bluuebunny/crossref_metadata_2025 huggingface dataset:
Rescue percutaneous coronary intervention for failed thrombolysis: results from a district general hospital
Authors: Balachandran K P , Miller J , Pell A C H , Vallance B D , Oldroyd K G
Published: July 2002

Objective

To assess the outcome of a policy of emergency percutaneous coronary intervention (PCI) in patients with acute myocardial infarction and electrocadiographic (ECG) evidence of failed reperfusion after thrombolysis.

Design

Observational study.

Setting

District general hospital.

Patients

A total of 109 consecutive patients with acute myocardial infarction who underwent emergency angiography and angioplasty for failed reperfusion diagnosed on the basis of standard ECG criteria.

Main outcome measures

In-hospital mortality; death, infarct territory reinfarction, and reintervention by PCI or coronary artery bypass graft (CABG) during follow up; in-lab resource utilisation.

Results

At initial angiography, 76 patients had Thrombolysis in Myocardial Infarction (TIMI) trial 0/1 flow and 33 had TIMI 2/3 flow. Fourteen patients were in cardiogenic shock. TIMI 3 flow was established or maintained in 93 patients (85%). Overall in-hospital mortality was 9%. It was 3% in non-shock patients, 50% in shocked patients, and 40% when the procedure was unsuccessful (TIMI 0/1 flow post-procedure). Over a mean follow up of 30 months (>12 months of follow up in all patients) there were 19 further events (one death, five reinfarctions, and 13 revascularisations (nine CABG and four PCI)). The cost of rescue PCI was not significantly higher than comparable elective interventions.

Conclusion

A policy of emergency angiography and PCI for failed reperfusion in acute myocardial infarction can be carried out in a hospital without on-site surgical backup with good medium term clinical outcomes.
Investigating competitive interactions from spatial patterns of trees in multispecies boreal forests: the random mortality hypothesis revisited
Authors: Little L R
Published: July 2002

Plant competition is expected to produce an overdispersed spatial pattern relative to the initial pattern of individuals. The spatial patterns of two boreal forest tree species, Populus tremuloides Michx. (trembling aspen) and Pinus banksiana Lamb. (jack pine), were examined for evidence of intraspecific and interspecific competition. Data consisting of species, position, and age of tree stems were obtained from a 21-year-old, 40 m × 30 m postfire area of boreal forest in northern Alberta, Canada. Tree stems were mapped and classified according to size (greater or less than 5 cm in diameter at ground height) and species. A variation on the random mortality hypothesis was used to detect overdispersed patterns indicative of competitive interactions. This was done by comparing the size of neighbouring stems with those expected when the size or "success" of a stem occurred randomly. The results showed roughly two scales of pattern. First, large seed-regenerating jack pine neighboured each other more often than expected, but jack pine and trembling aspen neighboured each other less than expected. Second, although the large jack pine appeared to be clustered as neighbours, they tended to associate at distances farther than expected. These results show little evidence of density-dependence patterns in the species at the site, and the interspecific association between jack pine and trembling aspen could be indicative of a heterogeneous habitat.Key words: triangulation, size variability, Pinus banksiana, Populus tremuloides, jack pine, trembling aspen.
Seawater tolerance and gene expression in two strains of Atlantic salmon smolts
Authors: Singer Thomas D , Clements Koreen M , Semple Jeffrey W , Schulte Patricia M , Bystriansky Jason S , Finstad Bengt , Fleming Ian A , McKinley R Scott
Published: July 2002

The seawater tolerance of Atlantic salmon (Salmo salar) smolts reared under identical hatchery conditions was assessed in two Norwegian strains: AquaGen and Imsa. Plasma ion levels were disrupted in both strains following seawater exposure, but these disruptions were more profound in the AquaGen fish. To investigate the mechanisms underlying these differences, we measured gill Na+,K+-adenosine triphosphatase (ATPase) activity and mRNA levels of Na+,K+-ATPase α-subunit and two isoforms of the cystic fibrosis transmembrane conductance regulator (CFTR). Gill Na+,K+-ATPase activity rose significantly in both strains following seawater exposure. Both Na+,K+-ATPase α-subunit and CFTR I mRNA levels were significantly elevated for the entire 2-week period following seawater exposure, whereas CFTR II levels were transiently elevated during the first 24 h only. There were no differences in enzyme activity or gene expression between strains, with the exception of CFTR II, which was significantly lower in the Imsa strain 2 weeks following seawater exposure. This suggests that although changes in mRNA and protein expression for these genes are associated with seawater transfer, they are not the basis of observed physiological differences between strains.
Molecular evolution of ribosomal intergenic spacers inOdontophrynus americanus2nand 4n(Amphibia: Anura)
Authors: Alvares Lúcia E , Polanco Carlos , Brison Olivier , Coutinho Luiz L , Ruiz Itamar R.G
Published: July 2002

