June 2006 arXiv papers — page 21

Franz Gross, G. Ramalho, M. T. Pena

Using the manifestly covariant spectator theory, and modeling the nucleon as a system of three constituent quarks with their own electromagnetic structure, we show that all four nucleon electromagnetic form factors can be very well described by a manifestly covariant nucleon wave function with zero orbital angular momentum. Since the concept of wave function

Csaba Toke, Paul E. Lammert, Jainendra K. Jain, Vincent H. Crespi

Unlike regular electron spin, the pseudospin degeneracy of Fermi points in graphene does not couple directly to magnetic field. Therefore, graphene provides a natural vehicle to observe the integral and fractional quantum Hall physics in an elusive limit analogous to zero Zeeman splitting in GaAs systems. This limit can exhibit new integral plateaus arising

George M. Bergman

In 1957, N. G. de Bruijn showed that the symmetric group Sym(\Omega) on an infinite set \Omega contains a free subgroup on 2^{card(\Omega)} generators, and proved a more general statement, a sample consequence of which is that for any group A of cardinality \leq card(\Omega), Sym(\Omega) contains a coproduct of 2^{card(\Omega)} copies of A, not only in the v

Dennis S. Keeler

We prove a version of Fujita's Conjecture in arbitrary characteristic, generalizing results of K.E. Smith. Our methods use the Frobenius morphism, but avoid tight closure theory. We also obtain versions of Fujita's Conjecture for coherent sheaves with certain ampleness properties.

E. Craig Dukes

The HyperCP (E871) experiment collected several billion hyperon decays in the 1997 and 1999 Fermilab fixed-target running periods. Using the data from the 1999 run, we report on the observation of three isolated events with reconstructed masses consistent with the hypothesis Sigma-plus -> proton + mu-plus + mu-minus. This is the rarest baryon decay ever obse

Robert A. Proctor

Rota's Twelvefold Way gave formulas for the numbers of partitions which could be formed in twelve scenarios. This proposed AMM article expands Rota's 4 x 3 table. The resulting 6 x 5 table considers a broader collection of splitting-distributing-grouping-arranging scenarios, each of which can be visualized with the distribution of m items into certai

Kamiokande Collaboration, K. Abe

We present the results from several studies used to search for astrophysical sources of high-energy neutrinos using the Super-Kamiokande-I (April 1996 to July 2001) neutrino-induced upward-going muon data. The data set consists of 2359 events with minimum energy 1.6 GeV, of which 1892 are through-going and 467 stop within the detector. The results of several

Sergio Flores-Tulian, Andreas Reisenegger

Several different processes could be changing the density in the core of a neutron star, leading to a departure from $β$ equilibrium, quantified by the chemical potential difference $δμ\equivμ_n-μ_p-μ_e$. The evolution of this quantity is coupled to that of the star's interior temperature $T$ by two functions that quantify the rate at which neutrino-emit

Sergey Bravyi, David P. DiVincenzo, Roberto I. Oliveira, Barbara M. Terhal

We study the complexity of the Local Hamiltonian Problem (denoted as LH-MIN) in the special case when a Hamiltonian obeys conditions of the Perron-Frobenius theorem: all off-diagonal matrix elements in the standard basis are real and non-positive. We will call such Hamiltonians, which are common in the natural world, stoquastic. An equivalent characterizatio

David T Gay

We construct four-dimensional symplectic cobordisms between contact three-manifolds generalizing an example of Eliashberg. One key feature is that any handlebody decomposition of one of these cobordisms must involve three-handles. The other key feature is that these cobordisms contain chains of symplectically embedded two-spheres of square zero. This, togeth

Matthias Schröter, Sibylle Nägle, Charles Radin, Harry L. Swinney

We find that a column of glass beads exhibits a well-defined transition between two phases that differ in their resistance to shear. Pulses of fluidization are used to prepare static states with well-defined particle volume fractions $ϕ$ in the range 0.57-0.63. The resistance to shear is determined by slowly inserting a rod into the column of beads. The tran

M. Andrecut, S. A. Kauffman

In this paper, we propose a mean-field model which attempts to bridge the gap between random Boolean networks and more realistic stochastic modeling of genetic regulatory networks. The main idea of the model is to replace all regulatory interactions to any one gene with an average or effective interaction, which takes into account the repression and activati

