cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Blind Deconvolution with Non-smooth Regularization via Bregman Proximal DCAs
Creators: name: Takahashi, Shota
name: Tanaka, Mirai
name: Ikeda, Shiro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optimization and Control (math.OC)
subject: Signal Processing (eess.SP)
subject: FOS: Mathematics
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Blind deconvolution is a technique to recover an original signal without knowing a convolving filter. It is naturally formulated as a minimization of a quartic objective function under some assumption. Because its differentiable part does not have a Lipschitz continuous gradient, existing first-order methods are not theoretically supported. In this paper, we employ the Bregman-based proximal methods, whose convergence is theoretically guaranteed under the $L$-smooth adaptable ($L$-smad) property. We first reformulate the objective function as a difference of convex (DC) functions and apply the Bregman proximal DC algorithm (BPDCA). This DC decomposition satisfies the $L$-smad property. The method is extended to the BPDCA with extrapolation (BPDCAe) for faster convergence. When our regularizer has a sufficiently simple structure, each iteration is solved in a closed-form expression, and thus our algorithms solve large-scale problems efficiently. We also provide the stability analysis of the equilibrium and demonstrate the proposed methods through numerical experiments on image deblurring. The results show that BPDCAe successfully recovered the original image and outperformed other existing algorithms.
Noncommutative Reissner-Nordstrøm Black hole
Creators: name: Soto-Campos, Carlos A.
name: Valdez-Alvarado, Susana
Publisher: name: arXiv
Year: 2015
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: A deformed embedding of the Reissner-Nordstrøm spacetime is constructed within the framework of a noncommutative Riemannian geometry. We find noncommutative corrections to the usual Riemannian expressions for the metric and curvature tensors, which, in the case of the metric, are valid to all orders in the deformation parameter. We calculate the area of the event horizon of the corresponding noncommutative R-N black-hole, obtaining corrections up to fourth order in the deformation parameter for the area of the black-hole. Finally we include some comments on the noncommutative version on one of the second order scalar invariants of the Riemann tensor, the so called Kretschmann invariant, a quantity regularly used in order to extend gravity to quantum level.
description: 7 page
VarGrad: A Low-Variance Gradient Estimator for Variational Inference
Creators: name: Richter, Lorenz
name: Boustati, Ayman
name: Nüsken, Nikolas
name: Ruiz, Francisco J. R.
name: Akyildiz, Ömer Deniz
Publisher: name: Freie Universität Berlin
Year: 2020
Subjects: subject: VarGrad
subject: Neural Information Processing Systems
subject: Low-Variance Gradient Estimator
subject: 500 Naturwissenschaften und Mathematik::510 Mathematik::510 Mathematik

description: We analyse the properties of an unbiased gradient estimator of the evidence lower bound (ELBO) for variational inference, based on the score function method with leave-one-out control variates. We show that this gradient estimator can be obtained using a new loss, defined as the variance of the log-ratio between the exact posterior and the variational approximation, which we call the log-variance loss. Under certain conditions, the gradient of the log-variance loss equals the gradient of the (negative) ELBO. We show theoretically that this gradient estimator, which we call VarGrad due to its connection to the log-variance loss, exhibits lower variance than the score function method in certain settings, and that the leave-one-out control variate coefficients are close to the optimal ones. We empirically demonstrate that VarGrad offers a favourable variance versus computation trade-off compared to other state-of-the-art estimators on a discrete variational autoencoder (VAE)
AI-READI Steering Committee Charter
Creators: name: Lee, Aaron
name: Owen, Julia
name: Patel, Bhavesh
name: Nebeker, Camille
name: Lee, Cecilia
name: Zangwill, Linda
name: Hurst, Samm
name: Singer, Sara
Publisher: name: Zenodo
Year: 2023
Subjects: Responsibility
Meetings
Membership
Voting

description: This is the Steering Committee Charter of AI-READI, a data generation project of the NIH-funded Bridge2AI program
description: The AI-READI project is supported by the NIH-funded Bridge2AI program (1OT2OD032644)
Forward hadron production in ultraperipheral proton-heavy-ion collisions at the LHC and RHIC
Creators: name: Mitsuka, Gaku
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We discuss hadron production in the forward rapidity region in ultraperipheral proton-lead collisions at the LHC and proton-gold collisions at RHIC. Our discussion is based on the Monte Carlo simulations of the interactions of virtual photons emitted by a fast moving nucleus with a proton beam. We simulate the virtual photon flux with the STARLIGHT event generator and then particle production with the SOPHIA, DPMJET, and PYTHIA event generators. We show the rapidity distributions of charged and neutral particles, and the momentum distributions of neutral pions and neutrons at forward rapidities. According to the Monte Carlo simulations, we find large cross sections of ultraperipheral collisions for particle production especially in the very forward region, leading to substantial background contributions to investigations of collective nuclear effects and spin physics. Finally we can distinguish between proton-nucleus inelastic interactions and ultraperipheral collisions with additional requirements of either of the charged particles at midrapidity and a certain level of activities at negative forward rapidity.