Ribosomal intergenic spacers (IGSs) of Odontophrynus americanus 2n and 4n were cloned, restriction mapped, and partially sequenced. Three distinct regions, namely α, β, and δ, were identified in the IGSs. The α and β regions flanked the 28S and 18S rRNA genes, respectively, conserving an identical restriction pattern at each ploidy level. The δ region, located between α and β, was highly variable in size and restriction pattern, enclosing different BamHI subrepeats (B-SR), 87- to 530-bp-long. Sequence analysis showed that B-SRs were composed mainly of different arrangements of similar blocks of sequences. Another family of repetitive sequences was found in the δ region, clustered inside large BamHI fragments. These subrepeats are 189-bp-long and, although very similar in diploid and tetraploid IGSs, show a pattern of concerted evolution. A hypothetical functional role for the 189-bp repeats is discussed in view of their predicted secondary structure and presence of potential E2 binding sites inside diploid subrepeats. Although the same structural elements were present both in diploid and tetraploid IGSs, the higher level of repeatability of tetraploid IGSs suggests that common ancestor sequences have undergone several rounds of amplification after O. americanus polyploidy.Key words: Odontophrynus americanus, amphibian polyploidy, ribosomal DNA, intergenic spacer, IGS subrepeats.
Proteolytic release of membrane-bound endo-(1,4)-β-glucanase activity associated with cell wall softening inAchlya ambisexualis
Authors: Hill Terry W , Loprete Darlene M , Vu Kim N , Mokhtari Susan P. Bayat , Hardin L Vanessa
Published: July 2002

Branching and other cell wall softening events in fungi and oomycetes are thought to involve the activity of secreted enzymes, which are packaged in membrane vesicles and delivered to sites of cell expansion, there to work in a carefully regulated manner upon the structure of the wall. Here we demonstrate a latent endo-(1,4)-β-glucanase activity in a mixed membrane fraction of the oomycete Achlya ambisexualis, which can be released by cysteine proteases with an increase of apparent activity. In addition, a similar endogenous process is strongly inhibited by the cysteine protease inhibitor iodoacetamide, while inhibitors of other types of proteases have a much smaller effect. Detergent treatment of membranes releases two glucanases detectable by electrophoretic activity staining, with apparent molecular masses of about 164 and 35 kDa. Proteolysis produces several activity bands, with major species having apparent molecular masses of about 149, 133, 48, 35, and 25 kDa. The ca. 35- and 25-kDa bands migrate in parallel with glucanases secreted during wall softening in vivo. We propose that the initiation of wall softening in Achlya involves the proteolytic processing and solubilization of at least some secreted endoglucanases. We also propose that the solubilization component of this process functions not just to provide the enzymes with access to wall matrix substrates but also may provide a mechanism for the eventual termination of their biological function.Key words: apical growth, hyphal branching, proteases, cell walls, protein secretion.
Relationship between spruce beetle and tomentosus root disease: two natural disturbance agents of spruce
Authors: Lewis Kathy J , Lindgren B Staffan
Published: July 2002

This project investigated the interaction between tomentosus root disease of spruce, caused by Inonotus tomentosus (Fr.:Fr.) S. Teng, and spruce beetle (Dendroctonus rufipennis (Kirby)). Both organisms are important agents of mortality and volume loss in boreal and sub-boreal spruce forests of British Columbia. They also occur in similar stand types with respect to species composition and tree age. One study involved an intensive survey of 23 spruce stands, where trees were sampled for both beetle and root disease. Tree condition (dead standing, live, windthrown) was also recorded. Few stands showed a significant relationship between incidence of spruce beetle and incidence of root disease, regardless of tree condition. Observations indicated that beetles actually tended to avoid severely infected trees. A second study involved pheromone baiting of paired healthy and infected trees, and measurements of phloem thickness. Two sites were used, one with very high (epidemic) populations of beetles, and the second with low (endemic) levels. Spruce beetle attacks were more successful on infected trees compared with healthy trees only at the site with endemic levels of beetle. Collectively, the results indicate that tomentosus root disease helps to maintain endemic levels of spruce beetle, and disease incidence may be useful as a tool to identify areas that may have endemic populations of spruce beetle.
Can endocranial volume be used as an estimate of brain size in birds?
Authors: Iwaniuk Andrew N , Nelson John E
Published: July 2002

Endocranial volumes of vertebrate skulls and brain masses are often used interchangeably in comparative analyses of brain size. We test whether endocranial volume can be used as a reliable estimate of brain size in birds by comparing endocranial volumes with brain masses across 82 species using absolute values and with respect to body size. The results of paired tests across all 82 species and within two orders, Passeriformes and Psittaciformes, did not yield a significant difference between the two measures. These results were supported by correlational analyses that showed a significant positive relationship between endocranial volume and brain mass. Unpaired tests within short-tailed shearwaters (Puffinus tenuirostris) and paired tests within budgerigars (Melopsittacus undulatus) also yielded no significant differences between endocranial volume and brain mass. Thus, a combination of interspecific and intraspecific comparisons indicates that endocranial volume does provide a reliable estimate of brain size. Although this may enable more rapid collection of avian brain size data, endocranial volume should be used with caution because it cannot account for seasonal and age-related variation and cannot be used to measure differences in brain structure.
EXISTENCE AND UNIQUENESS OF THE INTEGRATED DENSITY OF STATES FOR SCHRÖDINGER OPERATORS WITH MAGNETIC FIELDS AND UNBOUNDED RANDOM POTENTIALS
Authors: HUPFER THOMAS , LESCHKE HAJO , MÜLLER PETER , WARZEL SIMONE
Published: July 2002

The object of the present study is the integrated density of states of a quantum particle in multi-dimensional Euclidean space which is characterized by a Schrödinger operator with a constant magnetic field and a random potential which may be unbounded from above and from below. For an ergodic random potential satisfying a simple moment condition, we give a detailed proof that the infinite-volume limits of spatial eigenvalue concentrations of finite-volume operators with different boundary conditions exist almost surely. Since all these limits are shown to coincide with the expectation of the trace of the spatially localized spectral family of the infinite-volume operator, the integrated density of states is almost surely non-random and independent of the chosen boundary condition. Our proof of the independence of the boundary condition builds on and generalizes certain results obtained by S. Doi, A. Iwatsuka and T. Mine (Math. Z. 237 (2001) 335) and S. Nakamura (J. Funct. Anal. 173 (2001) 136).
GAUSS CODES, QUANTUM GROUPS AND RIBBON HOPF ALGEBRAS
Authors: KAUFFMAN LOUIS H.
Published: July 2002

