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Arxiv.org
by Hiroshi Miki; Satoshi Tsujimoto; Luc Vinet; Alexei Zhedanov
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An interpretation of the multiple Meixner polynomials of the first kind is provided through an infinite Lie algebra realized in terms of the creation and annihilation operators of a set of independent oscillators. The model is used to derive properties of these orthogonal polynomials.
Source: http://arxiv.org/abs/1203.0357v1
Arxiv.org
by Takeshi Araki; Julian Heeck; Jisuke Kubo
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Augmenting the Standard Model by three right-handed neutrinos allows for an anomaly-free gauge group extension G_max = U(1)_(B-L) x U(1)_(L_e-L_mu) x U(1)_(L_mu-L_tau). While simple U(1) subgroups of G_max have already been discussed in the context of approximate flavor symmetries, we show how two-zero textures in the right-handed neutrino Majorana mass matrix can be enforced by the flavor symmetry, which is spontaneously broken very economically by singlet scalars. These zeros lead to two...
Source: http://arxiv.org/abs/1203.4951v2
Arxiv.org
by Octavio Miramontes; Og DeSouza; Diego Hernández; Eliane Ceccon
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We measured mobility patterns that describe walking trajectories of individual Me'Phaa peasants searching and collecting fuelwood in the forests of "La Monta\~na de Guerrero" in Mexico. These one-day excursions typically follow a mixed pattern of nearly-constant steps when individuals displace from their homes towards potential collecting sites and a mixed pattern of steps of different lengths when actually searching for fallen wood in the forest. Displacements in the searching phase...
Source: http://arxiv.org/abs/1203.0971v1
Arxiv.org
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In complex systems, the interplay between nonlinear and stochastic dynamics, e.g., J. Monod's necessity and chance, gives rise to an evolutionary process in Darwinian sense, in terms of discrete jumps among attractors, with punctuated equilibrium, spontaneous random "mutations" and "adaptations". On an evlutionary time scale it produces sustainable diversity among individuals in a homogeneous population rather than convergence as usually predicted by a deterministic...
Source: http://arxiv.org/abs/1203.3554v2
Arxiv.org
by Ismael Fortuna; Gilberto L. Thomas; Rita M. C. de Almeida; Francois Graner
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We study the topology and geometry of two dimensional coarsening foams with arbitrary liquid fraction. To interpolate between the dry limit described by von Neumann's law, and the wet limit described by Marqusee equation, the relevant bubble characteristics are the Plateau border radius and a new variable, the e?ective number of sides. We propose an equation for the individual bubble growth rate as the weighted sum of the growth through bubble-bubble interfaces and through bubble-Plateau...
Source: http://arxiv.org/abs/1203.5834v2
Arxiv.org
by Kristoffer Arnsfelt Hansen; Rasmus Ibsen-Jensen; Peter Bro Miltersen
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Two standard algorithms for approximately solving two-player zero-sum concurrent reachability games are value iteration and strategy iteration. We prove upper and lower bounds of 2^(m^(Theta(N))) on the worst case number of iterations needed by both of these algorithms for providing non-trivial approximations to the value of a game with N non-terminal positions and m actions for each player in each position. In particular, both algorithms have doubly-exponential complexity. Even when the game...
Source: http://arxiv.org/abs/1007.1812v3
Arxiv.org
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In this paper, we shall establish a Dancer-type unilateral global bifurcation result for a class of quasilinear elliptic problems with sign-changing weight. Under some natural hypotheses on perturbation function, we show that $(\mu_k^\nu(p),0)$ is a bifurcation point of the above problems and there are two distinct unbounded continua, $(\mathcal{C}_{k}^\nu)^+$ and $(\mathcal{C}_{k}^\nu)^-$, consisting of the bifurcation branch $\mathcal{C}_{k}^\nu$ from $(\mu_k^\nu(p), 0)$, where $\mu_k^\nu(p)$...
Source: http://arxiv.org/abs/1203.3262v1
Arxiv.org
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We consider the synthesis of control policies for probabilistic systems, modeled by Markov decision processes, operating in partially known environments with temporal logic specifications. The environment is modeled by a set of Markov chains. Each Markov chain describes the behavior of the environment in each mode. The mode of the environment, however, is not known to the system. Two control objectives are considered: maximizing the expected probability and maximizing the worst-case probability...
Source: http://arxiv.org/abs/1203.1177v1
Arxiv.org
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We analyze event-by-event fluctuations of the transverse momentum in relativistic heavy-ion collisions at RHIC in the framework based on the fluctuating Glauber-model initial conditions, event-by-event (3+1)-dimensional viscous hydrodynamics, and statistical hadronization. We use the scaled fluctuation measure < Delta p_Ti Delta p_Tj > / < < p_T >>. The identified "geometric" mechanism of generating the transverse-momentum fluctuations from the initial size...
Source: http://arxiv.org/abs/1203.1810v1
Arxiv.org
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We consider the differential cross section of electron-positron pair production by a high-energy photon in a strong Coulomb field close to the end of the electron or positron spectrum. When the momentum transfer largely exceeds the electron mass, the cross section is obtained analytically in a compact form. Coulomb corrections essentially modify the cross section even for moderate values of the nuclear charge number $Z$. In the same kinematical region, the angular distribution for bound-free...
Source: http://arxiv.org/abs/1203.2137v1
Arxiv.org
by Kelly R. Patton; Daniel E. Sheehy
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The induced intraspecies interactions among the majority species, mediated by the minority species, is computed for a population-imbalanced two-component Fermi gas. Although the Feshbach-resonance mediated interspecies interaction is dominant for equal populations, leading to singlet s-wave pairing, we find that in the strongly imbalanced regime the induced intraspecies interaction leads to p-wave pairing and superfluidity of the majority species. Thus, we predict that the observed spin-polaron...
Source: http://arxiv.org/abs/1203.6348v1
Arxiv.org
by E. Stonkutė; G. Tautvaišienė; B. Nordström; R. Ženovienė
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Galactic Archeology is a powerful tool for investigating the formation and evolution of the Milky Way. We use this technique to study kinematic groups of F- and G-stars in the solar neighbourhood. From correlations between orbital parameters, three new coherent groups of stars were recently identified and suggested to correspond to remnants of disrupted satellites. We determine detailed elemental abundances in stars belonging to one of these groups and compare their chemical composition with...
