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arxiv_dataset-83001703.06496 | A Graph-Based Approach to Analyze Flux-Balanced Pathways in Metabolic
Networks
q-bio.MN
An Elementary Flux Mode (EFM) is a pathway with minimum set of reactions that
are functional in steady-state constrained space. Due to the high computational
complexity of calculating EFMs, different approaches have been proposed to find
these flux-balanced pathways. In this paper, an approach to find a subset of
EFMs is proposed based on a graph data model. The given metabolic network is
mapped to the graph model and decisions for reaction inclusion can be made
based on metabolites and their associated reactions. This notion makes the
approach more convenient to categorize the output pathways. Implications of the
proposed method on metabolic networks are discussed.
| arxiv topic:q-bio.MN |
arxiv_dataset-83011703.06596 | Full-Duplex Cooperative Cognitive Radio Networks with Wireless Energy
Harvesting
cs.IT math.IT
This paper proposes and analyzes a new full-duplex (FD) cooperative cognitive
radio network with wireless energy harvesting (EH). We consider that the
secondary receiver is equipped with a FD radio and acts as a FD hybrid access
point (HAP), which aims to collect information from its associated EH secondary
transmitter (ST) and relay the signals. The ST is assumed to be equipped with
an EH unit and a rechargeable battery such that it can harvest and accumulate
energy from radio frequency (RF) signals transmitted by the primary transmitter
(PT) and the HAP. We develop a novel cooperative spectrum sharing (CSS)
protocol for the considered system. In the proposed protocol, thanks to its FD
capability, the HAP can receive the PT's signals and transmit energy-bearing
signals to charge the ST simultaneously, or forward the PT's signals and
receive the ST's signals at the same time. We derive analytical expressions for
the achievable throughput of both primary and secondary links by characterizing
the dynamic charging/discharging behaviors of the ST battery as a finite-state
Markov chain. We present numerical results to validate our theoretical analysis
and demonstrate the merits of the proposed protocol over its non-cooperative
counterpart.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-83021703.06696 | Scaling from gauge and scalar radiation in Abelian Higgs string networks
astro-ph.CO hep-th
We investigate cosmic string networks in the Abelian Higgs model using data
from a campaign of large-scale numerical simulations on lattices of up to
$4096^3$ grid points. We observe scaling or self-similarity of the networks
over a wide range of scales, and estimate the asymptotic values of the mean
string separation in horizon length units $\dot{\xi}$ and of the mean square
string velocity $\bar v^2$ in the continuum and large time limits. The scaling
occurs because the strings lose energy into classical radiation of the scalar
and gauge fields of the Abelian Higgs model. We quantify the energy loss with a
dimensionless radiative efficiency parameter, and show that it does not vary
significantly with lattice spacing or string separation. This implies that the
radiative energy loss underlying the scaling behaviour is not a lattice
artefact, and justifies the extrapolation of measured network properties to
large times for computations of cosmological perturbations. We also show that
the core growth method, which increases the defect core width with time to
extend the dynamic range of simulations, does not introduce significant
systematic error. We compare $\dot{\xi}$ and $\bar v^2$ to values measured in
simulations using the Nambu-Goto approximation, finding that the latter
underestimate the mean string separation by about 25%, and overestimate $\bar
v^2$ by about 10%. The scaling of the string separation implies that string
loops decay by the emission of massive radiation within a Hubble time in field
theory simulations, in contrast to the Nambu-Goto scenario which neglects this
energy loss mechanism. String loops surviving for only one Hubble time emit
much less gravitational radiation than in the Nambu-Goto scenario, and are
consequently subject to much weaker gravitational wave constraints on their
tension.
| arxiv topic:astro-ph.CO hep-th |
arxiv_dataset-83031703.06796 | Underground tests of quantum mechanics. Whispers in the cosmic silence?
quant-ph physics.ins-det
By performing X-rays measurements in the "cosmic silence" of the underground
laboratory of Gran Sasso, LNGS-INFN, we test a basic principle of quantum
mechanics: the Pauli Exclusion Principle (PEP), for electrons. We present the
achieved results of the VIP experiment and the ongoing VIP2 measurement aiming
to gain two orders of magnitude improvement in testing PEP. We also use a
similar experimental technique to search for radiation (X and gamma) predicted
by continuous spontaneous localization models, which aim to solve the
"measurement problem".
| arxiv topic:quant-ph physics.ins-det |
arxiv_dataset-83041703.06896 | Modeling chiral criticality
hep-ph
We discuss the critical properties of net-baryon-number fluctuations at the
chiral restoration transition in matter at nonzero temperature and net-baryon
density. The chiral dynamics of quantum chromodynamics (QCD) is modeled by the
Polykov-loop extended Quark-Meson Lagrangian, that includes the coupling of
quarks to temporal gauge fields. The Functional Renormalization Group is
employed to account for the criticality at the phase boundary. We focus on the
ratios of the net-baryon-number cumulants, $\chi_B^n$, for $1\leq n\leq 4$. The
results are confronted with recent experimental data on fluctuations of the
net-proton number in nucleus-nucleus collisions.
| arxiv topic:hep-ph |
arxiv_dataset-83051703.06996 | Modeling Bloch Oscillations in Nanoscale Josephson Junctions
cond-mat.mes-hall cond-mat.supr-con
Bloch oscillations in nanoscale Josephson junctions with a Coulomb charging
energy comparable to the Josephson coupling energy are explored within the
context of a model previously considered by Geigenm\"uller and Sch\"on that
includes Zener tunneling and treats quasiparticle tunneling as an explicit
shot-noise process. The dynamics of the junction quasicharge are investigated
numerically using both Monte Carlo and ensemble approaches to calculate
voltage--current characteristics in the presence of microwaves. We examine in
detail the origin of harmonic and subharmonic Bloch steps at dc biases
$I=(n/m)2ef$ induced by microwaves of frequency $f$ and consider the optimum
parameters for the observation of harmonic ($m=1$) steps. We also demonstrate
that the GS model allows a detailed semi-quantitative fit to experimental
voltage--current characteristics previously obtained at the Chalmers University
of Technology, confirming and strengthening the interpretation of the observed
microwave-induced steps in terms of Bloch oscillations.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-83061703.07096 | Observation of individual spin quantum transitions of a single
antiproton
physics.atom-ph
We report on the detection of individual spin quantum transitions of a single
trapped antiproton in a Penning trap. The spin-state determination, which is
based on the unambiguous detection of axial frequency shifts in presence of a
strong magnetic bottle, reaches a fidelity of 92.1$\%$. Spin-state
initialization with $>99.9\%$ fidelity and an average initialization time of 24
min are demonstrated. This is a major step towards an antiproton magnetic
moment measurement with a relative uncertainty on the part-per-billion level.
| arxiv topic:physics.atom-ph |
arxiv_dataset-83071703.07196 | Virtual refinements of the Vafa-Witten formula
math.AG hep-th math.DG
We conjecture a formula for the generating function of virtual
$\chi_y$-genera of moduli spaces of rank 2 sheaves on arbitrary surfaces with
holomorphic 2-form. Specializing the conjecture to minimal surfaces of general
type and to virtual Euler characteristics, we recover (part of) a formula of C.
Vafa and E. Witten.
These virtual $\chi_y$-genera can be written in terms of descendent Donaldson
invariants. Using T. Mochizuki's formula, the latter can be expressed in terms
of Seiberg-Witten invariants and certain explicit integrals over Hilbert
schemes of points. These integrals are governed by seven universal functions,
which are determined by their values on $\mathbb{P}^2$ and $\mathbb{P}^1 \times
\mathbb{P}^1$. Using localization we calculate these functions up to some
order, which allows us to check our conjecture in many cases.
In an appendix by H. Nakajima and the first named author, the virtual Euler
characteristic specialization of our conjecture is extended to include
$\mu$-classes, thereby interpolating between Vafa-Witten's formula and Witten's
conjecture for Donaldson invariants.
| arxiv topic:math.AG hep-th math.DG |
arxiv_dataset-83081703.07296 | Tuning InP self-assembled quantum structures to telecom wavelength: a
versatile original InP(As) nanostructure "workshop"
cond-mat.mes-hall
The influence of hydride exposure on previously unreported self-assembled
InP(As) nanostructures is investigated, showing an unexpected morphological
variability with growth parameters, and producing a large family of InP(As)
nanostructures by metalorganic vapour phase epitaxy, from dome and ring-like
structures to double dot in a ring ensembles. Moreover, preliminary
microphotoluminescence data are indicating the capped rings system as an
interesting candidate for single quantum emitters at telecom wavelengths,
potentially becoming a possible alternative to InAs QDs for quantum technology
and telecom applications.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-83091703.07396 | The Overview Chapter in Loop Quantum Gravity: The First 30 Years
gr-qc astro-ph.CO hep-th
This is the introductory Chapter in the monograph Loop Quantum Gravity: The
First 30 Years, edited by the authors, that was just published in the series
"100 Years of General Relativity. The 8 invited Chapters that follow provide
fresh perspectives on the current status of the field from some of the younger
and most active leaders who are currently shaping its development. The purpose
of this Chapter is to provide a global overview by bridging the material
covered in subsequent Chapters. The goal and scope of the monograph is
described in the Preface which can be read by following the Front Matter link
at the website listed below.
| arxiv topic:gr-qc astro-ph.CO hep-th |
arxiv_dataset-83101703.07496 | Extremal theory for long range dependent infinitely divisible processes
math.PR
We prove limit theorems of an entirely new type for certain long memory
regularly varying stationary infinitely divisible random processes. These
theorems involve multiple phase transitions governed by how long the memory is.
Apart from one regime, our results exhibit limits that are not among the
classical extreme value distributions. Restricted to the one-dimensional case,
the distributions we obtain interpolate, in the appropriate parameter range,
the $\alpha$-Fr\'echet distribution and the skewed $\alpha$-stable
distribution. In general, the limit is a new family of stationary and
self-similar random sup-measures with parameters $\alpha\in(0,\infty)$ and
$\beta\in(0,1)$, with representations based on intersections of independent
$\beta$-stable regenerative sets. The tail of the limit random sup-measure on
each interval with finite positive length is regularly varying with index
$-\alpha$. The intriguing structure of these random sup-measures is due to
intersections of independent $\beta$-stable regenerative sets and the fact that
the number of such sets intersecting simultaneously increases to infinity as
$\beta$ increases to one. The results in this paper extend substantially
previous investigations where only $\alpha\in(0,2)$ and $\beta\in(0,1/2)$ have
been considered.
| arxiv topic:math.PR |
arxiv_dataset-83111703.07596 | Testing and Learning on Distributions with Symmetric Noise Invariance
stat.ML
Kernel embeddings of distributions and the Maximum Mean Discrepancy (MMD),
the resulting distance between distributions, are useful tools for fully
nonparametric two-sample testing and learning on distributions. However, it is
rarely that all possible differences between samples are of interest --
discovered differences can be due to different types of measurement noise, data
collection artefacts or other irrelevant sources of variability. We propose
distances between distributions which encode invariance to additive symmetric
noise, aimed at testing whether the assumed true underlying processes differ.
