bluuebunny/crossref_metadata_2025 huggingface dataset:
Distance to the convex hull of an orbit under the action of a compact Lie group
Authors: Holmes Randall R. , Tam Tin-Yau
Published: April 2009

For a real vector space V acted on by a group K and fixed x and y in V, we consider the problem of finding the minimum (respectively, maximum) distance, relative to a K-invariant convex function on V, between x and elements of the convex hull of the K-orbit of y. We solve this problem in the case where V is a Euclidean space and K is a finite reflection group acting on V. Then we use this result to obtain an analogous result in the case where K is a maximal compact subgroup of a reductive group G with adjoint action on the vector component ρ of a Cartan decomposition of Lie G. Our results generalize results of Li and Tsing and of Cheng concerning distances to the convex hulls of matrix orbits.
Lacunary sets for groups and hypergroups
Authors: Finet Catherine
Published: April 2009

In this paper, we generalize the classical F. and M. Riesz theorem to compact groups and compact commutative hypergroups. The group SU(2) of unitary matrices is also studied.
On Pascal ovals
Authors: Fernandes Olga
Published: April 2009

In this paper we prove that if an oval in a finite projective plane of order n ≡ 3 (mod 4) has the four point Pascal property and if each of its tangents and secants has the five point Pascal property, then the plane is Pappian and the oval is a conic.

We also establish results concerning Ostrom conics and ovals with the three point and four point Pascal properties.
Periodic and fixed point theorems in a quasi-metric space
Authors: Ćirić Ljubomir
Published: April 2009

General periodic and fixed point theorems are proved for a class of self maps of a quasi-metric space which satisfy the contractive definition (A) below. Two examples are presented to show that the class of mappings which satisfy (A) is indeed wider than a class of selfmaps which satisfy Caristi's contractive definition (C) below. Also a common fixed point theorem for a pair of maps which satisfy a contractive condition (D) below is established.
On the number of real roots of a random algebraic equation
Authors: Pratihari D. , Panda R. K. , Pattanaik B. P.
Published: April 2009

Let Nn(ω) be the number of real roots of the random algebraic equation Σnv = 0 avξv (ω)xv = 0, where the ξv(ω)'s are independent, identically distributed random variables belonging to the domain of attraction of the normal law with mean zero and P{ξv(ω) ≠ 0} > 0; also the av 's are nonzero real numbers such that (kn/tn) = 0(log n) where kn = max0≤v≤n |av| and tn = min0≤v≤n |av|. It is shown that for any sequence of positive constants (εn, n ≥ 0) satisfying εn → 0 and ε2nlog n → ∞ there is a positive constant μ so that for all n0 sufficiently large.
Minimal ideals in near-rings and localized distributivity conditions
Authors: Birkenmeier Gary , Heatherly Henry
Published: April 2009

LetB, S, andTbe subsets of a (left) near-ringRwithBandTnonempty. We sayBis (S, T)-distributiveifs(b1+b2)t=sb1t+sb2t, for eachs∈S,b1,2∈B,t∈T. Basic properties for this type of ‘localized distributivity’ condition are developed, examples are given, and applications are made in determining the structure of minimal ideals.Theorem. IfIis a minimal ideal ofRandIkis (Im,In)-distributive for somek,n≧ 1,m≧ 0, then eitherI2= 0 orIis a simple, nonnilpotent ring with every element ofIdistributive inR. Theorem. LetRkbe (Rm,Rn)-distributive, for somek,n≧ 1, m ≧ 0; ifRis semiprime or is a subdirect product of simple near-rings, thenRis a ring. Connections are established with near-rings which satisfy a permutation identity and with weakly distributive near-rings. IfR→A→ 0 is an exact sequence of near-rings, then conditions onAare given which will impose conditions on the minimal ideals ofR.
Full coactions on Hilbert C*-modules
Authors: Bui Huu Hung
Published: April 2009

We introduce a natural notion of full coactions of a locally compact group on a Hilbert C*-module, and associate each full coaction in a natural way to an ordinary coaction. We also introduce a natural notion of strong Morita equivalence of full coactions which is sufficient to ensure strong Morita equivalence of the corresponding crossed product C*-algebras.
Asymptotic properties of rooted 3-connected maps on surfaces
Authors: Bender Edward A. , Gao Zhicheng , Richmond L. Bruce , Wormald Nicholas C.
Published: April 2009

In this paper we obtain asymptotics for the number of rooted 3-connected maps on an arbitrary surface and use them to prove that almost all rooted 3-connected maps on any fixed surface have large edge-width and large face-width. It then follows from the result of Roberston and Vitray [10] that almost all rooted 3-connected maps on any fixed surface are minimum genus embeddings and their underlying graphs are uniquely embeddable on the surface.
The Appell transform and the semigroup property for temperatures
Authors: Kochneff Elizabeth , Sagher Yoram
Published: April 2009

We prove that if u(x, t) is a solution of the one dimensional heat equation and if A u(x, t) is its Appell transform, then u(x, t) has the semi-group (Huygens) property in a domain D if and only if A u(x, t) has the semi-group property in a dual region. We apply this result to simplify and extend some results of Rosenbloom and Widder.
Franel integrals of order four
Authors: McIntosh Richard J.
Published: April 2009