Source: http://arxiv.org/abs/1203.6199v1
Arxiv.org
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A numerical method to integrate the time-dependent Hartree-Fock Bogoliubov (TDHFB) equations with Gogny interaction is proposed. The feasibility of the TDHFB code is illustrated by the conservation of the energy, particle numbers, and center-of-mass in the small amplitude vibrations of oxygen 20. The TDHFB code is applied to the isoscalar quadrupole and/or isovector dipole vibrations in the linear (small amplitude) region in oxygen isotopes (masses A = 18,20,22 and 24), titanium isotopes (A =...
Source: http://arxiv.org/abs/1203.6174v1
Arxiv.org
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We study, in the framework of open quantum systems, the geometric phase acquired by a uniformly accelerated two-level atom undergoing nonunitary evolution due to its coupling to a bath of fluctuating vacuum electromagnetic fields in the multipolar scheme. We find that the phase variation due to the acceleration can be in principle observed via atomic interferometry between the accelerated atom and the inertial one, thus providing an evidence of the Unruh effect.
Source: http://arxiv.org/abs/1203.5869v1
Arxiv.org
by Jan O. Stenflo
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The Sun's magnetic field is structured over a range of scales that span approximately seven orders of magnitudes, four of which lie beyond the resolving power of current telescopes. Here we have used a Hinode SOT/SP deep mode data set for the quiet-sun disk center in combination with constraints from the Hanle effect to derive scaling laws that describe how the magnetic structuring varies from the resolved scales down to the magnetic diffusion limit, where the field ceases to be frozen-in. The...
Source: http://arxiv.org/abs/1203.6011v1
Arxiv.org
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Let $A \subseteq E$ be an extension of Hopf algebras such that there exists a normal left $A$-module coalgebra map $\pi : E \to A$ that splits the inclusion. We shall describe the set of all coquasitriangular structures on the Hopf algebra $E$ in terms of the datum $(A, E, \pi)$ as follows: first, any such extension $E$ is isomorphic to a unified product $A \ltimes H$, for some unitary subcoalgebra $H$ of $E$ (\cite{am2}). Then, as a main theorem, we establish a bijective correspondence between...
Source: http://arxiv.org/abs/1203.2455v1
Arxiv.org
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We have investigated the transmission and reflection properties of structures incorporating left-handed materials with graded index of refraction. We present an exact analytical solution to Helmholtz' equation for a graded index profile changing according to a hyperbolic tangent function along the propagation direction. We derive expressions for the field intensity along the graded index structure, and we show excellent agreement between the analytical solution and the corresponding results...
Source: http://arxiv.org/abs/1203.2311v1
Arxiv.org
by A. S. Sanz; Y. Elran; P. Brumer
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The effect of chaotic bath dynamics on the decoherence of a quantum system is examined for the vibrational degrees of freedom of a diatomic molecule in a realistic, constant temperature collisional bath. As an example, the specific case of I$_2$ in liquid xenon is examined as a function of temperature, and the results compared with an integrable xenon bath. A crossover in behavior is found: the integrable bath induces more decoherence at low bath temperatures than does the chaotic bath, whereas...
Source: http://arxiv.org/abs/1203.4629v2
Arxiv.org
by Sandro Gallo; Matthieu Lerasle; Daniel Yasumasa Takahashi
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We derive explicit upper bounds for the $\bar{d}$-distance between a chain of infinite order and its canonical $k$-steps Markov approximation. Our proof is entirely constructive and involves a "coupling from the past" argument. The new method covers non necessarily continuous probability kernels, and chains with null transition probabilities. These results imply in particular the Bernoulli property for these processes.
Source: http://arxiv.org/abs/1107.4353v2
Arxiv.org
by E. A. O'Brien; C. Voll
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We develop general formulae for the numbers of conjugacy classes and irreducible complex characters of finite p-groups of nilpotency class less than p. This allows us to unify and generalize a number of existing enumerative results, and to obtain new such results for generalizations of relatively free p-groups of exponent p. Our main tools are the Lazard correspondence and the Kirillov orbit method.
Source: http://arxiv.org/abs/1203.3050v1
Arxiv.org
by M. Arrayás; M. A. Fontelos; U. Kindelán
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We present the first analytical and numerical studies of the initial stage of the branching process based on an interface dynamics streamer model in the fully 3-D case. This model follows from fundamental considerations on charge production by impact ionization and balance laws, and leads to an equation for the evolution of the interface between ionized and non-ionized regions. We compare some experimental patterns with the numerically simulated ones, and give an explicit expression for the...
Source: http://arxiv.org/abs/1203.6790v1
Arxiv.org
by Lucas A. Cieza; Matthias R. Schreiber; Gisela A. Romero; Jonathan P. Williams; Alberto Rebassa-Mansergas; Bruno Merin
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As part of an ongoing program aiming to characterize a large number of Spitzer-selected transition disks (disks with reduced levels of near-IR and/or mid- IR excess emission), we have obtained (sub)millimeter wavelength photometry, high-resolution optical spectroscopy, and adaptive optics near-infrared imaging for a sample of 31 transition objects located in the Perseus, Taurus, and Auriga molecular clouds. We use these ground-based data to estimate disk masses, multiplicity, and accretion...
Source: http://arxiv.org/abs/1203.6849v1
Arxiv.org
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In this paper, a study of random times on filtered probability spaces is undertaken. The main message is that, as long as distributional properties of optional processes up to the random time are involved, there is no loss of generality in assuming that the random time is actually a randomized stopping time. This perspective has advantages in both the theoretical and practical study of optional processes up to random times. Applications are given to the stochastic behavior of processes up to...
Source: http://arxiv.org/abs/1007.1124v3
Arxiv.org
by Guangxi Jin; Kun Cao; Guang-Can Guo; Lixin He
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"Magnetic ferroelectric" has been found in a wide range of spiral magnets. However, these materials all suffer from low critical temperatures, which are usually below 40 K, due to strong spin frustration. Recently, CuO has been found to be multiferroic at much higher ordering temperature ($\sim$ 230K). To clarify the origin of the high ordering temperature in CuO, we investigate the structural, electronic and magnetic properties of CuO via first-principles methods. We find that CuO...
Source: http://arxiv.org/abs/1007.2274v4
Arxiv.org
by S. H. P. Alencar; J. Bouvier; F. M. Walter; C. Dougados; J. -F. Donati; R. Kurosawa; M. Romanova; X. Bonfils; G. H. R. A. Lima; S. Massaro; M. Ibrahimov; E. Poretti
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We analyze the photometric and spectroscopic variability of the classical T Tauri star V2129 Oph over several rotational cycles to test the dynamical predictions of magnetospheric accretion models. The photometric variability and the radial velocity variations in the photospheric lines can be explained by rotational modulation due to cold spots, while the radial velocity variations of the He I (5876 \AA) line and the veiling variability are due to hot spot rotational modulation. The hot and...
