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arxiv_dataset-69001512.07348 | Study on CEPC performances with different collision energies and
geometric layouts
physics.acc-ph
Circular Electron-Positron Collider(CEPC) is one of the largest plans in high
energy physics study at China, which would serve as Higgs Factory firstly and
then upgrade to a hadron collider. In this paper we give the 50km and 100km
design in both single ring and double ring schemes, including $Z$ boson and $W$
boson and Higgs boson by using the optimized method. Also, we give the
potential of CEPC running at $Z$ and $W$ poles. And we analysis the
relationship of luminosity with circumference and filling factor, which gives a
way to evaluate the choice of geometry. What's more, we compare the nominal
performance of CEPC-SPPC and LHC and FCC.
| arxiv topic:physics.acc-ph |
arxiv_dataset-69011512.07448 | Bose-Einstein condensate in an optical lattice with Raman-assisted
two-dimensional spin-orbit coupling
cond-mat.quant-gas
In a recent experiment by Wu {\textit et al.} (arXiv:1511.08170), a
Raman-assisted two-dimensional spin-orbit coupling has been realized for a
Bose-Einstein condensate in an optical lattice potential. In light of this
exciting progress, we study in detail key properties of the system. As the
Raman lasers inevitably couple atoms to high-lying bands, the behaviors of the
system in both the single- and many-particle sectors are significantly
affected. In particular, the high-band effects enhance the plane-wave phase and
lead to the emergence of "roton" gaps at low Zeeman fields. Furthermore, we
identify high-band-induced topological phase boundaries in both the
single-particle and the quasi-particle spectra. We then derive an effective
two-band model, which captures the high-band physics in the experimentally
relevant regime. Our results not only offer valuable insights into the novel
two-dimensional lattice spin-orbit coupling, but also provide a systematic
formalism to model high-band effects in lattice systems with Raman-assisted
spin-orbit couplings.
| arxiv topic:cond-mat.quant-gas |
arxiv_dataset-69021512.07548 | k-Means Clustering Is Matrix Factorization
stat.ML
We show that the objective function of conventional k-means clustering can be
expressed as the Frobenius norm of the difference of a data matrix and a low
rank approximation of that data matrix. In short, we show that k-means
clustering is a matrix factorization problem. These notes are meant as a
reference and intended to provide a guided tour towards a result that is often
mentioned but seldom made explicit in the literature.
| arxiv topic:stat.ML |
arxiv_dataset-69031512.07648 | Self-induced transparency mode-locking, and area theorem
physics.optics
Self-induced transparency mode-locking (or coherent mode-locking, CML) which
is based on intracavity self-induced transparency soliton dynamics, allows
potentially to achieve nearly single cycle intracavity pulse durations, much
below the phase relaxation time $T_2$ in a laser, which, despite of great
promise, has not yet been realized experimentally. We develop a diagram
technique which allows to predict the main features of CML regimes in a generic
two-section laser. We show that CML can arise directly at the first laser
threshold if the phase relaxation time is large enough. Furthermore, CML
regimes can be unconditionally stable. We also predict the existence of
``super-CML regimes``, with a pulse coupled to several Rabi oscillations in the
nonlinear medium.
| arxiv topic:physics.optics |
arxiv_dataset-69041512.07748 | Real-Time Audio-to-Score Alignment of Music Performances Containing
Errors and Arbitrary Repeats and Skips
cs.SD cs.LG cs.MM
This paper discusses real-time alignment of audio signals of music
performance to the corresponding score (a.k.a. score following) which can
handle tempo changes, errors and arbitrary repeats and/or skips (repeats/skips)
in performances. This type of score following is particularly useful in
automatic accompaniment for practices and rehearsals, where errors and
repeats/skips are often made. Simple extensions of the algorithms previously
proposed in the literature are not applicable in these situations for scores of
practical length due to the problem of large computational complexity. To cope
with this problem, we present two hidden Markov models of monophonic
performance with errors and arbitrary repeats/skips, and derive efficient
score-following algorithms with an assumption that the prior probability
distributions of score positions before and after repeats/skips are independent
from each other. We confirmed real-time operation of the algorithms with music
scores of practical length (around 10000 notes) on a modern laptop and their
tracking ability to the input performance within 0.7 s on average after
repeats/skips in clarinet performance data. Further improvements and extension
for polyphonic signals are also discussed.
| arxiv topic:cs.SD cs.LG cs.MM |
arxiv_dataset-69051512.07848 | Model-free inference on extreme dependence via waiting times
math.ST math.PR stat.ME stat.TH
A variety of methods have been proposed for inference about extreme
dependence for multivariate or spatially-indexed stochastic processes and time
series. Most of these proceed by first transforming data to some specific
extreme value marginal distribution, often the unit Fr\'echet, then fitting a
family of max-stable processes to the transformed data and exploring dependence
within the framework of that model. The marginal transformation, model
selection, and model fitting are all possible sources of misspecification in
this approach.
We propose an alternative model-free approach, based on the idea that
substantial information on the strength of tail dependence and its temporal
structure are encoded in the distribution of the waiting times between
exceedances of high thresholds at different locations. We propose quantifying
the strength of extremal dependence and assessing uncertainty by using
statistics based on these waiting times. The method does not rely on any
specific underlying model for the process, nor on asymptotic distribution
theory. The method is illustrated by applications to climatological, financial,
and electrophysiology data.
To put the proposed approach within the context of the existing literature,
we construct a class of spacetime-indexed stochastic processes whose waiting
time distributions are available in closed form by endowing the support points
in de Haan's spectral representation of max-stable processes with random birth
times, velocities, and lifetimes, and applying Smith's model to these
processes. We show that waiting times in this model are stochatically
decreasing in mean speed, and the sample mean of the waiting times obeys a
central limit theorem with a uniform convergence rate under mild conditions.
This indicates that our procedure can be implemented in this setting using
standard $t$ statistics and associated hypothesis tests.
| arxiv topic:math.ST math.PR stat.ME stat.TH |
arxiv_dataset-69061512.07948 | A Relaxed Drift Diffusion Model for Phylogenetic Trait Evolution
q-bio.PE stat.ME
Understanding the processes that give rise to quantitative measurements
associated with molecular sequence data remains an important issue in
statistical phylogenetics. Examples of such measurements include geographic
coordinates in the context of phylogeography and phenotypic traits in the
context of comparative studies. A popular approach is to model the evolution of
continuously varying traits as a Brownian diffusion process. However, standard
Brownian diffusion is quite restrictive and may not accurately characterize
certain trait evolutionary processes. Here, we relax one of the major
restrictions of standard Brownian diffusion by incorporating a nontrivial
estimable drift into the process. We introduce a relaxed drift diffusion model
for the evolution of multivariate continuously varying traits along a
phylogenetic tree via Brownian diffusion with drift. Notably, the relaxed drift
model accommodates branch-specific variation of drift rates while preserving
model identifiability. We implement the relaxed drift model in a Bayesian
inference framework to simultaneously reconstruct the evolutionary histories of
molecular sequence data and associated multivariate continuous trait data, and
provide tools to visualize evolutionary reconstructions. We illustrate our
approach in three viral examples. In the first two, we examine the
spatiotemporal spread of HIV-1 in central Africa and West Nile virus in North
America and show that a relaxed drift approach uncovers a clearer, more
detailed picture of the dynamics of viral dispersal than standard Brownian
diffusion. Finally, we study antigenic evolution in the context of HIV-1
resistance to three broadly neutralizing antibodies. Our analysis reveals
evidence of a continuous drift at the HIV-1 population level towards enhanced
resistance to neutralization by the VRC01 monoclonal antibody over the course
of the epidemic.
| arxiv topic:q-bio.PE stat.ME |
arxiv_dataset-69071512.08048 | Using Data Analytics to Detect Anomalous States in Vehicles
cs.AI cs.CR
Vehicles are becoming more and more connected, this opens up a larger attack
surface which not only affects the passengers inside vehicles, but also people
around them. These vulnerabilities exist because modern systems are built on
the comparatively less secure and old CAN bus framework which lacks even basic
authentication. Since a new protocol can only help future vehicles and not
older vehicles, our approach tries to solve the issue as a data analytics
problem and use machine learning techniques to secure cars. We develop a Hidden
Markov Model to detect anomalous states from real data collected from vehicles.
Using this model, while a vehicle is in operation, we are able to detect and
issue alerts. Our model could be integrated as a plug-n-play device in all new
and old cars.
| arxiv topic:cs.AI cs.CR |
arxiv_dataset-69081512.08148 | Decremental Single-Source Shortest Paths on Undirected Graphs in
Near-Linear Total Update Time
cs.DS
In the decremental single-source shortest paths (SSSP) problem we want to
maintain the distances between a given source node $s$ and every other node in
an $n$-node $m$-edge graph $G$ undergoing edge deletions. While its static
counterpart can be solved in near-linear time, this decremental problem is much
more challenging even in the undirected unweighted case. In this case, the
classic $O(mn)$ total update time of Even and Shiloach [JACM 1981] has been the
fastest known algorithm for three decades. At the cost of a
$(1+\epsilon)$-approximation factor, the running time was recently improved to
$n^{2+o(1)}$ by Bernstein and Roditty [SODA 2011]. In this paper, we bring the
running time down to near-linear: We give a $(1+\epsilon)$-approximation
algorithm with $m^{1+o(1)}$ expected total update time, thus obtaining
near-linear time. Moreover, we obtain $m^{1+o(1)} \log W$ time for the weighted
case, where the edge weights are integers from $1$ to $W$. The only prior work
on weighted graphs in $o(m n)$ time is the $m n^{0.9 + o(1)}$-time algorithm by
Henzinger et al. [STOC 2014, ICALP 2015] which works for directed graphs with
quasi-polynomial edge weights. The expected running time bound of our algorithm
holds against an oblivious adversary.
In contrast to the previous results which rely on maintaining a sparse
emulator, our algorithm relies on maintaining a so-called sparse $(h,
\epsilon)$-hop set introduced by Cohen [JACM 2000] in the PRAM literature. An
$(h, \epsilon)$-hop set of a graph $G=(V, E)$ is a set $F$ of weighted edges
such that the distance between any pair of nodes in $G$ can be
$(1+\epsilon)$-approximated by their $h$-hop distance (given by a path
containing at most $h$ edges) on $G'=(V, E\cup F)$. Our algorithm can maintain
an $(n^{o(1)}, \epsilon)$-hop set of near-linear size in near-linear time under
edge deletions.
| arxiv topic:cs.DS |
arxiv_dataset-69091512.08248 | On the tomographic description of quantum systems: theory and
applications
quant-ph
In this job, we will present a theory called Quantum Tomography that is the
natural extension of the theory of detection of signals in classical
telecommunications to Quantum Mechanics. This theory mainly consists in the
reconstruction of a quantum state of a system through a probability
distribution measured directly in the laboratory, usually called Tomogram.
This Thesis contains five chapters. In the first one, we will show the birth
of this theory as an adaptation of homodyne and heterodyne classical detection
to Quantum Mechanics. In the second, we will describe a tomographic description
of Quantum Mechanics on C*-algebras by splitting the theory in two parts: a
Generalized Sampling Theory and a Generalized Positive Transform. In the third,
we will present the first numerical algorithm that solves the Clebsh-Gordan
decomposition problem for any finite-dimensional unitary representation of any
finite or compact Lie group. This algorithm receives the name of SMILY
algorithm. In the fourth and fifth chapters, we will discuss tomography of
systems parametrized with fields. In the fourth, we will reconstruct states of
classical systems and in the fifth, we will do the same with quantum ones, but
here in two different ways: the first one will be done by adapting the
reconstruction formula of chapter four, and the second one by means of the
axiomatic description of Wightamn-Streater of a Quantum Field Theory.
| arxiv topic:quant-ph |
arxiv_dataset-69101512.08348 | Hook formulas for skew shapes I. $q$-analogues and bijections
math.CO math.AG
The celebrated hook-length formula gives a product formula for the number of
standard Young tableaux of a straight shape. In 2014, Naruse announced a more
general formula for the number of standard Young tableaux of skew shapes as a
positive sum over excited diagrams of products of hook-lengths. We give an
algebraic and a combinatorial proof of Naruse's formula, by using factorial
Schur functions and a generalization of the Hillman--Grassl correspondence,
respectively.
