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|---|---|---|---|---|
0906.1929
|
QCD against black holes?
|
Along with compacting baryon (neutron) spacing, two very important factors come into play at once: the lack of self-stabilization within a compact neutron star (NS) associated with possible black hole (BH) horizon appearance and the phase transition - color deconfinement and QCD-vacuum reconstruction - within the nuclear matter. That is why both phenomena should be taken into account side by side, as the gravitational collapse is considered. Since, under the above transition, the hadronic-phase vacuum (filled up with gluon and chiral $q\bar q$-condensates) turns into the "empty" (perturbation) subhadronic-phase one and, thus, the corresponding (very high) pressure falls down rather abruptly, the formerly cold (degenerated) nuclear medium starts to implode into the new vacuum. If the mass of a star is sufficiently large, then this implosion produces an enormous heating, which stops only after quark-gluon plasma of a temperature about 100 MeV (or even higher) is formed to withstand the gravitational compression (whereas the highest temperatures of supernovae bursts are, at least, one order lower). As a consequence, a "burning wall" must be, most probably, erected on the way of further collapsing the matter towards a black hole formation.
|
[
"Physics Archive->astro-ph->astro-ph.HE",
"Physics Archive->hep->hep-ph"
] | 2009-06-10T13:10:44Z |
gr-qc/0101006
|
A rigidity theorem for nonvacuum initial data
|
In this note we prove a theorem on non-vacuum initial data for general relativity. The result presents a ``rigidity phenomenon'' for the extrinsic curvature, caused by the non-positive scalar curvature. More precisely, we state that in the case of asymptotically flat non-vacuum initial data if the metric has everywhere non-positive scalar curvature then the extrinsic curvature cannot be compactly supported.
|
[
"Physics Archive->gr-qc"
] | 2000-12-31T07:39:23Z |
cond-mat/9309012
|
Persistent Currents in Mesoscopic Hubbard Rings with Spin-Orbit Interaction
|
The effect of spin-orbit interaction on persistent currents in mesoscopic Hubbard rings threaded by an Aharonov-Bohm flux is investigated putting stress on the orbital magnetism. The non-perturbative treatment of the spin-orbit interaction developed by Meir {\em et al.} is combined with the Bethe ansatz solution to deal with this problem exactly. We find that the interplay of spin-orbit interaction and electron-electron interaction plays a crucial role, bringing about some new effects on the orbital magnetism.
|
[
"Physics Archive->cond-mat"
] | 1993-09-13T11:18:28Z |
2109.01490
|
A Scalable Track-Before-Detect Method With Poisson/Multi-Bernoulli Model
|
We propose a scalable track-before-detect (TBD) tracking method based on a Poisson/multi-Bernoulli model. To limit computational complexity, we approximate the exact multi-Bernoulli mixture posterior probability density function (pdf) by a multi-Bernoulli pdf. Data association based on the sum-product algorithm and recycling of Bernoulli components enable the detection and tracking of low-observable objects with limited computational resources. Our simulation results demonstrate a significantly improved tracking performance compared to a state-of-the-art TBD method.
|
[
"Electrical Engineering and Systems Science Archive->eess.SP"
] | 2021-09-03T13:06:46Z |
2312.03230
|
Experimental Investigation of the Structural Performance of Composite Structures Produced using Additive Manufacturing
|
This project is focused on investigating the structural performance of parts and structures produced using the latest additive manufacturing techniques. For additive manufacturing of test coupons, fused deposition modeling of fiber-reinforced polymer (RFP) and high-resolution low-force stereolithography (LFS) thermoset resin printing systems were employed. UV thermoset resin was used for LFS printing, while RFP printing adopted two different types of filaments: amorphous polycarbonate carbon fiber filaments and semi-crystalline Nylon 12 glass fiber filaments. For the experimental work, specimens were printed for tension, compression, and shear tests. Additionally, mode-II interlminar fracture in these specimens was explored. The elastic modulus and strength values of these specimens were compared with the data of oven-cured T700G/2510 composites. The experimental work herein will be extended to develop damage models for 3D-printed structural parts and structures for aerospace and space applications.
|
[
"Physics Archive->physics->physics.app-ph"
] | 2023-12-06T01:56:44Z |
1304.2473
|
Smooth Transonic Flows in De Laval Nozzles
|
This paper concerns smooth transonic flows of Meyer type in finite de Laval nozzles, which are governed by an equation of mixed type with degeneracy and singularity at the sonic state. First we study the properties of sonic curves. For any $C^2$ transonic flow of Meyer type, the set of exceptional points is shown to be a closed line segment (may be empty or only one point). Furthermore, it is proved that a flow with nonexceptional points is unstable for a $C^1$ small perturbation in the shape of the nozzle. Then we seek smooth transonic flows of Meyer type which satisfy physical boundary conditions and whose sonic points are exceptional. For such a flow, its sonic curve must be located at the throat of the nozzle and it is strongly singular in the sense that the sonic curve is a characteristic degenerate boundary in the subsonic-sonic region, while in the sonic-supersonic region all characteristics from sonic points coincide, which are the sonic curve and never approach the supersonic region. It is proved that there exists uniquely such a smooth transonic flow near the throat of the nozzle, whose acceleration is Lipschitz continuous, if the wall of the nozzle is sufficiently flat.
|
[
"Mathematics Archive->math.AP"
] | 2013-04-09T07:20:07Z |
0909.2174
|
The exact spread of M12 is 9
|
Let G be a group. We say that G has spread r if for any set of distinct non-trivial elements {x1,...,xr}\subset G there exists an element y\in G with the property that <xi, y> = G for every 1 0<i<r+1. The group G has exact spread r if it has spread r but not r + 1. The case where G is a finite simple group is particularly interesting since it is known that in this case the spread is at least 2. The precise value of the exact spread of a simple group is known in very few cases. Here we determine the precise value of the exact spread in the smallest sporadic group for which this is still unknown, the Mathieu group M12.
|
[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.GR"
] | 2009-09-11T14:07:11Z |
2108.01321
|
Dynamics of Ginzburg-Landau vortices for vector fields on surfaces
|
In this paper we consider the gradient flow of the following Ginzburg-Landau type energy \[ F_\varepsilon(u) := \frac{1}{2}\int_{M}\vert D u\vert_g^2 +\frac{1}{2\varepsilon^2}\left(\vert u\vert_g^2-1\right)^2\mathrm{vol}_g. \] This energy is defined on tangent vector fields on a $2$-dimensional closed and oriented Riemannian manifold $M$ (here $D$ stands for the covariant derivative) and depends on a small parameter $\varepsilon>0$. If the energy satisfies proper bounds, when $\varepsilon\to 0$ the second term forces the vector fields to have unit length. However, due to the incompatibility for vector fields on $M$ between the Sobolev regularity and the unit norm constraint, critical points of $F_\varepsilon$ tend to generate a finite number of singular points (called vortices) having non-zero index (when the Euler characteristic is non-zero). These types of problems have been extensively analyzed in a recent paper by R. Ignat and R. Jerrard. As in Euclidean case, the position of the vortices is ruled by the so-called renormalized energy. In this paper we are interested in the dynamics of vortices. We rigorously prove that the vortices move according to the gradient flow of the renormalized energy, which is the limit behavior when $\varepsilon\to 0$ of the gradient flow of the Ginzburg-Landau energy.
|
[
"Mathematics Archive->math.AP"
] | 2021-08-03T06:40:52Z |
2311.08995
|
Simple but Effective Unsupervised Classification for Specified Domain Images: A Case Study on Fungi Images
|
High-quality labeled datasets are essential for deep learning. Traditional manual annotation methods are not only costly and inefficient but also pose challenges in specialized domains where expert knowledge is needed. Self-supervised methods, despite leveraging unlabeled data for feature extraction, still require hundreds or thousands of labeled instances to guide the model for effective specialized image classification. Current unsupervised learning methods offer automatic classification without prior annotation but often compromise on accuracy. As a result, efficiently procuring high-quality labeled datasets remains a pressing challenge for specialized domain images devoid of annotated data. Addressing this, an unsupervised classification method with three key ideas is introduced: 1) dual-step feature dimensionality reduction using a pre-trained model and manifold learning, 2) a voting mechanism from multiple clustering algorithms, and 3) post-hoc instead of prior manual annotation. This approach outperforms supervised methods in classification accuracy, as demonstrated with fungal image data, achieving 94.1% and 96.7% on public and private datasets respectively. The proposed unsupervised classification method reduces dependency on pre-annotated datasets, enabling a closed-loop for data classification. The simplicity and ease of use of this method will also bring convenience to researchers in various fields in building datasets, promoting AI applications for images in specialized domains.
|
[
"Computer Science Archive->cs.CV"
] | 2023-11-15T14:33:22Z |
1410.1135
|
Corpora Preparation and Stopword List Generation for Arabic data in Social Network
|
This paper proposes a methodology to prepare corpora in Arabic language from online social network (OSN) and review site for Sentiment Analysis (SA) task. The paper also proposes a methodology for generating a stopword list from the prepared corpora. The aim of the paper is to investigate the effect of removing stopwords on the SA task. The problem is that the stopwords lists generated before were on Modern Standard Arabic (MSA) which is not the common language used in OSN. We have generated a stopword list of Egyptian dialect and a corpus-based list to be used with the OSN corpora. We compare the efficiency of text classification when using the generated lists along with previously generated lists of MSA and combining the Egyptian dialect list with the MSA list. The text classification was performed using Na\"ive Bayes and Decision Tree classifiers and two feature selection approaches, unigrams and bigram. The experiments show that the general lists containing the Egyptian dialects words give better performance than using lists of MSA stopwords only.
|
[
"Computer Science Archive->cs.CL"
] | 2014-10-05T09:02:31Z |
1902.08641
|
Seeing beyond the light: Vison and photon electrodynamics in quantum spin ice
|
Understanding the nature and behaviour of excitations in quantum spin liquids, and in topological phases of matter in general, is of fundamental importance and has proven crucial for experimental detection and characterisation of candidate materials. Current theoretical and numerical techniques, however, have limited capabilities, especially when it comes to studying gapped excitations. Here, we propose a semiclassical numerical method to study systems whose spin liquid behaviour is underpinned by perturbative ring-exchange Hamiltonians. Our method can readily access both thermodynamic and spectral properties. We focus in particular on quantum spin ice and its photon and vison excitations. After benchmarking the method against existing results on photons, we use it to characterise visons and their thermodynamic behaviour, which remained hitherto largely unexplored. We find that visons, in contrast to spinons in classical spin ice, form a weak electrolyte: vison pairs are the dominant population at low temperatures. This is reflected in the behaviour of thermodynamic quantities, such as pinch point motifs in the relevant correlators. Visons also appear to strongly hybridise with the photon background, a phenomenon that affects the way these quasiparticles may show up in inelastic response measurements. Our results demonstrate that the method, and generalisations thereof, can substantially help our understanding of quasiparticles and their interplay in quantum spin ice and other quantum spin liquids, quantum dimer models, and lattice gauge theories in general.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech",
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2019-02-22T19:19:43Z |
2310.06807
|
Longitudinal gOSNR Monitoring by Receiver-side Digital Signal Processing in Multi-Span Optical Transmission System
|
We propose the world first longitudinal gOSNR estimation by using correlation template method at Rx, without any monitoring devices located in the middle of the link. The proposed method is experimentally demonstrated in a 12-span link with commercial transceiver.
