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arxiv_dataset-63001506.01556 | Tight Global Linear Convergence Rate Bounds for Douglas-Rachford
Splitting
math.OC
Recently, several authors have shown local and global convergence rate
results for Douglas-Rachford splitting under strong monotonicity, Lipschitz
continuity, and cocoercivity assumptions. Most of these focus on the convex
optimization setting. In the more general monotone inclusion setting, Lions and
Mercier showed a linear convergence rate bound under the assumption that one of
the two operators is strongly monotone and Lipschitz continuous. We show that
this bound is not tight, meaning that no problem from the considered class
converges exactly with that rate. In this paper, we present tight global linear
convergence rate bounds for that class of problems. We also provide tight
linear convergence rate bounds under the assumptions that one of the operators
is strongly monotone and cocoercive, and that one of the operators is strongly
monotone and the other is cocoercive. All our linear convergence results are
obtained by proving the stronger property that the Douglas-Rachford operator is
contractive.
| arxiv topic:math.OC |
arxiv_dataset-63011506.01656 | Internally heated convection and Rayleigh-B\'enard convection
physics.flu-dyn astro-ph.SR physics.geo-ph
This work reviews basic features of both Rayleigh-B\'enard (RB) convection
and internally heated (IH) convection, along with findings on IH convection
from laboratory experiments and numerical simulations. In the first chapter,
six canonical models of convection are described: three configurations of IH
convection driven by constant and uniform volumetric heating, and three
configurations of RB convection driven by the boundary conditions. The IH
models are distinguished by differing pairs of thermal boundary conditions: top
and bottom boundaries of equal temperature, an insulating bottom with heat flux
fixed at the top, and an insulating bottom with temperature fixed at the top.
The RB models also are distinguished by whether temperatures or heat fluxes are
fixed at the top and bottom boundaries. Integral quantities important to heat
transport are discussed, including the mean fluid temperature, the mean
temperature difference between the boundaries, and the mean convective heat
transport. Integral relations and bounds are presented, and further bounds are
conjectured for the IH cases. The second chapter presents results that can be
derived mathematically from the governing equations: linear and nonlinear
stability thresholds of static states, and parameter-dependent bounds. Known
bounds are on mean temperatures in IH convection and on convective transport in
RB convection. The third chapter reviews numerical simulations and laboratory
experiments on IH convection, emphasizing quantitative results.
| arxiv topic:physics.flu-dyn astro-ph.SR physics.geo-ph |
arxiv_dataset-63021506.01756 | Thermal and electrical properties of a solid through Fibonacci
oscillators
cond-mat.stat-mech
We investigate the thermodynamics of a crystalline solid applying q-deformed
algebra of Fibonacci oscillators through the generalized Fibonacci sequence of
two real and independent deformation parameters q1 and q2. We based part of our
study on both Einstein and Debye models, exploring primarily (q1,q2)-deformed
thermal and electric conductivities as a function of Debye specific heat. The
results revealed that q-deformation acts as a factor of disorder or impurity,
modifying the characteristics of a crystalline structure. Specially, one may
find the possibility of adjusting the Fibonacci oscillators to describe the
change of thermal and electrical conductivities of a given element as one
inserts impurities. Each parameter can be associated to different types of
deformations such as disorders and impurities.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-63031506.01856 | Three sources and three components of success in detection of ultra-rare
alpha decays at the Dubna Gas-Filled Recoil separator
physics.ins-det nucl-ex
General philosophy of procedure of detecting rare events in the recent
experiments with 48Ca projectile at the Dubna Gas-Filled Recoil
Separator(DGFRS) aimed to the synthesis of superheavy elements (SHE) has been
reviewed. Specific instruments and methods are under consideration. Some
historical sources of the successful experiments for Z=112-118 are considered
too. Special attention is paid to application of method of active correlations
in heavy-ion induced complete fusion nuclear reactions. Example of application
in Z=115 experiment is presented. Brief description of the 243Am + 48Ca ->
291-x115+xn experiment is presented too. Some attention is paid to the role of
chemical experiments in discoveries of SHEs. The DGFRS detection/monitoring
system is presented in full firstly.
| arxiv topic:physics.ins-det nucl-ex |
arxiv_dataset-63041506.01956 | Arithmetic Teichmuller Theory
math.NT
By Grothendieck's anabelian conjectures, Galois representations landing in
outer automorphism group of the algebraic fundamental group which are
associated to hyperbolic smooth curves defined over number-fields encode all
the arithmetic information of these curves. The Goal of this paper is to
develop an arithmetic Teichmuller theory, by which we mean, introducing
arithmetic objects summarizing the arithmetic information coming from all
curves of the same topological type defined over number-fields. We also
introduce Hecke-Teichmuller Lie algebra which plays the role of Hecke algebra
in the anabelian framework.
| arxiv topic:math.NT |
arxiv_dataset-63051506.02056 | Statistical Properties of the T-exponential of Isotropically Distributed
Random Matrices
nlin.CD cond-mat.dis-nn
A functional method for calculating averages of the time-ordered exponential
of a continuous isotropic random $N\times N$ matrix process is presented. The
process is not assumed to be Gaussian. In particular, the Lyapunov exponents
and higher correlation functions of the T-exponent are derived from the
statistical properties of the process.
The approach may be of use in a wide range of physical problems. For example,
in theory of turbulence the account of non-gaussian statistics is very
important since the non-Gaussian behavior is responsible for the time asymmetry
of the energy flow.
| arxiv topic:nlin.CD cond-mat.dis-nn |
arxiv_dataset-63061506.02156 | On Local Strong Solutions to the Cauchy Problem of Two-Dimensional
Density-Dependent Magnetohydrodynamic Equations with Vacuum
math.AP
This paper concerns the Cauchy problem of the nonhomogeneous incompressible
magnetohydrodynamic (MHD) equations on the whole two-dimensional (2D) space
with vacuum as far field density. In particular, the initial density can have
compact support. We prove that the 2D Cauchy problem of the nonhomogeneous
incompressible MHD equations admits a unique local strong solution provided the
initial density and the initial magnetic decay not too slow at infinity.
| arxiv topic:math.AP |
arxiv_dataset-63071506.02256 | Knowledge Transfer Pre-training
cs.LG cs.NE stat.ML
Pre-training is crucial for learning deep neural networks. Most of existing
pre-training methods train simple models (e.g., restricted Boltzmann machines)
and then stack them layer by layer to form the deep structure. This layer-wise
pre-training has found strong theoretical foundation and broad empirical
support. However, it is not easy to employ such method to pre-train models
without a clear multi-layer structure,e.g., recurrent neural networks (RNNs).
This paper presents a new pre-training approach based on knowledge transfer
learning. In contrast to the layer-wise approach which trains model components
incrementally, the new approach trains the entire model as a whole but with an
easier objective function. This is achieved by utilizing soft targets produced
by a prior trained model (teacher model). Compared to the conventional
layer-wise methods, this new method does not care about the model structure, so
can be used to pre-train very complex models. Experiments on a speech
recognition task demonstrated that with this approach, complex RNNs can be well
trained with a weaker deep neural network (DNN) model. Furthermore, the new
method can be combined with conventional layer-wise pre-training to deliver
additional gains.
| arxiv topic:cs.LG cs.NE stat.ML |
arxiv_dataset-63081506.02356 | Connection between commutative algebra and topology
math.AC
The main aim of this paper to show how commutative algebra is connected to
topology. We give underlying topological idea of some results on completable
unimodular rows.
| arxiv topic:math.AC |
arxiv_dataset-63091506.02456 | Continuum Percolation on Disoriented Surfaces: the Problem of Permeable
Disks on a Klein Bottle
cond-mat.dis-nn
The percolation threshold and wrapping probability $R_{\infty}$ for the
two-dimensional problem of continuum percolation on the surface of a Klein
bottle have been calculated by the Monte Carlo method with the Newman--Ziff
algorithm for completely permeable disks. It has been shown that the
percolation threshold of disks on the Klein bottle coincides with the
percolation threshold of disks on the surface of a torus, indicating that this
threshold is topologically invariant. The scaling exponents determining
corrections to the wrapping probability and critical concentration owing to the
finite-size effects are also topologically invariant. At the same time, the
quantities $R_{\infty}$ are different for percolation on the torus and Klein
bottle and are apparently determined by the topology of the surface.
Furthermore, the difference between the $R_{\infty}$ values for the torus and
Klein bottle means that at least one of the percolation clusters is degenerate.
| arxiv topic:cond-mat.dis-nn |
arxiv_dataset-63101506.02556 | Service Discovery in Mobile Ad hoc Networks Using Association Rules
Mining
cs.NI
We have proposed a novel approach to Service Discovery in Mobile Ad hoc
Networks. We have simulated the proposed approach in JIST/SWANS simulator and
the results have shown significant performance improvement.
| arxiv topic:cs.NI |
arxiv_dataset-63111506.02656 | Hadronic Calorimeter Shower Size: Challenges and Opportunities for Jet
Substructure in the Superboosted Regime
hep-ph physics.ins-det
Hadrons have finite interaction size with dense material, a basic feature
common to known forms of hadronic calorimeters (HCAL). We argue that
substructure variables cannot use HCAL information to access the microscopic
nature of jets much narrower than the hadronic shower size, which we call
superboosted massive jets. It implies that roughly 15% of their transverse
energy profile remains inaccessible due to the presence of long-lived neutral
hadrons. This part of the jet substructure is also subject to order-one
fluctuations. We demonstrate that the effects of the fluctuations are not
reduced when a global correction to jet variables is applied. The above leads
to fundamental limitations in the ability to extract intrinsic information from
jets in the superboosted regime. The neutral fraction of a jet is correlated
with its flavor. This leads to an interesting and possibly useful difference
between superboosted W/Z/h/t jets and their corresponding backgrounds. The QCD
jets that form the background to the signal superboosted jets might also be
qualitatively different in their substructure as their mass might lie at or
below the Sudakov mass peak. Finally, we introduce a set of zero-cone
longitudinal jet substructure variables and show that while they carry
information that might be useful in certain situations, they are not in general
sensitive to the jet substructure.
| arxiv topic:hep-ph physics.ins-det |
arxiv_dataset-63121506.02756 | Kinetic roughening and porosity scaling in film growth with subsurface
lateral aggregation
cond-mat.stat-mech cond-mat.mes-hall cond-mat.mtrl-sci
We study surface and bulk properties of porous films produced by a model in
which particles incide perpendicularly to a substrate, interact with deposited
neighbors in its trajectory, and aggregate laterally with probability of order
$a$ at each position. The model generalizes ballistic-like models by allowing
attachment to particles below the outer surface. For small values of $a$, a
crossover from uncorrelated deposition (UD) to correlated growth is observed.
