id stringlengths 16 29 | text stringlengths 86 3.49k | source stringlengths 14 112 |
|---|---|---|
arxiv_dataset-75001607.02449 | High Tc superconductivity at the interface between the CaCuO2 and SrTiO3
insulating oxides
cond-mat.supr-con
At interfaces between complex oxides it is possible to generate electronic
systems with unusual electronic properties, which are not present in the
isolated oxides. One important example is the appearance of superconductivity
at the interface between insulating oxides, although, until now, with very low
Tc. We report the occurrence of high Tc superconductivity in the bilayer
CaCuO2/SrTiO3, where both the constituent oxides are insulating. In order to
obtain a superconducting state, the CaCuO2/SrTiO3 interface must be realized
between the Ca plane of CaCuO2 and the TiO2 plane of SrTiO3. Only in this case
extra oxygen ions can be incorporated in the interface Ca plane, acting as
apical oxygen for Cu and providing holes to the CuO2 planes. A detailed hole
doping spatial profile has been obtained by STEM/EELS at the O K-edge, clearly
showing that the (super)conductivity is confined to about 1-2 CaCuO2 unit cells
close to the interface with SrTiO3. The results obtained for the CaCuO2/SrTiO3
interface can be extended to multilayered high Tc cuprates, contributing to
explain the dependence of Tc on the number of CuO2 planes in these systems.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-75011607.02549 | Formal Requirement Elicitation and Debugging for Testing and
Verification of Cyber-Physical Systems
cs.SY cs.LO cs.SE
A framework for the elicitation and debugging of formal specifications for
Cyber-Physical Systems is presented. The elicitation of specifications is
handled through a graphical interface. Two debugging algorithms are presented.
The first checks for erroneous or incomplete temporal logic specifications
without considering the system. The second can be utilized for the analysis of
reactive requirements with respect to system test traces. The specification
debugging framework is applied on a number of formal specifications collected
through a user study. The user study establishes that requirement errors are
common and that the debugging framework can resolve many insidious
specification errors.
| arxiv topic:cs.SY cs.LO cs.SE |
arxiv_dataset-75021607.02649 | Linear signal recovery from $b$-bit-quantized linear measurements:
precise analysis of the trade-off between bit depth and number of
measurements
cs.IT math.IT stat.ME
We consider the problem of recovering a high-dimensional structured signal
from independent Gaussian linear measurements each of which is quantized to $b$
bits. Our interest is in linear approaches to signal recovery, where "linear"
means that non-linearity resulting from quantization is ignored and the
observations are treated as if they arose from a linear measurement model.
Specifically, the focus is on a generalization of a method for one-bit
observations due to Plan and Vershynin [\emph{IEEE~Trans. Inform. Theory,
\textbf{59} (2013), 482--494}]. At the heart of the present paper is a precise
characterization of the optimal trade-off between the number of measurements
$m$ and the bit depth per measurement $b$ given a total budget of $B = m \cdot
b$ bits when the goal is to minimize the $\ell_2$-error in estimating the
signal. It turns out that the choice $b = 1$ is optimal for estimating the unit
vector (direction) corresponding to the signal for any level of additive
Gaussian noise before quantization as well as for a specific model of
adversarial noise, while the choice $b = 2$ is optimal for estimating the
direction and the norm (scale) of the signal. Moreover, Lloyd-Max quantization
is shown to be an optimal quantization scheme w.r.t. $\ell_2$-estimation error.
Our analysis is corroborated by numerical experiments showing nearly perfect
agreement with our theoretical predictions. The paper is complemented by an
empirical comparison to alternative methods of signal recovery taking the
non-linearity resulting from quantization into account. The results of that
comparison point to a regime change depending on the noise level: in a
low-noise setting, linear signal recovery falls short of more sophisticated
competitors while being competitive in moderate- and high-noise settings.
| arxiv topic:cs.IT math.IT stat.ME |
arxiv_dataset-75031607.02749 | The CO-H2 van der Waals complex and complex organic molecules in cold
molecular clouds: a TMC-1C survey
astro-ph.GA
Almost 200 different species have been detected in the interstellar medium
(ISM) during the last decades, revealing not only simple species but complex
molecules with more than 6 atoms. Other exotic compounds, like the weakly-bound
dimer (H2)2, have also been detected in astronomical sources like Jupiter. We
aim at detecting for the first time the CO-H2 van der Waals complex in the ISM,
which if detected can be a sensitive indicator for low temperatures. We use the
IRAM30m telescope, located in Pico Veleta (Spain), to search for the CO-H2
complex in a cold, dense core in TMC-1C (with a temperature of 10 K). All the
brightest CO-H2 transitions in the 3 mm (80-110 GHz) band have been observed
with a spectral resolution of 0.5-0.7 km/s, reaching a rms noise level of 2 mK.
The simultaneous observation of a broad frequency band, 16 GHz, has allowed us
to conduct a serendipitous spectral line survey. No lines belonging to the
CO-H2 complex have been detected. We have set up a new, more stringent upper
limit for its abundance to be [CO-H2]/[CO] = 5x10^{-6}, while we expect the
abundance of the complex to be in the range 10^{-8}-10^{-3}. The spectral line
survey has allowed us to detect 75 lines associated with 41 different species
(including isotopologues). We detect a number of complex organic species, e.g.
methyl cyanide (CH3CN), methanol (CH3OH), propyne (CH3CCH) and ketene (CH2CO),
associated with cold gas (excitation temperatures about 7 K), confirming the
presence of these complex species not only in warm objects but also in cold
regimes.
| arxiv topic:astro-ph.GA |
arxiv_dataset-75041607.02849 | Affine embeddings of Cantor sets on the line
math.DS
Let $s\in (0,1)$, and let $F\subset \mathbb{R}$ be a self similar set such
that $0 < \dim_H F \leq s$ . We prove that there exists $\delta= \delta(s) >0$
such that if $F$ admits an affine embedding into a homogeneous self similar set
$E$ and $0 \leq \dim_H E - \dim_H F < \delta$ then (under some mild conditions
on $E$ and $F$) the contraction ratios of $E$ and $F$ are logarithmically
commensurable. This provides more evidence for a Conjecture of Feng, Huang, and
Rao, that states that these contraction ratios are logarithmically
commensurable whenever $F$ admits an affine embedding into $E$ (under some mild
conditions). Our method is a combination of an argument based on the approach
of Feng, Huang, and Rao, with a new result by Hochman, which is related to the
increase of entropy of measures under convolutions.
| arxiv topic:math.DS |
arxiv_dataset-75051607.02949 | Scaling of anomalous Hall effect in ferromagnetic thin films
cond-mat.mes-hall
We propose a new scaling law for anomalous Hall effect in ferromagnetic thin
films by distinguishing three scattering sources, namely, bulk impurity,
phonon, and more importantly a rough surface. This new scaling law fits the
recent experimental data excellently with constant coefficients that are
independent of temperature and film thickness. This is in stark constrast with
previous scaling laws that use temperature/thickness dependent fitting
coefficients, and is a strong indicator that this law captures the essential
physics. By intepretating the experiments for Fe, Co, and Ni with this new law,
we conclude that (i) the phonon-induced skew scattering is unimportant as
expected; (ii) contribution from the impurity-induced skew scattering is
negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and
both the extrinsic and the intrinsic contribution are important in Ni.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-75061607.03049 | Magnetic Cycles and Rotation Periods of Late Type Stars from photometric
time series
astro-ph.SR
We investigate the photometric modulation induced by magnetic activity cycles
and study the relationship between rotation period and activity cycle(s) in
late-type (FGKM) stars. We analyse light-curves spanning up to 9 years of 125
nearby stars provided by the ASAS survey. The sample is mainly conformed by
low-activity main sequence late A to mid M-type stars. A search is performed
for short (days) and long-term (years) periodic variations in the photometry.
We modelled with combinations of sinusoids the light-curves to measure the
properties of these periodic signals. To provide a better statistical
interpretation of our results we complement them with the results from previous
similar works. We have been able to measure long-term photometric cycles of 47
stars. Rotational modulation was also detected and rotational periods measured
in 36 stars. For 28 stars we have simultaneous measurements of both, activity
cycles and rotational periods, being 17 of them M-type stars. From sinusoidal
fits we measured both photometric amplitudes and periods. The measured cycle
periods range from 2 up to 14 yr with photometric amplitudes in the range of
5-20 mmag. We have found that the distribution of cycle lengths for the
different spectral types is similar. On the other hand the distribution of
rotation periods is completely different, trending to longer periods for later
type stars. The amplitudes induced by magnetic cycles and rotation show a clear
correlation. A trend of photometric amplitudes with rotation period is also
outlined in the data. For a given activity index the amplitudes of the
photometric variability induced by activity cycles of main sequence GK stars
are lower than those of early and mid-M dwarfs. Using spectroscopic data we
also provide an update in the empirical relationship between the level of
chromospheric activity as given by log(Rhk) and the rotation periods.
| arxiv topic:astro-ph.SR |
arxiv_dataset-75071607.03149 | The clustering of galaxies in the completed SDSS-III Baryon Oscillation
Spectroscopic Survey: Baryon Acoustic Oscillations in Fourier-space
astro-ph.CO
We analyse the Baryon Acoustic Oscillation (BAO) signal of the final Baryon
Oscillation Spectroscopic Survey (BOSS) data release (DR12). Our analysis is
performed in Fourier-space, using the power spectrum monopole and quadrupole.
The dataset includes $1\,198\,006$ galaxies over the redshift range $0.2 < z <
0.75$. We divide this dataset into three (overlapping) redshift bins with the
effective redshifts $\zeff = 0.38$, $0.51$ and $0.61$. We demonstrate the
reliability of our analysis pipeline using N-body simulations as well as $\sim
1000$ MultiDark-Patchy mock catalogues, which mimic the BOSS-DR12 target
selection. We apply density field reconstruction to enhance the BAO
signal-to-noise ratio. By including the power spectrum quadrupole we can
separate the line-of-sight and angular modes, which allows us to constrain the
angular diameter distance $D_A(z)$ and the Hubble parameter $H(z)$ separately.
We obtain two independent $1.6\%$ and $1.5\%$ constraints on $D_A(z)$ and
$2.9\%$ and $2.3\%$ constraints on $H(z)$ for the low ($\zeff=0.38$) and high
($\zeff=0.61$) redshift bin, respectively. We obtain two independent $1\%$ and
$0.9\%$ constraints on the angular averaged distance $D_V(z)$, when ignoring
the Alcock-Paczynski effect. The detection significance of the BAO signal is of
the order of $8\sigma$ (post-reconstruction) for each of the three redshift
bins. Our results are in good agreement with the Planck prediction within
$\Lambda$CDM. This paper is part of a set that analyses the final galaxy
clustering dataset from BOSS. The measurements and likelihoods presented here
are combined with others in~\citet{Alam2016} to produce the final cosmological
constraints from BOSS.
| arxiv topic:astro-ph.CO |
arxiv_dataset-75081607.03249 | All entangled states can demonstrate non-classical teleportation
quant-ph
Quantum teleportation, the process by which Alice can transfer an unknown
quantum state to Bob by using pre-shared entanglement and classical
communication, is one of the cornerstones of quantum information. The standard
benchmark for certifying quantum teleportation consists in surpassing the
maximum average fidelity between the teleported and the target states that can
be achieved classically. According to this figure of merit, not all entangled
states are useful for teleportation. Here we propose a new benchmark that uses
the full information available in a teleportation experiment and prove that all
entangled states can implement a quantum channel which can not be reproduced
classically. We introduce the idea of non-classical teleportation witness to
certify if a teleportation experiment is genuinely quantum and discuss how to
quantify this phenomenon. Our work provides new techniques for studying
teleportation that can be immediately applied to certify the quality of quantum
technologies.
| arxiv topic:quant-ph |
arxiv_dataset-75091607.03349 | Tractable Stochastic Geometry Model for IoT Access in LTE Networks
cs.IT cs.NI math.IT
The Internet of Things (IoT) is large-scale by nature. This is not only
manifested by the large number of connected devices, but also by the high
volumes of traffic that must be accommodated. Cellular networks are indeed a
natural candidate for the data tsunami the IoT is expected to generate in
conjunction with legacy human-type traffic. However, the random access process
for scheduling request represents a major bottleneck to support IoT via LTE
cellular networks. Accordingly, this paper develops a mathematical framework to
model and study the random access channel (RACH) scalability to accommodate IoT
traffic. The developed model is based on stochastic geometry and discrete time
Markov chains (DTMC) to account for different access strategies and possible
sources of inter-cell and intra-cell interferences. To this end, the developed
model is utilized to assess and compare three different access strategies,
which incorporate a combination of transmission persistency, back-off, and
power ramping. The analysis and the results showcased herewith clearly
illustrate the vulnerability of the random access procedure as the IoT
intensity grows. Finally, the paper offers insights into effective scenarios
for each transmission strategy in terms of IoT intensity and RACH detection
thresholds.
| arxiv topic:cs.IT cs.NI math.IT |
arxiv_dataset-75101607.03449 | Theory for Spin Selective Andreev Reflection in Vortex Core of
Topological Superconductor: Majorana Zero Modes on Spherical Surface and
Application to Spin Polarized Scanning Tunneling Microscope Probe
cond-mat.supr-con
Majorana zero modes (MZMs) have been predicted to exist in the topological
insulator (TI)/superconductor (SC) heterostructure. Recent spin polarized
scanning tunneling microscope (STM) experiment$^{1}$ has observed
spin-polarization dependence of the zero bias differential tunneling
conductance at the center of vortex core, which may be attributed to the spin
selective Andreev reflection, a novel property of the MZMs theoretically
predicted in 1-dimensional nanowire$^{2}$. Here we consider a helical electron
system described by a Rashba spin orbit coupling Hamiltonian on a spherical
surface with a s-wave superconducting pairing due to proximity effect. We
examine in-gap excitations of a pair of vortices with one at the north pole and
the other at the south pole. While the MZM is not a spin eigenstate, the spin
wavefunction of the MZM at the center of the vortex core, r = 0, is parallel to
the magnetic field, and the local Andreev reflection of the MZM is spin
selective, namely occurs only when the STM tip has the spin polarization
parallel to the magnetic field, similar to the case in 1-dimensional nanowire2.
