cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Toward Robust Machine Learning by Countering Superficial Features
Creators: name: Wang, Haohan
Publisher: name: Carnegie Mellon University
Year: 2023
Subjects: Communications Technologies not elsewhere classified

description:  Machine learning, especially deep neural networks, has demonstrated remarkable empirical performances over various benchmarks. A potential next step is to extend these empirical successes beyond the i.i.d setting to a more practical scenario where the test data can be collected independently from the training data, while considered as the same task. In other words, how to train a robust model with data from one distribution and the test performance will not vary significantly over data from other different but related distributions. While there are many different works devoted to solve this problem of learning robust models from various perspectives, this thesis aims to complement other studies by offering a set of tools for the situation (and under the hypothesis) that one potential issue behind of the model’s non-robustness behaviors is the model’s tendency to predict through some features, which we refer to as superficial features.
We aim to attack the problem of learning robust models with several technical weapons: we first introduce a line of empirical efforts with numerical successes on different robustness-related benchmarks; we further aim to formally discuss the problem by assuming the challenges lie in the tendency of models’ learning of superficial features, which will also lead to a set of principled solutions; we also contribute engineering efforts to deliver a software that allows human to interact with image classification models to improve the model’s robustness against superficial features. 
In particular, we first hypothesize the underlying challenge of learning robust model lies in the data, and then validate our hypothesis by investigating the model’s behavior responding to different copies of the image data. 
Building upon our hypothesis, we introduce several new methods for image classification, countering different specific superficial features in the data. The success of these methods are validated as the empirical performances over standard domain generalization image classification tasks. 
Further, with the empirical success, we propose to formalize the problem of train?ing a model over data with superficial features. With the knowledge of the superficial features, the formalization leads to a proved bound of the generalization error over the distribution absent of the superficial features. Our formalization can connect to our proposed methods in the previous section well. Our bound will also inspire a new method forgoing the knowledge of superficial features with strong empirical successes.
 Finally, to foster the process of building robust models, we introduce a software with GUI that allows users to inspect image classification model’s decision process and annotate superficial features exploited by the model.
Many concepts and two logics of algorithmic reduction
Creators: name: Japaridze, Giorgi
Publisher: name: arXiv
Year: 2007
Subjects: subject: Logic in Computer Science (cs.LO)
subject: Logic (math.LO)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: F.1.1; F.1.2

description: Within the program of finding axiomatizations for various parts of computability logic, it was proved earlier that the logic of interactive Turing reduction is exactly the implicative fragment of Heyting's intuitionistic calculus. That sort of reduction permits unlimited reusage of the computational resource represented by the antecedent. An at least equally basic and natural sort of algorithmic reduction, however, is the one that does not allow such reusage. The present article shows that turning the logic of the first sort of reduction into the logic of the second sort of reduction takes nothing more than just deleting the contraction rule from its Gentzen-style axiomatization. The first (Turing) sort of interactive reduction is also shown to come in three natural versions. While those three versions are very different from each other, their logical behaviors (in isolation) turn out to be indistinguishable, with that common behavior being precisely captured by implicative intuitionistic logic. Among the other contributions of the present article is an informal introduction of a series of new -- finite and bounded -- versions of recurrence operations and the associated reduction operations. An online source on computability logic can be found at http://www.cis.upenn.edu/~giorgi/cl.html
description: To appear in Studia Logica in the Spring of 2009
Transport in randomly-fluctuating spatially-periodic potentials
Creators: name: Gleeson, James P.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The motion of overdamped particles in a one-dimensional spatially-periodic potential is considered. The potential is also randomly-fluctuating in time, due to multiplicative colored noise terms, and has a deterministic tilt. Numerical aimulations show two distinct parameter regimes, corresponding to free-running near-deterministic particles, and particles which are trapped in local minima of the potential with intermittent escape flights. Perturbation and asymptotic methods are developed to understand the drift velocity and diffusion coefficient in each parameter regime.
Coupling MOAO with Integral Field Spectroscopy: specifications for the VLT and the E-ELT
Creators: name: Puech, M.
name: Flores, H.
name: Lehnert, M.
name: Neichel, B.
name: Fusco, T.
name: Rosati, P.
name: Cuby, J. -G.