B. Shivamoggi, S. Kurien, D. Livescu

Kuzmin-Oseledets formulations of compressible Euler equations case are considered. Exact results and physical interpretations are given. One such exact result for the compressible barotropic case is the potential helicity Lagrange invariant. In recognition of the fundamental physical implications of this Lagrange invariant clarified here, this invariant is s

Haidong Feng, Warren Siegel

We propose some new simplifying ingredients for Feynman diagrams that seem necessary for random lattice formulations of superstrings. In particular, half the fermionic variables appear only in particle loops (similarly to loop momenta), reducing the supersymmetry of the constituents of the Type IIB superstring to N=1, as expected from their interpretation in

A. Rod Gover, Petr Somberg, Vladimir Soucek

Working over a pseudo-Riemannian manifold, for each vector bundle with connection we construct a sequence of three differential operators which is a complex (termed a Yang-Mills detour complex) if and only if the connection satisfies the full Yang-Mills equations. A special case is a complex controlling the deformation theory of Yang-Mills connections. In th

H. Kroger, G. Melkonyan, F. Paradis, S. G. Rubin

We investigate the dynamics of gravity coupled to a scalar field using a non-canonical form of the kinetic term. It is shown that its singular point represents an attractor for classical solutions and the stationary value of the field may occur distant from the minimum of the potential. In this paper properties of universes with such stationary states are co

Jason Kumar, James D. Wells

Intersecting D-brane theories motivate the existence of exotic U(1) gauge bosons that only interact with the Standard Model through kinetic mixing with hypercharge. We analyze an effective field theory description of this effect and describe the implications of these exotic gauge bosons on precision electroweak, LHC and ILC observables.

Maxim Braverman, Thomas Kappeler

The refined analytic torsion associated to a flat vector bundle over a closed odd-dimensional manifold canonically defines a quadratic form $τ$ on the determinant line of the cohomology. Both $τ$ and the Burghelea-Haller torsion are refinements of the Ray-Singer torsion. We show that whenever the Burghelea-Haller torsion is defined it is equal to $\pmτ$. As

Sergei L. Lukyanov, Philipp Werner

We perform a numerical analysis of recently proposed scaling functions for the single electron box. Specifically, we study the ``magnetic'' susceptibility as a function of tunneling conductance and gate charge, and the effective charging energy at zero gate charge as a function of tunneling conductance in the strong tunneling limit. Our Monte Carlo r

Kurusch Ebrahimi-Fard, Dominique Manchon

We establish Sakakibara's differential equations in a matrix setting for the counter term (respectively renormalized character) in Connes-Kreimer's Birkhoff decomposition in any connected graded Hopf algebra, thus including Feynman rules in perturbative renormalization as a key example.

Yi Ling, Hongbao Zhang

From the viewpoint of local quantum field theory, this letter investigates the high-order corrections to the holographic entropy bound. As a result, the logarithmic correction term appears naturally with the definite coefficient $-{1/2}$, which thus provides another semi-classical platform to examine such candidates for quantum gravity as Loop Quantum Gravit

Franz J. Kaiser, Peter Hänggi, Sigmund Kohler

We study numerically the influence of strong Coulomb repulsion on the current through molecular wires that are driven by external electromagnetic fields. The molecule is described by a tight-binding model whose first and last site is coupled to a respective lead. The leads are eliminated within a perturbation theory yielding a master equation for the wire. T

Jean-Marie Normand

The standard block orthogonal (SBO) polynomials $P_{i;n}(x), 0\le i\le n$ are real polynomials of degree $n$ which are orthogonal with respect to a first Euclidean scalar product to polynomials of degree less than $i$. In addition, they are mutually orthogonal with respect to a second Euclidean scalar product. Applying the general results obtained in a previ

Amit Giveon, Dan Gorbonos

We study aspects of four dimensional black holes with two electric charges, corresponding to fundamental strings with generic momentum and winding on an internal circle. The perturbative α' correction to such black holes and their gravitational thermodynamics is obtained.

