March 2008 arXiv papers — page 36

Mauricio Cataldo, Patricio Mella, Paul Minning, Joel Saavedra

We provide a detailed description for power--law scaling Friedmann-Robertson-Walker cosmological scenarios dominated by two interacting perfect fluid components during the expansion. As a consequence of the mutual interaction between the two fluids, neither component is conserved separately and the energy densities are proportional to $1/t^{2}$. It is shown

C. Noel, S. Goriely, Y. Busegnies, M. V. Papalexandris

We construct a new reduced nuclear reaction network able to reproduce the energy production due to the photo-disintegration of heavy elements such as Ru, which are believed to occur during superbursts in mixed H/He accreting systems. We use this network to simulate a detonation propagation, inside a mixture of C/Ru. As our reference, we use a full nuclear re

Yuha Kobayashi, Takahiro Onimaru, Marcos A. Avila, Kenzo Sasai

The Kondo lattice antiferromagnet YbNiSi3 was investigated by neutron scattering. The magnetic structure of YbNiSi3 was determined by neutron diffraction on a single-crystalline sample. Inelastic scattering experiments were also performed on a pulverized sample to study the crystalline electric field (CEF) excitations. Two broad CEF excitations were observed

N. Pinilla-ALonso, R. Brunetto, J. Licandro, R. Gil-Hutton

2003 EL61 is the largest member of a group of TNOs with similar orbits and 'unique' spectra (neutral slope in the visible and the deepest water ice absorption bands ever observed in the TNb). Studying the composition of the surface of 2003 EL61 provides useful constrains on the origin of this particular group of TNOs and on the outer Solar system&#39

Yu. T. Petrusenko, A. V. Bondarenko, A. A. Zavgorodniy, M. A. Obolenskii

We show that rotation of the magnetic field off the plane of twin boundaries (TB's) induces transition of an ordered vortex solid phase to a disordered one. This transition arises due to appearance of transverse deformations of vortex lines near the TB's, $u_{t,TB}$, the amplitude of which satisfies the Lindemann criteria, $u_{t,rp}=c_La_0$. This ord

L. Cagliero, N. Rojas

Given a Lie algebra $\mathfrak{g}$ over a field of characteristic zero $k$, let $μ(\mathfrak{g})=\min\{\dim π: π\text{is a faithful representation of}\mathfrak{g}\}$. Let $\mathfrak{h}_{m}$ be the Heisenberg Lie algebra of dimension $2m+1$ over $k$ and let $k[t]$ be the polynomial algebra in one variable. Given $m\in\mathbb{N}$ and $p\in k[t]$, let $\mathfra

Martin Schumacher

It is shown that the scalar mesons $σ$, $f_0(980)$ and $a_0(980)$ as $t$-channel exchanges quantitatively solve the problem of diamagnetism and give an explanation of the large missing part of the electric polarizability $α$ showing up when only the pion cloud is taken into account. The electric polarizability of the proton $α_p$ confirms a two-photon width

Fabrizio Anfuso, Markus Garst, Achim Rosch, Oliver Heyer

Magnetostriction and thermal expansion of the spin-ladder compound piperidinium copper bromide (C$_5$H$_{12}$N)$_2$CuBr$_4$ are analyzed in detail. We find perfect agreement between experiments and the theory of a two-leg spin ladder Hamiltonian for more than a decade in temperature and in a wide range of magnetic fields. Relating the magnetostriction along

A. Huke, K. Czerski, S. M. Chun, A. Biller

In antecedent experiments the electron screening energies of the d+d reactions in metallic environments have been determined to be enhanced by an order of magnitude in comparison to the case of gaseous deuterium targets. The analytical models describing averaged material properties have not been able to explain the experimental results so far. Therefore, a f

Sid Ahmed Sabeur, Fatima Hamdache, Friederike Schmid

Using Langevin simulations, we find that simple 'generic' bead-and-spring homopolymer chains in a sufficiently bad solvent spontaneously develop helical order during the process of collapsing from an initially stretched conformation. The helix formation is initiated by the unstable modes of the straight chain, which drive the system towards a long-li

L. Zschiedrich, S. Burger, A. Schädle, F. Schmidt

Rigorous computer simulations of propagating electromagnetic fields have become an important tool for optical metrology and design of nanostructured optical components. A vectorial finite element method (FEM) is a good choice for an accurate modeling of complicated geometrical features. However, from a numerical point of view solving the arising system of li

Antonio Di Crescenzo, Barbara Martinucci

Motivated by applications in mathematical biology concerning randomly alternating motion of micro-organisms, we analyze a generalized integrated telegraph process. The random times between consecutive velocity reversals are gamma-distributed, and perform an alternating renewal process. We obtain the probability law and the mean of the process.