Source: http://arxiv.org/abs/1203.6331v1
Arxiv.org
by J. de la Cruz Rodríguez; H. Socas-Navarro; M. Carlsson; J. Leenaarts
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The magnetic field of the quiet-Sun chromosphere remains a mystery for solar physicists. The reduced number of chromospheric lines are intrinsically hard to model and only a few of them are magnetically sensitive. In this work, we use a 3D numerical simulation of the outer layers of the solar atmosphere, to asses the reliability of non-LTE inversions, in this case applied to the Ca II 8542 \AA\ line. We show that NLTE inversions provide realistic estimates of physical quantities from synthetic...
Source: http://arxiv.org/abs/1203.4577v1
Arxiv.org
by Daniel Kolbe; Martin Scheid; Jochen Walz
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Continuous-wave coherent radiation in the vacuum ultraviolet (VUV)wavelength region at 121 nm will be essential for future laser-cooling of trapped antihydrogen [1]. Cold antihydrogen will enable both tests of the fundamental symmetry between matter and antimatter at unprecedented experimental precision [2] and also experiments in antimatter gravity [3]. Another fascinating application of narrowband continuous laser radiation in the VUV is quantum information processing using single trapped...
Source: http://arxiv.org/abs/1203.2121v1
We discuss quantum electrodynamics emerging in the vacua with anisotropic scaling. Systems with anisotropic scaling were suggested by Horava in relation to the quantum theory of gravity. In such vacua the space and time are not equivalent, and moreover they obey different scaling laws, called the anisotropic scaling. Such anisotropic scaling takes place for fermions in bilayer graphene, where if one neglects the trigonal warping effects the massless Dirac fermions have quadratic dispersion....
Source: http://arxiv.org/abs/1203.1578v3
Arxiv.org
by Gonzalo A. Alvarez; Alexandre M. Souza; Dieter Suter
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The loss of quantum information due to interaction with external degrees of freedom, which is known as decoherence, remains one of the main obstacles for large-scale implementations of quantum computing. Accordingly, different measures are being explored for reducing its effect. One of them is dynamical decoupling (DD) which offers a practical solution because it only requires the application of control pulses to the system qubits. Starting from basic DD sequences, more sophisticated schemes...
Source: http://arxiv.org/abs/1203.0252v1
Arxiv.org
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The Generalized Traveling Salesman Problem (GTSP) is a well-known combinatorial optimization problem with a host of applications. It is an extension of the Traveling Salesman Problem (TSP) where the set of cities is partitioned into so-called clusters, and the salesman has to visit every cluster exactly once. While the GTSP is a very important combinatorial optimization problem and is well studied in many aspects, the local search algorithms used in the literature are mostly basic adaptations...
Source: http://arxiv.org/abs/1005.5525v4
Arxiv.org
by Silvio Franz; Giorgio Parisi; Federico Ricci-Tersenghi
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We consider the critical properties of points of continuous glass transition as one can find in liquids in presence of constraints or in liquids in porous media. Through a one loop analysis we show that the critical Replica Field Theory describing these points can be mapped in the $\phi^4$-Random Field Ising Model. We confirm our analysis studying the finite size scaling of the $p$-spin model defined on sparse random graph, where a fraction of variables is frozen such that the phase transition...
Source: http://arxiv.org/abs/1203.4849v3
Arxiv.org
by Aaron D. Lauda; Heather M. Russell
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We identify the ring of odd symmetric functions introduced by Ellis and Khovanov as the space of skew polynomials fixed by a natural action of the Hecke algebra at q=-1. This allows us to define graded modules over the Hecke algebra at q=-1 that are `odd' analogs of the cohomology of type A Springer varieties. The graded module associated to the full flag variety corresponds to the quotient of the skew polynomial ring by the left ideal of nonconstant odd symmetric functions. The top degree...
Source: http://arxiv.org/abs/1203.0797v1
Arxiv.org
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We consider the recurrence and transience problem for a time-homogeneous Markov chain on the real line with transition kernel $p(x,dy)=f_x(y-x)dy$, where the density functions $f_x(y)$, for large $|y|$, have a power-law decay with exponent $\alpha(x)+1$, where $\alpha(x)\in(0,2)$. In this paper, under a uniformity condition on the density functions $f_x(y)$ and some mild technical conditions, we prove that when $\liminf_{|x|\longrightarrow\infty}\alpha(x)>1$, the chain is recurrent, while...
Source: http://arxiv.org/abs/1203.0447v1
Arxiv.org
by Jeffrey G. Rau; Hae-Young Kee
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We propose a candidate for the hidden order in URu2Si2: a rank-5 E type spin density wave between Uranium 5f crystal field doublets breaking time reversal and lattice tetragonal symmetry in a manner consistent with recent torque measurements [R. Okazaki et al, Science 331, 439 (2011)]. We argue that coupling of this order parameter to magnetic probes can be hidden by crystal field effects, while still having significant effects on transport, thermodynamics and magnetic susceptibilities. In a...
Source: http://arxiv.org/abs/1203.1047v2
Arxiv.org
by Leonardo Motta; Robert R. Caldwell
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We show that a conformal-invariance violating coupling of the inflaton to electromagnetism produces a cross correlation between curvature fluctuations and a spectrum of primordial magnetic fields. According to this model, in the case of power-law inflation, a primordial magnetic field is generated with a nearly flat power spectrum and rms amplitude ranging from nG to pG. We study the cross correlation, a three-point function of the curvature perturbation and two powers of the magnetic field, in...
Source: http://arxiv.org/abs/1203.1033v1
Arxiv.org
by Giacomo Ceccarelli; Christian Torrero
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In the framework of the trap-size scaling theory, we study the scaling properties of the Bose-Hubbard model in two dimensions in the presence of a trapping potential at finite temperature. In particular, we provide results for the particle density and the density-density correlator at the Mott transitions and within the superfluid phase. For the former quantity, numerical outcomes are also extensively compared to Local Density Approximation predictions.
Source: http://arxiv.org/abs/1203.2030v3
Arxiv.org
by D. Meloni; S. Morisi; E. Peinado
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In the light of the recent Daya Bay result the reactor angle is about 9 degrees, we reconsider the model presented in arXiv:1005.3482 showing that, when all neutrino oscillation parameters are taken at their best fit values of Schwetz et al and the reactor angle to be the central value of Daya Bay, the predicted value of the CP phase is approximately 45 degrees.