Micheal S. Berger, Hamed Shojaei

We explore a model of interacting dark energy where the dark energy density is related by the holographic principle to the Hubble parameter, and the decay of the dark energy into matter occurs at a rate comparable to the current value of the Hubble parameter. We find this gives a good fit to the observational data supporting an accelerating Universe, and the

Martin Hecht, Jens Harting, Hans J. Herrmann

In Al2O3 suspensions, depending on the experimental conditions very different microstructures can be found, comprising fluid like suspensions, a repulsive structure, and a clustered microstructure. For technical processing in ceramics, the knowledge of the microstructure is of importance, since it essentially determines the stability of a workpiece to be pro

Alcides Garat

Tetrads are introduced in order to study the relationship between tetrad gauge states of spacetime and particle interactions, specially in weak processes at low energy. Through several examples like inverse Muon decay, elastic Neutrino-Electron scattering, it is explicitly shown how to assign to each vertex of the corresponding low-order Feynman diagram in a

Vincenzo Chilla

Transformation coefficients between {\it standard} bases for irreducible representations of the symmetric group $S_n$ and {\it split} bases adapted to the $S_{n_1} \times S_{n_2} \subset S_n$ subgroup ($n_1 +n_2 = n$) are considered. We first provide a \emph{selection rule} and an \emph{identity rule} for the subduction coefficients which allow to decrease t

Jean-Marie Normand

Constrained orthogonal polynomials have been recently introduced in the study of the Hohenberg-Kohn functional to provide basis functions satisfying particle number conservation for an expansion of the particle density. More generally, we define block orthogonal (BO) polynomials which are orthogonal, with respect to a first Euclidean scalar product, to a giv

A. Sacchetti, L. Degiorgi, T. Giamarchi, N. Ru

We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectivel

F. Ginelli, H. Hinrichsen, R. Livi, D. Mukamel

A class of non-local contact processes is introduced and studied using mean-field approximation and numerical simulations. In these processes particles are created at a rate which decays algebraically with the distance from the nearest particle. It is found that the transition into the absorbing state is continuous and is characterized by continuously varyin

Carlo Rovelli, Simone Speziale

We construct a macroscopic semiclassical state state for a quantum tetrahedron. The expectation values of the geometrical operators representing the volume, areas and dihedral angles are peaked around assigned classical values, with vanishing relative uncertainties.

Lyublena Antova, Christoph Koch, Dan Olteanu

Current systems and formalisms for representing incomplete information generally suffer from at least one of two weaknesses. Either they are not strong enough for representing results of simple queries, or the handling and processing of the data, e.g. for query evaluation, is intractable. In this paper, we present a decomposition-based approach to addressing

D. Guadagnoli, V. Lubicz, M. Papinutto, S. Simula

We present the first quenched lattice QCD study of the form factors relevant for the hyperon semileptonic decay Sigma -> n l nu. The momentum dependence of both axial and vector form factors is investigated and the values of all the form factors at zero-momentum transfer are presented. Following the same strategy already applied to the decay K0 -> pi- l nu,

A. Semke, M. F. M. Lutz

We compute the quark-mass dependence of the baryon octet and decuplet masses within the $χ$-MS scheme at the one-loop level. The results are confronted with recent lattice QCD simulations of the MILC collaboration. A fair reproduction of the quark-mass dependence as suggested by the lattice simulations is obtained up to pion masses of about 700 MeV. Based on

M. Kachelriess, R. Tomas

We calculate the yield of high energy neutrinos produced in astrophysical sources with negligible magnetic fields varying their interaction depth from nearly transparent to opaque. We take into account the scattering of secondaries on background photons as well as the direct production of neutrinos in decays of charm mesons. If multiple scattering of nucleon

Bobby Ezhuthachan, Suresh Govindarajan, T. Jayaraman

We systematically study and obtain the large-volume analogues of fractional two-branes on resolutions of orbifolds C^3/Z_n. We study a generalisation of the McKay correspondence proposed in hep-th/0504164 called the quantum McKay correspondence by constructing duals to the fractional two-branes. Details are explicitly worked out for two examples -- the crepa

C. J. Evans, D. J. Lennon, S. J. Smartt, C. Trundle

We present new observations of 470 stars using the Fibre Large Array Multi-Element Spectrograph (FLAMES) instrument in fields centered on the clusters NGC 330 and NGC 346 in the Small Magellanic Cloud (SMC), and NGC 2004 and the N11 region in the Large Magellanic Cloud (LMC). A further 14 stars were observed in the N11 and NGC 330 fields using the Ultraviole