name: Rousset, G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: [Abridged] We have developed an end-to-end simulation to specify the science requirements of a MOAO-fed integral field spectrograph on either an 8m or 42m telescope. Our simulations re-scales observations of local galaxies or results from numerical simulations of disk or interacting galaxies. For the current analysis, we limit ourselves to a local disk galaxy which exhibits simple rotation and a simulation of a merger. We have attempted to generalize our results by introducing the simple concepts of "PSF contrast" which is the amount of light polluting adjacent spectra which we find drives the smallest EE at a given spatial scale. The choice of the spatial sampling is driven by the "scale-coupling", i.e., the relationship between the IFU pixel scale and the size of the features that need to be recovered by 3D spectroscopy in order to understand the nature of the galaxy and its substructure. Because the dynamical nature of galaxies are mostly reflected in their large-scale motions, a relatively coarse spatial resolution is enough to distinguish between a rotating disk and a major merger. Although we used a limited number of morpho-kinematic cases, our simulations suggest that, on a 42m telescope, the choice of an IFU pixel scale of 50-75 mas seems to be sufficient. Such a coarse sampling has the benefit of lowering the exposure time to reach a specific signal-to-noise as well as relaxing the performance of the MOAO system. On the other hand, recovering the full 2D-kinematics of z~4 galaxies requires high signal-to-noise and at least an EE of 34% in 150 mas (2 pixels of 75 mas). Finally, we carried out a similar study at z=1.6 with a MOAO-fed spectrograph for an 8m, and find that at least an EE of 30% at 0.25 arcsec spatial sampling is required to understand the nature of disks and mergers.
description: 17 pages, 20 figures, accepted for publication in the MNRAS
An improved solar wind electron-density model for pulsar timing
Creators: name: You, X. P.
name: Hobbs, G. B.
name: Coles, W. A.
name: Manchester, R. N.
name: Han, J. L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Variations in the solar wind density introduce variable delays into pulsar timing observations. Current pulsar timing analysis programs only implement simple models of the solar wind, which not only limit the timing accuracy, but can also affect measurements of pulsar rotational, astrometric and orbital parameters. We describe a new model of the solar wind electron density content which uses observations from the Wilcox Solar Observatory of the solar magnetic field. We have implemented this model into the tempo2 pulsar timing package. We show that this model is more accurate than previous models and that these corrections are necessary for high precision pulsar timing applications.
description: Accepted by ApJ, 13 pages, 4 figures
Sensitivity of double resonance alignment magnetometers
Creators: name: Di Domenico, G.
name: Saudan, H.
name: Bison, G.
name: Knowles, P.
name: Weis, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We present an experimental study of the intrinsic magnetometric sensitivity of an optical/rf-frequency double resonance magnetometer in which linearly polarized laser light is used in the optical pumping and detection processes. We show that a semi-empirical model of the magnetometer can be used to describe the magnetic resonance spectra. Then, we present an efficient method to predict the optimum operating point of the magnetometer, i.e., the light power and rf Rabi frequency providing maximum magnetometric sensitivity. Finally, we apply the method to investigate the evolution of the optimum operating point with temperature. The method is very efficient to determine relaxation rates and thus allowed us to determine the three collisional disalignment cross sections for the components of the alignment tensor. Both first and second harmonic signals from the magnetometer are considered and compared.
Charges of dyons in N=2 supersymmetric gauge theory
Creators: name: Kuchiev, Michael Yu.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Expressions for electric and magnetic charges of dyons, which become massless in the strong-coupling limit of the supersymmetric N=2 gauge theory with an arbitrary gauge group are presented. Transitions into different vacua of the N =1 gauge theory, when the N=2 supersymmetry is broken explicitly to the N =1 case, are discussed. The existence of a minimal set of light dyons, which are necessary to describe this transition, is established. The total number of these dyons equals the product of the rank and dual Coxeter number of the gauge group. A conjecture, which states that this minimal set incorporates all possible light dyons, is discussed. A relation of dyon charges with monodromies at weak and strong couplings is outlined and comparison with known charges of dyons for particular gauge groups is made.
description: 31 pages
Radiation damage in biological material: electronic properties and electron impact ionization in urea
Creators: name: Caleman, C.
name: Ortiz, C.
name: Marklund, E.
name: Bultmark, F.
name: Gabrysch, M.
name: Parak, F. G.
name: Hajdu, J.
name: Klintenberg, M.
name: Timneanu, N.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Radiation damage is an unavoidable process when performing structural investigations of biological macromolecules with X-ray sources. In crystallography this process can be limited through damage distribution in a crystal, while for single molecular imaging it can be outrun by employing short intense pulses. Secondary electron generation is crucial during damage formation and we present a study in urea, as model for biomaterial. From first principles we calculate the band structure and energy loss function, and subsequently the inelastic electron cross section in urea. Using Molecular Dynamics simulations, we quantify the damage and study the magnitude and spatial extent of the electron cloud coming from an incident electron, as well as the dependence with initial energy.