Michael Beasley, Terry Bridges, Eric Peng, William E. Harris

We have performed a spectroscopic study of globular clusters (GCs) in the giant elliptical NGC 5128 using the 2dF facility at the Anglo-Australian telescope. We obtained integrated optical spectra for a total of 254 GCs, 79 of which are newly confirmed on the basis of their radial velocities and spectra. In addition, we obtained an integrated spectrum of the

Weiliang Wang, Jie Peng, Guihua Chen, Shaozhi Deng

We calculated the image potentials of single-walled carbon nanotubes of various structures in the condition of field emission with a quantum chemistry method. The image potential of the single-walled carbon nanotubes can be well fitted with the image potential of an ideal metal sphere in a size comparable to an atom. The image potential is not sensitive to b

Jennifer Hatchell, Gary Fuller

In our SCUBA survey of Perseus, we find that the fraction of protostellar cores increases towards higher masses and the most massive cores are all protostellar. In this paper we consider the possible explanations of this apparent mass dependence in the evolutionary status of these cores, and the implications for protostellar evolution and the mapping of the

Bengt Eliasson

We present a full-scale simulation study of a generalized Zakharov model for the generation of the topside electrostatic turbulence due to the parametric instability during ionospheric heating experiments near the F region peak. The nonlinear tunneling of electromagnetic waves through the ionospheric layer is attributed to multiple-stage parametric decay and

R. Alvargonzalez, L. S. Soto

The energy flow of zero-point radiation is very great, but difficult to put to use. However, the observations made by Sparnaay in 1958 and by Lamoureux in 1997 reveal the possibility of making use of a very small fraction of that immense amount. This possibility is big enough for such a minute fraction to have significant importance, but such a possibility r

M. N. Chernodub

Chiral monopoles are hedgehoglike structures in local chiral condensates in QCD. These monopoles are (i) made of quark and gluon fields; (ii) explicitly gauge-invariant; and (iii) they carry quantized and conserved chromomagnetic charge. We argue that the chiral condensate vanishes in a core of the chiral monopole while the density of these monopoles increas

Antonio Gonzalez, Antonio Ramos, Pablo Garcia-Sanchez, Antonio Castellanos

We analyze the AC electro-osmotic motion of a 1:1 aqueous solution, taking into account the difference in mobilities and diffusion coefficients between positive and negative ions. This model serves to understand the behavior of common systems as a solution of NaCl in water. We pay special attention to two cases. First, the case of slightly different mobiliti

P. Jovanović, L. Č. Popović

Here we discuss the effects of strong gravity that can be observed in electromagnetic spectra of active galactic nuclei (AGN). According to the unification model of an AGN, there is a supermassive black hole ($10^7 - 10^9 M_\odot$) in its center, surrounded by an accretion disk that radiates in the X-ray band. Accretion disks could have different forms, dime

Helmut Friedrich

Extending the results of an earlier article we give a complete description of the asymptotically flat, conformally non-flat, static vacuum data which admit non-trivial, asymptotically smooth conformal mappings onto other such data. These data form a 3-parameter family which decomposes into 1-parameter families of data which are conformal to each other. The d

A. A. Saberi, M. D. Niry, S. M. Fazeli, M. R. Rahimi Tabar

The statistics of the iso-height lines in (2+1)-dimensional Kardar-Parisi-Zhang (KPZ) model is shown to be conformal invariant and equivalent to those of self-avoiding random walks. This leads to a rich variety of new exact analytical results for the KPZ dynamics. We present direct evidence that the iso-height lines can be described by the family of conforma

B. Wunsch, T. Stauber, F. Sols, F. Guinea

We analyze interaction effects on boundary states of single layer graphene. Near a half filled band, both short and long-ranged interactions lead to a fully spin polarized configuration. In addition, the band of boundary states acquires a finite dispersion as function of the momentum parallel to the edge, induced by the interactions. Away from half filling t

Sanjeev K. Gupta, Satyaprakash Sahoo, Prafulla K. Jha, A. K. Arora

Phonon modes found in low frequency Raman scattering from $CdS_{1-x}Se_x$ nanocrystals embedded in borosilicate glass arising from confined acoustic phonons are investigated. In addition to the breathing modes and quadrupolar modes, two additional modes are found in the spectra. In order to assign the new modes, confined acoustic phonon frequencies are calcu

