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arxiv_dataset-66001509.05361 | Direct evidences for inner-shell electron-excitation by laser induced
electron recollision
physics.atom-ph
Extreme ultraviolet (XUV) attosecond pulses, generated by a process known as
laser-induced electron recollision, are a key ingredient for attosecond
metrology, providing a tool to precisely initiate and probe sub-femtosecond
dynamics in the microcosms of atoms, molecules and solids[1]. However, with the
current technology, extending attosecond metrology to scrutinize the dynamics
of the inner-shell electrons is a challenge, that is because of the lower
efficiency in generating the required soft x-ray \hbar\omega>300 eV attosecond
bursts and the lower absorption cross-sections in this spectral range. A way
around this problem is to use the recolliding electron to directly initiate the
desired inner-shell process, instead of using the currently low flux x-ray
attosecond sources.Such an excitation process occurs in a sub-femtosecond
timescale, and may provide the necessary "pump" step in a pump-probe
experiment[2]. Here we used a few cycle infrared \lambda_{0}~1800nm source[3]
and observed direct evidences for inner-shell excitations through the
laser-induced electron recollision process. It is the first step toward
time-resolved core-hole studies in the keV energy range with sub-femtosecond
time resolution.
| arxiv topic:physics.atom-ph |
arxiv_dataset-66011509.05461 | A scoop from groups: Equational foundations for loops
math.GR
Groups are usually axiomatized as algebras with an associative binary
operation, a two-sided neutral element, and with two-sided inverses. We show in
this note that the same simplicity of axioms can be achieved for some of the
most important varieties of loops. In particular, we investigate loops of
Bol-Moufang type in the underlying variety of magmas with two-sided inverses,
and obtain "group-like" equational bases for Moufang, Bol and C-loops. We also
discuss the case when the inverses are only one-sided and/or the neutral
element is only one-sided.
| arxiv topic:math.GR |
arxiv_dataset-66021509.05561 | Long multiplets in supersymmetric mechanics
hep-th
The "long" indecomposable N=2, d=1 multiplet (2, 4, 2) defined in
arXiv:1503.05537 [hep-th] as a deformation of the pair of chiral multiplets (2,
2, 0) and (0, 2, 2) by a number of the mass-dimension parameters is described
in the superfield approach. We present its most general superfield and
component actions, as well as a generalization to the case with the superfields
of the opposite Grassmann parities and dimensionless deformation parameter. We
show that the long N=2, d=1 multiplets are naturally embedded into the chiral
SU(2|1), d=1 superfields having nonzero external spins with respect to SU(2)
\subset SU(2|1). A superfield with spin s contains 2s long multiplets and two
short multiplets (2, 2, 0) and (0, 2, 2). Two possible N=4, d=1 generalizations
of the N=2 long multiplet in the superfield approach are also proposed.
| arxiv topic:hep-th |
arxiv_dataset-66031509.05661 | Some counterexamples to Sobolev regularity for degenerate
Monge-Amp\`{e}re equations
math.AP
We construct a counterexample to $W^{2,1}$ regularity for convex solutions to
$$\det D^2u \leq 1, \quad u|_{\partial \Omega} = 0$$ in two dimensions. We also
prove a result on the propagation of singularities in two dimensions that are
logarithmically slower than Lipschitz. This generalizes a classical result of
Alexandrov and is optimal by example.
| arxiv topic:math.AP |
arxiv_dataset-66041509.05761 | A single crystal beam bent in double slip
cond-mat.mtrl-sci
The theory of plastic bending of single crystal beam having two active slip
systems is proposed. Applying the variational-asymptotic method we reduce the
energy functional of the beam to the one-dimensional energy functional which
admits analytical solutions for the symmetric slip systems. The threshold value
at the onset of plastic yielding, the dislocation density, as well as the
moment-curvature curve are found. We solve also a similar problem that takes
the energy dissipation into account.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-66051509.05861 | Aberration in qualitative multilevel designs
math.ST stat.ME stat.TH
Generalized Word Length Pattern (GWLP) is an important and widely-used tool
for comparing fractional factorial designs. We consider qualitative factors,
and we code their levels using the roots of the unity. We write the GWLP of a
fraction ${\mathcal F}$ using the polynomial indicator function, whose
coefficients encode many properties of the fraction. We show that the
coefficient of a simple or interaction term can be written using the counts of
its levels. This apparently simple remark leads to major consequence, including
a convolution formula for the counts. We also show that the mean aberration of
a term over the permutation of its levels provides a connection with the
variance of the level counts. Moreover, using mean aberrations for symmetric
$s^m$ designs with $s$ prime, we derive a new formula for computing the GWLP of
${\mathcal F}$. It is computationally easy, does not use complex numbers and
also provides a clear way to interpret the GWLP. As case studies, we consider
non-isomorphic orthogonal arrays that have the same GWLP. The different
distributions of the mean aberrations suggest that they could be used as a
further tool to discriminate between fractions.
| arxiv topic:math.ST stat.ME stat.TH |
arxiv_dataset-66061509.05961 | On Conformal Qc Geometry, Spherical Qc Manifolds and Convex Cocompact
Subgroups of ${\rm Sp}{(n+1,1)}$
math.DG math.CV
Conformal qc geometry of spherical qc manifolds are investigated. We
construct the qc Yamabe operators on qc manifolds, which are covariant under
the conformal qc transformations. A qc manifold is scalar positive, negative or
vanishing if and only if its qc Yamabe invariant is positive, negative or zero,
respectively. On a scalar positive spherical qc manifold, we can construct the
Green function of the qc Yamabe operator, which can be applied to construct a
conformally invariant tensor. It becomes a spherical qc metric if the qc
positive mass conjecture is true. Conformal qc geometry of spherical qc
manifolds can be applied to study convex cocompact subgroups of ${\rm
Sp}(n+1,1).$ On a spherical qc manifold constructed from such a discrete
subgroup, we construct a spherical qc metric of Nayatani type. As a corollary,
we prove that such a spherical qc manifold is scalar positive, negative or
vanishing if and only if the Poincar\'e critical exponent of the discrete
subgroup is less than, greater than or equal to $2n+2$, respectively.
| arxiv topic:math.DG math.CV |
arxiv_dataset-66071509.06061 | A Statistical Theory of Deep Learning via Proximal Splitting
stat.ML
In this paper we develop a statistical theory and an implementation of deep
learning models. We show that an elegant variable splitting scheme for the
alternating direction method of multipliers optimises a deep learning
objective. We allow for non-smooth non-convex regularisation penalties to
induce sparsity in parameter weights. We provide a link between traditional
shallow layer statistical models such as principal component and sliced inverse
regression and deep layer models. We also define the degrees of freedom of a
deep learning predictor and a predictive MSE criteria to perform model
selection for comparing architecture designs. We focus on deep multiclass
logistic learning although our methods apply more generally. Our results
suggest an interesting and previously under-exploited relationship between deep
learning and proximal splitting techniques. To illustrate our methodology, we
provide a multi-class logit classification analysis of Fisher's Iris data where
we illustrate the convergence of our algorithm. Finally, we conclude with
directions for future research.
| arxiv topic:stat.ML |
arxiv_dataset-66081509.06161 | On 3D Face Reconstruction via Cascaded Regression in Shape Space
cs.CV
Cascaded regression has been recently applied to reconstructing 3D faces from
single 2D images directly in shape space, and achieved state-of-the-art
performance. This paper investigates thoroughly such cascaded regression based
3D face reconstruction approaches from four perspectives that are not well
studied yet: (i) The impact of the number of 2D landmarks; (ii) the impact of
the number of 3D vertices; (iii) the way of using standalone automated landmark
detection methods; and (iv) the convergence property. To answer these
questions, a simplified cascaded regression based 3D face reconstruction method
is devised, which can be integrated with standalone automated landmark
detection methods and reconstruct 3D face shapes that have the same pose and
expression as the input face images, rather than normalized pose and
expression. Moreover, an effective training method is proposed by disturbing
the automatically detected landmarks. Comprehensive evaluation experiments have
been done with comparison to other 3D face reconstruction methods. The results
not only deepen the understanding of cascaded regression based 3D face
reconstruction approaches, but also prove the effectiveness of proposed method.
| arxiv topic:cs.CV |
arxiv_dataset-66091509.06261 | Standard Model Theory
hep-ph
Recent progress in the field of precision calculations for Standard Model
processes at the LHC is reviewed, highlighting examples of weak gauge-boson and
Higgs-boson production, as discussed at the 27th Rencontres de Blois, 2015.
| arxiv topic:hep-ph |
arxiv_dataset-66101509.06361 | Quantum Query Complexity of Subgraph Isomorphism and Homomorphism
cs.CC quant-ph
Let $H$ be a fixed graph on $n$ vertices. Let $f_H(G) = 1$ iff the input
graph $G$ on $n$ vertices contains $H$ as a (not necessarily induced) subgraph.
Let $\alpha_H$ denote the cardinality of a maximum independent set of $H$. In
this paper we show:
\[Q(f_H) = \Omega\left(\sqrt{\alpha_H \cdot n}\right),\] where $Q(f_H)$
denotes the quantum query complexity of $f_H$.
As a consequence we obtain a lower bounds for $Q(f_H)$ in terms of several
other parameters of $H$ such as the average degree, minimum vertex cover,
chromatic number, and the critical probability.
We also use the above bound to show that $Q(f_H) = \Omega(n^{3/4})$ for any
$H$, improving on the previously best known bound of $\Omega(n^{2/3})$. Until
very recently, it was believed that the quantum query complexity is at least
square root of the randomized one. Our $\Omega(n^{3/4})$ bound for $Q(f_H)$
matches the square root of the current best known bound for the randomized
query complexity of $f_H$, which is $\Omega(n^{3/2})$ due to Gr\"oger.
Interestingly, the randomized bound of $\Omega(\alpha_H \cdot n)$ for $f_H$
still remains open.
We also study the Subgraph Homomorphism Problem, denoted by $f_{[H]}$, and
show that $Q(f_{[H]}) = \Omega(n)$.
Finally we extend our results to the $3$-uniform hypergraphs. In particular,
we show an $\Omega(n^{4/5})$ bound for quantum query complexity of the Subgraph
Isomorphism, improving on the previously known $\Omega(n^{3/4})$ bound. For the
Subgraph Homomorphism, we obtain an $\Omega(n^{3/2})$ bound for the same.
| arxiv topic:cs.CC quant-ph |
arxiv_dataset-66111509.06461 | Deep Reinforcement Learning with Double Q-learning
cs.LG
The popular Q-learning algorithm is known to overestimate action values under
certain conditions. It was not previously known whether, in practice, such
overestimations are common, whether they harm performance, and whether they can
generally be prevented. In this paper, we answer all these questions
affirmatively. In particular, we first show that the recent DQN algorithm,
which combines Q-learning with a deep neural network, suffers from substantial
overestimations in some games in the Atari 2600 domain. We then show that the
idea behind the Double Q-learning algorithm, which was introduced in a tabular
setting, can be generalized to work with large-scale function approximation. We
propose a specific adaptation to the DQN algorithm and show that the resulting
algorithm not only reduces the observed overestimations, as hypothesized, but
that this also leads to much better performance on several games.
| arxiv topic:cs.LG |
arxiv_dataset-66121509.06561 | Equation of state constraints for the cold dense matter inside neutron
stars using the cooling tail method
astro-ph.HE nucl-th
The cooling phase of thermonuclear (type-I) X-ray bursts can be used to
constrain the neutron star (NS) compactness by comparing the observed cooling
tracks of bursts to accurate theoretical atmosphere model calculations. By
applying the so-called cooling tail method, where the information from the
whole cooling track is used, we constrain the mass, radius, and distance for
three different NSs in low-mass X-ray binaries 4U 1702-429, 4U 1724-307, and
SAX J1810.8-260. Care is taken to only use the hard state bursts where it is
thought that only the NS surface alone is emitting. We then utilize a Markov
chain Monte Carlo algorithm within a Bayesian framework to obtain a
parameterized equation of state (EoS) of cold dense matter from our initial
mass and radius constraints. This allows us to set limits on various nuclear
parameters and to constrain an empirical pressure-density relation for the
dense matter. Our predicted EoS results in NS radius between 10.5-12.8 km (95%
confidence limits) for a mass of 1.4 $M_{\odot}$. Due to systematic errors and
uncertainty in the composition these results should be interpreted as lower
limits for the radius.
