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Title: Differential Recursion and Differentially Algebraic FunctionsCategory: cs.CCAuthors: Akitoshi KawamuraStudy Abstract: Moore introduced a class of real-valued "recursive" functions by analogy with Kleene's formulation of the standard recursive functions. While his concise definition inspired a new line of research on analog computation, it contains some technical inaccuracies. Focusing on his "primitive recursive" functions, we pin down what is problematic and discuss possible attempts to remove the ambiguity regarding the behavior of the differential recursion operator on partial functions. It turns out that in any case the purported relation to differentially algebraic functions, and hence to Shannon's model of analog computation, fails. Comments: 14 pages, 3 figures

Title: Spline Single-Index Prediction ModelCategory: math.ST stat.THAuthors: Li Wang and Lijian YangStudy Abstract: For the past two decades, single-index model, a special case of projection pursuit regression, has proven to be an efficient way of coping with the high dimensional problem in nonparametric regression. In this paper, based on weakly dependent sample, we investigate the single-index prediction (SIP) model which is robust against deviation from the single-index model. The single-index is identified by the best approximation to the multivariate prediction function of the response variable, regardless of whether the prediction function is a genuine single-index function. A polynomial spline estimator is proposed for the single-index prediction coefficients, and is shown to be root-n consistent and asymptotically normal. An iterative optimization routine is used which is sufficiently fast for the user to analyze large data of high dimension within seconds. Simulation experiments have provided strong evidence that corroborates with the asymptotic theory. Application of the proposed procedure to the rive flow data of Iceland has yielded superior out-of-sample rolling forecasts. Comments: 39 pages,5 figures

Title: Measurement of the Aerosol Phase Function at the Pierre Auger ObservatoryCategory: astro-ph physics.ao-phAuthors: S.Y. BenZvi, B.M. Connolly, J.A.J. Matthews, M. Prouza, E.F. Visbal, S. WesterhoffStudy Abstract: Air fluorescence detectors measure the energy of ultra-high energy cosmic rays by collecting fluorescence light emitted from nitrogen molecules along the extensive air shower cascade. To ensure a reliable energy determination, the light signal needs to be corrected for atmospheric effects, which not only attenuate the signal, but also produce a non-negligible background component due to scattered Cherenkov light and multiple-scattered light. The correction requires regular measurements of the aerosol attenuation length and the aerosol phase function, defined as the probability of light scattered in a given direction. At the Pierre Auger Observatory in Malargue, Argentina, the phase function is measured on an hourly basis using two Aerosol Phase Function (APF) light sources. These sources direct a UV light beam across the field of view of the fluorescence detectors; the phase function can be extracted from the image of the shots in the fluorescence detector cameras. This paper describes the design, current status, standard operation procedure, and performance of the APF system at the Pierre Auger Observatory. Comments: 19 pages, 10 figures (4 in color), replaced with version accepted for publication in Astroparticle Physics

Title: The World as Evolving InformationCategory: cs.IT cs.AI math.IT q-bio.PEAuthors: Carlos GershensonStudy Abstract: This paper discusses the benefits of describing the world as information, especially in the study of the evolution of life and cognition. Traditional studies encounter problems because it is difficult to describe life and cognition in terms of matter and energy, since their laws are valid only at the physical scale. However, if matter and energy, as well as life and cognition, are described in terms of information, evolution can be described consistently as information becoming more complex. The paper presents eight tentative laws of information, valid at multiple scales, which are generalizations of Darwinian, cybernetic, thermodynamic, psychological, philosophical, and complexity principles. These are further used to discuss the notions of life, cognition and their evolution. Comments: 16 pages. Extended version, three more laws of information, two classifications, and discussion added. To be published (soon) in International Conference on Complex Systems 2007 Proceedings

Title: Polymerization Force Driven Buckling of Microtubule Bundles Determines the Wavelength of Patterns Formed in Tubulin SolutionsCategory: physics.bio-phAuthors: Yongxing Guo, Yifeng Liu, Jay X. Tang, and James M. Valles JrStudy Abstract: We present a model for the spontaneous formation of a striated pattern in polymerizing microtubule solutions. It describes the buckling of a single microtubule (MT) bundle within an elastic network formed by other similarly aligned and buckling bundles and unaligned MTs. Phase contrast and polarization microscopy studies of the temporal evolution of the pattern imply that the polymerization of MTs within the bundles creates the driving compressional force. Using the measured rate of buckling, the established MT force-velocity curve and the pattern wavelength, we obtain reasonable estimates for the MT bundle bending rigidity and the elastic constant of the network. The analysis implies that the bundles buckle as solid rods. Comments: 4 pages, 4 figures

Title: Neutron Inelastic Scattering Processes as Background for Double-Beta Decay ExperimentsCategory: nucl-ex hep-exAuthors: D.-M. Mei, S.R. Elliott, A. Hime, V. Gehman and K. KazkazStudy Abstract: We investigate several Pb$(n,n'\gamma$) and Ge$(n,n'\gamma$) reactions. We measure $\gamma$-ray production from Pb$(n,n'\gamma$) reactions that can be a significant background for double-beta decay experiments which use lead as a massive inner shield. Particularly worrisome for Ge-based double-beta decay experiments are the 2041-keV and 3062-keV $\gamma$ rays produced via Pb$(n,n'\gamma$). The former is very close to the ^{76}Ge double-beta decay endpoint energy and the latter has a double escape peak energy near the endpoint. Excitation $\gamma$-ray lines from Ge$(n,n'\gamma$) reactions are also observed. We consider the contribution of such backgrounds and their impact on the sensitivity of next-generation searches for neutrinoless double-beta decay using enriched germanium detectors. Comments: 16 pages, 7 figures

Title: Periodic accretion from a circumbinary disk in the young binary UZ Tau ECategory: astro-phAuthors: Eric L. N. Jensen (1), Saurav Dhital (1,2), Keivan G. Stassun (2), Jenny Patience (3), William Herbst (4), Frederick M. Walter (5), Michal Simon (5), Gibor Basri (6); (1 - Swarthmore College; 2 - Vanderbilt; 3 - Caltech; 4 - Wesleyan University; 5 - SUNY Stony Brook; 6 - UC Berkeley)Study Abstract: Close pre-main-sequence binary stars are expected to clear central holes in their protoplanetary disks, but the extent to which material can flow from the circumbinary disk across the gap onto the individual circumstellar disks has been unclear. In binaries with eccentric orbits, periodic perturbation of the outer disk is predicted to induce mass flow across the gap, resulting in accretion that varies with the binary period. This accretion may manifest itself observationally as periodic changes in luminosity. Here we present a search for such periodic accretion in the pre-main-sequence spectroscopic binary UZ Tau E. We present BVRI photometry spanning three years; we find that the brightness of UZ Tau E is clearly periodic, with a best-fit period of 19.16 +/- 0.04 days. This is consistent with the spectroscopic binary period of 19.13 days, refined here from analysis of new and existing radial velocity data. The brightness of UZ Tau E shows significant random variability, but the overall periodic pattern is a broad peak in enhanced brightness, spanning more than half the binary orbital period. The variability of the H-alpha line is not as clearly periodic, but given the sparseness of the data, some periodic component is not ruled out. The photometric variations are in good agreement with predictions from simulations of binaries with orbital parameters similar to those of UZ Tau E, suggesting that periodic accretion does occur from circumbinary disks, replenishing the inner disks and possibly extending the timescale over which they might form planets. Comments: Accepted by the Astronomical Journal; to appear July 2007; Corrected minor typos

Title: Effect of node deleting on network structureCategory: physics.soc-phAuthors: Ke Deng, Heping Zhao, Dejun LiStudy Abstract: The ever-increasing knowledge of the structure of various real-world networks has uncovered their complex multi-mechanism-governed evolution processes. Therefore, a better understanding of the structure and evolution of these networked complex systems requires us to describe such processes in a more detailed and realistic manner. In this paper, we introduce a new type of network growth rule which comprises addition and deletion of nodes, and propose an evolving network model to investigate the effect of node deleting on network structure. It is found that, with the introduction of node deleting, network structure is significantly transformed. In particular, degree distribution of the network undergoes a transition from scale-free to exponential forms as the intensity of node deleting increases. At the same time, nontrivial disassortative degree correlation develops spontaneously as a natural result of network evolution in the model. We also demonstrate that node deleting introduced in the model does not destroy the connectedness of a growing network so long as the increasing rate of edges is not excessively small. In addition, it is found that node deleting will weaken but not eliminate the small-world effect of a growing network, and generally it will decrease the clustering coefficient in a network. Comments: 12 pages, 9 figures, to be published in physica a

Title: The Complexity of HCP in Digraps with Degree Bound TwoCategory: cs.CC cs.DMAuthors: Guohun ZhuStudy Abstract: The Hamiltonian cycle problem (HCP) in digraphs D with degree bound two is solved by two mappings in this paper. The first bijection is between an incidence matrix C_{nm} of simple digraph and an incidence matrix F of balanced bipartite undirected graph G; The second mapping is from a perfect matching of G to a cycle of D. It proves that the complexity of HCP in D is polynomial, and finding a second non-isomorphism Hamiltonian cycle from a given Hamiltonian digraph with degree bound two is also polynomial. Lastly it deduces P=NP base on the results. Comments: 10 pages, 4 figures, had been submitted to a Journal

Title: VLBI observations of nineteen GHz-Peaked-Spectrum radio sources at 1.6 GHzCategory: astro-phAuthors: Xiang Liu, Lang Cui, Wen-Feng Luo, Wei-Zhao Shi, Hua-Gang Song (Urumqi Observatory, NAOC)Study Abstract: Aims and Methods: We present the results of VLBI observations of nineteen GHz-Peaked-Spectrum (GPS) radio sources at 1.6 GHz. Of them, 15 sources are selected from the Parkes Half Jansky (PHJ) sample (Snellen 2002), 4 others are from our previous observation list. We aimed at imaging the structure of GPS sources, searching for Compact Symmetric Objects (CSOs) and studying the absorption for the convex radio spectra of GPS sources. Results: We obtained total intensity 1.6 GHz VLBI images of 17 sources for the first time. Of them, 80% show mini-double-lobe radio structure, indicating that they are CSOs or candidates, and their host AGNs could be edge-on to us. This result suggests that there is a high incidence of mini double-lobe sources (or CSOs) in the PHJ sample. The sources J0323+0534, J1135-0021, J1352+0232, J2058+0540, J2123-0112 and J2325-0344 with measured redshift, showing double-lobe structure with sizes of <1 kpc, are classified as CSOs. Three sources J1057+0012, J1600-0037 and J1753+2750 are considered as core-jet sources according to their morphologies and flux variability. Comments: 11 pages, 12 figures, to appear in AA