description: 6 pages, 5 figures. Several major modifications. Revised version as accepted in EPL. Corrected figures 4 and 5, corresponding to published erratum
Viable Intermediate Inflation in the Mimetic DBI Model
Creators: name: Rashidi, Narges
name: Nozari, Kourosh
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
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: We study the intermediate inflation in the mimetic Dirac-Born-Infeld model. By considering the scale factor as $a=a_{0}\exp(bt^β)$, we show that in some ranges of the intermediate parameters $b$ and $β$, the model is free of the ghost and gradient instabilities. We study the scalar spectral index, tensor spectral index, and the tensor-to-scalar ratio in this model and compare the results with Planck2018 TT, TE, EE+lowE+lensing +BAO +BK14 data at $68\%$ and $95\%$ CL. In this regard, we find some constraints on the intermediate parameters that lead to the observationally viable values of the perturbation parameters. We also seek the non-gaussian features of the primordial perturbations in the equilateral configuration. By performing the numerical analysis on the nonlinearity parameter in this configuration, we show that the amplitude of the non-gaussianity in the intermediate mimetic DBI model is predicted to be in the range $-16.7
description: 24 pages, 9 figures, 2 tables
Numerical approach to low-doping regime of the t-J model
Creators: name: Bonca, J.
name: Maekawa, S.
name: Tohyama, T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We develop an efficient numerical method for the description of a single-hole motion in the antiferromagnetic background. The method is free of finite-size effects and allows calculation of physical properties at an arbitrary wavevector. Methodical increase of the functional space leads to results that are valid in the thermodynamic limit. We found good agreement with cumulant expansion, exact- diagonalization approaches on finite lattices as well as self-consistent Born approximations. The method allows a straightforward addition of other inelastic degrees of freedom, such as lattice effects. Our results confirm the existence of a finite quasiparticle weight near the band minimum for a single hole and the existence of string-like peaks in the single-hole spectral function.
description: 6 pages, 6 figures, accepted for publication in PRB
Spectral properties of interacting magnetoelectric particles
Creators: name: Kamenetskii, E. O.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The linear magnetoelectric (ME) effect provides a special route for linking magnetic and electric properties. In microwaves, a local ME effect appears due to the dynamical symmetry breakings of magnetic-dipolar modes (MDMs) in a ferrite disk particle. The fact that for MDMs in a ferrite disk one has evident both classical and quantum-like attributes, puts special demands on the methods used for study of interacting ME particles. A proper model for coupled particles should be based on the spectral characteristics of MDM oscillations and an analysis of the overlap integrals for interacting eigen oscillating ME elements. In this paper, we present theoretical studies of spectral properties of literally coupled of MDM ME disks. We show that there exists the "exchange" mechanism of interaction between the particles, which is distinctive from the magnetostatic interaction between magnetic dipoles. The spectral method proposed in this paper may further the development of a theory of ME "molecules" and realization of local ME composites.
description: 26 pages, 3 figures
Light emission patterns from stadium-shaped semiconductor microcavity lasers
Creators: name: Shinohara, Susumu
name: Fukushima, Takehiro
name: Harayama, Takahisa
Publisher: name: arXiv
Year: 2007
Subjects: subject: Optics (physics.optics)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: We study light emission patterns from stadium-shaped semiconductor (GaAs) microcavity lasers theoretically and experimentally. Performing systematic wave calculations for passive cavity modes, we demonstrate that the averaging by low-loss modes, such as those realized in multi-mode lasing, generates an emission pattern in good agreement with the ray model's prediction. In addition, we show that the dependence of experimental far-field emission patterns on the aspect ratio of the stadium cavity is well reproduced by the ray model.
description: 5 pages, 4 figures
Hadronic charmless B decays B-> AP
Creators: name: Cheng, Hai-Yang
name: Yang, Kwei-Chou
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The two-body hadronic decays of B mesons into pseudoscalar and axial vector mesons are studied within the framework of QCD factorization. The light-cone distribution amplitudes (LCDAs) for $^3P_1$ and $^1P_1$ axial-vector mesons have been evaluated using the QCD sum rule method. Owing to the G-parity, the chiral-even two-parton light-cone distribution amplitudes of the $^3P_1$ ($^1P_1$) mesons are symmetric (antisymmetric) under the exchange of quark and anti-quark momentum fractions in the SU(3) limit. For chiral-odd LCDAs, it is other way around. The main results are the following: (i) The predicted rates for $a_1^\pm(1260)π^\mp$, $b_1^\pm(1235)π^\mp$, $b_1^0(1235)π^-$, $a_1^+K^-$ and $b_1^+K^-$ modes are in good agreement with the data. However, the naively expected ratios $Br(B^-\to a_1^0π^-)/Br(\ov B^0\to a_1^+π^-)\leq 1$, $Br(B^-\to a_1^-π^0)/Br(\ov B^0\to a_1^-π^+)\sim {1\over 2}$ and $Br(B^-\to b_1^0K^-)/Br(\ov B^0\to b_1^+K^-)\sim {1\over 2}$ are not borne out by experiment. This should be clarified by the improved measurements of these decays. (ii) Since the $\bar B\to b_1K$ decays receive sizable annihilation contributions, their rates are sensitive to the interference between penguin and annihilation terms. The measurement of $Br(\bar B^0\to b_1^+K^-)$ implies a destructive interference which in turn indicates that the form factors for $B\to b_1$ and $B\to a_1$ transitions are of opposite signs. (iii) Sizable power corrections such as weak annihilation are needed to account for the observed rates of the penguin-dominated modes $K_1^-(1270)π^+$ and $K_1^-(1400)π^+$.