description: 9 pages, 4 figures, 2 table
Dissipative Dark Matter and the Andromeda Plane of Satellites
Creators: name: Randall, Lisa
name: Scholtz, Jakub
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We show that dissipative dark matter can potentially explain the large observed mass to light ratio of the dwarf satellite galaxies that have been observed in the recently identified planar structure around Andromeda, which are thought to result from tidal forces during a galaxy merger. Whereas dwarf galaxies created from ordinary disks would be dark matter poor, dark matter inside the galactic plane not only provides a source of dark matter, but one that is more readily bound due to the dark matter's lower velocity. This initial N-body study shows that with a thin disk of dark matter inside the baryonic disk, mass-to-light ratios as high as O(30) can be generated when tidal forces pull out patches of sizes similar to the scales of Toomre instabilities of the dark disk. A full simulation will be needed to confirm this result.
description: 13 pages, 12 figures
Geometric Biases in Power-Spectrum Measurements
Creators: name: Samushia, Lado
name: Branchini, Enzo
name: Percival, Will
Publisher: name: arXiv
Year: 2015
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The observed distribution of galaxies has local transverse isotropy around the line-of- sight (LOS) with respect to the observer. The difference in the statistical clustering signal along and across the line-of-sight encodes important information about the ge- ometry of the Universe, its expansion rate and the rate of growth of structure within it. Because the LOS varies across a survey, the standard Fast Fourier Transform (FFT) based methods of measuring the Anisotropic Power-Spectrum (APS) cannot be used for surveys with wide observational footprint, other than to measure the monopole moment. We derive a simple analytic formula to quantify the bias for higher-order Legendre moments and we demonstrate that it is scale independent for a simple sur- vey model, and depends only on the observed area. We derive a similar numerical correction formula for recently proposed alternative estimators of the APS that are based on summing over galaxies rather than using an FFT, and can therefore in- corporate a varying LOS. We demonstrate that their bias depends on scale but not on the observed area. For a quadrupole the bias is always less than 1 per cent for k > 0.01h/Mpc at z > 0.32. For a hexadecapole the bias is below 5 per cent for k>0.05h/Mpc at z>0.32.
description: 6 pages, 3 figures. Minor revisions to match published version
Development of a Rapid Fast Neutron Activation Analysis Method for the Determination of Nitrogen in Food Products
Creators: name: Ahafia, Albert Komi
Publisher: name: London South Bank University
Year: 1978

description: A fast neutron activation analysis method, developed for rapid (9 min) determination of nitrogen in the presence of phosphorus, is described. The results obtained by applying the method to nitrogen determination in some flour samples are presented and compared with those given by the Kjeldahl method. Also indicated are possible applications of the method and the overall value of the investigation. The basis of the method is the count ratio technique employed in this investigation for the resolution of two-component annihilation spectra. The irradiated mixture is counted over two separate time intervals, using two scalers and three timers. The ratio of the contributions from each component to the composite annihilation peak is then calculated from a set of two linear equations. A plot of the count ratios against the corresponding mass ratios yields a novel calibration procedure. By adding an additional known amount of one of the elements as an internal standard, it is possible to determine the amounts of both elements in the sample. The experimental procedures designed to achieve the rapid analysis are fully described. Also fully reported are investigations of the count ratio technique and the recoil proton effect which are likely to affect the performance of the new method. The method gave results accurate to within 1 % of the Kjeldahl value. Above 5% nitrogen concentration, the experimental relative standard deviation was ca. 3%. Though the analysis time achieved is 9 mins, the method can easily complete the analysis in 5 minutes if the neutron flux and the nitrogen concentration are high enough. The study of the count ratio technique has shown that the count ratio does not change significantly when the neutron flux changes with time during the irradiation. This is true whether the two half-lives are close or not. In the study of the recoil proton effect, it has been shown both theoretically and experimentally that the recoil proton reaction yield varies as the square of the mass irradiated and that, for a given matrix, there exists a definite hydrogen/carbon ratio that makes the yield a maximum. The count ratio technique, as developed in this study, could also be used to compare nuclear cross sections. In short, the results of the research show a clear shortening of the current analysis time. They have also thrown some light on the effectiveness of the count ratio technique and taken our understanding of the recoil proton effect one step further.
