann surface that supports a quadratic differential @xmath82 whose horizontal and vertical foliations are the measured foliations corresponding to @xmath83 and @xmath84 respectively , see @xcite , @xcite . flowing distance @xmath85 along @xmath86 expands the vertical foliation by a factor @xmath87 and contracts the horizontal foliation by @xmath88 . by abuse of notation , we denote the hyperbolic metric on the surface @xmath89 also by @xmath19 , and likewise denote the quadratic differential metric defined by @xmath82 also by @xmath82 . for a curve @xmath90 that is neither a component of the vertical nor the horizontal foliation , let @xmath91 denote the _ balance time _ of @xmath22 at which @xmath92 . along @xmath93 , a curve is shortest near its balance time . more precisely , we have the following proposition which follows from @xcite theorem 3.1 : [ prop : aroundbalancetime ] choose @xmath94 so that @xmath95 and suppose that @xmath96 let @xmath97 be the maximal connected interval containing @xmath98 such that @xmath99 for all @xmath100 . then there is a constant @xmath101 depending only on @xmath102 such that @xmath103 for all @xmath104 . ( if @xmath105 then set @xmath106 . ) curves which are components of the vertical foliation ( @xmath107 , called _ vertical _ ) or the horizontal foliation ( @xmath108 , called _ horizontal _ ) are exceptional but in general easier to handle . in such cases , @xmath91 is undefined . however , for reasons of continuity , it is natural to adopt the convention that when @xmath22 is vertical @xmath109 and when @xmath22 is horizontal @xmath110 . moreover , the arguments used to prove proposition [ prop : aroundbalancetime ] still hold ; when @xmath22 is vertical ( resp . horizontal ) , we define @xmath111 ( resp . @xmath112 ) to be the maximal interval where @xmath99 . let @xmath62 be a hyperbolic metric and let @xmath113 be any quadratic differential metric in the same conformal class . let @xmath114 be an annulus in @xmath115 with piecewise smooth boundary . the following notions are due to minsky @xcite . we say @xmath114 is _ regular _ if the boundary components @xmath116 are equidistant from one another and the curvature along @xmath116 is either non - positive at every point or non - negative at every point ( see @xcite or @xcite for details ) . we follow the sign convention that the curvature at a smooth point of @xmath117 is positive if the acceleration vector points into @xmath114 . suppose @xmath114 is a regular annulus such that the total curvature of @xmath118 satisfies @xmath119 . then , it follows from the gauss - bonnet theorem that @xmath120 . we say @xmath114 is _ flat _ if @xmath121 and say @xmath114 is _ expanding _ if @xmath122 , and call @xmath118 the _ inner _ boundary and @xmath123 the _ outer _ boundary . a regular annulus is _ primitive _ if it contains no singularities of @xmath113 in its interior . it follows that a flat annulus is primitive and is isometric to a cylinder obtained from a euclidean rectangle by identifying one pair of parallel sides . an expanding annulus that is primitive is coarsely isometric to an annulus bounded by two concentric circles in the plane . the length of a curve @xmath22 which is short in @xmath124 can be estimated by the modulus of a primitive annulus around it : [ thm : basic ] suppose @xmath59 is extremely short in @xmath124 . then for any quadratic differential metric @xmath113 in the same conformal class as @xmath62 , there is an annulus @xmath114 that is primitive with respect to @xmath113 whose core is homotopic to @xmath22 such that @xmath125 furthermore , the modulus of a primitive annulus is estimated as follows : [ thm : modcomparison]let @xmath126 be a primitive annulus . let @xmath85 be the @xmath113-distance between the boundary components @xmath127 . if @xmath114 is expanding let @xmath118 be the inner boundary . then either 1 . @xmath114 is flat and @xmath128 or 2 . @xmath114 is expanding and @xmath129 $ ] . our main tool for estimating distance is minsky s product regions theorem , which reduces the estimation of the distance between two surfaces on which a given set @xmath130 of curves is short to a calculation in the hyperbolic plane @xmath32 . to give a precise statement , we introduce the following notation . choose a pants curves system on @xmath2 that contains @xmath130 , and for a curve @xmath22 in the pants system let @xmath131 be the fenchel - nielsen twist coordinate of @xmath22 . ( here @xmath132 , where @xmath133 is the actual hyperbolic distance twisted round @xmath22 , see minsky @xcite for details . ) let @xmath134 be the subset of @xmath7 on which all the curves in @xmath130 have length less than @xmath47 and let @xmath135 be the analytically finite surface obtained from @xmath2 by pinching all the curves in @xmath130 . by forgetting the fenchel - nielsen length and twist coordinates associated to the curves in @xmath130 but retaining all remaining fenchel - nielsen coordinates , we obtain a projection @xmath136 . for each @xmath137 , let @xmath138 denote a copy of the upper - half plane and let @xmath139 denote _ half _ the usual hyperbolic metric on @xmath140 ( see lemma 2.2 in @xcite for the factor ) . define @xmath141 by @xmath142 . then the product regions theorem states : [ minsky @xcite ] [ thm : minskyproduct ] let @xmath143 . then @xmath144 to simplify notation , we write @xmath145 instead of @xmath146 and @xmath147 instead of @xmath148 . in practice , we usually apply minsky s theorem with the aid of the following estimate from geometry in @xmath32 . the hyperbolic distance between two points @xmath149 in @xmath32 is given by @xmath150 let @xmath151 be two points in @xmath152 at which a curve @xmath22 is short . let @xmath153 and @xmath154 denote the fenchel - nielsen twist coordinate of @xmath22 at @xmath151 respectively . it follows easily from the above formula that @xmath155 our estimates also require taking account of the _ twist _ @xmath156 of a lamination @xmath157 round @xmath158 with respect to a hyperbolic metric @xmath62 . following minsky , we define @xmath159 where @xmath160 is the signed hyperbolic distance between the perpendicular projections of the endpoints of a lift of a geodesic in @xmath161 at infinity onto a lift of @xmath158 , and the infimum is over all lifts of leaves of @xmath161 which intersect @xmath158 , see @xcite or @xcite for details . we write @xmath162 for @xmath163 . notice that the twist @xmath156 does not depend on the measure on @xmath157 , only on the underlying lamination @xmath164 . the twist is closely related to the fenchel - nielsen twist coordinate . specifically , we have : [ minsky @xcite lemma 3.5 ] [ lem : minskytwist ] for any lamination @xmath165 and any two metrics @xmath166 , @xmath167 although @xmath156 depends on the metric @xmath62 , for @xmath168 the difference @xmath169 is independent of @xmath62 up to a universal additive constant , see @xcite and @xcite section 4 . this motivates the following definition : for @xmath170 and @xmath171 , the relative twist of @xmath172 and @xmath173 round @xmath22 is [ defn : algint ] @xmath174 where the infimum is taken over all hyperbolic metrics @xmath60 . ( the relative twist @xmath175 agrees up to an additive constant with the definition of subsurface distance between the projections of @xmath176 and @xmath177 to the annular cover of @xmath2 with core @xmath22 , as defined in @xcite section 2.4 and used throughout @xcite . ) rafi @xcite , see also @xcite section 5.4 , introduced a similar notion of the twist @xmath178 with respect to a quadratic differential metric @xmath113 compatible with @xmath43 and proved the following result which enters into the proof of theorem [ thm : klarge ] : [ prop : twistcomparison ] suppose that @xmath60 is a hyperbolic metric and @xmath113 is a compatible quadratic differential metric . for any geodesic lamination @xmath42 intersecting @xmath22 , we have @xmath179 we shall also need the following important estimates of the twist which complement theorem [ thm : glshort ] . if @xmath22 is vertical or horizontal , @xmath98 is defined using the convention discussed following proposition [ prop : aroundbalancetime ] . [ thm : gtwist ] let @xmath22 be a simple closed curve on @xmath2 . if @xmath22 is extremely short on @xmath19 then : @xmath180 [ thm : ltwist ] let @xmath22 be a simple closed curve on @xmath2 . if @xmath22 is extremely short on @xmath4 then , @xmath181 in this section we discuss the quantities @xmath23 and @xmath24 that appear in the length estimates in theorem [ thm : glshort ] . let @xmath82 be the unit - area quadratic differential metric on @xmath19 whose vertical and horizontal foliations are @xmath20 and @xmath182 , respectively . in light of theorems [ thm : basic ] and [ thm : modcomparison ] , to estimate the length of a curve @xmath22 which is extremely short in @xmath19 , it is sufficient to estimate the modulus of a maximal flat or expanding annulus around @xmath22 in @xmath82 . the union of all @xmath82-geodesic representatives of @xmath22 foliate a euclidean cylinder @xmath183 , which is the maximal flat annulus whose core is homotopic to @xmath22 . ( the cylinder is degenerate if the representative of @xmath22 is unique . ) on either side of @xmath183 is attached a maximal expanding annulus . let @xmath184 be the one of larger modulus . up to coarse equivalence , @xmath23 will be the modulus of @xmath183 while @xmath25 will be the modulus of @xmath184 . the precise definition of @xmath23 is as follows . if @xmath22 is not a component of @xmath185 , we define @xmath186 where @xmath187 is the relative twisting of @xmath188 and @xmath189 about @xmath22 as defined above . if @xmath22 is vertical , define @xmath190 and if @xmath22 is horizontal , define @xmath191 , where @xmath192 is the annulus at time @xmath193 . the precise definition of @xmath24 is : @xmath194 where @xmath118 is the inner boundary of @xmath184 and @xmath195 is the @xmath82distance between the inner and outer boundaries of @xmath184 . the connection with the definition of @xmath24 in @xcite , and the reasons why @xmath23 and @xmath24 are coarsely the moduli of @xmath183 and @xmath184 respectively , are explained at the end of this section . the estimate for @xmath196 in theorem [ thm : glshort ] follows easily from the above definitions and minsky s estimates . the estimate for @xmath197 in the same theorem required a lengthy separate analysis . the only features of these definitions which will concern us here are the estimates in theorem [ thm : glshort ] , and the relative rates of change of @xmath23 and @xmath24 with time . the rate of change of @xmath23 with time is immediate from ( [ eqn : modf ] ) . to estimate the rate of change of @xmath24 note that , since @xmath184 is maximal , @xmath195 in equation ( [ eqn : mode ] ) is half the @xmath82length of an essential arc from @xmath22 to itself . since the @xmath82length of such an arc or a simple closed curve can increase or decrease at the rate of at most @xmath198 , equation implies that @xmath199 changes ( in the coarse sense ) at a rate at most @xmath200 . more precisely , if @xmath24 is sufficiently large for all @xmath201 $ ] , then @xmath202 in combination with equation and theorem [ thm : glshort ] , it follows that the length of a short curve along @xmath203 or @xmath86 changes at rate at most @xmath204 . more detailed control is given by the following two lemmas , which should be understood with our convention on @xmath91 to include the case when @xmath22 is vertical or horizontal . the first shows that @xmath24 decays as @xmath18 moves away from @xmath98 while the second , illustrated schematically in figure [ fig : graphs ] , compares rates of change of @xmath23 and @xmath199 . the function @xmath24 decays as @xmath18 moves away from @xmath98 . more precisely , [ lem : kdecay ] * if @xmath205 , then @xmath206 . * if @xmath207 , then @xmath208 . suppose first that @xmath22 is not a component of @xmath185 . by lemma 2.1 in @xcite , see also @xcite theorem 2.1 , we have @xmath209 for any @xmath210 . on the other hand , the length of any curve or arc can increase or decrease by a factor of at most @xmath198 . hence , if @xmath211 , then @xmath212 a similar argument can be applied in the case when @xmath207 . if @xmath22 is vertical , then @xmath213 , while if it is horizontal @xmath214 . the result then follows in the same way . [ lem : dandk ] let @xmath215 be as in proposition [ prop : aroundbalancetime ] and let @xmath40 \subset i_\a$ ] . suppose that @xmath216 for some @xmath217 $ ] . * if @xmath218 , then @xmath219 for all @xmath220.$ ] * if @xmath221 , then @xmath219 for all @xmath222.$ ] we refer to figure [ fig : graphs ] for a schematic picture of the two graphs . the proof is based on the fact that @xmath199 decays at a slower rate than @xmath23 as @xmath18 moves away from @xmath98 . if @xmath218 , then for any @xmath223 we have @xmath224 therefore , @xmath225 and @xmath199 . the function @xmath23 changes at rate @xmath204 while @xmath199 changes at rate at most @xmath226 . ] a similar argument can be applied in the case when @xmath227 . the remarks which follow , which may be helpful in clarifying background from @xcite , are not essential for the proof of theorem [ thm : qgeo0 ] . the claim that @xmath23 is coarsely equal to the modulus of @xmath183 is justified by @xcite proposition 5.8 ( section 5.6 for the exceptional case ) which states that @xmath228 . the proof is an exercise in euclidean geometry , combined with rafi s comparison proposition [ prop : twistcomparison ] between the twist in the quadratic and hyperbolic metrics . for example , at the balance time @xmath229 , the horizontal and vertical leaves both make an angle @xmath230 with the @xmath231-geodesic representatives of @xmath158 . in this case , a leaf of @xmath232 or @xmath233 intersects @xmath234 approximately ( up to an error of @xmath235 ) @xmath236 times , so the modulus of @xmath237 is approximated by @xmath238 , where @xmath239 ( and @xmath240 ) means the twist in the @xmath113-metric restricted to @xmath241 . the result would follow on noting that @xmath242 and @xmath243 have opposite signs , except that @xmath244 involves hyperbolic twists on @xmath2 rather than @xmath113-twists in @xmath241 . this is resolved using proposition [ prop : twistcomparison ] , see @xcite for further details . that @xmath25 is coarsely the modulus of @xmath184 follows from theorem [ thm : modcomparison ] . the above is not the definition of @xmath24 given in @xcite , but it is coarsely equivalent . specifically , let @xmath245 be the ( possibly coincident ) thick components adjacent to @xmath22 in the thick - thin decomposition of the hyperbolic metric @xmath19 . set @xmath246 where @xmath247 is the length of the shortest non - trivial non - peripheral simple closed curve on @xmath248 with respect to the metric @xmath82 . ( if either @xmath248 is a pair of pants there is a slightly different definition , see @xcite . ) in @xcite , we took the above expression for @xmath249 as the definition of @xmath24 . proposition 5.9 in @xcite shows that if @xmath249 is sufficiently large , then @xmath250 with @xmath24 defined as in ( [ eqn : mode ] ) above . it follows from theorems [ thm : glshort ] and [ thm : gldistance ] that if @xmath251 for every @xmath22 that is short in @xmath19 , then the distance @xmath252 is uniformly bounded . and , if @xmath19 is in the thick part of space , then @xmath4 is too , so that on such intervals @xmath4 is quasi - geodesic . thus our attention is focused on time intervals along which @xmath24 is large . this is handled with the following more precise version of theorem [ thm : klarge0 ] : [ thm : klarge ] choose @xmath253 to be a constant such that if @xmath254 then @xmath22 is extremely short in @xmath19 . ( this is possible due to theorem [ thm : glshort ] . ) suppose that @xmath254 for all @xmath34 $ ] . then @xmath255 we prove the statement of the theorem ; the corollary is immediate . the idea is that for each @xmath34 $ ] , we cut the maximal flat annulus around @xmath22 in @xmath257 out of @xmath2 and reglue the two boundary components , obtaining a new surface @xmath258 , see figure [ fig : cutandreglue ] . the surfaces @xmath258 will also move along a geodesic . in particular @xmath259 . on the other hand , @xmath258 contains the same expanding cylinders round @xmath22 as @xmath260 so that @xmath261 . consideration of the rate of change of @xmath262 with time shows that the contribution to the change in distance between @xmath263 and @xmath264 from the expanding cylinders is on the order of @xmath265 , so that the actual distance @xmath38 must be realized due to changes in @xmath266 . in more detail , this works as follows . let @xmath267 be the maximal flat annulus around @xmath22 in @xmath268 . the arcs in @xmath269 that are perpendicular to @xmath270 define an isometry @xmath271 from one component of @xmath270 to the other . let @xmath263 be the surface obtained by removing @xmath269 and gluing the components of @xmath270 together via @xmath271 ( also making sure to preserve the marking ) , see the upper two surfaces in figure [ fig : cutandreglue ] . let @xmath272 be the gluing curve in @xmath263 . since the vertical and horizontal foliations of @xmath273 match along @xmath272 , the surface @xmath263 is naturally equipped with vertical and horizontal foliations @xmath274 and quadratic differential @xmath275 , which we assume is scaled to have area one . let @xmath276 be the geodesic corresponding to @xmath277 and let @xmath278 be the corresponding family of quadratic differentials . then @xmath259 . observe that the surface @xmath258 is obtained from @xmath260 by cutting the maximal flat annulus @xmath279 . thus , for each @xmath18 , we have a natural map @xmath280 which fixes points but scales the metric . hence , @xmath281 on @xmath40 $ ] and therefore @xmath22 is also extremely short in @xmath258 on @xmath40 $ ] . applying theorem [ thm : minskyproduct ] , we get @xmath282 to prove the theorem , it will suffice to establish the following two bounds : @xmath283 and @xmath284 the theorem would then follow from equations ( [ eqn : product]),([eqn : hyp]),([eqn : pinched ] ) , and the triangle inequality . we use the estimate of distance in @xmath285 from equation ( [ eqn : distance - in - h2 ] ) in section [ sec : minskyproduct ] . let @xmath286 , let @xmath287 , and let @xmath288 be the fenchel - nielsen twist coordinate of @xmath22 at @xmath289 . by ( [ eqn : distance - in - h2 ] ) we have @xmath290 we shall to show that the contribution @xmath291 coming from the twist can be neglected . by lemma [ lem : minskytwist ] , we have for any lamination @xmath42 : @xmath292 by proposition [ prop : twistcomparison ] with @xmath293 ( or @xmath294 ) , we have latexmath:[\ ] ] now on the one hand , by theorem [ thm : gldistance ] , the thick parts of @xmath36 and @xmath415 are bounded distance from one another , as are the those of @xmath37 and @xmath416 . therefore @xmath417 on the other hand , because the twisting is bounded as in theorems [ thm : gtwist ] and [ thm : ltwist ] , we have @xmath418 thus it follows that @xmath419 \displaystyle d_{\t(s_\gamma)}(\l_b , \g_b ) \ladd \frac12 \max_{\a \in \gamma_b } \ , \log \frac 1{l_{\l_b}(\a)}. \end{array}\ ] ] to bound the first and last terms of the right hand side , we will use and the fact that the length @xmath358 of a curve increases at rate at most @xmath204 . more precisely , notice that if @xmath426 then @xmath427 = [ a , c)$ ] for some @xmath428 . by definition of @xmath215 , we have @xmath429 . then it follows from theorem [ thm : glshort ] that @xmath430 is bounded below by a uniform constant that depends only on @xmath102 . therefore , by the observation following equation , we have @xmath431 similarly , if @xmath432 , then @xmath433 therefore , from it follows that @xmath434 the second term in is bounded by minsky s product regions theorem : @xmath435 this finishes the proof of the upper bound . we begin by reducing the problem to a consideration of the curves in @xmath130 only . it follows from a theorem of wolpert @xcite that for every @xmath438 , @xmath439 it follows as before from theorem [ thm : glshort ] that if @xmath103 , then the length @xmath358 is uniformly bounded below . therefore , we have : @xmath440 \displaystyle \bigg| \log \frac{l_{\l_a}(\a)}{l_{\l_b}(\a ) } \bigg| \gadd \log \frac{1}{l_{\l_b}(\a ) } \mbox { for } \a \in \gamma_b . \end{array}\ ] ] it follows from the triangle inequality that if either @xmath441 the lower bound is proved . thus we may assume that @xmath442 bringing us to the key part of the proof . from minsky s product region theorem , we have @xmath443.\ ] ] we claim that either @xmath444 , or that there is some @xmath137 such that @xmath445 and such that lemma [ lem : dichotomy ] ( ii ) or ( iii ) holds . after proving the claim , we will show that either alternative implies the required bound on @xmath446 . we are going to use an inductive argument for which it is important to note than we can choose the additive constant in minsky s product regions theorem to be fixed for all surfaces obtained from @xmath2 by cutting out any subset of curves in @xmath130 . if the maximum in is realized by @xmath447 , then obviously @xmath444 . if the maximum in is realized by @xmath448 for some @xmath449 , consider the alternatives for @xmath450 in lemma [ lem : dichotomy ] . if ( i ) holds , then by theorem [ thm : klarge ] we have @xmath451 . in this case , we apply minsky s product regions theorem to @xmath452 , giving @xmath453.\ ] ] now repeat the same argument ; if the maximum in is realized by @xmath454 for some @xmath455 that satisfies lemma [ lem : dichotomy ] ( i ) , then apply the product regions theorem to @xmath456 . eventually , up to a finite number of changes to the additive constants , either there must be some @xmath137 for which @xmath457 such that lemma [ lem : dichotomy ] ( i ) does not hold , or it must be that @xmath444 . the claim follows . now assume the alternative : that there is some @xmath137 such that @xmath457 and such that lemma [ lem : dichotomy ] ( ii ) or ( iii ) holds . assume ( ii ) holds : we have that @xmath251 on an interval @xmath377 $ ] and consider the following two cases depending on the length of @xmath377 $ ] . ( case ( iii ) can be handled similarly . ) if @xmath459 , then the triangle inequality and lemma [ lem : hldistance ] give @xmath460 ( strictly speaking , it may be that @xmath461 for some values of @xmath220 $ ] . however , lemma [ lem : dandk ] implies that @xmath351 on @xmath379 $ ] , and this is sufficient to guarantee that @xmath462 , see the proof of lemma [ lem : hldistance ] ) . if @xmath463 , then consider the triangle inequality @xmath464 similarly to our previous argument , since the twisting is bounded as in theorems [ thm : gtwist ] and [ thm : ltwist ] , we have @xmath465 since @xmath466 it follows from theorem [ thm : glshort ] that @xmath467 since lemma [ lem : dichotomy ] ( ii ) holds , it follows from the assumption @xmath463 that @xmath468 thus , in this case we have @xmath469 this concludes the proof . @xmath470 k. rafi , `` a combinatorial model for the teichmller metric '' , _ geom . * 17 * ( 2007 ) 936659 . k. rafi , `` thick - thin decomposition of quadratic differentials '' , _ math . _ , * 14 * ( 2007 ) 333342 .