T. A. Carroll, M. Kopf

AIMS :The thermodynamic and magnetic field structure of the solar photosphere is analyzed by means of a novel 3-dimensional spectropolarimetric inversion and reconstruction technique. METHODS : On the basis of high-resolution, mixed-polarity magnetoconvection simulations, we used an artificial neural network (ANN) model to approximate the nonlinear inverse m

E. Roediger, G. Hensler

Ram pressure stripping, i.e. the removal of a galaxy's gas disk due to its motion through the intracluster medium of a galaxy cluster, appears to be a common phenomenon. Not every galaxy, however, is completely stripped of its gas disk. If the ram pressure is insufficiently strong, only the outer parts of the gas disk are removed, and the inner gas disk

R. Schnalle, J. Schnack

The energy spectra of mesoscopic, i.e. few-body quantum systems are of great interest in several areas of physics such as nuclear physics, cluster physics or magnetism. One way to obtain an approximate spectrum is to diagonalize with reduced but carefully chosen basis sets. In this Letter we propose for the case of mesoscopic antiferromagnets to use the eige

C. Bersier, A. Floris, A. Sanna, G. Profeta

We report first-principles calculations on the normal and superconducting state of CaBe(x)Si(2-x) (x=1), in the framework of density functional theory for superconductors (SCDFT). CaBeSi is isostructural and isoelectronic to MgB2 and this makes possible a direct comparison of the electronic and vibrational properties and the electron-phonon interaction of th

A. V. Taichenachev, V. I. Yudin, V. D. Ovsiannikov, V. G. Pal'chikov

Frequency light shifts resulting from the localization effects and effects of the quantization of translational atomic motion in an optical lattice is studied for a forbidden optical transition $J$=0$\to$$J$=0. In the Lamb-Dicke regime this shift is proportional to the square root from the lattice field intensity. With allowance made for magneto-dipole and q

H. Kumano, H. Kobayashi, S. Ekuni, Y. Hayashi

High degree of preservation of spin states during energy relaxation processes mediated by optical phonons is demonstrated in a single quantum dot. Optical-phonon resonance and relevant suppression of spin relaxation are clearly identified as dip structures in photoluminescence excitation spectra probed by the positive trion emission. The absence of continuum

F. Haas, P. K. Shukla, B. Eliasson

We present an investigation for the generation of intense magnetic fields in dense plasmas with an anisotropic electron Fermi-Dirac distribution. For this purpose, we use a new linear dispersion relation for transverse waves in the Wigner-Maxwell dense quantum plasma system. Numerical analysis of the dispersion relation reveals the scaling of the growth rate

Xiao-Ming Lu, Xiaoguang Wang, Yang Yang, Jian Chen

We extend the former matrix rearrangement approach of the entangling power to the general cases, without the requirement of the same dimensions of the subsystems. The entangling power of a unitary operator is completely determined by its realignment and partial transposition. As applications, we calculate the entangling power for the Ising interaction and th

Cisco Gooding, Andrei V. Frolov

We study scattering and capture of particles by a rotating black hole in the five-dimensional spacetime described by the Myers-Perry metric. The equations of geodesic motion are integrable, and allow us to calculate capture conditions for a free particle sent towards a black hole from infinity. We introduce a three-dimensional impact parameter describing asy

Giovanni Peccati

We point out that a proper use of the Hoeffding--ANOVA decomposition for symmetric statistics of finite urn sequences, previously introduced by the author, yields a decomposition of the space of square-integrable functionals of a Dirichlet--Ferguson process, written $L^2(D)$, into orthogonal subspaces of multiple integrals of increasing order. This gives an

Mikhail P. Kharlamov

Consider a rigid body having a fixed point in a superposition of two constant force fields (for example, gravitational and magnetic). Introducing the condition of Kowalevski type, O.I.Bogoyavlensky (1984) has found the first integral generalizing that of Kowalevski and pointed out the integrable case with two invariant relations, which reduces to the 1st App

M. Kriener, Y. Maeno, T. Oguchi, Z. -A. Ren

The discoveries of superconductivity in the heavily-boron doped semiconductors diamond (C:B) in 2004 and silicon (Si:B) in 2006 have renewed the interest in the physics of the superconducting state of doped semiconductors. Recently, we discovered superconductivity in the closely related ''mixed'' system heavily boron-doped silcon carbide (SiC