Let ((x)) =x−⌊x⌋−1/2 be the swatooth function. Ifa, b, cand e are positive integeral, then the integral or ((ax)) ((bx)) ((cx)) ((ex)) over the unit interval involves Apolstol's generalized Dedekind sums. By expressing this integral as a lattice-point sum we obtain an elementary method for its evaluation. We also give an elementary proof of the reciprocity law for the third generalized Dedekind sum.
On the component group of the automorphism group of a Lie group
Authors: Chen P. B. , Wu T. S.
Published: April 2009

LetGbe a Lie group,Gothe connected component ofGthat contains the identity, and AutGthe group of all topological automorphisms ofG. In the case whenG/Gois finite andGhas a faithful representation, we obtain a necessary and sufficient condition forGso that AutGhas finitely many components in terms of the maximal central torus inGo.
Holonomy and basic cohomology of foliations
Authors: Pang Peter Y.
Published: April 2009

In this paper, we consider the relationship between the cohomologies of the basic differential forms and the transverse holonomy groupoid of a foliation. Applications to minimal models are given.
Alexander polynomials of two-bridge knots
Authors: Nakanishi Yasutaka , Suketa Masaki
Published: April 2009

For two-bridge knots, the authors give necessary conditions on coefficients of Alexander polynomials.
Rates of convergence to normality for samples from a finite set of random variables
Authors: John R. D. , Robinson J.
Published: April 2009

Rates of convergence to normality ofO(N-½) are obtained for a standardized sum ofmrandom variables selected at random from a finite set ofNrandom variables in two cases. In the first case, the sum is randomly normed and the variables are not restricted to being independent. The second case is an alternative proof of a result due to von Bahr, which deals with independent variables. Both results derive from a rate obtained by Höglund in the case of sampling from a finite population.
Laguerre geometries and some connections to generalized quadrangles
Authors: Brown Matthew R.
Published: April 2009

A Laguerre plane is a geometry of points, lines and circles where three pairwise non-collinear points lie on a unique circle, any line and circle meet uniquely and finally, given a circle C and a point Q not on it for each point P on C there is a unique circle on Q and touching C at P. We generalise to a Laguerre geometry where three pairwise non-collinear points lie on a constant number of circles. Examples and conditions on the parameters of a Laguerre geometry are given.

A generalized quadrangle (GQ) is a point, line geometry in which for a non-incident point, line pair (P. m) there exists a unique point on m collinear with P. In certain cases we construct a Laguerre geometry from a GQ and conversely. Using Laguerre geometries we show that a GQ of order (s. s2) satisfying Property (G) at a pair of points is equivalent to a configuration of ovoids in three-dimensional projective space.
A note on Beukers' integral
Authors: Hata Masayoshi
Published: April 2009

The aim of this note is to give a sharp lower bound for rational approximations to ζ(2) = π2/6 by using a specific Beukers' integral. Indeed, we will show that π2 has an irrationality measure less than 6.3489, which improves the earlier result 7.325 announced by D. V. Chudnovsky and G. V. Chudnovsky.
Regular skew group rings
Authors: Alfaro Ricardo , Ara Pere , Río Angel Del
Published: April 2009

Let G be a group acting on a ring R. We study the problem of determining necessary and sufficient conditions in order that the skew group ring RG be von Neumann regular. Complete characterizations are given in some particular situations, including the case where all idempotents of R are central. For a regular ring R admitting a G-invariant pseudo-rank function N, with G finite, we obtain a necessary condition for RG being regular in terms of the induced action of G on the N-completion of R.
The quest for strong dualities
Authors: Clark David M. , Davey Brian A.
Published: April 2009

We give a revised and updated exposition of the theory of full dualities initiated by Clark, Davey, Krauss and Werner, introducing the (stronger) notion of a strong duality. All known full dualities turn out to be strong. A series of theorems which provide necessary and sufficient conditions for a strong duality to exist is proved. All full dualities in the literature can be obtained from these results and many new strong dualities can be derived. In particular, we show that within congruence distributive varieties every duality can be upgraded to a strong duality. Amongst the new strong dualities are the dualities of Davey, Priestley and Werner for the varieties of pseudocomplemented distributive lattices which are either strong as they stand or can easily be made strong by the addition of partial operations to the dual structures.
On almost-N-continuous functions
Authors: Konstadilaki-Savvopoulou Ch. , Reilly I. L.
Published: April 2009

Recently the class of almost-N-continuous functions between topological spaces has been defined. This paper continues the study of such functions, especially from the point of view of changing the topology on the codomain.
On p-groups whose maximal subgroups are isomorphic
Authors: Mann Avinoam
Published: April 2009

We give an improved bound for the order of a p-group enjoying the title property. We also point out relations between the upper central series of a p-group and of its maximal subgroups.
T-spaces by the Gottlieb groups and duality
Authors: Woo Moo Ha , Yoon Yeon Soo
Published: April 2009

It is shown that all the generalized Whitehead products vanish in X and all the components of XΣA have the same homotopy type when X is a T-space. It is also shown that any T-space is a G-space. The dual spaces of T-spaces are introduced and studied.
Characterization of upper semicontinuously integrable functions
Authors: Buczolich Zoltán
Published: April 2009