Christian D'Cruz, Tobias J. Osborne, Ruediger Schack

We formulate and prove a de Finetti representation theorem for finitely exchangeable states of a quantum system consisting of k infinite-dimensional subsystems. The theorem is valid for states that can be written as the partial trace of a pure state chosen from a family of subsets C_n of the full symmetric subspace for $n$ subsystems. We show that such state

Hjalmar Rosengren

We study multivariable Christoffel-Darboux kernels, which may be viewed as reproducing kernels for antisymmetric orthogonal polynomials, and also as correlation functions for products of characteristic polynomials of random Hermitian matrices. Using their interpretation as reproducing kernels, we obtain simple proofs of Pfaffian and determinant formulas, as

Akio Nakahara, Yousuke Matsuo

Experiments involving vibrating pastes before drying were performed for the purposes of controlling the crack patterns that appear in the drying process. These experiments revealed a transition in the direction of lamellar cracks from perpendicular to parallel when compared with the direction of the initial external vibration as the solid volume fraction of

Romuald A. Janik, Robi Peschanski

We derive the equation for the quasi-normal modes corresponding to the scalar excitation of a black hole moving away in the fifth dimension. This geometry is the AdS/CFT dual of a boost-invariant expanding perfect fluid in N=4 SUSY Yang-Mills theory at large proper-time. On the gauge-theory side, the dominant solution of the equation describes the decay back

Hua Wu, Z. Hu, T. Burnus, J. D. Denlinger

Using x-ray absorption spectroscopy at the Ru-$L_{2,3}$ edge we reveal that the Ru$^{4+}$ ions remain in the $S$=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We find using local spin density approximation + Hubbard U (LSDA+U) band structure calculations that the crystal fields in the low temperature phase are not strong

A. Sanchez Lorente, P. Achenbach, M. Agnello, T. Bressani

A new generation of high-resolution hypernuclear gamma$-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DAPhiNE, the Frascati phi-factory, and at PANDA, the antiproton proton hadron spectrometer at the future FAIR facility. Both, the FINUDA and PANDA spectrometers are built around the

Chyh-Hong Chern

We propose a pseudo-potential Hamiltonian for the Zhang-Hu's generalized fractional quantum Hall states to be the exact and unique ground states. Analogously to Laughlin's quasi-hole (quasi-particle), the excitations in the generalized fractional quantum Hall states are extended objects. They are vortex-like excitations with fractional charges $+(-)1

Ioannis Giannakis, Defu Hou, Mei Huang, Hai-cang Ren

In this letter we explore the Higgs instability in the gapless superfluid/superconducting phase. This is in addition to the (chromo)magnetic instability that is related to the fluctuations of the Nambu-Goldstone bosonic fields. While the latter may induce a single-plane-wave LOFF state, the Higgs instability favors spatial inhomogeneity and cannot be removed

Poul Olesen

The spectral density for two dimensional continuum QCD has a non-analytic behavior for a critical area. Apparently this is not reflected in the Wilson loops. However, we show that the existence of a critical area is encoded in the winding Wilson loops: Although there is no non-analyticity or phase transition in these Wilson loops, the dynamics of these loops

T. Barthel, S. Dusuel, J. Vidal

We present a perturbative method to compute the ground state entanglement entropy for interacting systems. We apply it to a collective model of mutually interacting spins in a magnetic field. At the quantum critical point, the entanglement entropy scales logarithmically with the subsystem size, the system size, and the anisotropy parameter. We determine the

Stefano Bellucci, Armen Nersessian, Armen Yeranyan

We apply the technique of Hamiltonian reduction for the construction of three-dimensional ${\cal N}=4$ supersymmetric mechanics specified by the presence of a Dirac monopole. For this purpose we take the conventional ${\cal N}=4$ supersymmetric mechanics on the four-dimensional conformally-flat spaces and perform its Hamiltonian reduction to three-dimensiona

Asmaa Abada, Gautam Bhattacharyya, Gregory Moreau

In the Minimal Supersymmetric Standard Model with bilinear R-parity violation, only one neutrino eigenstate acquires a mass at tree level, consequently experimental data on neutrinos cannot be accommodated at tree level. We show that in the Next-to-Minimal extension, where a gauge singlet superfield is added to primarily address the so-called $μ$-problem, it

