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arxiv_dataset-52001404.6947 | Distance and proper motion measurement of water masers in Shapless 269
IRS 2w
astro-ph.GA
We present astrometric analysis of archival data of water masers in the
star-forming region Sharpless 269 (S269) IRS 2w, observed with the VLBI
Exploration of Radio Astrometry. An annual parallax of one of the bright maser
features in this region was previously reported to be 0.189+/-0.008
milliarcsecond (mas) using part of the same archival data as we used. However,
we found that this maser feature is not the best to represent the annual
parallax to S269 IRS 2w because the morphology is remarkably elongated in the
east-west direction. For this study we have selected another maser feature
showing simpler morphology. This makes the new annual parallax estimate more
credible. Our newly obtained annual parallax is 0.247+/-0.034 mas,
corresponding to 4.05+0.65-0.49 kpc. This value is well consistent with the
3.7-3.8 kpc obtained using the kinematic distance estimates and photometric
distance modulus. We considered two hypotheses for the water maser spatial
distribution, a bipolar outflow and an expanding ring, in a kinematic model
fitting analysis with a radially expanding flow. At this stage, any conclusions
about the systemic proper motion could not be drawn from the kinematic
analysis. Alternatively, we evaluated the mean proper motion to be
(0.39+/-0.92, -1.27+/-0.90) mas/yr eastward and northward, respectively, from
the obtained proper motions of the detected water maser features. The newly
obtained annual parallax and mean proper motion give the peculiar motion of
S269 IRS 2w to be (Us, Vs, Ws) of (8+/-6, -21+/-17, 1+/-18) km/s.
| arxiv topic:astro-ph.GA |
arxiv_dataset-52011404.7047 | Extended dynamical mean-field study of the Hubbard model with long range
interactions
cond-mat.str-el
Using extended dynamical mean-field theory and its combination with the $GW$
approximation, we compute the phase diagrams and local spectral functions of
the single-band extended Hubbard model on the square and simple cubic lattices,
considering long range interactions up to the third nearest neighbors. The
longer range interactions shift the boundaries between the metallic,
charge-ordered insulating and Mott insulating phases, and lead to
characteristic changes in the screening modes and local spectral functions.
Momentum-dependent self-energy contributions enhance the correlation effects
and thus compete with the additional screening effect from longer range Coulomb
interactions. Our results suggest that the influence of longer range intersite
interactions is significant, and that these effects deserve attention in
realistic studies of correlated materials.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-52021404.7147 | Dynamics of stellar black holes in young star clusters with different
metallicities - II. Black hole-black hole binaries
astro-ph.GA astro-ph.CO astro-ph.HE astro-ph.SR gr-qc
In this paper, we study the formation and dynamical evolution of black
hole-black hole (BH-BH) binaries in young star clusters (YSCs), by means of
N-body simulations. The simulations include metallicity-dependent recipes for
stellar evolution and stellar winds, and have been run for three different
metallicities (Z = 0.01, 0.1 and 1 Zsun). Following recent theoretical models
of wind mass-loss and core-collapse supernovae, we assume that the mass of the
stellar remnants depends on the metallicity of the progenitor stars. We find
that BH-BH binaries form efficiently because of dynamical exchanges: in our
simulations, we find about 10 times more BH-BH binaries than double neutron
star binaries. The simulated BH-BH binaries form earlier in metal-poor YSCs,
which host more massive black holes (BHs) than in metal-rich YSCs. The
simulated BH-BH binaries have very large chirp masses (up to 80 Msun), because
the BH mass is assumed to depend on metallicity, and because BHs can grow in
mass due to the merger with stars. The simulated BH-BH binaries span a wide
range of orbital periods (10^-3-10^7 yr), and only a small fraction of them
(0.3 per cent) is expected to merge within a Hubble time. We discuss the
estimated merger rate from our simulations and the implications for Advanced
VIRGO and LIGO.
| arxiv topic:astro-ph.GA astro-ph.CO astro-ph.HE astro-ph.SR gr-qc |
arxiv_dataset-52031404.7247 | Human Factors of Formal Methods
cs.SE cs.HC
This paper provides a brief introduction to the work that aims to apply the
achievements within the area of engineering psychology to the area of formal
methods, focusing on the specification phase of a system development process.
| arxiv topic:cs.SE cs.HC |
arxiv_dataset-52041404.7347 | Covert Optical Communication
cs.IT math.IT quant-ph
Encryption prevents unauthorized decoding, but does not ensure stealth---a
security demand that a mere presence of a message be undetectable. We
characterize the ultimate limit of covert communication that is secure against
the most powerful physically-permissible adversary. We show that, although it
is impossible over a pure-loss channel, covert communication is attainable in
the presence of any excess noise, such as a $300$K thermal blackbody. In this
case, $\mathcal{O}(\sqrt{n})$ bits can be transmitted reliably and covertly in
$n$ optical modes using standard optical communication equipment. The
all-powerful adversary may intercept all transmitted photons not received by
the intended receiver, and employ arbitrary quantum memory and measurements.
Conversely, we show that this square root scaling cannot be outperformed. We
corroborate our theory in a proof-of-concept experiment. We believe that our
findings will enable practical realizations of covert communication and
sensing, both for point-to-point and networked scenarios.
| arxiv topic:cs.IT math.IT quant-ph |
arxiv_dataset-52051404.7447 | An Introduction to the Patstat Database with Example Queries
cs.DL
This paper provides an introduction to the Patstat patent database. It offers
guided examples of ten popular queries that are relevant for research purposes
and that cover the most important data tables. It is targeted at academic
researchers and practitioners willing to learn the basics of the database.
| arxiv topic:cs.DL |
arxiv_dataset-52061404.7547 | On the Impact of Dimension Reduction on Graphical Structures
stat.ME
Statisticians and quantitative neuroscientists have actively promoted the use
of independence relationships for investigating brain networks, genomic
networks, and other measurement technologies. Estimation of these graphs
depends on two steps. First is a feature extraction by summarizing measurements
within a parcellation, regional or set definition to create nodes. Secondly,
these summaries are then used to create a graph representing relationships of
interest. In this manuscript we study the impact of dimension reduction on
graphs that describe different notions of relations among a set of random
variables. We are particularly interested in undirected graphs that capture the
random variables' independence and conditional independence relations. A
dimension reduction procedure can be any mapping from high dimensional spaces
to low dimensional spaces. We exploit a general framework for modeling the raw
data and advocate that in estimating the undirected graphs, any acceptable
dimension reduction procedure should be a graph-homotopic mapping, i.e., the
graphical structure of the data after dimension reduction should inherit the
main characteristics of the graphical structure of the raw data. We show that,
in terms of inferring undirected graphs that characterize the conditional
independence relations among random variables, many dimension reduction
procedures, such as the mean, median, or principal components, cannot be
theoretically guaranteed to be a graph-homotopic mapping. The implications of
this work are broad. In the most charitable setting for researchers, where the
correct node definition is known, graphical relationships can be contaminated
merely via the dimension reduction. The manuscript ends with a concrete
example, characterizing a subset of graphical structures such that the
dimension reduction procedure using the principal components can be a
graph-homotopic mapping.
| arxiv topic:stat.ME |
arxiv_dataset-52071404.7647 | The Hahn-Exton $q$-Bessel function as the characteristic function of a
Jacobi matrix
math.SP
A family $\mathcal{T}^{(\nu)}$, $\nu\in\mathbb{R}$, of semiinfinite positive
Jacobi matrices is introduced with matrix entries taken from the Hahn-Exton
$q$-difference equation. The corresponding matrix operators defined on the
linear hull of the canonical basis in $\ell^{2}(\mathbb{Z}_{+})$ are
essentially self-adjoint for $|\nu|\geq1$ and have deficiency indices $(1,1)$
for $|\nu|<1$. A convenient description of all self-adjoint extensions is
obtained and the spectral problem is analyzed in detail. The spectrum is
discrete and the characteristic equation on eigenvalues is derived explicitly
in all cases. Particularly, the Hahn-Exton $q$-Bessel function $J_{\nu}(z;q)$
serves as the characteristic function of the Friedrichs extension. As a direct
application one can reproduce, in an alternative way, some basic results about
the $q$-Bessel function due to Koelink and Swarttouw.
| arxiv topic:math.SP |
arxiv_dataset-52081404.7747 | Relativistic equation-of-motion coupled-cluster method for the double
ionization potentials of the closed-shell atoms
physics.atom-ph
We report the general implementation of the relativistic equation-of-motion
coupled-cluster method to calculate double ionization spectra (DI-EOMCC) of
atomic and molecular systems. As a first application, this method is employed
to calculate the principal valence double ionization potential values of He and
alkaline earth metal (Be, Mg, Ca, Sr and Ba) atoms. Our results are compared
with the results available from the national institute of standards and
technology (NIST) database and other ab initio calculations. We have achieved
an accuracy of ~ 0.1%, which is an improvement over the first principles
T-matrix calculations [J. Chem. Phys. 123, 144112 (2005)]. We also present
results using the second-order many-body perturbation theory and the random-
phase approximation in the equation-of-motion framework and these results are
compared with the DI-EOMCC results.
| arxiv topic:physics.atom-ph |
arxiv_dataset-52091404.7847 | Importance of frequency-dependent grain boundary scattering in
nanocrystalline silicon and silicon-germanium thermoelectrics
cond-mat.mes-hall
Nanocrystalline silicon and silicon-germanium alloys are promising
thermoelectric materials that have achieved substantially improved figure of
merits compared to their bulk counterparts. This enhancement is typically
attributed to a reduction in lattice thermal conductivity by phonon scattering
at grain boundaries. However, further improvements are difficult to achieve
because grain boundary scattering is poorly understood, with recent
experimental observations suggesting that the phonon transmissivity may depend
on phonon frequency rather than being constant as in the commonly used gray
model. Here, we examine the impact of frequency-dependent grain boundary
scattering in nanocrystalline silicon and silicon-germanium alloys in a
realistic 3D geometry using frequency-dependent variance-reduced Monte Carlo
simulations. We find that the grain boundary may not be as effective as
predicted by the gray model in scattering certain phonons, with a substantial
amount of heat being carried by low frequency phonons with mean free paths
longer than the grain size. Our result will help guide the design of more
efficient thermoelectrics.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-52101405.0092 | Electron-doped phosphorene: A potential monolayer superconductor
cond-mat.supr-con cond-mat.mes-hall cond-mat.mtrl-sci
We predict by first-principles calculations that the electron-doped
phosphorene is a potential BCS-like superconductor. The stretching modes at the
Brillouin-zone center are remarkably softened by the electron-doping, which
results in the strong electron-phonon coupling. The superconductivity can be
introduced by a doped electron density ($n_{2D}$) above $1.3 \times10^{14}$
cm$^{-2}$, and may exist over the liquid helium temperature when $n_{2D}>2.6
\times10^{14}$ cm$^{-2}$. The maximum critical temperature is predicted to be
higher than 10 K. The superconductivity of phosphorene will significantly
broaden the applications of this novel material.
| arxiv topic:cond-mat.supr-con cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-52111405.0192 | Geo-neutrinos and Earth Models
physics.geo-ph
We present the current status of geo-neutrino measurements and their
implications for radiogenic heating in the mantle. Earth models predict
different levels of radiogenic heating and, therefore, different geo-neutrino
fluxes from the mantle. Seismic tomography reveals features in the deep mantle
possibly correlated with radiogenic heating and causing spatial variations in
the mantle geo-neutrino flux at the Earth surface. An ocean-based observatory
offers the greatest sensitivity to the mantle flux and potential for resolving
Earth models and mantle features. Refinements to estimates of the geo-neutrino
flux from continental crust reduce uncertainty in measurements of the mantle
flux, especially measurements from land-based observatories. These refinements
enable the resolution of Earth models using the combined measurements from
multiple continental observatories.
