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Self-induced flavor conversions of supernova (SN) neutrinos have been
characterized in the spherically symmetric "bulb" model, reducing the neutrino
evolution to a one dimensional problem along a radial direction. We lift this
assumption, presenting a two-dimensional toy-model where neutrino beams are
launched in many different directions from a ring. We find that
self-interacting neutrinos spontaneously break the spatial symmetries of this
model. As a result the flavor content and the lepton number of the neutrino gas
would acquire seizable direction-dependent variations, breaking the coherent
behavior found in the symmetric case. This finding would suggest that the
previous results of the self-induced flavor evolution obtained in
one-dimensional models should be critically re-examined.
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Focused ion beam (FIB) microscopy suffers from source shot noise - random
variation in the number of incident ions in any fixed dwell time - along with
random variation in the number of detected secondary electrons per incident
ion. This multiplicity of sources of randomness increases the variance of the
measurements and thus worsens the trade-off between incident ion dose and image
accuracy. Time-resolved sensing combined with maximum likelihood estimation
from the resulting sets of measurements greatly reduces the effect of source
shot noise. Through Fisher information analysis and Monte Carlo simulations,
the reduction in mean-squared error or reduction in required dose is shown to
be by a factor approximately equal to the secondary electron yield. Experiments
with a helium ion microscope (HIM) are consistent with the analyses and suggest
accuracy improvement for a fixed source dose, or reduced source dose for a
desired imaging accuracy, by a factor of about 3.
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In the present paper, we study the dynamics of a nine compartmental
vector-host model for Zika virus infection where the predatory fish Gambusia
Affinis is introduced into the system to control the zika infection by preying
on the vector. The system has six practically feasible equilibrium points where
four of them are disease-free, and the rest are endemic. We discuss the
existence and stability conditions for the equilibria. We find that when sexual
transmission of zika comes to a halt then in absence of mosquitoes infection
cannot persist. Hence, one needs to eradicate mosquitoes to eradicate
infection. Moreover, we deduce that in the case of zika infection pushing the
basic reproduction number below unity is next to impossible. Therefore, O_0,
the mosquito survival threshold parameter, and O, the mosquito survival
threshold parameter with predation play a crucial role in getting rid of the
infection in respective cases since mosquitoes cannot survive when these are
less than unity. Sensitivity analysis shows the importance of reducing mosquito
biting rate and mutual contact rates between vector and host. It exhibits the
importance of increasing the natural mortality rate of vectors to reduce the
basic reproduction number. Numerical simulation shows that when the basic
reproduction number is close but greater than unity, the introduction of a
small amount of predatory fish Gambusia Affinis can completely swipe off the
infection. In case of high transmission or high basic reproduction number, this
fish increases the susceptible human population and keeps the infection under
control, hence, prohibiting it from becoming an epidemic.
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The branching fractions of Ds meson decays serve to normalize many
measurements of processes involving charm quarks. Using 586 pb^-1 of e+ e-
collisions recorded at a center of mass energy of 4.17 GeV, we determine
absolute branching fractions for 13 Ds decays in 16 reconstructed final states
with a double tag technique. In particular we make a precise measurement of the
branching fraction B(Ds -> K- K+ pi+) = (5.55 +- 0.14 +- 0.13)%, where the
uncertainties are statistical and systematic respectively. We find a
significantly reduced value of B(Ds -> pi+ pi0 eta') compared to the world
average, and our results bring the inclusively and exclusively measured values
of B(Ds -> eta' X)$ into agreement. We also search for CP-violating asymmetries
in Ds decays and measure the cross-section of e+ e- -> Ds* Ds at Ecm = 4.17
GeV.
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The multidimensional character of the hydrodynamics in core-collapse
supernova (CCSN) cores is a key facilitator of explosions. Unfortunately, much
of this work has necessarily been performed assuming axisymmetry and it remains
unclear whether or not this compromises those results. In this work, we present
analyses of simplified two- and three-dimensional CCSN models with the goal of
comparing the multidimensional hydrodynamics in setups that differ only in
dimension. Not surprisingly, we find many differences between 2D and 3D models.
While some differences are subtle and perhaps not crucial to understanding the
explosion mechanism, others are quite dramatic and make interpreting 2D CCSN
models problematic. In particular, we find that imposing axisymmetry
artificially produces excess power at the largest spatial scales, power that
has been deemed critical in the success of previous explosion models and has
been attributed solely to the standing accretion shock instability.
Nevertheless, our 3D models, which have an order of magnitude less power on
large scales compared to 2D models, explode earlier. Since we see explosions
earlier in 3D than in 2D, the vigorous sloshing associated with the large scale
power in 2D models is either not critical in any dimension or the explosion
mechanism operates differently in 2D and 3D. Possibly related to the earlier
explosions in 3D, we find that about 25% of the accreted material spends more
time in the gain region in 3D than in 2D, being exposed to more integrated
heating and reaching higher peak entropies, an effect we associate with the
differing characters of turbulence in 2D and 3D. Finally, we discuss a simple
model for the runaway growth of buoyant bubbles that is able to quantitatively
account for the growth of the shock radius and predicts a critical luminosity
relation.
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Codes over Galois rings have been studied extensively during the last three
decades. Negacyclic codes over $GR(2^a,m)$ of length $2^s$ have been
characterized: the ring $\mathcal{R}_2(a,m,-1)= \frac{GR(2^a,m)[x]}{\langle
x^{2^s}+1\rangle}$ is a chain ring. Furthermore, these results have been
generalized to $\lambda$-constacyclic codes for any unit $\lambda$ of the form
$4z-1$, $z\in GR(2^a, m)$. In this paper, we study more general cases and
investigate all cases where $\mathcal{R}_p(a,m,\gamma)=
\frac{GR(p^a,m)[x]}{\langle x^{p^s}-\gamma \rangle}$ is a chain ring. In
particular, necessary and sufficient conditions for the ring
$\mathcal{R}_p(a,m,\gamma)$ to be a chain ring are obtained. In addition, by
using this structure we investigate all $\gamma$-constacyclic codes over
$GR(p^a,m)$ when $\mathcal{R}_p(a,m,\gamma)$ is a chain ring. Necessary and
sufficient conditions for the existence of self-orthogonal and self-dual
$\gamma$-constacyclic codes are also provided. Among others, for any prime $p$,
the structure of $\mathcal{R}_p(a,m,\gamma)=\frac{GR(p^a,m)[x]}{\langle
x^{p^s}-\gamma\rangle}$ is used to establish the Hamming and homogeneous
distances of $\gamma$-constacyclic codes.
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The elicitation of end-users' human values - such as freedom, honesty,
transparency, etc. - is important in the development of software systems. We
carried out two preliminary Q-studies to understand (a) the general human value
opinion types of eHealth applications (apps) end-users (b) the eHealth domain
human value opinion types of eHealth apps end-users (c) whether there are
differences between the general and eHealth domain opinion types. Our early
results show three value opinion types using generic value instruments: (1)
fun-loving, success-driven and independent end-user, (2) security-conscious,
socially-concerned, and success-driven end-user, and (3) benevolent,
success-driven, and conformist end-user Our results also show two value opinion
types using domain-specific value instruments: (1) security-conscious,
reputable, and honest end-user, and (2) success-driven, reputable and
pain-avoiding end-user. Given these results, consideration should be given to
domain context in the design and application of values elicitation instruments.
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We proceed to investigate the solutions of generalized supergravity equations
(GSE) in three dimensions. Our candidate is the metric of BTZ black hole. It is
shown that only the cases with $J=M=0$ and $J=0,~ M\neq 0$ of the BTZ metric
satisfy the GSE. In the former, we find a family of solutions including the
field strength $H_{_{r \varphi t}}=2r/l$, the cosmological constant
$\Lambda=-1/l^2$, one-form $Z_{\mu}$ and a vector field which is obtained to be
a linear combination of the directions of the time translation and rotational
symmetries. In the latter, the solutions possess the same field strength as
before, while the cosmological constant $\Lambda$, one-form $Z_{\mu}$ and
vector field $I$ will be different from the previous case. Finally, we show
that the charged black string solution found by Horne and Horowitz, which is
Abelian T-dual to the the BTZ black hole solution, can be considered as a
solution for the GSE.
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Detailed differential measurements of the elliptic flow for particles
produced in Au+Au and Cu+Cu collisions at sqrt(s_NN) = 200 GeV are presented.
Predictions from perfect fluid hydrodynamics for the scaling of the elliptic
flow coefficient v_2 with eccentricity, system size and transverse energy are
tested and validated. For transverse kinetic energies KE_T ~ m_T-m up to ~1
GeV, scaling compatible with the hydrodynamic expansion of a thermalized fluid
is observed for all produced particles. For large values of KE_T, the mesons
and baryons scale separately. A universal scaling for the flow of both mesons
and baryons is observed for the full transverse kinetic energy range of the
data when quark number scaling is employed. In both cases the scaling is more
pronounced in terms of KE_T rather than transverse momentum.
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The properties of the coexisting bulk gas and liquid phases of a polydisperse
fluid depend not only on the prevailing temperature, but also on the overall
parent density. As a result, a polydisperse fluid near a wall will exhibit
density-driven wetting transitions inside the coexistence region. We propose a
likely topology for the wetting phase diagram, which we test using Monte Carlo
simulations of a model polydisperse fluid at an attractive wall, tracing the
wetting line inside the cloud curve and identifying the relationship to
prewetting.
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Imitation learning from observation (LfO) is more preferable than imitation
learning from demonstration (LfD) due to the nonnecessity of expert actions
when reconstructing the expert policy from the expert data. However, previous
studies imply that the performance of LfO is inferior to LfD by a tremendous
gap, which makes it challenging to employ LfO in practice. By contrast, this
paper proves that LfO is almost equivalent to LfD in the deterministic robot
environment, and more generally even in the robot environment with bounded
randomness. In the deterministic robot environment, from the perspective of the
control theory, we show that the inverse dynamics disagreement between LfO and
LfD approaches zero, meaning that LfO is almost equivalent to LfD. To further
relax the deterministic constraint and better adapt to the practical
environment, we consider bounded randomness in the robot environment and prove
that the optimizing targets for both LfD and LfO remain almost same in the more
generalized setting. Extensive experiments for multiple robot tasks are
conducted to empirically demonstrate that LfO achieves comparable performance
to LfD. In fact, most common robot systems in reality are the robot environment
with bounded randomness (i.e., the environment this paper considered). Hence,
our findings greatly extend the potential of LfO and suggest that we can safely
apply LfO without sacrificing the performance compared to LfD in practice.