|
[
"Electrical Engineering and Systems Science Archive->eess.SP"
] | 2023-10-10T17:26:14Z |
1905.07824
|
Detection of the Quantum Illumination Measurement
|
In this report, we discuss possibilities to detect a signal at the target from the quantum illumination protocol, that could serve as a quantum radar. We assume a simple universal detecting schema on the target and study if it is possible to discover the quantum illumination measurement and in what conditions considering the microwave regime. Assuming many simplifications, we found that the possibility or the advantage of the detection of the quantum illumination measurement strongly depends on the realization of the quantum illumination protocol.
|
[
"Physics Archive->quant-ph"
] | 2019-05-19T23:09:08Z |
2209.03446
|
Activity from matroids to rooted trees and beyond
|
The interior and exterior activities of bases of a matroid are well-known notions that for instance permit one to define the Tutte polynomial. Recently, we have discovered correspondences between the regions of gainic hyperplane arrangements and coloredlabeled rooted trees. Here we define a general activity theory that applies in particular to no-broken circuit (NBC) sets and labeled colored trees. The special case of activity \textsf{0} was our motivating case. As a consequence, in a gainic hyperplane arrangement the number of bounded regions is equal to the number of the corresponding colored labeled rooted trees of activity \textsf{0}.
|
[
"Mathematics Archive->math.CO"
] | 2022-09-07T20:10:08Z |
1808.09385
|
Unified formulation for helicity and continuous spin fermionic fields
|
We propose a unified BRST formulation of general massless fermionic fields of arbitrary mixed-symmetry type in $d$-dimensional Minkowski space. Depending on the value of the real parameter the system describes either helicity fields or continuous spin fields. Starting with the unified formulation we derive a number of equivalent descriptions including the triplet formulation, Fang-Fronsdal-Labastida formulation, light-cone formulation and discuss the unfolded formulation.
|
[
"Physics Archive->hep->hep-th"
] | 2018-08-28T16:18:57Z |
hep-th/0604103
|
Bosonic Massless Higher Spin Fields from Matrix Model
|
We study matrix models as a new approach to formulate massless higher spin gauge field theory. As a first step in this direction, we show that the free equation of motion of bosonic massless higher spin gauge fields can be derived from that of a matrix model.
|
[
"Physics Archive->hep->hep-th"
] | 2006-04-14T09:15:30Z |
2208.12030
|
Catastrophic Cooling in Superwinds. III. Non-equilibrium Photoionization
|
Observations of some starburst-driven galactic superwinds suggest that strong radiative cooling could play a key role in the nature of feedback and the formation of stars and molecular gas in star-forming galaxies. These catastrophically cooling superwinds are not adequately described by adiabatic fluid models, but they can be reproduced by incorporating non-equilibrium radiative cooling functions into the fluid model. In this work, we have employed the atomic and cooling module MAIHEM implemented in the framework of the FLASH hydrodynamics code to simulate the formation of radiatively cooling superwinds as well as their corresponding non-equilibrium ionization (NEI) states for various outflow parameters, gas metallicities, and ambient densities. We employ the photoionization program CLOUDY to predict radiation- and density-bounded photoionization for these radiatively cooling superwinds, and we predict UV and optical line emission. Our non-equilibrium photoionization models built with the NEI states demonstrate the enhancement of C IV, especially in metal-rich, catastrophically cooling outflows, and O VI in metal-poor ones.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2022-08-24T15:43:15Z |
gr-qc/9405016
|
Behavior of Friedmann-Robertson-Walker Cosmological Models in Scalar-Tensor Gravity
|
We analyze solutions to Friedmann-Robertson-Walker cosmologies in Brans-Dicke theory, where a scalar field is coupled to gravity. Matter is modelled by a $\gamma$-law perfect fluid, including false-vacuum energy as a special case. Through a change of variables, we reduce the field equations from fourth order to second order, and they become equivalent to a two-dimensional dynamical system. We then analyze the entire solution space of this dynamical system, and find that many qualitative features of these cosmologies can be gleaned, including standard non-inflationary or extended inflationary expansion, but also including bifurcations of stable or unstable expansion or contraction, noninflationary vacuum-energy dominated models, and several varieties of ``coasting," ``bouncing," ``hesitating," and ``vacillating" universes. It is shown that inflationary dogma, which states that a universe with curvature and dominated by inflationary matter will always approach a corresponding flat-space solution at late times, does not hold in general for the scalar-tensor theory, but rather that the occurence of inflation depends upon the initial energy of the scalar field relative to the expansion rate. In the case of flat space ($k=0$), the dynamical system formalism generates some previously known exact power-law solutions.
|
[
"Physics Archive->gr-qc"
] | 1994-05-07T06:12:39Z |
2011.01296
|
First-order Lagrangian and Hamiltonian of Lovelock gravity
|
Based on the insight gained by many authors over the years on the structure of the Einstein-Hilbert, Gauss-Bonnet and Lovelock gravity Lagrangians, we show how to derive -- in an elementary fashion -- their first-order, generalized "ADM" Lagrangian and associated Hamiltonian. To do so, we start from the Lovelock Lagrangian supplemented with the Myers boundary term, which guarantees a Dirichlet variational principle with a surface term of the form $\pi^{ij}\delta h_{ij}$, where $\pi^{ij}$ is the canonical momentum conjugate to the boundary metric $h_{ij}$. Then, the first-order Lagrangian density is obtained either by integration of $\pi^{ij}$ over the metric derivative $\partial_wh_{ij}$ normal to the boundary, or by rewriting the Myers term as a bulk term.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2020-11-02T20:28:20Z |
2310.00840
|
Error Norm Truncation: Robust Training in the Presence of Data Noise for Text Generation Models
|
Text generation models are notoriously vulnerable to errors in the training data. With the wide-spread availability of massive amounts of web-crawled data becoming more commonplace, how can we enhance the robustness of models trained on a massive amount of noisy web-crawled text? In our work, we propose Error Norm Truncation (ENT), a robust enhancement method to the standard training objective that truncates noisy data. Compared to methods that only uses the negative log-likelihood loss to estimate data quality, our method provides a more accurate estimation by considering the distribution of non-target tokens, which is often overlooked by previous work. Through comprehensive experiments across language modeling, machine translation, and text summarization, we show that equipping text generation models with ENT improves generation quality over standard training and previous soft and hard truncation methods. Furthermore, we show that our method improves the robustness of models against two of the most detrimental types of noise in machine translation, resulting in an increase of more than 2 BLEU points over the MLE baseline when up to 50% of noise is added to the data.
|
[
"Computer Science Archive->cs.CL"
] | 2023-10-02T01:30:27Z |
1107.1421
|
Penrose's circles in the CMB and a test of inflation
|
We present a calculation of the angular size of the circles in the CMB predicted by Penrose on the basis of his Conformal Cyclic Cosmology. If these circles are detected, the existence of an upper limit on their angular radius would provide a challenge for inflation.
|
[
"Physics Archive->gr-qc"
] | 2011-07-07T15:18:41Z |
hep-ph/0507264
|
Phase effects from the general neutrino Yukawa matrix on lepton flavor violation
|
We examine contributions from Majorana phases to lepton flavor violating processes in the framework of the minimal supersymmetric standard model with heavy right-handed neutrinos. All phases in the complex neutrino Yukawa matrix are taken into account in our study. We find that in the scenario with universal soft-breaking terms sizable phase effects can appear on the lepton flavor violating processes such as $\mu \to e \gamma$, $\tau \to e \gamma$, and $\tau \to \mu \gamma$. In particular, the branching ratio of $\mu \to e \gamma$ can be considerably enhanced due to the Majorana phases, so that it can be much greater than that of $\tau \to \mu \gamma$.
|
[
"Physics Archive->hep->hep-ph"
] | 2005-07-22T14:40:15Z |
1510.07854
|
Adiabatic excitation of a confined particle in one dimension with a variable infinitely sharp wall
|
It is shown that adiabatic cycles excite a quantum particle, which is confined in a one-dimensional region and is initially in an eigenstate. During the cycle, an infinitely sharp wall is applied and varied its strength and position. After the completion of the cycle, the state of the particle arrives another eigenstate. It is also shown that we may vary the final adiabatic state by choosing the parameters of the cycle. With a combination of these adiabatic cycles, we can connect an arbitrary pair of eigenstates. Hence, these cycles may be regarded as basis of the adiabatic excitations. A detailed argument is provided for the case that the particle is confined by an infinite square well. This is an example of exotic quantum holonomy in Hamiltonian systems.
|
[
"Physics Archive->quant-ph"
] | 2015-10-27T10:47:30Z |
2306.02688
|
Meta-SAGE: Scale Meta-Learning Scheduled Adaptation with Guided Exploration for Mitigating Scale Shift on Combinatorial Optimization
|
This paper proposes Meta-SAGE, a novel approach for improving the scalability of deep reinforcement learning models for combinatorial optimization (CO) tasks. Our method adapts pre-trained models to larger-scale problems in test time by suggesting two components: a scale meta-learner (SML) and scheduled adaptation with guided exploration (SAGE). First, SML transforms the context embedding for subsequent adaptation of SAGE based on scale information. Then, SAGE adjusts the model parameters dedicated to the context embedding for a specific instance. SAGE introduces locality bias, which encourages selecting nearby locations to determine the next location. The locality bias gradually decays as the model is adapted to the target instance. Results show that Meta-SAGE outperforms previous adaptation methods and significantly improves scalability in representative CO tasks. Our source code is available at https://github.com/kaist-silab/meta-sage
|
[
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2023-06-05T08:28:42Z |
physics/9902066
|
A Brief Summary of Electromagnetic Quantum Gravity
|
We briefly review the current status of a new quantum gravity theory called Electro-Magnetic Quantum Gravity. EMQG is manifestly compatible with Cellular Automata (CA) theory, and is based on a new theory of inertia proposed by R. Haisch, A. Rueda, and H. Puthoff. Newtonian Inertia is due to the strictly local, electrical force interactions of matter particles (consisting of real electrically charged fermions) with the surrounding, electrically charged, virtual fermion particles of the quantum vacuum. The force originates from each charged fermion particle of the mass undergoing relative acceleration with the the quantum vacuum particles. The sum of all these tiny electrical forces originating from each electrically charged particle in the mass is the source of the total inertial force of a mass, which is the force that opposes accelerated motion in Newton's famous inertia law 'F = MA'. Gravity also involves the same 'inertial' electrical force component that exists for inertial mass described above. The Weak Equivalence Principle turns out to be a physical phenomenon, originating from common 'lower level' quantum processes in both gravitational and inertial mass. The magnitude of the gravitational mass of a test mass on the earth results from the same quantity of electrical force interactions as in inertia, but on the earth it is the virtual fermions of the quantum vacuum that are actually accelerating downward (on a statistical average basis) with respect to the test mass.