| arxiv topic:astro-ph.HE nucl-th |
arxiv_dataset-66131509.06661 | Tricritical wings in UGe$_2$: A microscopic interpretation
cond-mat.str-el
In the present work we analyze the second order transition line that connect
the tricritical point and the quantum critical ending point on the
temperature--magnetic-field plane in UGe$_2$. For the microscopic modeling we
employ the Anderson lattice model recently shown to provide a fairly complete
description of the full magnetic phase diagram of UGe$_2$ including all the
criticalities. The shape of the so-called tricritical wings, i.e. surfaces of
the first-order transitions, previously reported by us to quantitatively agree
with the experimental data, is investigated here with respect to the change of
the total filling and the Land\'e factor for $f$ electrons which can differ
from the free electron value. The analysis of the total filling dependence
demonstrates sensitivity of our prediction when the respective positions of the
critical ending point at the metamagnetic transition and tricritical point are
mismatched as compared to the experiment.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-66141509.06761 | The Spectra of Type IIB Flux Compactifications at Large Complex
Structure
hep-th
We compute the spectra of the Hessian matrix, ${\cal H}$, and the matrix
${\cal M}$ that governs the critical point equation of the low-energy effective
supergravity, as a function of the complex structure and axio-dilaton moduli
space in type IIB flux compactifications at large complex structure. We find
both spectra analytically in an $h^{1,2}_-+3$ real-dimensional subspace of the
moduli space, and show that they exhibit a universal structure with highly
degenerate eigenvalues, independently of the choice of flux, the details of the
compactification geometry, and the number of complex structure moduli. In this
subspace, the spectrum of the Hessian matrix contains no tachyons, but there
are also no critical points. We show numerically that the spectra of ${\cal H}$
and ${\cal M}$ remain highly peaked over a large fraction of the sampled moduli
space of explicit Calabi-Yau compactifications with 2 to 5 complex structure
moduli. In these models, the scale of the supersymmetric contribution to the
scalar masses is strongly linearly correlated with the value of the
superpotential over almost the entire moduli space, with particularly strong
correlations arising for $g_s < 1$. We contrast these results with the
expectations from the much-used continuous flux approximation, and comment on
the applicability of Random Matrix Theory to the statistical modelling of the
string theory landscape.
| arxiv topic:hep-th |
arxiv_dataset-66151509.06861 | The spectral function of the Tomonaga-Luttinger model revisited: power
laws and universality
cond-mat.str-el
We reinvestigate the momentum-resolved single-particle spectral function of
the Tomonaga-Luttinger model. In particular, we focus on the role of the
momentum-dependence of the two-particle interaction V(q). Usually, V(q) is
assumed to be a constant and integrals are regularized in the ultraviolet `by
hand' employing an ad hoc procedure. As the momentum dependence of the
interaction is irrelevant in the renormalization group sense this does not
affect the universal low-energy properties of the model, e.g. exponents of
power laws, if all energy scales are sent to zero. If, however, the momentum k
is fixed away from the Fermi momentum k_F, with |k-k_F| setting a nonvanishing
energy scale, the details of V(q) start to matter. We provide strong evidence
that any curvature of the two-particle interaction at small transferred
momentum q destroys power-law scaling of the momentum resolved spectral
function as a function of energy. Even for |k-k_F| much smaller than the
momentum space range of the interaction the spectral line shape depends on the
details of V(q). The significance of our results for universality in the
Luttinger liquid sense, for experiments on quasi one-dimensional metals, and
for recent attempts to compute the spectral function of one-dimensional
correlated systems taking effects of the curvature of the single-particle
dispersion into account (nonlinear Luttinger liquid phenomenology) is
discussed.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-66161509.06961 | A stochastic model for competing growth on $\mathbb{R}^d$
math.PR
A stochastic model, describing the growth of two competing infections on
$\mathbb{R}^d$, is introduced. The growth is driven by outbursts in the
infected region, an outburst in the type 1 (2) infected region transmitting the
type 1 (2) infection to the previously uninfected parts of a ball with
stochastic radius around the outburst point. The main result is that with the
growth rate for one of the infection types fixed, mutual unbounded growth has
probability zero for all but at most countably many values of the other
infection rate. This is a continuum analog of a result of H\"{a}ggstr\"{o}m and
Pemantle. We also extend a shape theorem of Deijfen for the corresponding model
with just one type of infection.
| arxiv topic:math.PR |
arxiv_dataset-66171509.07061 | Introduction to SARAH and related tools
hep-ph
I give in this lecture an overview of the features of the Mathematica package
SARAH, and explain how it can be used together with other codes to study all
aspects of a BSM model. The focus will be on the description of the analytical
calculations which SARAH can perform and how this information is used to
generate automatically a spectrum generator based on SPheno. I also summarize
the main aspects of the other interfaces to public codes like
HiggsBounds/HiggsSignals, FeynArts/FormCalc, CalcHep, MicrOmegas, WHIZARD,
Vevacious or MadGraph. The appendix contains a short tutorial about the
implementation and usage of a new model.
| arxiv topic:hep-ph |
arxiv_dataset-66181509.07161 | On p-adic modular forms and the Bloch-Okounkov theorem
math.NT
Bloch-Okounkov studied certain functions on partitions $f$ called shifted
symmetric polynomials. They showed that certain $q$-series arising from these
functions (the so-called \emph{$q$-brackets} $\left<f\right>_q$) are
quasimodular forms. We revisit a family of such functions, denoted $Q_k$, and
study the $p$-adic properties of their $q$-brackets. To do this, we define
regularized versions $Q_k^{(p)}$ for primes $p.$ We also use Jacobi forms to
show that the $\left<Q_k^{(p)}\right>_q$ are quasimodular and find explicit
expressions for them in terms of the $\left<Q_k\right>_q$.
| arxiv topic:math.NT |
arxiv_dataset-66191509.07261 | On the Eddington limit for relativistic accretion discs
astro-ph.HE
Standard accretion disc model relies upon several assumptions, the most
important of which is geometrical thinness. Whenever this condition is
violated, new physical effects become important such as radial energy advection
and mass loss from the disc. These effects are important, for instance, for
large mass accretion rates when the disc approaches its local Eddington limit.
In this work, we study the upper limits for standard accretion disc
approximation and find the corrections to the standard model that should be
considered in any model aiming on reproducing the transition to super-Eddington
accretion regime. First, we find that for thin accretion disc, taking into
account relativistic corrections allows to increase the local Eddington limit
by about a factor of two due to stronger gravity in General Relativity (GR).
However, violation of the local Eddington limit also means large disc
thickness. To consider consequently the disc thickness effects, one should make
assumptions upon the two-dimensional rotation law of the disc. For rotation
frequency constant on cylinders $r\sin\theta=const$, vertical gravity becomes
stronger with height on spheres of constant radius. On the other hand, effects
of radial flux advection increase the flux density in the inner parts of the
disc and lower the Eddington limit. In general, the effects connected to disc
thickness tend to increase the local Eddington limit even more. The efficiency
of accretion is however decreased by advection effects by about a factor of
several.
| arxiv topic:astro-ph.HE |
arxiv_dataset-66201509.07361 | A new topological semimetal with iso-energetic Weyl fermions in TaAs
under high pressure
cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.str-el
TaAs as one of the experimentally discovered topological Weyl semimetal has
attracted intense interests recently. The ambient TaAs has two types of Weyl
nodes which are not on the same energy level. As an effective way to tune
lattice parameters and electronic interactions, high pressure is becoming a
significant tool to explore new materials as well as their exotic states.
Therefore, it is highly interesting to investigate the behaviors of topological
Weyl fermions and possible structural phase transitions in TaAs under pressure.
Here, with a combination of ab initio calculations and crystal structure
prediction techniques, a new hexagonal P-6m2 phase is predicted in TaAs at
pressure around 14 GPa. Surprisingly, this new phase is a topological semimetal
with only single set of Weyl nodes exactly on the same energy level. The phase
transition pressure from the experimental measurements, including electrical
transport measurements and Raman spectroscopy, agrees with our theoretical
prediction reasonably. Moreover, the P-6m2 phase seems to be quenched
recoverable to ambient pressure, which increases the possibilities of further
study on the exotic behaviors of single set of Weyl fermions, such as the
interplay between surface states and other properties.
| arxiv topic:cond-mat.mtrl-sci cond-mat.mes-hall cond-mat.str-el |
arxiv_dataset-66211509.07461 | Invariant domains and first-order continuous finite element
approximation for hyperbolic systems
math.NA
We propose a numerical method to solve general hyperbolic systems in any
space dimension using forward Euler time stepping and continuous finite
elements on non-uniform grids. The properties of the method are based on the
introduction of an artificial dissipation that is defined so that any convex
invariant sets containing the initial data is an invariant domain for the
method. The invariant domain property is proved for any hyperbolic system
provided a CFL condition holds. The solution is also shown to satisfy a
discrete entropy inequality for every admissible entropy of the system. The
method is formally first-order accurate in space and can be made high-order in
time by using Strong Stability Preserving algorithms. This technique extends to
continuous finite elements the work of \cite{Hoff_1979,Hoff_1985}, and
\cite{Frid_2001}.
| arxiv topic:math.NA |
arxiv_dataset-66221509.07561 | Surveying the TeV sky with HAWC
astro-ph.HE astro-ph.IM
The High altitude Water Cherenkov (HAWC) Observatory has been completed and
began full operation in early 2015. Located at an elevation of 4,100 m near the
Sierra Negra volcano in the state of Puebla, Mexico, HAWC consists of 300 water
tanks instrumented with 4 PMTs each. The array is optimized for detecting air
showers produced by gamma rays with energies between 100 GeV and 100 TeV and
can also be used to measure charged cosmic rays. A wide instantaneous field of
view of ~2 steradians and a duty cycle >95% allow HAWC to survey two-thirds of
the sky every day. These unique capabilities make it possible to monitor
variable gamma-ray fluxes and search for gamma-ray bursts and other transient
events, providing new insights into particle acceleration in galactic and
extra-galactic sources. In this contribution, we will present first results
from more than one year of observations with a partial array configuration. We
will discuss how HAWC can map the gamma-ray sky as well as probe other physics
including cosmic ray anisotropies and the search for signatures of dark matter
annihilation.
| arxiv topic:astro-ph.HE astro-ph.IM |
arxiv_dataset-66231509.07661 | Electron multipacting in long-bunch beam
physics.acc-ph
The electron multipacting is an important factor for the development of the
electron cloud. There is a trailing-edge multipacting in the tail of the
long-bunch beam. It can be described by the energy gain and motion of
electrons. The analyses are in agreement with the simulation.
| arxiv topic:physics.acc-ph |
arxiv_dataset-66241509.07761 | Sentiment of Emojis
cs.CL
There is a new generation of emoticons, called emojis, that is increasingly
being used in mobile communications and social media. In the past two years,
over ten billion emojis were used on Twitter. Emojis are Unicode graphic
symbols, used as a shorthand to express concepts and ideas. In contrast to the
small number of well-known emoticons that carry clear emotional contents, there
are hundreds of emojis. But what are their emotional contents? We provide the
first emoji sentiment lexicon, called the Emoji Sentiment Ranking, and draw a
sentiment map of the 751 most frequently used emojis. The sentiment of the
emojis is computed from the sentiment of the tweets in which they occur. We
engaged 83 human annotators to label over 1.6 million tweets in 13 European
languages by the sentiment polarity (negative, neutral, or positive). About 4%
of the annotated tweets contain emojis. The sentiment analysis of the emojis
allows us to draw several interesting conclusions. It turns out that most of
the emojis are positive, especially the most popular ones. The sentiment
distribution of the tweets with and without emojis is significantly different.
