# Top arXiv papers

• May 06 2015 quant-ph arXiv:1505.00907v1
We introduce the notion of \emphpotential capacities of quantum channels in an operational way and provide upper bounds for these quantities, which quantify the ultimate limit of usefulness of a channel for a given task in the best possible context. Unfortunately, except for a few isolated cases, potential capacities seem to be as hard to compute as their "plain" analogues. We thus study upper bounds on some potential capacities: For the classical capacity, we give an upper bound in terms of the entanglement of formation. To establish a bound for the quantum and private capacity, we first "lift" the channel to a Hadamard channel and then prove that the quantum and private capacity of Hadamard channel is strongly additive, implying that for these channels, potential and plain capacity are equal. Employing these upper bounds we show that if a channel is noisy, however close it is to the noiseless channel, then it cannot be activated into the noiseless channel by any other contextual channel; this conclusion holds for all the three capacities. Although it is of less importance, we also discuss the so-called environment-assisted quantum capacity, because we are able to characterize its "potential" version.
• Mutually unbiased bases (MUB) are interesting for various reasons. The canonical MUB constructed by Ivanović as well as Wootters and Fields have attracted the most attention. Nevertheless, little is known about anything that is unique to this MUB. We show that the canonical MUB in any prime power dimension is uniquely determined by an extremal orbit of the (restricted) Clifford group except in dimension 3, in which case the trophy is taken by a special symmetric informationally complete measurement (SIC), known as the Hesse SIC. Here the extremal orbit is the orbit with the smallest number of pure states. Quite surprisingly, this characterization does not rely on any concept that is even remotely related to bases or unbiasedness. As a corollary, the canonical MUB is the unique minimal 2-design covariant with respect to the Clifford group except in dimension 3. In addition, these MUB provide an infinite family of highly symmetric frames and positive-operator-valued measures (POVMs), which are of independent interest.
• We study a generalization of Kitaev's abelian toric code model defined on CW complexes. In this model qudits are attached to n dimensional cells and the interaction is given by generalized star and plaquette operators. These are defined in terms of coboundary and boundary maps in the locally finite cellular cochain complex and the cellular chain complex. We find that the set of energy-minimizing ground states and the types of charges carried by certain localized excitations depends only on the proper homotopy type of the CW complex. As an application we show that the homological product of a CSS code with the infinite toric code has excitations with abelian anyonic statistics.
• Starting from a simple mapping of a generator of local stochastic dynamics to a quantum Hamiltonian, we derive a condition, which allows us to use the quasi-adiabatic evolution and so relate gapped quantum phases with non-equilibrium's. This leads us to a study of invertible matrix product operators. Finally, we present an ansatz for constructing local stochastic dynamics for which the Perron-Frobenius vector has a Matrix Product Representation. Additionally, we get for free that the dynamics satisfy a generalized form of detailed balance.
• We characterise Gaussian quantum channels that are Gaussian incompatibility breaking, that is, transform every set of Gaussian measurements into a set obtainable from a joint Gaussian observable via Gaussian postprocessing. Such channels represent local noise which renders measurements useless for Gaussian EPR-steering, providing the appropriate generalisation of entanglement breaking channels for this scenario. Understanding the structure of Gaussian incompatibility breaking channels contributes to the resource theory of noisy continuous variable quantum information protocols.
• We provide scientific foundations for athletic performance prediction on an individual level, exposing the phenomenology of individual athletic performance in the form of a low-rank model dominated by an individual power law. We present, evaluate, and compare a selection of methods for prediction of individual running performance, including our own, \emphlocal matrix completion (LMC), which we show to perform best. We also show that many documented phenomena in quantitative sports science, such as the form of scoring tables, the success of existing prediction methods including Riegel's formula, the Purdy points scheme, the power law for world records performances and the broken power law for world record speeds may be explained on the basis of our findings in a unified way.
• For any dg algebra $A$, not necessarily commutative, and a subset $S$ in $H(A)$, the homology of $A$, we construct its derived localisation $L_S(A)$ together with a map $A\to L_S(A)$, well-defined in the homotopy category of dg algebras, which possesses a universal property, similar to that of the ordinary localisation, but formulated in homotopy invariant terms. Even if $A$ is an ordinary ring, $L_S(A)$ may have non-trivial homology. Unlike the commutative case, the localisation functor does not commute, in general, with homology but instead there is a spectral sequence relating $H(L_S(A))$ and $L_S(H(A))$; this spectral sequence collapses when, e.g. $S$ is an Ore set or when $A$ is a free ring. We prove that $L_S(A)$ could also be regarded as a Bousfield localisation of $A$ viewed as a left or right dg module over itself. Combined with the results of Dwyer-Kan on simplicial localisation, this leads to a simple and conceptual proof of the topological group completion theorem. Further applications include algebraic $K$-theory, cyclic and Hochschild homology, the stable homology of various mapping class groups and Kontsevich's graph homology.
