text
stringlengths 6
128k
|
|---|
As introduced by Bollob\'as, a graph $G$ is weakly $H$-saturated if the
complete graph $K_n$ is obtained by iteratively completing copies of $H$ minus
an edge. For all graphs $H$, we obtain an asymptotic lower bound for the
critical threshold $p_c$, at which point the Erd\H{o}s--R\'enyi graph
${\mathcal G}_{n,p}$ is likely to be weakly $H$-saturated. We also prove an
upper bound for $p_c$, for all $H$ which are, in a sense, strictly balanced. In
particular, we improve the upper bound by Balogh, Bollob{\'a}s and Morris for
$H=K_r$, and we conjecture that this is sharp up to constants.
|
We present a theoretical study of the $\gamma\gamma^{*} \to \pi^+\pi^-,
\pi^0\pi^0$ processes from the threshold through the $f_2(1270)$ region in the
$\pi\pi$ invariant mass. We adopt the Omn\`es representation in order to
account for rescattering effects in both s- and d-partial waves. For the
description of the $f_0(980)$ resonance, we implement a coupled-channel
unitarity. The constructed amplitudes serve as an essential framework to
interpret the current experimental two-photon fusion program at BESIII. They
also provide an important input for the dispersive analyses of the hadronic
light-by-light scattering contribution to the muon's anomalous magnetic moment.
|
In this paper, we propose an uncertainty-aware learning from demonstration
method by presenting a novel uncertainty estimation method utilizing a mixture
density network appropriate for modeling complex and noisy human behaviors. The
proposed uncertainty acquisition can be done with a single forward path without
Monte Carlo sampling and is suitable for real-time robotics applications. The
properties of the proposed uncertainty measure are analyzed through three
different synthetic examples, absence of data, heavy measurement noise, and
composition of functions scenarios. We show that each case can be distinguished
using the proposed uncertainty measure and presented an uncertainty-aware
learn- ing from demonstration method of an autonomous driving using this
property. The proposed uncertainty-aware learning from demonstration method
outperforms other compared methods in terms of safety using a complex
real-world driving dataset.
|
Multi-pixel photodiodes operating in a limited Geiger mode will be used for
photoreadout of scintillator counters in underground cosmic ray experiment
EMMA. Main parameters of photodiodes and the performance of EMMA scintillator
counters are presented.
|
The first-order formulation of the Salam-Sezgin D=8 supergravity coupled to N
vector multiplets is discussed. The non-linear realization of the bosonic
sector of the D=8 matter coupled Salam-Sezgin supergravity is introduced by the
dualisation of the fields and by constructing the Lie superalgebra of the
symmetry group of the doubled field strength.
|
We give a permutation pattern avoidance criteria for determining when the
projection map from the flag variety to a Grassmannian induces a fiber bundle
structure on a Schubert variety. In particular, we introduce the notion of a
split pattern and show that a Schubert variety has such a fiber bundle
structure if and only if the corresponding permutation avoids the split
patterns 3|12 and 23|1. Continuing, we show that a Schubert variety is an
iterated fiber bundle of Grassmannian Schubert varieties if and only if the
corresponding permutation avoids (non-split) patterns 3412, 52341, and 635241.
This extends a combined result of Lakshmibai-Sandhya, Ryan, and Wolper who
prove that Schubert varieties whose permutation avoids the "smooth" patterns
3412 and 4231 are iterated fiber bundles of smooth Grassmannian Schubert
varieties.
|
Two-dimensional hybrid perovskites are currently in the spotlight of
condensed matter and nanotechnology research due to their intriguing
optoelectronic and vibrational properties with emerging potential for
light-harvesting and -emitting applications. While it is known that these
natural quantum wells host tightly bound excitons, the mobilities of these
fundamental optical excitations at the heart of the optoelectronic applications
are still largely unexplored. Here, we directly monitor the diffusion of
excitons through ultrafast emission microscopy from liquid helium to room
temperature in hBN-encapsulated two-dimensional hybrid perovskites. We find
very fast diffusion with characteristic hallmarks of free exciton propagation
for all temperatures above 50 K. In the cryogenic regime we observe nonlinear,
anomalous behavior with an exceptionally rapid expansion of the exciton cloud
followed by a very slow and even negative effective diffusion. We discuss our
findings in view of efficient exciton-phonon coupling, highlighting
two-dimensional hybrids as promising platforms for many-body physics research
and optoelectronic applications on the nanoscale.
|
A quantitative study of the observable radio signatures of the sausage, kink,
and torsional MHD oscillation modes in flaring coronal loops is performed.
Considering first non-zero order effect of these various MHD oscillation modes
on the radio source parameters such as magnetic field, line of sight, plasma
density and temperature, electron distribution function, and the source
dimensions, we compute time dependent radio emission (spectra and light
curves). The radio light curves (of both flux density and degree of
polarization) at all considered radio frequencies are than quantified in both
time domain (via computation of the full modulation amplitude as a function of
frequency) and in Fourier domain (oscillation spectra, phases, and partial
modulation amplitude) to form the signatures specific to a particular
oscillation mode and/or source parameter regime. We found that the parameter
regime and the involved MHD mode can indeed be distinguished using the
quantitative measures derived in the modeling. We apply the developed approach
to analyze radio burst recorded by Owens Valley Solar Array and report possible
detection of the sausage mode oscillation in one (partly occulted) flare and
kink or torsional oscillations in another flare.
|
We propose a hardware and software pipeline to fabricate flexible wearable
sensors and use them to capture deformations without line of sight. Our first
contribution is a low-cost fabrication pipeline to embed multiple aligned
conductive layers with complex geometries into silicone compounds. Overlapping
conductive areas from separate layers form local capacitors that measure dense
area changes. Contrary to existing fabrication methods, the proposed technique
only requires hardware that is readily available in modern fablabs. While area
measurements alone are not enough to reconstruct the full 3D deformation of a
surface, they become sufficient when paired with a data-driven prior. A novel
semi-automatic tracking algorithm, based on an elastic surface geometry
deformation, allows to capture ground-truth data with an optical mocap system,
even under heavy occlusions or partially unobservable markers. The resulting
dataset is used to train a regressor based on deep neural networks, directly
mapping the area readings to global positions of surface vertices. We
demonstrate the flexibility and accuracy of the proposed hardware and software
in a series of controlled experiments, and design a prototype of wearable
wrist, elbow and biceps sensors, which do not require line-of-sight and can be
worn below regular clothing.
|
A novel algorithm, called semantic line combination detector (SLCD), to find
an optimal combination of semantic lines is proposed in this paper. It
processes all lines in each line combination at once to assess the overall
harmony of the lines. First, we generate various line combinations from
reliable lines. Second, we estimate the score of each line combination and
determine the best one. Experimental results demonstrate that the proposed SLCD
outperforms existing semantic line detectors on various datasets. Moreover, it
is shown that SLCD can be applied effectively to three vision tasks of
vanishing point detection, symmetry axis detection, and composition-based image
retrieval. Our codes are available at https://github.com/Jinwon-Ko/SLCD.
|
We study monomial operators on $ L^2[0,1]$, that is bounded linear operators
that map each monomial $x^n$ to a multiple of $x^{p_n}$ for some $p_n$. We show
that they are all unitarily equivalent to weighted composition operators on a
Hardy space. We characterize what sequences $p_n$ can arise. In the case that
$p_n$ is a fixed translation of $n$, we give a criterion for boundedness of the
operator.
|
To expand the range in the colour-magnitude diagram where asteroseismology
can be applied, we organized a photometry campaign to find evidence for
solar-like oscillations in giant stars in the globular cluster M4. The aim was
to detect the comb-like p-mode structure characteristic for solar-like
oscillations in the amplitude spectra. The two dozen main target stars are in
the region of the bump stars and have luminosities in the range 50-140 Lsun. We
collected 6160 CCD frames and light curves for about 14000 stars were
extracted. We obtain high quality light curves for the K giants, but no clear
oscillation signal is detected. High precision differential photometry is
possible even in very crowded regions like the core of M4. Solar-like
oscillations are probably present in K giants, but the amplitudes are lower
than classical scaling laws predict.
|
Symmetric and sparse tensors arise naturally in many domains including linear
algebra, statistics, physics, chemistry, and graph theory. Symmetric tensors
are equal to their transposes, so in the $n$-dimensional case we can save up to
a factor of $n!$ by avoiding redundant operations. Sparse tensors, on the other
hand, are mostly zero, and we can save asymptotically by processing only
nonzeros. Unfortunately, specializing for both symmetry and sparsity at the
same time is uniquely challenging. Optimizing for symmetry requires
consideration of $n!$ transpositions of a triangular kernel, which can be
complex and error prone. Considering multiple transposed iteration orders and
triangular loop bounds also complicates iteration through intricate sparse
tensor formats. Additionally, since each combination of symmetry and sparse
tensor formats requires a specialized implementation, this leads to a
combinatorial number of cases. A compiler is needed, but existing compilers
cannot take advantage of both symmetry and sparsity within the same kernel. In
this paper, we describe the first compiler which can automatically generate
symmetry-aware code for sparse or structured tensor kernels. We introduce a
taxonomy for symmetry in tensor kernels, and show how to target each kind of
symmetry. Our implementation demonstrates significant speedups ranging from
1.36x for SSYMV to 30.4x for a 5-dimensional MTTKRP over the non-symmetric
state of the art.
