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We consider a cell-free massive multiple-input multiple-output (CFmMIMO)
network operating in dynamic time division duplex (DTDD). The switching point
between the uplink (UL) and downlink (DL) data transmission phases can be
adapted dynamically to the instantaneous quality-of-service (QoS) requirements
in order to improve energy efficiency (EE). To this end, we formulate a problem
of optimizing the DTDD switching point jointly with the UL and DL power control
coefficients, and the large-scale fading decoding (LSFD) weights for EE
maximization. Then, we propose an iterative algorithm to solve the formulated
challenging problem using successive convex approximation with an approximate
stationary solution. Simulation results show that optimizing switching points
remarkably improves EE compared with baseline schemes that adjust switching
points heuristically.
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The interaction between off-resonant laser pulses and excitons in monolayer
transition metal dichalcogenides is attracting increasing interest as a route
for the valley-selective coherent control of the exciton properties. Here, we
extend the classification of the known off-resonant phenomena by unveiling the
impact of a strong THz field on the excitonic resonances of monolayer MoS$_2$.
We observe that the THz pump pulse causes a selective modification of the
coherence lifetime of the excitons, while keeping their oscillator strength and
peak energy unchanged. We rationalize these results theoretically by invoking a
hitherto unobserved manifestation of the Franz-Keldysh effect on an exciton
resonance. As the modulation depth of the optical absorption reaches values as
large as 0.05 dB/nm at room temperature, our findings open the way to the use
of semiconducting transition metal dichalcogenides as compact and efficient
platforms for high-speed electroabsorption devices.
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We study stripes in cuprates within the one-band and the three-band Hubbard
model. Magnetic and charge excitations are described within the time-dependent
Gutzwiller approximation. A variety of experiments (charge profile from
resonant soft X-ray scattering, incommensurability vs. doping, optical
excitations, magnetic excitations, etc.) are described within the same
approach.
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We demonstrate that the recently observed $X$, $Y$, $Z$ states cannot be
purely from kinematic effect. Especially the narrow near-threshold structures
in elastic channels call for nearby poles of the $S$-matrix which are qualified
as states. We propose a way to distinguish cusp effects from genuine states and
demonstrate that (not all of) the recently observed $X$, $Y$, $Z$ states cannot
be purely from kinematic effects. Especially, we show that the narrow
near-threshold structures in elastic channels call for nearby poles of the
$S$-matrix, since the normal kinematic cusp effect cannot produce that narrow
structures in the elastic channels in contrast to genuine $S$-matrix poles. In
addition, it is also discussed how spectra can be used to distinguish different
scenarios proposed for the structure of those poles, such as hadro-quarkonia,
tetraquarks and hadronic molecules. The basic tool employed is heavy quark spin
symmetry.
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Motion planning in the configuration space (C-space) induces benefits, such
as smooth trajectories. It becomes more complex as the degrees of freedom (DOF)
increase. This is due to the direct relation between the dimensionality of the
search space and the DOF. Self-organizing neural networks (SONN) and their
famous candidate, the Self-Organizing Map, have been proven to be useful tools
for C-space reduction while preserving its underlying topology, as presented in
[29]. In this work, we extend our previous study with additional models and
adapt the approach from human motion data towards robots' kinematics. The
evaluation includes the best performant models from [29] and three additional
SONN architectures, representing the consequent continuation of this previous
work. Generated Trajectories, planned with the different SONN models, were
successfully tested in a robot simulation.
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Let $p: \mathcal{E} \to \mathcal{S}$ be a pre-cohesive geometric morphism. We
show that the least subtopos of $\mathcal{E}$ containing both the subcategories
$p^*: \mathcal{S} \to \mathcal{E}$ and $p^!: \mathcal{S} \to \mathcal{E}$
exists, and that it coincides with the least subtopos containing $p^*2$, where
2 denotes the subobject classifier of $\mathcal{S}$.
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The X-ray flares of NGC 5905, RX J1242.6-1119A, and RX J1624.9+7554 observed
by Chandra in 2001 and 2002 have been suggested as the candidate tidal
disruption events. The distinct features observed from these events may be used
to determine the type of a star tidally disrupted by a massive black hole. We
investigate these three events, focusing on the differences for the tidal
disruption of a giant star and a main sequence, resulted from their different
relation between the mass and the radius. We argue that their X-ray flare
properties could be modeled by the partial stripping of the outer layers of a
solar type star. The tidal disruption of a giant star is excluded completely.
This result may be useful for understanding the growth of a supermassive black
hole by capturing stars, versus the growth mode through continuous mass
accretion.
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The method of this paper is my original creation. A new method for solving
linear differential equations is proposed in this paper. The important
conclusion of this paper is that arbitrary order linear ordinary differential
equations with variable coefficients can be solved by the method of recursion
and reduction of order under some conditions which easily be satisfied in
practical applications.
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Let $T$ be a tree, a vertex of degree one is called a leaf. The set of leaves
of $T$ is denoted by $Leaf(T)$. The subtree $T-Leaf(T)$ of $T$ is called the
stem of $T$ and denoted by $Stem(T).$ In this note, we give a sharp sufficient
condition to show that a $K_{1,t}-$free graph has a spanning tree whose stem
has a few leaves. By applying the main result, we give improvements of previous
related results.
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Current, near-term quantum devices have shown great progress in recent years
culminating with a demonstration of quantum supremacy. In the medium-term,
however, quantum machines will need to transition to greater reliability
through error correction, likely through promising techniques such as surface
codes which are well suited for near-term devices with limited qubit
connectivity. We discover quantum memory, particularly resonant cavities with
transmon qubits arranged in a 2.5D architecture, can efficiently implement
surface codes with substantial hardware savings and performance/fidelity gains.
Specifically, we *virtualize logical qubits* by storing them in layers
distributed across qubit memories connected to each transmon.
Surprisingly, distributing each logical qubit across many memories has a
minimal impact on fault tolerance and results in substantially more efficient
operations. Our design permits fast transversal CNOT operations between logical
qubits sharing the same physical address which are 6x faster than lattice
surgery CNOTs. We develop a novel embedding which saves ~10x in transmons with
another 2x from an additional optimization for compactness.
Although Virtualized Logical Qubits (VLQ) pays a 10x penalty in
serialization, advantages in the transversal CNOT and area efficiency result in
performance comparable to 2D transmon-only architectures. Our simulations show
fault tolerance comparable to 2D architectures while saving substantial
hardware. Furthermore, VLQ can produce magic states 1.22x faster for a fixed
number of transmon qubits. This is a critical benchmark for future
fault-tolerant quantum computers. VLQ substantially reduces the hardware
requirements for fault tolerance and puts within reach a proof-of-concept
experimental demonstration of around 10 logical qubits, requiring only 11
transmons and 9 attached cavities in total.
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We study the dependence of thermal conductivity of single walled nanotubes
(SWNT) on chirality, isotope impurity, tube length and temperature by
nonequilibrium molecular dynamics method with accurate potentials. It is found
that, contrary to electronic conductivity, the thermal conductivity is
insensitive to the chirality. The isotope impurity, however, can reduce the
thermal conductivity up to 60% and change the temperature dependence behavior.
We also found that the tube length dependence of thermal conductivity is
different for nanotubes of different radius at different temperatures.
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We have seen that if \phi: M_n(\C) \rightarrow M_n(\C) is a unital q-positive
map and \nu is a type II Powers weight, then the boundary weight double (\phi,
\nu) induces a unique (up to conjugacy) type II_0 E_0-semigroup. Let \phi:
M_n(\C) \rightarrow M_n(\C) and \psi: M_{n'}(\C) \rightarrow M_{n'}(\C) be
unital rank one q-positive maps, so for some states \rho \in M_n(\C)^* and
\rho' \in M_{n'}(\C)^*, we have \phi(A)=\rho(A)I_n and \psi(D) = \rho'(D)I_{n'}
for all A \in M_n(\C) and D \in M_{n'}(\C). We find that if \nu and \eta are
arbitrary type II Powers weights, then (\phi, \nu) and (\psi, \eta) induce
non-cocycle conjugate E_0-semigroups if \rho and \rho' have different
eigenvalue lists. We then completely classify the q-corners and hyper maximal
q-corners from \phi to \psi, obtaining the following result: If \nu is a type
II Powers weight of the form \nu(\sqrt{I - \Lambda(1)} B \sqrt{I -
\Lambda(1)})=(f,Bf), then the E_0-semigroups induced by (\phi,\nu) and (\psi,
\nu) are cocycle conjugate if and only if n=n' and \phi and \psi are conjugate.
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We introduce an $A_\infty$ map from the cubical chain complex of the based
loop space of Lagrangian submanifolds with Legendrian boundary in a Liouville
Manifold $C_{*}(\Omega_{L} \mathcal{L}\mathit{ag})$ to wrapped Floer cohomology
of Lagrangian submanifold $\mathcal{CW}^{-*}(L,L)$. In the case of a cotangent
bundle and a Lagrangian co-fiber, the composition of our map with a previously
constructed map from $\mathcal{CW}^*(L,L) \to C_{*}(\Omega_q Q) $ shows that
this map is split surjective.