Simulations are performed in 1+1 and 2+1 dimensions. Extrapolation of effective
exponents and comparison of roughness distributions confirm Kardar-Parisi-Zhang
roughening of the outer surface for $a>0$. A scaling approach for small $a$
predicts crossover times as $a^{-2/3}$ and local height fluctuations as
$a^{-1/3}$ at the crossover, independently of substrate dimension. These
relations are different from all previously studied models with crossovers from
UD to correlated growth due to subsurface aggregation, which reduces scaling
exponents. The same approach predicts the porosity and average pore height
scaling as $a^{1/3}$ and $a^{-1/3}$, respectively, in good agreement with
simulation results in 1+1 and 2+1 dimensions. These results may be useful to
modeling samples with desired porosity and long pores.
| arxiv topic:cond-mat.stat-mech cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-63131506.02856 | Kerr nonlinearity and plasmonic bistability in graphene nanoribbons
cond-mat.mes-hall
We theoretically examine the role of Kerr nonlinearities for graphene
plasmonics in nanostructures, specifically in nanoribbons. The nonlinear Kerr
interaction is included semiclassically in the intraband approximation. The
resulting electromagnetic problem is solved numerically by self-consistent
iteration with linear steps using a real-space discretization. We derive a
simple approximation for the resonance shifts in general graphene
nanostructures, and obtain excellent agreement with numerics for moderately
high field strengths. Near plasmonic resonances the nonlinearities are strongly
enhanced due to field enhancement, and the total nonlinearity is significantly
affected by the field inhomogeneity of the plasmonic excitation. Finally, we
discuss the emergence of a plasmonic bistability which exists for frequencies
redshifted relative to the linear resonance. Our results offer new insights
into the role of nonlinear interaction in nanostructured graphene and paves the
way for experimental investigation.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-63141506.02956 | Stellar parameters for stars of the CoRoT exoplanet field
astro-ph.SR
Aims:To support the computation and evolutionary interpretation of periods
associated with the rotational modulation, oscillations, and variability of
stars located in the CoRoT fields, we are conducting a spectroscopic survey for
stars located in the fields already observed by the satellite. These
observations allow us to compute physical and chemical parameters for our
stellar sample. Method: Using spectroscopic observations obtained with UVES/VLT
and Hydra/Blanco, and based on standard analysis techniques, we computed
physical and chemical parameters ($T_{\rm{eff}}$, $\log \,(g)$, $\rm{[Fe/H]}$,
$v_{\rm{mic}}$, $v_{\rm{rad}}$, $v \sin \,(i)$, and $A(\rm{Li})$) for a large
sample of CoRoT targets. Results: We provide physical and chemical parameters
for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in
our sample are located in different evolutionary stages, ranging from the main
sequence to the red giant branch, and range in spectral type from F to K. The
physical and chemical properties for the stellar sample are in agreement with
typical values reported for FGK stars. However, we report three stars
presenting abnormal lithium behavior in the CoRoT fields. These parameters
allow us to properly characterize the intrinsic properties of the stars in
these fields. Our results reveal important differences in the distributions of
metallicity, $T_{\rm eff}$, and evolutionary status for stars belonging to
different CoRoT fields, in agreement with results obtained independently from
ground-based photometric surveys. Conclusions: Our spectroscopic catalog, by
providing much-needed spectroscopic information for a large sample of CoRoT
targets, will be of key importance for the successful accomplishment of several
different programs related to the CoRoT mission, thus it will help further
boost the scientific return associated with this space mission.
| arxiv topic:astro-ph.SR |
arxiv_dataset-63151506.03056 | Traveling surface spin-wave resonance spectroscopy using surface
acoustic waves
cond-mat.mtrl-sci
Coherent gigahertz-frequency surface acoustic waves (SAWs) traveling on the
surface of a piezoelectric crystal can, via the magnetoelastic interaction,
resonantly excite traveling spin waves in an adjacent thin-film ferromagnet.
These excited spin waves, traveling with a definite in-plane wave-vector q
enforced by the SAW, can be detected by measuring changes in the
electro-acoustical transmission of a SAW delay line. Here, we provide a first
demonstration that such measurements constitute a precise and quantitative
technique for spin-wave spectroscopy, providing a means to determine both
isotropic and anisotropic contributions to the spin-wave dispersion and
damping. We demonstrate the effectiveness of this spectroscopic technique by
measuring the spin-wave properties of a Ni thin film for a large range of wave
vectors,q = 2.5 x 10^4 - 8 x 10^4 cm^(-1), over which anisotropic dipolar
interactions vary from being negligible to quite significant.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-63161506.03156 | Systematic analysis of hadron spectra in p+p collisions using Tsallis
distribution
nucl-th
Using the experimental data from the STAR, PHENIX, ALICE and CMS programs on
the rapidity and energy dependence of the $p_T$ spectra in p+p collisions, we
show that a universal distribution exists. The energy dependence of temperature
$T$ and parameter $n$ of the Tsallis distribution are also discussed in detail.
A cascade particle production mechanism in p+p collisions is proposed.
| arxiv topic:nucl-th |
arxiv_dataset-63171506.03256 | Normal numbers and completeness results for difference sets
math.LO
We consider some natural sets of real numbers arising in ergodic theory and
show that they are, respectively, complete in the classes $\mathcal D_2
(\mathbf\Pi^0_3)$ and $\mathcal D_\omega (\mathbf \Pi^0_3)$, that is, the class
of sets which are 2-differences (respectively, $\omega$-differences) of
$\mathbf \Pi^0_3$ sets.
| arxiv topic:math.LO |
arxiv_dataset-63181506.03356 | Discontinuous transition of molecular-hydrogen chain to the quasi-atomic
state: Exact diagonalization - ab initio approach
cond-mat.str-el
We obtain in a direct and rigorous manner a transition from a stable
molecular hydrogen $nH_2$ single chain to the quasiatomic two-chain $2nH$
state. We devise an original method composed of an exact diagonalization in the
Fock space combined with an ab initio adjustment of the single-particle wave
function in the correlated state. In this approach the well-known problem of
double-counting the interparticle interaction does not arise at all. The
transition is strongly discontinuous, and appears even for relatively short
chains possible to tackle, $n=3\div6$. The signature of the transition as a
function of applied force is a discontinuous change of the equilibrium
intramolecular distance. The corresponding change of the Hubbard ratio $U/W$
reflects the Mott--Hubbard-transition aspect of the atomization. Universal
feature of the transition relation to the Mott criterion for the
insulator--metal transition is also noted. The role of the electron
correlations is thus shown to be of fundamental significance.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-63191506.03456 | Stringent Dilepton Bounds on Left-Right Models using LHC data
hep-ph hep-ex
In canonical left-right symmetric models the lower mass bounds on the charged
gauge bosons are in the ballpark of $3-4$ TeV, resulting into much stronger
limits on the neutral gauge boson $Z_R$, making its production unreachable at
the LHC. However, if one evokes different patterns of left-right symmetry
breaking the $Z_R$ might be lighter than the $W_R^\pm$ motivating an
independent $Z_R$ collider study. In this work, we use the 8 TeV ATLAS $20.3$
fb$^{-1}$ luminosity data to derive robust bounds on the $Z_R$ mass using
dilepton data. %because they provide the most restrictive limits due to the
sizable $Z_R$-lepton couplings. We find strong lower bounds on the $Z_R$ mass
for different right-handed gauge couplings, excluding $Z_R$ masses up to $\sim
3.2$TeV. For the canonical LR model we place a lower mass bound of $\sim
2.5$TeV. Our findings are almost independent of the right-handed neutrino
masses ($\sim 2\,\%$ effect) and applicable to general left-right models.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-63201506.03556 | Breaking Dense Structures: Proving Stability of Densely Structured
Hybrid Systems
cs.SE cs.LO cs.SY
Abstraction and refinement is widely used in software development. Such
techniques are valuable since they allow to handle even more complex systems.
One key point is the ability to decompose a large system into subsystems,
analyze those subsystems and deduce properties of the larger system. As
cyber-physical systems tend to become more and more complex, such techniques
become more appealing.
In 2009, Oehlerking and Theel presented a (de-)composition technique for
hybrid systems. This technique is graph-based and constructs a Lyapunov
function for hybrid systems having a complex discrete state space. The
technique consists of (1) decomposing the underlying graph of the hybrid system
into subgraphs, (2) computing multiple local Lyapunov functions for the
subgraphs, and finally (3) composing the local Lyapunov functions into a
piecewise Lyapunov function. A Lyapunov function can serve multiple purposes,
e.g., it certifies stability or termination of a system or allows to construct
invariant sets, which in turn may be used to certify safety and security.
In this paper, we propose an improvement to the decomposing technique, which
relaxes the graph structure before applying the decomposition technique. Our
relaxation significantly reduces the connectivity of the graph by exploiting
super-dense switching. The relaxation makes the decomposition technique more
efficient on one hand and on the other allows to decompose a wider range of
graph structures.
| arxiv topic:cs.SE cs.LO cs.SY |
arxiv_dataset-63211506.03656 | An Exclusion zone for Massive MIMO With Underlay D2D Communication
cs.IT math.IT
Fifth generation networks will incorporate a variety of new features in
wireless networks such as data offloading, D2D communication, and Massive MIMO.
Massive MIMO is specially appealing since it achieves huge gains while enabling
simple processing like MRC receivers. It suffers, though, from a major
shortcoming refereed to as pilot contamination. In this paper we propose a
frame-work in which, a D2D underlaid Massive MIMO system is implemented and we
will prove that this scheme can reduce the pilot contamination problem while
enabling an optimization of the system spectral efficiency. The D2D
communication will help maintain the network coverage while allowing a better
channel estimation to be performed.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-63221506.03756 | A Revisit to Non-maximally Entangled Mixed States: Teleportation
Witness, Noisy Channel and Discord
quant-ph
We constructed a class of non-maximally entangled mixed states \cite{roy2010}
and extensively studied its entanglement properties and also their usefulness
as teleportation channels. In this article, we revisited our constructed state
and have studied it from three different perspectives. Since every entangled
state is associated with an witness operator, we have found a suitable
entanglement as well as teleportation witness for our non-maximally entangled
mixed states. We considered the noisy channel's effects on our constructed
state and to see whether it affects the states' capacity as teleportation
channel. For this purpose we have mainly emphasized on amplitude damping
channel. A comparative study with concurrence and quantum discord of the state
of ref. \cite{roy2010} has also been carried out here.
| arxiv topic:quant-ph |
arxiv_dataset-63231506.03856 | Generalized Efimov effect in one dimension
cond-mat.other cond-mat.quant-gas math-ph math.MP quant-ph
We study a one-dimensional quantum problem of two particles interacting with
a third one via a scale-invariant subcritically attractive inverse square
potential, which can be realized, for example, in a mixture of dipoles and
charges confined to one dimension. We find that above a critical mass ratio,
this version of the Calogero problem exhibits the generalized Efimov effect,
the emergence of discrete scale invariance manifested by a geometric series of
three-body bound states with an accumulation point at zero energy.
| arxiv topic:cond-mat.other cond-mat.quant-gas math-ph math.MP quant-ph |
arxiv_dataset-63241506.03956 | Sur la torsion de Frobenius de la cat\'egorie des modules instables
math.AT
In the category $\mathcal{P}_{d}$ of strict polynomial functors, the
morphisms between extension groups induced by the Frobenius twist are
injective. In \cite{Cuo14a}, the category $\mathcal{P}_{d}$ is proved to be a
full sub-category of the category $\mathcal{U}$ of unstable modules
\textit{via} Hai's functor. The Frobenius twist is extended to the category
$\mathcal{U}$ but remains mysterious there. This article aims to study the
Frobenius twist and its effects on the extension groups of unstable modules. We
compute explicitly several extension groups and show that in these cases, the
morphisms induced by the Frobenius twist are injective. These results are
obtained by constructing the minimal injective resolution of the free unstable
module $F(1)$.
| arxiv topic:math.AT |
arxiv_dataset-63251506.04056 | Numerical relativity simulations of thick accretion disks around tilted
Kerr black holes
gr-qc astro-ph.HE
In this work we present 3D numerical relativity simulations of thick
accretion disks around tilted Kerr BH. We investigate the evolution of three
different initial disk models with a range of initial black hole spin
magnitudes and tilt angles. For all the disk-to-black hole mass ratios
considered (0.044-0.16) we observe significant black hole precession and
nutation during the evolution. This indicates that for such mass ratios,
neglecting the self-gravity of the disks by evolving them in a fixed background
black hole spacetime is not justified. We find that the two more massive models
are unstable against the Papaloizou-Pringle (PP) instability and that those
PP-unstable models remain unstable for all initial spins and tilt angles
considered, showing that the development of the instability is a very robust
feature of such PP-unstable disks. Our lightest model, which is the most
astrophysically favorable outcome of mergers of binary compact objects, is
stable. The tilt between the black hole spin and the disk is strongly modulated
during the growth of the PP instability, causing a partial global realignment
of black hole spin and disk angular momentum in the most massive model with
constant specific angular momentum l. For the model with non-constant l-profile
we observe a long-lived m=1 non-axisymmetric structure which shows strong
oscillations of the tilt angle in the inner regions of the disk. This effect
might be connected to the development of Kozai-Lidov oscillations. Our
simulations also confirm earlier findings that the development of the PP
instability causes the long-term emission of large amplitude gravitational
waves, predominantly for the l=m=2 multipole mode. The imprint of the BH
precession on the gravitational waves from tilted BH-torus systems remains an
interesting open issue that would require significantly longer simulations than
those presented in this work.