Mats Forsberg, Gert Brodin, Mattias Marklund, Padma K. Shukla

We present an investigation of nonlinear interactions between Gravitational Radiation and modified Alfvén modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three wave coupling coefficients, and calculate the growth rates for parametrically coupled grav

J. I. Read, A. P. Pontzen, M. Viel

Using analytic arguments and a suite of very high resolution (10^3 Msun per particle) cosmological hydro-dynamical simulations, we argue that high redshift, z ~ 10, M ~ 10^8 Msun halos, form the smallest `baryonic building block' (BBB) for galaxy formation. These halos are just massive enough to efficiently form stars through atomic line cooling and to h

Ivan V. Losev

Let $G$ be a connected reductive group. We find a necessary and sufficient condition for a quasiaffine homogeneous space of $G$ to be embeddable into an irreducible $G$-module. In addition, for an affine homogeneous space we find a criterium for a closed embedding to exist

Stefano Viaggiu

Starting with any stationary axisymmetric vacuum metric, we build anisotropic fluids. With the help of the Ernst method, the basic equations are derived together with the expression for the energy-momentum tensor and with the equation of state compatible with the field equations. The method is presented by using different coordinate systems: the cylindrical

Albert Schwarz, Vadim Vologodsky

We show that one can express Frobenius transformation on middle-dimensional p-adic cohomology of Calabi-Yau threefold in terms of mirror map and instanton numbers. We express the mirror map in terms of Frobenius transformation on p-adic cohomology . We discuss a $p$-adic interpretation of the conjecture about integrality of Gopakumar-Vafa invariants.

Ki-Myeong Lee, Ho-Ung Yee

In the Coulomb phase of the 6-dim (2,0) superconformal theories, the 1/4, 1/8, 1/16 BPS selfdual string webs are argued to exist such that the spatial SO(5) and internal SO(5) rotations are correlated. The basic constituents are 1/2 BPS strings and 1/4 BPS string junctions. One support comes from the existence of the similar BPS dyonic monostring webs in 5-d

Jian-Zhong Du, Su-Juan Qin, Qiao-Yan Wen, Fu-Chen Zhu

Grover's operator in the two-qubit case can transform a basis into its conjugated basis. A permutation operator can transform a state in the two conjugated bases into its orthogonal state. These properties are included in a threshold quantum protocol. The proposed threshold quantum protocol is secure based the proof that the legitimate participators can

Yasuhide Numata

Young's lattice, the lattice of all Young diagrams, has the Robinson-Schensted-Knuth correspondence, the correspondence between certain matrices and pairs of semi-standard Young tableaux with the same shape. Fomin introduced generalized Schur operators to generalize the Robinson-Schensted-Knuth correspondence. In this sense, generalized Schur operators a

Sung Joon Moon, B. Nabet, Naomi E. Leonard, Simon A. Levin

We study coarse-grained (group-level) alignment dynamics of individual-based animal group models for {\it heterogeneous} populations consisting of informed (on preferred directions) and uninformed individuals. The orientation of each individual is characterized by an angle, whose dynamics are nonlinearly coupled with those of all the other individuals, with

R. K. Nesbet

Qualitative implications of electroweak theory are reconsidered on the assumption that the unique source of fermion rest mass is self-interaction via coupling to gauge fields. This implies small but nonzero mass for neutrinos, and suggests that successive fermion generations are distinct coupled-field eigenstates of a self-interaction mass operator. For a sc

Meera G. Mainkar

We study nilmanifolds admitting Anosov automorphisms by applying elementary properties of algebraic units in number fields to the associated Anosov Lie algebras. We identify obstructions to the existence of Anosov Lie algebras. The case of 13-dimensional Anosov Lie algebras is worked out as an illustration of the technique. Also, we recapture the following k

Gang Chen, Istvan Szapudi

We measure the 2-1 cumulant correlator power spectrum $C^{21}_l$, a degenerate bispectrum, from the second data release of the Wilkinson Microwave Anisotropy Probe (WMAP). Our high resolution measurements with SpICE span a large configuration space ($\simeq 168\times999$) corresponding to the possible cross-correlations of the maps recorded by the different

Y. Shin, M. W. Zwierlein, C. H. Schunck, A. Schirotzek

We have observed phase separation between the superfluid and the normal component in a strongly interacting Fermi gas with imbalanced spin populations. The in situ distribution of the density difference between two trapped spin components is obtained using phase-contrast imaging and 3D image reconstruction. A shell structure is clearly identified where the s