By relating the diagrammatic foundations of knot theory with the structure of abstract tensors, quantum groups and ribbon Hopf algebras, specific expressions are derived for quantum link invariants. These expressions, when applied to the case of finite dimensional unimodular ribbon Hopf algebras, give rise to invariants of 3-manifolds.
CONSTRUCTIVE MANY-BODY THEORY
Authors: FELDMAN JOEL , MAGNEN JACQUES , RIVASSEAU VINCENT , TRUBOWITZ EUGENE
Published: July 2002

We review the rôle played by renormalization, particle-number symmetry breaking, Goldstone bosons and the renormalization group in a mathematically rigorous construction of many-Fermion models at temperature zero.
DIFFUSIVE LIMIT OF ASYMMETRIC SIMPLE EXCLUSION
Authors: ESPOSITO R. , MARRA R. , YAU H. T.
Published: July 2002

We consider the asymmetric simple exclusion process on the lattice [Formula: see text] with periodic b.c. for d ≥ 3, in the diffusive space-time scaling with parameter ε. Assume the initial state is a product of Bernoulli measures with density of order ε, up to a fixed reference constant density θ. We prove that the density at time t is given to first order by θ − εm(x − ε−1vt, t) with v a uniform velocity depending on θ and the dynamics and m(z, t) satisfies the d-dimensional viscous Burgers equation. The diffusion matrix is given by a variational formula related to the Green-Kubo formula and it is strictly bigger than the diffusion matrix for the corresponding symmetric exclusion process.
LOCALIZATION FOR ONE DIMENSIONAL LONG RANGE RANDOM HAMILTONIANS
Authors: JAKŠIĆ VOJKAN , MOLCHANOV STANISLAV
Published: July 2002

We study spectral properties of random Schrödinger operators hω=h0+vω(n) on l2(Z) whose free part h0 is long range. We prove that the spectrum of hω is pure point for typical ω whenever the off-diagonal terms of h0 decay as |i-j|-γ for some γ>8.
STATIONARY DISCS AND GEOMETRY OF CR MANIFOLDS OF CODIMENSION TWO
Authors: SUKHOV A. , TUMANOV A.
Published: July 2002

We give a construction of stationary discs and the indicatrix for manifolds of higher codimension which is a partial analog of L. Lempert's theory of stationary discs for strictly convex hypersurfaces. This leads to new invariants of the CR structure in higher codimension linked with the contact structure of the conormal bundle.
AFFINE MAXIMAL TORUS FIBRATIONS OF A COMPACT LIE GROUP
Authors: SALVAI MARCOS
Published: July 2002

By a generalization of the method developed by Gluck and Warner to characterize the oriented great circle fibrations of the three-sphere, we give, for any compact connected semisimple Lie group G, a general procedure to obtain the continuous fibrations of G by Weyl-oriented affine maximal tori, find conditions for smoothness and provide infinite dimensional spaces of concrete examples.
ON S-HARDY–LITTLEWOOD HOMOGENEOUS SPACES
Authors: MORISHITA MASANORI , WATANABE TAKAO
Published: July 2002

We study the asymptotic distribution of S-integral points on affine homogeneous spaces in the light of the Hardy–Littlewood property introduced by Borovoi and Rudnick. We introduce the S-Hardy–Littlewood property for affine homogeneous spaces defined over an algebraic number field and a finite set S of places of the base field. We work with the adelic harmonic analysis on affine algebraic groups over a number field to determine the asymptotic density of S-integral points under congruence conditions. We give some new examples of strongly or relatively S-Hardy–Littlewood homogeneous spaces over number fields. As an application, we prove certain asymptotically uniform distribution property of integral points on an ellipsoid defined by a totally positive definite tenary quadratic form over a totally real number field.
GRÜNEISEN PARAMETER OF IONIC AND COVALENT CRYSTALS FOR LOW AND HIGH TEMPERATURES
Authors: ROY S. D. D. , RAMACHANDRAN K.
Published: July 2002

The Grüneisen parameter for covalent crystals is calculated by employing an angular force model with eight parameters and using a 6–12 potential [Lennard–Jones potential (L–J)] whereas for ionic crystals, it is calculated by employing the Daniel's method, which uses anisotropy factor tables f(s,t) of de Launay.
NONLINEAR SIGMA MODEL ON CONIFOLDS
Authors: PARTHASARATHY R. , VISWANATHAN K. S.
Published: July 2002

Explicit solutions to the conifold equations with complex dimension n = 3, 4 in terms of complex coordinates (fields) are employed to construct the Ricci-flat Kähler metrics on these manifolds. The Kähler two-forms are found to be closed. The complex realization of these conifold metrics are used in the construction of two-dimensional nonlinear sigma model with the conifolds as target spaces. The action for the sigma model is shown to be bounded from below. By a suitable choice of the "integration constants", arising in the solution of Ricci flatness requirement, the metric and the equations of motion are found to be non-singular. As the target space is Ricci-flat, the perturbative one-loop counterterms being absent, the model becomes topological. The inherent U(1) fiber over the base of the conifolds is shown to correspond to a gauge connection in the sigma model.