|
[
"Physics Archive->physics->physics.gen-ph"
] | 1999-02-23T16:40:11Z |
2012.15668
|
Tensor Galileons as Lovelock theories
|
We review the construction of Galileon interactions involving a single two-column mixed-symmetry tensor of arbitrary degree in flat spacetime of arbitrary dimensions, in a reverse engineering spirit. By defining an appropriate Riemann-like tensor for each of these tensor gauge fields, we show that the theories constructed in the spirit of Lovelock's theory of Gravity correspond to the well-known Galileon theories from the literature.
|
[
"Physics Archive->hep->hep-th"
] | 2020-12-31T15:47:12Z |
hep-th/9307027
|
The WZNW Model at Two Loops
|
We study perturbatively the (conformal) WZNW model. At one loop we compute one-particle irreducible two- and three-point current correlation functions, both in the conventional version and in the classically equivalent, chiral, nonlocal, induced version of the model. At two loops we compute the two-point function and find that it vanishes (modulo infrared-induced logarithms). We use dimensional regularization and the $R^*$ operation for removing infrared divergences. The outcome of the calculations is insensitive to the treatment of the $\varepsilon^{\m\n}$ tensor as a two-dimensional or $d$-dimensional object. Our results indicate that the one-particle irreducible current correlation functions constitute an effective action equal to the original WZNW action with the familiar level shift, $k\to k+\tilde h$.
|
[
"Physics Archive->hep->hep-th"
] | 1993-07-05T14:40:00Z |
1405.4822
|
Wiener's theorem for positive definite functions on hypergroups
|
The following theorem on the circle group $\mathbb{T}$ is due to Norbert Wiener: If $f\in L^{1}\left( \mathbb{T}\right) $ has non-negative Fourier coefficients and is square integrable on a neighbourhood of the identity, then $f\in L^{2}\left( \mathbb{T}\right) $. This result has been extended to even exponents including $p=\infty$, but shown to fail for all other $p\in\left( 1,\infty\right] .$ All of this was extended further (appropriately formulated) well beyond locally compact abelian groups. In this paper we prove Wiener's theorem for even exponents for a large class of commutative hypergroups. In addition, we present examples of commutative hypergroups for which, in sharp contrast to the group case, Wiener's theorem holds for all exponents $p\in\left[ 1,\infty\right] $. For these hypergroups and the Bessel-Kingman hypergroup with parameter $\frac{1}{2}$ we characterise those locally integrable functions that are of positive type and square-integrable near the identity in terms of amalgam spaces.
|
[
"Mathematics Archive->math.FA"
] | 2014-05-19T18:03:55Z |
2305.19634
|
Is the background evolution of $\Lambda$CDM model consistent with observations?
|
We establish a new and cosmological-model-independent method to explore the cosmic background dynamics in this work. Utilizing the latest Pantheon+ type Ia supernova sample and the Hubble parameter measurements, we obtain the values of the Hubble parameter and the deceleration parameter at five different redshift points ranging from 0.2 to 0.6, and find that they can deviate from the predictions of the $\Lambda$CDM model at more than $2\sigma$. We further probe the equation of state of dark energy and obtain that a slightly oscillating equation of state of dark energy around the $-1$ line is favored.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->gr-qc"
] | 2023-05-31T08:07:26Z |
1701.08257
|
Detection of Face using Viola Jones and Recognition using Back Propagation Neural Network
|
Detection and recognition of the facial images of people is an intricate problem which has garnered much attention during recent years due to its ever increasing applications in numerous fields. It continues to pose a challenge in finding a robust solution to it. Its scope extends to catering the security, commercial and law enforcement applications. Research for moreover a decade on this subject has brought about remarkable development with the modus operandi like human computer interaction, biometric analysis and content based coding of images, videos and surveillance. A trivial task for brain but cumbersome to be imitated artificially. The commonalities in faces does pose a problem on various grounds but features such as skin color, gender differentiate a person from the other. In this paper the facial detection has been carried out using Viola-Jones algorithm and recognition of face has been done using Back Propagation Neural Network (BPNN).
|
[
"Computer Science Archive->cs.CV"
] | 2017-01-28T05:51:44Z |
1008.0878
|
Options for Control of Reactive Power by Distributed Photovoltaic Generators
|
High penetration levels of distributed photovoltaic(PV) generation on an electrical distribution circuit present several challenges and opportunities for distribution utilities. Rapidly varying irradiance conditions may cause voltage sags and swells that cannot be compensated by slowly responding utility equipment resulting in a degradation of power quality. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We discuss and compare via simulation various design options for control systems to manage the reactive power generated by these inverters. An important design decision that weighs on the speed and quality of communication required is whether the control should be centralized or distributed (i.e. local). In general, we find that local control schemes are capable for maintaining voltage within acceptable bounds. We consider the benefits of choosing different local variables on which to control and how the control system can be continuously tuned between robust voltage control, suitable for daytime operation when circuit conditions can change rapidly, and loss minimization better suited for nighttime operation.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2010-08-04T21:19:02Z |
1806.08794
|
Optical and Infrared Photometry of the Nearby SN 2017cbv
|
On 2017 March 11, the DLT40 Transient Discovery Survey discovered SN 2017cbv in NGC5643, a Type 2 Seyfert Galaxy in the Lupus Constellation. SN 2017cbv went on to become a bright Type Ia supernova, with a $V_{max}$ of 11.51 $\pm$ 0.05 mag. We present early time optical and infrared photometry of SN 2017cbv covering the rise and fall of over 68 days. We find that SN 2017cbv has a broad light curve $\Delta m_{15}(B)$ = 0.88 $\pm$ 0.07, a $B$-band maximum at 2457840.97 $\pm$ 0.43, a negligible host galaxy reddening where $E(B-V)_{host}$ $\approx$ 0, and a distance modulus of 30.49 $\pm$ 0.32 to the SN, corresponding to a distance of $12.58_{-1.71}^{+1.98}$ Mpc. We also present the results of two different numerical models we used for analysis in this paper: SALT2, an empirical model for Type Ia supernova optical light curves that accounts for variability components; and SNooPy, the CSP-II light-curve model that covers both optical and near-infrared wavelengths and is used for distance estimates.
|
[
"Physics Archive->astro-ph->astro-ph.HE",
"Physics Archive->astro-ph->astro-ph.SR"
] | 2018-06-22T18:00:00Z |
1510.03027
|
Group-blind detection with very large antenna arrays in the presence of pilot contamination
|
Massive MIMO is, in general, severely affected by pilot contamination. As opposed to traditional detectors, we propose a group-blind detector that takes into account the presence of pilot contamination. While sticking to the traditional structure of the training phase, where orthogonal pilot sequences are reused, we use the excess antennas at each base station to partially remove interference during the uplink data transmission phase. We analytically derive the asymptotic SINR achievable with group-blind detection, and confirm our findings by simulations. We show, in particular, that in an interference-limited scenario with one dominant interfering cell, the SINR can be doubled compared to non-group-blind detection.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2015-10-11T09:31:32Z |
0709.3795
|
Effects of decoherence on the radiative and squeezing properties in a coherently driven trapped two-level atom
|
Analysis of the effects of decoherence on the radiative and squeezing properties of a coherently driven two-level atom trapped in a resonant cavity applying the corresponding master equation is presented. The atomic dynamics as well as the squeezing and statistical properties of the emitted radiation are investigated. It is found that the atom stays in the lower energy level more often at steady state irrespective of the strength of the coherent radiation and thermal fluctuations entering the cavity. Moreover, a strong external coherent radiation results the splitting of the line of the emission spectrum, whereas the decoherence broadens the width and significantly decreases the height. It is also found that the emitted radiation exhibits photon anti-bunching, super-Poissonian photon statistics and squeezing, despite the presence of the decoherence which is expected to destroy the quantum features.
|
[
"Physics Archive->quant-ph"
] | 2007-09-24T15:44:08Z |
nucl-th/0309020
|
Some new perspectives on pairing in nuclei
|
Following a brief reminder of how the pairing model can be solved exactly, we describe how this can be used to address two interesting issues in nuclear structure physics. One concerns the mechanism for realizing superconductivity in finite nuclei and the other concerns the role of the nucleon Pauli principle in producing $sd$ dominance in interacting boson models of nuclei.
|
[
"Physics Archive->nucl->nucl-th"
] | 2003-09-10T07:03:19Z |
1712.09042
|
Search for PeVatrons at the Galactic Center using a radio air-shower array at the South Pole
|
The South Pole, which hosts the IceCube Neutrino Observatory, has a complete and around-the-clock exposure to the Galactic Center. Hence, it is an ideal location to search for gamma rays of PeV energy coming from the Galactic Center. However, it is hard to detect air showers initiated by these gamma rays using cosmic-ray particle detectors due to the low elevation of the Galactic Center. The use of antennas to measure the radio footprint of these air showers will help in this case, and would allow for a 24/7 operation time. So far, only air showers with energies well above 10 PeV have been detected with the radio technique. Thus, the energy threshold has to be lowered for the detection of gamma-ray showers of PeV energy. This can be achieved by optimizing the frequency band in order to obtain a higher level of signal-to-noise ratio. With such an approach, PeV gamma-ray showers with high inclination can be measured at the South Pole.
|
[
"Physics Archive->astro-ph->astro-ph.HE",
"Physics Archive->astro-ph->astro-ph.IM"
] | 2017-12-25T08:41:57Z |
1911.11973
|
A Most Irrational Foraging Algorithm
|
We present a foraging algorithm, GoldenFA, in which search direction is chosen based on the Golden Ratio. We show both theoretically and empirically that GoldenFA is more efficient for a single searcher than a comparable algorithm where search direction is chosen uniformly at random. Moreover, we give a variant of our algorithm that parallelizes linearly with the number of searchers.
|
[
"Computer Science Archive->cs.DC"
] | 2019-11-27T06:14:06Z |
quant-ph/0608085
|
Quantum universality by state distillation
|
Quantum universality can be achieved using classically controlled stabilizer operations and repeated preparation of certain ancilla states. Which ancilla states suffice for universality? This "magic states distillation" question is closely related to quantum fault tolerance. Lower bounds on the noise tolerable on the ancilla help give lower bounds on the tolerable noise rate threshold for fault-tolerant computation. Upper bounds show the limits of threshold upper-bound arguments based on the Gottesman-Knill theorem. We extend the range of single-qubit mixed states that are known to give universality, by using a simple parity-checking operation. For applications to proving threshold lower bounds, certain practical stability characteristics are often required, and we also show a stable distillation procedure. No distillation upper bounds are known beyond those given by the Gottesman-Knill theorem. One might ask whether distillation upper bounds reduce to upper bounds for single-qubit ancilla states. For multi-qubit pure states and previously considered two-qubit ancilla states, the answer is yes. However, we exhibit two-qubit mixed states that are not mixtures of stabilizer states, but for which every postselected stabilizer reduction from two qubits to one outputs a mixture of stabilizer states. Distilling such states would require true multi-qubit state distillation methods.