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By utilizing different communication channels, such as verbal language,
gestures or facial expressions, virtually embodied interactive humans hold a
unique potential to bridge the gap between human-computer interaction and
actual interhuman communication. The use of virtual humans is consequently
becoming increasingly popular in a wide range of areas where such a natural
communication might be beneficial, including entertainment, education, mental
health research and beyond. Behind this development lies a series of
technological advances in a multitude of disciplines, most notably natural
language processing, computer vision, and speech synthesis. In this paper we
discuss a Virtual Human Journalist, a project employing a number of novel
solutions from these disciplines with the goal to demonstrate their viability
by producing a humanoid conversational agent capable of naturally eliciting and
reacting to information from a human user. A set of qualitative and
quantitative evaluation sessions demonstrated the technical feasibility of the
system whilst uncovering a number of deficits in its capacity to engage users
in a way that would be perceived as natural and emotionally engaging. We argue
that naturalness should not always be seen as a desirable goal and suggest that
deliberately suppressing the naturalness of virtual human interactions, such as
by altering its personality cues, might in some cases yield more desirable
results.
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In a fibre bundle, natural derivatives of a section are defined as tangent
vector fields on the image of a section of the fibre bundle. A local extension
to vector fields in the tangent bundle leads to a direct proof of the formula
expressing the curvature of a connection in terms of covariant derivatives. The
result is based on a tensoriality argument and extends to nonlinear connections
on fibre bundles a well-known formula for linear connections on vector bundles.
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LaCrGe$_3$ is an itinerant, metallic ferromagnet with a Curie temperature
($T_C$) of $\sim$ 86 K. Whereas LaCrGe$_3$ has been studied extensively as a
function of pressure as an example of avoided ferromagnetic quantum
criticality, questions about its ambient pressure ordered state remain;
specifically, whether there is a change in the nature of the ferromagnetically
ordered state below $T_C$ $\sim$ 86 K. We present anisotropic $M$($H$)
isotherms, coupled with anisotropic AC susceptibility data, and demonstrate
that LaCrGe$_3$ has a remarkable, low temperature coercivity associated with
exceptionally sharp, complete magnetization reversals to and from fully
polarized states. This coercivity is temperature dependent, it drops to zero in
the 40 - 55 K region and reappears in the 70 - 85 K regions. At low
temperatures LaCrGe$_3$ has magnetization loops and behavior that has
previously associated with micromagnetic/nanocrystalline materials, not bulk,
macroscopic samples.
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We solve the Jones conjecture, which states that the exponent sum in a
minimal braid representation of a knot in S^3 is a knot invariant, by proving a
generalized version of the original one. We apply contact geometry to study
this problem in knot theory.
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Higher-order scalar field models in two dimensions, including the $\phi^8$
model, have been researched. It has been shown that for some special cases of
the minima positions of the potential, the explicit kink solutions can be
found. However, in physical applications, it is very important to know all the
explicit solutions of a model for any minima position. In the present study,
with the help of some deformation functions, we have shown that higher-order
scalar field theories can be obtained with explicit kinks. In particular, we
introduced two deformation functions that, when applied to the well known
$\phi^4$ and $\phi^6$ models, produce modified $\phi^8$ and $\phi^{10}$ models,
respectively, with all their explicit kink-like solutions which depend on a
single parameter. Since this parameter controls the position of the minima of
the potential, we have found interesting new solutions in many distinct cases.
We have also studied the kink mass, the behavior of the excitation spectra and
several kink-antikink collisions for these two new modified models. The
collision outcome is determined by the initial configuration, specifically the
sequence in which the kink-antikink and antikink-kink pairings emerge. Another
interesting finding is the suppression of resonance windows, which may be
explained by the presence of a set of internal modes in the model.
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Hyperplane Arrangements of rank $3$ admitting an unbalanced Ziegler
restriction are known to fulfill Terao's conjecture. This long-standing
conjecture asks whether the freeness of an arrangement is determined by its
combinatorics. In this note, we prove that arrangements that admit a locally
heavy flag satisfy Terao's conjecture which is a generalization of the
statement above to arbitrary dimension. To this end, we extend results
characterizing the freeness of multiarrangements with a heavy hyperplane to
those satisfying the weaker notion of a locally heavy hyperplane. As a
corollary, we give a new proof that irreducible arrangements with a generic
hyperplane are totally non-free. In another application, we show that an
irreducible multiarrangement of rank $3$ with at least two locally heavy
hyperplanes is not free.
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An efficient and fair node scheduling is a big challenge in multihop wireless
networks. In this work, we propose a distributed node scheduling algorithm,
called Local Voting. The idea comes from the finding that the shortest delivery
time or delay is obtained when the load is equalized throughout the network.
Simulation results demonstrate that Local Voting achieves better performance in
terms of average delay, maximum delay, and fairness compared to several
representative scheduling algorithms from the literature. Despite being
distributed, Local Voting has a very close performance to a centralized
algorithm that is considered to have the optimal performance.
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In this short note we classify the Cartan subalgebras in all von Neumann
algebras associated with graph product groups and their free ergodic measure
preserving actions on probability spaces.
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The increasing complexity of Internet-of-Things (IoT) applications and
near-sensor processing algorithms is pushing the computational power of
low-power, battery-operated end-node systems. This trend also reveals growing
demands for high-speed and energy-efficient inter-chip communications to manage
the increasing amount of data coming from off-chip sensors and memories. While
traditional micro-controller interfaces such as SPIs cannot cope with tight
energy and large bandwidth requirements, low-voltage swing transceivers can
tackle this challenge thanks to their capability to achieve several Gbps of the
communication speed at milliwatt power levels. However, recent research on
high-speed serial links focused on high-performance systems, with a power
consumption significantly larger than the one of low-power IoT end-nodes, or on
stand-alone designs not integrated at a system level. This paper presents a
low-swing transceiver for the energy-efficient and low power chip-to-chip
communication fully integrated within an IoT end-node System-on-Chip,
fabricated in CMOS 65nm technology. The transceiver can be easily controlled
via a software interface; thus, we can consider realistic scenarios for the
data communication, which cannot be assessed in stand-alone prototypes. Chip
measurements show that the transceiver achieves 8.46x higher energy efficiency
at 15.9x higher performance than a traditional microcontroller interface such
as a single-SPI.
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The ability to discriminate between simultaneously occurring noise sources in
the local environment of semiconductor InGaAs quantum dots, such as electric
and magnetic field fluctuations, is key to understanding their respective
dynamics and their effect on quantum dot coherence properties. We present a
discriminatory approach to all-optical sensing based on two-color resonance
fluorescence of a quantum dot charged with a single electron. Our measurements
show that local magnetic field fluctuations due to nuclear spins in the absence
of an external magnetic field are described by two correlation times, both in
the microsecond regime. The nuclear spin bath dynamics show a strong dependence
on the strength of resonant probing, with correlation times increasing by a
factor of four as the optical transition is saturated. We interpret the
behavior as motional averaging of both the Knight field of the resident
electron spin and the hyperfine-mediated nuclear spin-spin interaction due to
optically-induced electron spin flips.
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Unsupervised cross-modality domain adaptation is a challenging task in
medical image analysis, and it becomes more challenging when source and target
domain data are collected from multiple institutions. In this paper, we present
our solution to tackle the multi-institutional unsupervised domain adaptation
for the crossMoDA 2023 challenge. First, we perform unpaired image translation
to translate the source domain images to the target domain, where we design a
dynamic network to generate synthetic target domain images with controllable,
site-specific styles. Afterwards, we train a segmentation model using the
synthetic images and further reduce the domain gap by self-training. Our
solution achieved the 1st place during both the validation and testing phases
of the challenge. The code repository is publicly available at
https://github.com/MedICL-VU/crossmoda2023.
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Understanding online communities requires an appreciation of both structure
and culture. But basic questions remain difficult to pose. How do these facets
interact and drive each other? Using data on the membership and governance
styles of 5,000 small-scale online communities, we construct empirical measures
for cross-server similarities in institutional structure and culture to explore
the influence of institutional environment on their culture, and the influence
of culture on their institutional environment. To establish the influence of
culture and institutions on each other, we construct networks of communities,
linking those that are more similar either in their members or governance. We
then use network analysis to assess the causal relationships between shared
culture and institutions. Our result shows that while effects in both
directions are evident, there is a much stronger role for institutions on
culture than culture on institutions. These processes are evident within
administrative and informational type rules.
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In this study, the mechanical behavior of single tau, dimerized tau, and
tau-microtubule interface subjected to high strain rate is investigated by
molecular dynamics simulation.
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Let $Y \subset \P^r$ be a normal nondegenerate m-dimensional subvariety and
let $\sigma(Y)$ denote the maximum dimension of a subvariety $Z \subset
Y_{smooth}$ such that $Z$ contains a generic point of some divisor on $Y$ and
the tangent planes $T_y Y$ for all $y \in Z$ are contained in a fixed
hyperplane. In this article we study the double locus $D \subset $Y$ of its
generic projection to $\P^{r-1}$, proving that if the secant variety of $Y$ is
the whole space and $\sigma(Y) < 2m - r + 1$, then $D$ is irreducible. Applying
Zak's Tangency theorem we deduce the irreducibility of $D$ when $m > 2(r-1)/3$.
The latter implies a version of Zak's Linear Normality theorem.
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We introduce and carefully define an entire class of field theories based on
non-standard spinors. Their dominant interaction is via the gravitational field
which makes them naturally dark; we refer to them as Dark Spinors. We provide a
critical analysis of previous proposals for dark spinors noting that they
violate Lorentz invariance. As a working assumption we restrict our analysis to
non-standard spinors which preserve Lorentz invariance, whilst being non-local
and explicitly construct such a theory. We construct the complete
energy-momentum tensor and derive its components explicitly by assuming a
specific projection operator. It is natural to next consider dark spinors in a
cosmological setting. We find various interesting solutions where the spinor
field leads to slow roll and fast roll de Sitter solutions. We also analyse
models where the spinor is coupled conformally to gravity, and consider the
perturbations and stability of the spinor.