we continue the comparison between lines of minima and teichmller geodesics begun in @xcite . for two measured laminations @xmath0 and @xmath1 that fill up a hyperbolizable surface @xmath2 and for @xmath3 , let @xmath4 be the unique hyperbolic surface that minimizes the length function @xmath5 on space . we prove that the path @xmath6 is a teichmller quasi - geodesic .

topological sigma models , first put forward by witten @xcite , have long fascinated a number of theoretical physicists and mathematicians . most remarkably , the task of summing up worldsheet instantons is nowadays elegantly formulated by the theory of gromov - witten invariants . explicit computations of them are still being actively pursued . it goes without saying that among many possible target spaces calabi - yau threefolds have played distinguished roles and are of lasting interest to string theorists . since the initial appreciation of the significance of d - branes there has been the lingering hope that the gromov - witten theory of calabi - yau threefolds might be completely rewritten in the language of bps d - branes . this contribution is intended for explaining the picture which , to my eye , looks particularly attractive in this regard . this is based on the general philosophy : _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ the geometry of @xmath0-@xmath1 branes ( and _ not _ simply @xmath0-branes ) provides an alternative description of gromov - witten invariants of calabi - yau threefolds . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ what we actually imagine is very simple and intuitive : in analogy with the ( generalized ) super kac - moody algebras we regard the string partition function as the inverse of denominator function " and interpret the bound state degeneracies of @xmath0-@xmath1 branes as the super root multiplicities " . the gromov - witten potentials are then extracted from the string partition function . in particular , the variable @xmath2 measuring @xmath1-charge is related to the genus expansion parameter @xmath3 of gromov - witten theory by @xmath4 . this sort of idea was formerly presented in @xcite when the calabi - yau threefold is elliptically fibered over a hirzebruch surface . there , an analogy to borcherds products @xcite was pursued . recall that borcherds products or their inverses arise in some cases as the denominator functions of generalized ( super ) kac - moody algebras . the first hint of the relevance of borcherds products to gromov - witten theory was given by harvey and moore @xcite . i will report further progress on the string partition functions of these elliptic calabi - yau threefolds elsewhere @xcite . so the first purpose of this work is simply to extend the @xmath0-@xmath1 picture of @xcite to general calabi - yau threefolds focusing on those aspects which are believed to be independent of any particular details of the threefolds . some time ago gopakumar and vafa @xcite proposed an alternative reformulation of gromov - witten theory of calabi - yau threefolds based on the space - time effective theory interpretation of gromov - witten potentials . this claim has been influential but at the same time very mysterious ( at least to the author ) . the second objective of this paper is to discuss how this proposal of gopakumar and vafa may actually reconcile with ours . quite recently , the relation between singular instantons of @xmath5 @xmath6 gauge theory and gromov - witten theory has been discussed @xcite in relation to the topological vertex formalism @xcite . this gauge theoretic approach ( donaldson - thomas theory ) is probably a dual viewpoint of our @xmath0-@xmath1 picture in the same way point - like instantons of @xmath7 @xmath6 gauge theory describe @xmath1-branes . so , as far as the ideology is concerned , these works seem to have some overlaps with @xcite and the present work . nevertheless , there is a marked difference in practice : they discuss the sum side " with a supply of explicit calculations for local toric calabi - yau threefolds using the localization technique whilst we discuss the product side " inspired from the examples of certain elliptic calabi - yau threefolds and the associated borcherds - like products @xcite@xcite . it will be very interesting ( and necessary ! ) to investigate the existence of sum = product " formulas connecting both sides for a general calabi - yau threefold . in fact , the topological vertex formalism of @xcite seems to allow an intuitive understanding in terms of @xmath0-branes and @xmath1-branes . [ comment ] for comments on this point . i am grateful to k. yoshioka for the collaboration in @xcite . i also thank a. okounkov for kindly pointing out my nonsensical statement in the previous version of the manuscript and for explaining to me the marvelous proposal of him and his collaborators . . for a rational function @xmath8 of one variable @xmath2 we define @xmath9 as follows : @xmath10 is the laurent series of @xmath8 at @xmath11 and @xmath12 is that at @xmath13 . consider , for instance , @xmath14 for an integer @xmath15 . if @xmath16 then @xmath17 and @xmath18 coincide in @xmath19 $ ] . however , @xmath20\,.\ ] ] a calabi - yau threefold @xmath21 is a complex 3-dimensional smooth projective variety with @xmath22 and @xmath23 . we assume that @xmath21 is polarized by some ample line bundle . if one ever wishes to connect gromov - witten theory of calabi - yau threefolds to some sort of of bps @xmath24-brane counting , one might think that @xmath0-branes alone are relevant since gromov - witten theory is concerned with curve counting problems . however , this is too naive and even misleading . what needs to be emphasized is that in any attempt of this sort we have to incorporate the effects of @xmath1-branes in addition to @xmath0-branes . take as an example the case of a resolved conifold , the total space of @xmath25 . since the @xmath26 in the resolved conifold is rigid and the jacobian of @xmath26 is just a point , the moduli space of @xmath0-brane wrapping around the @xmath26 is also a point . if @xmath0-branes were the only relevant @xmath24-branes , this would mean that the gromov - witten theory of the resolved conifold was trivial . this is simply absurd given the result of @xcite . the origin for the necessity of @xmath1-branes may be roughly as follows . let us suppose that we are trying to answer the problem of counting curves in a calabi - yau threefold @xmath21 . there could be several different approaches according what we mean by _ counting_. in a crude approach by @xmath24-branes one may make curves charged " by putting line bundles , ( or more generally , rank one torsion - free sheaves ) on them and then claim , to within signs , the euler - poincar ' e characteristics of the moduli spaces of such sheaves ( regarded as torsion sheaves on @xmath21 ) with fixed @xmath24-brane charges as the numbers of curves " . apparently , in this naive approach we are concerned with @xmath0-branes alone . in gromov - witten theory , on the other hand , one tries to count holomorphic maps " from worldsheet connected curves to target curves in @xmath21 and regard this as a good substitute of directly counting curves in @xmath21 . however , this very substitution introduces some well - known complications . one of them is the so - called multi - covering effect . this is rather innocuous since we know more or less how to handle it . another complication , which seems to be more difficult , is related to conformal invariance of the holomorphic map equation and is known as bubbling phenomena . in order to have a nice intersection theory one must compactify the moduli space of holomorphic maps . for this we have to include degenerate contributions of bubble trees ( bubbling of bubbling of ) . it should be precisely for this reason that we have to modify the naive @xmath0-brane approach by including @xmath1-branes when one attempts to rewrite gromov - witten theory in terms of @xmath24-branes . an intuitive picture of @xmath1-branes bound to a @xmath0-brane is that of vortices . so morally speaking , _ bubble trees turn into vortices_. suppose that we are given a super kac - moody algebra . let @xmath27 denote the additive semigroup generated by simple roots . we write @xmath28 iff @xmath29 . any @xmath28 is either even or odd . consider @xmath30 so that @xmath28 is a positive root iff @xmath31 . we have @xmath32 where @xmath33 is the @xmath34-th adams operation sending @xmath35 to @xmath36 . the right hand side is the inverse of the denominator function in the product form . in a nutshell , what we intend to do is to make the analogy of this relation in studying a calabi - yau threefold @xmath21 . we express any element of @xmath37 as @xmath38 where @xmath39 and @xmath40 . denote by @xmath41 the additive semigroup of classes of effective 1-cycles ( holomorpic curves " ) on @xmath21 . in other words , @xmath41 is the intersection of the mori cone with @xmath42 . we write @xmath43 iff @xmath44 . similarly , for @xmath45 we write @xmath46 iff @xmath47 \quad \text{or}\quad \bigl[\beta=0 \text{\ and\ } j>0\bigr]\,.\ ] ] assume that there is a suitable @xmath48-grading so that any @xmath46 is either even or odd . now let us suppose in analogy with @xmath49 the existence of a formal sum : @xmath50 where @xmath51 is a formal symbol satisfying @xmath52 . in the proposal below , @xmath53 is in @xmath54 rather than in @xmath55 . this is to match up with the normalization of gromov - witten potentials . we next introduce the formal truncated . ] free energy @xmath56 where @xmath33 is again the @xmath34-th adams operation sending @xmath57 to @xmath58 . as the inverse of the denominator function " we are led to consider the following formal product @xmath59 we might call @xmath60 as the formal truncated string partition function . however the expected relation @xmath61 " is rather problematic since , in the formal sum , @xmath62 runs over all integers when @xmath43 so that powers of @xmath63 are not well - defined in general . thus @xmath63 and @xmath60 in the above should be interpreted at best as motivating expressions . in the following we will introduce regularized versions @xmath64 and @xmath65 related by @xmath66 . ( these are better behaved but somewhat lose direct analogy with super kac - moody algebras . ) those who are familiar with borcherds products and their relations to surfaces , say , @xmath67 surfaces will recognize that we are trying to cook up a similar story for calabi - yau threefolds here . a novel and distinct point is the introduction of @xmath68 in addition to @xmath42 . i intend to further discuss this similarity with borcherds products in @xcite . for the above analogy to be anything useful we have to know @xmath69 from the geometry of @xmath21 . our basic expectation is that @xmath70 should be , in some way or another , identified with the ( super ) degeneracy of bounded @xmath0-@xmath1 branes in @xmath21 with a fixed @xmath0-@xmath1 charge @xmath38 . therefore , what needs to be done is the geometrical understanding of @xmath0-@xmath1 bound systems . we first recall the gentlemen s agreement @xcite that even - dimensional @xmath24-branes are related to coherent sheaves and their @xmath24-brane charges are determined by mukai vectors @xcite . we define the @xmath24-brane charge @xmath71 of a coherent sheaf @xmath72 on @xmath21 by @xmath73 $ ] where @xmath74 is the mukai vector of @xmath72 . we express @xmath71 in the form @xmath75 where @xmath76 . note that if the @xmath24-brane charge is of the form @xmath77 then @xmath78 is actually in @xmath79 . ( there is no witten effect . ) for instance , suppose that @xmath80 is a smooth irreducible curve of genus @xmath81 and @xmath82 is a line bundle of degree @xmath83 , then @xmath84 , \chi(c , l))=(0,0,[c],d+1-g)$ ] . this is the @xmath24-brane charge of a @xmath0-brane singly wrapping around @xmath85 bound with @xmath83 @xmath1-branes . in this paper any @xmath0-brane is always singly wrapping by allowing non - reduced curves . if the @xmath24-brane charge ( or equivalently the mukai vector ) is fixed , the hilbert polynomial is also fixed since @xmath21 is assumed to be polarized . so it makes sense to consider the moduli space @xmath86 of semi - stable coherent sheaves on @xmath21 with a fixed @xmath24-brane charge @xmath87 . for simplicity let us suppose that @xmath86 consists only of stable sheaves . one well - known fact about @xmath86 is that its expected dimension @xmath88 vanishes because of the serre duality where @xmath89 and @xmath90 is the trace free part of @xmath91 . by stability , @xmath92 and by @xmath23 , we have @xmath93 @xmath94 . the zero - dimensional virtual moduli cycle was constructed in @xcite . its degree or virtual length @xmath95 serves as the number of sheaves " . the zariski tangent space of @xmath86 at @xmath72 is given by @xmath96 and the obstruction space is @xmath97 . hence the serre duality tells us that if @xmath86 is smooth , the obstruction sheaf is the cotangent bundle of @xmath86 and @xmath98 . one can also consider the hilbert scheme @xmath99 with a fixed @xmath24-brane charge @xmath87 . as usual , we have @xmath100 by considering ideal sheaves . the moduli space of possibly disconnected @xmath0-branes and @xmath1-branes , which we call the total @xmath0-@xmath1 moduli space , is given by @xmath101 where @xmath78 runs over all possible values . at first sight seems not to deserve its name . for instance , if an isolated @xmath0-brane is singly wrapping around a smooth curve @xmath102 , there should exist degrees of freedom in how it wraps , namely the jacobian @xmath103 . on the other hand in the hilbert scheme @xmath85 is allowed to carry only @xmath104 . a possible resolution of this puzzle may be as follows . first of all if a @xmath0-brane wrapping singly around @xmath85 is bounded to several @xmath1-branes , the moduli space of this bound system is given by a symmetric product of @xmath85 ( as we recall later ) . so this part of the moduli space is directly related to the hilbert scheme . the pure @xmath0-brane moduli space @xmath103 is actually related to the symmetric products of @xmath85 through the abel - jacobi maps . so , once we start to consider both @xmath0-branes and @xmath1-branes simultaneously , we should forget about @xmath103 and only consider the symmetric products of @xmath85 as fundamental in order not to overcount the degrees of freedom . a more explanation is given below about how pure @xmath0-brane moduli spaces are related to the moduli spaces of bounded @xmath0-@xmath1 branes . ( this is not unrelated to the upcoming interpretation of the gopakumar - vafa proposal . ) a relation between @xmath105 and gromov - witten invariants was already hinted in @xcite . a connection to the gopakumar - vafa invariant was conjectured in @xcite . recently , a striking connection of @xmath106 to gromov - witten theory has been proposed in @xcite . we expect that @xmath69 is related to but exactly describing this relation seems to be a very difficult problem at the moment . only a limited attempt is given below . let us call @xmath107 _ of simple class _ _ _ _ _ if its arithmetic genus @xmath108 is non - negative and for each integer @xmath109 there exist a suitable @xmath0-@xmath1 bound moduli space @xmath110 and a @xmath0 moduli space @xmath111 whose properties we spell out in the following . we assume that @xmath112 is of simple class and set @xmath113 . the @xmath0-@xmath1 bound moduli space @xmath110 describes a @xmath0-brane wrapping around a curve of class @xmath114 bound to @xmath83 @xmath1-branes . in particular we expect an intimate connection between @xmath110 and @xmath115 . we assume that @xmath110 is smooth and connected . as we will see shortly , it seems natural to have @xmath116 we set @xmath117 for convenience . this is the moduli space of the _ supports _ of @xmath0-branes . note that @xmath118 by . there should exist a morphism @xmath119 and @xmath120 moreover , there will be the universal family @xmath121 which is a flat family of curves of class @xmath114 and of arithmetic genus @xmath108 . in particular we expect @xmath122 where the morphism @xmath123 is the projection . intuitively speaking , @xmath124 is the family of curves around which @xmath0-branes are singly wrapping . in favorable situations it is tempting to identify @xmath125 with the relative hilbert scheme of points on curves @xmath126}:=\operatorname{hilb}^d_{\mathcal{c}_\beta/ s_\beta}\,.\ ] ] since we assumed that @xmath110 is smooth , our concern is limited to a smooth @xmath127}$ ] . let us explain why and seem natural . we regard @xmath128 as the moduli space of the bound system of a @xmath0-brane and @xmath83 @xmath1-branes in the limit where the support curve of the @xmath0-brane is shrinking to a point . what does the curve look like ? since we do not expect any @xmath0-brane degree of freedom in the end , the jacobian of the curve must be a point . so the curve will be a @xmath26 . with the vortex interpretation given in @xcite and to be recalled later , the moduli space of the @xmath0-brane wrapping around @xmath26 and @xmath83 @xmath1-branes sticked to it should be given by the @xmath83-th symmetric product of @xmath26 or @xmath129 . therefore if we take into account the location of the shrinking @xmath26 in @xmath21 , we are led to and . let us turn to the properties of the @xmath0 moduli space . we assume that @xmath111 is smooth and connected . there should exist a natural morphism @xmath130 . intuitively , @xmath111 is the moduli space of @xmath0-branes singly wrapping around fibers of @xmath121 . we expect an intimate connection between @xmath111 and @xmath131 . we furthermore expect that @xmath111 is independent of @xmath83 and is isomorphic to @xmath132 . we should have @xmath133 . hence @xmath134 is the identity map . we require the existence of a commutative diagram @xmath135\ar[dr]&\\ \mathfrak{n}_\beta\ar[rr]&&s_\beta}\ ] ] for @xmath112 we have by obvious morphisms . for @xmath136 , @xmath137 may be viewed as taking a section . if @xmath138}$ ] , one may take @xmath139 where @xmath140 is the relative compactified picard scheme and @xmath141 is the relative compactified jacobian . then the diagram is replaced by @xmath142}_\beta\ar[dl]\ar[dr]&\\ \bar{\mathcal{j}}_\beta\ar[rr]&&s_\beta}\ ] ] the morphism @xmath127}\to \bar{\mathcal{j}}_\beta$ ] is just the abel - jacobi map . we should have @xmath143 this ends the list of what we demand for @xmath114 to be of simple class . we now turn to our proposal on the structure of @xmath69 : by taking into account charge conjugation symmetry , we have @xmath144 where @xmath145 and if @xmath114 is of simple class @xmath146 with @xmath147 this looks like the most natural extension of what we conceived in @xcite . the reason why we choose the particular sign factor is explained below by comparison with gromov - witten theory . note that even if @xmath110 is non - empty , @xmath148 can vanish . in our analogy with super kac - moody algebras this is related to the vanishing of @xmath53 when @xmath38 is not a positive root " . at the moment we do not know how exactly @xmath149 should be described geometrically when @xmath114 is other than of simple class . to make contact with gromov - witten theory we further postulate for each @xmath107 there exists a rational function @xmath150 with inversion symmetry @xmath151 such that @xmath152 if @xmath114 is of simple class , we introduce @xmath153 by @xmath154 , namely , @xmath155 moreover we have the expansion of the form @xmath156 where @xmath4 and @xmath157 . one then observes that @xmath158 so far @xmath51 has been a formal symbol , but in gromov - witten theory we should like to set @xmath159 where @xmath160 is the complexified k " ahler form of @xmath21 . therefore , motivated by , we introduce @xmath161 and interpret this as a power series expansion in @xmath162 @xmath163 . here @xmath164 are generators of the mori cone . in addition one may introduce the truncated free energy by @xmath165 and the truncated string partition function @xmath166 . then , if @xmath167 for all @xmath168 and @xmath169 , we have an infinite product representation : @xmath170 where @xmath171 by we have @xmath172 . hence we have @xmath173 because of @xmath174 . to discuss the relation to gromov - witten theory we want to set @xmath4 with @xmath175 and @xmath176 very small and interpret @xmath3 as the genus expansion parameter . as above we always assume @xmath177 for @xmath43 in the following . for such expansions in @xmath3 to be possible , the truncated free energy needs a bit of regularization : @xmath178 let us introduce @xmath179 via the expansion @xmath180 and define @xmath181,\ ] ] where @xmath182 is the euler - mascheroni