|
The goal of our research is to understand how ideas propagate, combine and
are created in large social networks. In this work, we look at a sample of
relevant scientific publications in the area of high-frequency analog circuit
design and their citation distribution. A novel aspect of our work is the way
in which we categorize citations based on the reason and place of it in a
publication. We created seven citation categories from general domain
references, references to specific methods used in the same domain problem,
references to an analysis method, references for experimental comparison and so
on. This added information allows us to define two new measures to characterize
the creativity (novelty and usefulness) of a publication based on its pattern
of citations clustered by reason, place and citing scientific group. We
analyzed 30 publications in relevant journals since 2000 and their about 300
citations, all in the area of high-frequency analog circuit design. We observed
that the number of citations a publication receives from different scientific
groups matches a Levy type distribution: with a large number of groups citing a
publication relatively few times, and a very small number of groups citing a
publication a large number of times. We looked at the motifs a publication is
cited differently by different scientific groups.
|
Modified Derksen invariant HD^*(X) of an affine variety X is a subalgebra in
K[X] generated by kernels of all locally nilpotent derivations of K[X] with
slices. If there is a locally nilpotent derivation of K[X] with a slice then X
is a product of Y and a line, where Y is an affine variety. We prove that there
are three possibilities: A) HD^*(X) = K[X]; B) HD^*(X) is a proper infintely
generated subalgebra; C) HD^*(X) = \BK[Y]. We give examples for each case, and
also provide sufficient conditions for the variety Y so that the variety X
belongs to one of the type.
|
Thermonuclear supernovae, or Type-Ia supernovae (SNeIa), are an essential
tool of cosmology. Precise cosmological constraints are extracted from a Hubble
diagram defined by homogeneous distance indicators, but supernova homogeneity
is not guaranteed. The degree of heterogeneity within the SNeIa parent
population is unknown. In addition, event selections and standardization
procedures are based on empirical, optically-measured observables rather than
fundamental thermonuclear properties. Systematics are a natural consequence of
event selection from a diverse parent population. Quantifying the impact of
diversity-driven systematics is crucial to optimizing SNeIa as cosmic probes.
In this work, the empirical observables are used to calibrate previously
unidentified diversity-driven systematic uncertainties. The foundation of this
approach is the concept of "supernova siblings'', two or more supernovae hosted
by the same parent galaxy. Sibling-based calibrations isolate intrinsic
differences between supernovae; they control for source distance and host
galaxy dependencies that can conceal systematics or lead to their
underestimation. Newly calibrated distance modulus uncertainties are
approximately an order of magnitude larger than previously reported. The
physical origin of these uncertainties is plausibly attributed to the diverse
thermonuclear scenarios responsible for SNeIa and the inhomogeneous apparent
magnitudes induced by this diversity. Systematics mitigation strategies are
discussed. Cosmological parameter constraints extracted from a re-analysis of
the Pantheon+ SNeIa dataset are weaker than previously reported. Agreement with
early-Universe parameter estimates is achieved for a $\Lambda$CDM cosmology,
including a reduction of the Hubble Tension from $\sim$5$\sigma$ to <1$\sigma$.
|
This work presents a new sufficient condition for synthesizing nonlinear
controllers that yield bounded closed-loop tracking error transients despite
the presence of unmatched uncertainties that are concurrently being learned
online. The approach utilizes contraction theory and addresses fundamental
limitations of existing approaches by allowing the contraction metric to depend
on the unknown model parameters. This allows the controller to incorporate new
model estimates generated online without sacrificing its strong convergence and
bounded transients guarantees. The approach is specifically designed for
trajectory tracking so the approach is more broadly applicable to adaptive
model predictive control as well. Simulation results on a nonlinear system with
unmatched uncertainties demonstrates the approach.
|
The process of revising (or constructing) a policy at execution time -- known
as decision-time planning -- has been key to achieving superhuman performance
in perfect-information games like chess and Go. A recent line of work has
extended decision-time planning to imperfect-information games, leading to
superhuman performance in poker. However, these methods involve solving
subgames whose sizes grow quickly in the amount of non-public information,
making them unhelpful when the amount of non-public information is large.
Motivated by this issue, we introduce an alternative framework for
decision-time planning that is not based on solving subgames, but rather on
update equivalence. In this update-equivalence framework, decision-time
planning algorithms replicate the updates of last-iterate algorithms, which
need not rely on public information. This facilitates scalability to games with
large amounts of non-public information. Using this framework, we derive a
provably sound search algorithm for fully cooperative games based on mirror
descent and a search algorithm for adversarial games based on magnetic mirror
descent. We validate the performance of these algorithms in cooperative and
adversarial domains, notably in Hanabi, the standard benchmark for search in
fully cooperative imperfect-information games. Here, our mirror descent
approach exceeds or matches the performance of public information-based search
while using two orders of magnitude less search time. This is the first
instance of a non-public-information-based algorithm outperforming
public-information-based approaches in a domain they have historically
dominated.
|
Up to date, only lower and upper bounds for the optimal configuration of a
Square Array (A2) Group Testing (GT) algorithm are known. We establish exact
analytical formulae and provide a couple of applications of our result. First,
we compare the A2 GT scheme to several other classical GT schemes in terms of
the gain per specimen attained at optimal configuration. Second, operating
under objective Bayesian framework with the loss designed to attain minimum at
optimal GT configuration, we suggest the preferred choice of the group size
under natural minimal assumptions: the prior information regarding the
prevalence suggests that grouping and application of A2 is better than
individual testing. The same suggestion is provided for the Minimax strategy.
|
The 3SUM problem asks if an input $n$-set of real numbers contains a triple
whose sum is zero. We consider the 3POL problem, a natural generalization of
3SUM where we replace the sum function by a constant-degree polynomial in three
variables. The motivations are threefold. Raz, Sharir, and de Zeeuw gave a
$O(n^{11/6})$ upper bound on the number of solutions of trivariate polynomial
equations when the solutions are taken from the cartesian product of three
$n$-sets of real numbers. We give algorithms for the corresponding problem of
counting such solutions. Gr\o nlund and Pettie recently designed subquadratic
algorithms for 3SUM. We generalize their results to 3POL. Finally, we shed
light on the General Position Testing (GPT) problem: "Given $n$ points in the
plane, do three of them lie on a line?", a key problem in computational
geometry.
We prove that there exist bounded-degree algebraic decision trees of depth
$O(n^{\frac{12}{7}+\varepsilon})$ that solve 3POL, and that 3POL can be solved
in $O(n^2 {(\log \log n)}^\frac{3}{2} / {(\log n)}^\frac{1}{2})$ time in the
real-RAM model. Among the possible applications of those results, we show how
to solve GPT in subquadratic time when the input points lie on $o({(\log
n)}^\frac{1}{6}/{(\log \log n)}^\frac{1}{2})$ constant-degree polynomial
curves. This constitutes a first step towards closing the major open question
of whether GPT can be solved in subquadratic time.
To obtain these results, we generalize important tools --- such as batch
range searching and dominance reporting --- to a polynomial setting. We expect
these new tools to be useful in other applications.
|
The discrepancies between $b\to s\ell^+\ell^-$ data and the corresponding
Standard Model predictions point to the existence of new physics with a
significance at the $5\sigma$ level. While previously a lepton flavour
universality violating effect was preferred, the new $R(K^{(*)})$ and
$B_s\to\mu^+\mu^-$ measurements are now compatible with the Standard Model,
favouring a lepton flavour universal beyond the Standard Model contribution to
$C_9$. Since heavy new physics is generally chiral, and because of the
stringent constraints from charged lepton flavour violation, this poses a
challenge for model building. In this article, we point out a novel
possibility: a diquark, i.e. a coloured scalar, induces the Wilson coefficient
of the $(\bar s \gamma^\mu P_L b) (\bar c \gamma_\mu P_L c)$ operator at
tree-level, which then mixes into $O_9$ via an off-shell photon penguin. This
setup allows for a lepton flavour universal effect of $C_9\approx-0.5$, without
violating bounds from $\Delta M_s$, $\Delta\Gamma$, $B\to X_s\gamma$ and
$D^0-\bar D^0$ mixing. This scenario predicts a small and negative
$C_9^{\prime}$ and a light diquark, preferably with a mass around $500\,$GeV,
as compatible with the CMS di-di-jet analysis, and a deficit in the inclusive
$b\to c\bar c s$ rate.
|
Using the analytic extension method, we study Hawking radiation of an $(n +
4)$-dimensional Schwarzschild-de Sitter black hole. Under the condition that
the total energy is conserved, taking the reaction of the radiation of
particles to the spacetime into consideration and considering the relation
between the black hole event horizon and cosmological horizon, we obtain the
radiation spectrum of de Sitter spacetime. This radiation spectrum is no longer
a strictly pure thermal spectrum. It is related to the change of the
Bekenstein-Hawking(B-H) entropy corresponding the black hole event horizon and
cosmological horizon. The result satisfies the unitary principle. At the same
time, we also testify that the entropy of de Sitter spacetime is the sum of the
entropy of black hole event horizon and the one of cosmological horizon.
|
We construct the most general supersymmetric two boson system that is
integrable. We obtain the Lax operator and the nonstandard Lax representation
for this system. We show that, under appropriate redefinition of variables,
this reduces to the supersymmetric nonlinear Schr\"odinger equation without any
arbitrary parameter which is known to be integrable. We show that this
supersymmetric system has three local Hamiltonian structures just like the
bosonic counterpart and we show how the supersymmetric KdV equation can be
embedded into this system.
|
The concept of evolving intelligent system (EIS) provides an effective avenue
for data stream mining because it is capable of coping with two prominent
issues: online learning and rapidly changing environments. We note at least
three uncharted territories of existing EISs: data uncertainty, temporal system
dynamic, redundant data streams. This book chapter aims at delivering a
concrete solution of this problem with the algorithmic development of a novel
learning algorithm, namely PANFIS++. PANFIS++ is a generalized version of the
PANFIS by putting forward three important components: 1) An online active
learning scenario is developed to overcome redundant data streams. This module
allows to actively select data streams for the training process, thereby
expediting execution time and enhancing generalization performance, 2) PANFIS++
is built upon an interval type-2 fuzzy system environment, which incorporates
the so-called footprint of uncertainty. This component provides a degree of
tolerance for data uncertainty. 3) PANFIS++ is structured under a recurrent
network architecture with a self-feedback loop. This is meant to tackle the
temporal system dynamic. The efficacy of the PANFIS++ has been numerically
validated through numerous real-world and synthetic case studies, where it
delivers the highest predictive accuracy while retaining the lowest complexity.
|
Railways are a key infrastructure for any modern country. The reliability and
resilience of this peculiar transportation system may be challenged by
different shocks such as disruptions, strikes and adverse weather conditions.