The same procedure is employed to construct the metric for the resolved conifold, in terms of complex coordinates and the action for a nonlinear sigma model with resolved conifold as target space, is found to have a minimum value, which is topological. The metric is expressed in terms of the six real coordinates and compared with earlier works. The harmonic function, which is the warp factor in Type II-B string theory, is obtained and the ten-dimensional warped metric has the AdS5 × X5 geometry.
BOUND STATES FROM REGGE TRAJECTORIES IN A SCALAR MODEL
Authors: WEBER A. , VIEYRA J. C. LÓPEZ , STEPHENS C. R. , DILCHER S. , HESS P. O.
Published: July 2002

The calculation of bound state properties using renormalization group techniques to compute the corresponding Regge trajectories is presented. In particular, we investigate the bound states in different charge sectors of a scalar theory with interaction ϕ†ϕχ. The resulting bound state spectrum is surprisingly rich. Where possible we compare and contrast with known results of the Bethe–Salpeter equation in the ladder approximation and, in the nonrelativistic limit, with the corresponding Schrödinger equation.
CONFORMAL ANOMALY IN (2,0) THEORY
Authors: TSEYTLIN A. A.
Published: July 2002

Using Ads7/CFT6 correspondence we compute a subleading O(N) term in the scale anomaly of (2,0) theory describing N coincident M5 branes. The total scale anomaly extrapolated to N=1 is argued to be the same as the anomaly of a single free (2,0) tensor multiplet. This contribution is based on ref. 1,2 where details and references may be found.
DYNAMICS AND THE SECOND PEAK: COLD DARK MATTER?
Authors: MCGAUGH STACY
Published: July 2002

The amplitude of the second peak in the angular spectrum of the cosmic microwave background radiation is constrained to be small by recent experiments like Boomerang. This is surprising in the context of the ΛCDM model, which predicted a large second peak. However, this result is expected if CDM does not exist. The observed shape of the power spectrum was accurately predicted (before the fact) by a model motivated by the surprising recent successes of the modified dynamics (MOND) hypothesized by Milgrom.
A NONEQUILIBRIUM STATISTICAL ENSEMBLE FORMALISM MaxEnt–NESOM: Basic Concepts, Construction, Application, Open Questions and Criticisms
Authors: LUZZI ROBERTO , VASCONCELLOS ÁUREA R. , RAMOS J. GALVÃO
Published: July 2002

We describe a particular approach for the construction of a nonequilibrium statistical ensemble formalism for the treatment of dissipative many-body systems. This is the so-called Nonequilibrium Statistical Operator Method, based on the seminal and fundamental ideas set forward by Boltzmann and Gibbs. The existing approaches can be unified under a unique variational principle, namely, MaxEnt, which we consider here. The main six basic steps that are at the foundations of the formalism are presented and the fundamental concepts are discussed. The associated nonlinear quantum kinetic theory and the accompanying Statistical Thermodynamics (the Informational Statistical Thermodynamics) are very briefly described. The corresponding response function theory for systems away from equilibrium allows to connected the theory with experiments, and some examples are summarized; there follows a good agreement between theory and experimental data in the cases in which the latter are presently available. We also present an overview of some conceptual questions and associated criticisms.
EXTENDED dx2-y2-WAVE GAP ANISOTROPY IN THREE MODEL THEORIES OF HIGH-TcSUPERCONDUCTIVITY
Authors: ANGILELLA G. G. N. , SUDBØ A. , PUCCI R.
Published: July 2002

Recent experimental results have evidenced a remarkable structure in the k-dependence of the d-wave superconducting order parameter of underdoped high-Tccuprates near a node. Here, it is pointed out that deviations from a simple d-wave superconducting spectrum induce corrections to the superconducting DOS and the low-T asymptotic behavior of various electronic properties in the superconducting state at intermediate energies. Such corrections depend on the theoretical scheme employed to describe the deviations.
HIGH-FIELD MAGNETOTRANSPORT OF EPITAXIAL LA2-XSRXCUO4 THIN FILMS IN THE REGIME OF LOW SR-DOPING
Authors: WECKHUYSEN L. , VANACKEN J. , WAGNER P. , RUAN K.-Q. , GORDON I. , MOSHCHALKOV V. V. , BRUYNSERAEDE Y.
Published: July 2002

High temperature superconductors have an unusual temperature (T) — doping (x) phase diagram, in which both antiferromagnetism and superconductivity occur. The spin gap and the superconducting gap are the two essential features of the T(x) plane which evolve with doping. A material allowing investigating the T-x plane in detail, from the underdoped (x<0.15) to the overdoped (x>0.15) regime, is the La 2- x Sr x CuO 4 superconductor. The temperature dependence of the resistivity strongly depends on the substitution ratio x. Overdoped films show metallic behavior, meaning that ρ(T) is linear above 100 K, while it saturates for lower temperatures. This saturation persists below Tc, when superconductivity is suppressed by sufficiently high pulsed magnetic fields. From the slightly overdoped (0.2<x) down to the strongly underdoped regime (x~0.03) we observe, instead of saturation, a ρ(T) dependence with logarithmic divergence in the field-induced normal state at T→0. For underdoped films (x<0.1) a superlinear ρ(T) behavior develops at intermediate temperatures (50 K <T<200 K ), indicating the opening of the spin gap.
COULOMB GAP IN THE QUANTUM HALL INSULATOR
Authors: BACKHAUS MICHAEL , HUCKESTEIN BODO
Published: July 2002