The total local differential tunneling conductance consists of the normal term
proportional to the local density of states and an additional term arising from
the Andreev reflection. We also discuss the finite size effect, for which the
MZM at the north pole is hybridized with the MZM at the south pole. We apply
our theory to examine the recently reported spin-polarized STM experiments and
show good agreement with the experiments.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-75111607.03549 | Statistical Issues in Neutrino Physics Analyses
hep-ex physics.data-an
Various statistical issues relevant to searches for new physics or to
parameter determination in analyses of data in neutrino experiments are briefly
discussed.
| arxiv topic:hep-ex physics.data-an |
arxiv_dataset-75121607.03649 | LTL-based Verification of Reconfigurable Workflows
cs.SE
Logics and model-checking have been successfully used in the last decades for
modeling and verification of various types of hardware (and software) systems.
While most languages and techniques emerged in a context of monolithic systems
with a limited self-adaptability, modern systems require approaches able to
cope with dynamically changing requirements and emergent behaviors. The
emphasis on system reconfigurability has not been followed by an adequate
research effort, and the current state of the art lacks logics and model
checking paradigms that can describe and analyze complex modern systems in a
comprehensive way. This paper describes a case study involving the dynamic
reconfiguration of an office workflow. We state the requirements on a system
implementing the workflow and its reconfiguration and we prove workflow
reconfiguration termination by providing a compilation of generic workflows
into LTL, using the Bound model checker Zot. The objective of this paper is
demonstrating how temporal logics and model checking are effective in proving
properties of dynamic, reconfigurable and adaptable systems. This simple case
study is just a "proof of concept" to demonstrate the feasibility of our ideas.
| arxiv topic:cs.SE |
arxiv_dataset-75131607.03749 | The Impact of Lorentz Violation on the Klein Tunneling Effect
hep-ph
We discuss the impact of a tiny Lorentz-violating $b^\mu$ term on the one
dimensional motion of a Dirac particle scattering on a rectangular barrier. We
assume the experiment is performed in a particular inertial frame, where the
components of $b^\mu$ are assumed constants. The results show that
Lorentz-violation modification to the transmission rate depends on the observer
Lorentz nature of $b^\mu$. For a spacelike or lightlike $b^\mu$ the induced
resonant frequency shift depends on the polarization, while for timelike
$b^\mu$ there is essentially no modification.
| arxiv topic:hep-ph |
arxiv_dataset-75141607.03849 | Fitting a Simplicial Complex using a Variation of k-means
cs.LG cs.CG stat.ML
We give a simple and effective two stage algorithm for approximating a point
cloud $\mathcal{S}\subset\mathbb{R}^m$ by a simplicial complex $K$. The first
stage is an iterative fitting procedure that generalizes k-means clustering,
while the second stage involves deleting redundant simplices. A form of
dimension reduction of $\mathcal{S}$ is obtained as a consequence.
| arxiv topic:cs.LG cs.CG stat.ML |
arxiv_dataset-75151607.03949 | Large Scale SfM with the Distributed Camera Model
cs.CV
We introduce the distributed camera model, a novel model for
Structure-from-Motion (SfM). This model describes image observations in terms
of light rays with ray origins and directions rather than pixels. As such, the
proposed model is capable of describing a single camera or multiple cameras
simultaneously as the collection of all light rays observed. We show how the
distributed camera model is a generalization of the standard camera model and
describe a general formulation and solution to the absolute camera pose problem
that works for standard or distributed cameras. The proposed method computes a
solution that is up to 8 times more efficient and robust to rotation
singularities in comparison with gDLS. Finally, this method is used in an novel
large-scale incremental SfM pipeline where distributed cameras are accurately
and robustly merged together. This pipeline is a direct generalization of
traditional incremental SfM; however, instead of incrementally adding one
camera at a time to grow the reconstruction the reconstruction is grown by
adding a distributed camera. Our pipeline produces highly accurate
reconstructions efficiently by avoiding the need for many bundle adjustment
iterations and is capable of computing a 3D model of Rome from over 15,000
images in just 22 minutes.
| arxiv topic:cs.CV |
arxiv_dataset-75161607.04049 | Complex heavy-quark potential and Debye mass in a gluonic medium from
lattice QCD
hep-lat hep-ph nucl-th
We improve and extend our study of the complex in-medium heavy quark
potential and its Debye mass $m_D$ in a gluonic medium with a finer scan around
the deconfinement transition and newly generated ensembles closer to the
thermodynamic limit. On the lattices with larger physical volume, Re[V] shows
signs of screening, i.e. a finite $m_D$, only in the deconfined phase,
reminiscent of a genuine phase transition. Consistently Im[V] exhibits nonzero
values also only above $T_C$. We compare the behavior of Re[V] with the color
singlet free-energies that have been used historically to extract the Debye
mass. An effective coupling constant is computed to assess the residual
influence of the confining part of the potential at $T>0$. Our previous finding
of a gradual screening of Re[V] around $T_C$ on finer lattices is critically
reassessed and interpreted to originate from finite volume artifacts that
affect the deployed $\beta=7$, $\xi_b=3.5$ parameter set at $N_s=32$.
| arxiv topic:hep-lat hep-ph nucl-th |
arxiv_dataset-75171607.04149 | Best-Response Dynamics in Combinatorial Auctions with Item Bidding
cs.GT cs.DS
In a combinatorial auction with item bidding, agents participate in multiple
single-item second-price auctions at once. As some items might be substitutes,
agents need to strategize in order to maximize their utilities. A number of
results indicate that high welfare can be achieved this way, giving bounds on
the welfare at equilibrium. Recently, however, criticism has been raised that
equilibria are hard to compute and therefore unlikely to be attained.
In this paper, we take a different perspective. We study simple best-response
dynamics. That is, agents are activated one after the other and each activated
agent updates his strategy myopically to a best response against the other
agents' current strategies. Often these dynamics may take exponentially long
before they converge or they may not converge at all. However, as we show,
convergence is not even necessary for good welfare guarantees. Given that
agents' bid updates are aggressive enough but not too aggressive, the game will
remain in states of good welfare after each agent has updated his bid at least
once.
In more detail, we show that if agents have fractionally subadditive
valuations, natural dynamics reach and remain in a state that provides a $1/3$
approximation to the optimal welfare after each agent has updated his bid at
least once. For subadditive valuations, we can guarantee an $\Omega(1/\log m)$
approximation in case of $m$ items that applies after each agent has updated
his bid at least once and at any point after that. The latter bound is
complemented by a negative result, showing that no kind of best-response
dynamics can guarantee more than an $o(\log \log m/\log m)$ fraction of the
optimal social welfare.
| arxiv topic:cs.GT cs.DS |
arxiv_dataset-75181607.04249 | Generating strong squeezing in the dispersive regime of the quantum Rabi
model
quant-ph
We present a protocol to generate a large degree of squeezing of a boson
(light) field mode strongly coupled to a two-level system in the dispersive
regime. Our protocol exploits the strong dispersive coupling to introduce a
time dependent frequency change of the boson field. With an appropriately timed
sequence of sudden frequency changes, the quantum noise fluctuations in one
quadrature of the field can be reduced well below the standard quantum limit,
with a correspondingly increased uncertainty in the orthogonal quadrature. Even
in the presence of realistic noise and imperfections, the protocol should be
capable of generating substantial squeezing with present experimental
capabilities.
| arxiv topic:quant-ph |
arxiv_dataset-75191607.04349 | Dynamic Hysteresis Probes High-{\beta} Nanolaser Emission Regimes
physics.optics
The quest for an integrated light source that promises high energy efficiency
and fast modulation for high-performance photonic circuits has led to the
development of room-temperature telecom-wavelength nanoscale laser with high
spontaneous emission factors, \beta. The coherence characterization of this
type of lasers is inherently difficult with the conventional measurement of
output light intensity versus input pump intensity due to the diminishing kink
in the measurement curve. We demonstrate the transition from chaotic to
coherent emission of a high-{\beta} pulse-pump metallo-dielectric nanolaser can
be determined by examining the width of a second order intensity correlation
peak, which shrinks below and broadens above threshold. Photon fluctuation
study, first one ever reported for this type of nanolaser, confirms the
validity of this measurement technique. Additionally, we show that the width
variation above threshold results from the delayed threshold phenomenon,
providing the first indirect observation of dynamical hysteresis in a
nanolaser.
| arxiv topic:physics.optics |
arxiv_dataset-75201607.04449 | Effects of scalar leptoquark on semileptonic $\Lambda_b$ decays
hep-ph
We study the scalar leptoquark effects on the rare semileptonic decays of
$\Lambda_b$ baryon, governed by the quark level transition $b \to s l^+ l^-$.
We estimate the branching ratios, forward-backward asymmetries, lepton
polarization parameters and the lepton flavour non-universality effects in
these decay channels. We find significant deviations from the corresponding
standard model predictions in some of the observables due to leptoquark
effects. We also investigate the lepton flavour violating decays $\Lambda_b \to
\Lambda l_i^- l_j^+$, the branching ratios of which are found to be ${\cal
O}(10^{-10} - 10^{-9})$.
| arxiv topic:hep-ph |
arxiv_dataset-75211607.04549 | DiaSys: Improving SoC Insight Through On-Chip Diagnosis
cs.DC cs.AR cs.SE
To find the cause of a functional or non-functional defect (bug) in software
running on a multi-processor System-on-Chip (MPSoC), developers need insight
into the chip. Tracing systems provide this insight non-intrusively, at the
cost of high off-chip bandwidth requirements. This I/O bottleneck limits the
observability, a problem becoming more severe as more functionality is
integrated on-chip. In this paper, we present DiaSys, an MPSoC diagnosis system
with the potential to replace today's tracing systems. Its main idea is to
partially execute the analysis of observation data on the chip; in consequence,
more information and less data is sent to the attached host PC. With DiaSys,
the data analysis is performed by the diagnosis application. Its input are
events, which are generated by observation hardware at interesting points in
the program execution (like a function call). Its outputs are events with
higher information density. The event transformation is modeled as dataflow
application. For execution, it is mapped in part to dedicated and distributed
on-chip components, and in part to the host PC; the off-chip boundary is
transparent to the developer of the diagnosis application. We implement DiaSys
as extension to an existing SoC with four tiles and a mesh network running on
an FPGA platform. Two usage examples confirm that DiaSys is flexible enough to
replace a tracing system, while significantly lowering the off-chip bandwidth
requirements. In our examples, the debugging of a race-condition bug, and the
creation of a lock contention profile, we see a reduction of trace bandwidth of
more than three orders of magnitude, compared to a full trace created by a
common tracing system.
| arxiv topic:cs.DC cs.AR cs.SE |
arxiv_dataset-75221607.04649 | Electrified magnetic catalysis in three-dimensional topological
insulators
cond-mat.mes-hall hep-ph
The gap equations for the surface quasiparticle propagators in a slab of
three-dimensional topological insulator in external electric and magnetic
fields perpendicular to the slab surfaces are analyzed and solved. A different
type of magnetic catalysis is revealed with the dynamical generation of both
Haldane and Dirac gaps. Its characteristic feature manifests itself in the
crucial role that the electric field plays in dynamical symmetry breaking and
the generation of a Dirac gap in the slab. It is argued that, for a
sufficiently large external electric field, the ground state of the system is a
phase with a homogeneous surface charge density.
| arxiv topic:cond-mat.mes-hall hep-ph |
arxiv_dataset-75231607.04749 | Lifetimes and wave functions of ozone metastable vibrational states near
the dissociation limit in full symmetry approach
physics.chem-ph
Energies and lifetimes (widths) of vibrational states above the lowest
dissociation limit of $^{16}$O$_3$ were determined using a previously-developed
efficient approach, which combines hyperspherical coordinates and a complex
absorbing potential. The calculations are based on a recently-computed
potential energy surface of ozone determined with a spectroscopic accuracy [J.
Chem. Phys. {\bf 139}, 134307 (2013)]. The effect of permutational symmetry on
rovibrational dynamics and the density of resonance states in O$_3$ is
discussed in detail. Correspondence between quantum numbers appropriate for
short- and long-range parts of wave functions of the rovibrational continuum is
established. It is shown, by symmetry arguments, that the allowed purely
vibrational ($J=0$) levels of $^{16}$O$_3$ and $^{18}$O$_3$, both made of
bosons with zero nuclear spin, cannot dissociate on the ground state potential
energy surface. Energies and wave functions of bound states of the ozone
isotopologue $^{16}$O$_3$ with rotational angular momentum $J=0$ and 1 up to
the dissociation threshold were also computed. For bound levels, good agreement
with experimental energies is found: The RMS deviation between observed and
calculated vibrational energies is 1~\cm. Rotational constants were determined
and used for a simple identification of vibrational modes of calculated levels.
| arxiv topic:physics.chem-ph |
arxiv_dataset-75241607.04849 | Secure Group Testing
cs.IT math.IT
The principal goal of Group Testing (GT) is to identify a small subset of
"defective" items from a large population, by grouping items into as few test
pools as possible. The test outcome of a pool is positive if it contains at
least one defective item, and is negative otherwise. GT algorithms are utilized
in numerous applications, and in many of them maintaining the privacy of the
tested items, namely, keeping secret whether they are defective or not, is
critical.
