August 2006 arXiv papers — page 2

P. T. P. Hutauruk, A. Sulaksono, T. Mart

We have studied the effects of the nucleon weak magnetism and the neutrino electromagnetic properties on the neutrino and antineutrino mean free paths for all types of neutrinos. In the calculation, we consider matters with and without neutrino trapping as the target. We have found that the difference between the two mean free paths depends not only on the n

Kouji Kashiwa, Hiroaki Kouno, Tomohiko Sakaguchi, Masayuki Matsuzaki

The chiral phase transition is studied in an extended Nambu--Jona-Lasinio model with eight-quark interactions. Equations for scalar and vector quark densities, derived in the mean field approximation, are nonlinear and mutually coupled. The scalar-type nonlinear term hastens the restoration of chiral symmetry, while the scalar-vector mixing term makes the tr

B. Hippolyte

Strange quark and hadron production will be studied at the Large Hadron Collider (LHC) energies in order to explore the properties of both pp and heavy-ion collisions. The ALICE experiment will be specifically efficient in the strange sector with the identification of baryons and mesons over a wide range of transverse momentum. Dedicated measurements are pro

Marc Lefranc

The topological analysis of chaos based on a knot-theoretic characterization of unstable periodic orbits has proved a powerful method, however knot theory can only be applied to three-dimensional systems. Still, the core principles upon which this approach is built, determinism and continuity, apply in any dimension. We propose an alternative framework in wh

Arthur V. Straube, Markus Abel, Arkady Pikovsky

We develop a theory describing the transition to a spatially homogeneous regime in a mixing flow with a chaotic in time reaction. The transverse Lyapunov exponent governing the stability of the homogeneous state can be represented as a combination of Lyapunov exponents for spatial mixing and temporal chaos. This representation, being exact for time-independe

Robert Seiringer

A lower bound is derived on the free energy (per unit volume) of a homogeneous Bose gas at density $ρ$ and temperature $T$. In the dilute regime, i.e., when $a^3ρ\ll 1$, where $a$ denotes the scattering length of the pair-interaction potential, our bound differs to leading order from the expression for non-interacting particles by the term $4πa (2ρ^2 - [ρ-ρ_

M. A. Jafarizadeh, R. Sufiani

The continuous-time quantum walk (CTQW) on root lattice $A_n$ (known as hexagonal lattice for $n=2$) and honeycomb one is investigated by using spectral distribution method. To this aim, some association schemes are constructed from abelian group $Z^{\otimes n}_m$ and two copies of finite hexagonal lattices, such that their underlying graphs tend to root lat

Werner Kirsch, Bernd Metzger

We survey some aspects of the theory of the integrated density of states (IDS) of random Schroedinger operators. The first part motivates the problem and introduces the relevant models as well as quantities of interest. The proof of the existence of this interesting quantity, the IDS, is discussed in the second section. One central topic of this survey is th

Tomasz Schreiber

We consider the so-called length-interacting Arak-Surgailis polygonal Markov fields with V-shaped nodes - a continuum and isometry invariant process in the plane sharing a number of properties with the two-dimensional Ising model. For these polygonal fields we establish a low-temperature phase separation theorem in the spirit of the Dobrushin-Kotecky-Shlosma

Héctor Cancela, Ernesto Mordecki

We give an estimate of the number of geometrically distinct open tours $\G$ for a knight on a chessboard. We use a randomization of Warnsdorff rule to implement importance sampling in a backtracking scheme, correcting the observed bias of the original rule, according to the proposed principle that ``most solutions follow Warnsdorff rule most of the time'

Michael Farber, Dirk Schuetz

This paper studies the homotopy invariant $\cat(X,ξ)$ introduced in \cite{farbe2}. Given a finite cell-complex $X$, we study the function $ξ\mapsto \cat(X,ξ)$ where $ξ$ varies in the cohomology space $H^1(X;\R)$. Note that $\cat(X,ξ)$ turns into the classical Lusternik - Schnirelmann category $\cat(X)$ in the case $ξ=0$. Interest in $\cat(X,ξ)$ is based on i

Michael Farber, Dirk Schuetz

We prove that nonvanishing of the first Novikov-Betti number implies that the fundamental group contains a nonabelian free subgroup.