description: 38 pages, 1 figure. The experimental limit in Fig.1 is updated
Observation of the 5p Rydberg states of sulfur difluoride radical by resonance-enhanced multiphoton ionization spectroscopy
Creators: name: Zhang, Qun
name: Zhou, Xiaoguo
name: Li, Quanxin
name: Yu, Shuqin
name: Ma, Xingxiao
Publisher: name: arXiv
Year: 2008
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Sulfur difluoride radicals in their ground state have been produced by a "laser-free" pulsed dc discharge of the SF$_{6}$/Ar gas mixtures in a supersonic molecular beam and detected by mass-selective resonance-enhanced multilphoton ionization (REMPI) spectroscopy in the wavelength range of 408 - 420 nm. Analyses of the (3 + 1) REMPI excitation spectrum have enabled identification of three hitherto unknown Rydberg states of this radical. Following the Rydberg state labeling in our previous work [see J. Phys. Chem. A 102, 7233 (1998)], these we label the K(5p$_{1}$) [$nu_{0-0}$ = 71 837 cm$^{-1}$, $omega_{1}^{'}$(a$_{1}$ sym str) = 915 cm$^{-1}$], L(5p$_{2}$) [$nu_{0-0}$ = 72 134 cm$^{-1}$, $omega_{1}^{'}$(a$_{1}$ sym str) = 912 cm$^{-1}$], and M(5p$_{3}$) [$nu_{0-0}$ = 72 336 cm$^{-1}$, $omega_{1}^{'}$(a$_{1}$ sym str) = 926 cm$^{-1}$] Rydberg states, respectively. [Origins, relative to the lowest vibrational level of the X$^{1}$A$_{1}$ ground state, and vibrational frequencies of the symmetric S-F stretching mode are suggested by the numbers in brackets.] Photofragmentation process of SF$_{2}$$^{+}$--SF$^{+}$ + F that relates to the REMPI spectrum was discussed.
description: 17 pages, 1 table, 2 figures
Feature selection for high dimensional data in astronomy
Creators: name: Zheng, H.
name: Zhang, Y.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: With an exponentially increasing amount of astronomical data, the complexity and dimension of astronomical data are likewise growing rapidly. Extracting information from such data becomes a critical and challenging problem. For example, some algorithms can only be employed in the low-dimensional spaces, so feature selection and feature extraction become important topics. Here we describe the difference between feature selection and feature extraction methods, and introduce the taxonomy of feature selection methods as well as the characteristics of each method. We present a case study comparing the performance and computational cost of different feature selection methods. For the filter method, ReliefF and fisher filter are adopted; for the wrapper method, improved CHAID, linear discriminant analysis (LDA), Naive Bayes (NB) and C4.5 are taken as learners. Applied on the sample, the result indicates that from the viewpoints of computational cost the filter method is superior to the wrapper method. Moreover, different learning algorithms combined with appropriate feature selection methods may arrive at better performance.
description: 11, accepted by Advances in Space Research
Recent advances in Bayesian optimization with applications to parameter reconstruction in optical nano-metrology
Creators: name: Plock, Matthias
name: Burger, Sven
name: Schneider, Philipp-Immanuel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Optics (physics.optics)
subject: Machine Learning (stat.ML)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Parameter reconstruction is a common problem in optical nano metrology. It generally involves a set of measurements, to which one attempts to fit a numerical model of the measurement process. The model evaluation typically involves to solve Maxwell's equations and is thus time consuming. This makes the reconstruction computationally demanding. Several methods exist for fitting the model to the measurements. On the one hand, Bayesian optimization methods for expensive black-box optimization enable an efficient reconstruction by training a machine learning model of the squared sum of deviations. On the other hand, curve fitting algorithms, such as the Levenberg-Marquardt method, take the deviations between all model outputs and corresponding measurement values into account which enables a fast local convergence. In this paper we present a Bayesian Target Vector Optimization scheme which combines these two approaches. We compare the performance of the presented method against a standard Levenberg-Marquardt-like algorithm, a conventional Bayesian optimization scheme, and the L-BFGS-B and Nelder-Mead simplex algorithms. As a stand-in for problems from nano metrology, we employ a non-linear least-square problem from the NIST Standard Reference Database. We find that the presented method generally uses fewer calls of the model function than any of the competing schemes to achieve similar reconstruction performance.