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A careful analysis of the maximally extended metrics of Schwarzschild
manifold shows that the original Schwarzschild's solution (1916) and
Brillouin's solution (1923) are the only ones that are adequate from the
physical standpoint. Contrary to the other maximally extended metrics, they
represent faithfully the gravity field created by the mass-point.
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A large body of experimental work on the microstructure and dynamics of
simplifiedindustrial nanocomposites made of disordered silica filler in a
styrene-butadiene matrixby solid-phase mixing is regrouped and critically
discussed in this feature article. Recentresults encompass systems with varying
polymer mass, grafting functionality, and fillercontent. They have been
obtained by simulation-based structural modelling of nanoparticleaggregate size
and mass deduced from small-angle scattering and transmission
electronmicroscopy. Our model has been validated by independent swelling
experiments.Comparison of structurally-close nanocomposites of widely different
chain mass led tothe identification of a unique structure-determining
parameter, the grafting density, aswell as to a unified picture of aggregate
formation mechanisms in complex nanocompositesduring mixing. In addition,
low-field proton NMR allowed for the characterization ofdynamically slowed-down
('glassy') polymer layers, which were shown not to dominatethe rheological
response, unlike the structural contribution. Finally, broadband
dielectricspectroscopy was used in an innovative manner to identify filler
percolation -- also identifiedby rheology -- via dynamics along filler
surfaces.
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We report here the results of operation of a torsion balance with a period of
$\sim 1.27 \times 10^4$ s. The analysis of data collected over a period of
$\sim$115 days shows that the difference in the accelerations towards the
Galactic Center of test bodies made of aluminum and quartz was $(0.61 \pm 1.27)
\times 10^{-15} \, \mathrm{ m \, s}^{-2}$. This sets a bound on the violation
of the equivalence principle by forces exerted by Galactic dark matter which is
expressed by the E\"otv\"os parameter $\eta_{DM} = (1.32 \pm 2.68) \times
10^{-5}$, a significant improvement upon earlier bounds.
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We compare the luminosity function and rate inferred from the BATSE short
hard bursts (SHBs) peak flux distribution with the redshift and luminosity
distributions of SHBs observed by Swift/HETE II. The Swift/HETE II SHB sample
is incompatible with SHB population that follows the star formation rate.
However, it is compatible with a distribution of delay times after the SFR.
This would be the case if SHBs are associated with binary neutron star mergers.
The implied SHB rates that we find range from \sim 8 to \sim
30h_{70}^3Gpc^{-3}yr^{-1}. This rate is a much higher than what was previously
estimated and, when beaming is taken into account, it is comparable to the rate
of neutron star mergers estimated from statistics of binary pulsars. If GRBs
are produced in mergers the implied rate practically guarantees detection by
LIGO II and possibly even by LIGO I, if we are lucky. Our analysis, which is
based on observed short hard burst is limited to bursts with luminosities above
10^{49}erg/sec. Weaker bursts may exist but if so they are hardly detected by
BATSE or Swift and hence their rate is very weakly constrained by current
observations. Thus the rate of mergers that lead to a detection of a
gravitational radiation signal might be even higher.
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Let $f\left(K\right)$ be the number of unramified extensions $L/K$ of a
quadratic number field $K$ with $\mathrm{Gal}\left(L/K\right)=H$ and
$\mathrm{Gal}\left(L/\mathbb{Q}\right)=G$ where $G$ is a central extension of
$\mathbb{F}_{2}^{n}$ by $\mathbb{F}_{2}$. We find a function $g\left(K\right)$
such that $f/g$ has finite moments and a distribution on its values. We show
this distribution is a point mass when $H$ is non-abelian and the Cohen-Lenstra
distribution when $H$ is abelian, despite the fact that the set of values of
$f/g$ do not form a discrete set. We prove an explicit formula for $f$ as well
as a refined counting function with local conditions. We also determine
correlations of such counting functions for different groups $G$. Lastly we
formulate a conjecture about moments and correlations for any pair of 2-groups
$\left(G,H\right)$.
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Over the past several years, across the globe, there has been an increase in
people seeking care in emergency departments (EDs). ED resources, including
nurse staffing, are strained by such increases in patient volume. Accurate
forecasting of incoming patient volume in emergency departments (ED) is crucial
for efficient utilization and allocation of ED resources. Working with a
suburban ED in the Pacific Northwest, we developed a tool powered by machine
learning models, to forecast ED arrivals and ED patient volume to assist
end-users, such as ED nurses, in resource allocation. In this paper, we discuss
the results from our predictive models, the challenges, and the learnings from
users' experiences with the tool in active clinical deployment in a real world
setting.
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We report the results of the first sensitive L-band (3.5 micron) survey of
the intermediate age (2.5 - 30 Myr) clusters NGC 2264, NGC 2362 and NGC 1960.
We use JHKL colors to obtain a census of the circumstellar disk fractions in
each cluster. We find disk fractions of 52% +/- 10%, 12% +/- 4% and 3% +/- 3%
for the three clusters respectively. Together with our previously published
JHKL investigations of the younger NGC 2024, Trapezium and IC 348 clusters, we
have completed the first systematic and homogenous survey for circumstellar
disks in a sample of young clusters that both span a significant range in age
(0.3 - 30 Myr) and contain statistically significant numbers of stars whose
masses span nearly the entire stellar mass spectrum. Analysis of the combined
survey indicates that the cluster disk fraction is initially very high (> 80%)
and rapidly decreases with increasing cluster age, such that half the stars
within the clusters lose their disks in < ~3 Myr. Moreover, these observations
yield an overall disk lifetime of ~ 6 Myr in the surveyed cluster sample. This
is the timescale for essentially all the stars in a cluster to lose their
disks. This should set a meaningful constraint for the planet building
timescale in stellar clusters. The implications of these results for current
theories of planet formation are briefly discussed.
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Searching for periodic non-accelerated signals in presence of ideal white
noise using the fully phase-coherent Fast Folding Algorithm (FFA) is
theoretically established as a more sensitive search method than the Fast
Fourier Transform (FFT) search with incoherent harmonic summing. In this paper,
we present a comparison of the performance of an FFA search implementation
using RIPTIDE and an FFT search implementation using PRESTO, over a range of
signal parameters with white noise and with real telescope noise from the GHRSS
survey with the uGMRT. We find that FFA search with appropriate de-reddening of
time series, performs better than FFT search with spectral whitening for long
period pulsars in real GHRSS noise conditions. We describe an FFA search
pipeline implemented for the GHRSS survey looking for pulsars over a period
range of 0.1 s to 100 s and up to dispersion measure of 500 pc cm$^{-3}$. We
processed GHRSS survey data covering $\sim$ 1500 degree$^2$ of the sky with
this pipeline. We re-detected 43 known pulsars with better signal-to-noise in
the FFA search than in the FFT search. We also report discovery of two new
pulsars including a long period pulsar having a short duty-cycle with this FFA
search pipeline. The population of long period pulsars with periods of several
seconds or higher can help to constrain the pulsar death-line.
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We introduce a uniform representation of general objects that captures the
regularities with respect to their structure. It allows a representation of a
general class of objects including geometric patterns and images in a sparse,
modular, hierarchical, and recursive manner. The representation can exploit any
computable regularity in objects to compactly describe them, while also being
capable of representing random objects as raw data. A set of rules uniformly
dictates the interpretation of the representation into raw signal, which makes
it possible to ask what pattern a given raw signal contains. Also, it allows
simple separation of the information that we wish to ignore from that which we
measure, by using a set of maps to delineate the a priori parts of the objects,
leaving only the information in the structure.
Using the representation, we introduce a measure of information in general
objects relative to structures defined by the set of maps. We point out that
the common prescription of encoding objects by strings to use Kolmogorov
complexity is meaningless when, as often is the case, the encoding is not
specified in any way other than that it exists. Noting this, we define the
measure directly in terms of the structures of the spaces in which the objects
reside. As a result, the measure is defined relative to a set of maps that
characterize the structures. It turns out that the measure is equivalent to
Kolmogorov complexity when it is defined relative to the maps characterizing
the structure of natural numbers. Thus, the formulation gives the larger class
of objects a meaningful measure of information that generalizes Kolmogorov
complexity.
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In this paper, we present a strategy for training convolutional neural
networks to effectively resolve interference arising from competing hypotheses
relating to inter-categorical information throughout the network. The premise
is based on the notion of feature binding, which is defined as the process by
which activations spread across space and layers in the network are
successfully integrated to arrive at a correct inference decision. In our work,
this is accomplished for the task of dense image labelling by blending images
based on (i) categorical clustering or (ii) the co-occurrence likelihood of
categories. We then train a feature binding network which simultaneously
segments and separates the blended images. Subsequent feature denoising to
suppress noisy activations reveals additional desirable properties and high
degrees of successful predictions. Through this process, we reveal a general
mechanism, distinct from any prior methods, for boosting the performance of the
base segmentation and saliency network while simultaneously increasing
robustness to adversarial attacks.
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Motivated by the recent experimental realization of a candidate to the
Fulde-Ferrell (FF) and the Larkin-Ovchinnikov (LO) states in one dimensional
(1D) atomic Fermi gases, we study the quantum phase transitions in these
enigmatic, finite momentum-paired superfluids. We focus on the FF state and
investigate the effects of the induced interaction on the stability of the FFLO
phase in homogeneous spin-imbalanced quasi-1D Fermi gases at zero temperature.
When this is taken into account we find a direct transition from the fully
polarized to the FFLO state. Also, we consider the effect of a finite lifetime
of the quasi-particles states in the normal-superfluid instability. In the
limit of long lifetimes, the lifetime effect is irrelevant and the transition
is directly from the fully polarized to the FFLO state. We show, however, that
for sufficiently short lifetimes there is a quantum critical point (QCP), at a
finite value of the mismatch of the Fermi wave-vectors of the different
quasi-particles, that we fully characterize. In this case the transition is
from the FFLO phase to a normal partially polarized state with increasing
mismatch.
|
Standard Model may be defined with the additional discrete symmetry, i.e.
with the gauge group $SU(3)\times SU(2) \times U(1)/{\cal Z}$ (${\cal Z} =
Z_6$, $Z_3$ or $Z_2$) instead of the usual $SU(3)\times SU(2) \times U(1)$. It
has the same perturbation expansion as the conventional one. However, it may
describe nature in a different way at the energies compared to the triviality
bound (of about 1 Tev). In this paper we present a possibility to observe this
difference assuming that the gauge group of the Standard Model is embedded into
the gauge group of an {\it a priory} unknown model, which describes physics at
a Tev scale. This difference is related to the monopole content of the theory.