Laura DeMarco

Let $\MP_d$ denote the space of polynomials $f: \C \to \C$ of degree $d\geq 2$, modulo conjugation by $\Aut(\C)$. Using properties of polynomial trees (as introduced in [DM, math.DS/0608759]), we show that if $f_n$ is a divergent sequence of polynomials in $\MP_d$, then any subsequential limit of the measures of maximal entropy $m(f_n)$ will have finite supp

Michael A. van Opstall, Razvan Veliche

We find a sharp bound for the order of the automorphism group of a stable curve of genus $g$ with $3g-3$ nodes, and a sharp bound for the order of the automorphism group of such a curve with all smooth components. Combined with the results of our article math.CO/0608645 we find that graph theoretically, the cubic graph with a given number of vertices and mos

Reese Scott

Considering the equation $$a^x+b^y = c^z,$$ Le gives an upper bound on the number of solutions $(x,y,z)$, and a bound on $z$. Here we give slight improvements to these results, also removing the restriction that $a$, $b$, $c$ be squarefree.

Peter Constantin, Gautam Iyer

We discuss stochastic representations of advection diffusion equations with variable diffusivity, stochastic integrals of motion and generalized relative entropies.

Friedrich Hegenbarth, Dušan Repovš

It is well-known that an n-dimensional Poincaré complex $X^n$, $n \ge 5$, has the homotopy type of a compact topological $n$-manifold if the total surgery obstruction $s(X^n)$ vanishes. The present paper discusses recent attempts to prove analogous result in dimension 4. We begin by reviewing the necessary algebraic and controlled surgery theory. Next, we di

B. -W. Schulze, A. Volpato

The task to construct parametrices of elliptic differential operators on a manifold with edges requires a calculus of operators with a two-component principal symbolic hierarchy, consisting of (edge-degenerate) interior and (operator-valued) edge symbols. This so-called edge-algebra can be interpreted as a generalisation of the (pseudo-differential) algebra

Håkan Samuelsson

Let $f_1$, $f_2$, and $f_3$ be holomorphic functions on a complex manifold and assume that the common zero set of the $f_j$ has maximal codimension, i.e., that it is a complete intersection. We prove that the iterated Mellin transform of the residue integral has an analytic continuation to a neighborhood of the origin in $\mathbb{C}^3$. We prove also that th

Branko J. Malesevic

In the paper $λ$-method Mitrinovic-Vasic is applied aiming to improve Fink's inequality, and Shafer's inequality for arcus sinus function is observed.

Brian Rider, Balint Virag

For the plane, sphere, and hyperbolic plane we consider the canonical invariant determinantal point processes with intensity rho dnu, where nu is the corresponding invariant measure. We show that as rho converges to infinity, after centering, these processes converge to invariant H1 noise. More precisely, for all functions f in the interesection of H1(nu) an

Felice Ronga

We try to understand and justify Schubert Calculus the way Schubert did it.

Peter Friz, Nicolas Victoir

Multi-dimensional continuous local martingales, enhanced with their stochastic area process, give rise to geometric rough paths with a.s. finite homogenous p-variation, p>2. Here we go one step further and establish quantitative bounds of the p-variation norm in the form of a BDG inequality. Our proofs are based on old ideas by Lepingle. We also discuss geod

Fuquan Fang, Xiaochun Rong

Let M be a closed 5-manifold of pinched curvature 0<δ\le \text{sec}_M\le 1. We prove that M is homeomorphic to a spherical space form if M satisfies one of the following conditions: (i) δ=1/4 and the fundamental group is a non-cyclic group of order at least C, a constant. (ii) The center of the fundamental group has index at least w(δ), a constant depending

Alok Kumar Maloo

It is shown that if $A$ is a regular local ring and $I$ is a maximally differential ideal in $A$, then $I$ is generated by an $A$-sequence.