• We prove that every del Pezzo surface of degree two over a finite field is unirational, building on the work of Manin and an extension by Salgado, Testa, and Várilly-Alvarado, who had proved this for all but three surfaces. Over general fields of characteristic not equal to two, we state sufficient conditions for a del Pezzo surface of degree two to be unirational.
• Protein-peptide interactions play essential functional roles in living organisms and their structural characterization is a hot subject of current experimental and theoretical research. Computational modeling of the structure of protein-peptide interactions is usually divided into two stages: prediction of the binding site at a protein receptor surface, and then docking (and modeling) the peptide structure into the known binding site. This paper presents a comprehensive CABS-dock method for the simultaneous search of binding sites and flexible protein-peptide docking, available as a users friendly web server. We present example CABS-dock results obtained in the default CABS-dock mode and using its advanced options that enable the user to increase the range of flexibility for chosen receptor fragments or to exclude user-selected binding modes from docking search. Furthermore, we demonstrate a strategy to improve CABS-dock performance by assessing the quality of models with classical molecular dynamics. Finally, we discuss the promising extensions and applications of the CABS-dock method and provide a tutorial appendix for the convenient analysis and visualization of CABS-dock results. The CABS-dock web server is freely available at http://biocomp.chem.uw.edu.pl/CABSdock/
• The reliability function of variable-rate Slepian-Wolf coding is linked to the reliability function of channel coding with constant composition codes, through which computable lower and upper bounds are derived. The bounds coincide at rates close to the Slepian-Wolf limit, yielding a complete characterization of the reliability function in that rate regime. It is shown that variable-rate Slepian-Wolf codes can significantly outperform fixed-rate Slepian-Wolf codes in terms of rate-error tradeoff. The reliability function of variable-rate Slepian-Wolf coding with rate below the Slepian-Wolf limit is determined. In sharp contrast with fixed-rate Slepian-Wolf codes for which the correct decoding probability decays to zero exponentially fast if the rate is below the Slepian-Wolf limit, the correct decoding probability of variable-rate Slepian-Wolf codes can be bounded away from zero.
• In this paper, we present a numerical method, based on iterative Bregman projections, to solve the optimal transport problem with Coulomb cost. This is re- lated to the strong interaction limit of Density Functional Theory. The first idea is to introduce an entropic regularization of the Kantorovich formulation of the Optimal Transport problem. The regularized problem then corresponds to the projection of a vector on the intersection of the constraints with respect to the Kullback-Leibler dis- tance. Iterative Bregman projections on each marginal constraint are explicit which enables us to approximate the optimal transport plan. We validate the numerical method against analytical test cases.
• The focus of this work is on an alternative implementation of the iterative ensemble smoother (iES). We show that iteration formulae similar to those used in \citechen2013-levenberg,emerick2012ensemble can be derived by adopting a regularized Levenberg-Marquardt (RLM) algorithm \citejin2010regularized to approximately solve a minimum-average-cost (MAC) problem. This not only leads to an alternative theoretical tool in understanding and analyzing the behaviour of the aforementioned iES, but also provides insights and guidelines for further developments of the smoothing algorithms. For illustration, we compare the performance of an implementation of the RLM-MAC algorithm to that of the approximate iES used in \citechen2013-levenberg in three numerical examples: an initial condition estimation problem in a strongly nonlinear system, a facies estimation problem in a 2D reservoir and the history matching problem in the Brugge field case. In these three specific cases, the RLM-MAC algorithm exhibits comparable or even better performance, especially in the strongly nonlinear system.
• In this paper, we investigate the thermodynamics of hyperscaling violating Lifshitz black branes in the presence of a nonlinear massless electromagnetic field. We, first, obtain analytic nonlinear charged black brane solutions with hyperscaling violating factor in dilaton gravity and give the condition on the parameters of the metric for having black brane solutions. Second, we introduce the appropriate finite action in grand-canonical and canonical ensembles for nonlinear electromagnetic field. Next, by generalizing the counterterm method for the asymptotic Lifshitz spacetimes with hyperscaling violating factor, we calculate the energy density of our solutions. Then, we present a relation between the energy density and the thermodynamic quantities, electric potential, charge density, temperature and entropy density. This relation is the generalization of Smarr formula for anti-de Sitter black branes and charged Lifshiz solutions. Finally, we perform a stability analysis in both the canonical and grand-canonical ensemble. We show that the nonlinearity of electromagnetic field can make the solutions unstable in grand-canonical ensemble.