Tadashi Wadayama

Asymptotic concentration behaviors of linear combinations of weight distributions on the random linear code ensemble are presented. Many important properties of a binary linear code can be expressed as the form of a linear combination of weight distributions such as number of codewords, undetected error probability and upper bound on the maximum likelihood e

Mikhail P. Kharlamov

We consider the analogue of the 4th Appelrot class of motions of the Kowalevski top for the case of two constant force fields. The trajectories of this family fill the four-dimensional surface O^4 in the six-dimensional phase space. The constants of three first integrals in involution restricted to this surface fill one of the sheets of the bifurcation diagr

Naoki Masuda

Game dynamics in which three or more strategies are cyclically competitive, as represented by the rock-scissors-paper game, have attracted practical and theoretical interests. In evolutionary dynamics, cyclic competition results in oscillatory dynamics of densities of individual strategists. In finite-size populations, it is known that oscillations blow up u

Nicola Garofalo

We prove some new a priori estimates for H_2-convex functions which are zero on the boundary of a bounded smooth domain Ωin a Carnot group G. Such estimates are global and are geometric in nature as they involve the horizontal mean curvature \mathcal H of the boundary of Ω. As a consequence of our bounds we show that if G has step two, then for any smooth $H

K. L. Luhman, L. E. Allen, P. R. Allen, R. A. Gutermuth

We present a census of circumstellar disks in the Chamaeleon I star-forming region. Using the Infrared Array Camera and the Multiband Imaging Photometer onboard the Spitzer Space Telescope, we have obtained images of Chamaeleon I at 3.6, 4.5, 5.8, 8.0, and 24 um. To search for new disk-bearing members of the cluster, we have performed spectroscopy on objects

Jie Gao, Fangwen Sun, Chee Wei Wong

We propose a scheme to realize controlled phase gate between two single photons through a single quantum dot in slow-light silicon photonic crystal waveguide. Enhanced Purcell factor and beta factor lead to high gate fidelity over broadband frequencies compared to cavity-assisted system. The excellent physical integration of this silicon photonic crystal wav

Ching-Lung Lin, Sei Nagayasu, Jenn-Nan Wang

In this paper we study the local behavior of a solution to the $l$th power of Laplacian with singular coefficients in lower order terms. We obtain a bound on the vanishing order of the nontrivial solution. Our proofs use Carleman estimates with carefully chosen weights. We will derive appropriate three-sphere inequalities and apply them to obtain doubling in

Lin Chen, Yi-Xin Chen

We prove that the bipartite entangled state of rank three is distillable. So there is no rank three bipartite bound entangled state. By using this fact, We present some families of rank four states that are distillable. We also analyze the relation between the low rank state and the Werner state.

Hantao Ji, Philipp Kronberg, Stewart C. Prager, Dmitri A. Uzdensky

This paper provides a concise summary of the current status of the research and future perspectives discussed in the Mini-Conference on Angular Momentum Transport in Laboratory and Nature. This Mini-conference, sponsored by the Topical Group on Plasma Astrophysics, was held as part of the American Physical Society's Division of Plasma Physics 2007 Annual

Adriana Buica, Jaume Llibre, Oleg Makarenkov

The smooth second Bogolyubov's theorem is generalized for Lipschitz systems.

Oleg Makarenkov

Let $y=f(x)$ be a continuously differentiable implicit function solving the equation $F(x,y)=0$ with continuously differentiable $F.$ In this paper we show that if $F_\eps$ is a Lipschitz function such that the Lipschitz constant of $F_\eps-F$ goes to 0 as $\eps\to 0$ then the equation $F_\eps(x,y)=0$ has a Lipschitz solution $y=f_\eps(x)$ such that the Lips

Edmundo M. Monte

The braneworld theory appear with the purpose of solving the problem of the hierarchy of the fundamental interactions. The perspectives of the theory emerge as a new physics, for example, deviation of the law of Newton's gravity. One of the principles of the theory is to suppose that the braneworld is local submanifold in a space of high dimension, the b

Rodrigo Costas, Maria Bordons, Thed N. van Leeuwen, Anthony F. J. van Raan

The representation of science as a citation-density landscape and the study of scaling rules with the field-specific citation-density as a main topological property was previously analysed at the level of research groups. Here the focus is on the individual researcher. In this new analysis, the size-dependence of several main bibliometric indicators for a la

S. Chadov, J. Minár, M. I. Katsnelson, H. Ebert

The influence of correlation effects on the orbital moments for transition metals and their alloys is studied by first-principle relativistic Density Functional Theory in combination with the Dynamical Mean-Field Theory. In contrast to the previous studies based on the orbital polarization corrections we obtain an improved description of the orbital moments