The main new results are two different $q$-analogues of Naruse's formula: for
the skew Schur functions, and for counting reverse plane partitions of skew
shapes. We establish explicit bijections between these objects and families of
integer arrays with certain nonzero entries, which also proves the second
formula.
| arxiv topic:math.CO math.AG |
arxiv_dataset-69111512.08448 | On degree sequences of undirected, directed, and bidirected graphs
math.CO
Bidirected graphs generalize directed and undirected graphs in that edges are
oriented locally at every node. The natural notion of the degree of a node that
takes into account (local) orientations is that of net-degree. In this paper,
we extend the following four topics from (un)directed graphs to bidirected
graphs:
- Erd\H{o}s-Gallai-type results: characterization of net-degree sequences,
- Havel-Hakimi-type results: complete sets of degree-preserving operations,
- Extremal degree sequences: characterization of uniquely realizable
sequences, and
- Enumerative aspects: counting formulas for net-degree sequences.
To underline the similarities and differences to their (un)directed
counterparts, we briefly survey the undirected setting and we give a thorough
account for digraphs with an emphasis on the discrete geometry of degree
sequences. In particular, we determine the tight and uniquely realizable degree
sequences for directed graphs.
| arxiv topic:math.CO |
arxiv_dataset-69121512.08548 | A Class of logarithmically completely monotonic functions relating the
$q$-gamma function and applications
math.CA
In this paper, the logarithmically complete monotonicity property for a
functions involving $q$-gamma function is investigated for $q\in(0,1).$ As
applications of this results, some new inequalities for the $q$-gamma function
are established. Furthermore, let the sequence $r_n$ be defined by
$$n!=\sqrt{2\pi n}(n/e)^n e^{r_n}.$$ We establish new estimates for Stirling's
formula remainder $r_n.$
| arxiv topic:math.CA |
arxiv_dataset-69131512.08648 | A framework for robust object multi-detection with a vote aggregation
and a cascade filtering
cs.CV
This paper presents a framework designed for the multi-object detection
purposes and adjusted for the application of product search on the market
shelves. The framework uses a single feedback loop and a pattern resizing
mechanism to demonstrate the top effectiveness of the state-of-the-art local
features. A high detection rate with a low false detection chance can be
achieved with use of only one pattern per object and no manual parameters
adjustments. The method incorporates well known local features and a basic
matching process to create a reliable voting space. Further steps comprise of
metric transformations, graphical vote space representation, two-phase vote
aggregation process and a cascade of verifying filters.
| arxiv topic:cs.CV |
arxiv_dataset-69141512.08748 | Carbon nanoparticles in the acoustic field in the vicinity of the arc
discharge
physics.plasm-ph cond-mat.soft
The paper considers an effect of intensive ultrasound on the suspension of
soot microparticles and nanoparticles in the inert gas, resulting in the
coagulation of relatively large soot particles and leading to the improvement
of the efficiency of production of nanoparticles, as has been observed in
experiments. The effect of the particles charge on the possibility of
coagulation is analyzed.
| arxiv topic:physics.plasm-ph cond-mat.soft |
arxiv_dataset-69151512.08848 | Trade-off Relations of Bell Violations among Pairwise Qubit Systems
quant-ph
We investigate the nonlocality distributions among multiqubit systems based
on the maximal violations of the Clauser-Horne-Shimony-Holt (CHSH) inequality
of reduced pairwise qubit systems. We present a trade-off relation satisfied by
these maximal violations, which gives rise to restrictions on the distribution
of nonlocality among the subqubit systems. For a three-qubit system, it is
impossible that all pairs of qubits violate the CHSH inequality, and once a
pair of qubits violates the CHSH inequality maximally, the other two pairs of
qubits must both obey the CHSH inequality. Detailed examples are given to
illustrate the trade-off relations, and the trade-off relations are generalized
to arbitrary multiqubit systems.
| arxiv topic:quant-ph |
arxiv_dataset-69161512.08948 | Harmonic analysis operators related to symmetrized Jacobi expansions for
all admissible parameters
math.CA
This is an ultimate completion of our earlier paper [Acta.\ Math.\ Hungar.\
140 (2013), 248--292] where mapping properties of several fundamental harmonic
analysis operators in the setting of symmetrized Jacobi trigonometric
expansions were investigated under certain restrictions on the underlying
parameters of type. In the present article we take advantage of very recent
results due to Nowak, Sj\"ogren and Szarek to fully release those restrictions,
and also to provide shorter and more transparent proofs of the previous
restricted results. Moreover, we also study mapping properties of analogous
operators in the parallel context of symmetrized Jacobi function expansions.
Furthermore, as a consequence of our main results we conclude some new results
related to the classical non-symmetrized Jacobi polynomial and function
expansions.
| arxiv topic:math.CA |
arxiv_dataset-69171512.09048 | LHC 750 GeV Diphoton excess in a radiative seesaw model
hep-ph
We investigate a possibility for explaining the recently announced 750\,GeV
diphoton excess by the ATLAS and the CMS experiments at the CERN LHC in a model
with multiple doubly charged particles, which was originally suggested for
explaining tiny neutrino masses through a three-loop effect in a natural way.
The enhanced radiatively generated effective coupling of a new singlet scalar
$S$ with diphoton with multiple charged particles in the loop enlarges the
production rate of $S$ in $pp\to S+X$ via photon fusion process and also the
decay width $\Gamma(S\to \gamma\gamma)$ even without assuming a tree level
production mechanism. We provide detailed analysis on the cases with or without
allowing the mixing between $S$ and the standard model Higgs doublet.
| arxiv topic:hep-ph |
arxiv_dataset-69181512.09148 | MSSM from F-theory SU(5) with Klein Monodromy
hep-ph
We revisit a class of $SU(5)$ SUSY GUT models which arise in the context of
the spectral cover with Klein Group monodromy $V_4=Z_2\times Z_2$. We show that
$Z_2$ matter parities can be realised via new geometric symmetries respected by
the spectral cover. We discuss a particular example of this kind, where the low
energy effective theory below the GUT scale is just the MSSM with no exotics
and standard matter parity, extended by the seesaw mechanism with two
right-handed neutrinos.
| arxiv topic:hep-ph |
arxiv_dataset-69191512.09248 | Maximum entropy analysis of cosmic ray composition
astro-ph.HE
We focus on the primary composition of cosmic rays with the highest energies
that cause extensive air showers in the Earth's atmosphere. A way of examining
the two lowest order moments of the sample distribution of the depth of shower
maximum is presented. The aim is to show that useful information about the
composition of the primary beam can be inferred with limited knowledge we have
about processes underlying these observations. In order to describe how the
moments of the depth of shower maximum depend on the type of primary particles
and their energies, we utilize a superposition model. Using the principle of
maximum entropy, we are able to determine what trends in the primary
composition are consistent with the input data, while relying on a limited
amount of information from shower physics. Some capabilities and limitations of
the proposed method are discussed. In order to achieve a realistic description
of the primary mass composition, we pay special attention to the choice of the
parameters of the superposition model. We present two examples that demonstrate
what consequences can be drawn for energy dependent changes in the primary
composition.
| arxiv topic:astro-ph.HE |
arxiv_dataset-69201512.09348 | The baryon acoustic oscillation peak: a flexible standard ruler
astro-ph.CO gr-qc
For about a decade, the baryon acoustic oscillation (BAO) peak at about 105
Mpc/h has provided a standard ruler test of the LCDM cosmological model, a
member of the Friedmann--Lemaitre--Robertson--Walker (FLRW) family of
cosmological models---according to which comoving space is rigid. However,
general relativity does not require comoving space to be rigid. During the
virialisation epoch, when the most massive structures form by gravitational
collapse, it should be expected that comoving space evolves inhomogeneous
curvature as structure grows. The BAO peak standard ruler should also follow
this inhomogeneous evolution if the comoving rigidity assumption is false. This
"standard" ruler has now been detected to be flexible, as expected under
general relativity.
| arxiv topic:astro-ph.CO gr-qc |
arxiv_dataset-69211601.00072 | GPU-Based Fuzzy C-Means Clustering Algorithm for Image Segmentation
cs.DC cs.CV
In this paper, a fast and practical GPU-based implementation of Fuzzy
C-Means(FCM) clustering algorithm for image segmentation is proposed. First, an
extensive analysis is conducted to study the dependency among the image pixels
in the algorithm for parallelization. The proposed GPU-based FCM has been
tested on digital brain simulated dataset to segment white matter(WM), gray
matter(GM) and cerebrospinal fluid (CSF) soft tissue regions. The execution
time of the sequential FCM is 519 seconds for an image dataset with the size of
1MB. While the proposed GPU-based FCM requires only 2.33 seconds for the
similar size of image dataset. An estimated 245-fold speedup is measured for
the data size of 40 KB on a CUDA device that has 448 processors.
| arxiv topic:cs.DC cs.CV |
arxiv_dataset-69221601.00172 | On Quantitatively Measuring Controllability of Complex Networks
cs.SY cs.SI physics.soc-ph
This letter deals with the controllability issue of complex networks. An
index is chosen to quantitatively measure the extent of controllability of
given network. The effect of this index is analyzed based on empirical studies
on various classes of network topologies, such as random network, small-world
network, and scale-free network.
| arxiv topic:cs.SY cs.SI physics.soc-ph |
arxiv_dataset-69231601.00272 | Treelike quintet systems
math.CO
Let $X$ be a finite set. We give criterion to say if a system of trees ${\cal
P}=\{T_i\}_i$ with leaf sets $L(T_i) \in {X \choose 5}$ can be amalgamated into
a supertree, that is, if there exists a tree $T$ with $L(T)=X$ such that $T$
restricted to $ L(T_i)$ is equal to $T_i$.
| arxiv topic:math.CO |
arxiv_dataset-69241601.00372 | Mutual Information and Diverse Decoding Improve Neural Machine
Translation
cs.CL cs.AI
Sequence-to-sequence neural translation models learn semantic and syntactic
relations between sentence pairs by optimizing the likelihood of the target
given the source, i.e., $p(y|x)$, an objective that ignores other potentially
useful sources of information. We introduce an alternative objective function
for neural MT that maximizes the mutual information between the source and
target sentences, modeling the bi-directional dependency of sources and
targets. We implement the model with a simple re-ranking method, and also
introduce a decoding algorithm that increases diversity in the N-best list
produced by the first pass. Applied to the WMT German/English and
French/English tasks, the proposed models offers a consistent performance boost
on both standard LSTM and attention-based neural MT architectures.
| arxiv topic:cs.CL cs.AI |
arxiv_dataset-69251601.00472 | Intrinsic time in Friedmann-Robertson-Walker universe
gr-qc
A global intrinsic time in Friedmann - Robertson - Walker models is
proportional to a scaling factor of the spatial metric. The aim of the paper is
to study an applicability of the intrinsic global time chosen to nearest
non-symmetric cases by taking into account linear metric perturbations. Scalar
linear perturbations add some corrections to the effective energy density in
the Hubble law. The metric vector and tensor perturbations in linear
approximation do not influence the intrinsic time.