In this paper, we consider a scenario where there is an eavesdropper (Eve)
who is able to observe a subset of the GT outcomes (pools). We propose a new
non-adaptive Secure Group Testing (SGT) scheme based on information-theoretic
principles. The new proposed test design keeps the eavesdropper ignorant
regarding the items' status. Specifically, when the fraction of tests observed
by Eve is $0 \leq \delta <1$, we prove that with the naive Maximum Likelihood
(ML) decoding algorithm the number of tests required for both correct
reconstruction at the legitimate user (with high probability) and negligible
information leakage to Eve is $\frac{1}{1-\delta}$ times the number of tests
required with no secrecy constraint for the fixed $K$ regime. By a matching
converse, we completely characterize the Secure GT capacity. Moreover, we
consider the Definitely Non-Defective (DND) computationally efficient decoding
algorithm, proposed in the literature for non-secure GT. We prove that with the
new secure test design, for $\delta < 1/2$, the number of tests required,
without any constraint on $K$, is at most $\frac{1}{1/2-\delta}$ times the
number of tests required with no secrecy constraint.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-75251607.04949 | Leibniz algebras associated with representations of Euclidean Lie
algebra
math.RT math.RA
In the present paper we describe Leibniz algebras with three-dimensional
Euclidean Lie algebra $\mathfrak{e}(2)$ as its liezation. Moreover, it is
assumed that the ideal generated by the squares of elements of an algebra
(denoted by $I$) as a right $\mathfrak{e}(2)$-module is associated to
representations of $\mathfrak{e}(2)$ in $\mathfrak{sl}_2({\mathbb{C}})\oplus
\mathfrak{sl}_2({\mathbb{C}}), \mathfrak{sl}_3({\mathbb{C}})$ and
$\mathfrak{sp}_4(\mathbb{C})$. Furthermore, we present the classification of
Leibniz algebras with general Euclidean Lie algebra ${\mathfrak{e(n)}}$ as its
liezation $I$ being an $(n+1)$-dimensional right ${\mathfrak{e(n)}}$-module
defined by transformations of matrix realization of $\mathfrak{e(n)}.$ Finally,
we extend the notion of a Fock module over Heisenberg Lie algebra to the case
of Diamond Lie algebra $\mathfrak{D}_k$ and describe the structure of Leibniz
algebras with corresponding Lie algebra $\mathfrak{D}_k$ and with the ideal $I$
considered as a Fock $\mathfrak{D}_k$-module.
| arxiv topic:math.RT math.RA |
arxiv_dataset-75261607.05049 | YSO jets in the Galactic Plane from UWISH2: III - Jets and Outflows in
Cassiopeia and Auriga
astro-ph.GA
We present the analysis of 35.5 square degrees of images in the 1-0S(1) line
of H2 from the UK Widefield Infrared Survey for H2 (UWISH2) towards Cassiopeia
and Auriga. We have identified 98 Molecular Hydrogen emission-line Objects
(MHOs) driven by Young Stellar Objects, 60% of which are bipolar outflows and
all are new discoveries. We estimate that the UWISH2 extended emission object
catalogue contains fewer than % false positives and is complete at the 95%
level for jets and outflows brighter than the UWISH2 detection limit. We
identified reliable driving source candidates for three quarters of the
detected outflows, 40% of which are associated with groups and clusters of
stars. The driving source candidates are 20% protostars, the remainder are
CTTSs. We also identified 15 new star cluster candidates near MHOs in the
survey area.
We find that the typical outflow identified in the sample has the following
characteristics: the position angles are randomly orientated; bipolar outflows
are straight within a few degrees; the two lobes are slightly asymmetrical in
length and brightness; the length and brightness of the lobes are not
correlated; typical time gaps between major ejections of material are 1-3kyr,
hence FU-Ori or EX-Ori eruptions are most likely not the cause of these, but we
suggest MNors as a possible source. Furthermore, we find that outflow lobe
length distributions are statistically different from the widely used total
length distributions. There are a larger than expected number of bright
outflows indicating that the flux distribution does not follow a power law.
| arxiv topic:astro-ph.GA |
arxiv_dataset-75271607.05149 | Multiple scattering of polarized light in disordered media exhibiting
short-range structural correlations
physics.optics cond-mat.dis-nn
We develop a model based on a multiple scattering theory to describe the
diffusion of polarized light in disordered media exhibiting short-range
structural correlations. Starting from exact expressions of the average field
and the field spatial correlation function, we derive a radiative transfer
equation for the polarization-resolved specific intensity that is valid for
weak disorder and we solve it analytically in the diffusion limit. A
decomposition of the specific intensity in terms of polarization eigenmodes
reveals how structural correlations, represented via the standard anisotropic
scattering parameter $g$, affect the diffusion of polarized light. More
specifically, we find that propagation through each polarization eigenchannel
is described by its own transport mean free path that depends on $g$ in a
specific and non-trivial way.
| arxiv topic:physics.optics cond-mat.dis-nn |
arxiv_dataset-75281607.05249 | Performance of a Nonempirical Density Functional on Molecules and
Hydrogen-Bonded Complexes
physics.chem-ph
Recently, Tao and Mo (TM) derived a meta-generalized gradient approximation
functional based on a model exchange-correlation hole. In this work, the
performance of this functional is assessed on standard test sets, using the
6-311++G(3df,3pd) basis set. These test sets include 223 G3/99 enthalpies of
formation, 99 atomization energies, 76 barrier heights, 58 electron affinities,
8 proton affinities, 96 bond lengths, 82 harmonic vibrational frequencies, 10
hydrogen-bonded molecular complexes, and 22 atomic excitation energies. Our
calculations show that the TM functional can achieve high accuracy for most
properties considered, relative to the LSDA, PBE, and TPSS functionals. In
particular, it yields the best accuracy for proton affinities, harmonic
vibrational frequencies, hydrogen-bonded dissociation energies and bond
lengths, and atomic excitation energies.
| arxiv topic:physics.chem-ph |
arxiv_dataset-75291607.05349 | Magnetic Behavior of Superatom-Fullerene Assemblies
cond-mat.mes-hall cond-mat.mtrl-sci
It has recently been possible to synthesize ordered assemblies composed of
magnetic superatomic clusters Ni9Te6(PEt3)8 separated by C60 and study their
magnetic behavior. We have carried out theoretical studies on model systems
consisting of magnetic superatoms separated by non-magnetic species to examine
the evolution in magnetic response as the nature of the magnetic superatom
(directions of spin quantization), the strength of isotropic and anisotropic
interactions, the magnetic anisotropy energy, and the size of the assembly are
varied. We have examined square planar configurations consisting 16, 24 and 48
sites with 8, 12 and 24 magnetic superatoms respectively. The magnetic atoms
are allowed 2 or 5 orientations. The model Hamiltonian includes isotropic
exchange interactions with second nearest neighbor ferromagnetic and nearest
neighbor antiferromagnetic couplings and anisotropic Dzyaloshinskii-Moriya
interactions. It is shown that the inclusion of Dzyaloshinskii-Moriya
interaction that cause spin canting is necessary to get qualitative response as
observed in experiments.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-75301607.05449 | The circumstellar disk of FS Tau B - A self-consistent model based on
observations in the mid-infrared with NACO -
astro-ph.SR
Protoplanetary disks are a byproduct of the star formation process. In the
dense mid-plane of these disks, planetesimals and planets are expected to form.
The first step in planet formation is the growth of dust particles from
submicrometer-sized grains to macroscopic mm-sized aggregates. The grain growth
is accompanied by radial drift and vertical segregation of the particles within
the disk. To understand this essential evolutionary step, spatially resolved
multi-wavelength observations as well as photometric data are necessary which
reflect the properties of both disk and dust. We present the first spatially
resolved image obtained with NACO at the VLT in the L$_\text{p}$ band of the
near edge-on protoplanetary disk FS Tau B. Based on this new image, a
previously published Hubble image in H band and the spectral energy
distribution from optical to millimeter wavelengths, we derive constraints on
the spatial dust distribution and the progress of grain growth. For this
purpose we perform a disk modeling using the radiative transfer code MC3D.
Radial drift and vertical sedimentation of the dust are not considered. We find
a best-fit model which features a disk extending from $2\,\text{AU}$ to several
hundreds AU with a moderately decreasing surface density and
$M_\text{disk}=2.8\,\times\,10^{-2}\,\text{M}_\odot$. The inclination amounts
to $i=80^\circ$. Our findings indicate that substantial dust grain growth has
taken place and that grains of a size equal to or larger than $1\,\text{mm}$
are present in the disk. In conclusion, the parameters describing the vertical
density distribution are better constrained than those describing the radial
disk structure.
| arxiv topic:astro-ph.SR |
arxiv_dataset-75311607.05549 | On the modularity of elliptic curves over a composite field of some real
quadratic fields
math.NT
Let $K$ be a composite field of some real quadratic fields. We give a
sufficient condition on $K$ such that all elliptic curves over $K$ is modular.
| arxiv topic:math.NT |
arxiv_dataset-75321607.05649 | A search for low-energy neutrino and antineutrino signals correlated
with gamma-ray bursts with Borexino
astro-ph.HE
A search for neutrino and antineutrino events correlated with 2,350 gamma-ray
bursts (GRBs) is performed with Borexino data collected between December 2007
and November 2015. No statistically significant excess over background is
observed. We look for electron antineutrinos ($\bar{\nu}_e$) that inverse beta
decay on protons with energies from 1.8\,MeV to 15\,MeV and set the best limit
on the neutrino fluence from GRBs below 8\,MeV. The signals from neutrinos and
antineutrinos from GRBs that scatter on electrons are also searched for, a
detection channel made possible by the particularly radio-pure scintillator of
Borexino. We obtain currently the best limits on the neutrino fluence of all
flavors and species below 7\,MeV. Finally, time correlations between GRBs and
bursts of events are investigated. Our analysis combines two semi-independent
data acquisition systems for the first time: the primary Borexino readout
optimized for solar neutrino physics up to a few MeV, and a fast waveform
digitizer system tuned for events above 1\,MeV.
| arxiv topic:astro-ph.HE |
arxiv_dataset-75331607.05749 | PRIIME: A Generic Framework for Interactive Personalized Interesting
Pattern Discovery
cs.LG
The traditional frequent pattern mining algorithms generate an exponentially
large number of patterns of which a substantial proportion are not much
significant for many data analysis endeavors. Discovery of a small number of
personalized interesting patterns from the large output set according to a
particular user's interest is an important as well as challenging task.
Existing works on pattern summarization do not solve this problem from the
personalization viewpoint. In this work, we propose an interactive pattern
discovery framework named PRIIME which identifies a set of interesting patterns
for a specific user without requiring any prior input on the interestingness
measure of patterns from the user. The proposed framework is generic to support
discovery of the interesting set, sequence and graph type patterns. We develop
a softmax classification based iterative learning algorithm that uses a limited
number of interactive feedback from the user to learn her interestingness
profile, and use this profile for pattern recommendation. To handle sequence
and graph type patterns PRIIME adopts a neural net (NN) based unsupervised
feature construction approach. We also develop a strategy that combines
exploration and exploitation to select patterns for feedback. We show
experimental results on several real-life datasets to validate the performance
of the proposed method. We also compare with the existing methods of
interactive pattern discovery to show that our method is substantially superior
in performance. To portray the applicability of the framework, we present a
case study from the real-estate domain.
| arxiv topic:cs.LG |
arxiv_dataset-75341607.05849 | Spin Multiplicities
hep-th math-ph math.MP math.RT
The number of times spin s appears in the Kronecker product of n spin j
representations is computed, and the large n asymptotic behavior of the result
is obtained. Applications are briefly sketched.
| arxiv topic:hep-th math-ph math.MP math.RT |
arxiv_dataset-75351607.05949 | Main Physical Aspects of the Mathematical Conception of Energy in
Thermodynamics
physics.gen-ph
We consider the main physical notions and phenomena described by the author
in his mathematical theory of thermodynamics. The new mathematical model yields
the equation of state for a wide class of classical gases consisting of
non-polar molecules provided that the spinodal, the critical isochore and the
second virial coefficient are given. As an example, the spinodal, the critical
isochore and the second virial coefficient are taken from the Van-der-Waals
model. For this specific example, the isotherms constructed on the basis of the
author's model are compared to the Van-der-Waals isotherms, obtained from
completely different considerations.
| arxiv topic:physics.gen-ph |
arxiv_dataset-75361607.06049 | Energy-Momentum Squared Gravity
gr-qc astro-ph.CO
A new covariant generalization of Einstein's general relativity is developed
which allows the existence of a term proportional to
$T_{\alpha\beta}T^{\alpha\beta}$ in the action functional of the theory
($T_{\alpha\beta}$ is the energy-momentum tensor). Consequently the relevant
field equations are different from general relativity only in the presence of
matter sources. In the case of a charged black hole, we find exact solutions
for the field equations. Applying this theory to a homogeneous and isotropic
space-time, we find that there is a maximum energy density $\rho_{\text{max}}$,
and correspondingly a minimum length $a_{\text{min}}$, at early universe. This
means that there is a bounce at early times and this theory avoids the
existence of an early time singularity. Moreover we show that this theory
possesses a true sequence of cosmological eras. Also, we argue that although in
the context of the standard cosmological model the cosmological constant
$\Lambda$ does not play any important role in the early times and becomes
important only after the matter dominated era, in this theory the "repulsive"
nature of the cosmological constant plays a crucial role at early times for
resolving the singularity.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-75371607.06149 | Normal bundles of rational curves in projective space
math.AG
Let $b_{\bullet}$ be a sequence of integers $1 < b_1 \leq b_2 \leq \cdots
\leq b_{n-1}$. Let $M(b_{\bullet})$ be the space parameterizing nondegenerate,
rational curves of degree $e$ in $\mathbb{P}^n$ with ordinary singularities
such that the normal bundle has the splitting type
$\bigoplus_{i=1}^{n-1}\mathcal{O}(e+b_i)$. When $n=3$, celebrated results of
Eisenbud, Van de Ven, Ghione and Sacchiero show that $M(b_{\bullet})$ is
irreducible of the expected dimension. We show that when $n \geq 5$, these loci
are generally reducible with components of higher than the expected dimension.