Erin De Pree, Marc Sher, Ismail Turan

A sequential fourth generation of quarks and leptons is allowed by precision electroweak constraints if the mass splitting between the heavy quarks is between 50 and 80 GeV. Although heavy quarks can be easily detected at the LHC, it is very difficult to detect a sequential heavy charged lepton, L, due to large backgrounds. Should the L mass be above 250 GeV

Jesus Guillera

In 1987 Jonathan and Peter Borwein, inspired by the works of Ramanujan, derived many efficient algorithms for computing $π$. We will see that by using only a formula of Gauss's and elementary algebra we are able to prove the correctness of two of them.

P. D. Gujrati

We show that Poincare recurrence does not mean that the entropy will eventually decrease, contrary to the claim of Zermelo, and that the probabilitistic origin in statistical physics must lie in the external noise, and not the preparation of the system.

Joshua Frieman, Michael Turner, Dragan Huterer

The discovery ten years ago that the expansion of the Universe is accelerating put in place the last major building block of the present cosmological model, in which the Universe is composed of 4% baryons, 20% dark matter, and 76% dark energy. At the same time, it posed one of the most profound mysteries in all of science, with deep connections to both astro

K. I. Caputi, S. J. Lilly, H. Aussel, D. Sanders

We study zCOSMOS-bright optical spectra for 609 Spitzer/MIPS 24 micron-selected galaxies with S(24um)> 0.30 mJy and I<22.5 (AB mag) over 1.5 sq. deg. of the COSMOS field. From emission-line diagnostics we find that: 1) star-formation rates (SFR) derived from the observed Halpha and Hbeta lines underestimate, on average, the total SFR by factors ~5 and 10, re

Joel C. Miller

We consider an infectious disease spreading along the edges of a network which may have significant clustering. The individuals in the population have heterogeneous infectiousness and/or susceptibility. We define the out-transmissibility of a node to be the marginal probability that it would infect a randomly chosen neighbor given its infectiousness and the

N. Kaiser, J. M. Friedrich

We review the cross sections for low-energy $π^- γ$ reactions in the framework of chiral perturbation theory. Charged pion Compton scattering, $π^- γ\to π^-γ$, is considered up to one-loop order where the pion&#39;s internal structure enters through the difference of the electric and magnetic pion polarizability, $α_π- β_π$. The ongoing COMPASS experiment ai

J. L. Cardoso, P. Pereyra

Analyzing spin transport of quasi-2D electrons gas moving through a semiconductor wave guide subject to a sectionally homogeneous tilted magnetic field, we found well-defined selection rules for resonant and antiresonant spin carrier transmission. Based on these selection rules and the band shift induced by the magnetic field strength and the tilting angles,

R. Centeno, H. Socas-Navarro

In this work we present new data that sets strong constraints on the solar oxygen abundance. Our approach, based on the analysis of spectro-polarimetric observations, is almost model-independent and therefore extremely robust. The asymmetry of the Stokes V profile of the 6300 A [OI] and NiI blend is used as an indicator of the relative abundances of these tw

L. Stawarz, V. Petrosian

Here we investigate some aspects of stochastic acceleration of ultrarelativistic electrons by magnetic turbulence. In particular, we discuss the steady-state energy spectra of particles undergoing momentum diffusion due to resonant interactions with turbulent MHD modes, taking rigorously into account direct energy losses connected with different radiative co

S. K. Donaldson

This is an expository article. Among other topics, we discuss the existence of Kahler-Ricci soliton metrics on toric Fano manifolds, and Kahler-Einstein metrics on deformations of the Mukai-Umemura 3-fold

K. H. C. Castello-Branco, A. G. Martins

We study the free-fall of a quantum particle in the context of noncommutative quantum mechanics (NCQM). Assuming noncommutativity of the canonical type between the coordinates of a two-dimensional configuration space, we consider a neutral particle trapped in a gravitational well and exactly solve the energy eigenvalue problem. By resorting to experimental d

Raymond Mortini, Amol Sasane, Brett D. Wick

Let $B$ be a Blaschke product. We prove in several different ways the corona theorem for the algebra $H^\infty_B:=\mC+BH^\infty$. That is, we show the equivalence of the classical {\em corona condition} on data $f_1, ..., f_n \in H^\infty_B$: \[ \forall z \in \mD, \sum_{k=1}^{n} |f_k(z)| \geq δ>0, \] and the {\em solvability of the Bezout equation} for $g_1,