constant . the gromov - witten potentials @xmath183 @xmath184 of @xmath21 are given by @xmath185 where @xmath186 [ remweyl ] in seeking analogy with super kac - moody algebras @xmath187 should be interpreted as ( the negative of ) the weyl vector " . this part is quite delicate and important . in fact by using we find that @xmath188 where @xmath189 if @xmath190 and @xmath191 . this is an expected form . let us give some evidence for our choice . note first that @xmath192 and @xmath193 this enables us to calculate @xmath194 explicitly . for @xmath195 , we have @xmath196 . this is familiar to us . as for @xmath197 , the constant map contribution is correctly reproduced : @xmath198 where @xmath199 is the deligne - mumford moduli stack of stable curves of arithmetic genus @xmath81 without marked points and @xmath200 is the @xmath201-th chern class of the hodge bundle over @xmath199 . the relation was conjectured physically in @xcite from @xmath202-theory interpretation and in @xcite from duality to heterotic string . a mathematical proof of was given in @xcite . an argument here from a purely @xmath0-@xmath1 point of view is new . suppose that @xmath114 is of simple class and that both @xmath203 and @xmath204 are smooth . assume that _ all _ the fibers of @xmath121 are smooth irreducible curves of genus @xmath108 . then the vortex interpretation explained below shows that @xmath205 if @xmath206 we see that @xmath207 . this is consistent with gromov - witten theory . not infrequently we encounter non - trivial formulas of the form @xmath208 so far we have been discussing the product side . it is natural to ask what the sum side looks like . obviously , the sum should be taken over potentially all the @xmath0-@xmath1 states . so the total @xmath0-@xmath1 moduli space will be relevant . quite recently @xcite , in an attempt to understand the formalism of the topological vertex for local calabi - yau threefolds , the connection between singular instantons of @xmath5 @xmath6 gauge theory and gromov - witten theory has been studied . this is expected to be another description of our @xmath0-@xmath1 picture studied on the sum side . in particular , @xcite treats local calabi - yau threefolds and evaluates , by the localization technique , the generating function of @xmath105 for the moduli spaces of ideal sheaves @xmath209 . this is a very explicit and remarkable calculation . in fact the topological vertex formalism @xcite fits quite nicely into the picture of @xmath0-@xmath1 branes . for a local toric calabi - yau threefold , the relevant sum is reduced by localization to the one over the torus - fixed configurations of @xmath0-@xmath1 branes . in the approach of @xcite one writes the diagram consisting of edges and trivalent vertices . each internal edge corresponds to a @xmath210-fixed @xmath26 . each vertex corresponds to a @xmath211-fixed point and is the north or south poles of the @xmath26 s of the internal edges emanating from it . it is clear that the torus - fixed configurations of @xmath0-@xmath1 branes are such that @xmath0-branes are localized to the @xmath210-fixed @xmath26 s ( the internal edges ) and @xmath1-branes are localized to the @xmath211-fixed points ( the vertices ) . the way several @xmath0-branes are localized to the internal edge @xmath26 s must be treated scheme - theoretically and described by assigning a @xmath212 young diagram to each edge . similarly , the way @xmath1-branes accumulate to the vertex points must also be treated scheme - theoretically and described by assigning a @xmath213 young diagram to each vertex . however the configurations of @xmath1-branes and those of @xmath0-branes are not independent . how these are actually linked is specified by the rule of the topological vertex . it should be mentioned that having a nice sum expression does not a priori guarantee the connection to gromov - witten theory . for such to exist sum = product " will probably have to hold . for super ( generalized ) kac - moody algebras , this problem is related to finding the set of positive roots among @xmath27 , which in general is a subtle and difficult task . obviously , if our `` product '' proposal and the sum " proposal ( gw / dt correspondence ) of @xcite are consistent , @xmath214 and @xmath215 must be related . this looks plausible since both are concerned with counting @xmath0 and @xmath1 branes in @xmath21 . however , the precise geometrical characterization of @xmath214 is yet to be found . in @xcite , gopakumar and vafa asserted that the @xmath0-brane moduli spaces of a calabi - yau threefold @xmath21 have some characteristic properties . we considered the @xmath0 moduli space @xmath216 when @xmath114 is of simple class and assumed that @xmath216 is smooth . to recall the gopakumar - vafa proposal , let us temporarily lift the smoothness condition of @xmath216 . in this slightly more general context , we cast their claim taking into account the suggestion of @xcite as follows : let @xmath217 denote the intersection cohomologies of @xmath216 . there exists a representation @xmath218 in such a way that the restricted representations @xmath219 associated respectively with the first , the second and the diagonal @xmath220 subalgebras of @xmath221 have the following interpretations : @xmath222 resp . @xmath223 corresponds to the lefschetz action in the fiber resp . base direction " of the cohomologies of @xmath224 while @xmath225 corresponds to the usual lefschetz action . hence one can introduce @xmath226\,,\ ] ] where @xmath227 and @xmath228 are respectively the images by @xmath222 and @xmath225 of the cartan generator of @xmath220 . ( the eigenvalues of @xmath227 and @xmath228 are twice spins . ) note the obvious symmetry @xmath229 . according to @xcite , this claim is true if @xmath224 is a projective morphism between two normal projective varieties . in the rest of the paper we only consider the cases when @xmath114 s are of simple class . hence @xmath110 and @xmath216 do exist and they are smooth and connected . when dealing with @xmath216 we do not need @xmath230 and @xmath231 will suffice . gopakumar and vafa argued that @xmath232 s determine the gromov - witten potentials of @xmath21 . in particular , considering certain combinations of irreducible representations of @xmath220 to be fundamental , they expanded @xmath232 as @xmath233 then they considered that the integers @xmath234 are alternative fundamental invariants here . ] . since @xmath228 acts as the multiplication of @xmath235 on @xmath236 , we have @xmath237 . this claim of gopakumar and vafa may sound somewhat at odds with our earlier statement : _ considering @xmath0-branes alone is insufficient_. actually they mapped the problem into @xmath202-theory and used a physical interpretation of space - time effective theory typically using schwinger - like computations . this is the reason why @xmath1-branes secretly sneak in when interpreted in terms of type iia theory . the consistency of our proposal with that of gopakumar and vafa implies @xmath238 since @xmath239 and the fiber direction " is void , we have @xmath240 . consequently is true for @xmath112 . despite its innocent looking the geometrical implication of is rather non - trivial since the interpretations are quite different on both sides of the equation . before discussing the validity of let us pause to study purely algebraic consequences of . we expand @xmath241 as and @xmath232 as . if we set @xmath242 then the following proposition gives the explicit relations between @xmath148 and @xmath234 . note that since @xmath243 by our definition , the relation @xmath244 below implies @xmath245 . [ invprop ] let @xmath246 be an integer . suppose that sequences of numbers @xmath247 and @xmath248 are related by @xmath249 one can express @xmath247 in terms of @xmath248 as : @xmath250 conversely , @xmath248 can be expressed in terms of @xmath251 as : @xmath252 if @xmath247 are integers , so are @xmath248 and vice versa . implies the following taylor expansion at @xmath11 : @xmath253 it suffices to analyze this equation . ( a ) this is a consequence of straightforward binomial expansions of the right hand side of . since the cases @xmath195 and @xmath254 are obvious , we assume @xmath255 . notice that is equivalent to @xmath256 then , by the lagrange inversion formula , one finds @xmath257\\ & = \operatorname{res}_{y=0}\left[\frac{1+y}{(1-y)^{2(g - i)-1}}\sum_{d=0}^\infty e_d\ , y^{d - i-1}\right ] , \end{split}\ ] ] where @xmath258 represents the derivative with respect to @xmath2 . to evaluate this residue it is better to proceed case by case : + suppose that @xmath259 . then we actually have to have @xmath260 and @xmath261.\ ] ] it is straightforward to evaluate this residue . the result is given by . + suppose instead that @xmath262 . one uses the formula@xmath263 ( valid for a positive integer @xmath34 ) to obtain @xmath264.\ ] ] if @xmath265 one easily sees that @xmath266 . if @xmath267 , the evaluation of the residue gives @xmath268 which can be rewritten as . this is already obvious from what we have seen in this proof . we briefly recall the vortex picture of @xmath0-@xmath1 branes . for more on this see @xcite . let @xmath102 be a smooth irreducible curve of genus @xmath81 which is rigid in @xmath21 . suppose that a @xmath0-brane is singly wrapping around @xmath85 and @xmath83 @xmath1-branes are bound to it . such a bps system may be identified with vortices on @xmath85 with magnetic flux @xmath83 . as well - known the moduli space of such vortices is the @xmath83-th symmetric product of @xmath85 which we write as @xmath269 . there exists a classical result by macdonald on the euler - poincar ' e characteristics of symmetric products of smooth curves . as argued in @xcite , by taking into account the fact that @xmath24-brane charges must be measured by mukai vectors , it is more natural to consider a twisted version of macdonald formula : @xmath270 a naive way to treat @xmath0-@xmath1 branes in more general settings is to extend the vortex picture relatively and to replace @xmath269 by @xmath127}$ ] . to simplify the situation considerably we make a rather strong [ ass - integral ] all the fibers of @xmath121 are integral . we have @xmath138}$ ] and @xmath271 . hence , @xmath272}_\beta)y^{\pm(d+1-g(\beta))}=\iota_\pm f_\beta(y)\,.\ ] ] from this immediately follows . consider for instance the case of @xmath25 . let @xmath273 $ ] denote the class of the @xmath26 . then , @xmath274}(y)=(y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{-2}\,,\ ] ] and @xmath275}(y)=0 $ ] for @xmath276 . this expression can also be obtained ( in a difficult way ! ) either by gromov - witten theory @xcite or by the topological vertex formalism @xcite . in [ why ] we said that bubble trees in gromov - witten theory turn into @xmath1-branes ( vortices ) . it is instructive to see how this happens on this simple example . in @xcite , the authors use the localization technique to evaluate the gromov - witten invariants . this boils down to calculate the bubbling contributions at the north and south poles of the @xmath26 . on the other hand , the approach of the topological vertex gives a diagram consisting of one internal edge corresponding to the @xmath26 and two trivalent vertices corresponding to the north and south poles . the torus - fixed @xmath0-@xmath1 configurations relevant to calculate @xmath277}(y)$ ] is such that a @xmath0-brane wraps singly around the @xmath26 ( so the @xmath212 young diagram is a single box ) and @xmath1-branes are localized to the north or south poles , _ i.e. _ the two vertices . we also note that has an interpretation as a two - point function of vertex operators @xcite ( see also @xcite ) . this matches well with the appearance of the schur polynomials in the approach of @xcite . in the simplified setting we assume later , we will find that @xmath153 has an expansion of the form @xmath278 with @xmath279 and @xmath280 being a rational function . in fact there arise at least two natural choices of basis functions @xmath281 . one choice is associated with gopakumar - vafa s expansion and @xmath281 takes a simple form . the other choice has a clear geometrical meaning but @xmath281 takes a more complicated form . in @xcite we studied an analogous case with @xmath21 replaced by a projective @xmath67 surface @xmath202 . corresponding to @xmath121 in the present situation we considered the universal family of curves @xmath282 where @xmath283 is a smooth ( integral ) curve of genus @xmath284 on @xmath202 . associated to @xmath285 one considers the relative compactified jacobian @xmath286 together with the abel - jacobi map @xmath287}\to \bar{\mathcal{j}}_n $ ] . with the technical assumptions there , all the fibers of @xmath285 are integral and both @xmath287}$ ] and @xmath288 are smooth . in @xcite we proved an exact formula for @xmath289}_n)y^{\pm(d+1-n)}\,.\ ] ] ( the proof there rested on brill - noether theory of sheaves on @xmath67 surfaces developed by yoshioka @xcite and markman @xcite . ) in @xcite , the authors tried to develop an algorithm for calculating the numbers @xmath234 and in the process of this they also considered @xmath127}$ ] . however in their treatment it played only an auxiliary role since their point of view is that of gopakumar - vafa and not of the @xmath0-@xmath1 picture . they applied their formalism to concrete examples and obtained satisfactory results with the caveat that one must be careful when there are reducible fibers in the family of curves ( _ e.g. _ the case of local @xmath290 ) . in the following we will see that some of their findings can be uniformly understood once one considers the relation between the gopakumar - vafa picture and the @xmath0-@xmath1 picture . let @xmath85 be a smooth irreducible curve of genus @xmath81 and let @xmath103 be its jacobian . we have @xmath291 where @xmath292 is the image of the cartan generator of the lefschetz @xmath220 as before . rather trivially , it follows that @xmath293 what implies is that one may proceed relatively : [ clconj ] @xmath294}_\beta)y^{\pm(d+1-g(\beta))}=\iota_\pm \frac{\epsilon(\beta)\lambda_\beta(y ) } { ( y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{2}}\,.\ ] ] this is not obvious at all since there can be singular fibers in @xmath121 . however , with some simplifying assumptions , this conjecture can be shown to be true . see theorem [ mainth ] . notice that one may take @xmath295 and @xmath296 in . conjecture [ clconj ] implies relations between @xmath297})$ ] and @xmath234 again by proposition [ invprop ] . in particular , we note that coincides with the relation claimed in @xcite . if @xmath298 the abel - jacobi map @xmath299}_\beta\to{\bar { \mathcal{j}}}_\beta$ ] is a fibration with fiber @xmath300 . since @xmath301 , the relation @xmath302 is just a reflection of this projective bundle structure . it is again instructive to see the situation for the @xmath67 surface @xmath202 as before . there is little harm in replacing @xmath303 by the hilbert scheme of points @xmath304}:=\operatorname{hilb}^n_m$ ] . when one views @xmath304}$ ] as a compact hyperk " ahler manifold of real dimension @xmath305 , there are a triple of k " ahler forms @xmath306 and therefore a triple of lefschetz actions @xmath307}))$ ] . according to verbitsky @xcite , @xmath308 generate an action of @xmath309 on @xmath310})$ ] . gopakumar - vafa s @xmath221 should be identified ( with the replacement of @xmath303 by @xmath304}$ ] understood ) as a subalgebra of verbitsky s @xmath309 . we choose one complex structure on @xmath304}$ ] thereby viewing it as an irreducible holomorphic symplectic manifold of complex dimension @xmath311 . denote the associated k " ahler form by @xmath312 . then @xmath313}))$ ] should be identified with the usual lefschetz action . so the lowering operator of the @xmath220 is represented by the wedge operation of @xmath312 and the raising one by its adjoint . on the other hand , as we will justify shortly , @xmath314}))$ ] should be identified with the holomorphic lefschetz action first considered by fujiki @xcite . so the lowering operator is represented by the wedge operation of a holomorphic 2-form @xmath315},\omega_{m^{[n]}}^2)$ ] and the raising one by its adjoint . apparently an analog of @xmath232 is @xmath316})}(-1)^{h_d}y^{h_l}\,.\ ] ] ( thompson s observation ) with the convention that @xmath317 is meant for @xmath318 in the original sense of hirzebruch , we have @xmath319})\,.\ ] ] since @xmath228 acts as the multiplication of @xmath320 on @xmath321},\omega_{m^{[n]}}^p)$ ] and we have @xmath322 , we see that @xmath323 is precisely what thompson writes as @xmath324 in @xcite with @xmath2 being one of the eigenvalue of @xmath325 . ( amusingly , @xmath324 is the rozansky - witten invariant of a mapping torus @xmath326 if @xmath327 . ) so is just a consequence of his observation . to our please we showed in @xcite that @xmath289}_n)y^{\pm(d+1-n)}=\iota_\pm\frac { y^{-n}\chi_y(m^{[n]})}{(y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{2}}\,.\ ] ] ( this was proved by comparing our formula for @xmath328})$ ] and the formula for @xmath329})$ ] proved earlier by g " ottsche and soergel @xcite . ) note that what corresponds to @xmath330 is @xmath331 . as a preparation for the next section we make a digression to study hilbert schemes of points on nodal curves . it is well - known that @xmath332}:=\operatorname{hilb}^d_c$ ] coincides with @xmath269 if @xmath85 is smooth . this , however , is not the case when @xmath85 is singular . suppose that @xmath333 is an integral curve of arithmetic genus @xmath81 having @xmath334 nodes and no other singularities . in this case we say that @xmath333 is @xmath334-nodal . note that @xmath335 . let @xmath336 be the normalization . then @xmath337 . in general @xmath338 for the hilbert schemes we have to find the necessary correction terms to this formula , which we now turn to . we introduce the standard notation for multinomial coefficients . @xmath339 recall that a _ partition _ is any sequence @xmath340 of non - negative integers in non - increasing order and containing only finitely many non - zero terms . then @xmath341 is the _ weight _ of @xmath342 and we say @xmath342 is a _ partition of @xmath83 _ if @xmath343 . when @xmath342 is a partition of @xmath83 , we also use an alternative notation @xmath344 where @xmath345 is the multiplicity of @xmath346 in @xmath342 . ( note that @xmath347 might be zero . ) we set @xmath348 for convenience . if @xmath344 is a partition of @xmath83 , we define @xmath349 by @xmath350 @xmath351}_{g,\delta})=\sum_{\substack{\lambda=(1^{\delta_1}\cdots d^{\delta_d})\\[2pt ] { { \lvert\lambda\rvert}=d,\ \check \delta}_1\le \delta } } a_\lambda\ , \binom{\delta}{\delta-{\check \delta}_1,\delta_2,\dots,\delta_d } \binom{\delta_1 + 1+\delta-{\check \delta}_1 - 2g}{\delta_1}\,.\ ] ] we assume @xmath352 since otherwise the assertion is trivial . let @xmath353 be the zero - dimensional subscheme of the nodes on @xmath333 so that its length is @xmath354 . for a given partition @xmath355 such that @xmath356 we partition @xmath353 into mutually disjoint union @xmath357 with @xmath358 and @xmath359 @xmath360 . in @xmath361 we consider configurations where a multiplicity @xmath346 point collides with each node of @xmath362 for each @xmath363 . then @xmath332}_{g,\delta}$ ] differs from @xmath361 in that at each node of @xmath362 a multiplicity @xmath346 point is replaced by the punctual hilbert scheme of length @xmath346 . after some mental exercise , @xmath364}_{g,\delta})$ ] is then found to be @xmath365 { { \lvert\lambda\rvert}=d,\ \check \delta}_1\le \delta}}\ , \sum_{\mathcal{n}=\coprod_{\ell=1}^d \mathcal{n}_\ell^\lambda}\chi\left(\bigl(c_{g,\delta}\setminus{\textstyle \coprod}_{\ell=2}^d \mathcal{n}_\ell^\lambda\bigr)^{(\delta_1)}\right)\prod_{\ell=2}^d(\chi(h_\ell)-1)^{\delta_\ell}\,,\ ] ] where @xmath366 is the punctual hilbert scheme of length @xmath346 supported at a node . to proceed we have to calculate @xmath367 . according to ran @xcite , @xmath366 is a rational chain @xmath368 where @xmath369 are @xmath26 s and @xmath370 are nodes . therefore @xmath371 and we understand why the factor @xmath349 arises . next we easily see that @xmath372 finally , it should be noticed that there are @xmath373 ways to partition @xmath353 into @xmath374 . 