description: Proceedings article, SPIE conference "Modeling Aspects in Optical Metrology VIII"
The More, the Better? A Study on Collaborative Machine Learning for DGA Detection
Creators: name: Drichel, Arthur
name: Holmes, Benedikt
name: von Brandt, Justus
name: Meyer, Ulrike
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Domain generation algorithms (DGAs) prevent the connection between a botnet and its master from being blocked by generating a large number of domain names. Promising single-data-source approaches have been proposed for separating benign from DGA-generated domains. Collaborative machine learning (ML) can be used in order to enhance a classifier's detection rate, reduce its false positive rate (FPR), and to improve the classifier's generalization capability to different networks. In this paper, we complement the research area of DGA detection by conducting a comprehensive collaborative learning study, including a total of 13,440 evaluation runs. In two real-world scenarios we evaluate a total of eleven different variations of collaborative learning using three different state-of-the-art classifiers. We show that collaborative ML can lead to a reduction in FPR by up to 51.7%. However, while collaborative ML is beneficial for DGA detection, not all approaches and classifier types profit equally. We round up our comprehensive study with a thorough discussion of the privacy threats implicated by the different collaborative ML approaches.
description: Accepted at The 3rd Workshop on Cyber-Security Arms Race (CYSARM '21)
Preparation contextuality powers parity-oblivious multiplexing
Creators: name: Spekkens, Robert W.
name: Buzacott, D. H.
name: Keehn, A. J.
name: Toner, Ben
name: Pryde, G. J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In a noncontextual hidden variable model of quantum theory, hidden variables determine the outcomes of every measurement in a manner that is independent of how the measurement is implemented. Using a generalization of this notion to arbitrary operational theories and to preparation procedures, we demonstrate that a particular two-party information-processing task, "parity-oblivious multiplexing," is powered by contextuality in the sense that there is a limit to how well any theory described by a noncontextual hidden variable model can perform. This bound constitutes a "noncontextuality inequality" that is violated by quantum theory. We report an experimental violation of this inequality in good agreement with the quantum predictions. The experimental results also provide the first demonstration of 2-to-1 and 3-to-1 quantum random access codes. Consequently, our experimental results also demonstrate better-than-classical performance for this task. They also represent the first demonstration of 2-to-1 and 3-to-1 quantum random access codes.
description: 7 pages, 2 figures; published version with supplementary material included as appendices
Strongly modulated transmission of a spin-split quantum wire with local Rashba interaction
Creators: name: Sanchez, David
name: Serra, Llorens
name: Choi, Mahn-Soo
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We investigate the transport properties of ballistic quantum wires in the presence of Zeeman spin splittings and a spatially inhomogeneous Rashba interaction. The Zeeman interaction is extended along the wire and produces gaps in the energy spectrum which allow electron propagation only for spinors lying along a certain direction. For spins in the opposite direction the waves are evanescent far away from the Rashba region, which plays the role of the scattering center. The most interesting case occurs when the magnetic field is perpendicular to the Rashba field. Then, the spins of the asymptotic wavefunctions are not eigenfunctions of the Rashba Hamiltonian and the resulting coupling between spins in the Rashba region gives rise to sudden changes of the transmission probability when the Fermi energy is swept along the gap. After briefly examining the energy spectrum and eigenfunctions of a wire with extended Rashba coupling, we analyze the transmission through a region of localized Rashba interaction, in which a double interface separates a region of constant Rashba interaction from wire leads free from spin-orbit coupling. For energies slightly above the propagation threshold, we find the ubiquitous occurrence of transmission zeros (antiresonances) which are analyzed by matching methods in the one-dimensional limit. We find that a a minimal tight-binding model yields analytical transmission lineshapes of Fano antiresonance type. More general angular dependences of the external magnetic field is treated within projected Schroedinger equations with Hamiltonian matrix elements mixing wavefunction components. Finally, we consider a realistic quantum wire where the energy subbands are coupled via the Rashba intersubband coupling term and discuss its effect on the transmission zeros.
description: 11 pages, 12 figures
Hypoxia-inducible factor (HIF)-3α2 serves as an endothelial cell fate executor during chronic hypoxia
Creators: name: Jaśkiewicz, Maciej
name: Moszyńska, Adrianna
name: Serocki, Marcin
name: Króliczewski, Jarosław
name: Bartoszewska, Sylwia
name: Collawn, James F.