• Two outer bounds on the admissible source region for broadcast channels with correlated sources are presented: the first one is strictly tighter than the existing outer bound by Gohari and Anantharam while the second one provides a complete characterization of the admissible source region in the case where the two sources are conditionally independent given the common part. These outer bounds are deduced from the general necessary conditions established for the lossy source broadcast problem via suitable comparisons between the virtual broadcast channel (induced by the source and the reconstructions) and the physical broadcast channel.
• We use a Bayesian software package to analyze CARMA-8 data towards 19 unconfirmed Planck SZ-cluster candidates from Rodriguez-Gonzalvez et al. (2015), that are associated with significant overdensities in WISE. We used two cluster parameterizations, one based on a (fixed shape) generalized-NFW pressure profile and another based on a beta-gas-density profile (with varying shape parameters) to obtain parameter estimates for the nine CARMA-8 SZ-detected clusters. We find our sample is comprised of massive, Y_500=0.0010 \pm 0.0015 arcmin^2, relatively compact, theta_500= 3.9 \pm 2.0 arcmin systems. Results from the beta model show that our cluster candidates exhibit a heterogeneous set of brightness-temperature profiles. Comparison of Planck and CARMA-8 measurements showed good agreement in Y_500 and an absence of obvious biases. We estimated the total cluster mass M_500 as a function of z for one of the systems; at the preferred photometric redshift of 0.5, the derived mass, M_500 ≈0.8 \pm 0.2 \times 10^15 Msun. Spectroscopic Keck/MOSFIRE data confirmed a galaxy member of one of our cluster candidates to be at z=0.565. Applying a Planck prior in Y_500 to the CARMA-8 results reduces uncertainties for both parameters by a factor >4, relative to the independent Planck or CARMA-8 measurements. We here demonstrate a powerful technique to find massive clusters at intermediate z ≳0.5 redshifts using a cross-correlation between Planck and WISE data, with high-resolution follow-up with CARMA-8. We also use the combined capabilities of Planck and CARMA-8 to obtain a dramatic reduction by a factor of several, in parameter uncertainties.
• Protocols for tasks such as authentication, electronic voting, and secure multiparty computation ensure desirable security properties if agents follow their prescribed programs. However, if some agents deviate from their prescribed programs and a security property is violated, it is important to hold agents accountable by determining which deviations actually caused the violation. Motivated by these applications, we initiate a formal study of program actions as actual causes. Specifically, we define in an interacting program model what it means for a set of program actions to be an actual cause of a violation. We present a sound technique for establishing program actions as actual causes. We demonstrate the value of this formalism in two ways. First, we prove that violations of a specific class of safety properties always have an actual cause. Thus, our definition applies to relevant security properties. Second, we provide a cause analysis of a representative protocol designed to address weaknesses in the current public key certification infrastructure.
• Building a visual summary from an egocentric photostream captured by a lifelogging wearable camera is of high interest for different applications (e.g. memory reinforcement). In this paper, we propose a new summarization method based on keyframes selection that uses visual features extracted by means of a convolutional neural network. Our method applies an unsupervised clustering for dividing the photostreams into events, and finally extracts the most relevant keyframe for each event. We assess the results by applying a blind-taste test on a group of 20 people who assessed the quality of the summaries.
• We present a simulation study of the prospects for the mass measurement of TeV-scale light-flavored right-handed squark at a 3 TeV e+e- collider based on CLIC technology. The analysis is based on full GEANT4 simulations of the CLIC_ILD detector concept, including Standard Model physics backgrounds and beam-induced hadronic backgrounds from two-photon processes. The analysis serves as a generic benchmark for the reconstruction of highly energetic jets in events with substantial missing energy. Several jet finding algorithms were evaluated, with the longitudinally invariant kt algorithm showing a high degree of robustness towards beam-induced background while preserving the features typically found in algorithms developed for e+e- collisions. The presented study of the reconstruction of light-flavored squarks shows that for TeV-scale squark masses, sub-percent accuracy on the mass measurement can be achieved at CLIC.
• We present a coinductive framework for defining infinitary analogues of equational reasoning and rewriting in a uniform way. We define the relation =^infty, notion of infinitary equational reasoning, and ->^infty, the standard notion of infinitary rewriting as follows: =^infty := nu R. ( <-_root + ->_root + lift(R) )^* ->^infty := mu R. nu S. ( ->_root + lift(R) )^* ; lift(S) where lift(R) := (f(s_1,...,s_n), f(t_1,...,t_n)) | s_1 R t_1,...,s_n R t_n + id , and where mu is the least fixed point operator and nu is the greatest fixed point operator. The setup captures rewrite sequences of arbitrary ordinal length, but it has neither the need for ordinals nor for metric convergence. This makes the framework especially suitable for formalizations in theorem provers.