The inter-annotator agreement on the tweets with emojis is higher. Emojis tend
to occur at the end of the tweets, and their sentiment polarity increases with
the distance. We observe no significant differences in the emoji rankings
between the 13 languages and the Emoji Sentiment Ranking. Consequently, we
propose our Emoji Sentiment Ranking as a European language-independent resource
for automated sentiment analysis. Finally, the paper provides a formalization
of sentiment and a novel visualization in the form of a sentiment bar.
| arxiv topic:cs.CL |
arxiv_dataset-66251509.07861 | Exact solution of a delay difference equation modeling traffic flow and
their ultra-discrete limit
nlin.CG math-ph math.MP
We consider a car-following model described by a delay difference equation
and give its exact solutions that present propagation of a traffic jam. This
model is a discrete-time version of the delayed optimal-velocity model; in the
continuum limit, we recover the delay differential equation for this model and
the exact solutions as well. We then work in the ultra-discrete limit,
obtaining a delay cellular-automaton model, which successfully inherits the
solutions. Also the dispersion relation for the present solutions suggests that
a quick response of drivers does not always result in fast dissolution of a
traffic jam.
| arxiv topic:nlin.CG math-ph math.MP |
arxiv_dataset-66261509.07961 | Energy dissipation in magnetic null points at kinetic scales
astro-ph.EP astro-ph.SR physics.plasm-ph physics.space-ph
We use kinetic particle-in-cell and magnetohydrodynamic simulations supported
by an observational dataset to investigate magnetic reconnection in clusters of
null points in space plasma. The magnetic configuration under investigation is
driven by fast adiabatic flux rope compression that dissipates almost half of
the initial magnetic field energy. In this phase powerful currents are excited
producing secondary instabilities, and the system is brought into a state of
`intermittent turbulence' within a few ion gyro-periods. Reconnection events
are distributed all over the simulation domain and energy dissipation is rather
volume-filling. Numerous spiral null points interconnected via their spines
form null lines embedded into magnetic flux ropes; null point pairs demonstrate
the signatures of torsional spine reconnection. However, energy dissipation
mainly happens in the shear layers formed by adjacent flux ropes with
oppositely directed currents. In these regions radial null pairs are
spontaneously emerging and vanishing, associated with electron streams and
small-scale current sheets. The number of spiral nulls in the simulation
outweighs the number of radial nulls by a factor of 5\---10, in accordance with
Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with
embedded spiral null points might indicate the regions of major energy
dissipation for future space missions such as Magnetospheric Multiscale Mission
(MMS).
| arxiv topic:astro-ph.EP astro-ph.SR physics.plasm-ph physics.space-ph |
arxiv_dataset-66271509.08061 | Extendability of conformal structures on punctured surfaces
math.DG
For a smooth immersion $f$ from the punctured disk $D\backslash\{0\}$ into
$\mathbb{R}^n$ extendable continuously at the puncture, if its mean curvature
is square integrable and the measure of $f(D)\cap B_{r_k}=o(r_k)$ for a
sequence $r_k\to 0$, we show that the Riemannian surface
$(D_r\backslash\{0\},g)$ where $g$ is the induced metric is conformally
equivalent to the unit Euclidean punctured disk, for any $r\in(0,1)$. For a
locally $W^{2,2}$ Lipschitz immersion $f$ from the punctured disk
$D_2\backslash\{0\}$ into $\mathbb{R}^n$, if $\|\nabla f\|_{L^\infty}$ is
finite and the second fundamental form of $f$ is in $L^2$, we show that there
exists a homeomorphism $\phi:D\to D$ such that $f\circ\phi$ is a branched
$W^{2,2}$-conformal immersion from the Euclidean unit disk $D$ into
$\mathbb{R}^n$.
| arxiv topic:math.DG |
arxiv_dataset-66281509.08161 | Approximately Truthful Multi-Agent Optimization Using Cloud-Enforced
Joint Differential Privacy
math.OC
Multi-agent coordination problems often require agents to exchange state
information in order to reach some collective goal, such as agreement on a
final state value. In some cases, it is feasible that opportunistic agents may
deceptively report false state values for their own benefit, e.g., to claim a
larger portion of shared resources. Motivated by such cases, this paper
presents a multi-agent coordination framework which disincentivizes
opportunistic misreporting of state information. This paper focuses on
multi-agent coordination problems that can be stated as nonlinear programs,
with non-separable constraints coupling the agents. In this setting, an
opportunistic agent may be tempted to skew the problem's constraints in its
favor to reduce its local cost, and this is exactly the behavior we seek to
disincentivize. The framework presented uses a primal-dual approach wherein the
agents compute primal updates and a centralized cloud computer computes dual
updates. All computations performed by the cloud are carried out in a way that
enforces joint differential privacy, which adds noise in order to dilute any
agent's influence upon the value of its cost function in the problem. We show
that this dilution deters agents from intentionally misreporting their states
to the cloud, and present bounds on the possible cost reduction an agent can
attain through misreporting its state. This work extends our earlier work on
incorporating ordinary differential privacy into multi-agent optimization, and
we show that this work can be modified to provide a disincentivize for
misreporting states to the cloud. Numerical results are presented to
demonstrate convergence of the optimization algorithm under joint differential
privacy.
| arxiv topic:math.OC |
arxiv_dataset-66291509.08261 | Leibniz complexity of Nash functions on differentiations
math.AG
The derivatives of Nash functions are Nash functions which are derived
algebraically from their minimal polynomial equations. In this paper we show
that, for any non-Nash analytic function, it is impossible to derive its
derivatives algebraically, i.e., by using linearity and Leibniz rule finite
times. In fact we prove the impossibility of such kind of algebraic
computations, algebraically by using K{\" a}hler differentials. Then the notion
of Leibniz complexity of a Nash function is introduced in this paper, as a
computational complexity on its derivative, by the minimal number of usages of
Leibniz rules to compute the total differential algebraically. We provide
general observations and upper estimates on Leibniz complexity of Nash
functions, related to the binary expansions, the addition chain complexity, the
non-scalar complexity and the complexity of Nash functions in the sense of
Ramanakoraisina.
| arxiv topic:math.AG |
arxiv_dataset-66301509.08361 | Combining allele frequency uncertainty and population substructure
corrections in forensic DNA calculations
stat.AP
In forensic DNA calculations of relatedness of individuals and in DNA mixture
analyses, two sources of uncertainty are present concerning the allele
frequencies used for evaluating genotype probabilities when evaluating
likelihoods. They are: (i) imprecision in the estimates of the allele
frequencies in the population by using an inevitably finite database of DNA
profiles to estimate them; and (ii) the existence of population substructure.
Green and Mortera (2009) showed that these effects may be taken into account
individually using a common Dirichlet model within a Bayesian network
formulation, but that when taken in combination this is not the case; however
they suggested an approximation that could be used. Here we develop a slightly
different approximation that is shown to be exact in the case of a single
individual. We demonstrate the closeness of the approximation numerically using
a published database of allele counts, and illustrate the effect of
incorporating the approximation into calculations of a recently published
statistical model of DNA mixtures.
| arxiv topic:stat.AP |
arxiv_dataset-66311509.08461 | Haldane-Hubbard Mott Insulator: From Tetrahedral Spin Crystal to Chiral
Spin Liquid
cond-mat.str-el cond-mat.quant-gas
Motivated by cold atom experiments on Chern insulators, we study the
honeycomb lattice Haldane-Hubbard Mott insulator of spin-$1/2$ fermions using
exact diagonalization and density matrix renormalization group methods. We show
that this model exhibits various chiral magnetic orders including a wide regime
of triple-Q tetrahedral order. Incorporating third-neighbor hopping frustrates
and ultimately melts this tetrahedral spin crystal. From analyzing low energy
spectra, many-body Chern numbers, entanglement spectra, and modular matrices,
we identify the molten state as a chiral spin liquid (CSL) with gapped semion
excitations. We formulate and study the Chern-Simons-Higgs field theory of the
exotic CSL-to-tetrahedral spin crystallization transition.
| arxiv topic:cond-mat.str-el cond-mat.quant-gas |
arxiv_dataset-66321509.08561 | Efficient Checking of Individual Rewards Properties in Markov Population
Models
cs.LO cs.PF cs.SY
In recent years fluid approaches to the analysis of Markov populations models
have been demonstrated to have great pragmatic value. Initially developed to
estimate the behaviour of the system in terms of the expected values of
population counts, the fluid approach has subsequently been extended to more
sophisticated interrogations of models through its embedding within model
checking procedures. In this paper we extend recent work on checking CSL
properties of individual agents within a Markovian population model, to
consider the checking of properties which incorporate rewards.
| arxiv topic:cs.LO cs.PF cs.SY |
arxiv_dataset-66331509.08661 | Hydrodynamic length-scale selection and effective viscosity in
microswimmer suspensions
cond-mat.soft
A universal characteristic of mesoscale turbulence in active suspensions is
the emergence of a typical vortex length scale, distinctly different from the
scale-invariance of turbulent high-Reynolds number flows. Collective
length-scale selection has been observed in bacterial fluids, endothelial
tissue and active colloides, yet the physical origins of this phenomenon remain
elusive. Here, we systematically derive an effective fourth-order field theory
from a generic microscopic model that allows us to predict the typical vortex
size in microswimmer suspensions. Building on a self-consistent closure
condition, the derivation shows that the vortex length scale is determined by
the competition between local alignment forces and intermediate-range
hydrodynamic interactions. Vortex structures found in simulations of the theory
agree with recent measurements in Bacillus subtilis suspensions. Moreover, our
approach correctly predicts an effective viscosity enhancement (reduction), as
reported experimentally for puller (pusher) microorganisms.
| arxiv topic:cond-mat.soft |
arxiv_dataset-66341509.08761 | Reasoning in Infinitely Valued G-IALCQ
cs.AI cs.LO
Fuzzy Description Logics (FDLs) are logic-based formalisms used to represent
and reason with vague or imprecise knowledge. It has been recently shown that
reasoning in most FDLs using truth values from the interval [0,1] becomes
undecidable in the presence of a negation constructor and general concept
inclusion axioms. One exception to this negative result are FDLs whose
semantics is based on the infinitely valued G\"odel t-norm (G). In this paper,
we extend previous decidability results for G-IALC to deal also with qualified
number restrictions. Our novel approach is based on a combination of the known
crispification technique for finitely valued FDLs and the automata-based
procedure originally developed for reasoning in G-IALC. The proposed approach
combines the advantages of these two methods, while removing their respective
drawbacks.
| arxiv topic:cs.AI cs.LO |
arxiv_dataset-66351509.08861 | A program for branching problems in the representation theory of real
reductive groups
math.RT math-ph math.GR math.HO math.MP
We wish to understand how irreducible representations of a group G behave
when restricted to a subgroup G' (the branching problem). Our primary concern
is with representations of reductive Lie groups, which involve both algebraic
and analytic approaches. We divide branching problems into three stages:
(A) abstract features of the restriction;
(B) branching laws (irreducible decompositions of the restriction); and
(C) construction of symmetry breaking operators on geometric models.
We could expect a simple and detailed study of branching problems in Stages B
and C in the settings that are {\it{a priori}} known to be "nice" in Stage A,
and conversely, new results and methods in Stage C that might open another
fruitful direction of branching problems including Stage A.