Source: http://arxiv.org/abs/1203.2535v1
Arxiv.org
by R. Giostri; M. Vargas dos Santos; I. Waga; R. R. R. Reis; M. O. Calvão; B. L. Lago
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We use type Ia supernovae (SN Ia) data in combination with recent baryonic acoustic oscillations (BAO) and cosmic microwave background (CMB) observations to constrain a kink-like parametrization of the deceleration parameter ($q$). This $q$-parametrization can be written in terms of the initial ($q_i$) and present ($q_0$) values of the deceleration parameter, the redshift of the cosmic transition from deceleration to acceleration ($z_t$) and the redshift width of such transition ($\tau$). By...
Source: http://arxiv.org/abs/1203.3213v1
Arxiv.org
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In a recent paper, Gabriel Navarro and Pham Huu Tiep show that the so-called Alperin Weight Conjecture can be verified via the Classification of the Finite Simple Groups, provided any simple group fulfills a very precise list of conditions. Our purpose here is to show that the equivariant refinement of the Alperin's Conjecture for blocks formulated by Geoffrey Robinson in the eighties can be reduced to checking the same statement on any central k*-extension of any finite almost-simple group, or...
Source: http://arxiv.org/abs/1203.3851v3
Arxiv.org
by Oriane Aubert; Michael Le Bars; Patrice Le Gal; Philip S. Marcus
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We validate a new law for the aspect ratio $\alpha = H/L$ of vortices in a rotating, stratified flow, where $H$ and $L$ are the vertical half-height and horizontal length scale of the vortices. The aspect ratio depends not only on the Coriolis parameter f and buoyancy (or Brunt-Vaisala) frequency $\bar{N}$ of the background flow, but also on the buoyancy frequency $N_c$ within the vortex and on the Rossby number $Ro$ of the vortex such that $\alpha = f \sqrt{[Ro (1 + Ro)/(N_c^2- \bar{N}^2)]}$....
Source: http://arxiv.org/abs/1203.1562v1
Arxiv.org
by T. Wasak; J. Chwedenczuk; P. Zin; M. Trippenbach
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It is demonstrated that measurements of positions of atoms scattered from a quasi-condensate in a Raman process provide information on the temperature of the parent cloud. In particular, the widths of the density and second order correlation functions are sensitive to the phase fluctuations induced by non-zero temperature of the quasi-condensate. It is also shown how these widths evolve during expansion of the cloud of scattered atoms. These results are useful for planning future Raman...
Source: http://arxiv.org/abs/1203.0894v1
Arxiv.org
by A. Bazavov; Tanmoy Bhattacharya; C. E. DeTar; H. -T. Ding; Steven Gottlieb; Rajan Gupta; P. Hegde; Urs Heller; F. Karsch; E. Laermann; L. Levkova; Swagato Mukherjee; P. Petreczky; Christian Schmidt; R. A. Soltz; W. Soeldner; R. Sugar; Pavlos M. Vranas
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We calculate the quadratic fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in (2+1)-flavor lattice QCD at zero chemical potential. Results are obtained using calculations with tree level improved gauge and the highly improved staggered quark (HISQ) actions with almost physical light and strange quark masses at three different values of the lattice cut-off. Our choice of parameters corresponds to a value of 160 MeV for the...
Source: http://arxiv.org/abs/1203.0784v2
Arxiv.org
by Mugurel Ţolea; Bogdan Ostahie; Marian Niţă; Felicia Ţolea; Alexandru Aldea
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The phase of the electronic wave function is not directly measurable but, quite remarkably, it becomes accessible in pairs of isospectral shapes, as recently proposed in the experiment of Christopher R. Moon {\it et al.}, Science {\bf 319}, 782 (2008). The method is based on a special property, called transplantation, which relates the eigenfunctions of the isospectral pairs, and allows to extract the phase distributions, if the amplitude distributions are known. We numerically simulate such a...
Source: http://arxiv.org/abs/1203.0717v1
Arxiv.org
by Joseph Losby; Jacob A. J. Burgess; Zhu Diao; David C. Fortin; Wayne K. Hiebert; Mark R. Freeman
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We report on the fabrication of sensitive nanotorsional resonators, which can be utilized as magnetometers for investigating the magnetization dynamics in small magnetic elements. The thermo-mechanical noise is calibrated with the resonator displacement in order to determine the ultimate mechanical torque sensitivity of the magnetometer.
Source: http://arxiv.org/abs/1203.0998v1
Arxiv.org
by Maxim Vashkevich; Alexander Petrovsky
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A fast Discrete Cosine Transform (DCT) algorithm is introduced that can be of particular interest in image processing. The main features of the algorithm are regularity of the graph and very low arithmetic complexity. The 16-point version of the algorithm requires only 32 multiplications and 81 additions. The computational core of the algorithm consists of only 17 nontrivial multiplications, the rest 15 are scaling factors that can be compensated in the post-processing. The derivation of the...
Source: http://arxiv.org/abs/1203.3442v2
Arxiv.org
by Anna De Masi; Errico Presutti; Dimitrios Tsagkarogiannis; Maria Eulalia Vares
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We consider the symmetric simple exclusion process in the interval $\La_N:=[-N,N]\cap\mathbb Z$ with births and deaths taking place respectively on suitable boundary intervals $I_+$ and $I_-$, as introduced in De Masi et al. (J. Stat. Phys. 2011). We study the stationary measure density profile in the limit $N\to\infty$
Source: http://arxiv.org/abs/1203.1795v1
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by Andreas Schäfer; Jian Zhou
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We reexamine the scale dependence of the ETQS (Efremov-Teryaev-Qiu-Sterman) twist-3 matrix element which has been studied already by the four different groups with conflicting results Ref.[1-4]. We find that we can in fact reproduce the results of Ref.[4] with the method Ref.[4] when we treat some subtleties with greater care, thus easing the mentioned conflict.
Source: http://arxiv.org/abs/1203.5293v1
We use the framework of the HIJING/B\=B v2.0 model to simulate high-multiplicity (HM) $p+p$ collision events at the Large Hadron Collider (LHC) to study observables sensitive to possible collective phenomena, such as strong longitudinal color fields (SLCF) modeled by an enhanced string tension ($\kappa$). We focus on the hyperon/meson yield ratios at center-of-mass (c.m.) energy $\sqrt{s}$ = 7 TeV, in the transverse momentum region, $1 < p_T < 4 $ GeV/{\it c}. For minimum bias events...