We give examples where the number of components grows linearly with $n$. These
generalize an example of Alzati and Re.
| arxiv topic:math.AG |
arxiv_dataset-75381607.06249 | Radiative transfer of acoustic waves in continuous complex media: Beyond
the Helmholtz equation
physics.class-ph
Heterogeneity can be accounted for by a random potential in the wave
equation. For acoustic waves in a fluid with fluctuations of both density and
compressibility (as well as for electromagnetic waves in a medium with
fluctuation of both permittivity and permeability) the random potential entails
a scalar and an operator contribution. For simplicity, the latter is usually
overlooked in multiple scattering theory: whatever the type of waves, this
simplification amounts to considering the Helmholtz equation with a sound speed
$c$ depending on position $\mathbf{r}$. In this work, a radiative transfer
equation is derived from the wave equation, in order to study energy transport
through a multiple scattering medium. In particular, the influence of the
operator term on various transport parameters is studied, based on the
diagrammatic approach of multiple scattering. Analytical results are obtained
for fundamental quantities of transport theory such as the transport mean-free
path $\ell^*$, scattering phase function $f$ and anisotropy factor $g$.
Discarding the operator term in the wave equation is shown to have a
significant impact on $f$ and $g$, yet limited to the low-frequency regime
i.e., when the correlation length of the disorder $\ell_c$ is smaller than or
comparable to the wavelength $\lambda$. More surprisingly, discarding the
operator part has a significant impact on the transport mean-free path $\ell^*$
whatever the frequency regime. When the scalar and operator terms have
identical amplitudes, the discrepancy on the transport mean-free path is around
$300\,\%$ in the low-frequency regime, and still above $30\,\%$ for
$\ell_c/\lambda=10^3$ no matter how weak fluctuations of the disorder are.
Analytical results are supported by numerical simulations of the wave equation
and Monte Carlo simulations.
| arxiv topic:physics.class-ph |
arxiv_dataset-75391607.06349 | Fast Robust Monocular Depth Estimation for Obstacle Detection with Fully
Convolutional Networks
cs.RO cs.CV
Obstacle Detection is a central problem for any robotic system, and critical
for autonomous systems that travel at high speeds in unpredictable environment.
This is often achieved through scene depth estimation, by various means. When
fast motion is considered, the detection range must be longer enough to allow
for safe avoidance and path planning. Current solutions often make assumption
on the motion of the vehicle that limit their applicability, or work at very
limited ranges due to intrinsic constraints. We propose a novel
appearance-based Object Detection system that is able to detect obstacles at
very long range and at a very high speed (~300Hz), without making assumptions
on the type of motion. We achieve these results using a Deep Neural Network
approach trained on real and synthetic images and trading some depth accuracy
for fast, robust and consistent operation. We show how photo-realistic
synthetic images are able to solve the problem of training set dimension and
variety typical of machine learning approaches, and how our system is robust to
massive blurring of test images.
| arxiv topic:cs.RO cs.CV |
arxiv_dataset-75401607.06449 | First-principles approach to excitons in time-resolved and
angle-resolved photoemission spectra
cond-mat.mes-hall cond-mat.other
We show that any {\em quasi-particle} or GW approximation to the self-energy
does not capture excitonic features in time-resolved (TR) photoemission
spectroscopy. In this work we put forward a first-principles approach and
propose a feasible diagrammatic approximation to solve this problem. We also
derive an alternative formula for the TR photocurrent which involves a single
time-integral of the lesser Green's function. The diagrammatic approximation
applies to the {\em relaxed} regime characterized by the presence of
quasi-stationary excitons and vanishing polarization. The main distinctive
feature of the theory is that the diagrams must be evaluated using {\em
excited} Green's functions. As this is not standard the analytic derivation is
presented in detail. The final result is an expression for the lesser Green's
function in terms of quantities that can all be calculated {\em ab initio}. The
validity of the proposed theory is illustrated in a one-dimensional model
system with a direct gap. We discuss possible scenarios and highlight some
universal features of the exciton peaks. Our results indicate that the exciton
dispersion can be observed in TR {\em and} angle-resolved photoemission.
| arxiv topic:cond-mat.mes-hall cond-mat.other |
arxiv_dataset-75411607.06549 | Effect of nematic order on the low-energy spin fluctuations in detwinned
BaFe$_{1.935}$Ni$_{0.065}$As$_2$
cond-mat.supr-con
The origin of nematic order remains one of the major debates in iron-based
superconductors. In theories based on spin nematicity, one major prediction is
that the spin-spin correlation length at (0,$\pi$) should decrease with
decreasing temperature below the structural transition temperature $T_s$. Here
we report inelastic neutron scattering studies on the low-energy spin
fluctuations in BaFe$_{1.935}$Ni$_{0.065}$As$_2$ under uniaxial pressure. Both
intensity and spin-spin correlation start to show anisotropic behavior at high
temperature, while the reduction of the spin-spin correlation length at
(0,$\pi$) happens just below $T_s$, suggesting strong effect of nematic order
on low-energy spin fluctuations. Our results favor the idea that treats the
spin degree of freedom as the driving force of the electronic nematic order.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-75421607.06649 | The dynamics of quasiregular maps of punctured space
math.DS math.CV
The Fatou-Julia iteration theory of rational and transcendental entire
functions has recently been extended to quasiregular maps in more than two real
dimensions. Our goal in this paper is similar; we extend the iteration theory
of analytic self-maps of the punctured plane to quasiregular self-maps of
punctured space.
We define the Julia set as the set of points for which the complement of the
forward orbit of any neighbourhood of the point is a finite set. We show that
the Julia set is non-empty, and shares many properties with the classical Julia
set of an analytic function. These properties are stronger than those known to
hold for the Julia set of a general quasiregular map of space.
We define the quasi-Fatou set as the complement of the Julia set, and
generalise a result of Baker concerning the topological properties of the
components of this set. A key tool in the proof of these results is a version
of the fast escaping set. We generalise various results of Marti-Pete
concerning this set, for example showing that the Julia set is equal to the
boundary of the fast escaping set.
| arxiv topic:math.DS math.CV |
arxiv_dataset-75431607.06749 | Spatiotemporal Characterization of Supercontinuum Extending from the
Visible to the Mid-Infrared in Multimode Graded-Index Optical Fiber
physics.optics
We experimentally demonstrate that pumping a graded-index multimode fiber
with sub-ns pulses from a microchip Nd:YAG laser leads to spectrally flat
supercontinuum generation with a uniform bell-shaped spatial beam profile
extending from the visible to the mid-infrared at 2500\,nm. We study the
development of the supercontinuum along the multimode fiber by the cut-back
method, which permits us to analyze the competition between the Kerr-induced
geometric parametric instability and stimulated Raman scattering. We also
performed a spectrally resolved temporal analysis of the supercontinuum
emission.
| arxiv topic:physics.optics |
arxiv_dataset-75441607.06849 | Reciprocal Graphical Models for Integrative Gene Regulatory Network
Analysis
stat.ME
Constructing gene regulatory networks is a fundamental task in systems
biology. We introduce a Gaussian reciprocal graphical model for inference about
gene regulatory relationships by integrating mRNA gene expression and DNA level
information including copy number and methylation. Data integration allows for
inference on the directionality of certain regulatory relationships, which
would be otherwise indistinguishable due to Markov equivalence. Efficient
inference is developed based on simultaneous equation models. Bayesian model
selection techniques are adopted to estimate the graph structure. We illustrate
our approach by simulations and two applications in ZODIAC pairwise gene
interaction analysis and colon adenocarcinoma pathway analysis.
| arxiv topic:stat.ME |
arxiv_dataset-75451607.06949 | The ERIS Adaptive Optics System
astro-ph.IM
ERIS is the new AO instrument for VLT-UT4 led by a Consortium of Max-Planck
Institut fuer Extraterrestrische Physik, UK-ATC, ETH-Zurich, ESO and INAF. The
ERIS AO system provides NGS mode to deliver high contrast correction and LGS
mode to extend high Strehl performance to large sky coverage. The AO module
includes NGS and LGS wavefront sensors and, with VLT-AOF Deformable Secondary
Mirror and Laser Facility, will provide AO correction to the high resolution
imager NIX (1-5um) and the IFU spectrograph SPIFFIER (1-2.5um). In this paper
we present the preliminary design of the ERIS AO system and the estimated
correction performance.
| arxiv topic:astro-ph.IM |
arxiv_dataset-75461607.07049 | Local Stellar Kinematics from RAVE data - VII. Metallicity Gradients
from Red Clump Stars
astro-ph.GA
We investigate the Milky Way Galaxy's radial and vertical metallicity
gradients using a sample of 47,406 red clump stars from the RAVE DR4. This
sample is more than twice the size of the largest sample in the literature
investigating radial and vertical metallicity gradients. The absolute magnitude
of Groenewegen (2008) is used to determine distances to our sample stars. The
resulting distances agree with the RAVE DR4 distances Binney et al. (2014) of
the same stars. Our photometric method also provides distances to 6185 stars
that are not assigned a distance in RAVE DR4. The metallicity gradients are
calculated with their current orbital positions ($R_{gc}$ and $Z$) and with
their orbital properties (mean Galactocentric distance, $R_{m}$ and $z_{max}$),
as a function of the distance to the Galactic plane:
d[Fe/H]/d$R_{gc}=$-$0.047\pm0.003$ dex/kpc for $0\leq |Z|\leq0.5$ kpc and
d[Fe/H]/d$R_m=$-$0.025\pm0.002$ dex/kpc for $0\leq z_{max}\leq0.5$ kpc. This
reaffirms the radial metallicity gradient in the thin disc but highlights that
gradients are sensitive to the selection effects caused by the difference
between $R_{gc}$ and $R_{m}$. The radial gradient is flat in the distance
interval 0.5-1 kpc from the plane and then becomes positive greater than 1 kpc
from the plane. The radial metallicity gradients are also eccentricity
dependent. We showed that d[Fe/H]/d$R_m=$-$0.089\pm0.010$, -$0.073\pm0.007$,
-$0.053\pm0.004$ and -$0.044\pm0.002$ dex/kpc for $e_p\leq0.05$, $e_p\leq0.07$,
$e_p\leq0.10$ and $e_p\leq0.20$ sub-samples, respectively, in the distance
interval $0\leq z_{max}\leq0.5$ kpc. Similar trend is found for vertical
metallicity gradients. Both the radial and vertical metallicity gradients are
found to become shallower as the eccentricity of the sample increases. These
findings can be used to constrain different formation scenarios of the thick
and thin discs.
| arxiv topic:astro-ph.GA |
arxiv_dataset-75471607.07149 | Efficient quantum circuits for dense and non-unitary operators
quant-ph
Circulant matrices are an important family of operators, which have a wide
range of applications in science and engineering related fields. They are in
general non-sparse and non-unitary. In this paper, we present efficient quantum
circuits to implement circulant operators using fewer resources and with lower
complexity than existing methods. Moreover, our quantum circuits can be readily
extended to the implementation of Toeplitz, Hankel, and block circulant
matrices. Efficient quantum algorithms to implement the inverses and products
of circulant operators are also provided.
| arxiv topic:quant-ph |
arxiv_dataset-75481607.07249 | An Evolutionary Algorithm to Learn SPARQL Queries for
Source-Target-Pairs: Finding Patterns for Human Associations in DBpedia
cs.AI cs.DB cs.NE stat.ML
Efficient usage of the knowledge provided by the Linked Data community is
often hindered by the need for domain experts to formulate the right SPARQL
queries to answer questions. For new questions they have to decide which
datasets are suitable and in which terminology and modelling style to phrase
the SPARQL query.
In this work we present an evolutionary algorithm to help with this
challenging task. Given a training list of source-target node-pair examples our
algorithm can learn patterns (SPARQL queries) from a SPARQL endpoint. The
learned patterns can be visualised to form the basis for further investigation,
or they can be used to predict target nodes for new source nodes.
Amongst others, we apply our algorithm to a dataset of several hundred human
associations (such as "circle - square") to find patterns for them in DBpedia.