We show that for a Henstock-Kurzweil integrable functionffor every ∈ > 0 one can choose an upper semicontinuous gage function δ, used in the definition of the HK-integral if and only if |f| is bounded by a Baire 1 function. This answers a question raised by C. E. Weil.
The order-dual of a TRL group, I
Authors: Miller J. B.
Published: April 2009

Conditions are found for several intrinsically defined partial orders on b, the vector space of order-bounded additive functionals on a commutative pogroup, to have Riesz interpolation properties, and to make b a TRL group.
Lattices of zero-sets
Authors: Broverman S.
Published: April 2009

Characterizations are obtained of those lattices that are isomorphic to the lattice of zero-sets of the following types of Tychonoff spaces: (i) compact (Hausdorff), (ii) Lindelöf, (iii) realcompact and normal, (iv) realcompact.
Iterative criteria for bounds on the growth of positive solutions of a delay differential equation
Authors: Terry Raymond D.
Published: April 2009

Following Terry (Pacific J. Math. 52 (1974), 269–282), the positive solutions of eauqtion (E): are classified according to types Bj. We denote A neccessary condition is given for a Bk-solution y(t) of (E) to satisfy y2k(t) ≥ m(t) > 0. In the case m(t) = C > 0, we obtain a sufficient condition for all solutions of (E) to be oscillatory.
Extensions of strict partial orders in N-Groups
Authors: Prabhakara Rao K. B.
Published: April 2009

An attempt is made to extend the theory of extensions of partial orders in groups to strict partially ordered N-groups. Necessary and sufficient conditions, for a strict partial order of an N-group to have a strict full extension, and for a strict partial order of an N-group to be an intersection of strict full orders, are obtained when the partially ordered near-ring N and the N-group G satisfy the condition (− x) n = − xn for all elements x in G and positive elements n in N.
On a class of inequalities
Authors: Rennie B. C.
Published: April 2009

First consider some familiar results, the inequality of the arithmetic and geometric mean is: Kantorovich's inequality (reference [1]) asserts that if 0 < A ≦f(x) ≦ B then: The Cauchy-Schwarz inequality is: This paper discusses a certain class of inequalities which includes the three above. Three theorems are proved which apply to any inequality of this class; then follow some examples. They are mainly to show how the general theory helps in the finding of inequalities, but the result of Example 1 seems worth reporting for its own sake.
Some general results on random walks, with genetic applications
Authors: Moran P. A. P.
Published: April 2009

Consider a random Markovian process in which the state of the system is defined by a random variable which can take the finite set of valuesi=0, 1, …,N, and which is such that transition can only occur from any state i to the two nearest statesi+1. This restriction brings about an essential simplification of the theory for the basic reason that in order for the system to move fromito statej(i<jsay) it must first move toi+1, theni+2 and so on until it reachesj. From this it follows that the first passage distribution fromitojis the convolution of the first passage distributions fromitoi+l,i+l toi+2,…,j—l tojeach of which is comparatively easy to find.
Representation formulas for entire functions of exponential type and generalized bernoulli polynomials
Authors: Frappier C.
Published: April 2009

We introduce a sequence of polynomials which are extensions of the classic Bernoulli polynomials. This generalization is obtained by using the Bessel functions of the first kind. We use these polynomials to evaluate explicitly a general class of series containing an entire function of exponential type.
On mixture representation of the Linnik density
Authors: Erdoğan Burak , Ostrovskii I. V.
Published: April 2009

Let pα,θ be the Linnik density, that is, the probability density with the characteristic function . The following problem is studied: Let (α θ), (β, ϑ) be two point of PD. When is it possible to represent β,ϑ as a scale mixture of pαθ? A subset of the admissible pairs (α, θ), (β, ϑ) is described.
Dual symmetric inverse monoids and representation theory
Authors: Fitzgerald D. G. , Leech Jonathan
Published: April 2009

There is a substantial theory (modelled on permutation representations of groups) of representations of an inverse semigroup S in a symmetric inverse monoid Ix, that is, a monoid of partial one-to-one selfmaps of a set X. The present paper describes the structure of a categorical dual Ix* to the symmetric inverse monoid and discusses representations of an inverse semigroup in this dual symmetric inverse monoid. It is shown how a representation of S by (full) selfmaps of a set X leads to dual pairs of representations in Ix and Ix*, and how a number of known representations arise as one or the other of these pairs. Conditions on S are described which ensure that representations of S preserve such infima or suprema as exist in the natural order of S. The categorical treatment allows the construction, from standard functors, of representations of S in certain other inverse algebras (that is, inverse monoids in which all finite infima exist). The paper concludes by distinguishing two subclasses of inverse algebras on the basis of their embedding properties.
A minimum condition and some realted fixed-point theorems
Authors: Jachymski Jacek R. , Stein James D.
Published: April 2009

The classic Banach Contraction Principle assumes that the self-map is a contraction. Rather than requiring that a single operator be a contraction, we weaken this hypothesis by considering a minimum involving a set of iterates of that operator. This idea is a central motif for many of the results of this paper, in which we also study how this weakended hypothesis may be applied in Caristi's theorem, and how combinatorial arguments may be used in proving fixed-point theorems.
Integral means on radially weighted spaces of analytic functions
Authors: Andersson Mats Erik
Published: April 2009