name: Bartoszewski, Rafal
Publisher: name: IfADo - Leibniz Research Centre for Working Environment and Human Factors, Dortmund
Year: 2022
Subjects: hypoxia
human endothelial cells
HIF3A
DDIT4
REDD1

description: The adaptive response to hypoxia involves the transcriptional induction of three transcription factors called hypoxia inducible factor alpha 1, 2 and 3 (HIF-1α, HIF-2α, and HIF-3α) which dimerize with constitutively expressed beta chains that together form the HIF-1, -2 and -3 transcription factors. During normoxic conditions, the alpha chain is expressed at low levels since its stability is regulated by prolyl-hydroxylation that promotes subsequent ubiquitination and degradation. During hypoxic conditions, however, the prolyl hydroxylases are less active, and the alpha chain accumulates through elevated protein stability and the elevated induction of expression. Two of the three HIFs isoforms present in mammals, HIF-1 and HIF-2, are well characterized and have overlapping functions that promote cell survival, whereas HIF-3’s role remains less clear. The HIF-3 response is complicated because the HIF3A gene can utilize different promotors and alternate splicing sites that result in a number of different HIF-3α isoforms. Here, using human umbilical vein endothelial cells (HUVECs), we demonstrate that one of the isoforms of HIF-3α, isoform 2 (HIF-3α2) accumulates at a late stage of hypoxia and induces the expression of DNA damage inducible transcript 3 (DDIT4), a gene known to promote apoptosis. We also demonstrate that caspase 3/7 activity is elevated, supporting that the role of the HIF-3α2 isoform is to promote apoptosis. Furthermore, we provide evidence that HIF-3α2 is also expressed in seven other primary endothelial cell types, suggesting that this may be a common feature of HIF-3α2 in endothelial cells.
description: EXCLI Journal; 21:Doc454; ISSN 1611-2156
Equidistribution of the Fekete points on the sphere
Creators: name: Marzo, Jordi
name: Ortega-Cerdà, Joaquim
Publisher: name: arXiv
Year: 2008
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics

description: The Fekete points are the points that maximize a Vandermonde-type determinant that appears in the polynomial Lagrange interpolation formula. They are well suited points for interpolation formulas and numerical integration. We prove the asymptotic equidistribution of the Fekete points in the sphere. The way we proceed is by showing their connection with other array of points, the Marcinkiewicz-Zygmund arrays and the interpolating arrays, that have been studied recently.
Searching for energetic cosmic axions in a laboratory experiment: testing the PVLAS anomaly
Creators: name: Fairbairn, M.
name: Gninenko, S. N.
name: Krasnikov, N. V.
name: Matveev, V. A.
name: Rashba, T. I.
name: Rubbia, A.
name: Troitsky, Sergey
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Astrophysical sources of energetic gamma rays provide the right conditions for maximal mixing between (pseudo)scalar (axion-like) particles and photons if their coupling is as strong as suggested by the PVLAS claim. This is independent of whether or not the axion interaction is standard at all energies or becomes supressed in the extreme conditions of the stellar interior. The flux of such particles through the Earth could be observed using a metre long, Tesla strength superconducting solenoid thus testing the axion interpretation of the PVLAS anomaly. The rate of events in CAST caused by axions from the Crab pulsar is also estimated for the PVLAS-favoured parameters.
description: 5 pages, 3 figure
Non-conformal attractor in boost-invariant plasmas
Creators: name: Chattopadhyay, Chandrodoy
name: Jaiswal, Sunil
name: Du, Lipei
name: Heinz, Ulrich
name: Pal, Subrata
Publisher: name: arXiv
Year: 2021
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: We study the dissipative evolution of (0+1)-dimensionally expanding media with Bjorken symmetry using the Boltzmann equation for massive particles in relaxation-time approximation. Breaking conformal symmetry by a mass induces a non-zero bulk viscous pressure in the medium. It is shown that even a small mass (in units of the local temperature) drastically modifies the well-known attractor for the shear Reynolds number previously observed in massless systems. For generic nonzero particle mass, neither the shear nor the bulk viscous pressure relax quickly to a non-equilibrium attractor; they approach the hydrodynamic limit only late, at small values of the inverse Reynolds numbers. Only the longitudinal pressure, which is a combination of thermal, shear and bulk viscous pressures, continues to show early approach to a far-off-equilibrium attractor, driven by the rapid longitudinal expansion at early times. Second-order dissipative hydrodynamics based on a gradient expansion around locally isotropic thermal equilibrium fails to reproduce this attractor.
description: 7 pages, 4 figures
Hydrogen/silicon complexes in silicon from computational searches
Creators: name: Morris, Andrew J.
name: Pickard, Chris J.
name: Needs, R. J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Defects in crystalline silicon consisting of a silicon self-interstitial atom and one, two, three, or four hydrogen atoms are studied within density-functional theory (DFT). We search for low-energy defects by starting from an ensemble of structures in which the atomic positions in the defect region have been randomized. We then relax each structure to a minimum in the energy. We find a new defect consisting of a self-interstitial and one hydrogen atom (denoted by {I,H}) which has a higher symmetry and a lower energy than previously reported structures. We recover the {I,H_2} defect found in previous studies and confirm that it is the most stable such defect. Our best {I,H_3} defect has a slightly different structure and lower energy than the one previously reported, and our lowest energy {I,H_4} defect is different to those of previous studies.