Title: Moment switching in nanotube magnetic force probesCategory: cond-mat.mes-hall cond-mat.mtrl-sciAuthors: John R. Kirtley, Zhifeng Deng, Lan Luan, Erhan Yenilmez, Hongjie Dai, and Kathryn A. MolerStudy Abstract: A recent advance in improving the spatial resolution of magnetic force microscopy (MFM) uses as sensor tips carbon nanotubes grown at the apex of conventional silicon cantilever pyramids and coated with a thin ferromagnetic layer. Magnetic images of high density vertically recorded media using these tips exhibit a doubling of the spatial frequency under some conditions. Here we demonstrate that this spatial frequency doubling is due to the switching of the moment direction of the nanotube tip. This results in a signal which is proportional to the absolute value of the signal normally observed in MFM. Our modeling indicates that a significant fraction of the tip volume is involved in the observed switching, and that it should be possible to image very high bit densities with nanotube magnetic force sensors. Comments: 10 pages

Title: Power Spectra to 1% Accuracy between Dynamical Dark Energy CosmologiesCategory: astro-phAuthors: Matthew J. Francis, Geraint F. Lewis, Eric V. LinderStudy Abstract: For dynamical dark energy cosmologies we carry out a series of N-body gravitational simulations, achieving percent level accuracy in the relative mass power spectra at any redshift. Such accuracy in the power spectrum is necessary for next generation cosmological mass probes. Our matching procedure reproduces the CMB distance to last scattering and delivers subpercent level power spectra at z=0 and z~3. We discuss the physical implications for probing dark energy with surveys of large scale structure. Comments: 9 pages, 14 figures, submitted to MNRAS

Title: Possibility of Gapless Spin Liquid State by One-dimensionalizationCategory: cond-mat.str-elAuthors: Yuta Hayashi, Masao OgataStudy Abstract: Motivated by the observation of a gapless spin liquid state in $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$, we analyze the anisotropic triangular lattice $S=1/2$ Heisenberg model with the resonating valence bond mean-field approximation. Paying attention to the small quasi-one-dimensional anisotropy of the material, we take an approach from one-dimensional (1D) chains coupled with frustrating zig-zag bonds. By calculating one-particle excitation spectra changing anisotropy parameter $J'/J$ from the decoupled 1D chains to the isotropic triangular lattice, we find almost gapless excitations in the wide range from the 1D limit. This one-dimensionalization by frustration is considered to be a candidate for the mechanism of the gapless spin liquid state. Comments: 4 pages, 4 figures(downsized), To appear in J. Phys. Soc. Jpn.

Title: Extra dimensions and Lorentz invariance violationCategory: hep-ph astro-ph hep-thAuthors: Viktor Baukh, Alexander Zhuk, Tina KahniashviliStudy Abstract: We consider effective model where photons interact with scalar field corresponding to conformal excitations of the internal space (geometrical moduli/gravexcitons). We demonstrate that this interaction results in a modified dispersion relation for photons, and consequently, the photon group velocity depends on the energy implying the propagation time delay effect. We suggest to use the experimental bounds of the time delay of gamma ray bursts (GRBs) photons propagation as an additional constrain for the gravexciton parameters. Comments: RevTex, 5 pages, references added and minor changes. Corrected typos in title

Title: The small deviations of many-dimensional diffusion processes and rarefaction by boundariesCategory: math.PR math.APAuthors: Vitalii A. GasanenkoStudy Abstract: We lead the algorithm of expansion of sojourn probability of many-dimensional diffusion processes in small domain. The principal member of this expansion defines normalizing coefficient for special limit theorems. Comments: 10 pages

Title: The Millennium Galaxy Catalogue: The local supermassive black hole mass function in early- and late-type galaxiesCategory: astro-phAuthors: Alister W. Graham, Simon P. Driver, Paul D. Allen, Jochen LiskeStudy Abstract: We provide a new estimate of the local supermassive black hole mass function using (i) the empirical relation between supermassive black hole mass and the Sersic index of the host spheroidal stellar system and (ii) the measured (spheroid) Sersic indices drawn from 10k galaxies in the Millennium Galaxy Catalogue. The observational simplicity of our approach, and the direct measurements of the black hole predictor quantity, i.e. the Sersic index, for both elliptical galaxies and the bulges of disc galaxies makes it straightforward to estimate accurate black hole masses in early- and late-type galaxies alike. We have parameterised the supermassive black hole mass function with a Schechter function and find, at the low-mass end, a logarithmic slope (1+alpha) of ~0.7 for the full galaxy sample and ~1.0 for the early-type galaxy sample. Considering spheroidal stellar systems brighter than M_B = -18 mag, and integrating down to black hole masses of 10^6 M_sun, we find that the local mass density of supermassive black holes in early-type galaxies rho_{bh, early-type} = (3.5+/-1.2) x 10^5 h^3_{70} M_sun Mpc^{-3}, and in late-type galaxies rho_{bh, late-type} = (1.0+/-0.5) x 10^5 h^3_{70} M_sun Mpc^{-3}. The uncertainties are derived from Monte Carlo simulations which include uncertainties in the M_bh-n relation, the catalogue of Sersic indices, the galaxy weights and Malmquist bias. The combined, cosmological, supermassive black hole mass density is thus Omega_{bh, total} = (3.2+/-1.2) x 10^{-6} h_70. That is, using a new and independent method, we conclude that (0.007+/-0.003) h^3_{70} per cent of the universe's baryons are presently locked up in supermassive black holes at the centres of galaxies. Comments: 10 pages of text plus 5 of figs and refs. MNRAS, accepted.

Title: Complete Shrinking Ricci Solitons have Finite Fundamental GroupCategory: math.DGAuthors: William WylieStudy Abstract: We show that if a complete Riemannian manifold supports a vector field such that the Ricci tensor plus the Lie derivative of the metric with respect to the vector field has a positive lower bound, then the fundamental group is finite. In particular, it follows that complete shrinking Ricci solitons and complete smooth metric measure spaces with a positive lower bound on the Bakry-Emery tensor have finite fundamental group. The method of proof is to generalize arguments of Garcia-Rio and Fernandez-Lopez in the compact case. Comments: 4 pages, To appear in Proceedings of AMS

Title: Effects of Dirac sea on pion propagation in asymmetric nuclear matterCategory: nucl-th hep-phAuthors: Subhrajyoti Biswas and Abhee K. Dutt-MazumderStudy Abstract: We study pion propagation in asymmetric nuclear matter (ANM). One of the interesting consequences of pion propagation in ANM is the mode splitting for the different charged states of pions. First we describe the pion-nucleon dynamics using the non-chiral model where one starts with pseudoscalar (PS) $\pi$N coupling and the pseudovector (PV) representation is obtained via suitable non-linear field transformations. For both of these cases the effect of the Dirac sea is estimated. Subsequently, we present results using the chiral effective Lagrangian where the short-distance behavior (Dirac vacuum) is included by re-defining the field parameters as done in the modern effective field theory approach developed recently. The results are compared with the previous calculations for the case of symmetric nuclear matter (SNM). Closed form analytical results are presented for the effective pion masses and dispersion relations by making hard nucleon loop (HNL) approximation and suitable density expansion. Comments: Accepted for publication in PRC

Title: Probability distributions generated by fractional diffusion equationsCategory: cond-mat.stat-mechAuthors: Francesco Mainardi, Paolo Paradisi and Rudolf GorenfloStudy Abstract: Fractional calculus allows one to generalize the linear, one-dimensional, diffusion equation by replacing either the first time derivative or the second space derivative by a derivative of fractional order. The fundamental solutions of these equations provide probability density functions, evolving on time or variable in space, which are related to the class of stable distributions. This property is a noteworthy generalization of what happens for the standard diffusion equation and can be relevant in treating financial and economical problems where the stable probability distributions play a key role. Comments: 46 pages, 3 figures. International Workshop on Econophysics, Budapest, July 21-27, 1997.

Title: Fabrication of half metallicity in a ferromagnetic metalCategory: cond-mat.str-el cond-mat.mtrl-sciAuthors: Kalobaran MaitiStudy Abstract: We investigate the growth of half metallic phase in a ferromagnetic material using state-of-the-art full potential linearized augmented plane wave method. To address the issue, we have substituted Ti at the Ru-sites in SrRuO3, where SrRuO3 is a ferromagnetic material. Calculated results establish Ti4+ valence states (similar to SrTiO3), which was predicted experimentally. Thus, Ti substitution dilutes the Ru-O-Ru connectivity, which is manifested in the calculated results in the form of significant band narrowing leading to finite gap between t2g and eg bands. At 75% substitution, a large gap (> 2 eV) appears at the Fermi level, e_F in the up spin density of states, while the down spin states contributes at e_F characterizing the system a half-metallic ferromagnet. The t2g - eg gap can be tailored judiciously by tuning Ti concentrations to minimize thermal effects, which is often the major bottleneck to achieve high spin polarization at elevated temperatures in other materials. This study, thus, provides a novel but simple way to fabricate half-metallicity in ferromagnetic materials, which are potential candidates for spin-based technology. Comments: 4 pages, 5 figures