3.2pt the above formula of @xmath364}_{g,\delta})$ ] is rather complicated and not that convenient in practice . actually there exists a neat formula for the generating function as we explain below . however , before going to that , it will be worthwhile ( and fun ! ) to look at several examples of this formula : @xmath375 \chi(c^{[2]}_{g,\delta})&=&\binom{3+\delta-2g}{2}&+&\delta&&\\ & & \yng(1,1 ) & & \yng(2)&&\\[2 mm ] \chi(c^{[3]}_{g,\delta})&=&\binom{4+\delta-2g}{3}&+&\delta(1+\delta-2g)&+&2\delta\\ & & \yng(1,1,1 ) & & \yng(2,1)&&\yng(3 ) \end{array}\ ] ] these agree with the sample computations of @xcite . we can give further examples : @xmath376}_{g,\delta } ) & = & \binom{5+\delta-2g}{4 } & + & \delta\binom{2+\delta-2g}{2 } & + & \binom{\delta}{2}\\[1 mm ] & & \yng(1,1,1,1 ) & & \yng(2,1,1)&&\yng(2,2)\\[2 mm ] & + & 2\delta(1+\delta-2 g ) & + & 3\delta&&\\ & & \yng(3,1 ) & & \yng(4 ) & & \end{array}\ ] ] @xmath377}_{g,\delta})&= & \binom{6+\delta-2g}{5 } & + & \delta\binom{3+\delta-2g}{3 } & + & \binom{\delta}{2}(\delta-2g)\\[1 mm ] & & \yng(1,1,1,1,1 ) & & \yng(2,1,1,1)&&\yng(2,2,1)\\[2 mm ] & + & 2\delta\binom{2+\delta-2g}{2 } & + & 2\delta(\delta-1 ) & + & 3\delta(1+\delta-2g)\\[1 mm ] & & \yng(3,1,1 ) & & \yng(3,2)&&\yng(4,1)\\[2 mm ] & + & 4\delta&&&&\\ & & \yng(5 ) & & & & \end{array}\ ] ] @xmath378}_{g,\delta})&= & \binom{7+\delta-2\,g}{6 } & + & \delta{4+\delta-2\,g\choose 4 } & + & { \delta\choose 2}{1+\delta-2\,g\choose 2 } \\[2 mm ] & & \yng(1,1,1,1,1,1 ) & & \yng(2,1,1,1,1)&&\yng(2,2,1,1)\\[3 mm ] & + & { \delta\choose 3 } & + & 2\,\delta{3+\delta-2\,g\choose 3 } & + & 2\,\delta \left ( \delta-1 \right ) \left ( \delta-2\,g \right ) \\[1 mm ] & & \yng(2,2,2 ) & & \yng(3,1,1,1)&&\yng(3,2,1)\\[3 mm ] & + & 2 ^ 2\binom{\delta}{2 } & + & 3\,\delta{2+\delta-2\,g\choose 2 } & + & 3\,\delta \left ( \delta-1 \right)\\[1 mm ] & & \yng(3,3 ) & & \yng(4,1,1)&&\yng(4,2)\\[3 mm ] & + & 4\,\delta \left ( 1+\delta-2\,g \right ) & + & 5\,\delta & & \\ & & \yng(5,1 ) & & \yng(6)&&\\[2 mm ] \end{array}\ ] ] let us now turn to the generating function : [ nodalmacdonald ] @xmath379}_{g,\delta})y^{\pm(d+1-g)}=\iota_\pm\ , ( y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{2g-2}\left(1 + ( y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{-2}\right)^\delta\,.\ ] ] by eliminating the sum over @xmath380 in one obtains that @xmath381}_{g,\delta})= & \sum_{\substack{\delta_2\ge 0,\dots,\delta_d\ge 0\\[2pt ] \sum_{\ell \ge 2 } \ell \delta_\ell \le d\\ \sum_{\ell \ge 2 } \delta_\ell\le \delta } } \binom{\delta}{\sum_{\ell \ge 2 } \delta_\ell}\binom{\sum_{\ell \ge 2 } \delta_\ell}{\delta_2,\dots,\delta_d}\left(\prod_{\ell=2}^d(\ell-1)^{\delta_\ell}\right ) \\ & \qquad\quad\quad \times\binom{d-\sum_{\ell \ge 2 } \ell \delta_\ell+1+\delta- \sum_{\ell \ge 2 } \delta_\ell-2g}{d-\sum_{\ell \ge 2 } \ell \delta_\ell } \ , . \end{split}\ ] ] then consideration of the generating function leads to @xmath382}_{g,\delta})y^d&= \sum_{k=0}^\delta\,\,\sum_{\substack{\delta_2\ge 0,\delta_3\ge 0,\dots\\[2pt ] k= \sum_{\ell \ge 2 } \delta_\ell}}\binom{\delta}{k}\binom{k}{\delta_2,\delta_3,\dots}\\ & \quad\times\left(\prod_{\ell\ge 2}(\ell-1)^{\delta_\ell}\right ) y^{\sum_{\ell \ge 2 } \ell \delta_\ell}(1-y)^{2g-\delta+k-2}\ , , \end{split}\ ] ] where we understand the sequence @xmath383 contains only finitely many non - zero terms . the right hand side can be rewritten as @xmath384 k= \sum_{\ell \ge 2 } \delta_\ell } } \binom{k}{\delta_2,\delta_3,\dots } \prod_{\ell\ge 2}\left\{(\ell-1)y^\ell(1-y)\right\}^{\delta_\ell}\ , . \end{split}\ ] ] the multinomial theorem simplifies this as @xmath385 by summing up the geometric series one obtains @xmath386 by the binomial theorem this is equal to @xmath387 it thus follows that @xmath388}_{g,\delta})y^d=(1-y)^{2g-2}\left(1+\frac{y}{(1-y)^2}\right)^\delta\,.\ ] ] to see that this leads to is easy . let @xmath389 be the generalized jacobian of @xmath333 and @xmath390 its compactification . [ cjformulaprop ] @xmath391 this is ( with a correction of sign ) implicit in @xcite . ( see the discussion around eq . ( 5.8 ) of @xcite . ) we have an exact sequence of commutative algebraic groups can be obtained from one on @xmath392 by gluing the fibers over those points on @xmath392 which are identified to form nodes on @xmath333 . for each node the ways to glue two lines are parametrized by @xmath393 . ] @xmath394 hence @xmath390 is the product of @xmath395 and the compactification of @xmath396 . the latter is given by @xmath397 where @xmath398 is a certain equivalence relation essentially identifying @xmath399 and @xmath400 of each @xmath26 and @xmath401 is a rational curve with a single node . see iiib , 5 in @xcite for an exposition . since @xmath401 is obtained by pinching a homologically non - trivial 1-cycle from an elliptic curve , we obtain @xmath402 combining this with @xmath403 we easily obtain . the following may be viewed as an extension of . [ nodalcl ] @xmath404}_{g,\delta})y^{\pm(d+1-g)}=\iota_\pm\ , \frac{(-1)^g\operatorname{tr}_{h^*(\overline{j(c_{g,\delta})})}(-1)^hy^h } { ( y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{2}}\,.\ ] ] an immediate consequence of proposition [ nodalmacdonald ] and proposition [ cjformulaprop ] . we now investigate how the fibration structure of @xmath121 is directly reflected to properties of @xmath153 . we start by severi varieties were originally studied by severi ( and corrected by harris ) for curves of fixed degrees in @xmath290 . there are numerous works on severi varieties of other surfaces . see for instance @xcite . here we are extending the definition for calabi - yau threefolds assuming an appropriate family of curves @xmath121 . for attempts in defining severi varieties of threefolds see @xcite and references therein . one of the principal issues in the studies of severi varieties is whether or not they are regular . the standard way to investigate this is to resort to a deformation theory . there are many works for surfaces and these show that in most cases severi varieties of surfaces are regular but a care is needed when they are of general type . see again @xcite . if @xmath408 is regular , the @xmath334 nodes can be independently smoothed and @xmath409 . below we assume the regularity of @xmath408 for simplicity so that @xmath410 is meaningful . @xmath412}_\beta)y^{\pm(d+1-g(\beta))}\\ & \ \ = \iota_\pm \sum_{\delta=0}^{g(\beta)}\chi(v_{\beta,\delta})\ , ( y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{2g(\beta)-2}\left(1+(y^{{\frac{1}{2}}}-y^{-{\frac{1}{2}}})^{-2}\right)^\delta\ , . \end{split}\ ] ] by our assumptions , we see ( as in @xcite ) @xmath413}_\beta)y^{\pm(d+1-g(\beta))}=\sum_{\delta=0}^{g(\beta)}\chi(v_{\beta,\delta})\ , \sum_{d=0}^\infty\chi(c^{[d]}_{g(\beta),\delta})y^{\pm(d+1-g(\beta))}\,,\ ] ] to prove it suffices to binomially expand @xmath418 on the right hand side of and then notice @xmath419 the inversion relation that leads to is well - known . the last equality in is due to a yau - zaslow type argument @xcite . the way gopakumar and vafa introduced @xmath234 was representation theoretic and was driven by the motivation of finding a convenient expansion basis as in . however , to the best of my understanding , the direct geometrical characterization of @xmath234 has not yet been available . the relation seems to give an intuitive feeling about the geometrical meaning of @xmath420 . in general , one can produce a node on a curve by pinching a handle or gluing two points . conversely given a @xmath334-nodal curve of arithmetic genus @xmath108 one can make a smooth curve of genus @xmath421 , where @xmath422 , by ungluing ( or partially normalizing ) @xmath423 nodes and unpinching @xmath424 nodes . of course there are @xmath425 ways to choose such @xmath423 nodes from the entire nodes of the curve . if @xmath426 for all @xmath427 then @xmath428 . this was the claim in @xcite . however , such an assumption depends on @xmath423 and can not be satisfied for all @xmath423 simultaneously unless everything is empty . in general the relation between @xmath234 and @xmath410 has to be as above . to summarize , in our extremely ideal situation we can declare any of @xmath429})\}_{d=0}^{g(\beta)}\ , , \quad \{n_\beta^h\}_{h=0}^{g(\beta)}\ , , \quad \ { \chi(v_{\beta,\delta})\}_{\delta=0}^{g(\beta)}\,,\ ] ] as a _ fundamental set of invariants_. they can be converted from one to another .

we discuss how the geometry of @xmath0-@xmath1 branes may be related to gromov - witten theory of calabi - yau threefolds .

according to accepted cosmological theory , the early universe went through a period of inflation where it s size increased by at least 60 e - folds in a small fraction of a second @xcite . there is a wealth of observational data providing evidence that inflation occurred @xcite . in addition , inflation is needed to satisfy several fundamental problems in cosmology such as the flatness and horizon problems . unfortunately , most theories of inflation involve the existence of a scalar field and are difficult to distinguish by observation or experiment . also , there are still many unanswered questions about where the scalar field came from or why it disappeared after inflation ended . recently , alexander et al . @xcite suggested a new theory of cosmic inflation based on chern - simons modified gravity @xcite unlike scalar field theories of inflation , the theory proposed by alexander et al . utilizes the interaction between a gauge field and fermion current to drive inflation and does not depend on the existence of a scalar field . this is not the only theory of inflation derived from a vector field interaction @xcite but it is unique in that it involves elements that are known to exist in practice and not just in theory . the chern - simons inflation theory works by suggesting that the energy density from the interaction between the gauge field and fermion current behaves like vacuum energy . this is possible in chern - simons modified gravity . the gauge field starts with a random white noise spectrum but then the energy is transported to a few low frequency modes . in the early version of the paper by alexander et al , the spatial parts of the gauge field and fermion current where used to derive the energy density . they later changed that and based the energy density on the temporal parts of the gauge field and fermion current . this author believes that the motivation for this change may have been the belief that the spatial part of the fermion current dropped to zero too quickly to be effective in driving inflation . we find this to not be the case . we also find that the temporal part of the gauge field and fermion current may not be sufficient to drive a 60 e - fold increase in scale factor . our code utilizes the adler - bell - jackiw ( abj ) chiral anomaly @xcite to model the decrease in fermion current associated with changes in the scale factor and gauge field . this is a small quantum mechanical violation of the conservation of axial - vector current . this violation occurs due to tunneling of fermions from one vacuum to another and is partially responsible for the gentle ending of the inflation event . it is the means by which the gauge field converts to leptons during inflation resulting in lepto - genesis . as the current decreases during inflation , the negative pressure driving inflation should decrease as well unless the decrease in current is offset by an increase in the gauge field . the overall goal of the study presented here is to understand the dynamics of the system and strengthen our physical interpretation of the theory presented here . the author s previous paper on the numerical simulation of chern - simons inflation @xcite served to prove the feasibility of the theory . additional work is being planned to more thoroughly study the version of the theory involving the temporal part of the gauge field and fermion current both alone and in conjunction with the spatial part . in the following sections , we will describe in more detail what we believe is the most promising model of chern - simons inflation as well as the results of computer simulations of this model . in the final section , we will discuss these results and how they may be used in future research . the code utilized in these simulations is based on the cactus framework @xcite used for numerical relativity research . while cactus is an extremely sophisticated code containing millions of lines of code , all the physics is contained in code written by the author . this code has been thoroughly tested and the results are self - consistent and reliable . the inflation model developed by alexander , marciano and spergel utilizes a gauge field which interacts with fermions in the early universe to produce an effective scalar field that generates inflation @xcite . see the recent article by garrison and underwood for a complete description of how the numerical equations for this model are derived @xcite . for the numerical calculation , we use natural units but later evaluate the data in terms of si units so that the results can be easily compared to the established values . in order to use this model in our code , we separated the equations of motion for the gauge field , abj chiral anomaly , chern - simons term and the friedman equations into a system of first order in time differential equations . @xmath0 here the gauge field is represented with @xmath1 , the current is @xmath2 , a is the scale factor and h is the hubble parameter . current is assumed to depend simply on the charge density according to the equation @xmath3 . @xmath4 represents the hyper charged electric field , @xmath5 . @xmath6 is the hyper charged magnetic field , @xmath7 term . @xmath8 is the mass scale identified with the uv cut - off scale of the effective field theory and @xmath9 is responsible for cp violation . @xmath10 is on the order of the gut energy scale . finally , the average energy density is calculated as @xmath11 . here n represents the total number of grid points in the computational domain . the scale factor and hubble parameter therefore depend on the average energy density and not the local field dynamics . the initial gauge field was composed of a random ( white noise ) spectrum . in order to generate the initial gauge field , we used a random number generator to create a random spectrum with amplitude up to the calculated maximum amplitude , @xmath12 , in each direction . the magnitude of the gauge field was then held equal to the initial amplitude @xmath12 . the initial values for the variables used in this study are given below . @xmath13 the code was then run on the university of houston@xmath14s maxwell cluster using a variety of time - steps , grid sizes and resolutions in order to obtain consistent results . a fourth order finite differencing scheme was used to test convergence for high and low resolution simulations . because the initial units were entered as planck units , we assumed that the physical grid ( horizon ) size corresponded to planck lengths and the timing output could be interpreted as planck time . the previous article by garrison and underwood @xcite focused on demonstrating the feasibility of the model and verifying that the apparent inverse energy cascade occurred as predicted . previous data have shown that this is an interesting chaotic system which is highly dependent on initial conditions but numerically stable for a large range of initial data . as in the previous paper , figure 1 shows the life - cycle of the evolution as our virtual universe experiences inflation . this is demonstrated by the scale factor and hubble parameter . , width=456,height=240 ] figure 2 shows how the gauge field increases and charge density decreases with time . the net result of this is that the dot product of the gauge field and charge density yields a nearly constant energy density ( and therefore hubble parameter ) until inflation ends . the gauge field evolution equation is essentially an inhomogenous wave equation driven by the @xmath15 term and the @xmath16 term . understanding how inflation occurs is directly connected to the dynamics of these two terms . charge density falls off as roughly @xmath17 making the second term simply increase proportional to the scale factor and therefore lack the dynamics needed to significantly effect the gauge field evolution . the first term however is much more dynamic and could explain why inflation begins and ends . also , given our initial conditions , the first term is @xmath18 while the second term is @xmath19 so the first term should normally dominate since @xmath6 starts around @xmath20 and increases as quickly as the gauge field . , width=456,height=240 ] without the @xmath9 term chern simons modified gravity reduces to ordinary general relativity and the effective vacuum energy disappears . much of the gauge field dynamics is therefore the result of the @xmath9 term and it s time derivatives . the phase diagram in figure 3 shows that this term acts like a dampened driven harmonic oscillator . the frequency of this system is @xmath21 the dampening term is @xmath22 and the driving term is f = @xmath23 . given our initial conditions , @xmath24 , @xmath25 and f is insignificant because @xmath26 is unmeasurably small . this is therefore an under - damped harmonic oscillator that transitions into an over - damped harmonic oscillator as the hubble parameter increases . the @xmath9 term vanishes quickly after @xmath27 exceeds @xmath28 and the gauge field s rate of growth slows while current continues to decrease at a constant rate resulting in a decreasing energy density and an end to inflation . maintaining the chern simons term , @xmath29 , for as long as possible appears to be essential to the inflation process . and @xmath29 terms.[fig : theta],width=456,height=240 ] in figure 4 , we see the spectrum of the gauge field as a function of time . notice that the initial gauge field starts off with an evenly distributed spectrum and then sometime later the spectrum peaks at low frequencies to resemble an inverse energy cascade . later the peak of the power spectrum moves to higher frequencies as the chern simons term decays . the peak follows the changing frequency of the chern simons term to maintain resonance until it decays to zero and inflation ends . , width=456,height=336 ] an important result of this study is that we now know why inflation only appears to occur when the computational grid is sufficiently large . our analysis of the @xmath9 term s dynamics show that it s natural oscillatory frequency is on the order of @xmath30 . this corresponds to a grid size of about @xmath31 units . if the computational grid is smaller than this minimum , the gauge field can not come into resonance with the driver @xmath9 and explode in amplitude . information from this study may also be useful in better determining what initial conditions led to inflation in our universe . by varying the initial conditions , the forcing term , dampening term and frequency of @xmath9 may be altered to extend our simulated inflation and better conform to observation . a. r. ade _ et al . _ [ bicep2 collaboration ] . bicep2 i : detection of b - mode polarization at degree angular scales . arxiv:1403.3985 [ astro-ph.co ] , 2014 . s. adler . axial - vector vertex in spinor electrodynamics . _ physical review _ , 177 , 1969 . s. alexander , a. marciano , and d. spergel . chern - simons inflation and ba , ryogenesis . _ journal of cosmology and astroparticle physics _ , 2013 , 2013 s. alexander and n. yunes . chern - simons modified general relativity . _ physics reports _ , 480,1 - 2:155 , 2009 . j. s. bell and r. a. jackiw . pcac puzzle : @xmath32 in the @xmath33-model . em il nuovo cimento , 60a,4 , 1969 . l. h. ford . inflation driven by a vector field . _ physical review d _ , 40,4:967972 , 1989 . d. garrison and c. underwood . a numerical simulation of chern - simons inflation . _ advances in astronomy _ , 2013 : 207218 , 2013 . t. goodale , g. allen , g. lanfermann , j. mass , t. radke , e. seidel and j. shalf . the cactus framework and toolkit : design and applications , vector and parallel processing vecpar 2002 , 5th international converence , lecture notes in computer science , berlin : springer , 2003 . < http://edoc.mpg.de/3341 > a. h. guth . inflationary universe : a possible solution to the horizon and flatness problems . _ physical review d _ , 23,2:347356 , 1981

in this paper , we study the dynamics of the chern - simons inflation model proposed by alexander , marciano and spergel . according to this model , inflation begins when a fermion current interacts with a turbulent gauge field in a space larger than some critical size . this mechanism appears to work by driving energy from the initial random spectrum into a narrow band of frequencies , similar to the inverse energy cascade seen in mhd turbulence . in this work we focus on the dynamics of the interaction using phase diagrams and a thorough analysis of the evolution equations . we show that in this model inflation is caused by an over - damped harmonic oscillator driving waves in the gauge field at their resonance frequency .