The aim of this article is to give new perspectives on the subjects, to
explain the methods based on some recent progress, and to raise some
conjectures and open questions.
| arxiv topic:math.RT math-ph math.GR math.HO math.MP |
arxiv_dataset-66361509.08961 | On systems with quasi-discrete spectrum
math.DS math.FA
In this paper we re-examine the theory of systems with quasi-discrete
spectrum initiated in the 1960's by Abramov, Hahn, and Parry. In the first
part, we give a simpler proof of the Hahn--Parry theorem stating that each
minimal topological system with quasi-discrete spectrum is isomorphic to a
certain affine automorphism system on some compact Abelian group. Next, we show
that a suitable application of Gelfand's theorem renders Abramov's theorem ---
the analogue of the Hahn-Parry theorem for measure-preserving systems --- a
straightforward corollary of the Hahn-Parry result.
In the second part, independent of the first, we present a shortened proof of
the fact that each factor of a totally ergodic system with quasi-discrete
spectrum (a "QDS-system") has again quasi-discrete spectrum and that such
systems have zero entropy. Moreover, we obtain a complete algebraic
classification of the factors of a QDS-system.
In the third part, we apply the results of the second to the (still open)
question whether a Markov quasi-factor of a QDS-system is already a factor of
it. We show that this is true when the system satisfies some algebraic
constraint on the group of quasi-eigenvalues, which is satisfied, e.g., in the
case of the skew shift.
| arxiv topic:math.DS math.FA |
arxiv_dataset-66371509.09061 | Integrability of D1-brane on Group Manifold with Mixed Three Form Flux
hep-th
We consider D1-brane as a natural probe of the group manifold with mixed
three form fluxes. We determine Lax connection for given theory. Then we switch
to the canonical analysis and calculate the Poisson brackets between spatial
components of Lax connections and we argue for integrability of given theory.
| arxiv topic:hep-th |
arxiv_dataset-66381509.09161 | The Lyapunov dimension and its computation for self-excited and hidden
attractors in the Glukhovsky-Dolzhansky fluid convection model
nlin.CD
Consideration of various hydrodynamic phenomena involves the study of the
Navier-Stokes (N-S) equations, what is hard enough for analytical and numerical
investigations since already in three-dimensional (3D) case it is a challenging
task to study the limit behavior of N-S solutions. The low-order models (LOMs)
derived from the initial N-S equations by Galerkin method allow one to overcome
difficulties in studying the limit behavior and existence of attractors. Among
the simple LOMs with chaotic attractors there are famous Lorenz system, which
is an approximate model of two-dimensional convective flow and
Glukhovsky-Dolzhansky model, which describes a convective process in
three-dimensional rotating fluid and can be considered as an approximate model
of the World Ocean. One of the widely used dimensional characteristics of
attractors is the Lyapunov dimension. In the study we follow a rigorous
approach for the definition of the Lyapunov dimension and justification of its
computation by the Kaplan-Yorke formula, without using statistical physics
assumptions. The exact Lyapunov dimension formula for the global attractors is
obtained and peculiarities of the Lyapunov dimension estimation for
self-excited and hidden attractors are discussed. A tutorial on numerical
estimation of the Lyapunov dimension on the example of the
Glukhovsky-Dolzhansky model is presented.
| arxiv topic:nlin.CD |
arxiv_dataset-66391509.09261 | Polar decomposition of scale-homogeneous measures with application to
L\'evy measures of strictly stable laws
math.PR
A scaling on some space is a measurable action of the group of positive real
numbers. A measure on a measurable space equipped with a scaling is said to be
$\alpha$-homogeneous for some nonzero real number $\alpha$ if the mass of any
measurable set scaled by any factor $t > 0$ is the multiple $t^{-\alpha}$ of
the set's original mass. It is shown rather generally that given an
$\alpha$-homogeneous measure on a measurable space there is a measurable
bijection between the space and the Cartesian product of a subset of the space
and the positive real numbers (that is, a "system of polar coordinates") such
that the push-forward of the $\alpha$-homogeneous measure by this bijection is
the product of a probability measure on the first component (that is, on the
"angular" component) and an $\alpha$-homogeneous measure on the positive
half-line (that is, on the "radial" component). This result is applied to the
intensity measures of Poisson processes that arise in
L\'evy-Khinchin-It\^o-like representations of infinitely divisible random
elements. It is established that if a strictly stable random element in a
convex cone admits a series representation as the sum of points of a Poisson
process, then it necessarily has a LePage representation as the sum of i.i.d.
random elements of the cone scaled by the successive points of an independent
unit intensity Poisson process on the positive half-line each raised to the
power $-\frac{1}{\alpha}$.
| arxiv topic:math.PR |
arxiv_dataset-66401510.00043 | Parabolic and near-parabolic renormalizations for local degree three
math.DS
The invariant class under parabolic and near-parabolic renormalizations
constructed by Inou and Shishikura has been proved to be extremely useful in
recent years. It leads to several important progresses on the dynamics of
certain holomorphic maps with critical points of local degree two. In this
paper, we construct a new class consisting of holomorphic maps with critical
points of local degree three which is invariant under parabolic and
near-parabolic renormalizations. As potential applications, some results of
cubic unicritical polynomials can be obtained similarly as the quadratic case.
For example, the existence of cubic unicritical Julia sets with positive area,
the characterizations of the topology and geometry of cubic irrationally
indifferent attractors etc.
| arxiv topic:math.DS |
arxiv_dataset-66411510.00143 | Fast Single Image Super-Resolution
cs.CV
This paper addresses the problem of single image super-resolution (SR), which
consists of recovering a high resolution image from its blurred, decimated and
noisy version. The existing algorithms for single image SR use different
strategies to handle the decimation and blurring operators. In addition to the
traditional first-order gradient methods, recent techniques investigate
splitting-based methods dividing the SR problem into up-sampling and
deconvolution steps that can be easily solved. Instead of following this
splitting strategy, we propose to deal with the decimation and blurring
operators simultaneously by taking advantage of their particular properties in
the frequency domain, leading to a new fast SR approach. Specifically, an
analytical solution can be obtained and implemented efficiently for the
Gaussian prior or any other regularization that can be formulated into an
$\ell_2$-regularized quadratic model, i.e., an $\ell_2$-$\ell_2$ optimization
problem. Furthermore, the flexibility of the proposed SR scheme is shown
through the use of various priors/regularizations, ranging from generic image
priors to learning-based approaches. In the case of non-Gaussian priors, we
show how the analytical solution derived from the Gaussian case can be embedded
intotraditional splitting frameworks, allowing the computation cost of existing
algorithms to be decreased significantly. Simulation results conducted on
several images with different priors illustrate the effectiveness of our fast
SR approach compared with the existing techniques.
| arxiv topic:cs.CV |
arxiv_dataset-66421510.00243 | Exotic see-saw mechanism for neutrinos and leptogenesis in a Pati-Salam
model
hep-ph
We discuss non-perturbative corrections to the neutrino sector, in the
context of a D-brane Pati-Salam-like model, that can be obtained as a simple
alternative to $SO(10)$ GUT's in theories with open and unoriented strings. In
such D-brane models, exotic stringy instantons can correct the right-handed
neutrino mass matrix in a calculable way, thus affecting mass hierarchies and
modifying the see-saw mechanism to what we name exotic see-saw. For a wide
range of parameters, a compact spectrum of right-handed neutrino masses can
occur that gives rise to a predictive scenario for low energy observables. This
model also provides a viable mechanism for Baryon Asymmetry in the Universe
(BAU) through leptogenesis. Finally, a Majorana mass for the neutron is
naturally predicted in the model, leading to potentially testable
neutron-antineutron oscillations. Combined measurements in neutrino and
neutron-antineutron sectors could provide precious informations on physics at
the quantum gravity scale.
| arxiv topic:hep-ph |
arxiv_dataset-66431510.00343 | OPERA neutrino oscillation search: status and perspectives
hep-ex nucl-ex physics.ins-det
OPERA is a long-baseline experiment at the Gran Sasso laboratory (LNGS)
designed to search for $\nu_\mu \rightarrow \nu_\tau$ oscillations in
appearance mode. OPERA took data from 2008 to 2012 with the CNGS neutrino beam
from CERN. The data analysis is ongoing, with the goal of establishing
$\nu_\tau$ appearance with high significance and improving the sensitivity to
the sterile neutrino search in the $\nu_\mu$ $\rightarrow$ $\nu_e$ appearance
channel. Current results will be presented and perspectives discussed.
| arxiv topic:hep-ex nucl-ex physics.ins-det |
arxiv_dataset-66441510.00443 | The zero-inflated promotion cure rate regression model applied to fraud
propensity in bank loan applications
stat.ME
In this paper we extend the promotion cure rate model proposed by Chen et al
(1999), by incorporating excess of zeros in the modelling. Despite allowing to
relate the covariates to the fraction of cure, the current approach, which is
based on a biological interpretation of the causes that trigger the event of
interest, does not enable to relate the covariates to the fraction of zeros.
The presence of zeros in survival data, unusual in medical studies, can
frequently occur in banking loan portfolios, as presented in Louzada et al
(2015), where they deal with propensity to fraud in lending loans in a major
Brazilian bank. To illustrate the new cure rate survival method, the same real
dataset analyzed in Louzada et al (2015) is fitted here, and the results are
compared.
| arxiv topic:stat.ME |
arxiv_dataset-66451510.00543 | Weak measurements and the joint estimation of phase and phase diffusion
quant-ph
Weak measurements offer the possibility of tuning the information acquired on
a system, hence the imposed disturbance. This suggests that it could be a
useful tool for multi-parameter estimation, when two parameters can not be
measured simultaneously at the quantum limit. Here we discuss their use for
phase estimation in the presence of phase diffusion in the context of
polarimetry, a scenario which is conveniently cast in terms of a two-level
quantum system in many relevant cases.
| arxiv topic:quant-ph |
arxiv_dataset-66461510.00643 | Computing the dielectric constant of liquid water at constant dielectric
displacement
physics.chem-ph cond-mat.soft
The static dielectric constant of liquid water is computed using classical
force field based molecular dynamics simulation at fixed electric displacement
D. The method to constrain the electric displacement is the finite temperature
classical variant of the constant-D method developed by Stengel, Spaldin and
Vanderbilt (Nat. Phys. 2009, 5: 304). There is also a modification of this
scheme imposing fixed values of the macroscopic field E. The method is applied
to the popular SPC/E model of liquid water. We compare four different estimates
of the dielectric constant, two obtained from fluctuations of the polarization
at D = 0 and E = 0 and two from the variation of polarization with finite D and
E. It is found that all four estimates agree when properly converged. The
computational effort to achieve convergence varies however, with constant D
calculations being substantially more efficient. We attribute this difference
to the much shorter relaxation time of longitudinal polarization compared to
transverse polarization accelerating constant D calculations.
| arxiv topic:physics.chem-ph cond-mat.soft |
arxiv_dataset-66471510.00743 | Combinatorics of the gaps between primes
math.NT
A few years ago we identified a recursion that works directly with the gaps
among the generators in each stage of Eratosthenes sieve. This recursion
provides explicit enumerations of sequences of gaps among the generators, which
sequences are known as constellations. The populations of gaps and
constellations across stages of Eratosthenes sieve are modeled exactly by
discrete dynamic systems. These models and their asymptotic behaviors provide
evidence on a number of open problems regarding gaps between prime numbers. For
Eratosthenes sieve we show that the analogue of Polignac's conjecture is true:
every gap $g=2k$ does occur in the sieve, and its asymptotic population
supports the estimates made in Hardy and Littlewood's Conjecture B. A stronger
form of Polignac's conjecture also holds for the sieve: for any gap $g=2k$,
every feasible constellation $g,g,\ldots,g$ occurs; these constellations
correspond to consecutive primes in arithmetic progression. The models also
provide evidence toward resolving a series of questions posed by Erd\"os and
Tur\'an.