Irreducible representations of $\mathbb{Z}_2^2$-graded ${\cal N} =2$ supersymmetry algebra and $\mathbb{Z}_2^2$-graded supermechanics
Creators: name: Aizawa, N.
name: Doi, S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Irreducible representations (irreps) of $\mathbb{Z}_2^2$-graded supersymmetry algebra of ${\cal N}=2$ are obtained by the method of induced representation and they are used to derive $\mathbb{Z}_2^2$-graded supersymmetric classical actions. The irreps are four dimensional for $ λ= 0$ where $ λ$ is an eigenvalue of the Casimir element, and eight dimensional for $λ\neq 0.$ The eight dimensional irreps reduce to four dimensional ones only when $λ$ and an eigenvalue of Hamiltonian satisfy a particular relation. The reduced four dimensional irreps are used to define $\mathbb{Z}_2^2$-graded supersymmetry transformations and two types of classical actions invariant under the transformations are presented. It is shown that one of the Noether charges vanishes if all the variables of specific $\mathbb{Z}_2^2$-degree are auxiliary.
description: 17 pages, no figures
Andreev bound states in junctions formed by conventional and $\mathcal{PT}$-symmetric non-Hermitian superconductors
Creators: name: Kornich, Viktoriia
name: Trauzettel, Björn
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study theoretically a junction of a $\mathcal{PT}$-symmetric non-Hermitian superconductor (PTS) placed between two conventional superconductors. We show that due to non-Hermitian electron-electron interaction in the PTS region and the combination of symmetries, only discrete values of phases of the conventional superconductors yield solutions for Andreev bound states. Remarkably, in the case of $0$ and $π$, we obtain growing and decaying in time Andreev bound states. For $π/2$ and $3π/2$, there is a Majorana zero mode penetrating through the junction in only one direction forming a quasiparticle supercurrent.
A Fingerprint-based Access Control using Principal Component Analysis and Edge Detection
Creators: name: Melo, E. F.
name: de Oliveira, H. M.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Cryptography and Security (cs.CR)
subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: This paper presents a novel approach for deciding on the appropriateness or not of an acquired fingerprint image into a given database. The process begins with the assembly of a training base in an image space constructed by combining Principal Component Analysis (PCA) and edge detection. Then, the parameter H, a new feature that helps in the decision making about the relevance of a fingerprint image in databases, is derived from a relationship between Euclidean and Mahalanobian distances. This procedure ends with the lifting of the curve of the Receiver Operating Characteristic (ROC), where the thresholds defined on the parameter H are chosen according to the acceptable rates of false positives and false negatives.
description: 5 pages, 9 figures. SBrT/IEEE International Telecommunication Symposium, ITS 2010, Manaus, AM, Brazil
Methods;Figure S1;Figure S2;Figure S3;Figure S4 from Extremely low seasonal prey capture efficiency in a deep-diving whale, the narwhal
Creators: name: Chambault, Philippine
name: Blackwell, Susanna B.
name: Heide-Jørgensen, Mads Peter
Publisher: name: The Royal Society
Year: 2023
Subjects: subject: Ecology
subject: FOS: Biological sciences
subject: 60801 Animal Behaviour

description: Example of the spectrogram and waveform showing the clicks and STP pulses for Eistla on 08-25-2016. The inter-pulse intervals were used to encode the stomach temperature from the Acousonde.;Histograms of the whale depth at the onset of temperature drops for (a) the four narwhals equipped only with an STP tag and (b) the three narwhals equipped with both an STP tag and an Acousonde. The duration of the tracking and the total number of drops recorded are indicated in each panel individually. The horizontal red lines refer to the mean drop depth for each individual.;Individual histograms of the ST drop amplitude (a, c) and recovery time (b, d) for each type of tag. Note the differences in the ranges of the x axes. It is worth noting that in panel (d), recovery times exceeding 60 min might not be biologically relevant but were due to data gaps from the satellite transmitter, precluding the proper identification of the end of the feeding event.;(a) Number of daily ST drops (prey capture events) per individual and (b) average number of daily buzzes and ST drops for the three whales equipped with both an STP tag and an Acousonde. The numbers on the top of each bar refer to the values of ST drops or buzzes per day.
Cosmological Bound on the QCD Axion Mass, Redux
Creators: name: D'Eramo, Francesco
name: Di Valentino, Eleonora
name: Giarè, William
name: Hajkarim, Fazlollah
name: Melchiorri, Alessandro
name: Mena, Olga
name: Renzi, Fabrizio
name: Yun, Seokhoon
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We revisit the joint constraints in the mixed hot dark matter scenario in which both thermally produced QCD axions and relic neutrinos are present. Upon recomputing the cosmological axion abundance via recent advances in the literature, we improve the state-of-the-art analyses and provide updated bounds on axion and neutrino masses. By avoiding approximate methods, such as the instantaneous decoupling approximation, and limitations due to the limited validity of the perturbative approach in QCD that forced to artificially divide the constraints from the axion-pion and the axion-gluon production channels, we find robust and self-consistent limits. We investigate the two most popular axion frameworks: KSVZ and DFSZ. From Big Bang Nucleosynthesis (BBN) light element abundances data we find for the KSVZ axion $ΔN_{\rm eff}<0.31$ and an axion mass bound $m_a < 0.53 $ eV (i.e., a bound on the axion decay constant $f_a > 1.07 \times 10^7$ GeV) both at $95\%$ CL. These BBN bounds are improved to $ΔN_{\rm eff}<0.14$ and $m_a< 0.16$ eV ($f_a > 3.56 \times 10^7$ GeV) if a prior on the baryon energy density from Cosmic Microwave Background (CMB) data is assumed. When instead considering cosmological observations from the CMB temperature, polarization and lensing from the Planck satellite combined with large scale structure data we find $ΔN_{\rm eff}<0.23$, $m_a< 0.28$ eV ($f_a > 2.02 \times 10^7$ GeV) and $\sum m_ν< 0.16$ eV at $95\%$ CL. This corresponds approximately to a factor of $5$ improvement in the axion mass bound with respect to the existing limits. Very similar results are obtained for the DFSZ axion. We also forecast upcoming observations from future CMB and galaxy surveys, showing that they could reach percent level errors for $m_a\sim 1$ eV.