• The Hubbard model with local on-site repulsion is generally thought to possess a superconducting ground-state for appropriate parameters, but the effects of more realistic long-range Coulomb interactions have not been studied extensively. We study the influence of these interactions on superconductivity by including nearest and next-nearest neighbor extended Hubbard interactions in addition to the usual on-site terms. Utilizing numerical exact diagonalization, we analyze the signatures of superconductivity in the ground states through the fidelity metric of quantum information theory. We find that nearest and next-nearest neighbor interactions have thresholds above which they destabilize superconductivity regardless of whether they are attractive or repulsive, seemingly due to competing charge fluctuations.
• Ice formation is ubiquitous in nature, with important consequences in a variety of systems and environments, including biological cells [1], soil [2], aircraft [3], transportation infrastructure [4] and atmospheric clouds [5,6]. However, its intrinsic kinetics and microscopic mechanism are difficult to discern with current experiments. Molecular simulations of ice nucleation are also challenging, and direct rate calculations have only been performed for coarse-grained models of water [7-9]. For the more realistic molecular models, only indirect estimates have been obtained, e.g.~by assuming the validity of classical nucleation theory [10]. Here, we use a path sampling approach to perform the first direct rate calculation of homogeneous nucleation of ice in a molecular model of water. We use TIP4P/Ice [11], the most accurate among the existing molecular models for studying ice polymorphs. By using a novel topological order parameter for distinguishing different polymorphs, we are able to identify a freezing mechanism that involves a competition between cubic and hexagonal ice polymorphs in the early stages of nucleation. In this competition, the cubic polymorph takes over since the addition of new topological structural motifs consistent with cubic ice leads to the formation of more compact crystallites. This is not true for topological hexagonal motifs that give rise to elongated crystallites that are not able to grow. This leads to transition states that are rich in cubic ice, and not the thermodynamically stable hexagonal polymorph.
• This paper gives a new way to diagnose the star-forming potential of a molecular cloud region from the probability density function of its column density (N-pdf). It gives expressions for the column density and mass profiles of a symmetric filament having the same N-pdf as a filamentary region. The central concentration of this characteristic filament can distinguish regions and can quantify their fertility for star formation. Profiles are calculated for N-pdfs which are pure lognormal, pure power law, or a combination. In relation to models of singular polytropic cylinders, characteristic filaments can be unbound, bound, or collapsing depending on their central concentration. Such filamentary models of the dynamical state of N-pdf gas are more relevant to star-forming regions than are models of spherical collapse. The star formation fertility of a bound or collapsing filament is quantified by its mean mass accretion rate when in radial free fall. For a given mass per length, the fertility increases with the filament mean column density and with its initial concentration. In selected regions the fertility of their characteristic filaments increases with the level of star formation.
• This paper is focused on the local interior $W^{1,\infty}$-regularity for weak solutions of degenerate elliptic equations of the form $\text{div}[\mathbf{a}(x,u, \nabla u)] +b(x, u, \nabla u) =0$, which include those of $p$-Laplacian type. We derive an explicit estimate of the local $L^\infty$-norm for the solution's gradient in terms of its local $L^p$-norm. Specifically, we prove \beginequation* \|∇u\|_L^∞(B_\fracR2(x_0))^p ≤\fracC|B_R(x_0)|\int_B_R(x_0)|∇u(x)|^p dx. \endequation* This estimate paves the way for our forthcoming work in establishing $W^{1,q}$-estimates (for $q>p$) for weak solutions to a much larger class of quasilinear elliptic equations.
• We address a question answering task on real-world im- ages that is set up as a Visual Turing Test. By combining latest advances in image representation and natural language processing, we propose Neural-Image-QA, an end-to-end formulation of this problem for which all parts are trained jointly. In contrast to previous efforts, we are facing a multi-modal problem where the language output (answer) is conditioned on visual and natural language input (ques- tion). Our result doubles the performance of the previous best result on this problem. We provide additional insights into the problem by analyzing how much information is con- tained only in the language part for which we provide a new human baseline. Further annotations were collected to study human consensus, which is related to the ambiguities inherent in this challenging task.
• We introduce SparkCL, an open source unified programming framework based on Java, OpenCL and the Apache Spark framework. The motivation behind this work is to bring unconventional compute cores such as FPGAs/GPUs/APUs/DSPs and future core types into mainstream programming use. The framework allows equal treatment of different computing devices under the Spark framework and introduces the ability to offload computations to acceleration devices. The new framework is seamlessly integrated into the standard Spark framework via a Java-OpenCL device programming layer which is based on Aparapi and a Spark programming layer that includes new kernel function types and modified Spark transformations and actions. The framework allows a single code base to target any type of compute core that supports OpenCL and easy integration of new core types into a Spark cluster.