Geetika Narang, A K Agarwal

MacMahon&#39;s definition of self-inverse composition is extended to $n$-colour self-inverse composition. This introduces four new sequences which satisfy the same recurrence relation with different initial conditions like the famous Fibonacci and Lucas sequences. For these new sequences explicit formulas, recurrence relations, generating functions and a sum

Karin Baur, Simon M. Goodwin

Let $G$ be a simple algebraic group of classical type over an algebraically closed field $k$. Let $P$ be a parabolic subgroup of $G$ and let $\p = \Lie P$ be the Lie algebra of $P$ with Levi decomposition $\p = ł\oplus \u$, where $\u$ is the Lie algebra of the unipotent radical of $P$ and $ł$ is a Levi complement. Thanks to a fundamental theorem of R. W. Ric

Tamar Janelidze

We introduce relative homological and weakly homological categories, where ``relative&#39;&#39; refers to a distinguished class of normal epimorphisms. It is a generalization of homological categories, but also protomodular categories can be regarded as examples. We indicate that the relative versions of various homological lemmas can be proved in a relative

Steven G. Krantz

The Caratheodory and Kobayashi metrics have proved to be important tools in the function theory of several complex variables. But they are less familiar in the context of one complex variable. Our purpose here is to gather in one place the basic ideas about these important invariant metrics for domains in the plane and to provide some illuminating examples a

Arthur Jaffe, Gordon Ritter

We give a mathematical construction of Euclidean quantum field theory on certain curved backgrounds. We focus on generalizing Osterwalder-Schrader quantization, as these methods have proved useful to establish estimates for interacting fields on flat space-times. In this picture, a static Killing vector generates translations in Euclidean time, and physical

Hael Collins, R. Holman

We renormalize the divergences in the energy-momentum tensor of a scalar field that begins its evolution in an effective initial state. The effective initial state is a formalism that encodes the signatures of new physics in the structure of the quantum state of a field; in an inflationary setting, these signatures could include trans-Planckian effects. We t

A. Alexandrov, A. Mironov, A. Morozov

Various branches of matrix model partition function can be represented as intertwined products of universal elementary constituents: Gaussian partition functions Z_G and Kontsevich tau-functions Z_K. In physical terms, this decomposition is the matrix-model version of multi-instanton and multi-meron configurations in Yang-Mills theories. Technically, decompo

Alexander D. Popov, Martin Wolf

We describe an infinite-dimensional algebra of hidden symmetries of N=4 supersymmetric Yang-Mills (SYM) theory. Our derivation is based on a generalization of the supertwistor correspondence. Using the latter, we construct an infinite sequence of flows on the solution space of the N=4 SYM equations. The dependence of the SYM fields on the parameters along th

L. Sriramkumar, S. Shankaranarayanan

The enormous red-shifting of the modes during the inflationary epoch suggests that physics at the Planck scale may modify the standard, nearly, scale-invariant, primordial, density perturbation spectrum. Under the principle of path-integral duality, the space-time behaves as though it has a minimal length $L_{_{\rm P}}$ (which we shall assume to be of the or

D. Dalmazi, Elias L. Mendonca

The use of master actions to prove duality at quantum level becomes cumbersome if one of the dual fields interacts nonlinearly with other fields. This is the case of the theory considered here consisting of U(1) scalar fields coupled to a self-dual field through a linear and a quadratic term in the self-dual field. Integrating perturbatively over the scalar

P. V. Buividovich, V. I. Kuvshinov

We show that confinement of spinless heavy quarks in fundamental representation of $SU(N_{c})$ gauge group can be treated as decoherence of pure colour state into a white mixture of states. Decoherence rate is found to be proportional to the tension of QCD string and the distance between colour charges. The purity of colour states is calculated.

Alessandro Strumia

We discuss how leptogenesis can explain the observed baryon asymmetry and summarize attempts of testing leptogenesis. We first perform estimates and discuss the main physics, and later outline the techniques that allow to perform precise computations.

Geoffrey L. Greene, Vladimir Gudkov

In recent years, an energetic experimental program has set quite stringent limits on a possible &#34;non - 1/r^2&#34; dependence on gravity at short length scales. This effort has been largely driven by the predictions of theories based on compactification of extra spatial dimensions. It is characteristic of many such theories that the strength and length sc

W. Schäfer

The inclusive production of high-p_\perp particles (pions) in the beam fragmentation regions of high-energy hadronic collisions is driven by the breakup of valence constituents of the beam hadrons into their two-body Fock-state components,and their subsequent fragmentation. We briefly discuss an approach, that allows the consistent inclusion of intrinsic and

Christopher Smith

The theoretical status of the rare K --> pi nu nu, KL --> pi0 l+ l- and KL --> mu+ mu- decays in the Standard Model is reviewed. Their sensitivity to New Physics and their discriminating power is also illustrated.