| arxiv topic:physics.geo-ph |
arxiv_dataset-52121405.0292 | Helioseismology and Asteroseismology: Looking for Gravitational Waves in
acoustic oscillations
astro-ph.CO astro-ph.SR gr-qc physics.ins-det physics.space-ph
Current helioseismology observations allow the determination of the
frequencies and surface velocity amplitudes of solar acoustic modes with
exceptionally high precision. In some cases, the frequency accuracy is better
than one part in a million. We show that there is a distinct possibility that
the quadrupole acoustic modes of low order could be excited by gravitational
waves (GWs), if the GWs have a strain amplitude in the range $10^{-20}h_{-20}$
with $h_{-20}\sim 1$ or $h_{-20}\sim 10^{3}$, as predicted by several types of
GW sources, such as galactic ultracompact binaries or extreme mass ratio
inspirals and coalescence of black holes. If the damping rate at low order is $
10^{-3}\eta_N$ $\mu{\rm Hz}$, with $\eta_N\sim 10^{-3} $ - $1,$ as inferred
from the theory of stellar pulsations, then GW radiation will lead to a maximum
rms surface velocity amplitude of quadrupole modes of the order of
$h_{-20}\eta_N^{-1}\sim$ $10^{-9}$ - $10^{-3}$ ${\rm cm\; s^{-1}}$, on the
verge of what is currently detectable via helioseismology. The frequency and
sensitivity range probed by helioseismological acoustic modes overlap with, and
complement, the capabilities of eLISA for the brightest resolved ultracompact
galactic binaries.
| arxiv topic:astro-ph.CO astro-ph.SR gr-qc physics.ins-det physics.space-ph |
arxiv_dataset-52131405.0392 | Maxima of the $Q$-index for outer-planar graphs
math.CO
The $Q$-$index$ of graph $G$ is the largest eigenvalue $q(G)$ of its signless
Laplacian $Q(G)$. In this paper, we prove that the graph $K_{1}\nabla P_{n-1}$
has the maximal $Q$-index among all outer-planar graphs of order $n$.
| arxiv topic:math.CO |
arxiv_dataset-52141405.0492 | Clustering, host halos and environment of z$\sim$2 galaxies as a
function of their physical properties
astro-ph.GA astro-ph.CO
Using a sample of 25683 star-forming and 2821 passive galaxies at $z\sim2$,
selected in the COSMOS field following the BzK color criterion, we study the
hosting halo mass and environment of galaxies as a function of their physical
properties. Spitzer and Herschel provide accurate SFR estimates for starburst
galaxies. We measure the auto- and cross-correlation functions of various
galaxy sub-samples and infer the properties of their hosting halos using both
an HOD model and the linear bias at large scale. We find that passive and
star-forming galaxies obey a similarly rising relation between the halo and
stellar mass. The mean host halo mass of star forming galaxies increases with
the star formation rate between 30 and 200 M$_\odot$.yr$^{-1}$, but flattens
for higher values, except if we select only main-sequence galaxies. This
reflects the expected transition from a regime of secular co-evolution of the
halos and the galaxies to a regime of episodic starburst. We find similar large
scale biases for main-sequence, passive, and starburst galaxies at equal
stellar mass, suggesting that these populations live in halos of the same mass.
We detect an excess of clustering on small scales for passive galaxies and
showed, by measuring the large-scale bias of close pairs, that this excess is
caused by a small fraction ($\sim16%$) of passive galaxies being hosted by
massive halos ($\sim 3 \times 10^{13}$ M$_\odot$) as satellites. Finally,
extrapolating the growth of halos hosting the z$\sim$2 population, we show that
M$_\star \sim 10^{10}$ M$_\odot$ galaxies at z$\sim$2 will evolve, on average,
into massive (M$_\star \sim 10^{11}$ M$_\odot$), field galaxies in the local
Universe and M$_\star \sim 10^{11}$ M$_\odot$ galaxies at z=2 into local,
massive, group galaxies. The most massive main-sequence galaxies and close
pairs of massive, passive galaxies end up in today's clusters.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-52151405.0592 | Lie Symmetry Classification and Numerical Analysis of KdV Equation with
Power-law Nonlinearity
math.DG nlin.SI
In this paper, a complete Lie symmetry analysis of the damped wave equation
with time-dependent coefficients is investigated. Then the invariant solutions
and the exact solutions generated from the symmetries are presented. Moreover,
a Lie algebraic classifications and the optimal system are discussed. Finally,
using Chebyshev pseudo-spectral method (CPSM), a numerical analysis to solve
the invariant solutions corresponded the Lie symmetries of main equation is
presented. This method applies the Chebyshev-Gauss-Lobatto points as
collocation points.
| arxiv topic:math.DG nlin.SI |
arxiv_dataset-52161405.0692 | In situ electromagnetic field diagnostics with an electron plasma in a
Penning-Malmberg trap
physics.plasm-ph nucl-ex physics.atom-ph
We demonstrate a novel detection method for the cyclotron resonance frequency
of an electron plasma in a Penning-Malmberg trap. With this technique, the
electron plasma is used as an in situ diagnostic tool for measurement of the
static magnetic field and the microwave electric field in the trap. The
cyclotron motion of the electron plasma is excited by microwave radiation and
the temperature change of the plasma is measured non-destructively by
monitoring the plasma's quadrupole mode frequency. The spatially-resolved
microwave electric field strength can be inferred from the plasma temperature
change and the magnetic field is found through the cyclotron resonance
frequency. These measurements were used extensively in the recently reported
demonstration of resonant quantum interactions with antihydrogen.
| arxiv topic:physics.plasm-ph nucl-ex physics.atom-ph |
arxiv_dataset-52171405.0792 | On Exact Learning Monotone DNF from Membership Queries
cs.LG
In this paper, we study the problem of learning a monotone DNF with at most
$s$ terms of size (number of variables in each term) at most $r$ ($s$ term
$r$-MDNF) from membership queries. This problem is equivalent to the problem of
learning a general hypergraph using hyperedge-detecting queries, a problem
motivated by applications arising in chemical reactions and genome sequencing.
We first present new lower bounds for this problem and then present
deterministic and randomized adaptive algorithms with query complexities that
are almost optimal. All the algorithms we present in this paper run in time
linear in the query complexity and the number of variables $n$. In addition,
all of the algorithms we present in this paper are asymptotically tight for
fixed $r$ and/or $s$.
| arxiv topic:cs.LG |
arxiv_dataset-52181405.0892 | A Continuous Max-Flow Approach to Multi-Labeling Problems under
Arbitrary Region Regularization
cs.CV
The incorporation of region regularization into max-flow segmentation has
traditionally focused on ordering and part-whole relationships. A side effect
of the development of such models is that it constrained regularization only to
those cases, rather than allowing for arbitrary region regularization. Directed
Acyclic Graphical Max-Flow (DAGMF) segmentation overcomes these limitations by
allowing for the algorithm designer to specify an arbitrary directed acyclic
graph to structure a max-flow segmentation. This allows for individual 'parts'
to be a member of multiple distinct 'wholes.'
| arxiv topic:cs.CV |
arxiv_dataset-52191405.0992 | Spontaneous generation of quantum turbulence through the decay of a
giant vortex in a two-dimensional superfluid
cond-mat.quant-gas
We show the generation of two-dimensional quantum turbulence through
simulations of a giant vortex decay in a trapped Bose-Einstein condensate.
While evaluating the incompressible kinetic energy spectra of the quantum fluid
described by the Gross-Pitaevskii equation, a bilinear form in a log-log plot
is verified. A characteristic scaling behavior for small momenta shows
resemblance to the Kolmogorov $k^{-5/3}$ law, while for large momenta it
reassures the universal behavior of the core-size $k^{-3}$ power-law. This
indicates a mechanism of energy transportation consistent with an inverse
cascade. The feasibility of the described physical system with the currently
available experimental techniques to create giant vortices opens up a new route
to explore quantum turbulence.
| arxiv topic:cond-mat.quant-gas |
arxiv_dataset-52201405.1092 | Semi-localizations of semi-abelian categories
math.CT
A semi-localization of a category is a full reflective subcategory with the
property that the reflector is semi-left-exact. In this article we first
determine an abstract characterization of the categories which are
semi-localizations of an exact Mal'tsev category, by specializing a result due
to S. Mantovani. We then turn our attention to semi-abelian categories, where a
special type of semi-localizations are known to coincide with torsion-free
subcategories. A new characterisation of protomodular categories in terms of
binary relations is obtained, inspired by the one discovered in the pointed
context by Z. Janelidze. This result is useful to obtain an abstract
characterization of the torsion-free and of the hereditarily-torsion-free
subcategories of semi-abelian categories. Some examples are considered in
detail in the categories of groups, crossed modules, commutative rings and
topological groups. We finally explain how these results extend similar ones
obtained by W. Rump in the abelian context.
| arxiv topic:math.CT |
arxiv_dataset-52211405.1192 | Semantically Guided Evolution of $\mathcal{SHI}$ ABoxes
cs.LO
This paper presents a method for the evolution of SHI ABoxes which is based
on a compilation technique of the knowledge base. For this the ABox is regarded
as an interpretation of the TBox which is close to a model. It is shown, that
the ABox can be used for a semantically guided transformation resulting in an
equisatisfiable knowledge base. We use the result of this transformation to
efficiently delete assertions from the ABox. Furthermore, insertion of
assertions as well as repair of inconsistent ABoxes is addressed. For the
computation of the necessary actions for deletion, insertion and repair, the
E-KRHyper theorem prover is used.
| arxiv topic:cs.LO |
arxiv_dataset-52221405.1292 | Belief propagation for minimum weight many-to-one matchings in the
random complete graph
math.PR cs.DM cs.IT math.IT
In a complete bipartite graph with vertex sets of cardinalities $n$ and $m$,
assign random weights from exponential distribution with mean 1, independently
to each edge. We show that, as $n\rightarrow\infty$, with $m = \lceil
n/\alpha\rceil$ for any fixed $\alpha>1$, the minimum weight of many-to-one
matchings converges to a constant (depending on $\alpha$). Many-to-one matching
arises as an optimization step in an algorithm for genome sequencing and as a
measure of distance between finite sets. We prove that a belief propagation
(BP) algorithm converges asymptotically to the optimal solution. We use the
objective method of Aldous to prove our results. We build on previous works on
minimum weight matching and minimum weight edge-cover problems to extend the
objective method and to further the applicability of belief propagation to
random combinatorial optimization problems.
| arxiv topic:math.PR cs.DM cs.IT math.IT |
arxiv_dataset-52231405.1392 | From Tweets to Events: Exploring a Scalable Solution for Twitter Streams
cs.SI
The unprecedented use of social media through smartphones and other
web-enabled mobile devices has enabled the rapid adoption of platforms like
Twitter. Event detection has found many applications on the web, including
breaking news identification and summarization. The recent increase in the
usage of Twitter during crises has attracted researchers to focus on detecting
events in tweets. However, current solutions have focused on static Twitter
data. The necessity to detect events in a streaming environment during fast
paced events such as a crisis presents new opportunities and challenges. In
this paper, we investigate event detection in the context of real-time Twitter
streams as observed in real-world crises. We highlight the key challenges in
this problem: the informal nature of text, and the high volume and high
velocity characteristics of Twitter streams. We present a novel approach to
address these challenges using single-pass clustering and the compression
distance to efficiently detect events in Twitter streams. Through experiments
on large Twitter datasets, we demonstrate that the proposed framework is able
to detect events in near real-time and can scale to large and noisy Twitter
streams.