We illustrate our results by consideration of the Petite Unification of quarks
and leptons.
|
We model the spin pulse intensity and hardness ratio profiles of the isolated
neutron star RXJ0720.4--3125 using XMM-Newton data. The observed variation is
approximately sinusoidal with a peak-to-peak amplitude of 15%, and the hardness
ratio is softest slightly before flux maximum. By using polar cap models we are
able to derive maximum polar cap sizes and acceptable viewing geometries. The
inferred sizes of the caps turn out to be more compatible with a scenario in
which the neutron star is heated by accretion, and place limits on the magnetic
field strength. The hardness ratio modulation can then be explained in terms of
energy-dependent beaming effects, and this constrains the acceptable models of
the emerging radiation to cases in which softer photons are more strongly
beamed than harder photons. An alternative explanation in terms of spatially
variable absorption co-rotating in the magnetosphere is also discussed.
|
With the rapid development of neural architecture search (NAS), researchers
found powerful network architectures for a wide range of vision tasks. However,
it remains unclear if the searched architecture can transfer across different
types of tasks as manually designed ones did. This paper puts forward this
problem, referred to as NAS in the wild, which explores the possibility of
finding the optimal architecture in a proxy dataset and then deploying it to
mostly unseen scenarios.
We instantiate this setting using a currently popular algorithm named
differentiable architecture search (DARTS), which often suffers unsatisfying
performance while being transferred across different tasks. We argue that the
accuracy drop originates from the formulation that uses a super-network for
search but a sub-network for re-training. The different properties of these
stages have resulted in a significant optimization gap, and consequently, the
architectural parameters "over-fit" the super-network. To alleviate the gap, we
present a progressive method that gradually increases the network depth during
the search stage, which leads to the Progressive DARTS (P-DARTS) algorithm.
With a reduced search cost (7 hours on a single GPU), P-DARTS achieves improved
performance on both the proxy dataset (CIFAR10) and a few target problems
(ImageNet classification, COCO detection and three ReID benchmarks). Our code
is available at \url{https://github.com/chenxin061/pdarts}.
|
Since computer was invented, people are using many devices to interact with
computer. Initially there were keyboard, mouse etc. but with the advancement of
technology, new ways are being discovered that are quite usual and natural to
the humans like stylus, touch-enable systems. In the current age of technology,
user is expected to touch the machine interface to give input. Hand gesture is
such a way to interact with machines where natural bare hand is used to
communicate without touching machine interface. It gives a feeling to user that
he is interacting in natural way to some human, not with traditional machines.
This paper presents a technique where user needs not to touch the machine
interface to draw on screen. Here hand finger draws shapes on monitor like
stylus, without touching the monitor. This method can be used in many
applications including games. The finger was used as an input device that acts
like paint-brush or finger-stylus and is used to make shapes in front of the
camera. Fingertip extraction and motion tracking were done in Matlab with real
time constraints. This work is an early attempt to replace stylus with the
natural finger without touching screen.
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Biased locomotion is a common feature of microorganisms, but little is known
about its impact on self-organisation. Inspired by recent experiments showing a
transition to large-scale flows, we study theoretically the dynamics of
magnetotactic bacteria confined to a drop. We reveal two symmetry-breaking
mechanisms (one local chiral and one global achiral) leading to
self-organisation into global vortices and a net torque exerted on the drop.
The collective behaviour is ultimately controlled by the swimmers' microscopic
chirality and, strikingly, the system can exhibit oscillations and memory-like
features.
|
A continuum evolutionary model for micromagnetics is presented that, beside
the standard magnetic balance laws, includes thermo-magnetic coupling. To allow
conceptually efficient computer implementation, inspired by relaxation method
of static minimization problems, our model is mesoscopic in the sense that
possible fine spatial oscillations of the magnetization are modeled by means of
Young measures. Existence of weak solutions is proved by backward Euler time
discretization.
|
In the present paper, we construct 3-designs using extended binary quadratic
residue codes and their dual codes.
|
We consider a platform's problem of collecting data from privacy sensitive
users to estimate an underlying parameter of interest. We formulate this
question as a Bayesian-optimal mechanism design problem, in which an individual
can share her (verifiable) data in exchange for a monetary reward or services,
but at the same time has a (private) heterogeneous privacy cost which we
quantify using differential privacy. We consider two popular differential
privacy settings for providing privacy guarantees for the users: central and
local. In both settings, we establish minimax lower bounds for the estimation
error and derive (near) optimal estimators for given heterogeneous privacy loss
levels for users. Building on this characterization, we pose the mechanism
design problem as the optimal selection of an estimator and payments that will
elicit truthful reporting of users' privacy sensitivities. Under a regularity
condition on the distribution of privacy sensitivities we develop efficient
algorithmic mechanisms to solve this problem in both privacy settings. Our
mechanism in the central setting can be implemented in time $\mathcal{O}(n \log
n)$ where $n$ is the number of users and our mechanism in the local setting
admits a Polynomial Time Approximation Scheme (PTAS).
|
Take the degenerate affine Hecke algebra $H_{l+m}$ corresponding to the group
$GL_{l+m}$ over a $p$-adic field. Consider the $H_{l+m}$-module $W$ induced
from the tensor product of the evaluation modules over the algebras $H_l$ and
$H_m$. The module $W$ depends on two partitions $\lambda$ of $l$ and $\mu$ of
$m$, and on two complex numbers $z$ and $w$. There is a canonical operator $J$
acting in $W$, it corresponds to the rational Yang $R$-matrix.
The algebra $H_{l+m}$ contains the symmetric group $S_{l+m}$, and $J$
commutes with the action of $S_{l+m}$ in $W$. Under this action, $W$ decomposes
into irreducible subspaces according to the Littlewood-Richardson rule. We
compute the eigenvalues of $J$, corresponding to certain multiplicity-free
irreducible components of $W$. In particular, we obtain a nice formula for the
ratio of two eigenvalues of $J$, corresponding to the "highest" and "lowest"
(multiplicity-free) irreducible components of $W$.
|
The question of classifying the nature of the generating functions of
restricted lattice walks has enjoyed much attention in past years. We prove
that a certain class of octant walks have a D-finite generating function using
the theory of multivariate formal Laurent series.
|
We present new properties of generalized core-EP inverse in a Banach
*-algebra. We characterize this new generalized inverse by using involved
annihilators. The generalized core-EP inverse for products is obtained. The
core-EP orders for Banach *-algebra elements are thereby investigated. As
applications, new properties of the core-EP inverse for block complex matrices
are given.
|
We investigate the core level spectra of Ca(1-x)Sr(x)RuO(3) employing high
resolution photoemission spectroscopy. Sample surface appears to be dominated
by the contributions from Ru-O layers. Sr 3p core level spectra are sharp and
asymmetric in SrRuO(3) as expected in a metallic system, and exhibit multiple
features for the intermediate compositions that can be attributed to the
difference in Ca-O and Sr-O covalency. The Ru core level spectra exhibit
distinct signature of satellite features due to the finite electron
correlations strength among Ru 4d electrons. The intensity of the satellite
feature is weaker in the surface spectra compared to the bulk. The low
temperature spectra exhibit enhancement of satellite intensity in the spectra
corresponding to ferromagnetic compositions due to the inter-site exchange
coupling induced depletion of the intensity at the Fermi level. The increase in
x leads to a decrease in satellite intensity that has been attributed to the
increase in hopping interaction strength due to the enhancement of the Ru-O-Ru
bond angle. Evidently, the complex electronic properties of these materials are
derived from the interplay between the electron correlation and hopping
interaction strengths.
|
We survey generalisations of the Chang-Skjelbred Lemma for integral
coefficients. Moreover, we construct examples of manifolds with actions of tori
of rank > 2 whose equivariant cohomology is torsion-free, but not free. This
answers a question of Allday's. The "mutants" we construct are obtained from
compactified representations and involve Hopf bundles in a crucial way.
|
Recognizing human emotions from complex, multivariate, and non-stationary
electroencephalography (EEG) time series is essential in affective
brain-computer interface. However, because continuous labeling of ever-changing
emotional states is not feasible in practice, existing methods can only assign
a fixed label to all EEG timepoints in a continuous emotion-evoking trial,
which overlooks the highly dynamic emotional states and highly non-stationary
EEG signals. To solve the problems of high reliance on fixed labels and
ignorance of time-changing information, in this paper we propose a time-aware
sampling network (TAS-Net) using deep reinforcement learning (DRL) for
unsupervised emotion recognition, which is able to detect key emotion fragments
and disregard irrelevant and misleading parts. Extensive experiments are
conducted on three public datasets (SEED, DEAP, and MAHNOB-HCI) for emotion
recognition using leave-one-subject-out cross-validation, and the results
demonstrate the superiority of the proposed method against previous
unsupervised emotion recognition methods.
|
We consider the following problem in computational geometry: given, in the
d-dimensional real space, a set of points marked as positive and a set of
points marked as negative, such that the convex hull of the positive set does
not intersect the negative set, find K hyperplanes that separate, if possible,
all the positive points from the negative ones. That is, we search for a convex
polyhedron with at most K faces, containing all the positive points and no
negative point. The problem is known in the literature for pure convex
polyhedral approximation; our interest stems from its possible applications in
constraint learning, where points are feasible or infeasible solutions of a
Mixed Integer Program, and the K hyperplanes are linear constraints to be
found. We cast the problem as an optimization one, minimizing the number of
negative points inside the convex polyhedron, whenever exact separation cannot
be achieved. We introduce models inspired by support vector machines and we
design two mathematical programming formulations with binary variables. We
exploit Dantzig-Wolfe decomposition to obtain extended formulations, and we
devise column generation algorithms with ad-hoc pricing routines. We compare
computing time and separation error values obtained by all our approaches on
synthetic datasets, with number of points from hundreds up to a few thousands,
showing our approaches to perform better than existing ones from the
literature. Furthermore, we observe that key computational differences arise,
depending on whether the budget K is sufficient to completely separate the
positive points from the negative ones or not. On 8-dimensional instances (and
over), existing convex hull algorithms become computational inapplicable, while
our algorithms allow to identify good convex hull approximations in minutes of
computation.
|
The detection of X-ray narrow spectral features in the 5-7 keV band is
becoming increasingly more common in AGN observations, thanks to the
capabilities of current X-ray satellites. Such lines, both in emission and in
absorption, are mostly interpreted as arising from Iron atoms. When observed
with some displacement from their rest frame position, these lines carry the
potential to study the motion of circumnuclear gas in AGN, providing a
diagnostic of the effects of the gravitational field of the central black hole.