S. Dubnicka, A. Z. Dubnickova

Special eight-resonance unitary and analytic model of nucleon electromagnetic structure is used to analyze, first the classical proton form factor data obtained by the Rosenbluth technique and then also the contradicting JLab proton polarization data on the ratio $μ_p G_{Ep}(Q^2)/G_{Mp}(Q^2)$ with the aim to investigate a manifestation of the latter on the s

Soumitra Nandi, Jyoti Prasad Saha

We discuss the implications of the recent measurement of the $B_s-\bar{B_s}$ oscillation frequency $ΔM_s$ on the parameter space of R-parity violating supersymmetry. For completeness, we also discuss the bounds coming from leptonic, semileptonic, and nonleptonic B decay modes, and point out some possibly interesting channels at LHC.

Stefan Antusch

The expected high sensitivities of future neutrino oscillation experiments will allow precision tests of unified theories of flavour. In order to compare GUT scale predictions for neutrino masses, leptonic mixing angles and CP violating phases with experimental results obtained at low energy, their renormalization group running has to be taken into account.

M. A. Belushkin, H. -W. Hammer, U. -G. Meißner

Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon for all momentum transfers. Constraints from meson-nucleon scattering data, unitarity, and perturbative QCD can be included in a straightforward way. In particular, we include the 2pi, rho-pi, and KKbar continua as independent input in our analysis and pro

B. L. Ioffe

It is demonstrated, that the calculations of current correlators at low $T$, performed in Ref.&#39;s \cite{1},\cite{2},\cite{3a} by the methods of current algebra, are correct contrary to the statements of the recent paper by Mallik \cite{3}.

Thorsten Renk

The energy loss of a hard parton is regarded as a useful tool to probe properties of a soft medium. However, the information obtained by a measurement of the nuclear suppression R_AA is not very sensitive to medium properties. Thus, more differential observables are needed. Here we focus on the pattern of angular correlation of hadrons associated with a hard

Brett Altschul

We present a method for constraining Lorentz violation in the electron sector, based on observations of the photons emitted by high-energy astrophysical sources. The most important Lorentz-violating operators at the relevant energies are parameterized by a tensor c^{nu mu) with nine independent components. If c is nonvanishing, then there may be either a max

UKQCD Collaboration, A. Hart, C. McNeile, C. Michael

We compute the masses of the flavour singlet 0++ mesons using (n_f=2) unquenched lattice QCD with the Iwasaki and Wilson gauge actions. Both fermionic and glueball interpolating operators are used to create the states. The mass of the lightest 0++ meson is suppressed relative to the mass of the 0++ glueball in quenched QCD at an equivalent lattice spacing. W

C. Alexandrou

We review the current status of lattice QCD studies of the nucleon system. In particular, we focus on the determination of the shape of the nucleon by probing its wave function as well as by evaluating the N to Delta transition form factors.

F. -P. Schilling

Highlights are presented mainly from two recent measurements of the diffractive Deep Inelastic Scattering cross section at HERA. In the first, the process $ep\to eXp$ is studied by tagging the leading final state proton. In the second, events of this type are selected by requiring a large rapidity gap devoid of hadronic activity in the proton direction. The

Jens Sören Lange

The fragmentation functions of $D^0$, $D^{\pm}$, $D_s^{\pm}$, $D^{*o}$, $D^{*\pm}$ and $Λ_c^{\pm}$ at $\sqrt{s}$$\simeq$10.6 GeV are measured with a data set of 102.7 fb$^{-1}$. Fragmentation model parametrizations (Peterson, Kartvelishvili, Collins-Spiller, Lund, and Bowler models) are compared to the data. The data at high $x$$\simeq$1 indicate a contribut

Scott A. Hughes

The inspirals of ``small&#39;&#39; ($1 - 100 M_\odot$) compact bodies through highly relativistic orbits of massive (several $\times 10^5 M_\odot -$ several $\times 10^6 M_\odot$) black holes are among the most anticipated sources for the LISA gravitational-wave antenna. The measurement of these waves is expected to map the spacetime of the larger body with

D. Bini, A. Geralico, R. Ruffini

The multiyear problem of a two-body system consisting of a Reissner-Nordström black hole and a charged massive particle at rest is here solved by an exact perturbative solution of the full Einstein-Maxwell system of equations. The expressions of the metric and of the electromagnetic field, including the effects of the electromagnetically induced gravitationa