Hilbert spaces of analytic functions generated by rotationally symmetric measures on disks and annuli are studied. A domination relation between function norm and weighted sums of integral means on circles is developed. The function norm and the weighted sum take the same value for a specified class of polynomials. This class can be varied according to two parameters. Parts of the construction carry over to other Banach spaces of analytic of harmonic functions. Counterexamples illuminating properties of the complex method of interpolation appear as a byproduct.
Product and Markov measures of type III
Authors: Dooley Anthony H. , Klemeš Ivo , Quas Anthony N.
Published: April 2009

We give some explicit constructions of type III product measures with various properties, resolving some conjectures of Brown, Dooley and Lake. We also define a family of Markov odometers of type III0 and show that the associated flow is approximately transitive.
The Politics of Muslims in America
Authors: Jalalzai Farida
Published: April 2009

This article analyzes political participation and the attitudes of Muslim-Americans. Assessing national patterns, the first part highlights several regression models, discerning the impact of race/ethnicity, gender, foreign born status, age, and education on political activity and attitudes. I also compare changes in voting patterns among respondents between the 2000 and 2004 elections. The second half is based on in-depth interviews of Muslims from St. Louis, Missouri, probing more directly particular shifts in views and participation since September 11. Among the national sample, South Asians and Middle Easterners largely supported Republican George W. Bush in 2000, while African-Americans voted for Democrat Al Gore. However, by 2004, race and ethnicity were no longer statistically significant factors dividing the Muslim vote; instead, support largely went to Democrat John Kerry. Changes in voting patterns between 2000 and 2004 were also evident in the St. Louis sample of South Asians and Middle Easterners. They generally cited unfavorable views of Muslim treatment both at home and abroad since the War on Terror began as major reasons for these changes. Partisan and voting shifts were not evident among African-Americans, who have been consistent Democrats. However, many African-Americans in addition to Middle Easterners and South Asians reported heightened interest in politics and similar changes since September 11. Only Bosnians, who are relatively new to the United States, report few changes. This is largely because they have yet to develop firm political identities. Among both samples, Muslim-Americans generally exhibit high rates of participation in various political activities, many reporting increasing interest and involvement since September 11. Therefore, regardless of the hardships they may currently feel, Muslim-Americans are not hiding in the shadows but are fully participating in the political sphere.
Quantification of the gravity wave forcing of the migrating diurnal tide in a gravity wave–resolving general circulation model
Authors: Watanabe Shingo , Miyahara Saburo
Published: April 2009

The interaction of gravity waves (GWs) and the migrating diurnal tide are studied in a GW‐resolving general circulation model (GCM) by calculating the tidal components of zonal wind accelerations and equivalent Rayleigh friction due to tidal induced GW dissipation. Two 15‐day periods for perpetual equinoctial and solstice simulations are analyzed, which are performed with the Japanese Atmospheric General circulation model for Upper Atmosphere Research (JAGUAR) high‐resolution GCM. The model can directly simulate GWs with horizontal wavelengths greater than about 190 km, and, thus reproduce the general features of the mean winds and temperatures from the surface to the mesosphere and lower thermosphere (MLT). The amplitudes of the migrating diurnal tide are successfully simulated during both seasons, and the tidal winds affect the altitudes of GW dissipation in the low‐latitude MLT. The tidal component of GW forcing has maximal values of about 15 m s−1 d−1 near the maximal vertical shears of the tidal winds and generally works to shorten the vertical wavelength of the migrating diurnal tide. The phase relationship between the tidal winds and the tidal induced GW forcing is not exactly 90° out of phase, causing amplification/suppression of the tide. The GW forcing amplifies the migrating diurnal tide during the equinox, while during the solstice, it suppresses the tidal winds in the upper mesosphere of both hemispheres. This difference in behavior can be attributed to a seasonal variation of the mean zonal winds, because combination of the mean and tidal winds affects the altitudes of GW dissipation.
Inhibition of brush border sucrase by polyphenols in mouse intestine
Authors: Gupta Shiffalli , Mahmood Safrun , Khan Rizwan H. , Mahmood Akhtar
Published: April 2009

The interactions of gallic acid and tannic acid with purified brush border sucrase (EC 3.2.1.48) from mouse intestine have been studied. These findings indicate that both gallic acid and tannic acid inhibit sucrase activity, which is pH dependent. Kinetic analysis revealed that enzyme inhibition by gallic acid is a pure V effect at pH 5.0, which changes to mixed type at pH 7.2, and pure K effect at pH 8.5. In contrast, sucrase inhibition by tannic acid was a pure K effect at acidic pH and uncompetitive type in the alkaline pH range. Far-CD spectroscopic analysis revealed an increase in the helicity of the enzyme at acidic pH in the presence of tannic acid but no change at alkaline pH. Fluorescence spectra revealed a red shift in λmax of the enzyme, suggesting that tryptophan residues come to a more hydrophilic environment in the presence of polyphenols. These findings suggest that inhibition of mice sucrase by polyphenols is pH dependent, and is associated with conformational modifications of the enzyme.
Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al/Ni multilayers
Authors: Knepper Robert , Snyder Murray R. , Fritz Greg , Fisher Kaitlynn , Knio Omar M. , Weihs Timothy P.
Published: April 2009

