January 2004 arXiv papers — page 16

Patrick E. McSharry, Leonard A. Smith

Empirical modelling often aims for the simplest model consistent with the data. A new technique is presented which quantifies the consistency of the model dynamics as a function of location in state space. As is well-known, traditional statistics of nonlinear models like root-mean-square (RMS) forecast error can prove misleading. Testing consistency is shown

K. Abe

We report the first observation of CP-violating asymmetries in B0 --> pi+pi- decays based on a 140 fb-1 data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one neutral B meson as a B0 --> pi+pi- CP eigenstate and identify the flavor of the accompanying B meson from its decay p

Kevin Ford

We determine the order of magnitude of H(x,y,z), the number of integers n\le x having a divisor in (y,z], for all x,y and z. We also study H_r(x,y,z), the number of integers n\le x having exactly r divisors in (y,z]. When r=1 we establish the order of magnitude of H_1(x,y,z) for all x,y,z satisfying z\le x^{0.49}. For every r\ge 2, $C>1$ and $ε>0$, we determ

L. Stawarz, M. Sikora, M. Ostrowski, M. C. Begelman

We discuss morphological properties of the large-scale jets in powerful radio sources, which are now observed at radio, optical and X-ray frequencies, in order to determine the origin of their X-ray radiation and the nature of the particle acceleration responsible for their multiwavelength emission. We show that modeling knots of the these objects as station

Elena M. Rossi, Andrei M. Beloborodov, Martin J. Rees

Fireballs with high energy per baryon rest mass (> 400) contain a relatively slow neutron component. We show here that in this situation the thermal history of fireballs is very different from the standard adiabatic cooling.

Gregory D. Wirth, Christopher N. A. Willmer, Paola Amico, Frederic H. Chaffee

We report the results of an extensive imaging and spectroscopic survey in the GOODS-North field completed using DEIMOS on the Keck II telescope. Observations of 2018 targets in a magnitude-limited sample of 2911 objects to R=24.4 yield secure redshifts for a sample of 1440 galaxies and AGN plus 96 stars. In addition to redshifts and associated quality assess

I. Mirkovic, K. Vilonen

In this paper we give a geometric version of the Satake isomorphism. Given a connected complex reductive algebraic group, we show that the category of representations of its Langlands dual is naturally equivalent to a certain category of perverse sheaves on the complex affine Grassmannian. We can work with perverse sheaves with coefficients in an arbitrary c

D. Y. Ivanov, A. Schaefer, L. Szymanowski, G. Krasnikov

The process of exclusive heavy vector meson photoproduction, gamma p -> V p, is studied in the framework of QCD factorization. The mass of the produced meson, V = Upsilon or J/Psi, provides a hard scale for the process. We demonstrate, that in the heavy quark limit and at the one-loop order in perturbation theory, the amplitude factorizes in a convolution of

Pengjie Zhang, John F. Beacom

The measured cosmic gamma ray background (CGB) spectrum at MeV energies is in reasonable agreement with the predicted contribution from type Ia supernovae (SNIa). But the characteristic features in the SNIa gamma ray spectrum, weakened by integration over source redshifts, are hard to measure, and additionally the contributions from other sources in the MeV

S. Baskal, E. Georgieva, Y. S. Kim, M. E. Noz

It has been almost one hundred years since Einstein formulated his special theory of relativity in 1905. He showed that the basic space-time symmetry is dictated by the Lorentz group. It is shown that this group of Lorentz transformations is not only applicable to special relativity, but also constitutes the scientific language for optical sciences. It is no

Gonzalo Ordonez, Sungyun Kim

We consider a pair of identical two-level atoms interacting with a scalar field in one dimension, separated by a distance $x_{21}$. We restrict our attention to states where one atom is excited and the other is in the ground state, in symmetric or anti-symmetric combinations. We obtain exact collective decaying states, belonging to a complex spectral represe

Daniel Collins, Sandu Popescu

"Information is physical", and here we consider the physical directional information of a particle with spin. We ask whether, in the presence of a classical frame of reference, such a particle contains any intrinsic directional information, ie. information above that which can be transmitted by a classical bit. We show that when sending a large numbe

Thomas Garrity, Zachary Grossman

An algorithm is given for computing explicit formulas for the generators of relations among the invariant rational functions for vector-valued bilinear forms. These formulas have applications in the geometry of Riemannian submanifolds and in CR geometry.