|
[
"Physics Archive->quant-ph"
] | 2006-08-09T22:48:34Z |
2306.08460
|
Improving Generalization in Meta-Learning via Meta-Gradient Augmentation
|
Meta-learning methods typically follow a two-loop framework, where each loop potentially suffers from notorious overfitting, hindering rapid adaptation and generalization to new tasks. Existing schemes solve it by enhancing the mutual-exclusivity or diversity of training samples, but these data manipulation strategies are data-dependent and insufficiently flexible. This work alleviates overfitting in meta-learning from the perspective of gradient regularization and proposes a data-independent \textbf{M}eta-\textbf{G}radient \textbf{Aug}mentation (\textbf{MGAug}) method. The key idea is to first break the rote memories by network pruning to address memorization overfitting in the inner loop, and then the gradients of pruned sub-networks naturally form the high-quality augmentation of the meta-gradient to alleviate learner overfitting in the outer loop. Specifically, we explore three pruning strategies, including \textit{random width pruning}, \textit{random parameter pruning}, and a newly proposed \textit{catfish pruning} that measures a Meta-Memorization Carrying Amount (MMCA) score for each parameter and prunes high-score ones to break rote memories as much as possible. The proposed MGAug is theoretically guaranteed by the generalization bound from the PAC-Bayes framework. In addition, we extend a lightweight version, called MGAug-MaxUp, as a trade-off between performance gains and resource overhead. Extensive experiments on multiple few-shot learning benchmarks validate MGAug's effectiveness and significant improvement over various meta-baselines. The code is publicly available at \url{https://github.com/xxLifeLover/Meta-Gradient-Augmentation}.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LG"
] | 2023-06-14T12:04:28Z |
2101.10385
|
Online and Scalable Model Selection with Multi-Armed Bandits
|
Many online applications running on live traffic are powered by machine learning models, for which training, validation, and hyper-parameter tuning are conducted on historical data. However, it is common for models demonstrating strong performance in offline analysis to yield poorer performance when deployed online. This problem is a consequence of the difficulty of training on historical data in non-stationary environments. Moreover, the machine learning metrics used for model selection may not sufficiently correlate with real-world business metrics used to determine the success of the applications being tested. These problems are particularly prominent in the Real-Time Bidding (RTB) domain, in which ML models power bidding strategies, and a change in models will likely affect performance of the advertising campaigns. In this work, we present Automatic Model Selector (AMS), a system for scalable online selection of RTB bidding strategies based on real-world performance metrics. AMS employs Multi-Armed Bandits (MAB) to near-simultaneously run and evaluate multiple models against live traffic, allocating the most traffic to the best-performing models while decreasing traffic to those with poorer online performance, thereby minimizing the impact of inferior models on overall campaign performance. The reliance on offline data is avoided, instead making model selections on a case-by-case basis according to actionable business goals. AMS allows new models to be safely introduced into live campaigns as soon as they are developed, minimizing the risk to overall performance. In live-traffic tests on multiple ad campaigns, the AMS system proved highly effective at improving ad campaign performance.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LG"
] | 2021-01-25T20:12:52Z |
1309.3994
|
Quantum estimation of magnetic-field gradient using W-state
|
We study the precision limits of detecting a linear magnetic-field gradient by using W-states in the presence of different types of noises. We consider to use an atomic spin chain for probing the magnetic-field gradient, where a W-state is prepared. We compare this method with the measurement of using two uncorrelated atoms. For pure states, W-states can provide an improvement over uncorrelated states in determining the magnetic-field gradient up to four particles. We examine the effects of local dephasing and dissipations on the performances of detections. In presence of dephasing, the uncorrelated atoms can give a higher precision than using W-states. But W-states provide a better performance in the presence of dissipation for a few particles. We briefly discuss the implementation of the detection methods with cold atoms and trapped ions.
|
[
"Physics Archive->quant-ph"
] | 2013-09-16T15:07:26Z |
2304.11524
|
Personalized Federated Learning via Gradient Modulation for Heterogeneous Text Summarization
|
Text summarization is essential for information aggregation and demands large amounts of training data. However, concerns about data privacy and security limit data collection and model training. To eliminate this concern, we propose a federated learning text summarization scheme, which allows users to share the global model in a cooperative learning manner without sharing raw data. Personalized federated learning (PFL) balances personalization and generalization in the process of optimizing the global model, to guide the training of local models. However, multiple local data have different distributions of semantics and context, which may cause the local model to learn deviated semantic and context information. In this paper, we propose FedSUMM, a dynamic gradient adapter to provide more appropriate local parameters for local model. Simultaneously, FedSUMM uses differential privacy to prevent parameter leakage during distributed training. Experimental evidence verifies FedSUMM can achieve faster model convergence on PFL algorithm for task-specific text summarization, and the method achieves superior performance for different optimization metrics for text summarization.
|
[
"Computer Science Archive->cs.AI"
] | 2023-04-23T03:18:46Z |
1409.1261
|
The 3 $\mu$m Spectrum of Jupiter's Irregular Satellite Himalia
|
We present a medium resolution spectrum of Jupiter's irregular satellite Himalia covering the critical 3 $\mu$m spectral region. The spectrum shows no evidence for aqueously altered phyllosilicates, as had been suggested from the tentative detection of a 0.7 $\mu$m absorption, but instead shows a spectrum strikingly similar to the C/CF type asteroid 52 Europa. 52 Europa is the prototype of a class of asteroids generally situated in the outer asteroid belt between less distant asteroids which show evidence for aqueous alteration and more distant asteroids which show evidence for water ice. The spectral match between Himalia and this group of asteroids is surprising and difficult to reconcile with models of the origin of the irregular satellites.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2014-09-03T21:11:05Z |
1912.10426
|
A single-hole spin qubit
|
Qubits based on quantum dots have excellent prospects for scalable quantum technology due to their inherent compatibility with standard semiconductor manufacturing. While early on it was recognized that holes may offer a multitude of favourable properties for fast and scalable quantum control, research thus far has remained almost exclusively restricted to the simpler electron system. However, recent developments with holes have led to separate demonstrations of single-shot readout and fast quantum logic, albeit only in the multi-hole regime. Here, we establish a single-hole spin qubit in germanium and demonstrate the integration of single-shot readout and quantum control. Moreover, we make use of Pauli spin blockade, allowing to arbitrarily set the qubit resonance frequency, while providing large readout windows. We deplete a planar germanium double quantum dot to the last hole, confirmed by radio-frequency reflectrometry charge sensing, and achieve single-shot spin readout. To demonstrate the integration of the readout and qubit operation, we show Rabi driving on both qubits and find remarkable electric control over their resonance frequencies. Finally, we analyse the spin relaxation time, which we find to exceed one millisecond, setting the benchmark for hole-based spin qubits. The ability to coherently manipulate a single hole spin underpins the quality of strained germanium and defines an excellent starting point for the construction of novel quantum hardware.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2019-12-22T11:45:32Z |
1606.04476
|
Downlink Performance of Superimposed Pilots in Massive MIMO systems
|
In this paper, we investigate the downlink throughput performance of a massive multiple-input multiple-output (MIMO) system that employs superimposed pilots for channel estimation. The component of downlink (DL) interference that results from transmitting data alongside pilots in the uplink (UL) is shown to decrease at a rate proportional to the square root of the number of antennas at the BS. The normalized mean-squared error (NMSE) of the channel estimate is compared with the Bayesian Cram\'{e}r-Rao lower bound that is derived for the system, and the former is also shown to diminish with increasing number of antennas at the base station (BS). Furthermore, we show that staggered pilots are a particular case of superimposed pilots and offer the downlink throughput of superimposed pilots while retaining the UL spectral and energy efficiency of regular pilots. We also extend the framework for designing a hybrid system, consisting of users that transmit either regular or superimposed pilots, to minimize both the UL and DL interference. The improved NMSE and DL rates of the channel estimator based on superimposed pilots are demonstrated by means of simulations.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2016-06-14T17:53:37Z |
astro-ph/0306294
|
String Imprints from a Pre-inflationary Era
|
We derive the equations governing the dynamics of cosmic strings in a flat anisotropic universe of Bianchi type I and study the evolution of simple cosmic string loop solutions. We show that the anisotropy of the background can have a characteristic effect in the loop motion. We discuss some cosmological consequences of these findings and, by extrapolating our results to cosmic string networks, we comment on their ability to survive an inflationary epoch, and hence be a possible fossil remnant (still visible today) of an anisotropic phase in the very early universe.
|
[
"Physics Archive->astro-ph"
] | 2003-06-14T09:18:35Z |
2312.02215
|
A generalisation of the method of regression calibration and comparison with the Bayesian 2-dimensional Monte Carlo method
|
For many cancer sites it is necessary to assess risks from low-dose exposures via extrapolation from groups exposed at moderate and high levels of dose. Measurement error can substantially alter the shape of this relationship and hence the derived population risk estimates. Recently, much attention has been devoted to the issue of shared errors, common in many datasets, and particularly important in occupational settings. In this paper we test a Bayesian model averaging method, the so-called Bayesian two-dimensional Monte Carlo (2DMC) method, that has been fairly recently proposed against a very newly proposed modification of the regression calibration method, which is particularly suited to studies in which there is a substantial amount of shared error, and in which there may also be curvature in the true dose response. We also compared both methods against standard regression calibration and Monte Carlo maximum likelihood. The Bayesian 2DMC method performs poorly, with coverage probabilities both for the linear and quadratic dose coefficients that are under 5%, particularly when the magnitudes of classical and Berkson error are both moderate to large (20%-50%). The method also produces substantially biased (by a factor of 10) estimates of both the linear and quadratic coefficients, with the linear coefficient overestimated and the quadratic coefficient underestimated. By comparison the extended regression calibration method yields coverage probabilities that are too low when shared and unshared Berkson errors are both large (50%), although otherwise it performs well, and coverage is generally better than the Bayesian 2DMC and all other methods. The bias of the predicted relative risk at a variety of doses is generally smallest for extended regression calibration, and largest for the Bayesian 2DMC method.
|
[
"Quantitative Biology Archive->q-bio.QM"
] | 2023-12-03T09:46:39Z |
2210.04443
|
Don't Copy the Teacher: Data and Model Challenges in Embodied Dialogue
|
Embodied dialogue instruction following requires an agent to complete a complex sequence of tasks from a natural language exchange. The recent introduction of benchmarks (Padmakumar et al., 2022) raises the question of how best to train and evaluate models for this multi-turn, multi-agent, long-horizon task. This paper contributes to that conversation, by arguing that imitation learning (IL) and related low-level metrics are actually misleading and do not align with the goals of embodied dialogue research and may hinder progress. We provide empirical comparisons of metrics, analysis of three models, and make suggestions for how the field might best progress. First, we observe that models trained with IL take spurious actions during evaluation. Second, we find that existing models fail to ground query utterances, which are essential for task completion. Third, we argue evaluation should focus on higher-level semantic goals.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.LG"
] | 2022-10-10T05:51:40Z |
1603.05043
|
On a Kaehlerian space-time manifold
|
In this paper, the theory of space-time in 4-dimensional Kaehler manifold has been studied. We have discussed the Einstein equation with cosmological constant in perfect fluid Kaehler space-time manifold and proved that the isotropic pressure, energy density and the energy momentum tensor vanish and such a space-time manifold is an Einstein manifold. We have shown also that a conformally flat perfect fluid Kaehler space-time manifold is infinitesimally spatially isotropic relative to the velocity vector field. In last two sections, we have studied weakly symmetric and weakly Ricci symmetric perfect fluid Kaehler space-time manifolds and it has been shown, either the manifold is of zero scalar curvature or the associated vector fields rho and alpha are related by g(rho,alpha) = 4. At last, we have proved that the weakly Ricci symmetric perfect fluid Kaehler space-time manifold of non-zero scalar curvature does not exist.