Self-propagating reactions in Al/Ni nanostructured multilayer foils are examined both experimentally and computationally to determine the impact of variations in reactant spacing on reaction properties. Heats of reaction and reaction velocities have been characterized as a function of average bilayer spacing for sputter-deposited, single-bilayer foils (having a uniform bilayer spacing) and for dual-bilayer foils (having two different bilayer spacings that are labeled thick and thin). In the latter case, the spatial distribution of the thick and thin bilayers is found to have a significant effect on reaction velocity, with coarse distributions leading to much higher reaction velocities than fine distributions. Numerical simulations of reaction velocity match experimental data well for most spatial distributions, with the exception of very coarse distributions or distributions containing very small bilayer spacings. A simple model based on thermal diffusivities and reaction velocities is proposed to predict when the spatial distribution of thick and thin bilayers becomes coarse enough to affect reaction velocity. This combination of experiment and simulation will allow for more effective design and prediction of reaction velocities in both sputter-deposited and mechanically processed reactive materials with variable reactant spacings.
Effects of dielectric barrier discharges on silicon surfaces: Surface roughness, cleaning, and oxidation
Authors: Michel B. , Giza M. , Krumrey M. , Eichler M. , Grundmeier G. , Klages C.-P.
Published: April 2009

Silicon wafers were exposed to a dielectric barrier discharge (DBD) at atmospheric pressure, which was ignited by applying a high voltage (>12 kV peak voltage) to a small gap (dg=300 μm) above the wafer surface in an oxygen process gas atmosphere. The effect of the DBD on H-terminated silicon and native silicon oxide surfaces was investigated in situ and ex situ by means of Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy (XPS). The influence of the treatment on surface roughness was studied by atomic force microscopy. In order to determine the thickness of the newly formed oxide under DBD influence, the method of calculating the oxide thickness from the Si 2p peak ratio in the XPS spectrum, which has so far been described for thermal oxides only, was adopted with x-ray reflectometry calibration samples. Additionally, infrared spectroscopy and spectroscopic ellipsometry were used to verify the XPS measurements. The calculated thickness values can be fitted with the growth law d=d0 ln[(t/τ)+k], with d being the oxide thickness, grown during DBD exposure time t. Oxide thicknesses of more than 3 nm could be achieved within 350 s DBD exposure time. Our analysis of infrared spectra, XPS, and ellipsometry leads us to conclude that the newly formed oxide is porous with a pore fraction of roughly 10%.
Cumulants and the moment algebra: Tools for analyzing weak measurements
Authors: Åberg Johan , Mitchison Graeme
Published: April 2009

Recently it has been shown that cumulants significantly simplify the analysis of multipartite weak measurements. Here we consider the mathematical structure that underlies this and find that it can be formulated in terms of what we call the moment algebra. Apart from resulting in simpler proofs, the flexibility of this structure allows generalizations of the original results to a number of weak measurement scenarios, including one where the weakly interacting pointers reach thermal equilibrium with the probed system.
Investigation of iron impurity gettering at dislocations in a SiGe/Si heterostructure
Authors: Lu Jinggang , Yu Xuegong , Park Yongkook , Rozgonyi George
Published: April 2009

This article examined the electrical activities of dislocations in a SiGe/Si heterostructure by deep level transient spectroscopy (DLTS) after iron contamination and phosphorous diffusion gettering. DLTS of iron contaminated samples revealed a peak at 210 K, which was assigned to individual iron atoms or very small (<2 nm) precipitates decorated along dislocations, considering that the iron contamination annealing was terminated by quenching and transmission electron microscopy did not reveal any precipitate at dislocations. Arrhenius plot of the 210 K peak yielded a hole capture cross section of 2.4×10−14 cm2 and an energy level of 0.42 eV above the valance band. The relatively large hole capture cross section indicates strong interactions between iron-related deep levels and the dislocation shallow bands. DLTS of the iron contaminated sample revealed that 6×1014 cm−3 of boron can more effectively trap interstitial iron at room temperatures than the strain field/defect sites at 107–108 cm−2 dislocations. Phosphorous diffusion experiments revealed that the gettering efficiency of iron impurities depends on the dislocation density. For regions of high dislocation density, phosphorous diffusion cannot remove all iron impurities decorated at dislocations, suggesting a strong binding of iron impurities at dislocation core defects.
Doppler-shifted cyclotron resonance of fast ions with circularly polarized shear Alfvén waves
Authors: Zhang Yang , Heidbrink W. W. , Zhou Shu , Boehmer H. , McWilliams R. , Carter T. A. , Vincena S. , Lilley M. K.
Published: April 2009

The Doppler-shifted cyclotron resonance between fast ions and shear Alfvén waves (SAWs) has been experimentally investigated with a test-particle fast-ion (Li+) beam launched in the helium plasma of the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)]. Left- or right-hand circularly polarized SAWs are launched by an antenna with four current channels. A collimated fast-ion energy analyzer characterizes the resonance by measuring the nonclassical spreading of the averaged beam signal. Left-hand circularly polarized SAWs resonate with the fast ions but right-hand circularly polarized SAWs do not. The measured fast-ion profiles are compared with simulations by a Monte Carlo Lorentz code that uses the measured wave field data.
Substrate emitting index coupled quantum cascade lasers using biperiodic top metal grating
Authors: Maisons G. , Carras M. , Garcia M. , Parillaud O. , Simozrag B. , Marcadet X. , De Rossi A.
Published: April 2009