Moreover, we construct invariant features of distributions, leading to learning
algorithms robust to the impairment of the input distributions with symmetric
additive noise.
| arxiv topic:stat.ML |
arxiv_dataset-83121703.07696 | Anisotropic plasmons, excitons and electron energy loss spectroscopy of
phosphorene
cond-mat.mes-hall cond-mat.mtrl-sci
In this article, we explore the anisotropic electron energy loss spectrum
(EELS) in monolayer phosphorene based on ab-initio time dependent density
functional theory calculations. Similar to black phosphorous, the EELS of
undoped monolayer phosphorene is characterized by anisotropic excitonic peaks
for energies in vicinity of the bandgap, and by interband plasmon peaks for
higher energies. On doping, an additional intraband plasmon peak also appears
for energies within the bandgap. Similar to other two dimensional systems, the
intraband plasmon peak disperses as $\omega_{\rm pl} \propto \sqrt{q}$ in both
the zigzag and armchair directions in the long wavelength limit, and deviates
for larger wavevectors. The anisotropy of the long wavelength plasmon intraband
dispersion is found to be inversely proportional to the square root of the
ratio of the effective masses: $\omega_{\rm pl}(q \hat{y})/\omega_{\rm pl}(q
\hat{x}) = \sqrt{m_x/m_y}$.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-83131703.07796 | Gauge covariances and nonlinear optical responses
cond-mat.other
The formalism of the reduced density matrix is pursued in both length and
velocity gauges of the perturbation to the crystal Hamiltonian. The covariant
derivative is introduced as a convenient representation of the position
operator. This allow us to write compact expressions for the reduced density
matrix in any order of the perturbation which simplifies the calculations of
nonlinear optical responses; as an example, we compute the first and third
order contributions of the monolayer graphene. Expressions obtained in both
gauges share the same formal structure, allowing a comparison of the effects of
truncation to a finite set of bands. This truncation breaks the equivalence
between the two approaches: its proper implementation can be done directly in
the expressions derived in the length gauge, but require a revision of the
equations of motion of the reduced density matrix in the velocity gauge.
| arxiv topic:cond-mat.other |
arxiv_dataset-83141703.07896 | Lipschitz-free spaces over compact subsets of superreflexive spaces are
weakly sequentially complete
math.FA
Let $M$ be a compact subset of a superreflexive Banach space. We prove that
the Lipschitz-free space $\mathcal{F}(M)$, the predual of the Banach space of
Lipschitz functions on $M$, has the Pe{\l}czy\'nski's property ($V^\ast$). As a
consequence, the Lipschitz-free space $\mathcal{F}(M)$ is weakly sequentially
complete.
| arxiv topic:math.FA |
arxiv_dataset-83151703.07996 | Quantification of avoidable yield losses in oilseed Brassica caused by
insect pests
q-bio.PE
A six year field study was conducted from 2001 2002 to 2006 2007 at Punjab
Agricultural University, Ludhiana, India to study the losses in seed yield of
different Brassica species (B. juncea, B. napus, B. carinata, B. rapa and Eruca
sativa) by the infestation of insect pests. The experiment was conducted in two
different sets viz. protected/sprayed and unprotected, in a randomized block
design, with three replications. Data on the infestation of insect pests, and
seed yield were recorded at weekly intervals and at harvest, respectively. The
loss in seed yield, due to mustard aphid and cabbage caterpillar, varied from
6.5 to 26.4 per cent. E. sativa suffered the least loss in seed yield and
harboured the minimum population of mustard aphid (2.1 aphids/plant) and
cabbage caterpillar (2.4 larvae/plant). On the other hand, B. carinata was
highly susceptible to the cabbage caterpillar (26.2 larvae/plant) and suffered
the maximum yield loss (26.4%).
| arxiv topic:q-bio.PE |
arxiv_dataset-83161703.08096 | Mass content of UGC 6446 and UGC 7524 through HI rotation curves:
deriving the stellar discs from stellar population synthesis models
astro-ph.GA
In this work we study the mass distribution of two irregular galaxies, UGC
6446 and UGC 7524, by means of HI rotation curves derived from high resolution
HI velocity fields obtained through the Westerbork Synthesis Radio Telescope
data archive. We constrain the stellar and gas content of both galaxies with
stellar population synthesis models and by deriving the HI+He+metals rotation
curves from the total HI surface density maps, respectively. The discrepancy
between the circular velocity maxima of the stellar plus the HI+He+metals
rotation curves and the observed HI rotation curves of both galaxies requires
the inclusion of a substantial amount of dark matter. We explore the Navarro
Frenk and White, Burkert, Di Cintio, Einasto and Stadel dark matter halo
models. We obtain acceptable fits to the observed HI rotation curves of UGC
6446 and UGC 7524 with the cored Burkert, Einasto and Stadel dark matter halos.
In particular, Einasto and Stadel models prove to be an appropriate alternative
to the Burkert dark matter halo. This result should increase the empirical
basis that justify the usage of dark matter exponential models to adjust the
observed rotation curves of real galaxies.
| arxiv topic:astro-ph.GA |
arxiv_dataset-83171703.08196 | Mott Transition and Magnetism in Rare Earth Nickelates and its
Fingerprint on the X-ray Scattering
cond-mat.str-el
The metal-insulator transition (MIT) remains among the most thoroughly
studied phenomena in solid state physics, but the complexity of the phenomena,
which usually involves cooperation of many degrees of freedom including
orbitals, fluctuating local moments, magnetism, and the crystal structure, have
resisted predictive ab-initio treatment. Here we develop ab-initio theoretical
method for correlated electron materials, based on Dynamical Mean Field Theory,
which can predict the change of the crystal structure across the MIT at finite
temperature. This allows us to study the coupling between electronic, magnetic
and orbital degrees of freedom with the crystal structure across the MIT in
rare-earth nickelates. We predict the free energy profile of the competing
states, and the theoretical magnetic ground state configuration, which is in
agreement with neutron scattering data, but is different from the magnetic
models proposed before. The resonant elastic X-ray response at the K-edge,
which was argued to be a direct probe of the charge order, is theoretically
modelled within the Dynamical Mean Field Theory, including the core-hole
interaction. We show that the line-shape of the measured resonant elastic X-ray
response can be explained with the "site-selective" Mott scenario without real
charge order on Ni sites.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-83181703.08296 | Synchronization of Chaos
nlin.CD
Dynamical networks are important models for the behaviour of complex systems,
modelling physical, biological and societal systems, including the brain, food
webs, epidemic disease in populations, power grids and many other. Such
dynamical networks can exhibit behaviour in which deterministic chaos,
exhibiting unpredictability and disorder, coexists with synchronization, a
classical paradigm of order. We survey the main theory behind complete,
generalized and phase synchronization phenomena in simple as well as complex
networks and discuss applications to secure communications, parameter
estimation and the anticipation of chaos.
| arxiv topic:nlin.CD |
arxiv_dataset-83191703.08396 | The Universality of Thermal Transport in Amorphous Nanowires at Low
Temperatures
cond-mat.mes-hall
Thermal transport properties of amorphous materials at low temperatures are
governed by the interaction between phonons and localized excitations referred
to as tunneling two level systems (TLS). The temperature variation of the
thermal conductivity of these amorphous materials is considered as universal
and is characterized by a quadratic power law. This is well described by the
phenomenological TLS model even though its microscopic explanation is still
elusive. Here, by scaling down to the nanometer scale amorphous systems much
below the bulk phonon-TLS mean free path, we probed the robustness of that
model in restricted geometry systems. Using very sensitive thermal conductance
measurements, we demonstrate that the temperature dependence of the thermal
conductance of silicon nitride nanostructures remains mostly quadratic
independently of the nanowire section. It is not following the cubic power law
in temperature as expected in a Casimir-Ziman regime of boundary limited
thermal transport. This shows a thermal transport counter intuitively dominated
by phonon-TLS interactions and not by phonon-boundary scattering in the
nanowires. This could be ascribed to an unexpected high density of TLS on the
surfaces which still dominates the phonon diffusion processes at low
temperatures and explains why the universal quadratic temperature dependence of
thermal conductance still holds for amorphous nanowires.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-83201703.08496 | Phase retrieval of an electron vortex beam using diffraction holography
physics.optics
In both light optics and electron optics, the amplitude of a wave scattered
by an object is an observable that is usually recorded in the form of an
intensity distribution in a real space image or a diffraction image. In
contrast, retrieval of the phase of a scattered wave is a well-known challenge,
which is usually approached by interferometric or numerical methods. In
electron microscopy, as a result of constraints in the lens setup, it is
particularly difficult to retrieve the phase of a diffraction image. Here, we
use a defocused beam generated by a nanofabricated hologram to form a reference
wave that can be interfered with a diffracted beam. This setup provides an
extended interference region with the sample wavefunction in the Fraunhofer
plane. As a case study, we retrieve the phase of an electron vortex beam.
Beyond this specific example, the approach can be used to retrieve the
wavefronts of diffracted beams from a wide range of samples.
| arxiv topic:physics.optics |
arxiv_dataset-83211703.08596 | The Inner Structure of Time-Dependent Signals
stat.ME cs.SD math.ST stat.TH
This paper shows how a time series of measurements of an evolving system can
be processed to create an inner time series that is unaffected by any
instantaneous invertible, possibly nonlinear transformation of the
measurements. An inner time series contains information that does not depend on
the nature of the sensors, which the observer chose to monitor the system.
Instead, it encodes information that is intrinsic to the evolution of the
observed system. Because of its sensor-independence, an inner time series may
produce fewer false negatives when it is used to detect events in the presence
of sensor drift. Furthermore, if the observed physical system is comprised of
non-interacting subsystems, its inner time series is separable; i.e., it
consists of a collection of time series, each one being the inner time series
of an isolated subsystem. Because of this property, an inner time series can be
used to detect a specific behavior of one of the independent subsystems without
using blind source separation to disentangle that subsystem from the others.
The method is illustrated by applying it to: 1) an analytic example; 2) the
audio waveform of one speaker; 3) video images from a moving camera; 4)
mixtures of audio waveforms of two speakers.
| arxiv topic:stat.ME cs.SD math.ST stat.TH |
arxiv_dataset-83221703.08696 | Prediction in logarithmic distance
math.PR
The metric properties of the set in which random variables take their values
lead to relevant probabilistic concepts. For example, the mean of a random
variable is a best predictor in that it minimizes the standard Euclidean
distance or $L_2$ norm in an appropriate class of random variables. Similarly,
the median is the same concept but when the distance is measured by the $L_1$
norm. These two predictors stem from the fact that the mean and the median,
minimize the distance to a given set of points when distances in $\mathbb{R}$
or in $\mathbb{R}^n$ are measured in the aforementioned metrics.\\ It so
happens that an interesting {\it logarithmic distance} can be defined on the
cone of strictly positive vectors in $\mathbb{R}^n$ in such a way that the
minimizer of the distance to a collection of points is their geometric mean.\\
This distance on the base space leads to an interesting distance on the class
of strictly positive random variables, which in turn leads to an interesting
class of best predictors predictors and their estimators, as well as a
corresponding notion of conditional expectation. The appropriate version of the
Law of Large Numbers and the Central Limit Theorem, can also be obtained. We
shall see that, for example, the lognormal variables are the analogue of the
Gaussian variables for the modified version of the Central Limit Theorem.
| arxiv topic:math.PR |
arxiv_dataset-83231703.08796 | Ancient multiple-layer solutions to the Allen-Cahn equation
math.AP
We consider the parabolic one-dimensional Allen-Cahn equation $$u_t= u_{xx}+
u(1-u^2)\quad (x,t)\in \mathbb{R}\times (-\infty, 0].$$ The steady state $w(x)
=\tanh (x/\sqrt{2})$, connects, as a "transition layer" the stable phases $-1$
and $+1$. We construct a solution $u$ with any given number $k$ of transition
layers between $-1$ and $+1$. At main order they consist of $k$ time-traveling
copies of $w$ with interfaces diverging one to each other as $t\to -\infty$.
More precisely, we find $$ u(x,t) \approx \sum_{j=1}^k (-1)^{j-1}w(x-\xi_j(t))
+ \frac 12 ((-1)^{k-1}- 1)\quad \hbox{as} t\to -\infty, $$ where the functions
$\xi_j(t)$ satisfy a first order Toda-type system. They are given by
$$\xi_j(t)=\frac{1}{\sqrt{2}}\left(j-\frac{k+1}{2}\right)\log(-t)+\gamma_{jk},\quad
j=1,...,k,$$ for certain explicit constants $\gamma_{jk}.$
| arxiv topic:math.AP |
arxiv_dataset-83241703.08896 | Distributed Adaptive Gradient Optimization Algorithm
math.OC
In this paper, a distributed optimization problem with general differentiable
convex objective functions is studied for single-integrator and
double-integrator multi-agent systems. Two distributed adaptive optimization
algorithm is introduced which uses the relative information to construct the
gain of the interaction term. The analysis is performed based on the Lyapunov
functions, the analysis of the system solution and the convexity of the local
objective functions. It is shown that if the gradients of the convex objective
functions are continuous, the team convex objective function can be minimized
as time evolves for both single-integrator and double-integrator multi-agent
systems. Numerical examples are included to show the obtained theoretical
results.
| arxiv topic:math.OC |
arxiv_dataset-83251703.08996 | Confirming the oblique rotator model for the extremely slowly rotating
O8f?p star HD 108
astro-ph.SR
The O8f?p star HD 108 is implied to have experienced the most extreme
rotational braking of any magnetic, massive star, with a rotational period
$P_{\rm rot}$ of at least 55 years, but the upper limit on its spindown
timescale is over twice the age estimated from the Hertzsprung-Russell diagram.
