cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
High-order Time Expansion Path Integral Ground State
Creators: name: Rota, R.
name: Casulleras, J.
name: Mazzanti, F.
name: Boronat, J.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The feasibility of path integral Monte Carlo ground state calculations with very few beads using a high-order short-time Green's function expansion is discussed. An explicit expression of the evolution operator which provides dramatic enhancements in the quality of ground-state wave-functions is examined. The efficiency of the method makes possible to remove the trial wave function and thus obtain completely model-independent results still with a very small number of beads. If a single iteration of the method is used to improve a given model wave function, the result is invariably a shadow-type wave function, whose precise content is provided by the high-order algorithm employed.
description: 4 pages
A Survey: Deep Learning for Hyperspectral Image Classification with Few Labeled Samples
Creators: name: Jia, Sen
name: Jiang, Shuguo
name: Lin, Zhijie
name: Li, Nanying
name: Xu, Meng
name: Yu, Shiqi
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Artificial Intelligence (cs.AI)
subject: Image and Video Processing (eess.IV)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: With the rapid development of deep learning technology and improvement in computing capability, deep learning has been widely used in the field of hyperspectral image (HSI) classification. In general, deep learning models often contain many trainable parameters and require a massive number of labeled samples to achieve optimal performance. However, in regard to HSI classification, a large number of labeled samples is generally difficult to acquire due to the difficulty and time-consuming nature of manual labeling. Therefore, many research works focus on building a deep learning model for HSI classification with few labeled samples. In this article, we concentrate on this topic and provide a systematic review of the relevant literature. Specifically, the contributions of this paper are twofold. First, the research progress of related methods is categorized according to the learning paradigm, including transfer learning, active learning and few-shot learning. Second, a number of experiments with various state-of-the-art approaches has been carried out, and the results are summarized to reveal the potential research directions. More importantly, it is notable that although there is a vast gap between deep learning models (that usually need sufficient labeled samples) and the HSI scenario with few labeled samples, the issues of small-sample sets can be well characterized by fusion of deep learning methods and related techniques, such as transfer learning and a lightweight model. For reproducibility, the source codes of the methods assessed in the paper can be found at https://github.com/ShuGuoJ/HSI-Classification.git.
GEMINI 3D spectroscopy of BAL+IR+Fe II QSOs: II. IRAS 04505-2958 an explosive QSO with hypershell and a new scenario for galaxy formation and galaxy end
Creators: name: Lipari, S.
name: Bergmann, M.
name: Sanchez, S. F.
name: Garcia-Lorenzo, B.
name: Terlevich, R.
name: Mediavilla, E.
name: Taniguchi, Y.
name: Zheng, W.
name: Punsly, B.
name: Jahnke, K.
name: Ahumada, A.
name: Merlo, D.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: From a study of BAL + IR + Fe II QSOs (using deep Gemini GMOS-IFU spectroscopy) new results are presented: for IRAS 04505-2958. Specifically, we have studied in detail the out flow (OF) process and their associated structures, mainly at two large galactic scales: (i) two blobs/shells (S1, S2) at radius r = 1.1 and 2.2 kpc; and (ii) an external hypergiant shell (S3) at r = 11 kpc. In addition, the presence of two very extended hypergiant shells (S4, S5) at r = 80 kpc is discussed. From this GMOS study the following main results were obtained: (i) For the external hypergiant shell S3 the kinematics GMOS maps of the ionized gas show very similar features to those observed for the prototype of exploding external supergiant shell: in NGC 5514. (ii) The main knots K1, K2 and K3 -of this hypergiant shell S3- show a stellar population and emission line ratios associated with the presence of a starburst + OF/shocks. (iii) The internal shells S1 and S2 show structures, OF components and properties very similar to those detected in the nuclear shells of Mrk 231. (iv) The shells S1+S2 and S3 are aligned at PA = 131: i.e. suggesting that the OF process is in the blow-out phase with bipolar structure. In addition, the shells S4 and S5 (at 80-100 kpc scale) are aligned at PA = 40, i.e.: a bipolar OF perpendicular to the internal OF. Finally, the generation of UHE cosmic rays and neutrino/ dark-matter -associated with HyNe in BAL + IR + Fe II QSOs- is discussed.