Title: Emergence of spatiotemporal chaos driven by far-field breakup of spiral waves in the plankton ecological systemsCategory: nlin.PS nlin.CD q-bio.PEAuthors: Quan-Xing Liu, Gui-Quan Sun, Bai-Lian Li and Zhen JinStudy Abstract: Alexander B. Medvinsky \emph{et al} [A. B. Medvinsky, I. A. Tikhonova, R. R. Aliev, B.-L. Li, Z.-S. Lin, and H. Malchow, Phys. Rev. E \textbf{64}, 021915 (2001)] and Marcus R. Garvie \emph{et al} [M. R. Garvie and C. Trenchea, SIAM J. Control. Optim. \textbf{46}, 775-791 (2007)] shown that the minimal spatially extended reaction-diffusion model of phytoplankton-zooplankton can exhibit both regular, chaotic behavior, and spatiotemporal patterns in a patchy environment. Based on that, the spatial plankton model is furtherly investigated by means of computer simulations and theoretical analysis in the present paper when its parameters would be expected in the case of mixed Turing-Hopf bifurcation region. Our results show that the spiral waves exist in that region and the spatiotemporal chaos emerge, which arise from the far-field breakup of the spiral waves over large ranges of diffusion coefficients of phytoplankton and zooplankton. Moreover, the spatiotemporal chaos arising from the far-field breakup of spiral waves does not gradually involve the whole space within that region. Our results are confirmed by means of computation spectra and nonlinear bifurcation of wave trains. Finally, we give some explanations about the spatially structured patterns from the community level. Comments: 9 Figures and 11 pages, REVTeX 4

Title: General sequential quantum cloningCategory: quant-phAuthors: Gui-Fang Dang, and Heng FanStudy Abstract: Some multipartite quantum states can be generated in a sequential manner which may be implemented by various physical setups like microwave and optical cavity QED, trapped ions, and quantum dots etc. We analyze the general N to M qubits Universal Quantum Cloning Machine (UQCM) within a sequential generation scheme. We show that the N to M sequential UQCM is available. The case of d-level quantum states sequential cloning is also presented. Comments: 4 pages

Title: On the pseudospectrum of elliptic quadratic differential operatorsCategory: math.APAuthors: Karel Pravda-StarovStudy Abstract: We study the pseudospectrum of a class of non-selfadjoint differential operators. Our work consists in a detailed study of the microlocal properties, which rule the spectral stability or instability phenomena appearing under small perturbations for elliptic quadratic differential operators. The class of elliptic quadratic differential operators stands for the class of operators defined in the Weyl quantization by complex-valued elliptic quadratic symbols. We establish in this paper a simple necessary and sufficient condition on the Weyl symbol of these operators, which ensures the stability of their spectra. When this condition is violated, we prove that it occurs some strong spectral instabilities for the high energies of these operators, in some regions which can be far away from their spectra. We give a precise geometrical description of them, which explains the results obtained for these operators in some numerical simulations giving the computation of false eigenvalues far from their spectra by algorithms for eigenvalues computing. Comments: 39 pages

Title: Fluctuation-dissipation relation on a Melde string in a turbulent flow, considerations on a "dynamical temperature"Category: cond-mat.stat-mech physics.ins-detAuthors: Vincent Grenard (Phys-ENS), Nicolas Garnier (Phys-ENS), Antoine Naert (Phys-ENS)Study Abstract: We report on measurements of the transverse fluctuations of a string in a turbulent air jet flow. Harmonic modes are excited by the fluctuating drag force, at different wave-numbers. This simple mechanical probe makes it possible to measure excitations of the flow at specific scales, averaged over space and time: it is a scale-resolved, global measurement. We also measure the dissipation associated to the string motion, and we consider the ratio of the fluctuations over dissipation (FDR). In an exploratory approach, we investigate the concept of {\it effective temperature} defined through the FDR. We compare our observations with other definitions of temperature in turbulence. From the theory of Kolmogorov (1941), we derive the exponent -11/3 expected for the spectrum of the fluctuations. This simple model and our experimental results are in good agreement, over the range of wave-numbers, and Reynolds number accessible ($74000 \leq Re \leq 170000$). Comments: 3,5 new printed pages

Title: On generalized entropy measures and pathwaysCategory: math.ST cond-mat.stat-mech stat.THAuthors: A.M. Mathai, H.J. HauboldStudy Abstract: Product probability property, known in the literature as statistical independence, is examined first. Then generalized entropies are introduced, all of which give generalizations to Shannon entropy. It is shown that the nature of the recursivity postulate automatically determines the logarithmic functional form for Shannon entropy. Due to the logarithmic nature, Shannon entropy naturally gives rise to additivity, when applied to situations having product probability property. It is argued that the natural process is non-additivity, important, for example, in statistical mechanics, even in product probability property situations and additivity can hold due to the involvement of a recursivity postulate leading to a logarithmic function. Generalizations, including Mathai's generalized entropy are introduced and some of the properties are examined. Situations are examined where Mathai's entropy leads to pathway models, exponential and power law behavior and related differential equations. Connection of Mathai's entropy to Kerridge's measure of "inaccuracy" is also explored. Comments: 12 pages, LaTeX, typos corrected

Title: Evolution of a band insulating phase from a correlated metallic phaseCategory: cond-mat.str-el cond-mat.mtrl-sciAuthors: Kalobaran Maiti, Ravi Shankar Singh, V.R.R. MedicherlaStudy Abstract: We investigate the evolution of the electronic structure in SrRu_(1-x)Ti_xO_3 as a function of x using high resolution photoemission spectroscopy, where SrRuO3 is a weakly correlated metal and SrTiO3 is a band insulator. The surface spectra exhibit a metal-insulator transition at x = 0.5 by opening up a soft gap. A hard gap appears at higher x values consistent with the transport properties. In contrast, the bulk spectra reveal a pseudogap at the Fermi level, and unusual evolution exhibiting an apparent broadening of the coherent feature and subsequent decrease in intensity of the lower Hubbard band with the increase in x. Interestingly, the first principle approaches are found to be sufficient to capture anomalous evolutions at high energy scale. Analysis of the spectral lineshape indicates strong interplay between disorder and electron correlation in the electronic properties of this system. Comments: 4 figures

Title: Electroweak phase transitions in the MSSM with an extra $U(1)'$Category: hep-phAuthors: S.W. Ham, E.J. Yoo, S.K. OHStudy Abstract: We investigate the possibility of electroweak phase transition in the minimal supersymmetric standard model (MSSM) with an extra $U(1)'$. This model has two Higgs doublets and a singlet, in addition to a singlet exotic quark superfield. We find that at the one-loop level this model may accommodate the electroweak phase transitions that are strongly first-order in a reasonably large region of the parameter space. In the parameter region where the phase transitions take place, we observe that the lightest scalar Higgs boson has a smaller mass when the strength of the phase transition becomes weaker. Also, the other three heavier neutral Higgs bosons get more large masses when the strength of the phase transition becomes weaker. Comments: 17 pages, 2 tables, 3 figures

Title: Solutions of fractional reaction-diffusion equations in terms of the H-functionCategory: math.PR math.CA math.ST stat.THAuthors: H.J. Haubold, A.M. Mathai, R.K. SaxenaStudy Abstract: This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation associated with the Caputo derivative as the time-derivative and Riesz-Feller fractional derivative as the space-derivative. The solution is derived by the application of the Laplace and Fourier transforms in closed form in terms of the H-function. The results derived are of general nature and include the results investigated earlier by many authors, notably by Mainardi et al. (2001, 2005) for the fundamental solution of the space-time fractional diffusion equation, and Saxena et al. (2006a, b) for fractional reaction- diffusion equations. The advantage of using Riesz-Feller derivative lies in the fact that the solution of the fractional reaction-diffusion equation containing this derivative includes the fundamental solution for space-time fractional diffusion, which itself is a generalization of neutral fractional diffusion, space-fractional diffusion, and time-fractional diffusion. These specialized types of diffusion can be interpreted as spatial probability density functions evolving in time and are expressible in terms of the H-functions in compact form. Comments: 9 pages, LaTeX, typos corrected

Title: Random Matrix Theory at Nonzero $\mu$ and $T$Category: hep-phAuthors: K. Splittorff and J.J.M. VerbaarschotStudy Abstract: We review applications of random matrix theory to QCD at nonzero temperature and chemical potential. The chiral phase transition of QCD and QCD-like theories is discussed in terms of eigenvalues of the Dirac operator. We show that for QCD at $\mu \ne 0$, which has a sign problem, the discontinuity in the chiral condensate is due to an alternative to the Banks-Casher relation. The severity of the sign problem is analyzed in the microscopic domain of QCD. Comments: Invited talk at YKIS2006, YITP-Kyoto, 10 pages, 10 figures

Title: Symmetries by base substitutions in the genetic code predict 2' or 3' aminoacylation of tRNAsCategory: q-bio.OTAuthors: J.-L. Jestin, C. Soule (IHES)Study Abstract: This letter reports complete sets of two-fold symmetries between partitions of the universal genetic code. By substituting bases at each position of the codons according to a fixed rule, it happens that properties of the degeneracy pattern or of tRNA aminoacylation specificity are exchanged. Comments: Accepted for publication in the Journal of Theoretical Biology

Title: The effect of a fifth large-scale space-time dimension on the conservation of energy in a four dimensional UniverseCategory: gr-qcAuthors: M.B. Gerrard and T.J. SumnerStudy Abstract: The effect of introducing a fifth large-scale space-time dimension to the equations of orbital dynamics was analysed in an earlier paper by the authors. The results showed good agreement with the observed flat rotation curves of galaxies and the Pioneer Anomaly. This analysis did not require the modification of Newtonian dynamics, but rather only their restatement in a five dimensional framework. The same analysis derived a acceleration parameter ar, which plays an important role in the restated equations of orbital dynamics, and suggested a value for ar. In this companion paper, the principle of conservation of energy is restated within the same five-dimensional framework. The resulting analysis provides an alternative route to estimating the value of ar, without reference to the equations of orbital dynamics, and based solely on key cosmological constants and parameters, including the gravitational constant, G. The same analysis suggests that: (i) the inverse square law of gravity may itself be due to the conservation of energy at the boundary between a four-dimensional universe and a fifth large-scale space-time dimension; and (ii) there is a limiting case for the Tulley-Fisher relationship linking the speed of light to the mass of the Universe. Comments: 9 pages, 2 figures version update to correct figure placement Final update to include corrected typos and two additional equations

Title: Optical properties of the Holstein-t-J model from dynamical mean-field theoryCategory: cond-mat.str-elAuthors: E. Cappelluti, S. Ciuchi, S. FratiniStudy Abstract: We employ dynamical mean-field theory to study the optical conductivity $\sigma(\omega)$ of one hole in the Holstein-t-J model. We provide an exact solution for $\sigma(\omega)$ in the limit of infinite connectivity. We apply our analysis to Nd$_{2-x}$Ce$_x$CuO$_4$. We show that our model can explain many features of the optical conductivity in this compounds in terms of magnetic/lattice polaron formation. Comments: Proceeding of SCES07 Conference