Marco Gualtieri

Generalized complex geometry, as developed by Hitchin, contains complex and symplectic geometry as its extremal special cases. In this thesis, we explore novel phenomena exhibited by this geometry, such as the natural action of a B-field. We provide new examples, including some on manifolds admitting no known complex or symplectic structure. We prove a gener

Toufik Mansour

We study the generating function for the number of involutions on $n$ letters containing exactly $r\gs0$ occurrences of 3412. It is shown that finding this function for a given $r$ amounts to a routine check of all involutions on $2r+1$ letters.

Eric Egge, Toufik Mansour

We study generating functions for the number of involutions, even involutions, and odd involutions in $S_n$ subject to two restrictions. One restriction is that the involution avoid 3412 or contain 3412 exactly once. The other restriction is that the involution avoid another pattern $τ$ or contain $τ$ exactly once. In many cases we express these generating f

David Callan

A binomial coefficient identity due to Zhi-Wei Sun is the subject of half a dozen recent papers that prove it by various analytic techniques and establish a generalization. Here we give a simple proof that uses weight-reversing involutions on suitable configurations involving dominos and colorings. With somewhat more work, the method extends to the generaliz

Kevin Ford

If a sequence $(a_n)$ of non-negative real numbers has ``best possible'' distribution in arithmetic progressions, Bombieri showed that one can deduce an asymptotic formula for the sum $\sum_{n\le x} a_n Λ_k(n)$ for $k\ge 2$. By constructing appropriate sequences, we show that any weakening of the well-distribution property is not sufficient to deduce

F. P. Weber, R. M. Vollmer

We extend F.Pastjin's construction of uniform decomposable chains of finite rank to those of rank 'finite over a limit' and investigate infinite products and unions of such chains. We derive an extension of Pastjin's characterisation to uniform decomposable chains of small transfinite rank (less than or equal to 'omega+omega'). We con

Kaori Suzuki

This paper considers Q-Fano 3-folds X with ρ=1. The aim is to determine the maximal Fano index f of X. We prove that f<= 19, and that in case of equality, the Hilbert series of X equals that of weighted projective space PP(3,4,5,7). From the previous version, we restrict the list of all possibilities of X to the case f>8. It will appear in a forthcoming pape

Alexander A. Chernitskii

Clifford number representation for linear electrodynamics with dyon sources is considered. Source function for the appropriate system of the first order equations for electromagnetic field is obtained. The field of an arbitrary moving point dyon is derived.

Yousef Bisabr

We establish a connection between the trace anomaly and a thermal radiation in the context of the standard cosmology. This is done by solving the covariant conservation equation of the stress tensor associated with a conformally invariant quantum scalar field. The solution corresponds to a thermal radiation with a temperature which is given in terms of a cut

Takehiro Azuma

The large-N reduced models have been proposed as the nonperturbative formulation of the superstring theory. One of the most promising candidates is the IIB matrix model. While there have been a lot of interesting discoveries of the IIB matrix model in relation to the gravity, we have a lot of problems to surmount, if a large-N reduced model is to be an eligi

L. Alejandro Correa-Borbonet

A possible link between Holography and Information Theory is presented. Using the relation between the Shannon and Boltzmann formulas Holography can be seen as the best encoding scheme.

H. Ballhausen

A derivative expansion of the effective average action beyond first order yields renormalization group functional flow equations which are used for the computation of critical exponents of the Ising universality class. The critical exponent nu in D=3 is consistent with high-precision methods.