Archana Pai

We revisit the directionally optimal data streams of LISA first introduced in Nayak etal. It was shown that by using appropriate choice of Time delay interferometric (TDI) combinations, a monochromatic fixed source in the barycentric frame can be optimally tracked in the LISA frame. In this work, we study the beaming properties of these optimal streams. We s

Spiros Cotsakis, John D. Barrow

We define the notion of a finite-time singularity of a vector field and then discuss a technique suitable for the asymptotic analysis of vector fields and their integral curves in the neighborhood of such a singularity. Having in mind the application of this method to cosmology, we also provide an analysis of the time singularities of an isotropic universe f

O. S. Duarte, A. O. Caldeira

We use the system-plus-reservoir approach to study the dynamics of a system composed of two independent Brownian particles. We present an extension of the well-known model of a bath of oscillators which is capable of inducing an effective coupling between the two particles depending on the choice made for the spectral function of the bath oscillators. The co

A. Donkov, A. V. Chubukov

Motivated by the achievements of the $X$-ray scattering technique, we analyzed the profile of the light scattering intensity $R(q, ω)$ at a finite $q$ in a 2D Heisenberg antiferromagnet. Previous Raman scattering studies at $q=0$ identified the two-magnon peak in $B_{1g}$ scattering geometry. We found that the $B_{1g}$ peak disperses downwards at a finite $q

E. Sasioglu, L. M. Sandratskii, P. Bruno

The magnetic phase diagram of the Mn-based semi-Heusler alloys is determined at T=0 using first-principles calculations in conjunction with the frozen-magnon approximation. We show that the magnetism in these systems strongly depends on the number of conduction electrons, their spin polarization and the position of the unoccupied Mn 3d states with respect to

A. Siddiki

In this work we implement the self-consistent Thomas-Fermi approach and a local conductivity model to an electron-electron bilayer system. The presence of an incompressible strip, originating from screening calculations at the top (or bottom) layer is considered as a source of an external potential fluctuation to the bottom (or top) layer. This essentially y

S. Graser, T. Dahm

We study the influence of multiple bands on the properties of Josephson junctions. In particular we focus on the two gap superconductor magnesium diboride. We present a formalism to describe tunneling at a point contact between two MgB2 electrodes generalizing the transfer-matrix approach to multiple bands. A simple model is presented to determine the effect

Nick S. Norberg, Gustavo M. Dalpian, James R. Chelikowsky, Daniel R. Gamelin

Spectroscopic data demonstrate that impurity D/A levels in doped semiconductor nanostructures are energetically pinned, resulting in variations in D/A binding energies with increasing quantum confinement. Using magnetic circular dichroism spectroscopy, the donor binding energies of Co2+ ions in colloidal ZnSe quantum dots have been measured as a function of

Roberto B. Diener, Tin-Lun Ho

We show that the quantum evolution of a spin-1 Bose gas with nearly all bosons initially in the $F_z = 0$ state has a &#34;quantum carpet&#34; {\em spin-time} structure with self-similar properties. The system continuously evolves into &#34;multi-peaked&#34; Schrödinger cat like states, returning occasionally to coherent structures, which leads to large numb

Efim A. Brener, V. I. Marchenko, R. Spatschek

We consider a sharp interface kinetic model of phase transitions accompanied by elastic strain, together with its phase-field realization. Quantitative results for the steady-state growth of a new phase in a strip geometry are obtained and different pattern formation processes in this system are investigated.

Daniel Bonamy, Silke Prades, Cindy Rountree, Laurent Ponson

We report here atomic force microscopy experiments designed to uncover the nature of failure mechanisms occuring within the process zone at the tip of a crack propagating into a silica glass specimen under stress corrosion. The crack propagates through the growth and coalescence of nanoscale damage spots. This cavitation process is shown to be the key mechan

S. M. Shapiro, P. Vorderwisch, K. Habicht, K. Hrdil

An inelastic neutron scattering study of the lattice dynamics of the martensite phase of the ferromagnetic shape memory alloy, Ni2MnGa, reveals the presence of well-defined phasons associated with the charge density wave (CDW) resulting from Fermi surface (FS) nesting. The velocity and the temperature dependence of the phason are measured as well as the anom