| arxiv topic:cs.SI |
arxiv_dataset-52241405.1492 | Open sets of diffeomorphisms with trivial centralizer in the $C^1$
topology
math.DS
On the torus of dimension $2$, $3$, or $4$, we show that the subset of
diffeomorphisms with trivial centralizer in the $C^1$ topology has nonempty
interior. We do this by developing two approaches, the fixed point and the odd
prime periodic point, to obtain trivial centralizer for an open neighbourhood
of Anosov diffeomorphisms arbitrarily near certain irreducible hyperbolic toral
automorphism.
| arxiv topic:math.DS |
arxiv_dataset-52251405.1592 | Thermoelectric performance of classical topological insulator nanowires
cond-mat.mtrl-sci
There is currently substantial effort being invested into creating efficient
thermoelectric nanowires based on topological insulator chalcogenide-type
materials. A key premise of these efforts is the assumption that the generally
good thermoelectric properties that these materials exhibit in bulk form will
translate into similarly good or even better thermoelectric performance of the
same materials in nanowire form. Here, we calculate thermoelectric performance
of topological insulator nanowires based on Bi2Te3, Sb2Te3 and Bi2Se3 as a
function of diameter and Fermi level. We show that the thermoelectric
performance of topological insulator nanowires does not derive from the
properties of the bulk material in a straightforward way. For all investigated
systems the competition between surface states and bulk channel causes a
significant modification of the thermoelectric transport coefficients if the
diameter is reduced into the sub-10 um range. Key aspects are that the surface
and bulk states are optimized at different Fermi levels or have different
polarity as well as the high surface to volume ratio of the nanowires. This
limits the maximum thermoelectric performance of topological insulator
nanowires and thus their application in efficient thermoelectric devices.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-52261405.1692 | Minimum length effects in black hole physics
hep-th gr-qc
We review the main consequences of the possible existence of a minimum
measurable length, of the order of the Planck scale, on quantum effects
occurring in black hole physics. In particular, we focus on the ensuing minimum
mass for black holes and how modified dispersion relations affect the Hawking
decay, both in four space-time dimensions and in models with extra spatial
dimensions. In the latter case, we briefly discuss possible phenomenological
signatures.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-52271405.1792 | RAPTT: An Exact Two-Sample Test in High Dimensions Using Random
Projections
stat.ME stat.CO
In high dimensions, the classical Hotelling's $T^2$ test tends to have low
power or becomes undefined due to singularity of the sample covariance matrix.
In this paper, this problem is overcome by projecting the data matrix onto
lower dimensional subspaces through multiplication by random matrices. We
propose RAPTT (RAndom Projection T-Test), an exact test for equality of means
of two normal populations based on projected lower dimensional data. RAPTT does
not require any constraints on the dimension of the data or the sample size. A
simulation study indicates that in high dimensions the power of this test is
often greater than that of competing tests. The advantage of RAPTT is
illustrated on high-dimensional gene expression data involving the
discrimination of tumor and normal colon tissues.
| arxiv topic:stat.ME stat.CO |
arxiv_dataset-52281405.1892 | Intra-inter band pairing, order parameter symmetry in Fe-based
superconductors : A model study
cond-mat.supr-con
In the quest of why there should be a single transition temperature in a
multi-gapped system like Fe-based materials we use two band model for
simplicity. The model comprises of spin density wave (SDW), orbital density
wave (ODW) arising due to nested pieces of the electron and hole like Fermi
surfaces; together with superconductivity of different pairing symmetries
around electron and hole like Fermi surfaces. We show that either only intra or
only inter band pairing is insufficient to describe some of the experimental
results like large to small gap ratio, thermal behaviour of electronic specific
heat jump etc. It is shown that the inter-band pairing is essential in Fe-based
materials having multiple gaps to produce a single global $T_c$. Some of our
results in this scenario, matches with the earlier published work
\cite{two-band-prb}, and also have differences. The origin of difference
between the two is also discussed. Combined intra-inter band pairing mechanism
produces the specific heat jump to superconducting transition temperature ratio
proportional to square of the transition temperature, both in the electron and
hole doped regime, for sign changing s$^{\pm}$ wave symmetry which takes the
d+s pairing symmetry form. Our work thus demonstrates the importance of
combined intra-inter band pairing irrespective of the pairing mechanism.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-52291405.1992 | Structured Approach to Web Development
cs.SE cs.PL
In today's world of Web application development, programmers are commonly
called upon to use the Hypertext Markup Language (HTML) as a programming
language, something for which it was never intended and for which it is
woefully inadequate. HTML is a data language, nothing more. It lacks high level
programming constructions like procedures, conditions, and loops. Moreover it
provides no intrinsic mechanism to insert or associate dynamic application
data. Lastly, despite the visibly apparent structure of a web page when viewed
in a browser, the responsible HTML code bears little to no discernible
corresponding structure, making it very difficult to read, augment, and
maintain.
This paper examines the various drawbacks inherent in HTML when used in Web
development and examines the various augmenting technologies available in the
industry today and their drawbacks. It then proposes an alternative, complete
with the necessary constructs, structure, and data associating facilities based
upon server-side, Extensible Stylesheet Language Transforms (XSLT). This
alternative approach gives rise to an entirely new, higher level, markup
language that can be readily used in web development.
| arxiv topic:cs.SE cs.PL |
arxiv_dataset-52301405.2092 | Full-Duplex Cloud Radio Access Networks: An Information-Theoretic
Viewpoint
cs.IT math.IT
The conventional design of cellular systems prescribes the separation of
uplink and downlink transmissions via time-division or frequency-division
duplex. Recent advances in analog and digital domain self-interference
interference cancellation challenge the need for this arrangement and open up
the possibility to operate base stations, especially low-power ones, in a
full-duplex mode. As a means to cope with the resulting downlink-to-uplink
interference among base stations, this letter investigates the impact of the
Cloud Radio Access Network (C-RAN) architecture. The analysis follows an
information theoretic approach based on the classical Wyner model. The
analytical results herein confirm the significant potential advantages of the
C-RAN architecture in the presence of full-duplex base stations, as long as
sufficient fronthaul capacity is available and appropriate mobile station
scheduling, or successive interference cancellation at the mobile stations, is
implemented.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-52311405.2192 | Diffusion limit for the radiative transfer equation perturbed by a
Markovian process
math.AP math.PR
We study the stochastic diffusive limit of a kinetic radiative transfer
equation, which is non-linear, involving a small parameter and perturbed by a
smooth random term. Under an appropriate scaling for the small parameter, using
a generalization of the perturbed test-functions method, we show the
convergence in law to a stochastic non-linear fluid limit.
| arxiv topic:math.AP math.PR |
arxiv_dataset-52321405.2292 | Statistical Causality from a Decision-Theoretic Perspective
math.ST stat.ME stat.TH
We present an overview of the decision-theoretic framework of statistical
causality, which is well-suited for formulating and solving problems of
determining the effects of applied causes. The approach is described in detail,
and is related to and contrasted with other current formulations, such as
structural equation models and potential responses. Topics and applications
covered include confounding, the effect of treatment on the treated,
instrumental variables, and dynamic treatment strategies.
| arxiv topic:math.ST stat.ME stat.TH |
arxiv_dataset-52331405.2392 | Amorphous Silicon Nanowires with Low Two-Photon Absorption, High
Nonlinearity and Good Stability
physics.optics
We demonstrate optically stable amorphous silicon nanowires with both high
nonlinear figure of merit (FOM) of ~5 and high nonlinearity Re({\gamma}) =
1200W-1m-1.
| arxiv topic:physics.optics |
arxiv_dataset-52341405.2492 | Unified and Distributed QoS-Driven Cell Association Algorithms in
Heterogeneous Networks
cs.NI cs.IT math.IT
This paper addresses the cell association problem in the downlink of a
multi-tier heterogeneous network (HetNet), where base stations (BSs) have
finite number of resource blocks (RBs) available to distribute among their
associated users. Two problems are defined and treated in this paper: sum
utility of long term rate maximization with long term rate quality of service
(QoS) constraints, and global outage probability minimization with outage QoS
constraints. The first problem is well-suited for low mobility environments,
while the second problem provides a framework to deal with environments with
fast fading. The defined optimization problems in this paper are solved in two
phases: cell association phase followed by the optional RB distribution phase.
We show that the cell association phase of both problems have the same
structure. Based on this similarity, we propose a unified distributed algorithm
with low levels of message passing to for the cell association phase. This
distributed algorithm is derived by relaxing the association constraints and
using Lagrange dual decomposition method. In the RB distribution phase, the
remaining RBs after the cell association phase are distributed among the users.
Simulation results show the superiority of our distributed cell association
scheme compared to schemes that are based on maximum signal to interference
plus noise ratio (SINR).
| arxiv topic:cs.NI cs.IT math.IT |
arxiv_dataset-52351405.2592 | 3-D particle-in-cell simulations for quasi-phase matched direct laser
electron acceleration in density-modulated plasma waveguides
physics.plasm-ph
Quasi-phase matched direct laser acceleration (DLA) of electrons can be
realized with guided, radially polarized laser pulses in density-modulated
plasma waveguides. A 3-D particle-in-cell model has been developed to describe
the interactions among the laser field, injected electrons, and the background
plasma in the DLA process. Simulations have been conducted to study the scheme
in which seed electron bunches with moderate energies are injected into a
plasma waveguide and the DLA is performed by use of relatively low-power (0.5-2
TW) laser pulses. Selected bunch injection delays with respect to the laser
pulse, bunch lengths, and bunch transverse sizes have been studied in a series
of simulations of DLA in a plasma waveguide. The results show that the
injection delay is important for controlling the final transverse properties of
short electron bunches, but it also affects the final energy gain. With a long
injected bunch length, the enhanced ion-focusing force helps to collimate the
electrons and a relatively small final emittance can be obtained. DLA
efficiency is reduced when a bunch with a greater transverse size is injected;
in addition, micro-bunching is clearly observed due to the focusing and
defocusing of electrons by the radially directed Lorentz force. DLA should be
performed with a moderate laser power to maintain favorable bunch transverse
properties, while the waveguide length can be extended to obtain a higher
maximum energy gain, with the commensurate increase of laser pulse duration and
energy.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-52361405.2692 | Exact solution of the spin-s Heisenberg chain with generic non-diagonal
boundaries
cond-mat.stat-mech hep-th math-ph math.MP
The off-diagonal Bethe ansatz method is generalized to the high spin
integrable systems associated with the su(2) algebra by employing the spin-s
isotropic Heisenberg chain model with generic integrable boundaries as an
example. With the fusion techniques, certain closed operator identities for
constructing the functional T-Q relations and the Bethe ansatz equations are
derived. It is found that a variety of inhomogeneous T-Q relations obeying the
operator product identities can be constructed. Numerical results for two-site
s=1 case indicate that an arbitrary choice of the derived T-Q relations is
enough to give the complete spectrum of the transfer matrix.