Ernest Jankowski, David W. Maybury

A class of predictive SO(10) grand unified theories with highly asymmetric mass matrices, known as lopsided textures, has been developed to accommodate the observed mixing in the neutrino sector. The model class effectively determines the rate for charged lepton flavour violation, and in particular the branching ratio for $μ-> e γ$, assuming that the supersy

A. V. Prozorkevich, S. A. Smolyansky, S. V. Ilyin

The Vlasov type quantum kinetic equation for deconfined quarks in strong quasi-classical gluon field is derived in the covariant single-time formalism. The equations system for the Wigner function components is obtained as a result of spinor and color decomposition. The field-free and vacuum solutions of the kinetic equation are found, and the conservation l

Francisco S. N. Lobo

Applying the Darmois-Israel thin shell formalism, we construct static and dynamic thin shells around traversable wormholes. Firstly, by applying the cut-and-paste technique we apply a linearized stability analysis to thin-shell wormholes in the presence of a generic cosmological constant. We find that for large positive values of the cosmological constant, i

Vadim Tropashko

Relational Databases are universally conceived as an advance over their predecessors Network and Hierarchical models. Superior in every querying respect, they turned out to be surprisingly incomplete when modeling transitive dependencies. Almost every couple of months a question how to model a tree in the database surfaces at comp.database.theory newsgroup.

P. Hyldgaard

I report that thermal single-barrier (TSB) and thermal double-barrier (TDB) structures (formed, for example, by inserting one or two regions of a few Ge monolayers in Si) provide both a suppression of the phonon transport as well as a resonant-thermal-transport effect. I show that high-frequency phonons can experience a traditional double-barrier resonant tu

Victor M. Yakovenko, Victor A. Khodel

We propose to use the radio-frequency single-electron transistor as an extremely sensitive probe to detect the time-periodic ac signal generated by sliding electron lattice in the insulating state of the dilute two-dimensional electron gas. We also propose to use the optically-pumped NMR technique to probe the electron spin structure of the insulating state.

M. Khodas, A. M. Finkel&#39;stein

The Hall conductivity in a weak homogeneous magnetic field, $ω_{c}τ\ll 1$, is calculated. We have shown that to leading order in $1/ε_{F}τ$ the Hall coefficient $R_{H}$ is not renormalized by the electron-electron interaction. Our result explains the experimentally observed stability of the Hall coefficient in a dilute electron gas not too close to the metal

L. L. Cowie, A. J. Barger, E. M. Hu, P. Capak

We report the results of an extensive spectroscopic survey of galaxies in the roughly 160 square arcminute ACS-GOODS region surrounding the HDF-N. We have identified 787 galaxies or stars with z&#39;<24, R<24.5, or B<25 lying in the region. The spectra were obtained with either the DEIMOS or LRIS spectrographs on the Keck 10m telescopes. The results are comp

Seiichiro I. Aoki, Seiji Yashiro, Kazunari Shibata

We investigated the statistical distributions of physical quantities of solar flares and associated coronal mass ejections (CMEs). We found that the distributions of the X-ray peak fluxes of CME-related flares, their time intervals, and speeds of associated CMEs are in good agreement with log-normal distributions. One possible interpretation of this is that

I. V. Anikin, B. Pire, L. Szymanowski, O. V. Teryaev

We evaluate the leading order amplitude for the deep exclusive electroproduction of an exotic hybrid meson in the Bjorken regime. We show that, contrary to naive expectation, this amplitude factorizes at the twist 2 level and thus scales like usual meson electroproduction when the virtual photon and the hybrid meson are longitidinally polarized. Exotic hybri

Z. Burda, J. Jurkiewicz, A. Krzywicki

This paper is a direct continuation of an earlier work, where we studied Erdös-Rényi random graphs perturbed by an interaction Hamiltonian favouring the formation of short cycles. Here, we generalize these results. We keep the same interaction Hamiltonian but let it act on general graphs with uncorrelated nodes and an arbitrary given degree distribution. It

Christian Buth, Robin Santra, Lorenz S. Cederbaum

We devise a non-Hermitian Rayleigh-Schroedinger perturbation theory for the single- and the multireference case to tackle both the many-body problem and the decay problem encountered, for example, in the study of electronic resonances in molecules. A complex absorbing potential (CAP) is employed to facilitate a treatment of resonance states that is similar t

Lewis Bowen

In Thurston&#39;s notes, he gives two different definitions of the Gromov norm (also called simplicial volume) of a manifold and states that they are equal but does not prove it. Gromov proves it in the special case of hyperbolic manifolds as a consequence of his proof that simplicial volume is proportional to volume. We give a proof for all differentiable m