These events compromise the correct functioning of the system and trigger the
spreading of delays into the railway network on a daily basis. Despite their
importance, a general theoretical understanding of the underlying causes of
these disruptions is still lacking. In this work, we analyse the Italian and
German railway networks by leveraging on the train schedules and actual delay
data retrieved during the year 2015. We use {these} data to infer simple
statistical laws ruling the emergence of localized delays in different areas of
the network and we model the spreading of these delays throughout the network
by exploiting a framework inspired by epidemic spreading models. Our model
offers a fast and easy tool for the preliminary assessment of the
{effectiveness of} traffic handling policies, and of the railway {network}
criticalities.
|
We study the ground state properties of the bond alternating $S=1/2$ quantum
spin chain whose Hamiltonian is H=\sum_j (S_{2j}^x S_{2j+1}^x +S_{2j}^y
S_{2j+1}^y +\lambda S_{2j}^z S_{2j+1}^z ) +\beta \sum_j {\bf S}_{2j-1} \cdot
{\bf S}_{2j} . When $\beta=0$, the ground state is a collection of local
singlets with a finite excitation gap. In the limit of strong ferromagnetic
coupling $\beta \to - \infty$, this is equivalent to the $S=1 \ XXZ$
Hamiltonian. It has several ground state phases in the $\lambda$-$\beta$ plane
including the gapful Haldane phase. They are characterized by a full breakdown,
partial breakdowns and a non-breakdown of the hidden discrete $Z_2 \times Z_2$
symmetry. The ground state phase diagram is obtained by series expansions.
|
Deep reinforcement learning (deep RL) excels in various domains but lacks
generalizability and interpretability. On the other hand, programmatic RL
methods (Trivedi et al., 2021; Liu et al., 2023) reformulate RL tasks as
synthesizing interpretable programs that can be executed in the environments.
Despite encouraging results, these methods are limited to short-horizon tasks.
On the other hand, representing RL policies using state machines (Inala et al.,
2020) can inductively generalize to long-horizon tasks; however, it struggles
to scale up to acquire diverse and complex behaviors. This work proposes the
Program Machine Policy (POMP), which bridges the advantages of programmatic RL
and state machine policies, allowing for the representation of complex
behaviors and the address of long-term tasks. Specifically, we introduce a
method that can retrieve a set of effective, diverse, and compatible programs.
Then, we use these programs as modes of a state machine and learn a transition
function to transition among mode programs, allowing for capturing repetitive
behaviors. Our proposed framework outperforms programmatic RL and deep RL
baselines on various tasks and demonstrates the ability to inductively
generalize to even longer horizons without any fine-tuning. Ablation studies
justify the effectiveness of our proposed search algorithm for retrieving a set
of programs as modes.
|
The basic objective of the current research paper is to investigate the
structure and the algebraic varieties of Hom-associative dialgebras. We
elaborate a classification of $n$-dimensional Hom-associative dialgebras for
$n\leq4$. Additionally, using the classification result of Hom-associative
dialgebras, we characterize the $\alpha$-derivations and centroids of
low-dimensional Hom-associative dialgebras. Furthermore, we equally tackle
certain features of derivations and centroids in the light of associative
dialgebras and compute the centroids of low-dimensional associative dialgebras.
|
We present J-H-K' photometry for a sample of 45 high redshift quasars found
by the Sloan Digital Sky Survey. The sample was originally selected on the
basis of optical colors and spans a redshift range from 3.6 to 5.03. Our
photometry reflects the rest-frame
SED longward of Ly alpha for all redshifts. The results show that the near-IR
colors of high redshift quasars are quite uniform. We have modelled the
continuum shape of the quasars (from just beyond Ly alpha to ~4000 A) with a
power law of the form f_nu \propto nu^alpha, and find <alpha > =-0.57 with a
scatter of 0.33. This value is similar to what is found for lower redshift
quasars over the same restframe wavelength range, and we conclude that there is
hardly any evolution in the continuum properties of optically selected quasars
up to redshift 5. The spectral indices found by combining near-IR with optical
photometry are in general consistent but slightly flatter than what is found
for the same quasars using the optical spectra and photometry alone, showing
that the continuum region used to determine the spectral indices can somewhat
influence the results.
|
The matrix element \Vud of the CKM matrix can be determined by two
independent measurements in neutron decay: the neutron lifetime $\tau_n$ and
the ratio of coupling constants $\lambda=g_A/g_V$, which is most precisely
determined by measurements of the beta asymmetry angular correlation
coefficient~$A$. We present recent progress on the determination of these
coupling constants.
|
In this paper we provide examples of maps from almost complex domains into
pseudo-Riemannian symmetric targets, which are pluriharmonic and not
integrable, i.e. do not admit an associated family. More precisely, for one
class of examples the source has a non-integrable complex structure, like for
instance a nearly Kaehler structure and the target is a Riemannian symmetric
space and for the other class the source is a complex manifold and the target
is a pseudo-Riemannian symmetric space. These examples show, that a former
result on the existence of associated families is sharp.
|
The uncertainty and robustness of Computable General Equilibrium models can
be assessed by conducting a Systematic Sensitivity Analysis. Different methods
have been used in the literature for SSA of CGE models such as Gaussian
Quadrature and Monte Carlo methods. This paper explores the use of Quasi-random
Monte Carlo methods based on the Halton and Sobol' sequences as means to
improve the efficiency over regular Monte Carlo SSA, thus reducing the
computational requirements of the SSA. The findings suggest that by using
low-discrepancy sequences, the number of simulations required by the regular MC
SSA methods can be notably reduced, hence lowering the computational time
required for SSA of CGE models.
|
Epidemiological models with constant parameters may not capture satisfactory
infection patterns in the presence of pharmaceutical and non-pharmaceutical
mitigation measures during a pandemic, since infectiousness is a function of
time. In this paper, an Epidemiology-Informed Neural Network algorithm is
introduced to learn the time-varying transmission rate for the COVID-19
pandemic in the presence of various mitigation scenarios. There are
asymptomatic infectives, mostly unreported, and the proposed algorithm learns
the proportion of the total infective individuals that are asymptomatic
infectives. Using cumulative and daily reported cases of the symptomatic
infectives, we simulate the impact of non-pharmaceutical mitigation measures
such as early detection of infectives, contact tracing, and social distancing
on the basic reproduction number. We demonstrate the effectiveness of
vaccination on the transmission of COVID-19. The accuracy of the proposed
algorithm is demonstrated using error metrics in the data-driven simulation for
COVID-19 data of Italy, South Korea, the United Kingdom, and the United States.
|
Fermions and hardcore bosons share the same restriction: no more than one
particle can occupy a single site in a lattice system. Specifically, in one
dimension, two systems can share the same matrix representation. In this work,
we investigate both the fermion and hardcore-boson models with nearest-neighbor
(NN) interaction in a ring lattice. We construct the exact eigenstates of the
hardcore-boson model with resonant NN interaction and show that they possess
off-diagonal long-range order (ODLRO) in the thermodynamic limit. In
comparison, the fermionic counterpart does not support such a feature due to
the different particle statistics, although they share an identical energy
spectrum. In addition, we examine the effect of the periodic boundary condition
on the dynamics of the condensate states through numerical simulations.
|
Domain specific localization of eigenstates has been a persistent observation
for systems with local symmetries. The underlying mechanism for this
localization behaviour has however remained elusive. We provide here an
analysis of locally reflection symmetric tight-binding Hamiltonian which
attempts at identifying the key features that lead to the localized
eigenstates. A weak coupling expansion of closed-form expressions for the
eigenvectors demonstrates that the degeneracy of on-site energies occuring at
the center of the locally symmetric domains represents the nucleus for
eigenstates spreading across the domain. Since the symmetry-related subdomains
constituting a locally symmetric domain are isospectral we encounter pairwise
degenerate eigenvalues that split linearly with an increasing coupling strength
of the subdomains. The coupling to the (non-symmetric) environment in an
extended setup then leads to the survival of a certain system specific fraction
of linearly splitting eigenvalues. The latter go hand in hand with the
eigenstate localization on the locally symmetric domain. We provide a brief
outlook addressing possible generalizations of local symmetry transformations
while maintaining isospectrality.
|
We compute the image of a polynomial $GL_N$-module under the
Etingof-Freund-Ma functor \cite{EFM}. We give a combinatorial description of
the image in terms of standard tableaux on a collection of skew shapes and
analyze weights of the image in terms of contents.
|
Tuning hyperparameters for machine learning algorithms is a tedious task, one
that is typically done manually. To enable automated hyperparameter tuning,
recent works have started to use techniques based on Bayesian optimization.