M. Davier, S. Descotes-Genon, A. Hocker, B. Malaescu

We revisit the determination of alpha_s(m_tau) using a fit to inclusive tau hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K_4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e- annihilation cross sections, which decrease the uncertainty in the separation of

John A. Toth

We show that for a quantum completely integrable system in two dimensions,the $L^{2}$-normalized joint eigenfunctions of the commuting semiclassical pseudodifferential operators satisfy restriction bounds ofthe form $ \int_γ |ϕ_{j}^{\hbar}|^2 ds = {\mathcal O}(|\log \hbar|)$ for generic curves $γ$ on the surface. We also prove that the maximal restriction bo

S. Khlebnikov

In a short superconducting nanowire connected to bulk superconducting leads, quantum phase slips behave as a system of linearly (as opposed to logarithmically) interacting charges. This system maps onto quantum mechanics of a particle in a periodic potential. We show that, while the state with a high density of phase slips is not a true insulator (a conseque

David Brown

We extend the refined version of the Chabauty-Coleman bound on the number of rational points on a curve of genus g>1 to the case of bad reduction.

Mark Sterling

The action of a finite reflection group (type A) on its set of roots is understood as a permutation representation or group action. We show that this representation is an induced representation from a certain kind of parabolic subgroup. Furthermore, we use this representation to define a statistic (derived from the length function) on the set of roots. A pos

T. Pereg-Barnea, A. H. MacDonald

We present a theory of momentum space local density-of-states (LDOS) maps N(q,omega) in graphene. The LDOS map has both intravalley contributions centered near zero momentum and reciprocal lattice vectors and intervalley contributions displaced by the wavevector K&#39;-K which connects graphene&#39;s two distinct Dirac points. Using graphene&#39;s Dirac equa

Anton Gerasimov, Dimitri Lebedev, Sergey Oblezin

A representation of a specialization of a q-deformed class one lattice gl(\ell+1}-Whittaker function in terms of cohomology groups of line bundles on the space QM_d(P^{\ell}) of quasi-maps P^1 to P^{\ell} of degree d is proposed. For \ell=1, this provides an interpretation of non-specialized q-deformed gl(2)-Whittaker function in terms of QM_d(\IP^1). In par

Hua Xu, Su Li, M. C. Sullivan, Kouji Segawa

We have studied the normal-to-superconducting phase transition in optimally-doped YBa$_2$Cu$_3$O$_{7-δ}$ in zero external magnetic field using a variety of different samples and techniques. Using DC transport measurements, we find that the dynamical critical exponent $z=1.54\pm0.14$, and the static critical exponent $ν=0.66\pm0.10$ for both films (when finit

M. R. Tarbutt, J. J. Hudson, B. E. Sauer, E. A. Hinds

This paper is a chapter from an upcoming book on cold molecule physics. In it we describe techniques for the preparation and manipulation of cold molecules. We further describe techniques for applying said cold molecules to tests of fundamental physics.

Brice Ménard, Doron Chelouche

We estimate the mean dust-to-gas ratio of MgII absorbers as a function of rest equivalent width W_0 and redshift over the range 0.5<z<1.4. Using the expanded SDSS/HST sample of low-redshift Lyman-alpha absorbers we first show the existence of a 8-sigma correlation between the mean hydrogen column density <N_HI> and W_0, an indicator of gas velocity dispersio

Yen Lee Loh, Dao-Xin Yao, Erica W. Carlson

We derive exact results for close-packed dimers on the triangular kagome lattice (TKL), formed by inserting triangles into the triangles of the kagome lattice. Because the TKL is a non-bipartite lattice, dimer-dimer correlations are short-ranged, so that the ground state at the Rokhsar-Kivelson (RK) point of the corresponding quantum dimer model on the same

Michael Hahsler, Kurt Hornik

Mining association rules is an important technique for discovering meaningful patterns in transaction databases. Many different measures of interestingness have been proposed for association rules. However, these measures fail to take the probabilistic properties of the mined data into account. In this paper, we start with presenting a simple probabilistic f

Enrico Rossi, S. Das Sarma

We calculate the carrier density dependent ground state properties of graphene in the presence of random charged impurities in the substrate taking into account disorder and interaction effects non-perturbatively on an equal footing in a self-consistent theoretical formalism. We provide detailed quantitative results on the dependence of the disorder-induced