| arxiv topic:gr-qc |
arxiv_dataset-69261601.00572 | Signed tilings by ribbon L n-ominoes, n even, via Groebner bases
math.CO math.AC
Let $\mathcal{T}_n$ be the set of ribbon $L$-shaped $n$-ominoes for some
$n\ge 4$ even, and let $\mathcal{T}_n^+$ be $\mathcal{T}_n$ with an extra
$2\times 2$ square. We investigate signed tilings of rectangles by
$\mathcal{T}_n$ and $\mathcal{T}_n^+$. We show that a rectangle has a signed
tiling by $\mathcal{T}_n$ if and only if both sides of the rectangle are even
and one of them is divisible by $n$, or if one of the sides is odd and the
other side is divisible by $n\left (\frac{n}{2}-2\right ).$ We also show that a
rectangle has a signed tiling by $\mathcal{T}_n^+, n\ge 6$ even, if and only if
both sides of the rectangle are even, or if one of the sides is odd and the
other side is divisible by $n\left (\frac{n}{2}-2\right ).$ Our proofs are
based on the exhibition of explicit Gr\"obner bases for the ideals generated by
polynomials associated to the tiling sets. In particular, we show that some of
the regular tiling results in \emph{ V.~Nitica, Every tiling of the first
quadrant by ribbon $L$ $n$-ominoes follows the rectangular pattern. Open
Journal of Discrete Mathematics, {\em 5}, (2015) 11--25,} cannot be obtained
from coloring invariants.
| arxiv topic:math.CO math.AC |
arxiv_dataset-69271601.00672 | Subgap resonant quasiparticle transport in normal-superconductor quantum
dot devices
cond-mat.mes-hall cond-mat.supr-con
We report thermally activated transport resonances for biases below the
superconducting energy gap in a carbon nanotube (CNT) quantum dot (QD) device
with a superconducting Pb and a normal metal contact. These resonances are due
to the superconductor's finite quasi-particle population at elevated
temperatures and can only be observed when the QD life-time broadening is
considerably smaller than the gap. This condition is fulfilled in our QD
devices with optimized Pd/Pb/In multi-layer contacts, which result in
reproducibly large and "clean" superconducting transport gaps with a strong
conductance suppression for subgap biases. We show that these gaps close
monotonically with increasing magnetic field and temperature. The accurate
description of the subgap resonances by a simple resonant tunneling model
illustrates the ideal characteristics of the reported Pb contacts and gives an
alternative access to the tunnel coupling strengths in a QD.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-69281601.00772 | Linear minimum mean square filters for Markov jump linear systems
math.OC
New linear minimum mean square estimators are introduced in this paper by
considering a cluster information structure in the filter design. The set of
filters constructed in this way can be ordered in a lattice according to the
refines of clusters of the Markov chain, including the linear Markovian
estimator at one end (with only one cluster) and the Kalman filter at the other
hand (with as many clusters as Markov states). The higher is the number of
clusters, the heavier are pre-compuations and smaller is the estimation error,
so that the cluster cardinality allows for a trade-off between performance and
computational burden. In this paper we propose the estimator, give the formulas
for pre-computation of gains, present some properties, and give an illustrative
numerical example.
| arxiv topic:math.OC |
arxiv_dataset-69291601.00872 | Partition zeta functions
math.NT math.CO
We exploit transformations relating generalized $q$-series, infinite
products, sums over integer partitions, and continued fractions, to find
partition-theoretic formulas to compute the values of constants such as $\pi$,
and to connect sums over partitions to the Riemann zeta function, multiple zeta
values, and other number-theoretic objects.
| arxiv topic:math.NT math.CO |
arxiv_dataset-69301601.00972 | Updated determination of the solar neutrino fluxes from solar neutrino
data
hep-ph astro-ph.SR hep-ex
We present an update of the determination of the solar neutrino fluxes from a
global analysis of the solar and terrestrial neutrino data in the framework of
three-neutrino mixing. Using a Bayesian analysis we reconstruct the posterior
probability distribution function for the eight normalization parameters of the
solar neutrino fluxes plus the relevant masses and mixing, with and without
imposing the luminosity constraint. We then use these results to compare the
description provided by different Standard Solar Models. Our results show that,
at present, both models with low and high metallicity can describe the data
with equivalent statistical agreement. We also argue that even with the present
experimental precision the solar neutrino data have the potential to improve
the accuracy of the solar model predictions.
| arxiv topic:hep-ph astro-ph.SR hep-ex |
arxiv_dataset-69311601.01072 | Constraining the propagation speed of gravitational waves with compact
binaries at cosmological distances
gr-qc
In testing gravity a model-independent way, one of crucial tests is measuring
the propagation speed of a gravitational wave (GW). In general relativity, a GW
propagates with the speed of light, while in the alternative theories of
gravity the propagation speed could deviate from the speed of light due to the
modification of gravity or spacetime structure at a quantum level. Previously
we proposed the method measuring the GW speed by directly comparing the arrival
times between a GW and a photon from the binary merger of neutron stars or
neutron star and black hole, assuming that it is associated with a short
gamma-ray burst. The sensitivity is limited by the intrinsic time delay between
a GW and a photon at the source. In this paper, we extend the method to
distinguish the intrinsic time delay from the true signal caused by anomalous
GW speed with multiple events at cosmological distances, also considering the
redshift distribution of GW sources, redshift-dependent GW propagation speed,
and the statistics of intrinsic time delays. We show that an advanced GW
detector such as Einstein Telescope will constrain the GW propagation speed at
the precision of ~10^{-16}. We also discuss the optimal statistic to measure
the GW speed, performing numerical simulations.
| arxiv topic:gr-qc |
arxiv_dataset-69321601.01172 | Vacuum excitation by sudden appearance and disappearance of a Dirichlet
wall in a cavity
hep-th gr-qc quant-ph
Vacuum excitation by time-varying boundary conditions is not only of
fundamental importance but also has recently been confirmed in a laboratory
experiment. In this paper, we study the vacuum excitation of a scalar field by
the instantaneous appearance and disappearance of a both-sided Dirichlet wall
in the middle of a 1D cavity, as toy models of bifurcating and merging
spacetimes, respectively. It is shown that the energy flux emitted positively
diverges on the null lines emanating from the appearance and disappearance
events, which is analogous to the result of Anderson and DeWitt. This result
suggests that the semiclassical effect prevents the spacetime both from
bifurcating and merging. In addition, we argue that the diverging flux in the
disappearance case plays an interesting role to compensate for the lowness of
ambient energy density after the disappearance, which is lower than the
zero-point level.
| arxiv topic:hep-th gr-qc quant-ph |
arxiv_dataset-69331601.01272 | Recurrent Memory Networks for Language Modeling
cs.CL
Recurrent Neural Networks (RNN) have obtained excellent result in many
natural language processing (NLP) tasks. However, understanding and
interpreting the source of this success remains a challenge. In this paper, we
propose Recurrent Memory Network (RMN), a novel RNN architecture, that not only
amplifies the power of RNN but also facilitates our understanding of its
internal functioning and allows us to discover underlying patterns in data. We
demonstrate the power of RMN on language modeling and sentence completion
tasks. On language modeling, RMN outperforms Long Short-Term Memory (LSTM)
network on three large German, Italian, and English dataset. Additionally we
perform in-depth analysis of various linguistic dimensions that RMN captures.
On Sentence Completion Challenge, for which it is essential to capture sentence
coherence, our RMN obtains 69.2% accuracy, surpassing the previous
state-of-the-art by a large margin.
| arxiv topic:cs.CL |
arxiv_dataset-69341601.01372 | Constant-factor approximations for asymmetric TSP on nearly-embeddable
graphs
cs.DS cs.CG
In the Asymmetric Traveling Salesperson Problem (ATSP) the goal is to find a
closed walk of minimum cost in a directed graph visiting every vertex. We
consider the approximability of ATSP on topologically restricted graphs. It has
been shown by [Oveis Gharan and Saberi 2011] that there exists polynomial-time
constant-factor approximations on planar graphs and more generally graphs of
constant orientable genus. This result was extended to non-orientable genus by
[Erickson and Sidiropoulos 2014].
We show that for any class of \emph{nearly-embeddable} graphs, ATSP admits a
polynomial-time constant-factor approximation. More precisely, we show that for
any fixed $k\geq 0$, there exist $\alpha, \beta>0$, such that ATSP on
$n$-vertex $k$-nearly-embeddable graphs admits a $\alpha$-approximation in time
$O(n^\beta)$. The class of $k$-nearly-embeddable graphs contains graphs with at
most $k$ apices, $k$ vortices of width at most $k$, and an underlying surface
of either orientable or non-orientable genus at most $k$. Prior to our work,
even the case of graphs with a single apex was open. Our algorithm combines
tools from rounding the Held-Karp LP via thin trees with dynamic programming.
We complement our upper bounds by showing that solving ATSP exactly on graphs
of pathwidth $k$ (and hence on $k$-nearly embeddable graphs) requires time
$n^{\Omega(k)}$, assuming the Exponential-Time Hypothesis (ETH). This is
surprising in light of the fact that both TSP on undirected graphs and Minimum
Cost Hamiltonian Cycle on directed graphs are FPT parameterized by treewidth.
| arxiv topic:cs.DS cs.CG |
arxiv_dataset-69351601.01472 | Ferroelectric phenomena in CdSnO3: a first-principles study
cond-mat.mtrl-sci
The phonon spectrum of cubic cadmium metastannate and the crystal structures
of its distorted phases were calculated from first principles within the
density functional theory. It is shown that the phonon spectrum and the energy
spectrum of distorted phases in $\alpha$-CdSnO$_3$ are surprisingly similar to
the corresponding spectra of CdTiO$_3$. The ground state of $\alpha$-CdSnO$_3$
is the ferroelectric $Pbn2_1$ phase; the energy gain accompanying the phase
transition from the nonpolar $Pbnm$ phase to this phase is $\sim$30 meV and the
spontaneous polarization in it is 0.25 C/m$^2$. An analysis of the eigenvector
of the ferroelectric mode in $\alpha$-CdSnO$_3$ and calculations of the partial
densities of states indicates that the ferroelectric instability in this
crystal, which does not contain $d$ transition elements, is associated with the
formation of a covalent bonding between Cd and O atoms.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-69361601.01572 | Linking 1D Evolutionary to 3D Hydrodynamical Simulations of Massive
Stars
astro-ph.SR physics.flu-dyn
Stellar evolution models of massive stars are important for many areas of
astrophysics, for example nucleosynthesis yields, supernova progenitor models
and understanding physics under extreme conditions. Turbulence occurs in stars
primarily due to nuclear burning at different mass coordinates within the star.