However, to practically enable automated tuning for large scale machine
learning training pipelines, significant gaps remain in existing libraries,
including lack of abstractions, fault tolerance, and flexibility to support
scheduling on any distributed computing framework. To address these challenges,
we present Mango, a Python library for parallel hyperparameter tuning. Mango
enables the use of any distributed scheduling framework, implements intelligent
parallel search strategies, and provides rich abstractions for defining complex
hyperparameter search spaces that are compatible with scikit-learn. Mango is
comparable in performance to Hyperopt, another widely used library. Mango is
available open-source and is currently used in production at Arm Research to
provide state-of-art hyperparameter tuning capabilities.
|
This paper presents an optimal control strategy for operating a solar hybrid
system consisting of solar photovoltaic (PV) and a high-power, low-storage
battery energy storage system (BESS). A state-space model of the hybrid PV
plant is first derived, based on which an adaptive model predictive controller
is designed. The controller's objective is to control the PV and BESS to follow
power setpoints sent to the the hybrid system while maintaining desired power
reserves and meeting system operational constraints. Furthermore, an extended
Kalman filter (EKF) is implemented for estimating the battery SOC, and an error
sensitivity is executed to assess its limitations. To validate the proposed
strategy, detailed EMT models of the hybrid system are developed so that losses
and control limits can be quantified accurately. Day-long simulations are
performed in an OPAL-RT real-time simulator using second-by-second actual PV
farm data as inputs. Results verify that the proposed method can follow power
setpoints while maintaining power reserves in days of high irradiance
intermittency even with a small BESS storage.
|
We describe an automated method for assigning the most probable physical
parameters to the components of an eclipsing binary, using only its photometric
light curve and combined colors. With traditional methods, one attempts to
optimize a multi-parameter model over many iterations, so as to minimize the
chi-squared value. We suggest an alternative method, where one selects pairs of
coeval stars from a set of theoretical stellar models, and compares their
simulated light curves and combined colors with the observations. This approach
greatly reduces the parameter space over which one needs to search, and allows
one to estimate the components' masses, radii and absolute magnitudes, without
spectroscopic data. We have implemented this method in an automated program
using published theoretical isochrones and limb-darkening coefficients. Since
it is easy to automate, this method lends itself to systematic analyses of
datasets consisting of photometric time series of large numbers of stars, such
as those produced by OGLE, MACHO, TrES, HAT, and many others surveys.
|
Multi-head attention, a collection of several attention mechanisms that
independently attend to different parts of the input, is the key ingredient in
the Transformer. Recent work has shown, however, that a large proportion of the
heads in a Transformer's multi-head attention mechanism can be safely pruned
away without significantly harming the performance of the model; such pruning
leads to models that are noticeably smaller and faster in practice. Our work
introduces a new head pruning technique that we term differentiable subset
pruning. Intuitively, our method learns per-head importance variables and then
enforces a user-specified hard constraint on the number of unpruned heads. The
importance variables are learned via stochastic gradient descent. We conduct
experiments on natural language inference and machine translation; we show that
differentiable subset pruning performs comparably or better than previous works
while offering precise control of the sparsity level.
|
We present two different aspects of the anomalies in quantum field theory.
One is the dispersion relation aspect, the other is differential geometry where
we derive the Stora--Zumino chain of descent equations.
|
We present a direct comparison of the Pan-Andromeda Archaeological Survey
(PAndAS) observations of the stellar halo of M31 with the stellar halos of 6
galaxies from the Auriga simulations. We process the simulated halos through
the Auriga2PAndAS pipeline and create PAndAS-like mocks that fold in all
observational limitations of the survey data (foreground contamination from the
Milky Way stars, incompleteness of the stellar catalogues, photometric
uncertainties, etc). This allows us to study the survey data and the mocks in
the same way and generate directly comparable density maps and radial density
profiles. We show that the simulations are overall compatible with the
observations. Nevertheless, some systematic differences exist, such as a
preponderance for metal-rich stars in the mocks. While these differences could
suggest that M31 had a different accretion history or has a different mass
compared to the simulated systems, it is more likely a consequence of an
under-quenching of the star formation history of galaxies, related to the
resolution of the Auriga simulations. The direct comparison enabled by our
approach offers avenues to improve our understanding of galaxy formation as
they can help pinpoint the observable differences between observations and
simulations. Ideally, this approach will be further developed through an
application to other stellar halo simulations. To facilitate this step, we
release the pipeline to generate the mocks, along with the six mocks presented
and used in this contribution.
|
We propose an observable which involves measuring the properties (transverse
momentum $p_{h\perp}$ and energy fraction $z_h$) of an identified hadron inside
a groomed jet. The jet is identified with an anti-kT/CA algorithm and is
groomed by implementing the modified mass drop procedure with an energy cut-off
parameter $z_{cut}$. The transverse momentum of the hadron inside the jet is
measured with respect to the groomed jet axis. We obtain a factorization
theorem in the framework of Soft Collinear Effective Theory (SCET), to define a
Transverse Momentum Dependent Fragmenting Jet Function (TMDFJF). The TMDFJF is
factorized into collinear and collinear soft modes by matching onto SCET$_+$.
We resum large logarithms in $E_J/p_{h\perp}$, where $E_J$ is the ungroomed jet
energy, to NLL accuracy and apply this formalism for computing the shape of the
$p_{h\perp}$ distribution of a pion produced in an $e^+ +e^-$ collision. We
observe that the introduction of grooming makes this observable insensitive to
non-global logarithms and particularly sensitive to non-perturbative physics of
the transverse momentum dependent evolution at low values of $p_{h\perp}$,
which can be probed in the variation of the cut-off parameter $z_{cut}$ of the
groomer. We discuss how this observable can be used to distinguish between
non-perturbative models that describe universal TMD evolution and provide a
window into the three dimensional structure of hadrons.
|
Polyelectrolyte microcapsules loaded with fluorescent dyes have been proposed
as biosensors to monitor local pH and ionic strength for diagnostic purposes.
In the case of charged microcapsules, however, the local electric field can
cause deviations of ion densities inside the cavities, potentially resulting in
misdiagnosis of some diseases. Using nonlinear Poisson-Boltzmann theory, we
systematically investigate these deviations induced by charged microcapsules.
Our results show that the microcapsule charge density, as well as the capsule
and salt concentrations, contribute to deviations of local ion concentrations
and pH. Our findings are relevant for applications of polyelectrolyte
microcapsules with encapsulated ion-sensitive dyes as biosensors.
|
We show that a large class of maximally degenerating families of
n-dimensional polarized varieties come with a canonical basis of sections of
powers of the ample line bundle. The families considered are obtained by
smoothing a reducible union of toric varieties governed by a wall structure on
a real n-(pseudo-)manifold. Wall structures have previously been constructed
inductively for cases with locally rigid singularities and by Gromov-Witten
theory for mirrors of log Calabi-Yau surfaces and K3 surfaces by various
combinations of the authors. For trivial wall structures on the n-torus we
retrieve the classical theta functions. Possible applications include mirror
symmetry, geometric compactifications of moduli of certain polarized varieties
via stable pairs and geometric quantization.
|
To mitigate the imbalance in the number of assignees in the
Hospitals/Residents problem, Goko et al. [Goko et al., Maximally Satisfying
Lower Quotas in the Hospitals/Residents Problem with Ties, Proc. STACS 2022,
pp. 31:1--31:20] studied the Hospitals/Residents problem with lower quotas
whose goal is to find a stable matching that satisfies lower quotas as much as
possible. In their paper, preference lists are assumed to be complete, that is,
the preference list of each resident (resp., hospital) is assumed to contain
all the hospitals (resp., residents).
In this paper, we study a more general model where preference lists may be
incomplete. For four natural scenarios, we obtain maximum gaps of the best and
worst solutions, approximability results, and inapproximability results.
|
In this work, we study the tidal response of a rotating BTZ black hole to the
scalar tidal perturbation. We show that the real component of the tidal
response function isn't zero, indicating that a rotating BTZ black hole
possesses non-zero tidal Love numbers. Additionally, we observe scale-dependent
behaviour, known as log-running, in the tidal response function. We also
conduct a separate analysis on an extremal rotating BTZ black hole, finding
qualitative similarities with its non-extremal counterpart. In addition, we
present a procedure to calculate the tidal response function of a charged
rotating BTZ black hole as well.
|
Non-ideal magnetohydrodynamic effects that rule the coupling of the magnetic
field to the circumstellar gas during the low-mass star formation process
depend heavily on the local physical conditions, such as the ionization
fraction of the gas. The purpose of this work is to observationally
characterize the level of ionization of the circumstellar gas at small envelope
radii and investigate its relation to the efficiency of the coupling between
the star-forming gas and the magnetic field in the Class 0 protostar B335. We
have obtained molecular line emission maps of B335 with ALMA, which we use to
measure the deuteration fraction of the gas, its ionization fraction, and the
cosmic-ray ionization rate, at envelope radii $\lesssim$1000 au. We find large
fractions of ionized gas, $\chi_{e} \simeq 1-8 \times 10^{-6}$. Our
observations also reveal an enhanced ionization that increases at small
envelope radii, reaching values up to $\zeta_{CR} \simeq 10^{-14}$~s$^{-1}$ at
a few hundred au from the central protostellar object. We show that this
extreme ionization rate can be attributed to the presence of cosmic rays
accelerated close to the protostar. We report the first resolved map of the
cosmic-ray ionization rate at scales $\lesssim 1000$~au in a solar-type Class 0
protostar, finding remarkably high values. Our observations suggest that local
acceleration of cosmic rays, and not the penetration of interstellar Galactic
cosmic rays, may be responsible for the gas ionization in the inner envelope,
potentially down to disk forming scales. If confirmed, our findings imply that
protostellar disk properties may also be determined by local processes setting
the coupling between the gas and the magnetic field, and not only by the amount
of angular momentum available at large envelope scales and the magnetic field
strength in protostellar cores.