Wang-Kong Tse, S. Das Sarma

Employing diagrammatic perturbation theory, we calculate the (charge) Coulomb drag resistivity $ρ_D$ and spin Coulomb drag resistivity $ρ_{\uparrow\downarrow}$ in the presence of Rashba spin-orbit coupling. Analytical expressions for $ρ_D$ and $ρ_{\uparrow\downarrow}$ are derived, and it is found that spin-orbit interaction produces a small enhancement to $ρ

M. V. Katkov, Y. V. Pershin, C. Piermarocchi

We consider a semiconductor polymer chain coupled to a single electromagnetic mode in a cavity. The excitations of the chain have a mixed exciton-photon character and are described as polaritons. Polaritons are coupled to the lattice by the deformation potential interaction and can propagate in the chain. We find that the presence of optical excitation in th

X. Gratens, L. Mendonca Ferreira, Y. Kopelevich, N. F. Oliveira

Magnetization measurements were performed on CeCoIn_5 at temperature down to 30 mK with the magnetic field applied in three different orientations: parallel, near parallel ($\sim$ 10$^{0}$ rotated) and perpendicular to the ab-plane. For these three orientations we have observed crossover features in the torque/magnetization traces at fields just below $H_{c2

F. Muñoz-Rojas, D. Jacob, J. Fernández-Rossier, J. J. Palacios

We study the effect of a structural nanoconstriction on the coherent transport properties of otherwise ideal zig-zag-edged infinitely long graphene ribbons. The electronic structure is calculated with the standard one-orbital tight-binding model and the linear conductance is obtained using the Landauer formula. We find that, since the zero-bias current is ca

M. Dieskova, M. Konopka, P. Bokes

Interfaces between metals based on AlO$_{x}$ represent the most popular basis for Josephson junctions or, more recently, also for junctions exhibiting substantial tunneling magneto-resistance. We have performed a computational study of possible local geometric structures of such interfaces at the ab-initio DFT/GGA level of approximation to complement recent

Vladimir A. Baulin, Carlos M. Marques, Fabrice Thalmann

The dynamic behavior of microtubules in solution can be strongly modified by interactions with walls or other structures. We examine here a microtubule growth model where the increase in size of the plus-end is perturbed by collisions with other microtubules. We show that such a simple mechanism of constrained growth can induce ordered structures and pattern

K. H. Lee, K. Y. Michael Wong

We consider a population of agents competing for finite resources using strategies based on two channels of signals. The model is applicable to financial markets, ecosystems and computer networks. We find that the dynamics of the system is determined by the correlation between the two channels. In particular, occasional mismatches of the signals induce a ser

Riccardo Fantoni, Domenico Gazzillo, Achille Giacometti, Peter Sollich

We study the effects of size polydispersity on the gas-liquid phase behaviour of mixtures of sticky hard spheres. To achieve this, the system of coupled quadratic equations for the contact values of the partial cavity functions of the Percus-Yevick solution is solved within a perturbation expansion in the polydispersity, i.e. the normalized width of the size

K. Palotas, W. A. Hofer

In this paper we revisit the Levy-Perdew-Sahni equation. We establish that the relation implicitly contains the conservation of energy density at every point of the system. The separate contributions to the total energy density are described in detail, and it is shown that the key difference to standard density functional methods is the existence of a genera

B. D. Gerardot, S. Seidl, P. A. Dalgarno, R. J. Warburton

The fine structure of the neutral exciton in a single self assembled InGaAs quantum dot is investigated under the effect of a lateral electric field. Stark shifts up to 1.5 meV, an increase in linewidth, and a decrease in photoluminescence intensity were observed due to the electric field. We show that the lateral electric field strongly affects the exciton

L. Petit, G. M. Stocks, T. Egami, Z. Szotek

The ab initio self-interaction-corrected local-spin-density approximation is used to study the electronic structure of both stoichiometric and non-stoichiometric nickelates. From total energy considerations it emerges that, in their ground-state, both LiNiO2 and NaNiO2 are insulators, with the Ni ion in the Ni3+ low spin state (6t2g 1eg) configuration. It is

Olivier Bourgeois, T. Fournier, J. Chaussy

We have performed thermal conductance measurements on individual single crystalline silicon suspended nanowires. The nanowires (130 nm thick and 200 nm wide) are fabricated by e-beam lithography and suspended between two separated pads on Silicon On Insulator (SOI) substrate. We measure the thermal conductance of the phonon wave guide by the 3&#61559; method