The understanding and correct treatment of turbulence and turbulent mixing at
convective boundaries in stellar models has been studied for decades but still
lacks a definitive solution. This paper presents initial results of a study on
convective boundary mixing (CBM) in massive stars. The 'stiffness' of a
convective boundary can be quantified using the bulk Richardson number
($\textrm{Ri}_B$), the ratio of the potential energy for restoration of the
boundary to the kinetic energy of turbulent eddies. A 'stiff' boundary
($\textrm{Ri}_B \sim 10^4$) will suppress CBM, whereas in the opposite case a
'soft' boundary ($\textrm{Ri}_B \sim 10$) will be more susceptible to CBM. One
of the key results obtained so far is that lower convective boundaries (closer
to the centre) of nuclear burning shells are 'stiffer' than the corresponding
upper boundaries, implying limited CBM at lower shell boundaries. This is in
agreement with 3D hydrodynamic simulations carried out by Meakin and Arnett
[The Astrophysical Journal 667:448-475, 2007]. This result also has
implications for new CBM prescriptions in massive stars as well as for nuclear
burning flame front propagation in Super-Asymptotic Giant Branch stars and also
the onset of novae.
| arxiv topic:astro-ph.SR physics.flu-dyn |
arxiv_dataset-69371601.01672 | The $DKP$ equation in the Woods-Saxon potential well: Bound states
quant-ph hep-th math-ph math.MP
We solve the Duffin-Kemmer-P\'{e}tiau equation in the presence of a spatially
one-dimensional symmetric potential well. We compute the scattering state
solutions and we derive conditions for transmission resonances. The bound
solutions are derived by a graphic study and the appearance of the antiparticle
bound state is discussed.
| arxiv topic:quant-ph hep-th math-ph math.MP |
arxiv_dataset-69381601.01772 | Singular electrostatic energy of nanoparticle clusters
cond-mat.soft
The binding of clusters of metal nanoparticles is partly electrostatic. We
address difficulties in calculating the electrostatic energy when high charging
energies limit the total charge to a single quantum, entailing unequal
potentials on the particles. We show that the energy at small separation $h$
has a singular logarithmic dependence on $h$. We derive a general form for this
energy in terms of the singular capacitance of two spheres in near contact
$c(h)$, together with nonsingular geometric features of the cluster. Using this
form, we determine the energies of various clusters, finding that more compact
clusters are more stable. These energies are proposed to be significant for
metal-semiconductor binary nanoparticle lattices found experimentally. We
sketch how these effects should dictate the relative abundances of metal
nanoparticle clusters in nonpolar solvents.
| arxiv topic:cond-mat.soft |
arxiv_dataset-69391601.01872 | Some fundamental considerations on the dynamics of class B laser
threshold crossing
physics.optics
With the help of a simple rate equation model, we analyze the intrinsic
dynamics of threshold crossing for Class B lasers. A thorough discussion of the
characteristics and the limitations of this very commonly employed model, which
provides excellent qualitative predictions on the laser behaviour, is offered.
Approximate solutions for the population inversion and for the field intensity,
up to the point where the latter reaches macroscopic levels, are found and
discussed, together with the associated characteristic times. Numerical
verifications test the accuracy of these solutions and confirm their validity.
A discussion of the implications on threshold dynamics is presented, together
with the motivation for focussing on this -- nowadays most common -- class of
lasers.
| arxiv topic:physics.optics |
arxiv_dataset-69401601.01972 | Cox process representation and inference for stochastic
reaction-diffusion processes
cond-mat.stat-mech math.ST physics.data-an q-bio.QM stat.ML stat.TH
Complex behaviour in many systems arises from the stochastic interactions of
spatially distributed particles or agents. Stochastic reaction-diffusion
processes are widely used to model such behaviour in disciplines ranging from
biology to the social sciences, yet they are notoriously difficult to simulate
and calibrate to observational data. Here we use ideas from statistical physics
and machine learning to provide a solution to the inverse problem of learning a
stochastic reaction-diffusion process from data. Our solution relies on a
non-trivial connection between stochastic reaction-diffusion processes and
spatio-temporal Cox processes, a well-studied class of models from
computational statistics. This connection leads to an efficient and flexible
algorithm for parameter inference and model selection. Our approach shows
excellent accuracy on numeric and real data examples from systems biology and
epidemiology. Our work provides both insights into spatio-temporal stochastic
systems, and a practical solution to a long-standing problem in computational
modelling.
| arxiv topic:cond-mat.stat-mech math.ST physics.data-an q-bio.QM stat.ML stat.TH |
arxiv_dataset-69411601.02072 | Geometry, stability and thermal transport of hydrogenated graphene
nanoquilts
cond-mat.mes-hall cond-mat.mtrl-sci
Geometry, stability, and thermal transport of graphene nanoquilts folded by
hydrogenation are studied using molecular dynamics simulations. The
hydrogenated graphene nanoquilts show increased thermodynamic stability and
better transport properties than folded graphene structures without
hydrogenation. For the two-fold graphene nanoquilt, both geometry and thermal
conductivity are very sensitive to the adsorbed hydrogen chains, which is
interpreted by the red-shift of PDOS. For the multi-fold nanoquilts, their
thermal conductivities can be tuned from 100% to 15% of pristine graphene, by
varying the periodic number or length. Our results demonstrated that the
hydrogenated graphene nanoquilts are quite suitable to be thermal management
devices.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-69421601.02172 | Anisotropic softening of magnetic excitations in lightly electron doped
Sr$_2$IrO$_4$
cond-mat.str-el
The magnetic excitations in electron doped (Sr$_{1-x}$La$_x$)$_2$IrO$_4$ with
$x = 0.03$ were measured using resonant inelastic X-ray scattering at the Ir
$L_3$-edge. Although much broadened, well defined dispersive magnetic
excitations were observed. Comparing with the magnetic dispersion from the
parent compound, the evolution of the magnetic excitations upon doping is
highly anisotropic. Along the anti-nodal direction, the dispersion is almost
intact. On the other hand, the magnetic excitations along the nodal direction
show significant softening. These results establish the presence of strong
magnetic correlations in electron doped Sr$_{1-x}$La$_x$)$_2$IrO$_4$ with close
analogies to the hole doped cuprates, further motivating the search for high
temperature superconductivity in this system.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-69431601.02272 | Numerical predictions for planets in the debris discs of HD 202628 and
HD 207129
astro-ph.EP
Resolved debris disc images can exhibit a range of radial and azimuthal
structures, including gaps and rings, which can result from planetary
companions shaping the disc by their gravitational influence. Currently there
are no tools available to determine the architecture of potential companions
from disc observations. Recent work by Rodigas et al. (2014) presents how one
can estimate the maximum mass and minimum semi major axis of a hidden planet
empirically from the width of the disc in scattered light. In this work, we use
the predictions of Rodigas et al. applied to two debris discs HD 202628 and HD
207129. We aim to test if the predicted orbits of the planets can explain the
features of their debris disc, such as eccentricity and sharp inner edge. We
first run dynamical simulations using the predicted planetary parameters of
Rodigas et al., and then numerically search for better parameters. Using a
modified N-body code including radiation forces, we perform simulations over a
broad range of planet parameters and compare synthetics images from our
simulations to the observations. We find that the observational features of HD
202628 can be reproduced with a planet five times smaller than expected,
located 30 AU beyond the predicted value, while the best match for HD 207129 is
for a planet located 5-10 AU beyond the predicted location with a smaller
eccentricity. We conclude that the predictions of Rodigas et al. provide a good
starting point but should be complemented by numerical simulations.
| arxiv topic:astro-ph.EP |
arxiv_dataset-69441601.02372 | nodewatcher: A Substrate for Growing Your own Community Network
cs.SI
Community networks differ from regular networks by their organic growth
patterns -- there is no central planning body that would decide how the network
is built. Instead, the network grows in a bottom-up fashion as more people
express interest in participating in the community and connect with their
neighbours. People who participate in community networks are usually volunteers
with limited free time. Due to these factors, making the management of
community networks simpler and easier for all participants is the key component
in boosting their growth. Specifics of individual networks often force
communities to develop their own sets of tools and best practices which are
hard to share and do not interoperate well with others. We propose a new
general community network management platform nodewatcher that is built around
the core principle of modularity and extensibility, making it suitable for
reuse by different community networks. Devices are configured using
platform-independent configuration which nodewatcher can transform into
deployable firmware images, eliminating any manual device configuration,
reducing errors, and enabling participation of novice maintainers. An embedded
monitoring system enables live overview and validation of the whole community
network. We show how the system successfully operates in an actual community
wireless network, wlan Slovenija.
| arxiv topic:cs.SI |
arxiv_dataset-69451601.02472 | An Application-Level Dependable Technique for Farmer-Worker Parallel
Programs
cs.DC
An application-level technique is described for farmer-worker parallel
applications which allows a worker to be added or removed from the computing
farm at any moment of the run time without affecting the overall outcome of the
computation. The technique is based on uncoupling the farmer from the workers
by means of a separate module which asynchronously feeds these latter with new
"units of work" on an on-demand basis, and on a special feeding strategy based
on bookkeeping the status of each work-unit. An augmentation of the LINDA model
is finally proposed to exploit the bookkeeping algorithm for tuple management.
| arxiv topic:cs.DC |
arxiv_dataset-69461601.02572 | The geometric genus and Seiberg-Witten invariant of Newton nondegenerate
surface singularities
math.AG
Given a normal surface singularity (X,0), its link, M is a closed
differentiable three dimensional manifold which carries much analytic
information. It is an interesting question to ask whether, under suitable
analytic and topological conditions, the geometric genus (or other analytic
invariants) can be recovered from the link. The Casson invariant conjecture
predicts that p_g can be identified using the Casson invariant in the case when
(X,0) is a complete intersection and M has trivial first homology with integral
coefficients. The Seiberg-Witten invariant conjecture predicts that the
geometric genus of a Gorenstein singularity, whose link has trivial first
homology with rational coefficients, can be calculated as a normalized
Seiberg-Witten invariant of the link. The first conjecture is still open, but
counterexamples have been found for the second one. We prove here the
Seiberg-Witten invariant conjecture for hypersurface singularities given by a
function with Newton nondegenerate principal part. We provide a theory of
computation sequences and of the way they bound the geometric genus. Newton
nondegenerate singularities can be resolved explicitly by Oka's algorithm, and
we exploit the combinatorial interplay between the resolution graph and the
Newton diagram to show that in each step of the computation sequence we
construct, the given bound is sharp. Our method recovers the geometric genus of
(X,0) explicitly from the link, assuming that (X,0) is indeed Newton
nondegenerate with a rational homology sphere link. Assuming some additional
information about the Newton diagram, we recover part of the spectrum, as well
as the Poincar\'e series associated with the Newton filtration. Finally, we
show that the normalized Seiberg-Witten invariant associated with the canonical
spin^c structure on the link coincides with our identification of the geometric
genus.
| arxiv topic:math.AG |
arxiv_dataset-69471601.02672 | Extreme residues of Dedekind zeta functions
math.NT
In a family of $S_{d+1}$-fields ($d=2,3,4$), we obtain the true upper and
lower bound of the residues of Dedekind zeta functions except for a density
zero set. For $S_5$-fields, we need to assume the strong Artin conjecture. We
also show that there exists an infinite family of number fields with the upper
and lower bound, resp.
| arxiv topic:math.NT |
arxiv_dataset-69481601.02772 | The magnificent past of RR Lyrae variables
astro-ph.SR
The history of the observations of RR Lyr variables started in the XIXth
century, more than 120 years ago. The very long time baseline of available data
combined with the short period of RR Lyrae variables offer an unique
opportunity to look at their past as a treasure of valuable information. At
this purpose, the amateur/professional association Groupe Europeen
d'Observations Stellaires (GEOS) has built a database aimed to gather all the
published maxima. We could study the period changes due to stellar evolution.
Most of the 123 scrutinized RRab stars does not show any significant period
variation. This reflects the fact that the rapid evolution is confined in short
evolutionary phases. Notwithstanding this, we could put in evidence period
increases in 27 stars and decreases in 21 ones. We also used the GEOS database
to study the Blazhko effect of galactic RRab stars. The closed curves
representing the Blazhko effect are constructed by plotting the magnitudes at
maximum vs. the O-C values. We obtained a variegate family of Blazhko
"potatoes". We could also reconstruct the changes in the pulsational and
Blazhko periods of RR Lyr itself, resulted to be completely decoupled.