Title: A Multiphilic Descriptor for Chemical Reactivity and SelectivityCategory: physics.chem-phAuthors: J. Padmanabhan (1,2), R. Parthasarathi (2), M. Elango (2), V. Subramanian (2), B. S. Krishnamoorthy (1,3), S. Gutierrez-Oliva (4), A. Toro-Labbe (4), D. R. Roy (1) and P. K. Chattaraj (1)Study Abstract: In line with the local philicity concept proposed by Chattaraj et al. (Chattaraj, P. K.; Maiti, B.; Sarkar, U. J. Phys. Chem. A. 2003, 107, 4973) and a dual descriptor derived by Toro-Labbe and coworkers (Morell, C.; Grand, A.; Toro-Labbe, A. J. Phys. Chem. A. 2005, 109, 205), we propose a multiphilic descriptor. It is defined as the difference between nucleophilic (Wk+) and electrophilic (Wk-) condensed philicity functions. This descriptor is capable of simultaneously explaining the nucleophilicity and electrophilicity of the given atomic sites in the molecule. Variation of these quantities along the path of a soft reaction is also analyzed. Predictive ability of this descriptor has been successfully tested on the selected systems and reactions. Corresponding force profiles are also analyzed in some representative cases. Also, to study the intra- and intermolecular reactivities another related descriptor namely, the nucleophilicity excess (DelW-+) for a nucleophile, over the electrophilicity in it has been defined and tested on all-metal aromatic compounds. Comments: 38 pages, 8 figures, 11 tables

Title: Influence of Phonon dimensionality on Electron Energy RelaxationCategory: cond-mat.mes-hallAuthors: J. T. Karvonen and I. J. MaasiltaStudy Abstract: We studied experimentally the role of phonon dimensionality on electron-phonon (e-p) interaction in thin copper wires evaporated either on suspended silicon nitride membranes or on bulk substrates, at sub-Kelvin temperatures. The power emitted from electrons to phonons was measured using sensitive normal metal-insulator-superconductor (NIS) tunnel junction thermometers. Membrane thicknesses ranging from 30 nm to 750 nm were used to clearly see the onset of the effects of two-dimensional (2D) phonon system. We observed for the first time that a 2D phonon spectrum clearly changes the temperature dependence and strength of the e-p scattering rate, with the interaction becoming stronger at the lowest temperatures below $\sim$ 0.5 K for the 30 nm membranes. Comments: Phys. Rev. Lett. in press

Title: Phonon-mediated decay of an atom in a surface-induced potentialCategory: quant-phAuthors: Fam Le Kien, S. Dutta Gupta, and K. HakutaStudy Abstract: We study phonon-mediated transitions between translational levels of an atom in a surface-induced potential. We present a general master equation governing the dynamics of the translational states of the atom. In the framework of the Debye model, we derive compact expressions for the rates for both upward and downward transitions. Numerical calculations for the transition rates are performed for a deep silica-induced potential allowing for a large number of bound levels as well as free states of a cesium atom. The total absorption rate is shown to be determined mainly by the bound-to-bound transitions for deep bound levels and by bound-to-free transitions for shallow bound levels. Moreover, the phonon emission and absorption processes can be orders of magnitude larger for deep bound levels as compared to the shallow bound ones. We also study various types of transitions from free states. We show that, for thermal atomic cesium with temperature in the range from 100 $\mu$K to 400 $\mu$K in the vicinity of a silica surface with temperature of 300 K, the adsorption (free-to-bound decay) rate is about two times larger than the heating (free-to-free upward decay) rate, while the cooling (free-to-free downward decay) rate is negligible. Comments: 14 pages, 15 figures

Title: Infrared Evolution Equations: Method and ApplicationsCategory: hep-phAuthors: B.I. Ermolaev, M. Greco, S.I. TroyanStudy Abstract: It is a brief review on composing and solving Infrared Evolution Equations. They can be used in order to calculate amplitudes of high-energy reactions in different kinematic regions in the double-logarithmic approximation. Comments: Talk given at Cracow Epiphany conference on precision physics and Monte Carlos for LHS. 4-6 January 2007, Cracow, Poland. 12 pp, 3 figures.

Title: Cofibrations in the Category of Frolicher Spaces. Part ICategory: math.ATAuthors: B. Dugmore and PP. NtumbaStudy Abstract: Cofibrations are defined in the category of Fr\"olicher spaces by weakening the analog of the classical definition to enable smooth homotopy extensions to be more easily constructed, using flattened unit intervals. We later relate smooth cofibrations to smooth neighborhood deformation retracts. The notion of smooth neighborhood deformation retract gives rise to an analogous result that a closed Fr\"olicher subspace $A$ of the Fr\"olicher space $X$ is a smooth neighborhood deformation retract of $X$ if and only if the inclusion $i: A\hookrightarrow X$ comes from a certain subclass of cofibrations. As an application we construct the right Puppe sequence. Comments: 27 pages

Title: Experimental observation of structural crossover in binary mixtures of colloidal hard spheresCategory: cond-mat.soft cond-mat.dis-nnAuthors: J\"org Baumgartl, Roel P.A. Dullens, Marjolein Dijkstra, Roland Roth and Clemens BechingerStudy Abstract: Using confocal-microscopy we investigate the structure of binary mixtures of colloidal hard spheres with size ratio q=0.61. As a function of the packing fraction of the two particle species, we observe a marked change of the dominant wavelength in the pair correlation function. This behavior is in excellent agreement with a recently predicted structural crossover in such mixtures. In addition, the repercussions of structural crossover on the real-space structure of a binary fluid are analyzed. We suggest a relation between crossover and the lateral extension of networks containing only equally sized particles that are connected by nearest neighbor bonds. This is supported by Monte-Carlo simulations which are performed at different packing fractions and size ratios. Comments: 4 pages, 4 figures

Title: The Blazar Spectral Sequence and GLASTCategory: astro-phAuthors: L. Maraschi, G. Ghisellini, F. TavecchioStudy Abstract: The present status and understanding of the "spectral sequence" of blazars is discussed in the perspective of the upcoming GLAST launch. The vast improvement in sensitivity will allow to i) determine more objectively the "average" gamma-ray properties of classes objects ii) probe more deeply the ratio between accretion power and jet power in different systems. Comments: 3 pages, 4 figures. Proceedings of the First GLAST Symposium, to be published

Title: A High Robustness and Low Cost Model for Cascading FailuresCategory: physics.soc-phAuthors: Bing Wang, Beom Jun KimStudy Abstract: We study numerically the cascading failure problem by using artificially created scale-free networks and the real network structure of the power grid. The capacity for a vertex is assigned as a monotonically increasing function of the load (or the betweenness centrality). Through the use of a simple functional form with two free parameters, revealed is that it is indeed possible to make networks more robust while spending less cost. We suggest that our method to prevent cascade by protecting less vertices is particularly important for the design of more robust real-world networks to cascading failures. Comments: 5 pages, 5 figures, accepted by EPL

Title: Diffuse X-ray Emission from the Carina Nebula Observed with SuzakuCategory: astro-phAuthors: Kenji Hamaguchi, the Suzaku Eta Carinae team and the Carinae D-1 teamStudy Abstract: A number of giant HII regions are associated with soft diffuse X-ray emission. Among these, the Carina nebula possesses the brightest soft diffuse emission. The required plasma temperature and thermal energy can be produced by collisions or termination of fast winds from main-sequence or embedded young O stars, but the extended emission is often observed from regions apart from massive stellar clusters. The origin of the X-ray emission is unknown. The XIS CCD camera onboard Suzaku has the best spectral resolution for extended soft sources so far, and is therefore capable of measuring key emission lines in the soft band. Suzaku observed the core and the eastern side of the Carina nebula (Car-D1) in 2005 Aug and 2006 June, respectively. Spectra of the south part of the core and Car-D1 similarly showed strong L-shell lines of iron ions and K-shell lines of silicon ions, while in the north of the core these lines were much weaker. Fitting the spectra with an absorbed thin-thermal plasma model showed kT~0.2, 0.6 keV and NH~1-2e21 cm-2 with a factor of 2-3 abundance variation in oxygen, magnesium, silicon and iron. The plasma might originate from an old supernova, or a super shell of multiple supernovae. Comments: 4 pages, 2 figures, proceeding of the extreme universe in the Suzaku era, held in Kyoto, Japan on Dec. 4-8, 2006

Title: Resolvent estimates related with a class of dispersive equationsCategory: math.AP math.CAAuthors: Hiroyuki ChiharaStudy Abstract: We present a simple proof of the resolvent estimates of elliptic Fourier multipliers on the Euclidean space, and apply them to the analysis of time-global and spatially-local smoothing estimates of a class of dispersive equations. For this purpose we study in detail the properties of the restriction of Fourier transform on the unit cotangent sphere associated with the symbols of multipliers. Comments: minor change, 20 pages, no figure, final version

Title: What can emission lines tell us?Category: astro-phAuthors: G. StasinskaStudy Abstract: 1 Generalities 2 Empirical diagnostics based on emission lines 3 Photoionization modelling 4 Pending questions 5 Appendix: Lists of useful lines and how to deal with them Comments: 55 pages, Lectures given at the XVIII Canary Island Winterschool "The emission line Universe", to be published by Cambridge University Press

Title: The Colin de Verdi\`ere number and graphs of polytopesCategory: math.CO math.MGAuthors: Ivan IzmestievStudy Abstract: The Colin de Verdi\`ere number $\mu(G)$ of a graph $G$ is the maximum corank of a Colin de Verdi\`ere matrix for $G$ (that is, of a Schr\"odinger operator on $G$ with a single negative eigenvalue). In 2001, Lov\'asz gave a construction that associated to every convex 3-polytope a Colin de Verdi\`ere matrix of corank 3 for its 1-skeleton. We generalize the Lov\'asz construction to higher dimensions by interpreting it as minus the Hessian matrix of the volume of the polar dual. As a corollary, $\mu(G) \ge d$ if $G$ is the 1-skeleton of a convex $d$-polytope. Determination of the signature of the Hessian of the volume is based on the second Minkowski inequality for mixed volumes and on Bol's condition for equality. Comments: 18 pages, 2 figures; reorganized; an estimate of the spectral gap added; the appendix on mixed volumes rewritten