Because for some lucky souls, the place where the sidewalk ends just happens to be the Playboy Mansion. Part of a weeklong series on poems and poets, sounds and sense. Video by Melanie Ruiz. One of the many unexpected pleasures of the internet is Hugh Hefner’s Instagram page, where you’ll find scores of old — mostly PG-rated — photos from Hef’s personal collection, brought to life in gentle Kodachrome color (and you thought your Facebook friends’ photos made you jealous!). And among the pools, pinball, parrots and tug-of-war games with scantily clad models, you’ll spot celebrities, from Chevy Chase to James Caan to the now rather regrettable presence of Bill Cosby. But you’ll also catch sight of another distinct figure playing croquet shirtless, a bald man with a beard you have known since your childhood — but never really known. Just what, exactly, you may wonder, is Shel Silverstein, author of The Giving Tree, Where the Sidewalk Ends and other children’s classics, doing in a highlight reel of the Playboy Mansion’s most iconic scenes? Quite a bit, it turns out, and much of it, shall we say, was not particularly suitable for the children’s hour. Silverstein might spend weeks or months at a time at Hef’s infamous party pad. Like the Giving Tree itself, Silverstein had a lot to offer — from cartoons to poems to songs to plays — and when he died of heart failure at age 68 in 1999, he had given his adoring fans everything up to his stump. Born in 1930 to a middle-class Jewish family in Chicago, young Sheldon was a poor student who hated conformity. After being kicked out of one college, dropping out of another and being drafted to serve in the Korean War, his prospects looked rather dim. “I didn’t get laid much. I didn’t learn much,” Silverstein later summed up his college days. “Those are the two worst things that can happen to a guy.” So with the war behind him, Silverstein set about making up for lost time, and stimulating both his mind and body. He worked as a freelance cartoonist for a few years until 1956, when he got his big break — a job on staff at fellow Chicagoan Hugh Hefner’s young Playboy magazine. As Lisa Rogak details in A Boy Named Shel: The Life and Times of Shel Silverstein, he traveled the world as Playboy’s cartoon-drawing foreign correspondent, and his travelogue soon became the magazine’s second most popular feature, after the centerfold, of course. And the great adventure did not end once Silverstein returned to Chicago. “For the first time in his life, women began to look his way, to flock to him,” writes Rogak. “They wanted him. Badly.” As Rik Elswit, a member of Dr. Hook, a rock band Silverstein used to write for and hang with, explained the cartoonist’s sex appeal: “Shel was not handsome. … Maybe it was his eyes; they would twinkle and pierce simultaneously, giving you the impression that he knew something you didn’t.” Fellow Playboy cartoonist Skip Williamson likewise tells Rogak that Silverstein “knew his way around a skirt,” recalling how he and the children’s author used to walk down the street, telling the beautiful women they encountered that they worked for Playboy and asking if they would like to be a Playmate. If any of their targets expressed interest, Silverstein would pull out a measuring tape to record her dimensions. It wasn’t a bad life, but it could only get better when Hefner bought his first Playboy Mansion in Chicago in 1959 (the current Playboy Mansion West in Los Angeles did not open until 1971). “Being at the mansion in the middle of the night was like putting your finger in an electric socket,” Larry Dubois, a writer for Playboy, once said. “It was really alive. And Shel loved it.” And what wasn’t to love? Hefner made his mansion a most enchanting place to visit, equipped with half-naked women, top-shelf entertainment and celebrities, swimming pools, party games, you name it. As part of Hef’s inner circle and one of its court jesters, Silverstein might spend weeks or months at a time at the infamous party pad, where he tended to lurk in the background and let others come to him. Silverstein had no patience for bores, whether they were movie stars or 34Ds, but he fed creatively off the many interesting people and encounters he had in the Playboy world — and he wrote many of his children’s works while inside it. As playwright David Mamet told The New York Times after Silverstein’s death: “He was Hugh Hefner’s sidekick, he was the great cartoonist, he lived with Hef at the Playboy Mansion, in a riot of delight.” Silverstein had two kids and would never marry, but that riot of delight permeates all of his art, including his poems for children. Just try to read his classic “Hug O’ War,” from Where the Sidewalk Ends, without summoning those sun-drenched scenes of yore in Hefner’s pleasure garden. I will not play at tug o’ war. I’d rather play at hug o’ war, Where everyone hugs Instead of tugs, Where everyone giggles And rolls on the rug, Where everyone kisses, And everyone grins, And everyone cuddles, And everyone wins. ||||| A few weeks ago, rummaging around the Strand, I came across a fiftieth-anniversary edition of Shel Silverstein’s “The Giving Tree.” It had the fern-green cover familiar from childhood, the same oversized dimensions, the same appealing sketch on its front—a squiggly drawing of a tall tree, its top spilling off the page, and a little boy, looking up at it. But instead of experiencing a pleasant rush of nostalgia, I was dismayed. A strange thing happens when we encounter a book we used to love and suddenly find it charmless; the feeling is one of puzzled dissociation. Was it really me who once cherished this book? The beginning of the story is innocuous enough: a boy climbs a tree, swings from her branches, and devours her apples (I’d never noticed that the tree was a “she”). “And the tree was happy,” goes the refrain. But then time passes, and the boy forgets about her. One day, the boy, now a young man, returns, asking for money. Not having any to offer him, the tree is “happy” to give him her apples to sell. She is likewise “happy” to give him her branches, and later her trunk, until there is nothing left of her but an old stump, which the old man, or boy, proceeds to sit on. A little Googling corroborated my own distaste. “The Giving Tree” ranks high on both “favorite” and “least favorite” lists of children’s books, and is the subject of many online invectives. One blog post, “Why I Hate The Giving Tree by Shel Silverstein,” argues that the book encourages selfishness, narcissism, and codependency. Unsurprisingly, perhaps, environmental activists rue the boy’s pillaging of the tree and, by extension, the environment. William Cole, who turned down the manuscript when he was an editor at Simon & Schuster (Silverstein took it to Harper & Row), was troubled by its portrayal of parenthood: “My interpretation is that that was one dum-dum of a tree, giving everything and expecting nothing in return.” More recently, the children’s-book author Laurel Snyder said, “When you give a new mother ten copies of ‘The Giving Tree,’ it does send a message to the mother that we are supposed to be this person.” Still, it’s difficult to know whether Silverstein, who died of a heart attack in 1999, after keeping out of the public eye for more than two decades, meant for us to read the book so conclusively. His biography and body of work suggest a subtler, and, in the end, perhaps an even more troubling, way of looking at it. *** Silverstein detested stories with happy endings. As he once put it, “The child asks, ‘Why don’t I have this happiness thing you’re telling me about?’” His own up-by-the-bootstraps childhood was marked by insecurity and self-doubt. Born in 1930 on the northwest side of Chicago, Sheldon Allan Silverstein grew up in a second-story apartment crammed with relatives. His parents, an immigrant father from Eastern Europe and a Chicago-born mother, opened an unsuccessful bakery on the heels of the Great Depression. Though Silverstein’s mother encouraged his early knack for drawing, his father made it clear that he was expected to join the flailing family business. But Silverstein couldn’t sit still. He was a distracted student, who may have also suffered from dyslexia (at fifteen, he misspelled his middle name on his Social Security application). As Lisa Rogak writes in “A Boy Named Shel,” an engaging 2011 biography of the man, “His attention span ran from nil to nonexistent.” Silverstein discovered his passion for drawing early, and it became his refuge from his increasingly wrathful father. After a few unsuccessful attempts at college—he never graduated, explaining, “I didn’t get laid much and I didn’t learn much. Those are the two worst things that can happen to a guy”—Silverstein’s listlessness and love of cartoons found an unexpected outlet in the military, which he joined in 1953, serving on the newspaper of a troopship in Japan. His break came three years later when, discharged and unemployed, he visited the offices of a fledgling magazine for men and met its editor, himself an avid cartoonist: Hugh Hefner. So began Silverstein’s long association with Playboy, where he published not only cartoons and illustrations but also ongoing travelogues from such places as Tokyo, Paris, and Moscow, and became a regular fixture at the seedily infamous Playboy Mansion. By Rogak’s count, he bedded hundreds, if not thousands, of women. He was raggedly attractive (though not particularly handsome): his beard full, his brows furrowed, his half smile gap-toothed, his hair long (later he was completely bald). He liked to wear pirate shirts and a pair of shiny corduroys that, according to a female friend, “made him look like a filing cabinet.” During those Playboy years, Silverstein shuttled back and forth between Chicago and downtown New York; he frequented folk clubs and began making his own music—scribbling away songs on the back of cocktail napkins and tablecloths, performing folk and jazz numbers in a low, gravelly voice. He was wildly prolific and prolifically wild. On a visit to Denmark, Silverstein signed on as the vocalist of a group called Papa Bue’s Bearded Viking New Orleans Danish Jazz Band. He was the mastermind behind Johnny Cash’s Grammy-winning song “A Boy Named Sue.” He palled around with Norman Mailer and Dustin Hoffman, and reportedly advised a young Bob Dylan on lyrics for what turned out to be “Blood on the Tracks.” “He was our own personal beatnik,” his friend, the actress Lois Nettleton, tells Rogak. Silverstein himself once remarked of his itinerant lifestyle, “Comfortable shoes and the freedom to leave are the two most important things in life.” As becomes clear from reading Rogak’s biography, Silverstein never intended to write or draw for children. He was often impatient around kids and, Rogak claims, “made no secret of the contempt he felt” for most children’s books. “Hell, a kid’s already scared of being small and insignificant,” he once said. “So what does E. B. White give them? A mouse who’s afraid of being flushed down the toilet or rolled up in a window shade and a spider who’s getting ready to die.” But writing kids’ books was the complete opposite of the work he was doing for Playboy and, maybe for that reason, and with the prodding of a savvy editor, he decided to try his hand at it. The result was a classic Silversteinian burst of productivity: in 1964 alone, he published three children’s books and one book for adults. Among them was “The Giving Tree,” whose breakaway success caught by surprise not only his publishers, who had printed a modest run of seven thousand copies, but also Silverstein himself, who claimed it had no message. Sales of “The Giving Tree” doubled every year in the decade following its publication; they have since topped five million copies worldwide. But Silverstein was continually asked to defend the book, and this seems to have sapped his energy. “It’s just a relationship between two people; one gives and the other takes,” he would often repeat. It would take him another decade to complete his next children’s book, the fiercely imagined poetry collection “Where the Sidewalk Ends,” and, by 1975, he had almost entirely stopped talking to the press. (Silverstein never married and never wanted to have kids. But circumstances changed the year he turned forty, when one of his former Mansion “playmates” gave birth to a daughter; in 1982, the girl, Shoshanna, died of a brain aneurysm at age eleven, a tragedy from which Silverstein is said to have never recovered. Two years later, a son, Matthew, was born.) “Where the Sidewalk Ends” was banned from many libraries across the country for years after its publication: it was said to promote such diverse ills as drug use, suicide, death, the occult, violence, disrespect for authority, disrespect for truth, and rebellion against parents. It also happened to be a book that perfectly encapsulated the idiosyncratic concerns of childhood. One poem, called “Eighteen Flavors,” is about a person who “labels all the flavors on their ice cream cone before accidentally dropping them all.” Another is about an acrobat hanging from a trapeze who asks for “just one thing, please / As we float through the breeze — Don’t sneeze.” The book easily and sensitively inhabited a child’s perspective. A moralistic reading of “The Giving Tree” is challenged again and again by Silverstein’s other writing for children, as he consistently ended his books on a note of ambiguity. Consider “The Missing Piece,” another Silverstein classic. Published in 1976, “The Missing Piece” tells the story of a circle that’s missing a wedge. The circle goes in search of this lost piece and, after some tribulations, finds it. The story could have easily ended there—the circle made whole!—but it doesn’t. Instead, the newly spiffy circle begins to roll too fast, and its view of the world becomes blurred. “That’s the madness of the book,” Silverstein said, “the disturbing part of it.” If madness is what he was after, then the “The Giving Tree” might be read as another expression of it, perhaps a cousin to a song Silverstein wrote, called “Fuck ’Em,” in which he cheerfully exclaims, “Hey, a woman come around and handed me a line / About a lot of little orphan kids sufferin’ and dyin’ / Shit, I give her a quarter, cause one of ’em might be mine.” Rogak, his biographer, has her own explanation for “The Giving Tree” ’s portrayal of self-abnegation—one that echoes his beatnik years: “Given his disgust with the me-first attitude among the folksingers and other artists in the Village who were creating art as a form of self-analysis, it almost sounds like he wrote it as an experiment, a reaction to their own mushiness.” The dismay I felt on rereading the book soon gave way to something else. Finding that a childhood favorite wasn’t at all what I remembered carried with it a peculiar thrill, a kind of scientific proof that I’d grown up and changed. And, if I’ve changed, perhaps “The Giving Tree” has, too. What, for example, does Silverstein mean with his injection of the flat, repetitive “happy”? He wasn’t one for happiness. In fact, the book’s illustrations seem to undermine this very conceit. “And the tree was happy,” we are told, but all we see is a sorry stump and a hunched old man staring forlornly into the distance. Is she happy? We have to ask. Is he? Or maybe the book isn’t about love or happiness at all, but a lament about the passing of time, an unsentimental view of physical decay, a withering away. Maybe it’s enough to take Silverstein’s own reading of it. “It’s about a boy and a tree,” he once said. “It has a pretty sad ending.” ||||| More than a decade after his death of a heart attack at age 68, Shel Silverstein's career avoids any defining label. Millions of children have anointed him to beloved status thanks to poetry books like Where The Sidewalk Ends and A Light in the Attic, and a visit to the website run in tandem by Shel's estate and his longtime publisher, HarperCollins, might convince you that his work for kids is his primary legacy. Doing so, however, neglects the full spectrum of what made Silverstein tick as an artist. It rubs out the more than 40 years he spent in the bosom of Hugh Hefner's Playboy empire, a veritable court jester at Mansion gatherings when not traveling the world as the magazine's cartoon-capturing foreign correspondent (see Shel Silverstein Around the World, a coffee table-style compendium of reports from places like Moscow, Spain, and Fire Island) or producing epic poems like "The Perfect High" or "Hamlet As Told on the Street". Sticking only to the school-age side of the road means ignoring his prodigious work as a songwriter (Johnny Cash's "A Boy Named Sue"? Dr. Hook and the Medicine Show's "The Cover of the Rolling Stone"? The Irish Rovers' "Unicorn"? The Oscar-nominated "I'm Checking Out" from Postcards From the Edge? All penned by Shel), his one-act plays for Off-Off Broadway venues (which attracted the attention, and later friendship, of David Mamet) and a tentative foray into crime fiction that, if not for his premature passing, might have blossomed into something greater. But the most remarkable element of his non-children's-lit career was Silverstein's nine albums worth of songs he recorded—and especially the album's worth of unreleased material that might even surprise fans of Shel's adult side. As a recording artist, Silverstein brought a raspy vocal style (not unlike Tom Waits's satanic older cousin) that came from his teenage years as a Comiskey Park hot dog vendor. And his firsthand knowledge of various scenes (Greenwich Village Beats, the Chicago folk music world, Nashville's Music Row) led to a varying array of song styles and production values. By the late 1960s, this songwriting acumen helped Silverstein move into rock circles, thanks in large part to the New Jersey-based Dr. Hook & The Medicine Show. Dr. Hook also backed Shel on his most commercially successful album, Freakin' At the Freakers Ball. "Commercially successful" is a relative term for a group of raucous and risque songs like Masochistic Baby." Shel sweetly intones that ever since his baby left him, "I've got nothing to hit but the wall." Dr. Hook gave it as much oomph as its own, Rolling Stone-cover-worthy album Sloppy Seconds, adding a sense of gleeful disconnect to the whole musical affair. The album cracked Billboard's Top 200 and recording label CBS provided a marketing budget, something beyond Shel's resources at the time. The one-sheet ad featured Shel, clad in a jean jacket, patterned shirt and cowboy boats, and what can only be described as a piratical beard, trumpeted as some sort of heir apparent to Gilbert O'Sullivan (!) But Freakers Ball was likely the compromise point on a series of songs Shel recorded a couple of years before the final album was released, songs with eye-popping titles like "Fuck 'Em", "I Am Not a Fag" and "I Love My Right Hand.". Some of these songsare available on YouTube. Others may wish to seek the bootleg. The titular track, so to speak, is astonishing. It starts out like a dirge, with Shel intoning that he's "all strung out, his money spent/couldn't even tell you where last year went/But I've given up payin' my bills for lent/and now the landlord, he wants his rent..." a litany of staggering and despairing proportions that demands only one answer: "Fuck 'Em." What follows is a playful series of shrieking, baleful grouses and complaints until Shel is at death's door, doing an uncanny imitation of a tubercular cough, waiting to become "the Devil's favorite pet." Then a strumming coda erupts, dissipating into a knowing chuckle and "how's that" to the obviously amused producer behind the glass door. Listening now, "Fuck 'Em" is all too apt for today's turbulent economic times, when it would be great to dismiss mere trifles like bills and rent and relationships knowing full well it isn't so simple. A good two decades before the Divinyls teased a mass audience with "I Touch Myself", Silverstein mined similar masturbatory territory in "I Love My Right Hand" with considerably more bluntness. Rhyming "Some men prefer adolescents" with "sexual acquiescence" is rather ballsy, not to mention off the beaten phrase track. That said, considering the song peters off into patter after about two minutes - admittedly, deliberate, amusing patter about threatening to amputate the right hand for daring to stray with other limbs and objects—it does feel like a warmup for the similarly bawdy "Get My Rocks Off" performed with deadpan aplomb by Dr. Hook's basso profundo George Cummings (and later covered by Marilyn Manson, perhaps the last person one would associate with Silverstein) and the biggest laugh of "Everybody's Makin' It Big But Me", when nerdy Rik Elswit sings "they got groupies for their bands/all I've got is my right hand."

– Shel Silverstein was kicked out of one college and dropped out of another, and he described those days gloomily: "I didn't get laid much. I didn't learn much. Those are the two worst things that can happen to a guy." His trouble with the ladies didn't persist. Ozy recalls what for many is a less-known side of the famed cartoonist's life: that of, in the words of David Mamet, "Hugh Hefner's sidekick." After scraping by as a freelance cartoonist for a few years, Silverstein got his first real job under the wings of Hefner, traveling the world as Playboy's foreign correspondent cartoonist. And women soon flocked to him, reports Ozy. "Shel was not handsome," one friend said. "Maybe it was his eyes; they would twinkle and pierce simultaneously, giving you the impression that he knew something you didn't." By the time the first Playboy Mansion was built in 1959, Silverstein was in the inner circle, known to spend weeks and even months partying within its confines. Lisa Rogak, author of the 2011 biography A Boy Named Shel, believes he slept with hundreds—perhaps thousands—of women, per a 2014 New Yorker article. His first child, Shoshanna, was born to a Playboy Bunny, reports the Atlantic; the girl died at age 11 from a brain aneurysm, a loss Silverstein reportedly never got over. He also had a son. The Atlantic points out Silverstein was also a songwriter and penned "A Boy Named Sue," made famous by Johnny Cash. Though Silverstein released nine albums, he also recorded some "eye-popping" songs that weren't formally released, with titles like "I Love My Right Hand" and "Get My Rocks Off"; the latter was covered by none other than Marilyn Manson. Read more on Silverstein's Playboy days here. (Playboy itself is changing in a fundamental way in March.)