| arxiv topic:gr-qc astro-ph.HE |
arxiv_dataset-63261506.04156 | The radial variation of HI velocity dispersions in dwarfs and spirals
astro-ph.GA astro-ph.CO
Gas velocity dispersions provide important diagnostics of the forces
counteracting gravity to prevent collapse of the gas. We use the 21 cm line of
neutral atomic hydrogen (HI) to study HI velocity dispersion and HI phases as a
function of galaxy morphology in 22 galaxies from The HI Nearby Galaxy Survey
(THINGS). We stack individual HI velocity profiles and decompose them into
broad and narrow Gaussian components. We study the HI velocity dispersion and
the HI surface density, as a function of radius. For spirals, the velocity
dispersions of the narrow and broad components decline with radius and their
radial profiles are well described by an exponential function. For dwarfs,
however, the profiles are much flatter. The single Gaussian dispersion profiles
are, in general, flatter than those of the narrow and broad components. In most
cases, the dispersion profiles in the outer disks do not drop as fast as the
star formation profiles, derived in the literature. This indicates the
importance of other energy sources in driving HI velocity dispersion in the
outer disks. The radial surface density profiles of spirals and dwarfs are
similar. The surface density profiles of the narrow component decline more
steeply than those of the broad component, but not as steep as what was found
previously for the molecular component. As a consequence, the surface density
ratio between the narrow and broad components, an estimate of the mass ratio
between cold HI and warm HI, tends to decrease with radius. On average, this
ratio is lower in dwarfs than in spirals. This lack of a narrow, cold HI
component in dwarfs may explain their low star formation activity.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-63271506.04256 | Generating minimally transitive permutation groups
math.GR
We improve the upper bounds (in terms of $n$) in [9] and [13] on the minimal
number of elements required to generate a minimally transitive permutation
group of degree $n$.
| arxiv topic:math.GR |
arxiv_dataset-63281506.04356 | The Artists who Forged Themselves: Detecting Creativity in Art
cs.CV q-bio.NC
Creativity and the understanding of cognitive processes involved in the
creative process are relevant to all of human activities. Comprehension of
creativity in the arts is of special interest due to the involvement of many
scientific and non scientific disciplines. Using digital representation of
paintings, we show that creative process in painting art may be objectively
recognized within the mathematical framework of self organization, a process
characteristic of nonlinear dynamic systems and occurring in natural and social
sciences. Unlike the artist identification process or the recognition of
forgery, which presupposes the knowledge of the original work, our method
requires no prior knowledge on the originality of the work of art. The original
paintings are recognized as realizations of the creative process which, in
general, is shown to correspond to self-organization of texture features which
determine the aesthetic complexity of the painting. The method consists of the
wavelet based statistical digital image processing and the measure of
statistical complexity which represents the minimal (average) information
necessary for optimal prediction. The statistical complexity is based on the
properly defined causal states with optimal predictive properties. Two
different time concepts related to the works of art are introduced: the
internal time and the artistic time. The internal time of the artwork is
determined by the span of causal dependencies between wavelet coefficients
while the artistic time refers to the internal time during which complexity
increases where complexity refers to compositional, aesthetic and structural
arrangement of texture features. The method is illustrated by recognizing the
original paintings from the copies made by the artists themselves, including
the works of the famous surrealist painter Ren\'{e} Magritte.
| arxiv topic:cs.CV q-bio.NC |
arxiv_dataset-63291506.04456 | Using the Rossiter-McLaughlin effect to observe the transmission
spectrum of Earth's atmosphere
astro-ph.EP astro-ph.SR
Due to stellar rotation, the observed radial velocity of a star varies during
the transit of a planet across its surface, a phenomenon known as the
Rossiter-McLaughlin (RM) effect. The amplitude of the RM effect is related to
the radius of the planet which, because of differential absorption in the
planetary atmosphere, depends on wavelength. Therefore, the
wavelength-dependent RM effect can be used to probe the planetary atmosphere.
We measure for the first time the RM effect of the Earth transiting the Sun
using a lunar eclipse observed with the ESO HARPS spectrograph. We analyze the
observed RM effect at different wavelengths to obtain the transmission spectrum
of the Earth's atmosphere after the correction of the solar limb-darkening and
the convective blueshift. The ozone Chappuis band absorption as well as the
Rayleigh scattering features are clearly detectable with this technique. Our
observation demonstrates that the RM effect can be an effective technique for
exoplanet atmosphere characterization. Its particular asset is that photometric
reference stars are not required, circumventing the principal challenge for
transmission spectroscopy studies of exoplanet atmospheres using large
ground-based telescopes.
| arxiv topic:astro-ph.EP astro-ph.SR |
arxiv_dataset-63301506.04556 | Excitation band topology and edge matter waves in Bose-Einstein
condensates in optical lattices
cond-mat.quant-gas cond-mat.str-el
We show that Bose-Einstein condensates in optical lattices with broken
time-reversal symmetry can support chiral edge modes originating from
nontrivial bulk excitation band topology. To be specific, we analyze a
Bose-Hubbard extension of the Haldane model, which can be realized with
recently developed techniques of manipulating honeycomb optical lattices. The
topological properties of Bloch bands known for the noninteracting case are
smoothly carried over to Bogoliubov excitation bands for the interacting case.
We show that the parameter ranges that display topological bands enlarge with
increasing the Hubbard interaction or the particle density. In the presence of
sharp boundaries, chiral edge modes appear in the gap between topological
excitation bands. We demonstrate that by coherently transferring a portion of a
condensate into an edge mode, a density wave is formed along the edge owing to
an interference with the background condensate. This offers a unique method of
detecting an edge mode through a macroscopic quantum phenomenon.
| arxiv topic:cond-mat.quant-gas cond-mat.str-el |
arxiv_dataset-63311506.04656 | Discrete diagonal recurrences and discrete minimal submanifolds
math.DS
Our original results refer to multivariate recurrences: discrete multitime
diagonal recurrence, bivariate recurrence, trivariate recurrence, solutions
tailored to particular situations, second order multivariate recurrences,
characteristic equation, and multivariate diagonal recurrences of superior
order. We find the solutions, we clarify the structural background and provides
short, conceptual proofs. The original results include a new point of view on
discrete minimal submanifolds.
| arxiv topic:math.DS |
arxiv_dataset-63321506.04756 | Relating the type A alcove path model to the right key of a semistandard
Young tableau, with Demazure character consequences
math.CO math.RT
There are several combinatorial methods that can be used to produce type A
Demazure characters (key polynomials). The alcove path model of Lenart and
Postnikov provides a procedure that inputs a semistandard tableau $T$ and
outputs a saturated chain in the Bruhat order. The final permutation in this
chain determines a family of Demazure characters for which $T$ contributes its
weight. Separately, the right key of $T$ introduced by Lascoux and
Sch\"utzenberger also determines a family of Demazure characters for which $T$
contributes its weight. In this paper we show that the final permutation in the
chain produced by the alcove model corresponds bijectively to the right key of
the tableau. From this it follows that the generating sets for the Demazure
characters produced by these two methods are equivalent.
| arxiv topic:math.CO math.RT |
arxiv_dataset-63331506.04856 | Three Upsilon Transforms Related to Tempered Stable Distributions
math.PR
We discuss the properties of three upsilon transforms, which are related to
the class of $p$-tempered $\alpha$-stable ($TS^p_\alpha$) distributions. In
particular, we characterize their domains and show how they can be represented
as compositions of each other. Further, we show that if
$-\infty<\beta<\alpha<2$ and $0<q<p<\infty$ then they can be used to transform
the L\'evy measures of $TS^p_\beta$ distributions into those of $TS^q_\alpha$.
| arxiv topic:math.PR |
arxiv_dataset-63341506.04956 | The Scope and Limits of Simulation in Cognitive Models
cs.AI
It has been proposed that human physical reasoning consists largely of
running "physics engines in the head" in which the future trajectory of the
physical system under consideration is computed precisely using accurate
scientific theories. In such models, uncertainty and incomplete knowledge is
dealt with by sampling probabilistically over the space of possible
trajectories ("Monte Carlo simulation"). We argue that such simulation-based
models are too weak, in that there are many important aspects of human physical
reasoning that cannot be carried out this way, or can only be carried out very
inefficiently; and too strong, in that humans make large systematic errors that
the models cannot account for. We conclude that simulation-based reasoning
makes up at most a small part of a larger system that encompasses a wide range
of additional cognitive processes.
| arxiv topic:cs.AI |
arxiv_dataset-63351506.05056 | Next-to-next-to-leading order gravitational spin-orbit coupling via the
effective field theory for spinning objects in the post-Newtonian scheme
gr-qc hep-th
We implement the effective field theory for gravitating spinning objects in
the post-Newtonian scheme at the next-to-next-to-leading order level to derive
the gravitational spin-orbit interaction potential at the third and a half
post-Newtonian order for rapidly rotating compact objects. From the
next-to-next-to-leading order interaction potential, which we obtain here in a
Lagrangian form for the first time, we derive straightforwardly the
corresponding Hamiltonian. The spin-orbit sector constitutes the most elaborate
spin dependent sector at each order, and accordingly we encounter a
proliferation of the relevant Feynman diagrams, and a significant increase of
the computational complexity. We present the evaluation of the interaction
potential, going over contributing Feynman diagrams. The computation is carried
out in terms of the nonrelativistic gravitational fields, together with the
various gauge choices included in the effective field theory for gravitating
spinning objects, which optimize the calculation. In addition, we automatize
the effective field theory computations, and carry out the automated
computations in parallel. Such automated effective field theory computations
would be most useful to obtain higher order post-Newtonian corrections. We
compare our Hamiltonian to the ADM Hamiltonian, and arrive at a complete
agreement between the ADM and effective field theory results. We provide
complete gauge invariant relations among the binding energy, angular momentum,
and orbital frequency of an inspiralling binary with generic compact spinning
components to third and a half post-Newtonian order. The derivation presented
here is essential to obtain further higher order post-Newtonian corrections,
and to reach the accuracy level required for the successful detection of
gravitational radiation.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-63361506.05156 | On multi-scale percolation behaviour of the effective conductivity for
the lattice model with interacting particles
cond-mat.stat-mech
Recently, the effective medium approach using 2x2 basic cluster of model
lattice sites to predict the conductivity of interacting droplets has been
presented by Hattori et al. To make a step aside from pure applications, we
have studied earlier a multi-scale percolation, employing any kxk basic cluster
for non-interacting particles. Here, with interactions included, we examine in
what way they alter the percolation threshold for any cluster case. We found
that at a fixed length scale k the interaction reduces the range of shifts of
the percolation threshold. To determine the critical concentrations, the
simplified model is used. It diminishes the number of local conductivities into
two main ones. In the presence of a dominance of the repulsive interaction over
the thermal energy, the exact percolation thresholds at scales k=2 and 3 can be
obtained from analytical formulas. Furthermore, by a simple reasoning, we
obtain the limiting threshold formula for odd k. When k>>1, the odd-even
difference becomes negligible. Hence, the 0.75 is the highest possible value of
the threshold.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-63371506.05256 | Existence of solitary-wave solutions to nonlocal equations
math.AP
We prove existence and conditional energetic stability of solitary-wave
solutions for the two classes of pseudodifferential equations $
u_t+\left(f(u)\right)_x-\left(L u\right)_x=0 $ and $
u_t+\left(f(u)\right)_x+\left(L u\right)_t=0, $ where $f$ is a nonlinear term,
typically of the form $c|u|^p$ or $cu|u|^{p-1}$, and $L$ is a Fourier
multiplier operator of positive order. The former class includes for instance
the Whitham equation with capillary effects and the generalized Korteweg-de
Vries equation, and the latter the Benjamin-Bona-Mahony equation. Existence and
conditional energetic stability results have earlier been established using the
method of concentration-compactness for a class of operators with symbol of
order $s\geq 1$. We extend these results to symbols of order $0<s<1$, thereby
improving upon the results for general operators with symbol of order $s\geq 1$
by enlarging both the class of linear operators and nonlinearities admitting
existence of solitary waves. Instead of using abstract operator theory, the new
results are obtained by direct calculations involving the nonlocal operator
$L$, something that gives us the bounds and estimates needed for the method of
concentration-compactness.