Moreover, the amplitude of the Blazhko effect decreased so much to be hardly
detectable by looking at the maxima collected in 2014 only. The effect seems to
start again in the 2015 data.
| arxiv topic:astro-ph.SR |
arxiv_dataset-69491601.02872 | Reconstruction of graded groupoids from graded Steinberg algebras
math.RA math.OA
We show how to reconstruct a graded ample Hausdorff groupoid with
topologically principal neutrally graded component from the ring structure of
its graded Steinberg algebra over any commutative integral domain with 1,
together with the embedding of the canonical abelian subring of functions
supported on the unit space. We deduce that diagonal-preserving ring
isomorphism of Leavitt path algebras implies $C^*$-isomorphism of
$C^*$-algebras for graphs $E$ and $F$ in which every cycle has an exit.
| arxiv topic:math.RA math.OA |
arxiv_dataset-69501601.02972 | Optimal Gabor frame bounds for separable lattices and estimates for
Jacobi theta functions
math.FA
We study sharp frame bounds of Gabor frames with the standard Gaussian window
and prove that the square lattice optimizes both the lower and the upper frame
bound among all rectangular lattices. This proves a conjecture of Floch, Alard
& Berrou (as reformulated by Strohmer & Beaver). The proof is based on refined
log-convexity/concavity estimates for the Jacobi theta functions $\theta_3$ and
$\theta_4$.
| arxiv topic:math.FA |
arxiv_dataset-69511601.03072 | The B/C and sub-Iron/Iron Cosmic ray ratios - further evidence in favor
of the spiral arm diffusion model
astro-ph.HE
The Boron to Carbon (B/C) and sub-Fe/Fe ratios provides an important clue on
Cosmic Ray (CR) propagation within the Galaxy. These ratios estimate the
grammage that the CR traverse as they propagate from their sources to Earth.
Attempts to explain these ratios within the standard CR propagation models
require ad hoc modifications and even with those these models necessitate
inconsistent grammages to explain both ratios. As an alternative, physically
motivated model, we have proposed that CR originate preferably within the
galactic spiral arms. CR propagation from dynamic spiral arms has important
imprints on various secondary to primary ratios, such as the B/C ratio and the
positron fraction. We use our spiral arm diffusion model with the spallation
network extended up to Nickel to calculate the sub-Fe/Fe ratio. We show that
without any additional parameters the spiral arm model consistently explains
both ratios with the same grammage, providing further evidence in favor of this
model.
| arxiv topic:astro-ph.HE |
arxiv_dataset-69521601.03172 | On Caffarelli-Kohn-Nirenberg inequalities for block-radial functions
math.AP math.FA
The paper provides weighted Sobolev inequalities of the
Caffarelli-Kohn-Nirenberg type for functions with multi-radial symmetry.
Similarly to the previously studied radial case, the range of parameters in CKN
inequalities can be extended, sometimes to infinity, providing a pointwise
estimate similar to the classical radial estimate. Furthermore, the
"multi-radial" weights are a stronger singularity than radial weights of the
same homogeneity.
| arxiv topic:math.AP math.FA |
arxiv_dataset-69531601.03272 | On the nonlocal Cahn-Hilliard-Brinkman and Cahn-Hilliard-Hele-Shaw
systems
math.AP
The phase separation of an isothermal incompressible binary fluid in a porous
medium can be described by the so-called Brinkman equation coupled with a
convective Cahn-Hilliard (CH) equation. The former governs the average fluid
velocity $\mathbf{u}$, while the latter rules evolution of $\varphi$, the
difference of the (relative) concentrations of the two phases. The two
equations are known as the Cahn-Hilliard-Brinkman (CHB) system. In particular,
the Brinkman equation is a Stokes-like equation with a forcing term (Korteweg
force) which is proportional to $\mu\nabla\varphi$, where $\mu$ is the chemical
potential. When the viscosity vanishes, then the system becomes the
Cahn-Hilliard-Hele-Shaw (CHHS) system. Both systems have been studied from the
theoretical and the numerical viewpoints. However, theoretical results on the
CHHS system are still rather incomplete. For instance, uniqueness of weak
solutions is unknown even in 2D. Here we replace the usual CH equation with its
physically more relevant nonlocal version. This choice allows us to prove more
about the corresponding nonlocal CHHS system. More precisely, we first study
well-posedness for the CHB system, endowed with no-slip and no-flux boundary
conditions. Then, existence of a weak solution to the CHHS system is obtained
as a limit of solutions to the CHB system. Stronger assumptions on the initial
datum allow us to prove uniqueness for the CHHS system. Further regularity
properties are obtained by assuming additional, though reasonable, assumptions
on the interaction kernel. By exploiting these properties, we provide an
estimate for the difference between the solution to the CHB system and the one
to the CHHS system with respect to viscosity.
| arxiv topic:math.AP |
arxiv_dataset-69541601.03372 | Interpreting the Ionization Sequence in Star-Forming Galaxy
Emission-Line Spectra
astro-ph.GA
High ionization star forming (SF) galaxies are easily identified with strong
emission line techniques such as the BPT diagram, and form an obvious
ionization sequence on such diagrams. We use a locally optimally emitting cloud
model to fit emission line ratios that constrain the excitation mechanism,
spectral energy distribution, abundances and physical conditions along the
star-formation ionization sequence. Our analysis takes advantage of the
identification of a sample of pure star-forming galaxies, to define the
ionization sequence, via mean field independent component analysis. Previous
work has suggested that the major parameter controlling the ionization level in
SF galaxies is the metallicity. Here we show that the observed SF- sequence
could alternatively be interpreted primarily as a sequence in the distribution
of the ionizing flux incident on gas spread throughout a galaxy. Metallicity
variations remain necessary to model the SF-sequence, however, our best models
indicate that galaxies with the highest and lowest observed ionization levels
(outside the range -0.37 < log [O III]/H\b{eta} < -0.09) require the variation
of an additional physical parameter other than metallicity, which we determine
to be the distribution of ionizing flux in the galaxy.
| arxiv topic:astro-ph.GA |
arxiv_dataset-69551601.03472 | A Golod complex with non-suspension moment-angle complex
math.AT math.AC math.CO
It could be expected that the moment-angle complex associated with a Golod
simplicial complex is homotopy equivalent to a suspension space. In this paper,
we provide a counter example to this expectation. We have discovered this
complex through the studies of the Golod property of the Alexander dual of a
join of simplicial complexes, and that of a union of simplicial complexes.
| arxiv topic:math.AT math.AC math.CO |
arxiv_dataset-69561601.03572 | Effectivity in Mochizuki's work on the $abc$-conjecture
math.NT
This note outlines a constructive proof of a proposition in Mochizuki's paper
"Arithmetic elliptic curves in general position," making a direct use of
computable non-critical Belyi maps to effectively reduce the full
$abc$-conjecture to a restricted form. Such a reduction means that an effective
$abc$-theorem is implied by Theorem 1.10 of Mochizuki's final IUT paper
("Inter-universal Teichmuller theory IV: log-volume computations and
set-theoretic foundations").
| arxiv topic:math.NT |
arxiv_dataset-69571601.03672 | Colored and Dissipative Continuous Spontaneous Localization model and
Bounds from Matter-Wave Interferometry
quant-ph
Matter-wave interferometry is a direct test of the quantum superposition
principle for massive systems, and of collapse models. Here we show that the
bounds placed by matter-wave interferometry depend weakly on the details of the
collapse mechanism. Specifically, we compute the bounds on the CSL model and
its variants, provided by the the KDTL interferometry experiment of Arndt's
group [Phys. Chem. Chem. Phys., 2013, 15, 14696-14700], which currently holds
the record of largest mass in interferometry.
We also show that the CSL family of models emerges naturally by considering a
minimal set of assumptions. In particular, we construct the dynamical map for
the colored and dissipative Continuous Spontaneous Localization (cdCSL) model,
which reduces to the CSL model and variants in the appropriate limits. In
addition, we discuss the measure of macroscopicity based on the cdCSL model.
| arxiv topic:quant-ph |
arxiv_dataset-69581601.03772 | The photon PDF in events with rapidity gaps
hep-ph
We consider photon-initiated events with large rapidity gaps in proton-proton
collisions, where one or both protons may break up. We formulate a modified
photon PDF that accounts for the specific experimental rapidity gap veto, and
demonstrate how the soft survival probability for these gaps may be implemented
consistently. Finally, we present some phenomenological results for the
two-photon induced production of lepton and $W$ boson pairs.
| arxiv topic:hep-ph |
arxiv_dataset-69591601.03872 | Container-Based Cloud Virtual Machine Benchmarking
cs.DC
With the availability of a wide range of cloud Virtual Machines (VMs) it is
difficult to determine which VMs can maximise the performance of an
application. Benchmarking is commonly used to this end for capturing the
performance of VMs. Most cloud benchmarking techniques are typically
heavyweight - time consuming processes which have to benchmark the entire VM in
order to obtain accurate benchmark data. Such benchmarks cannot be used in
real-time on the cloud and incur extra costs even before an application is
deployed.
In this paper, we present lightweight cloud benchmarking techniques that
execute quickly and can be used in near real-time on the cloud. The exploration
of lightweight benchmarking techniques are facilitated by the development of
DocLite - Docker Container-based Lightweight Benchmarking. DocLite is built on
the Docker container technology which allows a user-defined portion (such as
memory size and the number of CPU cores) of the VM to be benchmarked. DocLite
operates in two modes, in the first mode, containers are used to benchmark a
small portion of the VM to generate performance ranks. In the second mode,
historic benchmark data is used along with the first mode as a hybrid to
generate VM ranks. The generated ranks are evaluated against three scientific
high-performance computing applications. The proposed techniques are up to 91
times faster than a heavyweight technique which benchmarks the entire VM. It is
observed that the first mode can generate ranks with over 90% and 86% accuracy
for sequential and parallel execution of an application. The hybrid mode
improves the correlation slightly but the first mode is sufficient for
benchmarking cloud VMs.
| arxiv topic:cs.DC |
arxiv_dataset-69601601.03972 | Weak decays of heavy hadrons into dynamically generated resonances
hep-ph nucl-th
In this review we give a perspective of the theoretical work done recently on
the interpretation of results from $B$, $D$, $\Lambda_b$, $\Lambda_c$ weak
decays into final states that contain interacting hadrons, and how it is
possible to obtain additional valuable information that is increasing our
understanding of hadron interactions and the nature of many hadronic
resonances. The novelty of these processes is that one begins with a clean
picture at the quark level which allows one to select the basic mechanisms by
means of which the process proceeds. Finally, one has a final state described
in terms of quarks. To make contact with the experiments, where mesons and
baryons are observed, one must hadronize, creating pairs of $q \bar q$ and
writing the new states in terms of mesons and baryons. This concludes the
primary hadron production in these processes. After that, the interaction of
these hadrons takes place, offering a rich spectrum of resonances and special
features from where it is possible to learn much about the interaction of these
hadrons and the nature of many resonances in terms of the components of their
wave functions.
| arxiv topic:hep-ph nucl-th |
arxiv_dataset-69611601.04072 | Comments on Determinant Formulas for General CFTs
hep-th math.RT
We point out that the determinant formula for a parabolic Verma module plays
a key role in the study of (super)conformal field theories and in particular
their (super)conformal blocks. The determinant formula is known from the old
work of Jantzen for bosonic conformal algebras, and we present a conjecture for
superconformal algebras. The application of the formula includes derivation of
the unitary bound and recursion relations for conformal blocks.
| arxiv topic:hep-th math.RT |
arxiv_dataset-69621601.04172 | A Massive Molecular Gas Reservoir in the z=2.221 Type-2 Quasar Host
Galaxy SMM J0939+8315 Lensed by the Radio Galaxy 3C220.3
astro-ph.GA
We report the detection of CO(J=3-2) line emission in the strongly-lensed
submillimeter galaxy (SMG) SMM J0939+8315 at z=2.221, using the Combined Array
for Research in Millimeter-wave Astronomy. SMM J0939+8315 hosts a type-2
quasar, and is gravitationally lensed by the radio galaxy 3C220.3 and its
companion galaxy at z=0.685. The 104 GHz continuum emission underlying the CO
line is detected toward 3C220.3 with an integrated flux density of S_cont = 7.4
+/- 1.4 mJy. Using the CO(J=3-2) line intensity of I_(CO(3-2)) = (12.6 +/- 2.0)
Jy km s^-1, we derive a lensing- and excitation-corrected CO line luminosity of
L'(CO(3-2)) = (3.4 +/- 0.7) x 10^10 (10.1/mu_L) K km s^-1 pc^2 for the SMG,
where mu_L is the lensing magnification factor inferred from our lens modeling.