Antonio Acin, Nicolas Gisin, Benjamin Toner

We relate the nonlocal properties of noisy entangled states to Grothendieck's constant, a mathematical constant appearing in Banach space theory. For two-qubit Werner states $ρ^W_p=p \proj{ψ^-}+(1-p){\one}/{4}$, we show that there is a local model for projective measurements if and only if $p \le 1/K_G(3)$, where $K_G(3)$ is Grothendieck's constant o

S. Garnerone, A. Marzuoli, M. Rasetti

We analyze the connections between the mathematical theory of knots and quantum physics by addressing a number of algorithmic questions related to both knots and braid groups. Knots can be distinguished by means of `knot invariants', among which the Jones polynomial plays a prominent role, since it can be associated with observables in topological quantu

K. A. Milton

Julian Schwinger's influence on Twentieth Century science is profound and pervasive. Of course, he is most famous for his renormalization theory of quantum electrodynamics, for which he shared the Nobel Prize with Richard Feynman and Sin-itiro Tomonaga. But although this triumph was undoubtedly his most heroic accomplishment, his legacy lives on chiefly

Nathaniel Lasry, Pierre-Osias Christin

The purpose of this paper is to show the magic of physics by showing the physics of magic. What usually makes magic tricks interesting is that something unexpected occurs. Similarly, demonstrations are interesting inasmuch as they produce something unexpected. Since expectations are linked to preconceptions, a demonstration making use of a flaw in a preconce

V. M. Datsyuk, I. M. Sokolov, D. V. Kupriyanov, M. D. Havey

We show that, under conditions of electromagnetically induced transparency (EIT), a significant portion of the incident probe pulse can be transferred into Rayleigh and Raman scattering channels. The light scattered into the Rayleigh channel emerges from the sample with an EIT time delay. We show that a proper description of the probe light propagation in th

Georges Bettega, Yohan Payan, Benoit Mollard, Anthony Boyer

Objectives : This paper presents a new simulator for maxillo-facial surgery, that gathers the dental and the maxillo-facial analyses together into a single computer-assisted procedure. The idea is first to propose a repositioning of the maxilla, via the introduction of a 3D cephalometry, applied to a 3D virtual model of the patient's skull. Then, orthodo

Jean-Michel Gerard, Reiner Wilhelms-Tricarico, Pascal Perrier, Yohan Payan

A 3D biomechanical dynamical model of human tongue is presented, that is elaborated in the aim to test hypotheses about speech motor control. Tissue elastic properties are accounted for in Finite Element Modeling (FEM). The FEM mesh was designed in order to facilitate the implementation of muscle arrangement within the tongue. Therefore, its structure was de

David Voirin, Yohan Payan, Miriam Amavizca, Christian Letoublon

Surgical resection of hepatic tumours is not always possible, since it depends on different factors, among which their location inside the liver functional segments. Alternative techniques consist in local use of chemical or physical agents to destroy the tumour. Radio frequency and cryosurgical ablations are examples of such alternative techniques that may

Yohan Payan, Matthieu Chabanas, Xavier Pelorson, Coriandre Vilain

This paper presents the biomechanical finite element models that have been developed in the framework of the computer-assisted maxillofacial surgery. After a brief overview of the continuous elastic modelling method, two models are introduced and their use for computer-assisted applications discussed. The first model deals with orthognathic surgery and aims

Vincent Luboz, Annaig Pedrono, Dominique Ambard, Franck Boutault

Objective: A method to predict the relationships between decompressed volume of orbital soft tissues, backward displacement of globe after osteotomy, and force exerted by the surgeon, was proposed to improve surgery planning in exophthalmia reduction. Design: A geometric model and a poroelastic finite element model were developed, based on Computed Tomograph

Vincent Luboz, Matthieu Chabanas, Pascal Swider, Yohan Payan

This paper addresses an important issue raised for the clinical relevance of Computer-Assisted Surgical applications, namely the methodology used to automatically build patient-specific Finite Element (FE) models of anatomical structures. From this perspective, a method is proposed, based on a technique called the Mesh-Matching method, followed by a process