Source: http://arxiv.org/abs/1203.6679v2
Arxiv.org
by Andre Chatzistamatiou
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We prove the following criterion for the pro-representability of the deformation cohomology of a commutative formal Lie group. Let f be a flat and separated morphism between noetherian schemes. Assume that the target of f is flat over the integers. For a commutative formal Lie group E, we have the deformation cohomology of f with coefficients in E at our disposal. If the higher direct images of the tangent space of E are locally free and of finite rank then the deformation cohomology is...
Source: http://arxiv.org/abs/1203.4926v3
Arxiv.org
by H. F. Chau; C. -K. Li; Y. -T. Poon; N. -S. Sze
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Recently, Chau [Quant. Inform. & Comp. 11, 721 (2011)] showed that one can define certain metrics and pseudo-metrics on U(n), the group of all $n\times n$ unitary matrices, based on the arguments of the eigenvalues of the unitary matrices. More importantly, these metrics and pseudo-metrics have quantum information theoretical meanings. So it is instructive to study this kind of metrics and pseudo-metrics on U(n). Here we show that any symmetric norm on ${\mathbb R}^n$ induces a metric on...
Source: http://arxiv.org/abs/1107.1047v2
Arxiv.org
by Jason Matthews; David Sánchez; Marcus Larsson; Heiner Linke
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The response of electric devices to an applied thermal gradient has, so far, been studied almost exclusively in two-terminal devices. Here we present measurements of the response to a thermal bias of a four-terminal, quasi-ballistic junction with a central scattering site. We find a novel transverse thermovoltage measured across isothermal contacts. Using a multi-terminal scattering model extended to the weakly non-linear voltage regime, we show that the device's response to a thermal bias can...
Source: http://arxiv.org/abs/1107.3179v3
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by P. S. Burada; B. Lindner
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We study the dynamics of an active Brownian particle with a nonlinear friction function located in a spatial cubic potential. For strong but finite damping, the escape rate of the particle over the spatial potential barrier shows a nonmonotonic dependence on the noise intensity. We relate this behavior to the fact that the active particle escapes from a limit cycle rather than from a fixed point and that a certain amount of noise can stabilize the sojourn of the particle on this limit cycle.
Source: http://arxiv.org/abs/1203.6814v1
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by Spyros Basilakos; Athina Pouri
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We place tight constraints on the growth index $\gamma$ by using the recent growth history results of 2dFGRS, SDSS-LRG, VIMOS-VLT deep Survey (VVDS) and {\em WiggleZ} datasets. In particular, we investigate several parametrizations of the growth index $\gamma(z)$, by comparing their cosmological evolution using observational growth rate data at different redshifts. Utilizing a standard likelihood analysis we find that the use of the combined growth data provided by the 2dFGRS, SDSS-LRG, VVDS...
Source: http://arxiv.org/abs/1203.6724v2
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by Jian-Feng Li; Hong-Tao Feng; Yu Jiang; Wei-Min Sun; Hong-Shi Zong
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We study dynamical chiral symmetry breaking (DCSB) in an effective QED$_{3}$ theory of d-wave high temperature cuprate superconductors under a uniform magnetic field. At zero temperature, the external magnetic field induces a mixed state by generating vortices in the condensate of charged holons. The growing magnetic field suppresses the superfluid density and thus reduces the gauge field mass which is opened via the Anderson-Higgs mechanism. By numerically solving the Dyson-Schwinger gap...
Source: http://arxiv.org/abs/1203.6423v1
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by Morgan W. Mitchell; Marco Koschorreck; Marcin Kubasik; Mario Napolitano; Robert J. Sewell
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An extensive debate on quantum non-demolition (QND) measurement, reviewed in Grangier et al. [Nature, {\bf 396}, 537 (1998)], finds that true QND measurements must have both non-classical state-preparation capability and non-classical information-damage tradeoff. Existing figures of merit for these non-classicality criteria require direct measurement of the signal variable and are thus difficult to apply to optically-probed material systems. Here we describe a method to demonstrate both...
Source: http://arxiv.org/abs/1203.6584v1
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by Yannick Chevalier; Mounira Kourjieh
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We present in this paper a new procedure to saturate a set of clauses with respect to a well-founded ordering on ground atoms such that A < B implies Var(A) {\subseteq} Var(B) for every atoms A and B. This condition is satisfied by any atom ordering compatible with a lexicographic, recursive, or multiset path ordering on terms. Our saturation procedure is based on a priori ordered resolution and its main novelty is the on-the-fly construction of a finite complexity atom ordering. In contrast...
Source: http://arxiv.org/abs/1203.2809v1
We present the results of a search for pair production of scalar bottom quarks ($\tilde b_1$) and scalar third-generation leptoquarks ($LQ_3$) in a data sample of 5.2 $fb^{-1}$ collected by the D0 experiment at the Tevatron, the $p\bar{p}$ collider at Fermilab. We assume that sbottoms decay to a neutralino ($\tilde \chi^0_1$) and a b quark, and we set 95% C.L. lower limits on their production in the ($m_{\tilde b_1}$, $m_{\tilde \chi^0_1}$) mass plane such that $m_{\tilde b_1} > 247$ GeV for...
Source: http://arxiv.org/abs/1203.6800v1
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by Mohsen Sardari; Ahmad Beirami; Faramarz Fekri
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Recently, the existence of considerable amount of redundancy in the Internet traffic has stimulated the deployment of several redundancy elimination techniques within the network. These techniques are often based on either packet-level Redundancy Elimination (RE) or Content-Centric Networking (CCN). However, these techniques cannot exploit sub-packet redundancies. Further, other alternative techniques such as the end-to-end universal compression solutions would not perform well either over the...
Source: http://arxiv.org/abs/1203.6864v1
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by D. Wilms; P. Virnau; S. Sengupta; K. Binder
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Langevin Dynamics simulations are used to study the effect of shear on a two-dimensional colloidal crystal confined by structured parallel walls. When walls are sheared very slowly, only two or three crystalline layers next to the walls move along with them, while the inner layers of the crystal are only slightly tilted. At higher shear velocities, this inner part of the crystal breaks into several pieces with different orientations. The velocity profile across the slit is reminiscent of...