We calculate numerically the spectrum of disordered electrons in the lowest Landau level at filling factor 1/5 using the self-consistent Hartree-Fock approximation for systems containing up to 400 flux quanta. Special attention is paid to the correct treatment of the q=0 component of the Coulomb interaction. For sufficiently strong disorder, the system is an insulator at this filling factor. We observe numerically a Coulomb gap in the single-particle density of states (DOS). The DOS agrees quantitatively with the predictions for classical point charges.
THEORY OF BICRYSTAL c-AXIS TWIST JOSEPHSON JUNCTIONS
Authors: KLEMM RICHARD A. , SCHARNBERG KURT
Published: July 2002

We calculate the critical current density [Formula: see text] for Josephson tunneling between identical high temperature superconductors twisted an angle (ϕ0) about the c-axis. Regardless of the shape of the two-dimensional Fermi surface and for very general tunneling matrix elements, an order parameter (OP) with general d-wave symmetry leads to [Formula: see text]. This general result is inconsistent with the data of Li et al. on Bi2Sr2CaCu2O8+δ (Bi2212), which showed [Formula: see text] to be independent of ϕ0. If the momentum parallel to the barrier is conserved in the tunneling process, [Formula: see text] should vary substantially with the twist angle (ϕ0) when the tight-binding Fermi surface appropriate for Bi2212 is taken into account, even if the OP is completely isotropic. We quantify the degree of momentum non-conservation necessary to render [Formula: see text] constant within experimental error for a variety of pair states by interpolating between the coherent and incoherent limits using five specific models to describe the momentum dependence of the tunneling matrix element squared. From the data of Li et al., we conclude that the c-axis tunneling in Bi2212 must be very nearly incoherent, and that the OP must have a non-vanishing Fermi surface average for T≤Tc.
NANO-CRYSTAL ALLOY AND ALLOY-OXIDE COATINGS AND THEIR HIGH-TEMPERATURE CORROSION PROPERTIES
Authors: GAO WEI , LIU ZHENYU , LI ZHENGWEI , LI SEAN S. , GONG HAO
Published: July 2002

Nano-materials often possess special properties that materials with identical compositions but ordinary grain size do not have. This paper reports our work on the alloy and alloy-oxide nano-composite coatings. These coatings have special properties at elevated temperatures. Nano-crystal structures accelerate diffusion of certain types of elements, promoting selective oxidation of alloys, and forming desirable protective oxide films with low growth rate. The high-density grain boundaries also provide a network that holds the oxide scale tightly to the substrate, greatly improving the oxide scale spallation resistance. This paper also reports the processing techniques that are used to apply the nano-crstal alloy and alloy-oxide coatings, discuss the effects of mixed grain boundary and lattice diffusion, and studies the interface structures of oxide to metal substrate.
DENSITY OF STATES, CHARGE TRANSFER, AND OPTICAL PROPERTIES OF MAGNESIUM DIBORIDE
Authors: BAGAYOKO D. , ZHAO G. L.
Published: July 2002

We performed ab-initio, local density functional calculations of the electronic structure, charge transfer, and optical properties of MgB2, using the LCAO formalism. The Fermi level of MgB 2 cuts through relatively narrow electron bands which have a dominant contribution from B (2p) states. There is a substantial charge transfer from magnesium to boron atoms. We found the ionic formula for this material to be [Formula: see text]. A clearly metallic distribution of the electronic charge density in the plane of boron atoms is interwoven with a visibly covalent one in the direction perpendicular to this plane. The calculated optical conductivities from the direct inter-band transitions exhibit a strong anisotropy between σxx(ω) or σyy(ω) and σzz(ω). Due to our application of the BZW procedure, major peaks in the density of states above the Fermi level are at markedly higher energies (1–1.5 eV) than the results of previously reported ones. A similar pattern is followed by our findings for optical conductivities.
APPLICATIONS OF A HARD-CORE BOSE–HUBBARD MODEL TO WELL-DEFORMED NUCLEI
Authors: CHEN YUYAN , PAN FENG , STOITCHEVA G. S. , DRAAYER J. P.
Published: July 2002

An exactly solvable hard-core Bose–Hubbard model, which is equivalent to a mean-filed plus nearest-level pairing theory, for a description of well-deformed nuclei is used and applied to the actinide region. Binding energies and pairing excitation energies of 226–234 Th , 230–240 U , and 236–243 Pu isotopes are calculated and compared with the corresponding experimental values.
PHONON INDUCED METAL-INSULATOR PHASE TRANSITION IN A METAL
Authors: FAN J. D. , MALOZOVSKY Y. M.
Published: July 2002

It is attempted to clarify a historically existing misunderstanding that Cooper's pairing leads to superconductivity. It was found that the well-known Cooper instability in the presence of a quiescent Fermi sea for a given attractive interelectronic interaction mediated by any boson field, such as phonon, plasmon, paramagnon, etc. causes a metal-insulator other than superconducting transition. This is because the phase transition in this scenario leads to a vanishing density response and hence vanishing conductivity of the Fermi system when temperature approaches the transition temperature T c at which Cooper's instability occurs. In contrast, it is argued that the origin of a metal-superconductor transition is due to the repulsive Coulomb field. Nevertheless, the results from BCS theory regarding a gap in the electron spectrum for conventional superconductors remain valid only if the interaction in the BCS Hamiltonian is re-interpreted as an attractive interaction between an electron and a hole.
BEHAVIOR IN ELECTRIC FIELDS OF SIMPLE BIOLOGICAL MEMBRANES
Authors: HONCIUC MARIA , SLAVNICU ELENA
Published: July 2002

The latest studies in biophysics and biochemistry have revealed the major role that liquid crystals (LC) and related phenomena play in biological processes.