| arxiv topic:math.AP |
arxiv_dataset-63381506.05356 | Non-Gaussian forecasts of weak lensing with and without priors
astro-ph.CO astro-ph.IM
Assuming a Euclid-like weak lensing data set, we compare different methods of
dealing with its inherent parameter degeneracies. Including priors into a data
analysis can mask the information content of a given data set alone. However,
since the information content of a data set is usually estimated with the
Fisher matrix, priors are added in order to enforce an approximately Gaussian
likelihood. Here, we compare priorless forecasts to more conventional forecasts
that use priors. We find strongly non-Gaussian likelihoods for 2d-weak lensing
if no priors are used, which we approximate with the DALI-expansion. Without
priors, the Fisher matrix of the 2d-weak lensing likelihood includes unphysical
values of $\Omega_m$ and $h$, since it does not capture the shape of the
likelihood well. The Cramer-Rao inequality then does not need to apply. We find
that DALI and Monte Carlo Markov Chains predict the presence of a dark energy
with high significance, whereas a Fisher forecast of the same data set also
allows decelerated expansion. We also find that a 2d-weak lensing analysis
provides a sharp lower limit on the Hubble constant of $h > 0.4$, even if the
equation of state of dark energy is jointly constrained by the data. This is
not predicted by the Fisher matrix and usually masked in other works by a sharp
prior on $h$. Additionally, we find that DALI estimates Figures of Merit in the
presence of non-Gaussianities better than the Fisher matrix. We additionally
demonstrate how DALI allows switching to a Hamiltonian Monte Carlo sampling of
a highly curved likelihood with acceptance rates of $\approx 0.5$, an effective
covering of the parameter space, and numerically effectively costless leapfrog
steps. This shows how quick forecasts can be upgraded to accurate forecasts
whenever needed. Results were gained with the public code from
http://lnasellentin.github.io/DALI/
| arxiv topic:astro-ph.CO astro-ph.IM |
arxiv_dataset-63391506.05456 | A Lucky Imaging search for stellar sources near 74 transit hosts
astro-ph.SR
Many transiting planet host stars lack high resolution imaging and thus close
stellar sources can be missed. Those unknown stars potentially bias the
derivation of the planetary and stellar parameters from the transit light
curve, no matter if they are bound or not. In addition, bound stellar
companions interact gravitationally with the exoplanet host star, the disk and
the planets and can thus influence the formation and evolution of the planetary
system strongly. We extended our high-resolution Lucky Imaging survey for close
stellar sources by 74 transiting planet host stars. 39 of these stars lack
previous high-resolution imaging, 23 are follow up observations of companions
or companion candidates, and the remaining stars have been observed by others
with AO imaging though in different bands. We determine the separation of all
new and known companion candidates and estimate the flux ratio in the observed
bands. All observations were carried out with the Lucky Imaging camera AstraLux
Norte at the Calar Alto 2.2 m telescope in i' and z' passbands. We find new
stellar sources within 1 arcsec to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, and
WASP-103, and between 1 and 4 arcsec to HAT-P-29 and WASP-56.
| arxiv topic:astro-ph.SR |
arxiv_dataset-63401506.05556 | Hints of the jet composition in gamma-ray bursts from dissipative
photosphere models
astro-ph.HE
We present a model for gamma-ray bursts where a dissipative photosphere
provides the usual spectral peak around MeV energies accompanied by a
subdominant thermal component. We treat the initial acceleration of the jet in
a general way, allowing for magnetic field- and baryon dominated outflows. In
this model, the GeV emission associated with GRBs observed by Fermi LAT, arises
as the interaction of photospheric radiation and the shocked electrons at the
deceleration radius. Through recently discovered correlations between the
thermal and non-thermal peaks within individual bursts, we are able to infer
whether the jet was Poynting flux or baryon dominated.
| arxiv topic:astro-ph.HE |
arxiv_dataset-63411506.05656 | Helium reionization in the presence of self-annihilating clumpy dark
matter
astro-ph.CO
The reionization of helium describes the transition from its singly ionized
state to a doubly-ionized state in the intergalactic medium (IGM). This process
is important for the thermal evolution of the IGM and influences the mean free
path of photons with energies above $54.4$~eV. While it is well-known that
helium reionization is mostly driven by the contribution of energetic quasars
at $z<6$, we study here how helium reionization proceeds if there is an
additional contribution due to the annihilation of dark matter. We explore the
effects of different dark matter profiles for the dark matter clumping factor,
which can significantly enhance the annihilation rate at late times. We find
that the presence of dark matter annihilation enhances the He$^{++}$ abundance
at early stages where it would be zero within the standard model, and it can
further increase during structure formation, reflecting the increase of the
dark matter clumping factor. The latter is, however, degenerate with the
build-up of the quasar contribution, and we therefore expect no significant
changes at late times. We expect that future studies of the He$^+$ Lyman
$\alpha$ forest may help to assess whether the evolution is consistent with the
contribution from quasars alone, or if an additional component may be required.
| arxiv topic:astro-ph.CO |
arxiv_dataset-63421506.05756 | A simple criterion for the existence of nonreal eigenvalues for a class
of 2D and 3D Pauli operators
math.SP math-ph math.AP math.MP
In this work, we investigate the discrete spectrum generated by complex
matrix-valued perturbations for a class of 2D and 3D Pauli operators with
nonconstant magnetic fields. We establish a simple criterion for the potentials
to produce discrete spectrum near the low ground energy of the operators.
Moreover, in case of creation of nonreal eigenvalues, this criterion specifies
also their location.
| arxiv topic:math.SP math-ph math.AP math.MP |
arxiv_dataset-63431506.05856 | Simulating nanoscale heat transport
cond-mat.mtrl-sci
In this book chapter we provide the definition of "Simulating Nanoscale Heat
Transport", broadly regarded as modeling heat conduction beyond Fourier's law.
We primarely focus on incoherent transport, which is dominated by scattering
between phonons and the boundaries of a given material. After introducing the
Boltzmann Transport Equation (BTE) for phonons, we elaborate on different
numerical techniques for solving nanoscale heat transport includind
deterministic and Monte Carlo based method. A discussion on the need for
multiscale modeling concludes the chapter.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-63441506.05956 | Recovering p-adic valuations from pro-p Galois groups
math.NT
Let $K$ be a field with $G_K(2) \simeq G_{\mathbb{Q}}(2)$, where $G_F(2)$
denotes the maximal pro-2 quotient of the absolute Galois group of a field $F$.
We prove that then $K$ admits a (non-trivial) valuation $v$ which is
2-henselian and has residue field $\mathbb{F}_2$. Furthermore, $v(2)$ is a
minimal positive element in the value group $\Gamma_v$ and
$[\Gamma_v:2\Gamma_v]=2$. This forms the first positive result on a more
general conjecture about recovering $p$-adic valuations from pro-$p$ Galois
groups which we formulate precisely. As an application, we show how this result
can be used to easily obtain number-theoretic information, by giving an
independent proof of a strong version of the birational section conjecture for
smooth, complete curves $X$ over $\mathbb{Q}_2$, as well as an analogue for
varieties.
| arxiv topic:math.NT |
arxiv_dataset-63451506.06056 | Sequential Warped Products: Curvature and Killing Vector Fields
math.DG
In this note, we introduce a new type of warped products called as sequential
warped products to cover a wider variety of exact solutions to Einstein's
equation. First, we study the geometry of sequential warped products and obtain
covariant derivatives, curvature tensor, Ricci curvature and scalar curvature
formulas. Then some important consequences of these formulas are also stated.
We provide characterizations of geodesics and two different types of conformal
vector fields, namely, Killing vector fields and concircular vector fields on
sequential warped product manifolds. Finally, we consider the geometry of two
classes of sequential warped product space-time models which are sequential
generalized Robertson-Walker spacetimes and sequential standard static
spacetimes.
| arxiv topic:math.DG |
arxiv_dataset-63461506.06156 | A novel ZnO piezoelectric microcantilever energy scavenger: Fabrication
and characterization
cond-mat.mes-hall
This novel piezoelectric zinc oxide (ZnO) thin film microcantilever was
fabricated by micromachining technique. To release the cantilever, wet
anisotropic etching of Silicon (Si) was performed by tetramethyl ammonium
hydroxide (TMAH). The transverse piezoelectric coefficient d31 of the ZnO film,
obtained from the deflection of the cantilever with influence of applied
voltage, was calculated as 3.32 pC/N. The observed dynamic characterization of
the novel piezoelectric microcantilever had linear response with the applied
driving voltage. The obtained values of Young Modulus and Hardness were 208 +4
GPa and 4.84+ 0.1 GPa respectively. This inexpensive novel method provides
additional design flexibility to fabricate vibrational energy harvesters. The
easy steps of fabrication and cost effectiveness of this method may be
preferred it over DRIE. The voltage induced due to deformation of ZnO
cantilever were measured ~230mV. This microcantilever energy scavenger may be
used to power the nano devices and sensors for medical and agricultural
applications as a replacement of traditional bulky batteries.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-63471506.06256 | Collective Mind, Part II: Towards Performance- and Cost-Aware Software
Engineering as a Natural Science
cs.SE cs.LG cs.PF
Nowadays, engineers have to develop software often without even knowing which
hardware it will eventually run on in numerous mobile phones, tablets,
desktops, laptops, data centers, supercomputers and cloud services.
Unfortunately, optimizing compilers are not keeping pace with ever increasing
complexity of computer systems anymore and may produce severely underperforming
executable codes while wasting expensive resources and energy.
We present our practical and collaborative solution to this problem via
light-weight wrappers around any software piece when more than one
implementation or optimization choice available. These wrappers are connected
with a public Collective Mind autotuning infrastructure and repository of
knowledge (c-mind.org/repo) to continuously monitor various important
characteristics of these pieces (computational species) across numerous
existing hardware configurations together with randomly selected optimizations.