HD 108's observed X-ray luminosity is also much higher than predicted by the
XADM model, a unique discrepancy amongst magnetic O-type stars. Previously
reported magnetic data cover only a small fraction ($\sim$3.5\%) of $P_{\rm
rot}$, and were furthermore acquired when the star was in a photometric and
spectroscopic `low state' at which the longitudinal magnetic field $\langle
B_z\rangle$~was likely at a minimum. We have obtained a new ESPaDOnS magnetic
measurement of HD 108, 6 years after the last reported measurement. The star is
returning to a spectroscopic high state, although its emission lines are still
below their maximum observed strength, consistent with the proposed 55-year
period. We measured $\langle B_z\rangle=-325 \pm 45$ G, twice the strength of
the 2007-2009 observations, raising the lower limit of the dipole surface
magnetic field strength to $B_{\rm d} \ge 1$ kG. The simultaneous increase in
$\langle B_z\rangle$~and emission strength is consistent with the oblique
rotator model. Extrapolation of the $\langle B_z\rangle$~maximum via comparison
of HD 108's spectroscopic and magnetic data with the similar Of?p star HD
191612 suggests that $B_{\rm d} > 2$~kG, yielding $t_{\rm S, max}<3$~Myr,
compatible with the stellar age. These results also yield a better agreement
between the observed X-ray luminosity and that predicted by the XADM model.
| arxiv topic:astro-ph.SR |
arxiv_dataset-83261703.09096 | Jacobi-Davidson method on low-rank matrix manifolds
math.NA
In this work we generalize the Jacobi-Davidson method to the case when
eigenvector can be reshaped into a low-rank matrix. In this setting the
proposed method inherits advantages of the original Jacobi-Davidson method, has
lower complexity and requires less storage. We also introduce low-rank version
of the Rayleigh quotient iteration which naturally arises in the
Jacobi-Davidson method.
| arxiv topic:math.NA |
arxiv_dataset-83271703.09196 | Pattern Recognition on Oriented Matroids: Decompositions of Topes, and
Orthogonality Relations
math.CO
If V(R) is the vertex set of a symmetric cycle R in the tope graph of a
simple oriented matroid M, then for any tope T of M there exists a unique
inclusion-minimal subset Q(T,R) of V(R) such that T is the sum of the topes of
Q(T,R).
If for decompositions Q(T',R') and Q(T",R") with respect to symmetric cycles
R' and R" in the tope graphs of two simple oriented matroids, whose ground sets
have the cardinalities of opposite parity, we have |Q(T',R')|>3 and
|Q(T",R")|>3, then these decompositions satisfy a certain orthogonality
relation.
| arxiv topic:math.CO |
arxiv_dataset-83281703.09296 | Femoral ROIs and Entropy for Texture-based Detection of Osteoarthritis
from High-Resolution Knee Radiographs
cs.CV
The relationship between knee osteoarthritis progression and changes in
tibial bone structure has long been recognized and various texture descriptors
have been proposed to detect early osteoarthritis (OA) from radiographs. This
work aims to investigate (1) femoral textures as an OA indicator and (2) the
potential of entropy as a computationally efficient alternative to established
texture descriptors.
We design a robust semi-automatically placed layout for regions of interest
(ROI), compute the Hurst coefficient and the entropy in each ROI, and employ
statistical and machine learning methods to evaluate feature combinations.
Based on 153 high-resolution radiographs, our results identify medial femur
as an effective univariate descriptor, with significance comparable to medial
tibia. Entropy is shown to contribute to classification performance. A linear
five-feature classifier combining femur, entropic and standard texture
descriptors, achieves AUC of 0.85, outperforming the state-of-the-art by
roughly 0.1.
| arxiv topic:cs.CV |
arxiv_dataset-83291703.09396 | Luneburg-lens-like structural Pauli attractive core of nuclear force at
short distances
nucl-th hep-ph nucl-ex
The nuclear force has been understood to have a repulsive core at short
distances, similar to a molecular force, since Jastrow proposed it in 1951. The
existence of the repulsion was experimentally confirmed from the proton-proton
scattering 1S_0 phase shift, which becomes negative beyond 230 MeV. This
repulsion is essential for preventing the nucleon-nucleon system from
collapsing by attraction. The origin of the repulsion has been considered to be
due to the Pauli principle, similar to the repulsion originally revealed in
alpha-alpha scattering, in many studies including recent lattice QCD
calculations. On the other hand, very recently it was shown that an
inter-nuclear potential including alpha-alpha interactions has a
Luneburg-lens-like attraction at short distances rather than repulsion. We show
that the nuclear force with an attractive potential at short distances that
reproduces the experimental phase shifts well has a Luneburg-lens-like
structural Pauli attractive core (SPAC) at short distances and acts as apparent
repulsion. The apparent repulsion is caused by the deeply embedded unobservable
Pauli forbidden state similar to nucleus-nucleus potentials.
| arxiv topic:nucl-th hep-ph nucl-ex |
arxiv_dataset-83301703.09496 | Event-by-event charge separation in Pb-Pb collisions at $\sqrt{s_{\rm
NN}}$ = 2.76 TeV with ALICE at the LHC
hep-ex nucl-ex
Relativistic heavy-ion collisions provide a unique opportunity to search for
parity violation in non-central collisions. This could lead to charge
separation perpendicular to the reaction plane. An event-by-event measurement
of charge separation effect in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76
TeV using Sliding Dumbbell Method (SDM) is discussed in this article.
| arxiv topic:hep-ex nucl-ex |
arxiv_dataset-83311703.09596 | Active Particle Condensation by Nonreciprocal and Time-delayed
Interactions
cond-mat.soft
We consider flocking of self-propelling agents in two dimensions, each of
which communicates with its neighbors within a limited vision cone. Also, the
communication occurs with some delay. The communication among the agents are
modeled by Vicsek rules. In this study we explore the effect of non-reciprocal
interaction among the agents, induced by their vision cone, together with the
delayed interactions on the dynamical pattern formation within the flock. We
find that under these two influences and without any position based attractive
interactions or confining boundaries, the agents can spontaneously condense
into drops. Though the agents are in motion within the drop, the drop as whole
is virtually pinned in space. We also find that this novel state of the flock
has a well defined order stabilized by the noise present in the system.
| arxiv topic:cond-mat.soft |
arxiv_dataset-83321703.09696 | Reversing the irreversible: from limit cycles to emergent time symmetry
gr-qc astro-ph.CO nlin.AO physics.class-ph
In 1979 Penrose hypothesized that the arrows of time are explained by the
hypothesis that the fundamental laws are time irreversible. That is, our
reversible laws, such as the standard model and general relativity are
effective, and emerge from an underlying fundamental theory which is time
irreversible. In Cort\^{e}s and Smolin (2014a, 2014b, 2016) we put forward a
research program aiming at realizing just this. The aim is to find a
fundamental description of physics above the planck scale, based on
irreversible laws, from which will emerge the apparently reversible dynamics we
observe on intermediate scales. Here we continue that program and note that a
class of discrete dynamical systems are known to exhibit this very property:
they have an underlying discrete irreversible evolution, but in the long term
exhibit the properties of a time reversible system, in the form of limit
cycles. We connect this to our original model proposal in Cort\^{e}s and Smolin
(2014a), and show that the behaviours obtained there can be explained in terms
of the same phenomenon: the attraction of the system to a basin of limit
cycles, where the dynamics appears to be time reversible. Further than that, we
show that our original models exhibit the very same feature: the emergence of
quasi-particle excitations obtained in the earlier work in the space-time
description is an expression of the system's convergence to limit cycles when
seen in the causal set description.
| arxiv topic:gr-qc astro-ph.CO nlin.AO physics.class-ph |
arxiv_dataset-83331703.09796 | Saxion Cosmology for Thermalized Gravitino Dark Matter
hep-ph astro-ph.CO
In all supersymmetric theories, gravitinos, with mass suppressed by the
Planck scale, are an obvious candidate for dark matter; but if gravitinos ever
reached thermal equilibrium, such dark matter is apparently either too abundant
or too hot, and is excluded. However, in theories with an axion, a saxion
condensate is generated during an early era of cosmological history and its
late decay dilutes dark matter. We show that such dilution allows previously
thermalized gravitinos to account for the observed dark matter over very wide
ranges of gravitino mass, keV < $m_{3/2}$ < TeV, axion decay constant, $10^9$
GeV < $f_a$ < $10^{16}$ GeV, and saxion mass, 10 MeV < $m_s$ < 100 TeV.
Constraints on this parameter space are studied from BBN, supersymmetry
breaking, gravitino and axino production from freeze-in and saxion decay, and
from axion production from both misalignment and parametric resonance
mechanisms. Large allowed regions of $(m_{3/2}, f_a, m_s)$ remain, but differ
for DFSZ and KSVZ theories. Superpartner production at colliders may lead to
events with displaced vertices and kinks, and may contain saxions decaying to
$(WW,ZZ,hh), gg, \gamma \gamma$ or a pair of Standard Model fermions. Freeze-in
may lead to a sub-dominant warm component of gravitino dark matter, and saxion
decay to axions may lead to dark radiation.
| arxiv topic:hep-ph astro-ph.CO |
arxiv_dataset-83341703.09896 | On generalized Toeplitz and little Hankel operators on Bergman spaces
math.FA
We find a concrete integral formula for the class of generalized Toeplitz
operators $T_a$ in Bergman spaces $A^p$, $1<p<\infty$, studied in an earlier
work by the authors. The result is extended to little Hankel operators. We give
an example of an $L^2$-symbol $a$ such that $T_{|a|} $ fails to be bounded in
$A^2$, although $T_a : A^2 \to A^2$ is seen to be bounded by using the
generalized definition. We also confirm that the generalized definition
coincides with the classical one whenever the latter makes sense.
| arxiv topic:math.FA |
arxiv_dataset-83351703.09996 | On Non-BPS Effective Actions of String Theory
hep-th gr-qc hep-ph
We discuss some physical prospective of the non-BPS effective actions of type
IIA and IIB superstring theories. By dealing with the complete all three and
four point functions, including a closed string Ramond-Ramond (in terms of both
its field strength and its potential), gauge (scalar) fields as well as a real
tachyon and under symmetry structures, we find various restricted world volume
and bulk Bianchi identities. The complete forms of the non-BPS scattering
amplitudes including their Chan-Paton factors are elaborated. All the
singularity structures of the non-BPS amplitudes, their all orders $\alpha'$
higher derivative corrections, their contact terms and various modified Bianchi
identities are derived. Finally we show that scattering amplitudes computed in
different super-ghost pictures are compatible when suitable Bianchi identities
are imposed on the Ramond-Ramond fields. Moreover, we argue that the higher
derivative expansion in powers of the momenta of the tachyon is universal.
| arxiv topic:hep-th gr-qc hep-ph |
arxiv_dataset-83361703.10096 | Redundancy of einselected information in quantum Darwinism: The
irrelevance of irrelevant environment bits
quant-ph
The objective, classical world emerges from the underlying quantum substrate
via the proliferation of redundant copies of selected information into the
environment, which acts as a communication channel, transmitting that
information to observers. These copies are independently accessible, allowing
many observers to reach consensus about the state of a quantum system via its
imprints in the environment. Quantum Darwinism recognizes that the redundancy
of information is thus central to the emergence of objective reality in the
quantum world. However, in addition to the "quantum system of interest," there
are many other systems "of no interest" in the Universe that can imprint
information on the common environment. There is therefore a danger that the
information of interest will be diluted with irrelevant bits, suppressing the
redundancy responsible for objectivity. We show that mixing of the relevant
(the "wheat") and irrelevant (the "chaff") bits of information makes little
quantitative difference to the redundancy of the information of interest. Thus,
we demonstrate that it does not matter whether one separates the relevant
information) from the (irrelevant) chaff: The large redundancy of the relevant
information survives dilution, providing evidence of the objective, effectively
classical world.
| arxiv topic:quant-ph |
arxiv_dataset-83371703.10196 | Detecting Human Interventions on the Landscape: KAZE Features, Poisson
Point Processes, and a Construction Dataset
cs.CV
We present an algorithm capable of identifying a wide variety of
human-induced change on the surface of the planet by analyzing matches between
local features in time-sequenced remote sensing imagery. We evaluate feature
sets, match protocols, and the statistical modeling of feature matches. With
application of KAZE features, k-nearest-neighbor descriptor matching, and
geometric proximity and bi-directional match consistency checks, average match
rates increase more than two-fold over the previous standard. In testing our
platform, we developed a small, labeled benchmark dataset expressing
large-scale residential, industrial, and civic construction, along with null
instances, in California between the years 2010 and 2012. On the benchmark set,
our algorithm makes precise, accurate change proposals on two-thirds of scenes.