widely separated time - scales occur in many radio - frequency ( rf ) circuits such as mixers , oscillators , plls , etc . , making the analysis with standard numerical methods difficult and costly . low frequency or baseband signals and high frequency carrier signals often occur in the same circuit , enforcing very small time - steps over a long time - period for the computation of the numerical solution . the occurrence of widely separated time - scales is also referred to as a multi - scale or multi - rate problem , where classical numerical techniques require prohibitively long run - times . a method to circumvent this bottleneck is to reformulate the ordinary circuit equations , which are differentieal algebraic equations ( daes ) , as a system of partial daes ( multi - rate pdae ) . the method was first presented in @xcite , specialized to compute steady states.the technique was adapted to the transient simulation of driven circuits with a - priori known frequencies in @xcite . a generalization for circuits with a - priori unknown or time - varying frequencies was developed in @xcite . this approach opened the door to multi - rate techniques with frequency modulated signal sources or autonomous circuits such as oscillators with a priori unknown fundamental frequency @xcite . here , we present a new approach for the computation of a not a - priori known , time - varying frequency , which is driven by the requirement to have a smooth multi - rate solution , crucial for the efficiency of the computation . we consider circuit equations in the charge / flux oriented modified nodal analysis ( mna ) formulation , which yields a mathematical model in the form of a system of differential - algebraic equations ( daes ) : @xmath0 here @xmath1 is the vector of node potentials and specific branch voltages and @xmath2 is the vector of charges and fluxes . the vector @xmath3 comprises static contributions , while @xmath4 contains the contributions of independent sources . to separate different time scales the problem is reformulated as a multi - rate pdae ( cf . @xcite ) , i.e. , @xmath5 if the new source term is chosen , such that @xmath6 where @xmath7 , then a solution @xmath8 of ( [ multirate ] ) determines a family @xmath9 of solutions for @xmath10 by @xmath11 although the formulation ( [ multirate ] ) is valid for any circuit , it offers a more efficient solution only for certain types of problems . this is the case if @xmath12 is periodic in @xmath13 and smooth with respect to @xmath14 . then , a semi - discretization with respect to @xmath14 can be done resulting in a relative small number of periodic boundary problems in @xmath13 for only a few discretization points @xmath15 . in the sequel we will consider ( [ multirate ] ) with periodicity conditions in @xmath13 , i.e. , @xmath16 and suitable initial conditions @xmath17 . here @xmath18 is an arbitrary but fixed period length , which results in a scaling of @xmath12 and @xmath19 as we will see in the next section . note that for a given initial value for the original circuit equations ( [ eq_mna_charge ] ) the multi - rate formulation ( [ multirate ] ) is not unique . first it does not correspond to a single problem , but to a family of problems as described in ( [ singlerate ] ) . this usually permits some freedom in the choice of the multi - rate source term @xmath20 and for the initial conditions . furthermore , @xmath19 can , in principle , be chosen arbitrarily , but influences on the other hand , which choice of @xmath20 satisfies ( [ char_source ] ) . in the sequel , we want to study how the above freedom can be used to facilitate an efficient numerical solution of ( [ multirate ] ) . the smoothness of @xmath12 is essential for the efficiency of classical solvers . that is , the freedom we have for the formulation of ( [ multirate ] ) should be used to make the solution as smooth as possible . it can be easily verified that @xmath19 can be any positive function , if the source term @xmath20 is chosen to satisfy ( [ char_source ] ) . therefore , we will first investigate , what effect different selections of @xmath19 have . let @xmath21 and @xmath22 be two choices . if @xmath23 and @xmath24 both satisfy ( [ character ] ) , then it is obvious that @xmath25 where @xmath26 . that is , for a fixed @xmath14 changing @xmath27 results in a phase shift of @xmath12 . a corresponding phase shift for the source term has to be performed in order to satisfy ( [ char_source ] ) . the following lemma describes how @xmath19 affects the smoothness of @xmath12 . [ smoothmr ] let @xmath28 for any @xmath29 . if @xmath30 for @xmath31 $ ] , then @xmath32 where @xmath33 is the unique solution of @xmath34 following ( [ character ] ) we have @xmath35 by the mean value theorem for integration we obtain @xmath36 thus , @xmath37 and ( [ smoothx ] ) follows from ( [ smoothxhat ] ) by ( [ character ] ) . lemma [ smoothmr ] states that we can only expect smoothness of @xmath12 in @xmath14 if @xmath38 is nearly @xmath33-periodic in a neighborhood of @xmath14 . since typical multi - rate signals behave locally like a periodic signal , i.e. , @xmath39 as long as @xmath13 is close to some @xmath40 that is , there should be a choice of @xmath19 such that @xmath41 and @xmath42 do not differ much for sufficiently small @xmath43 . this leads to the additional condition @xmath44 in order to determine @xmath19 . a similar condition is used in @xcite ) . the difference to our approach is in the discretization of the problem . while pulch derives a phase condition from the minimization condition , we will discretize the minimization condition directly , which will lead to a smaller linear system to be solved in the algorithm . furthermore , we are using a rothe method for the discretization of the pdae , which allows a completely adaptive solution . a different approach is suggested in @xcite , where @xmath12 is replaced by @xmath45 in ( [ min_cond ] ) . although this seems the proper condition for an efficient discretization of the derivative in @xmath14 in the multi - rate pdae ( [ multirate ] ) , another problem occurs here . using an implicit multistep method for the discretization in @xmath14 , we need a predictor ( as initial guess for newton s method ) , which is usually based on the solution of the previous time step . here , a condition on @xmath12 as in ( [ min_cond ] ) occurs naturally . a condition on @xmath45 covers only contributions of the signal which are already smoothed ( by capacitances or inductances ) , and might not provide a sufficient initial guess . it turns out that condition ( [ min_cond ] ) yields the expected result for amplitude and frequency modulation of a periodic signal , i.e. , for typical multirate rf signals . [ mr_modulated ] assume @xmath46 with @xmath47 is a solution of _ ( [ singlerate ] ) _ with non - trivial @xmath48 and @xmath49 . the solution of the corresponding multi - rate problem _ ( [ multirate ] ) _ satisfies _ ( [ min_cond ] ) _ if and only if @xmath50 and @xmath51 . according to ( [ character ] ) and ( [ omega2 ] ) we can write the multi - rate solution as @xmath52 , where @xmath53 vanishes if and only if @xmath50 . taking the derivative with respect to @xmath14 we obtain @xmath54 note , that due to periodicity of @xmath55 we have @xmath56 thus , the expression in ( [ min_cond ] ) , which has to be minimized becomes @xmath57 obviously the expression becomes minimal if @xmath58 , @xmath59 $ ] . from ( [ omega2 ] ) we see that @xmath60 and the statement is proven . applying the approach to more general problems , permits to consider @xmath61 as a generalization of the instantaneous frequency of the multi - rate problem , if ( [ min_cond ] ) is satisfied . for the numerical solution of the multi - rate problem we have to discretize the mpdae s ( [ multirate ] ) together with the smoothness condition ( [ min_cond ] ) . the following section presents a new approach for the numerical solution of the multi - rate problem with unknown frequency parameter . we discretize ( [ multirate ] ) with respect to @xmath14 by a rothe method using a linear multi step method and obtain @xmath62 complemented by the periodicity condition @xmath63 . here we have to determine an approximation @xmath64 of @xmath65 from known , approximative solutions @xmath66 at previous time steps @xmath67 . examples are the trapezoidal rule with @xmath69 , @xmath70 and @xmath71 or gear - bdf of order @xmath72 with @xmath73 and suitable @xmath74 . that is , @xmath75 is the solution of a periodic boundary value problem for the daes given in ( [ rothe ] ) . assuming that the @xmath67 , @xmath76 and @xmath66 are known and fixed for @xmath77 we define @xmath78 & + ~\sum_{i=1}^s\bigg\ { \alpha^k_i q\big(x_{k - i}(t)\big ) + \beta^k_i \left(\omega_{k - i}\,\frac{d}{dt}q\big(x_{k - i}(t)\big ) + g\big(x_{k - i}(t)\big)-\hat{s}\big(\tau_{k - i},t\big)\right)\bigg\},\end{aligned}\ ] ] as well as @xmath79 . then ( [ rothe ] ) becomes the periodic boundary value problem @xmath80 furthermore , @xmath81 is an approximation for @xmath82 , which has to be determined during the computation ( if not known in advance ) . since the midpoint rule states for a suitable choice of @xmath83 that @xmath84 we replace condition ( [ min_cond ] ) by @xmath85 i.e. , we aim to minimize the change of @xmath64 from one time step to the next , which corresponds well to the original goal . if we have a smooth envelope , we may be able to choose the step sizes @xmath86 much larger than the period @xmath87 . that means the number of time steps will become much smaller compared to the number of oscillations of the carrier signal . this can lead to an essential gain in computation time compared to transient analysis , since the computation cost for one period is comparable to one envelope time step . the periodic problem ( [ envelope ] ) can be solved by a collocation or galerkin method , where @xmath64 is expanded in a periodic basis @xmath88 ( as a fourier , b - spline , or wavelet basis ) and tested at collocation points or integrated against test functions ( see e.g. @xcite ) . this leads to a nonlinear system @xmath89 of equations for the coefficients @xmath90 of the basis expansion @xmath91 and the unknown frequency parameter @xmath92 . here , condition ( [ min_cond2 ] ) is replaced by a condition on the expansion coefficients , namely @xmath93 this means , that we are still minimizing the distance of @xmath64 and @xmath94 , although with respect to a slightly modified measure . the nonlinear system ( [ nonlinear ] ) is solved by a modified newton s method . the linearization of the problem yields the under - determined system @xmath95 with the right hand site @xmath96 , the jacobian @xmath97 , and @xmath98 . furthermore , @xmath99 and @xmath100 are the updates in the newton iteration @xmath101 with an initial guess chosen as @xmath102 and @xmath103 . to find a solution satisfying ( [ min_cond3 ] ) we rewrite ( [ newton_ud ] ) as @xmath104 where @xmath105 and @xmath106 are computed by solving the corresponding linear systems . this needs a lu - decomposition of @xmath107 and two forward - backward substitution , i.e. , the computational costs are only slightly higher as for @xmath19 fixed in advance . possible higher step sizes and faster convergence of newton s method justify this extra cost if a good choice for @xmath19 is not available in advance . in the @xmath108-th newton step @xmath109 we determine the newton correction , which satisfies ( [ min_cond3 ] ) as follows . we want @xmath110 to be minimal . obviously the minimum is attained for @xmath111 the method has been tested on several circuits . we show results from the multi - rate simulation of a phase locked loop ( pll ) with a frequency modulated input signal . the phase of the output signal is synchronized with the phase of the input `` reference '' signal . this is achieved , by comparing the phases of the `` reference '' signal and the output or `` feedback '' signal in a phase detector . the result is then filtered , in order to stabilize the behavior of the pll , and fed to a voltage controlled oscillator ( vco ) whose frequency depends on the ( filtered ) phase difference . the output is fed back ( possibly through a frequency divider ) to the phase detector . if the pll is locked , the phases of reference and feedback signal are synchronized . thus both signal will have ( almost ) the same local frequency . we have tested a pll ( containing 145 mosfets and 80 unknowns ) with a frequency modulated sinusoidal signal with frequency 222khz . the baseband signal is also sinusoidal with frequency 200hz and frequency deviation 200hz . we have chosen this example , since it was particular challenging , due to its size , but also due its digital - like behavior , which requires an efficient adaptive representation of the solution , as well as a very accurate estimate of the frequency parameter @xmath19 . although the baseband signal is known to us after locking of the pll , this information is not provided to the algorithm . this permits a verification of the @xmath19 determined by our algorithm . before the locking of the pll the optimal @xmath19 is not known to us , and the estimate of the algorithm proved essential for this part of the simulation to be successful . , scaledwidth=60.0% ] due to the chosen circuit design most of the signals show a digital behavior such that the solution can not efficiently be expanded by a fourier basis . thus , using the harmonic balance method is not suited for the solution of the problem , in particular since the use of a frequency divider results in a wide frequency range of the solution . therefore , the periodic problem is solved by an adaptive spline wavelet method described in @xcite . the quality of the estimate of @xmath19 is essential for the efficiency of the method , because this results in a good initial guess for the solution and the spline grid in newton s method . in figure [ pllcontrol ] ( left ) one can see the control signal for the vco ( the filtered output of the phase detector ) , which controls the frequency of the oscillator . note , that after the locking phase at the beginning the envelope corresponds to the baseband signal , while the carrier signal is due to the filtering almost constant . figure [ pllcontrol ] ( right ) shows the digital feedback signal . note that @xmath19 was chosen to satisfy the condition ( [ min_cond3 ] ) . the plot of @xmath19 in figure [ pllomega ] fits almost perfectly the baseband signal , after the pll is locked . in the light of lemma [ mr_modulated ] , the graphs in figures [ pllcontrol ] and [ pllomega ] show indeed a frequency modulated box shaped signal . the optimal choice of @xmath19 results in high smoothness with respect to @xmath14 . this allows to do the shown envelope simulation using only 74 envelope time steps , while a corresponding transient analysis would contain 3100 oscillations . the wavelet envelope simulation of this circuit was done in 7min . however , a comparable transient simulation on the same simulator needed 33hours . we have presented a new method for an accurate estimate of an unknown frequency parameter in multi - rate envelope simulations , which permits an efficient simulation even for challenging problems . k. bittner and e. dautbegovic ( 2012_a _ ) , adaptive wavelet - based method for simulation of electronic circuits , in _ scientific computing in electrical engineering 2010 _ ( b. michielsen and j .- r . poirier , eds ) , mathematics in industry , springer , berlin heidelberg , pp . 321 328 . k. bittner and e. dautbegovic ( 2012_b _ ) , wavelets algorithm for circuit simulation , in _ progress in industrial mathematics at ecmi 2010 _ ( m. gnther , a. bartel , m. brunk , s. schps and m. striebel , eds ) , mathematics in industry , springer , berlin heidelberg , pp . 5 11 . h. g. brachtendorf ( 1997 ) , on the relation of certain classes of ordinary differential algebraic equations with partial differential algebraic equations , technical report 1131g0 - 971114 - 19tm , bell - laboratories . h. g. brachtendorf ( 2001 ) , ` theorie und analyse von autonomen und quasiperiodisch angeregten elektrischen netzwerken . eine algorithmisch orientierte betrachtung ' , universitt bremen . abilitationsschrift . s. houben ( 2004 ) , simulating multi - tone free - running oscillators with optimal sweep following , in _ scientific computing in electrical engineering 2010 _ ( w. schilders , e. ter maten and s. houben , eds ) , mathematics in industry , springer , berlin , pp . 240 247 . e. ngoya and r. larchevque ( 1996 ) , envelope transient analysis : a new method for the transient and steady state analysis of microwave communication circuit and systems , in _ proc . ieee mtt - s int . microwave symp . _ , san francisco , pp . 13651368 .

* purpose rf circuits often possess a multi - rate behavior . slow changing baseband signals and fast oscillating carrier signals often occur in the same circuit . frequency modulated signals pose a particular challenge . * * design / methodology / approach the ordinary circuit differential equations ( odes ) are first rewritten by a system of ( multi - rate ) partial differential equations ( mpdes ) in order to decouple the different time scales . for an efficient simulation we need an optimal choice of a frequency dependent parameter . this is achieved by an additional smoothness condition . * * finding by incorporating the smoothness condition into the discretization , we obtain a nonlinear system of equations complemented by a minimization constraint . this problem is solved by a modified newton method , which needs only little extra computational effort . the method is tested on a phase locked loop with a frequency modulated input signal . * * originality / value a new optimal frequency sweep method was introduced , which will permit a very efficient simulation of multi - rate circuits . * rf circuit simulation , multi - rate simulation , envelope simulation . * paper type : * research paper

supracervical hysterectomy is considered controversial . however , according to the latest american association of gynecologic laparoscopists ( aagl ) survey , the performance of laparoscopic supracervical hysterectomies ( lsh ) is apparently increasing . lsh has several advantages but is admittedly only for a subset of patients who meet the following criteria : the patient must have a history of negative pap smears . . the patient must be compliant and dependable when it comes to undergoing annual pap smears . recently , a new instrument , the lap loop ( medsys , gembloux , belgium ) monopolar electrode for resection and detachment of the uterine corpus from the cervix has been developed by dequesne ( figure 1 ) . we are the first center in the united states to try this new device in laparoscopic supracervical hysterectomy . herein , we describe this new technique and compare it with the traditional methods of detachment of the uterine corpus in laparoscopic supracervical hysterectomy . the loop electrode consists of 3 parts : the 10-mm introducer , electrode shaft , and disposable cutting wire electrode . the wire electrode is insulated at the ends and has only a 2-cm area in the middle of the wire that maintains contact with the cervix . the screw end of the wire electrode is screwed into the tip of the electrode shaft , and the wire is placed around the cervix . the ball on the other end of the electrode is inserted and locked into the slit on the tip of the electrode shaft completing the loop and the circuit . seventeen patients signed consent forms to participate in this study of the experimental device ( lap loop system ) for fundal detachment in laparoscopic supracervical hysterectomy . the institutional review board at the university of louisville school of medicine and norton healthcare hospitals approved this study . study patients were compared with a control group of 12 patients with similar characteristics who underwent supracervical hysterectomy using the conventional methods of uterine detachment with either laparoscopic monopolar scissors or harmonic scalpel . all patients fulfilled the following inclusion criteria : patients with a clear indication for hysterectomy with benign gynecologic conditions ; patients with a healthy cervix with a negative pap smear and normal endometrial biopsy ; patients who agreed to a follow - up schedule of annual pap smears . the operative time was calculated in minutes from the time of the first incision to the time of the last dressing . loop application time was calculated from the beginning of its insertion through the trocar until the complete positioning of the loop around the cervix . cervical cutting time was calculated from the activation of the monopolar current indicating actual beginning of cutting until the body of the uterus became freely detached from the cervix . cervical cutting in the control group was measured from the beginning to the completion of the cervical transection . the loop application and actual cutting time were compared with the cutting time by conventional methods . all patients were discharged as soon as they were able to tolerate food , not in need of parenteral pain medications , able to ambulate , able to void without a catheter , and with stable hemoglobin / hematocrit values . after both uterine arteries were coagulated using either the harmonic scalpel or bipolar forceps and the bladder dissection was completed , the cervix was transected at the level of the internal ostium . pushing the uterus from below with a uterine manipulator moved the cervix away from the ureters facilitating the safer amputation of the uterine corpus . the ureters are about 2 cm lateral to the point at which the uterus is separated from the cervix ; therefore , visualization of the ureters during the operation is helpful . the lap loop electrode consists of 3 parts ( figure 1 ) : the 10-mm introducer , electrode shaft , and disposable cutting wire electrode . the wire electrode has a small screw at one end and a ball at the other end . the screw end of the wire electrode is screwed into the tip of the electrode shaft . the shaft with the wire is inserted into the abdomen through the 10-mm introducer via a lateral 10-mm trocar . the wire is insulated at the ends and has only a 2-cm area in the middle of the wire that is in contact with the cervix . the wire electrode at the tip of the lap loop device is grasped with a grasper and manipulated around the cervix so that the ball is placed into the slit at the tip of the shaft electrode to form a loop ( figure 2a ) . once the ball is placed into the slit of the electrode shaft , it is pulled back into the introducer therefore locking the loop in place around the cervix . the position of the wire loop is checked to guarantee it is snug around the cervix without compressing the tissue and to ensure that the loop is not in contact with any other structures , such as bowel or the pelvic sidewall ( figure 2b ) . once the bare part of the wire is directly applied to the cervix , it ensures that the energy is directed to the uterine isthmus and not randomly to other tissues . conversely , as with any electrocautery , avoiding excessive pressure against the tissue ensures timely spark creation for efficient cutting action . a 100-w unipolar cutting current is applied , and the loop electrode is pulled back into the introducer slicing the wire loop through the cervix and detaching the uterine corpus from the cervix ( figure 2c ) . passage of the wire electrode leaves a perfectly clean and hemostatic cut on the cervical stump . the wire electrode at the tip of the lap loop device is grasped with a grasper and manipulated around the cervix . the ball at the end of the wire electrode is placed into the slit at the tip of the shaft electrode to form a loop ( 2a , b ) . once the ball has been placed into the slit , the electrode shaft is pulled back into the introducer locking the loop in place around the cervix , ensuring the shielding of the noninsulated part of the wire other than that in direct contact with the cervix . a unipolar cutting current is applied , and the loop electrode is slowly pulled back into the introducer permitting the wire to slice through the cervix and detaching the uterine corpus from the cervix ( 2c ) . after detachment from the cervix , the corpus of the uterus is removed with morcellation by using either the gynecare x - tract tissue morcellator ( gynecare , somerville , new jersey , usa ) or the storz morcellator ( storz , tutlingen germany ) . cautery of the endocervical canal is performed using bipolar forceps at the completion of the operation . this step is intended to reduce the chance of developing subsequent cervical stump cancer and to eliminate possible menstrual bleeding that may occur from endometrium remaining in the cervical canal . after irrigation and final inspection of the peritoneal cavity cystoscopy was performed on all study patients to make sure that both ureters were intact after the hysterectomy was completed and patients were taken to the recovery and floor units . statistical analysis was performed using spss software ( version 11.0 ) , and with consultation and the recommendations of our statistician , statistical significance was calculated using the student t test for real numbers , and a p value of < 0.05 was considered statistically significant . after both uterine arteries were coagulated using either the harmonic scalpel or bipolar forceps and the bladder dissection was completed , the cervix was transected at the level of the internal ostium . pushing the uterus from below with a uterine manipulator moved the cervix away from the ureters facilitating the safer amputation of the uterine corpus . the ureters are about 2 cm lateral to the point at which the uterus is separated from the cervix ; therefore , visualization of the ureters during the operation is helpful . the lap loop electrode consists of 3 parts ( figure 1 ) : the 10-mm introducer , electrode shaft , and disposable cutting wire electrode . the wire electrode has a small screw at one end and a ball at the other end . the screw end of the wire electrode is screwed into the tip of the electrode shaft . the shaft with the wire is inserted into the abdomen through the 10-mm introducer via a lateral 10-mm trocar . the wire is insulated at the ends and has only a 2-cm area in the middle of the wire that is in contact with the cervix . the wire electrode at the tip of the lap loop device is grasped with a grasper and manipulated around the cervix so that the ball is placed into the slit at the tip of the shaft electrode to form a loop ( figure 2a ) . once the ball is placed into the slit of the electrode shaft , it is pulled back into the introducer therefore locking the loop in place around the cervix . the position of the wire loop is checked to guarantee it is snug around the cervix without compressing the tissue and to ensure that the loop is not in contact with any other structures , such as bowel or the pelvic sidewall ( figure 2b ) . once the bare part of the wire is directly applied to the cervix , it ensures that the energy is directed to the uterine isthmus and not randomly to other tissues . conversely , as with any electrocautery , avoiding excessive pressure against the tissue ensures timely spark creation for efficient cutting action . a 100-w unipolar cutting current is applied , and the loop electrode is pulled back into the introducer slicing the wire loop through the cervix and detaching the uterine corpus from the cervix ( figure 2c ) . passage of the wire electrode leaves a perfectly clean and hemostatic cut on the cervical stump . the wire electrode at the tip of the lap loop device is grasped with a grasper and manipulated around the cervix . the ball at the end of the wire electrode is placed into the slit at the tip of the shaft electrode to form a loop ( 2a , b ) . once the ball has been placed into the slit , the electrode shaft is pulled back into the introducer locking the loop in place around the cervix , ensuring the shielding of the noninsulated part of the wire other than that in direct contact with the cervix . a unipolar cutting current is applied , and the loop electrode is slowly pulled back into the introducer permitting the wire to slice through the cervix and detaching the uterine corpus from the cervix ( 2c ) . after detachment from the cervix , the corpus of the uterus is removed with morcellation by using either the gynecare x - tract tissue morcellator ( gynecare , somerville , new jersey , usa ) or the storz morcellator ( storz , tutlingen germany ) . cautery of the endocervical canal is performed using bipolar forceps at the completion of the operation . this step is intended to reduce the chance of developing subsequent cervical stump cancer and to eliminate possible menstrual bleeding that may occur from endometrium remaining in the cervical canal . after irrigation and final inspection of the peritoneal cavity cystoscopy was performed on all study patients to make sure that both ureters were intact after the hysterectomy was completed and patients were taken to the recovery and floor units . statistical analysis was performed using spss software ( version 11.0 ) , and with consultation and the recommendations of our statistician , statistical significance was calculated using the student t test for real numbers , and a p value of < 0.05 was considered statistically significant . the patients where divided into 2 groups . the loop electrode was used in 17 patients and the conventional method of cervical detachment with unipolar scissors or harmonic scalpel was used in 12 patients . operative time among lap loop patients ranged from 90 minutes to 206 minutes ( mean , 140.1 ) . operative time among control patients ranged from 69 minutes to 180 minutes ( mean , 131.5 ) . the estimated blood loss ( ebl ) in the lap loop group ranged from 50 ml to 600 ml ( mean , 205 ) . the ebl for the control group ranged from 20 ml to 200 ml ( mean , 76 ml ) . the loop application time ranged from 3.5 minutes to 12 minutes ( mean , 6.1 ) . the actual cervical cutting time that was measured after the loop was placed around the cervix and the monopolar current was activated ranged from 15 seconds to100 seconds ( mean , 33.5 ) . the total loop application and cutting time ranged from 4.3 minutes to 12.8 minutes ( mean , 6.6 ) . the cervical cutting time in the control group ranged from 6.5 minutes to 22 minutes ( mean , 14.4 ) . when comparing the total of the application and cutting time for the loop electrode with the cutting time in the control group , a statistically significant difference was observed in the amount of time required for amputation of the uterine corpus from the cervix . thus , cervical cutting time was reduced even though total time may or may not have been shorter for the entire surgical procedure . patient characteristics the average postoperative pain score for both groups , according to the vas ( visual analog scale ) , was 3.2 . the mean hospital stay for the study patients was 32 hours ( range , 23 to 120 ) . the mean hospital stay for the control group was 29 hours ( range , 23 to 48 ) . however , only 1 patient had a relatively major complication , incisional hernia ( 3.7% ) . on postoperative day 4 , this patient was reoperated on and left the hospital the next day . one case of liver puncture by a veress needle secondary to left upper quadrant entry was treated expectantly . this injury was the result of a seldom seen , very rare occurrence in some patients where enlargement of the left lobe of the liver may cause it to be just below the point of needle insertion . it has been shown in other studies that supracervical hysterectomy performed by laparoscopy ( lsh ) results in a reduction in blood loss , operative time , and surgical complications compared with total laparoscopic hysterectomies and abdominal hysterectomies . there is also less risk of postoperative pain and infection , vault prolapse , enterocele , and painful vaginal scarring in addition to shorter hospital stay and convalescence , and lower overall cost . dequesne et al reported that a further decrease in operating time can be achieved with the loop technique for uterine corpus amputation . safety has always been an important consideration when choosing a supracervical procedure over total hysterectomy . amputation of the uterine corpus at the level of the internal ostium is the crucial and technically most challenging part of the supracervical hysterectomy . even in the case of a small uterus precise dissection is difficult to perform because bowel is often in the way and attention should be paid to not injure the pelvic sidewall and the ureters . this risk seems to be reduced considerably with the use of the electrosurgical loop electrode . because a large portion of the loop is electrically insulated , the electrode can safely be used for cervical transection without fear of collateral damage . the main advantages of the loop electrode are safety , precision of the cut , and reduced operating time . we believe that further reduction in the operative time can be achieved with the use of the lap loop electrode . this relatively lengthy time may be explained by the fact that all of the procedures were performed by residents in a training setting and that cystoscopy was performed routinely on all patients to ensure ureteral integrity . although not statistically significant , we achieved shorter operative times in the control group . surgical times with the loop were longer because we first used it when we began performing lsh and then started using other techniques on subsequent patients . the length of the entire hysterectomy in this study is not relevant because we have clearly demonstrated that the cervical cutting time is much shorter with the loop compared with cutting time in other conventional methods . the loop applies only to that particular step of this procedure that is also the most complex and requires the greatest surgical skill . the statistically significant difference was observed in the time required to amputate the uterine corpus in the lap loop group compared with that in the control . the mean application and cutting time for the lap loop electrode in this study was 6.6 minutes . the use of the lap loop electrode considerably simplified cervical amputation and decreased the time required for the detachment of the uterine corpus , which many consider the more difficult part of laparoscopic subtotal hysterectomy . this may explain the fact that although not statistically significant , operating time and blood loss were smaller in the control group than in the lap loop group . two minor complications and only one relatively major complication , an incisional hernia , occurred in the study . the hernia patient was taken to the operating room on postoperative day 4 and was discharged home the next day . the minor complication was puncture to the left lobe of the liver with the veress needle during left upper quadrant insufflation that was treated expectantly . this injury resulted from the rare occurrence of a patient with an enlarged left lobe of the liver . one patient from the lap loop group developed an ectopic pregnancy 4 months after hysterectomy and was treated by laparoscopic salpingectomy . we do not believe that this unusual incident was related to the use of the device at the time of the hysterectomy . dequesne et al reported no complications in their 127 patients operated on with this new device . the mean estimated blood loss in the study patients was 205 ml , and no patients required a blood transfusion . the estimated blood loss in the control group was not statistically different from blood loss in the study group . the average postoperative pain score was 3.2 on a visual assessment ( vas ) pain scale of 1 to 10 . the mean hospital stay was 32 hours , which means that most of the patients were able to leave the hospital the day after surgery without problems . the majority of the patients were discharged home within the 23-hour admit policy fulfilling the criteria for the outpatient procedure . the main advantages of the new electrosurgical loop system is the simplicity of use combined with increased safety , reduced time required for cervical amputation , and the precision of the cervical cut . the benefits of laparoscopic supracervical hysterectomy clearly outweigh the risks . an electrosurgical loop has been designed and successfully used to decrease the time required and to facilitate safer , quicker transection of the uterine cervix during lsh for benign uterine conditions .