Timo Hyart, Natalia V. Alexeeva, Ahti Leppanen, Kirill N. Alekseev

We theoretically show that conditions for THz gain and conditions for formation of destructive electric domains in semiconductor superlattices are fairly different in the case of parametric generation and amplification. Action of an unbiased high-frequency electric field on a superlattice causes a periodic variation of energy and effective mass of miniband e

Hiroshi Kori, Alexander S. Mikhailov

Entrainment of randomly coupled oscillator networks by periodic external forcing applied to a subset of elements is numerically and analytically investigated. For a large class of interaction functions, we find that the entrainment window with a tongue shape becomes exponentially narrow for networks with higher hierarchical organization. However, the entrain

David Parker, Stephan Haas

It is usually believed that a coherence peak just below T$_{c}$ in the nuclear spin lattice relaxation rate T$_{1}^{-1}$ in superconducting materials is a signature of conventional s-wave pairing. In this paper we demonstrate that any unconventional superconductor obeying BCS pure-case weak-coupling theory should show a small T$_{1}^{-1}$ coherence peak near

Chandra Shekhar, Rajiv Giri, S. K. Malik*, O N Srivastava

In the present study, we report a systematic study of doping/ admixing of carbon nanotubes (CNTs) in different concentrations in MgB2. The composite material corresponding to MgB2+ x at.%CNTs (35 at.% > x > 0 at.%) have been prepared by solid-state reaction at ambient pressure. All the samples in the present investigation have been subjected to structural/ m

Takuma Ohashi, Sei-ichiro Suga, Norio Kawakami, Hirokazu Tsunetsugu

We study the magnetic properties around the Mott transition in the Kagomé lattice Hubbard model by the cellular dynamical mean field theory combined with quantum Monte Carlo simulations. By investigating the q-dependence of the susceptibility, we find a dramatic change of the dominant spin fluctuations around the Mott transition. The spin fluctuations in the

Masahide Nishiyama, Takayuki Kato, Hitoshi Sugawara, Daisuke Kikuchi

We have carried out nuclear quadrupole resonance (NQR) measurements in the filled skutterudite compounds Pr(Os$_{1-x}$Ru$_x$)$_4$Sb$_{12}$ ($x=0.1, 0.2$), in order to gain insights into the symmetry of the superconducting gap function. Upon replacing Os with Ru, the spin-lattice relaxation rate $1/T_1$ becomes proportional to temperature ($T$) at low $T$ far

S. K. Sikka

In situ high pressure neutron diffraction measured lengths of O H and H O pairs in hydrogen bonds in substances are shown to follow the correlation between them established from 0.1 MPa data on different chemical compounds. In particular, the conclusion by Nelmes et al that their high pressure data on ice VIII differ from it is not supported. For compounds i

Derek Walton

Dilute magnetic nanoparticle systems exhibit slow dynamics [1] due to a broad distribution of relaxation times that can be traced to a correspondingly broad distribution of particle sizes [1]. However, at higher concentrations interparticle interactions lead to a slow dynamics that is qualitatively indistinguishable from that dislayed by atomic spin glasses.

E. Guilmeau, M. Pollet, D. Grebille, M. Hervieu

This paper has been withdrawn

Karel A. van der Hucht

This paper gathers, from the literature and private communication, 72 new Galactic Population I Wolf-Rayet stars and 17 candidate WCLd stars, recognized and/or discovered after the publication of The VIIth Catalogue of Galactic Wolf-Rayet Stars. This brings the total number of known Galactic Wolf-Rayet stars to 298, of which 24 (8%) are in open cluster Weste

Masanori Nakamura, Hui Li, Shengtai Li

Stability properties of ``magnetic tower&#39;&#39; jets propagating in the gravitationally stratified background have been examined by performing three-dimensional magnetohydrodynamic simulations. The current-carrying, Poynting flux-dominated magnetic tower jet, which possesses a highly wound helical magnetic field, is subject to the current-driven instabili

Yosuke Mizuno, Ken-Ichi Nishikawa, Shinji Koide, Philip Hardee

We have developed a new three-dimensional general relativistic magnetohydrodynamic (GRMHD) code, RAISHIN, using a conservative, high resolution shock-capturing scheme. The numerical fluxes are calculated using the Harten, Lax, & van Leer (HLL) approximate Riemann solver scheme. The flux-interpolated, constrained transport scheme is used to maintain a diverge