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Radiation hydrodynamics simulations based on the one-fluid two-temperature
model may violate the law of energy conservation because the governing
equations are expressed in a nonconservative formulation. Here, we maintain the
important physical requirements by employing a strategy based on the key
concept that the mathematical structures associated with the conservative and
nonconservative equations are preserved, even at the discrete level. To this
end, we discretize the conservation laws and transform them via exact algebraic
operations. The proposed scheme maintains the global conservation errors within
the round-off level. In addition, a numerical experiment concerning the shock
tube problem suggests that the proposed scheme well agrees with the jump
conditions at the discontinuities regulated by the Rankine-Hugoniot
relationship. The generalized derivation allows us to employ arbitrary central
difference, artificial dissipation, and Runge-Kutta methods.
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In relation to a thesis put forward by Marx Wartofsky, we seek to show that a
historiography of mathematics requires an analysis of the ontology of the part
of mathematics under scrutiny. Following Ian Hacking, we point out that in the
history of mathematics the amount of contingency is larger than is usually
thought. As a case study, we analyze the historians' approach to interpreting
James Gregory's expression ultimate terms in his paper attempting to prove the
irrationality of pi. Here Gregory referred to the last or ultimate terms of a
series. More broadly, we analyze the following questions: which modern
framework is more appropriate for interpreting the procedures at work in texts
from the early history of infinitesimal analysis? as well as the related
question: what is a logical theory that is close to something early modern
mathematicians could have used when studying infinite series and quadrature
problems? We argue that what has been routinely viewed from the viewpoint of
classical analysis as an example of an "unrigorous" practice, in fact finds
close procedural proxies in modern infinitesimal theories. We analyze a mix of
social and religious reasons that had led to the suppression of both the
religious order of Gregory's teacher degli Angeli, and Gregory's books at
Venice, in the late 1660s.
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We study the following coupled Schr\"odinger system \ds -\Delta
u+u=u^{2^*-1}+\be u^{\frac{2^*}{2}-1}v^{\frac{2^*}{2}}+\la_1u^{\al-1}, &x\in
\R^N, \ds -\Delta v+v=v^{2^*-1}+\be
u^{\frac{2^*}{2}}v^{\frac{2^*}{2}-1}+\la_2v^{r-1}, &x\in \R^N, u,v > 0, &x\in
\R^N, where $N\geq 5, \la_1,\la_2>0,\be\neq 0, 2<\al,r<2^*,2^*\triangleq
\frac{2N}{N-2}.$ Note that the nonlinearity and the coupling terms are both
critical. Using the Mountain Pass Theorem, Ekeland's variational principle and
Nehari mainfold, we show that this critical system has a positive radial
solution for positive $\be$ and some negative $\be$ respectively.
|
Covering the face and all body parts, sometimes the only evidence to identify
a person is their hand geometry, and not the whole hand- only two fingers (the
index and the middle fingers) while showing the victory sign, as seen in many
terrorists videos. This paper investigates for the first time a new way to
identify persons, particularly (terrorists) from their victory sign. We have
created a new database in this regard using a mobile phone camera, imaging the
victory signs of 50 different persons over two sessions. Simple measurements
for the fingers, in addition to the Hu Moments for the areas of the fingers
were used to extract the geometric features of the shown part of the hand shown
after segmentation. The experimental results using the KNN classifier were
encouraging for most of the recorded persons; with about 40% to 93% total
identification accuracy, depending on the features, distance metric and K used.
|
The utility of optical coherence tomography signal intensity for measurement
of glucose concentration has been analysed in tissue phantom and blood samples
from human subjects. The diffusion equation based calculations as well as
in-vivo OCT signal measurements confirms the cyclic correlation of signal
intensity with glucose concentration and scatterer size.
|
We have applied laser calorimetry to the measurement of optical absorption in
mono-crystalline sapphire at cryogenic temperatures. Sapphire is a promising
candidate for the mirror substrates of the Large-scale Cryogenic Gravitational
wave Telescope. The optical absorption coefficients of different sapphire
samples at a wavelength of 1.064(micro)m at 5K were found to average 90ppm/cm.
|
This Ph.D. thesis focuses on developing a system for high-quality speech
synthesis and voice conversion. Vocoder-based speech analysis, manipulation,
and synthesis plays a crucial role in various kinds of statistical parametric
speech research. Although there are vocoding methods which yield close to
natural synthesized speech, they are typically computationally expensive, and
are thus not suitable for real-time implementation, especially in embedded
environments. Therefore, there is a need for simple and computationally
feasible digital signal processing algorithms for generating high-quality and
natural-sounding synthesized speech. In this dissertation, I propose a solution
to extract optimal acoustic features and a new waveform generator to achieve
higher sound quality and conversion accuracy by applying advances in deep
learning. The approach remains computationally efficient. This challenge
resulted in five thesis groups, which are briefly summarized below.
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Unconventional density wave (UDW) has been speculated as a possible
electronic ground state in excitonic insulator in 1968. Recent surge of
interest in UDW is partly due to the proposal that the pseudogap phase in high
T_c cuprate superconductors is d-wave density wave (d-DW).
Here we review our recent works on UDW within the framework of mean field
theory. In particular we have shown that many properties of the low temperature
phase (LTP) in alpha-(BEDT-TTF)_2MHg(SCN)_4 with M=K, Rb and Tl are well
characterized in terms of unconventional charge density wave (UCDW). In this
identification the Landau quantization of the quasiparticle motion in a
magnetic field (the Nersesyan effect) plays the crucial role. Indeed the
angular dependent magnetoresistance and the negative giant Nernst effect are
two hallmarks of UDW.
|
In their thought-provoking paper [1], Belkin et al. illustrate and discuss
the shape of risk curves in the context of modern high-complexity learners.
Given a fixed training sample size $n$, such curves show the risk of a learner
as a function of some (approximate) measure of its complexity $N$. With $N$ the
number of features, these curves are also referred to as feature curves. A
salient observation in [1] is that these curves can display, what they call,
double descent: with increasing $N$, the risk initially decreases, attains a
minimum, and then increases until $N$ equals $n$, where the training data is
fitted perfectly. Increasing $N$ even further, the risk decreases a second and
final time, creating a peak at $N=n$. This twofold descent may come as a
surprise, but as opposed to what [1] reports, it has not been overlooked
historically. Our letter draws attention to some original, earlier findings, of
interest to contemporary machine learning.
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A coarse-grained variational model is used to investigate the polymer
dynamics of barrier crossing for a diverse set of two-state folding proteins.
The model gives reliable folding rate predictions provided excluded volume
terms that induce minor structural cooperativity are included in the
interaction potential. In general, the cooperative folding routes have sharper
interfaces between folded and unfolded regions of the folding nucleus and
higher free energy barriers. The calculated free energy barriers are strongly
correlated with native topology as characterized by contact order. Increasing
the rigidity of the folding nucleus changes the local structure of the
transition state ensemble non-uniformly across the set of protein studied.
Neverthless, the calculated prefactors k0 are found to be relatively uniform
across the protein set, with variation in 1/k0 less than a factor of five. This
direct calculation justifies the common assumption that the prefactor is
roughly the same for all small two-state folding proteins. Using the barrier
heights obtained from the model and the best fit monomer relaxation time 30ns,
we find that 1/k0 (1-5)us (with average 1/k0 4us). This model can be extended
to study subtle aspects of folding such as the variation of the folding rate
with stability or solvent viscosity, and the onset of downhill folding.
|
Quantitative analysis of in utero human brain development is crucial for
abnormal characterization. Magnetic resonance image (MRI) segmentation is
therefore an asset for quantitative analysis. However, the development of
automated segmentation methods is hampered by the scarce availability of fetal
brain MRI annotated datasets and the limited variability within these cohorts.
In this context, we propose to leverage the power of fetal brain MRI
super-resolution (SR) reconstruction methods to generate multiple
reconstructions of a single subject with different parameters, thus as an
efficient tuning-free data augmentation strategy. Overall, the latter
significantly improves the generalization of segmentation methods over SR
pipelines.
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This paper concerns quantum heuristics based on Mixer Hamiltonians that allow
to restrict investigation on a specific subspace. Mixer Hamiltonian based
approaches can be included in QAOA algorithm and we can state that Mixer
Hamiltonians are mapping functions from the set of qubit-strings to the set of
solutions. Mixer Hamiltonian offers an approach very similar to indirect
representations commonly used in routing or in scheduling community for
decades. After the initial publication of Cheng et al. in 1996 (Cheng et al.,
1996), numerous propositions in OR lies on 1-to-n mapping functions, including
the split algorithm that transform one TSP solution into a VRP solution. The
objective is at first to give a compact and readable presentation of these
Mixer Hamiltonians considering the functional analogies that exist between the
OR community practices and the quantum field. Our experiments encompass
numerical evaluations of circuit using the Qiskit library of IBM meeting the
theoretical considerations.
|
Let $X$ be a compact K\"ahler manifold. We study plurisupported currents on
$X$, i.e. closed, positive $(1,1)$-currents which are supported on a pluripolar
set. In particular, we are able present a technical generalization of
Witt-Nystr\"om's proof of the BDPP conjecture on projective manifolds, showing
that this conjecture holds on $X$ admitting at least one plurisupported current
$T$ such that $[T]$ is K\"ahler.