Further, the detection threshold can be tuned so that all or almost all
proposed detections are true positives.
| arxiv topic:cs.CV |
arxiv_dataset-83381703.10296 | The XXL Survey XVIII. ATCA 2.1 GHz radio source catalogue and source
counts for the XXL-South field
astro-ph.GA
The 2.1 GHz radio source catalogue of the 25 deg$^2$ ultimate XMM
extragalactic survey south (XXL-S) field, observed with the Australia Telescope
Compact Array (ATCA), is presented. The final radio mosaic achieved a
resolution of $\sim$$4.8"$ and a median rms noise of $\sigma \approx41$
$\mu$Jy/beam. To date, this is the largest area radio survey to reach this flux
density level. A total of 6350 radio components above 5$\sigma$ are included in
the component catalogue, 26.4% of which are resolved. Of these components, 111
were merged together to create 48 multiple-component radio sources, resulting
in a total of 6287 radio sources in the source catalogue, 25.9% of which were
resolved. A survival analysis revealed that the median spectral index of the
Sydney University Molonglo Sky Survey (SUMSS) 843 MHz sources in the field is
$\alpha$ = $-$0.75, consistent with the values of $-0.7$ to $-0.8$ commonly
used to characterise radio spectral energy distributions of active galactic
nuclei (AGN). The 2.1 GHz and 1.4 GHz differential radio source counts are
presented and compared to other 1.4 GHz radio surveys. The XXL-S source counts
show good agreement with the other surveys.
| arxiv topic:astro-ph.GA |
arxiv_dataset-83391703.10396 | Mobility tensor of a sphere moving on a super-hydrophobic wall:
application to particle separation
physics.flu-dyn
The paper addresses the hydrodynamic behavior of a sphere close to a
micro-patterned superhydrophobic surface described in terms of alternated
no-slip and perfect-slip stripes. Physically, the perfect-slip stripes model
the parallel grooves where a large gas cushion forms between fluid and solid
wall, giving rise to slippage at the gas-liquid interface. The potential of the
boundary element method (BEM) in dealing with mixed no-slip/perfect-slip
boundary conditions is exploited to systematically calculate the mobility
tensor for different particle-to-wall relative positions and for different
particle radii. The particle hydrodynamics is characterized by a non trivial
mobility field which presents a distinct near wall behavior where the wall
patterning directly affects the particle motion. In the far field, the effects
of the wall pattern can be accurately represented via an effective description
in terms of a homogeneous wall with a suitably defined apparent slippage. The
trajectory of the sphere under the action of an external force is also
described in some detail. A resonant regime is found when the frequency of the
transversal component of the force matches a characteristic crossing frequency
imposed by the wall pattern. It is found that, under resonance, the particle
undergoes a mean transversal drift. Since the resonance condition depends on
the particle radius the effect can in principle be used to conceive devices for
particle sorting based on superhydrophobic surfaces.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-83401703.10496 | Progress Report on an Ultra-compact LumiCal
physics.ins-det
A new design of a detector module of submillimeter thickness for an
electromagnetic calorimeter is presented. It is aimed to be used in the
luminometers LumiCal and BeamCal in future linear e$^{+}$e$^{-}$ collider
experiments. The module prototypes were produced utilizing novel connectivity
schemes technologies. They are installed in a compact prototype of the
calorimeter and tested at DESY with an electron beam of 1 GeV $-$ 6 GeV. The
performance of eight detector modules and the possibility of electron and
photon identification is studied.
| arxiv topic:physics.ins-det |
arxiv_dataset-83411703.10596 | The Reversibility Error Method (REM): a new, dynamical fast indicator
for planetary dynamics
astro-ph.EP
We describe the Reversibility Error Method (REM) and its applications to
planetary dynamics. REM is based on the time-reversibility analysis of the
phase-space trajectories of conservative Hamiltonian systems. The round-off
errors break the time reversibility and the displacement from the initial
condition, occurring when we integrate it forward and backward for the same
time interval, is related to the dynamical character of the trajectory. If the
motion is chaotic, in the sense of non-zero maximal Characteristic Lyapunov
Exponent (mLCE), then REM increases exponentially with time, as exp \lambda t,
while when the motion is regular (quasi-periodic) then REM increases as a power
law in time, as t^{\alpha}, where {\alpha} and {\lambda} are real coefficients.
We compare the REM with a variant of mLCE, the Mean Exponential Growth factor
of Nearby Orbits (MEGNO). The test set includes the restricted three body
problem and five resonant planetary systems: HD 37124, Kepler-60, Kepler-36,
Kepler-29 and Kepler-26. We found a very good agreement between the outcomes of
these algorithms. Moreover, the numerical implementation of REM is astonishing
simple, and is based on solid theoretical background. The REM requires only a
symplectic and time-reversible (symmetric) integrator of the equations of
motion. This method is also CPU efficient. It may be particularly useful for
the dynamical analysis of multiple planetary systems in the KEPLER sample,
characterized by low-eccentricity orbits and relatively weak mutual
interactions. As an interesting side-result, we found a possible stable chaos
occurrence in the Kepler-29 planetary system.
| arxiv topic:astro-ph.EP |
arxiv_dataset-83421703.10696 | Higher Morse moduli spaces and n-categories
math.CT math.DG math.DS
We generalize Cohen & Jones & Segal's flow category whose objects are the
critical points of a Morse function and whose morphisms are the Morse moduli
spaces between the critical points to an n-category. The n-category
construction involves repeatedly doing Morse theory on Morse moduli spaces for
which we have to construct a class of suitable Morse functions. It turns out to
be an `almost strict' n-category, i.e. it is a strict n-category `up to
canonical isomorphisms'.
| arxiv topic:math.CT math.DG math.DS |
arxiv_dataset-83431703.10796 | A linear Uzawa-type solver for nonlinear transmission problems
math.NA
We propose an Uzawa-type iteration for the Johnson-N\'ed\'elec formulation of
a Laplace-type transmission problem with possible (strongly monotone)
nonlinearity in the interior domain. In each step, we sequentially solve one
BEM for the weakly-singular integral equation associated with the
Laplace-operator and one FEM for the linear Yukawa equation. In particular, the
nonlinearity is only evaluated to build the right-hand side of the Yukawa
equation. We prove that the proposed method leads to linear convergence with
respect to the number of Uzawa iterations. Moreover, while the current analysis
of a direct FEM-BEM discretization of the Johnson-N\'ed\'elec formulation
requires some restrictions on the ellipticity (resp. strong monotonicity
constant) in the interior domain, our Uzawa-type solver avoids such
assumptions.
| arxiv topic:math.NA |
arxiv_dataset-83441703.10896 | BB8: A Scalable, Accurate, Robust to Partial Occlusion Method for
Predicting the 3D Poses of Challenging Objects without Using Depth
cs.CV
We introduce a novel method for 3D object detection and pose estimation from
color images only. We first use segmentation to detect the objects of interest
in 2D even in presence of partial occlusions and cluttered background. By
contrast with recent patch-based methods, we rely on a "holistic" approach: We
apply to the detected objects a Convolutional Neural Network (CNN) trained to
predict their 3D poses in the form of 2D projections of the corners of their 3D
bounding boxes. This, however, is not sufficient for handling objects from the
recent T-LESS dataset: These objects exhibit an axis of rotational symmetry,
and the similarity of two images of such an object under two different poses
makes training the CNN challenging. We solve this problem by restricting the
range of poses used for training, and by introducing a classifier to identify
the range of a pose at run-time before estimating it. We also use an optional
additional step that refines the predicted poses. We improve the
state-of-the-art on the LINEMOD dataset from 73.7% to 89.3% of correctly
registered RGB frames. We are also the first to report results on the Occlusion
dataset using color images only. We obtain 54% of frames passing the Pose 6D
criterion on average on several sequences of the T-LESS dataset, compared to
the 67% of the state-of-the-art on the same sequences which uses both color and
depth. The full approach is also scalable, as a single network can be trained
for multiple objects simultaneously.
| arxiv topic:cs.CV |
arxiv_dataset-83451703.10996 | The relation between alignment covariance and background-averaged
epistasis
q-bio.QM
Epistasis, or the context-dependence of the effects of mutations, limits our
ability to predict the functional impact of combinations of mutations, and
ultimately our ability to predict evolutionary trajectories. Information about
the context-dependence of mutations can essentially be obtained in two ways:
First, by experimental measurement the functional effects of combinations of
mutations and calculating the epistatic contributions directly, and second, by
statistical analysis of the frequencies and co-occurrences of protein residues
in a multiple sequence alignment of protein homologs. In this manuscript, we
derive the mathematical relationship between epistasis calculated on the basis
of functional measurements, and the covariance calculated from a multiple
sequence alignment. There is no one-to-one mapping between covariance and
epistatic terms: covariance implies epistasis, but epistasis does not
necessarily lead to covariance, indicating that covariance in itself is not the
directly relevant quantity for functional prediction. Having calculated
epistatic contributions from the alignment, we can directly obtain a functional
prediction from the alignment statistics by applying a Walsh-Hadamard
transform, fully analogous to the transformation that reconstructs functional
data from measured epistatic contributions. This embedding into the Hadamard
framework is directly relevant for solidifying our theoretical understanding of
statistical methods that predict function and three-dimensional structure from
natural alignments.
| arxiv topic:q-bio.QM |
arxiv_dataset-83461704.00088 | Noether currents for higher-order variational problems of Herglotz type
with time delay
math.OC math-ph math.MP
We study, from an optimal control perspective, Noether currents for
higher-order problems of Herglotz type with time delay. Main result provides
new Noether currents for such generalized variational problems, which are
particularly useful in the search of extremals. The proof is based on the idea
of rewriting the higher-order delayed generalized variational problem as a
first-order optimal control problem without time delays.
| arxiv topic:math.OC math-ph math.MP |
arxiv_dataset-83471704.00188 | Modeling trait-dependent evolution on a random species tree
q-bio.PE math.PR
Understanding the evolution of binary traits, which affects the birth and
survival of species and also the rate of molecular evolution, remains
challenging. A typical example is the evolution of mating systems in plant
species. In this work, we present a probabilistic modeling framework for binary
trait, random species trees, in which the number of species and their traits
are represented by a two-type, continuous time Markov branching process. We
develop our model by considering the impact of mating systems on dN/dS, the
ratio of nonsynonymous to synonymous substitutions. A methodology is introduced
which enables us to match model parameters with parameter estimates from
phylogenetic tree data. The properties obtained from the model are applied to
outcrossing and selfing species trees in the Geraniaceae and Solanaceae family.