description: 22 pages, 9 figures, 5 tables. V2: updated to match the JCAP published version
Linear Sigma Dark Matter
Creators: name: Kondo, Dan
name: McGehee, Robert
name: Melia, Tom
name: Murayama, Hitoshi
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present a model of self-interacting dark matter based on QCD-like theories and inspired by the proximity of $a_0(980\pm 20)$ to the $K\bar{K}(990)$ threshold. Dark matter is comprised of dark pions which self-scatter via the $σ$ resonance close to the $ππ$ threshold. While the linear sigma model serves as a qualitative guide, a fully unitary description of the scattering in the strongly coupled regime is given by effective range theory. The introduction of a kinetically mixed dark photon allows the dark pion to either freeze-out or -in. We study the viable parameter space which explains the observed relic abundance while evading all current constraints. Searches for dark matter self interactions at different scales, (in)direct detection signals, and (in)visibly-decaying dark photons will test this model in the near future.
description: 30 pages, 13 figures; v2: minor revisions to match published version
On Gröbner bases and Cohen-Macaulay property of closed path polyominoes
Creators: name: Cisto, Carmelo
name: Navarra, Francesco
name: Utano, Rosanna
Publisher: name: arXiv
Year: 2022
Subjects: subject: Commutative Algebra (math.AC)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05B50, 05E40, 13C05, 13G05, 13C14

description: In this paper we introduce some monomial orders for the class of closed path polyominoes and we prove that the set of the generators of the polyomino ideal attached to a closed path forms the reduced Gröbner basis with respect to these monomial orders. It is known that the polyomino ideal attached to a closed path containing an L-configuration or a ladder of at least three steps, equivalently having no zig-zag walks, is prime. As a consequence, we obtain that the coordinate ring of a closed path having no zig-zag walks is a normal Cohen-Macaulay domain.
description: 18 pages, 20 figures
Approximation and estimation of very small probabilities of multivariate extreme events
Creators: name: de Valk, Cees
Publisher: name: arXiv
Year: 2015
Subjects: subject: Statistics Theory (math.ST)
subject: FOS: Mathematics
subject: 60G70 (Primary), 60F10, 62G32 (Secondary)

description: This article discusses modelling of the tail of a multivariate distribution function by means of a large deviation principle (LDP), and its application to the estimation of the probability of a multivariate extreme event from a sample of n iid random vectors, with the probability bounded by powers of sample size with exponents below -1. One way to view classical tail limits is as limits of probability ratios. In contrast, the tail LDP provides asymptotic bounds or limits for log-probability ratios. After standardising the marginals to standard exponential, dependence is represented by a homogeneous rate function. Furthermore, the tail LDP can be extended to represent both dependence and marginals, the latter implying marginal log-GW tail limits. A connection is established between the tail LDP and residual tail dependence (or hidden regular variation) and a recent extension of it. Under a smoothness assumption, they are implied by the tail LDP. Based on the tail LDP, a simple estimator for very small probabilities of extreme events is formulated. It avoids estimation of the rate function by making use of its homogeneity. Strong consistency in the sense of convergence of log-probability ratios is proven. Simulations and an application illustrate the difference between the classical approach and the LDP-based approach.
Sulfurization of Iron in the Dynamic Solar Nebula and Implications for Planetary Compositions
Creators: name: Ciesla, Fred J.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: One explanation for the enhanced ratio of volatiles to hydrogen in Jupiter's atmosphere compared to a a gas of solar composition is that the planet accreted volatile-bearing clathrates during its formation. Models, however, suggest that S would be over abundant if clathrates were the primary carrier of Jupiter's volatiles. This led to the suggestion that S was depleted in the outer nebula due to the formation troilite (FeS). Here, this depletion is quantitatively explored by modeling the coupled dynamical and chemical evolution of Fe grains in the solar nebula. It is found that disks that undergo rapid radial expansion from an initially compact state may allow sufficient production of FeS and carry H$_{2}$S-depleted gas outward where ices would form, providing the conditions needed for S-depleted clathrates to form. However, this expansion would also carry FeS grains to this region, which could also be incorporated into planetesimals. Thus for clathrates to be a viable source of volatiles, models must account for the presence of both H$_{2}$S in FeS in the outer solar nebula.