D. R. Ballantyne, Y. Shi, G. H. Rieke, J. L. Donley

Deep X-ray surveys by Chandra and XMM-Newton have resolved about 80% of the 2-10 keV cosmic extragalactic X-ray background (CXRB) into point sources, the majority of which are obscured AGN. The obscuration might be connected to processes within the host galaxy, possibly the star-formation rate. Here, we use the results of CXRB synthesis calculations as input

Andrew A. West, John J. Bochanski, Suzanne L. Hawley, Kelle L. Cruz

We present a spectroscopic study and dynamical analysis of ~2600 M7 dwarfs. We confirm our previous finding that the fraction of magnetically active stars decreases with vertical distance from the Galactic plane. We also show that the mean luminosity of the H-alpha emission has a small but statistically significant decrease with distance. Using space motions

Ralph C. Bohlin

Free of any atmospheric contamination, HST provides the best available spectrophotometry from the far-UV to the near-IR for stars as faint as V~16. The HST CALSPEC standard star network is based on 3 standard candles: the hot, pure hydrogen white dwarf (WD) stars G191B2B, GD153, and GD71, which have Hubeny NLTE model flux calculations that require the atomic

Xiaofeng Tan

A novel theoretical method is developed to study the polycyclic aromatic hydrocarbon - diffuse interstellar band (PAH-DIB) hypothesis. In this method, a computer program is used to enumerate all PAH molecules with up to a specific number of fused benzene rings. Fast quantum chemical calculations are then employed to calculate the electronic transition energi

Markus Boettcher

Blazars are the most violent steady/recurrent sources of high-energy gamma-ray emission in the known Universe. They are prominent emitters of electromagnetic radiation throughout the entire electromagnetic spectrum. The observable radiation most likely originates in a relativistic jet oriented at a small angle with respect to the line of sight. This review s

Cuihua Du, Jun Ma, Zhenyu Wu, Xu Zhou

We present an analysis of the photometric parallaxes of stars in 21 BATC fields carried out with the National Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope in 15 intermediate-band filters from 3000 to 10000 Å. In this study, we have adopted a three-component (thin disk, thick disk and halo) model to analyze star counts information. By calculat

J. Hong, J. E. Grindlay, N. Chammas, A. Copete

We describe the detector development for a balloon-borne wide-field hard X-ray (20 - 600 keV) telescope, ProtoEXIST. ProtoEXIST is a pathfinder for both technology and science of the proposed implementation of the Black Hole Finder Probe, Energetic X-ray Imaging Survey telescope (EXIST). The principal technology challenge is the development of large area, cl

A. A. Djupvik, Ph. Andre, S. Bontemps, F. Motte

Aims. The aim of this paper is to characterise the star formation activity in the poorly studied embedded cluster Serpens/G3-G6, located ~ 45&#39; (3 pc) to the south of the Serpens Cloud Core, and to determine the luminosity and mass functions of its population of Young Stellar Objects (YSOs). Methods. Multi-wavelength broadband photometry was obtained to s

Paul D. Feldman, S. Alan Stern, Andrew J. Steffl, Joel Wm. Parker

We report on spectroscopic observations of periodic comet 9P/Tempel 1 by the Alice ultraviolet spectrograph on the Rosetta spacecraft in conjunction with NASA&#39;s Deep Impact mission. Our objectives were to measure an increase in atomic and molecular emissions produced by the excavation of volatile sub-surface material. We unambiguously detected atomic oxy

Gianfranco Bertone

We review the status of indirect Dark Matter searches, focusing in particular on the connection with gamma-ray Astrophysics, and on the prospects for detection with the upcoming space telescope GLAST and Air Cherenkov Telescopes such as CANGAROO, HESS, MAGIC and VERITAS. After a brief introduction where we review the fundamental motivations for indirect sear

A. K. Pandey, S. Sharma, K. Ogura

We present colour-magnitude diagrams of open clusters, located in the range $112^\circ < l < 252^\circ$, manifesting stellar populations in the background of clusters. Some of the populations are found to be located beyond the Perseus arm and may be the part of Norma-Cygnus (outer) arm. The outer arm seems to be continued from $l\sim120^\circ$ to $l\sim235^\