This allows us to investigate not only the branching tree rates, but also the
mutation rates and the intensity of selection.
| arxiv topic:q-bio.PE math.PR |
arxiv_dataset-83481704.00288 | A modulated RRd star observed by K2
astro-ph.SR
We report the analysis of the double-mode RR Lyrae star EPIC 205209951, the
first modulated RRd star observed from space. The amplitude and phase
modulation are present in both modes.
| arxiv topic:astro-ph.SR |
arxiv_dataset-83491704.00388 | Implications of a frame dependent gravitational effective action for
perturbations on the Robertson-Walker Metric
gr-qc astro-ph.CO hep-ph hep-th
In earlier work we showed that a frame dependent effective action motivated
by the postulates of three-space general coordinate invariance and Weyl scaling
invariance exactly mimics a cosmological constant in Robertson-Walker (RW)
spacetimes. Here we study the implications of this effective action for small
fluctuations around a spatially flat RW background geometry. The equations for
the conserving extension of the modified stress-energy tensor can be integrated
in closed form, and involve only the metric perturbation $h_{00}$. Hence the
equations for tensor and vector perturbations are unmodified, but there are
Hubble scale additions to the scalar perturbation equations, which nonetheless
admit no propagating wave solutions. Consequently, there are no modifications
to standard gravitational wave propagation theory, but there may be observable
implications for cosmology. We give a self-contained discussion, including an
analysis of the restricted class of gauge transformations that act when a frame
dependent effective action is present.
| arxiv topic:gr-qc astro-ph.CO hep-ph hep-th |
arxiv_dataset-83501704.00488 | First measurement of transverse-spin-dependent azimuthal asymmetries in
the Drell-Yan process
hep-ex hep-ph
The first measurement of transverse-spin-dependent azimuthal asymmetries in
the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190
GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three
azimuthal asymmetries giving access to different transverse-momentum-dependent
(TMD) parton distribution functions (PDFs) are extracted using dimuon events
with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign
of the Sivers asymmetry is found to be consistent with the fundamental
prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted
from DY have a sign opposite to the one extracted from semi-inclusive
deep-inelastic scattering (SIDIS) data. We present two other asymmetries
originating from the pion Boer-Mulders TMD PDFs convoluted with either the
nucleon transversity or pretzelosity TMD PDFs. These DY results are obtained at
a hard scale comparable to that of a recent COMPASS SIDIS measurement and hence
allow unique tests of fundamental QCD universality predictions.
| arxiv topic:hep-ex hep-ph |
arxiv_dataset-83511704.00588 | Causality and surrogate variable analysis
stat.AP
Gene expression depends on thousands of factors and we usually only have
access to tens or hundreds of observations of gene expression levels meaning we
are in a high-dimensional setting. Additionally we don't always observe or care
about all the factors. However, many different gene expression levels depend on
a set of common factors. By observing the joint variance of the gene expression
levels together with the observed primary variables (those we care about)
Surrogate Variable Analysis (SVA) seeks to estimate the remaining unobserved
factors. The ultimate goal is to assess whether the primary variable (or
vector) has a significant effect on the different gene expression levels, but
without estimating unobserved factors first the various regression models and
hypothesis tests are dependent which complicates significance analysis. In this
work we define a class of additive gene expression structural equation models
(SEMs) which are convenient for modeling gene expression data and which
provides a useful framework to understand the various steps of the SVA
methodology. We justify the use of this class from a modeling viewpoint but
also from a causality viewpoint by exploring the independence and causality
properties of this class and comparing to the biologically driven data
assumptions. For this we use some of the theory that has been developed
elsewhere on graphical models and causality. We then give a detailed
description of the SVA methodology and its implementation in the R package sva
referring each step to different parts of the additive gene expression SEM
defined previously.
| arxiv topic:stat.AP |
arxiv_dataset-83521704.00688 | A variational nonlinear Hausdorff-Young inequality in the discrete
setting
math.CA
Following the works of Lyons and Oberlin, Seeger, Tao, Thiele and Wright, we
relate the variation of certain discrete curves on the Lie group
$\text{SU}(1,1)$ to the corresponding variation of their linearized versions on
the Lie algebra. Combining this with a discrete variational
Menshov-Paley-Zygmund theorem, we establish a variational Hausdorff-Young
inequality for a discrete version of the nonlinear Fourier transform on
$\text{SU}(1,1)$.
| arxiv topic:math.CA |
arxiv_dataset-83531704.00788 | Challenges for Cosmic-ray Experiments
astro-ph.HE
This paper is a commentary on presentations at ISVHECRI 2016 related to
cosmic rays, gamma rays and neutrinos. Its goal is to highlight the unanswered
questions raised during the conference about the sources of these cosmic
particles and the relations among them.
| arxiv topic:astro-ph.HE |
arxiv_dataset-83541704.00888 | A Discrete-Time Attitude Observer on SO(3) for Vision and GPS Fusion
cs.RO cs.SY
This paper proposes a discrete-time geometric attitude observer for fusing
monocular vision with GPS velocity measurements. The observer takes the
relative transformations obtained from processing monocular images with any
visual odometry algorithm and fuses them with GPS velocity measurements. The
objectives of this sensor fusion are twofold; first to mitigate the inherent
drift of the attitude estimates of the visual odometry, and second, to estimate
the orientation directly with respect to the North-East-Down frame. A key
contribution of the paper is to present a rigorous stability analysis showing
that the attitude estimates of the observer converge exponentially to the true
attitude and to provide a lower bound for the convergence rate of the observer.
Through experimental studies, we demonstrate that the observer effectively
compensates for the inherent drift of the pure monocular vision based attitude
estimation and is able to recover the North-East-Down orientation even if it is
initialized with a very large attitude error.
| arxiv topic:cs.RO cs.SY |
arxiv_dataset-83551704.00988 | Checklists to Support Test Charter Design in Exploratory Testing
cs.SE
During exploratory testing sessions the tester simultaneously learns, designs
and executes tests. The activity is iterative and utilizes the skills of the
tester and provides flexibility and creativity.Test charters are used as a
vehicle to support the testers during the testing. The aim of this study is to
support practitioners in the design of test charters through checklists. We
aimed to identify factors allowing practitioners to critically reflect on their
designs and contents of test charters to support practitioners in making
informed decisions of what to include in test charters. The factors and
contents have been elicited through interviews. Overall, 30 factors and 35
content elements have been elicited.
| arxiv topic:cs.SE |
arxiv_dataset-83561704.01088 | sWSI: A Low-cost and Commercial-quality Whole Slide Imaging System on
Android and iOS Smartphones
physics.bio-ph cs.CV
In this paper, scalable Whole Slide Imaging (sWSI), a novel high-throughput,
cost-effective and robust whole slide imaging system on both Android and iOS
platforms is introduced and analyzed. With sWSI, most mainstream smartphone
connected to a optical eyepiece of any manually controlled microscope can be
automatically controlled to capture sequences of mega-pixel fields of views
that are synthesized into giga-pixel virtual slides. Remote servers carry out
the majority of computation asynchronously to support clients running at
satisfying frame rates without sacrificing image quality nor robustness. A
typical 15x15mm sample can be digitized in 30 seconds with 4X or in 3 minutes
with 10X object magnification, costing under $1. The virtual slide quality is
considered comparable to existing high-end scanners thus satisfying for
clinical usage by surveyed pathologies. The scan procedure with features such
as supporting magnification up to 100x, recoding z-stacks,
specimen-type-neutral and giving real-time feedback, is deemed
work-flow-friendly and reliable.
| arxiv topic:physics.bio-ph cs.CV |
arxiv_dataset-83571704.01188 | Adaptive Communication Networks with Privacy Guarantees
cs.SY
Utilizing the concept of observability, in conjunction with tools from graph
theory and optimization, this paper develops an algorithm for network synthesis
with privacy guarantees. In particular, we propose an algorithm for the
selection of optimal weights for the communication graph in order to maximize
the privacy of nodes in the network, from a control theoretic perspective. In
this direction, we propose an observability-based design of the communication
topology that improves the privacy of the network in presence of an intruder.
The resulting adaptive network responds to the intrusion by changing the
topology of the network-in an online manner- in order to reduce the information
exposed to the intruder.
| arxiv topic:cs.SY |
arxiv_dataset-83581704.01288 | A class of generalized positive linear maps on matrix algebras
math.OA
We construct a class of positive linear maps on matrix algebras. We find
conditions when these maps are atomic, decomposable and completely positive. We
obtain a large class of atomic positive linear maps. As applications in quantum
information theory, we discuss the structural physical approximation and
optimality of entanglement witness associated with these maps.
| arxiv topic:math.OA |
arxiv_dataset-83591704.01388 | Security Against Collective Attacks of a Modified BB84 QKD Protocol with
Information only in One Basis
quant-ph cs.CR
The Quantum Key Distribution (QKD) protocol BB84 has been proven secure
against several important types of attacks: the collective attacks and the
joint attacks. Here we analyze the security of a modified BB84 protocol, for
which information is sent only in the z basis while testing is done in both the
z and the x bases, against collective attacks. The proof follows the framework
of a previous paper (Boyer, Gelles, and Mor, 2009), but it avoids the classical
information-theoretical analysis that caused problems with composability. We
show that this modified BB84 protocol is as secure against collective attacks
as the original BB84 protocol, and that it requires more bits for testing.
| arxiv topic:quant-ph cs.CR |
arxiv_dataset-83601704.01488 | Superconductivity at 33 - 37 K in $ALn_2$Fe$_4$As$_4$O$_2$ ($A$ = K and
Cs; $Ln$ = Lanthanides)
cond-mat.supr-con cond-mat.mtrl-sci
We have synthesized 10 new iron oxyarsenides, K$Ln_2$Fe$_4$As$_4$O$_2$ ($Ln$
= Gd, Tb, Dy, and Ho) and Cs$Ln_2$Fe$_4$As$_4$O$_2$ ($Ln$ = Nd, Sm, Gd, Tb, Dy,
and Ho), with the aid of lattice-match [between $A$Fe$_2$As$_2$ ($A$ = K and
Cs) and $Ln$FeAsO] approach. The resultant compounds possess hole-doped
conducting double FeAs layers, [$A$Fe$_4$As$_4$]$^{2-}$, that are separated by
the insulating [$Ln_2$O$_2$]$^{2+}$ slabs. Measurements of electrical
resistivity and dc magnetic susceptibility demonstrate bulk superconductivity
at $T_\mathrm{c}$ = 33 - 37 K. We find that $T_\mathrm{c}$ correlates with the
axis ratio $c/a$ for all 12442-type superconductors discovered. Also,
$T_\mathrm{c}$ tends to increase with the lattice mismatch, implying a role of
lattice instability for the enhancement of superconductivity.
| arxiv topic:cond-mat.supr-con cond-mat.mtrl-sci |
arxiv_dataset-83611704.01588 | Magnetization process in a frustrated plaquette dimerized ladder
cond-mat.str-el
The magnetic phase diagram of a plaquette dimerized antiferromagnetic system
is studied by using a combination of numerical and analytical techniques. For
the strongly frustrated regime, series expansions and bond operators techniques
are employed to analyze zero magnetization plateau, whereas low energy
effective models are used to study the complete magnetization process. The
interplay between frustration and dimerization gives rise to a rich plateaus
structure that is captured by effective models and corroborated by numerical
density matrix renormalization group simulations, in particular the emergence
of intermediate plateaus at M = 1/4 and 3/4 of saturation in the magnetization
curve.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-83621704.01688 | Worlds Without Moons: Exomoon Constraints for Compact Planetary Systems
astro-ph.EP
One of the primary surprises of exoplanet detections has been the discovery
of compact planetary systems, whereby numerous planets reside within ~0.5 AU of
the host star. Many of these kinds of systems have been discovered in recent
years, indicating that they are fairly common orbital architecture. Of
particular interest are those systems for which the host star is low-mass, thus
potentially enabling one or more of the planets to lie within the Habitable
Zone of the host star. One of the contributors to the habitability of the Earth
is the presence of a substantial moon whose tidal effects can stabilize axial
tilt variations and increase the rate of tidal pool formation. Here we explore
the constraints on the presence of moons for planets in compact systems based
on Hill radii and Roche limit considerations. We apply these constraints to the
TRAPPIST-1 system and demonstrate that most of the planets are very likely to
be worlds without moons.
| arxiv topic:astro-ph.EP |
arxiv_dataset-83631704.01788 | A Survey of Skyline Query Processing
cs.DB
Living in the Information Age allows almost everyone have access to a large
amount of information and options to choose from in order to fulfill their
needs. In many cases, the amount of information available and the rate of
change may hide the optimal and truly desired solution. This reveals the need
of a mechanism that will highlight the best options to choose among every
possible scenario. Based on this the skyline query was proposed which is a
decision support mechanism, that retrieves the valuefor- money options of a
dataset by identifying the objects that present the optimal combination of the
characteristics of the dataset. This paper surveys the state-of-the-art
techniques for skyline query processing, the numerous variations of the initial
algorithm that were proposed to solve similar problems and the
application-specific approaches that were developed to provide a solution
efficiently in each case. Aditionally in each section a taxonomy is outlined
along with the key aspects of each algorithm and its relation to previous
studies.
| arxiv topic:cs.DB |
arxiv_dataset-83641704.01888 | Exploring first-order phase transitions with population annealing
physics.comp-ph cond-mat.soft cond-mat.stat-mech hep-lat
Population annealing is a hybrid of sequential and Markov chain Monte Carlo
methods geared towards the efficient parallel simulation of systems with
complex free-energy landscapes. Systems with first-order phase transitions are
among the problems in computational physics that are difficult to tackle with
standard methods such as local-update simulations in the canonical ensemble,
for example with the Metropolis algorithm. It is hence interesting to see
whether such transitions can be more easily studied using population annealing.