Similar to natural sciences, we can now continuously track winning solutions
(optimizations for a given hardware) that minimize all costs of a computation
(execution time, energy spent, code size, failures, memory and storage
footprint, optimization time, faults, contentions, inaccuracy and so on) of a
given species on a Pareto frontier along with any unexpected behavior. The
community can then collaboratively classify solutions, prune redundant ones,
and correlate them with various features of software, its inputs (data sets)
and used hardware either manually or using powerful predictive analytics
techniques. Our approach can then help create a large, realistic, diverse,
representative, and continuously evolving benchmark with related optimization
knowledge while gradually covering all possible software and hardware to be
able to predict best optimizations and improve compilers and hardware depending
on usage scenarios and requirements.
| arxiv topic:cs.SE cs.LG cs.PF |
arxiv_dataset-63481506.06356 | Absorption of an electron by a dielectric wall
physics.plasm-ph
We introduce a method for calculating the probability with which a low-energy
electron hitting the wall of a plasma gets stuck in it and apply the method to
a dielectric wall with positive electron affinity smaller than the bandgap
using MgO as an example. In accordance with electron beam scattering data we
obtain energy-dependent sticking probabilities significantly less than unity
and question thereby for electrons the perfect absorber assumption unisono used
in plasma modeling.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-63491506.06456 | An $O(n^{0.4732})$ upper bound on the complexity of the GKS
communication game
cs.CC
We give an $5\cdot n^{\log_{30}5}$ upper bund on the complexity of the
communication game introduced by G. Gilmer, M. Kouck\'y and M. Saks \cite{saks}
to study the Sensitivity Conjecture \cite{linial}, improving on their
$\sqrt{999\over 1000}\sqrt{n}$ bound. We also determine the exact complexity of
the game up to $n\le 9$.
| arxiv topic:cs.CC |
arxiv_dataset-63501506.06556 | Beyond the Dark matter effective field theory and a simplified model
approach at colliders
hep-ph hep-ex
Direct detection of and LHC search for the singlet fermion dark matter (SFDM)
model with Higgs portal interaction are considered in a renormalizable model
where the full Standard Model (SM) gauge symmetry is imposed by introducing a
singlet scalar messenger. In this model, direct detection is described by an
effective operator m_q \bar{q} q \bar{\chi} \chi as usual, but the full
amplitude for monojet + \not E_T involves two intermediate scalar propagators,
which cannot be seen within the effective field theory (EFT) or in the
simplified model without the full SM gauge symmetry. We derive the collider
bounds from the ATLAS monojet + \not E_T as well as the CMS t\bar{t} + \not E_T
data, finding out that the bounds and the interpretation of the results are
completely different from those obtained within the EFT or simplified models.
It is pointed out that it is important to respect unitarity, renormalizability
and local gauge invariance of the SM.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-63511506.06656 | An optimization-based reformulation of the classical displacement
approach for state update of non-linear material models
math.OC math.NA
In this paper, we build on recent work using a mathematical programming
approach for incremental state update in analysis of non-linear mechanics
models. In particular, we consider quasi-static analysis of continuum problems
in the linearized kinematics regime, with non-linear material models described
using convex energy functions. We find in this case that the classical
displacement-based nested approach for incremental state update can be
reformulated as solving a reduced dual optimization problem. This reformulation
provides insights into the working of the algorithm, and eliminates the need
for some heuristics. An important purpose of this paper is to further
illustrate the unifying nature of the mathematical programming approach. We
therefore present relationships with several of these types of algorithms
recently presented in the literature for incremental state update.
| arxiv topic:math.OC math.NA |
arxiv_dataset-63521506.06756 | F-theory at order $\alpha'^3$
hep-th
We study the effective physics of F-theory at order $\alpha'^3$ in derivative
expansion. We show that the ten-dimensional type IIB eight-derivative couplings
involving the graviton and the axio-dilaton naturally descend from pure gravity
in twelve dimensions. Upon compactification on elliptically fibered Calabi-Yau
fourfolds, the non-trivial vacuum profile for the axio-dilaton leads to a new,
genuinely N=1, $\alpha'^3$ correction to the four-dimensional effective action.
| arxiv topic:hep-th |
arxiv_dataset-63531506.06856 | Semi-phenomenological analysis of neutron scattering results for
quasi-two dimensional quantum anti-ferromagnet
cond-mat.str-el
The available results from the inelastic neutron scattering experiment
performed on the quasi-two dimensional spin $\frac{1}{2}$ anti-ferromagnetic
material $La_2 Cu O_4$ have been analysed theoretically. The formalism of ours
is based on a semi-classical like treatment involving a model of an ideal gas
of mobile vortices and anti-vortices built on the background of the
N$\acute{e}$el state, using the bipartite classical spin configuration
corresponding to an XY- anisotropic Heisenberg anti-ferromagnet on a square
lattice. The results for the integrated intensities for our spin $\frac{1}{2}$
model corresponding to different temperatures, show occurrence of vigorous
unphysical oscillations, when convoluted with a realistic spectral window
function. These results indicate failure of the conventional semi-classical
theoretical model of ideal vortex/anti-vortex gas arising in the
Berezinskii-Kosterlitz-Thouless theory for the low spin magnetic systems. A
full fledged quantum mechanical formalism and calculations seem crucial for the
understanding of topological excitations in such low spin systems. Furthermore,
a severe disagreement is found to occur at finite values of energy transfer
between the integrated intensities obtained theoretically from the conventional
formalism and those obtained experimentally. This further suggests strongly
that the full quantum treatment should also incorporate the interaction between
the fragile-magnons and the topological excitations. This is quite plausible in
view of the recent work establishing such a process in XXZ quantum ferromagnet
on 2D lattice. The high spin XXZ quasi-two dimensional antiferromagnet like
$MnPS_3$ however follows the conventional theory quite well
| arxiv topic:cond-mat.str-el |
arxiv_dataset-63541506.06956 | Weighted bound for commutators
math.CA
Let $K$ be the Calder\'on-Zygmund convolution kernel on $\mathbb{R}^d
(d\geq2)$. Define the commutator associated with $K$ and $a\in
L^\infty(\mathbb{R}^d)$ by \[ T_af(x)=p.v. \int K(x-y)m_{x,y}a\cdot f(y)dy. \]
Recently, Grafakos and Honz\'{\i}k [5] proved that $T_a$ is of weak type (1,1)
for $d=2$. In this paper, we show that $T_a$ is also weighted weak type (1,1)
with the weight $|x|^\alpha\,(-2<\alpha <0)$ for $d=2$. Moreover, we prove that
$T_a$ is bounded on weighted $L^p(\mathbb{R}^d)\,(1<p<\infty)$ for all $d\ge2$.
| arxiv topic:math.CA |
arxiv_dataset-63551506.07056 | Lubell mass and induced partially ordered sets
math.CO
We prove that for every partially ordered set $P$, there exists $c(P)$ such
that every family $\mathcal{F}$ of subsets of $[n]$ ordered by inclusion and
which contains no induced copy of $P$ satisfies $\sum_{F\in
\mathcal{F}}1/{n\choose |F|}\leq c(P)$. This confirms a conjecture of Lu and
Milans.
| arxiv topic:math.CO |
arxiv_dataset-63561506.07156 | Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi
gases
cond-mat.quant-gas cond-mat.str-el cond-mat.supr-con nucl-th
We present a theoretical study of the ground state of the BCS-BEC crossover
in dilute two-dimensional Fermi gases. While the mean-field theory provides a
simple and analytical equation of state, the pressure is equal to that of a
noninteracting Fermi gas in the entire BCS-BEC crossover, which is not
consistent with the features of a weakly interacting Bose condensate in the BEC
limit and a weakly interacting Fermi liquid in the BCS limit. The inadequacy of
the 2D mean-field theory indicates that the quantum fluctuations are much more
pronounced than those in 3D. In this work, we show that the inclusion of the
Gaussian quantum fluctuations naturally recovers the above features in both the
BEC and the BCS limits. In the BEC limit, the missing logarithmic dependence on
the boson chemical potential is recovered by the quantum fluctuations. Near the
quantum phase transition from the vacuum to the BEC phase, we compare our
equation of state with the known grand canonical equation of state of 2D Bose
gases and determine the ratio of the composite boson scattering length $a_{\rm
B}$ to the fermion scattering length $a_{\rm 2D}$. We find $a_{\rm B}\simeq
0.56 a_{\rm 2D}$, in good agreement with the exact four-body calculation. We
compare our equation of state in the BCS-BEC crossover with recent results from
the quantum Monte Carlo simulations and the experimental measurements and find
good agreements.
| arxiv topic:cond-mat.quant-gas cond-mat.str-el cond-mat.supr-con nucl-th |
arxiv_dataset-63571506.07256 | Enumeration of standard Young tableaux of shifted strips with constant
width
math.CO
Let $g_{n_1,n_2}$ be the number of standard Young tableau of truncated
shifted shape with $n_1$ rows and $n_2$ boxes in each row. By using of the
integral method this paper derives the recurrence relations of $g_{3,n}$,
$g_{n,4}$ and $g_{n,5}$ respectively. Specially, $g_{n,4}$ is the $(2n-1)$-st
Pell number.
| arxiv topic:math.CO |
arxiv_dataset-63581506.07356 | 3d N=1 effective supergravity and F-theory from M-theory on fourfolds
hep-th
We consider 3d N=1 M-theory compactifications on Calabi-Yau fourfolds, and
the effective 3d theory of light modes obtained by reduction from eleven
dimensions. We study in detail the mass spectrum at the vacuum and, by
decoupling the massive multiplets, we derive the effective 3d N=1 theory in the
large-volume limit up to quartic fermion terms. We show that in general it is
an ungauged N=1 supergravity of the form expected from 3d supersymmetry. In
particular the massless bosonic fields consist of the volume modulus and the
axions originating from the eleven-dimensional three-form, while the
moduli-space metric is locally isometric to hyperbolic space. We consider the
F-theory interpretation of the 3d N=1 M-theory vacua in the light of the
F-theory effective action approach. We show that these vacua generally have
F-theory duals with circle fluxes, thus breaking 4d Poincar\'e invariance.
| arxiv topic:hep-th |
arxiv_dataset-63591506.07456 | Comparisons of two quantile regression smoothers
stat.ME
The paper compares the small-sample properties of two non-parametric quantile
regression estimators. The first is based on constrained B-spline smoothing
(COBS) and the other is based on a variation and slight extension of a running
interval smoother, which apparently has not been studied via simulations. The
motivation for this paper stems from the Well Elderly 2 study, a portion of
which was aimed at understanding the association between the cortisol awakening
response and two measures of stress.
COBS indicated what appeared be an usual form of curvature. The modified
running interval smoother gave a strikingly different estimate, which raised
the issue of how it compares to COBS in terms of mean squared error and bias as
well as its ability to avoid a spurious indication of curvature. R functions
for applying the methods were used in conjunction with default settings for the
various optional arguments. The results indicate that the modified running
interval smoother has practical value. Manipulation of the optional arguments
might impact the relative merits of the two methods, but the extent to which
this is the case remains unknown.
| arxiv topic:stat.ME |
arxiv_dataset-63601506.07556 | Effects of anisotropy and disorder on the conductivity of Weyl
semimetals
cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.str-el
We study dc conductivity of a Weyl semimetal with uniaxial anisotropy (Fermi
velocity ratio $\xi= v_\bot/v_\parallel\neq1$) considering the scattering of
charge carriers by a wide class of impurity potentials, both short- and
long-range. We obtain the ratio of transverse and longitudinal (with respect to
the anisotropy axis) conductivities as a function of both $\xi$ and
temperature. We find that the transverse and longitudinal conductivities
exhibit different temperature dependence in the case of short-range disorder.