|
We study the fluctuation-induced dissipative dynamics of the quantized center
of mass motion of a polarizable dielectric particle trapped near a surface. The
particle's center of mass is treated as an open quantum system coupled to the
electromagnetic field acting as its environment, with the resulting system
dynamics described by a quantum Brownian motion master equation. The
dissipation and decoherence of the particle's center of mass are characterized
by the modified spectral density of the electromagnetic field that depends on
surface losses and the strength of the classical trap field. Our results are
relevant to experiments with levitated dielectric particles near surfaces,
illustrating potential ways of mitigating fluctuation-induced decoherence while
preparing such systems in macroscopic quantum states.
|
The Yang-Lee edge singularity is a quintessential nonunitary critical
phenomenon accompanied by anomalous scaling laws. However, an imaginary
magnetic field involved in this critical phenomenon makes its physical
implementation difficult. By invoking the quantum-classical correspondence to
embed the Yang-Lee edge singularity in a quantum system with an ancilla qubit,
we demonstrate a physical realization of the nonunitary quantum criticality in
an open quantum system. Here the nonunitary criticality is identified with the
singularity at an exceptional point caused by postselection of quantum
measurement.
|
Watching TV not only provides news information but also gives an opportunity
for different generations to communicate. With the proliferation of
smartphones, PC, and the Internet, increase the opportunities for communication
in front of the television is also likely to diminish. This has led to some
problems further from face-to-face such as a lack of self-control and
insufficient development of communication skills. This paper proposes a
TV-watching companion robot with open-domain chat ability. The robot contains
two modes: TV-watching mode and conversation mode. In TV-watching mode, the
robot first extracts keywords from the TV program and then generates the
disclosure utterances based on the extracted keywords as if enjoying the TV
program. In the conversation mode, the robot generates question utterances with
keywords in the same way and then employs a topics-based dialog management
method consisting of multiple dialog engines for rich conversations related to
the TV program. We conduct the initial experiments and the result shows that
all participants from the three groups enjoyed talking with the robot, and the
question about their interests in the robot was rated 6.5/7-levels. This
indicates that the proposed conversational features of TV-watching Companion
Robot have the potential to make our daily lives more enjoyable. Under the
analysis of the initial experiments, we achieve further experiments with more
participants by dividing them into two groups: a control group without a robot
and an intervention group with a robot. The results show that people prefer to
talk to robots because the robot will bring more enjoyable, relaxed, and
interesting.
|
A theory of matter wave interference is developed in which resonant optical
fields interact with two-level atoms. When recoil effects are included, spatial
modulation of the atomic density can occur for times that are greater than or
comparable with the inverse recoil frequency. In this regime, the atoms exhibit
matter-wave interference. Two specific atom field geometries are considered. In
the first, atoms characterized by a homogeneous velocity distribution are
subjected to a single radiation pulse. The pulse excites the atoms which then
decay back to the lower state. The spatial modulation of the total atomic
density is calculated as a function of $t$, where $t$ is the time following the
pulse. In contrast to the normal Talbot effect, the spatially modulated density
is not a periodic function of $ t,$ owing to spontaneous emission; however,
after a sufficiently long time, the contribution from spontaneous processes no
longer plays a role and the Talbot periodicity is restored. In the second
atom-field geometry, there are two pulses separated by an interval $T$. The
atomic velocity distribution in this case is assumed to be inhomogeneously
broadened. In contrast to the normal Talbot-Lau effect, the spatially modulated
density is not a periodic function of $T$, owing to spontaneous emission;
however, for sufficiently long time, the contribution from spontaneous
processes no longer plays a role and the Talbot periodicity is restored. The
structure of the spatially modulated density is studied, and is found to mirror
the atomic density following the first pulse. The spatially modulated atomic
density serves as an indirect probe of the distribution of spontaneously
emitted radiation.
|
Anaphora and ellipses are two common phenomena in dialogues. Without
resolving referring expressions and information omission, dialogue systems may
fail to generate consistent and coherent responses. Traditionally, anaphora is
resolved by coreference resolution and ellipses by query rewrite. In this work,
we propose a novel joint learning framework of modeling coreference resolution
and query rewriting for complex, multi-turn dialogue understanding. Given an
ongoing dialogue between a user and a dialogue assistant, for the user query,
our joint learning model first predicts coreference links between the query and
the dialogue context, and then generates a self-contained rewritten user query.
To evaluate our model, we annotate a dialogue based coreference resolution
dataset, MuDoCo, with rewritten queries. Results show that the performance of
query rewrite can be substantially boosted (+2.3% F1) with the aid of
coreference modeling. Furthermore, our joint model outperforms the
state-of-the-art coreference resolution model (+2% F1) on this dataset.
|
A practical strategy for synchronizing the properties of compound Josephson
junction rf-SQUID qubits on a multiqubit chip has been demonstrated. The
impacts of small ($\sim1%$) fabrication variations in qubit inductance and
critical current can be minimized by the application of a custom tuned flux
offset to the CJJ structure of each qubit. This strategy allows for
simultaneous synchronization of the qubit persistent current and tunnel
splitting over a range of external bias parameters that is relevant for the
implementation of an adiabatic quantum processor.
|
Two of the major obstacles to achieve quantum computing (QC) are (i)
scalability to many qubits and (ii) controlled connectivity between any
selected qubits. Using Josephson charge qubits, here we propose an
experimentally realizable method to efficiently solve these two central
problems. Since any two charge qubits can be effectively coupled by an
experimentally accessible inductance, the proposed QC architecture is scalable.
In addition, we formulate an efficient and realizable QC scheme that requires
only one (instead of two or more) two-bit operation to implement conditional
gates.
|
We revisit the radiation mechanism of relativistic electrons in the
stochastic magnetic field and apply it to the high-energy emissions of
gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible
explanation for GRB prompt emission in the condition of a large electron
deflection angle. In the turbulent scenario, the radiative spectral property of
GRB prompt emission is decided by the kinetic energy spectrum of turbulence.
The intensity of the random and small-scale magnetic field is determined by the
viscous scale of the turbulent eddy. The microphysical parameters $\epsilon_e$
and $\epsilon_B$ can be obtained. The acceleration and cooling timescales are
estimated as well. Due to particle acceleration in magnetized filamentary
turbulence, the maximum energy released from the relativistic electrons can
reach a value of about $10^{14}$ eV. The GeV GRBs are possible sources of
high-energy cosmic-ray.
|
In a target communication system, a delicately designed frequency offset
estimation scheme is required to meet certain decoding performance. In this
paper, we proposed at wo-step estimation scheme, coarse and residual, with
different value of an time interval parameter. A result of RF conduction test
shows that the proposed method has an 1dB gain of SNR compared to coarse-only
estimator. A result of the commercial test also indicates the proposed method
outperforms coarse-only estimator especially in low SNR condition.
|
We compute, via motivic wall-crossing, the generating function of virtual
motives of the Quot scheme of points on $\mathbb{A}^3$, generalising to higher
rank a result of Behrend, Bryan and Szendr\H{o}i. We show that this motivic
partition function converges to a Gaussian distribution, extending a result of
Morrison.
|
We list up all the possible local orbit types of hyperbolic or elliptic
orbits for the isotropy representations of semisimple pseudo-Riemannian
symmetric spaces. It is key to give a recipe to determine the local orbit types
of hyperbolic principal orbits by using three kind of restricted root systems
and Satake diagrams associated with semisimple pseudo-Riemannian symmetric
spaces.
|
Convolutional networks (ConvNets) have become a popular approach to computer
vision. It is important to accelerate ConvNet training, which is
computationally costly. We propose a novel parallel algorithm based on
decomposition into a set of tasks, most of which are convolutions or FFTs.
Applying Brent's theorem to the task dependency graph implies that linear
speedup with the number of processors is attainable within the PRAM model of
parallel computation, for wide network architectures. To attain such
performance on real shared-memory machines, our algorithm computes convolutions
converging on the same node of the network with temporal locality to reduce
cache misses, and sums the convergent convolution outputs via an almost
wait-free concurrent method to reduce time spent in critical sections. We
implement the algorithm with a publicly available software package called ZNN.
Benchmarking with multi-core CPUs shows that ZNN can attain speedup roughly
equal to the number of physical cores. We also show that ZNN can attain over
90x speedup on a many-core CPU (Xeon Phi Knights Corner). These speedups are
achieved for network architectures with widths that are in common use. The task
parallelism of the ZNN algorithm is suited to CPUs, while the SIMD parallelism
of previous algorithms is compatible with GPUs. Through examples, we show that
ZNN can be either faster or slower than certain GPU implementations depending
on specifics of the network architecture, kernel sizes, and density and size of
the output patch. ZNN may be less costly to develop and maintain, due to the
relative ease of general-purpose CPU programming.
|
We investigate the prospects for micron-scale acoustic wave components and
circuits on chip in solid planar structures that do not require suspension. We
leverage evanescent guiding of acoustic waves by high slowness contrast
materials readily available in silicon complementary metal-oxide semiconductor
(CMOS) processes. High slowness contrast provides strong confinement of GHz
frequency acoustic fields in micron-scale structures. We address the
fundamental implications of intrinsic material and radiation losses on
operating frequency, bandwidth, device size and as a result practicality of
multi-element microphononic circuits based on solid embedded waveguides. We
show that a family of acoustic components based on evanescently guided acoustic
waves, including waveguide bends, evanescent couplers, Y-splitters, and
acoustic-wave microring resonators, can be realized in compact, micron-scale
structures, and provide basic scaling and performance arguments for these
components based on material properties and simulations. We further find that
wave propagation losses are expected to permit high quality factor (Q),
narrowband resonators and propagation lengths allowing delay lines and the
coupling or cascading of multiple components to form functional circuits, of
potential utility in guided acoustic signal processing on chip. We also address
and simulate bends and radiation loss, providing insight into routing and
resonators. Such circuits could be monolithically integrated with electronic
and photonic circuits on a single chip with expanded capabilities.
|
To substantially enhance robot intelligence, there is a pressing need to
develop a large model that enables general-purpose robots to proficiently
undertake a broad spectrum of manipulation tasks, akin to the versatile
task-planning ability exhibited by LLMs. The vast diversity in objects, robots,
and manipulation tasks presents huge challenges. Our work introduces a
comprehensive framework to develop a foundation model for general robotic
manipulation that formalizes a manipulation task as contact synthesis.