| arxiv topic:cond-mat.stat-mech hep-th math-ph math.MP |
arxiv_dataset-52371405.2792 | Holographic entanglement entropy and gravitational anomalies
hep-th
We study entanglement entropy in two-dimensional conformal field theories
with a gravitational anomaly. In theories with gravity duals, this anomaly is
holographically represented by a gravitational Chern-Simons term in the bulk
action. We show that the anomaly broadens the Ryu-Takayanagi minimal worldline
into a ribbon, and that the anomalous contribution to the CFT entanglement
entropy is given by the twist in this ribbon. The entanglement functional may
also be interpreted as the worldline action for a spinning particle -- that is,
an anyon -- in three-dimensional curved spacetime. We demonstrate that the
minimization of this action results in the Mathisson-Papapetrou-Dixon equations
of motion for a spinning particle in three dimensions. We work out several
simple examples and demonstrate agreement with CFT calculations.
| arxiv topic:hep-th |
arxiv_dataset-52381405.2892 | New Results on the Minimum Amount of Useful Space
cs.FL cs.CC quant-ph
We present several new results on minimal space requirements to recognize a
nonregular language: (i) realtime nondeterministic Turing machines can
recognize a nonregular unary language within weak $\log\log n$ space, (ii)
$\log\log n$ is a tight space lower bound for accepting general nonregular
languages on weak realtime pushdown automata, (iii) there exist unary
nonregular languages accepted by realtime alternating one-counter automata
within weak $\log n$ space, (iv) there exist nonregular languages accepted by
two-way deterministic pushdown automata within strong $\log\log n$ space, and,
(v) there exist unary nonregular languages accepted by two-way one-counter
automata using quantum and classical states with middle $\log n$ space and
bounded error.
| arxiv topic:cs.FL cs.CC quant-ph |
arxiv_dataset-52391405.2992 | Correlating power consumption and network traffic for improving data
centers resiliency
cs.NI
The deployment of business critical applications and information
infrastructures are moving to the cloud. This means they are hosted in large
scale data centers with other business applications and infrastructures with
less (or none) mission critical constraints. This mixed and complex environment
makes very challenging the process of monitoring critical applications and
handling (detecting and recovering) possible failures of servers' data center
that could affect responsiveness and/or reliability of mission critical
applications. Monitoring mechanisms used in data center are usually intrusive
in the sense that they need to install agents on each single server. This has
considerable drawbacks: huge usage of human resources to install and patch the
system and interference with the critical application because agents share
application resources. In order to detect (and possibly predict) failures in
data centers the paper does a first attempt in showing the correlation between
network traffic and servers' power consumption. This is an important step in
deriving non-intrusive monitoring systems, as both network traffic and power
consumption can be captured without installing any software at the servers.
This will improve in its turn the overall resiliency of the data center and its
self-managing capacity.
| arxiv topic:cs.NI |
arxiv_dataset-52401405.3092 | Thermal Conductivity due to Spinons in the One-Dimensional Quantum Spin
System Sr2V3O9
cond-mat.str-el
We have measured the thermal conductivity along different directions of the S
= 1/2 one-dimensional (1D) spin system Sr2V3O9 in magnetic fields up to 14 T.
It has been found that the thermal conductivity along the [10-1] direction,
\k{appa}[10-1], is large and markedly suppressed by the application of magnetic
field, indicating that there is a large contribution of spinons to
\k{appa}[10-1] and that the spin chains run along the [10-1] direction. The
maximum value of the thermal conductivity due to spinons is ~14 W/Km along the
[10-1] direction, supporting the empirical law that the magnitude of the
thermal conductivity due to spinons is roughly proportional to the
antiferromagnetic interaction between the nearest neighboring spins.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-52411405.3192 | On Self-Predicative Universals in Category Theory
math.GM
1. This paper shows how the universals of category theory in mathematics
provide a model (in the Platonic Heaven of mathematics) for the
self-predicative strand of Plato's Theory of Forms as well as for the idea of a
"concrete universal" in Hegel and similar ideas of paradigmatic exemplars in
ordinary thought. 2. The paper also shows how the always-self-predicative
universals of category theory provide the "opposite bookend" to the
never-self-predicative universals of iterative set theory and thus that the
paradoxes arose from having one theory (e.g., Frege's Paradise) where
universals could be either self-predicative or non-self-predicative (instead of
being always one or the other). 3. Moreover the paper considers one of the most
important examples of self-predicative universals in pure mathematics, namely
adjoint functors or adjunctions. It gives a parsing of adjunctions into two
halves (left and right semi-adjunctions) using the heterodox notion of
heteromorphisms, and then shows that the parts can be recombined in a new way
to define the cognate-to-adjoints notion of a brain functor that provides an
abstract conceptual model of a brain. 4. Finally the paper argues that at least
one way category theory has foundational relevance is that it isolates the
universal concepts and structures that are important throughout mathematics.
| arxiv topic:math.GM |
arxiv_dataset-52421405.3292 | Learning with many experts: model selection and sparsity
stat.ME cs.LG
Experts classifying data are often imprecise. Recently, several models have
been proposed to train classifiers using the noisy labels generated by these
experts. How to choose between these models? In such situations, the true
labels are unavailable. Thus, one cannot perform model selection using the
standard versions of methods such as empirical risk minimization and cross
validation. In order to allow model selection, we present a surrogate loss and
provide theoretical guarantees that assure its consistency. Next, we discuss
how this loss can be used to tune a penalization which introduces sparsity in
the parameters of a traditional class of models. Sparsity provides more
parsimonious models and can avoid overfitting. Nevertheless, it has seldom been
discussed in the context of noisy labels due to the difficulty in model
selection and, therefore, in choosing tuning parameters. We apply these
techniques to several sets of simulated and real data.
| arxiv topic:stat.ME cs.LG |
arxiv_dataset-52431405.3392 | The FRUITY database on AGB stars: past, present and future
astro-ph.SR
We present and show the features of the FRUITY database, an interactive
web-based interface devoted to the nucleosynthesis in AGB stars. We describe
the current available set of AGB models (largely expanded with respect to the
original one) with masses in the range 1.3<=M/M_SUN<=3.0 and metallicities
-2.15<=[Fe/H]<=+0.15. We illustrate the details of our s-process surface
distributions and we compare our results to observations. Moreover, we
introduce a new set of models where the effects of rotation are taken into
account. Finally, we shortly describe next planned upgrades.
| arxiv topic:astro-ph.SR |
arxiv_dataset-52441405.3492 | The birth of spacetime atoms as the passage of time
gr-qc hep-th
The view that the passage of time is physical finds expression in the
classical sequential growth models of Rideout and Sorkin in which a discrete
spacetime grows by the partially ordered accretion of new spacetime atoms.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-52451405.3592 | Revisiting Discrete Dark Matter Model:\theta_{13}\neq0 and \nu_{R} Dark
Matter
hep-ph
We revisit the discrete dark matter model with $A_4$ flavor symmetry
originally introduced by M.Hirsch {\it et.al}. We show that radiative
corrections can lead to non-zero $\theta_{13}$ and non-zero mass for the
lightest neutrino. We find an interesting relation among neutrino mixing
parameters and it indicates the sizable deviation of $s_{23}$ from the maximal
angle $s_{23}^2=1/2$ and the degenerate mass spectrum for neutrinos. Also we
study the possibilities that the right-handed neutrino is a dark matter
candidate. Assuming the thermal freeze-out explains observed dark matter
abundance, TeV-scale right-handed neutrino and flavored scalar bosons are
required. In such a case, flavor symmetry plays an important role for the
suppression of lepton flavor violating processes as well as for the stability
of dark matter. We show that this scenario can be viable against currently
existing constraints from collider, low energy experiments and cosmological
observations.
| arxiv topic:hep-ph |
arxiv_dataset-52461405.3692 | Split Dirac Supersymmetry: An Ultraviolet Completion of Higgsino Dark
Matter
hep-ph
Motivated by the observation that the Higgs quartic coupling runs to zero at
an intermediate scale, we propose a new framework for models of split
supersymmetry, in which gauginos acquire intermediate scale Dirac masses of
$\sim 10^{8-11}$ GeV. Scalar masses arise from one-loop finite contributions as
well as direct gravity-mediated contributions. Like split supersymmetry, one
Higgs doublet is fine-tuned to be light. The scale at which the Dirac gauginos
are introduced to make the Higgs quartic zero is the same as is necessary for
gauge coupling unification. Thus, gauge coupling unification persists
(nontrivially, due to adjoint multiplets), though with a somewhat higher
unification scale $\gtrsim 10^{17}$ GeV. The $\mu$-term is naturally at the
weak scale, and provides an opportunity for experimental verification. We
present two manifestations of Split Dirac Supersymmetry. In the "Pure Dirac"
model, the lightest Higgsino must decay through R-parity violating couplings,
leading to an array of interesting signals in colliders. In the "Hypercharge
Impure" model, the bino acquires a Majorana mass that is one-loop suppressed
compared with the Dirac gluino and wino. This leads to weak scale Higgsino dark
matter whose overall mass scale, as well as the mass splitting between the
neutral components, is naturally generated from the same UV dynamics. We
outline the challenges to discovering pseudo-Dirac Higgsino dark matter in
collider and dark matter detection experiments.
| arxiv topic:hep-ph |
arxiv_dataset-52471405.3792 | Minimum Model Semantics for Extensional Higher-order Logic Programming
with Negation
cs.PL cs.AI cs.LO
Extensional higher-order logic programming has been introduced as a
generalization of classical logic programming. An important characteristic of
this paradigm is that it preserves all the well-known properties of traditional
logic programming. In this paper we consider the semantics of negation in the
context of the new paradigm. Using some recent results from non-monotonic
fixed-point theory, we demonstrate that every higher-order logic program with
negation has a unique minimum infinite-valued model. In this way we obtain the
first purely model-theoretic semantics for negation in extensional higher-order
logic programming. Using our approach, we resolve an old paradox that was
introduced by W. W. Wadge in order to demonstrate the semantic difficulties of
higher-order logic programming.
| arxiv topic:cs.PL cs.AI cs.LO |
arxiv_dataset-52481405.3892 | On-Site and Off-Site Bound States of the Discrete Nonlinear
Schr\"odinger Equation and the Peierls-Nabarro Barrier
nlin.PS cond-mat.mes-hall math-ph math.AP math.MP
We construct multiple families of solitary standing waves of the discrete
cubically nonlinear Schr\"{o}dinger equation (DNLS) in dimensions $d=1,2$ and
$3$. These states are obtained via a bifurcation analysis about the continuum
(NLS) limit. One family consists {\it on-site symmetric} (vertex-centered)
states; these are spatially localized solitary standing waves which are
symmetric about any fixed lattice site. The other spatially localized states
are {\it off-site symmetric}. Depending on the spatial dimension, these may be
bond-centered, cell-centered, or face-centered. Finally, we show that the
energy difference among distinct states of the same frequency is exponentially
small with respect to a natural parameter. This provides a rigorous bound for
the so-called {\it Peierls-Nabarro} energy barrier.
| arxiv topic:nlin.PS cond-mat.mes-hall math-ph math.AP math.MP |
arxiv_dataset-52491405.3992 | Nanoscale phase separation in deep underdoped
Bi$_{2}$Sr$_{2}$CuO$_{6+\delta}$ and Ca$_2$CuO$_2$Cl$_2$
cond-mat.supr-con
We demonstrate that tunneling spectra in deeply underdoped
Bi$_{2}$Sr$_{2}$CuO$_{6+\delta}$ (Bi2201) and Ca$_2$CuO$_2$Cl$_2$ (CCOC)
provide clear evidence for nanoscale phase separation (NPS), causing the gap to
fill with doping rather than close. The phase separation extends over a doping
range from half filling to approximately $x\sim 0.09$. Assuming the NPS is in
the form of stripes, then the nodal gap -- which we model as a Coulomb gap --
arises from impurity pinning of the charged stripes, ultimately driving a
metal-insulator transition.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-52501405.4092 | An ICT-Based Real-Time Surveillance System for Controlling Dengue in Sri
Lanka
cs.CY
Dengue is a notifiable communicable disease in Sri Lanka since 1996. Dengue
fever spread rapidly among people living in most of the districts of Sri Lanka.