For general long-range disorder, the temperature dependence ($\sim T^4$) of the
conductivity turns out to be insensitive of the anisotropy in the limits of
strong ($\xi\gg$ and $\ll1$) and weak ($\xi\approx1$) anisotropy.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.str-el |
arxiv_dataset-63611506.07656 | DeepMatching: Hierarchical Deformable Dense Matching
cs.CV
We introduce a novel matching algorithm, called DeepMatching, to compute
dense correspondences between images. DeepMatching relies on a hierarchical,
multi-layer, correlational architecture designed for matching images and was
inspired by deep convolutional approaches. The proposed matching algorithm can
handle non-rigid deformations and repetitive textures and efficiently
determines dense correspondences in the presence of significant changes between
images. We evaluate the performance of DeepMatching, in comparison with
state-of-the-art matching algorithms, on the Mikolajczyk (Mikolajczyk et al
2005), the MPI-Sintel (Butler et al 2012) and the Kitti (Geiger et al 2013)
datasets. DeepMatching outperforms the state-of-the-art algorithms and shows
excellent results in particular for repetitive textures.We also propose a
method for estimating optical flow, called DeepFlow, by integrating
DeepMatching in the large displacement optical flow (LDOF) approach of Brox and
Malik (2011). Compared to existing matching algorithms, additional robustness
to large displacements and complex motion is obtained thanks to our matching
approach. DeepFlow obtains competitive performance on public benchmarks for
optical flow estimation.
| arxiv topic:cs.CV |
arxiv_dataset-63621506.07756 | General fixed points of quasi-local frustration-free quantum semigroups:
from invariance to stabilization
quant-ph
We investigate under which conditions a mixed state on a finite-dimensional
multipartite quantum system may be the unique, globally stable fixed point of
frustration-free semigroup dynamics subject to specified quasi-locality
constraints. Our central result is a linear-algebraic necessary and sufficient
condition for a generic (full-rank) target state to be frustration-free
quasi-locally stabilizable, along with an explicit procedure for constructing
Markovian dynamics that achieve stabilization. If the target state is not
full-rank, we establish sufficiency under an additional condition, which is
naturally motivated by consistency with pure-state stabilization results yet
provably not necessary in general. Several applications are discussed, of
relevance to both dissipative quantum engineering and information processing,
and non-equilibrium quantum statistical mechanics. In particular, we show that
a large class of graph product states (including arbitrary thermal graph
states) as well as Gibbs states of commuting Hamiltonians are frustration-free
stabilizable relative to natural quasi-locality constraints. Likewise, we
provide explicit examples of non-commuting Gibbs states and non-trivially
entangled mixed states that are stabilizable despite the lack of an underlying
commuting structure, albeit scalability to arbitrary system size remains in
this case an open question.
| arxiv topic:quant-ph |
arxiv_dataset-63631506.07856 | Dielectric susceptibility of magnetoelectric thin films with
vortex-antivortex dipole pairs
cond-mat.str-el
We consider model of quasi-2D magnetoelectric material as XY model for spin
system on a lattice with local multiferroic-like interaction of spin and
electric polarization vectors. We calculate the contribution of magnetic (spin)
vortex-antivortex pairs (which form electric dipoles) to the dielectric
susceptibility of the system. We show that in approximation of non-interacting
pairs at $T \rightarrow T_{BKT}$ (Berezinskii-Kosterlitz-Thouless temperature)
dielectric susceptibility diverges.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-63641506.07956 | Extended Goldberger-Treiman relation obtained in a three-flavor parity
doublet model
hep-ph nucl-th
We study masses and decay widths of positive and negative parity nucleons
using a three-flavor parity doublet model, in which we introduce three
representations, $\left[({\bf 3} , \bar{{\bf 3}})\oplus (\bar{{\bf 3}} , {\bf
3})\right]$, $\left[({\bf 3} , {\bf 6}) \oplus ({\bf 6}, {\bf 3})\right]$, and
$\left[({\bf 8} , {\bf 1}) \oplus ({\bf 1} , {\bf 8})\right]$ of the chiral
U$(3)_{\rm L}\times$U$(3)_{\rm R}$ symmetry. We find an extended version of the
Goldberger-Treiman relation among the mass differences and the coupling
constants for pionic transitions. This relation leads to an upper bound for the
decay width of $N(1440) \rightarrow N(939) + \pi$ independently of the model
parameters. We perform the numerical fitting of the model parameters and derive
several predictions, which can be tested in future experiments or lattice QCD
analysis. Furthermore, when we use the axial coupling of the excited nucleons
obtained from lattice QCD analyses as inputs, we find that the ground state
nucleon $N(939)$ consists of about 80% of $\left[({\bf 3} , {\bf 6}) \oplus
({\bf 6}, {\bf 3})\right]$ component, and that the chiral invariant mass of
$N(939)$ is roughly $500$ -- $800$MeV.
| arxiv topic:hep-ph nucl-th |
arxiv_dataset-63651506.08056 | Berkelian Idealism Regarding Properties in Orthodox Quantum Mechanics,
and Implications for Quantum Gravity
physics.gen-ph quant-ph
Referring to the 18th century idealism of George Berkeley in which an object
exists if and only if it is observed, this note shows that orthodox quantum
mechanics (OQM) entails a Berkelian idealism regarding properties (BIRP): a
quantum `has' a property X with quantitative value x if and only if the
property X has just been measured with outcome x. It is then impossible to
recontextualize GR's principle of curvature in any quantum framework that
implies this BIRP, for a quantum cannot curve space-time if it doesn't have a
definite energy - which is supposed to be the cause of curvature - in absence
of observation to begin with. Concluding, it is ruled out that a quantum theory
of gravity, in which GR's principle of curvature is built in as a fundamental
physical principle, can be developed in any framework implying this BIRP.
| arxiv topic:physics.gen-ph quant-ph |
arxiv_dataset-63661506.08156 | Classical solutions of a flag manifold sigma-model
hep-th math.DG
We study a sigma-model with target space the flag manifold U(3)/U(1)^3. A
peculiarity of the model is that the complex structure on the target space
enters explicitly in the action. We describe the classical solutions of the
model for the case when the worldsheet is a sphere CP^1.
| arxiv topic:hep-th math.DG |
arxiv_dataset-63671506.08256 | Gaussian Process Regression with Location Errors
stat.ME math.ST stat.AP stat.TH
In this paper, we investigate Gaussian process regression models where inputs
are subject to measurement error. In spatial statistics, input measurement
errors occur when the geographical locations of observed data are not known
exactly. Such sources of error are not special cases of "nugget" or microscale
variation, and require alternative methods for both interpolation and parameter
estimation. Gaussian process models do not straightforwardly extend to
incorporate input measurement error, and simply ignoring noise in the input
space can lead to poor performance for both prediction and parameter inference.
We review and extend existing theory on prediction and estimation in the
presence of location errors, and show that ignoring location errors may lead to
Kriging that is not "self-efficient". We also introduce a Markov Chain Monte
Carlo (MCMC) approach using the Hybrid Monte Carlo algorithm that obtains
optimal (minimum MSE) predictions, and discuss situations that lead to
multimodality of the target distribution and/or poor chain mixing. Through
simulation study and analysis of global air temperature data, we show that
appropriate methods for incorporating location measurement error are essential
to valid inference in this regime.
| arxiv topic:stat.ME math.ST stat.AP stat.TH |
arxiv_dataset-63681506.08356 | Temporal Analysis of Dissipative Structures in Magnetohydrodynamic
Turbulence
astro-ph.HE astro-ph.SR physics.flu-dyn physics.plasm-ph physics.space-ph
Energy dissipation is highly intermittent in turbulent plasmas, being
localized in coherent structures such as current sheets. The statistical
analysis of spatial dissipative structures is an effective approach to studying
turbulence. In this paper, we generalize this methodology to investigate
four-dimensional spatiotemporal structures, i.e., dissipative processes
representing sets of interacting coherent structures, which correspond to
flares in astrophysical systems. We develop methods for identifying and
characterizing these processes, and then perform a statistical analysis of
dissipative processes in numerical simulations of driven magnetohydrodynamic
turbulence. We find that processes are often highly complex, long-lived, and
weakly asymmetric in time. They exhibit robust power-law probability
distributions and scaling relations, including a distribution of dissipated
energy with power-law index near -1.75, indicating that intense dissipative
events dominate the overall energy dissipation. We compare our results with the
previously observed statistical properties of solar flares.
| arxiv topic:astro-ph.HE astro-ph.SR physics.flu-dyn physics.plasm-ph physics.space-ph |
arxiv_dataset-63691506.08456 | Asymptotic behavior of interface solutions to quasilinear parabolic
equations with nonlinear forcing terms
math.AP
We investigate the asymptotic behavior of solutions for quasilinear parabolic
equations in bounded intervals. In particular, we are concerned with a special
class of solutions, called interface solutions, which exhibit e metastable
behavior, meaning that their convergence towards the asymptotic configuration
of the system is exponentially slow. The key of our analysis is a linearization
around an approximation of the steady state of the problem, and the reduction
of the dynamics to a one-dimensional motion, describing the slow convergence of
the interfaces towards the equilibrium.
| arxiv topic:math.AP |
arxiv_dataset-63701506.08556 | The impact of beam deconvolution on noise properties in CMB
measurements: Application to Planck LFI
astro-ph.IM astro-ph.CO
We present an analysis of the effects of beam deconvolution on noise
properties in CMB measurements. The analysis is built around the artDeco beam
deconvolver code. We derive a low-resolution noise covariance matrix that
describes the residual noise in deconvolution products, both in harmonic and
pixel space. The matrix models the residual correlated noise that remains in
time-ordered data after destriping, and the effect of deconvolution on it. To
validate the results, we generate noise simulations that mimic the data from
the Planck LFI instrument. A $\chi^2$ test for the full 70 GHz covariance in
multipole range $\ell=0-50$ yields a mean reduced $\chi^2$ of 1.0037. We
compare two destriping options, full and independent destriping, when
deconvolving subsets of available data. Full destriping leaves substantially
less residual noise, but leaves data sets intercorrelated. We derive also a
white noise covariance matrix that provides an approximation of the full noise
at high multipoles, and study the properties on high-resolution noise in pixel
space through simulations.
| arxiv topic:astro-ph.IM astro-ph.CO |
arxiv_dataset-63711506.08656 | Measurement of the production of neighbouring jets in lead-lead
collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV with the ATLAS detector
hep-ex nucl-ex
This Letter presents measurements of correlated production of nearby jets in
Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV using the ATLAS
detector at the Large Hadron Collider. The measurement was performed using 0.14
${\rm nb}^{-1}$ of data recorded in 2011. The production of correlated jet
pairs was quantified using the rate, $R_{\Delta R}$, of "neighbouring" jets
that accompany "test" jets within a given range of angular distance, $\Delta
R$, in the pseudorapidity--azimuthal angle plane. The jets were measured in the
ATLAS calorimeter and were reconstructed using the anti-$k_{t}$ algorithm with
radius parameters $d = 0.2$, $0.3$, and $0.4$. $R_{\Delta R}$ was measured in
different Pb+Pb collision centrality bins, characterized by the total
transverse energy measured in the forward calorimeters. A centrality dependence
of $R_{\Delta R}$ is observed for all three jet radii with $R_{\Delta R}$ found
to be lower in central collisions than in peripheral collisions. The ratios
formed by the $R_{\Delta R}$ values in different centrality bins and the values
in the 40-80 % centrality bin are presented.
| arxiv topic:hep-ex nucl-ex |
arxiv_dataset-63721506.08756 | Small-amplitude nonlinear modes under the combined effect of the
parabolic potential, nonlocality and ${\cal PT}$ symmetry
nlin.PS
We consider nonlinear modes of the nonlinear Schr\"odinger equation with a
nonlocal nonlinearity and an additional PT-symmetric parabolic potential. We
show that there exists a set of continuous families of nonlinear modes and
study their linear stability in the limit of small nonlinearity. It is
demonstrated that either PT symmetry or the nonlocality can be used to manage
the stability of the small-amplitude nonlinear modes. The stability properties
are also found to depend on the particular shape of the nonlocal kernel.