description: Submitted MNRAS, 81 pages, 25 Figures
Formation of galactic bulges from the cold gas filaments in high-redshift dark matter halos
Creators: name: Noguchi, Masafumi
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Formation process(es) of galactic bulges are not yet clarified although several mechanisms have been proposed. In a previous study, we suggested one possibility that galactic bulges have been formed from the cold gas inflowing through surrounding hot halo gas in massive dark matter halos at high redshifts. It was shown that this scenario leads to the bulge-to-total stellar mass ratio increasing with the galaxy mass, in agreement with the well-known observed trend. We here indicate that it also reproduces recent observational results that the mean stellar age of the bulge increases with the galaxy mass while the age gradient across the bulge decreases. We infer that this formation path applies mainly to high-mass galaxies and the bulges in lower-mass galaxies have different origins such as secular formation from the disc material.
description: 6 pages, 4 figures, submitted to MNRAS
Budding and vesiculation induced by conical membrane inclusions
Creators: name: Auth, Thorsten
name: Gompper, Gerhard
Publisher: name: arXiv
Year: 2009
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Conical inclusions in a lipid bilayer generate an overall spontaneous curvature of the membrane that depends on concentration and geometry of the inclusions. Examples are integral and attached membrane proteins, viruses, and lipid domains. We propose an analytical model to study budding and vesiculation of the lipid bilayer membrane, which is based on the membrane bending energy and the translational entropy of the inclusions. If the inclusions are placed on a membrane with similar curvature radius, their repulsive membrane-mediated interaction is screened. Therefore, for high inclusion density the inclusions aggregate, induce bud formation, and finally vesiculation. Already with the bending energy alone our model allows the prediction of bud radii. However, in case the inclusions induce a single large vesicle to split into two smaller vesicles, bending energy alone predicts that the smaller vesicles have different sizes whereas the translational entropy favors the formation of equal-sized vesicles. Our results agree well with those of recent computer simulations.
description: 11 pages, 12 figures
Axions as Dark Matter Particles
Creators: name: Duffy, Leanne D.
name: van Bibber, Karl
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We review the current status of axions as dark matter. Motivation, models, constraints and experimental searches are outlined. The axion remains an excellent candidate for the dark matter and future experiments, particularly the Axion Dark Matter eXperiment (ADMX), will cover a large fraction of the axion parameter space.
description: 17 pages, 1 figure; contribution to NJP focus issue, "Dark Matter and Particle Physics"
Domain growth in cholesteric blue phases: hybrid lattice Boltzmann simulations
Creators: name: Henrich, O.
name: Marenduzzo, D.
name: Stratford, K.
name: Cates, M. E.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Here we review a hybrid lattice Boltzmann algorithm to solve the equations of motion of cholesteric liquid crystals. The method consists in coupling a lattice Boltzmann solver for the Navier-Stokes equation to a finite difference method to solve the dynamical equations governing the evolution of the liquid crystalline order parameter. We apply this method to study the growth of cholesteric blue phase domains, within a cholesteric phase. We focus on the growth of blue phase II and on a thin slab geometry in which the domain wall is flat. Our results show that, depending on the chirality, the growing blue phase is either BPII with no or few defects, or another structure with hexagonal ordering. We hope that our simulations will spur further experimental investigations on quenches in micron-size blue phase samples. The computational size that our hybrid lattice Boltzmann scheme can handle suggest that large scale simulations of new generation of blue phase liquid crystal device are within reach.
description: 22 pages, 4 figures
Stability and dynamics of the laminar flow past rectangular prisms
Creators: name: Chiarini, Alessandro
name: Boujo, Edouard
Publisher: name: arXiv
Year: 2024
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: The laminar flow past rectangular prisms is studied in the space of length-to-height ratio ($1 \le L/H \le 5$), width-to-height ratio ($1.2 \le W/H \le 5$) and Reynolds number ($Re \lessapprox 700$). The primary bifurcation is investigated with linear stability analysis. For large $W/L$ it consists of an oscillating mode breaking the top/bottom planar symmetry. For smaller $W/L$ the flow becomes first unstable to stationary perturbations, and the wake experiences a static deflection, vertical for intermediate $W/L$ and horizontal for small $W/L$. Weakly nonlinear analysis and nonlinear direct numerical simulations are used for $L/H = 5$ and larger $Re$. For $W/H = 1.2$ and $2.25$, after the primary bifurcation the flow recovers the top/bottom planar symmetry but loses the left/right one, via supercritical and subcritical pitchfork bifurcations, respectively. Further increasing $Re$, the flow becomes unsteady and oscillates around either the deflected (small $W/H$) or the non-deflected (intermediate $W/H$) wake. For intermediate $W/H$ and $R$e, a periodic and fully symmetric regime is detected, with hairpin vortices shed from the top and bottom leading-edge (LE) shear layers; its triggering mechanism is discussed. At large $Re$ and for all $W/H$, the flow approaches a chaotic state characterised by the superposition of different modes: shedding of hairpin vortices from the LE shear layers, and wake oscillations in the horizontal and vertical directions. In some portions of the parameter space the different modes synchronise, giving rise to periodic regimes also at relatively large $Re$.