To account for a number of membrane mechanisms in view of the theoretical model developed by S. J. Singer, studies were carried out on mixtures of fatty acids (arachidic, lauric, butyric) and cholesterol in different weight percentages. Such mixtures may help one understand some mechanisms on which the operation of biological membranes relies. To this end, the way these mixtures behave in an electric field was studied.

Electric measurements were conducted from which the average time of electric relaxation (τ) and average electric permittivity (ε r ) were determined. Depending on cholesterol percentage, changes by more than one order of magnitude were found to occur in the electric relaxation time. The ratio between the various fatty acid components did not influence the average time τ in any significant manner. By contrast, the relative electric permittivity ε r was seen to decrease by at least one order of magnitude with raising the cholesterol percentage. The electric properties of such systems essentially depend on changing the amount of cholesterol in the system.
DEFECT TRANSFORMATIONS AT LOW TEMPERATURES IN AlxGa1-xAs COMPOUND SEMICONDUCTORS
Authors: STONERT ANNA , TUROS ANDRZEJ , NOWICKI LECH , BREEGER BERHARD , WENDLER ELKE , WESCH WERNER
Published: July 2002

Defect recovery at low tempetatures in N-ion implanted Al x Ga 1-x As (0 ≤ x ≤ 1) ternary compounds were studied. AlGaAs epitaxial layers were implanted at 51 K or 77 K with 150 KeV N-ions to fluences ranging from 4 × 1013 to 5 × 1015 at/cm2. Implanted crystals were analyzed in situ using the RBS/channeling technique. Successive measurements were performed during warming up of samples to room temperature. For low Al content, a large recovery stage between 200 K and 300 K was observed. For x > 0.5, a continuous damage recovery at the implantation temperatures due to the analyzing beam bombardment was observed. It leads to the substantial reduction of the principal recovery stage. For AlAs (x = 1) negligible defect recovery in the whole temperature range was noticed.
EPR AND OPTICAL ABSORPTION STUDIES OF Mn2+ IONS IN ALKALI BOROTELLURITE GLASSES
Authors: GIRI PRAKASH P. , MURALI A. , RAO J. L.
Published: July 2002

Electron paramagnetic resonance (EPR) and optical absorption spectra of Mn2+ ions in alkali borotellurite glass systems have been studied. The EPR spectra of all the glass samples exhibit three resonance signals at g ≈ 2.0, g ≈ 3.3 and g ≈ 4.3. A six line hyperfine structure has also been observed at g ≈ 2.0. The concentration and temperature dependence of EPR signals were studied for Mn2+ ions in potassium borotellurite glass samples. The zero-field splitting parameter D has been calculated for different alkali borotellurite glass samples from the intensities of the allowed hyperfine lines. The paramagnetic susceptibility was calculated from the EPR data at various temperatures and the Curie constant was calculated from the 1/χ versus T graph. The optical absorption spectrum exhibits a single broad band near 498 nm and this has been attributed to the spin-allowed 5Eg → 5T2g transition of Mn3+ ions in octahedral symmetry. The optical band gap energy (E opt ) and Urbach energy (Δ E) were calculated from their ultraviolet edges. The optical band gap energy varies between 3.38 and 3.61 eV and increases from Li to K glasses.
Synthesis and Characterization of A2CaCuO5(A=Nd, Sm)
Authors: Jeyabalan K. , Kaliyaperumal L. K. , Sekar A. , Srinivas J.
Published: July 2002

Synthesis and characterization of A 2 CaCuO 5( A=Nd, Sm ) system is reported. Powder X-ray diffraction analysis shows that the compounds crystallizes in an orthorhombic crystal systems and the unit cell parameters are found to be a=6.399(9)Å, b=7.218(8) Å and c=12.167(17) Å for Nd 2 CaCuO 5 and a=5.872(8) Å, b=7.457(3) Å and c=12.682(18) Å for Sm 2 CaCuO 5.
SYNCHRONIZATION STABILITY IN COUPLED OSCILLATOR ARRAYS: SOLUTION FOR ARBITRARY CONFIGURATIONS
Authors: PECORA LOU , CARROLL TOM , JOHNSON GREGG , MAR DOUG , FINK KENNETH S.
Published: July 2002

The stability of the state of motion in which a collection of coupled oscillators are in identical synchrony is often a primary and crucial issue. When synchronization stability is needed for many different configurations of the oscillators the problem can become computationally intense. In addition, there is often no general guidance on how to change a configuration to enhance or diminsh stability, depending on the requirements. We have recently introduced a concept called the Master Stability Function that is designed to accomplish two goals: (1) decrease the numerical load in calculating synchronization stability and (2) provide guidance in designing coupling configurations that conform to the stability required. In doing this, we develop a very general formulation of the identical synchronization problem, show that asymptotic results can be derived for very general cases, and demonstrate that simple oscillator configurations can probe the Master Stability Function.
BORDER-COLLISION BIFURCATIONS AND CHAOTIC OSCILLATIONS IN A PIECEWISE-SMOOTH DYNAMICAL SYSTEM
Authors: ZHUSUBALIYEV ZHANYBAI T. , SOUKHOTERIN EVGENIY A. , MOSEKILDE ERIK
Published: July 2002