| arxiv topic:math.NT |
arxiv_dataset-66481510.00843 | The Bruss-Robertson Inequality: Elaborations, Extensions, and
Applications
math.PR
The Bruss-Robertson inequality gives a bound on the maximal number of
elements of a random sample whose sum is less than a specified value, and the
extension of that inequality which is given here neither requires the
independence of the summands nor requires the equality of their marginal
distributions. A review is also given of the applications of the
Bruss-Robertson inequality, especially the applications to problems of
combinatorial optimization such as the sequential knapsack problem and the
sequential monotone subsequence selection problem.
| arxiv topic:math.PR |
arxiv_dataset-66491510.00943 | Bessel periods and the non-vanishing of Yoshida lifts modulo a prime
math.NT
We give an explicit construction of vector-valued Yoshida lifts and derive a
formula of the Bessel periods of Yoshida lifts, by which we prove the
non-vanishing modulo a prime of Yoshida lifts attached to a pair of elliptic
modular newforms. As a consequence, we obtain a new proof of the non-vanishing
of Yoshida lifts.
| arxiv topic:math.NT |
arxiv_dataset-66501510.01043 | Extremal conformal structures on projective surfaces
math.DG math.AP math.GT
We introduce a new functional $\mathcal{E}_{\mathfrak{p}}$ on the space of
conformal structures on an oriented projective manifold $(M,\mathfrak{p})$. The
nonnegative quantity $\mathcal{E}_{\mathfrak{p}}([g])$ measures how much
$\mathfrak{p}$ deviates from being defined by a $[g]$-conformal connection. In
the case of a projective surface $(\Sigma,\mathfrak{p})$, we canonically
construct an indefinite K\"ahler--Einstein structure
$(h_{\mathfrak{p}},\Omega_{\mathfrak{p}})$ on the total space $Y$ of a fibre
bundle over $\Sigma$ and show that a conformal structure $[g]$ is a critical
point for $\mathcal{E}_{\mathfrak{p}}$ if and only if a certain lift
$\widetilde{[g]} : (\Sigma,[g]) \to (Y,h_{\mathfrak{p}})$ is weakly conformal.
In fact, in the compact case $\mathcal{E}_{\mathfrak{p}}([g])$ is -- up to a
topological constant -- just the Dirichlet energy of $\widetilde{[g]}$. As an
application, we prove a novel characterisation of properly convex projective
structures among all flat projective structures. As a by-product, we obtain a
Gauss--Bonnet type identity for oriented projective surfaces.
| arxiv topic:math.DG math.AP math.GT |
arxiv_dataset-66511510.01143 | Photocurrents in a Single InAs Nanowire/ Silicon Heterojunction
cond-mat.mes-hall
We investigate the optoelectronic properties of single indium arsenide
nanowires, which are grown vertically on p-doped silicon substrates. We apply a
scanning photocurrent microscopy to study the optoelectronic properties of the
single heterojunctions. The measured photocurrent characteristics are
consistent with an excess charge carrier transport through mid-gap trap states,
which form at the Si/InAs heterojunctions. Namely, the trap states add an
additional transport path across a heterojunction, and the charge of the
defects changes the band bending at the junction. The bending gives rise to a
photovoltaic effect at a small bias voltage. In addition, we observe a
photoconductance effect within the InAs nanowires at large biases.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-66521510.01243 | Mechanics of Cosserat media: II. relativistic theory
math-ph gr-qc math.MP
The derivation of the non-relativistic Cosserat equations that was described
in Part I of this series of papers is extended from the group of rigid motions
in three-dimensional Euclidian space to the Poincar\'e group of
four-dimensional Minkowski space. Examples of relativistic Cosserat media are
then given in the form of the free Dirac electron and the Weyssenhoff fluid.
| arxiv topic:math-ph gr-qc math.MP |
arxiv_dataset-66531510.01343 | Parametrizing an integer linear program by an integer
math.CO
We consider a family of integer linear programs in which the coefficients of
the constraints and objective function are polynomials of an integer parameter
$t.$ For $\ell$ in $\mathbb{Z}_+,$ we define $f_\ell(t)$ to be the
$\ell^{\text{th}}$ largest value of the objective function with multiplicity
for the integer linear program at $t.$ We prove that for all $\ell,$ $f_\ell$
is eventually quasi-polynomial; that is, there exists $d$ and polynomials $P_0,
\ldots, P_{d-1}$ such that for sufficiently large $t,$ $f_\ell(t)=P_{d
\pmod{t}}(t).$ Closely related to finding the $\ell^{\text{th}}$ largest value
is describing the vertices of the convex hull of the feasible set. Calegari and
Walker showed that if $R(t)$ is the convex hull of $\mathbf{v_1}(t), \ldots,
\mathbf{v_k}(t)$ where $\mathbf{v_i}$ is a vector whose coordinates are in
$\mathbb{Q}(u)$ and of size $O(u),$ then the vertices of the convex hull of the
set of lattice points in $R(t)$ has eventually quasi-polynomial structure. We
prove this without the $O(u)$ assumption.
| arxiv topic:math.CO |
arxiv_dataset-66541510.01443 | A Waveform Representation Framework for High-quality Statistical
Parametric Speech Synthesis
cs.SD cs.LG
State-of-the-art statistical parametric speech synthesis (SPSS) generally
uses a vocoder to represent speech signals and parameterize them into features
for subsequent modeling. Magnitude spectrum has been a dominant feature over
the years. Although perceptual studies have shown that phase spectrum is
essential to the quality of synthesized speech, it is often ignored by using a
minimum phase filter during synthesis and the speech quality suffers. To bypass
this bottleneck in vocoded speech, this paper proposes a phase-embedded
waveform representation framework and establishes a magnitude-phase joint
modeling platform for high-quality SPSS. Our experiments on waveform
reconstruction show that the performance is better than that of the widely-used
STRAIGHT. Furthermore, the proposed modeling and synthesis platform outperforms
a leading-edge, vocoded, deep bidirectional long short-term memory recurrent
neural network (DBLSTM-RNN)-based baseline system in various objective
evaluation metrics conducted.
| arxiv topic:cs.SD cs.LG |
arxiv_dataset-66551510.01543 | Density-functional Monte-Carlo simulation of CuZn order-disorder
transition
cond-mat.stat-mech cond-mat.mtrl-sci
We perform a Wang-Landau Monte Carlo simulation of a Cu0.5Zn0.5
order-disorder transition using 250 atoms and pairwise atom swaps inside a 5 x
5 x 5 BCC supercell. Each time step uses energies calculated from density
functional theory (DFT) via the all-electron Korringa-Kohn- Rostoker method and
self-consistent potentials. Here we find CuZn undergoes a transition from a
disordered A2 to an ordered B2 structure, as observed in experiment. Our
calculated transition temperature is near 870 K, comparing favorably to the
known experimental peak at 750 K. We also plot the entropy, temperature,
specific-heat, and short-range order as a function of internal energy.
| arxiv topic:cond-mat.stat-mech cond-mat.mtrl-sci |
arxiv_dataset-66561510.01643 | On time regularity of stochastic evolution equations with monotone
coefficients
math.AP
We report on a time regularity result for stochastic evolutionary PDEs with
monotone coefficients. If the diffusion coefficient is bounded in time without
additional space regularity we obtain a fractional Sobolev type time regularity
of order up to $\tfrac{1}{2}$ for a certain functional $ G( u )$ of the
solution. Namely, $ G( u )=\nabla u $ in the case of the heat equation and $G(
u )=|\nabla u |^{\frac{p-2}{2}}\nabla u $ for the $p$-Laplacian. The motivation
is twofold. On the one hand, it turns out that this is the natural time
regularity result that allows to establish the optimal rates of convergence for
numerical schemes based on a time discretization. On the other hand, in the
linear case, i.e. where the solution is given by a stochastic convolution, our
result complements the known stochastic maximal space-time regularity results
for the borderline case not covered by other methods.
| arxiv topic:math.AP |
arxiv_dataset-66571510.01743 | Testing noncontextuality inequalities that are building blocks of
quantum correlations
quant-ph
Measurement scenarios containing events with relations of exclusivity
represented by pentagons, heptagons, nonagons, etc., or their complements are
the only ones in which quantum probabilities cannot be described classically.
Interestingly, quantum theory predicts that the maximum values for any of these
graphs cannot be achieved in Bell inequality scenarios. With the exception of
the pentagon, this prediction remained experimentally unexplored. Here we test
the quantum maxima for the heptagon and the complement of the heptagon using
three- and five-dimensional quantum states, respectively. In both cases, we
adopt two different encodings: linear transverse momentum and orbital angular
momentum of single photons. Our results exclude maximally noncontextual
hidden-variable theories and are in good agreement with the maxima predicted by
quantum theory.
| arxiv topic:quant-ph |
arxiv_dataset-66581510.01843 | Meridional circulation in the solar convection zone: time-distance
helioseismic inferences from four years of HMI/SDO observations
astro-ph.SR
We present and discuss results from time-distance helioseismic measurements
of meridional circulation in the solar convection zone using 4 years of Doppler
velocity observations by the Helioseismic and Magnetic Imager (HMI) onboard the
Solar Dynamics Observatory (SDO). Using an in-built mass conservation
constraint in terms of the stream function we invert helioseismic travel times
to infer meridional circulation in the solar convection zone. We find that the
return flow that closes the meridional circulation is possibly beneath the
depth of $0.77 R_{\odot}$. We discuss the significance of this result in
relation to other helioseismic inferences published recently and possible
reasons for the differences in the results. Our results show clearly the
pitfalls involved in the measurements of material flows in the deep solar
interior given the current limits on signal-to-noise and our limited
understanding of systematics in the data. We also discuss the implications of
our results for the dynamics of solar interior and popular solar dynamo models.
| arxiv topic:astro-ph.SR |
arxiv_dataset-66591510.01943 | Measurements of inclusive jet and dijet cross sections at the Large
Hadron Collider
hep-ex
This review discusses the measurements of the inclusive jet and dijet cross
section performed by the experimental collaborations at the LHC during what is
now being called LHC Run 1 (2009 - 2013). It summarises some of the
experimental challenges and the techniques used in the measurements of jets
cross sections during the LHC Run 1.
| arxiv topic:hep-ex |
arxiv_dataset-66601510.02043 | Offshore wind energy climate projection using UPSCALE climate data under
the RCP8.5 emission scenario
physics.ao-ph physics.geo-ph
Recently it was demonstrated how climate data can be utilized to estimate
regional wind power densities. In particular it was shown that the quality of
the global scale estimate compared well with regional high resolution studies
and a link between surface temperature and moist density in the estimate was
presented. In the present paper the methodology is tested further, to ensure
that the results using one climate data set are reliable. This is achieved by
extending the study to include four ensemble members. With the confidence that
one instantiation is sufficient a climate change data set, which was also a
result of the UPSCALE experiment, is analyzed. This, for the first time,
provides a projection of future changes in wind power resources using this data
set. This climate change data set is based on the Representative Concentration
Pathways (RCP) 8.5 climate change scenario. This provides guidance for
developers and policy makers to mitigate and adapt.
| arxiv topic:physics.ao-ph physics.geo-ph |
arxiv_dataset-66611510.02143 | On the characteristic polynomial of a supertropical adjoint matrix
math.CO
Let $\chi(A)$ denote the characteristic polynomial of a matrix $A$ over a
field; a standard result of linear algebra states that $\chi(A^{-1})$ is the
reciprocal polynomial of $\chi(A)$. More formally, the condition $\chi^n(X)
\chi^k(X^{-1})=\chi^{n-k}(X)$ holds for any invertible $n\times n$ matrix $X$
over a field, where $\chi^i(X)$ denotes the coefficient of $\lambda^{n-i}$ in
the characteristic polynomial $\det(\lambda I-X)$. We confirm a recent
conjecture of Niv by proving the tropical analogue of this result.