One of the steps in our proof is to show an upper-bound for the pluripolar
mass of certain envelopes of quasi-psh functions when the cohomology class is
shifted, a result of independent interest. Using this, we are able to
generalize an inequality of McKinnon and Roth to arbitrary pseudoeffective
classes on compact K\"ahler manifolds.
|
Quality data is a fundamental contributor to success in statistics and
machine learning. If a statistical assessment or machine learning leads to
decisions that create value, data contributors may want a share of that value.
This paper presents methods to assess the value of individual data samples, and
of sets of samples, to apportion value among different data contributors. We
use Shapley values for individual samples and Owen values for combined samples,
and show that these values can be computed in polynomial time in spite of their
definitions having numbers of terms that are exponential in the number of
samples.
|
Consider the problem of recovering an unknown signal from undersampled
measurements, given the knowledge that the signal has a sparse representation
in a specified dictionary $D$. This problem is now understood to be well-posed
and efficiently solvable under suitable assumptions on the measurements and
dictionary, if the number of measurements scales roughly with the sparsity
level. One sufficient condition for such is the $D$-restricted isometry
property ($D$-RIP), which asks that the sampling matrix approximately preserve
the norm of all signals which are sufficiently sparse in $D$. While many
classes of random matrices are known to satisfy such conditions, such matrices
are not representative of the structural constraints imposed by practical
sensing systems. We close this gap in the theory by demonstrating that one can
subsample a fixed orthogonal matrix in such a way that the $D$-RIP will hold,
provided this basis is sufficiently incoherent with the sparsifying dictionary
$D$. We also extend this analysis to allow for weighted sparse expansions.
Consequently, we arrive at compressive sensing recovery guarantees for
structured measurements and redundant dictionaries, opening the door to a wide
array of practical applications.
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We provide the full set of renormalization group functions for the
renormalization of QCD in the minimal MOM scheme to four loops for the colour
group SU(N_c).
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We extend work of the first author concering relative double commutants and
approximate double commutants of unital subalgebras of unital C*-algebras,
including metric versions involving distance estimates. We prove metric results
for AH subalgebras of von Neumann algebras or AF subalgebras of primitive
C*-algebras. We prove other general results, including some for nonselfadjoint
commutative subalgebras, using C*-algebraic versions of the Stone-Weierstrass
and Bishop-Stone-Weierstrass theorems.
|
A well-balanced detector with high sensitivity and low noise is presented in
this paper. The two-stage amplification structure is used to increase
electronic gain while keeping an effective bandwidth of about 70 MHz. In order
to further reduce electronic noise, a junction field-effect transistor(JFET) is
connected between photodiodes and transimpedance amplifier to reduce the impact
of amplifier leakage current. Benefit from these designs, the
root-mean-square(RMS) of noise voltage is about 6 mV with a gain of 3.2E5 V/W,
and it means an ultra-low noise equivalent power density of 2.2E-12 W/rtHz,
only half of common low-noise commercial detectors. In addition, two
photodiodes in similar frequency response are selected for detector and make
the common mode rejection ratio(CMRR) of detector reached 53 dB, about 13 dB
higher than commercial detectors. Further tests indicate that 16.8 dB
shot-noise to electronic-noise ratio is measured in our detector, which is
better than most high speed balanced detectors.
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Anomaly detection is challenging, especially for large datasets in high
dimensions. Here we explore a general anomaly detection framework based on
dimensionality reduction and unsupervised clustering. We release DRAMA, a
general python package that implements the general framework with a wide range
of built-in options. We test DRAMA on a wide variety of simulated and real
datasets, in up to 3000 dimensions, and find it robust and highly competitive
with commonly-used anomaly detection algorithms, especially in high dimensions.
The flexibility of the DRAMA framework allows for significant optimization once
some examples of anomalies are available, making it ideal for online anomaly
detection, active learning and highly unbalanced datasets.
|
We will present an extension of the standard model of particle physics in its
almost-commutative formulation. This extension is guided by the minimal
approach to almost-commutative geometries employed in [13], although the model
presented here is not minimal itself.
The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs
model which consists of the standard model and two new fermions of opposite
electro-magnetic charge which may possess a new colour like gauge group. As a
new phenomenon, grand unification is no longer required by the spectral action.
|
$O(\alpha_s)$ QCD corrections to the inclusive $B \to X_s e^+ e^-$ decay are
investigated within the two - Higgs doublet extension of the standard model
(2HDM). The analysis is performed in the so - called off-resonance region; the
dependence of the obtained results on the choice of the renormalization scale
is examined in details. It is shown that $O(\alpha_s)$ corrections can suppress
the $B \to X_s e^+ e^-$ decay width up to $1.5 \div 3$ times (depending on the
choice of the dilepton invariant mass $s$ and the low - energy scale $\mu$). As
a result, in the experimentally allowed range of the parameters space, the
relations between the $B \to X_s e^+ e^-$ branching ratio and the new physics
parameters are strongly affected. It is found also that though the
renormalization scale dependence of the $B \to X_s e^+ e^-$ branching is
significantly reduced, higher order effects in the perturbation theory can
still be nonnegligible.
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Metasurfaces have drawn significant attentions due to their superior
capability in tailoring electromagnetic waves with a wide frequency range, from
microwave to visible light. Recently, programmable metasurfaces have
demonstrated the ability of manipulating the amplitude or phase of
electromagnetic waves in a programmable manner in real time, which renders them
especially appealing in the applications of wireless communications. To
practically demonstrate the feasibility of programmable metasurfaces in future
communication systems, in this paper, we design and realize a novel
metasurface-based wireless communication system. By exploiting the dynamically
controllable property of programmable metasurface, we firstly introduce the
fundamental principle of the metasurface-based wireless communication system
design. We then present the design, implementation and experimental evaluation
of the proposed metasurface-based wireless communication system with a
prototype, which realizes single carrier quadrature phase shift keying (QPSK)
transmission over the air. In the developed prototype, the phase of the
reflected electromagnetic wave of programmable metasurface is directly
manipulated in real time according to the baseband control signal, which
achieves 2.048 Mbps data transfer rate with video streaming transmission over
the air. Experimental result is provided to compare the performance of the
proposed metasurface-based architecture against the conventional one. With the
slight increase of the transmit power by 5 dB, the same bit error rate (BER)
performance can be achieved as the conventional system in the absence of
channel coding. Such a result is encouraging considering that the
metasurface-based system has the advantages of low hardware cost and simple
structure, thus leading to a promising new architecture for wireless
communications.
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The multichannel Kondo model supports effective anyons on the partially
screened impurity, as suggested by its fractional impurity entropy. It was
recently demonstrated for the multi-impurity chiral Kondo model, that
scattering of an electron through the impurities depends on the anyon's total
fusion channel. Here we study the correlation between impurity-spins. We argue,
based on a combination of conformal field theory, a perturbative limit with a
large number of channels $k$, and the exactly solvable two-channel case, that
the inter-impurity spin correlation probes the anyon fusion of the pair of
correlated impurities. This may allow, using measurement-only topological
quantum computing protocols, to braid the multichannel Kondo anyons via
consecutive measurements.
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Deep generative models (DGMs) and their conditional counterparts provide a
powerful ability for general-purpose generative modeling of data distributions.
However, it remains challenging for existing methods to address advanced
conditional generative problems without annotations, which can enable multiple
applications like image-to-image translation and image editing. We present a
unified Bayesian framework for such problems, which introduces an inference
stage on latent variables within the learning process. In particular, we
propose a variational Bayesian image translation network (VBITN) that enables
multiple image translation and editing tasks. Comprehensive experiments show
the effectiveness of our method on unsupervised image-to-image translation, and
demonstrate the novel advanced capabilities for semantic editing and mixed
domain translation.
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The Fock-Krylov formalism for the calculation of survival probabilities of
unstable states is revisited paying particular attention to the mathematical
constraints on the density of states, the Fourier transform of which gives the
survival amplitude. We show that it is not possible to construct a density of
states corresponding to a purely exponential survival amplitude. he survival
probability $P(t)$ and the autocorrelation function of the density of states
are shown to form a pair of cosine Fourier transforms. This result is a
particular case of the Wiener Khinchin theorem and forces $P(t)$ to be an even
function of time which in turn forces the density of states to contain a form
factor which vanishes at large energies. Subtle features of the transition
regions from the non-exponential to the exponential at small times and the
exponential to the power law decay at large times are discussed by expressing
$P(t)$ as a function of the number of oscillations, $n$, performed by it. The
transition at short times is shown to occur when the survival probability has
completed one oscillation. The number of oscillations depend on the properties
of the resonant state and a complete description of the evolution of the
unstable state is provided by determining the limits on the number of
oscillations in each region.