This translates to a molecular gas mass of M_gas = (2.7 +/- 0.6) x 10^10
(10.1/mu_L) Msun. Fitting spectral energy distribution models to the
(sub)-millimeter data of this SMG yields a dust temperature of T =
63.1^{+1.1}_{-1.3} K, a dust mass of M_dust = (5.2 +/- 2.1) x 10^8 (10.1/mu_L)
Msun, and a total infrared luminosity of L_IR = (9.1 +/- 1.2) x 10^12
(10.1/mu_L) Lsun. We find that the properties of the interstellar medium of SMM
J0939+8315 overlap with both SMGs and type-2 quasars. Hence, SMM J0939+8315 may
be transitioning from a star-bursting phase to an unobscured quasar phase as
described by the "evolutionary link" model, according to which this system may
represent an intermediate stage in the evolution of present-day galaxies at an
earlier epoch.
| arxiv topic:astro-ph.GA |
arxiv_dataset-69631601.04272 | An efficient approach for solving stiff nonlinear boundary value
problems
math.NA
A new method for solving stiff boundary value problems is described and
compared to other known approaches using the Troesch's problem as a test
example. The method is based on the general idea of alternate approximation of
either the unknown function or its inverse and has a genuine "immunity" towards
numerical difficulties invoked by the rapid variation (stiffness) of the
unknown solution. A c++ implementation of the proposed method is available at
https://github.com/imathsoft/MathSoftDevelopment .
| arxiv topic:math.NA |
arxiv_dataset-69641601.04372 | Coherence loss in stroboscopic radar ranging in the problem of asteroid
size estimation
astro-ph.IM astro-ph.EP
We consider the problem of coherence loss in a stroboscopic high resolution
radar ranging due to phase instability of the probing and reference radio
signals. Requirements to the coherence of reference generators in stroboscopic
signal processing system are formulated. The results of statistical modeling
are presented.
| arxiv topic:astro-ph.IM astro-ph.EP |
arxiv_dataset-69651601.04472 | The evolution of $\sigma^{\gamma P}$ with coherence length
hep-ph
Assuming the form $\sigma^{\gamma P} \propto l^{\lambda_{\rm eff}}$ at fixed
$Q^2$ for the behavior of the virtual-photon proton scattering cross section,
where $l$ is the coherence length of the photon fluctuations, it is seen that
the extrapolated values of $\sigma^{\gamma P}$ for different $Q^2$ cross for
$l\approx 10^8$~fm. It is argued that this behavior is not physical, and that
the behavior of the cross sections must change before this coherence length $l$
is reached. This could set the scale for the onset of saturation of parton
densities.
| arxiv topic:hep-ph |
arxiv_dataset-69661601.04572 | Cosymplectic and $\alpha$-cosymplectic Lie algebras
math.DG
We completely characterize cosymplectic and $\alpha$-cosymplectic Lie
algebras in terms of corresponding symplectic Lie algebras and suitable
derivations on them. Several examples are given and classification results are
obtained in dimension five for cosymplectic, $K$-cosymplectic and coK\"ahler
Lie algebras.
| arxiv topic:math.DG |
arxiv_dataset-69671601.04672 | Physical maze solvers. All twelve prototypes implement 1961 Lee
algorithm
cs.ET
We overview experimental laboratory prototypes of maze solvers. We speculate
that all maze solvers implement Lee algorithm by first developing a gradient of
values showing a distance from any site of the maze to the destination site and
then tracing a path from a given source site to the destination site. All
prototypes approximate a set of many-source-one-destination paths using
resistance, chemical and temporal gradients. They trace a path from a given
source site to the destination site using electrical current, fluidic, growth
of slime mould, Marangoni flow, crawling of epithelial cells, excitation waves
in chemical medium, propagating crystallisation patterns. Some of the
prototypes visualise the path using a stream of dye, thermal camera or glow
discharge; others require a computer to extract the path from time lapse images
of the tracing. We discuss the prototypes in terms of speed, costs and
durability of the path visualisation.
| arxiv topic:cs.ET |
arxiv_dataset-69681601.04772 | Universal scaled Higgs-mass gap for the bilayer Heisenberg model in the
ordered phase
cond-mat.stat-mech
The spectral properties for the bilayer quantum Heisenberg model were
investigated with the numerical diagonalization method. In the ordered phase,
there appears the massive Higgs excitation embedded in the continuum of the
Goldstone excitations. Recently, it was claimed that the properly scaled Higgs
mass is a universal constant in proximity to the critical point. Diagonalizing
the finite-size cluster with $N \le 36$ spins, we calculated the dynamical
scalar susceptibility $\chi_s"(\omega)$, which is rather insensitive to the
Goldstone mode. A finite-size-scaling analysis of $\chi_s "(\omega)$ is made,
and the universal (properly scaled) Higgs mass is estimated.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-69691601.04872 | Adiabatic Green's function technique and the transient behavior in
time-dependent fermion-boson coupled models
cond-mat.mes-hall
The Lang-Firsov Hamiltonian, a well-known solvable model of interacting
fermion-boson system with sideband features in the fermion spectral weight, is
generalized to have the time-dependent fermion-boson coupling constant. We show
how to derive the two-time Green's function for the time-dependent problem in
the adiabatic limit, defined as the slow temporal variation of the coupling
over the characteristic oscillator period. The idea we use in deriving the
Green's function is akin to the use of instantaneous basis states in solving
the adiabatic evolution problem in quantum mechanics. With such "adiabatic
Green's function" at hand we analyze the transient behavior of the spectral
weight as the coupling is gradually tuned to zero. Time-dependent
generalization of a related model, the spin-boson Hamiltonian, is analyzed in
the same way. In both cases the sidebands arising from the fermion-boson
coupling can be seen to gradually lose their spectral weights over time.
Connections of our solution to the two-dimensional Dirac electrons coupled to
quantized photons are discussed.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-69701601.04972 | Highly connected neurons spike less frequently in balanced networks
q-bio.NC
Many biological neuronal networks exhibit highly variable spiking activity.
Balanced networks offer a parsimonious model of this variability. In balanced
networks, strong excitatory synaptic inputs are canceled by strong inhibitory
inputs on average and spiking activity is driven by transient breaks in this
balance. Most previous studies of balanced networks assume a homogeneous or
distance-dependent connectivity structure, but connectivity in biological
cortical networks is more intricate. We use a heterogeneous mean-field theory
of balanced networks to show that heterogeneous in-degrees can break balance,
but balance can be restored by heterogeneous out-degrees that are correlated
with in-degrees. In all examples considered, we find that highly connected
neurons spike less frequently, consistent with recent experimental
observations.
| arxiv topic:q-bio.NC |
arxiv_dataset-69711601.05072 | Cyclic Adams Operations
math.KT math.AC
Let $Q$ be a commutative, Noetherian ring and $Z \subseteq
\operatorname{Spec}(Q)$ a closed subset. Define $K_0^Z(Q)$ to be the
Grothendieck group of those bounded complexes of finitely generated projective
$Q$-modules that have homology supported on $Z$. We develop "cyclic" Adams
operations on $K_0^Z(Q)$ and we prove these operations satisfy the four axioms
used by Gillet and Soul\'e in their paper "Intersection Theory Using Adams
Operations". From this we recover a shorter proof of Serre's Vanishing
Conjecture. We also show our cyclic Adams operations agree with the Adams
operations defined by Gillet and Soul\'e in certain cases.
| arxiv topic:math.KT math.AC |
arxiv_dataset-69721601.05172 | A parametric reconstruction of the cosmological jerk from diverse
observational data sets
gr-qc astro-ph.CO
A parametric reconstruction of the jerk parameter, the third order derivative
of the scale factor expressed in a dimensionless way, has been discussed.
Observational constraints on the model parameters have been obtained by Maximum
Likelihood Analysis of the models using Supernova Distance Modulus data (SNe),
Observational Hubble Data (OHD), Baryon Acoustic Oscillation (BAO) data and CMB
shift parameter data (CMBShift). The present value of the jerk parameter has
been kept open to start with, but the plots of various cosmological parameter
like deceleration parameter $q(z)$, jerk parameter $j(z)$, dark energy equation
of state parameter $w_{DE}(z)$ indicate that the reconstructed models are very
close to a $\Lambda$CDM model with a slight inclination towards a non-phantom
behaviour of the evolution.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-69731601.05272 | Asymptotic behavior of the ground state energy of a Fermionic Fr\"ohlich
multipolaron in the strong coupling limit
math-ph math.MP
In this article, we investigate the asymptotic behavior of the ground state
energy of the Fr\"ohlich Hamiltonian for a Fermionic multipolaron in the
so-called strong coupling limit. We prove that it is given to leading order by
the ground state energy of the Pekar-Tomasevich functional with Fermionic
statistics, which is a much simpler model. Our main theorem is new because none
of the previous results on the strong coupling limit have taken into account
the Fermionic statistics and the spin of the electrons. A binding result for
Fr\"ohlich multipolarons is a corollary of our main theorem combined with the
binding result for multipolarons in the Pekar-Tomasevich model by the first
author and Griesemer in [AG14]. Our analysis strongly relies on the work of
Wellig [Well15] which in turn used and generalized methods developed by Lieb
and Thomas [LT97], Frank, Lieb, Seiringer and Thomas [FLST11] and Griesemer and
Wellig [GW13]. In order to take the Fermionic statistics into account, we
employ a localization method given by Lieb and Loss in [LL05].
| arxiv topic:math-ph math.MP |
arxiv_dataset-69741601.05372 | Coherence for Frobenius pseudomonoids and the geometry of linear proofs
cs.LO
We prove coherence theorems for Frobenius pseudomonoids and snakeorators in
monoidal bicategories. As a consequence we obtain a 3d notation for proofs in
nonsymmetric multiplicative linear logic, with a geometrical notion of
equivalence, and without the need for a global correctness criterion or
thinning links. We argue that traditional proof nets are the 2d projections of
these 3d diagrams.
| arxiv topic:cs.LO |
arxiv_dataset-69751601.05472 | Hierarchical Latent Word Clustering
cs.CL
This paper presents a new Bayesian non-parametric model by extending the
usage of Hierarchical Dirichlet Allocation to extract tree structured word
clusters from text data. The inference algorithm of the model collects words in
a cluster if they share similar distribution over documents. In our
experiments, we observed meaningful hierarchical structures on NIPS corpus and
radiology reports collected from public repositories.
| arxiv topic:cs.CL |
arxiv_dataset-69761601.05572 | Mean Field Dynamics of a Network of Wilson-Cowan Neurons with Electrical
Synapses
math.PR
In this paper we prove the propagation of chaos property for an ensemble of
interacting neurons subject to independent Brownian noise. The propagation of
chaos property means that in the large network size limit, the neurons behave
as if they are probabilistically independent. The model for the internal
dynamics of the neurons is taken to be that of Wilson and Cowan, and we
consider there to be multiple different populations. The synaptic connections
are modelled with a nonlinear `electrical' model. The nonlinearity of the
synaptic connections means that our model lies outside the scope of classical
propagation of chaos results. We obtain the propagation of chaos result by
taking advantage of the fact that the mean-field equations are Gaussian, which
allows us to use Borell's Inequality to prove that its tails decay
exponentially.