These narrow features have been often found with marginal statistical
significance. We are carrying on a systematic search for narrow features using
spectra of bright type 1 AGNs available in the XMM-Newton archive. The aim of
this work is to characterise the occurrence of the narrow features phenomenon
on a large sample of objects and to estimate the significance of the features
through Monte Carlo simulations. The project and preliminary results are
presented.
|
Temporal knowledge graphs (TKGs) can effectively model the ever-evolving
nature of real-world knowledge, and their completeness and enhancement can be
achieved by reasoning new events from existing ones. However, reasoning
accuracy is adversely impacted due to an imbalance between new and recurring
events in the datasets. To achieve more accurate TKG reasoning, we propose an
attention masking-based contrastive event network (AMCEN) with local-global
temporal patterns for the two-stage prediction of future events. In the
network, historical and non-historical attention mask vectors are designed to
control the attention bias towards historical and non-historical entities,
acting as the key to alleviating the imbalance. A local-global message-passing
module is proposed to comprehensively consider and capture multi-hop structural
dependencies and local-global temporal evolution for the in-depth exploration
of latent impact factors of different event types. A contrastive event
classifier is used to classify events more accurately by incorporating
local-global temporal patterns into contrastive learning. Therefore, AMCEN
refines the prediction scope with the results of the contrastive event
classification, followed by utilizing attention masking-based decoders to
finalize the specific outcomes. The results of our experiments on four
benchmark datasets highlight the superiority of AMCEN. Especially, the
considerable improvements in Hits@1 prove that AMCEN can make more precise
predictions about future occurrences.
|
Advances in sensing and communication capabilities as well as power industry
deregulation are driving the need for distributed state estimation in the smart
grid at the level of the regional transmission organizations (RTOs). This leads
to a new competitive privacy problem amongst the RTOs since there is a tension
between sharing data to ensure network reliability (utility/benefit to all
RTOs) and withholding data for profitability and privacy reasons. The resulting
tradeoff between utility, quantified via fidelity of its state estimate at each
RTO, and privacy, quantified via the leakage of the state of one RTO at other
RTOs, is captured precisely using a lossy source coding problem formulation for
a two RTO network. For a two-RTO model, it is shown that the set of all
feasible utility-privacy pairs can be achieved via a single round of
communication when each RTO communicates taking into account the correlation
between the measured data at both RTOs. The lossy source coding problem and
solution developed here is also of independent interest.
|
In light of the recent experimental data from $B$ factories, We try to
explain the large branching ratio (compared to the Standard Model prediction)
of the decay $B^{\pm}\to \eta' K^{\pm}$ in the context of R-parity violating
($\rpv$) supersymmetry. We investigate other observed $\eta^{(\prime)}$ modes
and find that only two pairs of $\rpv$ coupling can satisfy the requirements
without affecting the other $B \to PP$ and $B \to VP$ decay modes except the
mode $B \to \phi K$. We also calculate the CP asymmetry for the observed decay
modes affected by the new couplings.
|
The hyperspectral pixel unmixing aims to find the underlying materials
(endmembers) and their proportions (abundances) in pixels of a hyperspectral
image. This work extends the Latent Dirichlet Variational Autoencoder (LDVAE)
pixel unmixing scheme by taking into account local spatial context while
performing pixel unmixing. The proposed method uses an isotropic convolutional
neural network with spatial attention to encode pixels as a dirichlet
distribution over endmembers. We have evaluated our model on Samson, Hydice
Urban, Cuprite, and OnTech-HSI-Syn-21 datasets. Our model also leverages the
transfer learning paradigm for Cuprite Dataset, where we train the model on
synthetic data and evaluate it on the real-world data. The results suggest that
incorporating spatial context improves both endmember extraction and abundance
estimation.
|
Augmenting X-ray imaging with 3D roadmap to improve guidance is a common
strategy. Such approaches benefit from automated analysis of the X-ray images,
such as the automatic detection and tracking of instruments. In this paper, we
propose a real-time method to segment the catheter and guidewire in 2D X-ray
fluoroscopic sequences. The method is based on deep convolutional neural
networks. The network takes as input the current image and the three previous
ones, and segments the catheter and guidewire in the current image.
Subsequently, a centerline model of the catheter is constructed from the
segmented image. A small set of annotated data combined with data augmentation
is used to train the network. We trained the method on images from 182 X-ray
sequences from 23 different interventions. On a testing set with images of 55
X-ray sequences from 5 other interventions, a median centerline distance error
of 0.2 mm and a median tip distance error of 0.9 mm was obtained. The
segmentation of the instruments in 2D X-ray sequences is performed in a
real-time fully-automatic manner.
|
Dominant spin-flip effects for the direct and prompt $J/\psi$ polarizations
at TEVATRON run II with collision energy 1.96 TeV and rapidity cut
$|y^{J/\psi}|<0.6$, have been systematically studied, especially, the spin-flip
effect for the transition of $(c\bar{c})_8[^3S_1]$ into $J/\psi$ has been
carefully discussed. It is found that the spin-flip effect shall always dilute
the $J/\psi$ polarization, and with a suitable choice of the parameters
$a_{0,1}$ and $c_{0,1,2}$, the $J/\psi$ polarization puzzle can be solved to a
certain degree. At large transverse momentum $p_t$, $\alpha$ for the prompt
$J/\psi$ is reduced by $\sim50%$ for $f_0 = v^2$ and by $\sim80%$ for $f_0=1$.
We also study the indirect $J/\psi$ polarization from the $b$-decays, which
however is slightly affected by the same spin-flip effect and then shall
provide a better platform to determine the color-octet matrix elements.
|
We obtain uniform estimates for $N_k(x,y)$, the number of positive integers
$n$ up to $x$ for which $\omega_y(n)=k$, where $\omega_y(n)$ is the number of
distinct prime factors of $n$ which are $<y$. The motivation for this problem
is an observation due to the first author in 2015 that for certain ranges of
$y$, the asymptotic behavior of $N_k(x,y)$ is different from the classical
situation concerning $N_k(x,x)$ studied by Sathe and Selberg. We demonstrate
this variation of the classical theme; to estimate $N_k(x,y)$ we study the sum
$S_z(x,y)=\sum_{n\le x}z^{\omega_y(n)}$ for $Re(z)>0$ by the Buchstab-de Bruijn
method. We also utilize a certain recent result of Tenenbaum to complete our
asymptotic analysis.
|
Based on the assignment of the first radial excitation states of the
isoscalar pseudoscalars for $\eta(1295)$ and $\eta(1405/1475)$, we investigate
their three-body and four-body decay contributions to the total widths. In
agreement with our previous studies we find that the triangle singularity (TS)
mechanism arising from the intermediate $K^*\bar{K}$ rescatterings by
exchanging a kaon or pion plays a crucial role in both $K\bar{K}\pi$ and
$\eta\pi\pi$ channels. For the $\eta_X$ ($\eta_X$ stands for $\eta(1295)$ and
$\eta(1405/1475)$) decays into $K\bar{K}\pi$, we find that although the
transition $\eta_X\to K^*\bar{K}+c.c.\to K\bar{K}\pi$ is the dominant
tree-level process, the productions of the intermediate $K\bar{\kappa}+c.c.$
and $a_0(980)\pi$ are strongly enhanced by the TS mechanism. For the $\eta_X$
decays into $\eta\pi\pi$, we find that the production of the intermediate
$a_0(980)\pi$ via the triangle transition is the dominant one for $\eta(1295)$
partly because of the large $\eta(1295)K^*\bar{K}$ coupling. In contrast, the
tree-level and triangle loop contributions are compatible and dominant in the
$\eta(1405/1475)$ decays into $\eta\pi\pi$. It shows that a combined analysis
is useful for disentangling the underlying dynamics for these two states.
|
In this paper we present the main developments in Oka theory since the
publication of my book Stein Manifolds and Holomorphic Mappings (The Homotopy
Principle in Complex Analysis)}, Second Edition, Springer, 2017. We also give
several new results, examples and constructions of Oka domains in Euclidean and
projective spaces. Furthermore, we show that for $n>1$ the fibre $\mathbb C^n$
in a Stein family can degenerate to a non-Oka fibre, thereby answering a
question of Takeo Ohsawa. Several open problems are discussed.
|
NELIOTA (NEO Lunar Impacts and Optical TrAnsients) is an ESA-funded lunar
monitoring project, which aims to determine the size-frequency distribution of
small Near-Earth Objects (NEOs) via detection of impact flashes on the surface
of the Moon. A prime focus, high-speed, twin-camera system providing
simultaneous observations in two photometric bands at a rate of 30
frames-per-second on the 1.2 m Kryoneri telescope of the National Observatory
of Athens was commissioned for this purpose. A dedicated software processes the
images and automatically detects candidate lunar impact flashes, which are then
validated by an expert user. The four year observing campaign began in February
2017 and has so far detected more than 40 lunar impact events. The software
routinely detects satellites, which typically appear as streaks or dots
crossing the lunar disk. To avoid confusing these events with real flashes, we
check different available catalogs with spacecraft orbital information and
exclude spacecraft identifications.
|
We study non-recurrence sets for weakly mixing dynamical systems by using
linear dynamical systems. These are systems consisting of a bounded linear
operator acting on a separable complex Banach space X, which becomes a
probability space when endowed with a non-degenerate Gaussian measure. We
generalize some recent results of Bergelson, del Junco, Lema\'nczyk and
Rosenblatt, and show in particular that sets \{n_k\} such that n_{k+1}/{n_k}
tends to infinity, or such that n_{k} divides n_{k+1} for each k, are
non-recurrence sets for weakly mixing linear dynamical systems. We also give
examples, for each r, of r-Bohr sets which are non-recurrence sets for some
weakly mixing systems.