We report here our preliminary observations from population annealing runs for
the two-dimensional Potts model with $q > 4$, where it undergoes a first-order
transition.
| arxiv topic:physics.comp-ph cond-mat.soft cond-mat.stat-mech hep-lat |
arxiv_dataset-83651704.01988 | Random Access Analysis for Massive IoT Networks under A New
Spatio-Temporal Model: A Stochastic Geometry Approach
cs.IT math.IT
Massive Internet of Things (mIoT) has provided an auspicious opportunity to
build powerful and ubiquitous connections that faces a plethora of new
challenges, where cellular networks are potential solutions due to their high
scalability, reliability, and efficiency. The Random Access CHannel (RACH)
procedure is the first step of connection establishment between IoT devices and
Base Stations (BSs) in the cellular-based mIoT network, where modelling the
interactions between static properties of physical layer network and dynamic
properties of queue evolving in each IoT device are challenging. To tackle
this, we provide a novel traffic-aware spatio-temporal model to analyze RACH in
cellular-based mIoT networks, where the physical layer network is modelled and
analyzed based on stochastic geometry in the spatial domain, and the queue
evolution is analyzed based on probability theory in the time domain. For
performance evaluation, we derive the exact expressions for the preamble
transmission success probabilities of a randomly chosen IoT device with
different RACH schemes in each time slot, which offer insights into
effectiveness of each RACH scheme. Our derived analytical results are verified
by the realistic simulations capturing the evolution of packets in each IoT
device. This mathematical model and analytical framework can be applied to
evaluate the performance of other types of RACH schemes in the cellular-based
networks by simply integrating its preamble transmission principle.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-83661704.02088 | Supervised Deep Hashing for Hierarchical Labeled Data
cs.CV
Recently, hashing methods have been widely used in large-scale image
retrieval. However, most existing hashing methods did not consider the
hierarchical relation of labels, which means that they ignored the rich
information stored in the hierarchy. Moreover, most of previous works treat
each bit in a hash code equally, which does not meet the scenario of
hierarchical labeled data. In this paper, we propose a novel deep hashing
method, called supervised hierarchical deep hashing (SHDH), to perform hash
code learning for hierarchical labeled data. Specifically, we define a novel
similarity formula for hierarchical labeled data by weighting each layer, and
design a deep convolutional neural network to obtain a hash code for each data
point. Extensive experiments on several real-world public datasets show that
the proposed method outperforms the state-of-the-art baselines in the image
retrieval task.
| arxiv topic:cs.CV |
arxiv_dataset-83671704.02188 | Mitigation of the hose instability in plasma-wakefield accelerators
physics.plasm-ph
Current models predict the hose instability to crucially limit the
applicability of plasma-wakefield accelerators. By developing an analytical
model which incorporates the evolution of the hose instability over long
propagation distances, this work demonstrates that the inherent drive-beam
energy loss, along with an initial beam energy spread detune the betatron
oscillations of beam electrons, and thereby mitigate the instability. It is
also shown that tapered plasma profiles can strongly reduce initial hosing
seeds. Hence, we demonstrate that the propagation of a drive beam can be
stabilized over long propagation distances, paving the way for the acceleration
of high-quality electron beams in plasma-wakefield accelerators. We find
excellent agreement between our models and particle-in-cell simulations.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-83681704.02288 | New prospects for the numerical calculation of Mellin-Barnes integrals
in Minkowskian kinematics
hep-ph
During the last several years remarkable progress has been made in numerical
calculations of dimensionally regulated multi-loop Feynman diagrams using
Mellin-Barnes (MB) representations. The bottlenecks were non-planar diagrams
and Minkowskian kinematics. The method has been proved to work in highly
non-trivial physical application (two-loop electroweak bosonic corrections to
the $Z \to b \bar{{b}}$ decay), and cross-checked with the sector decomposition
(SD) approach. In fact, both approaches have their pros and cons. In
calculation of multidimensional integrals, depending on masses and scales
involved, they are complementary. A powerful top-bottom approach to the
numerical integration of multidimensional MB integrals is automatized in the
MB-suite AMBRE/MB/ MBtools/MBnumerics/CUBA. Key elements are a dedicated use of
the Cheng-Wu theorem for non-planar topologies and of shifts and deformations
of the integration contours. An alternative bottom-up approach starting with
complex 1-dimensional MB-integrals, based on the exploration of steepest
descent integration contours in Minkowskian kinematics, is also discussed.
Short and long term prospects of the MB-method for multi-loop applications to
LHC- and LC-physics are discussed.
| arxiv topic:hep-ph |
arxiv_dataset-83691704.02388 | Evolution of Long Term Variability in Solar Analogs
astro-ph.SR astro-ph.EP
Earth is the only planet known to harbor life, therefore we may speculate on
how the nature of the Sun-Earth interaction is relevant to life on Earth, and
how the behavior of other stars may influence the development of life on their
planetary systems. We study the long-term variability of a sample of five solar
analog stars using composite chromospheric activity records up to 50 years in
length and synoptic visible-band photometry about 20 years long. This sample
covers a large range of stellar ages which we use to represent the evolution in
activity for solar mass stars. We find that young, fast rotators have an
amplitude of variability many times that of the solar cycle, while old, slow
rotators have very little variability. We discuss the possible impacts of this
variability on young Earth and exoplanet climates.
| arxiv topic:astro-ph.SR astro-ph.EP |
arxiv_dataset-83701704.02488 | Gravitational Waves, baryon asymmetry of the universe and electric
dipole moment in the CP-violating NMSSM
hep-ph
In this work, we make the first study of electroweak baryogenesis (EWBG)
based on the LHC data in the CP-violating next-to-minimal supersymmetric model
(NMSSM) where a strongly first order electroweak phase transition (EWPT) is
obtained in the general complex Higgs potential. With representative benchmark
points which pass the current LEP and LHC constraints, we demonstrate the
structure of EWPT for those points and how a strongly first order EWPT is
obtained in the complex NMSSM where the resulting gravitational wave production
properties are found to be within the reaches of future space-based
interferometers like BBO and Ultimate-DECIGO. We further calculate the
generated baryon asymmetries where the CP violating sources are (1):
higgsino-singlino dominated, (2): higgsino-gaugino dominated or (3): from both
sources. It is shown that all three representing scenarios could evade the
strong constraints set by various electric dipole moments (EDM) searches where
cancellations among the EDM contributions occur at the tree level
(higgsino-singlino dominated) or loop level (higgsino-gaugino dominated). The
125 GeV SM like Higgs can be either the second lightest neutral Higgs $H_2$ or
the third lightest neutral Higgs $H_3$. Finally, we comment on the future
direct and indirect probe of CPV in the Higgs sector from the collider and EDM
experiments.
| arxiv topic:hep-ph |
arxiv_dataset-83711704.02588 | Front propagation and effect of memory in stochastic desertification
models with an absorbing state
q-bio.PE
Desertification in dryland ecosystems is considered to be a major
environmental threat that may lead to devastating consequences. The concern
increases when the system admits two alternative steady states and the
transition is abrupt and irreversible (catastrophic shift). However, recent
studies show that the inherent stochasticity of the birth-death process, when
superimposed on the presence of an absorbing state, may lead to a continuous
(second order) transition even if the deterministic dynamics supports a
catastrophic transition. Following these works we present here a numerical
study of a one-dimensional stochastic desertification model, where the
deterministic predictions are confronted with the observed dynamics. Our
results suggest that a stochastic spatial system allows for a propagating front
only when its active phase invades the inactive (desert) one. In the extinction
phase one observes transient front propagation followed by a global collapse.
In the presence of a seed bank the vegetation state is shown to be more robust
against demographic stochasticity, but the transition in that case still
belongs to the directed percolation equivalence class.
| arxiv topic:q-bio.PE |
arxiv_dataset-83721704.02688 | Hadronic decay properties of newly observed $\Omega_c$ baryons
hep-ph hep-ex
Hadronic decay widths of the newly observed charmed strange baryons,
$\Omega_c(3000)^0$, $\Omega_c(3050)^0$, $\Omega_c(3066)^0$, $\Omega_c(3090)^0$
and $\Omega_c(3119)^0$ have been calculated in a $^3P_0$ model. Our results
indicate that $\Omega_c(3066)^0$ and $\Omega_c(3090)^0$ can be interpreted as
the $1P-$wave $\Omega_{c2}(\frac{3}{2}^-)$ or $\Omega_{c2}(\frac{5}{2}^-)$.
Though the measured masses of $\Omega_c(3000)^0$, $\Omega_c(3050)^0$ and
$\Omega_c(3119)^0$ are lower than existed theoretical predictions of $1D-$wave
$\Omega_c$, the hadronic decay features of these $\Omega_c$ favor assignments
of the $1D-$wave states. $\Omega_c(3000)^0$ is possibly
$\Omega_{c1}(\frac{1}{2}^+)$ or $\Omega_{c1}(\frac{3}{2}^+)$,
$\Omega_c(3050)^0$ is possibly $\hat\Omega_{c3}(\frac{5}{2}^+)$ or
$\hat\Omega_{c3}(\frac{7}{2}^+)$, and $\Omega_c(3119)^0$ is possibly
$\hat\Omega_{c3}(\frac{5}{2}^+)$, $\hat\Omega_{c3}(\frac{7}{2}^+)$,
$\Omega_{c3}(\frac{5}{2}^+)$ or $\Omega_{c3}(\frac{7}{2}^+)$. The predicted
total decay widths in these assignments are consistent with experiment.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-83731704.02788 | Entity Linking for Queries by Searching Wikipedia Sentences
cs.CL
We present a simple yet effective approach for linking entities in queries.
The key idea is to search sentences similar to a query from Wikipedia articles
and directly use the human-annotated entities in the similar sentences as
candidate entities for the query. Then, we employ a rich set of features, such
as link-probability, context-matching, word embeddings, and relatedness among
candidate entities as well as their related entities, to rank the candidates
under a regression based framework. The advantages of our approach lie in two
aspects, which contribute to the ranking process and final linking result.