Source: http://arxiv.org/abs/1203.3669v1
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by Mehdi Talamali; Viljo Petäjä; Damien Vandembroucq; Stéphane Roux
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A mesoscopic model for shear plasticity of amorphous materials in two dimensions is introduced, and studied through numerical simulations in order to elucidate the macroscopic (large scale) mechanical behavior. Plastic deformation is assumed to occur through a series of local reorganizations. Using a discretization of the mechanical fields on a discrete lattice, local reorganizations are modeled as local slip events. Local yield stresses are randomly distributed in space and invariant in time....
Source: http://arxiv.org/abs/1005.2463v3
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by A. Hill; A. Sinner; K. Ziegler
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We calculate the optical Hall conductivity within the Kubo formalism for systems with gapped spectral nodes, where the latter have a power-law dispersion with exponent n. The optical conductivity is proportional to n and there is a characteristic logarithmic singularity as the frequency approaches the gap energy. The optical Hall conductivity is almost unaffected by thermal fluctuations and disorder for n=1, whereas disorder has a stronger effect on transport properties if n=2.
Source: http://arxiv.org/abs/1005.3211v3
For a semi-abelian variety over a global function field which is isogenous to an isotrivial one, we show that on the product of local points of a subvariety satisfying a minor condition, the topological closure of a finitely generated subgroup of %the group of its global points cuts out exactly the global points of the subvariety lying in this subgroup. As a corollary, on every non-isotrivial super-singular curve of genus two over a global function field, we conclude that the Brauer-Manin...
Source: http://arxiv.org/abs/1005.4998v3
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by Francis Bach; Simon Lacoste-Julien; Guillaume Obozinski
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We show that the herding procedure of Welling (2009) takes exactly the form of a standard convex optimization algorithm--namely a conditional gradient algorithm minimizing a quadratic moment discrepancy. This link enables us to invoke convergence results from convex optimization and to consider faster alternatives for the task of approximating integrals in a reproducing kernel Hilbert space. We study the behavior of the different variants through numerical simulations. The experiments indicate...
Source: http://arxiv.org/abs/1203.4523v2
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by Maria Rita Casali; Paola Cristofori; Michele Mulazzani
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The idea of computing Matveev complexity by using Heegaard decompositions has been recently developed by two different approaches: the first one for closed 3-manifolds via crystallization theory, yielding the notion of Gem-Matveev complexity; the other one for compact orientable 3-manifolds via generalized Heegaard diagrams, yielding the notion of modified Heegaard complexity. In this paper we extend to the non-orientable case the definition of modified Heegaard complexity and prove that for...
Source: http://arxiv.org/abs/1203.0183v1
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by M. Emin Ozdemir; Ahmet Ocak Akdemir; Mevlut Tunc
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In this paper, we establish some new inequalities of the Hermite-Hadamard like for class of (h-s)_{1,2}-convex functions which are ordinary, super-multiplicative or similarly ordered and nonnegative.
Source: http://arxiv.org/abs/1203.3698v1
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The $\beta$ function for a scalar field theory describes the dependence of the coupling constant on the renormalization mass scale. This dependence is affected by the choice of regularization scheme. I explicitly relate the $\beta$-functions of momentum cut-off regularization and dimensional regularization on scalar field theories by a gauge transformation using the Hopf algebras of the Feynman diagrams of the theories.
Source: http://arxiv.org/abs/1107.5533v2
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I present a brief review on space and time in different periods of physics, and then talk on the nature of space and time from physical arguments. I discuss the ways to test such a new perspective on space and time through searching for Lorentz violation in some physical processes. I also make an introduce to a newly proposed theory of Lorentz violation from basic considerations.
Source: http://arxiv.org/abs/1203.5852v2
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by Mancho Manev; Miroslava Ivanova
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The canonical-type connection on the almost contact manifolds with B-metric is constructed. It is proved that its torsion is invariant with respect to a subgroup of the general conformal transformations of the almost contact B-metric structure. The basic classes of the considered manifolds are characterized in terms of the torsion of the canonical-type connection.
Source: http://arxiv.org/abs/1203.0137v3
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by S. Quaglioni; P. Navratil; R. Roth; W. Horiuchi
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Nuclei are prototypes of many-body open quantum systems. Complex aggregates of protons and neutrons that interact through forces arising from quantum chromo-dynamics, nuclei exhibit both bound and unbound states, which can be strongly coupled. In this respect, one of the major challenges for computational nuclear physics, is to provide a unified description of structural and reaction properties of nuclei that is based on the fundamental underlying physics: the constituent nucleons and the...
Source: http://arxiv.org/abs/1203.0268v1
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by Ai Min Chen; Sam Young Cho; Mun Dae Kim
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Single-step implementations of multi-qubit gates are generally believed to provide a simpler design, a faster operation, and a lower decoherence. For coupled three qubits interacting with a photon field, a realizable scheme for a single-step Toffoli gate is investigated. We find that the three qubit system can be described by four effective modified Jaynes-Cummings models in the states of two control qubits. Within the rotating wave approximation, the modified Jaynes-Cummings models are shown...
Source: http://arxiv.org/abs/1203.0374v1
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The Negative Binomial distribution becomes highly skewed under extreme dispersion. Even at moderately large sample sizes, the sample mean exhibits a heavy right tail. The standard Normal approximation often does not provide adequate inferences about the data's mean in this setting. In previous work, we have examined alternative methods of generating confidence intervals for the expected value. These methods were based upon Gamma and Chi Square approximations or tail probability bounds such as...
Source: http://arxiv.org/abs/1203.0813v1
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We study the linear perturbation of the recently proposed model of inflation where a uniform gauge-kinetic coupling of the inflaton to multiple vector fields breaks the cosmic no-hair conjecture while maintaining the isotropy. We derive the general quadratic action for the perturbation and calculate the power spectra of scalar and tensor modes at the end of inflation by in-in formalism. It is shown that the model predicts slightly red spectra and the tensor-to-scalar ratio tends to be...
Source: http://arxiv.org/abs/1203.1071v3
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This is a continuation of our previous paper. We consider a certain order-like relation for positive operators on a Hilbert space. This relation is defined by using the Jensen inequality with respect to the square-root function. We show that this relation is antisymmetric if the operators are invertible.
Source: http://arxiv.org/abs/1203.1154v1
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In the mini-superspace approximation to cosmology, the canonical measure can be used to compute probabilities when a cutoff is introduced in the phase space to regularize the divergent measure. However, the region initially constrained by a simple cutoff evolves non-trivially under the Hamiltonian flow. We determine the deformation of the regularized phase space along the orbits when a cutoff is introduced for the scale factor of the universe or for the Hubble parameter. In the former case, we...