|
This paper discusses the finite element method for the Yang-Mills equations
with temporal gauge. The new contributions reported in this paper are
threefold: an efficient linearized strategy for the Lie bracket $[A, A]$ is
introduced, the novel implicit scheme in time for the Yang-Mills equations
based on the above linearized strategy is presented, which preserves the
conservation of its discrete energy and the error estimates for the
semi-discrete scheme and the linearized scheme are proved. Finally, numerical
test studies are then carried out to confirm the theoretical results.
|
We discuss the status of both cosmological and black hole type singularities
in the framework of the brane-world model of gravity. We point out that the Big
Bang is not properly understood yet. We also show new features of the
gravitational collapse on the brane, the most important being the production of
dark energy during the collapse.
|
A new general relativistic magnetohydrodynamics (GRMHD) code ``RAISHIN'' used
to simulate jet generation by rotating and non-rotating black holes with a
geometrically thin Keplarian accretion disk finds that the jet develops a
spine-sheath structure in the rotating black hole case. Spine-sheath structure
and strong magnetic fields significantly modify the Kelvin-Helmholtz (KH)
velocity shear driven instability. The RAISHIN code has been used in its
relativistic magnetohydrodynamic (RMHD) configuration to study the effects of
strong magnetic fields and weakly relativistic sheath motion, c/2, on the KH
instability associated with a relativistic, Lorentz factor equal 2.5, jet
spine-sheath interaction. In the simulations sound speeds up to c/1.7 and
Alfven wave speeds up to 0.56 c are considered. Numerical simulation results
are compared to theoretical predictions from a new normal mode analysis of the
RMHD equations. Increased stability of a weakly magnetized system resulting
from c/2 sheath speeds and stabilization of a strongly magnetized system
resulting from c/2 sheath speeds is found.
|
Asymptotics of the normalizing constant is computed for a class of one
parameter exponential families on permutations which includes Mallows model
with Spearmans's Footrule and Spearman's Rank Correlation Statistic. The MLE,
and a computable approximation of the MLE are shown to be consistent. The
pseudo-likelihood estimator of Besag is shown to be $\sqrt{n}$-consistent. An
iterative algorithm (IPFP) is proved to converge to the limiting normalizing
constant. The Mallows model with Kendall's Tau is also analyzed to demonstrate
flexibility of the tools of this paper.
|
Highly precise measurements of the $^{99}$Tc beta spectrum were performed in
two laboratories using metallic magnetic calorimeters. Independent sample
preparations, evaluation methods and analyses yield consistent results and the
spectrum could be measured down to less than 1 keV. Consistent beta spectra
were also obtained via cross-evaluations of the experimental data sets. An
additional independent measurement with silicon detectors in a $4\pi$
configuration confirms the spectrum shape above 25 keV. Detailed theoretical
calculations were performed including nuclear structure and atomic effects. The
spectrum shape was found to be sensitive to the effective value of the
axial-vector coupling constant. Combining measurements and predictions, we
extracted $Q_{\beta}=$295.82(16) keV and $g_A^{\text{eff}} = 1.530 (83)$.
Furthermore, we derived the mean energy of the beta spectrum
$\overline{E}_{\beta}$=98.45(20) keV, $\log f = -0.47660 (22)$ and $\log ft =
12.3478 (23)$.
|
Dialogue state tracking (DST) is an important part of a spoken dialogue
system. Existing DST models either ignore temporal feature dependencies across
dialogue turns or fail to explicitly model temporal state dependencies in a
dialogue. In this work, we propose Temporally Expressive Networks (TEN) to
jointly model the two types of temporal dependencies in DST. The TEN model
utilizes the power of recurrent networks and probabilistic graphical models.
Evaluating on standard datasets, TEN is demonstrated to be effective in
improving the accuracy of turn-level-state prediction and the state
aggregation.
|
We present novel method for the organisation of events. The method is based
on comparing event-by-event histograms of a chosen quantity Q that is measured
for each particle in every event. The events are organised in such a way that
those with similar shape of the Q-histograms end-up placed close to each other.
We apply the method on histograms of azimuthal angle of the produced hadrons in
ultrarelativsitic nuclear collisions. By selecting events with similar
azimuthal shape of their hadron distribution one chooses events which are
likely that they underwent similar evolution from the initial state to the
freeze-out. Such events can more easily be compared to theoretical simulations
where all conditions can be controlled. We illustrate the method on data
simulated by the AMPT model.
|
We provide a brane realization of 2d (0,2) Gadde-Gukov-Putrov triality in
terms of brane brick models. These are Type IIA brane configurations that are
T-dual to D1-branes over singular toric Calabi-Yau 4-folds. Triality translates
into a local transformation of brane brick models, whose simplest
representative is a cube move. We present explicit examples and construct their
triality networks. We also argue that the classical mesonic moduli space of
brane brick model theories, which corresponds to the probed Calabi-Yau 4-fold,
is invariant under triality. Finally, we discuss triality in terms of phase
boundaries, which play a central role in connecting Calabi-Yau 4-folds to brane
brick models.
|
As the adoption of deep learning techniques in industrial applications grows
with increasing speed and scale, successful deployment of deep learning models
often hinges on the availability, volume, and quality of annotated data. In
this paper, we tackle the problems of efficient data labeling and annotation
verification under the human-in-the-loop setting. We showcase that the latest
advancements in the field of self-supervised visual representation learning can
lead to tools and methods that benefit the curation and engineering of natural
image datasets, reducing annotation cost and increasing annotation quality. We
propose a unifying framework by leveraging self-supervised semi-supervised
learning and use it to construct workflows for data labeling and annotation
verification tasks. We demonstrate the effectiveness of our workflows over
existing methodologies. On active learning task, our method achieves 97.0%
Top-1 Accuracy on CIFAR10 with 0.1% annotated data, and 83.9% Top-1 Accuracy on
CIFAR100 with 10% annotated data. When learning with 50% of wrong labels, our
method achieves 97.4% Top-1 Accuracy on CIFAR10 and 85.5% Top-1 Accuracy on
CIFAR100.
|
Superflares on giant stars have up to 100,000 times more energy than the high
energy solar flares. However, it is disputed, whether scaling up a solar-type
dynamo could explain such a magnitude difference. We investigate the flaring
activity of KIC 2852961, a late-type spotted giant. We seek for flares in the
Kepler Q0-Q17 datasets by an automated technique together with visual
inspection. Flare occurence rate and flare energies are analyzed and compared
to flare statistics of different targets with similar flare activity at
different energy levels. We find that the flare energy distribution of KIC
2852961 does not seem to be consistent with that of superflares on solar-type
stars. Also, we believe that in case of KIC 2852961 spot activity should have
an important role in producing such superflares.
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We determine the behavior of the critical temperature of magnetically
mediated p-wave superconductivity near a ferromagnetic quantum critical point
in three dimensions, distinguishing universal and non-universal aspects of the
result. We find that the transition temperature is non-zero at the critical
point, raising the possibility of superconductivity in the ferromagnetic phase.
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In this Thesis, we report a detailed study of the ground-state properties of
a set of quantum few- and many-body systems in one and two dimensions with
different types of interactions by using Quantum Monte Carlo methods.
Nevertheless, the main focus of this work is the study of the ground-state
properties of an ultracold Bose system with dipole-dipole interaction between
the particles. We consider the cases where the bosons are confined to a bilayer
and multilayer geometries, that consist of equally spaced two-dimensional
layers. These layers can be experimentally realized by imposing tight
confinement in one direction. We specifically address the study of new quantum
phases, their properties, and transitions between them. One expects these
systems to have a rich collection of few- and many-body phases because the
dipole-dipole interaction is anisotropic and quasi long-range.
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The relation between the branching ratios and direct CP asymmetries of B -->
K pi decays and the angle gamma of the CKM unitarity triangle is studied
numerically in the general framework of the SU(3) approach, with minimal
assumptions about the parameters not fixed by flavour-symmetry arguments.
Experimental and theoretical uncertainties are subjected to a statistical
treatment according to the Bayesian method. In this context, the experimental
limits recently obtained by CLEO, BaBar and Belle for the direct CP asymmetries
are translated into the bound |gamma - 90 deg| > 21 deg at the 95% C.L.. A
detailed analysis is carried out to evaluate the conditions under which
measurements of the CP averaged branching ratios may place a significant
constraint on gamma. Predictions for the ratios of charged (R_c) and neutral
(R_n) B --> K pi decays are also presented.
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It is known that Lorentz covariance fixes uniquely the current and the
associated guidance law in the trajectory interpretation of quantum mechanics
for spin-1/2 particles. In the nonrelativistic domain this implies a guidance
law for electrons which differs by an additional spin-dependent term from the
one originally proposed by de Broglie and Bohm. Although the additional term in
the guidance equation may not be detectable in the quantum measurements derived
solely from the probability density $\rho$, it plays a role in the case of
arrival-time measurements. In this paper we compute the arrival time
distribution and the mean arrival time at a given location, with and without
the spin contribution, for two problems: 1) a symmetrical Gaussian packet in a
uniform field and 2) a symmetrical Gaussian packet passing through a 1D
barrier. Using the Runge-Kutta method for integration of the guidance law,
Bohmian paths of these problems are also computed.
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Given a finitely generated relatively hyperbolic group $G$, we construct a
finite generating set $X$ of $G$ such that $(G,X)$ has the `falsification by
fellow traveler property' provided that the parabolic subgroups
$\{H_\omega\}_{\omega\in \Omega}$ have this property with respect to the
generating sets $\{X\cap H_\omega\}_{\omega\in \Omega}$. This implies that
groups hyperbolic relative to virtually abelian subgroups, which include all
limit groups and groups acting freely on $\mathbb{R}^n$-trees, or geometrically
finite hyperbolic groups, have generating sets for which the language of
geodesics is regular, and the complete growth series and complete geodesic
series are rational. As an application of our techniques, we prove that if each
$H_\omega$ admits a geodesic biautomatic structure over $X\cap H_\omega$, then
$G$ has a geodesic biautomatic structure.