First, it can greatly reduce the number of candidate entities by filtering out
irrelevant entities with the words in the query. Second, we can obtain the
query sensitive prior probability in addition to the static link-probability
derived from all Wikipedia articles. We conduct experiments on two benchmark
datasets on entity linking for queries, namely the ERD14 dataset and the GERDAQ
dataset. Experimental results show that our method outperforms state-of-the-art
systems and yields 75.0% in F1 on the ERD14 dataset and 56.9% on the GERDAQ
dataset.
| arxiv topic:cs.CL |
arxiv_dataset-83741704.02888 | $\tilde{\delta}$ Gravity, $\tilde{\delta}$ matter and the accelerated
expansion of the Universe
gr-qc
A gravitational field model based on two symmetric tensors, $g_{\mu \nu}$ and
$\tilde{g}_{\mu \nu}$, is presented. In this model, new matter fields are added
to the original matter fields, motivated by an additional symmetry
($\tilde{\delta}$ symmetry). We call them $\tilde{\delta}$ matter fields. We
find that massive particles do not follow geodesics, while trajectories of
massless particles are null geodesics of an effective metric. Then we study the
Cosmological case, where we get an accelerated expansion of the Universe
without dark energy.
| arxiv topic:gr-qc |
arxiv_dataset-83751704.02988 | Formation of Globular Cluster Candidates in Merging Proto-galaxies at
High Redshift: A View from the FIRE Cosmological Simulations
astro-ph.GA astro-ph.CO
Using a state-of-the-art cosmological simulation of merging proto-galaxies at
high redshift from the FIRE project, with explicit treatments of star formation
and stellar feedback in the interstellar medium, we investigate the formation
of star clusters and examine one of the formation hypothesis of present-day
metal-poor globular clusters. We find that frequent mergers in high-redshift
proto-galaxies could provide a fertile environment to produce long-lasting
bound star clusters. The violent merger event disturbs the gravitational
potential and pushes a large gas mass of ~> 1e5-6 Msun collectively to high
density, at which point it rapidly turns into stars before stellar feedback can
stop star formation. The high dynamic range of the reported simulation is
critical in realizing such dense star-forming clouds with a small dynamical
timescale, t_ff <~ 3 Myr, shorter than most stellar feedback timescales. Our
simulation then allows us to trace how clusters could become virialized and
tightly-bound to survive for up to ~420 Myr till the end of the simulation.
Because the cluster's tightly-bound core was formed in one short burst, and the
nearby older stars originally grouped with the cluster tend to be
preferentially removed, at the end of the simulation the cluster has a small
age spread.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-83761704.03088 | The structure and motion of incoherent {\Sigma}3 grain boundaries in FCC
metals
cond-mat.mtrl-sci
Synthetic driving force molecular dynamics simulations were utilized to
survey grain boundary mobility in three classes of incoherent {\Sigma}3 twin
boundaries: <112>, <110>, and <111> tilt boundaries. These boundaries are
faceted on low energy planes, and step flow boundary motion occurs by glide of
the triplets of partial dislocations that comprise the mobile facets.
Systematic trends with inclination angle are identified and characterized.
Observations of thermally activated, anti-thermal, and athermal motion are
explained in terms of the orientation of the Shockley partial dislocations
along close-packed and non-close-packed directions. Thermally activated
boundaries follow a compensation effect associated with a facet roughening
transition. As for all faceting boundaries, system size and driving force must
be chosen with care to prevent simulation artifacts.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-83771704.03188 | Simplified Stochastic Feedforward Neural Networks
cs.LG
It has been believed that stochastic feedforward neural networks (SFNNs) have
several advantages beyond deterministic deep neural networks (DNNs): they have
more expressive power allowing multi-modal mappings and regularize better due
to their stochastic nature. However, training large-scale SFNN is notoriously
harder. In this paper, we aim at developing efficient training methods for
SFNN, in particular using known architectures and pre-trained parameters of
DNN. To this end, we propose a new intermediate stochastic model, called
Simplified-SFNN, which can be built upon any baseline DNNand approximates
certain SFNN by simplifying its upper latent units above stochastic ones. The
main novelty of our approach is in establishing the connection between three
models, i.e., DNN->Simplified-SFNN->SFNN, which naturally leads to an efficient
training procedure of the stochastic models utilizing pre-trained parameters of
DNN. Using several popular DNNs, we show how they can be effectively
transferred to the corresponding stochastic models for both multi-modal and
classification tasks on MNIST, TFD, CASIA, CIFAR-10, CIFAR-100 and SVHN
datasets. In particular, we train a stochastic model of 28 layers and 36
million parameters, where training such a large-scale stochastic network is
significantly challenging without using Simplified-SFNN
| arxiv topic:cs.LG |
arxiv_dataset-83781704.03288 | Energy Efficiency in Cell-Free Massive MIMO with Zero-Forcing Precoding
Design
cs.IT math.IT
We consider the downlink of a cell-free massive multiple-input
multiple-output (MIMO) network where numerous distributed access points (APs)
serve a smaller number of users under time division duplex operation. An
important issue in deploying cell-free networks is high power consumption,
which is proportional to the number of APs. This issue has raised the question
as to their suitability for green communications in terms of the total energy
efficiency (bits/Joule). To tackle this, we develop a novel low-complexity
power control technique with zero-forcing precoding design to maximize the
energy efficiency of cell-free massive MIMO taking into account the backhaul
power consumption and the imperfect channel state information.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-83791704.03388 | Higgs boson mass corrections in the $\mu\nu$SSM with effective potential
methods
hep-ph
To solve the $\mu$ problem of the MSSM, the $\mu$ from $\nu$ Supersymmetric
Standard Model ($\mu\nu$SSM) introduces three singlet right-handed neutrino
superfields $\hat{\nu}_i^c$, which lead to the mixing of the neutral components
of the Higgs doublets with the sneutrinos, producing a relatively large CP-even
neutral scalar mass matrix. In this work, we analytically diagonalize the
CP-even neutral scalar mass matrix and analyze in detail how the mixing impacts
the lightest Higgs boson mass. We also give an approximate expression for the
lightest Higgs boson mass. Simultaneously, we consider the radiative
corrections to the Higgs boson masses with effective potential methods.
| arxiv topic:hep-ph |
arxiv_dataset-83801704.03488 | Learning Proximal Operators: Using Denoising Networks for Regularizing
Inverse Imaging Problems
cs.CV
While variational methods have been among the most powerful tools for solving
linear inverse problems in imaging, deep (convolutional) neural networks have
recently taken the lead in many challenging benchmarks. A remaining drawback of
deep learning approaches is their requirement for an expensive retraining
whenever the specific problem, the noise level, noise type, or desired measure
of fidelity changes. On the contrary, variational methods have a plug-and-play
nature as they usually consist of separate data fidelity and regularization
terms.
In this paper we study the possibility of replacing the proximal operator of
the regularization used in many convex energy minimization algorithms by a
denoising neural network. The latter therefore serves as an implicit natural
image prior, while the data term can still be chosen independently. Using a
fixed denoising neural network in exemplary problems of image deconvolution
with different blur kernels and image demosaicking, we obtain state-of-the-art
reconstruction results. These indicate the high generalizability of our
approach and a reduction of the need for problem-specific training.
Additionally, we discuss novel results on the analysis of possible optimization
algorithms to incorporate the network into, as well as the choices of algorithm
parameters and their relation to the noise level the neural network is trained
on.
| arxiv topic:cs.CV |
arxiv_dataset-83811704.03588 | Ensemble Inequivalence and Maxwell Construction in the Self-Gravitating
Ring Model
cond-mat.stat-mech
Equilibrium Statistical Mechanics is undoubtedly a cornerstone for the
description of many particle systems. The common interpretation is based on
ensemble theory as put forward by Gibbs, alongside the basic assumptions that
different ensembles are equivalent, i.~e.\ the properties of the system can
equally be obtained in any ensemble with the same results. However, the
simplicity of the argument that provides such equivalence, mathematically
grounded by the existence of Legendre transformation between the ensembles and
the existence of its inverse, may break down for physical systems with long
range interactions. In this paper we study the behavior of a simple toy model
with a long range interaction and show from first principles, by solving
numerically the mechanical equations of motion and Monte Carlo simulations, the
inequivalence of ensembles, and discuss in what situations and how the Maxwell
construction is applicable.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-83821704.03688 | Classical transitions with the topological number changing in the early
Universe
hep-th astro-ph.CO gr-qc
We consider classical dynamics of two real scalar fields within a model with
the potential having a saddle point. The solitons of such model are field
configurations that have the form of closed loops in the field space. We study
the formation and evolution of these solitons, in particular, the conditions at
which they could be formed even when the model potential has only one minimum.
These non-trivial field configurations represent domain walls in the
three-dimensional physical space. The set of these configurations can be split
into disjoint equivalence classes. We provide a simple expression for the
winding number of an arbitrary closed loop in the field space and discuss the
transitions that change the winding number. We also show that non-trivial field
configurations could be responsible for the energy density excess that could
evade the CMB constraints but could be important at scales which are
responsible for the formation of galaxies and the massive primordial black
holes.
| arxiv topic:hep-th astro-ph.CO gr-qc |
arxiv_dataset-83831704.03788 | Probing extra Yukawa couplings by precision measurements of Higgs
properties
hep-ph
If one removes any \emph{ad hoc} symmetry assumptions, the general two Higgs
doublet model should have additional Yukawa interactions independent from
fermion mass generation, in general involving flavor changing neutral Higgs
couplings. These extra couplings can affect the discovered Higgs boson $h$
through fermion loop contributions. We calculate the renormalized $hZZ$
coupling at one-loop level %by on-shell and minimal subtraction scheme, and
evaluate the dependence on heavy Higgs boson mass and extra Yukawa coupling
$\rho_{tt}$. Precision measurements at future colliders can explore the
parameter space, and can give stronger bound on $\rho_{tt}$ than the current
bound from flavor experiments. As a side result, we find that if
$\rho_{tt}\cos\gamma < 0$, where $\cos\gamma$ is the exotic Higgs component of
$h$, the $\rho_{tt}$-induced top loop contribution cancels against bosonic loop
contributions, and one may have alignment without decoupling, namely
$\sin(-\gamma) \simeq 1$, but exotic scalar bosons could have masses at several
hundred GeV.
| arxiv topic:hep-ph |
arxiv_dataset-83841704.03888 | Feynman Rules for the Standard Model Effective Field Theory in
$R_\xi$-gauges
hep-ph
We assume that New Physics effects are parametrized within the Standard Model
Effective Field Theory (SMEFT) written in a complete basis of gauge invariant
operators up to dimension 6, commonly referred to as "Warsaw basis". We discuss
all steps necessary to obtain a consistent transition to the spontaneously
broken theory and several other important aspects, including the
BRST-invariance of the SMEFT action for linear $R_\xi$-gauges. The final theory
is expressed in a basis characterized by SM-like propagators for all physical
and unphysical fields. The effect of the non-renormalizable operators appears
explicitly in triple or higher multiplicity vertices. In this mass basis we
derive the complete set of Feynman rules, without resorting to any simplifying
assumptions such as baryon-, lepton-number or CP conservation. As it turns out,
for most SMEFT vertices the expressions are reasonably short, with a noticeable
exception of those involving 4, 5 and 6 gluons. We have also supplemented our
set of Feynman rules, given in an appendix here, with a publicly available
Mathematica code working with the FeynRules package and producing output which
can be integrated with other symbolic algebra or numerical codes for automatic
SMEFT amplitude calculations.
| arxiv topic:hep-ph |
arxiv_dataset-83851704.03988 | Renormalization group in super-renormalizable quantum gravity
hep-th gr-qc math-ph math.MP
One of the main advantages of super-renormalizable higher derivative quantum
gravity models is the possibility to derive exact beta functions, by making
perturbative one-loop calculations. We perform such a calculation for the
Newton constant by using the Barvinsky-Vilkovisky trace technology. The result
is well-defined in a large class of models of gravity in the sense that the
renormalization group beta functions do not depend on the gauge-fixing
condition. Finally, we discuss the possibility to apply the results to a large
class of nonlocal gravitational theories which are free of massive ghost-like
states at the tree-level.