C. T. Shih, T. K. Lee, R. Eder, C. -Y. Mou

We investigate the effects of the next-nearest-neighbor ($t&#39;$) and the third-nearest-neighbor (t&#34;) hopping terms on superconductivity (SC) correlation in the 2D hole-doped extended t-J model based on the variational Monte-Carlo (VMC), mean-field (MF) calculation, and exact diagonalization (ED) method. Despite of the diversity of the methods employed,

W. Struyve, W. De Baere, J. De Neve, S. De Weirdt

We re-examine Peres&#39; statement ``opposite momenta lead to opposite directions&#39;&#39;. It will be shown that Peres&#39; statement is only valid in the large distance or large time limit. In the short distance or short time limit an additional deviation from perfect alignment occurs due to the uncertainty of the location of the source. This error contri

Todd M. Squires, Michael S. Weidman, Timothy C. Hain, Howard A. Stone

Benign Paroxysmal Positional Vertigo (BPPV) is a mechanical disorder of the vestibular system in which calcite particles called otoconia interfere with the mechanical functioning of the fluid-filled semicircular canals normally used to sense rotation. Using hydrodynamic models, we examine the two mechanisms proposed by the medical community for BPPV: cupulol

Paul Seidel

This short and fairly informal note is an attempt to explain how methods of homological algebra may be brought to bear on problems in symplectic geometry. We do this by looking at a familiar sample question, which is that of the topology of Lagrangian submanifolds in the cotangent bundle of the sphere.

Franc Forstneric

In this paper we prove results on the existence and homotopy classification of holomorphic submersions from Stein manifolds to other complex manifolds. We say that a complex manifold Y satisfies Property S_n for some integer n bigger or equal the dimension of Y if every holomorphic submersion from a compact convex set in C^n of a certain special type to Y ca

Kimball A. Milton

Quantum vacuum energy has been known to have observable consequences since 1948 when Casimir calculated the force of attraction between parallel uncharged plates, a phenomenon confirmed experimentally with ever increasing precision. Casimir himself suggested that a similar attractive self-stress existed for a conducting spherical shell, but Boyer obtained a

Liu Lianshou, Fu Jinghua

Various measures for the dynamical event-mean transverse momentum fluctuation are compared with the real dynamical fluctuation using a Monte Carlo model. The variance calculated from the G-moments can reproduce the dynamical variance well, while those obtained through subtraction procedures are approximate measures for not very low multiplicity. The Phi_pt c

Frank Wilczek

This is a broad and in part unconventional review of our current knowledge of fundamental physics, emphasizing the potential for advances the LHC will open up.

Jian Qi Shen

In this paper, we assume that the observer is fixed in a comoving frame of reference with $g_{00}=\fracλΛ$, where $λ$ and $Λ$ denote the comoving parameter and the cosmological constant, respectively. By using the {\it comoving suppression mechanism} and {\it Mach&#39;s principle} (the latter of which is used to determine the comoving parameter $λ$), we calc

Amir H. Darooneh

We consider the concept of equilibrium in economic systems from statistical mechanics viewpoint. A new method is suggested for computing the premium on this basis. The Bühlmann economic premium principle is derived as a special case of our method.

K. B. Efetov, G. Schwiete, K. Takahashi

Using a supersymmetry formalism, we reduce exactly the problem of electron motion in an external potential to a new supermatrix model valid at all distances. All approximate nonlinear sigma models obtained previously for disordered systems can be derived from our exact model using a coarse-graining procedure. As an example, we consider a model for a smooth d

Mason A. Porter, P. G. Kevrekidis, B. A. Malomed

We consider a system of two Gross-Pitaevskii (GP) equations, in the presence of an optical-lattice (OL) potential, coupled by both nonlinear and linear terms. This system describes a Bose-Einstein condensate (BEC) composed of two different spin states of the same atomic species, which interact linearly through a resonant electromagnetic field. In the absence

Todd M. Squires

The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has `optimally designed&#39;. Four geometric parameters are used to characterize the S

N. Michel, W. Nazarewicz, M. Ploszajczak, J. Rotureau

Recently, the shell model in the complex k-plane (the so-called Gamow Shell Model) has been formulated using a complex Berggren ensemble representing bound single-particle states, single-particle resonances, and non-resonant continuum states. In this framework, we shall discuss binding energies and energy spectra of neutron-rich helium and lithium isotopes.