Title: Visible spectroscopic and photometric survey of Jupiter Trojans: final results on dynamical familiesCategory: astro-phAuthors: S. Fornasier, E. Dotto, O. Hainaut, F. Marzari, H. Boehnhardt, F. De Luise, M. A. BarucciStudy Abstract: We present the results of a visible spectroscopic and photometric survey of Jupiter Trojans belonging to different dynamical families carried out at the ESO-NTT telescope. We obtained data on 47 objects, 23 belonging to the L5 swarm and 24 to the L4 one. These data together with those already published by Fornasier et al. (2004a) and Dotto et al. (2006), constitute a total sample of visible spectra for 80 objects. The survey allows us to investigate six families (Aneas, Anchises, Misenus, Phereclos, Sarpedon, Panthoos) in the L5 cloud and four L4 families (Eurybates, Menelaus, 1986 WD and 1986 TS6). The sample that we measured is dominated by D--type asteroids, with the exception of the Eurybates family in the L4 swarm, where there is a dominance of C- and P-type asteroids. All the spectra that we obtained are featureless with the exception of some Eurybates members, where a drop--off of the reflectance is detected shortward of 5200 A. Similar features are seen in main belt C-type asteroids and commonly attributed to the intervalence charge transfer transition in oxidized iron. Our sample comprises fainter and smaller Trojans as compared to the literature's data and allows us to investigate the properties of objects with estimated diameter smaller than 40--50 km. The analysis of the spectral slopes and colors versus the estimated diameters shows that the blue and red objects have indistinguishable size distribution. We perform a statistical investigation of the Trojans's spectra property distributions as a function of their orbital and physical parameters, and in comparison with other classes of minor bodies in the outer Solar System. Trojans at lower inclination appear significantly bluer than those at higher inclination, but this effect is strongly driven by the Eurybates family. Comments: 52 pages, 14 figure, paper accepted for publication in Icarus

Title: FIRST-based survey of Compact Steep Spectrum sources, V. Milliarcsecond-scale morphology of CSS objectsCategory: astro-phAuthors: Magdalena Kunert-Bajraszewska (1), Andrzej Marecki (1),((1) Torun Centre for Astronomy, N. Copernicus University, Torun)Study Abstract: Multifrequency VLBA observations of the final group of ten objects in a sample of FIRST-based compact steep spectrum (CSS) sources are presented. The sample was selected to investigate whether objects of this kind could be relics of radio-loud AGNs switched off at very early stages of their evolution or possibly to indicate intermittent activity. Initial observations were made using MERLIN at 5 GHz. The sources have now been observed with the VLBA at 1.7, 5 and 8.4 GHz in a snapshot mode with phase-referencing. The resulting maps are presented along with unpublished 8.4-GHz VLA images of five sources. Some of the sources discussed here show a complex radio morphology and therefore a complicated past that, in some cases, might indicate intermittent activity. One of the sources studied - 1045+352 - is known as a powerful radio and infrared-luminous broad absorption line (BAL) quasar. It is a young CSS object whose asymmetric two-sided morphology on a scale of several hundred parsecs, extending in two different directions, may suggest intermittent activity. The young age and compact structure of 1045+352 is consistent with the evolution scenario of BAL quasars. It has also been confirmed that the submillimetre flux of 1045+352 can be seriously contaminated by synchrotron emission. Comments: 14 pages, 10 figures, matches the version appearing in Astronomy & Astrophysics

Title: Investigation of relaxation phenomena in high-temperature superconductors HoBa2Cu3O7-d at the action of pulsed magnetic fieldsCategory: cond-mat.soft cond-mat.supr-conAuthors: J.G. Chigvinadze, J.V. Acrivos, S.M. Ashimov, A.A. Iashvili, T. V. Machaidze, Th. WolfStudy Abstract: It is used the mechanical method of Abrikosov vortex stimulated dynamics investigation in superconductors. With its help it was studied relaxation phenomena in vortex matter of high-temperature superconductors. It established that pulsed magnetic fields change the course of relaxation processes taking place in vortex matter. The study of the influence of magnetic pulses differing by their durations and amplitudes on vortex system of isotropic high-temperature superconductors system HoBa2Cu3O7-d showed the presence of threshold phenomena. The small duration pulses does not change the course of relaxation processes taking place in vortex matter. When the duration of pulses exceeds some critical value (threshold), then their influence change the course of relaxation process which is revealed by stepwise change of relaxing mechanical moment . These investigations showed that the time for formatting of Abrikosov vortex lattice in HoBa2Cu3O7-d is of the order of 20 microsec. which on the order of value exceeds the time necessary for formation of a single vortex observed in type II superconductors. Comments: 6 pages, 0 figures

Title: Spin and pseudospin symmetries and the equivalent spectra of relativistic spin-1/2 and spin-0 particlesCategory: nucl-th quant-phAuthors: P. Alberto, A. S. de Castro, M. MalheiroStudy Abstract: We show that the conditions which originate the spin and pseudospin symmetries in the Dirac equation are the same that produce equivalent energy spectra of relativistic spin-1/2 and spin-0 particles in the presence of vector and scalar potentials. The conclusions do not depend on the particular shapes of the potentials and can be important in different fields of physics. When both scalar and vector potentials are spherical, these conditions for isospectrality imply that the spin-orbit and Darwin terms of either the upper component or the lower component of the Dirac spinor vanish, making it equivalent, as far as energy is concerned, to a spin-0 state. In this case, besides energy, a scalar particle will also have the same orbital angular momentum as the (conserved) orbital angular momentum of either the upper or lower component of the corresponding spin-1/2 particle. We point out a few possible applications of this result. Comments: 5 pages, uses revtex macros

Title: General asymptotic solutions of the Einstein equations and phase transitions in quantum gravityCategory: hep-th gr-qcAuthors: D. PodolskyStudy Abstract: We discuss generic properties of classical and quantum theories of gravity with a scalar field which are revealed at the vicinity of the cosmological singularity. When the potential of the scalar field is exponential and unbounded from below, the general solution of the Einstein equations has quasi-isotropic asymptotics near the singularity instead of the usual anisotropic Belinskii - Khalatnikov - Lifshitz (BKL) asymptotics. Depending on the strength of scalar field potential, there exist two phases of quantum gravity with scalar field: one with essentially anisotropic behavior of field correlation functions near the cosmological singularity, and another with quasi-isotropic behavior. The ``phase transition'' between the two phases is interpreted as the condensation of gravitons. Comments: 8 pages; reference added, acknoledgement added

Title: AMR simulations of the low T/|W| bar-mode instability of neutron starsCategory: astro-phAuthors: Pablo Cerd\'a-Dur\'an, Vicent Quilis, Jos\'e A. FontStudy Abstract: It has been recently argued through numerical work that rotating stars with a high degree of differential rotation are dynamically unstable against bar-mode deformation, even for values of the ratio of rotational kinetic energy to gravitational potential energy as low as O(0.01). This may have implications for gravitational wave astronomy in high-frequency sources such as core collapse supernovae. In this paper we present high-resolution simulations, performed with an adaptive mesh refinement hydrodynamics code, of such low T/|W| bar-mode instability. The complex morphological features involved in the nonlinear dynamics of the instability are revealed in our simulations, which show that the excitation of Kelvin-Helmholtz-like fluid modes outside the corotation radius of the star leads to the saturation of the bar-mode deformation. While the overall trends reported in an earlier investigation are confirmed by our work, we also find that numerical resolution plays an important role during the long-term, nonlinear behaviour of the instability, which has implications on the dynamics of rotating stars and on the attainable amplitudes of the associated gravitational wave signals. Comments: 20 pages, 9 figures, accepted for publication in Computer Physics Communications.

Title: Evolutionary games on minimally structured populationsCategory: q-bio.PE q-bio.OTAuthors: Gergely J Szollosi and Imre DerenyiStudy Abstract: Population structure induced by both spatial embedding and more general networks of interaction, such as model social networks, have been shown to have a fundamental effect on the dynamics and outcome of evolutionary games. These effects have, however, proved to be sensitive to the details of the underlying topology and dynamics. Here we introduce a minimal population structure that is described by two distinct hierarchical levels of interaction. We believe this model is able to identify effects of spatial structure that do not depend on the details of the topology. We derive the dynamics governing the evolution of a system starting from fundamental individual level stochastic processes through two successive meanfield approximations. In our model of population structure the topology of interactions is described by only two parameters: the effective population size at the local scale and the relative strength of local dynamics to global mixing. We demonstrate, for example, the existence of a continuous transition leading to the dominance of cooperation in populations with hierarchical levels of unstructured mixing as the benefit to cost ratio becomes smaller then the local population size. Applying our model of spatial structure to the repeated prisoner's dilemma we uncover a novel and counterintuitive mechanism by which the constant influx of defectors sustains cooperation. Further exploring the phase space of the repeated prisoner's dilemma and also of the "rock-paper-scissor" game we find indications of rich structure and are able to reproduce several effects observed in other models with explicit spatial embedding, such as the maintenance of biodiversity and the emergence of global oscillations. Comments: Supporting information available as EPAPS Document No. E-PLEEE8-78-144809 at http://ftp.aip.org/epaps/phys_rev_e/E-PLEEE8-78-144809/

Title: Flavor Physics in SUSY at large tan(beta)Category: hep-phAuthors: Paride ParadisiStudy Abstract: We discuss the phenomenological impact of a particularly interesting corner of the MSSM: the large tan(beta) regime. The capabilities of leptonic and hadronic Flavor Violating processes in shedding light on physics beyond the Standard Model are reviewed. Moreover, we show that tests of Lepton Universality in charged current processes can represent an interesting handle to obtain relevant information on New Physics scenarios. Comments: Proceedings of the Workshop CKM2006, 12-16 December, Nagoya (Japan). 4 pages, 2 figures.