| arxiv topic:math.CO |
arxiv_dataset-66621510.02243 | Homogenization of stratified elastic media with high contrast
math.AP
We determine the asymptotic behavior of the solutions to the linear
elastodynamic equations in a stratified medium comprising an alternation of
possibly very stiff layers with much softer ones, when the thickness of the
layers tends to zero. The limit equations may depend on higher order terms,
characterizing bending effects. A part of this work is set in the context of
non-periodic homogenization and an extension to stochastic homogenization is
presented.
| arxiv topic:math.AP |
arxiv_dataset-66631510.02343 | Bipartite Network Model for Inferring Hidden Ties in Crime Data
cs.SI physics.soc-ph
Certain crimes are hardly committed by individuals but carefully organised by
group of associates and affiliates loosely connected to each other with a
single or small group of individuals coordinating the overall actions. A common
starting point in understanding the structural organisation of criminal groups
is to identify the criminals and their associates. Situations arise in many
criminal datasets where there is no direct connection among the criminals. In
this paper, we investigate ties and community structure in crime data in order
to understand the operations of both traditional and cyber criminals, as well
as to predict the existence of organised criminal networks. Our contributions
are twofold: we propose a bipartite network model for inferring hidden ties
between actors who initiated an illegal interaction and objects affected by the
interaction, we then validate the method in two case studies on pharmaceutical
crime and underground forum data using standard network algorithms for
structural and community analysis. The vertex level metrics and community
analysis results obtained indicate the significance of our work in
understanding the operations and structure of organised criminal networks which
were not immediately obvious in the data. Identifying these groups and mapping
their relationship to one another is essential in making more effective
disruption strategies in the future.
| arxiv topic:cs.SI physics.soc-ph |
arxiv_dataset-66641510.02443 | Entanglement as a resource for local state discrimination in
multipartite systems
quant-ph
We explore the question of using an entangled state as a universal resource
for implementing quantum measurements by local operations and classical
communication (LOCC). We show that for most systems consisting of three or more
subsystems, there is no entangled state from the same space that can enable all
measurements by LOCC. This is in direct contrast to the bipartite case, where a
maximally entangled state is an universal resource. Our results are obtained
showing an equivalence between the problem of local state transformation and
that of entanglement-assisted local unambiguous state discrimination.
| arxiv topic:quant-ph |
arxiv_dataset-66651510.02543 | On the Interactive-Beating-Modes Model: Generation of Asymmetric
Multiplet Structures and Explanation of the Blazhko Effect
astro-ph.SR
This paper considers a nonlinear coupling between a radial and a nonradial
mode of nearly the same frequency. The results may be of general interest, but
in particular have application to the "beating-modes model" of the Blazhko
effect which was recently shown to accurately reproduce the light curve of RR
Lyr. For weak coupling, the two modes do not phase-lock and they retain
separate frequencies, but the coupling nevertheless has important consequences.
Upon increasing the coupling strength from zero, an additional side-peak
emerges in the spectrum forming an asymmetric triplet centered on the
fundamental. As the coupling is further increased, the amplitude of this
side-peak increases and the three peaks are also pulled towards each other,
decreasing the Blazhko frequency. Beyond a critical coupling strength,
phase-locking occurs between the modes. With appropriate choice of coupling
strength, this "interactive beating-modes model" can match the side-peak
amplitude ratio of any star. The effects of nonlinear damping are also explored
and found to generate additional side-peaks of odd order. Consistent with this,
the odd side-peaks are found to be favored in V808 Cyg. It is also shown that
the Blazhko effect generates a fluctuating "environment" that can have a
modulatory effect on other excited modes of the star. An example is found in
V808 Cyg where the modulation is at double the Blazhko frequency. An
explanation is found for this mysterious doubling, providing additional
evidence in favor of the model.
| arxiv topic:astro-ph.SR |
arxiv_dataset-66661510.02643 | Representations of bicircular lift matroids
math.CO
Bicircular lift matroids are a class of matroids defined on the edge set of a
graph. For a given graph $G$, the circuits of its bicircular lift matroid are
the edge sets of those subgraphs of $G$ that contain at least two cycles, and
are minimal with respect to this property. The main result of this paper is a
characterization of when two graphs give rise to the same bicircular lift
matoid, which answers a question proposed by Irene Pivotto. In particular,
aside from some appropriately defined "small" graphs, two graphs have the same
bicircular lift matroid if and only if they are $2$-isomorphic in the sense of
Whitney.
| arxiv topic:math.CO |
arxiv_dataset-66671510.02743 | Simulating Dense Small Cell Networks
cs.NI
Through massive deployment of additional small cell infrastructure, Dense
Small cell Networks (DSNs) are expected to help meet the foreseen increase in
traffic demand on cellular networks. Performance assessment of architectural
and protocol solutions tailored to DSNs will require system and network level
simulators that can appropriately model the complex interference environment
found in those networks. This paper identifies the main features of DSN
simulators, and guides the reader in the selection of an appropriate simulator
for their desired investigations. We extend our discussion with a comparison of
representative DSN simulators.
| arxiv topic:cs.NI |
arxiv_dataset-66681510.02843 | Atom Probe Tomography Spatial Reconstruction: Status and Directions
cond-mat.mtrl-sci
In this review we present an overview of the current atom probe tomography
spatial data reconstruction paradigm, and explore some of potential routes to
improve the current methodology in order to yield a more accurate
representation of nanoscale microstructure. Many of these potential improvement
methods are directly tied to extensive application of advanced numerical
methods, which are also very briefly reviewed. We have described effects
resulting from the application of the standard model and then introduced
several potential improvements, first in the far field, and, second, in the
near field. The issues encountered in both cases are quite different but
ultimately they combine to determine the spatial resolution of the technique.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-66691510.02943 | Defining the Free-Energy Landscape of Curvature-Inducing Proteins on
Membrane Bilayers
physics.bio-ph cond-mat.soft cond-mat.stat-mech
Curvature-sensing and curvature-remodeling proteins are known to reshape cell
membranes, and this remodeling event is essential for key biophysical processes
such as tubulation, exocytosis, and endocytosis. Curvature-inducing proteins
can act as curvature sensors as well as induce curvature in cell membranes to
stabilize emergent high curvature, non-spherical, structures such as tubules,
discs, and caveolae. A definitive understanding of the interplay between
protein recruitment and migration, the evolution of membrane curvature, and
membrane morphological transitions is emerging but remains incomplete. Here,
within a continuum framework and using the machinery of Monte Carlo
simulations, we introduce and compare three free-energy methods to delineate
the free-energy landscape of curvature-inducing proteins on bilayer membranes.
We demonstrate the utility of the Widom test-particle/field insertion
methodology in computing the excess chemical potentials associated with
curvature-inducing proteins on the membrane-- in particular, we use this method
to track the onset of morphological transitions in the membrane at elevated
protein densities. We validate this approach by comparing the results from the
Widom method with those of thermodynamic integration and Bennett acceptance
ratio methods. Furthermore, the predictions from the Widom method have been
tested against analytical calculations of the excess chemical potential at
infinite dilution. Our results are useful in precisely quantifying the
free-energy landscape, and also in determining the phase boundaries associated
with curvature-induction, curvature-sensing, and morphological transitions.
This approach can be extended to studies exploring the role of thermal
fluctuations and other external (control) variables, such as membrane excess
area, in shaping curvature-mediated interactions on bilayer membranes.
| arxiv topic:physics.bio-ph cond-mat.soft cond-mat.stat-mech |
arxiv_dataset-66701510.03043 | The Yang-Baxter relation and gauge invariance
math-ph math.MP
Starting from a quantum dilogarithm over a Pontryagin self-dual LCA group
$A$, we construct an operator solution of the Yang-Baxter equation generalizing
the solution of the Faddeev-Volkov model. Based on a specific choice of a
subgroup $B\subset A$ and by using the Weil transformation, we also give a new
non-operator interpretation of the Yang-Baxter relation. That allows us to
construct a lattice QFT-model of IRF-type with gauge invariance under
independent $B$-translations of local `spin' variables.
| arxiv topic:math-ph math.MP |
arxiv_dataset-66711510.03143 | Gauge Mediation in the NMSSM with a Light Singlet: Sparticles within the
Reach of LHC Run II
hep-ph
Relatively light stops in gauge mediation models are usually made compatible
with the Higgs mass of 125 GeV by introducing direct Higgs-messenger couplings.
We show that such couplings are not necessary in a simple and predictive model
that combines minimal gauge mediation and the next-to-minimal supersymmetric
standard model (NMSSM). We show that one can obtain a 125 GeV Standard
Model-like Higgs boson with stops as light as 1.1 TeV, thanks to the mixing of
the Higgs with a singlet state at ${\cal O}(90-100)$ GeV that can explain the
LEP excess. In this scenario the singlet-higgs-higgs superfields coupling
$\lambda$ is small and $\tan\beta$ large. Sparticle searches at the LHC may
come with additional $b-$jets or taus and may involve displaced vertices. The
sparticle production cross-section at the 13 TeV LHC can be ${\mathcal
O}(10-100)$ fb, leading to great prospects for discovery in the early phase of
LHC Run II.
| arxiv topic:hep-ph |
arxiv_dataset-66721510.03243 | The NLS limit for bosons in a quantum waveguide
math-ph math.MP
We consider a system of $N$ bosons confined to a thin waveguide, i.e.\ to a
region of space within an $\varepsilon$-tube around a curve in $\mathbb{R}^3$.
We show that when taking simultaneously the NLS limit $N\to \infty$ and the
limit of strong confinement $\varepsilon\to 0$, the time-evolution of such a
system starting in a state close to a Bose-Einstein condensate is approximately
captured by a non-linear Schr\"odinger equation in one dimension. The strength
of the non-linearity in this Gross-Pitaevskii type equation depends on the
shape of the cross-section of the waveguide, while the "bending" and the
"twisting" of the waveguide contribute potential terms. Our analysis is based
on an approach to mean-field limits developed by Pickl.
| arxiv topic:math-ph math.MP |
arxiv_dataset-66731510.03343 | Plasma Instabilities in the Context of Current Helium Sedimentation
Models: Dynamical Implications for the ICM in Galaxy Clusters
astro-ph.CO
Understanding whether Helium can sediment to the core of galaxy clusters is
important for a number of problems in cosmology and astrophysics. All current
models addressing this question are one-dimensional and do not account for the
fact that magnetic fields can effectively channel ions and electrons, leading
to anisotropic transport of momentum, heat, and particle diffusion in the
weakly collisional intracluster medium (ICM). This anisotropy can lead to a
wide variety of instabilities, which could be relevant for understanding the
dynamics of heterogeneous media. In this paper, we consider the radial
temperature and composition profiles as obtained from a state-of-the-art Helium
sedimentation model and analyze its stability properties. We find that the
associated radial profiles are unstable, to different kinds of instabilities
depending on the magnetic field orientation, at all radii. The fastest growing
modes are usually related to generalizations of the Magnetothermal Instability
(MTI) and the Heat-flux-driven Buoyancy Instability (HBI) which operate in
heterogeneous media. We find that the effect of sedimentation is to increase
(decrease) the predicted growth rates in the inner (outer) cluster region. The
unstable modes grow fast compared to the sedimentation timescale. This suggests
that the composition gradients as inferred from sedimentation models, which do
not fully account for the anisotropic character of the weakly collisional
environment, might not be very robust. Our results emphasize the subtleties
involved in understanding the gas dynamics of the ICM and argue for the need of
a comprehensive approach to address the issue of Helium sedimentation beyond
current models.