Similarly, we construct a finite generating set $X$ of $G$ such that $(G,X)$
has the `bounded conjugacy diagrams' property or the `neighbouring shorter
conjugate' property if the parabolic subgroups $\{H_\omega\}_{\omega\in
\Omega}$ have this property with respect to the generating sets $\{X\cap
H_\omega\}_{\omega\in \Omega}$. This implies that a group hyperbolic relative
to abelian subgroups has a generating set for which its Cayley graph has
bounded conjugacy diagrams, a fact we use to give a cubic time algorithm to
solve the conjugacy problem.
Another corollary of our results is that groups hyperbolic relative to
virtually abelian subgroups have a regular language of conjugacy geodesics.
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Motivated by the potential chiral spin liquid in the metallic spin ice
Pr2Ir2O7, we consider how such a chiral state might be selected from the spin
ice manifold. We propose that chiral fluctuations of the conducting Ir moments
promote ferro-chiral couplings between the local Pr moments, as a chiral
analogue of the magnetic RKKY effect. Pr2Ir2O7 provides an ideal setting to
explore such a chiral RKKY effect, given the inherent chirality of the spin-ice
manifold. We use a slave-rotor calculation on the pyrochlore lattice to
estimate the sign and magnitude of the chiral coupling, and find it can easily
explain the 1.5K transition to a ferro-chiral state.
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Mass-conservative reaction-diffusion systems have recently been proposed as a
general framework to describe intracellular pattern formation. These systems
have been used to model the conformational switching of proteins as they cycle
from an inactive state in the cell cytoplasm, to an active state at the cell
membrane. The active state then acts as input to downstream effectors. The
paradigm of activation by recruitment to the membrane underpins a range of
biological pathways - including G-protein signalling, growth control through
Ras and PI 3-kinase, and cell polarity through Rac and Rho; all activate their
targets by recruiting them from the cytoplasm to the membrane. Global mass
conservation lies at the heart of these models reflecting the property that the
total number of active and inactive forms, and targets, remains constant. Here
we present a conservative arbitrary Lagrangian Eulerian (ALE) finite element
method for the approximate solution of systems of bulk-surface
reaction-diffusion equations on an evolving two-dimensional domain. Fundamental
to the success of the method is the robust generation of bulk and surface
meshes. For this purpose, we use a moving mesh partial differential equation
(MMPDE) approach. Global conservation of the fully discrete finite element
solution is established independently of the ALE velocity field and the time
step size. The developed method is applied to model problems with known
analytical solutions; these experiments indicate that the method is
second-order accurate and globally conservative. The method is further applied
to a model of a single cell migrating in the presence of an external
chemotactic signal.
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Network slicing enables the deployment of multiple dedicated virtual
sub-networks, i.e. slices on a shared physical infrastructure. Unlike
traditional one-size-fits-all resource provisioning schemes, each network slice
(NS) in 5G is tailored to the specific service requirements of a group of
customers. An end-to-end (E2E) mobile NS orchestration requires the
simultaneous provisioning of computing, storage, and networking resources
across the core network (CN) and the radio access network (RAN). Constant
temporospatial changes in mobile user demand profiles further complicate the
E2E NSs resource provisioning beyond the limits of the existing best-effort
schemes that are only effective under accurate demand forecasts for all slices.
This paper proposes a practical two-time-scale resource provisioning framework
for E2E network slicing under demand uncertainty. At each macro-scale instance,
we assume that only the spatial probability distribution of the NS demands is
available. We formulate the NSs resource allocation problem as a stochastic
mixed integer program (SMIP) with the objective of minimizing the total
resource cost at the CN and the RAN. At each microscale instance, utilizing the
exact slice demand profiles, a linear program is solved to jointly minimize the
unsupported traffic and the resource cost at the RAN. We verify the
effectiveness of our resource allocation scheme through numerical experiments.
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The ultrarelativistic limit of the Kerr - Newman geometry is studied in
detail. We find the gravitational shock wave background associated with this
limit. We study the scattering of scalar fields in the gravitational shock wave
geometries and compare this with the scattering by ultrarelativistic extended
sources and with the scattering of fundamental strings.
We also study planckian energy string collisions in flat spacetime as the
scattering of a string in the effective curved background produced by the
others as the impact parameter $b$ decreases. We find the effective energy
density distribution generated by these collisions. The effective metric
generated by these collisions is a gravitational shock wave with profile
$f(\rho)\sim p\rho^{4-D}$, for large impact parameter $b$. For intermediate
$b$, $f(\rho)\sim q\rho^2$, corresponding to an extended source of momentum
$q$.
We finally study the emergence of string instabilities in $D$ - dimensional
black hole spacetimes and De Sitter space. We solve the first order string
fluctuations around the center of mass motion at spatial infinity, near the
horizon and at the spacetime singularity. We find that the time components are
always well behaved in the three regions and in the three backgrounds. The
radial components are unstable: imaginary frequencies develop in the
oscillatory modes near the horizon, and the evolution is like $(\tau-\tau_0)^
{-P}$, $(P>0)$, near the spacetime singularity, $r\to0$, where the world -
sheet time $(\tau-\tau_0)\to0$, and the proper string length grows infinitely.
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The non-commuting graph of a non-abelian group $G$ with center $Z(G)$ is a
simple undirected graph whose vertex set is $G\setminus Z(G)$ and two vertices
$x, y$ are adjacent if $xy \ne yx$. In this study, we compute Signless
Laplacian spectrum and Signless Laplacian energy of non-commuting graphs of
finite groups. We obtain several conditions such that the non-commuting graph
of $G$ is Q-integral and observe relations between energy, Signless Laplacian
energy and Laplacian energy. In addition, we look into the energetic hyper- and
hypo-properties of non-commuting graphs of finite groups. We also assess
whether the same graphs are Q-hyperenergetic and L-hyperenergetic.
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To better understand the temporal characteristics and the lifetime of
fluctuations in stochastic processes in networks, we investigated diffusive
persistence in various graphs. Global diffusive persistence is defined as the
fraction of nodes for which the diffusive field at a site (or node) has not
changed sign up to time $t$ (or in general, that the node remained
active/inactive in discrete models). Here we investigate disordered and random
networks and show that the behavior of the persistence depends on the topology
of the network. In two-dimensional (2D) disordered networks, we find that above
the percolation threshold diffusive persistence scales similarly as in the
original 2D regular lattice, according to a power law $P(t,L)\sim t^{-\theta}$
with an exponent $\theta \simeq 0.186$, in the limit of large linear system
size $L$. At the percolation threshold, however, the scaling exponent changes
to $\theta \simeq 0.141$, as the result of the interplay of diffusive
persistence and the underlying structural transition in the disordered lattice
at the percolation threshold. Moreover, studying finite-size effects for 2D
lattices at and above the percolation threshold, we find that at the
percolation threshold, the long-time asymptotic value obeys a power-law
$P(t,L)\sim L^{-z\theta}$ with $z\simeq 2.86$ instead of the value of $z=2$
normally associated with finite-size effects on 2D regular lattices. In
contrast, we observe that in random networks without a local regular structure,
such as Erd\H{o}s-R\'enyi networks, no simple power-law scaling behavior exists
above the percolation threshold.
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We demonstrate a simple and robust geometry for optical trapping in vacuum of
a single nanoparticle based on a parabolic mirror and the optical gradient
force, and we demonstrate rapid parametric feedback cooling of all three
motional degrees of freedom from room temperature to a few mK. A single laser
at 1550nm, and a single photodiode, are used for trapping, position detection,
and cooling for all three dimensions. Particles with diameters from 26nm to
160nm are trapped without feedback to 10$^{-5}$mbar and with feedback engaged
the pressure is reduced to 10$^{-6}$mbar. Modifications to the harmonic motion
in the presence of noise and feedback are studied, and an experimental
mechanical quality factor $>4\times 10^7$ is estimated.
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We consider the combination of uplink code-domain non-orthogonal multiple
access (NOMA) with massive multiple-input multiple-output (MIMO) and
reconfigurable intelligent surfaces (RISs). We assume a setup in which the base
station (BS) is capable of forming beams towards the RISs under line-of-sight
conditions, and where each RIS is covering a cluster of users. In order to
support multi-user transmissions within a cluster, code-domain NOMA via
spreading is utilized. We investigate the optimization of the RIS phase-shifts
such that a large number of users is supported. As it turns out, it is a
coupled optimization problem that depends on the detection order under
interference cancellation and the applied filtering at the BS. We propose to
decouple those variables by using sum-rate optimized phase-shifts as the
initial solution, allowing us to obtain a decoupled estimate of those
variables. Then, in order to determine the final phase-shifts, the problem is
relaxed into a semidefinite program that can be solved efficiently via convex
optimization algorithms. Simulation results show the effectiveness of our
approach in improving the detectability of the users.
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We present both spin-independent and -dependent parts of a central interquark
potential for charmonium states, which is calculated in 2+1 flavor dynamical
lattice QCD using the PACS-CS gauge configurations with a lattice cutoff of
a^{-1}~2.2 GeV. Our simulations are performed with a relativistic heavy quark
action for the charm quark at the lightest pion mass, M_\pi=156(7) MeV, in a
spatial volume of 3fm^3. We observe that the spin-independent charmonium
potential obtained from lattice QCD with almost physical quark masses is quite
similar to the Conrnell potential used in non-relativistic potential models.
The spin-spin potential properly exhibits the short range repulsive
interaction, while its r-dependence is different from either a point-like
spin-spin potential generated by one-gluon exchange or a phenomenological
finite-range one adopted in quark potential models.
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For a smooth projective toric variety of Picard rank two we classify all
exceptional sequences of invertible sheaves which have maximal length. In
particular, we prove that unlike non-maximal sequences, they (a) remain
exceptional under lexicographical reordering (b) satisfy strong height
constraints in the Picard lattice (c) are full, that is, they generate the
derived category of the variety.