The present notification system of dengue communicable diseases which is
enforced by law is a passive surveillance system carried out by the public
health care professionals. The present notification of communicable disease
system is manual, slow, inefficient, and repetitive all of these lead to handle
the dengue related health problems ineffectively. Thus it is less effective in
preventing a spreading epidemic, public health care professionals and others
require an operational support system to help for managing day-to-day public
health responsibilities as well as a method to effectively detect and manage
health problems such as Dengue. On the other hand the Information and
Communication Technology (ICT) in medical world has been widely used. To give
the information technology touch, a complementary web based open source
software application environment has been developed with minimum implementation
and recurrent costs critical for developing countries like Sri Lanka and named
as eDCS: e Dengue Control System based on the same principles of manual disease
surveillance system while taking steps to provide timely, accurate information
in a reliable and useable manner. The eDCS helps to manage outbreaks through
early detection, rapid verification, and appropriate response to Dengue. It
allows health care professionals and citizens to get early awareness about the
dengue disease via Internet or mobile phone and bring them for performing
Dengue prevention and controlling operation through the social media
acceleration. The system is initially limited to dengue communicable disease.
It can be easily expanded to other communicable diseases, and non communicable
disease surveillance in future.
| arxiv topic:cs.CY |
arxiv_dataset-52511405.4192 | Black holes as self-sustained quantum states, and Hawking radiation
hep-th gr-qc
We employ the recently proposed formalism of the "horizon wave-function" to
investigate the emergence of a horizon in models of black holes as
Bose-Einstein condensates of gravitons. We start from the Klein-Gordon equation
for a massless scalar (toy graviton) field coupled to a static matter current.
The (spherically symmetric) classical field reproduces the Newtonian potential
generated by the matter source, and the corresponding quantum state is given by
a coherent superposition of scalar modes with continuous occupation number.
Assuming an attractive self-interaction that allows for bound states, one finds
that (approximately) only one mode is allowed, and the system can be confined
in a region of the size of the Schwarzschild radius. This radius is then shown
to correspond to a proper horizon, by means of the horizon wave-function of the
quantum system, with an uncertainty in size naturally related to the expected
typical energy of Hawking modes. In particular, this uncertainty decreases for
larger black hole mass (with larger number of light scalar quanta), in
agreement with semiclassical expectations, a result which does not hold for a
single very massive particle. We finally speculate that a phase transition
should occur during the gravitational collapse of a star, ideally represented
by a static matter current and Newtonian potential, that leads to a black hole,
again ideally represented by the condensate of toy gravitons, and suggest an
effective order parameter that could be used to investigate this transition.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-52521405.4292 | Limitations of holography
hep-th gr-qc
By studying global AdS using different foliations, global and Rindler-AdS, we
show that there are two different asymptotic Fefferman-Graham expansions
possible and thus two different definitions of "boundaries". We demonstrate
that imposing boundary conditions on the two boundaries is not mutually
compatible even when these boundaries are pushed to infinity. Thus, these two
procedures define two genuinely distinct theories that we call global-CFT and
Rindler-CFT. We show that the Rindler-CFT is not the same as the theory one
gets by "Rindlerizing the global-CFT" as described in hep-th/9804085. We
conjecture that the Rindler theory is incapable of capturing the dynamics
inside the horizon and discuss its implications for the BTZ-CFT duality
proposed in hep-th/0106112.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-52531405.4392 | That's sick dude!: Automatic identification of word sense change across
different timescales
cs.CL cs.AI
In this paper, we propose an unsupervised method to identify noun sense
changes based on rigorous analysis of time-varying text data available in the
form of millions of digitized books. We construct distributional thesauri based
networks from data at different time points and cluster each of them separately
to obtain word-centric sense clusters corresponding to the different time
points. Subsequently, we compare these sense clusters of two different time
points to find if (i) there is birth of a new sense or (ii) if an older sense
has got split into more than one sense or (iii) if a newer sense has been
formed from the joining of older senses or (iv) if a particular sense has died.
We conduct a thorough evaluation of the proposed methodology both manually as
well as through comparison with WordNet. Manual evaluation indicates that the
algorithm could correctly identify 60.4% birth cases from a set of 48 randomly
picked samples and 57% split/join cases from a set of 21 randomly picked
samples. Remarkably, in 44% cases the birth of a novel sense is attested by
WordNet, while in 46% cases and 43% cases split and join are respectively
confirmed by WordNet. Our approach can be applied for lexicography, as well as
for applications like word sense disambiguation or semantic search.
| arxiv topic:cs.CL cs.AI |
arxiv_dataset-52541405.4492 | Recursive families of higher order iterative maps
math.NA
To approximate a simple root of an equation we construct families of
iterative maps of higher order of convergence. These maps are based on model
functions which can be written as an inner product. The main family of maps
discussed is defined recursively and is called {\it Newton-barycentric}. We
illustrate the application of Newton-barycentric maps in two worked examples,
one dealing with a typical least squares problem and the other showing how to
locate simultaneously a great number of extrema of the Ackley's function.
| arxiv topic:math.NA |
arxiv_dataset-52551405.4592 | Fast Adaptive Beamforming based on kernel method under Small Sample
Support
cs.IT math.IT
It is well-known that the high computational complexity and the insufficient
samples in large-scale array signal processing restrict the real-world
applications of the conventional full-dimensional adaptive beamforming (sample
matrix inversion) algorithms. In this paper, we propose a computationally
efficient and fast adaptive beamforming algorithm under small sample support.
The proposed method is implemented by formulating the adaptive weight vector as
a linear combination of training samples plus a signal steering vector, on the
basis of the fact that the adaptive weight vector lies in the
signal-plus-interference subspace. Consequently, by using the well-known linear
kernel methods with very good small-sample performance, only a low-dimension
combination vector needs to be computed instead of the high-dimension adaptive
weight vector itself, which remarkably reduces the degree of freedom and the
computational complexity. Experimental results validate the good performance
and the computational effectiveness of the proposed methods for small samples.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-52561405.4692 | From Science to Management: Using Bayesian Networks to Learn about
Lyngbya
stat.ME q-bio.PE
Toxic blooms of Lyngbya majuscula occur in coastal areas worldwide and have
major ecological, health and economic consequences. The exact causes and
combinations of factors which lead to these blooms are not clearly understood.
Lyngbya experts and stakeholders are a particularly diverse group, including
ecologists, scientists, state and local government representatives, community
organisations, catchment industry groups and local fishermen. An integrated
Bayesian network approach was developed to better understand and model this
complex environmental problem, identify knowledge gaps, prioritise future
research and evaluate management options.
| arxiv topic:stat.ME q-bio.PE |
arxiv_dataset-52571405.4792 | N=2 Heterotic-Type II duality and bundle moduli
hep-th
Heterotic string compactifications on a $K3$ surface $\mathfrak{S}$ depend on
a choice of hyperk\"ahler metric, anti-self-dual gauge connection and
Kalb-Ramond flux, parametrized by hypermultiplet scalars. The metric on
hypermultiplet moduli space is in principle computable within the $(0,2)$
superconformal field theory on the heterotic string worldsheet, although little
is known about it in practice. Using duality with type II strings compactified
on a Calabi-Yau threefold, we predict the form of the quaternion-K\"ahler
metric on hypermultiplet moduli space when $\mathfrak{S}$ is elliptically
fibered, in the limit of a large fiber and even larger base. The result is in
general agreement with expectations from Kaluza-Klein reduction, in particular
the metric has a two-stage fibration structure, where the $B$-field moduli are
fibered over bundle and metric moduli, while bundle moduli are themselves
fibered over metric moduli. A more precise match must await a detailed analysis
of $R^2$-corrected ten-dimensional supergravity.
| arxiv topic:hep-th |
arxiv_dataset-52581405.4892 | Alternative Algorithms for Lyndon Factorization
cs.DS
We present two variations of Duval's algorithm for computing the Lyndon
factorization of a word. The first algorithm is designed for the case of small
alphabets and is able to skip a significant portion of the characters of the
string, for strings containing runs of the smallest character in the alphabet.
Experimental results show that it is faster than Duval's original algorithm,
more than ten times in the case of long DNA strings. The second algorithm
computes, given a run-length encoded string $R$ of length $\rho$, the Lyndon
factorization of $R$ in $O(\rho)$ time and constant space.
| arxiv topic:cs.DS |
arxiv_dataset-52591405.4992 | Femtosecond electrons probing currents and atomic structure in
nanomaterials
cond-mat.mes-hall cond-mat.mtrl-sci
The investigation of ultrafast electronic and structural dynamics in
low-dimensional systems like nanowires and two-dimensional materials requires
femtosecond probes providing high spatial resolution and strong interaction
with small volume samples. Low-energy electrons exhibit large scattering cross
sections and high sensitivity to electric fields, but their pronounced
dispersion during propagation in vacuum so far prevented their use as
femtosecond probe pulses in time-resolved experiments. Employing a
laser-triggered point-like source of either divergent or collimated electron
wave packets, we developed a hybrid approach for femtosecond point projection
microscopy and femtosecond low-energy electron diffraction. We investigate
ultrafast electric currents in nanowires with sub-100 femtosecond temporal and
few 10 nm spatial resolutions and demonstrate the potential of our approach for
studying structural dynamics in crystalline single-layer materials.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-52601405.5092 | Masses and decay constants of the heavy tensor mesons with QCD sum rules
hep-ph
In this article, we calculate the contributions of the vacuum condensates up
to dimension-6 in the operator product expansion, study the masses and decay
constants of the heavy tensor mesons $D_2^*(2460)$, $D_{s2}^*(2573)$,
$B_2^*(5747)$, $B_{s2}^*(5840)$ using the QCD sum rules. The predicted masses
are in excellent agreement with the experimental data, while the ratios of the
decay constants
$\frac{f_{D_{s2}^*}}{f_{D_{2}^*}}\approx\frac{f_{B_{s2}^*}}{f_{B_{2}^*}}\approx\frac{f_{D_{s}}}{f_{D}}\mid_{\rm
exp}$, where the exp denotes the experimental value.
| arxiv topic:hep-ph |
arxiv_dataset-52611405.5192 | Inequalities for generalized normalized $\delta$-Casorati curvatures of
slant submanifolds in quaternionic space forms
math.DG
In this paper we prove two sharp inequalities involving the normalized scalar
curvature and the generalized normalized $\delta$-Casorati curvatures for slant
submanifolds in quaternionic space forms. We also characterize those
submanifolds for which the equality cases hold. These results are a
generalization of some recent results concerning the Casorati curvature for a
slant submanifold in a quaternionic space form obtained by Slesar et al.: J.
Inequal. Appl. 2014, 2014:123.
| arxiv topic:math.DG |
arxiv_dataset-52621405.5292 | Temperature dependence of cross sections for meson-meson nonresonant
reactions in hadronic matter
nucl-th hep-ph
We study unpolarized cross sections for the endothermic nonresonant
reactions: pion pion to rho rho for I=2, KK to K*K* for I=1, KK* to K*K* for
I=1, pion K to rho K* for I=3/2, pion K* to rho K* for I=3/2, rho K to rho K*
for I=3/2, and pion K* to rho K for I=3/2, which take place in hadronic matter.