Specifically, our model takes as input object and robot manipulator point
clouds, object physical attributes, target motions, and manipulation region
masks. It outputs contact points on the object and associated contact forces or
post-contact motions for robots to achieve the desired manipulation task. We
perform extensive experiments both in the simulation and real-world settings,
manipulating articulated rigid objects, rigid objects, and deformable objects
that vary in dimensionality, ranging from one-dimensional objects like ropes to
two-dimensional objects like cloth and extending to three-dimensional objects
such as plasticine. Our model achieves average success rates of around 90\%.
Supplementary materials and videos are available on our project website at
https://manifoundationmodel.github.io/.
|
In quantum information, it is of high importance to efficiently detect
entanglement. Generally, it needs quantum tomography to obtain state density
matrix. However, it would consumes a lot of measurement resources, and the key
is how to reduce the consumption. In this paper, we discovered the relationship
between convolutional layer of artificial neural network and the average value
of an observable operator in quantum mechanics. Then we devise a branching
convolutional neural network which can be applied to detect entanglement in
2-qubit quantum system. Here, we detect the entanglement of Werner state,
generalized Werner state and general 2-qubit states, and observable operators
which are appropriate for detection can be automatically found. Beside,
compared with privious works, our method can achieve higher accuracy with fewer
measurements for quantum states with specific form. The results show that the
convolutional neural network is very useful for efficiently detecting quantum
entanglement.
|
In this work we develop an approach to obtain analytical expressions for
potentials in an impenetrable box. It is illustrated through the particular
cases of the harmonic oscillator and the Coulomb potential. In this kind of
system the energy expression respect the correct quantum limits, which is a
very important quality. The similarity of this kind of problem with the quasi
exactly solvable potentials is explored in order to accomplish our goals.
|
We give an overview of literature related to J\"urgen Ehlers' pioneering 1981
paper on Frame theory--a theoretical framework for the unification of General
Relativity and the equations of classical Newtonian gravitation. This
unification encompasses the convergence of one-parametric families of
four-dimensional solutions of Einstein's equations of General Relativity to a
solution of equations of a Newtonian theory if the inverse of a causality
constant goes to zero. As such the corresponding light cones open up and become
space-like hypersurfaces of constant absolute time on which Newtonian solutions
are found as a limit of the Einsteinian ones. It is explained what it means to
not consider the `standard-textbook' Newtonian theory of gravitation as a
complete theory unlike Einstein's theory of gravitation. In fact, Ehlers' Frame
theory brings to light a modern viewpoint in which the `standard' equations of
a self-gravitating Newtonian fluid are Maxwell-type equations. The consequences
of Frame theory are presented for Newtonian cosmological dust matter expressed
via the spatially projected electric part of the Weyl tensor, and for the
formulation of characteristic quasi-Newtonian initial data on the light cone of
a Bondi-Sachs metric.
|
Recently, it was pointed out that soft masses of the supersymmetric gauge
theories with extra dimensions tends to a flavor conserving point, which is a
desirable scenario in gravity mediation models. We point out that in 6D we must
consider the anomaly free condition in addition to the condition on the
asymptotic freedom. From this, we find $E_6$, $E_7$ and $E_8$ are natural
candidates in 6D. There is no SU(N) model, but there exist two SO(10) models
and SO(2n) models(one each for each $n\ge 6$) satisfying these conditions. In 5
dimensions, there is no such condition on anomaly freedom, but the softening
may not be enough.
|
Asymptotic normality of intermediate order statistics taken from univariate
iid random variables is well-known. We generalize this result to random vectors
in arbitrary dimension, where the order statistics are taken componentwise.
|
Electric dipole moments of nuclei, diamagnetic atoms, and certain molecules
are induced by CP-violating nuclear forces. Naive dimensional analysis predicts
these forces to be dominated by long-range one-pion-exchange processes, with
short-range forces entering only at next-to-next-to-leading order in the chiral
expansion. Based on renormalization arguments we argue that a consistent
picture of CP-violating nuclear forces requires a leading-order short-distance
operator contributing to ${}^1S_0$-${}^3P_0$ transitions, due to the attractive
and singular nature of the strong tensor force in the ${}^3P_0$ channel. The
short-distance operator leads to $\mathcal O(1)$ corrections to static and
oscillating, relevant for axion searches, electric dipole moments. We discuss
strategies how the finite part of the associated low-energy constant can be
determined in the case of CP violation from the QCD theta term by the
connection to charge-symmetry violation in nuclear systems.
|
We investigate the transport properties of
La$_{1.8-x}$Eu$_{0.2}$Sr$_x$CuO$_4$ ($x=0.04$, 0.08, 0.125, 0.15, 0.2) with a
special focus on the Nernst effect in the normal state. Various anomalous
features are present in the data. For $x=0.125$ and 0.15 a kink-like anomaly is
present in the vicinity of the onset of charge stripe order in the LTT phase,
suggestive of enhanced positive quasiparticle Nernst response in the stripe
ordered phase. At higher temperature, all doping levels except $x=0.2$ exhibit
a further kink anomaly in the LTO phase which cannot unambiguously be related
to stripe order. Moreover, a direct comparison between the Nernst coefficients
of stripe ordering La$_{1.8-x}$Eu$_{0.2}$Sr$_x$CuO$_4$ and superconducting
La$_{2-x}$Sr$_x$CuO$_4$ at the doping levels $x=0.125$ and $x=0.15$ reveals
only weak differences. Our findings make high demands on any scenario
interpreting the Nernst response in hole-doped cuprates.
|
From more than half a century ago indexing scientific articles has been
studied intensively to provide a more efficient data retrieval and to conserve
researchers invaluable time. In the last two decades with the emergence of the
World Wide Web and the rapid growth in the number of scientific documents
online many academic databases and search engines were launched with almost
similar structure in order to reduce the difficulty in finding, relating and
sorting of the existing scientific documents published online. The dramatic
increase of the scientific documents in the last few years makes it necessary
that the retrieved information by the search engines be analyzed and more
organized and interpretable representation be displayed to the users.
Information visualization is a great way for exploration of large and complex
data sets, therefore it can be a natural candidate for the purpose of
generating more comprehensible search results for the citation and academic
databases. In this survey the usage pattern of the participants and their
demands and ideas for the existence of other beneficial methods for literature
review has been questioned and the results are quantitatively analyzed.
|
The rapid proliferation of ChatGPT has incited debates regarding its impact
on human writing. Amid concerns about declining writing standards, this study
investigates the role of ChatGPT in facilitating academic writing, especially
among language learners. Using a case study approach, this study examines the
experiences of Kailing, a doctoral student, who integrates ChatGPT throughout
their academic writing process. The study employs activity theory as a lens for
understanding writing with generative AI tools and data analyzed includes
semi-structured interviews, writing samples, and GPT logs. Results indicate
that Kailing effectively collaborates with ChatGPT across various writing
stages while preserving her distinct authorial voice and agency. This
underscores the potential of AI tools such as ChatGPT to enhance academic
writing for language learners without overshadowing individual authenticity.
This case study offers a critical exploration of how ChatGPT is utilized in the
academic writing process and the preservation of a student's authentic voice
when engaging with the tool.
|
Turbulence is ubiquitously observed in nearly collisionless heliospheric
plasmas, including the solar wind and corona and the Earth's magnetosphere.
Understanding the collisionless mechanisms responsible for the energy transfer
from the turbulent fluctuations to the particles is a frontier in kinetic
turbulence research. Collisionless energy transfer from the turbulence to the
particles can take place reversibly, resulting in non-thermal energy in the
particle velocity distribution functions (VDFs) before eventual collisional
thermalization is realized. Exploiting the information contained in the
fluctuations in the VDFs is valuable. Here we apply a recently developed method
based on VDFs, the field-particle correlation technique, to a $\beta=1$,
solar-wind-like, low-frequency Alfv\'enic turbulence simulation with well
resolved phase space to identify the field-particle energy transfer in velocity
space. The field-particle correlations reveal that the energy transfer,
mediated by the parallel electric field, results in significant structuring of
the ion and electron VDFs in the direction parallel to the magnetic field.
Fourier modes representing the length scales between the ion and electron
gyroradii show that energy transfer is resonant in nature, localized in
velocity space to the Landau resonances for each Fourier mode. The energy
transfer closely follows the Landau resonant velocities with varying
perpendicular wavenumber $k_\perp$ and plasma $\beta$. This resonant signature,
consistent with Landau damping, is observed in all diagnosed Fourier modes that
cover the dissipation range of the simulation.
|
We provide a detailed derivation of the low-energy model for Zn-diluted
La2CuO4 in the limit of low doping together with a study of the ground-state
properties of that model. We consider Zn-doped La2CuO4 within a framework of
the three-band Hubbard model, which closely describes high-Tc cuprates on the
energy scale of the most relevant atomic orbitals. Qualitatively, we find that
the hybridization of zinc and oxygen orbitals can result in an impurity state
with the energy \varepsilon, which is lower than the effective Hubbard gap U.