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We consider a two flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model where the
Lagrangian includes an interaction term that explicitly breaks the U$_A(1)$
anomaly. At finite temperature, the restoration of chiral and axial symmetries,
signaled by the behavior of several observables, is investigated. We compare
the effects of two regularizations at finite temperature, one of them, that
allows high momentum quarks states, leading to the full recovery of chiral
symmetry. From the analysis of the behavior of the topological susceptibility
and of the mesonic masses of the axial partners, it is found in the SU(2) model
that, unlike the SU(3) results, the recovery of the axial symmetry is not a
consequence of the full recovery of the chiral symmetry. Thus, one needs to use
an additional idea, by means of a temperature dependence of the anomaly
coefficient, that simulates instanton suppression effects.
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Archimedean cohomology provides a cohomological interpretation for the
calculation of the local L-factors at archimedean places as zeta regularized
determinant of a log of Frobenius. In this paper we investigate further the
properties of the Lefschetz and log of monodromy operators on this cohomology.
We use the Connes-Kreimer formalism of renormalization to obtain a fuchsian
connection whose residue is the log of the monodromy. We also present a
dictionary of analogies between the geometry of a tubular neighborhood of the
``fiber at arithmetic infinity'' of an arithmetic variety and the complex of
nearby cycles in the geometry of a degeneration over a disk, and we recall
Deninger's approach to the archimedean cohomology through an interpretation as
global sections of a analytic Rees sheaf. We show that action of the Lefschetz,
the log of monodromy and the log of Frobenius on the archimedean cohomology
combine to determine a spectral triple in the sense of Connes. The archimedean
part of the Hasse-Weil L-function appears as a zeta function of this spectral
triple. We also outline some formal analogies between this cohomological theory
at arithmetic infinity and Givental's homological geometry on loop spaces.
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Context. he study of prestellar cores is essential to understanding the
initial stages of star formation. With $Herschel$ more cold clumps have been
detected than ever before. For this study we have selected 21 cold clumps from
20 $Herschel$ fields observed as a follow-up on original $Planck$ detections.
We have observed these clumps in $^{13}$CO (1-0), C$^{18}$O (1-0), and
N$_2$H$^+$ (1-0) lines. Aims. Our aim is to find out if these cold clumps are
prestellar. We have examined to what extent independent analysis of the dust
and the molecular lines lead to similar conclusions about the masses of these
objects. Methods. We calculate the clump masses and densities from the dust
continuum and molecular line observations and compare these to each other and
to the virial and Bonnor-Ebert masses calculated for each clump. Finally we
examine two of the fields with radiative transfer models to estimate CO
abundances. Results. When excitation temperatures could be estimated, the
column densities derived from molecular line observations were comparable to
those from dust continuum data. The median column density estimates are
4.2$\times 10^{21}$cm$^{-2}$ and 5.5$\times 10^{21}$cm$^{-2}$ for the line and
dust emission data, respectively. The calculated abundances, column densities,
volume densities, and masses all have large uncertainties and one must be
careful when drawing conclusions. Abundance of $^{13}$CO was found in modeling
the two clumps in the field G131.65$+$9.75 to be close to the usual value of
10$^{-6}$. The abundance ratio of $^{13}$CO and C$^{18}$O was $\sim$10.
Molecular abundances could only be estimated with modeling, relying on dust
column density data. Conclusions. The results indicate that most cold clumps,
even those with dust color temperatures close to 11 K, are not necessarily
prestellar.
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The desirable properties when constructing collections of subspaces often
include the algebraic constraint that the projections onto the subspaces yield
a resolution of the identity like the projections onto lines spanned by vectors
of an orthonormal basis (the so-called tightness condition) and the geometric
constraint that the subspaces form an optimal packing of the Grassmannian,
again like the one-dimensional subspaces spanned by vectors in an orthonormal
basis. In this article a generalization of related constructions which use
known packings to build new configurations and which appear in numerous forms
in the literature is given, as well as the characterization of a long list of
desirable algebraic and geometric properties which the construction preserves.
Another construction based on subspace complementation is similarly analyzed.
While many papers on subspace packings focus only on so-called equiisoclinic or
equichordal arrangements, attention is also given to other configurations like
those which saturate the orthoplex bound and thus are optimal but lie outside
of the parameter regime where equiisoclinic and equichordal packings can occur.
Keywords: fusion frame, Grassmannian packing, simplex bound, orthoplex bound,
equichordal, strongly simplicial, equiisoclinic
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Open-vocabulary 3D instance segmentation is cutting-edge for its ability to
segment 3D instances without predefined categories. However, progress in 3D
lags behind its 2D counterpart due to limited annotated 3D data. To address
this, recent works first generate 2D open-vocabulary masks through 2D models
and then merge them into 3D instances based on metrics calculated between two
neighboring frames. In contrast to these local metrics, we propose a novel
metric, view consensus rate, to enhance the utilization of multi-view
observations. The key insight is that two 2D masks should be deemed part of the
same 3D instance if a significant number of other 2D masks from different views
contain both these two masks. Using this metric as edge weight, we construct a
global mask graph where each mask is a node. Through iterative clustering of
masks showing high view consensus, we generate a series of clusters, each
representing a distinct 3D instance. Notably, our model is training-free.
Through extensive experiments on publicly available datasets, including
ScanNet++, ScanNet200 and MatterPort3D, we demonstrate that our method achieves
state-of-the-art performance in open-vocabulary 3D instance segmentation. Our
project page is at https://pku-epic.github.io/MaskClustering.
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We investigate a one-dimensional electron liquid with two point scatterers of
different strength. In the presence of electron interactions, the nonlinear
conductance is shown to depend on the current direction. The resulting
asymmetry of the transport characteristic gives rise to a ratchet effect, i.e.,
the rectification of a dc current for an applied ac voltage. In the case of
strong repulsive interactions, the ratchet current grows in a wide voltage
interval with decreasing ac voltage. In the regime of weak interaction the
current-voltage curve exhibits oscillatory behavior. Our results apply to
single-band quantum wires and to tunneling between quantum Hall edges.
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We define a sequence of functions, namely tame cuts, in the Fourier algebra
$A(G)$ of a locally compact group $G$, that satisfies certain convergence and
growth conditions. This new consideration allows us to give a group admitting a
Fourier multiplier that is not completely bounded. Furthermore, we show that
the induction map $MA(\Gamma)\rightarrow MA(G)$ is not always continuous. We
also show how Liao's Property $(T_{Schur}, G, K)$ opposes tame cuts. Some
examples are provided.
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Thin-film superconductors with thickness 30 to 500 nm are used as
non-equilibrium quantum detectors for photons, phonons or more exotic
particles. One of the most basic questions in determining their limiting
sensitivity is the efficiency with which the quanta of interest couple to the
detected quasiparticles. As low temperature superconducting resonators,
thin-films are attractive candidates for producing quantum-sensitive arrayable
sensors and the readout uses an additional microwave probe. We have calculated
the quasiparticle generation efficiency eta_s for low energy photons in a
representative, clean thin-film superconductor (Al) operating well-below its
superconductingtransition temperature as a function of film thickness, within
the framework of the coupled kineticequations described by Chang and
Scalapino.[J. J. Chang and D. J. Scalapino, J. Low Temp. Phys. 31, 1 (1978)].
We have also included the effect of a lower frequency probe. We show that
phonon loss from the thin-film reduces eta_s by as much as 40% compared to
earlier models that considered relatively thick films or infinite volumes. We
also show that the presence of the probe and signal enhances the generation
efficiency slightly. We conclude that the ultimate limiting noise equivalent
power of this class of detector is determined by the thin-film geometry.
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We present a new class of solutions for the inverse problem in the calculus
of variations in arbitrary dimension $n$. This is the problem of determining
the existence and uniqueness of Lagrangians for systems of $n$ second order
ordinary differential equations. We also provide a number of new theorems
concerning the inverse problem using exterior differential systems theory
(EDS). Concentrating on the differential step of the EDS process, our new
results provide a significant advance in the understanding of the inverse
problem in arbitrary dimension. In particular, we indicate how to generalise
Jesse Douglas's famous solution for $n=2$. We give some non-trivial examples in
dimensions 2,3 and 4. We finish with a new classification scheme for the
inverse problem in arbitrary dimension.
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We explicitly obtain energy-momentum tensor at the asymptotic 3-dimensional
region of Schwarzschild AdS$_4$ and Taub-NUT-(A)dS$_4$ using the so-called
`counter-term subtraction method' in Fefferman-Graham coordinate. The energy
momentum tensor is presented in a closed form for the AdS$_4$ and for the
special case of Taub-NUT-dS and in an asymptotic series for other cases. The
result suggests that in light of AdS/CFT correspondence, the 3-dimensional
trace anomaly can be expressed in terms of the 3-dimensional volume and Ricci
scalar.
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A persistent focus on the concept of emergence as a core element of the
scientific method allows a clean separation, insofar as this is possible, of
the physical and philosophical aspects of the problem of outcomes in quantum
mechanics. The philosophical part of the problem is to explain why a closed
system has definite experimental outcomes. The physical part is to show
mathematically that there exists a limit in which the contradiction between
unitary Schroedinger dynamics and a reduction process leading to distinct
outcomes becomes negligible according to an explicitly stated criterion, and to
make this criterion as objective as possible. The physical problem is solved
here by redefining the notion of a quantum state and finding a suitable measure
for the change of state upon reduction. The appropriate definition of the
quantum state is not as a ray or density operator in Hilbert space, but rather
as an equivalence class consisting of all density operators in a given
subspace, the members of which all describe the same experimental outcome. For
systems containing only subsystems that are integrated with their environments,
these equivalence classes can be represented mathematically by projection
operators, and the resulting formalism is closely related to that used by von
Neumann to study the increase of entropy predicted by the second law of
thermodynamics. However, nearly isolated subsystems are reduced only
indirectly, as a consequence of their interaction with integrated subsystems.
The reduced states of isolated subsystems are the same conditional states used
in the definition of quantum discord. The key concepts of decoherence theory
can all be adapted to fit this definition of a quantum state, resulting in a
unified theory capable of resolving, in principle, all aspects of the quantum
measurement problem. The theory thus obtained is weakly objective but not
strongly objective.
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Subsets and Splits
Filtered Text Samples
Retrieves 100 samples of text containing the specific phrase "You are a helpful assistant", providing limited insight into the dataset.
Helpful Assistant Text Samples
Returns a limited set of rows containing the phrase 'helpful assistant' in the text, providing basic filtering of relevant entries.