Maikel C. Rheinstadter, Karin Schmalzl, Kathleen Wood, Dieter Strauch

We present experimental evidence for a long-range protein-protein interaction in purple membrane (PM). The interprotein dynamics were quantified by measuring the spectrum of the acoustic phonons in the 2D bacteriorhodopsin (BR) protein lattice using inelastic neutron scattering. Phonon energies of about 1 meV were determined. The data are compared to an anal

I. Serban, B. L. T. Plourde, F. K. Wilhelm

We present a measurement protocol for a flux qubit coupled to a dc-Superconducting QUantum Interference Device (SQUID), representative of any two-state system with a controllable coupling to an harmonic oscillator quadrature, which consists of two steps. First, the qubit state is imprinted onto the SQUID via a very short and strong interaction. We show that

Benjamin Lévêque, Frédéric Maffray, Myriam Preissmann

A graph is a path graph if it is the intersection graph of a family of subpaths of a tree. In 1970, Renz asked for a characterizaton of path graphs by forbidden induced subgraphs. Here we answer this question by listing all graphs that are not path graphs and are minimal with this property.

Jeffrey Diller, Romain Dujardin, Vincent Guedj

We consider the dynamics of a meromorphic map on a compact kahler surface whose topological degree is smaller than its first dynamical degree. The latter quantity is the exponential rate at which its iterates expand the cohomology class of a kahler form. Our goal in this article and its sequels is to carry out a conjectural program for constructing and analy

Vikram Chandrasekhar, Jeffrey Andrews, Alan Gatherer

The surest way to increase the system capacity of a wireless link is by getting the transmitter and receiver closer to each other, which creates the dual benefits of higher quality links and more spatial reuse. In a network with nomadic users, this inevitably involves deploying more infrastructure, typically in the form of microcells, hotspots, distributed a

Oleg Gittsovich, Otfried Gühne, Philipp Hyllus, Jens Eisert

We present a framework for deciding whether a quantum state is separable or entangled using covariance matrices of locally measurable observables. This leads to the covariance matrix criterion as a general separability criterion. We demonstrate that this criterion allows to detect many states where the familiar criterion of the positivity of the partial tran

Anastasia Doikou

Generic classically integrable boundary conditions for the $A_{n}^{(1)}$ affine Toda field theories (ATFT) are investigated. The present analysis rests primarily on the underlying algebra, defined by the classical version of the reflection equation. We use as a prototype example the first non-trivial model of the hierarchy i.e. the $A_2^{(1)}$ ATFT, however

A. Tamai, M. P. Allan, J. F. Mercure, W. Meevasana

The low-energy electronic structure of the itinerant metamagnet Sr3Ru2O7 is investigated by angle resolved photoemission and density functional calculations. We find well-defined quasiparticle bands with resolution limited line widths and Fermi velocities up to an order of magnitude lower than in single layer Sr2RuO4. The complete topography, the cyclotron m

R. Rapp, H. van Hees

We report on recent research on the properties of elementary particle matter governed by the strong force at high temperatures, where QCD predicts hadrons to dissolve into the Quark-Gluon Plasma (QGP). After a short introduction to the basic elements of QCD in the vacuum, most notably quark confinement and mass generation, we discuss how these phenomena rela

Wei-Feng Tsai, Hong Yao, Andreas Laeuchli, Steven A. Kivelson

We report the results of exact diagonalization studies of Hubbard models on a $4\times 4$ square lattice with periodic boundary conditions and various degrees and patterns of inhomogeneity, which are represented by inequivalent hopping integrals $t$ and $t^{\prime}$. We focus primarily on two patterns, the checkerboard and the striped cases, for a large rang

S. Meloni, J. Gomez-Gardenes, V. Latora, Y. Moreno

We propose a model of random diffusion to investigate flow fluctuations in complex networks. We derive an analytical law showing that the dependence of fluctuations with the mean traffic in a network is ruled by the delicate interplay of three factors, respectively of dynamical, topological and statistical nature. In particular, we demonstrate that the exist

Daniel A. Spielman, Nikhil Srivastava

We present a nearly-linear time algorithm that produces high-quality sparsifiers of weighted graphs. Given as input a weighted graph $G=(V,E,w)$ and a parameter $ε>0$, we produce a weighted subgraph $H=(V,\tilde{E},\tilde{w})$ of $G$ such that $|\tilde{E}|=O(n\log n/ε^2)$ and for all vectors $x\in\R^V$ $(1-ε)\sum_{uv\in E}(x(u)-x(v))^2w_{uv}\le \sum_{uv\in\t