Source: http://arxiv.org/abs/1203.2807v2
We provide a comment on "Velocity slip coefficients based on the hard-sphere Boltzmann equation" by Livio Gibelli published in Phys. Fluids 24, 022001 (2012).
Source: http://arxiv.org/abs/1203.3021v2
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by Riccardo Barbieri; Dario Buttazzo; Filippo Sala; David M. Straub
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The quark sector of the Standard Model exhibits an approximate U(2)^3 flavour symmetry. This symmetry, broken in specific directions dictated by minimality, can explain the success of the Cabibbo-Kobayashi-Maskawa picture of flavour mixing and CP violation, confirmed by the data so far, while allowing for observable deviations from it, as expected in most models of ElectroWeak Symmetry Breaking. Building on previous work in the specific context of supersymmetry, we analyze the expected effects...
Source: http://arxiv.org/abs/1203.4218v1
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Biopolymer networks are of fundamental importance to many biological processes in normal and tumorous tissues. In this paper, we employ the panoply of theoretical and simulation techniques developed for characterizing heterogeneous materials to quantify the microstructure and effective diffusive transport properties (diffusion coefficient $D_e$ and mean survival time $\tau$) of collagen type I networks at various collagen concentrations. In particular, we compute the pore-size probability...
Source: http://arxiv.org/abs/1203.4823v1
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by Clotilde Fermanian-Kammerer; Patrick Gérard; Caroline Lasser
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We study the evolution of Wigner measures of a family of solutions of a Schr\"odinger equation with a scalar potential displaying a conical singularity. Under a genericity assumption, classical trajectories exist and are unique, thus the question of the propagation of Wigner measures along these trajectories becomes relevant. We prove the propagation for general initial data.
Source: http://arxiv.org/abs/1203.5047v1
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by Ali Kebarighotbi; Christos G. Cassandras
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We extend the definition of a Stochastic Hybrid Automaton (SHA) to overcome limitations that make it difficult to use for on-line control. Since guard sets do not specify the exact event causing a transition, we introduce a clock structure (borrowed from timed automata), timer states, and guard functions that disambiguate how transitions occur. In the modified SHA, we formally show that every transition is associated with an explicit element of an underlying event set. This also makes it...
Source: http://arxiv.org/abs/1203.5165v1
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In this note we review the construction of topologically gauged M2 branes with 6 supersymmetries and discuss some of its properties. This is done using the 3-algebra formulation thereby covering all possible gauge groups. We will elaborate upon 1) the fundamental identity and its solutions noting, provided these gauged theories describe stacks of branes, the case of a single brane, 2) the chiral point solution to the field equations (occuring even for a single brane) that breaks the...
Source: http://arxiv.org/abs/1203.5090v1
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by Vladislav Kargin
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It is shown that the normalized fluctuations of Riemann's zeta zeros around their predicted locations follow the Gaussian law. It is also shown that fluctuations of two zeros, \gamma_k and \gamma_{k+x}, with x asymptotically equal to \alpha(\log k)^{\beta}, with \beta>0, for large k follow the two-variate Gaussian distribution with correlation (1-\beta)_+.
Source: http://arxiv.org/abs/1203.5309v1
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by N. G. Guseva; Y. I. Izotov; K. J. Fricke; C. Henkel
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(abridged) Strongly star-forming galaxies of subsolar metallicities are typical of the high-redshift universe. Here we therefore provide accurate data for two low-z analogs, the well-known low-metallicity emission-line galaxies Haro 11 and ESO 338-IG 004. On the basis of Very Large Telescope/X-shooter spectroscopic observations in the wavelength range 3000-24000\AA, we use standard direct methods to derive physical conditions and element abundances. Furthermore, we use X-shooter data together...
Source: http://arxiv.org/abs/1203.5268v1
This paper describes a new approach to the optimization of information extraction in multi-wavelength image cubes of cosmological fields. The objective is to create a framework for the automatic identification and tagging of sources according to various criteria (isolated source, partially overlapped, fully overlapped, cross-matched, etc) and to set the basis for the automatic production of the SEDs (spectral energy distributions) for all objects detected in the many multi-wavelength images in...
Source: http://arxiv.org/abs/1203.6052v2
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by L. E. Bleem; A. van Engelen; G. P. Holder; K. A. Aird; R. Armstrong; M. L. N. Ashby; M. R. Becker; B. A. Benson; T. Biesiadzinski; M. Brodwin; M. T. Busha; J. E. Carlstrom; C. L. Chang; H. M. Cho; T. M. Crawford; A. T. Crites; T. de Haan; S. Desai; M. A. Dobbs; O. Doré; J. Dudley; J. E. Geach; E. M. George; M. D. Gladders; A. H. Gonzalez; N. W. Halverson; N. Harrington; F. W. High; B. P. Holden; W. L. Holzapfel; S. Hoover; J. D. Hrubes; M. Joy; R. Keisler; L. Knox; A. T. Lee; E. M. Leitch; M....
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We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, the Wide-field Infrared Survey Explorer, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 square degrees of sky, we detect correlation between the SPT convergence maps and each of the galaxy density maps at >4 sigma, with zero...
Source: http://arxiv.org/abs/1203.4808v3
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by Viktor Bekkert; Georgia Benkart; Vyacheslav Futorny; Iryna Kashuba
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We study $\mathbb Z$-graded modules of nonzero level with arbitrary weight multiplicities over Heisenberg Lie algebras and the associated generalized loop modules over affine Kac-Moody Lie algebras. We construct new families of such irreducible modules over Heisenberg Lie algebras. Our main result establishes the irreducibility of the corresponding generalized loop modules providing an explicit construction of many new examples of irreducible modules for affine Lie algebras. In particular, to...
Source: http://arxiv.org/abs/1107.0893v2
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The transverse Ising Model (TIM) in one dimension is the simplest model which exhibits a quantum phase transition (QPT). Quantities related to quantum information theoretic measures like entanglement, quantum discord (QD) and fidelity are known to provide signatures of QPTs. The issue is less well explored when the quantum system is subjected to decoherence due to its interaction, represented by a quantum channel, with an environment. In this paper we study the dynamics of the mutual...
Source: http://arxiv.org/abs/1107.3939v2
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Charge-exchange (CE) emission produces features which are detectable with the current X-ray instrumentation in the brightest near galaxies. We describe these aspects in the observed X-ray spectra of the star forming galaxies M82 and NGC 3256, from the Suzaku and XMM-Newton telescopes. Emission from both ions (O, C) and neutrals (Mg, Si) is recognised. We also describe how microcalorimeter instrumentation on future missions will improve CE observations.