description: 5 pages, 1 figure; Accepted to ApJ Letters
Boundaries control active channel flows
Creators: name: Gulati, Paarth
name: Shankar, Suraj
name: Marchetti, M. Cristina
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: Boundary conditions dictate how fluids, including liquid crystals, flow when pumped through a channel. Can boundary conditions also be used to control internally driven active fluids that generate flows spontaneously? By using numerical simulations and stability analysis we explore how surface anchoring of active agents at the boundaries and substrate drag can be used to rectify coherent flow of an active polar fluid in a 2D channel. Upon increasing activity, a succession of dynamical states is obtained, from laminar flow to vortex arrays to eventual turbulence, that are controlled by the interplay between the hydrodynamic screening length and the extrapolation length quantifying the anchoring strength of the orientational order parameter. We highlight the key role of symmetry in both flow and order and show that coherent laminar flow with net throughput is only possible for weak anchoring and intermediate activity. Our work demonstrates the possibility of controlling the nature and properties of active flows in a channel simply by patterning the confining boundaries.
description: 12 pages, 9 figures
การประเมินโครงการแลกเปลี่ยนเรียนรู้ด้านสังคมพหุวัฒนธรรม ล้านนา-รัตนโกสินทร์
Creators: name: จิระศักดิ์ สาระรัตน์
Publisher: name: ศูนย์สนับสนุนและพัฒนาการเรียนการสอน มหาวิทยาลัยรังสิต
Year: 2014
Subjects: Evaluation
Knowledge Sharing
Multiculture
การประเมิน
การแลกเปลี่ยนเรียนรู้
พหุวัฒนธรรม

description: วารสารพัฒนาการเรียนการสอน, 8, 1, 25-36
สุขภาวะทางจิตวิญญาณนักศึกษามหาวิทยาลัยรังสิต : กรณีศึกษาคณะกายภาพบำบัด
Creators: name: พรพิมล จันทรวิโรจน์
Publisher: name: ศูนย์สนับสนุนและพัฒนาการเรียนการสอน มหาวิทยาลัยรังสิต
Year: 2014
Subjects: Academic Performance
Faculty of physical therapy
Spiritual Well-Being
Student
คณะกายภาพบำบัด
นักศึกษา
ผลการเรียน

description: วารสารพัฒนาการเรียนการสอน, 8, 1, 37-50
The local symbol complex of a Reciprocity Functor
Creators: name: Gazaki, Evangelia
Publisher: name: arXiv
Year: 2015
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: For a reciprocity functor $\mathcal{M}$ we consider the local symbol complex $\mathcal{M}\otimes^{M}\mathbb{G}_{m}(η_{C})\to\oplus_{P\in C}\mathcal{M}(k)\to\mathcal{M}(k)$, where $C$ is a smooth complete curve over an algebraically closed field $k$ with generic point $η_{C}$ and $\otimes^{M}$ is the product of Mackey functors. We prove that if $\mathcal{M}$ satisfies certain conditions, then the homology of the above complex is isomorphic to the $K$-group of reciprocity functors $T(\mathcal{M},\underline{CH}_{0}(C)^{0})(Spec k)$.
description: 17 pages
Optical Conductivity of the two dimensional Hubbard model: vertex corrections, emergent Galilean invariance and the accuracy of the single-site dynamical mean field approximation
Creators: name: Mu, Anqi
name: Sun, Zhiyuan
name: Millis, Andrew J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We compute the frequency dependent conductivity of the two dimensional square lattice Hubbard model at zero temperature as a function of density to second order in the interaction strength, and compare the results to the predictions of single-site dynamical mean field theory computed at the same order. We find that despite the neglect of vertex corrections, the single site dynamical mean field approximation produces semiquantitatively accurate results for most carrier concentrations, but fails qualitatively for the nearly empty or nearly filled band cases where the theory exhibits an emergent Galilean invariance. The theory also becomes qualitatively inaccurate very near half filling if nesting is important.
description: 12 pages, 6 figures
Magnetic warping in topological insulators
Creators: name: Naselli, Gabriele
name: Moghaddam, Ali G.
name: Di Napoli, Solange
name: Vildosola, Veronica
name: Fulga, Ion Cosma
name: Brink, Jeroen van den
name: Facio, Jorge I.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We analyze the electronic structure of topological surface states in the family of magnetic topological insulators MnBi$_{2n}$Te$_{3n+1}$. We show that, at natural-cleavage surfaces, the Dirac cone warping changes its symmetry from hexagonal to trigonal at the magnetic ordering temperature. In particular, an energy splitting develops between the surface states of same band index but opposite surface momenta upon formation of the long-range magnetic order. As a consequence, measurements of such energy splittings constitute a simple protocol to detect the magnetic ordering via the surface electronic structure, alternative to the detection of the surface magnetic gap. Interestingly, while the latter signals a nonzero surface magnetic flux, the trigonal warping predicted here is, in addition, sensitive to the direction of the surface magnetic flux.