• We study bound states embedded into the continuum of edge states in two-dimensional topological insulators. These states emerge in the presence of a short-range potential of a structural defect coupled to the boundary. In this case the edge states flow around the defect and have two resonances in the local density of states. The bound state in continuum (BIC) arises due to an interference of the resonances when they are close to the degeneracy. We find the condition under which the BIC appears, study the spacial distribution of the electron density, and show that the BIC has a helical structure with an electron current circulating around the defect.
• In order to project electromagnetic fields between different meshes with respect to the conservation of energetic values, Galerkin projection formulations based on the energetic norm are developed in this communication. The proposed formulations are applied to an academic example.
• We weave together a tale of two rings, SYM and QSYM, following one gold thread spun by Richard Stanley. The lesson we learn from this tale is that "Combinatorial objects like to be counted by quasisymmetric functions."
• May 06 2015 math.DS arXiv:1505.01113v1
For a non-exceptional oriented surface S let Q(S) be the moduli space of area one quadratic differentials. We show that there is a Borel subset E of Q(S) which is invariant under the Teichmueller flow F^t and of full measure for every invariant Borel probability measure, and there is a measurable conjugacy of the restriction of F^t to E into the Weil-Petersson flow. This conjugacy induces a continuous injection H of the space of invariant Borel probability measures for F^t into the space of invariant Borel probability measures for the Weil-Petersson flow. The map H is not surjective, but its image contains the Lebesgue Liouville measure.
• May 06 2015 math.RT arXiv:1505.01112v1
The satellite endofunctors are used to extend the definition of linkage of ideals to the linkage of finitely presented functors. The new notion for linkage works over a larger class of rings and is consistent with Auslander's approach to encoding information about modules into the category of finitely presented functors. In the process of extending linkage, we recover the Auslander-Gruson-Jensen duality using injective resolutions of finitely presented functors. Using the satellite endofunctors we give general definitions of derived functors which do not require the existence of projective or injective objects. These new definitions are motivated by certain exact sequences of functors appearing in multiple works of Auslander. The defect sequence of a finitely presented functor is used to understand the functor ( _ ) * on the functor category as well as establish Yoneda's colemma.
• This paper presents location based service for telecom providers. Most of the location-based services in the mobile networks are introduced and deployed by Internet companies. It leaves for telecom just the role of the data channel. Telecom providers should use their competitive advantages and offer own solutions. In this paper, we discuss the sharing location information via geo-messages. Geo messages let mobile users share location information as signatures to the standard messages (e.g., email, SMS). Rather than let some service constantly monitor (poll) the user location (as the most standalone services do) or share location info within any social circle (social network check-in, etc.) The Geo Messages approach lets users share location data on the peer to peer basis. Users can share own location info with any existing messaging systems. And messaging (e.g., SMS) is the traditional service for telecom
• May 06 2015 cs.IT math.IT arXiv:1505.01110v1
In this paper, we consider a zero error coordination problem wherein the nodes of a network exchange messages to be able to perfectly coordinate their actions with the individual observations of each other. While previous works on coordination commonly assume an asymptotically vanishing error, we assume exact, zero error coordination. Furthermore, unlike previous works that employ the empirical or strong notions of coordination, we define and use a notion of set coordination. This notion of coordination bears similarities with the empirical notion of coordination. We observe that set coordination, in its special case of two nodes with a one-way communication link is equivalent with the "Hide and Seek" source coding problem of McEliece and Posner. The Hide and Seek problem has known intimate connections with graph entropy, rate distortion theory, Renyi mutual information and even error exponents. Other special cases of the set coordination problem relate to Witsenhausen's zero error rate and the distributed computation problem. These connections motivate a better understanding of set coordination, its connections with empirical coordination, and its study in more general setups. This paper takes a first step in this direction by proving new results for two node networks.
• This tutorial review gives an overview of the transverse Anderson localization of light in one and two transverse dimensions. A pedagogical approach is followed throughout the presentation, where many aspects of localization are illustrated by means of a few simple models. The tutorial starts with some basic aspects of random matrix theory, and light propagation through and reflection from a random stack of dielectric slabs. Transverse Anderson localization of light in one- and two-dimensional coupled waveguide arrays is subsequently established and discussed. Recent experimental observations of localization and image transport in disordered optical fibers are discussed. More advanced topics, such as hyper-transport in longitudinally varying disordered waveguides, the impact of nonlinearity, and propagation of partially coherent and quantum light, are also examined.