description: 7 pages, 8 figures
Utilization of multi-temporal landsat imagery for analyzing land Use/Cover changes and urban expansion of Nakhon Rachasima City
Creators: name: Prach Sangthongwattanakul
name: Chattichai Waisurasingha
name: Suriya Polpoon
Publisher: name: Faculty of Engineering, Khon Kaen Univeristy
Year: 2014
Subjects: Urban growth,Land use/cover changes,Landsat imagery, Remote sensing

description: 1, 41, KKU Engineering Journal
O$_2$ on Ag(110): A puzzle for exchange-correlation functionals
Creators: name: Lončarić, Ivor
name: Alducin, Maite
name: Juaristi, J. Iñaki
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Despite the great success of density functional theory in describing materials, there are still a few examples where current exchange-correlation functionals fail. We add another example to this list that drives further development of functionals. We show that the interaction of O$_2$ with Ag(110) cannot be properly described by some of the most popular GGA, meta GGA, and hybrid functionals. We identify problems and provide clues for a functional that should be able to describe this and similar systems properly.
Spatially resolved observation of dipole-dipole interaction between Rydberg atoms
Creators: name: van Ditzhuijzen, C. S. E.
name: Koenderink, A. F.
name: Hernández, J. V.
name: Robicheaux, F.
name: Noordam, L. D.
name: Heuvell, H. B. van Linden van den
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We have observed resonant energy transfer between cold Rydberg atoms in spatially separated cylinders. Resonant dipole-dipole coupling excites the 49s atoms in one cylinder to the 49p state while the 41d atoms in the second cylinder are transferred down to the 42p state. We have measured the production of the 49p state as a function of separation of the cylinders (0 - 80 um) and the interaction time (0 - 25 us). In addition we measured the width of the electric field resonances. A full many-body quantum calculation reproduces the main features of the experiments.
description: 4 pages, 4 figures
Greenberger-Horne-Zeilinger-type violation of local realism by mixed states
Creators: name: Zhou, X. -Q.
name: Lu, C. -Y.
name: Gao, W. -B.
name: Zhang, J.
name: Chen, Z. -B.
name: Yang, T.
name: Pan, J. -W.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Cluster states are multi-particle entangled states with special entanglement properties particularly suitable for quantum computation. It has been shown that cluster states can exhibit Greenberger-Horne-Zeilinger (GHZ)-type non-locality even when some of their qubits have been lost. In the present work, we generated a four-photon mixed state, which is equivalent to the partial, qubit-loss state of an N-qubit cluster state up to some local transformations. By using this mixed state, we then realize a GHZ-type violation of local realism. Our results not only demonstrate a mixed state's GHZ-type non-locality but also exhibit the robustness of cluster states under qubit-loss conditions.
description: four pages, five figures, revTex
Pushing the limits of EPD zeros method
Creators: name: Rodrigues, R. G. M.
name: Costa, B. V.
name: Mól, L. A. S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The use of partition function zeros in the study of phase transition is growing in the last decade mainly due to improved numerical methods as well as novel formulations and analysis. In this paper the impact of different parameters choice for the energy probability distribution (EPD) zeros recently introduced by Costa et al is explored in search for optimal values. Our results indicate that the EPD method is very robust against parameter variations and only small deviations on estimated critical temperatures are found even for large variation of parameters, allowing to obtain accurate results with low computational cost. A proposal to circumvent potential convergence issues of the original algorithm is presented and validated for the case where it occurs.
Quantum Reference Frames and the Classification of Rotationally-Invariant Maps
Creators: name: Boileau, J. -C.
name: Sheridan, L.
name: Laforest, M.
name: Bartlett, S. D.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We give a convenient representation for any map that is covariant with respect to an irreducible representation of SU(2), and use this representation to analyze the evolution of a quantum directional reference frame when it is exploited as a resource for performing quantum operations. We introduce the moments of a quantum reference frame, which serve as a complete description of its properties as a frame, and investigate how many times a quantum directional reference frame represented by a spin-j system can be used to perform a certain quantum operation with a given probability of success. We provide a considerable generalization of previous results on the degradation of a reference frame, from which follows a classification of the dynamics of spin-j system under the repeated action of any covariant map with respect to SU(2).
description: 18 pages. Accepted in Journal of Mathematical Physics
Flat modules over valuation rings
Creators: name: Couchot, Francois
Publisher: name: arXiv
Year: 2007
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: (Primary) 13F30, 13C11; (Secondary) 16D40

description: Let $R$ be a valuation ring and let $Q$ be its total quotient ring. It is proved that any singly projective (respectively flat) module is finitely projective if and only if $Q$ is maximal (respectively artinian). It is shown that each singly projective module is a content module if and only if any non-unit of $R$ is a zero-divisor and that each singly projective module is locally projective if and only if $R$ is self injective. Moreover, $R$ is maximal if and only if each singly projective module is separable, if and only if any flat content module is locally projective. Necessary and sufficient conditions are given for a valuation ring with non-zero zero-divisors to be strongly coherent or $π$-coherent. A complete characterization of semihereditary commutative rings which are $π$-coherent is given. When $R$ is a commutative ring with a self FP-injective quotient ring $Q$, it is proved that each flat $R$-module is finitely projective if and only if $Q$ is perfect.