Bo-Hae Im, Michael Larsen

Let G be a finite group and V a finite-dimensional rational G-representation. We ask whether there exists a finite Galois extension L/K of number fields with Galois group G, an elliptic curve E/K, and a G-submodule of E(L) tensor Q isomorphic to V.

B. B. Levchenko

In this note I recall some features of two-body decay kinematics which can be effectively applied, in particular, in experimental searches for pentaquark states.

Hartmut Wachter

We present explicit formulae for q-exponentials on quantum spaces which could be of particular importance in physics, i.e. the q-deformed Minkowski-space and the q-deformed Euclidean space with two, three or four dimensions. Furthermore, these formulae can be viewed as 2-, 3- or 4-dimensional analogues of the well-known q-exponential function.

A. K. Ray, J. C. Boettger

First principles linear combinations of Gaussian type orbitals-fitting function (LCGTO-FF) electronic structure calculations are used to study thickness dependencies in the surface energies and work functions of ultra-thin (111) films of fcc delta-Pu, up to five layers thick. The calculations are carried out at both scalar- and fully-relativistic (with and w

G. Y. Chitov, C. Gros

We study the 2D Ising model on a square lattice with additional non-equal diagonal next-nearest neighbor interactions. The cases of classical and quantum (transverse) models are considered. Possible phases and their locations in the space of three Ising couplings are analyzed. In particular, incommensurate phases occurring only at non-equal diagonal coupling

Yan V. Fyodorov

Finding the mean of the total number N_{tot} of critical points for N-dimensional random energy landscapes is reduced to averaging the absolute value of characteristic polynomial of the corresponding Hessian. For any finite N we provide the exact solution to the problem for a class of landscapes corresponding to the &#34;toy model&#34; of manifolds in random

U. Tippawan, S. Pomp, A. Atac, B. Bergenwall

Double-differential cross sections for light-ion (p, d, t, He-3 and alpha) production in silicon, induced by 96 MeV neutrons are reported. Energy spectra are measured at eight laboratory angles, ranging from 20 degrees to 160 degrees in steps of 20 degrees. Procedures for data taking and data reduction are presented. Deduced energy-differential, angle-differ

SVD Collaboration

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $Θ^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $Γ< 2

Y. Narumi, K. Katsumata, Z. Honda, J. -C. Domenge

The magnetization process of an S=1/2 antiferromagnet on the kagome lattice, [Cu_3(titmb)_2(OCOCH_3)_6]H_2O {titmb= 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6 trimethylbenzene} has been measured at very low temperatures in both pulsed and steady fields. We have found a new dynamical behavior in the magnetization process: a plateau at one third of the saturation m

Paolo Cea

P-stars are a new class of compact stars made of up and down quarks in $β$-equilibrium with electrons in a chromomagnetic condensate. P-stars are able to account for compact stars with $R \lesssim 6 Km$, as well as stars comparable to canonical neutron stars. We show that P-stars once formed are absolutely stable, for they cannot decay into neutron or strang

P. Giudice, A. Papa

In this paper we study the finite temperature SU(2) gauge theory with staggered fermions for non-zero imaginary and real chemical potential. The method of analytical continuation of Monte Carlo results from imaginary to real chemical potential is tested by comparison with simulations performed {\em directly} for real chemical potential. We discuss the applic

F. Pakovich

In this paper, in the context of the ``Dessins d&#39;enfants&#39;&#39; theory, we give a combinatorial criterion for a plane tree to cover a tree from the classes of &#34;chains&#34; or &#34;stars&#39;&#39;. Besides, we discuss some applications of this result which are related to the arithmetical theory of torsion on curves.