Title: Some properties of the complex Monge-Ampere operator in Cegrell's classes and applicationsCategory: math.CVAuthors: Nguyen Van Khue and Pham Hoang HiepStudy Abstract: In this article we will first prove a result about convergence in capacity. Using the achieved result we will obtain a general decompositon theorem for complex Monge-Ampere measues which will be used to prove a comparison principle for the complex Monge-Ampere operator. Comments: 19 pages

Title: Torsional oscillations of longitudinally inhomogeneous coronal loopsCategory: astro-phAuthors: T.V. Zaqarashvili and K MurawskiStudy Abstract: We explore the effect of an inhomogeneous mass density field on frequencies and wave profiles of torsional Alfven oscillations in solar coronal loops. Dispersion relations for torsional oscillations are derived analytically in limits of weak and strong inhomogeneities. These analytical results are verified by numerical solutions, which are valid for a wide range of inhomogeneity strength. It is shown that the inhomogeneous mass density field leads to the reduction of a wave frequency of torsional oscillations, in comparison to that of estimated from mass density at the loop apex. This frequency reduction results from the decrease of an average Alfven speed as far as the inhomogeneous loop is denser at its footpoints. The derived dispersion relations and wave profiles are important for potential observations of torsional oscillations which result in periodic variations of spectral line widths. Torsional oscillations offer an additional powerful tool for a development of coronal seismology. Comments: 6 pages, 3 figures, accepted in A&A

Title: Pseudo-random Puncturing: A Technique to Lower the Error Floor of Turbo CodesCategory: cs.IT math.ITAuthors: Ioannis Chatzigeorgiou, Miguel R. D. Rodrigues, Ian J. Wassell and Rolando CarrascoStudy Abstract: It has been observed that particular rate-1/2 partially systematic parallel concatenated convolutional codes (PCCCs) can achieve a lower error floor than that of their rate-1/3 parent codes. Nevertheless, good puncturing patterns can only be identified by means of an exhaustive search, whilst convergence towards low bit error probabilities can be problematic when the systematic output of a rate-1/2 partially systematic PCCC is heavily punctured. In this paper, we present and study a family of rate-1/2 partially systematic PCCCs, which we call pseudo-randomly punctured codes. We evaluate their bit error rate performance and we show that they always yield a lower error floor than that of their rate-1/3 parent codes. Furthermore, we compare analytic results to simulations and we demonstrate that their performance converges towards the error floor region, owning to the moderate puncturing of their systematic output. Consequently, we propose pseudo-random puncturing as a means of improving the bandwidth efficiency of a PCCC and simultaneously lowering its error floor. Comments: 5 pages, 1 figure, Proceedings of the 2007 IEEE International Symposium on Information Theory, Nice, France, June 24-29, 2007

Title: The Arctic Circle RevisitedCategory: math-ph hep-th math.MPAuthors: F. Colomo and A.G. PronkoStudy Abstract: The problem of limit shapes in the six-vertex model with domain wall boundary conditions is addressed by considering a specially tailored bulk correlation function, the emptiness formation probability. A closed expression of this correlation function is given, both in terms of certain determinant and multiple integral, which allows for a systematic treatment of the limit shapes of the model for full range of values of vertex weights. Specifically, we show that for vertex weights corresponding to the free-fermion line on the phase diagram, the emptiness formation probability is related to a one-matrix model with a triple logarithmic singularity, or Triple Penner model. The saddle-point analysis of this model leads to the Arctic Circle Theorem, and its generalization to the Arctic Ellipses, known previously from domino tilings. Comments: 16 pages, 3 figures

Title: Time and motion in physics: the Reciprocity Principle, relativistic invariance of the lengths of rulers and time dilatationCategory: physics.gen-phAuthors: J.H.FieldStudy Abstract: Ponderable objects moving in free space according to Newton's First Law constitute both rulers and clocks when one such object is viewed from the rest frame of another. Together with the Reciprocity Principle this is used to demonstrate, in both Galilean and special relativity, the invariance of the measured length of a ruler in motion. The different times: `proper', `improper' and `apparent' appearing in different formulations of the relativistic time dilatation relation are discussed and exemplified by experimental applications. A non-intuitive `length expansion' effect predicted by the Reciprocity Principle as a necessary consequence of time dilatation is pointed out Comments: 14 pages, 3 figures. v2 Important conceptual errors explained in Added Note. See also arXiv:0807.0158, arXiv:0809.4121. References added

Title: B --> rho K* decays and other rare vector-vector modesCategory: hep-exAuthors: G. VasseurStudy Abstract: The recent analyses of the following rare vector-vector decays of the B meson are presented: rho K*, omega K*, omega rho, omega omega, and omega phi charmless final states. The latest results indicate that the fraction of longitudinal polarization is about 0.5 in penguin-dominated modes and close to 1 for tree-dominated modes. Comments: 4 pages, 8 figures, presented at the 4th International Workshop on the CKM Unitariry Triangle, Nagoya, Japan, December 12-16, 2006.

Title: Extending the theory of phonon-mediated superconductivity in quasi-2DCategory: cond-mat.supr-con cond-mat.str-elAuthors: J.P.HagueStudy Abstract: I present results from an extended Migdal-Eliashberg theory of electron-phonon interactions and superconductivity. The history of the electron-phonon problem is introduced, and then study of the intermediate parameter regime is justified from the energy scales in the cuprate superconductors. The Holstein model is detailed, and limiting cases are examined to demonstrate the need for an extended theory of superconductivity. Results of the extended approximation are shown, including spectral functions and phase diagrams. These are discussed with reference to Hohenberg's theorem, the Bardeen-Cooper-Schrieffer theory and Coulomb repulsion. Comments: Reprint to improve access. 10 pages, 7 figures.

Title: Generalized Nariai Solutions for Yang-type MonopolesCategory: gr-qc hep-thAuthors: Pablo Diaz, Antonio SeguiStudy Abstract: A detailed study of the geometries that emerge by a gravitating generalized Yang monopole in even dimensions is carried out. In particular, those which present black hole and cosmological horizons. This two-horizon system is thermally unstable. The process of thermalization will drive both horizons to coalesce. This limit is what is profusely studied in this paper. It is shown that eventhough coordinate distance shrinks to zero, physical distance does not. So, there is some remaining space which geometry has been computed and identified as a generalized Nariai solution. The thermal properties of this new spacetime are then calculated. Topics, as the elliptical relation between radii of spheres in the geometry or a discussion about whether a mass-type term should be present in the line element or not, are also included. Comments: 15 pages, 3 figures. References added, typos corrected and points clarified

Title: Instanton representation of Plebanski gravity. Consistency of the initital value constraints under time evolutionCategory: gr-qcAuthors: Eyo Eyo Ita IIIStudy Abstract: The instanton representation of Plebanski gravity provides as equations of motion a Hodge self-duality condition and a set of `generalized' Maxwell's equations, subject to gravitational degrees of freedom encoded in the initial value constraints of general relativity. The main result of the present paper will be to prove that this constraint surface is preserved under time evolution. We carry this out not using the usual Dirac procedure, but rather the Lagrangian equations of motion themsleves. Finally, we provide a comparison with the Ashtekar formulation to place these results into overall context. Comments: 16 pages

Title: Metal-insulator transition in the low-dimensional organic conductor (TMTSF)2FSO3 probed by infrared microspectroscopyCategory: cond-mat.str-elAuthors: A. Pashkin, K. Thirunavukkuarasu, Y.-L. Mathis, W. Kang, and C. A. KuntscherStudy Abstract: We present measurements of the infrared response of the quasi-one-dimensional organic conductor (TMTSF)2$SO3 along (E||a) and perpendicular (E||b') to the stacking axis as a function of temperature. Above the metal-insulator transition related to the anion ordering the optical conductivity spectra show a Drude-like response. Below the transition an energy gap of about 1500 cm-1 (185 meV) opens, leading to the corresponding charge transfer band in the optical conductivity spectra. The analysis of the infrared-active vibrations gives evidence for the long-range crystal structure modulation below the transition temperature and for the short-range order fluctuations of the lattice modulation above the transition temperature. Also we report about a new infrared mode at around 710 cm-1 with a peculiar temperature behavior, which has so far not been observed in any other (TMTSF)2X salt showing a metal-insulator transition. A qualitative model based on the coupling between the TMTSF molecule vibration and the reorientation of electrical dipole moment of the FSO3 anion is proposed, in order to explain the anomalous behavior of the new mode. Comments: to appear in Eur. Phys. J. B

Title: The effect of Topcolor Assisted Technicolor, and other models, on Neutrino OscillationCategory: hep-phAuthors: Minako Honda, Yee Kao, Naotoshi Okamura, Alexey Pronin, and Tatsu TakeuchiStudy Abstract: New physics beyond the Standard Model can lead to extra matter effects on neutrino oscillation if the new interactions distinguish among the three flavors of neutrino. In Ref.1, we argued that a long-baseline neutrino oscillation experiment in which the Fermilab-NUMI beam in its high-energy mode is aimed at the planned Hyper-Kamiokande detector would be capable of constraining the size of those extra matter effects, provided the vacuum value of \sin^2 2\theta_{23} is not too close to one. In this talk, we discuss how such a constraint would translate into limits on the coupling constants and masses of new particles in models such as topcolor assisted technicolor. Comments: 7 pages, latex, uses ws-procs9x6.cls; talk presented by Takeuchi at SCGT06, 21-24 November 2006, Nagoya, Japan

Title: Dark energy interacting with neutrinos and dark matter: a phenomenological theoryCategory: gr-qcAuthors: G. M. KremerStudy Abstract: A model for a flat homogeneous and isotropic Universe composed of dark energy, dark matter, neutrinos, radiation and baryons is analyzed. The fields of dark matter and neutrinos are supposed to interact with the dark energy. The dark energy is considered to obey either the van der Waals or the Chaplygin equations of state. The ratio between the pressure and the energy density of the neutrinos varies with the red-shift simulating massive and non-relativistic neutrinos at small red-shifts and non-massive relativistic neutrinos at high red-shifts. The model can reproduce the expected red-shift behaviors of the deceleration parameter and of the density parameters of each constituent. Comments: 7 pages, 5 figures. To appear in GRG

Title: Levy-Lieb constrained-search formulation as a minimization of the correlation functionalCategory: quant-phAuthors: L.Delle SiteStudy Abstract: The constrained-search formulation of Levy and Lieb, which formally defines the exact Hohenberg-Kohn functional for any N-representable electron density, is here shown to be equivalent to the minimization of the correlation functional with respect to the N-1 conditional probability density, where N is number of electrons of the system. The consequences and implications of such a result are here analyzed and discussed via a practical example. Comments: 9 pages, no figures