Automated detection of galaxy-scale gravitational lenses in high resolution imaging data
Creators: name: Marshall, Philip J.
name: Hogg, David W.
name: Moustakas, Leonidas A.
name: Fassnacht, Christopher D.
name: Bradac, Marusa
name: Schrabback, Tim
name: Blandford, Roger D.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Lens modeling is the key to successful and meaningful automated strong galaxy-scale gravitational lens detection. We have implemented a lens-modeling "robot" that treats every bright red galaxy (BRG) in a large imaging survey as a potential gravitational lens system. Using a simple model optimized for "typical" galaxy-scale lenses, we generate four assessments of model quality that are used in an automated classification. The robot infers the lens classification parameter H that a human would have assigned; the inference is performed using a probability distribution generated from a human-classified training set, including realistic simulated lenses and known false positives drawn from the HST/EGS survey. We compute the expected purity, completeness and rejection rate, and find that these can be optimized for a particular application by changing the prior probability distribution for H, equivalent to defining the robot's "character." Adopting a realistic prior based on the known abundance of lenses, we find that a lens sample may be generated that is ~100% pure, but only ~20% complete. This shortfall is due primarily to the over-simplicity of the lens model. With a more optimistic robot, ~90% completeness can be achieved while rejecting ~90% of the candidate objects. The remaining candidates must be classified by human inspectors. We are able to classify lens candidates by eye at a rate of a few seconds per system, suggesting that a future 1000 square degree imaging survey containing 10^7 BRGs, and some 10^4 lenses, could be successfully, and reproducibly, searched in a modest amount of time. [Abridged]
description: 17 pages, 11 figures, submitted to ApJ
The Existence of Inner Cool Disks in the Low Hard State of Accreting Black Holes
Creators: name: Liu, B. F.
name: Taam, Ronald E.
name: Meyer-Hofmeister, E.
name: Meyer, F.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The condensation of matter from a corona to a cool, optically thick inner disk is investigated for black hole X-ray transient systems in the low hard state. A description of a simple model for the exchange of energy and mass between corona and disk originating from thermal conduction is presented, taking into account the effect of Compton cooling of the corona by photons from the underlying disk. It is found that a weak, condensation-fed inner disk can be present in the low hard state of black hole transient systems for a range of luminosities which depend on the magnitude of the viscosity parameter. For $α\sim 0.1-0.4$ an inner disk can exist for luminosities in the range $\sim 0.001- 0.02$ Eddington value. The model is applied to the X-ray observations of the black hole candidate sources GX 339-4 and Swift J1753.5-0127 in their low hard state. It is found that Compton cooling is important in the condensation process, leading to the maintenance of cool inner disks in both systems. As the results of the evaporation/condensation model are independent of the black hole mass, it is suggested that such inner cool disks may contribute to the optical and ultraviolet emission of low luminosity active galactic nuclei.
description: 32 pages, 5 figures, accepted for publication in ApJ (Dec. 10, 2007, Vol.671)
A Novel Ordered Phase in SrCu2(BO3)2 under High Pressure
Creators: name: Waki, Takeshi
name: Arai, Koichi
name: Takigawa, Masashi
name: Saiga, Yuta
name: Uwatoko, Yoshiya
name: Kageyama, Hiroshi
name: Ueda, Yutaka
Publisher: name: arXiv
Year: 2007
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report results of 11B NMR and susceptibility measurements on the quasi 2D frustrated dimer spin system SrCu2(BO3)2 under high pressure. At 2.4 GPa and in a magnetic field of 7 T, NMR lines split with decreasing temperature in two steps. A gradual splitting below T=30 K breaking the four-fold symmetry of magnetic response is followed by a further sudden splitting below 3.6 K. The latter indicates a magnetic phase transition, which is also marked by a kink in the susceptibility at 1.44 GPa. From the magnetic hyperfine shift data, we conclude that the low-T phase has a doubled unit cell containing two types of dimers, one in a nearly singlet state and the other with a finite magnetization down to T=0.
description: 5 pages, 4 figures, to appear in J. Phys. Soc. Jpn. (July 2007)