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We describe further results of a program aimed to yield ~10^4 fully
characterized optical identifications of ROSAT X-ray sources. Our program
employs X-ray data from the ROSAT All-Sky Survey (RASS), and both optical
imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS).
RASS/SDSS data from 5740 deg^2 of sky spectroscopically covered in SDSS Data
Release 5 (DR5) provide an expanded catalog of 7000 confirmed quasars and other
AGN that are probable RASS identifications. Again in our expanded catalog, the
identifications as X-ray sources are statistically secure, with only a few
percent of the SDSS AGN likely to be randomly superposed on unrelated RASS
X-ray sources. Most identifications continue to be quasars and Seyfert 1s with
15<m<21 and 0.01<z<4; but the total sample size has grown to include very
substantial numbers of even quite rare AGN, e.g., now including several
hundreds of candidate X-ray emitting BL Lacs and narrow-line Seyfert 1
galaxies. In addition to exploring rare subpopulations, such a large total
sample may be useful when considering correlations between the X-ray and the
optical, and may also serve as a resource list from which to select the "best"
object (e.g., X-ray brightest AGN of a certain subclass, at a preferred
redshift or luminosity) for follow-on X-ray spectral or alternate detailed
studies.
|
We consider the solutions of the field equations for the large $N$ dilaton
gravity model in $1+1$ dimensions recently proposed by Callan, Giddings, Harvey
and Strominger (CGHS). We find time dependant solutions with finite mass and
vanishing flux in the weak coupling regime, as well as solutions which lie
entirely in the Liouville region.
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We revisit the notion of individual fairness proposed by Dwork et al. A
central challenge in operationalizing their approach is the difficulty in
eliciting a human specification of a similarity metric. In this paper, we
propose an operationalization of individual fairness that does not rely on a
human specification of a distance metric. Instead, we propose novel approaches
to elicit and leverage side-information on equally deserving individuals to
counter subordination between social groups. We model this knowledge as a
fairness graph, and learn a unified Pairwise Fair Representation (PFR) of the
data that captures both data-driven similarity between individuals and the
pairwise side-information in fairness graph. We elicit fairness judgments from
a variety of sources, including human judgments for two real-world datasets on
recidivism prediction (COMPAS) and violent neighborhood prediction (Crime &
Communities). Our experiments show that the PFR model for operationalizing
individual fairness is practically viable.
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We report updates to an ongoing lattice-QCD calculation of the form factors
for the semileptonic decays $B \to \pi \ell \nu$, $B_s \to K \ell \nu$, $B \to
\pi \ell^+ \ell^-$, and $B \to K \ell^+ \ell^-$. The tree-level decays $B_{(s)}
\to \pi (K) \ell \nu$ enable precise determinations of the CKM matrix element
$|V_{ub}|$, while the flavor-changing neutral-current interactions $B \to \pi
(K) \ell^+ \ell^-$ are sensitive to contributions from new physics. This work
uses MILC's (2+1+1)-flavor HISQ ensembles at approximate lattice spacings
between $0.057$ and $0.15$ fm, with physical sea-quark masses on four out of
the seven ensembles. The valence sector is comprised of a clover $b$ quark (in
the Fermilab interpretation) and HISQ light and $s$ quarks. We present
preliminary results for the form factors $f_0$, $f_+$, and $f_T$, including
studies of systematic errors.
|
Relaxation rates in the $13mLiNO_3-6,5mCa(NO_3)_2-H_2O$ ternary system have
been measured for nuclei of water ($^1H$ and $^{17}O$), anion ($^{14}N$), and
both cations ($^7Li$, $^{43}Ca$). The data analysis reveals the system
structure as consisting of two main charged units: [Li(H$_2$O)$_4$]$^+$ and
[Ca(NO$_3$)$_4$]$^{2-}$. Thus the system presents inorganic ionic liquid like
structure.
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This paper shows the debugging facilities provided by the SLAM system. The
SLAM system includes i) a specification language that integrates algebraic
specifications and model-based specifications using the object oriented model.
Class operations are defined by using rules each of them with logical pre and
postconditions but with a functional flavour. ii) A development environment
that, among other features, is able to generate readable code in a high level
object oriented language. iii) The generated code includes (part of) the pre
and postconditions as assertions, that can be automatically checked in the
debug mode execution of programs. We focus on this last aspect.
The SLAM language is expressive enough to describe many useful properties and
these properties are translated into a Prolog program that is linked (via an
adequate interface) with the user program. The debugging execution of the
program interacts with the Prolog engine which is responsible for checking
properties.
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We investigate determinacy of delay games with Borel winning conditions,
infinite-duration two-player games in which one player may delay her moves to
obtain a lookahead on her opponent's moves.
First, we prove determinacy of such games with respect to a fixed evolution
of the lookahead. However, strategies in such games may depend on information
about the evolution. Thus, we introduce different notions of universal
strategies for both players, which are evolution-independent, and determine the
exact amount of information a universal strategy needs about the history of a
play and the evolution of the lookahead to be winning. In particular, we show
that delay games with Borel winning conditions are determined with respect to
universal strategies. Finally, we consider decidability problems, e.g., "Does a
player have a universal winning strategy for delay games with a given winning
condition?", for omega-regular and omega-context-free winning conditions.
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The origin of stellar-mass black hole mergers discovered through
gravitational waves is being widely debated. Mergers in the disks of active
galactic nuclei (AGN) represent a promising source of origin, with possible
observational clues in the gravitational wave data. Beyond gravitational waves,
a unique signature of AGN-assisted mergers is electromagnetic emission from the
accreting black holes. Here we show that jets launched by accreting black holes
merging in an AGN disk can be detected as peculiar transients by infrared,
optical, and X-ray observatories We further show that this emission mechanism
can explain the possible associations between gravitational wave events and the
optical transient ZTF19abanrhr and the proposed gamma-ray counterparts
GW150914-GBM and LVT151012-GBM. We demonstrate how these associations, if
genuine, can be used to reconstruct the properties of these events'
environments. Searching for infrared and X-ray counterparts to similar
electromagnetic transients in the future, once host galaxies are localized by
optical observations, could provide a smoking gun signature of the mergers' AGN
origin.
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Many people are aware of the theory of elastic fracture originated by AA
Griffith, and although Griffith used the theorem of minimum potential energy
most people seem unaware of the broader implications of this theorem. If it is
set within its classical mechanics roots, it is clear that it is a restricted
form of a Lagrangian.
In advanced texts on fracture cracks are treated as dynamic entities, and the
role of stress waves is clearly articulated. However, in most non-advanced
texts on fracture and fatigue the role of stress waves are either not included
or not emphasised, often leading to a possible misunderstanding of the
fundamentals of fracture.
What is done here is to extend Griffiths approach by setting it within the
concept of Stationary Action, and introducing a quasi-static stress wave
unloading model, which connects the energy release mechanism with the stress
field. This leads to a definition of a dynamic stress intensity factor, and
this model is then applied to fatigue of perfectly elastic and elastic-plastic
materials to include crack tip plasticity.
The results for the Griffiths crack and the dynamic case are retrodiction, to
establish the validity of the methods used. The extension to fatigue gives
significant new results, which show that for elastic-plastic materials the
influence of the maximum stress in the cycle as a fraction of the yield stress,
called the yield stress ratio, has not been recognised. The new form of the
fatigue crack growth relationship derived answers many of the long standing
questions about the Paris Law.
|
A novel channel representation for a two-hop decentralized wireless relay
network (DWRN) is proposed, where the relays operate in a completely
distributive fashion. The modeling paradigm applies an analogous approach to
the description method for a double-directional multipath propagation channel,
and takes into account the finite system spatial resolution and the extended
relay listening/transmitting time. Specifically, the double-directional
information azimuth spectrum (IAS) is formulated to provide a compact
representation of information flows in a DWRN. The proposed channel
representation is then analyzed from a geometrically-based statistical modeling
perspective. Finally, we look into the problem of relay network tomography
(RNT), which solves an inverse problem to infer the internal structure of a
DWRN by using the instantaneous doubledirectional IAS recorded at multiple
measuring nodes exterior to the relay region.
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We present new techniques for inertial-sensing atom interferometers which
produce multiple phase measurements per experimental cycle. With these
techniques, we realize two types of multiport measurements, namely quadrature
phase detection and real-time systematic phase cancellation, which address
challenges in operating high-sensitivity cold-atom sensors in mobile and field
applications. We confirm experimentally the increase in sensitivity due to
quadrature phase detection in the presence of large phase uncertainty, and
demonstrate suppression of systematic phases on a single shot basis.
|
We say that a nonselfadjoint operator algebra is partly free if it contains a
free semigroup algebra. Motivation for such algebras occurs in the setting of
what we call free semigroupoid algebras. These are the weak operator topology
closed algebras generated by the left regular representations of semigroupoids
associated with finite or countable directed graphs. We expand our analysis of
partly free algebras from previous work and obtain a graph-theoretic
characterization of when a free semigroupoid algebra with countable graph is
partly free. This analysis carries over to norm closed quiver algebras. We also
discuss new examples for the countable graph case.
