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arxiv_dataset-49001401.0769 | Complete asymptotic expansion of the spectral function of
multidimensional almost-periodic Schrodinger operators
math-ph math.AP math.MP
We prove the complete asymptotic expansion of the spectral function (the
integral kernel of the spectral projection) of a Schrodinger operator
$H=-\Delta+b$ acting in $R^d$ when the potential $b$ is real and either smooth
periodic, or generic quasi-periodic (finite linear combination of
exponentials), or belongs to a wide class of almost-periodic functions.
| arxiv topic:math-ph math.AP math.MP |
arxiv_dataset-49011401.0869 | Schatten-$p$ Quasi-Norm Regularized Matrix Optimization via Iterative
Reweighted Singular Value Minimization
math.OC cs.LG math.NA stat.CO stat.ML
In this paper we study general Schatten-$p$ quasi-norm (SPQN) regularized
matrix minimization problems. In particular, we first introduce a class of
first-order stationary points for them, and show that the first-order
stationary points introduced in [11] for an SPQN regularized $vector$
minimization problem are equivalent to those of an SPQN regularized $matrix$
minimization reformulation. We also show that any local minimizer of the SPQN
regularized matrix minimization problems must be a first-order stationary
point. Moreover, we derive lower bounds for nonzero singular values of the
first-order stationary points and hence also of the local minimizers of the
SPQN regularized matrix minimization problems. The iterative reweighted
singular value minimization (IRSVM) methods are then proposed to solve these
problems, whose subproblems are shown to have a closed-form solution. In
contrast to the analogous methods for the SPQN regularized $vector$
minimization problems, the convergence analysis of these methods is
significantly more challenging. We develop a novel approach to establishing the
convergence of these methods, which makes use of the expression of a specific
solution of their subproblems and avoids the intricate issue of finding the
explicit expression for the Clarke subdifferential of the objective of their
subproblems. In particular, we show that any accumulation point of the sequence
generated by the IRSVM methods is a first-order stationary point of the
problems. Our computational results demonstrate that the IRSVM methods
generally outperform some recently developed state-of-the-art methods in terms
of solution quality and/or speed.
| arxiv topic:math.OC cs.LG math.NA stat.CO stat.ML |
arxiv_dataset-49021401.0969 | Automated Reasoning over Deontic Action Logics with Finite Vocabularies
cs.LO
In this paper we investigate further the tableaux system for a deontic action
logic we presented in previous work. This tableaux system uses atoms (of a
given boolean algebra of action terms) as labels of formulae, this allows us to
embrace parallel execution of actions and action complement, two action
operators that may present difficulties in their treatment. One of the
restrictions of this logic is that it uses vocabularies with a finite number of
actions. In this article we prove that this restriction does not affect the
coherence of the deduction system; in other words, we prove that the system is
complete with respect to language extension. We also study the computational
complexity of this extended deductive framework and we prove that the
complexity of this system is in PSPACE, which is an improvement with respect to
related systems.
| arxiv topic:cs.LO |
arxiv_dataset-49031401.1069 | Stability of hybrid Levy systems
math.PR
Continuous-time stochastic systems have attracted a lot of attention
recently, due to their wide-spread use in finance for modelling price-dynamics.
More recently models taking into accounts shocks have been developed by
assuming that the return process is an infinitesimal Levy process. Levy
processes are also used to model the traffic in a telecommunication network. In
this paper we focus on a particular technical problem: stability of
time-varying stochastic systems driven or modulated by a Levy process with
discrete time interventions, such as parameter or state resetting. Such systems
will be called hybrid Levy systems. They are hybrid in the sense that jumps
both in the dynamics may occur. The peculiarity of our systems is that the
jump-times are defined by a more or less arbitrary point process, but there
exists an asymmetry in the system dynamics. The novelty of our model relative
to the theory of switching stochastic systems is two-fold. First, we allow slow
time variation of the parameters, in a stochastic sense, without any
statistical pattern, in the spirit of the classical stability result of Desoer.
Secondly, we allow certain jumps (resetting) in the system parameters almost
without any a priori condition.
| arxiv topic:math.PR |
arxiv_dataset-49041401.1169 | Correlation structure of time-changed Pearson diffusions
math.PR math.AP
The stochastic solution to diffusion equations with polynomial coefficients
is called a Pearson diffusion. If the time derivative is replaced by a
distributed fractional derivative, the stochastic solution is called a
fractional Pearson diffusion. This paper develops a formula for the covariance
function of a fractional Pearson diffusion in steady state, in terms of
generalized Mittag-Leffler functions. That formula shows that fractional
Pearson diffusions are long-range dependent, with a correlation that falls off
like a power law, whose exponent equals the smallest order of the distributed
fractional derivative.
| arxiv topic:math.PR math.AP |
arxiv_dataset-49051401.1269 | Bayesian Robust Inference of Sample Selection Using Selection-t Models
stat.CO stat.AP
Heckman selection model is the most popular econometric model in analysis of
data with sample selection. However, selection models with Normal errors cannot
accommodate heavy tails in the error distribution. Recently, Marchenko and
Genton proposed a selection-t model to perform frequentist' robust analysis of
sample selection. Instead of using their maximum likelihood estimates, our
paper develops new Bayesian procedures for the selection-t models with either
continuous or binary outcomes. By exploiting the Normal mixture representation
of the t distribution, we can use data augmentation to impute the missing data,
and use parameter expansion to sample the restricted covariance matrices. The
Bayesian procedures only involve simple steps, without calculating analytical
or numerical derivatives of the complicated log likelihood functions.
Simulation studies show the vulnerability of the selection models with Normal
errors, as well as the robustness of the selection models with t errors.
Interestingly, we find evidence of heavy-tailedness in three real examples
analyzed by previous studies, and the conclusions about the existence of
selection effect are very sensitive to the distributional assumptions of the
error terms.
| arxiv topic:stat.CO stat.AP |
arxiv_dataset-49061401.1369 | Controlling the level of sparsity in MPC
math.OC
In optimization routines used for on-line Model Predictive Control (MPC),
linear systems of equations are usually solved in each iteration. This is true
both for Active Set (AS) methods as well as for Interior Point (IP) methods,
and for linear MPC as well as for nonlinear MPC and hybrid MPC. The main
computational effort is spent while solving these linear systems of equations,
and hence, it is of greatest interest to solve them efficiently. Classically,
the optimization problem has been formulated in either of two different ways.
One of them leading to a sparse linear system of equations involving relatively
many variables to solve in each iteration and the other one leading to a dense
linear system of equations involving relatively few variables. In this work, it
is shown that it is possible not only to consider these two distinct choices of
formulations. Instead it is shown that it is possible to create an entire
family of formulations with different levels of sparsity and number of
variables, and that this extra degree of freedom can be exploited to get even
better performance with the software and hardware at hand. This result also
provides a better answer to an often discussed question in MPC; should the
sparse or dense formulation be used. In this work, it is shown that the answer
to this question is that often none of these classical choices is the best
choice, and that a better choice with a different level of sparsity actually
can be found.
| arxiv topic:math.OC |
arxiv_dataset-49071401.1469 | Cascading and Local-Field Effects in Non-Linear Optics Revisited; A
Quantum-Field Picture Based on Exchange of Photons
quant-ph
The semi-classical theory of radiation-matter coupling misses local-field
effects that may alter the pulse time-ordering and cascading that leads to the
generation of new signals. These are then introduced macroscopically by solving
Maxwell's equations. This procedure is convenient and intuitive but ad hoc. We
show that both effects emerge naturally by including coupling to quantum modes
of the radiation field in the vacuum state to second order. This approach is
systematic and suggests a more general class of corrections that only arise in
a QED framework. In the semi-classical theory, which only includes classical
field modes, the susceptibility of a collection of $N$ non-interacting
molecules is additive and scales as $N$. Second-order coupling to a vacuum mode
generates an effective retarded interaction that leads to cascading and local
field effects both of which scale as $N^2$.
| arxiv topic:quant-ph |
arxiv_dataset-49081401.1569 | Surface pole bracket polynomials of virtual knots and twisted knots
math.GT
Dye and Kauffman defined surface bracket polynomials for virtual links by use
of surface states, and found a relationship between the surface states and the
minimal genus of a surface in which a virtual link diagram is realized. They
and Miyazawa independently defined a multivariable polynomial invariant of
virtual links. This invariant is deeply related to the surface states. In this
paper, we introduce the notion of surface pole bracket polynomials for link
diagrams in closed surfaces, as a generalization of surface bracket polynomials
by Dye and Kauffman. The polynomials induce the invariant of twisted links
defined by the author before as a generalization of Dye, Kauffman and
Miyazawa's polynomial invariant. Furthermore we discuss a relationship between
curves in surface pole states and variables of the polynomial invariant.
| arxiv topic:math.GT |
arxiv_dataset-49091401.1669 | Smart machines and the SP theory of intelligence
cs.AI
These notes describe how the "SP theory of intelligence", and its embodiment
in the "SP machine", may help to realise cognitive computing, as described in
the book "Smart Machines". In the SP system, information compression and a
concept of "multiple alignment" are centre stage. The system is designed to
integrate such things as unsupervised learning, pattern recognition,
probabilistic reasoning, and more. It may help to overcome the problem of
variety in big data, it may serve in pattern recognition and in the
unsupervised learning of structure in data, and it may facilitate the
management and transmission of big data. There is potential, via information
compression, for substantial gains in computational efficiency, especially in
the use of energy. The SP system may help to realise data-centric computing,
perhaps via a development of Hebb's concept of a "cell assembly", or via the
use of light or DNA for the processing of information. It has potential in the
management of errors and uncertainty in data, in medical diagnosis, in
processing streams of data, and in promoting adaptability in robots.
| arxiv topic:cs.AI |
arxiv_dataset-49101401.1769 | Concordance Cosmology with Particle Creation
astro-ph.CO gr-qc hep-th
A constant-rate creation of dark particles in the late-time FLRW spacetime
provides a cosmological model in accordance with precise observational tests.
The matter creation backreaction implies in this context a vacuum energy
density scaling linearly with the Hubble parameter, which is consistent with
the vacuum expectation value of the QCD condensate in a low-energy expanding
spacetime. Both the cosmological constant and coincidence problems are
alleviated in this scenario. We discuss the cosmological model that arises in
this context and present a joint analysis of observations of the first acoustic
peak in the cosmic microwave background (CMB) anisotropy spectrum, the Hubble
diagram for supernovas of type Ia (SNIa), the distance scale of baryonic
acoustic oscillations (BAO) and the distribution of large scale structures
(LSS). We show that a good concordance is obtained, albeit with a higher value
of the present matter abundance than in the standard model.
| arxiv topic:astro-ph.CO gr-qc hep-th |
arxiv_dataset-49111401.1869 | Self-avoiding quantum walks
quant-ph
Quantum walks exhibit many unique characteristics compared to classical
random walks. In the classical setting, self-avoiding random walks have been
studied as a variation on the usual classical random walk. Classical
self-avoiding random walks have found numerous applications, most notably in
the modeling of protein folding. We consider the analogous problem in the
quantum setting. We complement a quantum walk with a memory register that
records where the walker has previously resided. The walker is then able to
avoid returning back to previously visited sites. We parameterise the strength
of the memory recording and the strength of the memory back-action on the
walker's motion, and investigate their effect on the dynamics of the walk. We
find that by manipulating these parameters the walk can be made to reproduce
ideal quantum or classical random walk statistics, or a plethora of more
elaborate diffusive phenomena. In some parameter regimes we observe a close
correspondence between classical self-avoiding random walks and the quantum
self-avoiding walk.
| arxiv topic:quant-ph |
arxiv_dataset-49121401.1969 | Rational and global forms of certain Chiral Conformal Field Theories;
Vertex Algebras I
math.QA math.AG
We present explicit global constructions - avoiding power series - of certain
chiral CFTs, including current algebras on the projective line. We outline an
approach to vertex algebras, inspired by this construction. We construct
natural pairings on state spaces.
| arxiv topic:math.QA math.AG |
arxiv_dataset-49131401.2069 | Constraints from $v_2$ fluctuations for the initial state geometry of
heavy-ion collisions
nucl-th hep-ph
The ability to accurately compute the series of coefficients $v_n$
characterizing the momentum space anisotropies of particle production in
ultrarelativistic heavy ion collisions as a function of centrality is widely
regarded as a triumph of fluid dynamics as description of the bulk matter
evolution. A key ingredient to fluid dynamical modeling is however the initial
spatial distribution of matter as created by a yet not completely understood
equilibration process. A measurement directly sensitive to this initial state
geometry is therefore of high value for constraining models of pre-equilibrium
dynamics. Recently, it has been shown that such a measurement is indeed
possible in terms of the event by event probability distribution of the
normalized $v_n$ distribution as a function of centrality, which is to high
accuracy independent on the details of the subsequent fluid dynamical evolution
and hence directly reflects the primary distribution of spatial eccentricities.