• May 06 2015 cond-mat.soft arXiv:1505.01108v1
Many naturally occurring materials can change their shape in response to external stimuli or internal stresses. Inspired by such materials, as well as recent experiments, we consider a three- dimensional network of aqueous droplets joined by single lipid bilayers to form a cohesive, tissue- like material. The droplets in these self-assembled networks can be programmed to have distinct osmolarities. The resultant osmotic gradients generate internal stresses via local fluid flows, causing the network to deform in shape. We study, using molecular dynamics simulations, the formation of a variety of shapes ranging from rings to spirals to tetrahedra and determine the optimal range of parameters for each structure. We also realize a reversible folding-unfolding process by adding an osmotic interaction with the surrounding environment which necessarily evolves dynamically as the shape of the network changes. Such reversible processes may well be important for the development of osmotic robotics in synthetic and bio-inspired materials.
• In this paper we consider a resonance problem, in a generic regime, in the consideration of relaxation of ground states of semilinear Schrodinger equations. Different from previous results, our consideration includes the presence of resonance, resulted by overlaps of frequencies of different states. All the known key results, proved under non-resonance conditions, have been recovered uniformly. These are achieved by better understandings of normal form transformation and Fermi Golden rule. Especially, we find that if certain denominators are zeros (or small), resulted by the presence of resonances (or close to it), then cancellations between terms make the corresponding numerators proportionally small.
• We present a high-precision lattice calculation of the equation of state in the confining phase of SU(2) Yang-Mills theory. We show that the results are described very well by a gas of massive, non-interacting glueballs, provided one assumes an exponentially growing Hagedorn spectrum. The latter can be derived within an effective bosonic closed-string model, leading to a parameter-free theoretical prediction, which is in perfect agreement with our lattice results. Furthermore, when applied to SU(3) Yang-Mills theory, this effective model accurately describes the lattice results reported by Borsányi et al. in JHEP 07 (2012) 056.
• Although foot-and-mouth disease virus (FMDV) incidence has decreased in South America over the last years, the pathogen still circulates in the region and the risk of re-emergence in previously FMDV-free areas is a veterinary public health concern. In this paper we merge environmental, epidemiological and genetic data to reconstruct spatiotemporal patterns and determinants of FMDV serotypes A and O dispersal in South America. Our dating analysis suggests that serotype A emerged in South America around 1930, while serotype O emerged around 1990. The rate of evolution for serotype A was significantly higher compared to serotype O. Phylogeographic inference identified two well-connected sub networks of viral flow, one including Venezuela, Colombia and Ecuador; another including Brazil, Uruguay and Argentina. The spread of serotype A was best described by geographic distances, while trade of live cattle was the predictor that best explained serotype O spread. Our findings show that the two serotypes have different underlying evolutionary and spatial dynamics and may pose different threats to control programmes. Key-words: Phylogeography, foot-and-mouth disease virus, South America, animal trade.
• The properties of the observed Higgs boson with mass around 125 GeV are constrained by a wealth of experimental results targeting different combinations for the production and decay of a Higgs boson. In order to assess the compatibility of a non-Standard Model-like Higgs boson with all available results, we present Lilith, a new public tool that makes use of signal strength measurements performed at the LHC and the Tevatron.
• In this paper, we analyze the drag force acting on a cylinder in a wind tunnel. The inspiration comes from an experimental result: a small, light ball falls on air; its speed increases, reaches a maximum, decreases and finally stabilizes. This surprising breaking behavior is due to the gradual formation of the so-called von Kármán street of air vortices behind the ball: while it is not completely formed, the transient drag force is smaller than the known steady state value and the ball can reach speeds higher than its final value. To show it, we treat the similar problem of a cylinder inside a wind tunnel suddenly switched on, by solving the Navier-Stokes dynamic equation. We use a finite difference method with successive relaxations on a grid. We also treat the case of a rotating cylinder, leading to the Magnus force. The novelty is the method we use to calculate these forces, which avoids the traditional surface integration of velocity gradients; the latter demands a very precise determination of the velocity field near the cylinder or ball, a very hard numerical task.
• We will prove that, for a $2$ or $3$ component $L$-space link, $HFL^-$ is completely determined by the multi-variable Alexander polynomial of all the sub-links of $L$, as well as the pairwise linking numbers of all the components of $L$. We will also give some restrictions on the multi-variable Alexander polynomial of an $L$-space link. Finally, we use the methods in this paper to prove a conjecture by Yajing Liu classifying all $2$-bridge $L$-space links.