| arxiv topic:math.PR |
arxiv_dataset-69771601.05672 | Pluto's atmosphere from the 29 June 2015 ground-based stellar
occultation at the time of the New Horizons flyby
astro-ph.EP
We present results from a multi-chord Pluto stellar occultation observed on
29 June 2015 from New Zealand and Australia. This occurred only two weeks
before the NASA New Horizons flyby of the Pluto system and serves as a useful
comparison between ground-based and space results. We find that Pluto's
atmosphere is still expanding, with a significant pressure increase of
5$\pm$2\% since 2013 and a factor of almost three since 1988. This trend rules
out, as of today, an atmospheric collapse associated with Pluto's recession
from the Sun. A central flash, a rare occurrence, was observed from several
sites in New Zealand. The flash shape and amplitude are compatible with a
spherical and transparent atmospheric layer of roughly 3~km in thickness whose
base lies at about 4~km above Pluto's surface, and where an average thermal
gradient of about 5 K~km$^{-1}$ prevails. We discuss the possibility that small
departures between the observed and modeled flash are caused by local
topographic features (mountains) along Pluto's limb that block the stellar
light. Finally, using two possible temperature profiles, and extrapolating our
pressure profile from our deepest accessible level down to the surface, we
obtain a possible range of 11.9-13.7~$\mu$bar for the surface pressure.
| arxiv topic:astro-ph.EP |
arxiv_dataset-69781601.05772 | Phase Transitions and Duality in Adiabatic Memristive Networks
cond-mat.stat-mech cond-mat.mes-hall
The development of neuromorphic systems based on memristive elements -
resistors with memory - requires a fundamental understanding of their
collective dynamics when organized in networks. Here, we study an
experimentally inspired model of two-dimensional disordered memristive networks
subject to a slowly ramped voltage and show that they undergo a first-order
phase transition in the conductivity for sufficiently high values of memory, as
quantified by the memristive ON/OFF ratio. We investigate the consequences of
this transition for the memristive current-voltage characteristics both through
simulation and theory, and uncover a duality between forward and reverse
switching processes that has also been observed in several experimental systems
of this sort. Our work sheds considerable light on the statistical properties
of memristive networks that are presently studied both for unconventional
computing and as models of neural networks.
| arxiv topic:cond-mat.stat-mech cond-mat.mes-hall |
arxiv_dataset-69791601.05872 | The value of foresight
math.PR q-fin.PR
Suppose you have one unit of stock, currently worth 1, which you must sell
before time $T$. The Optional Sampling Theorem tells us that whatever stopping
time we choose to sell, the expected discounted value we get when we sell will
be 1. Suppose however that we are able to see $a$ units of time into the
future, and base our stopping rule on that; we should be able to do better than
expected value 1. But how much better can we do? And how would we exploit the
additional information? The optimal solution to this problem will never be
found, but in this paper we establish remarkably close bounds on the value of
the problem, and we derive a fairly simple exercise rule that manages to
extract most of the value of foresight.
| arxiv topic:math.PR q-fin.PR |
arxiv_dataset-69801601.05972 | On the Graph Fourier Transform for Directed Graphs
math.SP
The analysis of signals defined over a graph is relevant in many
applications, such as social and economic networks, big data or biological
networks, and so on. A key tool for analyzing these signals is the so called
Graph Fourier Transform (GFT). Alternative definitions of GFT have been
suggested in the literature, based on the eigen-decomposition of either the
graph Laplacian or adjacency matrix. In this paper, we address the general case
of directed graphs and we propose an alternative approach that builds the graph
Fourier basis as the set of orthonormal vectors that minimize a continuous
extension of the graph cut size, known as the Lov\'{a}sz extension. To cope
with the non-convexity of the problem, we propose two alternative iterative
optimization methods, properly devised for handling orthogonality constraints.
Finally, we extend the method to minimize a continuous relaxation of the
balanced cut size. The formulated problem is again non-convex and we propose an
efficient solution method based on an explicit-implicit gradient algorithm.
| arxiv topic:math.SP |
arxiv_dataset-69811601.06072 | Optical Polarization M\"obius Strips and Points of Purely Transverse
Spin Density
physics.optics
Tightly focused light beams can exhibit electric fields spinning around any
axis including the one transverse to the beams' propagation direction. At
certain focal positions, the corresponding local polarization ellipse can
degenerate into a perfect circle, representing a point of circular
polarization, or C-point. We consider the most fundamental case of a linearly
polarized Gaussian beam, where - upon tight focusing - those C-points created
by transversely spinning fields can form the center of 3D optical polarization
topologies when choosing the plane of observation appropriately. Due to the
high symmetry of the focal field, these polarization topologies exhibit non
trivial structures similar to M\"obius strips. We use a direct physical measure
to find C-points with an arbitrarily oriented spinning axis of the electric
field and experimentally investigate the fully three-dimensional polarization
topologies surrounding these C-points by exploiting an amplitude and phase
reconstruction technique.
| arxiv topic:physics.optics |
arxiv_dataset-69821601.06172 | Competing ground states of strongly correlated bosons in the
Harper-Hofstadter-Mott model
cond-mat.quant-gas
Using an efficient cluster approach, we study the physics of two-dimensional
lattice bosons in a strong magnetic field in the regime where the tunneling is
much weaker than the on-site interaction strength. We study both dilute, hard
core bosons at filling factors much smaller than unity occupation per site, and
the physics in the vicinity of the superfluid-Mott lobes as the density is
tuned away from unity. For hardcore bosons, we carry out extensive numerics for
a fixed flux per plaquette $\phi=1/5$ and $\phi = 1/3$. At large flux, the
lowest energy state is a strongly correlated superfluid, analogous to He-$4$,
in which the order parameter is dramatically suppressed, but non-zero. At
filling factors $\nu=1/2,1$, we find competing incompressible states which are
metastable. These appear to be commensurate density wave states. For small
flux, the situation is reversed, and the ground state at $\nu = 1/2$ is an
incompressible density-wave solid. Here, we find a metastable lattice
supersolid phase, where superfluidity and density-wave order coexist. We then
perform careful numerical studies of the physics near the vicinity of the Mott
lobes for $\phi = 1/2$ and $\phi = 1/4$. At $\phi = 1/2$, the superfluid ground
state has commensurate density-wave order. At $\phi = 1/4$, incompressible
phases appear outside the Mott lobes at densities $n = 1.125$ and $n = 1.25$,
corresponding to filling fractions $\nu = 1/2$ and $1$ respectively. These
phases, which are absent in single-site mean-field theory are metastable, and
have slightly higher energy than the superfluid, but the energy difference
between them shrinks rapidly with increasing cluster size, suggestive of an
incompressible ground state. We thus explore the interplay between Mott
physics, magnetic Landau levels, and superfluidity, finding a rich phase
diagram of competing compressible and incompressible states.
| arxiv topic:cond-mat.quant-gas |
arxiv_dataset-69831601.06272 | Turbulence and fire-spotting effects into wild-land fire simulators
physics.ao-ph
This paper presents a mathematical approach to model the effects of phenomena
with random nature such as turbulence and fire-spotting into the existing
wildfire simulators. The formulation proposes that the propagation of the
fire-front is the sum of a drifting component (obtained from an existing
wildfire simulator without turbulence and fire-spotting) and a random
fluctuating component. The modelling of the random effects is embodied in a
probability density function accounting for the fluctuations around the fire
perimeter which is given by the drifting component. In past, this formulation
has been applied to include these random effects into a wildfire simulator
based on an Eulerian moving interface method, namely the Level Set Method
(LSM), but in this paper the same formulation is adapted for a wildfire
simulator based on a Lagrangian front tracking technique, namely the Discrete
Event System Specification (DEVS). The main highlight of the present study is
the comparison of the performance of a Lagrangian and an Eulerian moving
interface method when applied to wild-land fire propagation. Simple idealised
numerical experiments are used to investigate the potential applicability of
the proposed formulation to DEVS and to compare its behaviour with respect to
the LSM. The results show that DEVS based wildfire propagation model
qualitatively improves its performance (e.g., reproducing flank and back fire,
increase in fire spread due to pre-heating of the fuel by hot air and
firebrands, fire propagation across no fuel zones, secondary fire generation,
\dots). Though the results presented here are devoid of any validation exercise
and provide only a proof of concept, they show a strong inclination towards an
intended operational use. The existing LSM or DEVS based operational simulators
like WRF-SFIRE and ForeFire respectively can serve as an ideal basis for the
same.
| arxiv topic:physics.ao-ph |
arxiv_dataset-69841601.06372 | An NFC-Enabled Anti-Counterfeiting System for Wine Industry
cs.CY
Wine counterfeiting has been posing significant challenges to wine industry,
and has undermined the international wine trading market and the global economy
hugely. The situation of counterfeiting has even been exacerbating in wine
industry and global supply chain. There has been a number of
anti-counterfeiting approaches which have been proposed and adopted utilizing
different authentication technologies, in response to growing threats of
counterfeiting to wine industry. The proposed NFC-Enabled Anti-Counterfeiting
System (NAS) is developed for luxury-good industry such as wine industry,
aiming at upholding provenance and authenticity of wine products from
counterfeits via the product pedigree, transaction records and supply chain
integrity maintained along the supply chain. Consumers can therefore safeguard
their stake by authenticating a specific wine product with their NFC-enabled
smartphones before purchasing at the retail points. NAS utilizes Near-field
Communication (NFC), which has emerged as a promising technology and
communication protocol for developing innovative alternatives, to facilitate
the wine record processing of wine products and in turn combat wine and spirit
counterfeiting. The integrated NAS is consisted of a wide range of hardware and
software components, and the best combination of settings, parameters and
deployments will therefore be identified. Other possible implementation issues,
such as tag selection, tag programming and encryption, setup of back-end
database servers and the design of NFC mobile application will also be
discussed in this project. The critical design of NAS is vital not only to the
key of product anti-counterfeiting of wine industry, but also to the strong
foundation for other innovative supply chain solutions, such as the NFC-enabled
purchasing system, developed on top of NAS with improved and integrated
anti-counterfeiting functionalities.
| arxiv topic:cs.CY |
arxiv_dataset-69851601.06472 | On the jumping phenomenon of
$\dim_{\mathbb{C}}H^q(\mathcal{X}_t,\mathcal{E}_t)$
math.DG math.AG math.CV
Let $X$ be a compact complex manifold and $E$ be a holomorphic vector bundle
on $X$. Given a deformation $(\mathcal{X},\mathcal{E})$ of the pair $(X,E)$
over a small polydisk $B$ centered at the origin, we study the jumping
phenomenon of the cohomology groups
$\dim_{\mathbb{C}}H^q(\mathcal{X}_t,\mathcal{E}_t)$ near $t = 0$. Generalizing
previous results of X. Ye for the tangent bundle $E = T_{\mathcal{X}_t}$ and
exterior powers of the cotangent bundle $E = \Omega^p_{\mathcal{X}_t}$, we show
that there are precisely two cohomological obstructions to the stability of
$\dim_{\mathbb{C}}H^q(\mathcal{X}_t,\mathcal{E}_t)$, which can be expressed
explicitly in terms of the Maurer-Cartan element associated to the deformation
$(\mathcal{X},\mathcal{E})$. As an application, we study the jumping phenomenon
of the dimension of the cohomology group
$H^1(\mathcal{X}_t,\text{End}(T_{\mathcal{X}_t}))$ which is related to a
question raised by physicists.