We present a study of this observable using a variety of Glauber-based models
and argue that the experimental data place very tight constraints on the
initial distribution of matter and rule out all simple Glauber-based models.
| arxiv topic:nucl-th hep-ph |
arxiv_dataset-49141401.2169 | Achievability of Nonlinear Degrees of Freedom in Correlatively Changing
Fading Channels
cs.IT math.IT
A new approach toward the noncoherent communications over the time varying
fading channels is presented. In this approach, the relationship between the
input signal space and the output signal space of a correlatively changing
fading channel is shown to be a nonlinear mapping between manifolds of
different dimensions. Studying this mapping, it is shown that using nonlinear
decoding algorithms for single input-multiple output (SIMO) and multiple input
multiple output (MIMO) systems, extra numbers of degrees of freedom (DOF) are
available. We call them the nonlinear degrees of freedom.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-49151401.2269 | Spectral Operators of Matrices
math.OC
The class of matrix optimization problems (MOPs) has been recognized in
recent years to be a powerful tool by researchers far beyond the optimization
community to model many important applications involving structured low rank
matrices. This trend can be credited to some extent to the exciting
developments in the emerging field of compressed sensing. The L\"owner
operator, which generates a matrix valued function by applying a
single-variable function to each of the singular values of a matrix, has played
an important role for a long time in solving matrix optimization problems.
However, the classical theory developed for L\"owner operators has become
inadequate in these recent applications. The main objective of this paper is to
provide some necessary theoretical foundations for designing numerical methods
for solving the MOP. This goal is achieved by introducing and conducting a
thorough study on a new class of matrix valued functions, coined as spectral
operators of matrices. Several fundamental properties of spectral operators,
including the well-definedness, continuity, directional differentiability,
Fr\'{e}chet-differentiability, locally Lipschitzian continuity, $\rho$-order
B(ouligand)-differentiability ($0<\rho\leq 1$), $\rho$-order G-semismooth
($0<\rho\leq 1$) and the characterization of Clarke's generalized Jacobian, are
systematically studied.
| arxiv topic:math.OC |
arxiv_dataset-49161401.2369 | Self Organizing strategies for enhanced ICIC (eICIC)
cs.NI
Small cells have been identified as an effective solution for coping with the
important traffic increase that is expected in the coming years. But this
solution is accompanied by additional interference that needs to be mitigated.
The enhanced Inter Cell Interference Coordination (eICIC) feature has been
introduced to address the interference problem. eICIC involves two parameters
which need to be optimized, namely the Cell Range Extension (CRE) of the small
cells and the ABS ratio (ABSr) which defines a mute ratio for the macro cell to
reduce the interference it produces. In this paper we propose self-optimizing
algorithms for the eICIC. The CRE is adjusted by means of load balancing
algorithm. The ABSr parameter is optimized by maximizing a proportional fair
utility of user throughputs. The convergence of the algorithms is proven using
stochastic approximation theorems. Numerical simulations illustrate the
important performance gain brought about by the different algorithms.
| arxiv topic:cs.NI |
arxiv_dataset-49171401.2469 | Frequency adjustment and synchrony in networks of delayed pulse coupled
oscillators
q-bio.NC nlin.AO
We introduce a system of pulse coupled oscillators that can change both their
phases and frequencies; and prove that when there is a separation of time
scales between phase and frequency adjustment the system converges to exact
synchrony on strongly connected graphs with time delays. The analysis involves
decomposing the network into a forest of tree-like structures that capture
causality. Furthermore, we provide a lower bound for the size of the basin of
attraction with immediate implications for empirical networks and random graph
models. These results provide a robust method of sensor net synchronization as
well as demonstrate a new avenue of possible pulse coupled oscillator research.
| arxiv topic:q-bio.NC nlin.AO |
arxiv_dataset-49181401.2569 | Multi Terminal Probabilistic Compressed Sensing
cs.IT math.IT stat.ML
In this paper, the `Approximate Message Passing' (AMP) algorithm, initially
developed for compressed sensing of signals under i.i.d. Gaussian measurement
matrices, has been extended to a multi-terminal setting (MAMP algorithm). It
has been shown that similar to its single terminal counterpart, the behavior of
MAMP algorithm is fully characterized by a `State Evolution' (SE) equation for
large block-lengths. This equation has been used to obtain the rate-distortion
curve of a multi-terminal memoryless source. It is observed that by spatially
coupling the measurement matrices, the rate-distortion curve of MAMP algorithm
undergoes a phase transition, where the measurement rate region corresponding
to a low distortion (approximately zero distortion) regime is fully
characterized by the joint and conditional Renyi information dimension (RID) of
the multi-terminal source. This measurement rate region is very similar to the
rate region of the Slepian-Wolf distributed source coding problem where the RID
plays a role similar to the discrete entropy.
Simulations have been done to investigate the empirical behavior of MAMP
algorithm. It is observed that simulation results match very well with
predictions of SE equation for reasonably large block-lengths.
| arxiv topic:cs.IT math.IT stat.ML |
arxiv_dataset-49191401.2669 | On-line vertex ranking of trees
math.CO
A $k$-ranking of a graph $G$ is a labeling of its vertices from
$\{1,\ldots,k\}$ such that any nontrivial path whose endpoints have the same
label contains a larger label. The least $k$ for which $G$ has a $k$-ranking is
the ranking number of $G$, also known as tree-depth. Applications of rankings
include VLSI design, parallel computing, and factory scheduling. The on-line
ranking problem asks for an algorithm to rank the vertices of $G$ as they are
presented one at a time along with all previously ranked vertices and the edges
between them (so each vertex is presented as the lone unranked vertex in a
partially labeled induced subgraph of $G$ whose final placement in $G$ is not
specified). The on-line ranking number of $G$ is the minimum over all such
algorithms of the largest label that algorithm can be forced to use. We give
bounds on the on-line ranking number of trees in terms of maximum degree,
diameter, and number of interior vertices.
| arxiv topic:math.CO |
arxiv_dataset-49201401.2769 | A class of nonperturbative nonlinear covariant gauges in Yang-Mills
theories
hep-th hep-lat hep-ph nucl-th
We report on the recent proposal of a class of nonlinear covariant gauges
that can be formulated as an extremization procedure which admits a simple
discretization well-suited to numerical minimization techniques. This class of
gauges is continuously connected to the Landau gauge and, in the ultraviolet,
where one can ignore Gribov ambiguities, it reduces to the
Curci-Ferrari-Delbourgo-Jarvis gauges.
| arxiv topic:hep-th hep-lat hep-ph nucl-th |
arxiv_dataset-49211401.2869 | A basis of the group of primitive almost pythagorean triples
math.NT
Let $m$ be a fixed square-free positive integer, then equivalence classes of
solutions of Diophantine equation $x^2+m\cdot y^2=z^2$ form an infinitely
generated abelian group under the operation induced by the complex
multiplication. A basis of this group is constructed here using prime ideals
and the ideal class group of the field $\mathbb Q (\sqrt{-m})$.
| arxiv topic:math.NT |
arxiv_dataset-49221401.2969 | Latest news on the Physics of Brown dwarfs
astro-ph.SR
The physics of brown dwarfs has continuously improved since the discovery of
these astrophysical bodies. The first important developments were devoted to
the description of their mechanical structure, with the derivation of an
appropriate equation of state, and the modelling of their atmosphere
characterised by strong molecular absorption. New challenges are arising with
progress in observational techniques which provide data of unprecedented
accuracy. The goal of this chapter is to describe some of the current
challenges for the theory of brown dwarfs. Those challenges concerns
atmospheric dust and cloud, non-equilibrium atmospheric chemistry, the effect
of rotation and magnetic fields on internal structure and the very early phases
of evolution characterised by accretion processes. The field remains lively as
more and more high quality observational data become available and because of
increasing discoveries of exoplanets. Indeed, many physical properties of giant
exoplanets can be described by the same theory as brown dwarfs, as described in
this chapter.
| arxiv topic:astro-ph.SR |
arxiv_dataset-49231401.3069 | Use Case Point Approach Based Software Effort Estimation using Various
Support Vector Regression Kernel Methods
cs.SE cs.LG
The job of software effort estimation is a critical one in the early stages
of the software development life cycle when the details of requirements are
usually not clearly identified. Various optimization techniques help in
improving the accuracy of effort estimation. The Support Vector Regression
(SVR) is one of several different soft-computing techniques that help in
getting optimal estimated values. The idea of SVR is based upon the computation
of a linear regression function in a high dimensional feature space where the
input data are mapped via a nonlinear function. Further, the SVR kernel methods
can be applied in transforming the input data and then based on these
transformations, an optimal boundary between the possible outputs can be
obtained. The main objective of the research work carried out in this paper is
to estimate the software effort using use case point approach. The use case
point approach relies on the use case diagram to estimate the size and effort
of software projects. Then, an attempt has been made to optimize the results
obtained from use case point analysis using various SVR kernel methods to
achieve better prediction accuracy.
| arxiv topic:cs.SE cs.LG |
arxiv_dataset-49241401.3169 | Exact and approximate operator parallelism
math.FA math.OA
Extending the notion of parallelism we introduce the concept of approximate
parallelism in normed spaces and then substantially restrict ourselves to the
setting of Hilbert space operators endowed with the operator norm. We present
several characterizations of the exact and approximate operator parallelism in
the algebra $\mathbb{B}(\mathscr{H})$ of bounded linear operators acting on a
Hilbert space $\mathscr{H}$. Among other things, we investigate the
relationship between approximate parallelism and norm of inner derivations on
$\mathbb{B}(\mathscr{H})$. We also characterize the parallel elements of a
$C^*$-algebra by using states. Finally we utilize the linking algebra to give
some equivalence assertions regarding parallel elements in a Hilbert
$C^*$-module.
| arxiv topic:math.FA math.OA |
arxiv_dataset-49251401.3269 | Teaching precursors to data science in introductory and second courses
in statistics
stat.CO cs.CY stat.OT
Statistics students need to develop the capacity to make sense of the
staggering amount of information collected in our increasingly data-centered
world. Data science is an important part of modern statistics, but our
introductory and second statistics courses often neglect this fact. This paper
discusses ways to provide a practical foundation for students to learn to
"compute with data" as defined by Nolan and Temple Lang (2010), as well as
develop "data habits of mind" (Finzer, 2013). We describe how introductory and
second courses can integrate two key precursors to data science: the use of
reproducible analysis tools and access to large databases. By introducing
students to commonplace tools for data management, visualization, and
reproducible analysis in data science and applying these to real-world
scenarios, we prepare them to think statistically in the era of big data.
| arxiv topic:stat.CO cs.CY stat.OT |
arxiv_dataset-49261401.3369 | Time dependence in large amplitude oscillatory shear: a rheo-ultrasonic
study of fatigue dynamics in a colloidal gel
cond-mat.soft
We report on the response of a yield stress material, namely a colloidal gel
made of attractive carbon black particles, submitted to large amplitude
oscillatory shear stress (LAOStress). At a constant stress amplitude well below
its apparent yield stress, the gel displays fatigue and progressively turns
from an elastic solid to a viscous fluid. The time-resolved analysis of the
strain response, of the Fourier spectrum, and of Lissajous plots allows one to
define two different timescales $\tau_w<\tau_f$ associated with the yielding
and fluidization of the gel. Coupling rheology to ultrasonic imaging further
leads to a local picture of the LAOStress response in which the gel first fails
at the walls at $\tau_w$ and then undergoes a slow heterogeneous fluidization
involving solid--fluid coexistence until the whole sample is fluid at $\tau_f$.