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We introduce an approximation scheme to perform an analytic study of the
oscillation phenomena in a pedagogical and comprehensive way. By using Gaussian
wave packets, we show that the oscillation is bounded by a time-dependent
vanishing function which characterizes the slippage between the mass-eigenstate
wave packets. We also demonstrate that the wave packet spreading represents a
secondary effect which plays a significant role only in the non-relativistic
limit. In our analysis, we note the presence of a new time-dependent phase and
calculate how this additional term modifies the oscillating character of the
flavor conversion formula. Finally, by considering Box and Sine wave packets we
study how the choice of different functions to describe the particle
localization changes the oscillation probability.
|
It is demonstrated that an emission of collinear photons by the polarized
initial electron in elastic electron-proton polarization transfer scattering
leads to an apparent shifting of real events with small momentum transfer into
the data sample with large momentum transfer. Effectively this shows a fictive
enhancement of the cross section at large momentum transfer. However, the
enhancement is different for transverse and longitudinal polarizations of the
recoil proton. The former is responsible for a deformation of results when
extracting the proton electromagnetic form factors ratio from the data on
electron-proton polarization transfer scattering. Nevertheless, this effect
does not explain the suppression of the Dirac form factor at large momentum
transfer completely.
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Recent experiments have demonstrated that dynein motor exhibits catch bonding
behaviour, in which the unbinding rate of a single dynein decreases with
increasing force, for a certain range of force. Motivated by these experiments,
we propose a model for catch bonding in dynein using a threshold force bond
deformation (TFBD) model wherein catch bonding sets in beyond a critical
applied load force. We study the effect of catch bonding on unidirectional
transport properties of cellular cargo carried by multiple dynein motors within
the framework of this model. We find catch bonding can result in dramatic
changes in the transport properties, which are in sharp contrast to kinesin
driven unidirectional transport, where catch bonding is absent. We predict
that, under certain conditions, the average velocity of the cellular cargo can
actually increase as applied load is increased. We characterize the transport
properties in terms of a velocity profile phase plot in the parameter space of
the catch bond strength and the stall force of the motor. This phase plot
yields predictions that may be experimentally accessed by suitable
modifications of motor transport and binding properties. Our work necessitates
a reexamination of existing theories of collective bidirectional transport of
cellular cargo where the catch bond effect of dynein described in this paper is
expected to play a crucial role.
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We study the non-equilibrium pattern formation that emerges when magnetically
repelling colloids, trapped by optical tweezers, are abruptly released, forming
colloidal explosions. For multiple colloids in a single trap we observe a
pattern of expanding concentric rings. For colloids individually trapped in a
line, we observe explosions with a zigzag pattern that persists even when
magnetic interactions are much weaker than those that break the linear symmetry
in equilibrium. Theory and computer simulations quantitatively describe these
phenomena both in and out of equilibrium. An analysis of the mode spectrum
allows us to accurately quantify the non-harmonic nature of the optical traps.
Colloidal explosions provide a new way to generate well-characterized
non-equilibrium behaviour in colloidal systems.
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In this paper we study a type of stochastic McKean-Vlasov equations with
non-Lipschitz coefficients. Firstly, by an Euler-Maruyama approximation
existence of its weak solutions is proved. And then we observe pathwise
uniqueness of its weak solutions. Finally, it is shown that the Euler-Maruyama
approximation has an optimal strong convergence rate.
|
Scanning fluorescence correlation spectroscopy (SFCS) with a scan path
perpendicular to the membrane plane was introduced to measure diffusion and
interactions of fluorescent components in free standing biomembranes. Using a
confocal laser scanning microscope (CLSM) the open detection volume is moved
laterally with kHz frequency through the membrane and the photon events are
continuously recorded and stored in a file. While the accessory hardware
requirements for a conventional CLSM are minimal, data evaluation can pose a
bottleneck. The photon events must be assigned to each scan, in which the
maximum signal intensities have to be detected, binned, and aligned between the
scans, in order to derive the membrane related intensity fluctuations of one
spot. Finally, this time-dependent signal must be correlated and evaluated by
well known FCS model functions. Here we provide two platform independent, open
source software tools (PyScanFCS and PyCorrFit) that allow to perform all of
these steps and to establish perpendicular SFCS in its one- or two-focus as
well as its single- or dual-colour modality.
|
We have mapped the dense gas distribution and dynamics in the NW region of
the Serpens molecular cloud in the CS(2-1) and N2H+(1-0) lines and 3 mm
continuum using the FCRAO telescope and BIMA interferometer. 7 continuum
sources are found. The N2H+ spectra are optically thin and fits to the 7
hyperfine components are used to determine the distribution of velocity
dispersion. 8 cores, 2 with continuum sources, 6 without, lie at a local
linewidth minimum and optical depth maximum. The CS spectra are optically thick
and generally self-absorbed over the full 0.2 pc extent of the map. We use the
line wings to trace outflows around at least 3, and possibly 4, of the
continuum sources, and the asymmetry in the self-absorption as a diagnostic of
relative motions between core centers and envelopes. The quiescent regions with
low N2H+ linewidth tend to have more asymmetric CS spectra than the spectra
around the continuum sources indicating higher infall speeds. These regions
have typical sizes ~5000 AU, linewidths ~0.5 km/s, and infall speeds ~0.05
km/s. The correlation of CS asymmetry with N2H+ velocity dispersion suggests
that the inward flows of material that build up pre-protostellar cores are
driven at least partly by a pressure gradient rather than by gravity alone. We
discuss a scenario for core formation and eventual star forming collapse
through the dissipation of turbulence.
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We report a high-pressure single-crystal study of the non-centrosymmetric
superconductor YPtBi ($T_c = 0.77$ K). Magnetotransport measurements show a
weak metallic behavior with a carrier concentration $n \simeq 2.2 \times
10^{19}$ cm$^{-3}$. Resistivity measurements up to $p = 2.51$ GPa reveal
superconductivity is promoted by pressure. The reduced upper critical field
$B_{c2}(T)$ curves collapse onto a single curve, with values that exceed the
model values for spin-singlet superconductivity. The $B_{c2}$ data point to an
odd-parity component in the superconducting order parameter, in accordance with
predictions for non-centrosymmetric superconductors.
|
Modern abstractive summarization models often generate summaries that contain
hallucinated or contradictory information. In this paper, we propose a simple
but effective contrastive learning framework that incorporates recent
developments in reward learning and factuality metrics. Empirical studies
demonstrate that the proposed framework enables summarization models to learn
from feedback of factuality metrics using contrastive reward learning, leading
to more factual summaries by human evaluations. This suggests that further
advances in learning and evaluation algorithms can feed directly into providing
more factual summaries.
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We consider the nature of the fluid-solid phase transition in a polydisperse
mixture of hard spheres. For a sufficiently polydisperse mixture
crystallisation occurs with simultaneous fractionation. At the fluid-solid
boundary, a broad fluid diameter distribution is split into a number of
narrower fractions, each of which then crystallises. The number of crystalline
phases increases with the overall level of polydispersity. At high densities,
freezing is followed by a sequence of demixing transitions in the polydisperse
crystal.
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In this work we show that the classification performance of high-dimensional
structural MRI data with only a small set of training examples is improved by
the usage of dimension reduction methods. We assessed two different dimension
reduction variants: feature selection by ANOVA F-test and feature
transformation by PCA. On the reduced datasets, we applied common learning
algorithms using 5-fold cross-validation. Training, tuning of the
hyperparameters, as well as the performance evaluation of the classifiers was
conducted using two different performance measures: Accuracy, and Receiver
Operating Characteristic curve (AUC). Our hypothesis is supported by
experimental results.
|
Deep deraining networks consistently encounter substantial generalization
issues when deployed in real-world applications, although they are successful
in laboratory benchmarks. A prevailing perspective in deep learning encourages
using highly complex data for training, with the expectation that richer image
background content will facilitate overcoming the generalization problem.
However, through comprehensive and systematic experimentation, we discover that
this strategy does not enhance the generalization capability of these networks.
On the contrary, it exacerbates the tendency of networks to overfit specific
degradations. Our experiments reveal that better generalization in a deraining
network can be achieved by simplifying the complexity of the training
background images. This is because that the networks are ``slacking off''
during training, that is, learning the least complex elements in the image
background and degradation to minimize training loss. When the background
images are less complex than the rain streaks, the network will prioritize the
background reconstruction, thereby suppressing overfitting the rain patterns
and leading to improved generalization performance. Our research offers a
valuable perspective and methodology for better understanding the
generalization problem in low-level vision tasks and displays promising
potential for practical application.