| arxiv topic:astro-ph.CO |
arxiv_dataset-66741510.03443 | Pushing Higgs Effective Theory to its Limits
hep-ph
At the LHC, an effective theory of the Higgs sector allows us to analyze
kinematic distributions in addition to inclusive rates, although there is no
clear hierarchy of scales. We systematically analyze how well dimension-6
operators describe LHC observables in comparison to the full theory, and in a
range where the LHC will be sensitive. The key question is how the breakdown of
the dimension-6 description affects Higgs measurements during the upcoming LHC
run for weakly interacting models. We cover modified Higgs sectors with a
singlet and doublet extension, new top partners, and a vector triplet. First,
weakly interacting models only generate small relevant subsets of dimension-6
operators. Second, the dimension-6 description tends to be justified at the
LHC. Scanning over model parameters, significant discrepancies can nevertheless
arise; their main source is the matching procedure in the absence of a
well-defined hierarchy of scales. This purely theoretical problem should not
affect future LHC analyses.
| arxiv topic:hep-ph |
arxiv_dataset-66751510.03543 | On the limiting absorption principle for a new class of schroedinger
hamiltonians
math-ph math.AP math.MP math.SP
We prove the limiting absorption principle and discuss the continuity
properties of the boundary values of the resolvent for a class of form bounded
perturbations of the Euclidean Laplacian $\Delta$ that covers both short and
long range potentials with an essentially optimal behaviour at infinity.
| arxiv topic:math-ph math.AP math.MP math.SP |
arxiv_dataset-66761510.03643 | Smooth long-time existence of Harmonic Ricci Flow on surfaces
math.DG math.AP
We prove that at a finite singular time for the Harmonic Ricci Flow on a
surface of positive genus both the energy density of the map component and the
curvature of the domain manifold have to blow up simultaneously. As an
immediate consequence, we obtain smooth long-time existence for the Harmonic
Ricci Flow with large coupling constant.
| arxiv topic:math.DG math.AP |
arxiv_dataset-66771510.03743 | Wide-Area Image Geolocalization with Aerial Reference Imagery
cs.CV
We propose to use deep convolutional neural networks to address the problem
of cross-view image geolocalization, in which the geolocation of a ground-level
query image is estimated by matching to georeferenced aerial images. We use
state-of-the-art feature representations for ground-level images and introduce
a cross-view training approach for learning a joint semantic feature
representation for aerial images. We also propose a network architecture that
fuses features extracted from aerial images at multiple spatial scales. To
support training these networks, we introduce a massive database that contains
pairs of aerial and ground-level images from across the United States. Our
methods significantly out-perform the state of the art on two benchmark
datasets. We also show, qualitatively, that the proposed feature
representations are discriminative at both local and continental spatial
scales.
| arxiv topic:cs.CV |
arxiv_dataset-66781510.03843 | Dirac canonical idea as an alternative to the approach of Bohr. A toy
model
quant-ph physics.hist-ph
Classical objects have been excluded as subjects of the observed quantum
properties, and the related problem of quantum objects nature has been
suspended since the early days of Quantum Theory. Recent experiments show that
the problem could be reasonably revisited. The outlined model indicates new
issues, which could result from following and exploring the canonical idea of
Dirac. Topological defects in solids are considered as an example. The aim is
helping to grasp the underlying pre-theoretical new intuitions, which should
replace the old ones attached to the background of classical physics.
| arxiv topic:quant-ph physics.hist-ph |
arxiv_dataset-66791510.03943 | Constrained percolation in two dimensions
math.PR
We prove absence of infinite clusters and contours in a class of critical
constrained percolation models on the square lattice. The percolation
configuration is assumed to satisfy certain hard local constraints, but only
weak symmetry and ergodicity conditions are imposed on its law. The proofs use
new combinatorial techniques exploiting planar duality.
Applications include absence of infinite clusters of diagonal edges for
critical dimer models on the square-octagon lattice, as well as absence of
infinite contours and infinite clusters for critical XOR Ising models on the
square grid. We also prove that there exists at most one infinite contour for
high-temperature XOR Ising models, and no infinite contour for low-temperature
XOR Ising model.
| arxiv topic:math.PR |
arxiv_dataset-66801510.04043 | Entropy of Bernoulli convolutions and uniform exponential growth for
linear groups
math.CA math.GR math.PR
The exponential growth rate of non polynomially growing subgroups of $GL_d$
is conjectured to admit a uniform lower bound. This is known for non-amenable
subgroups, while for amenable subgroups it is known to imply the Lehmer
conjecture from number theory. In this note, we show that it is equivalent to
the Lehmer conjecture. This is done by establishing a lower bound for the
entropy of the random walk on the semigroup generated by the maps $x\mapsto
\lambda\cdot x\pm 1$, where $\lambda$ is an algebraic number. We give a bound
in terms of the Mahler measure of $\lambda$. We also derive a bound on the
dimension of Bernoulli convolutions.
| arxiv topic:math.CA math.GR math.PR |
arxiv_dataset-66811510.04143 | Systems engineering of optimal control I. Synthesis of the structure of
the technological product conversion system (part1)
math.OC
Study of current controlled systems and scientific publications has shown
that the architecture of controlled systems, related to the products conversion
is based on the principle of austerity and, in general, does not provide the
possibility of implementing a full parametric optimization. The paper proposes
to develop a controlled conversion system from highly specialized systems, each
of which performs only one function. The conversion system has the ability of
independent conversion process rate control, and finished products are
transferred to the buffering system, which provides release of finished
products with specified consumer properties and in the required volume to the
consumption system. Herewith, the maximum number of degrees of freedom, which
is a prerequisite for the implementation of the full parametric optimization is
ensured. The product conversion system structure was synthesized based on the
liquid portion heating system is synthesized. The system is presented in the
form of interconnected simple mechanisms. It is experimentally found that
systems with continuous feed - release of raw product are a special case of
fully controllable systems with the architecture that provides the optimal
control possibility. The developed models were tested and examined in specially
designed free software constructor EFFLI. Link to the current model of the
controlled system is available in the text.
| arxiv topic:math.OC |
arxiv_dataset-66821510.04243 | The holographic principle and the Immirzi parameter of loop quantum
gravity
gr-qc
The geometrical spectra in loop quantum gravity (LQG) suffer from ambiguity
up to the free Immirzi parameter that is often determined by comparing results
from the theory with the established dynamics at the black hole horizon. We
address conceptual difficulties associated with such approaches and point out
that the Immirzi parameter can be fixed naively by applying the LQG version of
the equipartition rule at a holographic boundary such that the Hawking-Unruh
temperature law follows. The value of the Immirzi parameter derived in this way
should possess universal validity. This approach also provides a clue that this
parameter could be rooted in the holographic principle.
| arxiv topic:gr-qc |
arxiv_dataset-66831510.04343 | The Pan-Pacific Planet Search III: Five companions orbiting giant stars
astro-ph.EP
We report a new giant planet orbiting the K giant HD 155233, as well as four
stellar-mass companions from the Pan-Pacific Planet Search, a southern
hemisphere radial velocity survey for planets orbiting nearby giants and
subgiants. We also present updated velocities and a refined orbit for HD 47205b
(7 CMa b), the first planet discovered by this survey. HD 155233b has a period
of 885$\pm$63 days, eccentricity e=0.03$\pm$0.20, and m sin i=2.0$\pm$0.5
M_jup. The stellar-mass companions range in m sin i from 0.066 M_sun to 0.33
M_sun. Whilst HD 104358B falls slightly below the traditional 0.08 M_sun
hydrogen-burning mass limit, and is hence a brown dwarf candidate, we estimate
only a 50% a priori probability of a truly substellar mass.
| arxiv topic:astro-ph.EP |
arxiv_dataset-66841510.04443 | New distinguished classes of spectral spaces: a survey
math.AC math.AG
In the present survey paper, we present several new classes of Hochster's
spectral spaces "occurring in nature", actually in multiplicative ideal theory,
and not linked to or realized in an explicit way by prime spectra of rings. The
general setting is the space of the semistar operations (of finite type),
endowed with a Zariski-like topology, which turns out to be a natural
topological extension of the space of the overrings of an integral domain,
endowed with a topology introduced by Zariski. One of the key tool is a recent
characterization of spectral spaces, based on the ultrafilter topology, given
in a paper by C. Finocchiaro in Comm. Algebra 2014. Several applications are
also discussed.
| arxiv topic:math.AC math.AG |
arxiv_dataset-66851510.04543 | Optimal design of auxetic hexachiral metamaterials with local resonators
cond-mat.mtrl-sci
A parametric beam lattice model is formulated to analyse the propagation
properties of elastic in-plane waves in an auxetic material based on a
hexachiral topology of the periodic cell, equipped with inertial local
resonators. The Floquet-Bloch boundary conditions are imposed on a reduced
order linear model in the only dynamically active degrees-offreedom. Since the
resonators can be designed to open and shift band gaps, an optimal design,
focused on the largest possible gap in the low-frequency range, is achieved by
solving a maximization problem in the bounded space of the significant
geometrical and mechanical parameters. A local optimized solution, for a the
lowest pair of consecutive dispersion curves, is found by employing the
globally convergent version of the Method of Moving asymptotes, combined with
Monte Carlo and quasi-Monte Carlo multi-start techniques.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-66861510.04643 | Core-Collapse Supernovae from 9 to 120 Solar Masses Based on
Neutrino-powered Explosions
astro-ph.HE astro-ph.SR
Nucleosynthesis, light curves, explosion energies, and remnant masses are
calculated for a grid of supernovae resulting from massive stars with solar
metallicity and masses from 9.0 to 120 solar masses. The full evolution is
followed using an adaptive reaction network of up to 2000 nuclei. A novel
aspect of the survey is the use of a one-dimensional neutrino transport model
for the explosion. This explosion model has been calibrated to give the
observed energy for SN 1987A, using several standard progenitors, and for the
Crab supernova using a 9.6 solar mass progenitor. As a result of using a
calibrated central engine, the final kinetic energy of the supernova is
variable and sensitive to the structure of the presupernova star. Many
progenitors with extended core structures do not explode, but become black
holes, and the masses of exploding stars do not form a simply connected set.
The resulting nucleosynthesis agrees reasonably well with the sun provided that
a reasonable contribution from Type Ia supernovae is also allowed, but with a
deficiency of light s-process isotopes. The resulting neutron star IMF has a
mean gravitational mass near 1.4 solar masses. The average black hole mass is
about 9 solar masses if only the helium core implodes, and 14 solar masses if
the entire presupernova star collapses. Only ~10% of supernovae come from stars
over 20 solar masses and some of these are Type Ib or Ic. Some useful
systematics of Type IIp light curves are explored.
| arxiv topic:astro-ph.HE astro-ph.SR |
arxiv_dataset-66871510.04743 | Muon polarization in the MEG experiment: predictions and measurements
hep-ex physics.ins-det
The MEG experiment makes use of one of the world's most intense low energy
muon beams, in order to search for the lepton flavour violating process
$\mu^{+} \rightarrow {\rm e}^{+} \gamma$. We determined the residual beam
polarization at the thin stopping target, by measuring the asymmetry of the
angular distribution of Michel decay positrons as a function of energy. The
initial muon beam polarization at the production is predicted to be $P_{\mu} =
-1$ by the Standard Model (SM) with massless neutrinos. We estimated our
residual muon polarization to be $P_{\mu} = -0.85 \pm 0.03 ~ {\rm (stat)} ~ {
}^{+ 0.04}_{-0.05} ~ {\rm (syst)}$ at the stopping target, which is consistent
with the SM predictions when the depolarizing effects occurring during the muon
production, propagation and moderation in the target are taken into account.
The knowledge of beam polarization is of fundamental importance in order to
model the background of our ${\megsign}$ search induced by the muon radiative
decay: $\mu^{+} \rightarrow {\rm e}^{+} \bar{\nu}_{\mu} \nu_{\rm e} \gamma$.
| arxiv topic:hep-ex physics.ins-det |
arxiv_dataset-66881510.04843 | Chv\'{a}tal-type results for degree sequence Ramsey numbers
math.CO
A sequence of nonnegative integers $\pi =(d_1,d_2,...,d_n)$ is graphic if
there is a (simple) graph $G$ of order $n$ having degree sequence $\pi$. In
this case, $G$ is said to realize or be a realization of $\pi$. Given a graph
$H$, a graphic sequence $\pi$ is potentially $H$-graphic if there is some
realization of $\pi$ that contains $H$ as a subgraph.