We provide a potential that is given by perturbative QCD with loop corrections
at short distances, becomes a distance-independent and temperature-dependent
value at long distances, and has a spin-spin interaction with relativistic
modifications. The Schrodinger equation with the potential yields
temperature-dependent meson masses and mesonic quark-antiquark relative-motion
wave functions. In the first Born approximation with the quark-interchange
mechanism, the temperature dependence of the potential, meson masses and wave
functions brings about temperature dependence of unpolarized cross sections for
the seven nonresonant reactions. Noticeably, rapid changes of pion and K radii
cause an increase in peak cross sections while the temperature approaches the
critical temperature. Parametrizations of the numerical cross sections are
given for their future applications in heavy ion collisions.
| arxiv topic:nucl-th hep-ph |
arxiv_dataset-52631405.5392 | Gravitational Lensing Effect on the Hawking Radiation of Dyonic Black
Holes
gr-qc
In this paper, we analyze the Hawking radiation (HR) of a non-asymptotically
flat (NAF) dyonic black hole (dBH) in four-dimensional (4D)
Einstein-Maxwell-Dilaton (EMD) gravity by using one of the semiclassical
approaches which is the so-called Hamilton-Jacobi (HJ) method. We particularly
motivate on the isotropic coordinate system (ICS) of the dBH in order to
highlight the ambiguity to be appeared in the derivation of the Hawking
temperature (T_{H}) via the HJ method. Besides, it will be shown that the ICS
allows us to write the metric of the dBH in form of the Fermat metric, which
renders possible of identification of the refractive index (n) of the dBH. It
is unraveled that the value of n and therefore the gravitational lensing effect
is decisive on the the tunneling rate of the HR. We also uncloak how one can
resolve the discrepancy about the T_{H} of the dBH in spite of that lensing
effect.
| arxiv topic:gr-qc |
arxiv_dataset-52641405.5492 | Stability conditions on $\text{CY}_N$ categories associated to
$A_n$-quivers and period maps
math.RT math.AG math.DS
In this paper, we study the space of stability conditions on a certain
$N$-Calabi-Yau ($\text{CY}_N$) category associated to an $A_n$-quiver.
Recently, Bridgeland and Smith constructed stability conditions on some
$\text{CY}_3$ categories from meromorphic quadratic differentials with simple
zeros. Generalizing their results to higher dimensional Calabi-Yau categories,
we describe the space of stability conditions as the universal cover of the
space of polynomials of degree $n+1$ with simple zeros. In particular, central
charges of stability conditions on $\text{CY}_N$ categories are constructed as
the periods of quadratic differentials with zeros of order $N-2$ which are
associated to polynomials.
| arxiv topic:math.RT math.AG math.DS |
arxiv_dataset-52651405.5592 | Microwave Down-Conversion with an Impedance-Matched $\Lambda$ System in
Driven Circuit QED
quant-ph cond-mat.supr-con physics.atom-ph
By driving a dispersively coupled qubit-resonator system, we realize an
"impedance-matched" $\Lambda$ system that has two identical radiative decay
rates from the top level and interacts with a semi-infinite waveguide. It has
been predicted that a photon input from the waveguide deterministically induces
a Raman transition in the system and switches its electronic state. We confirm
this through microwave response to a continuous probe field, observing
near-perfect ($99.7\%$) extinction of the reflection and highly efficient
($74\%$) frequency down-conversion. These proof-of-principle results lead to
deterministic quantum gates between material qubits and microwave photons and
open the possibility for scalable quantum networks interconnected with
waveguide photons.
| arxiv topic:quant-ph cond-mat.supr-con physics.atom-ph |
arxiv_dataset-52661405.5692 | Thickness and growth-condition dependence of \emph{in-situ} mobility and
carrier density of epitaxial thin-film Bi$_2$Se$_3$
cond-mat.mtrl-sci
Bismuth selenide Bi$_2$Se$_3$ was grown by molecular beam epitaxy while
carrier density and mobility were measured directly \emph{in situ} as a
function of film thickness. Carrier density shows high interface n-doping (1.5
x 10$^{13}$ cm$^{-2}$) at the onset of film conduction, and bulk dopant density
of $\sim$5 x 10$^{18}$ cm$^{-3}$, roughly independent of growth temperature
profile. Mobility depends more strongly on the growth temperature and is
related to the crystalline quality of the samples quantified by \emph{ex-situ}
AFM measurements. These results indicate that Bi$_2$Se$_3$ as prepared by
widely employed parameters is \emph{n}-doped before exposure to atmosphere, the
doping is largely interfacial in origin, and dopants are not the limiting
disorder in present Bi$_2$Se$_3$ films.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-52671405.5792 | Virtual gravitational dipoles: The key for the understanding of the
Universe?
physics.gen-ph
Before the end of this decade, three competing experiments (ALPHA, AEGIS and
GBAR) will discover if atoms of antihydrogen fall up or down. We wonder what
the major changes in astrophysics and cosmology would be if it is
experimentally confirmed that antimatter falls upwards. The key point is: If
antiparticles have negative gravitational charge, the quantum vacuum, well
established in the Standard Model of Particles and Fields, contains virtual
gravitational dipoles. The main conclusions are: (1) the physical vacuum
enriched with gravitational dipoles is compatible with a cyclic universe
alternatively dominated by matter and antimatter, without initial singularity
and without need for cosmic inflation; (2) the virtual dipoles might explain
the phenomena usually attributed to dark matter and dark energy. While what we
have presented is still far from a complete theory, hopefully it can stimulate
a radically different and potentially important way of thinking.
| arxiv topic:physics.gen-ph |
arxiv_dataset-52681405.5892 | Nonlinear POMDPs for Active State Tracking with Sensing Costs
cs.SY math.OC
Active state tracking is needed in object classification, target tracking,
medical diagnosis and estimation of sparse signals among other various
applications. Herein, active state tracking of a discrete-time, finite-state
Markov chain is considered. Noisy Gaussian observations are dynamically
collected by exerting appropriate control over their information content, while
incurring a related sensing cost. The objective is to devise sensing strategies
to optimize the trade-off between tracking performance and sensing cost. A
recently proposed Kalman-like estimator \cite{ZoisTSP14} is employed for state
tracking. The associated mean-squared error and a generic sensing cost metric
are then used in a partially observable Markov decision process formulation,
and the optimal sensing strategy is derived via a dynamic programming
recursion. The resulting recursion proves to be non-linear, challenging control
policy design. Properties of the related cost functions are derived and
sufficient conditions are provided regarding the structure of the optimal
control policy enabling characterization of when passive state tracking is
optimal. To overcome the associated computational burden of the optimal sensing
strategy, two lower complexity strategies are proposed, which exploit the
aforementioned properties. The performance of the proposed strategies is
illustrated in a wireless body sensing application, where cost savings as high
as $60\%$ are demonstrated for a $4\%$ detection error with respect to a static
equal allocation sensing strategy.
| arxiv topic:cs.SY math.OC |
arxiv_dataset-52691405.5992 | Superionicity and Polymorphism in Calcium Fluoride at High Pressure
cond-mat.mtrl-sci
We present a combined experimental and computational first-principles study
of the superionic and structural properties of CaF2 at high P-T conditions. We
observe an anomalous superionic behavior in the low-P fluorite phase that
consists in a decrease of the normal-> superionic critical temperature with
compression. This unexpected effect can be explained in terms of a P-induced
softening of a zone-boundary $X$ phonon which involves exclusively fluorine
displacements. Also we find that superionic conductivity is absent in the
high-P cotunnite phase. Instead, superionicity develops in a new low-symmetry
high-T phase that we identify as monoclinic (space group P2_1/c). We discuss
the possibility of observing these intriguing phenomena in related isomorphic
materials.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-52701405.6092 | A Note on the Rapanui Lunar Calendar
physics.hist-ph
This paper is dedicated to the research of secrets of Easter Island (Rapa
Nui), a remote plot of land in the Pacific; the article contains not only
ethnological data, but also some results on the archaeoastronomy. This author
examines both lunar calendar lists presented on the Mamari tablet as well as on
a panel at Ahu Raai. Calendar records on different tablets have been
investigated, too.
| arxiv topic:physics.hist-ph |
arxiv_dataset-52711405.6192 | Holomorphic Campanato Spaces on the Unit Ball
math.CV
As outlined below, this paper is devoted to a Carleson-type-measure-based
study of the holomorphic Campanato $2$-space on the open unit ball $\mathbb
B_n$ of $\mathbb C^n$, comprising all Hardy $2$-functions whose oscillations in
non-isotropic metric balls on the compact unit sphere $\mathbb S_n$ are
proportional to some power of the radius other than the dimension $n\ge 1$.
| arxiv topic:math.CV |
arxiv_dataset-52721405.6292 | Charge transfer statistics of transport through Majorana bound states
cond-mat.mes-hall
We analyse the full counting statistics of charge transfer through a Majorana
bound state coupled to an STM tip and show how they can be used for an
unambiguous identification of the bound state at the end of the wire.
Additionally, we show how to generate Majorana bound states in a simple setup
involving a ferromagnetic wire on a superconducting substrate.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-52731405.6392 | Parameter estimation of beta-geometric model with application to human
fecundability data
stat.AP
The present study deals with the estimation of the mean value of
fecundability by fitting a theoretical distribution from the observed month of
first conception of the married women who did not use any contraceptive method
before their first conception. It is assumed that fecundability is fixed for a
given couple, but across couples it varies according to a specified
distribution. Under the classical approach, methods of moment and maximum
likelihood are used while for Bayesian approach we use the above two estimates
as prior for fecundability parameter. A real data analysis from the third
National Family Health Survey (NFHS-III) is analyzed as an application of
model. Finally, a simulation study is performed to access the performance of
the several of methods used in this paper
| arxiv topic:stat.AP |
arxiv_dataset-52741405.6492 | Reviving quark nuggets as a candidate for dark matter
hep-ph astro-ph.CO hep-th nucl-th
We discuss a novel mechanism for segregation of baryons and anti-baryons in
the quark-gluon plasma phase which can lead to formation of quark and antiquark
nuggets in the early universe, irrespective of the order of the quark-hadron
phase transition. This happens due to CP violating scattering of quarks and
antiquarks from moving $Z(3)$ domain walls. CP violation here is spontaneous in
nature and arises from the nontrivial profile of the background gauge field
($A_{0}$ ) between different $Z(3)$ vacua. We study the effect of this
spontaneous CP violation on the baryon transport across the collapsing large
$Z(3)$ domain walls (which can arise in the context of certain low energy scale
inflationary models). Our results show that this CP violation can lead to large
concentrations of baryons and anti-baryons in the early universe. The quark and
antiquark nuggets, formed by this alternate mechanism, can provide a viable
dark matter candidate within standard model without violating any observational
constraints.
| arxiv topic:hep-ph astro-ph.CO hep-th nucl-th |
arxiv_dataset-52751405.6592 | Primes in short arithmetic progressions
math.NT
Let $x,h$ and $Q$ be three parameters. We show that, for most moduli $q\le Q$
and for most positive real numbers $y\le x$, every reduced arithmetic
progression $a\mod q$ has approximately the expected number of primes $p$ from
the interval $(y,y+h]$, provided that $h>x^{1/6+\epsilon}$ and $Q$ satisfies
appropriate bounds in terms of $h$ and $x$. Moreover, we prove that, for most
moduli $q\le Q$ and for most positive real numbers $y\le x$, there is at least
one prime $p\in(y,y+h]$ lying in every reduced arithmetic progression $a\mod
q$, provided that $1\le Q^2\le h/x^{1/15+\epsilon}$.
| arxiv topic:math.NT |
arxiv_dataset-52761405.6692 | Infinite Dimensional Stochastic Differential Equations for Dyson's Model
math.PR
In this paper we show the strong existence and the pathwise uniqueness of an
infinite-dimensional Stochastic Differential Equation (SDE) corresponding to
the bulk limit of Dyson's Brownian Motion (DBM), for all $\beta\geq 1$. Our
construction applies to an explicit and general class of initial conditions,
including the lattice configuration $\{x_i\}=\mathbb{Z}$ and the sine process.