description: 49 pages, 32 figures; accepted in the Journal of Fluid Mechanics
The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey
Creators: name: Hayden, Brian T.
name: Garnavich, Peter M.
name: Kessler, Richard
name: Frieman, Joshua A.
name: Jha, Saurabh W.
name: Cinabro, David
name: Dilday, Benjamin
name: Kasen, Daniel
name: Marriner, John
name: Nichol, Robert C.
name: Riess, Adam G.
name: Sako, Masao
name: Schneider, Donald P.
name: Smith, Mathew
name: Sollerman, Jesper
name: Bassett, Bruce
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We analyze the rise and fall times of type Ia supernova (SN Ia) light curves discovered by the SDSS-II Supernova Survey. From a set of 391 light curves k-corrected to the rest frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single 'stretch' correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well-observed in both rise and fall portions of the light curves and develop a '2-stretch' fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 +/- 0.17 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. We find that slow declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single-peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink (2007) from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, tr-tf <= 2 days and tr-tf>2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble residuals in our sample.
description: 42 pages, 15 figures, accepted to ApJ for publication in March 2010, v711 issue
Relationship between leisure activities and satisfaction with a rural fringe location
Creators: name: Pounder, Kathryn Elizabeth
Publisher: name: University of British Columbia
Year: 2011

description: The purpose of this study is to explore the relationship between residents' leisure activities and their physical environment as an aid to understanding their satisfaction with that environment. This is done with specific reference to Maple Ridge, a fringe area of Vancouver. Three major questions are considered. How do the characteristics of the residents affect the frequency of their participation in various leisure, activities? To what extent does the environment constrain or facilitate activities which the residents have an interest in pursuing? And, to what extent does participation in activities which are facilitated or constrained by the environment influence residents1 satisfaction with that environment? Ten hypotheses and two assumptions were formulated to examine the relationships suggested by these questions. The study data consists of 152 responses to a mailed questionnaire which was distributed to a random sample of the residents of Maple Ridge. Univariate techniques for comparing percentage differences, means and correlations, and the multivariate techniques of factor analysis, Hotelling's T² statistic and discriminant analysis are used to test the hypotheses. It is shown that the residents who were most interested and participated most frequently in rural related activities preferred a more rural environment; whereas, there is some indication that those who participated less frequently in such activities preferred a more urban environment. For planners, the results of this study imply that it is valid to examine residential location on the basis of the residents' leisure activities and that the fringe should be recognized as an area offering unique residential opportunities within the metropolitan area.
The orbit of the star S2 around SgrA* from VLT and Keck data
Creators: name: Gillessen, S.
name: Eisenhauer, F.
name: Fritz, T. K.
name: Bartko, H.
name: Dodds-Eden, K.
name: Pfuhl, O.
name: Ott, T.
name: Genzel, R.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Two recent papers (Ghez et al. 2008, Gillessen et al. 2009) have estimated the mass of and the distance to the massive black hole in the center of the Milky Way using stellar orbits. The two astrometric data sets are independent and yielded consistent results, even though the measured positions do not match when simply overplotting the two sets. In this letter we show that the two sets can be brought to excellent agreement with each other when allowing for a small offset in the definition of the reference frame of the two data sets. The required offsets in the coordinates and velocities of the origin of the reference frames are consistent with the uncertainties given in Ghez et al. (2008). The so combined data set allows for a moderate improvement of the statistical errors of mass of and distance to Sgr A*, but the overall accuracies of these numbers are dominated by systematic errors and the long-term calibration of the reference frame. We obtain R0 = 8.28 +- 0.15(stat) +- 0.29(sys) kpc and M(MBH) = 4.30 +- 0.20(stat) +- 0.30(sys) x 10^6 Msun as best estimates from a multi-star fit.