In this paper, we consider a degree sequence analogue to classical graph
Ramsey numbers. For graphs $H_1$ and $H_2$, the potential-Ramsey number
$r_{pot}(H_1,H_2)$ is the minimum integer $N$ such that for any $N$-term
graphic sequence $\pi$, either $\pi$ is potentially $H_1$-graphic or the
complementary sequence $\overline{\pi}=(N-1-d_N,\dots, N-1-d_1)$ is potentially
$H_2$-graphic.
We prove that if $s\ge 2$ is an integer and $T_t$ is a tree of order $t>
7(s-2)$, then $$r_{pot}(K_s, T_t) = t+s-2.$$ This result, which is best
possible up to the bound on $t$, is a degree sequence analogue to a classical
1977 result of Chv\'{a}tal on the graph Ramsey number of trees vs. cliques. To
obtain this theorem, we prove a sharp condition that ensures an arbitrary graph
packs with a forest, which is likely to be of independent interest.
| arxiv topic:math.CO |
arxiv_dataset-66891510.04943 | Portfolio Optimization under Expected Shortfall: Contour Maps of
Estimation Error
q-fin.RM q-fin.PM
The contour maps of the error of historical resp. parametric estimates for
large random portfolios optimized under the risk measure Expected Shortfall
(ES) are constructed. Similar maps for the sensitivity of the portfolio weights
to small changes in the returns as well as the VaR of the ES-optimized
portfolio are also presented, along with results for the distribution of
portfolio weights over the random samples and for the out-of-sample and
in-the-sample estimates for ES. The contour maps allow one to quantitatively
determine the sample size (the length of the time series) required by the
optimization for a given number of different assets in the portfolio, at a
given confidence level and a given level of relative estimation error. The
necessary sample sizes invariably turn out to be unrealistically large for any
reasonable choice of the number of assets and the confidence level. These
results are obtained via analytical calculations based on methods borrowed from
the statistical physics of random systems, supported by numerical simulations.
| arxiv topic:q-fin.RM q-fin.PM |
arxiv_dataset-66901510.05043 | A cost function for similarity-based hierarchical clustering
cs.DS cs.LG stat.ML
The development of algorithms for hierarchical clustering has been hampered
by a shortage of precise objective functions. To help address this situation,
we introduce a simple cost function on hierarchies over a set of points, given
pairwise similarities between those points. We show that this criterion behaves
sensibly in canonical instances and that it admits a top-down construction
procedure with a provably good approximation ratio.
| arxiv topic:cs.DS cs.LG stat.ML |
arxiv_dataset-66911510.05143 | Alfven wave coupled with flow-driven fluid instability in
interpenetrating plasmas
physics.plasm-ph
The Alfven wave is analyzed in case of one quasineutral plasma propagating
with some constant speed $v_0$ through another static quasineutral plasma. A
dispersion equation is derived describing the Alfven wave coupled with the flow
driven mode $\omega= k v_0$ and solutions are discussed analytically and
numerically. The usual solutions for two oppositely propagating Alfv\'en waves
are substantially modified due to the flowing plasma. More profound is
modification of the solution propagating in the negative direction with respect
to the magnetic field and the plasma flow. For a large enough flow speed
(exceeding the Alfven speed in the static plasma), this negative solution may
become non-propagating, with frequency equal to zero. In this case it
represents a spatial variation of the electromagnetic field. For greater flow
speed it becomes a forward mode, and it may merge with the positive one. This
merging of the two modes represents the starting point for a flow-driven
instability, with two complex-conjugate solutions. The Alfven wave in
interpenetrating plasmas is thus modified and coupled with the flow-driven mode
and this coupled mode is shown to be growing when the flow speed is large
enough. The energy for the instability is macroscopic kinetic energy of the
flowing plasma. The dynamics of plasma particles caused by such a coupled wave
still remains similar to the ordinary Alfven wave. This means that well-known
stochastic heating by the Alfv\'en wave may work, and this should additionally
support the potential role of the Alfven wave in the coronal heating.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-66921510.05243 | Resonant Combinatorial Frequency Generation Induced by a PT-symmetric
Periodic Layered Stack
physics.optics
The nonlinear interaction of waves in PT-symmetric periodic stacks with an
embedded nonlinear anisotropic dielectric layer illuminated by plane waves of
two tones is examined. The three-wave interaction technique is applied to study
the nonlinear processes. It is shown that the intensity of the three-wave
mixing process can be significantly enhanced in resonant cavities based on
PT-symmetric periodic structures, especially as the pumping wave frequency is
near the coherent perfect absorber-lasing resonances. The main mechanisms and
properties of the combinatorial frequency generation and emission from the
stacks are illustrated by the simulation results and the effect of the layer
arrangement in PT-symmetric walls of resonator on the stack nonlinear response
is discussed. The enhanced efficiency of the frequency conversion at Wolf-Bragg
resonances is demonstrated. It has been shown that Wolf-Bragg resonances of
very high orders may lead to the global maxima and nulls of the scattered
field. The analysis of the effect of losses in nonlinear dielectric layer on
the combinatorial frequency generation efficiency has shown that the rate of
losses may amplify the intensity of the frequency mixing process.
| arxiv topic:physics.optics |
arxiv_dataset-66931510.05343 | HI-deficient galaxies in intermediate density environments
astro-ph.GA
Observations show that spiral galaxies in galaxy clusters tend to have on
average less neutral hydrogen (HI) than galaxies of the same type and size in
the field. There is accumulating evidence that such HI-deficient galaxies are
also relatively frequent in galaxy groups. An important question is, which
mechanisms are responsible for the gas deficiency in galaxy groups. To gain a
better understanding of how environment affects the gas content of galaxies, we
identified a sample of six HI-deficient galaxies from the HI Parkes All Sky
Survey (HIPASS) using HI-optical scaling relations. One of the galaxies is
located in the outskirts of the Fornax cluster, four are in loose galaxy groups
and one is in a galaxy triplet. We present new high resolution HI observations
with the Australia Telescope Compact Array (ATCA) of these galaxies. We discuss
the possible cause of HI-deficiency in these galaxies based on HI observations
and various multi-wavelength data. We find that the galaxies have truncated HI
disks, lopsided gas distribution and some show asymmetries in their stellar
disks. We conclude that both ram pressure stripping and tidal interactions are
important gas removal mechanisms in low density environments.
| arxiv topic:astro-ph.GA |
arxiv_dataset-66941510.05443 | Poincar\'e-like approach to Landau Theory. I. General theory
math-ph cond-mat.soft math.MP physics.class-ph
We discuss a procedure to simplify the Landau potential, based on Michel's
reduction to orbit space and Poincar\'e normalization procedure; and illustrate
it by concrete examples. The method makes use, as in Poincar\'e theory, of a
chain of near-identity coordinate transformations with homogeneous generating
functions; using Michel's insight, one can work in orbit space. It is shown
that it is possible to control the choice of generating functions so to obtain
a (in many cases, substantial) simplification of the Landau polynomial,
including a reduction of the parameters it depends on. Several examples are
considered in detail.
| arxiv topic:math-ph cond-mat.soft math.MP physics.class-ph |
arxiv_dataset-66951510.05543 | Crystalline comparison isomorphisms in $p$-adic Hodge theory: the
absolutely unramified case
math.AG
We construct the crystalline comparison isomorphisms for proper smooth formal
schemes over an absolutely unramified base. Such isomorphisms hold for \'etale
cohomology with nontrivial coefficients, as well as in the relative setting,
i.e. for proper smooth morphisms of smooth formal schemes. The proof is
formulated in terms of the pro-\'etale topos introduced by Scholze, and uses
his primitive comparison theorem for the structure sheaf on the pro-\'etale
site. Moreover, we need to prove the Poincar\'e lemma for crystalline period
sheaves, for which we adapt the idea of Andreatta and Iovita. Another
ingredient for the proof is the geometric acyclicity of crystalline period
sheaves, whose computation is due to Andreatta and Brinon.
| arxiv topic:math.AG |
arxiv_dataset-66961510.05643 | Reply to "Comment on `Axion induced oscillating electric dipole moments'
" [1]
hep-ph hep-ex hep-th
We respond to a paper of Flambaum, et.al. [Phys. Rev. D95, no. 5, 058701
(2017)], claiming there is no effective induced oscillating electric dipole
moment, e.g., for the electron, arising from interaction with an oscillating
cosmic axion background via the anomaly. The relevant Feynman amplitude,
Fig.(1), as computed by Flambaum et.al., becomes a total divergence, and
vanishes. Contrary to this result, we obtained a nonvanishing amplitude, that
yields physical electric dipole radiation for an electron (or any magnetic
dipole moment) immersed in a cosmic axion field. We argue that the Flambaum
et.al. counter-claim is incorrect, and is based upon a misunderstanding of a
physics choice vs. gauge choice, and an assumption that electric dipoles be
defined only by coupling to static (constant in time) electric fields.
| arxiv topic:hep-ph hep-ex hep-th |
arxiv_dataset-66971510.05743 | A scalable theoretical mean-field model for the electron component of an
ultracold neutral plasma
physics.plasm-ph
The electron component of an ultracold neutral plasma (UCP) is modeled based
on a scalable method using a self-consistently determined mean-field
approximation. Representative sampling of discrete electrons within the UCP are
used to project the electron spatial distribution onto an expansion of
orthogonal basis functions. A collision operator acting on the sample electrons
is employed in order to drive the distribution toward thermal equilibrium.
These equilibrium distributions can be determined for non-zero electron
temperatures even in the presence of spherical symmetry-breaking applied
electric fields. This is useful for predicting key macroscopic UCP parameters,
such as the depth of the electrons' confining potential. Dynamics such as
electron oscillations in UCPs with non-uniform density distributions can also
be treated by this model.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-66981510.05843 | Takens' embedding theorem with a continuous observable
math.DS math-ph math.MP
Let $(X,T)$ be a dynamical system where $X$ is a compact metric space and
$T:X\rightarrow X$ is continuous and invertible. Assume the Lebesgue covering
dimension of $X$ is $d$. We show that for a generic continuous map
$h:X\rightarrow[0,1]$, the $(2d+1)$-delay observation map
$x\mapsto\big(h(x),h(Tx),\ldots,h(T^{2d}x)\big)$ is an embedding of $X$ inside
$[0,1]^{2d+1}$. This is a generalization of the discrete version of the
celebrated Takens embedding theorem, as proven by Sauer, Yorke and Casdagli to
the setting of a continuous observable. In particular there is no assumption on
the (lower) box-counting dimension of $X$ which may be infinite.
| arxiv topic:math.DS math-ph math.MP |
arxiv_dataset-66991510.05943 | Reinforcing the link between the double red clump and the X-shaped bulge
of the Milky Way
astro-ph.GA
The finding of a double red clump in the luminosity function of the Milky Way
bulge has been interpreted as evidence for an X-shaped structure. Recently, an
alternative explanation has been suggested, where the double red clump is an
effect of multiple stellar populations in a classical spheroid. In this letter
we provide an observational assessment of this scenario and show that it is not
consistent with the behaviour of the red clump across different lines of sight,
particularly at high distances from the Galactic plane. Instead, we confirm
that the shape of the red clump magnitude distribution closely follows the
distance distribution expected for an X-shaped bulge at critical Galactic
latitudes. We also emphasize some key observational properties of the bulge red
clump that should not be neglected in the search for alternative scenarios.
| arxiv topic:astro-ph.GA |
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