|
[
"Mathematics Archive->math.GM"
] | 2016-03-16T11:33:55Z |
1911.04982
|
Scaling limits of permutations avoiding long decreasing sequences
|
We determine the scaling limit for permutations conditioned to have longest decreasing subsequence of length at most $d$. These permutations are also said to avoid the pattern $(d+1)d \cdots 2 1$ and they can be written as a union of $d$ increasing subsequences. We show that these increasing subsequences can be chosen so that, after proper scaling, and centering, they converge in distribution. As the size of the permutations tends to infinity, the distribution of functions generated by the permutations converges to the eigenvalue process of a traceless $d\times d$ Hermitian Brownian bridge.
|
[
"Mathematics Archive->math.PR"
] | 2019-11-12T16:13:41Z |
1406.5204
|
Improving Dark Matter Searches by Measuring the Nucleon Axial Form Factor: Perspectives from MicroBooNE
|
The MicroBooNE neutrino experiment at Fermilab is constructing a liquid-argon time-projection chamber for the Booster Neutrino Beam to study neutrino oscillations and interactions with nucleons and nuclei, starting in 2014. We describe the experiment and focus on its unique abilities to measure cross sections at low values of $Q^2$. In particular, the neutral-current elastic scattering cross section is especially interesting, as it is sensitive to the contribution of the strange sea quark spin to the angular-momentum of the nucleon, $\Delta s$. Implications for dark-matter searches are discussed.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2014-06-19T20:20:20Z |
hep-th/9601169
|
Noncommutative Kaluza-Klein Theory
|
Efforts have been made recently to reformulate traditional Kaluza-Klein theory by using a generalized definition of a higher-dimensional extended space-time. Both electromagnetism and gravity have been studied in this context. We review some of the models which have been proposed, with a special effort to keep the mathematical formalism to a very minimum.
|
[
"Physics Archive->hep->hep-th"
] | 1996-01-31T10:32:37Z |
2204.10408
|
ICDBigBird: A Contextual Embedding Model for ICD Code Classification
|
The International Classification of Diseases (ICD) system is the international standard for classifying diseases and procedures during a healthcare encounter and is widely used for healthcare reporting and management purposes. Assigning correct codes for clinical procedures is important for clinical, operational, and financial decision-making in healthcare. Contextual word embedding models have achieved state-of-the-art results in multiple NLP tasks. However, these models have yet to achieve state-of-the-art results in the ICD classification task since one of their main disadvantages is that they can only process documents that contain a small number of tokens which is rarely the case with real patient notes. In this paper, we introduce ICDBigBird a BigBird-based model which can integrate a Graph Convolutional Network (GCN), that takes advantage of the relations between ICD codes in order to create 'enriched' representations of their embeddings, with a BigBird contextual model that can process larger documents. Our experiments on a real-world clinical dataset demonstrate the effectiveness of our BigBird-based model on the ICD classification task as it outperforms the previous state-of-the-art models.
|
[
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.LG"
] | 2022-04-21T20:59:56Z |
1201.5830
|
Bridgeland stability conditions on twisted Kummer surfaces
|
We construct a topological embedding of the maximal connected component of Bridgeland stability conditions of a (twisted) Abelian surface into the distinguished connected component of the stability manifold of the associated (twisted) Kummer surface. We use methods developed for orbifold conformal field theories.
|
[
"Mathematics Archive->math.AG",
"Physics Archive->hep->hep-th"
] | 2012-01-27T16:52:37Z |
1904.04819
|
Practical self-testing quantum random number generator based on an energy bound
|
We present a scheme for a self-testing quantum random number generator. Compared to the fully device-independent model, our scheme requires an extra natural assumption, namely that the mean energy per signal is bounded. The scheme is self-testing, as it allows the user to verify in real-time the correct functioning of the setup, hence guaranteeing the continuous generation of certified random bits. Based on a prepare-and-measure setup, our scheme is practical, and we implement it using only off-the-shelf optical components. The randomness generation rate is 1.25 Mbits/s, comparable to commercial solutions. Overall, we believe that this scheme achieves a promising trade-off between the required assumptions, ease-of-implementation and performance.
|
[
"Physics Archive->quant-ph"
] | 2019-04-09T17:58:21Z |
2109.03440
|
Pythagorean Triples in the Fibonacci Model Set
|
In this paper we give a description of all Pythagorean triples in the ring ${{\mathbb Z}}[\tau]$. We also consider triples in the Fibonacci model set which satisfy the Diophantine equations arising from Fermat's Last Theorem. Examples are provided, including a counterexample to Fermat's Last Theorem for the third degree in the Fibonacci model set.
|
[
"Mathematics Archive->math.DS"
] | 2021-09-08T05:39:43Z |
2310.00341
|
Mathematical Model of Dating Apps' Influence on Sexually Transmitted Diseases Spread
|
Sexually transmitted diseases (STDs) are a group of pathogens infecting new hosts through sexual interactions. Due to its social and economic burden, multiple models have been proposed to study the spreading of pathogens. In parallel, in the ever-evolving landscape of digital social interactions, the pervasive utilization of dating apps has become a prominent facet of modern society. Despite the surge in popularity and the profound impact on relationship formation, a crucial gap in the literature persists regarding the potential ramifications of dating apps usage on the dynamics of STDs. In this paper, we address this gap by presenting a novel mathematical framework - an extended Susceptible-Infected-Susceptible (SIS) epidemiological model to elucidate the intricate interplay between dating apps engagement and the propagation of STDs. Namely, as dating apps are designed to make users revisit them and have mainly casual sexual interactions with other users, they increase the number of causal partners, which increases the overall spread of STDS. Using extensive simulation, based on real-world data, explore the effect of dating apps adoption and control on the STD spread. We show that an increased adoption of dating apps can result in an STD outbreak if not handled appropriately.
|
[
"Computer Science Archive->cs.SI"
] | 2023-09-30T11:15:36Z |
2204.12609
|
A 3-Approximation Algorithm for a Particular Case of the Hamiltonian p-Median Problem
|
Given a weighted graph $G$ with $n$ vertices and $m$ edges, and a positive integer $p$, the Hamiltonian $p$-median problem consists in finding $p$ cycles of minimum total weight such that each vertex of $G$ is in exactly one cycle. We introduce an $O(n^6)$ 3-approximation algorithm for the particular case in which $p \leq \lceil \frac{n-2\lceil \frac{n}{5} \rceil}{3} \rceil$. An approximation ratio of 2 might be obtained depending on the number of components in the optimal 2-factor of $G$. We present computational experiments comparing the approximation algorithm to an exact algorithm from the literature. In practice much better ratios are obtained. For large values of $p$, the exact algorithm is outperformed by our approximation algorithm.
|
[
"Computer Science Archive->cs.DS"
] | 2022-04-26T21:49:32Z |
1810.06850
|
A versatile quantum walk resonator with bright classical light
|
In a Quantum Walk (QW) the "walker" follows all possible paths at once through the principle of quantum superposition, differentiating itself from classical random walks where one random path is taken at a time. This facilitates the searching of problem solution spaces faster than with classical random walks, and holds promise for advances in dynamical quantum simulation, biological process modelling and quantum computation. Current efforts to implement QWs have been hindered by the complexity of handling single photons and the inscalability of cascading approaches. Here we employ a versatile and scalable resonator configuration to realise quantum walks with bright classical light. We experimentally demonstrate the versatility of our approach by implementing a variety of QWs, all with the same experimental platform, while the use of a resonator allows for an arbitrary number of steps without scaling the number of optics. Our approach paves the way for practical QWs with bright classical light and explicitly makes clear that quantum walks with a single walker do not require quantum states of light.
|
[
"Physics Archive->quant-ph"
] | 2018-10-16T07:43:07Z |
1908.06567
|
Recommendation of Exception Handling Code in Mobile App Development
|
In modern programming languages, exception handling is an effective mechanism to avoid unexpected runtime errors. Thus, failing to catch and handle exceptions could lead to serious issues like system crashing, resource leaking, or negative end-user experiences. However, writing correct exception handling code is often challenging in mobile app development due to the fast-changing nature of API libraries for mobile apps and the insufficiency of their documentation and source code examples. Our prior study shows that in practice mobile app developers cause many exception-related bugs and still use bad exception handling practices (e.g. catch an exception and do nothing). To address such problems, in this paper, we introduce two novel techniques for recommending correct exception handling code. One technique, XRank, recommends code to catch an exception likely occurring in a code snippet. The other, XHand, recommends correction code for such an occurring exception. We have developed ExAssist, a code recommendation tool for exception handling using XRank and XHand. The empirical evaluation shows that our techniques are highly effective. For example, XRank has top-1 accuracy of 70% and top-3 accuracy of 87%. XHand's results are 89% and 96%, respectively.
|
[
"Computer Science Archive->cs.SE"
] | 2019-08-19T02:46:01Z |
1609.05344
|
Optimisations for Real-Time Volumetric Cloudscapes
|
Volumetric cloudscapes are prohibitively expensive to render in real time without extensive optimisations. Previous approaches render the clouds to an offscreen buffer at one quarter resolution and update a fraction of the pixels per frame, drawing the remaining pixels by temporal reprojection. We present an alternative approach, reducing the number of raymarching steps and adding a randomly jittered offset to the raymarch. We use an analytical integration technique to make results consistent with a lower number of raymarching steps. To remove noise from the resulting image we apply a temporal anti-aliasing implementation. The result is a technique producing visually similar results with 1/16 the number of steps.
|
[
"Computer Science Archive->cs.GR"
] | 2016-09-17T14:43:17Z |
cond-mat/0407320
|
Critical temperature of superconducting bilayers: theory and experiment
|
A generalized model for the critical temperature Tc of superconducting bilayers is presented, which is valid with no restrictions to film thicknesses, Tc of the layers and interface resistivity. The model is verified experimentally on a series of Nb-Al and Ta-Al bilayers with Nb, Ta layer thicknesses of 100 nm and Al layer thicknesses ranging from 5 nm to 200 nm. Excellent agreement between theory and experiment was found for the energy gap and the Tc of bilayers. The results are important for designing practical superconducting devices.
|
[
"Physics Archive->cond-mat->cond-mat.supr-con"
] | 2004-07-13T09:22:20Z |
1403.5000
|
Light composite scalar in eight-flavor QCD on the lattice
|
We present the first observation of a flavor-singlet scalar meson as light as the pion in $N_f=8$ QCD on the lattice, using the Highly Improved Staggered Quark action. Such a light scalar meson can be regarded as a composite Higgs with mass 125 GeV. In accord with our previous lattice results showing that the theory exhibits walking behavior, the light scalar may be a technidilaton, a pseudo Nambu-Goldstone boson of the approximate scale symmetry in walking technicolor.
|
[
"Physics Archive->hep->hep-lat",
"Physics Archive->hep->hep-ph"
] | 2014-03-19T23:16:34Z |
1506.07598
|
The influence of initial solutions to exact solutions of the (2+1)-dimensional generalized Nizhnik-Novikov-Veselov equations
|
The (2+1)-dimensional generalized Nizhnik-Novikov-Veselov equations (GNNVEs) are investigated in order to search the influence of initial solution to exact solutions. The GNNVEs are converted into the combined equations of differently two bilinear forms by means of the homogeneous balance of undetermined coefficients method. Accordingly, the two class of exact N-soliton solutions and three wave solutions are obtained respectively by using the Hirota direct method combined with the simplified version of Hereman and the three wave method. The proposed method is also a standard and computable method, which can be generalized to deal with some nonlinear partial differential equations (NLPDEs).