We show the scalability of the algorithm by running it against a SPARQL
endpoint loaded with > 7.9 billion triples. Further, we use the resulting
SPARQL queries to mimic human associations with a Mean Average Precision (MAP)
of 39.9 % and a Recall@10 of 63.9 %.
| arxiv topic:cs.AI cs.DB cs.NE stat.ML |
arxiv_dataset-75491607.07349 | Integral representations for Horn's $H_2$ function and Olsson's $F_P$
function
math.CA
We derive some Euler type double integral representations for hypergeometric
functions in two variables. In the first part of this paper we deal with Horn's
$H_2$ function, in the second part with Olsson's $F_P$ function. Our double
integral representing the $F_P$ function is compared with the formula for the
same integral representing an $H_2$ function by M. Yoshida (Hiroshima Math. J.
10 (1980), 329-335 and M. Kita (Japan. J. Math. 18 (1992), 25-74). As specified
by Kita, their integral is defined by a homological approach. We present a
classical double integral version of Kita's integral, with outer integral over
a Pochhammer double loop, which we can evaluate as $H_2$ just as Kita did for
his integral. Then we show that shrinking of the double loop yields a sum of
two double integrals for $F_P$.
| arxiv topic:math.CA |
arxiv_dataset-75501607.07449 | Classical and quantum particle dynamics in univariate background fields
hep-th
We investigate deviations from the plane wave model in the interaction of
charged particles with strong electromagnetic fields. A general result is that
integrability of the dynamics is lost when going from lightlike to timelike or
spacelike field dependence. For a special scenario in the classical regime we
show how the radiation spectrum in the spacelike (undulator) case becomes
well-approximated by the plane wave model in the high energy limit, despite the
two systems being Lorentz inequivalent. In the quantum problem, there is no
analogue of the WKB-exact Volkov solution. Nevertheless, WKB and uniform-WKB
approaches give good approximations in all cases considered. Other approaches
that reduce the underlying differential equations from second to first order
are found to miss the correct physics for situations corresponding to barrier
transmission and wide-angle scattering.
| arxiv topic:hep-th |
arxiv_dataset-75511607.07549 | Concentration of Measure for Radial Distributions and Consequences for
Statistical Modeling
math.ST stat.TH
Motivated by problems in high-dimensional statistics such as mixture modeling
for classification and clustering, we consider the behavior of radial densities
as the dimension increases. We establish a form of concentration of measure,
and even a convergence in distribution, under additional assumptions. This
extends the well-known behavior of the normal distribution (its concentration
around the sphere of radius square-root of the dimension) to other radial
densities. We draw some possible consequences for statistical modeling in
high-dimensions, including a possible universality property of Gaussian
mixtures.
| arxiv topic:math.ST stat.TH |
arxiv_dataset-75521607.07649 | Siegert State Approach to Quantum Defect Theory
physics.atom-ph nucl-th
The Siegert states are approached in framework of Bloch-Lane-Robson formalism
for quantum collisions. The Siegert state is not described by a pole of Wigner
R- matrix but rather by the equation $1- R_{nn}L_n = 0$, relating R- matrix
element $R_{nn}$ to decay channel logarithmic derivative $L_n$. Extension of
Siegert state equation to multichannel system results into replacement of
channel R- matrix element $R_{nn}$ by its reduced counterpart ${\cal R}_{nn}$.
One proves the Siegert state is a pole, $(1 - {\cal R}_{nn} L_{n})^{-1}$, of
multichannel collision matrix. The Siegert equation $1 - {\cal R}_{nn} L_{n} =
0$, ($n$ - Rydberg channel), implies basic results of Quantum Defect Theory as
Seaton's theorem, complex quantum defect, channel resonances and threshold
continuity of averaged multichannel collision matrix elements.
| arxiv topic:physics.atom-ph nucl-th |
arxiv_dataset-75531607.07749 | Some basic properties of G-Calculus and its applications in numerical
analysis
math.GM
Objective of this paper is to introduce a new type of calculus which will be
called G-Calculus based on non-Newtonian calculus introduced by Grossman and
Katz \cite{GrossmanKatz}. The basic difference between geometric calculus
defined by Grossman and Katz and the present G-calculus is that Grossman took
the values of the argument as $x, x+ h, x+2h,...$ but here in G-calculus we
take the values as $x, x\oplus h, x\oplus e^2\odot h, x\oplus e^3\odot h....$
This calculus will have great deal with numerical analysis which are discussed
in the last section of this paper.
| arxiv topic:math.GM |
arxiv_dataset-75541607.07849 | Facing ADAS validation complexity with usage oriented testing
cs.CY cs.SE
Validating Advanced Driver Assistance Systems (ADAS) is a strategic issue,
since such systems are becoming increasingly widespread in the automotive
field. ADAS bring extra comfort to drivers, and this has become a selling
point. But these functions, while useful, must not affect the general safety of
the vehicle which is the manufacturer's responsibility. A significant number of
current ADAS are based on vision systems, and applications such as obstacle
detection and detection of pedestrians have become essential components of
functions such as automatic emergency braking. These systems that preserve and
protect road users take on even more importance with the arrival of the new
Euro NCAP protocols. Therefore the robustness and reliability of ADAS functions
cannot be neglected and car manufacturers need to have tools to ensure that the
ADAS functions running on their vehicles operate with the utmost safety.
Furthermore, the complexity of these systems in conjunction with the nearly
infinite number of parameter combinations related to the usage profile of
functions based on image sensors push us to think about testing optimization
methods and tool standards to support the design and validation phases of ADAS
systems. The resources required for the validation using current methods make
them actually less and less adapted to new active safety features, which induce
very strong dependability requirements. Today, to test the camera-based ADAS,
test vehicles are equipped with these systems and are performing long hours of
driving that can last for years. These tests are used to validate the use of
the function and to verify its response to the requirements described in the
specifications without considering the functional safety standard ISO26262.
| arxiv topic:cs.CY cs.SE |
arxiv_dataset-75551607.07949 | Nonminimal De Rham-Hodge Operators and Non-commutative Residue
math.DG
In this paper, we get a Kastler-Kalau-Walze type theorem associated to
nonminimal de Rham-Hodge operators on compact manifolds with boundary. We give
two kinds of operator-theoretic explanations of the gravitational action in the
case of four dimensional compact manifolds with flat boundary.
| arxiv topic:math.DG |
arxiv_dataset-75561607.08049 | Infrared fingerprints of few-layer black phosphorus
cond-mat.mes-hall
Black phosphorus is an infrared layered material. Its bandgap complements
other widely studied two-dimensional materials: zero-gap graphene and
visible/near-infrared gap transition metal dichalcogenides. Though highly
desirable, a comprehensive infrared characterization is still lacking. Here we
report a systematic infrared study of mechanically exfoliated few-layer black
phosphorus, with thickness ranging from 2 to 15 layers and photon energy
spanning from 0.25 to 1.36 eV. Each few-layer black phosphorus exhibits a
thickness-dependent unique infrared spectrum with a series of absorption
resonances, which reveals the underlying electronic structure evolution and
serves as its IR fingerprints. Surprisingly, unexpected absorption features,
which are associated with the forbidden optical transitions, have been
observed. Furthermore, we unambiguously demonstrate that controllable uniaxial
strain can be used as a convenient and effective approach to tune the
electronic structure of few-layer black phosphorus. Our study paves the way for
black phosphorus applications in infrared photonics and optoelectronics.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-75571607.08149 | N-opcode Analysis for Android Malware Classification and Categorization
cs.CR cs.AI
Malware detection is a growing problem particularly on the Android mobile
platform due to its increasing popularity and accessibility to numerous third
party app markets. This has also been made worse by the increasingly
sophisticated detection avoidance techniques employed by emerging malware
families. This calls for more effective techniques for detection and
classification of Android malware. Hence, in this paper we present an n-opcode
analysis based approach that utilizes machine learning to classify and
categorize Android malware. This approach enables automated feature discovery
that eliminates the need for applying expert or domain knowledge to define the
needed features. Our experiments on 2520 samples that were performed using up
to 10-gram opcode features showed that an f-measure of 98% is achievable using
this approach.
| arxiv topic:cs.CR cs.AI |
arxiv_dataset-75581607.08249 | Classification of maximally supersymmetric backgrounds in supergravity
theories
hep-th
We study maximally supersymmetric solutions of all gauged or deformed
supergravity theories in $D \ge 3$ space-time dimensions. For vanishing
background fluxes the space-time background has to be either Minkowski or
anti-de Sitter. We derive a simple criterion for the existence of solutions
with non-trivial fluxes and determine all supergravities that satisfy it. We
show that their solutions coincide with those of the corresponding ungauged
theories and conclude that the known list of maximally supersymmetric solutions
is exhaustive.
| arxiv topic:hep-th |
arxiv_dataset-75591607.08349 | Amplitude determination for $M M \to M M$, $M = \pi, K$ and
cross-sections for $\gamma \gamma \to \pi^+ \pi^-, \pi^0 \pi^0, \pi^0 \eta$
in a chiral model
hep-ph
Dai and Pennington have performed a comprehensive analysis of essentially all
pion and kaon pair production data from two-photon collisions below 1.5 GeV,
including all high statistics results from Belle, as well as the older data
from Mark II at SLAC, CELLO at DESY, and Crystal Ball at SLAC. Imposing the
basic constraints required by analyticity, unitarity, and crossing symmetry and
making use of Low's low-energy theorem for QED, they were able to extract the
final-state, strong-interaction scattering amplitudes for the intermediate $\pi
\pi \to \pi \pi$ and $\pi \pi \to K \overline{K}$ reactions in a
model-independent fashion. In addition, they provided good fits to the
respective $\gamma \gamma \to \pi \pi$ cross-sections that are known in the
low-energy sector in the restricted angular range, $| \cos \theta | < 0.6 -
0.8$. Using the parameters obtained in this fashion, these authors constructed
the $\gamma \gamma \to \pi \pi$ cross-sections integrated over the full angular
range. In the present work, we use a version of chiral perturbation theory
developed by Oller and Oset to evaluate the final-state, strong-interaction
amplitudes theoretically, and we compare our low-energy QCD-based results with
the amplitudes extracted by Dai and Pennington. We also calculate the $\gamma
\gamma \to \pi \pi$ cross-sections (integrated over the full angular range) and
compare them with those obtained by Dai and Pennington. These calculations give
a more detailed insight into the fit of chiral perturbation theory, not just to
the measured $\gamma \gamma \to \pi \pi$ cross-sections, as is usually
presented, but rather to a higher level of detail through the available
analysis of the experimental data for the underlying final-state,
strong-interaction, meson-meson scattering amplitudes $\pi \pi \to \pi \pi$ and
$\pi \pi \to K \overline{K}$ themselves. The fits appear to be sensible.
| arxiv topic:hep-ph |
arxiv_dataset-75601607.08449 | An Efficient Representation for Filtrations of Simplicial Complexes
cs.CG cs.DS
A filtration over a simplicial complex $K$ is an ordering of the simplices of
$K$ such that all prefixes in the ordering are subcomplexes of $K$. Filtrations
are at the core of Persistent Homology, a major tool in Topological Data
Analysis. In order to represent the filtration of a simplicial complex, the
entire filtration can be appended to any data structure that explicitly stores
all the simplices of the complex such as the Hasse diagram or the recently
introduced Simplex Tree [Algorithmica '14]. However, with the popularity of
various computational methods that need to handle simplicial complexes, and
with the rapidly increasing size of the complexes, the task of finding a
compact data structure that can still support efficient queries is of great
interest.
In this paper, we propose a new data structure called the Critical Simplex
Diagram (CSD) which is a variant of the Simplex Array List (SAL) [Algorithmica
'17]. Our data structure allows one to store in a compact way the filtration of
a simplicial complex, and allows for the efficient implementation of a large
range of basic operations. Moreover, we prove that our data structure is
essentially optimal with respect to the requisite storage space. Finally, we
show that the CSD representation admits fast construction algorithms for Flag
complexes and relaxed Delaunay complexes.
| arxiv topic:cs.CG cs.DS |
arxiv_dataset-75611607.08549 | Inverse problem for multi-body interaction of nonlinear waves
cond-mat.dis-nn cond-mat.stat-mech physics.optics
The inverse problem is studied in multi-body systems with nonlinear dynamics
representing, e.g., phase-locked wave systems, standard multimode and random
lasers. Using a general model for four-body interacting complex-valued
variables we test two methods based on pseudolikelihood, respectively with
regularization and with decimation, to determine the coupling constants from
sets of measured configurations. We test statistical inference predictions for
increasing number of sampled configurations and for an externally tunable {\em
temperature}-like parameter mimicing real data noise and helping minimization
procedures. Analyzed models with phasors and rotors are generalizations of
problems of real-valued spherical problems (e.g., density fluctuations),
discrete spins (Ising and vectorial Potts) or finite number of states (standard
Potts): inference methods presented here can, then, be straightforward applied
to a large class of inverse problems.
| arxiv topic:cond-mat.dis-nn cond-mat.stat-mech physics.optics |
arxiv_dataset-75621607.08649 | Complete minimal submanifolds with nullity in Euclidean space
math.DG
In this paper, we investigate minimal submanifolds in Euclidean space with
positive index of relative nullity. Let $M^m$ be a complete Riemannian manifold
and let $f\colon M^m\to\R^n$ be a minimal isometric immersion with index of
relative nullity at least $m-2$ at any point. We show that if the Omori-Yau
maximum principle for the Laplacian holds on $M^m$, for instance, if the scalar
curvature of $M^m$ does not decrease to $-\infty$ too fast or if the immersion
$f$ is proper, then the submanifold must be a cylinder over a minimal surface.
| arxiv topic:math.DG |
arxiv_dataset-75631607.08749 | Simultaneous Water Vapor and Dry Air Optical Path Length Measurements
and Compensation with the Large Binocular Telescope Interferometer
astro-ph.IM
The Large Binocular Telescope Interferometer uses a near-infrared camera to
measure the optical path length variations between the two AO-corrected
apertures and provide high-angular resolution observations for all its science
channels (1.5-13 $\mu$m). There is however a wavelength dependent component to
the atmospheric turbulence, which can introduce optical path length errors when
observing at a wavelength different from that of the fringe sensing camera.