We report on the design and experimental demonstration of a specific metal grating profile that enables a substrate emission of a quantum cascade laser. A low loss, index coupled, and horizontal cavity surface emitting laser (HCSEL) design is proposed, which is very robust against technological spreads. The detailed analysis of the metallic top grating is performed, enabling the laser still to operate as a distributed feedback laser while emitting from the substrate. Following this concept, HCSEL with InP cladding layers and InGaAs/AlInAs active regions have been fabricated. Room temperature HCSEL emitting at 5.65 μm with a low beam divergence is demonstrated.
Poloidal mode structure of long-distance correlation of fluctuations under strong E×B shear in the torsatron TJ-K
Authors: Manz P. , Ramisch M. , Stroth U.
Published: April 2009

Long-distance correlations of density and potential fluctuations are investigated on the poloidal circumference of flux surface in the TJ-K plasmas. Shear flow as induced by biasing causes a strong increase in the long-distance correlation of potential and density fluctuations. In the potential fluctuations, zonal-flow-like modes are excited. The density long-distance correlation is dominated by an m=3 mode. As a new feature a coherency analysis reveals also the existence of m=0 density fluctuations. As an explanation, background profile fluctuations or a turbulent zonal density drive are proposed.
Seeding magnetic fields for laser-driven flux compression in high-energy-density plasmas
Authors: Gotchev O. V. , Knauer J. P. , Chang P. Y. , Jang N. W. , Shoup M. J. , Meyerhofer D. D. , Betti R.
Published: April 2009

A compact, self-contained magnetic-seed-field generator (5 to 16 T) is the enabling technology for a novel laser-driven flux-compression scheme in laser-driven targets. A magnetized target is directly irradiated by a kilojoule or megajoule laser to compress the preseeded magnetic field to thousands of teslas. A fast (300 ns), 80 kA current pulse delivered by a portable pulsed-power system is discharged into a low-mass coil that surrounds the laser target. A >15 T target field has been demonstrated using a <100 J capacitor bank, a laser-triggered switch, and a low-impedance (<1 Ω) strip line. The device has been integrated into a series of magnetic-flux-compression experiments on the 60 beam, 30 kJ OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The initial application is a novel magneto-inertial fusion approach [O. V. Gotchev et al., J. Fusion Energy 27, 25 (2008)] to inertial confinement fusion (ICF), where the amplified magnetic field can inhibit thermal conduction losses from the hot spot of a compressed target. This can lead to the ignition of massive shells imploded with low velocity—a way of reaching higher gains than is possible with conventional ICF.
Virtual-photon-induced quantum phase gates for two distant atoms trapped in separate cavities
Authors: Zheng Shi-Biao
Published: April 2009

We propose a scheme for implementing quantum gates for two atoms trapped in distant cavities connected by an optical fiber. The effective long-distance coupling between the two distributed qubits is achieved without excitation and transportation of photons through the optical fiber. Since the cavity modes and fiber mode are never populated and the atoms undergo no transitions, the gate operation is insensitive to the decoherence effect when the thermal photons in the environment are negligible. The scheme opens promising perspectives for networking quantum information processors and implementing distributed and scalable quantum computation.
The effects of hCG and growth factors on in vitro nuclear maturation of dog oocytes obtained during anoestrus
Authors: Alhaider A. K. , Watson P. F.
Published: April 2009

The effects of human chorionic gonadotrophin (hCG) and a combination of growth factors on the developmental competence of canine oocytes during in vitro maturation was examined. Oocytes recovered from domestic dog ovaries at routine ovariectomy were cultured in a basic tissue culture medium with 0.3% BSA, 7 μg mL–1 progesterone and antibiotics. After the appropriate culture periods (up to 96 h), they were fixed and labelled by double-antibody immunofluorescence for tubulin and with propidium iodide for chromatin. Human chorionic gonadotrophin increased the proportion of oocytes resuming meiosis and reduced the degeneration rate. Supplementing with hCG in declining concentrations was of no superior benefit but the presence of a combination of growth factors (growth hormone, insulin-like growth factor-1, transforming growth factor-α and fibroblast growth factor) improved both the resumption of meiosis and the degeneration rate. No particular synergisms between pairs of growth factors could be demonstrated. Human chorionic gonadotrophin and growth factors together gave poorer results, implying that hCG inhibited the beneficial effects of the growth factors. A growth factor combination is the present most successful treatment, with 49% of total oocytes (inclusive of degenerated) recovered from anoestrous bitches at MI or MII by 96 h of culture. This is the highest result so far demonstrated for cultured dog oocytes.
Ovarian imaging in the mouse using ultrasound biomicroscopy (UBM): a validation study
Authors: Mircea Carmen N. , Lujan Marla E. , Jaiswal Rajesh S. , Singh Jaswant , Adams Gregg P. , Pierson Roger A.
Published: April 2009