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We present preliminary results from an experimental study of slow light in
anti-relaxation-coated Rb vapor cells, and describe the construction and
testing of such cells. The slow ground state decoherence rate allowed by coated
cell walls leads to a dual-structured electromagnetically induced transparency
(EIT) spectrum with a very narrow (<100 Hz) transparency peak on top of a broad
pedestal. Such dual-structure EIT permits optical probe pulses to propagate
with greatly reduced group velocity on two time scales. We discuss ongoing
efforts to optimize the pulse delay in such coated cell systems.
|
In this paper we have analyzed IUE high resolution spectra of the central
star (BD+602522) of the Bubble nebula. We discuss velocities of the different
regions along the line of sight to the bubble. We find that the Bubble Nebula
is younger (by a factor of 100) than the exciting star suggesting that either
the bubble is expanding into an inhomogenuous interstellar medium or that the
mechanics of the stellar wind are not fully understood.
|
Let $H$ be a pointed Hopf algebra over an algebraically closed field of
characteristic zero. If $H$ is a domain with finite Gelfand-Kirillov dimension
greater than or equal to two, then $H$ contains a Hopf subalgebra of
Gelfand-Kirillov dimension two.
|
The article analyzes the contribution of stochastic thermal fluctuations in
the attachment times of the immature T-cell receptor TCR:
peptide-major-histocompatibility-complex pMHC immunological synapse bond. The
key question addressed here is the following: how does a synapse bond remain
stabilized in the presence of high frequency thermal noise that potentially
equates to a strong detaching force? Focusing on the average time persistence
of an immature synapse, we show that the high frequency nodes accompanying
large fluctuations are counterbalanced by low frequency nodes that evolve over
longer time periods. Our analysis shows that such a behavior could be easily
explained from the fact that the survival probability distribution is governed
by two distinct phases, for the two different time regimes. The relatively
shorter time scales correspond to the cohesion:adhesion induced immature bond
formation whereas the larger time reciprocates the association:dissociation
regime leading to TCR:pMHC signaling. From an estimation of the bond survival
probability, we show that at shorter time scales, this probability
$P_{\Delta}(\tau)$ scales with time $\tau$ as an universal function of a
rescaled noise amplitude $\frac{D}{\Delta^2}$, such that $P_{\Delta}(\tau)\sim
\tau^{-(\frac{\Delta}{\sqrt{D}}+\frac{1}{2})}$, $\Delta$ being the distance
from the mean inter-membrane (T cell:Antigen Presenting Cell) separation
distance. The crossover from this shorter to a longer time regime leads to an
universality in the dynamics, at which point the survival probability shows a
different power-law scaling compared to the one at shorter time scales. In
biological terms, such a crossover indicates that the TCR:pMHC bond has a
survival probability with a slower decay rate than the longer LFA-1:ICAM-1 bond
justifying its stability.
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We introduce Parametric Linear Dynamic Logic (PLDL), which extends Linear
Dynamic Logic (LDL) by temporal operators equipped with parameters that bound
their scope. LDL was proposed as an extension of Linear Temporal Logic (LTL)
that is able to express all $\omega$-regular specifications while still
maintaining many of LTL's desirable properties like an intuitive syntax and a
translation into non-deterministic B\"uchi automata of exponential size. But
LDL lacks capabilities to express timing constraints. By adding parameterized
operators to LDL, we obtain a logic that is able to express all
$\omega$-regular properties and that subsumes parameterized extensions of LTL
like Parametric LTL and PROMPT-LTL. Our main technical contribution is a
translation of PLDL formulas into non-deterministic B\"uchi word automata of
exponential size via alternating automata. This yields a PSPACE model checking
algorithm and a realizability algorithm with doubly-exponential running time.
Furthermore, we give tight upper and lower bounds on optimal parameter values
for both problems. These results show that PLDL model checking and
realizability are not harder than LTL model checking and realizability.
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The starburst / AGN galaxy M82 was studied by Dahlem, Weaver and Heckman
using X-ray data from ROSAT and ASCA, as part of their X-ray survey of edge-on
starburst galaxies. They found seventeen unresolved hard-X-ray sources around
M82, in addition to its strong nuclear source, and other X-rays within the main
body of M82. We have measured optical point sources at these positions, and
have obtained redshifts of six candidates at the Keck I 10-m telescope, using
the low-resolution imaging spectrograph (LRIS). All six are highly compact
optical and X-ray objects with redshifts ranging from 0.111 to 1.086. They all
show emission lines. The three with the highest redshifts are clearly QSOs. The
others with lower redshifts may either be QSOs or compact emission-line
galaxies. In addition to these six there are nine QSOs lying very close to M82
which were discovered many years ago. There is no difference between optical
spectra of these latter QSOs, only two of which are known to be X-ray sources,
and the X-ray emitting QSOs. The redshifts of all fifteen range between 0.111
and 2.05. The large number of QSOs and their apparent association with ejected
matter from M82 suggest that they are physically associated with the galaxy,
and have large intrinsic redshift components. If this is correct, the absolute
magnitudes lie in the range -8 < M_v < -10. Also we speculate that the luminous
variable X-ray source which has been detected by Chandra in the main body of
M82 some 9 arcseconds from the center is another QSO in the process of ejection
from the nucleus, and propose some observational tests of this hypothesis.
|
Uncertainty relations are a distinctive characteristic of quantum theory that
impose intrinsic limitations on the precision with which physical properties
can be simultaneously determined. The modern work on uncertainty relations
employs \emph{entropic measures} to quantify the lack of knowledge associated
with measuring non-commuting observables. However, there is no fundamental
reason for using entropies as quantifiers; any functional relation that
characterizes the uncertainty of the measurement outcomes defines an
uncertainty relation. Starting from a very reasonable assumption of invariance
under mere relabelling of the measurement outcomes, we show that Schur-concave
functions are the most general uncertainty quantifiers. We then discover a
fine-grained uncertainty relation that is given in terms of the majorization
order between two probability vectors, \textcolor{black}{significantly
extending a majorization-based uncertainty relation first introduced in [M. H.
Partovi, Phys. Rev. A \textbf{84}, 052117 (2011)].} Such a vector-type
uncertainty relation generates an infinite family of distinct scalar
uncertainty relations via the application of arbitrary uncertainty quantifiers.
Our relation is therefore universal and captures the essence of uncertainty in
quantum theory.
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We study the \eta' N interaction within a chiral unitary approach which
includes \pi N, \eta N and related pseudoscalar meson-baryon coupled channels.
Since the SU(3) singlet does not contribute to the standard interaction and the
\eta' is mostly a singlet, the resulting scattering amplitude is very small and
inconsistent with experimental estimations of the \eta' N scattering length.
The additional consideration of vector meson-baryon states into the coupled
channel scheme, via normal and anomalous couplings of pseudoscalar to vector
mesons, enhances substantially the \eta' N amplitude. We also exploit the
freedom of adding to the Lagrangian a new term, allowed by the symmetries of
QCD, which couples baryons to the singlet meson of SU(3). Adjusting the unknown
strength to the \eta' N scattering length, we obtain predictions for the
elastic \eta' N --> \eta' N and inelastic \eta' N --> \eta N, \pi N, K\Lambda,
K\Sigma\ cross sections at low \eta' energies, and discuss their significance.
|
We establish a geometric quantization formula for a Hamiltonian action of a
compact Lie group acting on a noncompact symplectic manifold with proper moment
map.
|
Quick UDP Internet Connections (QUIC) is a recently proposed transport
protocol, currently being standardized by the Internet Engineering Task Force
(IETF). It aims at overcoming some of the shortcomings of TCP, while
maintaining the logic related to flow and congestion control, retransmissions
and acknowledgments. It supports multiplexing of multiple application layer
streams in the same connection, a more refined selective acknowledgment scheme,
and low-latency connection establishment. It also integrates cryptographic
functionalities in the protocol design. Moreover, QUIC is deployed at the
application layer, and encapsulates its packets in UDP datagrams. Given the
widespread interest in the new QUIC features, we believe that it is important
to provide to the networking community an implementation in a controllable and
isolated environment, i.e., a network simulator such as ns-3, in which it is
possible to test QUIC's performance and understand design choices and possible
limitations. Therefore, in this paper we present a native implementation of
QUIC for ns-3, describing the features we implemented, the main assumptions and
differences with respect to the QUIC Internet Drafts, and a set of examples.
|
We determine the limiting empirical singular value distribution for random
unitary matrices with Haar distribution and discrete Fourier transform (DFT)
matrices when a random set of columns and rows is removed.
|
We discuss how the geometric theory of differential equations can be used for
the numerical integration and visualisation of implicit ordinary differential
equations, in particular around singularities of the equation. The Vessiot
theory automatically transforms an implicit differential equation into a vector
field distribution on a manifold and thus reduces its analysis to standard
problems in dynamical systems theory like the integration of a vector field and
the determination of invariant manifolds. For the visualisation of
low-dimensional situations we adapt the streamlines algorithm of Jobard and
Lefer to 2.5 and 3 dimensions. A concrete implementation in Matlab is discussed
and some concrete examples are presented.