Spatial heterogeneities are observed in both the gradient and vorticity
directions and suggest a fragmentation of the initially solidlike gel into
macroscopic domains eroded by the surrounding fluidized suspension.
| arxiv topic:cond-mat.soft |
arxiv_dataset-49271401.3469 | Exploiting Single-Cycle Symmetries in Continuous Constraint Problems
cs.AI
Symmetries in discrete constraint satisfaction problems have been explored
and exploited in the last years, but symmetries in continuous constraint
problems have not received the same attention. Here we focus on permutations of
the variables consisting of one single cycle. We propose a procedure that takes
advantage of these symmetries by interacting with a continuous constraint
solver without interfering with it. A key concept in this procedure are the
classes of symmetric boxes formed by bisecting a n-dimensional cube at the same
point in all dimensions at the same time. We analyze these classes and quantify
them as a function of the cube dimensionality. Moreover, we propose a simple
algorithm to generate the representatives of all these classes for any number
of variables at very high rates. A problem example from the chemical
and#64257;eld and the cyclic n-roots problem are used to show the performance
of the approach in practice.
| arxiv topic:cs.AI |
arxiv_dataset-49281401.3569 | Efficient Strategies for Single/Multi-Target Jamming on MIMO Gaussian
Channels
cs.IT math.IT
The problem of jamming on multiple-input multiple-output (MIMO) Gaussian
channels is investigated in this paper. In the case of a single target
legitimate signal, we show that the existing result based on the simplification
of the system model by neglecting the jamming channel leads to losing important
insights regarding the effect of jamming power and jamming channel on the
jamming strategy. We find a closed-form optimal solution for the problem under
a positive semi-definite (PSD) condition without considering simplifications in
the model. If the condition is not satisfied and the optimal solution may not
exist in closed-form, we find the optimal solution using a numerical method and
also propose a suboptimal solution in closed-form as a close approximation of
the optimal solution. Then, the possibility of extending the results to solve
the problem of multi-target jamming is investigated for four scenarios, i.e.,
multiple access channel, broadcasting channel, multiple transceiver pairs with
orthogonal transmissions, and multiple transceiver pairs with interference,
respectively. It is shown that the proposed numerical method can be extended to
all scenarios while the proposed closed-form solutions for jamming may be
applied in the scenarios of the multiple access channel and multiple
transceiver pairs with orthogonal transmissions. Simulation results verify the
effectiveness of the proposed solutions.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-49291401.3669 | Hrebs and Cohesion Chains as similar tools for semantic text properties
research
cs.CL
In this study it is proven that the Hrebs used in Denotation analysis of
texts and Cohesion Chains (defined as a fusion between Lexical Chains and
Coreference Chains) represent similar linguistic tools. This result gives us
the possibility to extend to Cohesion Chains (CCs) some important indicators
as, for example the Kernel of CCs, the topicality of a CC, text concentration,
CC-diffuseness and mean diffuseness of the text. Let us mention that nowhere in
the Lexical Chains or Coreference Chains literature these kinds of indicators
are introduced and used since now. Similarly, some applications of CCs in the
study of a text (as for example segmentation or summarization of a text) could
be realized starting from hrebs. As an illustration of the similarity between
Hrebs and CCs a detailed analyze of the poem "Lacul" by Mihai Eminescu is
given.
| arxiv topic:cs.CL |
arxiv_dataset-49301401.3769 | The High-$z$ Universe Confronts Warm Dark Matter: Galaxy Counts,
Reionization and the Nature of Dark Matter
astro-ph.CO hep-ph
We use $N$-body simulations to show that high-redshift galaxy counts provide
an interesting constraint on the nature of dark matter, specifically Warm Dark
Matter (WDM), owing to the lack of early structure formation these models. Our
simulations include three WDM models with thermal-production masses of 0.8 keV,
1.3 keV, and 2.6 keV, as well as CDM. Assuming a relationship between dark halo
mass and galaxy luminosity that is set by the observed luminosity function at
bright magnitudes, we find that 0.8 keV WDM is disfavored by direct galaxy
counts in the Hubble Ultra Deep Field at $>\!\!10\sigma$. Similarly, 1.3 keV
WDM is statistically inconsistent at $2.2\sigma$. Future observations with JWST
(and possibly HST via the Frontier Fields) could rule out $1.3$ keV WDM at high
significance, and may be sensitive to WDM masses greater than 2.6 keV. We also
examine the ability of galaxies in these WDM models to reionize the universe,
and find that 0.8 keV and 1.3 keV WDM produce optical depths to the Cosmic
Microwave Background (CMB) that are inconsistent at 68% C.L. with current
Planck results, even with extremely high ionizing radiation escape fractions,
and 2.6 keV WDM requires an optimistic escape fraction to yield an optical
depth consistent with Planck data. Although CMB optical depth calculations are
model dependent, we find a strong challenge for stellar processes alone to
reionize the universe in a 0.8 keV and 1.3 keV WDM cosmology.
| arxiv topic:astro-ph.CO hep-ph |
arxiv_dataset-49311401.3869 | False-Name Manipulations in Weighted Voting Games
cs.GT cs.MA
Weighted voting is a classic model of cooperation among agents in
decision-making domains. In such games, each player has a weight, and a
coalition of players wins the game if its total weight meets or exceeds a given
quota. A players power in such games is usually not directly proportional to
his weight, and is measured by a power index, the most prominent among which
are the Shapley-Shubik index and the Banzhaf index.In this paper, we
investigate by how much a player can change his power, as measured by the
Shapley-Shubik index or the Banzhaf index, by means of a false-name
manipulation, i.e., splitting his weight among two or more identities. For both
indices, we provide upper and lower bounds on the effect of weight-splitting.
We then show that checking whether a beneficial split exists is NP-hard, and
discuss efficient algorithms for restricted cases of this problem, as well as
randomized algorithms for the general case. We also provide an experimental
evaluation of these algorithms. Finally, we examine related forms of
manipulative behavior, such as annexation, where a player subsumes other
players, or merging, where several players unite into one. We characterize the
computational complexity of such manipulations and provide limits on their
effects. For the Banzhaf index, we describe a new paradox, which we term the
Annexation Non-monotonicity Paradox.
| arxiv topic:cs.GT cs.MA |
arxiv_dataset-49321401.3969 | Precise Phase Measurements using an Entangled Coherent State
quant-ph
Quantum entanglement offers the possibility of making measurements beyond the
classical limit, however some issues still need to be overcome before it can be
applied in realistic lossy systems. Recent work has used the quantum Fisher
information (QFI) to show that entangled coherent states (ECSs) may be useful
for this purpose as they combine sub-classical phase precision capabilities
with robustness (Joo et al., 2011). However, to date no effective scheme for
measuring a phase in lossy systems using an ECS has been devised. Here we
present a scheme that does just this. We show how one could measure a phase to
a precision significantly better than that attainable by both unentangled
"classical" states and highly-entangled NOON states over a wide range of
different losses. This brings quantum metrology closer to being a realistic and
practical technology.
| arxiv topic:quant-ph |
arxiv_dataset-49331401.4069 | Binary Scientific Star Coauthors Core Size
physics.soc-ph cs.DL
It is examined whether the relationship $ J \propto A/r^{\alpha}$, and the
subsequent coauthor core notion (Ausloos 2013), between the number ($J$) of
joint publications (JP) by a "main scientist" (LI) with her/his coauthors (CAs)
can be extended to a team-like system. This is done by considering that each
coauthor can be so strongly tied to the LI that they are forming {\it binary
scientific star} (BSS) systems with respect to their other collaborators.
Moreover, publications in peer review journals and in "proceedings", both often
thought to be of "different quality", are separetely distinguished. The role of
a time interval for measuring $J$ and $\alpha$ is also examined. New indirect
measures are also introduced.
For making the point, two LI cases with numerous CAs are studied. It is found
that only a few BSS need to be usefully examined. The exponent $\alpha$ turns
out to be "second scientist" weakly dependent, but still "size" and
"publication type" dependent, according to the number of CAs or JP. The CA core
value is found to be (CA or JP) size and publication type dependent, but
remains in an understandable range. Somewhat unexpectedly, no special
qualitative difference on the binary scientific star CA core value is found
between publications in peer review journals and in proceedings.
In conclusion, some remark is made on partner cooperation in BSS teams. It is
suggested that such measures can serve as criteria for distinguishing the role
of scientists in a team.
| arxiv topic:physics.soc-ph cs.DL |
arxiv_dataset-49341401.4169 | Implementation of robust image artifact removal in SWarp through clipped
mean stacking
astro-ph.IM
We implement an algorithm for detecting and removing artifacts from
astronomical images by means of outlier rejection during stacking. Our method
is capable of addressing both small, highly significant artifacts such as
cosmic rays and, by applying a filtering technique to generate single frame
masks, larger area but lower surface brightness features such as secondary
(ghost) images of bright stars. In contrast to the common method of building a
median stack, the clipped or outlier-filtered mean stacked point-spread
function (PSF) is a linear combination of the single frame PSFs as long as the
latter are moderately homogeneous, a property of great importance for weak
lensing shape measurement or model fitting photometry. In addition, it has
superior noise properties, allowing a significant reduction in exposure time
compared to median stacking. We make publicly available a modified version of
SWarp that implements clipped mean stacking and software to generate single
frame masks from the list of outlier pixels.