Water vapor in particular is highly dispersive and its effect must be taken
into account for high-precision infrared interferometric observations as
described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this
paper, we describe the new sensing approach that has been developed at the LBT
to measure and monitor the optical path length fluctuations due to dry air and
water vapor separately. After reviewing the current performance of the system
for dry air seeing compensation, we present simultaneous H-, K-, and N-band
observations that illustrate the feasibility of our feedforward approach to
stabilize the path length fluctuations seen by the LBTI nuller.
| arxiv topic:astro-ph.IM |
arxiv_dataset-75641607.08849 | Caveat on the Boltzmann distribution function use in biology
q-bio.QM
Sigmoid semilogarithmic functions with shape of Boltzmann equations, have
become extremely popular to describe diverse biological situations. Part of the
popularity is due to the easy avail- ability of software which fits Boltzmann
functions to data, without much knowledge of the fitting procedure or the
statistical properties of the parameters derived from the procedure. The
purpose of this paper is to explore the plasticity of the Boltzmann function to
fit data, some aspects of the optimization procedure to fit the function to
data and how to use this plastic function to differentiate the effect of
treatment on data and to attest the statistical significance of treatment
effect on the data.
| arxiv topic:q-bio.QM |
arxiv_dataset-75651608.00038 | Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2
cond-mat.mes-hall
We investigate valley dynamics associated with trions in monolayer tungsten
diselenide (WSe2) using polarization resolved two-color pump-probe
spectroscopy. When tuning the pump and probe energy across the trion resonance,
distinct trion valley polarization dynamics are observed as a function of
energy and attributed to the intra-valley and inter-valley trions in monolayer
WSe2. We observe no decay of a near-unity valley polarization associated with
the intra-valley trions during ~ 25 ps, while the valley polarization of the
inter-valley trions exhibits a fast decay of ~ 4 ps. Furthermore, we show that
resonant excitation is a prerequisite for observing the long-lived valley
polarization associated with the intra-valley trion. The exceptionally robust
valley polarization associated with resonantly created intra-valley trions
discovered here may be explored for future valleytronic applications such as
valley Hall effects.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-75661608.00138 | Heterogeneous Strategy Particle Swarm Optimization
cs.NE
PSO is a widely recognized optimization algorithm inspired by social swarm.
In this brief we present a heterogeneous strategy particle swarm optimization
(HSPSO), in which a proportion of particles adopt a fully informed strategy to
enhance the converging speed while the rest are singly informed to maintain the
diversity. Our extensive numerical experiments show that HSPSO algorithm is
able to obtain satisfactory solutions, outperforming both PSO and the fully
informed PSO. The evolution process is examined from both structural and
microscopic points of view. We find that the cooperation between two types of
particles can facilitate a good balance between exploration and exploitation,
yielding better performance. We demonstrate the applicability of HSPSO on the
filter design problem.
| arxiv topic:cs.NE |
arxiv_dataset-75671608.00238 | Constituent counting rule for exclusive production of heavy
quarkoniumlike exotic resonance and a light hadron
hep-ph
The exclusive processes are considered, where a point-like source of heavy
quark-antiquark pairs $Q \bar Q$, e.g. their electromagnetic current, produces
a pair consisting of a heavy quarkoniumlike exotic meson (tetraquark) or baryon
(pentaquark) and a light meson or an antibaryon. For a sufficiently large mass
of the heavy quark $m_Q$ there is a range of the energy $E$ above the $Q \bar
Q$ threshold, where $E \ll m_Q$ and still the energy is large compared to the
strong interaction scale, $E \gg \Lambda_{QCD}$. It is shown that in this
energy range, where the heavy quarks are nonrelelativistic, a specific
`intermediate asymptotic' behavior sets in determined by the number $n$ of the
pairs of constituent quarks, with the rate scaling as $E^{1-n}$.
| arxiv topic:hep-ph |
arxiv_dataset-75681608.00338 | Leading order relativistic corrections to the dipole polarizability of
the hydrogen molecular ions
physics.atom-ph
The static dipole polarizability for the hydrogen molecular ions H$_2^+$,
HD$^+$, and D$_2^+$ are calculated. These new data for polarizability takes
into account the leading order relativistic corrections to the wave function of
the three-body system resulted from the Breit-Pauli Hamiltonian of $m\alpha^4$
order. Our study covers a wide range of rotational ($L=0-5$) and vibrational
($v=0-10$) states, which are of practical interest for precision spectroscopy
of the hydrogen molecular ions.
| arxiv topic:physics.atom-ph |
arxiv_dataset-75691608.00438 | A new peridynamic formulation with shear deformation for elastic solid
cond-mat.soft cond-mat.mtrl-sci
We propose a new peridynamic formulation with shear deformation for linear
elastic solid. The key idea lies in subtracting the rigid body rotation part
from the total deformation. Based on the strain energy equivalence between
classic local model and non-local model, the bond force vector is derived. A
new damage rule of maximal deviatoric bond strain for elastic brittle fracture
is proposed in order to account for both the tensile damage and shear damage.
2D and 3D numerical examples are tested to verify the accuracy of the current
peridynamics. The new damage rule is applied to simulate the propagation of
Mode I, II and III cracks.
| arxiv topic:cond-mat.soft cond-mat.mtrl-sci |
arxiv_dataset-75701608.00538 | Directional Statistics of Preferential Orientations of Two Shapes in
Their Aggregate and Its Application to Study Preferential Attachment of
Nanoparticles
stat.AP
Nanoscientists have long conjectured that adjacent nanoparticles aggregate
with one another in certain preferential directions during a chemical synthesis
of nanoparticles, which is referred to the oriented attachment. For the study
of the oriented attachment, the microscopy and nanoscience communities have
used dynamic electron microscopy for direct observations of nanoparticle
aggregation and have been so far relying on manual and qualitative analysis of
the observations. We propose a statistical approach for studying the oriented
attachment quantitatively with multiple aggregation examples in imagery
observations. We abstract an aggregation by an event of two primary geometric
objects merging into a secondary geometric object. We use a point set
representation to describe the geometric features of the primary objects and
the secondary object, and formulated the alignment of two point sets to one
point set to estimate the orientation angles of the primary objects in the
secondary object. The estimated angles are used as data to estimate the
probability distribution of the orientation angles and test important
hypotheses statistically. The proposed approach was applied for our motivating
example, which demonstrated that nanoparticles of certain geometries have
indeed preferential orientations in their aggregates.
| arxiv topic:stat.AP |
arxiv_dataset-75711608.00638 | The Light and Heavy Higgs Interpretation of the MSSM
hep-ph hep-ex
We perform a parameter scan of the phenomenological Minimal Supersymmetric
Standard Model (pMSSM) with eight parameters taking into account the
experimental Higgs boson results from Run I of the LHC and further low-energy
observables. We investigate various MSSM interpretations of the Higgs signal at
125 GeV. First, we consider the case where the light CP-even Higgs boson of the
MSSM is identified with the discovered Higgs boson. In this case it can
impersonate the SM Higgs-like signal either in the decoupling limit, or in the
limit of alignment without decoupling. In the latter case, the other states in
the Higgs sector can also be light, offering good prospects for upcoming LHC
searches and for searches at future colliders. Second, we demonstrate that the
heavy CP-even Higgs boson is still a viable candidate to explain the Higgs
signal - albeit only in a highly constrained parameter region, that will be
probed by LHC searches for the CP-odd Higgs boson and the charged Higgs boson
in the near future. As a guidance for such searches we provide new benchmark
scenarios that can be employed to maximize the sensitivity of the experimental
analysis to this interpretation.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-75721608.00738 | Calculating correlation coefficient for Gaussian copula
stat.ME
When Gaussian copula with linear correlation coefficient is used to model
correlated random variables, one crucial issue is to determine a suitable
correlation coefficient $\rho_z$ in normal space for two variables with
correlation coefficient $\rho_x$. This paper attempts to address this problem.
For two continuous variables, the marginal transformation is approximated by a
weighted sum of Hermite polynomials, then, with Mehler's formula, a polynomial
of $\rho_z$ is derived to approximate the function relationship between
$\rho_x$ and $\rho_z$. If a discrete variable is involved, the marginal
transformation is decomposed into piecewise continuous ones, and $\rho_x$ is
expressed as a polynomial of $\rho_z$ by Taylor expansion. For a given
$\rho_x$, $\rho_z$ can be efficiently determined by solving a polynomial
equation.
| arxiv topic:stat.ME |
arxiv_dataset-75731608.00838 | The cause of spatial structure in solar He I 1083 nm multiplet images
astro-ph.SR
Context. The He i 1083 nm is a powerful diagnostic for inferring properties
of the upper solar chromosphere, in particular for the magnetic field. The
basic formation of the line in one-dimensional models is well understood, but
the influence of the complex 3D structure of the chromosphere and corona has
however never been investigated. This structure must play an essential role
because images taken in He i 1083 nm show structures with widths down to 100
km. Aims. To understand the effect of the three-dimensional temperature and
density structure in the solar atmosphere on the formation of the He i 1083 nm
line. Methods. We solve the non-LTE radiative transfer problem assuming
statistical equilibrium for a simple 9-level helium atom that nevertheless
captures all essential physics. As a model atmosphere we use a snapshot from a
3D radiation-MHD simulation computed with the Bifrost code. Ionising radiation
from the corona is self-consistently taken into account. Results. The emergent
intensity in the He i 1083 nm is set by the source function and the opacity in
the upper chromosphere. The former is dominated by scattering of photospheric
radiation and does not vary much with spatial location. The latter is
determined by the photonionisation rate in the He i ground state continuum, as
well as the electron density in the chromosphere. The spatial variation of the
flux of ionising radiation is caused by the spatially-structured emissivity of
the ionising photons from material at T = 100 kK in the transition region. The
hotter coronal material produces more ionising photons, but the resulting
radiation field is smooth and does not lead to small-scale variation of the UV
flux. The corrugation of the transition region further increases the spatial
variation of the amount of UV radiation in the chromosphere.
| arxiv topic:astro-ph.SR |
arxiv_dataset-75741608.00938 | Evolutionary forces in language change
q-bio.PE cs.CL
Languages and genes are both transmitted from generation to generation, with
opportunity for differential reproduction and survivorship of forms. Here we
apply a rigorous inference framework, drawn from population genetics, to
distinguish between two broad mechanisms of language change: drift and
selection. Drift is change that results from stochasticity in transmission and
it may occur in the absence of any intrinsic difference between linguistic
forms; whereas selection is truly an evolutionary force arising from intrinsic
differences -- for example, when one form is preferred by members of the
population. Using large corpora of parsed texts spanning the 12th century to
the 21st century, we analyze three examples of grammatical changes in English:
the regularization of past-tense verbs, the rise of the periphrastic `do', and
syntactic variation in verbal negation. We show that we can reject stochastic
drift in favor of a selective force driving some of these language changes, but
not others. The strength of drift depends on a word's frequency, and so drift
provides an alternative explanation for why some words are more prone to change
than others. Our results suggest an important role for stochasticity in
language change, and they provide a null model against which selective theories
of language evolution must be compared.
| arxiv topic:q-bio.PE cs.CL |
arxiv_dataset-75751608.01038 | Competing spreading processes and immunization in multiplex networks
cs.SI physics.soc-ph
Epidemic spreading on physical contact network will naturally introduce the
human awareness information diffusion on virtual contact network, and the
awareness diffusion will in turn depress the epidemic spreading, thus forming
the competing spreading processes of epidemic and awareness in a multiplex
networks. In this paper, we study the competing dynamics of epidemic and
awareness, both of which follow the SIR process, in a two-layer networks based
on microscopic Markov chain approach and numerical simulations. We find that
strong capacities of awareness diffusion and self-protection of individuals
could lead to a much higher epidemic threshold and a smaller outbreak size.
However, the self-awareness of individuals has no obvious effect on the
epidemic threshold and outbreak size. In addition, the immunization of the
physical contact network under the interplay between of epidemic and awareness
spreading is also investigated. The targeted immunization is found performs
much better than random immunization, and the awareness diffusion could reduce
the immunization threshold for both type of random and targeted immunization
significantly.
| arxiv topic:cs.SI physics.soc-ph |
arxiv_dataset-75761608.01138 | The asteroseismic potential of TESS: exoplanet-host stars
astro-ph.SR
New insights on stellar evolution and stellar interiors physics are being
made possible by asteroseismology. Throughout the course of the Kepler mission,
asteroseismology has also played an important role in the characterization of
exoplanet-host stars and their planetary systems. The upcoming NASA Transiting
Exoplanet Survey Satellite (TESS) will be performing a near all-sky survey for
planets that transit bright nearby stars. In addition, its excellent
photometric precision, combined with its fine time sampling and long intervals
of uninterrupted observations, will enable asteroseismology of solar-type and
red-giant stars. Here we develop a simple test to estimate the detectability of
solar-like oscillations in TESS photometry of any given star. Based on an
all-sky stellar and planetary synthetic population, we go on to predict the
asteroseismic yield of the TESS mission, placing emphasis on the yield of
exoplanet-host stars for which we expect to detect solar-like oscillations.