We further show the convergence of the finite to infinite-dimensional SDE. This
convergence concludes the determinantal formula of Katori and Tanemura (2010)
for the solution of this SDE at $\beta=2$.
| arxiv topic:math.PR |
arxiv_dataset-52771405.6792 | Discussion: "A significance test for the lasso"
math.ST stat.TH
Discussion of "A significance test for the lasso" by Richard Lockhart,
Jonathan Taylor, Ryan J. Tibshirani, Robert Tibshirani [arXiv:1301.7161].
| arxiv topic:math.ST stat.TH |
arxiv_dataset-52781405.6892 | Concept of effective states of atoms in compounds to describe properties
determined by the densities of valence electrons in atomic cores
physics.chem-ph physics.atom-ph
A new approach for describing the effective electronic states of "atoms in
compounds" to study the properties of molecules and condensed matter which are
circumscribed by the operators heavily concentrated in atomic cores is
proposed. Among the properties are hyperfine structure, space parity (P) and
time reversal invariance (T) nonconservation effects, chemical shifts of x-ray
emission lines (XES), M\"{o}ssbauer effect, etc. Advantage of the approach is
that a good quantitative agreement of predicted and experimental data can be
attained even for such difficult cases as XES chemical shifts providing correct
quantum-mechanical interpretation of the experimental data. From computational
point of view the method can be quite efficient being implemented in the
framework of the relativistic pseudopotential theory [Int.J. Quantum Chem. 71,
359 (1999)] and procedures of recovering the wave functions in heavy-atom cores
[Int.J. Quantum Chem. 104, 223 (2005)] after a molecular, cluster or periodic
structure calculation performed on the basis of pseudoorbitals smoothed near
the nuclei within the pseudopotential approximation. We report results of our
studies of a number of atomic and molecular systems to demonstrate the
capabilities of the approach.
| arxiv topic:physics.chem-ph physics.atom-ph |
arxiv_dataset-52791405.6992 | AGT relations for abelian quiver gauge theories on ALE spaces
math.RT hep-th math-ph math.AG math.MP
We construct level one dominant representations of the affine Kac-Moody
algebra $\widehat{\mathfrak{gl}}_k$ on the equivariant cohomology groups of
moduli spaces of rank one framed sheaves on the orbifold compactification of
the minimal resolution $X_k$ of the $A_{k-1}$ toric singularity
$\mathbb{C}^2/\mathbb{Z}_k$. We show that the direct sum of the fundamental
classes of these moduli spaces is a Whittaker vector for
$\widehat{\mathfrak{gl}}_k$, which proves the AGT correspondence for pure
$\mathcal{N}=2$ $U(1)$ gauge theory on $X_k$. We consider Carlsson-Okounkov
type Ext-bundles over products of the moduli spaces and use their Euler classes
to define vertex operators. Under the decomposition
$\widehat{\mathfrak{gl}}_k\simeq \mathfrak{h}\oplus \widehat{\mathfrak{sl}}_k$,
these vertex operators decompose as products of bosonic exponentials associated
to the Heisenberg algebra $\mathfrak{h}$ and primary fields of
$\widehat{\mathfrak{sl}}_k$. We use these operators to prove the AGT
correspondence for $\mathcal{N}=2$ superconformal abelian quiver gauge theories
on $X_k$.
| arxiv topic:math.RT hep-th math-ph math.AG math.MP |
arxiv_dataset-52801405.7092 | Clique-width of Graph Classes Defined by Two Forbidden Induced Subgraphs
cs.DM math.CO
If a graph has no induced subgraph isomorphic to any graph in a finite family
$\{H_1,\ldots,H_p\}$, it is said to be $(H_1,\ldots,H_p)$-free. The class of
$H$-free graphs has bounded clique-width if and only if $H$ is an induced
subgraph of the 4-vertex path $P_4$. We study the (un)boundedness of the
clique-width of graph classes defined by two forbidden induced subgraphs $H_1$
and $H_2$. Prior to our study it was not known whether the number of open cases
was finite. We provide a positive answer to this question. To reduce the number
of open cases we determine new graph classes of bounded clique-width and new
graph classes of unbounded clique-width. For obtaining the latter results we
first present a new, generic construction for graph classes of unbounded
clique-width. Our results settle the boundedness or unboundedness of the
clique-width of the class of $(H_1,H_2)$-free graphs (i) for all pairs
$(H_1,H_2)$, both of which are connected, except two non-equivalent cases, and
(ii) for all pairs $(H_1,H_2)$, at least one of which is not connected, except
11 non-equivalent cases.
We also consider classes characterized by forbidding a finite family of
graphs $\{H_1,\ldots,H_p\}$ as subgraphs, minors and topological minors,
respectively, and completely determine which of these classes have bounded
clique-width. Finally, we show algorithmic consequences of our results for the
graph colour
| arxiv topic:cs.DM math.CO |
arxiv_dataset-52811405.7192 | The PeerRank Method for Peer Assessment
cs.AI cs.DS
We propose the PeerRank method for peer assessment. This constructs a grade
for an agent based on the grades proposed by the agents evaluating the agent.
Since the grade of an agent is a measure of their ability to grade correctly,
the PeerRank method weights grades by the grades of the grading agent. The
PeerRank method also provides an incentive for agents to grade correctly. As
the grades of an agent depend on the grades of the grading agents, and as these
grades themselves depend on the grades of other agents, we define the PeerRank
method by a fixed point equation similar to the PageRank method for ranking
web-pages. We identify some formal properties of the PeerRank method (for
example, it satisfies axioms of unanimity, no dummy, no discrimination and
symmetry), discuss some examples, compare with related work and evaluate the
performance on some synthetic data. Our results show considerable promise,
reducing the error in grade predictions by a factor of 2 or more in many cases
over the natural baseline of averaging peer grades.
| arxiv topic:cs.AI cs.DS |
arxiv_dataset-52821405.7292 | An Easy to Use Repository for Comparing and Improving Machine Learning
Algorithm Usage
stat.ML cs.LG
The results from most machine learning experiments are used for a specific
purpose and then discarded. This results in a significant loss of information
and requires rerunning experiments to compare learning algorithms. This also
requires implementation of another algorithm for comparison, that may not
always be correctly implemented. By storing the results from previous
experiments, machine learning algorithms can be compared easily and the
knowledge gained from them can be used to improve their performance. The
purpose of this work is to provide easy access to previous experimental results
for learning and comparison. These stored results are comprehensive -- storing
the prediction for each test instance as well as the learning algorithm,
hyperparameters, and training set that were used. Previous results are
particularly important for meta-learning, which, in a broad sense, is the
process of learning from previous machine learning results such that the
learning process is improved. While other experiment databases do exist, one of
our focuses is on easy access to the data. We provide meta-learning data sets
that are ready to be downloaded for meta-learning experiments. In addition,
queries to the underlying database can be made if specific information is
desired. We also differ from previous experiment databases in that our
databases is designed at the instance level, where an instance is an example in
a data set. We store the predictions of a learning algorithm trained on a
specific training set for each instance in the test set. Data set level
information can then be obtained by aggregating the results from the instances.
The instance level information can be used for many tasks such as determining
the diversity of a classifier or algorithmically determining the optimal subset
of training instances for a learning algorithm.
| arxiv topic:stat.ML cs.LG |
arxiv_dataset-52831405.7392 | Information-Theoretic Stochastic Optimal Control via Incremental
Sampling-based Algorithms
cs.RO cs.SY
This paper considers optimal control of dynamical systems which are
represented by nonlinear stochastic differential equations. It is well-known
that the optimal control policy for this problem can be obtained as a function
of a value function that satisfies a nonlinear partial differential equation,
namely, the Hamilton-Jacobi-Bellman equation. This nonlinear PDE must be solved
backwards in time, and this computation is intractable for large scale systems.
Under certain assumptions, and after applying a logarithmic transformation, an
alternative characterization of the optimal policy can be given in terms of a
path integral. Path Integral (PI) based control methods have recently been
shown to provide elegant solutions to a broad class of stochastic optimal
control problems. One of the implementation challenges with this formalism is
the computation of the expectation of a cost functional over the trajectories
of the unforced dynamics. Computing such expectation over trajectories that are
sampled uniformly may induce numerical instabilities due to the exponentiation
of the cost. Therefore, sampling of low-cost trajectories is essential for the
practical implementation of PI-based methods. In this paper, we use incremental
sampling-based algorithms to sample useful trajectories from the unforced
system dynamics, and make a novel connection between Rapidly-exploring Random
Trees (RRTs) and information-theoretic stochastic optimal control. We show the
results from the numerical implementation of the proposed approach to several
examples.
| arxiv topic:cs.RO cs.SY |
arxiv_dataset-52841405.7492 | Star-forming regions of the Aquila rift cloud complex. II. Turbulence in
molecular cores probed by NH3 emission
astro-ph.GA
(Abridged) Aims. We intend to derive statistical properties of stochastic gas
motion inside the dense low mass star forming molecular cores traced by
NH3(1,1) and (2,2) emission lines. Methods. We use the spatial two-point
autocorrelation (ACF) and structure functions calculated from maps of the
radial velocity fields. Results. We find oscillating ACFs which eventually
decay to zero with increasing lags on scales of 0.04 <= l <= 0.5 pc. The
current paradigm supposes that the star formation process is controlled by the
interplay between gravitation and turbulence, the latter preventing molecular
cores from a rapid collapse due to their own gravity. Thus, oscillating ACFs
may indicate a damping of the developed turbulent flows surrounding the dense
but less turbulent core - a transition to dominating gravitational forces and,
hence, to gravitational collapse.
| arxiv topic:astro-ph.GA |
arxiv_dataset-52851405.7592 | Critical fermion density for restoring spontaneously broken symmetry
physics.gen-ph
We show how the phenomenon of spontaneous symmetry breakdown is affected by
the presence of a sea of fermions in the system. When its density exceeds a
critical value, the broken symmetry can be restored. We calculate the critical
value and discuss the consequences for three different physical systems: First,
for the standard model of particle physics, where the spontaneous symmetry
breakdown leads nonzero masses of intermediate gauge bosons and fermions. The
symmetry restoration will greatly enhance various processes with dramatic
consequences for the early universe. Second, for the Gell-Mann--L\`evy
$\sigma$-model of nuclear physics, where the symmetry breakdown gives rise to
the nucleon and meson masses. The symmetry restoration may have important
consequences for formation or collapse of stellar cores. Third, for the
superconductive phase of condensed-matter, where the BCS condensate at
low-temperature may be destroyed by a too large electron density.