Additional numerical simulations show that the stability results remain valid
not only for the infinitesimally small nonlinear modes, but also for the modes
of finite amplitude
| arxiv topic:nlin.PS |
arxiv_dataset-63731506.08856 | Development of a dry linear compressor for GM and pulse tube cryocoolers
physics.ins-det
Pressure Wave Systems GmbH has developed a dry compressor for GM and pulse
tube cryocoolers. The concept is based on hydraulically driven metal bellows in
which the Helium working gas is compressed. The system is operated in the
region of 1 kW of electrical input power and has been successfully tested with
a SHI RDK-101D GM cryocooler cold head. Set-up, performance and reliability of
the compressor system will be discussed.
| arxiv topic:physics.ins-det |
arxiv_dataset-63741506.08956 | Lens Factory: Automatic Lens Generation Using Off-the-shelf Components
cs.GR cs.CV
Custom optics is a necessity for many imaging applications. Unfortunately,
custom lens design is costly (thousands to tens of thousands of dollars), time
consuming (10-12 weeks typical lead time), and requires specialized optics
design expertise. By using only inexpensive, off-the-shelf lens components the
Lens Factory automatic design system greatly reduces cost and time. Design,
ordering of parts, delivery, and assembly can be completed in a few days, at a
cost in the low hundreds of dollars. Lens design constraints, such as focal
length and field of view, are specified in terms familiar to the graphics
community so no optics expertise is necessary. Unlike conventional lens design
systems, which only use continuous optimization methods, Lens Factory adds a
discrete optimization stage. This stage searches the combinatorial space of
possible combinations of lens elements to find novel designs, evolving simple
canonical lens designs into more complex, better designs. Intelligent pruning
rules make the combinatorial search feasible. We have designed and built
several high performance optical systems which demonstrate the practicality of
the system.
| arxiv topic:cs.GR cs.CV |
arxiv_dataset-63751506.09056 | Carbon-rich presolar grains from massive stars. Subsolar 12C/13C and
14N/15N ratios and the mystery of 15N
astro-ph.SR
Carbon-rich grains with isotopic anomalies compared to the Sun are found in
primitive meteorites. They were made by stars, and carry the original stellar
nucleosynthesis signature. Silicon carbide grains of Type X and C, and
low-density graphites condensed in the ejecta of core-collapse supernovae. We
present a new set of models for the explosive He shell and compare them with
the grains showing 12C/13C and 14N/15N ratios lower than solar. In the stellar
progenitor H was ingested into the He shell and not fully destroyed before the
explosion. Different explosion energies and H concentrations are considered. If
the SN shock hits the He-shell region with some H still present, the models can
reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle
isotopic signatures are obtained, including a large production of 13C and 15N.
The short-lived radionuclides 22Na and 26Al are increased by orders of
magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He
shell might solve the puzzle of the Ne-E(L) component in low-density graphite
grains. This scenario is attractive for the SiC grains of type AB with 14N/15N
ratios lower than solar, and provides an alternative solution for SiC grains
originally classified as nova grains. Finally, this process may contribute to
the production of 14N and 15N in the Galaxy, helping to produce the 14N/15N
ratio in the solar system.
| arxiv topic:astro-ph.SR |
arxiv_dataset-63761506.09156 | The ERA Method with Idealizing PSF for Precise Weak Gravitational
Lensing Shear Analysis
astro-ph.CO
We generalize ERA method of PSF correction for more realistic situations. The
method re-smears the observed galaxy image(galaxy image smeared by PSF) and PSF
image by an appropriate function called Re-Smearing Function(RSF) to make new
images which have the same ellipticity with the lensed (before smeared by PSF)
galaxy image. It has been shown that the method avoids a systematic error
arising from an approximation in the usual PSF correction in moment method such
as KSB for simple PSF shape. By adopting an idealized PSF we generalize ERA
method applicable for arbitrary PSF. This is confirmed with simulated complex
PSF shapes. We also consider the effect of pixel noise and found that the
effect causes systematic overestimation.
| arxiv topic:astro-ph.CO |
arxiv_dataset-63771507.00039 | Selective Inference and Learning Mixed Graphical Models
stat.ML cs.LG
This thesis studies two problems in modern statistics. First, we study
selective inference, or inference for hypothesis that are chosen after looking
at the data. The motiving application is inference for regression coefficients
selected by the lasso. We present the Condition-on-Selection method that allows
for valid selective inference, and study its application to the lasso, and
several other selection algorithms.
In the second part, we consider the problem of learning the structure of a
pairwise graphical model over continuous and discrete variables. We present a
new pairwise model for graphical models with both continuous and discrete
variables that is amenable to structure learning. In previous work, authors
have considered structure learning of Gaussian graphical models and structure
learning of discrete models. Our approach is a natural generalization of these
two lines of work to the mixed case. The penalization scheme involves a novel
symmetric use of the group-lasso norm and follows naturally from a particular
parametrization of the model. We provide conditions under which our estimator
is model selection consistent in the high-dimensional regime.
| arxiv topic:stat.ML cs.LG |
arxiv_dataset-63781507.00139 | Bounds on genus and configurations of embedded surfaces in 4-manifolds
math.GT math.DG
For several embedded surfaces with zero self-intersection number in
4-manifolds, we show that an adjunction-type genus bound holds for at least one
of the surfaces under certain conditions. For example, we derive certain
adjunction inequalities for surfaces embedded in $m\mathbb{CP}^2\#
n(-\mathbb{CP}^2)$ ($m, n \geq 2$). The proofs of these results are given by
studying a family of Seiberg-Witten equations.
| arxiv topic:math.GT math.DG |
arxiv_dataset-63791507.00239 | Arbitrarily long relativistic bit commitment
quant-ph cs.CR
We consider the recent relativistic bit commitment protocol introduced by
Lunghi et al. [Phys. Rev. Lett. 2015] and present a new security analysis
against classical attacks. In particular, while the initial complexity of the
protocol scaled double-exponentially with the commitment time, our analysis
shows that the correct dependence is only linear. This has dramatic
implications in terms of implementation: in particular, the commitment time can
easily be made arbitrarily long, by only requiring both parties to communicate
classically and perform efficient classical computation.
| arxiv topic:quant-ph cs.CR |
arxiv_dataset-63801507.00339 | Quantization of BMS$_3$ orbits: a perturbative approach
hep-th math-ph math.MP
We compute characters of the BMS group in three dimensions. The approach is
the same as that performed by Witten in the case of coadjoint orbits of the
Virasoro group in the eighties, within the large central charge approximation.
The procedure involves finding a Poisson bracket between classical variables
and the corresponding commutator of observables in a Hilbert space, explaining
why we call this a quantization. We provide first a pedagogical warm up by
applying the method to both SL(2,R) and Poincar\'{e}3 groups. As for BMS3, our
results coincide with the characters of induced representations recently
studied in the literature. Moreover, we relate the 'coadjoint representations'
to the induced representations.
| arxiv topic:hep-th math-ph math.MP |
arxiv_dataset-63811507.00439 | Giant osmotic pressure in the forced wetting of hydrophobic nanopores
cond-mat.soft
The forced intrusion of water in hydrophobic nanoporous pulverulent material
is of interest for quick storage of energy. With nanometric pores the energy
storage capacity is controlled by interfacial phenomena. With subnanometric
pores, we demonstrate that a breakdown occurs with the emergence of molecular
exclusion as a leading contribution. This bulk exclusion effect leads to an
osmotic contribution to the pressure that can reach levels never previously
sustained. We illustrate on various electrolytes and different microporous
materials, that a simple osmotic pressure law accounts quantitatively for the
enhancement of the intrusion and extrusion pressures governing the forced
wetting and spontaneous drying of the nanopores. Using electrolyte solutions,
energy storage and power capacities can be widely enhanced.
| arxiv topic:cond-mat.soft |
arxiv_dataset-63821507.00539 | Diffusion and subdiffusion of interacting particles on comb-like
structures
cond-mat.stat-mech cond-mat.dis-nn
We study the dynamics of a tracer particle (TP) on a comb lattice populated
by randomly moving hard-core particles in the dense limit. We first consider
the case where the TP is constrained to move on the backbone of the comb only,
and, in the limit of high density of particles, we present exact analytical
results for the cumulants of the TP position, showing a subdiffusive behavior
$\sim t^{3/4}$. At longer times, a second regime is observed, where standard
diffusion is recovered, with a surprising non analytical dependence of the
diffusion coefficient on the particle density. When the TP is allowed to visit
the teeth of the comb, based on a mean-field-like Continuous Time Random Walk
description, we unveil a rich and complex scenario, with several successive
subdiffusive regimes, resulting from the coupling between the inhomogeneous
comb geometry and particle interactions. Remarkably, the presence of hard-core
interactions speeds up the TP motion along the backbone of the structure in all
regimes.
| arxiv topic:cond-mat.stat-mech cond-mat.dis-nn |
arxiv_dataset-63831507.00639 | Simple, Fast Semantic Parsing with a Tensor Kernel
cs.CL
We describe a simple approach to semantic parsing based on a tensor product
kernel. We extract two feature vectors: one for the query and one for each
candidate logical form. We then train a classifier using the tensor product of
the two vectors. Using very simple features for both, our system achieves an
average F1 score of 40.1% on the WebQuestions dataset. This is comparable to
more complex systems but is simpler to implement and runs faster.
| arxiv topic:cs.CL |
arxiv_dataset-63841507.00739 | Extremal eigenvalues of local Hamiltonians
quant-ph cs.CC
We apply classical algorithms for approximately solving constraint
satisfaction problems to find bounds on extremal eigenvalues of local
Hamiltonians. We consider spin Hamiltonians for which we have an upper bound on
the number of terms in which each spin participates, and find extensive bounds
for the operator norm and ground-state energy of such Hamiltonians under this
constraint. In each case the bound is achieved by a product state which can be
found efficiently using a classical algorithm.
| arxiv topic:quant-ph cs.CC |
arxiv_dataset-63851507.00839 | Massive stars on the verge of exploding: the properties of oxygen
sequence Wolf-Rayet stars
astro-ph.SR
Context. Oxygen sequence Wolf-Rayet (WO) stars represent a very rare stage in
the evolution of massive stars. Their spectra show strong emission lines of
helium-burning products, in particular highly ionized carbon and oxygen. The
properties of WO stars can be used to provide unique constraints on the
(post-)helium burning evolution of massive stars, as well as their remaining
lifetime and the expected properties of their supernovae. Aims. We aim to
homogeneously analyse the currently known presumed-single WO stars to obtain
the key stellar and outflow properties and to constrain their evolutionary
state. Methods. We use the line-blanketed non-local thermal equilibrium
atmosphere code cmfgen to model the X-Shooter spectra of the WO stars and
deduce the atmospheric parameters. We calculate dedicated evolutionary models
to determine the evolutionary state of the stars. Results. The WO stars have
extremely high temperatures that range from 150 kK to 210 kK, and very low
surface helium mass fractions that range from 44% down to 14%. Their properties
can be reproduced by evolutionary models with helium zero-age main sequence
masses of $M_{\mathrm{He, ini}} = 15-25 M_{\odot}$ that exhibit a fairly strong
(on the order of a few times $10^{-5} M_{\odot} \mathrm{yr}^{-1}$), homogeneous
($f_\mathrm{c} > 0.3$) stellar wind. Conclusions. WO stars represent the final
evolutionary stage of stars with estimated initial masses of $M_{\mathrm{ini}}
= 40-60 M_{\odot}$. They are post core-helium burning and predicted to explode
as type Ic supernovae within a few thousand years.
| arxiv topic:astro-ph.SR |
arxiv_dataset-63861507.00939 | Evolution of as-a-Service Era in Cloud
cs.DC
Today, a paradigm shift is being observed in science, where the focus is
gradually shifting toward the cloud environments to obtain appropriate, robust
and affordable services to deal with Big Data challenges (Sharma et al. 2014,
2015a, 2015b). Cloud computing avoids any need to locally maintain the overly
scaled computing infrastructure that include not only dedicated space, but the
expensive hardware and software also. In this paper, we study the evolution of
as-a-Service modalities, stimulated by cloud computing, and explore the most
complete inventory of new members beyond traditional cloud computing stack.
| arxiv topic:cs.DC |
arxiv_dataset-63871507.01039 | A Counterexample for Lightning Flash Modules over E(e1,e2)
math.RT math.AT
We give a counterexample to Theorem 5 in Section 18.2 of Margolis' book,
"Spectra and the Steenrod Algebra", and make remarks about the proofs of some
later theorems in the book that depend on it. The counterexample is a module
which does not split as a sum of lightning flash modules and free modules.
| arxiv topic:math.RT math.AT |
arxiv_dataset-63881507.01139 | Spiral magnets with Dzyaloshinskii-Moriya interaction containing defect
bonds
cond-mat.str-el
We present a theory describing spiral magnets with Dzyaloshinskii-Moriya
interaction (DMI) subject to bond disorder at small concentration $c$ of
defects. It is assumed that both DMI and exchange coupling are changed on
imperfect bonds. Qualitatively the same physical picture is obtained in two
models which are considered in detail: B20 cubic helimagnets and layered
magnets in which DMI leads to a long-period spiral ordering perpendicular to
layers. We find that the distortion of the spiral magnetic ordering around a
single imperfect bond is long-range: values of additional turns of spins decay
with the distance $r$ to the defect as $1/r^2$ being governed by the Poisson's
equation for electric dipole. At finite concentration of randomly distributed
imperfect bonds, we calculate correction to the spiral vector. We show that
this correction can change the sign of spin chirality even at $c\ll1$ if
defects are strong enough. It is demonstrated that impurities lead to a diffuse
elastic neutron scattering which has power-law singularities at magnetic Bragg
peaks positions. Then, each Bragg peak acquires power-law decaying tails.