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2015-06-25T02:42:58Z |
2310.06495
|
Some Remarks on the Spectrum of Nonlinear Continuous Operators
|
In this article, the existence of the spectrum (the eigenvalues) for the nonlinear continuous operators acting in the Banach spaces is investigated. For the study, this question is used a different approach that allows the studying of all eigenvalues of the nonlinear operator relative to another nonlinear operator. Here shows that in nonlinear operators, case is necessary to seek the spectrum of the given nonlinear operator relative to another nonlinear operator satisfying certain conditions. The different examples, for which eigenvalues can be found are provided. Moreover, the nonlinear problems including parameters are studied.
|
[
"Mathematics Archive->math.FA"
] | 2023-10-10T10:09:05Z |
1107.2139
|
Factoring Sobolev inequalities through classes of functions
|
We recall two approaches to recent improvements of the classical Sobolev inequality. The first one follows the point of view of Real Analysis, while the second one relies on tools from Convex Geometry. In this paper we prove a (sharp) connection between them.
|
[
"Mathematics Archive->math.FA"
] | 2011-07-11T20:38:39Z |
2007.06521
|
Predicting the long-term stability of compact multiplanet systems
|
We combine analytical understanding of resonant dynamics in two-planet systems with machine learning techniques to train a model capable of robustly classifying stability in compact multi-planet systems over long timescales of $10^9$ orbits. Our Stability of Planetary Orbital Configurations Klassifier (SPOCK) predicts stability using physically motivated summary statistics measured in integrations of the first $10^4$ orbits, thus achieving speed-ups of up to $10^5$ over full simulations. This computationally opens up the stability constrained characterization of multi-planet systems. Our model, trained on $\approx 100,000$ three-planet systems sampled at discrete resonances, generalizes both to a sample spanning a continuous period-ratio range, as well as to a large five-planet sample with qualitatively different configurations to our training dataset. Our approach significantly outperforms previous methods based on systems' angular momentum deficit, chaos indicators, and parametrized fits to numerical integrations. We use SPOCK to constrain the free eccentricities between the inner and outer pairs of planets in the Kepler-431 system of three approximately Earth-sized planets to both be below 0.05. Our stability analysis provides significantly stronger eccentricity constraints than currently achievable through either radial velocity or transit duration measurements for small planets, and within a factor of a few of systems that exhibit transit timing variations (TTVs). Given that current exoplanet detection strategies now rarely allow for strong TTV constraints (Hadden et al., 2019), SPOCK enables a powerful complementary method for precisely characterizing compact multi-planet systems. We publicly release SPOCK for community use.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2020-07-13T17:26:41Z |
2207.14527
|
Cohomology algebra of orbit spaces of free involutions on the product of projective space and 4-sphere
|
Let $X$ be a finitistic space with the mod 2 cohomology of the product space of a projective space and a 4-sphere. Assume that $X$ admits a free involution. In this paper we study the mod 2 cohomology algebra of the quotient of $X$ by the action of the free involution and derive some consequences regarding the existence of $\mathbb{Z}_2$-equivariant maps between such $X$ and an $n$-sphere.
|
[
"Mathematics Archive->math.AT"
] | 2022-07-29T07:49:42Z |
1405.7135
|
Odr\v{z}avanje ra\v{c}unarskih sistema
|
Computer hardware and software are resources without which the modern business of any organization, from manufacturing to services, is impossible. Not enough attention is being payed to maintenance of computer systems as an aspect of business. This paper gives some recommendations for the selection of the computer systems maintenance approach, based on many years of experience maintaining these systems at the University of Zenica.
|
[
"Computer Science Archive->cs.OH"
] | 2014-05-28T07:01:00Z |
1908.07511
|
Holomorphic Chern-Simons theory and affine Gaudin models
|
We relate two formalisms recently proposed for describing classical integrable field theories. The first is based on the action of four-dimensional holomorphic Chern-Simons theory introduced and studied by Costello, Witten and Yamazaki. The second makes use of classical generalised Gaudin models associated with untwisted affine Kac-Moody algebras.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->hep->hep-th",
"Physics Archive->math-ph"
] | 2019-08-20T17:52:02Z |
1709.06493
|
Learning to update Auto-associative Memory in Recurrent Neural Networks for Improving Sequence Memorization
|
Learning to remember long sequences remains a challenging task for recurrent neural networks. Register memory and attention mechanisms were both proposed to resolve the issue with either high computational cost to retain memory differentiability, or by discounting the RNN representation learning towards encoding shorter local contexts than encouraging long sequence encoding. Associative memory, which studies the compression of multiple patterns in a fixed size memory, were rarely considered in recent years. Although some recent work tries to introduce associative memory in RNN and mimic the energy decay process in Hopfield nets, it inherits the shortcoming of rule-based memory updates, and the memory capacity is limited. This paper proposes a method to learn the memory update rule jointly with task objective to improve memory capacity for remembering long sequences. Also, we propose an architecture that uses multiple such associative memory for more complex input encoding. We observed some interesting facts when compared to other RNN architectures on some well-studied sequence learning tasks.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2017-09-19T15:55:16Z |
hep-ph/9609479
|
Axial-vector meson mixing in orthocharmonium decays
|
The new BES measurement on the two-body decays of J/psi and psi' into an axial-vector meson and a pseudoscalar meson is analyzed with the axial-K mixing including the one-photon annihilation contribution. A somewhat puzzling pattern of the K_1^+ K^- decay channels can be understood with no tight constraint on the mixing angle. The branching fractions of the K_1^0 K-bar^0 channels will be the cleanest source of information to determine the mixing angle from the 1^+ 0^- decays of J/psi and psi'.
|
[
"Physics Archive->hep->hep-ph"
] | 1996-09-25T20:57:11Z |
1310.7020
|
Exploring the chemical link between local ellipticals and their high-redshift progenitors
|
We present Keck/MOSFIRE K-band spectroscopy of the first mass-selected sample of galaxies at $z\sim2.3$. Targets are selected from the 3D-HST Treasury survey. The six detected galaxies have a mean [NII]$\lambda$6584/H$\alpha$ ratio of $0.27\pm0.01$, with a small standard deviation of 0.05. This mean value is similar to that of UV-selected galaxies of the same mass. The mean gas-phase oxygen abundance inferred from the [NII]/H$\alpha$ ratios depends on the calibration method, and ranges from 12+log(O/H)$_{gas}=8.57$ for the {Pettini} & {Pagel} (2004) calibration to 12+log(O/H)$_{gas}= 8.87$ for the {Maiolino} {et~al.} (2008) calibration. Measurements of the stellar oxygen abundance in nearby quiescent galaxies with the same number density indicate 12+log(O/H)$_{stars}= 8.95$, similar to the gas-phase abundances of the $z\sim2.3$ galaxies if the {Maiolino} {et~al.} (2008) calibration is used. This suggests that these high-redshift star forming galaxies may be progenitors of today's massive early-type galaxies. The main uncertainties are the absolute calibration of the gas-phase oxygen abundance and the incompleteness of the $z\sim2.3$ sample: the galaxies with detected H$\alpha$ tend to be larger and have higher star formation rates than the galaxies without detected H$\alpha$, and we may still be missing the most dust-obscured progenitors.
|
[
"Physics Archive->astro-ph->astro-ph.CO"
] | 2013-10-25T20:00:00Z |
quant-ph/0301005
|
Quantum dissipation induced noncommutative geometry
|
The quantum statistical dynamics of a position coordinate x coupled to a reservoir requires theoretically two copies of the position coordinate within the reduced density matrix description. One coordinate moves forward in time while the other coordinate moves backward in time. It is shown that quantum dissipation induces, in the plane of the forward and backward motions, a noncommutative geometry. The noncommutative geometric plane is a consequence of a quantum dissipation induced phase interference which is closely analogous to the Aharanov-Bohm effect.
|
[
"Physics Archive->quant-ph"
] | 2003-01-03T19:26:07Z |
1002.2906
|
Invariant formulation of surfaces associated with $CP^{N-1}$ models
|
In this paper, we provide an invariant formulation of completely integrable $CP^{N-1}$ Euclidean sigma models in two dimensions defined on the Riemann sphere $S^2$. The scaling invariance is explicitly taken into account by expressing all the equations in terms of projection operators. Properties of the projectors mapping onto one-dimensional subspaces are discussed in detail. The paper includes a discussion of surfaces connected with the $CP^{N-1}$ models and the wave functions of their linear spectral problem.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph",
"Physics Archive->nlin->nlin.SI"
] | 2010-02-15T16:26:07Z |
1105.3107
|
Learning to Place New Objects
|
The ability to place objects in the environment is an important skill for a personal robot. An object should not only be placed stably, but should also be placed in its preferred location/orientation. For instance, a plate is preferred to be inserted vertically into the slot of a dish-rack as compared to be placed horizontally in it. Unstructured environments such as homes have a large variety of object types as well as of placing areas. Therefore our algorithms should be able to handle placing new object types and new placing areas. These reasons make placing a challenging manipulation task. In this work, we propose a supervised learning algorithm for finding good placements given the point-clouds of the object and the placing area. It learns to combine the features that capture support, stability and preferred placements using a shared sparsity structure in the parameters. Even when neither the object nor the placing area is seen previously in the training set, our algorithm predicts good placements. In extensive experiments, our method enables the robot to stably place several new objects in several new placing areas with 98% success-rate; and it placed the objects in their preferred placements in 92% of the cases.