objectives : our aim was to evaluate a new electrosurgical instrument ( lap loop device ) that amputates the uterine corpus from the cervix during a laparoscopic supracervical hysterectomy ( lsh ) and to compare the time required for cervical amputation with traditional methods.methods:this comparative trial was conducted at the university of louisville and norton healthcare hospitals , louisville , ky . the patients comprised 29 women scheduled for hysterectomy for benign conditions . all patients underwent laparoscopic supracervical hysterectomy . the lap loop device was used in 17 patients to section the cervix . conventional methods with either laparoscopic monopolar scissors or harmonic scalpel were used in 12 patients.results:in the control group , the mean cervical cutting time with laparoscopic scissors or harmonic scalpel was 14.4 minutes . the mean time for the application of the loop electrode and cutting time was 6.6 minutes and was significantly shorter than the cutting time of conventional methods . two minor complications ( 7.4% of cases ) and one relatively major complication ( 3.7% ) , an incisional hernia , occurred in the study patients . none of the complications were related to the new device.conclusion:an electrosurgical loop decreased the time required for resection of the uterine cervix during lsh for benign uterine conditions . this device facilitates and increases the safety of this procedure .

the main outcome of the relativistic heavy ion collision ( rhic ) experiments is the creation of a deconfined medium of strongly interacting quarks and gluons , known as quark gluon plasma ( qgp ) . since the hqs are mainly produced at the initial stage of heavy - ion collisions and the thermalization time of hqs are of the order of the lifetime of qgp therefore hqs are the suitable candidate to probe the qgp . due to the large mass of hq , it was expected from perturbative qcd , the nuclear suppression factor , @xmath0 would have been large , _ viz . _ @xmath1 0.6 and 0.8 - 0.9 for charm and bottom quarks , respectively @xcite and the elliptic flow ( measured as @xmath2 ) of heavy flavoured hadrons were expected to be smaller than the light hadrons @xcite but the experimental data reveals the opposite trend , _ i.e. _ smaller @xmath0 and large @xmath2 @xcite . therefore , to circumvent the contradictory observation , investigation for the evolution of hqs with the proper input and the accompanied energy - loss mechanism in the hot and dense qgp becomes essential . + for the evolution of hqs in the medium , understanding about the energy - loss mechanisms of hqs becomes vital . there are mainly two mechanisms for the energy loss of hqs : the first one is the medium induced gluon radiation ( radiation energy loss ) and the other one is the quasielastic scattering with the background medium partons ( collisional energy loss ) . earlier it was thought that the medium induced gluon radiation is the dominant one but recent studies suggest that this process is suppressed by the large mass of heavy quark , dubbed as `` dead - cone effect '' @xcite , thus the collisional energy loss is then considered to be responsible especially at lower energies eg . , rhic energy @xcite . however , at lhc energy the `` dead - cone effect '' is not so pronounced thus the radiational energy loss become commensurate again . in brief , the issue is not yet settled and one can only say that both mechanisms for the energy loss are equally important to understand the experimental data for both @xmath0 and @xmath2 @xcite . + since the evolution of hqs in phase space can be envisaged as the motion of a nonequilibrated particle in an equilibrium medium therefore the motion of hqs can be thought as the random motion or the brownian motion in the heat bath of an equilibrated plasma because the mass of hq is much smaller than the temperature of the medium . thus the trajectories of hqs due to its random motion can be quantified by the langevin dynamics @xcite , which , however , can also be studied by the fokker - plank equation @xcite in the limit of soft scattering ( landau ) approximation . other approaches have also been employed to study the hqs dynamics at rhic and lhc energies , _ viz . _ relativistic boltzmann transport approach @xcite , where the boltzmann equation is solved numerically by discretizing the space into a 3-dimensional lattice and the collisional integral is modeled by the stochastic sampling of the collision probability . instead of a constant coupling , the running coupling and the improved scattering matrix @xcite within perturbative qcd framework supplemented by hard thermal loop ( htl ) scheme has been employed to improve upon the collision integral and thence the drag and diffusion coefficients can be refined further . since the emergence of hadronic phase is inevitable in rhic therefore some efforts have also been made to understand the evolution of heavy flavours in hadronic medium @xcite , which deciphers to subtract the hadronic contribution from the data to separate the effect of qgp alone . recently @xcite , authors have shown that even a weak coupling of heavy flavour hadrons to the hadronic medium can lead to a noticeable contribution to the total elliptic flow . the aforesaid discussions are limited to the weak coupling limit , thus some groups used the complementary setup of the gauge - gravity duality @xcite to understand the heavy flavour dynamics at strong coupling limit in heavy ion collisions . in summary , after so many efforts , all models face some difficulties to describe both @xmath0 and @xmath2 of heavy mesons simultaneously . the ultimate aim of the studies on the the drag and diffusion coefficients is to determine the transverse and the azimuthal momentum distribution of hqs . the fluctuation of the momentum encoded in the diffusion coefficient can be understood in terms of the random forces acting on the heavy quarks , which is defined by the auto - correlation of the random forces @xcite . on the other hand , the drag coefficient , in relaxation - time approximation , is related to the kinetic equilibration rate of hqs in a thermal medium @xcite . asymptotically the drag and diffusion coefficients are related by the fluctuation - dissipation theorem ( fdt ) : @xmath3 ( non - relativistically the fdt relation is @xmath4 ) , where @xmath5 and @xmath6 are the momentum and drag coefficients , respectively . one of our aim in this article is to check the fdt theorem . nowadays it is expected that the rhic collisions at the initial stage may induce an anisotropy in the momentum space due to the asymptotic free expansion of the fireball in the beam direction compared to its transverse direction . thus the strongly interacting fluid created in rhic possesses momentum - space anisotropies in the local rest frame @xcite for a short duration of time in the initial stage . since the heavy quarks too are produced in the initial stage of the collision therefore the momentum - space anisotropies may have important implications on heavy quark dynamics . this anisotropy subsequently induces the chromo - weibal instability @xcite in the medium , which may significantly affect the hq drag and diffusion coefficients @xcite and facilitates early equilibration of the medium . thus it is desirable to study the effect of momentum - space anisotropy on the drag and diffusion coefficients of hqs , which , in turn may have significant impact on the experimental observables , _ e.g. _ @xmath0 and @xmath2 @xcite . + in this article we have thus explored the effect of momentum anisotropy on the drag and diffusion coefficients due to collisional energy loss only when a test charm quark evolves in a hot anisotropic qcd medium . in our calculation we employ the one - loop running coupling constant and the debye mass in the leading and next - to - leading order to see the effect of the regulator on the @xmath7-channel matrix element , which appears in the collision integral . our work is thus organized as follows : first , in subsection ii a we revisited the drag and diffusion coefficients arises due to collisional energy loss alone in an isotropic medium . here we closely follow the kinematics used by svetitsky @xcite with the corrected matrix elements made in ref . we then move on to an anisotropic medium in subsection ii b , where it is found that for weak anisotropic limit ( @xmath8 ) , both coefficients can be decomposed into the dominant isotopic and the sub - leading anisotropic contributions . later we demonstrate our results for an isotropic medium in subsection iii a and understand the salient features of both coefficients as a function of momentum , temperature etc . and its connection with the microscopic properties of hqs evolution from the point of view of statistical mechanics . with these understanding in isotropic medium , we then explain the numerical results for anisotropic medium in subsection iii b. we have noticed that how the momentum anisotropy affects the coefficients and finally transpires to the equilibration rate . finally we conclude in section iv . since the thermalization of hqs is very slow compared to the light quarks and gluons therefore a description of the motion of non - equilibrated degrees of freedom in the background of equilibrated degrees of freedom is required . the appropriate framework is provided by the fokker - planck equation . therefore we start with the boltzmann transport equation describing a non - equilibrium statistical system as follows : @xmath9 for @xmath10 interaction the collisional integral appearing in the right hand side of above transport equation can be written as : @xmath11 , \label{two}\ ] ] where @xmath12 is the rate of collision which encodes the change of hq momentum from @xmath13 to @xmath14 and can be expressed as @xcite : @xmath15 here @xmath16 is the phase space distribution of the bulk constituents , @xmath17 is the relative velocity between the two collision partners , @xmath18 represents the cross - section and @xmath19 is the statistical degeneracy of the particles in qcd medium . using the soft - scattering landau approximation in the collision integral , the resulting fokker - planck equation ( [ one ] ) is cast in the form @xmath20\right ] , \label{four}\ ] ] where the kernels are defined as : @xmath21 and @xmath22 in low momentum transfer limit ( @xmath23 ) , kernels are reduced into @xmath24 and @xmath25 where @xmath6 and @xmath5 are the drag and diffusion coefficient , respectively . the generic integral appeared for both the drag and diffusion coefficients for hq in a hot and isotropic medium of massless quarks and gluons is given by @xcite : @xmath26 where @xmath27 and @xmath28 are the masses and degeneracy factors of heavy quarks , respectively ( here we use @xmath29 gev for charm quark ) and @xmath30 , the equilibrium distribution function of the massless quarks and gluons is given by @xmath31 where @xmath32 sign is for quarks and gluons , respectively . + depending on the drag or diffusion , the function , @xmath33 in the integral ( [ seven ] ) is given by @xmath34 for the drag coefficient whereas for the diffusion coefficient @xmath35~ , \label{ten}\ ] ] where the dot product , @xmath36 is calculated from the expression @xcite : @xmath37 where @xmath38 are the energies of incident and scattered heavy quarks in the lab frame , @xmath39 and @xmath40 are the energy and momentum of heavy quarks in the cm frame , respectively , and @xmath41 is the cm scattering angle ( hereafter the cap represents the variables in the cm frame ) . the energy , @xmath42 in the laboratory frame is related to the cm frame by inverse lorentz transformation : @xmath43~ , \label{twelve}\end{aligned}\ ] ] where the lorentz factor and velocity in the cm frame are given by , @xmath44 respectively . the energy , @xmath39 and the magnitude of the momentum @xmath45 in the cm frame can be written as : @xmath46 respectively . now the dot product @xmath47 , in ( [ twelve ] ) can be calculated by the using lorentz transformation of @xmath40 from lab frame to cm frame @xmath48 as @xmath49 which can be further simplified as : @xmath50 the factor , @xmath51 in eq . ( [ twelve ] ) can be obtained as @xcite : @xmath52 and the mandelstam variable , @xmath53 in cm frame is given by @xmath54 where @xmath55 is the angle between @xmath56 and @xmath57 . + in the present work , we consider the collisional energy loss of hqs , where the hqs are scattered quasi - elastically with the partons in qgp medium : @xmath58 ( the quantities inside the bracket denotes the four momentum of the particle ) . if the hq is scattered by the quark ( anti - quark ) then the matrix element for the corresponding process is @xcite : @xmath59 , \label{twentyone}\ ] ] whereas the matrix element for the gluon scattering is given by @xcite : @xmath60 . \label{twentytwo}\end{aligned}\ ] ] in the above eqs . ( [ twentyone ] , [ twentytwo ] ) , the @xmath7 and @xmath61 variables are given by @xmath62 and @xmath63 is the regulator , which is needed to shield the infra - red divergences arising in the @xmath7-channel scattering amplitude . in our calculation we take it as the leading - order debye mass @xmath64 as @xcite : @xmath65 \label{twentythree}\ ] ] where @xmath19 is the strong qcd coupling in one - loop . recently it is envisaged that the partonic system generated in ultra - relativistic heavy - ion collisions at the nascent stage may not be necessarily isotropic in the momentum space rather the medium exhibits a momentum anisotropy due to the rapid expansion in the longitudinal direction compared to the transverse directions @xcite . this motivates us to study the transport coefficients related to drag and diffusion processes in such anisotropic medium . if the anisotropy is small then the anisotropic distribution is obtained by either stretching or squeezing the isotropic distribution along a certain direction , thereby preserving a cylindrical symmetry in momentum space . in particular , the anisotropic distribution relevant for relativistic heavy ion collision can be approximated by removing particles with the large momentum component along the direction of anisotropy , @xmath66 as @xcite : @xmath67 where @xmath68 is an arbitrary isotropic distribution function and @xmath69 is the anisotropic parameter and is generically defined as : @xmath70 where @xmath71 and @xmath72 are the components of momentum parallel and perpendicular to @xmath73 , respectively . there have been significant advancement in the dynamical models used to simulate plasma evolution having momentum - space anisotropies @xcite . one of us have studied the effects of momentum anisotropy on the quarkonia states by the leading - anisotropic correction to the resummed gluon propagator @xcite which subsequently affects the suppression of quarkonium production at rhic and lhc . recently we have investigated the effect of momentum anisotropy on one the transport coefficients , _ namely _ the electrical conductivity @xcite . if the distribution function is nearly an ideal gas distribution and the anisotropy , @xmath69 is small then @xmath69 can be related to the shear viscosity of the medium via the one - dimensional bjorken expansion in the navier - stokes limit @xcite : : @xmath74 for an expanding system , non - vanishing viscosity implies the finite relaxation time in the momentum space , hence an anisotropy of the particle momenta does appear inherently , _ for example _ for the ratio , @xmath75 in the range , 0.1 - 0.3 and @xmath76 , one finds @xmath69 tentatively as @xmath77 . + as we have explained , hot qcd medium due to expansion and non zero viscosity , exhibits a local anisotropy in momentum space , therefore the quark distribution function in the anisotropic medium can be approximated for a baryonless medium ( @xmath78 ) : @xmath79 for weakly anisotropic systems ( @xmath80 ) , one can expand the distribution function and keep the leading term in @xmath69 only : @xmath81 where @xmath57 @xmath82 @xmath83 and @xmath66 @xmath82 @xmath84 or @xmath85 . @xmath86 is the angle between @xmath57 and @xmath66 . therefore the drag and diffusion coefficients in a weakly anisotropic medium may be obtained by replacing the phase - space distribution in the anisotropic medium ( [ anisodist ] ) @xmath87 since @xmath88 has two part : isotropic and correction due to momentum anisotropy . the resulting expression for drag and diffusion has two parts . the isotropic part is similar to eq.([seven ] ) . the expression for anisotropic part is as follows : @xmath89 now using the definition of @xmath90 and @xmath91 , one can get the expression for @xmath92 as follows : @xmath93 putting this value in eq . ( [ thirty ] ) and integrating over @xmath94 , we can get the modified expression as follows for the anisotropic correction part : @xmath95\\ \nonumber & \times&{f^{0}}^{2}(q)e^{e_{q}/t}\frac{\omega^{1/2}}{s}\\ \nonumber & \times&\int_{-1}^{1}d(cos\hat{\theta})\frac{1}{g_{q}}\sum \overline{|m|}^2\\ \nonumber & \times&\int_{0}^{2\pi}f({\mathbf p}^{'})~d\hat{\phi}. \label{thirtytwo}\end{aligned}\ ] ] thus the total drag and/or diffusion coefficient for an anisotropic qgp is : @xmath96 dash - dotted curve represents the drag on heavy quark due to light quarks of the qgp medium and dotted curve shows the contribution of gluons . further solid curve is the sum of these two contributions . ( b ) variation of diffusion coefficient of charm quark with respect to hq momentum . all other things are similar to ( a ) . ] gev , and ( b ) @xmath97 gev . ] first of all we would like to explore how the charm quarks are dragged by the partons while propagating in a hot and isotropic medium through its drag coefficient . to see the effects of intrinsic motion of test quark , we vary the momentum of charm quark from non - relativistic limit ( @xmath97 gev ) to relativistic limit ( @xmath13=5 gev ) in figure 1(a ) at some temperature , @xmath98 gev of the medium . during the evolution of heavy quarks in medium , the charm quarks are dragged by both quarks and gluons , thus we calculate separately the contribution by quarks , gluons and their sum total , which are shown by the dash - dotted , dotted and solid curves , respectively . in our calculation of the matrix element in @xmath7-channel , we take the regulator , @xmath99 as the leading - order debye mass , @xmath100 , unlike a constant value used in other calculations . for the temperature dependence of the debye mass , we take the strong coupling ( @xmath101 ) from one - loop expression . we found that the drag coefficient decreases when the momentum of the charm quark increases . this observation agrees with common sense because the relative speed of the charm quark with respect to the medium increases with the increase its momentum and hence the drag coefficient decreases . the above observation can be understood from the point of view of statistical mechanics in the following way : the equilibration rate of hqs in phase space decreases with the increase in its momentum , hence the drag coefficient for hqs should decrease with its momentum because the drag coefficient is related linearly to the kinetic equilibration rate . this understanding will later be useful to understand the variation of diffusion coefficient with the momentum ( in fig . another observation of fig . 1 ( a ) is that the momentum dependence of the drag coefficient are mostly emanated from the gluon scattering due to their abundance and the large contribution to the cross - section whereas the contribution by light quarks is meagre . on the other hand the momentum dependence of the diffusion coefficient is opposite , _ i.e. _ @xmath102 increases with the momentum ( shown in figure 1b ) because it is easy for hqs having larger momentum to diffuse in the system compared to hqs of lower momentum . from the point of view of statistical physics , the diffusion coefficient is a measure of the equilibration time ( inverse of the equilibration rate ) thus the coefficient should be greater when the hq momentum becomes larger . like the drag coefficient , the gluons contribute substantially to the momentum dependence of diffusion coefficient compared to the meagre contribution by quarks . gev , and ( b ) @xmath97 gev as function of temperature ( @xmath103 ) . we have plotted both coefficients at two different values of matrix regulator ie . , @xmath104 and @xmath105 , where @xmath106 is the debye mass . ] in fig . 2(a ) , we have studied how a relativistic charm quark is diffused or dragged while evolving in a static isotropic qcd medium when the temperature of the medium changes from lower to higher values . we found that the drag coefficient becomes small and increases with the temperature slowly whereas the diffusion coefficient increases with the temperature rapidly , so their separation ( @xmath107 increases with the temperature . this can be understood qualitatively : since the momentum is much higher than the temperature of the medium therefore the physical scale set here is the momentum of hq only . if the temperature of a thermal medium is increased then the constituents of the medium exert more and more random force on the test particle , thus the increase of temperature causes the motion of the test particle more random . since the diffusion is asymptotically related to the temperature of the medium , therefore the diffusion coefficient increase with the increase of the temperature . similar to fig . 