Title: Reality of linear and angular momentum expectation values in bound statesCategory: quant-ph hep-thAuthors: Utpal Roy, Suranjana Ghosh, T. Shreecharan, and Kaushik BhattacharyaStudy Abstract: In quantum mechanics textbooks the momentum operator is defined in the Cartesian coordinates and rarely the form of the momentum operator in spherical polar coordinates is discussed. Consequently one always generalizes the Cartesian prescription to other coordinates and falls in a trap. In this work we introduce the difficulties one faces when the question of the momentum operator in spherical polar coordinate comes. We have tried to point out most of the elementary quantum mechanical results, related to the momentum operator, which has coordinate dependence. We explicitly calculate the momentum expectation values in various bound states and show that the expectation value really turns out to be zero, a consequence of the fact that the momentum expectation value is real. We comment briefly on the status of the angular variables in quantum mechanics and the problems related in interpreting them as dynamical variables. At the end, we calculate the Heisenberg's equation of motion for the radial component of the momentum for the Hydrogen atom. Comments: 18 pages

Title: Gravity-induced electric polarization of matter and planetary magnetic fieldsCategory: physics.geo-phAuthors: Boris A. Zon, Igor Yu. KretininStudy Abstract: This paper has been withdrawn due to copyright reasons. Comments: This paper has been withdrawn

Title: Environmental noise reduction for holonomic quantum gatesCategory: quant-ph cond-mat.mes-hallAuthors: Daniele Parodi, Maura Sassetti, Paolo Solinas, Nino Zangh\`iStudy Abstract: We study the performance of holonomic quantum gates, driven by lasers, under the effect of a dissipative environment modeled as a thermal bath of oscillators. We show how to enhance the performance of the gates by suitable choice of the loop in the manifold of the controllable parameters of the laser. For a simplified, albeit realistic model, we find the surprising result that for a long time evolution the performance of the gate (properly estimated in terms of average fidelity) increases. On the basis of this result, we compare holonomic gates with the so-called stimulated Raman adiabatic passage (STIRAP) gates. Comments: 7 pages, 2 figures, to appear in Phys. Rev. A

Title: The lifetime of unstable particles in electromagnetic fieldsCategory: hep-ph hep-th nucl-thAuthors: Daniele Binosi (ECT*, Trento), Vladimir Pascalutsa (ECT*, Trento & Mainz U.)Study Abstract: We show that the electromagnetic moments of unstable particles (resonances) have an absorptive contribution which quantifies the change of the particle's lifetime in an external electromagnetic field. To give an example we compute here the imaginary part of the magnetic moment for the cases of the muon and the neutron at leading order in the electroweak coupling. We also consider an analogous effect for the strongly-decaying $\Delta$(1232) resonance. The result for the muon is Im$ \mu = e G_F^2 m^3/768 \pi^3$, with $e$ the charge and $m$ the mass of the muon, $G_F$ the Fermi constant, which in an external magnetic field of $B$ Tesla give rise to the relative change in the muon lifetime of $3\times 10^{-15} B$. For neutron the effect is of a similar magnitude. We speculate on the observable implications of this effect. Comments: 11 pages, 3 figs; published version

Title: An equilibrium problem for the limiting eigenvalue distribution of banded Toeplitz matricesCategory: math.CV math.CAAuthors: Maurice Duits and Arno B.J. KuijlaarsStudy Abstract: We study the limiting eigenvalue distribution of $n\times n$ banded Toeplitz matrices as $n\to \infty$. From classical results of Schmidt-Spitzer and Hirschman it is known that the eigenvalues accumulate on a special curve in the complex plane and the normalized eigenvalue counting measure converges weakly to a measure on this curve as $n\to\infty$. In this paper, we characterize the limiting measure in terms of an equilibrium problem. The limiting measure is one component of the unique vector of measures that minimes an energy functional defined on admissible vectors of measures. In addition, we show that each of the other components is the limiting measure of the normalized counting measure on certain generalized eigenvalues. Comments: 28 pages; 7 figures

Title: Capturing knots in polymersCategory: cond-mat.soft cond-mat.stat-mechAuthors: P. Virnau, M. Kardar, and Y. KantorStudy Abstract: This paper visualizes a knot reduction algorithm Comments: 2 pages, 4 figures

Title: Exponential growth rates in a typed branching diffusionCategory: math.PRAuthors: Y. Git, J. W. Harris, S. C. HarrisStudy Abstract: We study the high temperature phase of a family of typed branching diffusions initially studied in [Ast\'{e}risque 236 (1996) 133--154] and [Lecture Notes in Math. 1729 (2000) 239--256 Springer, Berlin]. The primary aim is to establish some almost-sure limit results for the long-term behavior of this particle system, namely the speed at which the population of particles colonizes both space and type dimensions, as well as the rate at which the population grows within this asymptotic shape. Our approach will include identification of an explicit two-phase mechanism by which particles can build up in sufficient numbers with spatial positions near $-\gamma t$ and type positions near $\kappa \sqrt{t}$ at large times $t$. The proofs involve the application of a variety of martingale techniques--most importantly a ``spine'' construction involving a change of measure with an additive martingale. In addition to the model's intrinsic interest, the methodologies presented contain ideas that will adapt to other branching settings. We also briefly discuss applications to traveling wave solutions of an associated reaction--diffusion equation. Comments: Published at http://dx.doi.org/10.1214/105051606000000853 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)

Title: The collision velocity of the bullet cluster in conventional and modified dynamicsCategory: astro-phAuthors: Garry W. Angus (St. Andrews), Stacy S. McGaugh (Maryland)Study Abstract: We consider the orbit of the bullet cluster 1E 0657-56 in both CDM and MOND using accurate mass models appropriate to each case in order to ascertain the maximum plausible collision velocity. Impact velocities consistent with the shock velocity (~ 4700km/s) occur naturally in MOND. CDM can generate collision velocities of at most ~ 3800km/s, and is only consistent with the data provided that the shock velocity has been substantially enhanced by hydrodynamical effects. Comments: 8 pages, 4 figures, 1 table, accepted for publication in MNRAS

Title: Clustering features of $^9$Be, $^{14}$N, $^7$Be, and $^8$B nuclei in relativistic fragmentationCategory: nucl-exAuthors: D. A. Artemenkov, T. V. Shchedrina, R. Stanoeva, and P. I. ZarubinStudy Abstract: Recent studies of clustering in light nuclei with an initial energy above 1 A GeV in nuclear treack emulsion are overviewed. The results of investigations of the relativistic $^9$Be nuclei fragmentation in emulsion, which entails the production of He fragments, are presented. It is shown that most precise angular measurements provided by this technique play a crucial role in the restoration of the excitation spectrum of the $\alpha$ particle sysytem. In peripheral interactions $^9$Be nuclei are dissociated practically totally through the 0$^+$ and 2$^+$ states of the $^8$Be nucleus. The results of investigations of the dissociation of a $^{14}$N nucleus of momentum 2.86 A GeV/c in emulsion are presented as example of more complicated system. The momentum and correlation characteristics of $\alpha$ particles for the $^{14}$N$\to3\alpha+X$ channel in the laboratory system and the rest systems of 3$\alpha$ particles were considered in detail. Topology of charged fragments produced in peripheral relativistic dissociation of radioactive $^8$B, $^7$Be nuclei in emulsion is studied. Comments: 14 pages, 6 figures, 4 tables, International Symposium on Exotic Nuclei (EXON-2006), 17-22 July, 2006, Khanty-Mansiysk, Russia

Title: Super-shell structures and pairing in ultracold trapped Fermi gasesCategory: cond-mat.otherAuthors: M. Ogren and H. HeiselbergStudy Abstract: We calculate level densities and pairing gaps for an ultracold dilute gas of fermionic atoms in harmonic traps under the influence of mean field and anharmonic quartic trap potentials. Super-shell structures, which were found in Hartree-Fock calculations, are calculated analytically within periodic orbit theory as well as from WKB calculations. For attractive interactions, the underlying level densities are crucial for pairing and super-shell structures in gaps are predicted. Comments: 4 pages, 2 figures.

Title: Quantum non-local effects with Bose-Einstein condensatesCategory: quant-ph cond-mat.otherAuthors: Franck Lalo\"e (LKB - Lhomond), William J. Mullin (UMASS)Study Abstract: We study theoretically the properties of two Bose-Einstein condensates in different spin states, represented by a double Fock state. Individual measurements of the spins of the particles are performed in transverse directions, giving access to the relative phase of the condensates. Initially, this phase is completely undefined, and the first measurements provide random results. But a fixed value of this phase rapidly emerges under the effect of the successive quantum measurements, giving rise to a quasi-classical situation where all spins have parallel transverse orientations. If the number of measurements reaches its maximum (the number of particles), quantum effects show up again, giving rise to violations of Bell type inequalities. The violation of BCHSH inequalities with an arbitrarily large number of spins may be comparable (or even equal) to that obtained with two spins. Comments: version published, with a shorter abstract to fit into the 9 lines of PRL, one more reference, and minor changes

Title: Low mass visual binaries in the solar neighbourhood: The case of HD141272Category: astro-phAuthors: T. Eisenbeiss, A. Seifahrt, M. Mugrauer, T.O.B. Schmidt, R. Neuhaeuser, T. RoellStudy Abstract: We search for stellar and substellar companions of young nearby stars to investigate stellar multiplicity and formation of stellar and substellar companions. We detect common proper-motion companions of stars via multi-epoch imaging. Their companionship is finally confirmed with photometry and spectroscopy. Here we report the discovery of a new co-moving (13 sigma) stellar companion ~17.8 arcsec (350 AU in projected separation) north of the nearby star HD141272 (21 pc). With EMMI/NTT optical spectroscopy we determined the spectral type of the companion to be M3+-0.5V. The derived spectral type as well as the near infrared photometry of the companion are both fully consistent with a 0.26+-0.07 Msol dwarf located at the distance of HD141272 (21 pc). Furthermore the photometry data rules out the pre-main sequence status, since the system is consistent with the ZAMS of the Pleiades. Comments: 6 pages, 6 figures