• Let $X_0$ be a complete borderless infinite area hyperbolic surface. We introduce Thurston's boundary to the Teichmüller space $T(X_0)$ of the surface $X_0$ using Liouville (geodesic) currents. Thurston's boundary to $T(X_0)$ is identified with the space $PML_{bdd}(X_0)$ of projective bounded measured laminations on $X_0$ which naturally extends Thurston's result for closed surfaces. Moreover, the quasiconformal mapping class group $MCG_{qc}(X_0)$ acts continuously on the closure $T(X_0)\cup PML_{bdd}(X_0)$.
• While computer programs and logical theories begin by declaring the concepts of interest, be it as data types or as predicates, network computation does not allow such global declarations, and requires *concept mining* and *concept analysis* to extract shared semantics for different network nodes. Powerful semantic analysis systems have been the drivers of nearly all paradigm shifts on the web. In categorical terms, most of them can be described as bicompletions of enriched matrices, generalizing the Dedekind-MacNeille-style completions from posets to suitably enriched categories. Yet it has been well known for more than 40 years that ordinary categories themselves in general do not permit such completions. Armed with this new semantical view of Dedekind-MacNeille completions, and of matrix bicompletions, we take another look at this ancient mystery. It turns out that simple categorical versions of the *limit superior* and *limit inferior* operations characterize a general notion of Dedekind-MacNeille completion, that seems to be appropriate for ordinary categories, and boils down to the more familiar enriched versions when the limits inferior and superior coincide. This explains away the apparent gap among the completions of ordinary categories, and broadens the path towards categorical concept mining and analysis, opened in previous work.
• May 06 2015 hep-ph arXiv:1505.01097v1
Several models of neutrino masses predict the existence of neutral heavy leptons. Here, we review current constraints on heavy neutrinos and apply a new formalism separating new physics from Standard Model. We discuss also the indirect effect of extra heavy neutrinos in oscillation experiments.
• In this article, we have theoretically investigated the performance of graphene-hexagonal Boron Nitride hyper crystals to demonstrate all angle negative refraction.Hexagonal Boron Nitride, the latest natural hyperbolic material; can be a very strong contender to form a hyper crystal with graphene due to its excellence as a graphene-compatible substrate. Although bare hexagonal Boron Nitride can exhibit negative refraction, the transmission is generally low due to its high reflective nature. On the other hand, due to two dimensional nature and metallic characteristics of graphene in the frequency range where hexagonal Boron Nitride behaves as a type-I hyperbolic Metamaterial, we have found that graphene-hexagonal Boron Nitride hyper-crystals exhibit all angle negative refraction with superior transmission. This has been possible because of the strong suppression of reflection from the hyper-crystal without any adverse effect on the negative refraction properties. This finding can prove very useful in applications such as superlensing, routing and imaging within a particular frequency range. We have also presented an effective medium description of the hyper crystal in the low k limit and validated the proposed theory using general transfer matrix method and also full wave simulation.
• We study the collective charge excitations (plasmons) in spin polarized graphene, and derive explicit expressions for their dispersion in the undamped regime. From this, we are able to calculate the critical wave vector beyond which the plasmon enters the electron-hole continuum, its quality factor decreasing sharply. We find that the value of the critical wave vector is strongly spin polarization-dependent, in a way that has no analogue in ordinary two-dimensional electron gases. The origin of this effect is in the coupling between the plasmon and the inter-band electron-hole pairs of the minority spin carriers. We show that the effect is robust with respect to the inclusion of disorder and we suggest that it can be exploited to experimentally determine the spin polarization of graphene.
• We present a version of the Banach-Mazur game, where open sets are replaced by elements of a fixed partially ordered set. We show how to apply it in the theory of Fraisse limits and beyond, obtaining simple proofs of universality of certain objects and classes.
• Stars in the immediate vicinity of supermassive black holes (SMBHs) can be ripped apart by the tidal forces of the black hole. The subsequent accretion of the stellar material causes a spectacular flare of electromagnetic radiation. Here, we provide a review of the observations of tidal disruption events (TDEs), with an emphasis on the important contributions of Swift to this field. TDEs represent a new probe of matter under strong gravity, and have opened up a new window into studying accretion physics under extreme conditions. The events probe relativistic effects, provide a new means of measuring black hole spin, and represent signposts of intermediate-mass BHs, binary BHs and recoiling BHs. Luminous, high-amplitude X-ray flares, matching key predictions of the tidal disruption scenario, have first been discovered with ROSAT, and more recently with other missions and in other wavebands. The Swift discovery of two gamma-ray emitting, jetted TDEs, never seen before, has provided us with a unique probe of the early phases of jet formation and evolution, and SwiftJ1644+75 has the best covered lightcurve of any TDE to date. Further, Swift has made important contributions in providing well-covered lightcurves of TDEs discovered with other instruments, setting constraints on the physics that govern the TDE evolution, and including the discovery of the first candidate binary SMBH identified from a TDE lightcurve.