Pascal Perrier, Yohan Payan, Majid Zandipour, Joseph Perkell

This study explores the following hypothesis: forward looping movements of the tongue that are observed in VCV sequences are due partly to the anatomical arrangement of the tongue muscles and how they are used to produce a velar closure. The study uses an anatomically based 2D biomechanical tongue model. Tissue elastic properties are accounted for in finite-

N. G. Kelkar, K. P. Khemchandani, B. K. Jain

Unstable states of the eta meson and the 3He nucleus predicted using the time delay method were found to be in agreement with a recent claim of eta-mesic 3He states made by the TAPS collaboration. Here, we extend this method to a speculative study of the unstable states occurring in the eta-d and eta-4He elastic scattering. The T-matrix for eta-4He scatterin

Stephen Wills

The stochastic generators of Markov-regular operator cocycles on symmetric Fock space are studied in a variety of cases: positive cocycles, projection cocycles, and partially isometric cocycles. Moreover a class of transformations of positive contraction cocycles is exhibited which leads to a polar decomposition result.

Stuart Armstrong, Thomas Leistner

For a conformal manifold we introduce the notion of an ambient connection, an affine connection on an ambient manifold of the conformal manifold, possibly with torsion, and with conditions relating it to the conformal structure. The purpose of this construction is to realise the normal conformal tractor holonomy as affine holonomy of such a connection. We gi

Antonio Rapagnetta

We study the global geometry of the ten dimensional O'Grady irreducible symplectic variety. We determine its second Betti number, its Beauville form and its Fujiki constant.

K. Soundararajan

This is an expanded account of three lectures on the distribution of prime numbers given at the Montreal NATO school on equidistribution.

Siman Wong

Given two elliptic curves defined over a number field K, not both with j-invariant zero, we show that there are infinitely many $D\in K^\times$ with pairwise distinct image in $ K^\times/{K^\times}^2 $, such that the quadratic twist of both curves by D have positive Mordell-Weil rank. The proof depends on relating the values of pairs of cubic polynomials to

Pavel Etingof, Frederic Latour, Eric Rains

We determine the structure of the center and the trace space of the centrally extended preprojective algebra of an ADE quiver, introduced by the first and the third authors in math/0503393. It turns out that this structure has a mysterious relationship to the structure of the maximal nilpotent subalgebra of the corresponding simple Lie algebra.

J. Kedra, Yu. Rudyak, A. Tralle

We describe all abelian groups which can appear as the fundamental groups of closed symplectically aspherical manifolds. The proofs use the theory of symplectic Lefschetz fibrations.

Yat-Ming Chan

This paper is a follow-up to an earlier paper math.DG/0410260 on desingularizations of Calabi-Yau 3-folds with a conical singularity. In math.DG/0410260 we study Calabi-Yau 3-folds M_0 with a conical singularity at x modelled on some Calabi-Yau cone V, and construct a desingularization of M_0 by gluing in an Asymptotically Conical (AC) Calabi-Yau 3-fold Y to

Philippe Jaming

In this article, we give an estimate of the zero-free region around the origin of the ambiguity function of a signal $u$ in terms of the moments of $u$. This is done by proving an uncertainty relation between the first zero of the Fourier transform of a non-negative function and the moments of the function. As a corollary, we also give an estimate of how muc

Philippe Jaming

In this survey, we present various forms of the uncertainty principle (Hardy, Heisenberg, Benedicks). We further give a new interpretation of the uncertainty principles as a statement about the time-frequency localization of elements of an orthonormal basis, which improves previous unpublished results of H. Shapiro. Finally, we show that Benedicks' resul

Philippe Jaming, Alexander M. Powell

The aim of this paper is to provide complementary quantitative extensions of two results of H.S. Shapiro on the time-frequency concentration of orthonormal sequences in $L^2 (\R)$. More precisely, Shapiro proved that if the elements of an orthonormal sequence and their Fourier transforms are all pointwise bounded by a fixed function in $L^2(\R)$ then the seq

Jian Song, Ben Weinkove

We prove some basic properties of Donaldson's flow of surfaces in a hyperkahler 4-manifold. When the initial submanifold is symplectic with respect to one Kähler form and Lagrangian with respect to another, we show that certain kinds of singularities cannot form, and we prove a convergence result under a condition related to one considered by M.-T. Wang