| arxiv topic:astro-ph.IM |
arxiv_dataset-49351401.4269 | SUPER: Sparse signals with Unknown Phases Efficiently Recovered
cs.IT math.IT
Suppose ${\bf x}$ is any exactly $k$-sparse vector in $\mathbb{C}^{n}$. We
present a class of phase measurement matrix $A$ in $\mathbb{C}^{m\times n}$,
and a corresponding algorithm, called SUPER, that can resolve ${\bf x}$ up to a
global phase from intensity measurements $|A{\bf x}|$ with high probability
over $A$. Here $|A{\bf x}|$ is a vector of component-wise magnitudes of $A{\bf
x}$. The SUPER algorithm is the first to simultaneously have the following
properties: (a) it requires only ${\cal O}(k)$ (order-optimal) measurements,
(b) the computational complexity of decoding is ${\cal O}(k\log k)$ (near
order-optimal) arithmetic operations.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-49361401.4369 | Delayed acceptance particle MCMC for exact inference in stochastic
kinetic models
stat.CO
Recently-proposed particle MCMC methods provide a flexible way of performing
Bayesian inference for parameters governing stochastic kinetic models defined
as Markov (jump) processes (MJPs). Each iteration of the scheme requires an
estimate of the marginal likelihood calculated from the output of a sequential
Monte Carlo scheme (also known as a particle filter). Consequently, the method
can be extremely computationally intensive. We therefore aim to avoid most
instances of the expensive likelihood calculation through use of a fast
approximation. We consider two approximations: the chemical Langevin equation
diffusion approximation (CLE) and the linear noise approximation (LNA). Either
an estimate of the marginal likelihood under the CLE, or the tractable marginal
likelihood under the LNA can be used to calculate a first step acceptance
probability. Only if a proposal is accepted under the approximation do we then
run a sequential Monte Carlo scheme to compute an estimate of the marginal
likelihood under the true MJP and construct a second stage acceptance
probability that permits exact (simulation based) inference for the MJP. We
therefore avoid expensive calculations for proposals that are likely to be
rejected. We illustrate the method by considering inference for parameters
governing a Lotka-Volterra system, a model of gene expression and a simple
epidemic process.
| arxiv topic:stat.CO |
arxiv_dataset-49371401.4469 | A cosmic web filament revealed in Lyman-alpha emission around a luminous
high-redshift quasar
astro-ph.CO astro-ph.GA
Simulations of structure formation in the Universe predict that galaxies are
embedded in a "cosmic web", where the majority of baryons reside as rarefied
and highly ionized gas. This material has been studied for decades in
absorption against background sources, but the sparseness of these inherently
one-dimensional probes preclude direct constraints on the three-dimensional
morphology of the underlying web. Here we report observations of a cosmic web
filament in Lyman-alpha emission, discovered during a survey for cosmic gas
fluorescently "illuminated" by bright quasars at z=2.3. With a projected size
of approximately 460 physical kpc, the Lyman-alpha emission surrounding the
radio-quiet quasar UM287 extends well beyond the virial radius of any plausible
associated dark matter halo. The estimated cold gas mass of the nebula from the
observed emission is at least ten times larger than what is typically found by
cosmological simulations, suggesting that a population of intergalactic gas
clumps with sub-kpc sizes may be missing within current numerical models.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-49381401.4569 | Stabilisation de la formule des traces tordue I: endoscopie tordue sur
un corps local
math.RT math.NT
This is the first of a series of papers devoted to the stabilization of the
twisted trace formula. It is just an introduction. We present the local theory
of twisted endoscopy, following the fundamental works of Kottwitz-Shelstad,
Labesse and Shelstad. Our presentation is partly new because we try to give
canonical definitions of the basic objects, which are more usually defined
using auxiliary data. We prove also some results about the image of endoscopic
transfer and about the dual transfer of stable distributions whose support is a
finite set of stable conjugacy classes.
| arxiv topic:math.RT math.NT |
arxiv_dataset-49391401.4669 | Single Photoelectron Detection after Selective Excitation of
Electron-Heavy Hole and Electron-Light Hole Pairs in Double Quantum Dots
cond-mat.mes-hall quant-ph
We demonstrate the real-time detection of single photogenerated electrons in
two different lateral double quantum dots made in AlGaAs/GaAs/AlGaAs quantum
wells having a thin or a thick AlGaAs barrier layer. The observed incident
laser power and photon energy dependences of the photoelectron detection
efficiency both indicate that the trapped photoelectrons are, for the thin
barrier sample, predominantly photogenerated in the buffer layer followed by
tunneling into one of the two dots, whereas for the thick barrier sample they
are directly photogenerated in the well. For the latter, single photoelectron
detection after selective excitation of the heavy and light hole state in the
dot is well resolved. This ensures the applicability of our quantum well-based
quantum dot systems for the coherent transfer from single photon polarization
to single electron spin states.
| arxiv topic:cond-mat.mes-hall quant-ph |
arxiv_dataset-49401401.4769 | Variable Screenings in Binary Response Regressions with Multivariate
Normal Predictors
stat.AP
Screening before model building is a reasonable strategy to reduce the
dimension of regression problems. Sure independence screening is an efficient
approach to this purpose. It applies the slope estimate of a simple linear
regression as a surrogate measure of the association between the response and
the predictor so that the final model can be built by those predictors with
steep slopes. However, if the response is truly affected by a nontrivial linear
combination of some predictors then the simple linear regression model is a
misspecified model. In this work, we investigate the performance of the sure
independence screening in the view of model misspecification for binary
response regressions. Both maximum likelihood screening and least square
screening are studied with the assumption that predictors follow multivariate
normal distribution and the true and the working link function belong to a
class of scale mixtures of normal distributions.
| arxiv topic:stat.AP |
arxiv_dataset-49411401.4869 | Does Syntactic Knowledge help English-Hindi SMT?
cs.CL cs.AI
In this paper we explore various parameter settings of the state-of-art
Statistical Machine Translation system to improve the quality of the
translation for a `distant' language pair like English-Hindi. We proposed new
techniques for efficient reordering. A slight improvement over the baseline is
reported using these techniques. We also show that a simple pre-processing step
can improve the quality of the translation significantly.
| arxiv topic:cs.CL cs.AI |
arxiv_dataset-49421401.4969 | Local and Parallel Finite Element Algorithm Based On Multilevel
Discretization for Eigenvalue Problem
math.NA
A local and parallel algorithm based on the multilevel discretization is
proposed in this paper to solve the eigenvalue problem by the finite element
method. With this new scheme, solving the eigenvalue problem in the finest grid
is transferred to solutions of the eigenvalue problems on the coarsest mesh and
a series of solutions of boundary value problems by using the local and
parallel algorithm. The computational work in each processor can reach the
optimal order. Therefore, this type of multilevel local and parallel method
improves the overall efficiency of solving the eigenvalue problem. Some
numerical experiments are presented to validate the efficiency of the new
method.
| arxiv topic:math.NA |
arxiv_dataset-49431401.5069 | The Fermi GBM Gamma-Ray Burst Spectral Catalog: Four Years Of Data
astro-ph.HE
In this catalog we present the updated set of spectral analyses of GRBs
detected by the Fermi Gamma-Ray Burst Monitor (GBM) during its first four years
of operation. It contains two types of spectra, time-integrated spectral fits
and spectral fits at the brightest time bin, from 943 triggered GRBs. Four
different spectral models were fitted to the data, resulting in a compendium of
more than 7500 spectra. The analysis was performed similarly, but not
identically to Goldstein et al. 2012. All 487 GRBs from the first two years
have been re-fitted using the same methodology as that of the 456 GRBs in years
three and four. We describe, in detail, our procedure and criteria for the
analysis, and present the results in the form of parameter distributions both
for the observer-frame and rest-frame quantities. The data files containing the
complete results are available from the High-Energy Astrophysics Science
Archive Research Center (HEASARC).
| arxiv topic:astro-ph.HE |
arxiv_dataset-49441401.5169 | Calculations of gamma-ray spectral profiles of linear alkanes in the
positron annihilation process
physics.chem-ph
The positron-electron annihilation gamma-ray spectra of linear alkanes
CnH2n+2 (n=1-12) have been studied systematically. A profile quality (PQ)
parameter, is introduced to assess the agreement between the obtained
theoretical profiles and the experimental measurements in the entire region of
energy shift of the spectra. Together with the Doppler shift of the gamma-ray
spectra, the two parameters,PQ and Doppler shift, are able to provide a more
comprehensive assessment of the calculated gamma-ray spectra with respect to
available experiment. Applying the recently developed docking model, the
present study determines the positrophilic electrons for individual alkanes
from which the gamma-ray spectral profiles are calculated. The results achieve
an excellent agreement with experiment, not only with respect to the Doppler
shift, but also with respect to the gamma-ray profiles in the photon energy
region up to 5 keV. The study further calculates the gamma-ray spectra of other
linear alkanes in the series without available experimental measurements, such
as heptane (C7H16), octane (C8H18), decane (C10H22) and undecane (C11H24). The
results obtained show a dominance of the positrophilic electrons in the lowest
occupied valence orbital (LOVO) in the positron-electron annihilation process,
in agreement with previous studies.
| arxiv topic:physics.chem-ph |
arxiv_dataset-49451401.5269 | Stable Roommates Problem with Random Preferences
cs.DS cs.CC math.CO
The stable roommates problem with $n$ agents has worst case complexity
$O(n^2)$ in time and space. Random instances can be solved faster and with less
memory, however. We introduce an algorithm that has average time and space
complexity $O(n^\frac{3}{2})$ for random instances. We use this algorithm to
simulate large instances of the stable roommates problem and to measure the
probabilty $p_n$ that a random instance of size $n$ admits a stable matching.
Our data supports the conjecture that $p_n = \Theta(n^{-1/4})$.
| arxiv topic:cs.DS cs.CC math.CO |
arxiv_dataset-49461401.5369 | A limit equation criterion for applying the conformal method to
asymptotically cylindrical initial data sets
gr-qc math.AP
We prove that in a certain class of conformal data on an asymptotically
cylindrical manifold, if the conformally decomposed Einstein constraint
equations do not admit a solution, then one can always find a nontrivial
solution to the limit equation first explored by Dahl, Gicquaud, and Humbert in
[DGH11]. We also give an example of a Ricci curvature condition on the manifold
which precludes the existence of a solution to this limit equation, showing
that such a limit criterion can be a useful tool for studying the Einstein
constraint equations on manifolds with asymptotically cylindrical ends.
| arxiv topic:gr-qc math.AP |
arxiv_dataset-49471401.5469 | A spectral synthesis code for rapid modelling of supernovae
astro-ph.SR astro-ph.IM
We present TARDIS - an open-source code for rapid spectral modelling of
supernovae (SNe). Our goal is to develop a tool that is sufficiently fast to
allow exploration of the complex parameter spaces of models for SN ejecta. This
can be used to analyse the growing number of high-quality SN spectra being
obtained by transient surveys. The code uses Monte Carlo methods to obtain a
self-consistent description of the plasma state and to compute a synthetic
spectrum. It has a modular design to facilitate the implementation of a range
of physical approximations that can be compared to asses both accuracy and
computational expediency. This will allow users to choose a level of
sophistication appropriate for their application. Here, we describe the
operation of the code and make comparisons with alternative radiative transfer
codes of differing levels of complexity (SYN++, PYTHON, and ARTIS). We then
explore the consequence of adopting simple prescriptions for the calculation of
atomic excitation, focussing on four species of relevance to Type Ia supernova
spectra - Si II, S II, Mg II, and Ca II. We also investigate the influence of
three methods for treating line interactions on our synthetic spectra and the
need for accurate radiative rate estimates in our scheme.
| arxiv topic:astro-ph.SR astro-ph.IM |
arxiv_dataset-49481401.5569 | Generalized L\"uscher's Formula in Multichannel Baryon-Baryon Scattering
hep-lat
In this paper, L\"uscher's formula is generalized to the case of two
spin-$\frac{1}{2}$ particles in two-channel scattering based on Ref.