The mouse is a well accepted model for studies of human reproduction despite little being known about follicle dynamics in this species. Longitudinal studies of mouse folliculogenesis have been hampered by the lack of an appropriate imaging tool. Ultrasound biomicroscopy (UBM) may overcome this obstacle as it confers near-microscopic resolution through the use of high-frequency ultrasound waves. The objective of the present study was to determine whether UBM could be used to count and measure ovarian follicles and corpora lutea (CL) reliably in mice. Ovaries of 25 adult CD-1 mice were imaged using a 55-MHz transducer and then excised and processed for histology. Follicles and CL were counted and measured from digitally stored UBM cine-loops and photographed histological sections. Differences between techniques were assessed by Bland-Altman agreement analyses. Follicle counts yielded by the two techniques varied by only ± 1 follicle when follicles ranged between 300 and 499 μm. Perfect agreement among counts was evident when follicles were >500 μm. The total number of CL was accurately estimated using UBM; however, the number of 350–699 μm CL was underestimated and the number of CL ≥700 μm was overestimated. In conclusion, UBM can be used reliably to count and measure follicles in mice.
Non-competitive androgen receptor inhibition in vitro and in vivo
Authors: Jones Jeremy O. , Bolton Eric C. , Huang Yong , Feau Clementine , Guy R. Kiplin , Yamamoto Keith R. , Hann Byron , Diamond Marc I.
Published: April 2009

Androgen receptor (AR) inhibitors are used to treat multiple human diseases, including hirsutism, benign prostatic hypertrophy, and prostate cancer, but all available anti-androgens target only ligand binding, either by reduction of available hormone or by competitive antagonism. New strategies are needed, and could have an important impact on therapy. One approach could be to target other cellular mechanisms required for receptor activation. In prior work, we used a cell-based assay of AR conformation change to identify non-ligand inhibitors of AR activity. Here, we characterize 2 compounds identified in this screen: pyrvinium pamoate, a Food and Drug Administration-approved drug, and harmol hydrochloride, a natural product. Each compound functions by a unique, non-competitive mechanism and synergizes with competitive antagonists to disrupt AR activity. Harmol blocks DNA occupancy by AR, whereas pyrvinium does not. Pyrvinium inhibits AR-dependent gene expression in the prostate gland in vivo, and induces prostate atrophy. These results highlight new therapeutic strategies to inhibit AR activity.
A general quantitative theory of forest structure and dynamics
Authors: West Geoffrey B. , Enquist Brian J. , Brown James H.
Published: April 2009

We present the first part of a quantitative theory for the structure and dynamics of forests at demographic and resource steady state. The theory uses allometric scaling relations, based on metabolism and biomechanics, to quantify how trees use resources, fill space, and grow. These individual-level traits and properties scale up to predict emergent properties of forest stands, including size–frequency distributions, spacing relations, resource flux rates, and canopy configurations. Two insights emerge from this analysis: (
i
) The size structure and spatial arrangement of trees in the entire forest are emergent manifestations of the way that functionally invariant xylem elements are bundled together to conduct water and nutrients up from the trunks, through the branches, to the leaves of individual trees. (
ii
) Geometric and dynamic properties of trees in a forest and branches in trees scale identically, so that the entire forest can be described mathematically and behaves structurally and functionally like a scaled version of the branching networks in the largest tree. This quantitative framework uses a small number of parameters to predict numerous structural and dynamical properties of idealized forests.
Extensions and evaluations of a general quantitative theory of forest structure and dynamics
Authors: Enquist Brian J. , West Geoffrey B. , Brown James H.
Published: April 2009

Here, we present the second part of a quantitative theory for the structure and dynamics of forests under demographic and resource steady state. The theory is based on individual-level allometric scaling relations for how trees use resources, fill space, and grow. These scale up to determine emergent properties of diverse forests, including size–frequency distributions, spacing relations, canopy configurations, mortality rates, population dynamics, successional dynamics, and resource flux rates. The theory uniquely makes quantitative predictions for both stand-level scaling exponents and normalizations. We evaluate these predictions by compiling and analyzing macroecological datasets from several tropical forests. The close match between theoretical predictions and data suggests that forests are organized by a set of very general scaling rules. Our mechanistic theory is based on allometric scaling relations, is complementary to “demographic theory,” but is fundamentally different in approach. It provides a quantitative baseline for understanding deviations from predictions due to other factors, including disturbance, variation in branching architecture, asymmetric competition, resource limitation, and other sources of mortality, which are not included in the deliberately simplified theory. The theory should apply to a wide range of forests despite large differences in abiotic environment, species diversity, and taxonomic and functional composition.
Symmetry, probability, and recognition in face space
Authors: Sirovich Lawrence , Meytlis Marsha
Published: April 2009

The essential midline symmetry of human faces is shown to play a key role in facial coding and recognition. This also has deep and important connections with recent explorations of the organization of primate cortex, as well as human psychophysical experiments. Evidence is presented that the dimension of face recognition space for human faces is dramatically lower than previous estimates. One result of the present development is the construction of a probability distribution in face space that produces an interesting and realistic range of (synthetic) faces. Another is a recognition algorithm that by reasonable criteria is nearly 100% accurate.
β-Arrestin-dependent signaling and trafficking of 7-transmembrane receptors is reciprocally regulated by the deubiquitinase USP33 and the E3 ligase Mdm2
Authors: Shenoy Sudha K. , Modi Aalok S. , Shukla Arun K. , Xiao Kunhong , Berthouze Magali , Ahn Seungkirl , Wilkinson Keith D. , Miller William E. , Lefkowitz Robert J.
Published: April 2009