ผลสัมฤทธิ์ทางการเรียนของนักศึกษา รายวิชา FIN 201 การเงินธุรกิจ
Creators: name: มุกดา โควหกุล
Publisher: name: ศูนย์สนับสนุนและพัฒนาการเรียนการสอน มหาวิทยาลัยรังสิต
Year: 2014
Subjects: Demographic Factors
Learning Achievement
Learning Management
การจัดการเรียนการสอน
ปัจจัยส่วนบุคคล
ผลสัมฤทธิ์ทางการเรียน

description: วารสารพัฒนาการเรียนการสอน, 8, 1, 51-68
A Novel, Fully Automated Pipeline for Period Estimation in the EROS 2 Data Set
Creators: name: Protopapas, Pavlos
name: Huijse, Pablo
name: Estevez, Pablo A.
name: Zegers, Pablo
name: Principe, Jose C.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Information Theory (cs.IT)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: We present a new method to discriminate periodic from non-periodic irregularly sampled lightcurves. We introduce a periodic kernel and maximize a similarity measure derived from information theory to estimate the periods and a discriminator factor. We tested the method on a dataset containing 100,000 synthetic periodic and non-periodic lightcurves with various periods, amplitudes and shapes generated using a multivariate generative model. We correctly identified periodic and non-periodic lightcurves with a completeness of 90% and a precision of 95%, for lightcurves with a signal-to-noise ratio (SNR) larger than 0.5. We characterize the efficiency and reliability of the model using these synthetic lightcurves and applied the method on the EROS-2 dataset. A crucial consideration is the speed at which the method can be executed. Using hierarchical search and some simplification on the parameter search we were able to analyze 32.8 million lightcurves in 18 hours on a cluster of GPGPUs. Using the sensitivity analysis on the synthetic dataset, we infer that 0.42% in the LMC and 0.61% in the SMC of the sources show periodic behavior. The training set, the catalogs and source code are all available in http://timemachine.iic.harvard.edu.
An efficient explicit jump HOC immersed interface approach for transient incompressible viscous flows
Creators: name: Singhal, Raghav
name: Kalita, Jiten C
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: In the present work, we propose a novel hybrid explicit jump immersed interface approach in conjunction with a higher order compact (HOC) scheme for simulating transient complex flows governed by the streamfunction-vorticity ($ψ$-$ζ$) formulation of the Navier-Stokes (N-S) equations for incompressible viscous flows. A new strategy has been adopted for the jump conditions at the irregular points across the interface using Lagrangian interpolation on a Cartesian grid. This approach, which starts with the discretization of parabolic equations with discontinuities in the solutions, source terms and the coefficients across the interface, can easily be accommodated into simulating flow past bluff bodies immersed in the flow. The superiority of the approach is reflected by the reduced magnitude and faster decay of the errors in comparison to other existing methods. It is seen to handle several fluid flow problems having practical implications in the real world very efficiently, which involves flows involving multiple and moving bodies. This includes the flow past a stationary circular and a twenty-four edge cactus cylinder, flows past two tandem cylinders, where in one situation both are fixed and in another, one of them is oscillating transversely with variable amplitude in time. To the best of our knowledge, the last two examples have been tackled for the first time by such an approach employing the $ψ$-$ζ$ formulation in finite difference set-up. The extreme closeness of our computed solutions with the existing numerical and experimental results exemplifies the accuracy and the robustness of the proposed approach.
Scattering of matter-waves in spatially inhomogeneous environments
Creators: name: Tsitoura, F.
name: Krüger, P.
name: Kevrekidis, P. G.
name: Frantzeskakis, D. J.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We study scattering of quasi one-dimensional matter-waves at an interface of two spatial domains, one with repulsive and one with attractive interatomic interactions. It is shown that the incidence of a Gaussian wavepacket from the repulsive to the attractive region gives rise to generation of a soliton train. More specifically, the number of emergent solitons can be controlled e.g. by the variation of the amplitude or the width of the incoming wavepacket. Furthermore, we study the reflectivity of a soliton incident from the attractive region to the repulsive one. We find the reflection coefficient numerically and employ analytical methods, that treat the soliton as a particle (for moderate and large amplitudes) or a quasi-linear wavepacket (for small amplitudes), to determine the critical soliton momentum - as function of the soliton amplitude - for which total reflection is observed.