Gang Mu, Xiyu Zhu, Lei Fang, Lei Shan

We report the specific heat measurements on the newly discovered Fe-based layered superconductor LaO_0.9F_{0.1-delta}FeAs with the onset transition temperature T_c \approx 28 K. A nonlinear magnetic field dependence of the electronic specific heat coefficient gamma(H) has been found in the low temperature limit, which is consistent with the prediction for a

Shiva Prasad Kasiviswanathan, Homin K. Lee, Kobbi Nissim, Sofya Raskhodnikova

Learning problems form an important category of computational tasks that generalizes many of the computations researchers apply to large real-life data sets. We ask: what concept classes can be learned privately, namely, by an algorithm whose output does not depend too heavily on any one input or specific training example? More precisely, we investigate lear

Peter Bürgisser, Dennis Amelunxen

We perform a smoothed analysis of the GCC-condition number C(A) of the linear programming feasibility problem \exists x\in\R^{m+1} Ax < 0. Suppose that \bar{A} is any matrix with rows \bar{a_i} of euclidean norm 1 and, independently for all i, let a_i be a random perturbation of \bar{a_i} following the uniform distribution in the spherical disk in S^m of ang

H. -J. Schmidt

We calculate the perihelion precession delta for nearly circular orbits in a central potential V(r). Differently from other approaches to this problem, we do not assume that the potential is close to the Newtonian one. The main idea in the deduction is to apply the underlying symmetries of the system to show that delta must be a function of r V&#39;&#39;(r)/

Joerg M. Colberg, Frazer Pearce, Caroline Foster, Erwin Platen

Despite a history that dates back at least a quarter of a century studies of voids in the large--scale structure of the Universe are bedevilled by a major problem: there exist a large number of quite different void--finding algorithms, a fact that has so far got in the way of groups comparing their results without worrying about whether such a comparison in

Bernd Sturmfels, Zhiqiang Xu

We degenerate Cox-Nagata rings to toric algebras by means of sagbi bases induced by configurations over the rational function field. For del Pezzo surfaces, this degeneration implies the Batyrev-Popov conjecture that these rings are presented by ideals of quadrics. For the blow-up of projective n-space at n+3 points, sagbi bases of Cox-Nagata rings establish

Jonas Bergström, Carel Faber, Gerard van der Geer

We study the cohomology of certain local systems on moduli spaces of principally polarized abelian surfaces with a level 2 structure. The trace of Frobenius on the alternating sum of the étale cohomology groups of these local systems can be calculated by counting the number of pointed curves of genus 2 with a prescribed number of Weierstrass points over the

Chong-Sun Chu, Shou-Huang Dai, Douglas J. Smith

We construct type IIB supergravity duals of non-anticommutative deformed N = 4 SU(N) gauge theories. We consider in particular deformations preserving N = (1,0) and N = (1/2,0) supersymmetry. Such theories can be realised on N D3-branes in specific self-dual 5-form backgrounds. We show that the required 5-form field strengths can be produced by configuration

M. O. Goerbig, J. -N. Fuchs, G. Montambaux, F. Piechon

We investigate a generalized two-dimensional Weyl Hamiltonian, which may describe the low-energy properties of mechanically deformed graphene and of the organic compound alpha-(BEDT-TTF)_2I_3 under pressure. The associated dispersion has generically the form of tilted anisotropic Dirac cones. The tilt arises due to next-nearest-neighbor hopping when the Dira

E. Khosravi, G. Stefanucci, S. Kurth, E. K. U. Gross

The presence of bound states in a nanoscale electronic system attached to two biased, macroscopic electrodes is shown to give rise to persistent, non-decaying, localized current oscillations which can be much larger than the steady part of the current. The amplitude of these oscillations depends on the entire history of the applied potential. The bound-state

A1 Collaboration, P. Janssens, L. Doria, P. Achenbach

The cross section of the $ep \to e&#39; p&#39; γ$ reaction has been measured at $Q^2 = 0.33$ (GeV/c)$^2$. The experiment was performed using the electron beam of the MAMI accelerator and the standard detector setup of the A1 Collaboration. The cross section is analyzed using the low-energy theorem for virtual Compton scattering, yielding a new determination

Christopher M. Hirata

The subject of cosmological hydrogen recombination has received much attention recently because of its importance to predictions for and cosmological constraints from CMB observations. While the central role of the two-photon decay 2s->1s has been recognized for many decades, high-precision calculations require us to consider two-photon decays from the highe