2a , in figure 2 b , we have explored how do the drag and diffusion coefficients depend on the temperature for a non - relativistic charm quark ( @xmath97 gev ) . since the relative speed of hq becomes small therefore the drag coefficient becomes large . by the same reasoning as in figure 2 a , the relevant scale set here is the temperature of the medium , _ not the momentum of the test hq_. thus both the equilibration rate and the random force exerted by the partons increase with the temperature for hqs having low momentum . hence both drag and diffusion coefficients increase with the temperature . the increase of diffusion coefficient with the temperature in both figures ( figure 2 a & b ) is understandable because the number of constituents faced by the test particle increases with temperature ( for massless case , @xmath108 ) and thus the random force exerted on hq by the constituents increases . as we mentioned earlier in figs 1 and 2 , we have taken the regulator in the @xmath7 channel matrix element by the debye mass in leading - order ( @xmath109 ) . the debye mass in the leading - order is correct in the weak coupling regime when the coupling constant is very small @xmath110 . however when @xmath111 then higher order corrections also arise in the debye mass @xcite . kajantie et al . @xcite computed these contributions of @xmath112 and @xmath113 from a three - dimensional effective field theory . here we wish to see the effect of the regulator on the drag and diffusion coefficients due to the corrections in the debye mass . thus , we have used two regulators : @xmath114 and @xmath115 , where the factor @xmath116 takes into account the next - to - leading order corrections , for relativistic ( @xmath13= 5 gev ) and non - relativistic ( @xmath13=0.001 gev ) in figures 3 a and b , respectively . we observed that the inclusion of higher order effects in the debye mass as the regulator decreases both drag and diffusion coefficients . to be specific , the changes in drag coefficient of non - relativistic hqs due to increase in the regulator are about @xmath117 while going from t=0.2 gev to t=0.6 gev whereas in relativistic regime the change in drag coefficient ( @xmath118 ) is almost independent to the change in temperature . further the change in the value of diffusion is about @xmath119 as one goes from lower to higher temperature at non - relativistic momentum but again the percentage of change in diffusion ( @xmath118 ) remains independent to the temperature at relativistic momentum @xmath120 gev . + ) with respect to hq momentum @xmath13 at fixed value of qgp temperature @xmath98 gev . we have also plotted the product of hq energy ( @xmath121 ) and temperature ( @xmath103 ) by dash - dotted curve for comparison . ] to check the validity of the fluctuation dissipation theorem ( fdt ) for a picture where the non - equilibrated degrees of freedom ( in this case it is heavy quarks ) evolves in the background of equilibrated degrees of freedom , we have studied the ratio of the diffusion to drag coefficient ( @xmath122 ) for dynamical hqs in isotropic medium at a temperature , t=0.2 gev ( in figure 4 ) . as we know that the ratio is asymptotically related to the temperature of the medium so we have also plotted the quantity @xmath123 in the same figure . we observed that the fdt is almost satisfied in the non - relativistic limit of hq momentum but is violated as the hq momentum becomes more and more relativistic . this observation seems more plausible because fdt is satisfied only if a non - equilibrated degrees of freedom evolves in an ideal heat bath and undergoes through linear damping @xcite . our result is consistent with other calculations @xcite , where the kln factorization is employed to model the pre - equilibrium momentum space gluon distribution @xcite . , and @xmath124 ) at a medium temperature @xmath98 gev for ( a ) perpedicular ( @xmath125 ) , and ( b ) parallel ( @xmath126 ) case . ] , and @xmath124 ) at a medium temperature @xmath98 gev for ( a ) perpedicular ( @xmath125 ) , and ( b ) parallel ( @xmath126 ) case . ] as we discussed in the preamble that the system produced at the early stage of ultra - relativistic heavy ion collisions exhibits an anisotropy in the momentum space , thus we aim to explore the effect of anisotropy on the heavy quark evolution because heavy quarks are also produced at early stages of the collision . since the anisotropy introduces an angular dependence in the drag coefficient so we have calculated the coefficient for different values of anisotropy parameter for two cases : a ) when the partons move transverse to the direction of anisotropy ( @xmath125 ) in figure 5 a and b ) when the partons moves along the direction of anisotropy ( @xmath127 ) in figure 5 b. the immediate observation is that the drag coefficient always decreases with the anisotropy ( @xmath128 ) for both parallel and perpendicular alignment , which can be understood qualitatively : in the small anisotropic limit , the anisotropic distribution function for partons may be approximated as an isotropic distribution function by removing particles with a large momentum component along the direction of anisotropy , ( @xmath66 ) , which causes a reduction of the number of partons around a test heavy quark in a given phase - space point ( @xmath129 ) . as a result , while propagating in the medium , hq encountered less number of scatterings and hence the equilibration rate becomes smaller in anisotropic plasma , resulting a decrease in the drag coefficient . it can also be seen that if the temperature of the medium is increased then the ( negative ) correction due to anisotropy increases , as a result the coefficient decreases sharply for all values of hq momentum . another important observation is that the drag coefficient of hq in parallel alignment ( @xmath130 ) is always less than the perpendicular alignment ( @xmath131 ) . this is due to the fact that for parallel alignment the momentum of partons got effectively shifted towards higher momentum side ( @xmath132 ) thus a large chunk of higher momentum particles do not contribute to the scattering of partons with hq whereas for perpendicular alignment , the shift of partons to higher momentum side does not arise that much . similarly we can see from figs . 6 ( a ) and ( b ) that the diffusion coefficient also decreases due to the momentum space anisotropy . further , like drag coefficient , diffusion coefficient of hq also becomes smaller in parallel alignment than the perpendicular alignment . in conclusion , we have first revisited the propagation of charm quarks in a hot isotropic medium of quarks and gluons by its transport coefficients - drag and diffusion coefficients and then explore the dependencies of the coefficients on the charm quark momentum , the temperature of the medium and the regulator in the @xmath7-channel matrix element in the form of debye mass . we have understood the results through the connection of the coefficients with the equilibration rate from the statistical mechanics point of view . with these understanding from the isotropic medium we move on to a medium which exhibits a momentum anisotropy and calculated both drag and diffusion coefficients in an anisotropic medium . the important finding of our calculation is that both drag and diffusion coefficients of charm quarks get waned due to the momentum anisotropy , which may be created at the early stages of the relativistic collisions . moreover the anisotropy causes a direction dependent sizable modifications to both drag and diffusion , as a result the ( negative ) correction due to anisotropy , when the partons are moving parallel to the direction of anisotropy , is larger than when the partons are moving perpendicular to the direction of anisotropy . thus the study of drag and diffusion coefficients in anisotropic medium will open up further applications to the phenomenology of relativistic heavy ion collisions . pks and bkp is thankful for financial assistance from council of scientific and industrial research ( no . csr-656-phy ) , government of india . authors also acknowledge the fruitful discussion with s. das , r. rapp and h. van hees during the course of this work . 99 m. djordjevic , m. gyulassy , r. vogt , and s. wicks , phys . b * 632 * , 81 ( 2006 ) . n. armesto , m. cacciari , a. dainese , c. a. salgado , and u. a. wiedemann , phys . b * 637 * , 362 ( 2006 ) . v. greco , c. m. ko , and r. rapp , phys . b * 595 * , 202 ( 2004 ) . a. adare et al . 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the propagation of heavy quarks ( hqs ) in a medium was quite often modeled by the fokker - plank ( fp ) equation . since the transport coefficients , related to drag and diffusion processes are the main ingredients in the fp equation , the evolution of hqs is thus effectively controlled by them . at the initial stage of the relativistic heavy ion collisions , asymptotic weak - coupling causes the free - streaming motions of partons in the beam direction and the expansion in transverse directions are almost frozen , hence an anisotropy in the momentum space sets in . since hqs are too produced in the same time therefore the study of the effect of momentum anisotropy on the drag and diffusion coefficients becomes advertently desirable . in this article we have thus studied the drag and diffusion of hqs in the anisotropic medium and found that the presence of the anisotropy reduces both drag and diffusion coefficients . in addition , the anisotropy introduces an angular dependence to both the drag and diffusion coefficients , as a result both coefficients get inflated when the partons are moving transverse to the direction of anisotropy than parallel to the direction of anisotropy . + pacs numbers : 12.38.mh , 12.38.gc , 25.75.nq , 24.10.pa

This crawl of online resources of the 115th US Congress was performed on behalf of The United States National Archives & Records ||||| The first comprehensive study of CEO-to-worker pay reveals an extraordinary disparity – with the highest gap approaching 5,000 to 1 The first comprehensive study of the massive pay gap between the US executive suite and average workers has found that the average CEO-to-worker pay ratio has now reached 339 to 1, with the highest gap approaching 5,000 to 1. The study, titled Rewarding Or Hoarding?, was published on Wednesday by Minnesota’s Democratic US congressman Keith Ellison, and includes data on almost 14 million workers at 225 US companies with total annual revenues of $6.3tn. Just the summary makes for sober reading. In 188 of the 225 companies in the report’s database, a single chief executive’s pay could be used to pay more than 100 workers; the average worker at 219 of the 225 companies studied would need to work at least 45 years to earn what their CEO makes in one. I knew inequality was a great problem in our society but I didn’t understand quite how extreme it was Keith Ellison, congressman It also shows how some of the most extreme disparities in CEO-to-worker pay exist in industries that are considered consumer discretionary, such as fast food and retail, with a 977 to 1 disparity, one of the widest gaps. “Now we know why CEOs didn’t want this data released,” says Ellison, who championed the implementation of the pay ratio disclosure rule as it was written into the Dodd-Frank financial reform bill of 2010. “I knew inequality was a great problem in our society but I didn’t understand quite how extreme it was.” The requirements, long resisted by some of the largest US companies, simply tells companies to identify a median worker and then calculate how much the CEO makes in comparison to that person. But the requirement triggered years of prevarication as companies claimed the method of calculating CEO compensation and median employee compensation had not been well defined. Some claimed that including workers employed abroad, especially in developing countries, would make pay ratio data even more extreme than it would be if calculated only within the US. “If wealth is being concentrated into fewer and fewer hands, then obviously wealth is being dissipated from more and more people,” Ellison said. “We have people who are paying more half their income in rent, and we have whole school districts where poverty is erasing any opportunity for Americans to climb that ladder.” No CEO should earn 1,000 times more than a regular employee | Sarah Anderson Read more According to a recent Bloomberg analysis of 22 major world economies, the average CEO-worker pay gap in the US far outpaces that of other industrialized nations. The average US CEO makes more than four times his or her counterpart in the other countries analyzed. Ellison rejected claims from corporate America that executive suite compensation is a just reward for the skillful exercising of their business talents. “Truth is, they’re doing nothing except extracting value and wealth from hard working people because they have economic advantages.” “With all this extra money they have, it corrupts our politics absolutely,” he continues. “It concentrates markets and makes them less competitive.” Ellison has become a frequent target for criticism from the Trump administration, including from the president himself. Last week, Ellison, who also serves as deputy chair of the Democratic National Committee, appeared at a Minnesota May Day parade wearing a black T-shirt with the words “Yo no creo en fronteras”, or “I don’t believe in borders”. Trump described the slogan as an example of the US having “the worst immigration laws in the history of mankind”. Facebook Twitter Pinterest The fast food industry has one of the widest pay disparities between CEO and worker. Photograph: Lucy Nicholson/Reuters Companies singled out for criticism in the report include Marathon Petroleum, a gas station operator, whose CEO Gary Heminger took home an astonishing 935 times more pay than an average employee in 2017. Sarah Anderson, the policy director at Inequality.org, said the data that’s now coming out from corporate America could prove historic. “We’ve known for many years we have an extreme gap between CEO and worker pay but this report goes into detail about which companies are doing the most to contribute to inequality by having extreme gaps in pay scales.” Anderson’s advocacy group had previously identified at least five US firms where workers would have to work more than 1,000 years to catch up with their top bosses. The companies include the auto-parts maker Aptiv (CEO-worker pay ratio: 2,526 to 1), the temp agency Manpower (2,483 to 1), the amusement park owner Six Flags (1,920 to 1), Del Monte Produce (1,465 to 1), and the apparel maker VF (1,353 to 1). “We’re getting eye-opening data now because companies are now required to make disclosures for their global workforce,” she said. Ellison said the data remains imperfect, as companies are still able to exclude contracted workers from their reporting. He singled out Newmont Mining, which claims 30,000 workers and contractors on its website but only reported 12,500 to the SEC. 'Tax Amazon': Seattle passes plan for corporate wealth tax to fund housing Read more “What happened to the other workers? They’re missing some. But even then the CEO is making 114 times the average employee.” Ellison hopes that the issue is beginning to break out of the political echo-chamber and that changes are beginning to occur. The city of Portland, Oregon, for instance, recently imposed a 10% business tax surcharge on companies with top executives making more than 100 times what their median worker is paid – and a 20% surcharge on firms with pay gaps that stretch exceed 250 to 1. “We need to ban stock buy-backs, increase marginal tax rates, we need to make sure companies cant write huge bonuses. But we also need to increase the voice of workers. What’s going on in Portland is good. Taxes are part of any realistic solution. It’s not like this concentration and hoarding of wealth has no consequence. Everytime they acquire more, it means someone else gets less.” ||||| Equilar 100: Highest-Paid CEOs at the Largest Companies by Revenue April 11, 2018 Each year, the Equilar 100 examines CEO compensation at the largest companies by revenue to provide an early look at executive pay trends. The study includes companies that filed annual proxy statements before March 31, considered the “half-way” point in the annual proxy season. Thousands more public companies will file executive compensation data during the month of April, and the annual Equilar 200 study with The New York Times will be forthcoming in late May. That study will provide a comprehensive look at the largest pay packages provided to all public company chief executives in fiscal year 2017. The introductory page of this feature shows the Top 10 highest-paid CEOs at Equilar 100 companies. Below the highest-paid CEO table, there is a link to the full Equilar 100 in an interactive chart that allows you to sort by compensation and performance measurements. A summary of key highlights from the report follows on this page. Highest-Paid CEOs at Equilar 100 Companies EXECUTIVE NAME COMPANY (Ticker) TOTAL COMP. CHANGE IN PAY FY End Revenue ($MM) 1. Hock E. Tan Broadcom (AVGO) $103,211,163 318% $17,636 2. Brian Duperreault American International Group (AIG) $42,755,012 n/a $49,520 3. Mark V. Hurd Oracle (ORCL) $40,832,279 -1% $37,728 4. Safra A. Catz Oracle (ORCL) $40,729,965 -1% $37,728 5. Robert A. Iger Walt Disney (DIS) $36,283,680 -11% $55,137 6. Ian Read Pfizer (PFE) $26,165,138 54% $52,546 7. Indra K. Nooyi PepsiCo (PEP) $25,891,211 3% $63,525 8. Randall L. Stephenson AT&T; (T) $25,300,661 1% $160,546 9. Michael F. Neidorff Centene (CNC) $25,259,468 15% $48,382 10. Alex Gorsky Johnson & Johnson (JNJ) $22,843,420 8% $76,450 The full list of CEOs is on the following page in an interactive table. Click Here Key Trends and Takeaways Median pay again rose for Equilar 100 CEOs. Median pay for Equilar 100 CEOs overall was $15.7 million in fiscal year 2017, in comparison to $15.0 million for the CEOs on the previous year’s list*. On an individual level, Equilar 100 CEOs saw a 5% pay increase at the median in fiscal year 2017. By comparison, the median pay increase for CEOs on last year’s Equilar 100 list was 6%. The median CEO pay ratio for the Equilar 100 was 235:1. Among the 69 companies on the list reporting the ratio of CEO pay to that of a median employee, the median ratio was 235:1. Because the pay ratio disclosure was required for companies whose fiscal year began on or after January 1, 2017, 31 companies in the Equilar 100 were exempt from reporting this figure in their most recent proxy statements. The highest ratio was not correlated to the highest pay. Manpower Group, a provider of workplace solutions, reported the highest ratio among Equilar 100 companies at 2,483:1. Its CEO, Jonas Prising, was awarded $12.0 million in 2017, translating to the 76th highest-paid among Equilar 100 CEOs. Yet because the company’s 600,000 employees are mostly on temporary work assignments, the median pay among them was $4,828. Warren Buffett, with his annual compensation of $100,000, turned in the lowest CEO pay ratio at approximately 2:1. Though few in number, women CEOs are concentrated among the highest-paid. Of the eight women represented on this year’s Equilar 100 list, five were among the top 20 highest-paid. Safra Catz of Oracle, fourth on the highest-paid list, was awarded $40.7 million in 2017, essentially flat from the year before. Notably, the number of women CEOs in the Equilar 100 dropped in 2017 from nine to eight, one of whom was Meg Whitman, who has since left her position at Hewlett Packard Enterprise. Berkshire and Apple once again led in total revenue. Berkshire Hathaway was the largest company by revenue in the second straight Equilar 100 study, earning $242.1 billion in fiscal year 2017, an 8% gain from the previous year. Apple remained the only other company with more than $200 billion in revenue, increasing 6% to $229.2 billion in 2017. AT&T; had the third-largest revenue on the list with $160.5 billion. *Note: While many of the companies in the Equilar 100 are consistent from year to year, due to changes in revenue and floating filing dates the list is not the same every year. For information regarding the Equilar 100 and the underlying datasets, or to learn more about Equilar Research Services, please contact the Equilar research team at researchservices@equilar.com.

– Don’t cry for your busy CEO. A comprehensive survey of executive pay has found that the average CEO-to-median-worker pay ratio in the US has reached 339 to 1, reports the Guardian. Simply put, median workers at most of the companies surveyed would need to work 45 years to earn what the CEO makes in one year. This figure is higher than that of other industrialized countries, where CEOs make less, according to a Bloomberg analysis. Published by Minnesota Rep. Keith Ellison, the study looked at the earnings of nearly 14 million workers at 225 companies with total annual revenues of $6.3 trillion. Among the findings: In 188 of the 225 companies surveyed, the pay of the CEO could be used to pay more than 100 workers. The gaps are most apparent in the fast food and retail industries, which had a 977 to 1 ratio. The findings are consistent with another recent report by the compensation research firm Equilar. Equilar evaluated pay at the 100 largest public companies by revenue and found that in 2017 the median CEO pay package was about $15.7 million, its highest figure since Equilar first started analyzing pay in 2007, the Washington Post reported at the time. The biggest earner was Broadcom’s Hock Tan, who brought in a breathtaking $103.2 million. The pay disparity rankles Sarah Anderson, policy director at Inequality.org, who says it could be historic. “We’ve known for many years we have an extreme gap between CEO and worker pay," she tells the Guardian, "but this report goes into detail about which companies are doing the most to contribute to inequality by having extreme gaps in pay scales.”