description: 8 pages, 7 figures
Response of a baryon-charged medium to energetic partons
Creators: name: Du, Lipei
name: Heinz, Ulrich
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We explore the response to energetic partons of a baryon-charged medium produced in low energy heavy-ion collisions in which the partonic energy loss rate is expected to depend on both temperature and baryon chemical potential. The energy and momentum deposited by the partons are described by dynamical sources added to hydrodynamic equations of motion. We study the distortions of various hydrodynamic quantities, especially the energy and baryon densities, induced by energetic partons plowing through the medium. By studying the contribution from this medium response to the emission spectra of several identified hadron species we identify qualitative differences between the jet-induced modifications for mesons and net protons.
description: v3: title changed, published on PRC
Degeneracy Engineering for Classical and Quantum Annealing: A Case Study of Sparse Linear Regression in Collider Physics
Creators: name: Anschuetz, Eric R.
name: Funcke, Lena
name: Komiske, Patrick T.
name: Kryhin, Serhii
name: Thaler, Jesse
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Classical and quantum annealing are computing paradigms that have been proposed to solve a wide range of optimization problems. In this paper, we aim to enhance the performance of annealing algorithms by introducing the technique of degeneracy engineering, through which the relative degeneracy of the ground state is increased by modifying a subset of terms in the objective Hamiltonian. We illustrate this novel approach by applying it to the example of $\ell_0$-norm regularization for sparse linear regression, which is in general an NP-hard optimization problem. Specifically, we show how to cast $\ell_0$-norm regularization as a quadratic unconstrained binary optimization (QUBO) problem, suitable for implementation on annealing platforms. As a case study, we apply this QUBO formulation to energy flow polynomials in high-energy collider physics, finding that degeneracy engineering substantially improves the annealing performance. Our results motivate the application of degeneracy engineering to a variety of regularized optimization problems.
description: 22 pages, 7 figures, 1 table, v2: updated to match journal version
Black holes in anti-de Sitter: quasinormal modes, tails and tales of flat spacetime
Creators: name: Cardoso, Vitor
name: Khanna, Gaurav
Publisher: name: arXiv
Year: 2015
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Black holes in asymptotically anti-de Sitter (AdS) spacetimes have been the subject of intense scrutiny, including detailed frequency-domain analysis and full nonlinear evolutions. Remarkably, studies of linearized perturbations in the time-domain are scarce or non-existing. We close this gap by evolving linearized scalar wavepackets in the background of rotating BHs in AdS spacetimes. Our results show a number of interesting features. Small BHs in AdS behave as asymptotically flat BHs for early/intermediate times, displaying the same ringdown modes and power-law tails. As the field bounces back and forth between the horizon and the timelike boundary it "thermalizes" and the modes of AdS settle in. Finally, we have indications that wavepackets in the vicinity of fastly spinning BHs grow exponentially in time, signalling a superradiant instability of the geometry previously reported through a frequency-domain analysis.
description: 6 pages, RevTex4. Accepted for publication in Physical Review D. v2: References added
Supplementary material – Table S1 from Whole-body variational modularity in the zebrafish: an inside-out story of a model species
Creators: name: Vanhaesebroucke, Olivia
name: Larouche, Olivier
name: Cloutier, Richard
Publisher: name: The Royal Society
Year: 2023
Subjects: subject: Evolutionary Biology
subject: FOS: Biological sciences

description: Description of the cranial and postcranial landmarks
Supplementary material – Table S3 from Whole-body variational modularity in the zebrafish: an inside-out story of a model species
Creators: name: Vanhaesebroucke, Olivia
name: Larouche, Olivier
name: Cloutier, Richard
Publisher: name: The Royal Society
Year: 2023
Subjects: subject: Evolutionary Biology
subject: FOS: Biological sciences

description: Description of the seven modularity hypotheses
title: Central airway obstruction treatment with self-expanding covered Y-carina nitinol stents: A single center retrospective analysis
Creators: name: Schulze, Arik Bernard
name: Evers, Georg Heribert
name: Tenk, Friederike Sophia
name: Schliemann, Christoph
name: Schmidt, Lars Henning
name: Görlich, Dennis
name: Mohr, Michael
Publisher: name: University of Muenster, Institutional Repository MIAMI
Year: 2023
Subjects: subject: 610 Medicine and health

description: Background: Central airway obstruction (CAO) is one of the most challenging, potentially lethal complications in malignant and benign respiratory diseases. Worsening dyspnea is also a relevant cause for reduced quality of life in such patients. Here, we present our data on the application of covered, self-expanding Y-carina nitinol stents due to benign and malignant diseases. Methods: We retrospectively identified 27 patients who had undergone 31 rigid bronchoscopies with implantation of covered Y-carina nitinol stents over a period of 10 years in order to evaluate indication, clinical course, and outcome. Results: Short-term survival of successfully stented patients with palliative and curative treatment goal did not differ, allowing for diagnosis independent indication. With respect to overall survival, patients with endoluminal obstruction benefited most compared to patients with fistula and/or external compression. Granulation tissue formation (61.3%) and mucus plugging (80.6%) were the most frequent complications. Material defect (6.5%) and migration (3.2%) were rare complications that could be handled by revisional rigid bronchoscopy and stent exchange in some cases. Conclusions: Implantation of self-expanding covered Y-carina nitinol stents via rigid bronchoscopy is a feasible and safe treatment option for benign and malignant central airway obstruction. Especially in palliative, malignant airway stenosis, stenting might facilitate additional treatment options and optimize dyspnea and eventually quality of life.
description: Finanziert über die DEAL-Vereinbarung mit Wiley 2019-2022.