Many problems of engineering and applied science result in the consideration of piecewise-smooth dynamical systems. Examples are relay and pulse-width control systems, impact oscillators, power converters, and various electronic circuits with piecewise-smooth characteristics. The subject of investigation in the present paper is the dynamical model of a constant voltage converter which represents a three-dimensional piecewise-smooth system of nonautonomous differential equations. A specific type of phenomena that arise in the dynamics of piecewise-smooth systems are the so-called border-collision bifurcations. The paper contains a detailed analysis of this type of bifurcational transition in the dynamics of the voltage converter, in particular, the merging and subsequent disappearance of cycles of different types, change of solution type, and period-doubling, -tripling, -quadrupling and -quintupling. We show that a denumerable set of unstable cycles can arise together with stable cycles at border-collision bifurcations. The characteristic peculiarities of border-collision bifurcational transitions in piecewise-smooth systems are described and we provide a comparison with some recent results.
ASYNCHRONOUS UPDATING RESTORES THE LAW OF LARGE NUMBERS IN GLOBALLY COUPLED SYSTEMS
Authors: SINHA SUDESHNA
Published: July 2002

It was observed in earlier studies, that the mean field of globally coupled maps evolving under synchronous updating rules violated the law of large numbers, and this remarkable result generated widespread research interest. In this work we demonstrate that incorporating increasing degrees of asynchronicity in the updating rules rapidly restores the statistical behavior of the mean field. This is clear from the decay of the mean square deviation of the mean field with respect to lattice size N, for varying degrees of asynchronicity, which shows 1/N behavior upto very large N even when the updating is far from fully asynchronous. This is also evidenced through increasing 1/f2 behavior regimes in the power spectrum of the mean field under increasing asynchronicity.
On the Existence of Finite Type Link Homotopy Invariants
Authors: MELLOR BLAKE , THURSTON DYLAN
Published: July 2002

We show that for links with at most 5 components, the only finite type homotopy invariants are products of the linking numbers. In contrast, we show that for links with at least 9 components, there must exist finite type homotopy invariants which are not products of the linking numbers. This corrects the errors of the first author in [11, 12].
ON LINKING SIGNATURE INVARIANTS OF SURFACE-KNOTS
Authors: KAWAUCHI AKIO
Published: July 2002

We show that the linking signature of a closed oriented 4-manifold with infinite cyclic first homology is twice the Rochlin invariant of an exact leaf with a spin support if such a leaf exists. In particular, the linking signature of a surface-knot in the 4-sphere is twice the Rochlin invariant of an exact leaf of an associated closed spin 4-manifold with infinite cyclic first homology. As an application, we characterize a difference between the spin structures on a homology quaternion space in terms of closed oriented 4-manifolds with infinite cyclic first homology, so that we can obtain examples showing that some different punctured embeddings into S4 produce different Rochlin invariants for some homology quaternion spaces.
A SMALL BUT NONZERO COSMOLOGICAL CONSTANT
Authors: NG Y. JACK , VAN DAM H.
Published: July 2002

Recent astrophysical observations seem to indicate that the cosmological constant is small but nonzero and positive. The old cosmological constant problem asks why it is so small; we must now ask, in addition, why it is nonzero (and is in the range found by recent observations), and why it is positive. In this essay, we try to kill these three metaphorical birds with one stone. That stone is the unimodular theory of gravity, which is the ordinary theory of gravity, except for the way the cosmological constant arises in the theory. We argue that the cosmological constant becomes dynamical, and eventually, in terms of the cosmic scale factor R(t), it takes the form Λ(t)=Λ(t0)(R(t0)/R(t))2, but not before the epoch corresponding to the redshift parameter z~1.
APPROXIMATE CANONICAL QUANTIZATION FOR COSMOLOGICAL MODELS
Authors: CAVAGLIÀ MARCO
Published: July 2002

In cosmology minisuperspace models are described by nonlinear time-reparametrization invariant systems with a finite number of degrees of freedom. Often these models are not explicitly integrable and cannot be quantized exactly. Having this in mind, we present a scheme for the (approximate) quantization of perturbed, nonintegrable, time-reparametrization invariant systems that uses (approximate) gauge invariant quantities. We apply the scheme to a couple of simple quantum cosmological models.
SELECTED TOPICS IN HIGH ENERGY SEMI-EXCLUSIVE ELECTRO-NUCLEAR REACTIONS
Authors: SARGSIAN MISAK M.
Published: July 2002

We review the present status of the theory of high energy reactions with semi-exclusive nucleon electro-production from nuclear targets. We demonstrate how the increase of transferred energies in these reactions opens a completely new window for study of the microscopic nuclear structure at small distances. The simplifications in theoretical descriptions associated with the increase in the energies are discussed. The theoretical framework for calculation of high energy nuclear reactions based on the effective Feynman diagram rules is described in detail. The result of this approach is the generalized eikonal approximation (GEA), which is reduced to the Glauber approximation when nucleon recoil is neglected. The method of GEA is demonstrated in the calculation of high energy electro-disintegration of the deuteron and A=3 targets. Subsequently, we generalize the obtained formulae for A>3 nuclei. The relation of GEA to the Glauber theory is analyzed. Then, based on the GEA framework we discuss some of the phenomena which can be studied in exclusive reactions: nuclear transparency and short-range correlations in nuclei. We illustrate how light-cone dynamics of high-energy scattering emerge naturally in high energy electro-nuclear reactions.
RESILIENCE AND CRITICAL STOCK SIZE IN A STOCHASTIC RECRUITMENT MODEL
Authors: GRASMAN JOHAN , HUISKES MARK J.
Published: July 2002