Title: Sterile neutrinos at the CNGSCategory: hep-phAuthors: A. Donini, M. Maltoni, D. Meloni, P. Migliozzi, F. TerranovaStudy Abstract: We study the potential of the CNGS beam in constraining the parameter space of a model with one sterile neutrino separated from three active ones by an $\mathcal{O}(\eVq)$ mass-squared difference, $\Dmq_\Sbl$. We perform our analysis using the OPERA detector as a reference (our analysis can be upgraded including a detailed simulation of the ICARUS detector). We point out that the channel with the largest potential to constrain the sterile neutrino parameter space at the CNGS beam is $\nu_\mu \to \nu_\tau$. The reason for that is twofold: first, the active-sterile mixing angle that governs this oscillation is the less constrained by present experiments; second, this is the signal for which both OPERA and ICARUS have been designed, and thus benefits from an extremely low background. In our analysis we also took into account $\nu_\mu \to \nu_e$ oscillations. We find that the CNGS potential to look for sterile neutrinos is limited with nominal intensity of the beam, but it is significantly enhanced with a factor 2 to 10 increase in the neutrino flux. Data from both channels allow us, in this case, to constrain further the four-neutrino model parameter space. Our results hold for any value of $\Dmq_\Sbl \gtrsim 0.1 \eVq$, \textit{i.e.} when oscillations driven by this mass-squared difference are averaged. We have also checked that the bound on $\theta_{13}$ that can be put at the CNGS is not affected by the possible existence of sterile neutrinos. Comments: Major modifications; new analysis after MiniBooNE data release: 21 pages, 5 figures

Title: Evolution of the Carter constant for inspirals into a black hole: effect of the black hole quadrupoleCategory: gr-qcAuthors: Eanna E. Flanagan and Tanja HindererStudy Abstract: We analyze the effect of gravitational radiation reaction on generic orbits around a body with an axisymmetric mass quadrupole moment Q to linear order in Q, to the leading post-Newtonian order, and to linear order in the mass ratio. This system admits three constants of the motion in absence of radiation reaction: energy, angular momentum, and a third constant analogous to the Carter constant. We compute instantaneous and time-averaged rates of change of these three constants. For a point particle orbiting a black hole, Ryan has computed the leading order evolution of the orbit's Carter constant, which is linear in the spin. Our result, when combined with an interaction quadratic in the spin (the coupling of the black hole's spin to its own radiation reaction field), gives the next to leading order evolution. The effect of the quadrupole, like that of the linear spin term, is to circularize eccentric orbits and to drive the orbital plane towards antialignment with the symmetry axis. In addition we consider a system of two point masses where one body has a single mass multipole or current multipole. To linear order in the mass ratio, to linear order in the multipole, and to the leading post-Newtonian order, we show that there does not exist an analog of the Carter constant for such a system (except for the cases of spin and mass quadrupole). With mild additional assumptions, this result falsifies the conjecture that all vacuum, axisymmetric spacetimes posess a third constant of geodesic motion. Comments: Typos found in sec. III, this version has the corrected expressions. An erratum is in press. 22 pages, added a paragraph to sec. V B; Erratum-ibid.D82:069904,2010; Erratum-ibid.D82:129903,2010

Title: Exactly solvable spin dynamics of an electron coupled to large number of nuclei and the electron-nuclear spin echo in a quantum dotCategory: cond-mat.mes-hallAuthors: G. G. KozlovStudy Abstract: The model considered in the paper is used nowadays to describe spin dynamics of quantum dots after optical excitation. Based on the exact diagonalization of a model Hamiltonian, we solve the problems of the electron spin polarization decay and magnetic field dependence of the steady state polarization. The important role of the nuclear state is shown and methods of its calculation for different regimes of optical excitation are proposed. The effect of spin echo observed after application of the magnetic field $\pi$-pulse is predicted. Comments: 5 figures. submitted to JETP

Title: Simulation of Robustness against Lesions of Cortical NetworksCategory: q-bio.NC cond-mat.dis-nn physics.soc-phAuthors: Marcus Kaiser, Robert Martin, Peter Andras and Malcolm P. YoungStudy Abstract: Structure entails function and thus a structural description of the brain will help to understand its function and may provide insights into many properties of brain systems, from their robustness and recovery from damage, to their dynamics and even their evolution. Advances in the analysis of complex networks provide useful new approaches to understanding structural and functional properties of brain networks. Structural properties of networks recently described allow their characterization as small-world, random (exponential) and scale-free. They complement the set of other properties that have been explored in the context of brain connectivity, such as topology, hodology, clustering, and hierarchical organization. Here we apply new network analysis methods to cortical inter-areal connectivity networks for the cat and macaque brains. We compare these corticocortical fibre networks to benchmark rewired, small-world, scale-free and random networks, using two analysis strategies, in which we measure the effects of the removal of nodes and connections on the structural properties of the cortical networks. The brain networks' structural decay is in most respects similar to that of scale-free networks. The results implicate highly connected hub-nodes and bottleneck connections as structural basis for some of the conditional robustness of brain systems. This informs the understanding of the development of brain networks' connectivity. Comments: submitted to European Journal of Neuroscience (under review)

Title: A thermodynamic model for the melting of supported metal nanoparticlesCategory: cond-mat.mtrl-sciAuthors: S. C. HendyStudy Abstract: We construct a simple thermodynamic model to describe the melting of a supported metal nanoparticle with a spherically curved free surface both with and without surface melting. We use the model to investigate the results of recent molecular dynamics simulations, which suggest the melting temperature of a supported metal particle is the same as that of a free spherical particle with the same surface curvature. Our model shows that this is only the case when the contact angles of the supported solid and liquid particles are similar. This is also the case for the temperature at which surface melting begins. Comments: 7 pages, 2 figures

Title: Average optimality for risk-sensitive control with general state spaceCategory: q-fin.RM math.PRAuthors: Anna Ja\'skiewiczStudy Abstract: This paper deals with discrete-time Markov control processes on a general state space. A long-run risk-sensitive average cost criterion is used as a performance measure. The one-step cost function is nonnegative and possibly unbounded. Using the vanishing discount factor approach, the optimality inequality and an optimal stationary strategy for the decision maker are established. Comments: Published at http://dx.doi.org/10.1214/105051606000000790 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)

Title: A Study of $B_{d}^0 \to J/\Psi \eta^{(\prime)}$ Decays in the pQCD ApproachCategory: hep-phAuthors: Xin Liu, Zhen-Jun Xiao, and Hui-Sheng WangStudy Abstract: Motivated by the very recent measurement of the branching ratio of ${B_d^0} \to J/\psi \eta$ decay, we calculate the branching ratios of ${B_d}^0 \to J/\psi \eta$ and ${B_d}^0 \to J/\Psi \eta'$ decays in the perturbative QCD (pQCD) approach. The pQCD predictions for the branching ratios of considered decays are: $BR(B_d^0 \to J/\Psi \eta) = (1.96 ^{+9.68}_{-0.65}) \times 10^{-6}$, which is consistent with the first experimental measurement within errors; while $BR(B_d^0 \to J/\Psi \eta') = (1.09 ^{+3.76}_{-0.25}) \times 10^{-6}$, very similar with $B_d^0 \to \jpsi \eta$ decay and can be tested by the forthcoming LHC experiments. The measurements of these decay channels may help us to understand the QCD dynamics in the corresponding energy scale, especially the reliability of pQCD approach to these kinds of B meson decays. Comments: 10 pages, 1 ps figure, Revtex

Title: Finite-temperature phase transitions in a two-dimensional boson Hubbard modelCategory: cond-mat.str-elAuthors: Min-Chul Cha and Ji-Woo LeeStudy Abstract: We study finite-temperature phase transitions in a two-dimensional boson Hubbard model with zero-point quantum fluctuations via Monte Carlo simulations of quantum rotor model, and construct the corresponding phase diagram. Compressibility shows a thermally activated gapped behavior in the insulating regime. Finite-size scaling of the superfluid stiffness clearly shows the nature of the Kosterlitz-Thouless transition. The transition temperature, $T_c$, confirms a scaling relation $T_c \propto \rho_0^x$ with $x=1.0$. Some evidences of anomalous quantum behavior at low temperatures are presented. Comments: 4 pages, 7 figures

Title: Conditional generation of path-entangled optical NOON statesCategory: quant-phAuthors: Anne E. B. Nielsen and Klaus MolmerStudy Abstract: We propose a measurement protocol to generate path-entangled NOON states conditionally from two pulsed type II optical parametric oscillators. We calculate the fidelity of the produced states and the success probability of the protocol. The trigger detectors are assumed to have finite dead time, and for short pulse trigger fields they are modeled as on/off detectors with finite efficiency. Continuous-wave operation of the parametric oscillators is also considered. Comments: 7 pages, 5 figures, v2: added references and minor changes

Title: Renewals for exponentially increasing lifetimes, with an application to digital search treesCategory: math.PRAuthors: Florian Dennert, Rudolf Gr\"ubelStudy Abstract: We show that the number of renewals up to time $t$ exhibits distributional fluctuations as $t\to\infty$ if the underlying lifetimes increase at an exponential rate in a distributional sense. This provides a probabilistic explanation for the asymptotics of insertion depth in random trees generated by a bit-comparison strategy from uniform input; we also obtain a representation for the resulting family of limit laws along subsequences. Our approach can also be used to obtain rates of convergence. Comments: Published at http://dx.doi.org/10.1214/105051606000000862 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)

Title: Hawking radiation of linear dilaton black holesCategory: gr-qc hep-thAuthors: G. Clement, J.C. Fabris and G.T. MarquesStudy Abstract: We compute exactly the semi-classical radiation spectrum for a class of non-asymptotically flat charged dilaton black holes, the so-called linear dilaton black holes. In the high frequency regime, the temperature for these black holes generically agrees with the surface gravity result. In the special case where the black hole is massless, we show that, although the surface gravity remains finite, there is no radiation, in agreement with the fact that massless objects cannot radiate. Comments: 9 pages

Title: The S-Matrix of AdS/CFT and Yangian SymmetryCategory: nlin.SI cond-mat.stat-mech hep-thAuthors: Niklas BeisertStudy Abstract: We review the algebraic construction of the S-matrix of AdS/CFT. We also present its symmetry algebra which turns out to be a Yangian of the centrally extended su(2|2) superalgebra. Comments: 12 pages, contributed to the Solvay workshop "Bethe Ansatz: 75 Years Later", v2: references added, v3: wording changed, v4: factor 1/2 for Delta C hat corrected in tab 2 (thanks to F. Spill)