Han Guangze, O. Sørensen, A. S. Jensen, D. V. Fedorov

The hyperspherical adiabatic expansion method is used to describe correlations in a symmetric boson system rigorously confined to two spatial dimensions. The hyperangular eigenvalue equation turns out to be almost independent of the hyperradius, whereas the solutions are strongly varying with the strength of the attractive two-body potentials. Instability is

Svjetlana Fajfer, Tri Nang Pham, Anita Prapotnik

We investigate the decay mechanism in the B^- -> phi phi K^- decay with the phi phi invariant mass below the charm threshold and in the neighborhood of the eta_c invariant mass region. Our approach is based on the use of factorization model and the knowledge of matrix elements of the weak currents. For the B meson weak transition we apply form factor formali

G. L. Israel, N. Rea, V. Mangano, V. Testa

We report the accurate sub-arcsec X-ray position of the new Anomalous X-ray Pulsar (AXP) XTE J1810-197, derived with a Chndra-HRC Target of Opportunity observation carried out in November 2003. We also report the discovery of a likely IR counterpart based on a VLT (IR band) Target of Opportunity observation carried out in October 2003. Our proposed counterpa

S. Colson, C. J. van der Beek, M. Konczykowski, M. B. Gaifullin

The introduction of a large density of columnar defects in %underdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+δ}$ crystals does not, at sufficiently low vortex densities, increase the irreversibility line beyond the first order transition (FOT) field of pristine crystals. At such low fields, the flux line wandering length $r_{w}$ behaves as in pristine %Bi$_{2}$Sr$

Donato Bini, Christian Cherubini, Bahram Mashhoon

We study the vacuum C-metric and its physical interpretation in terms of the exterior spacetime of a uniformly accelerating spherically - symmetric gravitational source. Wave phenomena on the linearized C-metric background are investigated. It is shown that the scalar perturbations of the linearized C-metric correspond to the gravitational Stark effect. This

E. W. N. Glover

We present the two-loop helicity amplitudes for the scattering of massless quarks in QCD. We use projector techniques to compute the coefficients of the general four-quark amplitude at up to two-loops in conventional dimensional regularisation and use these coefficients to derive the helicity amplitudes in the &#39;t Hooft-Veltman scheme. The structure of th

Amit Ghosh, P. Mitra

Various approaches to black hole entropy yield the area law with logarithmic corrections, many involving a coefficient 1/2, and some involving 3/2. It is pointed out here that the standard quantum geometry formalism is not consistent with 3/2 and favours 1/2.

M. Kozlov, E. Levin

We show that the Iancu-Mueller factorization has a simple interpretation in the Reggeon - like technique based on the BFKL Pomeron. The formula for calculating the high energy asymptotic behaviour for the colour dipole-dipole amplitude is proposed which suggests a procedure to calculate this amplitude through the solution to the Balitsky-Kovchegov non-linear

Allan I Solomon, Sonia G Schirmer

Nature, in the form of dissipation, inevitably intervenes in our efforts to control a quantum system. In this talk we show that although we cannot, in general, compensate for dissipation by coherent control of the system, such effects are not always counterproductive; for example, the transformation from a thermal (mixed) state to a cold condensed (pure stat

Boris F. Samsonov

Darboux transformation of both Barut-Girardello and Perelomov coherent states for the time-dependent singular oscillator is studied. In both cases the measure that realizes the resolution of the identity operator in terms of coherent states is found and corresponding holomorphic representation is constructed. For the particular case of a free particle moving

Boris F Samsonov, Javier Negro

A detailed analysis of matrix Darboux transformations under the condition that the derivative of the superpotential be self-adjoint is given. As a onsequence, a class of the symmetries associated to Schrödinger matrix Hamiltonians is characterized. The applications are oriented towards the Jaynes-Cummings eigenvalue problem, so that exactly solvable $2\times

Thimo Rohlf, Stefan Bornholdt

Based on a recently proposed non-equilibrium mechanism for spatial pattern formation [cond-mat/0312366] we study how morphogenesis can be controlled by locally coupled discrete dynamical networks, similar to gene regulation networks of cells in a developing multicellular organism. As an example we study the developmental problem of domain formation and propo

J. Camacho, R. Guimera, D. B. Stouffer, L. A. N. Amaral

We analyze the properties of model food webs and of fifteen community food webs from a variety of environments. We first perform a theoretical analysis of the niche model of Williams and Martinez. We derive analytical expressions for the distributions of species&#39; number of prey, number of predators, and total number of trophic links and find that they fo