|
[
"Computer Science Archive->cs.RO"
] | 2011-05-16T14:41:10Z |
1612.01345
|
Human-In-The-Loop Person Re-Identification
|
Current person re-identification (re-id) methods assume that (1) pre-labelled training data are available for every camera pair, (2) the gallery size for re-identification is moderate. Both assumptions scale poorly to real-world applications when camera network size increases and gallery size becomes large. Human verification of automatic model ranked re-id results becomes inevitable. In this work, a novel human-in-the-loop re-id model based on Human Verification Incremental Learning (HVIL) is formulated which does not require any pre-labelled training data to learn a model, therefore readily scalable to new camera pairs. This HVIL model learns cumulatively from human feedback to provide instant improvement to re-id ranking of each probe on-the-fly enabling the model scalable to large gallery sizes. We further formulate a Regularised Metric Ensemble Learning (RMEL) model to combine a series of incrementally learned HVIL models into a single ensemble model to be used when human feedback becomes unavailable.
|
[
"Computer Science Archive->cs.CV"
] | 2016-12-05T13:29:47Z |
cond-mat/0105084
|
Fragile-to-strong transition and polyamorphism in the energy landscape of liquid silica
|
We study the static and dynamic properties of liquid silica over a wide range of temperature T and density using computer simulations. The results reveal a change in the potential energy landscape as T decreases that underlies a transition from a fragile liquid at high T to a strong liquid at low T. We also show that a specific heat anomaly is associated with this fragile-to-strong transition, and suggest that this anomaly is related to the polyamorphic behaviour of amorphous solid silica.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2001-05-04T03:29:52Z |
cond-mat/9710247
|
The generalized localization lengths in one dimensional systems with correlated disorder
|
The scale invariant properties of wave functions in finite samples of one dimensional random systems with correlated disorder are analyzed. The random dimer model and its generalizations are considered and the wave functions are compared. Generalized entropic localization lengths are introduced in order to characterize the states and compared with their behavior for exponential localization. An acceptable agreement is obtained, however, the exponential form seems to be an oversimplification in the presence of correlated disorder. According to our analysis in the case of the random dimer model and the two new models the presence of power-law localization cannot be ruled out.
|
[
"Physics Archive->cond-mat->cond-mat.dis-nn"
] | 1997-10-23T10:38:21Z |
1103.3050
|
Near-field radiative heat transfer for structured surfaces
|
We apply an analytical approach for determining the near-field radiative heat transfer between a metallic nanosphere and a planar semi-infinite medium with some given surface structure. This approach is based on a perturbative expansion, and evaluated to first order in the surface profile. With the help of numerical results obtained for some simple model geometries we discuss typical signatures that should be obtainable with a near-field scanning thermal microscope operated in either constant-height or constant-distance mode.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->quant-ph"
] | 2011-03-15T21:37:58Z |
1502.02961
|
Avatar-independent scripting for real-time gesture animation
|
When animation of a humanoid figure is to be generated at run-time, instead of by replaying pre-composed motion clips, some method is required of specifying the avatar's movements in a form from which the required motion data can be automatically generated. This form must be of a more abstract nature than raw motion data: ideally, it should be independent of the particular avatar's proportions, and both writable by hand and suitable for automatic generation from higher-level descriptions of the required actions. We describe here the development and implementation of such a scripting language for the particular area of sign languages of the deaf, called SiGML (Signing Gesture Markup Language), based on the existing HamNoSys notation for sign languages. We conclude by suggesting how this work may be extended to more general animation for interactive virtual reality applications.
|
[
"Computer Science Archive->cs.GR"
] | 2015-02-10T16:03:37Z |
2202.07574
|
Damped Online Newton Step for Portfolio Selection
|
We revisit the classic online portfolio selection problem, where at each round a learner selects a distribution over a set of portfolios to allocate its wealth. It is known that for this problem a logarithmic regret with respect to Cover's loss is achievable using the Universal Portfolio Selection algorithm, for example. However, all existing algorithms that achieve a logarithmic regret for this problem have per-round time and space complexities that scale polynomially with the total number of rounds, making them impractical. In this paper, we build on the recent work by Haipeng et al. 2018 and present the first practical online portfolio selection algorithm with a logarithmic regret and whose per-round time and space complexities depend only logarithmically on the horizon. Behind our approach are two key technical novelties of independent interest. We first show that the Damped Online Newton steps can approximate mirror descent iterates well, even when dealing with time-varying regularizers. Second, we present a new meta-algorithm that achieves an adaptive logarithmic regret (i.e. a logarithmic regret on any sub-interval) for mixable losses.
|
[
"Computer Science Archive->cs.LG",
"Mathematics Archive->math.OC"
] | 2022-02-15T17:01:55Z |
cond-mat/0110605
|
Football goal distributions and extremal statistics
|
We analyse the distributions of the number of goals scored by home teams, away teams, and the total scored in the match, in domestic football games from 169 countries between 1999 and 2001. The probability density functions (PDFs) of goals scored cannot be fitted over their entire ranges by Poisson or negative binomial distributions; here, we compare the PDFs with those arising from extremal statistics. In addition, we show that it is sufficient to model English top division and FA Cup matches in the seasons of 1970/71 to 2000/01 on Poisson or negative binomial distributions, as reported in analyses of earlier seasons, and that these are not consistent with extremal statistics.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2001-10-29T20:26:51Z |
2203.09463
|
FERV39k: A Large-Scale Multi-Scene Dataset for Facial Expression Recognition in Videos
|
Current benchmarks for facial expression recognition (FER) mainly focus on static images, while there are limited datasets for FER in videos. It is still ambiguous to evaluate whether performances of existing methods remain satisfactory in real-world application-oriented scenes. For example, the "Happy" expression with high intensity in Talk-Show is more discriminating than the same expression with low intensity in Official-Event. To fill this gap, we build a large-scale multi-scene dataset, coined as FERV39k. We analyze the important ingredients of constructing such a novel dataset in three aspects: (1) multi-scene hierarchy and expression class, (2) generation of candidate video clips, (3) trusted manual labelling process. Based on these guidelines, we select 4 scenarios subdivided into 22 scenes, annotate 86k samples automatically obtained from 4k videos based on the well-designed workflow, and finally build 38,935 video clips labeled with 7 classic expressions. Experiment benchmarks on four kinds of baseline frameworks were also provided and further analysis on their performance across different scenes and some challenges for future research were given. Besides, we systematically investigate key components of DFER by ablation studies. The baseline framework and our project will be available.
|
[
"Computer Science Archive->cs.CV"
] | 2022-03-17T17:25:33Z |
0812.3953
|
Upper and lower critical fields in NdFeAs(O,F) single crystals : a study by Hall probe magnetization and specific heat
|
The upper and lower critical fields have been deduced from specific heat and Hall probe magnetization measurements in non-optimally doped NdFeAs(O,F) single crystals ($T_c \sim 32-35$K). The anisoptropy of the penetration depth ($\Gamma_\lambda$) is temperature independent and on the order of $4.0 \pm 1.5$. Similarly specific heat data lead an anisotropy of the coherence lenght $\Gamma_\xi \sim 5.5 \pm 1.5$ close to $T_c$. Our results suggest the presence of rather large thermal fluctuations and to the existence of a vortex liquid phase over a broad temperature range ($\sim 5$K large at 2T).
|
[
"Physics Archive->cond-mat->cond-mat.supr-con"
] | 2008-12-20T09:49:06Z |
1503.01086
|
Some properties of a sequence defined with the aid of prime numbers
|
For every integer $n\ge 1$ let $a_n$ be the smallest positive integer such that $n+a_n$ is prime. We investigate the behavior of the sequence $(a_n)_{n\ge 1}$, and prove asymptotic results for the sums $\sum_{n\le x} a_n$, $\sum_{n\le x} 1/a_n$ and $\sum_{n\le x} \log a_n$.
|
[
"Mathematics Archive->math.NT"
] | 2015-03-03T20:07:48Z |
1309.3079
|
Pseudo-holomorphic functions at the critical exponent
|
We study Hardy classes on the disk associated to the equation $\bar\d w=\alpha\bar w$ for $\alpha\in L^r$ with $2\leq r<\infty$. The paper seems to be the first to deal with the case $r=2$. We prove an analog of the M.~Riesz theorem and a topological converse to the Bers similarity principle. Using the connection between pseudo-holomorphic functions and conjugate Beltrami equations, we deduce well-posedness on smooth domains of the Dirichlet problem with weighted $L^p$ boundary data for 2-D isotropic conductivity equations whose coefficients have logarithm in $W^{1,2}$. In particular these are not strictly elliptic. Our results depend on a new multiplier theorem for $W^{1,2}_0$-functions.
|
[
"Mathematics Archive->math.AP",
"Mathematics Archive->math.CA"
] | 2013-09-12T09:49:50Z |
1309.7964
|
A General Formula for the Mismatch Capacity
|
The fundamental limits of channels with mismatched decoding are addressed. A general formula is established for the mismatch capacity of a general channel, defined as a sequence of conditional distributions with a general decoding metrics sequence. We deduce an identity between the Verd\'{u}-Han general channel capacity formula, and the mismatch capacity formula applied to Maximum Likelihood decoding metric. Further, several upper bounds on the capacity are provided, and a simpler expression for a lower bound is derived for the case of a non-negative decoding metric. The general formula is specialized to the case of finite input and output alphabet channels with a type-dependent metric. The closely related problem of threshold mismatched decoding is also studied, and a general expression for the threshold mismatch capacity is obtained. As an example of threshold mismatch capacity, we state a general expression for the erasures-only capacity of the finite input and output alphabet channel. We observe that for every channel there exists a (matched) threshold decoder which is capacity achieving. Additionally, necessary and sufficient conditions are stated for a channel to have a strong converse. Csisz\'{a}r and Narayan's conjecture is proved for bounded metrics, providing a positive answer to the open problem introduced in [1], i.e., that the "product-space" improvement of the lower random coding bound, $C_q^{(\infty)}(W)$, is indeed the mismatch capacity of the discrete memoryless channel $W$. We conclude by presenting an identity between the threshold capacity and $C_q^{(\infty)}(W)$ in the DMC case.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2013-09-30T19:09:01Z |
1008.1735
|
Development of Powder-in-Tube Processed Iron Pnictide Wires and Tapes
|
The development of the PIT fabrication process of iron pnictide superconducting wires and tapes has been carried out in order to enhance their transport properties. Silver was found to be the best sheath material, since no reaction layer was observed between the silver sheath and the superconducting core. The grain connectivity of iron pnictide wires and tapes has been markedly improved by employing Ag or Pb as dopants. At present, critical current densities in excess of 3750 A/cm^2 (Ic = 37.5 A) at 4.2 K have been achieved on Ag-sheathed SrKFeAs wires prepared with the above techniques, which is the highest in iron-based wires and tapes so far. Moreover, Ag-sheathed Sm-1111 superconducting tapes were successfully prepared by PIT method at temperatures as low as 900C, instead of commonly used temperatures of 1200C. These results demonstrate the feasibility of producing superconducting pnictide composite wires, even grain boundary properties require much more attention.