The low-energy, spin-only Hamiltonian includes terms of the order t^2/U and
t^4/\varepsilon^3. That is, besides the usual nearest-neighbor superexchange
J-terms of order t^2/U, the low-energy model contains impurity-mediated,
further-neighbor frustrating interactions among the Cu spins surrounding
Zn-sites in an otherwise unfrustrated antiferromagnetic background. These terms
can be substantial when \varepsilon ~ U/2, the latter value corresponding to
the realistic CuO2 parameters. In order to verify this spin-only model, we
subsequently apply the T-matrix approach to study the effect of impurities on
the antiferromagnetic order parameter. Previous theoretical studies, which
include only the dilution effect of impurities, show a large discrepancy with
experimental data in the doping dependence of the staggered magnetization at
low doping. We demonstrate that this discrepancy is eliminated by including
impurity-induced frustrations into the effective spin model with realistic CuO2
parameters. Recent experimental study shows a significantly stronger
suppression of spin stiffness in the case of Zn-doped La2CuO4 compared to the
Mg-doped case and thus gives a strong support to our theory. We argue that the
proposed impurity-induced frustrations should be important in other strongly
correlated oxides and charge-transfer insulators.
|
Trialitarian triples are triples of central simple algebras of degree 8 with
orthogonal involution that provide a convenient structure for the
representation of trialitarian algebraic groups as automorphism groups. This
paper explicitly describes the canonical "trialitarian'' isomorphisms between
the spin groups of the algebras with involution involved in a trialitarian
triple, using a rationally defined shift operator that cyclically permutes the
algebras. The construction relies on compositions of quadratic spaces of
dimension 8, which yield all the trialitarian triples of split algebras. No
restriction on the characteristic of the base field is needed.
|
We propose a scheme to manipulate quantum correlation of output lights from
two sides of a cavity by phase control. A probe laser is set to split into two
beams in an interferometer with a relative phase in two arms which drive the
cavity mode in opposite directions along cavity axis, individually. This phase,
here named as driving-field phase, is important to build up quantum correlation
in HBT (Hanbury Brown-Twiss) setup. Three control lasers propagate vertically
to the cavity axis and drive the corresponding atomic transitions with a
closed-loop phase. This type of closed-loop phase has been utilized to realize
quantum correlation and even quantum entanglement of the atomic system in
previous work [Phys. Rev. A 81 033836 (2010)]. The scheme here is useful to
manipulate steady and maximum quantum correlation.
|
When a diatomic molecule is ionized by an intense laser field, the ionization
rate depends very strongly on the inter-nuclear separation. That dependence
exhibits a pronounced maximum at the inter-nuclear separation known as the
critical distance. This phenomenon was first demonstrated theoretically in H2+
and became known as charge-resonance enhanced ionization (CREI, in reference to
a proposed physical mechanism) or simply enhanced ionisation (EI). All
theoretical models of this phenomenon predict a double-peak structure in the
R-dependent ionization rate of H2+. However, such double-peak structure has
never been observed experimentally. It was even suggested that it is impossible
to observe due to fast motion of the nuclear wavepackets. Here we report a
few-cycle pump-probe experiment which clearly resolves that elusive double-peak
structure. In the experiment, an expanding H2+ ion produced by an intense pump
pulse is probed by a much weaker probe pulse. The predicted double-peak
structure is clearly seen in delay-dependent kinetic energy spectra of protons
when pump and probe pulses are polarized parallel to each other. No structure
is seen when the probe is polarized perpendicular to the pump.
|
In this paper we present a novel particle method for the Vlasov--Poisson
equation. Unlike in conventional particle methods, the particles are not
interpreted as point charges, but as point values of the distribution function.
In between the particles, the distribution function is reconstructed using
mesh-free interpolation. Our numerical experiments confirm that this approach
results in significantly increased accuracy and noise reduction. At the same
time, many benefits of the conventional schemes are preserved.
|
Observations of the polarization of the cosmic microwave backround (CMB) have
the potential to place much tighter constraints on cosmological parameters than
observations of the fluctuations in temperature alone. We discuss using CMB
polarization to constrain parameters relevant for distinguishing among popular
models for cosmological inflation, using the MAP and Planck satellite missions
as example cases. Of particular interest is the ability to detect tiny
contributions to the CMB anisotropy from tensor modes, which is fundamentally
limited by cosmic variance in temperature-only observations. The ability to
detect a tensor/scalar ratio $r \sim 0.01$ would allow precision tests of
interesting inflation models, and is possible with a modest increase in
sensitivity over that planned for the Planck satellite, or potentially by
ground-based experiments.
|
Despite the recent success of deep learning in continuous sign language
recognition (CSLR), deep models typically focus on the most discriminative
features, ignoring other potentially non-trivial and informative contents. Such
characteristic heavily constrains their capability to learn implicit visual
grammars behind the collaboration of different visual cues (i,e., hand shape,
facial expression and body posture). By injecting multi-cue learning into
neural network design, we propose a spatial-temporal multi-cue (STMC) network
to solve the vision-based sequence learning problem. Our STMC network consists
of a spatial multi-cue (SMC) module and a temporal multi-cue (TMC) module. The
SMC module is dedicated to spatial representation and explicitly decomposes
visual features of different cues with the aid of a self-contained pose
estimation branch. The TMC module models temporal correlations along two
parallel paths, i.e., intra-cue and inter-cue, which aims to preserve the
uniqueness and explore the collaboration of multiple cues. Finally, we design a
joint optimization strategy to achieve the end-to-end sequence learning of the
STMC network. To validate the effectiveness, we perform experiments on three
large-scale CSLR benchmarks: PHOENIX-2014, CSL and PHOENIX-2014-T. Experimental
results demonstrate that the proposed method achieves new state-of-the-art
performance on all three benchmarks.
|
We formulate and prove a local arithmetic Siegel--Weil formula for GSpin
Rapoport--Zink spaces, which is a precise identity between the arithmetic
intersection numbers of special cycles on GSpin Rapoport--Zink spaces and the
derivatives of local representation densities of quadratic forms. As a first
application, we prove a semi-global arithmetic Siegel--Weil formula as
conjectured by Kudla, which relates the arithmetic intersection numbers of
special cycles on GSpin Shimura varieties at a place of good reduction and the
central derivatives of nonsingular Fourier coefficients of incoherent Siegel
Eisenstein series.
|
The anomalous decay rate of the quasinormal modes occurs when the
longest-lived modes are the ones with higher angular number. Such behaviour has
been recently studied in different static spacetimes, for uncharged scalar and
fermionic perturbations, being observed in both cases. In this work we consider
the propagation of charged massive scalar fields in the background of
Reissner-Nordstr\"om-de Sitter black holes and we mainly study the effect of
the scalar field charge in the spectrum of quasinormal frequencies, as well as,
its effect on the anomalous decay rate. Mainly, we show that the anomalous
behaviour is present for massive charged scalar fields as well, and a critical
value of scalar field mass exists, beyond which the behaviour is inverted.
However, there is also a critical value of the parameter $qQ$ of the charge of
the scalar field and of the charge of the black hole, which increases when the
cosmological constant increases, and beyond the critical value the anomalous
behaviour of the decay rate could be avoided for the fundamental mode.
|
Algorithmic education theory examines, among other things, the trade-off
between reviewing old material and studying new material: time spent learning
the new comes at the expense of reviewing and solidifying one's understanding
of the old. This trade-off is captured in the `Slow Flashcard System' (SFS) --
a system that has been studied not only for its applications in educational
software but also for its critical properties; it is a simple discrete
deterministic system capable of remarkable complexity, with standing
conjectures regarding its longterm behavior. Here we introduce a probabilistic
model of SFS and further derive a continuous time, continuous space PDE model.
These two models of SFS shed light on the longterm behavior of SFS and open new
avenues of research.
|
We compute bordered Floer homology CFDD of (2,2n)-torus link complement, and
discuss assorted examples and type-DD structure homotopy equivalence.
|
Multilingual machine translation (MMT), trained on a mixture of parallel and
monolingual data, is key for improving translation in low-resource language
pairs. However, the literature offers conflicting results on the performance of
different methods of including monolingual data. To resolve this, we examine
how denoising autoencoding (DAE) and backtranslation (BT) impact MMT under
different data conditions and model scales. Unlike prior studies, we use a
realistic dataset of 100 translation directions and consider many domain
combinations of monolingual and test data. We find that monolingual data
generally helps MMT, but models are surprisingly brittle to domain mismatches,
especially at smaller model scales. BT is beneficial when the parallel,
monolingual, and test data sources are similar but can be detrimental
otherwise, while DAE is less effective than previously reported. Next, we
analyze the impact of scale (from 90M to 1.6B parameters) and find it is
important for both methods, particularly DAE. As scale increases, DAE
transitions from underperforming the parallel-only baseline at 90M to
converging with BT performance at 1.6B, and even surpassing it in low-resource.
These results offer new insights into how to best use monolingual data in MMT.
|
Given a pair of translation surfaces it is very difficult to determine
whether they are supported on the same algebraic curve. In fact, there are very
few examples of such pairs. In this note we present infinitely many examples of
finite collections of translation surfaces supported on the same algebraic
curve.
The underlying curves are hyperelliptic curves with many automorphisms. For
each curve, the automorphism of maximal order acts on the space of holomorphic
1-forms. We present a translation surface corresponding to each of the
eigenforms of this action.
|
We consider model order reduction based on proper orthogonal decomposition
(POD) for unsteady incompressible Navier-Stokes problems, assuming that the
snapshots are given by spatially adapted finite element solutions. We propose
two approaches of deriving stable POD-Galerkin reduced-order models for this
context. In the first approach, the pressure term and the continuity equation
are eliminated by imposing a weak incompressibility constraint with respect to
a pressure reference space. In the second approach, we derive an inf-sup stable
velocity-pressure reduced-order model by enriching the velocity reduced space
with supremizers computed on a velocity reference space. For problems with
inhomogeneous Dirichlet conditions, we show how suitable lifting functions can
be obtained from standard adaptive finite element computations. We provide a
numerical comparison of the considered methods for a regularized lid-driven
cavity problem.
|
This paper explores the potential of a hybrid modeling approach that combines
machine learning (ML) with conventional physics-based modeling for weather
prediction beyond the medium range. It extends the work of Arcomano et al.