| arxiv topic:hep-th gr-qc math-ph math.MP |
arxiv_dataset-83861704.04088 | QDB: a new database of plasma chemistries and reactions
physics.plasm-ph
One of the most challenging and recurring problems when modelling plasmas is
the lack of data on key atomic and molecular reactions that drive plasma
processes. Even when there are data for some reactions, complete and validated
datasets of chemistries are rarely available. This hinders research on plasma
processes and curbs development of industrial applications. The QDB project
aims to address this problem by providing a platform for provision, exchange,
and validation of chemistry datasets. A new data model developed for QDB is
presented. QDB collates published data on both electron scattering and
heavy-particle reactions. These data are formed into reaction sets, which are
then validated against experimental data where possible. This process produces
both complete chemistry sets and identifies key reactions that are currently
unreported in the literature. Gaps in the datasets can be filled using
established theoretical methods. Initial validated chemistry sets for
SF$_6$/CF$_4$/O$_2$ and SF$_6$/CF$_4$/N$_2$/H$_2$ are presented as examples.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-83871704.04188 | The influence of anisotropic Rashba spin-orbit coupling on
current-induced spin polarization in graphene
cond-mat.mes-hall
We consider a disordered graphene layer with anisotropic Rashba spin-orbit
coupling subjected to a longitudinal electric field. Using the linear response
theory we calculate current-induced spin polarization including in-plane normal
and parallel components with respect to the electric field direction. Unlike
the case of isotropic Rashba spin-orbit where the normal component of spin
polarization is linear in terms of Fermi energy around the Dirac point,
anisotropic Rashba spin-orbit can result in non-linear dependence of this
component at such energies within the Lifshitz points. Furthermore, we show
that anisotropic Rashba interaction allows for tuning the direction of spin
polarization from perpendicular direction to the parallel one such that for
certain values of Rashba parameters the magnitudes of both components can also
be quenched. The effect of carriers scattering on randomly distributed
non-magnetic disorders is also taken into account by calculating vertex
correction. This results in modification of spin polarization components
depending on the relative strength of Rashba parameters.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-83881704.04288 | Passing through a stack $k$ times
math.CO
We consider the number of passes a permutation needs to take through a stack
if we only pop the appropriate output values and start over with the remaining
entries in their original order. We define a permutation $\pi$ to be $k$-pass
sortable if $\pi$ is sortable using $k$ passes through the stack. Permutations
that are $1$-pass sortable are simply the stack sortable permutations as
defined by Knuth. We define the permutation class of $2$-pass sortable
permutations in terms of their basis. We also show all $k$-pass sortable
classes have finite bases by giving bounds on the length of a basis element of
the permutation class for any positive integer $k$. Finally, we define the
notion of tier of a permutation $\pi$ to be the minimum number of passes after
the first pass required to sort $\pi$. We then give a bijection between the
class of permutations of tier $t$ and a collection of integer sequences studied
by Parker. This gives an exact enumeration of tier $t$ permutations of a given
length and thus an exact enumeration for the class of $(t+1)$-pass sortable
permutations. Finally, we give a new derivation for the generating function in
Parker's thesis and an explicit formula for the coefficients.
| arxiv topic:math.CO |
arxiv_dataset-83891704.04388 | On the connectivity of the hyperbolicity region of irreducible
polynomials
math.AG math.OC
We give an elementary proof for the fact that an irreducible hyperbolic
polynomial has only one pair of hyperbolicity cones.
| arxiv topic:math.AG math.OC |
arxiv_dataset-83901704.04488 | Kakeya books and projections of Kakeya sets
math.CA
Here we show some results related with Kakeya conjecture which says that for
any integer $n\geq 2$, a set containing line segments in every dimension in
$\mathbb{R}^n$ has full Hausdorff dimension as well as box dimension. We proved
here that the Kakeya books, which are Kakeya sets with some restrictions on
positions of line segments have full box dimension. We also prove here a
relation between the projection property of Kakeya sets and the Kakeya
conjecture. If for any Kakeya set $K\subset\mathbb{R}^n$, the Hausdorff
dimension of orthogonal projections on $k\leq n$ subspaces is independent of
directions then the Kakeya conjecture is true. Moreover, the converse is also
true.
| arxiv topic:math.CA |
arxiv_dataset-83911704.04588 | Data aggregation routing protocols in wireless sensor networks: a
taxonomy
cs.DC cs.NI
Routing in Wireless Sensor Network (WSN) aims to interconnect sensor nodes
via single or multi-hop paths. The routes are established to forward data
packets from sensor nodes to the sink. Establishing a single path to report
each data packet results in increasing energy consumption in WSN, hence, data
aggregation routing is used to combine data packets and consequently reduce the
number of transmissions. This reduces the routing overhead by eliminating
redundant and meaningless data. There are two models for data aggregation
routing in WSN: mobile agent and client/server. This paper describes data
aggregation routing and classifies then the routing protocols according to the
network architecture and routing models. The key issues of the data aggregation
routing models (client/server and mobile agent) are highlighted and discussed.
| arxiv topic:cs.DC cs.NI |
arxiv_dataset-83921704.04688 | Machine Learning and the Future of Realism
stat.ML cs.LG
The preceding three decades have seen the emergence, rise, and proliferation
of machine learning (ML). From half-recognised beginnings in perceptrons,
neural nets, and decision trees, algorithms that extract correlations (that is,
patterns) from a set of data points have broken free from their origin in
computational cognition to embrace all forms of problem solving, from voice
recognition to medical diagnosis to automated scientific research and
driverless cars, and it is now widely opined that the real industrial
revolution lies less in mobile phone and similar than in the maturation and
universal application of ML. Among the consequences just might be the triumph
of anti-realism over realism.
| arxiv topic:stat.ML cs.LG |
arxiv_dataset-83931704.04788 | Rotational deviations and invariant pseudo-foliations for periodic point
free torus homeomorphisms
math.DS
This article deals with directional rotational deviations for non-wandering
periodic point free homeomorphisms of the 2-torus which are homotopic to the
identity. We prove that under mild assumptions, such a homeomorphism exhibits
uniformly bounded rotational deviations in some direction if and only it leaves
invariant a pseudo-foliation, a notion which is a slight generalization of
classical one-dimensional foliations. To get these results, we introduce a
novel object called $\tilde\rho$-centralized skew-product and their associated
stable sets at infinity.
| arxiv topic:math.DS |
arxiv_dataset-83941704.04888 | Envy-free Matchings with Lower Quotas
cs.GT
While every instance of the Hospitals/Residents problem admits a stable
matching, the problem with lower quotas (HR-LQ) has instances with no stable
matching. For such an instance, we expect the existence of an envy-free
matching, which is a relaxation of a stable matching preserving a kind of
fairness property. In this paper, we investigate the existence of an envy-free
matching in several settings, in which hospitals have lower quotas and not all
doctor-hospital pairs are acceptable. We first show that, for an HR-LQ
instance, we can efficiently decide the existence of an envy-free matching.
Then, we consider envy-freeness in the Classified Stable Matching model due to
Huang (2010), i.e., each hospital has lower and upper quotas on subsets of
doctors. We show that, for this model, deciding the existence of an envy-free
matching is NP-hard in general, but solvable in polynomial time if quotas are
paramodular.
| arxiv topic:cs.GT |
arxiv_dataset-83951704.04988 | Augmented Coaching Ecosystem for Non-obtrusive Adaptive Personalized
Elderly Care on the Basis of Cloud-Fog-Dew Computing Paradigm
cs.CY
The concept of the augmented coaching ecosystem for non-obtrusive adaptive
personalized elderly care is proposed on the basis of the integration of new
and available ICT approaches. They include the multimodal user interface
(MMUI), augmented reality (AR), machine learning (ML), Internet of Things
(IoT), and machine-to-machine (M2M) interactions. The ecosystem is based on the
Cloud-Fog-Dew computing paradigm services, providing a full symbiosis by
integrating the whole range from low-level sensors up to high-level services
using integration efficiency inherent in synergistic use of applied
technologies. Inside of this ecosystem, all of them are encapsulated in the
following network layers: Dew, Fog, and Cloud computing layer. Instead of the
"spaghetti connections", "mosaic of buttons", "puzzles of output data", etc.,
the proposed ecosystem provides the strict division in the following dataflow
channels: consumer interaction channel, machine interaction channel, and
caregiver interaction channel. This concept allows to decrease the physical,
cognitive, and mental load on elderly care stakeholders by decreasing the
secondary human-to-human (H2H), human-to-machine (H2M), and machine-to-human
(M2H) interactions in favor of M2M interactions and distributed Dew Computing
services environment. It allows to apply this non-obtrusive augmented reality
ecosystem for effective personalized elderly care to preserve their physical,
cognitive, mental and social well-being.
| arxiv topic:cs.CY |
arxiv_dataset-83961704.05088 | GASP III. JO36: a case of multiple environmental effects at play?
astro-ph.GA
The so-called jellyfish galaxies are objects exhibiting disturbed morphology,
mostly in the form of tails of gas stripped from the main body of the galaxy.
Several works have strongly suggested ram pressure stripping to be the
mechanism driving this phenomenon. Here, we focus on one of these objects,
drawn from a sample of optically selected jellyfish galaxies, and use it to
validate SINOPSIS, the spectral fitting code that will be used for the analysis
of the GASP (GAs Stripping Phenomena in galaxies with MUSE) survey, and study
the spatial distribution and physical properties of gas and stellar populations
in this galaxy. We compare the model spectra to those obtained with GANDALF, a
code with similar features widely used to interpret the kinematic of stars and
gas in galaxies from IFU data. We find that SINOPSIS can reproduce the
pixel-by-pixel spectra of this galaxy at least as good as GANDALF does,
providing reliable estimates of the underlying stellar absorption to properly
correct the nebular gas emission. Using these results, we find strong evidences
of a double effect of ram pressure exerted by the intracluster medium onto the
gas of the galaxy. A moderate burst of star formation, dating between 20 and
500 Myr ago and involving the outer parts of the galaxy more strongly than the
inner regions, was likely induced by a first interaction of the galaxy with the
intracluster medium. Stripping by ram pressure, plus probable gas depletion due
to star formation, contributed to create a truncated ionized gas disk. The
presence of an extended stellar tail on only one side of the disk, points
instead to another kind of process, likely a gravitational interaction by a
fly-by or a close encounter with another galaxy in the cluster.
| arxiv topic:astro-ph.GA |
arxiv_dataset-83971704.05188 | Deep Self-Taught Learning for Weakly Supervised Object Localization
cs.CV
Most existing weakly supervised localization (WSL) approaches learn detectors
by finding positive bounding boxes based on features learned with image-level
supervision. However, those features do not contain spatial location related
information and usually provide poor-quality positive samples for training a
detector. To overcome this issue, we propose a deep self-taught learning
approach, which makes the detector learn the object-level features reliable for
acquiring tight positive samples and afterwards re-train itself based on them.
Consequently, the detector progressively improves its detection ability and
localizes more informative positive samples. To implement such self-taught
learning, we propose a seed sample acquisition method via image-to-object
transferring and dense subgraph discovery to find reliable positive samples for
initializing the detector. An online supportive sample harvesting scheme is
further proposed to dynamically select the most confident tight positive
samples and train the detector in a mutual boosting way. To prevent the
detector from being trapped in poor optima due to overfitting, we propose a new
relative improvement of predicted CNN scores for guiding the self-taught
learning process. Extensive experiments on PASCAL 2007 and 2012 show that our
approach outperforms the state-of-the-arts, strongly validating its
effectiveness.
| arxiv topic:cs.CV |
arxiv_dataset-83981704.05288 | An application of $\Gamma$-semigroups techniques to the Green's Theorem
math.GM
The concept of a $\Gamma$-semigroup has been introduced by Mridul Kanti Sen
in the Int. Symp., New Delhi, 1981. It is well known that the Green's relations
play an essential role in studying the structure of semigroups. In the present
paper we deal with an application of $\Gamma$-semigroups techniques to the
Green's Theorem in an attempt to show the way we pass from semigroups to
$\Gamma$-semigroups.
| arxiv topic:math.GM |
arxiv_dataset-83991704.05388 | An adaptive observer design approach for discrete-time nonlinear systems
math.OC
We discuss a design approach for nonlinear discrete-time adaptive observer.
This involves transforming a nonlinear system into a quasi-LPV (Linear
Parameter Varying) polytopic model in Takagi-Sugeno (T-S) form using nonlinear
embedding and sector nonlinearity (SNL) transformation. We then develop a
discrete-time counterpart for a joint state and parameter estimation, based on
design strategies developed for continuous time models in the existing
literature. The design uses a Lyapunov approach and provides an error bounded
by $\mathbb{L}_2$ gain. Based on this strategy, we propose a design for
adaptive observers for nonlinear systems whose T-S form can have unmeasured
premise variables.
| arxiv topic:math.OC |
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