|
We consider the hydrodynamics for biaxial nematic phases described by a field
of orthonormal frame, which can be derived from a molecular-theory-based tensor
model. We prove the uniqueness of global weak solutions to the Cauchy problem
of the frame hydrodynamics in dimensional two. The proof is mainly based on the
suitable weaker energy estimates within the Littlewood--Paley analysis. We take
full advantage of the estimates of nonlinear terms with rotational derivatives
on $SO(3)$, together with cancellation relations and dissipative structures of
the biaxial frame system.
|
We present new one loop calculations that confirm the theorems of Joglekar
and Lee on the renormalization of composite operators. We do this by
considering physical matrix elements with the operators inserted at non-zero
momentum. The resulting IR singularities are regulated dimensionally. We show
that the physical matrix element of the BRST exact gauge variant operator which
appears in the energy- momentum tensor is zero. We then show that the physical
matrix elements of the classical energy-momentum tensor and the gauge invariant
twist two gluon operator are independent of the gauge fixing parameter. A
Sudakov factor appears in the latter cases. The universality of this factor and
the UV finiteness of the energy-momentum tensor provide another method of
finding the anomalous dimension of the gluon operator. We conjecture that this
method applies to higher loops and takes full advantage of the triangularity of
the mixing matrix.
|
The variational theory of the perfect hypermomentum fluid is developed. The
new type of the generalized Frenkel condition is considered. The Lagrangian
density of such fluid is stated, and the equations of motion of the fluid and
the Weyssenhoff-type evolution equation of the hypermomentum tensor are
derived. The expressions of the matter currents of the fluid (the canonical
energy-momentum 3-form, the metric stress-energy 4-form and the hypermomentum
3-form) are obtained. The Euler-type hydrodynamic equation of motion of the
perfect hypermomentum fluid is derived. It is proved that the motion of the
perfect fluid without hypermomentum in a metric-affine space coincides with the
motion of this fluid in a Riemann space.
|
In a recent paper, W. She, J. Yu and R. Feng reported the slight deformations
observed upon transmission of a light pulse through a short length of a silica
glass nano-filament. Relating the shape and magnitude of these deformations to
the momentum of the light pulse inside and outside the filament, these authors
concluded that, within the fiber, the photons carry the Abraham momentum. We
present an alternative evaluation of force and momentum in a system similar to
the experimental setup of She et al. Using precise numerical calculations that
take into account not only the electromagnetic momentum inside and outside the
filament, but also the Lorentz force exerted by a light pulse in its entire
path through the nano-waveguide, we conclude that the net effect should be a
pull (rather than a push) force on the end face of the nano-filament.
|
The transfer matrix of the XXZ open spin-1/2 chain with general integrable
boundary conditions and generic anisotropy parameter (q is not a root of unity
and |q|=1) is diagonalized using the representation theory of the q-Onsager
algebra. Similarly to the Ising and superintegrable chiral Potts models, the
complete spectrum is expressed in terms of the roots of a characteristic
polynomial of degree d=2^N. The complete family of eigenstates are derived in
terms of rational functions defined on a discrete support which satisfy a
system of coupled recurrence relations. In the special case of linear relations
between left and right boundary parameters for which Bethe-type solutions are
known to exist, our analysis provides an alternative derivation of the results
by Nepomechie et al. and Cao et al.. In the latter case the complete family of
eigenvalues and eigenstates splits in two sets, each associated with a
characteristic polynomial of degree $d< 2^N$. Numerical checks performed for
small values of $N$ support the analysis.
|
We present a simple method for the identification of weak signals associated
with gravitational wave events. Its application reveals a signal with the same
time lag as the GW150914 event in the released LIGO strain data with a
significance around $3.2\sigma$. This signal starts about 10 minutes before
GW150914 and lasts for about 45 minutes. Subsequent tests suggest that this
signal is likely to be due to external sources.
|
We present the dependence of $D$ production on the charged particle
multiplicity in proton-proton collisions at LHC energies. We show that, in a
framework of source coherence, the open charm production exhibits a growth with
the multiplicity which is stronger than linear in the high density domain. This
departure from linearity was previously observed in the $J/\psi$ inclusive data
from proton-proton collisions at 7 TeV and was successfully described in our
approach. Our assumption, the existence of coherence effects present in
proton-proton collisions at high energy, applies for high multiplicity
proton-proton collisions in the central rapidity region and should affect any
hard observable.
|
It is shown that the gauge field in Poincare-gauge theory of gravity consists
in two parts: the translational gauge field (t -field), which is generated by
the energy-momentum current of external fields, and the rotational gauge field
(r -field), which is generated by the sum of the angular and spin momentum
currents of external fields. In connection with this the physical field
generating by rotating masses should exist.
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We construct representations of the quantum algebras ~$U_{q{\bf q}}(gl(n))$
and ~$U_{q{\bf q}}(sl(n))$~ which are in duality with the multiparameter
quantum groups ~$GL_{q{\bf q}}(n)$, ~$SL_{q{\bf q}}(n)$,~ respectively. These
objects depend on ~$n(n-1)/2+1$~ deformation parameters ~$q,q_{ij}$ ($1\leq i
<j\leq n$) which is the maximal possible number in the case of $GL(n)$. The
representations are labelled by $n-1$ complex numbers ~$r_i$~ and are acting in
the space of formal power series of ~$n(n-1)/2$~ non-commuting variables. These
variables generate quantum flag manifolds of ~$GL_{q{\bf q}}(n)$, ~$SL_{q{\bf
q}}(n)$. The case $n=3$ is treated in more detail.
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Using the largest cosmological reionization simulation to-date (~24 billion
particles), we use the genus curve to quantify the topology of neutral hydrogen
distribution on scales > 1 Mpc as it evolves during cosmological reionization.
We find that the reionization process proceeds primarily in an inside-out
fashion, where higher density regions become ionized earlier than lower density
regions. There are four distinct topological phases: (1) Pre-reionization at z
~ 15, when the genus curve is consistent with a Gaussian density distribution.
(2) Pre-overlap at 10 < z < 15, during which the number of HII bubbles
increases gradually with time, until percolation of HII bubbles starts to take
effect, characterized by a very flat genus curve at high volume fractions. (3)
Overlap at 8 < z < 10, when large HII bubbles rapidly merge, manifested by a
precipitous drop in the amplitude of the genus curve. (4) Post-overlap at 6 < z
< 8, when HII bubbles have mostly overlapped and the genus curve is consistent
with a diminishing number of isolated neutral islands. After the end of
reionization (z < 6), the genus of neutral hydrogen is consistent with Gaussian
random phase, in agreement with observations.
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Simply restricting the computation to non-sensitive part of the data may lead
to inferences on sensitive data through data dependencies. Inference control
from data dependencies has been studied in the prior work. However, existing
solutions either detect and deny queries which may lead to leakage -- resulting
in poor utility, or only protects against exact reconstruction of the sensitive
data -- resulting in poor security. In this paper, we present a novel security
model called full deniability. Under this stronger security model, any
information inferred about sensitive data from non-sensitive data is considered
as a leakage. We describe algorithms for efficiently implementing full
deniability on a given database instance with a set of data dependencies and
sensitive cells. Using experiments on two different datasets, we demonstrate
that our approach protects against realistic adversaries while hiding only
minimal number of additional non-sensitive cells and scales well with database
size and sensitive data.
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We study the ultrametric random matrix ensemble, whose independent entries
have variances decaying exponentially in the metric induced by the tree
topology on $\mathbb{N}$, and map out the entire localization regime in terms
of eigenfunction localization and Poisson statistics. Our results complement
existing works on complete delocalization and random matrix universality,
thereby proving the existence of a phase transition in this model. In the
simpler case of the Rosenzweig-Porter model, the analysis yields a complete
characterization of the transition in the local statistics. The proofs are
based on the flow of the resolvents of matrices with a random diagonal
component under Dyson Brownian motion, for which we establish submicroscopic
stability results for short times. These results go beyond norm-based
continuity arguments for Dyson Brownian motion and complement the existing
analysis after the local equilibration time.
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We examine single chargino production in conjunction with R-parity lepton
number violation in future lepton-lepton collisions. Present bounds on R-parity
violating couplings allow for a production cross section of the order of
${\cal{O}} (10 {fb})$ for a wide range of sneutrino and chargino masses.
Scenarios of chargino decay which lead to purely leptonic signals in the final
state and without missing energy are also discussed.