A stochastic model for fish recruitment is fitted to data after performing an age-structured stock assessment. The main aim is to investigate the relation between safe levels of spawning stock size and fish stock resilience. Resilience indicators, such as stock recovery time and the frequency that a stock is below a critical size, are computed by means of simulation using the fitted stochastic model. The stochastic element of the model describes the early life stage survival of the fish using a nonlinear stochastic Leslie type of matrix. From catch data and fishing mortality rates, the free parameters in the model are estimated by means of a maximum likelihood method. The performance of the maximum likelihood estimation method is tested by means of simulation. The method is applied to data of a halibut population (Hippoglossus stenolepis) in the Southeastern Bering Sea. It turns out that given the fluctuation in recruitment, data of at least 25 consecutive years are required.
PERIPHERAL NERVE REPAIR USING NON NEURAL SHEATHS AND CONDUITS
Authors: Peimer Clayton A. , Heffner Reid R. , Howard Craig S. , Czyrny James J. , Sherwin Frances S.
Published: July 2002

The purpose of this study was to evaluate and compare peripheral nerve regeneration following the use of alternative non neural materials to traditional direct repair techniques and autologous nerve graft. Autologous vein and synthetic polytetrafluoroethylene (PTFE) segments were used to repair standardized defects of the tibial nerve in rabbits. The materials served as sheaths for direct primary repairs and as conduits to bridge a gap in the nerve. Evaluations performed at five months revealed that direct primary repairs ensheathed by vein segments produced a significantly greater number of axons regenerating across the repair site, whereas PTFE, either as a sheath or conduit, failed to improve axonal regeneration. Also, vein conduits used to bridge nerve gaps was less effective than traditional nerve grafts.
Biomechanical Analysis of the Stress Force on Midcarpal Joint in Kienböck's Disease
Authors: Nakamura K. , Beppu M. , Matsushita K. , Arai T. , Ide T.
Published: July 2002

Two types of lunate were recognized in the midcarpal joint. Type I lunate has no facet articulation with the hamate, and Type II lunate has a facet articulation with the hamate. The purposes of this study are to estimate the biomechanical contribution of Type II lunate for Kienböck's disease, and to elucidate the change of the contact surface between the lunate and hamate during radial and ulnar deviation for both Type I and Type II. Twenty-four contralateral unaffected wrists with Kienböck's disease were used for the first purpose. The radiographic force analysis was performed with a modified two-dimensional rigid-body spring model computer-simulation technique. Six wrists of volunteers (3 of Type I and 3 of Type II lunates) were used for the second purpose. Dynamic examination on lunohamate joint was carried out using magnetic resonance imaging. The force distribution between the radius and Type II lunate was greater than that between the radius and Type I lunate statistically. Furthermore, the impingement of articular cartilages between Type II lunate and hamate was observed in ulnar deviation on dynamic study. These results suggest that Type II lunate was one of the anatomical risk factors for Kienböck's disease.
HISTORICAL VOLATILITY DISTRIBUTION IN GAUSSIAN AND GARCH(1,1) MODELS
Authors: MOLGEDEY LUTZ
Published: July 2002

On experimental data the historical volatility is usually calculated by averaging the local variance (or its generalizations) over a finite time window. Already in the case of a constant volatility in the Gaussian model the resulting historical volatility is non-Gaussian distributed. We will calculate historical volatility distributions in the Gaussian and GARCH(1,1) model for different time window sizes and compare them with those obtained from the S&P500 data [1].
Impact of Property Prices on Stock Prices in Hong Kong
Authors: Tse Raymond Y. C.
Published: July 2002

This paper studies the extent to which real estate prices impact common stock prices in Hong Kong. Real estate-related firms account for over 30 percent of Hong Kong's stock market capitalization. The real estate markets are therefore major determinants of changes in common stock prices. This study, using data during the 1974-1998 period, not only supports empirically that both unexpected changes in residential and office property prices are important determinants of the change in stock prices for Hong Kong, it also finds that the property and stock price series are cointegrated. Impulse response function based on an error-correction VAR model is used to examine the dynamic relationships between real estate and common stock prices.
PHENOMENOLOGICAL APPROACH TO PROFILE IMPACT OF SCIENTIFIC RESEARCH: CITATION MINING
Authors: DEL RIO J. A. , KOSTOFF R. N. , GARCIA E. O. , RAMIREZ A. M. , HUMENIK J. A.
Published: July 2002

In this paper we present a phenomenological approach to describe a complex systemcolon; scientific research impact through Citation Mining. The novel concept of Citation Mining, a combination of citation bibliometrics and text mining, is used for the phenomenological description. Citation Mining starts with a group of core papers whose impact is to be examined, retrieves the papers that cite these core papers, and then analyzes the bibliometrics characteristics of the citing papers as well as their linguistic and thematic characteristics. The Science Citation Index is used as the source database for the core of citing papers, since its citation-based structure enables the capability to perform citation studies easily. This paper presents illustrative examples in photovoltaics (applied research) and sandpile dynamics (basic research) to show the types of output products possible. Bibliometric profiling is performed over a number of the citing papers' record fields to offer different perspectives on the citing (user) community. Text mining is performed on the aggregate citing papers, to identify aggregate citing community themes, and to identify extra-discipline and applications themes. The photovoltaics applied research papers had of the order of hundreds of citations in aggregate. All of the citing papers ranged from applied research to applications, and their main themes were fully aligned with those of the aggregate cited papers. This seems to be the typical case with applied research. The sandpile dynamics basic research papers had hundreds of citations in aggregate. Most of the citing papers were also basic research whose main themes were aligned with those of the cited paper. This is typically the case with basic research. However, about twenty percent of the citing papers were research or development in other disciplines, or development within the same discipline. In addition, there was a four year lag time between publication and citation by the development papers.