Yisroel Brumer, Eugene I. Shakhnovich

In this letter we study the full semi-conservative treatment of a model for the co-evolution of a virus and an adaptive immune system. Regions of viability are calculated for both conservatively and semi-conservatively replicating viruses interacting with a realistic semi-conservatively replicating immune system. The conservative virus is found to have a sel

Myran C. Sauer, R. A. Crowell, Ilya A. Shkrob

Time resolved transient absorption spectroscopy has been used to determine quantum yields for electron photodetachment in 193 nm and (where possible) 248 nm laser excitation of miscellaneous aqueous anions, including hexacyanoferrate(II), sulfate, sulfite, halide anions (Cl-, Br-, and I-), pseudohalide anions (OH-, HS-, CNS-), and several common inorganic an

Michael C. Parker, Stuart D. Walker

Recent investigations into the physical nature of information and fundamental limits to information transmission have revealed questions such as the possibility of superluminal data transfer or not; and whether reversible computation (information processing) is feasible. In some respects these uncertainties stem from the determination of whether information

K. Saitoh, N. A. Mortensen, M. Koshiba

We study the dispersion and leakage properties for the recently reported low-loss photonic band-gap fiber by Smith et al. [Nature 424, 657 (2003)]. We find that surface modes have a significant impact on both the dispersion and leakage properties of the fundamental mode. Our dispersion results are in qualitative agreement with the dispersion profile reported

Jens Harting, Maddalena Venturoli, Peter V. Coveney

Well designed lattice-Boltzmann codes exploit the essentially embarrassingly parallel features of the algorithm and so can be run with considerable efficiency on modern supercomputers. Such scalable codes permit us to simulate the behaviour of increasingly large quantities of complex condensed matter systems. In the present paper, we present some preliminary

A. Chernomoretz, F. Gulminelli, M. J. Ison, C. O. Dorso

Global equilibrium fragmentation inside a freeze out constraining volume is a working hypothesis widely used in nuclear fragmentation statistical models. In the framework of classical Lennard Jones molecular dynamics, we study how the relaxation of the fixed volume constraint affects the posterior evolution of microscopic correlations, and how a non-confined

M. F. M. Lutz, C. García-Recio, E. E. Kolomeitsev, J. Nieves

We study the quark-mass dependence of J^P = \frac12^- s-wave and J^P = \frac32^- d-wave baryon resonances. Parameter-free results are obtained in terms of the leading order chiral Lagrangian. In the &#39;heavy&#39; SU(3) limit with m_π=m_K \simeq 500 MeV the s-wave resonances turn into bound states forming two octets plus a singlet representations of the SU(

A4 Collaboration, F. E. Maas, P. Achenbach, K. Aulenbacher

We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a $Q^2$ of 0.230 (GeV/c)^2 and a scattering angle of θ_e = 30^o - 40^o. Using a large acceptance fast PbF_2 calorimeter with a solid angle of ΔΩ= 0.62 sr the A4 experiment is the first parity violation experiment to c

P. Camerini, E. Fragiacomo, N. Grion, S. Piano

The pion production reaction $π^+ \to π^+π^{\pm}$ on $^{45}Sc$ was studied at incident pion energies of $T_{π^{+}}$ = 240, 260, 280, 300, and 320 MeV. The experiment was performed using the $M11$ pion-channel at TRIUMF, and multiparticle events, ($π^+,π^+π^{\pm}$) and ($π^+,π^+π^{\pm}p$), were detected with the CHAOS spectrometer. Results are reported in the

S. Hu, D. I. Goldman, D. J. Kouri, D. K. Hoffman

The disorder function formalism [Gunaratne et.al., Phys. Rev. E, {\bf 57}, 5146 (1998)]^M is used to show that pattern relaxation in an experiment on a vibrated layer of brass beads^M occurs in three distinct stages. During stage I, all lengthscales associated with ^M moments of the disorder grow at a single universal rate, given by $L(t) \sim t^{0.5}$. In s

V. V. Gribanov, V. G. Kadyshevsky, A. S. Sorin

Bi-Hamiltonian structure and Lax pair formulation with the spectral parameter of the generalized fermionic Toda lattice hierarchy as well as its bosonic and fermionic symmetries for different (including periodic) boundary conditions are described. Its two reductions --N=4 and N=2 supersymmetric Toda lattice hierarchies-- in different (including canonical) ba