β-Arrestins are multifunctional adaptors that mediate the desensitization, internalization, and some signaling functions of seven-transmembrane receptors (7TMRs). Agonist-stimulated ubiquitination of β-arrestin2 mediated by the E3 ubiquitin ligase Mdm2 is critical for rapid β
2
-adrenergic receptor (β
2
AR) internalization. We now report the discovery that the deubiquitinating enzyme ubiquitin-specific protease 33 (USP33) binds β-arrestin2 and leads to the deubiquitination of β-arrestins. USP33 and Mdm2 function reciprocally and favor respectively the stability or lability of the receptor β-arrestin complex, thus regulating the longevity and subcellular localization of receptor signalosomes. Receptors such as the β
2
AR, previously shown to form loose complexes with β-arrestin (“class A”) promote a β-arrestin conformation conducive for binding to the deubiquitinase, whereas the vasopressin V2R, which forms tight β-arrestin complexes (“class B”), promotes a distinct β-arrestin conformation that favors dissociation of the enzyme. Thus, USP33–β-arrestin interaction is a key regulatory step in 7TMR trafficking and signal transmission from the activated receptors to downstream effectors.
Sweden - the world’s most feminist society
Authors: Hornscheidt Lann
Published: April 2009

The article investigates the actual usage of the termfeministin current Swedish public debates and analyses it as a strategy of political branding. The following questions are considered in particular: How and when are resisting political attitudes integrated into the political mainstream? To what degree can this be traced in verbal actions? Furthermore, the article introduces the concept ofcritical occidentalismas a starting point for analysis. In this way, the investigation focuses on the self-construction of hegemonic European identities. The analytical focal point is therefore transferred from the construction of others – as is very often the case in CDA studies of the mechanisms of racism and sexism – to the construction of selves. The hegemonic and interdependent ‘nature’ of linguistic collective identity constructions is then discussed in this context.
A conserved CCCH-type zinc finger protein regulates mRNA nuclear adenylation and export
Authors: Hurt Jessica A. , Obar Robert A. , Zhai Bo , Farny Natalie G. , Gygi Steven P. , Silver Pamela A.
Published: April 2009

Coupling of messenger RNA (mRNA) nuclear export with prior processing steps aids in the fidelity and efficiency of mRNA transport to the cytoplasm. In this study, we show that the processes of export and polyadenylation are coupled via the Drosophila melanogaster CCCH-type zinc finger protein CG6694/dZC3H3 through both physical and functional interactions. We show that depletion of dZC3H3 from S2R+ cells results in transcript hyperadenylation. Using targeted coimmunoprecipitation and liquid chromatography mass spectrometry (MS)/MS techniques, we characterize interactions of known components of the mRNA nuclear export and polyadenylation machineries with dZC3H3. Furthermore, we demonstrate the functional conservation of this factor, as depletion of its human homologue ZC3H3 by small interfering RNA results in an mRNA export defect in human cells as well. Nuclear polyadenylated (poly(A)) RNA in ZC3H3-depleted cells is sequestered in foci removed from SC35-containing speckles, indicating a shift from the normal subnuclear distribution of poly(A) RNA. Our data suggest a model wherein ZC3H3 interfaces between the polyadenylation machinery, newly poly(A) mRNAs, and factors for transcript export.
In vivo regulation of interleukin 1β in patients with cryopyrin-associated periodic syndromes
Authors: Lachmann Helen J. , Lowe Philip , Felix Sandra Daniela , Rordorf Christiane , Leslie Kieron , Madhoo Sheril , Wittkowski Helmut , Bek Stephan , Hartmann Nicole , Bosset Sophie , Hawkins Philip N. , Jung Thomas
Published: April 2009

The investigation of interleukin 1β (IL-1β) in human inflammatory diseases is hampered by the fact that it is virtually undetectable in human plasma. We demonstrate that by administering the anti–human IL-1β antibody canakinumab (ACZ885) to humans, the resulting formation of IL-1β–antibody complexes allowed the detection of in vivo–produced IL-1β. A two-compartment mathematical model was generated that predicted a constitutive production rate of 6 ng/d IL-1β in healthy subjects. In contrast, patients with cryopyrin-associated periodic syndromes (CAPS), a rare monogenetic disease driven by uncontrolled caspase-1 activity and IL-1 production, produced a mean of 31 ng/d. Treatment with canakinumab not only induced long-lasting complete clinical response but also reduced the production rate of IL-1β to normal levels within 8 wk of treatment, suggesting that IL-1β production in these patients was mainly IL-1β driven. The model further indicated that IL-1β is the only cytokine driving disease severity and duration of response to canakinumab. A correction for natural IL-1 antagonists was not required to fit the data. Together, the study allowed new insights into the production and regulation of IL-1β in man. It also indicated that CAPS is entirely mediated by IL-1β and that canakinumab treatment restores physiological IL-1β production.