| arxiv topic:physics.gen-ph |
arxiv_dataset-52861405.7692 | The protoplanetary disk of FT Tauri: multi-wavelength data analysis and
modeling
astro-ph.SR astro-ph.EP
Investigating the evolution of protoplanetary disks is crucial for our
understanding of star and planet formation. Several theoretical and
observational studies have been performed in the last decades to advance this
knowledge. FT Tauri is a young star in the Taurus star forming region that was
included in a number of spectroscopic and photometric surveys. We investigate
the properties of the star, the circumstellar disk, and the accretion and
ejection processes and propose a consistent gas and dust model also as a
reference for future observational studies. We performed a multi-wavelength
data analysis to derive the basic stellar and disk properties, as well as mass
accretion/outflow rate from TNG-Dolores, WHT-Liris, NOT-Notcam, Keck-Nirspec,
and Herschel-Pacs spectra. From the literature, we compiled a complete Spectral
Energy Distribution. We then performed detailed disk modeling using the MCFOST
and ProDiMo codes. Multi-wavelengths spectroscopic and photometric measurements
were compared with the reddened predictions of the codes in order to constrain
the disk properties. This object can serve as a benchmark for primordial disks
with significant mass accretion rate, high gas content and typical size.
| arxiv topic:astro-ph.SR astro-ph.EP |
arxiv_dataset-52871405.7792 | Special lines on contact manifolds
math.AG
In a series of two articles Kebekus studied deformation theory of minimal
rational curves on contact Fano manifolds. Such curves are called contact
lines. Kebekus proved that a contact line through a general point is
necessarily smooth and has a fixed standard splitting type of the restricted
tangent bundle. In this paper we study singular contact lines and those with
special splitting type. We provide restrictions on the families of such lines,
and on contact Fano manifolds which have reducible varieties of minimal
rational tangents. We also show that the results about singular lines naturally
generalise to complex contact manifolds, which are not necessarily Fano, for
instance, quasi-projective contact manifolds or compact contact manifolds of
Fujiki class C. In particular, in many cases the dimension of a family of
singular lines is at most 2 less than the dimension of the contact manifold.
| arxiv topic:math.AG |
arxiv_dataset-52881405.7892 | Interactions of aqueous amino acids and proteins with the (110) surface
of ZnS in molecular dynamics simulations
q-bio.BM
The growing usage of nanoparticles of zinc sulfide as quantum dots and
biosensors calls for a theoretical assessment of interactions of ZnS with
biomolecules. We employ the molecular-dynamics-based umbrella sampling method
to determine potentials of mean force for 20 single amino acids near the ZnS
(110) surface in aqueous solutions. We find that five amino acids do not bind
at all and the binding energy of the remaining amino acids does not exceed 4.3
kJ/mol. Such energies are comparable to those found for ZnO (and to hydrogen
bonds in proteins) but the nature of the specificity is different. Cysteine can
bind with ZnS in a covalent way, e.g. by forming the disulfide bond with S in
the solid. If this effect is included within a model incorporating the Morse
potential, then the potential well becomes much deeper - the binding energy is
close to 98 kJ/mol. We then consider tryptophan cage, a protein of 20 residues,
and characterize its events of adsorption to ZnS. We demonstrate the relevance
of interactions between the amino acids in the selection of optimal adsorbed
conformations and recognize the key role of cysteine in generation of lasting
adsorption. We show that ZnS is more hydrophobic than ZnO and that the density
profile of water is quite different than that forming near ZnO - it has only a
minor articulation into layers. Furthermore, the first layer of water is
disordered and mobile.
| arxiv topic:q-bio.BM |
arxiv_dataset-52891406.0017 | Biclique coverings, rectifier networks and the cost of
$\varepsilon$-removal
cs.FL cs.DM
We relate two complexity notions of bipartite graphs: the minimal weight
biclique covering number $\mathrm{Cov}(G)$ and the minimal rectifier network
size $\mathrm{Rect}(G)$ of a bipartite graph $G$. We show that there exist
graphs with $\mathrm{Cov}(G)\geq \mathrm{Rect}(G)^{3/2-\epsilon}$. As a
corollary, we establish that there exist nondeterministic finite automata
(NFAs) with $\varepsilon$-transitions, having $n$ transitions total such that
the smallest equivalent $\varepsilon$-free NFA has $\Omega(n^{3/2-\epsilon})$
transitions. We also formulate a version of previous bounds for the weighted
set cover problem and discuss its connections to giving upper bounds for the
possible blow-up.
| arxiv topic:cs.FL cs.DM |
arxiv_dataset-52901406.0117 | EACOF: A Framework for Providing Energy Transparency to enable
Energy-Aware Software Development
cs.SE
Making energy consumption data accessible to software developers is an
essential step towards energy efficient software engineering. The presence of
various different, bespoke and incompatible, methods of instrumentation to
obtain energy readings is currently limiting the widespread use of energy data
in software development. This paper presents EACOF, a modular Energy-Aware
Computing Framework that provides a layer of abstraction between sources of
energy data and the applications that exploit them. EACOF replaces platform
specific instrumentation through two APIs - one accepts input to the framework
while the other provides access to application software. This allows developers
to profile their code for energy consumption in an easy and portable manner
using simple API calls. We outline the design of our framework and provide
details of the API functionality. In a use case, where we investigate the
impact of data bit width on the energy consumption of various sorting
algorithms, we demonstrate that the data obtained using EACOF provides
interesting, sometimes counter-intuitive, insights. All the code is available
online under an open source license. http://github.com/eacof
| arxiv topic:cs.SE |
arxiv_dataset-52911406.0217 | The most parsimonious tree for random data
q-bio.PE
Applying a method to reconstruct a phylogenetic tree from random data
provides a way to detect whether that method has an inherent bias towards
certain tree `shapes'. For maximum parsimony, applied to a sequence of random
2-state data, each possible binary phylogenetic tree has exactly the same
distribution for its parsimony score. Despite this pleasing and slightly
surprising symmetry, some binary phylogenetic trees are more likely than others
to be a most parsimonious (MP) tree for a sequence of $k$ such characters, as
we show. For $k=2$, and unrooted binary trees on six taxa, any tree with a
caterpillar shape has a higher chance of being an MP tree than any tree with a
symmetric shape. On the other hand, if we take any two binary trees, on any
number of taxa, we prove that this bias between the two trees vanishes as the
number of characters grows. However, again there is a twist: MP trees on six
taxa are more likely to have certain shapes than a uniform distribution on
binary phylogenetic trees predicts, and this difference does not appear to
dissipate as $k$ grows.
| arxiv topic:q-bio.PE |
arxiv_dataset-52921406.0317 | A lower bound for the number of negative eigenvalues of Schr\"{o}dinger
operators
math.DG
We prove a lower bound for the number of negative eigenvalues for a
Schr\"{o}dinger operator on a Riemannian manifold via the integral of the
potential.
| arxiv topic:math.DG |
arxiv_dataset-52931406.0417 | Equilibrium configuration of perfect fluid orbiting around black holes
in some classes of alternative gravity theories
gr-qc astro-ph.CO
The hydrodynamic behaviour of perfect fluid orbiting around black holes in
spherically symmetric spacetime for various alternative gravity theories has
been investigated. For this purpose we have assumed an uniform distribution for
the angular momentum density of the rotating perfect fluid. The contours of
equipotential surfaces are illustrated in order to obtain the nature of inflow
and outflow of matters. It has been noticed that, the marginally stable
circular orbits originating from decreasing angular momentum density lead to
closed equipotential surfaces along with cusp allowing existence of accretion
disks. On the other hand, the growing part of angular momentum density exhibits
central rings for which stable configurations are possible. However inflow of
matter is prohibited. Among the solutions discussed in this work, the charged
$F(R)$ gravity and Einstein-Maxwell-Gauss-Bonnet solution exhibit inflow and
outflow of matter with central rings present. These varied accretion disk
structure of perfect fluid attribute these spacetimes astrophysical importance.
The effect of higher curvature terms predominantly arises from region near the
black hole horizon. Hence the structural difference of accretion disk in
modified gravity theories with comparison to general relativity may act as an
experimental probe for these alternative gravity theories.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-52941406.0517 | Electroweak Baryogenesis, Electric Dipole Moments, and Higgs Diphoton
Decays
hep-ph
We study the viability of electroweak baryogenesis in a two Higgs doublet
model scenario augmented by vector-like, electroweakly interacting fermions.
Considering a limited, but illustrative region of the model parameter space, we
obtain the observed cosmic baryon asymmetry while satisfying present
constraints from the non-observation of the permanent electric dipole moment
(EDM) of the electron and the combined ATLAS and CMS result for the Higgs boson
diphoton decay rate. The observation of a non-zero electron EDM in a next
generation experiment and/or the observation of an excess (over the Standard
Model) of Higgs to diphoton events with the 14 TeV LHC run or a future $e^+e^-$
collider would be consistent with generation of the observed baryon asymmetry
in this scenario.
| arxiv topic:hep-ph |
arxiv_dataset-52951406.0617 | A minimal model for two-component dark matter
hep-ph
We propose and study a new minimal model for two-component dark matter. The
model contains only three additional fields, one fermion and two scalars, all
singlets under the Standard Model gauge group. Two of these fields, one fermion
and one scalar, are odd under a $Z_2$ symmetry that renders them simultaneously
stable. Thus, both particles contribute to the observed dark matter density.
This model resembles the union of the singlet scalar and the singlet fermionic
models but it contains some new features of its own. We analyze in some detail
its dark matter phenomenology. Regarding the relic density, the main novelty is
the possible annihilation of one dark matter particle into the other, which can
affect the predicted relic density in a significant way. Regarding dark matter
detection, we identify a new contribution that can lead either to an
enhancement or to a suppression of the spin-independent cross section for the
scalar dark matter particle. Finally, we define a set of five benchmarks models
compatible with all present bounds and examine their direct detection prospects
at planned experiments. A generic feature of this model is that both particles
give rise to observable signals in 1-ton direct detection experiments. In fact,
such experiments will be able to probe even a subdominant dark matter component
at the percent level.
| arxiv topic:hep-ph |
arxiv_dataset-52961406.0717 | Fractional Variational Principle of Herglotz
math.OC
The aim of this paper is to bring together two approaches to non-conservative
systems -- the generalized variational principle of Herglotz and the fractional
calculus of variations. Namely, we consider functionals whose extrema are
sought, by differential equations that involve Caputo fractional derivatives.
The Euler--Lagrange equations are obtained for the fractional variational
problems of Herglotz-type and the transversality conditions are derived. The
fractional Noether-type theorem for conservative and non-conservative physical
systems is proved.
| arxiv topic:math.OC |
arxiv_dataset-52971406.0817 | On the existence of a minimal generating set for $\sigma$-algebras
math.FA
Does there exist for any $\sigma$-algebra a minimal (with respect to
inclusion) generating set? We formulate this problem and answer it in the very
special instance of partition generated and standard measurable spaces, the
general case remaining open.
| arxiv topic:math.FA |
arxiv_dataset-52981406.0917 | Self-adjoint Dirac type Hamiltonians in one space dimension with a mass
jump
quant-ph math-ph math.MP
Physical self-adjoint extensions and their spectra of the one-dimensional
Dirac type Hamiltonian operator in which both the mass and velocity are
constant except for a finite jump at one point of the real axis are correctly
found. Different boundary conditions on envelope wave functions are studied,
and the limiting case of equal masses (with no mass jump) is reviewed.
Transport across one-dimensional heterostructures described by the Dirac
equation is considered.
| arxiv topic:quant-ph math-ph math.MP |
arxiv_dataset-52991406.1017 | Rotation in an exact hydro model
hep-ph
We study an exact and extended solution of the fluid dynamical model of heavy
ion reactions, and estimate the rate of slowing down of the rotation due to the
longitudinal and transverse expansion of the system. The initial state
parameters of the model are set on the basis of a realistic 3+1D fluid
dynamical calculation at TeV energies, where the rotation is enhanced by the
build up of the Kelvin Helmholtz Instability in the flow.
| arxiv topic:hep-ph |
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