|
[
"Physics Archive->cond-mat->cond-mat.supr-con"
] | 2010-08-10T15:12:08Z |
1509.02852
|
Efficient particle continuation model predictive control
|
Continuation model predictive control (MPC), introduced by T. Ohtsuka in 2004, uses Krylov-Newton approaches to solve MPC optimization and is suitable for nonlinear and minimum time problems. We suggest particle continuation MPC in the case, where the system dynamics or constraints can discretely change on-line. We propose an algorithm for on-line controller implementation of continuation MPC for ensembles of predictions corresponding to various anticipated changes and demonstrate its numerical effectiveness for a test minimum time problem arriving to a destination. Simultaneous on-line particle computation of ensembles of controls, for several dynamically changing system dynamics, allows choosing the optimal destination on-line and adapt it as needed.
|
[
"Computer Science Archive->cs.SY",
"Mathematics Archive->math.OC"
] | 2015-09-09T17:01:15Z |
cond-mat/0608431
|
Comparison of room-temperature multiferroics in Bi4Fe2TiO12 film and bulk
|
It is reported that both dielectricity and magnetism at room temperature have been appreciably improved in Bi4Fe2TiO12 film compared with that of Bi4Fe2TiO12 bulk. X-ray diffraction profiles reveal similar crystalline nature and random orientation of the two but X-ray photoelectron spectroscopy (XPS) experiments indicate 1.4 eV lower binding energy of core-state O 1s in film relative to those of bulk, so the improvement of multiferroics in film are attributed to the oxygen vacancies and high fraction of interface. The results have promising applications in multifunctional integrated devices.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2006-08-18T17:18:58Z |
0912.1595
|
Polycyclic aromatic hydrocarbon processing in a hot gas
|
Context: PAHs are thought to be a ubiquitous and important dust component of the interstellar medium. However, the effects of their immersion in a hot (post-shock) gas have never before been fully investigated. Aims: We study the effects of energetic ion and electron collisions on PAHs in the hot post-shock gas behind interstellar shock waves. Methods: We calculate the ion-PAH and electron-PAH nuclear and electronic interactions, above the carbon atom loss threshold, in H II regions and in the hot post-shock gas, for temperatures ranging from 10^3 to 10^8 K. Results: PAH destruction is dominated by He collisions at low temperatures (T < 3x10^4 K), and by electron collisions at higher temperatures. Smaller PAHs are destroyed faster for T < 10^6 K, but the destruction rates are roughly the same for all PAHs at higher temperatures. The PAH lifetime in a tenuous hot gas (n_H ~ 0.01 cm^-3, T ~ 10^7 K), typical of the coronal gas in galactic outflows, is found to be about thousand years, orders of magnitude shorter than the typical lifetime of such objects. Conclusions: In a hot gas, PAHs are principally destroyed by electron collisions and not by the absorption of X-ray photons from the hot gas. The resulting erosion of PAHs occurs via C_2 loss from the periphery of the molecule, thus preserving the aromatic structure. The observation of PAH emission from a million degree, or more, gas is only possible if the emitting PAHs are ablated from dense, entrained clumps that have not yet been exposed to the full effect of the hot gas.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.GA"
] | 2009-12-08T21:46:37Z |
1901.00989
|
On the Universality and Extremality of graphs with a distance constrained colouring
|
A lambda colouring (or $L(2,1)-$colouring) of a graph is an assignment of non-negative integers (with minimum assignment $0$) to its vertices such that the adjacent vertices must receive integers at least two apart and vertices at distance two must receive distinct integers. The lambda chromatic number (or the $\lambda$ number) of a graph $G$ is the least positive integer among all the maximum assigned positive integer over all possible lambda colouring of the graph $G$. Here we have primarily shown that every graph with lambda chromatic number $t$ can be embedded in a graph, with lambda chromatic number $t$, which admits a partition of the vertex set into colour classes of equal size. It is further proved that if an $n-$vertex graph with lambda chromatic number $t\geq5$, where $n\geq t+1$, contains maximum number of edges, then the vertex set of such graph admits an equitable partition. For such an admitted equitable partition there are either $0$ or $\min\{|A|,|B|\}$ number of edges between each pair $(A,B)$ of subsets (i.e. roughly, such partition is a "sparse like" equitable partition). Here we establish a classification result, identifying all possible $n-$vertex graphs with lambda chromatic number $t\geq3$, where $n\geq t+1$, which contain maximum number of edges. Such classification provides a solution of a problem posed more than two decades ago by John P. Georges and David W. Mauro.
|
[
"Mathematics Archive->math.CO"
] | 2019-01-04T05:55:58Z |
2307.04259
|
Dynamical Wormhole Solutions in Rastall Theory
|
Wormhole configurations in Einstein's general theory of relativity (GR) require exotic matter sources violating the weak energy condition (WEC). Rastall's theory is a generalization of GR in its matter source considering a nonconserved energy-momentum (EM) tensor. Hence, on one hand, the nature of this generalization of the matter source of field equations and, on the other hand, the possibility of respecting energy conditions for dynamical wormholes in contrast to static ones motivates us to study the possibility of the existence of wormhole configurations respecting energy conditions or minimizing the violations of them in Rastall's modified theory. We derive general analytical solutions considering a constant redshift function and a particular equation of state for energy density and pressure profiles. We show that because of the modification in the EM source of the field equations, there exist solutions respecting the WEC in the vicinity of the wormhole's throat for specified values of the parameters. Some particular solutions are discussed in detail.
|
[
"Physics Archive->gr-qc"
] | 2023-07-09T20:18:58Z |
1604.07605
|
Photoelectron generation and capture in the resonance fluorescence of a quantum dot
|
Time-resolved resonance fluorescence (RF) on a single self-assembled quantum dot (QD) is used to analyze the generation and capture of photoinduced free charge carriers. We directly observe the capture of electrons into the QD in an intensity reduction of the exciton transition. The exciton transition is quenched until the captured electron tunnels out of the dot again in the order of milliseconds. Our results demonstrate that even under resonant excitation, excited, free electrons are generated, which can negatively influence the optical properties of a QD. This detrimental effect has been neglected before for dots that are optimized for maximum efficiency and minimum spectral diffusion.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2016-04-26T10:20:34Z |
1505.06026
|
Counting function of magnetic resonances for exterior problems
|
We study the asymptotic distribution of the resonances near the Landau levels $\Lambda\_q =(2q+1)b$, $q \in \mathbb{N}$, of the Dirichlet (resp. Neumann, resp. Robin) realization in the exterior of a compact domain of $\mathbb{R}^3$ of the 3D Schr{\"o}dinger operator with constant magnetic field of scalar intensity $b\textgreater{}0$. We investigate the corresponding resonance counting function and obtain the main asymptotic term. In particular, we prove the accumulation of resonances at the Landau levels and the existence of resonance free sectors. In some cases, it provides the discreteness of the set of embedded eigenvalues near the Landau levels.
|
[
"Mathematics Archive->math.MP",
"Mathematics Archive->math.SP",
"Physics Archive->math-ph"
] | 2015-05-22T11:07:39Z |
2206.01659
|
Accurate collection of reasons for treatment discontinuation to better define estimands in clinical trials
|
Background: Reasons for treatment discontinuation are important not only to understand the benefit and risk profile of experimental treatments, but also to help choose appropriate strategies to handle intercurrent events in defining estimands. The current case report form (CRF) commonly in use mixes the underlying reasons for treatment discontinuation and who makes the decision for treatment discontinuation, often resulting in an inaccurate collection of reasons for treatment discontinuation. Methods and results: We systematically reviewed and analyzed treatment discontinuation data from nine phase 2 and phase 3 studies for insulin peglispro. A total of 857 participants with treatment discontinuation were included in the analysis. Our review suggested that, due to the vague multiple-choice options for treatment discontinuation present in the CRF, different reasons were sometimes recorded for the same underlying reason for treatment discontinuation. Based on our review and analysis, we suggest an intermediate solution and a more systematic way to improve the current CRF for treatment discontinuations. Conclusion: This research provides insight and directions on how to optimize the CRF for recording treatment discontinuation. Further work needs to be done to build the learning into Clinical Data Interchange Standards Consortium standards.
|
[
"Statistics Archive->stat.AP"
] | 2022-06-03T16:09:38Z |
2305.19116
|
Measurement of the $\tau$-lepton mass with the Belle~II experiment
|
We present a measurement of the $\tau$-lepton mass using a sample of about 175 million $e^+e^- \to \tau^+\tau^-$ events collected with the Belle II detector at the SuperKEKB $e^+e^-$ collider at a center-of-mass energy of $10.579\,\mathrm{Ge\kern -0.1em V}$. This sample corresponds to an integrated luminosity of $190\,\mathrm{fb^{-1}}$. We use the kinematic edge of the $\tau $ pseudomass distribution in the decay ${\tau^-\to\pi^-\pi^+\pi^-\nu_\tau}$ and measure the $\tau$ mass to be $1777.09 \pm 0.08 \pm 0.11 \,\mathrm{Me\kern -0.1em V\!/c^2}$, where the first uncertainty is statistical and the second systematic. This result is the most precise to date.
|
[
"Physics Archive->hep->hep-ex"
] | 2023-05-30T15:24:41Z |
0708.2853
|
Dense sets of integers with prescribed representation functions
|
Let A be a set of integers and let h \geq 2. For every integer n, let r_{A, h}(n) denote the number of representations of n in the form n=a_1+...+a_h, where a_1,...,a_h belong to the set A, and a_1\leq ... \leq a_h. The function r_{A,h} from the integers Z to the nonnegative integers N_0 U {\infty} is called the representation function of order h for the set A. We prove that every function f from Z to N_0 U {\infty} satisfying liminf_{|n|->\infty} f (n)\geq g is the representation function of order h for some sequence A of integers, and that A can be constructed so that it increases "almost" as slowly as any given B_h[g] sequence. In particular, for every epsilon >0 and g \geq g(h,epsilon), we can construct a sequence A satisfying r_{A,h}=f and A(x)\gg x^{(1/h)-epsilon}.
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[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.NT"
] | 2007-08-21T14:38:12Z |
2112.14488
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Random necklaces require fewer cuts
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It is known that any open necklace with beads of $t$ types in which the number of beads of each type is divisible by $k$, can be partitioned by at most $(k-1)t$ cuts into intervals that can be distributed into $k$ collections, each containing the same number of beads of each type. This is tight for all values of $k$ and $t$. Here, we consider the case of random necklaces, where the number of beads of each type is $km$. Then the minimum number of cuts required for a ``fair'' partition with the above property is a random variable $X(k,t,m)$. We prove that for fixed $k,t,$ and large $m$, this random variable is at least $(k-1)(t+1)/2$ with high probability. For $k=2$, fixed $t$, and large $m$, we determine the asymptotic behavior of the probability that $X(2,t,m)=s$ for all values of $s\le t $. We show that this probability is polynomially small when $s<(t+1)/2$, it is bounded away from zero when $s>(t+1)/2$, and decays like $\Theta ( 1/\log m)$ when $s=(t+1)/2$. We also show that for large $t$, $X(2,t,1)$ is at most $(0.4+o(1))t$ with high probability and that for large $t$ and large ratio $k/\log t$, $X(k,t,1)$ is $o(kt)$ with high probability.
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[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.PR"
] | 2021-12-29T10:23:17Z |
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