| arxiv topic:math.DG math.AG math.CV |
arxiv_dataset-69861601.06572 | Cyclicity in the harmonic Dirichlet space
math.CV math.CA math.FA
The harmonic Dirichlet space $\cal{D} (\mathbb{T})$ is the Hilbert space of
functions $f \in L^2(\mathbb{T})$ such that $$\|f\|_{\cal{D} (\mathbb{T})}^2 :=
\sum_{n\in\mathbb{Z}} (1+|n|)|\hat{f}(n)|^2 < \infty.$$ We give sufficient
conditions for $f$ to be cyclic in $\cal{D} (\mathbb{T})$, in other words, for
$\{\zeta ^nf(\zeta):\ n\geq 0\}$ to span a dense subspace of $\cal{D}
(\mathbb{T})$.
| arxiv topic:math.CV math.CA math.FA |
arxiv_dataset-69871601.06672 | Pricing Vehicle Sharing with Proximity Information
math.OC cs.AI cs.MA
For vehicle sharing schemes, where drop-off positions are not fixed, we
propose a pricing scheme, where the price depends in part on the distance
between where a vehicle is being dropped off and where the closest shared
vehicle is parked. Under certain restrictive assumptions, we show that this
pricing leads to a socially optimal spread of the vehicles within a region.
| arxiv topic:math.OC cs.AI cs.MA |
arxiv_dataset-69881601.06772 | Tachyonic models of dark matter
gr-qc astro-ph.GA
We consider a spherically symmetric stationary problem in General Relativity,
including a black hole, inflow of normal and tachyonic matter and outflow of
tachyonic matter. Computations in a weak field limit show that the resulting
concentration of matter around the black hole leads to gravitational effects
equivalent to those associated with dark matter halo. In particular, the model
reproduces asymptotically constant galactic rotation curves, if the tachyonic
flows of the central supermassive black hole in the galaxy are considered as a
main contribution.
| arxiv topic:gr-qc astro-ph.GA |
arxiv_dataset-69891601.06872 | Double Circulant Matrices
math.RA
Double circulant matrices are introduced and studied. A formula to compute
the rank r of a double circulant matrix is exhibited; and it is shown that any
consecutive r rows of the double circulant matrix are linearly independent. As
a generalization, multiple circulant matrices are also introduced. Two
questions on square double circulant matrices are suggested.
| arxiv topic:math.RA |
arxiv_dataset-69901601.06972 | A numerical treatment to the problem of the quantity of Einstein metrics
on flag manifolds
math.DG math-ph math.MP
In this paper we employ numerical methods to study the Einstein equation \[
Ric(g)=\lambda\, g, \] where $Ric$ is the Ricci tensor and $\lambda$ is the
Einstein constant, restricted to a class of full flag manifolds. These metrics
describe the gravitational field of a vacuum with cosmological constant (vacuum
is the case $\lambda=0$). In particular, we give estimates to the number of
such metrics on the full flag manifolds $SU(n+1)/T^n$ for $n=4,5$, improving
some classical estimatives. We also examine the isometric problem for these
Einstein metrics. Our method can be applied for any fixed $n$.
| arxiv topic:math.DG math-ph math.MP |
arxiv_dataset-69911601.07072 | Event patterns extracted from transverse momentum and rapidity spectra
of Z bosons and quarkonium states produced in pp and Pb-Pb collisions at LHC
hep-ph hep-ex nucl-ex nucl-th
Transverse momentum ($p_T$) and rapidity ($y$) spectra of $Z$ bosons and
quarkonium states (some charmonium $c\bar c$ mesons such as $J/\psi$ and
$\psi(2S)$, and some bottomonium $b\bar b$ mesons such as $\Upsilon(1S)$,
$\Upsilon(2S)$, and $\Upsilon(3S)$) produced in proton-proton ($pp$) and
lead-lead (Pb-Pb) collisions at the large hadron collider (LHC) are uniformly
described by a hybrid model of two-component Erlang distribution for $p_T$
spectrum and two-component Gaussian distribution for $y$ spectrum. The former
distribution results from a multisource thermal model, and the latter one
results from the revised Landau hydrodynamic model. The modelling results are
in agreement with the experimental data measured in $pp$ collisions at
center-of-mass energies $\sqrt{s}=2.76$ and 7 TeV, and in Pb-Pb collisions at
center-of-mass energy per nucleon pair $\sqrt{s_{NN}}=2.76$ TeV. Based on the
parameter values extracted from $p_T$ and $y$ spectra, the event patterns
(particle scatter plots) in two-dimensional $p_T$-$y$ space and in
three-dimensional velocity space are obtained.
| arxiv topic:hep-ph hep-ex nucl-ex nucl-th |
arxiv_dataset-69921601.07172 | Measuring the Weak Charge of the Proton via Elastic Electron-Proton
Scattering
nucl-ex physics.ins-det
The Qweak experiment which ran at Jefferson Lab in Newport News, VA, measured
the weak charge of the proton $Q_W^p$ via elastic electron-proton scattering.
Longitudinally polarized electrons were scattered from an unpolarized liquid
hydrogen target. The Standard Model predicts a small parity-violating asymmetry
of scattering rates between electron right and left helicity states due to the
weak interaction. An initial result using 4% of the data was published in
October 2013 with a measured parity-violating asymmetry of $-279\pm
35(\text{stat})\pm 31$ (syst) parts per billion (ppb). This asymmetry, along
with other data from parity-violating electron scattering experiments, provided
the world's first determination of the weak charge of the proton. The weak
charge of the proton was found to be $Q_W^p=0.064\pm0.012$, in agreement with
the Standard Model prediction of $Q_W^p(SM)=0.0708\pm0.0003$.
The results of the full dataset are expected to decrease the statistical
error from the initial publication by a factor of 4-5. The level of precision
of the final result makes it a useful test of Standard Model predictions and
particularly of the "running" of $\sin^2\theta_W$ from the Z-mass to low
energies. This thesis focuses on reduction of systematic error in two key
systematics for the Qweak experiment. First, techniques for measuring and
removing false asymmetries arising from helicity-correlated electron beam
properties at the few ppb level are discussed. Second, as a parity-violating
experiment, Qweak relies on accurate knowledge of electron beam polarimetry. To
help address the requirement of accurate polarimetry, a Compton polarimeter
built specifically for Qweak. Compton polarimetry requires accurate knowledge
of laser polarization inside a Fabry-Perot cavity enclosed in the electron beam
pipe. A new technique was developed for Qweak that nearly eliminates this
systematic error.
| arxiv topic:nucl-ex physics.ins-det |
arxiv_dataset-69931601.07272 | A Discrete Surface Theory
math.DG cond-mat.mtrl-sci
In the present paper, we propose a new discrete surface theory on 3-valent
embedded graphs in the 3-dimensional Euclidean space which are not necessarily
discretization or approximation of smooth surfaces. The Gauss curvature and the
mean curvature of discrete surfaces are defined which satisfy properties
corresponding to the classical surface theory. We also discuss the convergence
of a family of subdivided discrete surfaces of a given 3-valent discrete
surface by using the Goldberg-Coxeter construction. Although discrete surfaces
in general have no corresponding smooth surfaces, we may find one as the limit.
| arxiv topic:math.DG cond-mat.mtrl-sci |
arxiv_dataset-69941601.07372 | Deep Saturated Free Electron Laser Oscillators and Frozen Spikes
physics.acc-ph
We analyze the behavior of Free Electron Laser (FEL) oscillators operating in
the deep saturated regime and point out the formation of sub-peaks of the
optical pulse. They are very stable configurations, having a width
corresponding to a coherence length. We speculate on the physical mechanisms
underlying their growth and attempt an identification with FEL mode locked
structures associated with Super Modes. Their impact on the intra-cavity
nonlinear harmonic generation is also discussed along with the possibility of
exploiting them as cavity out-coupler.
| arxiv topic:physics.acc-ph |
arxiv_dataset-69951601.07472 | Formalized linear algebra over Elementary Divisor Rings in Coq
cs.LO math.RA
This paper presents a Coq formalization of linear algebra over elementary
divisor rings, that is, rings where every matrix is equivalent to a matrix in
Smith normal form. The main results are the formalization that these rings
support essential operations of linear algebra, the classification theorem of
finitely presented modules over such rings and the uniqueness of the Smith
normal form up to multiplication by units. We present formally verified
algorithms computing this normal form on a variety of coefficient structures
including Euclidean domains and constructive principal ideal domains. We also
study different ways to extend B\'ezout domains in order to be able to compute
the Smith normal form of matrices. The extensions we consider are: adequacy
(i.e. the existence of a gdco operation), Krull dimension $\leq 1$ and
well-founded strict divisibility.
| arxiv topic:cs.LO math.RA |
arxiv_dataset-69961601.07572 | Analysis and Evaluation for the Performance of the Communication
Infrastructure for Real Wide Area Monitoring Systems (WAMS) Based on 3G
Technology
cs.NI
Wide Area Monitoring Systems (WAMS) utilizing synchrophasor measurements is
considered one of the essential parts in smart grids that enable system
operators to monitor, operate, and control power systems in wide geographical
area. On the other hand, high-speed, reliable and scalable data communication
infrastructure is crucial in both construction and operation of WAMS. Universal
mobile Telecommunication System (UMTS), the 3G standard for mobile
communication networks, was developed to provide high speed data transmission
with reliable service performance for mobile users. Therefore, UMTS is
considered a promising solution for providing a communication infrastructure
for WAMS. 3G based EWAMS (Egyptian wide area Monitoring System) is designed and
implemented in Egypt through deployment a number of frequency disturbance
recorders (FDRs) devices on a live 220kV/500kV Egyptian grid in cooperation
with the Egyptian Electricity Transmission Company (EETC). The developed EWAMS
can gather information from 11 FDRs devices which are geographically dispersed
throughout the boundary of the Egyptian power grid and to a remote data
management center located at Helwan University. The communication performance
for the developed EWAMS in terms of communication time delay, throughput, and
percentage of wasted bandwidth are studied in this paper. The results showed
that the system can achieve successfully the communication requirements needed
by various wide area monitoring applications.
| arxiv topic:cs.NI |
arxiv_dataset-69971601.07672 | The bijection between exceptional subcategories and non-crossing
partitions
math.RT
This note discusses the bijection between the exceptional subcategories of
representations of quivers and generalized non-crossing partitions of Weyl
groups. We give a new proof of the Ingalls-Thomas-Igusa-Schiffler bijection by
using the exchange property of the Weyl groups of the Kac-Moody Lie algebras.
| arxiv topic:math.RT |
arxiv_dataset-69981601.07772 | Wigner Functions for Arbitrary Quantum Systems
quant-ph math-ph math.MP
The possibility of constructing a complete, continuous Wigner function for
any quantum system has been a subject of investigation for over 50 years. A key
system that has served to illustrate the difficulties of this problem has been
an ensemble of spins. Here we present a general and consistent framework for
constructing Wigner functions exploiting the underlying symmetries in the
physical system at hand. The Wigner function can be used to fully describe any
quantum system of arbitrary dimension or ensemble size.
| arxiv topic:quant-ph math-ph math.MP |
arxiv_dataset-69991601.07872 | Nonparametric Clustering of Functional Data Using Pseudo-Densities
math.ST stat.ME stat.TH
We study nonparametric clustering of smooth random curves on the basis of the
L2 gradient flow associated to a pseudo-density functional and we show that the
clustering is well-defined both at the population and at the sample level. We
provide an algorithm to mark significant local modes, which are associated to
informative sample clusters, and we derive its consistency properties. Our
theory is developed under weak assumptions, which essentially reduce to the
integrability of the random curves, and does not require to project the random
curves on a finite-dimensional subspace. However, if the underlying probability
distribution is supported on a finite-dimensional subspace, we show that the
pseudo-density and the expectation of a kernel density estimator induce the
same gradient flow, and therefore the same clustering. Although our theory is
developed for smooth curves that belong to an infinite-dimensional functional
space, we also provide consistent procedures that can be used with real data
(discretized and noisy observations).
| arxiv topic:math.ST stat.ME stat.TH |
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