\cite{Li:2012bi}. This is first done in a non-relativistic quantum mechanics
model and then generalized to quantum field theory. We show that L\"uscher's
formula obtained from these two different methods are equivalent up to terms
that are exponentially suppressed in the box size. This formalism can be
readily applied to future lattice QCD calculations.
| arxiv topic:hep-lat |
arxiv_dataset-49491401.5669 | On Stability of Hyperbolic Thermoelastic Reissner-Mindlin-Timoshenko
Plates
math.AP
In the present article, we consider a thermoelastic plate of
Reissner-Mindlin-Timoshenko type with the hyperbolic heat conduction arising
from Cattaneo's law. In the absense of any additional mechanical dissipations,
the system is often not even strongly stable unless restricted to the
rotationally symmetric case, etc. We present a well-posedness result for the
linear problem under general mixed boundary conditions for the elastic and
thermal parts. For the case of a clamped, thermally isolated plate, we show an
exponential energy decay rate under a full damping for all elastic variables.
Restricting the problem to the rotationally symmetric case, we further prove
that a single frictional damping merely for the bending compoment is sufficient
for exponential stability. To this end, we construct a Lyapunov functional
incorporating the Bogovski\u{i} operator for irrotational vector fields which
we discuss in the appendix.
| arxiv topic:math.AP |
arxiv_dataset-49501401.5769 | A geometric version of the Andrasfai-Erdos-Sos theorem
math.CO
For each odd integer $k\ge 5$, we prove that, if $M$ is a simple rank-$r$
binary matroid with no odd circuit of length less than $k$ and with $|M| > k
2^{r-k+1}$, then $M$ is isomorphic to a restriction of the rank-$r$ binary
affine geometry; this bound is tight for all $r\ge k-1$. We use this to give a
simpler proof of the following result of Govaerts and Storme: for each integer
$n\ge 2$, if $M$ is a simple rank-$r$ binary matroid with no
$PG(n-1,2)$-restriction and with $|M| > \left(1-\frac{11}{2^{n+2}}\right) 2^r$,
then $M$ has critical number at most $n-1$. That result is a geometric analogue
of a theorem of Andrasfai, Erdos, and Sos in extremal graph theory.
| arxiv topic:math.CO |
arxiv_dataset-49511401.5869 | An Enhanced Branch-and-bound Algorithm for the Talent Scheduling Problem
cs.AI
The talent scheduling problem is a simplified version of the real-world film
shooting problem, which aims to determine a shooting sequence so as to minimize
the total cost of the actors involved. In this article, we first formulate the
problem as an integer linear programming model. Next, we devise a
branch-and-bound algorithm to solve the problem. The branch-and-bound algorithm
is enhanced by several accelerating techniques, including preprocessing,
dominance rules and caching search states. Extensive experiments over two sets
of benchmark instances suggest that our algorithm is superior to the current
best exact algorithm. Finally, the impacts of different parameter settings are
disclosed by some additional experiments.
| arxiv topic:cs.AI |
arxiv_dataset-49521401.5969 | Entropy of subordinate shift spaces
math.DS math.CO
We introduce a new family of shift spaces --- the subordinate shifts. Using
subordinate shifts we prove in an elementary way that for every nonnegative
real number $t$ there is a shift space with entropy $t$.
| arxiv topic:math.DS math.CO |
arxiv_dataset-49531401.6069 | On Continuous-Time White Phase Noise Channels
cs.IT math.IT
A continuous-time model for the additive white Gaussian noise (AWGN) channel
in the presence of white (memoryless) phase noise is proposed and discussed. It
is shown that for linear modulation the output of the baud-sampled filter
matched to the shaping waveform represents a sufficient statistic. The analysis
shows that the phase noise channel has the same information rate as an AWGN
channel but with a penalty on the average signal-to-noise ratio, the amount of
penalty depending on the phase noise statistic.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-49541401.6169 | Parsimonious Topic Models with Salient Word Discovery
cs.LG cs.CL cs.IR stat.ML
We propose a parsimonious topic model for text corpora. In related models
such as Latent Dirichlet Allocation (LDA), all words are modeled
topic-specifically, even though many words occur with similar frequencies
across different topics. Our modeling determines salient words for each topic,
which have topic-specific probabilities, with the rest explained by a universal
shared model. Further, in LDA all topics are in principle present in every
document. By contrast our model gives sparse topic representation, determining
the (small) subset of relevant topics for each document. We derive a Bayesian
Information Criterion (BIC), balancing model complexity and goodness of fit.
Here, interestingly, we identify an effective sample size and corresponding
penalty specific to each parameter type in our model. We minimize BIC to
jointly determine our entire model -- the topic-specific words,
document-specific topics, all model parameter values, {\it and} the total
number of topics -- in a wholly unsupervised fashion. Results on three text
corpora and an image dataset show that our model achieves higher test set
likelihood and better agreement with ground-truth class labels, compared to LDA
and to a model designed to incorporate sparsity.
| arxiv topic:cs.LG cs.CL cs.IR stat.ML |
arxiv_dataset-49551401.6269 | Hadronic production of $\Xi_{cc}$ at a fixed-target experiment at the
LHC
hep-ph
In the paper, we present a detailed discussion on the $\Xi_{cc}$ production
at a fixed target experiment at the LHC (After@LHC). The doubly charmed baryon
$\Xi_{cc}$ is produced via the channel, ${\rm Proton} + {\rm
Proton}\to\Xi_{cc}+X$. In estimating its hadroproduction, we discuss three
dominant subprocesses, e.g. $g+g\to \Xi_{cc} +\bar{c} +\bar{c}$, $g+c\to
\Xi_{cc}+\bar{c}$ and $c+c\to \Xi_{cc}+g$. During the production, it shall
first generate a binding diquark and then form the $\Xi_{cc}$ baryon by
grabbing soft light-quarks or gluons. We observe that both the two diquark
configurations $(cc)[^3S_1]_{\bf\bar 3}$ and $(cc)[^1S_0]_{\bf 6}$ can have
sizable contributions to the $\Xi_{cc}$ production. Large number of $\Xi_{cc}$
events can be generated at the After@LHC, whose total production cross section
is larger than that of the SELEX experiment by about thirty-five times. It may
also possible to study the properties of $\Xi_{bc}$ at the After@LHC. More
specifically, we shall have about $8.3 \times 10^6$ $\Xi_{cc}$ events/year and
$1.8 \times 10^4$ $\Xi_{bc}$ events/year when its integrated luminosity
approaches to $2$ fb$^{-1}$/year. Thus, in addition to SELEX and LHC, the
After@LHC shall provide another useful platform for studying the baryon
properties.
| arxiv topic:hep-ph |
arxiv_dataset-49561401.6369 | A regularity result for quasilinear stochastic partial differential
equations of parabolic type
math.NA
We consider a quasilinear parabolic stochastic partial differential equation
driven by a multiplicative noise and study regularity properties of its weak
solution satisfying classical a priori estimates. In particular, we determine
conditions on coefficients and initial data under which the weak solution is
H\"older continuous in time and possesses spatial regularity that is only
limited by the regularity of the given data. Our proof is based on an efficient
method of increasing regularity: the solution is rewritten as the sum of two
processes, one solves a linear parabolic SPDE with the same noise term as the
original model problem whereas the other solves a linear parabolic PDE with
random coefficients. This way, the required regularity can be achieved by
repeatedly making use of known techniques for stochastic convolutions and
deterministic PDEs.
| arxiv topic:math.NA |
arxiv_dataset-49571401.6469 | Phase-sensitive detection of spin pumping via the ac inverse spin Hall
effect
cond-mat.mes-hall cond-mat.mtrl-sci
An intriguing feature of spintronics is the use of pure spin-currents to
manipulate magnetization, e.g., spin-currents can switch magnetization in
spin-torque MRAM, a next-generation DRAM alternative. Giant spin-currents via
the spin Hall effect greatly expand the technological opportunities.
Conversely, a ferromagnet/normal metal junction emits spin-currents under
microwave excitation, i.e. spin-pumping. While such spin-currents are modulated
at the excitation frequency, there is also a non-linear, rectified component
that is commonly detected using the corresponding inverse spin Hall effect
(iSHE) dc voltage. However, the ac component should be more conducive for
quantitative analysis, as it is up to two orders of magnitude larger and
linear. But any device that uses the ac iSHE is also sensitive to inductive
signals via Faraday's Law and discrimination of the ac iSHE signal must rely on
phase-sensitive measurements. We use the inductive signal as a reference for a
quantitative measurement of the magnitude and phase of the ac iSHE.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-49581401.6569 | Blow-up for the two-component Camassa-Holm system
math.AP
Following conservative solutions of the two-component Camassa-Holm system
$u_t-u_{txx}+3uu_x-2u_xu_{xx}-uu_{xxx}+\rho\rho_x=0$, $\rho_t+(u\rho)_x=0$
along characteristics, we determine if wave breaking occurs in the nearby
future or not, for initial data $u_0\in H^1(\mathbb R)$ and $\rho_0\in
L^2(\mathbb R)$.
| arxiv topic:math.AP |
arxiv_dataset-49591401.6669 | Nonlinear Acoustics FDTD method including Frequency Power Law
Attenuation for Soft Tissue Modeling
physics.med-ph
This paper describes a model for nonlinear acoustic wave propagation through
absorbing and weakly dispersive media, and its numerical solution by means of
finite differences in time domain method (FDTD). The attenuation is based on
multiple relaxation processes, and provides frequency dependent absorption and
dispersion without using computational expensive convolutional operators. In
this way, by using an optimization algorithm the coefficients for the
relaxation processes can be obtained in order to fit a frequency power law that
agrees the experimentally measured attenuation data for heterogeneous media
over the typical frequency range for ultrasound medical applications. Our
results show that two relaxation processes are enough to fit attenuation data
for most soft tissues in this frequency range including the fundamental and the
first ten harmonics. Furthermore, this model can fit experimental attenuation
data that do not follow exactly a frequency power law over the frequency range
of interest. The main advantage of the proposed method is that only one
auxiliary field per relaxation process is needed, which implies less
computational resources compared with time-domain fractional derivatives
solvers based on convolutional operators.
| arxiv topic:physics.med-ph |
arxiv_dataset-49601401.6769 | Acoustic Bessel-like beam formation by an axisymmetric grating
cond-mat.mtrl-sci
We report Bessel-like beam formation of acoustic waves by means of an
axisymmetric grating of rigid tori. The results show that the generated beam
pattern is similar to that of Bessel beams, characterized by elongated
non-diffracting focal spots. A multiple foci structure is observed, due to the
finite size of the lens. The dependence of the focal distance on the frequency
is also discussed, on the basis of an extended grating theory. Experimental
validation of acoustic Bessel-like beam formation is also reported for sound
waves. The results can be generalized to wave beams of different nature, as
optical or matter waves.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-49611401.6869 | Abstract convex optimal antiderivatives
math.FA math.OC
Having studied families of antiderivatives and their envelopes in the setting
of classical convex analysis, we now extend and apply these notions and results
in settings of abstract convex analysis. Given partial data regarding a
c-subdifferential, we consider the set of all c-convex c-antiderivatives that
comply with the given data. Under a certain assumption, this set is not empty
and contains both its lower and upper envelopes. We represent these optimal
antiderivatives by explicit formulae. Some well known functions are, in fact,
optimal c-convex c-antiderivatives. In one application, we point out a natural
minimality property of the Fitzpatrick function of a c-monotone mapping, namely
that it is a minimal antiderivative. In another application, in metric spaces,
a constrained Lipschitz extension problem fits naturally the convexity notions
we discuss here. It turns out that the optimal Lipschitz extensions are
precisely the optimal antiderivatives. This approach yields explicit formulae
for these extensions, the most particular case of which recovers the well known
extensions due to McShane and Whitney.