Microwave magnetoelectric fields: An analytical study of topological characteristics
Creators: name: Joffe, R.
name: Shavit, R.
name: Kamenetskii, E. O.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Optics (physics.optics)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The near fields originated from a small quasi-two-dimensional ferrite disk with magnetic-dipolar-mode (MDM) oscillations are the fields with broken dual (electric-magnetic) symmetry. Numerical studies show that such fields, called the magnetoelectric (ME) fields, are distinguished by the power-flow vortices and helicity parameters [E. O. Kamenetskii, R. Joffe, and R. Shavit, Phys. Rev. E 87, 023201 (2013)]. These numerical studies can well explain recent experimental results with MDM ferrite disks. In the present paper, we obtain analytically topological characteristics of the ME-field modes. For this purpose, we use a method of successive approximations. In the second approximation we take into account the influence of the edge regions of an open ferrite disk, which are excluded in the first-approximation solving of the magnetostatic (MS) spectral problem. Based on the analytical method, we obtain a 'pure' structure of the electric and magnetic fields outside the MDM ferrite disk. The analytical studies can display some fundamental features that are non-observable in the numerical results. While in numerical investigations, one cannot separate the ME fields from the external electromagnetic (EM) radiation, the present theoretical analysis allows clearly distinguish the eigen topological structure of the ME fields. Importantly, this ME-field structure gives evidence for certain phenomena that can be related to the Tellegen and bianisotropic coupling effects. We discuss the question whether the MDM ferrite disk can exhibit properties of the cross magnetoelectric polarizabilities.
description: arXiv admin note: text overlap with arXiv:1502.00220
Covariant entanglement wedge cross-section, balanced partial entanglement and gravitational anomalies
Creators: name: Wen, Qiang
name: Zhong, Haocheng
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The balanced partial entanglement (BPE) was observed to give the reflected entropy and the entanglement wedge cross-section (EWCS) for various mixed states in different theories \cite{Wen:2021qgx,Camargo:2022mme}. It can be calculated in different purifications, and is conjectured to be independent from purifications. In this paper we calculate the BPE and the EWCS in generic covariant scenarios in two-dimensional CFTs with and without gravitational anomalies, and find that they coincide with the reflected entropy. In covariant configurations we determine the partition for the purifying system with the help of the gravitational anomalies, and we extend our discussion to topological massive gravity (TMG). We give the first prescription to evaluate the entropy quantity associated to the EWCS beyond Einstein gravity, i.e. the correction to the EWCS from the Chern-Simons term in TMG. Apart from the gravity theory and geometry, further input from the mixed state should be taken into account.
description: 37 pages, 8 figures; v2: references updated, a few typos fixed, more calculation details added; v3: Matched with the published version
Improving cosmological covariance matrices with machine learning
Creators: name: de Santi, Natalí S. M.
name: Abramo, L. Raul
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Cosmological covariance matrices are fundamental for parameter inference, since they are responsible for propagating uncertainties from the data down to the model parameters. However, when data vectors are large, in order to estimate accurate and precise matrices we need huge numbers of observations, or rather costly simulations - neither of which may be viable. In this work we propose a machine learning approach to alleviate this problem in the context of the matrices used in the study of large-scale structure. With only a small amount of data (matrices built with samples of 50-200 halo power spectra) we are able to provide significantly improved matrices, which are almost indistinguishable from the ones built from much larger samples (thousands of spectra). In order to perform this task we trained convolutional neural networks to denoise the matrices, using in the training process a data set made up entirely of spectra extracted from simple, inexpensive halo simulations (mocks). We then show that the method not only removes the noise in the matrices of the cheap simulation, but it is also able to successfully denoise the matrices of halo power spectra from N-body simulations. We compare the denoised to the other matrices using several metrics, and in all of them they score better, without any signs of spurious artifacts. With the help of the Wishart distribution we derive an analytical extrapolation for the effective sample augmentation allowed by the denoiser. Finally, we show that, by using the denoised matrices, the cosmological parameters can be recovered with nearly the same accuracy as when using matrices built with a sample of 30,000 spectra in the case of the cheap simulations, and with 15,000 spectra in the case of the N-body simulations. Of particular interest is the bias in the Hubble parameter $H_0$, which was significantly reduced after applying the denoiser.
description: Matches published version; very minor changes wrt V1