Corrections are calculated to the magnon energy and to its damping caused by
scattering on impurities.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-63891507.01239 | Experiments on Parallel Training of Deep Neural Network using Model
Averaging
cs.LG cs.NE
In this work we apply model averaging to parallel training of deep neural
network (DNN). Parallelization is done in a model averaging manner. Data is
partitioned and distributed to different nodes for local model updates, and
model averaging across nodes is done every few minibatches. We use multiple
GPUs for data parallelization, and Message Passing Interface (MPI) for
communication between nodes, which allows us to perform model averaging
frequently without losing much time on communication. We investigate the
effectiveness of Natural Gradient Stochastic Gradient Descent (NG-SGD) and
Restricted Boltzmann Machine (RBM) pretraining for parallel training in
model-averaging framework, and explore the best setups in term of different
learning rate schedules, averaging frequencies and minibatch sizes. It is shown
that NG-SGD and RBM pretraining benefits parameter-averaging based model
training. On the 300h Switchboard dataset, a 9.3 times speedup is achieved
using 16 GPUs and 17 times speedup using 32 GPUs with limited decoding accuracy
loss.
| arxiv topic:cs.LG cs.NE |
arxiv_dataset-63901507.01339 | On the greatest and least elements in the set of semistandard tableaux
of given shape and weight
math.CO
We give three algorithms to construct a semistandard tableau of given shape
and weight, where the weight is a composition which is not necessarily a
partition. With respect to a natural partial order on the set of semistandard
tableaux, we show that the set of semistandard tableaux of given shape and
weight has a unique greatest element and a unique least element. Two of our
algorithms give each of these elements.
| arxiv topic:math.CO |
arxiv_dataset-63911507.01439 | Elasticity and Glocality: Initiation of Embryonic Inversion in ${\it
Volvox}$
cond-mat.soft q-bio.CB
Elastic objects across a wide range of scales deform under local changes of
their intrinsic properties, yet the shapes are ${\it glocal}$, set by a
complicated balance between local properties and global geometric constraints.
Here, we explore this interplay during the inversion process of the green alga
${\it Volvox}$, whose embryos must turn themselves inside out to complete their
development. This process has recently been shown [S. H\"ohn ${\it et~al}.$,
${\it Phys. Rev. Lett.}$ $\textbf{114}$, 178101 (2015)] to be well described by
the deformations of an elastic shell under local variations of its intrinsic
curvatures and stretches, although the detailed mechanics of the process have
remained unclear. Through a combination of asymptotic analysis and numerical
studies of the bifurcation behavior, we illustrate how appropriate local
deformations can overcome global constraints to initiate inversion.
| arxiv topic:cond-mat.soft q-bio.CB |
arxiv_dataset-63921507.01539 | Quantum entanglement in coupled lossy waveguides using SU(2) and SU(1,1)
Thermo-algebras
quant-ph
In this paper, the master equation for the coupled lossy waveguides is solved
using the thermofield dynamics(TFD) formalism. This formalism allows the use of
the underlying symmetry algebras SU(2) and SU(1,1), associated with the
Hamiltonian of the coupled lossy waveguides,to compute entanglement and
decoherence as a function of time for various input states such as NOON states
and thermal states.
| arxiv topic:quant-ph |
arxiv_dataset-63931507.01639 | Theory of Raman response in three-dimensional Kitaev spin liquids:
application to $\beta-$ and $\gamma-$Li$_2$IrO$_3$ compounds
cond-mat.str-el
We calculate the Raman response for the Kitaev spin model on the
$\mathcal{H}$-$0$, $\mathcal{H}$-$1$, and $\mathcal{H}$-$\infty$ harmonic
honeycomb lattices. We identify several quantitative features in the Raman
spectrum that are characteristic of the spin liquid phase. Unlike the dynamical
structure factor, which probes both the Majorana spinons and flux excitations
that emerge from spin fractionalization, the Raman spectrum in the Kitaev
models directly probes a density of states of pairs of fractional, dispersing
Majorana spinons. As a consequence, the Raman spectrum in all these models is
gapless for sufficiently isotropic couplings, with a low-energy power law that
results from the Fermi lines (or points) of the dispersing Majorana spinons. We
show that the polarization dependence of the Raman spectrum contains crucial
information about the symmetry of the ground state. We also discuss to what
extent the features of the Raman response that we find reflect generic
properties of the spin liquid phase, and comment on their possible relevance to
$\alpha-$, $\beta-$ and $\gamma-$Li$_2$IrO$_3$ compounds.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-63941507.01739 | Direct detection of singlet dark matter in classically scale-invariant
standard model
hep-ph
Classical scale invariance is one of the possible solutions to explain the
origin of the electroweak scale. The simplest extension is the classically
scale-invariant standard model augmented by a multiplet of gauge singlet real
scalar. In the previous study it was shown that the properties of the Higgs
potential deviate substantially, which can be observed in the International
Linear Collider. On the other hand, since the multiplet does not acquire vacuum
expectation value, the singlet components are stable and can be dark matter. In
this letter we study the detectability of the real singlet scalar bosons in the
experiment of the direct detection of dark matter. It is shown that a part of
this model has already been excluded and the rest of the parameter space is
within the reach of the future experiment.
| arxiv topic:hep-ph |
arxiv_dataset-63951507.01839 | Dependency-based Convolutional Neural Networks for Sentence Embedding
cs.CL cs.AI cs.LG
In sentence modeling and classification, convolutional neural network
approaches have recently achieved state-of-the-art results, but all such
efforts process word vectors sequentially and neglect long-distance
dependencies. To exploit both deep learning and linguistic structures, we
propose a tree-based convolutional neural network model which exploit various
long-distance relationships between words. Our model improves the sequential
baselines on all three sentiment and question classification tasks, and
achieves the highest published accuracy on TREC.
| arxiv topic:cs.CL cs.AI cs.LG |
arxiv_dataset-63961507.01939 | Nonequilibrium many-body steady states via Keldysh formalism
cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el
Many-body systems with both coherent dynamics and dissipation constitute a
rich class of models which are nevertheless much less explored than their
dissipationless counterparts. The advent of numerous experimental platforms
that simulate such dynamics poses an immediate challenge to systematically
understand and classify these models. In particular, nontrivial many-body
states emerge as steady states under non-equilibrium dynamics. While these
states and their phase transitions have been studied extensively with mean
field theory, the validity of the mean field approximation has not been
systematically investigated. In this paper, we employ a field-theoretic
approach based on the Keldysh formalism to study nonequilibrium phases and
phase transitions in a variety of models. In all cases, a complete description
via the Keldysh formalism indicates a partial or complete failure of the mean
field analysis. Furthermore, we find that an effective temperature emerges as a
result of dissipation, and the universal behavior including the dynamics near
the steady state is generically described by a thermodynamic universality
class.
| arxiv topic:cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el |
arxiv_dataset-63971507.02039 | Rectifiability and elliptic measures on 1-sided NTA domains with
Ahlfors-David regular boundaries
math.CA math.AP
Let $\Omega \subset \mathbb{R}^{n+1}$, $n\geq 2$, be 1-sided NTA domain (aka
uniform domain), i.e. a domain which satisfies interior Corkscrew and Harnack
Chain conditions, and assume that $\partial\Omega$ is $n$-dimensional
Ahlfors-David regular. We characterize the rectifiability of $\partial\Omega$
in terms of the absolute continuity of surface measure with respect to harmonic
measure. We also show that these are equivalent to the fact that
$\partial\Omega$ can be covered $\mathcal{H}^n$-a.e. by a countable union of
portions of boundaries of bounded chord-arc subdomains of $\Omega$ and to the
fact that $\partial\Omega$ possesses exterior corkscrew points in a qualitative
way $\mathcal{H}^n$-a.e. Our methods apply to harmonic measure and also to
elliptic measures associated with real symmetric second order divergence form
elliptic operators with locally Lipschitz coefficients whose derivatives
satisfy a natural qualitative Carleson condition.
| arxiv topic:math.CA math.AP |
arxiv_dataset-63981507.02139 | Model of human collective decision-making in complex environments
cs.MA cs.AI nlin.AO physics.soc-ph
A continuous-time Markov process is proposed to analyze how a group of humans
solves a complex task, consisting in the search of the optimal set of decisions
on a fitness landscape. Individuals change their opinions driven by two
different forces: (i) the self-interest, which pushes them to increase their
own fitness values, and (ii) the social interactions, which push individuals to
reduce the diversity of their opinions in order to reach consensus. Results
show that the performance of the group is strongly affected by the strength of
social interactions and by the level of knowledge of the individuals.
Increasing the strength of social interactions improves the performance of the
team. However, too strong social interactions slow down the search of the
optimal solution and worsen the performance of the group. In particular, we
find that the threshold value of the social interaction strength, which leads
to the emergence of a superior intelligence of the group, is just the critical
threshold at which the consensus among the members sets in. We also prove that
a moderate level of knowledge is already enough to guarantee high performance
of the group in making decisions.
| arxiv topic:cs.MA cs.AI nlin.AO physics.soc-ph |
arxiv_dataset-63991507.02239 | The signature of the Ricci curvature of left-invariant Riemannian
metrics on nilpotent Lie groups
math.DG
Let $(G,h)$ be a nilpotent Lie group endowed with a left invariant Riemannian
metric, $\mathfrak{g}$ its Euclidean Lie algebra and $Z(\mathfrak{g})$ the
center of $\mathfrak{g}$. By using an orthonormal basis adapted to the
splitting
$\mathfrak{g}=(Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}])\oplus
O^+\oplus (Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}]^\perp)\oplus
O^-$, where $O^+$ (resp. $O^-$) is the orthogonal of
$Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}]$ in
$[\mathfrak{g},\mathfrak{g}]$ (resp. is the orthogonal of
$Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}]^\perp$ in
$[\mathfrak{g},\mathfrak{g}]^\perp$), we show that the signature of the Ricci
operator of $(G,h)$ is determined by the dimensions of the vector spaces
$Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}],$
$Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}]^\perp$ and the signature of a
symmetric matrix of order
$\dim[\mathfrak{g},\mathfrak{g}]-\dim(Z(\mathfrak{g})\cap[\mathfrak{g},\mathfrak{g}])$.
This permits to associate to $G$ a subset $\mathbf{Sign}(\mathfrak{g})$ of
$\mathbf{N}^3$ depending only on the Lie algebra structure, easy to compute and
such that, for any left invariant Riemannian metric on $G$, the signature of
its Ricci operator belongs to $\mathbf{Sign}(\mathfrak{g})$. We show also that
for any nilpotent Lie group of dimension less or equal to 6,
$\mathbf{Sign}(\mathfrak{g})$ is actually the set of signatures of the Ricci
operators of all left invariant Riemannian metrics on $G$. We give also some
general results which support the conjecture that the last result is true in
any dimension.
| arxiv topic:math.DG |
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