| arxiv topic:math.FA math.OC |
arxiv_dataset-49621401.6969 | Room-temperature vibrational properties of multiferroic MnWO4 under
quasi-hydrostatic compression up to 39 GPa
cond-mat.mtrl-sci
The multiferroic manganese tungstate (MnWO4) has been studied by
high-pressure Raman spectroscopy at room temperature under quasi-hydrostatic
conditions up to 39.3 GPa. The low-pressure wolframite phase undergoes a phase
transition at 25.7 GPa, a pressure around 8 GPa higher than that found in
previous works which used less hydrostatic pressure-transmitting media. The
pressure dependence of the Raman active modes of both the low- and
high-pressure phases are reported and discussed comparing with the results
available in the literature for MnWO4 and related wolframites. A gradual
pressure-induced phase transition from the low- to the high- pressure phase is
suggested on the basis of the linear intensity decrease of the Raman mode with
the lowest frequency up to the end of the phase transition.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-49631401.7069 | Least-Order Torsion-Gravity for Fermion Fields, and the Non-Linear
Potentials in the Standard Models
gr-qc
We will consider the least-order torsional completion of gravity for a
spacetime filled with fermionic Dirac matter fields, and we study the effects
of the background-induced non-linear potentials for the matter field themselves
in view of their effects for both standard models of physics: from the one of
cosmology to that of particles, we will discuss the mechanisms of generation of
the cosmological constant and particle masses as well as the phenomenology of
leptonic weak-like forces and neutrino oscillations, the problem of zero-point
energy, how there can be neutral massive fields as candidates for dark matter,
and avoidance of gravitational singularity formation; we will show the way in
which all these different effects can nevertheless be altogether described in
terms of just a single model, which will be thoroughly discussed in the end.
| arxiv topic:gr-qc |
arxiv_dataset-49641401.7169 | On the Evaluation of the Polyanskiy-Poor-Verdu Converse Bound for Finite
Blocklength Coding in AWGN
cs.IT math.IT
A tight converse bound to channel coding rate in the finite block-length
regime and under AWGN conditions was recently proposed by Polyanskiy, Poor, and
Verdu (PPV). The bound is a generalization of a number of other classical
results, and it was also claimed to be equivalent to Shannon's 1959 cone
packing bound. Unfortunately, its numerical evaluation is troublesome even for
not too large values of the block-length n. In this paper we tackle the
numerical evaluation by compactly expressing the PPV converse bound in terms of
non-central chi-squared distributions, and by evaluating those through a an
integral expression and a corresponding series expansion which exploit a method
proposed by Temme. As a result, a robust evaluation method and new insights on
the bound's asymptotics, as well as new approximate expressions, are given.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-49651401.7269 | Glass-Transition Properties from Hard Spheres to Charged Point Particles
cond-mat.stat-mech cond-mat.soft
The glass transition is investigated in three dimensions for single and
double Yukawa potentials for the full range of control parameters. For
vanishing screening parameter, the limit of the one-component plasma is
obtained; for large screening parameters and high coupling strengths, the
glass-transition properties crossover to the hard-sphere system. Between the
two limits, the entire transition diagram can be described by analytical
functions. Different from other potentials, the glass-transition and melting
lines for Yukawa potentials are found to follow shifted but otherwise identical
curves in control-parameter space.
| arxiv topic:cond-mat.stat-mech cond-mat.soft |
arxiv_dataset-49661401.7369 | Linear Codes are Optimal for Index-Coding Instances with Five or Fewer
Receivers
cs.IT math.IT
We study zero-error unicast index-coding instances, where each receiver must
perfectly decode its requested message set, and the message sets requested by
any two receivers do not overlap. We show that for all these instances with up
to five receivers, linear index codes are optimal. Although this class contains
9847 non-isomorphic instances, by using our recent results and by properly
categorizing the instances based on their graphical representations, we need to
consider only 13 non-trivial instances to solve the entire class. This work
complements the result by Arbabjolfaei et al. (ISIT 2013), who derived the
capacity region of all unicast index-coding problems with up to five receivers
in the diminishing-error setup. They employed random-coding arguments, which
require infinitely-long messages. We consider the zero-error setup; our
approach uses graph theory and combinatorics, and does not require long
messages.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-49671401.7469 | Giant Seebeck coefficient in semiconducting single-wall carbon nanotube
film
cond-mat.mes-hall cond-mat.mtrl-sci
We found a giant Seebeck effect in semiconducting single-wall carbon nanotube
(SWCNT) films, which exhibited a performance comparable to that of commercial
Bi2Te3 alloys. Carrier doping of semiconducting SWCNT films further improved
the thermoelectric performance. These results were reproduced well by
first-principles transport simulations based on a simple SWCNT junction model.
These findings suggest strategies that pave the way for emerging printed,
all-carbon, flexible thermoelectric devices.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-49681401.7569 | Transversality and alternating projections for nonconvex sets
math.OC
We consider the method of alternating projections for finding a point in the
intersection of two closed sets, possibly nonconvex. Assuming only the standard
transversality condition (or a weaker version thereof), we prove local linear
convergence. When the two sets are semi-algebraic and bounded, but not
necessarily transversal, we nonetheless prove subsequence convergence.
| arxiv topic:math.OC |
arxiv_dataset-49691401.7669 | A panchromatic analysis of starburst galaxy M82: Probing the dust
properties
astro-ph.GA astro-ph.CO
(Abridged) We combine NUV, optical and IR imaging of the nearby starburst
galaxy M82 to explore the properties of the dust both in the interstellar
medium of the galaxy and the dust entrained in the superwind. The three NUV
filters of Swift/UVOT enable us to probe in detail the properties of the
extinction curve in the region around the 2175A bump. The NUV colour-colour
diagram strongly rules out a Calzetti-type law, which can either reflect
intrinsic changes in the dust properties or in the star formation history
compared to starbursts well represented by such an attenuation law. We
emphasize that it is mainly in the NUV region where a standard Milky-Way-type
law is preferred over a Calzetti law. The age and dust distribution of the
stellar populations is consistent with the scenario of an encounter with M81 in
the recent 400 Myr. The radial gradients of the NUV and optical colours in the
superwind region support the hypothesis that the emission in the wind cone is
driven by scattering from dust grains entrained in the ejecta. The observed
wavelength dependence reveals either a grain size distribution $n(a)\propto
a^{-2.5}$, where $a$ is the size of the grain, or a flatter distribution with a
maximum size cutoff, suggesting that only small grains are entrained in the
supernovae-driven wind.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-49701401.7769 | X-ray and EUV spectroscopy of various astrophysical and laboratory
plasmas -- Collisional, photoionization and charge-exchange plasmas
astro-ph.SR
Several laboratory facilities were used to benchmark theoretical spectral
models those extensively used by astronomical communities. However there are
still many differences between astrophysical environments and laboratory
miniatures that can be archived. Here we setup a spectral analysis system for
astrophysical and laboratory (SASAL) plasmas to make a bridge between them, and
investigate the effects from non-thermal electrons, contribution from
metastable level-population on level populations and charge stage distribution
for coronal-like, photoionized, and geocoronal plasmas. Test applications to
laboratory measurement (i.e. EBIT plasma) and astrophysical observation (i.e.
Comet, Cygnus X-3) are presented. Time evolution of charge stage and level
population are also explored for collisional and photoionized plasmas.
| arxiv topic:astro-ph.SR |
arxiv_dataset-49711401.7869 | Polynomial actions of unitary operators and idempotent ultrafilters
math.DS
Let $p$ be an idempotent ultrafilter over $\mathbb{N}$. For a positive
integer $N$, let ${\cal P}_{\leq N}$ denote the additive group of polynomials
$P\in\mathbb{Z}[x]$ with ${\rm deg}\, P\leq N$ and $P(0)=0$. Given a unitary
operator $U$ on a Hilbert space ${\cal H}$, we prove, for each $N\geq1$, the
existence of a unique decomposition ${\cal H}=\bigoplus_{r\geq 1}{\cal
H}^{(N)}_r$ into closed, $U$-invariant subspaces such that
(a) for any polynomial $P\in{\cal P}_{\leq N}$, we have $$ p\,
\text{-}\!\lim_{n\in\mathbb{N}} \left(U|_{{\cal
H}_r^{(N)}}\right)^{P(n)}=0_{{\cal H}_r^{(N)}}\;\mbox{or}\; Id_{{\cal
H}_r^{(N)}},\; \mbox{for each}\; r\geq1 ; $$ (b) for each $r\neq s$ there
exists $Q\in{\cal P}_{\leq N}$ such that $$ p\,\text{-}\!\lim_{n\in\mathbb{N}}
\left(U|_{{\cal H}_r^{(N)}}\right)^{Q(n)}\neq
p\,\text{-}\!\lim_{n\in\mathbb{N}} \left(U|_{{\cal H}_s^{(N)}}\right)^{Q(n)}.
$$
In connection with this result we introduce the notion of rigidity group.
Namely, a subgroup $G\subset {\cal P}_{\leq N}$ is called an $N$-rigidity group
if there exist an idempotent ultrafilter $p$ over $\mathbb{N}$ and a unitary
operator $U$ on a Hilbert space $\cal H$ such that $$\label{ab1} G=\{P\in{\cal
P}_{\leq N}:\: p\,\text{-}\!\lim_{n\in\mathbb{N}} U ^{P(n)}=Id\}$$ and
$p\,\text{-}\!\lim_{n\in\mathbb{N}} U ^{Q(n)}=0\;\;\mbox{for each}\;\;Q\in{\cal
P}_{\leq N}\setminus G.$
The main result of the paper states that a subgroup $G\subset {\cal P}_{\leq
N}$ satisfying $\max\{{\rm deg}\, P:\:P\in G\}=N$ is an $N$-rigidity group if
and only if $G$ has finite index in ${\cal P}_{\leq N}$.
| arxiv topic:math.DS |
arxiv_dataset-49721401.7969 | Uniform bounds for Fourier transforms of surface measures in R^3 with
nonsmooth density
math.CA math.FA
We prove uniform estimates for the decay rate of the Fourier transform of
measures supported on real-analytic hypersurfaces in R^3. If the surface
contains the origin and is oriented such that its normal at the origin is in
the direction of the z-axis and if dS denotes the surface measure for this
surface, then the measures under consideration are of the form K(x,y)g(z) dS
where K(x,y)g(z) is supported near the origin and both K(x,y) and g(z) are
allowed to have singularities. The estimates here generalize the previously
known sharp uniform estimates for when K(x,y)g(z) is smooth. The methods used
in this paper involve an explicit two-dimensional resolution of singularities
theorem, iterated twice, coupled with Van der Corput-type lemmas.
| arxiv topic:math.CA math.FA |
arxiv_dataset-49731401.8069 | Defect Detection Efficiency A Combined Approach
cs.SE
Survival of IT industries depends much upon the development of high quality
and customer satisfied software products. Quality however can be viewed from
various perspectives such as deployment of the products within estimated
resources, constrains and also being defect free. Testing is one of the
promising techniques ever since the inception of software in the global market.