• Misner spacetime is among the simplest solutions of Einstein's equation that exhibits a Cauchy horizon with a smooth extension beyond it. Besides violating strong cosmic censorship, this extension contains closed timelike curves. We analyze the stability of the Cauchy horizon, and prove that neighboring spacetimes in one parameter families of solutions through Misner's in pure gravity, gravity coupled to a scalar field, or Einstein-Maxwell theory, end at the Cauchy horizon developing a curvature singularity.
• In this paper we study the generation of primordial perturbations in a cosmological setting of bigravity during inflation. We consider a model of bigravity which can reproduce the Lambda-CDM background and large scale structure and a simple model of inflation with a single scalar field and a quadratic potential. Reheating is implemented with a toy-model in which the energy density of the inflaton is entirely dissipated into radiation. We present analytic and numerical results for the evolution of primordial perturbations in this cosmological setting. We find that even for low-scale inflation, the amplitude of tensor perturbations generated during inflation is not sufficiently suppressed to avoid the generation of the tensor instability discovered in Ref.[1] which develops during the cosmological evolution. We argue that, for viable reheating temperatures, this bigravity model is seriously affected by the power-law instability in the tensor sector on observable scales and therefore it is ruled out by present observations.
• In this paper we present numerical and analytical studies on the complete synchronization phenomena exhibited by unidirectionally coupled two variant of Murali-Lakshmanan-Chua circuits. The transition of the coupled system from an unsynchronized state to a state of complete synchronization under the influence of the coupling parameter is observed through phase portraits obtained numerically and analytically.

Ashley Apr 21 2015 18:42 UTC
Thanks for the further comments and spotting the new typos. To reply straight away to the other points: First, the resulting states might as well stay in the same bin (even though, as you rightly note, the bins no longer correspond to the same bit-strings as before). All that matters is that the ...(continued)
Perplexed Platypus Apr 21 2015 14:55 UTC
Thanks for updating the paper so promptly. The updated version addresses all my concerns so far. However I noticed a few extra (minor) things while reading through it. On page 15, last step of 2(b): if $|\psi_r\rangle$ and $|\psi_t\rangle$ were in the same bin but the combination operation failed ...(continued)
Ashley Apr 20 2015 16:27 UTC
Thank you for these very detailed and helpful comments. I have uploaded a new version of the paper to the arXiv to address them, which should appear tomorrow. I will reply to the comments in more detail (and justify the cases where I didn't modify the paper as suggested) when I receive them through ...(continued)
Mark M. Wilde Apr 17 2015 03:43 UTC
From the abstract: "Our result suggests that the coherent-state scheme known to achieve the ultimate information-theoretic capacity is not a practically optimal scheme for the case of using a finite number of channels." I find this language highly misleading and would have appreciated an arXiv po ...(continued)
Santiago Casas Apr 16 2015 14:05 UTC
Finally a good use for the Torsion tensor
Perplexed Platypus Apr 13 2015 22:37 UTC
**Summary and recommendation** This paper considers a $d$-dimensional version of the problem of finding a given pattern within a text, for random patterns and text. The text is assumed to be picked uniformly at random and has size $n^d$ while the pattern has size $m^d$ and is either uniformly ran ...(continued)
Ashley Apr 12 2015 13:01 UTC
Thanks for the clarification. In fact it seems that I do have this option switched on, with the correct author identifier, so I'm not sure why I didn't get an email about these comments.
Mankei Tsang Apr 10 2015 18:03 UTC
First of all let me say that I find the paper very interesting (which is why I read it in the first place), but at this stage it's not obvious to me that it will work; extraordinary claims require extraordinary evidence! Your measurement (Eqs. (12) and (13)) has a classical Fisher information that ...(continued)
Kavan Apr 10 2015 14:59 UTC
Mankei, thanks for your comment. Indeed, it is common knowledge that the optimal POVM given by Braunstein and Caves in general depends on the unknown parameter. An adaptive method can always be used to achieve the equality $F = F_q$. This issue has been addressed many times in both theoretical an ...(continued)
Mankei Tsang Apr 10 2015 13:44 UTC
I've seen this mistake so many times that I have to say it in public: The quantum Fisher information in terms of the symmetric logarithmic derivative ($F_q$) is NOT equal to the classical Fisher information optimized over all POVMs ($F$), contrary to the claim by Braunstein and Caves PRL 72, 3439 (1 ...(continued)