This is done for both the target stars (observed at a 2-min cadence) and the
full-frame-image stars (observed at a 30-min cadence). A similar exercise is
also conducted based on a compilation of known host stars. We predict that TESS
will detect solar-like oscillations in a few dozen target hosts (mainly
subgiant stars but also in a smaller number of F dwarfs), in up to 200
low-luminosity red-giant hosts, and in over 100 solar-type and red-giant known
hosts, thereby leading to a threefold improvement in the asteroseismic yield of
exoplanet-host stars when compared to Kepler's.
| arxiv topic:astro-ph.SR |
arxiv_dataset-75771608.01238 | Improving Quality of Hierarchical Clustering for Large Data Series
cs.CL cs.LG
Brown clustering is a hard, hierarchical, bottom-up clustering of words in a
vocabulary. Words are assigned to clusters based on their usage pattern in a
given corpus. The resulting clusters and hierarchical structure can be used in
constructing class-based language models and for generating features to be used
in NLP tasks. Because of its high computational cost, the most-used version of
Brown clustering is a greedy algorithm that uses a window to restrict its
search space. Like other clustering algorithms, Brown clustering finds a
sub-optimal, but nonetheless effective, mapping of words to clusters. Because
of its ability to produce high-quality, human-understandable cluster, Brown
clustering has seen high uptake the NLP research community where it is used in
the preprocessing and feature generation steps.
Little research has been done towards improving the quality of Brown
clusters, despite the greedy and heuristic nature of the algorithm. The
approaches tried so far have focused on: studying the effect of the
initialisation in a similar algorithm; tuning the parameters used to define the
desired number of clusters and the behaviour of the algorithm; and including a
separate parameter to differentiate the window from the desired number of
clusters. However, some of these approaches have not yielded significant
improvements in cluster quality.
In this thesis, a close analysis of the Brown algorithm is provided,
revealing important under-specifications and weaknesses in the original
algorithm. These have serious effects on cluster quality and reproducibility of
research using Brown clustering. In the second part of the thesis, two
modifications are proposed. Finally, a thorough evaluation is performed,
considering both the optimization criterion of Brown clustering and the
performance of the resulting class-based language models.
| arxiv topic:cs.CL cs.LG |
arxiv_dataset-75781608.01338 | Paraconsistency and Word Puzzles
cs.AI cs.LO
Word puzzles and the problem of their representations in logic languages have
received considerable attention in the last decade (Ponnuru et al. 2004;
Shapiro 2011; Baral and Dzifcak 2012; Schwitter 2013). Of special interest is
the problem of generating such representations directly from natural language
(NL) or controlled natural language (CNL). An interesting variation of this
problem, and to the best of our knowledge, scarcely explored variation in this
context, is when the input information is inconsistent. In such situations, the
existing encodings of word puzzles produce inconsistent representations and
break down. In this paper, we bring the well-known type of paraconsistent
logics, called Annotated Predicate Calculus (APC) (Kifer and Lozinskii 1992),
to bear on the problem. We introduce a new kind of non-monotonic semantics for
APC, called consistency preferred stable models and argue that it makes APC
into a suitable platform for dealing with inconsistency in word puzzles and,
more generally, in NL sentences. We also devise a number of general principles
to help the user choose among the different representations of NL sentences,
which might seem equivalent but, in fact, behave differently when inconsistent
information is taken into account. These principles can be incorporated into
existing CNL translators, such as Attempto Controlled English (ACE) (Fuchs et
al. 2008) and PENG Light (White and Schwitter 2009). Finally, we show that APC
with the consistency preferred stable model semantics can be equivalently
embedded in ASP with preferences over stable models, and we use this embedding
to implement this version of APC in Clingo (Gebser et al. 2011) and its Asprin
add-on (Brewka et al. 2015).
| arxiv topic:cs.AI cs.LO |
arxiv_dataset-75791608.01438 | Three friendly walkers
math-ph cond-mat.stat-mech math.CA math.CO math.MP
More than 15 years ago Guttmann and V\"oge [J. Statist. Plann. Inference,
{\bf 101}, 107 (2002)], introduced a model of friendly walkers. Since then it
has remained unsolved. In this paper we provide the exact solution to a closely
allied model, originally introduced by Tsuchiya and Katori [J. Phys. Soc. Japan
{\bf 67}, 1655 (1988)], which essentially only differs in the boundary
conditions. The exact solution is expressed in terms of the reciprocal of the
generating function for vicious walkers which is a D-finite function. However,
ratios of D-finite functions are inherently not D-finite and in this case we
prove that the friendly walkers generating function is the solution to a
non-linear differential equation with polynomial coefficients, it is in other
words D-algebraic. We then show via numerically exact calculations that the
generating function of the original model can also be expressed as a D-finite
function times the reciprocal of the generating function for vicious walkers.
We obtain an expression for this D-finite function in terms of a ${}_{2}F_{1}$
hypergeometric function with a rational pullback and its first and second
derivatives.
| arxiv topic:math-ph cond-mat.stat-mech math.CA math.CO math.MP |
arxiv_dataset-75801608.01538 | News from strong interactions program of the NA61/SHINE experiment
nucl-ex hep-ex
The NA61/SHINE experiment aims to discover the critical point of strongly
interacting matter and study the properties of the onset of deconfinement. This
is performed by a two dimensional phase diagram ($T-\mu_B$) scan of
measurements of particle spectra and fluctuations in proton-proton,
proton-nucleus and nucleus-nucleus interactions as a function of collision
energy and system size.
In this contribution new NA61/SHINE results on negative pion production, as
well as transverse momentum and multiplicity fluctuations in Ar+Sc collisions
are presented. Moreover, the latest results on higher order moments of
net-charge multiplicity distribution in p+p collisions are also discussed. The
Ar+Sc results are compared to NA61 p+p and Be+Be data, as well as to NA49 $A+A$
results.
| arxiv topic:nucl-ex hep-ex |
arxiv_dataset-75811608.01638 | A Modified Stern-Gerlach Experiment Using a Quantum Two-State Magnetic
Field
quant-ph
The Stern-Gerlach experiment has played an important role in our
understanding of quantum behavior. We propose and analyze a modified version of
this experiment where the magnetic field of the detector is in a quantum
superposition, which may be experimentally realized using a superconducting
flux qubit. We show that if incident spin-$1/2$ particles couple with the
two-state magnetic field, a discrete target distribution results that resembles
the distribution in the classical Stern-Gerlach experiment. As an application
of the general result, we compute the distribution for a square waveform of the
incident fermion. This experimental setup allows us to establish: (1) the
quantization of the intrinsic angular momentum of a spin-$1/2$ particle, and
(2) a correlation between EPR pairs leading to nonlocality, without necessarily
collapsing the particle's spin wavefunction.
| arxiv topic:quant-ph |
arxiv_dataset-75821608.01738 | Linear Network Coding over Rings, Part I: Scalar Codes and Commutative
Alphabets
cs.IT math.IT
Fixed-size commutative rings are quasi-ordered such that all scalar linearly
solvable networks over any given ring are also scalar linearly solvable over
any higher-ordered ring. As consequences, if a network has a scalar linear
solution over some finite commutative ring, then (i) the network is also scalar
linearly solvable over a maximal commutative ring of the same size, and (ii)
the (unique) smallest size commutative ring over which the network has a scalar
linear solution is a field. We prove that a commutative ring is maximal with
respect to the quasi-order if and only if some network is scalar linearly
solvable over the ring but not over any other commutative ring of the same
size. Furthermore, we show that maximal commutative rings are direct products
of certain fields specified by the integer partitions of the prime factor
multiplicities of the maximal ring's size.
Finally, we prove that there is a unique maximal commutative ring of size $m$
if and only if each prime factor of $m$ has multiplicity in $\{1,2,3,4,6\}$. In
fact, whenever $p$ is prime and $k \in \{1,2,3,4,6\}$, the unique such maximal
ring of size $p^k$ is the field $GF(p^k)$. However, for every field $GF(p^k)$
with $k\not\in \{1,2,3,4,6\}$, there is always some network that is not scalar
linearly solvable over the field but is scalar linearly solvable over a
commutative ring of the same size. These results imply that for scalar linear
network coding over commutative rings, fields can always be used when the
alphabet size is flexible, but alternative rings may be needed when the
alphabet size is fixed.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-75831608.01838 | Inference from the small scales of cosmic shear with current and future
Dark Energy Survey data
astro-ph.CO
Cosmic shear is sensitive to fluctuations in the cosmological matter density
field, including on small physical scales, where matter clustering is affected
by baryonic physics in galaxies and galaxy clusters, such as star formation,
supernovae feedback and AGN feedback. While muddying any cosmological
information that is contained in small scale cosmic shear measurements, this
does mean that cosmic shear has the potential to constrain baryonic physics and
galaxy formation. We perform an analysis of the Dark Energy Survey (DES)
Science Verification (SV) cosmic shear measurements, now extended to smaller
scales, and using the Mead et al. 2015 halo model to account for baryonic
feedback. While the SV data has limited statistical power, we demonstrate using
a simulated likelihood analysis that the final DES data will have the
statistical power to differentiate among baryonic feedback scenarios. We also
explore some of the difficulties in interpreting the small scales in cosmic
shear measurements, presenting estimates of the size of several other
systematic effects that make inference from small scales difficult, including
uncertainty in the modelling of intrinsic alignment on nonlinear scales,
`lensing bias', and shape measurement selection effects. For the latter two, we
make use of novel image simulations. While future cosmic shear datasets have
the statistical power to constrain baryonic feedback scenarios, there are
several systematic effects that require improved treatments, in order to make
robust conclusions about baryonic feedback.
| arxiv topic:astro-ph.CO |
arxiv_dataset-75841608.01938 | Low-degree factors of random polynomials
math.PR math.NT
Motivated by the question of whether a random polynomial with integer
coefficients is likely to be irreducible, we study the probability that a monic
polynomial with integer coefficients has a low-degree factor over the integers,
which is equivalent to having a low-degree algebraic root. It is known in
certain cases that random polynomials with integer coefficients are very likely
to be irreducible, and our project can be viewed as part of the general program
of testing whether this is a universal behavior exhibited by many random
polynomial models.
Our main result shows that pointwise delocalization of the roots of a random
polynomial can be used to imply that the polynomial is unlikely to have a
low-degree factor over the integers. We apply our main result to a number of
models of random polynomials, including characteristic polynomials of random
matrices, where strong delocalization results are known. Studying a variety of
random matrix models---including iid matrices, symmetric matrices, elliptical
matrices, and adjacency matrices of random graphs and digraphs---we show that,
for a random square matrix with integer entries, the characteristic polynomial
is unlikely to have a low-degree factor over the integers, which is equivalent
to the matrix having an eigenvalue that is algebraic with low degree. Having a
low-degree algebraic eigenvalue generalizes the questions of whether the matrix
has a rational eigenvalue and whether the matrix is singular (i.e., has an
eigenvalue equal to zero).
| arxiv topic:math.PR math.NT |
arxiv_dataset-75851608.02038 | Responding to an enquiry concerning the geographic population structure
(GPS) approach and the origin of Ashkenazic Jews - a reply to Flegontov et al
q-bio.PE
Recently, we investigated the geographical origins of Ashkenazic Jews (AJs)
and their native language Yiddish by applying a biogeographical tool, the
Geographic Population Structure (GPS), to a cohort of 367 exclusively
Yiddish-speaking and multilingual AJs genotyped on the Genochip microarray. GPS
localized most AJs along major ancient trade routes in northeastern Turkey
adjacent to primeval villages with names that may be derived from the word
"Ashkenaz." These findings were compatible with the hypothesis of an
Irano-Turko-Slavic origin for AJs and a Slavic origin for Yiddish and at odds
with the Rhineland hypothesis advocating a German origin of both. Our approach
has been recently adopted by Flegontov et al. (2016a) to trace the origin of
the Siberian Ket people and their language. Recently, Flegontov et al. (2016b)
have raised several questions concerning the accuracy of the Genochip
microarray and GPS, specifically in relation to AJs and Yiddish. Although many
of these issues have been addressed in our previous papers, we take this
opportunity to clarify the principles of the GPS approach, review the recent
biogeographical and ancient DNA findings regarding AJs, and comment on the
origin of Yiddish.
| arxiv topic:q-bio.PE |
arxiv_dataset-75861608.02138 | Quantum Chaos in the Heisenberg Spin Chain: the Effect of
Dzyaloshinskii-Moriya Interaction
cond-mat.stat-mech
Using one-dimensional spin-1/2 systems as prototypes of quantum many-body
systems, we study the emergence of quantum chaos. The main purpose of this work
is to answer the following question: how does the spin-orbit interaction, as a
pure quantum interaction, may lead to the onset of quantum chaos? We consider
three integrable spin-1/2 systems: the Ising, the XX, and the XXZ limits, and
analyze whether quantum chaos develops or not after the addition of the
Dzyaloshinskii-Moriya interaction. We find that, depending on the strength of
the anisotropy parameter, the answer is positive for the XXZ and Ising models,
while no such evidence is observed for the XX model. We also discuss the
relationship between quantum chaos and thermalization.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-75871608.02238 | Resonances for open quantum maps and a fractal uncertainty principle
math.SP math-ph math.AP math.MP nlin.CD
We study eigenvalues of quantum open baker's maps with trapped sets given by
linear arithmetic Cantor sets of dimensions $\delta\in (0,1)$. We show that the
size of the spectral gap is strictly greater than the standard bound
$\max(0,{1\over 2}-\delta)$ for all values of $\delta$, which is the first
result of this kind. The size of the improvement is determined from a fractal
uncertainty principle and can be computed for any given Cantor set. We next
show a fractal Weyl upper bound for the number of eigenvalues in annuli, with
exponent which depends on the inner radius of the annulus.
| arxiv topic:math.SP math-ph math.AP math.MP nlin.CD |
arxiv_dataset-75881608.02338 | A new truncation scheme for BBGKY hierarchy: conservation of energy and
time reversibility
cond-mat.stat-mech math-ph math.MP
We propose a new truncation scheme for Bogoliubov-Born-Green-Kirkwood-Yvon
(BBGKY) hierarchy. We approximate the three particle distribution function
$f_{3}(1,2,3,t)$ in terms of $f_{2}(1,2,t)$, $f_{1}(3,t)$ and two point
correlation functions $\left\lbrace g_{2}(1,3,t), g_{2}(2,3,t)\right\rbrace $.