Though there are several testing techniques existing, the most widely accepted
is the conventional scripted testing. Despite of advancement in the technology,
achieving defect free deliverables is yet a challenge. This paper therefore
aims to enhance the existing testing techniques in order to achieve nearly zero
defect products through the combined approach of scripted and exploratory
testing. This approach thus enables the testing team to capture maximum defects
and thereby reduce the expensive nature of overheads. Further, it leads towards
generation of high quality products and assures the continued customer
satisfaction.
| arxiv topic:cs.SE |
arxiv_dataset-49741401.8169 | Partitions of large unbalanced bipartites
math.CO math.PR
We compute the asymptotic behaviour of the number of partitions of large
vectors $(n_1,n_2)$ of $\mathbb{Z}_+^2$ in the critical regime $n_1 \asymp
\sqrt{n_2}$ and in the subcritical regime $n_1 = o(\sqrt{n_2})$. This work
completes the results established in the fifties by Auluck, Nanda, and Wright.
| arxiv topic:math.CO math.PR |
arxiv_dataset-49751401.8269 | Experiments with Three Approaches to Recognizing Lexical Entailment
cs.CL cs.AI cs.LG
Inference in natural language often involves recognizing lexical entailment
(RLE); that is, identifying whether one word entails another. For example,
"buy" entails "own". Two general strategies for RLE have been proposed: One
strategy is to manually construct an asymmetric similarity measure for context
vectors (directional similarity) and another is to treat RLE as a problem of
learning to recognize semantic relations using supervised machine learning
techniques (relation classification). In this paper, we experiment with two
recent state-of-the-art representatives of the two general strategies. The
first approach is an asymmetric similarity measure (an instance of the
directional similarity strategy), designed to capture the degree to which the
contexts of a word, a, form a subset of the contexts of another word, b. The
second approach (an instance of the relation classification strategy)
represents a word pair, a:b, with a feature vector that is the concatenation of
the context vectors of a and b, and then applies supervised learning to a
training set of labeled feature vectors. Additionally, we introduce a third
approach that is a new instance of the relation classification strategy. The
third approach represents a word pair, a:b, with a feature vector in which the
features are the differences in the similarities of a and b to a set of
reference words. All three approaches use vector space models (VSMs) of
semantics, based on word-context matrices. We perform an extensive evaluation
of the three approaches using three different datasets. The proposed new
approach (similarity differences) performs significantly better than the other
two approaches on some datasets and there is no dataset for which it is
significantly worse. Our results suggest it is beneficial to make connections
between the research in lexical entailment and the research in semantic
relation classification.
| arxiv topic:cs.CL cs.AI cs.LG |
arxiv_dataset-49761402.0075 | Galaxy luminosity function and its cosmological evolution: Testing a new
feedback model depending on galaxy-scale dust opacity
astro-ph.CO astro-ph.GA
We present a new version of a semi-analytic model of cosmological galaxy
formation, incorporating a star formation law with a feedback depending on the
galaxy-scale mean dust opacity and metallicity, motivated by recent
observations of star formation in nearby galaxies and theoretical
considerations. This new model is used to investigate the effect of such a
feedback on shaping the galaxy luminosity function and its evolution. Star
formation activity is significantly suppressed in dwarf galaxies by the new
feedback effect, and the faint-end slope of local luminosity functions can be
reproduced with a reasonable strength of supernova feedback, which is in
contrast to the previous models that require a rather extreme strength of
supernova feedback. Our model can also reproduce the early appearance of
massive galaxies manifested in the bright-end of high redshift K-band
luminosity functions. Though some of the previous models also succeeded in
reproducing this, they assumed a star formation law depending on the
galaxy-scale dynamical time, which is not supported by observations. We argue
that the feedback depending on dust opacity (or metal column density) is
essential, rather than that simply depending on gas column density, to get
these results.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-49771402.0175 | Aqueous alteration on main belt primitive asteroids: results from
visible spectroscopy
astro-ph.EP
This work focuses on the study of the aqueous alteration process which acted
in the main belt and produced hydrated minerals on the altered asteroids. The
aqueous alteration is particularly important for unraveling the processes
occurring during the earliest times of the Solar System history, as it can give
information both on the asteroids thermal evolution and on the localization of
water sources in the asteroid belt. We present new spectral observations in the
visible region of 80 asteroids belonging to the primitive classes C, G, F, B
and P. We combine the present observations with the visible spectra of
asteroids available in the literature for a total of 600 primitive main belt
asteroids. Our analysis shows that the aqueous alteration sequence starts from
the P-type objects, practically unaltered, and increases through the F, B, C,
and G asteroids. Around 50% of the observed C-type asteroids show absorption
features in the vis. range due to hydrated silicates, implying that more than
70% of them will have a 3 $\mu$m absorption band and thus hydrated minerals on
their surfaces. The process dominates in primitive asteroids located between
2.3 and 3.1 AU, that is at smaller heliocentric distances than previously
suggested. The aqueous alteration process dominates in the 50--240 km sized
primitive asteroids, while it is less effective for bodies smaller than 50 km.
No correlation is found between the aqueous alteration process and the
asteroids albedo or orbital elements. Comparing the $\sim$ 0.7 $\mu$m band
parameters of hydrated silicates and CM2 carbonaceous chondrites, we see that
the band center of meteorites is at longer wavelengths than that of asteroids.
This difference on center positions may be attributed to different minerals
abundances, and to the fact that CM2 available on Earth might not be
representative of the whole aqueous altered asteroids population.
| arxiv topic:astro-ph.EP |
arxiv_dataset-49781402.0275 | Aging as a mean to retain an adaptive mutation rate in mutagenesis with
asymmetric reproduction
q-bio.PE
The paper discusses a connection between asymmetric reproduction -- that is
reproduction in a parent-child relationship where the parent does not mutate
during reproduction --, the fact that all non-viral lifeforms bear genes of
their reproduction machinery and how this could relate to evolutionary
mechanisms behind aging. In a highly simplified model of the evolution process
rules are derived under which aging is an important factor of the adaption in
the evolution process and what groups of life-forms necessarily have to age and
where exceptions from that rule are possible.
| arxiv topic:q-bio.PE |
arxiv_dataset-49791402.0375 | Highly symmetric POVMs and their informational power
quant-ph cs.IT math-ph math.IT math.MP
We discuss the dependence of the Shannon entropy of normalized finite rank-1
POVMs on the choice of the input state, looking for the states that minimize
this quantity. To distinguish the class of measurements where the problem can
be solved analytically, we introduce the notion of highly symmetric POVMs and
classify them in dimension two (for qubits). In this case we prove that the
entropy is minimal, and hence the relative entropy (informational power) is
maximal, if and only if the input state is orthogonal to one of the states
constituting a POVM. The method used in the proof, employing the Michel theory
of critical points for group action, the Hermite interpolation and the
structure of invariant polynomials for unitary-antiunitary groups, can also be
applied in higher dimensions and for other entropy-like functions. The links
between entropy minimization and entropic uncertainty relations, the Wehrl
entropy and the quantum dynamical entropy are described.
| arxiv topic:quant-ph cs.IT math-ph math.IT math.MP |
arxiv_dataset-49801402.0475 | Topological invariance of the homological index
math.KT
R. W. Carey and J. Pincus in [CaPi86] proposed and index theory for
non-Fredholm bounded operators T on a separable Hilbert space H such that TT* -
T*T is in the trace class. We showed in [CGK13] using Dirac-type operators
acting on sections of bundles over R^{2n} that we could construct bounded
operators T satisfying the more general condition that (1-TT*)^n - (1-T*T)^n is
trace class. We proposed there a "homological" index for these Dirac-type
operators given by Tr( (1-TT*)^n - (1-T*T)^n ). In this paper we show that the
index introduced in [CGK13] represents the result of a pairing between a cyclic
homology theory for the algebra generated by T and T* and its dual cohomology
theory. This leads us to establish homotopy invariance of our homological index
(in the sense of cyclic theory). We are then able to define in a very general
fashion a homological index for certain unbounded operators and prove
invariance of this index under a class of unbounded perturbations.
| arxiv topic:math.KT |
arxiv_dataset-49811402.0575 | Reasoning about Explanations for Negative Query Answers in DL-Lite
cs.AI cs.LO
In order to meet usability requirements, most logic-based applications
provide explanation facilities for reasoning services. This holds also for
Description Logics, where research has focused on the explanation of both TBox
reasoning and, more recently, query answering. Besides explaining the presence
of a tuple in a query answer, it is important to explain also why a given tuple
is missing. We address the latter problem for instance and conjunctive query
answering over DL-Lite ontologies by adopting abductive reasoning; that is, we
look for additions to the ABox that force a given tuple to be in the result. As
reasoning tasks we consider existence and recognition of an explanation, and
relevance and necessity of a given assertion for an explanation. We
characterize the computational complexity of these problems for arbitrary,
subset minimal, and cardinality minimal explanations.
| arxiv topic:cs.AI cs.LO |
arxiv_dataset-49821402.0675 | Operation and performance of the CMS tracker
physics.ins-det hep-ex
The CMS silicon tracker consists of two tracking devices utilizing
semiconductor technology: the inner pixel and the outer strip detectors. They
operate in a high-occupancy and high-radiation environment presented by
particle collisions in the LHC. The tracker detectors occupy the region around
the center of CMS, where the LHC beams collide, between 4 cm and 110 cm in
radius and up to 280 cm along the beam axis. The pixel detector consists of 66
million pixels, covering about 1 m2 total area. It is surrounded by the strip
tracker with 10 million read-out channels covering about 200 m2 total area. The
proceedings describe the operational experience collected during the first
three years of LHC running. Results include operational challenges encountered
during data taking that influence the active fraction and read-out efficiency
of the detectors. Details are given about the performance of the tracker at
high occupancy with respect to local observables such as signal to noise ratio
and hit reconstruction efficiency. Studies of radiation effects are presented
with respect to the evolution of sensor bias, read-out thresholds in the inner
pixels, and leakage current.
| arxiv topic:physics.ins-det hep-ex |
arxiv_dataset-49831402.0775 | Noncommutative covering projections and $K$-homology
math.KT
If $X$ is a topological space then there is a natural homomorphism
$\pi_1(X)\rightarrow K_1(X)$ from a fundamental group to a $K_1$-homology
group. Covering projections depend of fundamental group. So $K_1$-homology
groups are interrelated with covering projections. This article is concerned
with a noncommutative analogue of this interrelationship.
| arxiv topic:math.KT |
arxiv_dataset-49841402.0875 | Quantum quenches and competing orders
cond-mat.supr-con cond-mat.str-el hep-th
We study the nonequilibrium dynamics of an electronic model of competition
between an unconventional charge density wave (a bond density wave) and
$d$-wave superconductivity. In a time-dependent Hartree-Fock+BCS approximation,
the dynamics reduces to the equations of motion of operators realizing the
generators of SU(4) at each pair of momenta, ( $\boldsymbol{k}$, -
$\boldsymbol{k}$ ), in the Brillouin zone. We also study the nonequilibrium
dynamics of a quantum generalization of a O(6) nonlinear $\sigma$ model of
competing orders in the underdoped cuprates [Hayward et al., Science
$\boldsymbol{343}$, 1336 (2014)]. We obtain results, in the large $N$ limit of
a O($N$) model, on the time dependence of correlation functions following a
pulse disturbance. We compare our numerical studies with recent picosecond
optical experiments. We find that, generically, the oscillatory responses in
our models share various qualitative features with the experiments.