Hao Fang

We verify a conjecture of Gillet-Soulé. We prove that the determinant of the Laplacian on a line bundle over $\mathbb{CP}^{1}$ is always bounded from above. This can also be viewed as a multi-particle generalization of the Moser-Trudinger Inequality. Furthermore, we conjecture that this functional achieves its maximum at the canonical metric. We give some ev

A. Chakrabarti

A basis of $N^2$ projectors, each an ${N^2}\times{N^2}$ matrix with constant elements, is implemented to construct a class of braid matrices $\hat{R}(θ)$, $θ$ being the spectral parameter. Only odd values of $N$ are considered here. Our ansatz for the projectors $P_α$ appearing in the spectral decomposition of $\hat{R}(θ)$ leads to exponentials $exp(m_αθ)$ a

Antonios Zagaris, Hans G. Kaper, Tasso J. Kaper

The Computational Singular Perturbation (CSP) method of Lam and Goussis is an iterative method to reduce the dimensionality of systems of ordinary differential equations with multiple time scales. In [J. Nonlin. Sci., to appear], the authors showed that each iteration of the CSP algorithm improves the approximation of the slow manifold by one order. In this

Andrea D&#39;Agnolo, Pierre Schapira

Using the notion of subprincipal symbol, we give a necessary condition for the existence of twisted D-modules simple along a smooth involutive submanifold of the cotangent bundle to a complex manifold. As an application, we prove that there are no generalized massless field equations with non trivial twist on grassmannians, and in particular that the Penrose

Stephan Mohrdieck

We generalise the concept of a Steinberg cross-section to non-connected Kac-Moody group. As in the connected case, which was treated by G. Brüchert, a quotient map w.r.t the conjugacy action exists only on a certain submonoid of the Kac-Moody group. Non-connected Kac-Moody groups appear naturally as semidirect product of \C^* with a central extension of loop

Andreas Knauf, Iskander A. Taimanov

It is known that for $n \geq 3$ centres and positive energies the $n$-centre problem of celestial mechanics leads to a flow with a strange repellor and positive topological entropy. Here we consider the energies above some threshold and show: Whereas for arbitrary $g >1$ independent integrals of Gevrey class $g$ exist, no real-analytic (that is, Gevrey class

Han Peters

We study the dynamics of compositions of a sequence of holomorphic mappings in projective space. We define ergodicity and mixing for non-autonomous dynamical systems, and we construct totally invariant measures for which our sequence satisfies these properties.

Somdeb Lahiri

In this paper, we consider the problem of choosing a set of multi-party contracts, where each coalition of agents has a non-empty finite set of contracts to choose from. We call such problems, contract choice problems. We provide conditions under which a contract choice problem has a non-empty set of &#34;stable&#34; outcomes. There are two types of stabilit

Gianni Dal Maso, Gilles A. Francfort, Rodica Toader

The main steps of the proof of the existence result for the quasi-static evolution of cracks in brittle materials, obtained in [7] in the vector case and for a general quasiconvex elastic energy, are presented here under the simplifying assumption that the minimizing sequences involved in the problem are uniformly bounded in $L^\infty$.

Rolf Soeren Krausshar

This paper deals with a new analytic type of vector- and Clifford algebra valued automorphic forms in one and two vector variables. For hypercomplex generalizations of the classical modular group and their arithmetic congruence subgroups Eisenstein- and Poincaré type series that are annihilated by Dirac operators, and more generally, by iterated Dirac operat

Gianni Dal Maso, Gilles A. Francfort, Rodica Toader

In this paper, we prove a new existence result for a variational model of crack growth in brittle materials proposed in [15]. We consider the case of $n$-dimensional finite elasticity, for an arbitrary $n\ge1$, with a quasiconvex bulk energy and with prescribed boundary deformations and applied loads, both depending on time.

Manfred Kühleitner, Werner Georg Nowak

For a convex body B in three-dimensional Euclidean space, which is invariant under rotations around one coordinate axis and has a smooth boundary of bounded nonzero curvature, the lattice point discrepancy (number of integer points minus volume) of a linearly enlarged copy of B is estimated from below. On the basis of a recent method of K. Soundararajan, an