Source: http://arxiv.org/abs/1203.0941v1
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by Olivier Fercoq
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We give a new link spam detection and PageRank demotion algorithm called MaxRank. Like TrustRank and AntiTrustRank, it starts with a seed of hand-picked trusted and spam pages. We define the MaxRank of a page as the frequency of visit of this page by a random surfer minimizing an average cost per time unit. On a given page, the random surfer selects a set of hyperlinks and clicks with uniform probability on any of these hyperlinks. The cost function penalizes spam pages and hyperlink removals....
Source: http://arxiv.org/abs/1203.1457v1
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by Robert Biele; Carsten Timm; Roberto D'Agosta
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Stochastic methods form a general framework for investigating the generally non-Markovian dynamics of a quantum-mechanical system coupled to an environment. They promise to be computationally superior to the master-equation approach, which is numerically expensive for large dimensions of the system Hilbert space. A stochastic Schr\"odinger equation that is local in time but nevertheless reproduces the dynamics of a non-Markovian master equation would be particularly useful. Here, we derive...
Source: http://arxiv.org/abs/1203.3785v1
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For a finite family of 3-dimensional almost contact metric manifolds with closed the structure form $\eta$ is described a construction of an almost contact metric manifold, where the members of the family are building blocks - cells. Obtained manifold share many properties of cells. One of the more important are nullity conditions. If cells satisfy nullity conditions - then - in the case of almost cosymplectic or almost $\alpha$-Kenmotsu manifolds - "sewed cells" also satisfies...
Source: http://arxiv.org/abs/1203.4778v2
Consider the following forest-fire process on a connected graph. Each site of the graph can be either occupied or vacant. A vacant site becomes occupied with rate 1. A site is ignited with rate lambda, and its whole occupied cluster burns instantaneously. The purpose of this paper is to show the existence of a stationary distribution for forest-fire processes on Z^d, for d >= 2. We define a distribution as a limit of a sequence of invariant distributions of finite volume forest-fire...
Source: http://arxiv.org/abs/1203.5533v1
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by Zhicheng Zhong; G. Koster; Paul J. Kelly
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Competition between electronic and atomic reconstruction is a constantly recurring theme in transition-metal oxides. We use density functional theory calculations to study this competition for a model system consisting of a thin film of the polar, infinite-layer structure ACuO2 (A=Ca, Sr, Ba) grown on a nonpolar, perovskite SrTiO3 substrate. A transition from the bulk planar structure to a chain-type thin film accompanied by substantial changes to the electronic structure is predicted for a...
Source: http://arxiv.org/abs/1203.5686v1
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The most popular ways to test for independence of two ordinal random variables are by means of Kendall's tau and Spearman's rho. However, such tests are not consistent, only having power for alternatives with `monotonic' association. In this paper we introduce a natural extension of Kendall's tau, called $\tau^*$, which is nonnegative and zero if and only if independence holds, thus leading to a consistent independence test. Furthermore, normalization gives a rank correlation which can be used...
Source: http://arxiv.org/abs/1007.4259v5
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by S. C. Hou; M. A. Khan; Daoyi Dong; Ian R. Petersen; X. X. Yi
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Quantum Lyapunov control was developed in order to transform a quantum system from arbitrary initial states to a target state. The idea is to find control fields that steer the Lyapunov function to zero as $t\rightarrow \infty$, meanwhile the quantum system is driven to the target state. In order to shorten the time required to reach the target state, we propose two designs to optimize Lyapunov control in this paper. The first design makes the Lyapunov function decrease as fast as possible with...
Source: http://arxiv.org/abs/1203.5373v2
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by Paolo Cascini; De-Qi Zhang
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We describe a bound on the degree of the generators for some adjoint rings on surfaces and threefolds.
Source: http://arxiv.org/abs/1203.5204v1
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by Roman Kompaneets; Alexei V. Ivlev; Sergey V. Vladimirov; Gregor E. Morfill
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The fundamental higher-order Landau plasma modes are known to be generally heavily damped. We show that these modes for the ion component in a weakly ionized plasma can be substantially modified by ion-neutral collisions and a dc electric field driving ion flow so that some of them can become unstable. This instability is expected to naturally occur in presheaths of gas discharges at sufficiently small pressures and thus affect sheaths and discharge structures.
Source: http://arxiv.org/abs/1007.0142v3
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by Omer Angel; Alexander E. Holroyd; Gady Kozma; Johan Wästlund; Peter Winkler
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A dyadic tile of order n is any rectangle obtained from the unit square by n successive bisections by horizontal or vertical cuts. Let each dyadic tile of order n be available with probability p, independently of the others. We prove that for p sufficiently close to 1, there exists a set of pairwise disjoint available tiles whose union is the unit square, with probability tending to 1 as n->infinity, as conjectured by Joel Spencer in 1999. In particular we prove that if p=7/8, such a tiling...
Source: http://arxiv.org/abs/1107.2636v3
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by Martin Lazar; Darko Mitrovic
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We prove that the sequence of averaged quantities $\int_{\R^m}u_n(\mx,\msnop)$ $\rho(\msnop)d\msnop$, is strongly precompact in $\Ldl\Rd$, where $\rho\in \Ldc{\R^m}$, and $u_n\in \Ld{\R^m; \pL s\Rd}$, $s\geq 2$, are weak solutions to differential operator equations with variable coefficients. In particular, this includes differential operators of hyperbolic, parabolic or ultraparabolic type, but also fractional differential operators. If $s>2$ then the coefficients can be discontinuous with...
Source: http://arxiv.org/abs/1107.2616v3
The ad-atom dynamic equation, a Langevin type equation is analyzed and solved using some non-linear analytical and numerical tools. We noticeably show that the effect of the surface acoustic wave is to induce an effective potential that governs the diffusion of the ad-atom: the minima of this effective potential correspond to the preferential sites in which the ad-atom spends more time. The strength of this effective potential is compared to the destructuring role of the thermal diffusion and...
Source: http://arxiv.org/abs/1203.2812v1
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by Emil Saucan
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We introduce a metric notion of Ricci curvature for $PL$ manifolds and study its convergence properties. We also prove a fitting version of the Bonnet-Myers Theorem, for surfaces as well as for a large class of higher dimensional manifolds.
Source: http://arxiv.org/abs/1203.1592v1