(2022), which tested the approach for short- and medium-range weather
prediction, and the work of Arcomano et al. (2023), which investigated its
potential for climate modeling. The hybrid model used for the forecast
experiments of the paper is based on the low-resolution, simplified
parameterization atmospheric general circulation model (AGCM) SPEEDY. In
addition to the hybridized prognostic variables of SPEEDY, the current version
of the model has three purely ML-based prognostic variables. One of these is
6~h cumulative precipitation, another is the sea surface temperature, while the
third is the heat content of the top 300 m deep layer of the ocean. The model
has skill in predicting the El Ni\~no cycle and its global teleconnections with
precipitation for 3-7 months depending on the season. The model captures
equatorial variability of the precipitation associated with Kelvin and Rossby
waves and MJO. Predictions of the precipitation in the equatorial region have
skill for 15 days in the East Pacific and 11.5 days in the West Pacific. Though
the model has low spatial resolution, for these tasks it has prediction skill
comparable to what has been published for high-resolution, purely
physics-based, conventional operational forecast models.
|
This paper is devoted mainly to mathematical aspects of modeling and
simulation of tunnel relaxation of nonequilibrium charged oxide traps located
at/near the interface insulator - conductive channel, for instance in
irradiated MOS devices. The generic form of the tunnel annealing response
function was derived from the rate equation for the charged defect buildup and
annealing as a linear superposition of the responses of different defects with
different time constants. Using this linear response function, a number of
important practical problems are analyzed and discussed. Combined tunnel and
thermal or RICN annealing, power-like temporal relaxation after a single ion
strike into the gate oxide, are described in context of general approach.
|
Polarization profiles are presented for 20 millisecond pulsars that are being
observed as part of the Parkes Pulsar Timing Array project. The observations
used the Parkes multibeam receiver with a central frequency of 1369 MHz and the
Parkes digital filterbank pulsar signal-processing system PDFB2. Because of the
large total observing time, the summed polarization profiles have very high
signal/noise ratios and show many previously undetected profile features.
Thirteen of the 20 pulsars show emission over more than half of the pulse
period. Polarization variations across the profiles are complex and the
observed position angle variations are generally not in accord with the
rotating-vector model for pulsar polarization. Never-the-less, the polarization
properties are broadly similar to those of normal (non-millisecond) pulsars,
suggesting that the basic radio emission mechanism is the same in both classes
of pulsar. The results support the idea that radio emission from millisecond
pulsars originates high in the pulsar magnetosphere, probably close to the
emission regions for high-energy X-ray and gamma-ray emission. Rotation
measures were obtained for all 20 pulsars, eight of which had no previously
published measurements.
|
In this paper we prove generic results concerning Hardy spaces in one or
several complex variables. More precisely, we show that the generic function in
certain Hardy type spaces is totally unbounded and hence non-extentable,
despite the fact that these functions have non tangential limits at the
boundary of the domain. We also consider local Hardy spaces and show that
generically these functions do not belong, not even locally, to Hardy spaces of
higher order. We work first in the case of the unit ball of Cn where the
calculations are easier and the results are somehow better, and then we extend
them to the case of strictly pseudoconvex domains.
|
The use of Printed Circuit Boards (PCBs) for the inductive pick-up windings
of rotating coil probes has made the construction of these precision magnetic
measurement devices much more accessible. This paper discusses the design
details for PCBs which on each layer of the board provide for simultaneous
analog bucking (suppression) of dipole, quadrupole, and sextupole field
components so as to more accurately measure the higher order harmonic fields in
sextupole magnets. Techniques to generate designs are discussed, as well as
trade-offs to optimize sensitivity. Examples of recent sextupole PCBs and their
performance are given.
|
We study $p$-localizations, where $p$ is an odd prime, of the full
subcategories $S^n$ of stable homotopy category consisting of CW-complexes
having cells in $n$ successive dimensions. Using the technique of triangulated
categories and matrix problems we classify atoms (indecomposable objects) in
$S_p^n$ for $n\le 4(p-1)$ and show that for $n>4(p-1)$ such classification is
wild in the sense of the representation theory.
|
We develop the theory of optical beam shifts (both Goos-Hanchen and
Imbert-Fedorov) for the case of near-normal incidence, when the incident angle
becomes comparable with the angular beam divergence. Such a situation naturally
leads to strong enhancement of the shifts reported recently [ACS Photonics 6,
2530 (2019)]. Experimental results find complete and rigorous explanation in
our generalized theory. In addition, the developed theory uncovers the unified
origin of the anomalous beam shifts enhancement via the Berry phase
singularity. We also propose a simple experimental scheme involving
quarter-wave plate that allows to observe the giant transverse and
longitudinal, spatial and angular beam shifts simultaneously. Our results can
find applications in spin-orbit photonics, polarization optics, sensing
applications, and quantum weak measurements.
|
We present a novel method for the reconstruction of events containing pairs
of hadronically decaying tau leptons at collider experiments. This method
relies on accurate knowledge of the tau production vertex and precise
measurement of its charged decay products. The method makes no assumptions
about the centre-of-mass or invariant mass of the tau pair, and is insensitive
to momentum loss along the beam direction. We demonstrate the method using e+e-
-> mu+ mu- tau+ tau- events fully simulated in the ILD detector.
|
Conversation is the natural mode for information exchange in daily life, a
spoken conversational interaction for search input and output is a logical
format for information seeking. However, the conceptualisation of user-system
interactions or information exchange in spoken conversational search (SCS) has
not been explored. The first step in conceptualising SCS is to understand the
conversational moves used in an audio-only communication channel for search.
This paper explores conversational actions for the task of search. We define a
qualitative methodology for creating conversational datasets, propose analysis
protocols, and develop the SCSdata. Furthermore, we use the SCSdata to create
the first annotation schema for SCS: the SCoSAS, enabling us to investigate
interactivity in SCS. We further establish that SCS needs to incorporate
interactivity and pro-activity to overcome the complexity that the information
seeking process in an audio-only channel poses. In summary, this exploratory
study unpacks the breadth of SCS. Our results highlight the need for
integrating discourse in future SCS models and contributes the advancement in
the formalisation of SCS models and the design of SCS systems.
|
We study $B\to \phi K$ and $B\to \phi X_s$ decays in the heavy quark limit
using perturbative QCD. The next leading order corrections introduce
substantial modifications to the naive factorization results (more than 50%).
The branching ratio $Br(B\to \phi K)$ is predicted to be in the range $(F^{B\to
K}_1(m^2_\phi)/0.33)^2(3.5\sim 4.2) \times 10^{-6}$ which is within the one
$\sigma$ allowed region from the central value of $6.2\times 10^{-6}$ measured
by CLEO, but outside the one $\sigma$ allowed region from the central value of
$17.2\times 10^{-6}$ measured by BELLE for reasonable $F_1^{B\to K}$. For the
semi-inclusive decay $B\to \phi X_s$ we also include initial bound state effect
in the heavy quark limit which decreases the branching ratio by about 10%.
$Br(B\to \phi X_s)$ is predicted to be in the range $(5.1\sim 6.3)\times
10^{-5}$.
|
In this article we develop some aspects of the construction of new Hopf
algebras found recently by Andruskiewitsch and Schneider. There the authors
classified (under some slight restrictions) all pointed finite dimensional Hopf
algebras with coradical (Z/p)^s. We contribute to this work by giving a closer
description of the possible ``exotic'' linkings.
|
In this paper, we show that if $m$ and $n$ are distinct positive integers and
$x$ is a nonzero real number with $\Phi_m(x)=\Phi_n(x)$, then
$\frac{1}{2}<|x|<2$ except when $\{m,n\}=\{2,6\}$ and $x=2$. We also observe
that 2 appears to be the largest limit point of the set of values of $x$ for
which $\Phi_m(x)=\Phi_n(x)$ for some $m\neq n$.
|
We report on the discovery and investigation of a new 218 heavy fermion
compound. Crystals have been synthesized from In-flux. Structurally, Ce2PtIn8
is located between the cubic CeIn3 and the more two-dimensional CeTIn5 (T =
transition metal) type of compounds. The weak anisotropy of the paramagnetic
susceptibility suggests rather 3D magnetic correlations. Specific heat,
electrical resistivity and magnetization measurements revealed that Ce2PtIn8
orders antiferromagnetically below Tn = 2.1 K. An order-to-order transition is
observed at Tm = 2 K. Similarities in the H - T phase diagram to other
CenTmIn3n+2m (T = Rh, Pt) compounds point to a pressure-induced quantum phase
transition (QPT) which, according to the tentative location of Ce2PtIn8 in the
recent proposed global phase diagram for QPT, would be of spin density wave
type.
|
Tremendous progress in deep learning over the last years has led towards a
future with autonomous vehicles on our roads. Nevertheless, the performance of
their perception systems is strongly dependent on the quality of the utilized
training data. As these usually only cover a fraction of all object classes an
autonomous driving system will face, such systems struggle with handling the
unexpected. In order to safely operate on public roads, the identification of
objects from unknown classes remains a crucial task. In this paper, we propose
a novel pipeline to detect unknown objects. Instead of focusing on a single
sensor modality, we make use of lidar and camera data by combining state-of-the
art detection models in a sequential manner. We evaluate our approach on the
Waymo Open Perception Dataset and point out current research gaps in anomaly
detection.
|
Subsets and Splits