M. Weber

A 2-categorical generalisation of elementary topos is provided and some of the properties of the yoneda structure it generates are explored. Examples relevant to the globular approach to higher category theory are discussed. This paper also contains some expository material on the theory of fibrations internal to a finitely complete 2-category as well as a s

Manuel Lladser, Jaime San Martin

Let $X=(X_t)$ be a one-dimensional Ornstein-Uhlenbeck process with an initial density function $f$ supported on the positive real-line that is a regularly varying function with exponent $-(1+η)$, with $η\in (0,1)$. We prove the existence of a probability measure $ν$ with a Lebesgue density, depending on $η$, such that for every Borel set $A$ of the positive

L. Baracco, G. Zampieri

In $\C^2=\R^2+i\R^2$ with coordinates $z=(z_1,z_2), z=x+iy$, we consider a function $f$ continuous on a domain $Ω$ of $\R^2$ separately real analytic in $x_1$ and CR extendible to $y_2$ (resp. CR extendible to $y_2>0$). This means that $f(\cdot,x_2)$ extends holomorphically for $|y_1|<ε_{x_2}$ and $f(x_1,\cdot)$ for $| y_2|<ε$ (resp. $0\leq y_2<ε$ continuous

Hyung Ju Hwang, Alan D. Rendall, Juan J. L. Velazquez

The Vlasov-Poisson system describes interacting systems of collisionless particles. For solutions with small initial data in three dimensions it is known that the spatial density of particles decays like $t^{-3}$ at late times. In this paper this statement is refined to show that each derivative of the density which is taken leads to an extra power of decay

Maria Jose Cantero, Ruyman Cruz-Barroso, Pablo Gonzalez-Vera

In this paper we consider a general sequence of orthogonal Laurent polynomials on the unit circle and we first study the equivalences between recurrences for such families and Szego&#39;s recursion and the structure of the matrix representation for the multiplication operator when a general sequence of orthogonal Laurent polynomials on the unit circle is con

Parameswaran Sankaran

We show that the group of all pl-homeomorphisms of the reals having bounded slopes surjects on the group $QI({\Bbb R})$ of all quasi-isometries of ${\Bbb R}$. We prove that the following groups can be imbedded in $QI({\Bbb R})$: The group of compactly supported pl-homeomorphisms of the reals, the Richard Thompson group F, and the free group of rank the conti

Richard Melrose, Frédéric Rochon

The infinite matrix `Schwartz&#39; group $G^{-\infty}$ is a classifying group for odd K-theory and carries Chern classes in each odd dimension, generating the cohomology. These classes are closely related to the Fredholm determinant on $G^{-\infty}.$ We show that while the higher (even, Schwartz) loop groups of $G^{-\infty},$ again classifying for odd K-theo

A. R. Gover, K. Hallowell, A. Waldron

Gravitational interactions of higher spin fields are generically plagued by inconsistencies. We present a simple framework that couples higher spins to a broad class of gravitational backgrounds (including Ricci flat and Einstein) consistently at the classical level. The model is the simplest example of a Yang--Mills detour complex, which recently has been a

Mokhtar Hassaïne

We consider the problem of a self-interacting scalar field nonminimally coupled to the three-dimensional BTZ metric such that its energy-momentum tensor evaluated on the BTZ metric vanishes. We prove that this system is equivalent to a self-dual system composed by a set of two first-order equations. The self-dual point is achieved by fixing one of the coupli

S. L. Lukyanov

The main result of these notes is an analytical expression for the partition function of the circular brane model for arbitrary values of the topological angle. The model has important applications in condensed matter physics. It is related to the dissipative rotator (Ambegaokar-Eckern-Schon) model and describes a ``weakly blocked&#39;&#39; quantum dot with

Bernard de Wit, Frank Saueressig

A multiplet calculus is presented for an arbitrary number n of N=2 tensor supermultiplets. For rigid supersymmetry the known couplings are reproduced. In the superconformal case the target spaces parametrized by the scalar fields are cones over (3n-1)-dimensional spaces encoded in homogeneous SU(2) invariant potentials, subject to certain constraints. The co

Thomas Hambye

We investigate what would be the consequences for leptogenesis of the existence of a charged SU(2)_L singlet scalar delta^+. If such a scalar particle exists, it allows the right-handed neutrinos to couple not only to left-handed lepton and Higgs doublets as in ordinary leptogenesis, but also to a right-handed charged lepton and a delta^+. This provides a ne