| arxiv topic:cond-mat.supr-con cond-mat.str-el hep-th |
arxiv_dataset-49851402.0975 | The QCD improved electroweak parameter $\rho$
hep-ph
In the present paper, we make a detailed analysis for the QCD corrections to
the electroweak $\rho$ parameter by applying the principle of maximum
conformality (PMC). As a comparison, we show that under the conventional scale
setting, we have $\Delta\rho|_{\rm N^3LO} =
\left(8.257^{+0.045}_{-0.012}\right) \times10^{-3}$ by varying the scale
$\mu_{r}\in[M_{t}/2$, $2M_{t}]$. By defining a ratio, $\Delta
R=\Delta\rho/3X_t-1$, which shows the relative importance of the QCD
corrections, it is found that its scale error is $\sim \pm9 \%$ at the two-loop
level, which changes to $\sim\pm4\%$ at the three-loop level and $\sim \pm
2.5\%$ at the four-loop level, respectively. These facts well explain why the
conventional scale uncertainty constitutes an important error for estimating
the $\rho$ parameter. On the other hand, by applying the PMC scale setting, the
four-loop estimation $\Delta\rho|_{\rm N^3LO}$ shall be almost fixed to
$8.228\times10^{-3}$, which indicates that the conventional scale error has
been eliminated. We observe the pQCD convergence for the $\rho$ parameter has
also been greatly improved due to the elimination of the divergent renormalon
terms. As applications of the present QCD improved $\rho$ parameter, we show
the shifts of the $W$-boson mass and the effective leptonic weak-mixing angle
due to $\Delta\rho$ can be reduced to $\delta M_{W}|_{\rm N^3LO} =0.7$ MeV and
$\delta \sin^2{\theta}_{\rm eff}|_{\rm N^3LO}=-0.4\times10^{-5}$.
| arxiv topic:hep-ph |
arxiv_dataset-49861402.1075 | A New Class of Complex Ejecta Resulting from the Interaction of two CMEs
and its Expected Geoeffectiveness
astro-ph.SR physics.space-ph
A significant portion of transients measured by spacecraft at 1 AU does not
show the well-defined properties of magnetic clouds (MCs). Here, we propose a
new class of complex, non-MC ejecta resulting from the interaction of two CMEs
with different orientation, which differ from the previously studied
multiple-MC event. At 1 AU, they are associated with a smooth rotation of the
magnetic field vector over an extended duration and do not show clear signs of
interaction. We determine the characteristics of such events based on a
numerical simulation and identify and analyze a potential case in the
long-duration CME measured in situ in 2001 March 19-22. Such events may result
in intense, long-duration geo-magnetic storms, with sawtooth events, and may
sometimes be misidentified as isolated CMEs.
| arxiv topic:astro-ph.SR physics.space-ph |
arxiv_dataset-49871402.1175 | Erratum for "Elementary formula for the Hall conductivity of interacting
systems"
cond-mat.str-el
When deriving a formula for the Hall conductivity of interacting electrons in
Phys. Rev. B 86, 165133, we have relied on an unjustified implicit assumption
that a certain gauge choice could be made. Only under this condition would the
formula follow. If this condition fails, the formula we derived does not lead
to the exactly quantized value of the Hall conductance in fractional Chern
insulators.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-49881402.1275 | On the Validity of the Effective Field Theory for Dark Matter Searches
at the LHC, Part II: Complete Analysis for the s-channel
hep-ph hep-ex
We generalize in several directions our recent analysis of the limitations to
the use of the effective field theory approach to study dark matter at the LHC.
Firstly, we study the full list of operators connecting fermion DM to quarks
and gluons, corresponding to integrating out a heavy mediator in the
$s$-channel; secondly, we provide analytical results for the validity of the
EFT description for both $\sqrt{s}=8$ {\rm TeV} and $14$ {\rm TeV}; thirdly, we
make use of a MonteCarlo event generator approach to assess the validity of our
analytical conclusions. We apply our results to revisit the current collider
bounds on the ultraviolet cut-off scale of the effective field theory and show
that these bounds are weakened once the validity conditions of the effective
field theory are imposed.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-49891402.1375 | Synchronization of two self-excited double pendula
physics.class-ph nlin.CD
We consider the synchronization of two self-excited double pendula. We show
that such pendula hanging on the same beam can have four different synchronous
configurations. Our approximate analytical analysis allows us to derive the
synchronization conditions and explain the observed types of synchronization.
We consider an energy balance in the system and describe how the energy is
transferred between the pendula via the oscillating beam, allowing thus the
pendula synchronization. Changes and stability ranges of the obtained solutions
with increasing and decreasing masses of the pendula are shown using
path-following.
| arxiv topic:physics.class-ph nlin.CD |
arxiv_dataset-49901402.1475 | The Transport of Cosmic Rays Across Magnetic Fieldlines
astro-ph.HE
The long residence times and small anisotropies of cosmic rays suggest that
they are well confined and well scattered by the Galactic magnetic field. Due
to the disklike shape of the confinement volume, transport in the vertical
direction, perpendicular to the mean Galactic magnetic field, is key to cosmic
ray escape. It has long been recognized that this vertical transport depends
both on the vertical component of the fieldlines themselves and on the extent
to which the cosmic rays are tied to the fieldlines. In this paper we use
magnetic fields with very simple spatial and temporal structure to isolate some
important features of cross fieldline transport. We show that even simple
magnetic nonuniformities combined with pitch angle scattering can enhance cross
fieldline transport by several orders of magnitude, while pitch angle
scattering is unnecessary for enhanced transport if the field is chaotic.
Nevertheless, perpendicular transport is much less than parallel transport in
all the cases we study. We apply the results to confinement of cosmic rays in
the Fermi Bubbles.
| arxiv topic:astro-ph.HE |
arxiv_dataset-49911402.1575 | Positronium contribution to the electron g-2
hep-ph
The contribution of positronium to the electron $g$-2 ($a_e$) has been
computed in Ref. [1] and found to be of the same order of $\alpha$ as that of
five-loop perturbative QED. We confirm this result and correct a few errors in
its first derivation. As recently calculated in Ref. [2], a continuum
nonperturbative contribution to $a_e$ cancels one-half of the positronium one.
We show by explicit calculation that the remaining half is already included in
the five-loop perturbative result. We also show that it arises from the class
I(i) of five-loop diagrams containing only one closed electron loop.
| arxiv topic:hep-ph |
arxiv_dataset-49921402.1675 | Rationality problem for transitive subgroups of S_8
math.AG
For any field K and any transitive subgroup G of S_8, let G acts naturally on
K(x_1, . . ., x_8) by permutations of the variables, we prove that under some
minor conditions K(x_1, . . ., x_8)^G is always K-rational except G is A_8 or G
is isomorphic to PGL(2, 7). We pay special attentions on the characteristic 2
cases.
| arxiv topic:math.AG |
arxiv_dataset-49931402.1775 | The topology of quaternionic contact manifolds
math.DG
We explore the consequences of curvature and torsion on the topology of
quaternionic contact manifolds with integrable vertical distribution. We prove
a general Myers theorem and establish a Cartan-Hadamard result for almost
qc-Einstein manifolds.
| arxiv topic:math.DG |
arxiv_dataset-49941402.1875 | The Lusternik-Schnirelmann category of metric spaces
math.AT math.GN
We extend the theory of the Lusternik-Schnirelmann category to general metric
spaces by means of covers by arbitrary subsets. We also generalize the
definition of the strict category weight. We show that if the Bockstein
homomorphism on a metric space is non-zero, then its LS-category is at least
two, and use this to compute the category of Pontryagin surfaces. Additionally,
we prove that a Polish space with LS-category $n$ can be presented as the
inverse limit of ANR spaces of category at most $n$.
| arxiv topic:math.AT math.GN |
arxiv_dataset-49951402.1975 | A note on general sliding window processes
math.PR
Let $f:\mathbb{R}^k\to \mathbb{R}$ be a measurable function, and let
$\{U_i\}_{i\in\mathbb{N}}$ be a sequence of i.i.d. random variables. Consider
the random process $Z_i=f(U_{i},...,U_{i+k-1})$. We show that for all $\ell$,
there is a positive probability, uniform in $f$, for $Z_1,...,Z_\ell$ to be
monotone. We give upper and lower bounds for this probability, and draw
corollaries for $k$-block factor processes with a finite range.
The proof is based on an application of combinatorial results from Ramsey
theory to the realm of continuous probability.
| arxiv topic:math.PR |
arxiv_dataset-49961402.2075 | A search for small and medium scale anisotropy of cosmic rays above 1
PeV registered at the Tunka-133 array
astro-ph.HE
A search for anisotropy at different scales in the arrival directions of
cosmic rays with energies above 1 PeV is performed with data of the Tunka-133
array. A number of regions with angular sizes up to approximately 30 degrees
that deviate from the uniform background with a statistical significance
greater than three standard deviations are found using the shuffling technique
both in the complete data set and its subsets in different energy ranges. Some
regions with an excess of cosmic rays correlate with the distribution of
possible cosmic ray sources. A comparison of the results with a similar
analysis of the legacy data of the EAS MSU array is presented.
| arxiv topic:astro-ph.HE |
arxiv_dataset-49971402.2175 | A Characterization of Locally Testable Affine-Invariant Properties via
Decomposition Theorems
cs.CC
Let $\mathcal{P}$ be a property of function $\mathbb{F}_p^n \to \{0,1\}$ for
a fixed prime $p$. An algorithm is called a tester for $\mathcal{P}$ if, given
a query access to the input function $f$, with high probability, it accepts
when $f$ satisfies $\mathcal{P}$ and rejects when $f$ is "far" from satisfying
$\mathcal{P}$. In this paper, we give a characterization of affine-invariant
properties that are (two-sided error) testable with a constant number of
queries. The characterization is stated in terms of decomposition theorems,
which roughly claim that any function can be decomposed into a structured part
that is a function of a constant number of polynomials, and a pseudo-random
part whose Gowers norm is small. We first give an algorithm that tests whether
the structured part of the input function has a specific form. Then we show
that an affine-invariant property is testable with a constant number of queries
if and only if it can be reduced to the problem of testing whether the
structured part of the input function is close to one of a constant number of
candidates.
| arxiv topic:cs.CC |
arxiv_dataset-49981402.2275 | New self dualities and duality cascades
hep-th hep-ph
New self-dualities involving two index tensors are derived. These new
self-dualities are used to build various duality cascades. Both vector like and
chiral cascades are presented. Aside from ending in confinement, these duality
cascades can also end in interacting conformal field theories, free field
theories, and meta-stable supersymmetry breaking. Higgsing effects are built
into the self-duality so that when the gauge groups are small enough,
supersymmetry is broken through the rank condition. Dynamical supersymmetry
restoration occurs far from the SUSY breaking vacuum resulting in a long lived
meta-stable vacuum. It is found that Coulomb branches are critical in the
stabilization of runaways and dynamical supersymmetry restoration.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-49991402.2375 | Significance of Coupling and Cohesion on Design Quality
cs.SE
In recent years, the complexity of the software is increasing due to
automation of every segment of application. Software is nowhere remained as
one-time development product since its architectural dimension is increasing
with addition of new requirements over a short duration. Object Oriented
Development (OOD) methodology is a popular development approach for such
systems which perceives and models the requirements as real world entities.
Classes and Objects logically represent the entities in the solution space and
quality of the software is directly depending on the design quality of these
logical entities. Cohesion and Coupling (C&C) are two major design decisive
factors in OOD which impacts the design of a class and dependency between them
in complex software. It is also most significant to measure C&C for software to
control the complexity level as requirements increases. Several metrics are in
practice to quantify C&C which plays a major role in measuring the design
quality. The software industries are focusing on increasing and measuring the
quality of the product through quality design to continue their market image in
the competitive world. As a part of our research, this paper highlights on the
impact of C&C on design quality of a complex system and its measures to
quantify the overall quality of software.
| arxiv topic:cs.SE |
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