Further $f_{2}$ is expressed in terms of $f_{1}(1,t)$ and $g_{2}(1,2,t)$ to
close the hierarchy, resulting a set of coupled kinetic equations for $f_{1}$
and $g_{2}$. In this paper we show that, for velocity independent correlations,
the kinetic equation for $f_{1}$ reduces to the model proposed by Martys[Martys
N S 1999 \textit{IJMPC} \textbf{10} 1367-1382]. In the steady state limit, the
kinetic equation for $g_{2}$ reduces to Born-Green-Yvon (BGY) hierarchy for
homogeneous density. We also prove that the present scheme respects the energy
conservation and under specific circumstances, time symmetry \textit{i.e.,}
$\displaystyle \frac{dH(t)}{dt} = 0$ where $H(t)$ refers to the Boltzmann's
H-function.
| arxiv topic:cond-mat.stat-mech math-ph math.MP |
arxiv_dataset-75891608.02438 | Out-of-Time-Order Correlation at a Quantum Phase Transition
cond-mat.quant-gas cond-mat.str-el
In this paper we numerically calculate the out-of-time-order correlation
functions in the one-dimensional Bose-Hubbard model. Our study is motivated by
the conjecture that a system with Lyapunov exponent saturating the upper bound
$2\pi/\beta$ will have a holographic dual to a black hole at finite
temperature. We further conjecture that for a many-body quantum system with a
quantum phase transition, the Lyapunov exponent will have a peak in the quantum
critical region where there exists an emergent conformal symmetry and is absent
of well-defined quasi-particles. With the help of a relation between the
R\'enyi entropy and the out-of-time-order correlation function, we argue that
the out-of-time-order correlation function of the Bose-Hubbard model will also
exhibit an exponential behavior at the scrambling time. By fitting the
numerical results with an exponential function, we extract the Lyapunov
exponents in the one-dimensional Bose-Hubbard model across the quantum critical
regime at finite temperature. Our results on the Bose-Hubbard model support the
conjecture. We also compute the butterfly velocity and propose how the echo
type measurement of this correlator in the cold atom realizations of the
Bose-Hubbard model without inverting the Hamiltonian.
| arxiv topic:cond-mat.quant-gas cond-mat.str-el |
arxiv_dataset-75901608.02538 | Towards the (Mexican) discovery of second class currents at Belle-II
hep-ph hep-ex
Within the SM, the yet unmeasured $\tau^-\to\pi^-\eta^{(\prime)}\nu_\tau$
decays are predicted as a suppressed, isospin-violating effect with branching
ratios $\lesssim\mathcal{O}(10^{-5})$. However, they can also proceed through
other mechanisms (such as charged Higgs exchange) at comparable rates. This has
motivated several studies of the corresponding QCD predictions for these second
class current processes. In this contribution we discuss the prospects for the
discovery of these decays at Belle-II emphasizing the Mexican involvement in
this project. Our branching ratio prediction $\sim1.7\cdot10^{-5}$ (decay
channel with an $\eta$ meson) is well within the reach of Belle-II. The
branching fraction for the decay channel with an $\eta^\prime$ meson is
expected to be between one and two orders of magnitude more suppressed.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-75911608.02638 | Asymptotic laws for random knot diagrams
math.GT math.CO
We study random knotting by considering knot and link diagrams as decorated,
(rooted) topological maps on spheres and pulling them uniformly from among sets
of a given number of vertices $n$, as first established in recent work with
Cantarella and Mastin. The knot diagram model is an exciting new model which
captures both the random geometry of space curve models of knotting as well as
the ease of computing invariants from diagrams.
We prove that unknot diagrams are asymptotically exponentially rare, an
analogue of Sumners and Whittington's landmark result for self-avoiding walks.
Our proof uses the same key idea: We first show that knot diagrams obey a
pattern theorem, which describes their fractal structure. We examine how
quickly this behavior occurs in practice. As a consequence, almost all diagrams
are asymmetric, simplifying sampling from this model. We conclude with
experimental data on knotting in this model. This model of random knotting is
similar to those studied by Diao et al., and Dunfield et al.
| arxiv topic:math.GT math.CO |
arxiv_dataset-75921608.02738 | Reliability Considerations for the Operation of Large Accelerator User
Facilities
physics.acc-ph physics.ins-det
The lecture provides an overview of considerations relevant for achieving
highly reliable operation of accelerator based user facilities. The article
starts with an overview of statistical reliability formalism which is followed
by high reliability design considerations with examples. The article closes
with operational aspects of high reliability such as preventive maintenance and
spares inventory.
| arxiv topic:physics.acc-ph physics.ins-det |
arxiv_dataset-75931608.02838 | Closed-loop robots driven by short-term synaptic plasticity: Emergent
explorative vs. limit-cycle locomotion
q-bio.NC cs.RO nlin.AO
We examine the hypothesis, that short-term synaptic plasticity (STSP) may
generate self-organized motor patterns. We simulated sphere-shaped autonomous
robots, within the LPZRobots simulation package, containing three weights
moving along orthogonal internal rods. The position of a weight is controlled
by a single neuron receiving excitatory input from the sensor, measuring its
actual position, and inhibitory inputs from the other two neurons. The
inhibitory connections are transiently plastic, following physiologically
inspired STSP-rules. We find that a wide palette of motion patterns are
generated through the interaction of STSP, robot, and environment (closed-loop
configuration), including various forward meandering and circular motions,
together with chaotic trajectories. The observed locomotion is robust with
respect to additional interactions with obstacles. In the chaotic phase the
robot is seemingly engaged in actively exploring its environment. We believe
that our results constitute a concept of proof that transient synaptic
plasticity, as described by STSP, may potentially be important for the
generation of motor commands and for the emergence of complex locomotion
patterns, adapting seamlessly also to unexpected environmental feedback. We
observe spontaneous and collision induced mode switchings, finding in addition,
that locomotion may follow transiently limit cycles which are otherwise
unstable. Regular locomotion corresponds to stable limit cycles in the
sensorimotor loop, which may be characterized in turn by arbitrary angles of
propagation. This degeneracy is, in our analysis, one of the drivings for the
chaotic wandering observed for selected parameter settings, which is induced by
the smooth diffusion of the angle of propagation.
| arxiv topic:q-bio.NC cs.RO nlin.AO |
arxiv_dataset-75941608.02938 | Are Ultra-Long Gamma-Ray Bursts Caused by Blue Supergiant Collapsars,
Newborn Magnetars, or White Dwarf Tidal Disruption Events?
astro-ph.HE astro-ph.GA astro-ph.SR
Ultra-long gamma-ray bursts (ulGRBs) are a new population of GRBs with
extreme durations of $\sim 10^{4}$ s. Leading candidates for their origin are
blue supergiant collapsars, magnetars, and white dwarf tidal disruption events
(WD-TDEs) caused by massive black holes (BHs). Recent observations of
supernova-like (SN-like) bumps associated with ulGRBs challenged both the
WD-TDE and the blue supergiant models because of the detection of SNe and the
absence of hydrogen lines, respectively. We propose that WD-TDEs can
accommodate the observed SN-like bumps if the fallback WD matter releases
energy into the unbound WD ejecta. The observed ejecta energy, luminosity, and
velocity are explained by the gravitational energy, Eddington luminosity, and
escape velocity of the formed accretion disk, respectively. We also show that
the observed X-rays can ionize the ejecta, eliminating lines. The SN-like light
curves (SN 2011kl) for the ulGRB 111209A are consistent with all three models,
although a magnetar model is unnatural because the spin-down time required to
power the SN-like bump is a hundred times longer than the GRB. Our results
imply that TDEs are a possible energy source for SN-like events in general and
for ulGRBs in particular.
| arxiv topic:astro-ph.HE astro-ph.GA astro-ph.SR |
arxiv_dataset-75951608.03038 | Probing the out-of-equilibrium dynamics of two interacting atoms
quant-ph cond-mat.quant-gas
We study the out-of-equilibrium dynamics of two interacting atoms in a
one-dimensional harmonic trap after a quench by a tightly pinned impurity atom.
We make use of an approximate variational calculation called the Lagrange-mesh
method to solve the Schr\"odinger equation as a function of inter-particle
interaction and impurity quench strength. We investigate the out-of-equilibrium
dynamics by calculating the Loschmidt echo which quantifies the irreversibility
of the system following the quench, while its probability distribution after
long times can be used to identify distinct dynamical regimes. These quantities
are related to the spectral function which describes the full dynamical
spectrum, and we show through a thorough examination of the parameter space the
existence of distinct scattering states and collective oscillations. This work
demonstrates how these dynamics are strongly dependent on the interaction
strength between the atoms and may be tuned to reach the orthogonality
catastrophe in few-body systems.
| arxiv topic:quant-ph cond-mat.quant-gas |
arxiv_dataset-75961608.03138 | Linear evolution equations in scales of Banach spaces
math.FA math.CA
This work is devoted to the study of a class of linear time-inhomogeneous
evolution equations in a scale of Banach spaces. Existence, uniquenss and
stability for classical solutions is provided. We study also the associated
dual Cauchy problem for which we prove uniqueness in the dual scale of Banach
spaces. The results are applied to an infinite system of ordinary differential
equations but also to the Fokker-Planck equation associated with the spatial
logistic model in the continuum.
| arxiv topic:math.FA math.CA |
arxiv_dataset-75971608.03238 | Antiferromagnetic multi-level memory cell
cond-mat.mtrl-sci
Antiferromagnets (AFs) are remarkable magnetically ordered materials that due
to the absence of a net magnetic moment do not generate dipolar fields and are
insensitive to external magnetic field perturbations. However, it has been
notoriously difficult to control antiferromagnetic moments by any practical
means suitable for device applications. This has left AFs over their hundred
years history virtually unexploited and only poorly explored, in striking
contrast to the thousands of years of fascination and utility of
ferromagnetism. Very recently it has been predicted and experimentally
confirmed that relativistic spin-orbit torques can provide the means for
efficient electrical control of an AF. Here we place the emerging field of
antiferromagnetic spintronics on the map of non-volatile solid state memory
technologies. We demonstrate the complete write/store/read functionality in an
antiferromagnetic CuMnAs bit cell embedded in a standard printed circuit board
communicating with a computer via a USB interface. We show that the
elementary-shape bit cells fabricated from a single-layer AF are electrically
written on timescales ranging from milliseconds to nanoseconds and we
demonstrate their deterministic multi-level switching. The multi-level cell
characteristics, reflecting series of reproducible, electrically controlled
domain reconfigurations, allow us to integrate memory and signal counter
functionalities within the bit cell.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-75981608.03338 | Galactoseismology and the Local Density of Dark Matter
astro-ph.GA
We model vertical breathing mode perturbations in the Milky Way's stellar
disc and study their effects on estimates of the local dark matter density,
surface density, and vertical force. Evidence for these perturbations, which
involve compression and expansion of the Galactic disc perpendicular to its
midplane, come from the SEGUE, RAVE, and LAMOST surveys. We show that their
existence may lead to systematic errors of $10\%$ or greater in the vertical
force $K_z(z)$ at $|z|=1.1\,{\rm kpc}$. These errors translate to $\gtrsim
25\%$ errors in estimates of the local dark matter density. Using different
mono-abundant subpopulations as tracers offers a way out: if the inferences
from all tracers in the Gaia era agree, then the dark matter determination will
be robust. Disagreement in the inferences from different tracers will signal
the breakdown of the unperturbed model and perhaps provide the means for
determining the nature of the perturbation.
| arxiv topic:astro-ph.GA |
arxiv_dataset-75991608.03438 | Exact propagation of open quantum systems in a system-reservoir context
cond-mat.stat-mech physics.comp-ph quant-ph
A stochastic representation of the dynamics of open quantum systems, suitable
for non-perturbative system-reservoir interaction, non-Markovian effects and
arbitrarily driven systems is presented. It includes the case of driving on
timescales comparable to or shorter than the reservoir correlation time, a
notoriously difficult but relevant case in the context of quantum information
processing and quantum thermodynamics. A previous stochastic approach is
re-formulated for the case of finite reservoir correlation and response times,
resulting in a numerical simulation strategy exceeding previous ones by orders
of magnitude in efficiency. Although the approach is based on a memory
formalism, the dynamical equations propagated in the simulations are
time-local. This leaves a wide range of choices in selecting the system to be
studied and the numerical method used for propagation. For a series of tests,
the dynamics of the spin-boson system is computed in various settings including
strong external driving and Landau-Zener transitions.
| arxiv topic:cond-mat.stat-mech physics.comp-ph quant-ph |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.