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Multi-wavelength observations with TeV photons are an essential diagnostic
tool to study the physics of TeV sources. The complex variability of blazars,
however (timescales from years down to minutes, with different patterns and SED
behaviours), requires a great effort on simultaneous campaigns, which should be
performed possibly over several days. Spectral information is essential, and
now with the new TeV and X-ray telescopes it can be obtained on timescales less
than one hour. The insights from such observations can be tremendous, since
recent results have shown that the X-ray and TeV emissions do not always follow
the same behaviour, and flares can have different relations between rise and
decay times. Unfortunately, the strong pointing constraints of XMM do not allow
the full use of this satellite simultaneously with ground telescopes.
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For spoken dialog systems to conduct fluid conversational interactions with
users, the systems must be sensitive to turn-taking cues produced by a user.
Models should be designed so that effective decisions can be made as to when it
is appropriate, or not, for the system to speak. Traditional end-of-turn
models, where decisions are made at utterance end-points, are limited in their
ability to model fast turn-switches and overlap. A more flexible approach is to
model turn-taking in a continuous manner using RNNs, where the system predicts
speech probability scores for discrete frames within a future window. The
continuous predictions represent generalized turn-taking behaviors observed in
the training data and can be applied to make decisions that are not just
limited to end-of-turn detection. In this paper, we investigate optimal
speech-related feature sets for making predictions at pauses and overlaps in
conversation. We find that while traditional acoustic features perform well,
part-of-speech features generally perform worse than word features. We show
that our current models outperform previously reported baselines.
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We prove a theorem that generalizes Schmidt's Subspace Theorem in the context
of metric diophantine approximation. To do so we reformulate the Subspace
theorem in the framework of homogeneous dynamics by introducing and studying a
slope formalism and the corresponding notion of semistability for diagonal
flows.
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This paper presents a class of boundary integral equation methods for the
numerical solution of acoustic and electromagnetic time-domain scattering
problems in the presence of unbounded penetrable interfaces in two-spatial
dimensions. The proposed methodology relies on Convolution Quadrature (CQ)
methods in conjunction with the recently introduced Windowed Green Function
(WGF) method. As in standard time-domain scattering from bounded obstacles, a
CQ method of the user's choice is utilized to transform the problem into a
finite number of (complex) frequency-domain problems posed on the domains
involving penetrable unbounded interfaces. Each one of the frequency-domain
transmission problems is then formulated as a second-kind integral equation
that is effectively reduced to a bounded interface by means of the WGF
method---which introduces errors that decrease super-algebraically fast as the
window size increases. The resulting windowed integral equations can then be
solved by means of any (accelerated or unaccelerated) off-the-shelf Helmholtz
boundary integral equation solver capable of handling complex wavenumbers with
a large imaginary part. A high-order Nystr\"om method based on Alpert
quadrature rules is utilized here. A variety of numerical examples including
wave propagation in open waveguides as well as scattering from multiply layered
media demonstrate the capabilities of the proposed approach.
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Inclusive jet cross sections in Z/gamma^* events, with Z/gamma^* decaying
into an electron-positron pair, are measured as a function of jet transverse
momentum and jet multiplicity in ppbar collisions at sqrt{s} = 1.96 TeV with
the upgraded Collider Detector at Fermilab in Run II, based on an integrated
luminosity of 1.7 fb^-1. The measurements cover the rapidity region | yjet | <
2.1 and the transverse momentum range ptjet > 30 GeV/c. Next-to-leading order
perturbative QCD predictions are in good agreement with the measured cross
sections.
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Finding the set of nodes, which removed or (de)activated can stop the spread
of (dis)information, contain an epidemic or disrupt the functioning of a
corrupt/criminal organization is still one of the key challenges in network
science. In this paper, we introduce the generalized network dismantling
problem, which aims to find the set of nodes that, when removed from a network,
results in a network fragmentation into subcritical network components at
minimum cost. For unit costs, our formulation becomes equivalent to the
standard network dismantling problem. Our non-unit cost generalization allows
for the inclusion of topological cost functions related to node centrality and
non-topological features such as the price, protection level or even social
value of a node. In order to solve this optimization problem, we propose a
method, which is based on the spectral properties of a novel node-weighted
Laplacian operator. The proposed method is applicable to large-scale networks
with millions of nodes. It outperforms current state-of-the-art methods and
opens new directions in understanding the vulnerability and robustness of
complex systems.
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We report on a scheme for incorporating vertical radiative energy transport
into a fully relativistic, Kerr-metric model of optically thick, advective,
transonic alpha disks. Our code couples the radial and vertical equations of
the accretion disk. The flux was computed in the diffusion approximation, and
convection is included in the mixing-length approximation. We present the
detailed structure of this "two-dimensional" slim-disk model for alpha=0.01. We
then calculated the emergent spectra integrated over the disk surface. The
values of surface density, radial velocity, and the photospheric height for
these models differ by 20%-30% from those obtained in the polytropic,
height-averaged slim disk model considered previously. However, the emission
profiles and the resulting spectra are quite similar for both types of models.
The effective optical depth of the slim disk becomes lower than unity for high
values of the alpha parameter and for high accretion rates.
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Biomedical text summarization is a critical tool that enables clinicians to
effectively ascertain patient status. Traditionally, text summarization has
been accomplished with transformer models, which are capable of compressing
long documents into brief summaries. However, transformer models are known to
be among the most challenging natural language processing (NLP) tasks.
Specifically, GPT models have a tendency to generate factual errors, lack
context, and oversimplify words. To address these limitations, we replaced the
attention mechanism in the GPT model with a pointer network. This modification
was designed to preserve the core values of the original text during the
summarization process. The effectiveness of the Pointer-GPT model was evaluated
using the ROUGE score. The results demonstrated that Pointer-GPT outperformed
the original GPT model. These findings suggest that pointer networks can be a
valuable addition to EMR systems and can provide clinicians with more accurate
and informative summaries of patient medical records. This research has the
potential to usher in a new paradigm in EMR systems and to revolutionize the
way that clinicians interact with patient medical records.
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In this article, we study several problems related to virtual traces for
finite group actions on schemes of finite type over an algebraically closed
field. We also discuss applications to fixed point sets. Our results generalize
previous results obtained by Deligne, Laumon, Serre and others.
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Continuous word representations, trained on large unlabeled corpora are
useful for many natural language processing tasks. Popular models that learn
such representations ignore the morphology of words, by assigning a distinct
vector to each word. This is a limitation, especially for languages with large
vocabularies and many rare words. In this paper, we propose a new approach
based on the skipgram model, where each word is represented as a bag of
character $n$-grams. A vector representation is associated to each character
$n$-gram; words being represented as the sum of these representations. Our
method is fast, allowing to train models on large corpora quickly and allows us
to compute word representations for words that did not appear in the training
data. We evaluate our word representations on nine different languages, both on
word similarity and analogy tasks. By comparing to recently proposed
morphological word representations, we show that our vectors achieve
state-of-the-art performance on these tasks.
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It is shown that the renormalisation group (RG) equation can be viewed as an
equation for Lie transport of physical amplitudes along the integral curves
generated by the $\beta$-functions of a quantum field theory. The anomalous
dimensions arise from Lie transport of basis vectors on the space of couplings.
The RG equation can be interpreted as relating a particular diffeomorphism of
flat space-(time), that of dilations, to a diffeomorphism on the space of
couplings generated by the vector field associated with the $\beta$-functions.
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A mechanism for phonon Hall effect (PHE) in non-magnetic insulators under an
external magnetic field is theoretically studied. PHE is known in
(para)magnetic compounds, where the magnetic moments and spin-orbit interaction
play an essential role. In sharp contrast, we here show that a non-zero Berry
curvature of acoustic phonons is induced by an external magnetic field due to
the correction to the adiabatic Born-Oppenheimer approximation. This results in
the finite thermal Hall conductivity $\kappa_H$ in nonmagnetic band insulators.
Our estimate of $\kappa_H$ for a simple model gives $\kappa_H \sim 1.0\times
10^{-5} $[W/Km] at $ B=10 $[T] and $ T=150 $[K].
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We consider the finite temperature Casimir interaction between two Dirichlet
spheres in $(D+1)$-dimensional Minkowski spacetime. The Casimir interaction
free energy is derived from the zero temperature Casimir interaction energy via
the Matsubara formalism. In the high temperature region, the Casimir
interaction is dominated by the term with zero Matsubara frequency, and it is
known as the classical term since this term is independent of the Planck
constant $\hbar$. Explicit expression of the classical term is derived and it
is computed exactly using appropriate similarity transforms of matrices. We
then compute the small separation asymptotic expansion of this classical term
up to the next-to-leading order term. For the remaining part of the finite
temperature Casimir interaction with nonzero Matsubara frequencies, we obtain
its small separation asymptotic behavior by applying certain prescriptions to
the corresponding asymptotic expansion at zero temperature. This gives us a
leading term that is shown to agree precisely with the proximity force
approximation at any temperature. The next-to-leading order term at any
temperature is also derived and it is expressed as an infinite sum over
integrals. To obtain the asymptotic expansion at the low and medium temperature
regions, we apply the inverse Mellin transform techniques. In the low
temperature region, we obtain results that agree with our previous work on the
zero temperature Casimir interaction.
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