description: submitted to ApJL
Introduction and analysis of a method for the investigation of QCD-like tree data
Creators: name: Jercic, Marko
name: Jercic, Ivan
name: Poljak, Nikola
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computational Physics (physics.comp-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The properties of decays that take place during jet formation cannot be easily deduced from the final distribution of particles in a detector. In this work, we first simulate a system of particles with well defined masses, decay channels, and decay probabilities. This presents the "true system" for which we want to reproduce the decay probability distributions. Assuming we only have the data that this system produces in the detector, we decided to employ an iterative method which uses a neural network as a classifier between events produced in the detector by the "true system" and some arbitrary "test system". In the end, we compare the distributions obtained with the iterative method to the "true" distributions.
description: 19 pages, 13 figures, submitted to Entropy
"Ab initio" models of galaxy formation: successes and open problems
Creators: name: De Lucia, Gabriella
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: In the past decades, different approaches have been developed in order to link the physical properties of galaxies to the dark matter haloes in which they reside. In this review, I give a brief overview of methods, aims, and limits of these techniques, with particular emphasis on semi-analytic models of galaxy formation. For these models, I also provide a brief summary of recent successes and open problems.
description: 8 pages, to appear in "Probing Stellar Populations out to the Distant Universe", AIP Conf. Proc. Series (Cefalu, Italy, Sep 7-19, 2008)
Standard and non-standard metarefraction with confocal lenslet arrays
Creators: name: Courtial, Johannes
Publisher: name: arXiv
Year: 2009
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A recent paper demonstrated that two lenslet arrays with focal lengths f_1 and f_2, separated by f_1 + f_2, change the direction of transmitted light rays approximately like the interface between isotropic media with refractive indices n_1 and n_2, where n_1 / n_2 = - f_1 / f_2 [J. Courtial, New J. Phys. 10, 083033 (2008)]. This is true if light passes through corresponding lenslets, that is lenslets that share an optical axis. Light can also pass through different combinations of non-corresponding lenslets. Such light can be either absorbed or allowed to form "ghost images"; either way, it leads to a limitation of the field of view of confocal lenslet arrays. This paper describes, qualitatively and quantitatively, a number of such field-of-view limitations.
description: 10 pages, 8 figures
Effective theory for the Goldstone field in the BCS-BEC crossover at T=0
Creators: name: Mañes, Juan L.
name: Valle, Manuel A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Superconductivity (cond-mat.supr-con)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We perform a detailed study of the effective Lagrangian for the Goldstone mode of a superfluid Fermi gas at zero temperature in the whole BCS-BEC crossover. By using a derivative expansion of the response functions, we derive the most general form of this Lagrangian at the next to leading order in the momentum expansion in terms of four coefficient functions. This involves the elimination of all the higher order time derivatives by careful use of the leading order field equations. In the infinite scattering length limit where conformal invariance is realized, we show that the effective Lagrangian must contain an unnoticed invariant combination of higher spatial gradients of the Goldstone mode, while explicit couplings to spatial gradients of the trapping potential are absent. Across the whole crossover, we determine all the coefficient functions at the one-loop level, taking into account the dependence of the gap parameter on the chemical potential in the mean-field approximation. These results are analytically expressed in terms of elliptic integrals of the first and second kind. We discuss the form of these coefficients in the extreme BCS and BEC regimes and around the unitary limit, and compare with recent work by other authors.
description: 27 pages. 4 references added, typos corrected, expanded Section III B
Mass Functions of the Active Black Holes in Distant Quasars from the Large Bright Quasar Survey, the Bright Quasar Survey, and the Color-Selected Sample of the SDSS Fall Equatorial Stripe
Creators: name: Vestergaard, M.
name: Osmer, Patrick S.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present mass functions of distant actively accreting supermassive black holes residing in luminous quasars discovered in the Large Bright Quasar Survey, the Bright Quasar Survey, and the Fall Equatorial Stripe of the Sloan Digital Sky Survey (SDSS). The quasars cover a wide range of redshifts (0 ~ 10^8 Msun) between redshifts ~4 and ~2.5. Also, the z~4 SDSS quasar mass function has a somewhat flatter high mass-end slope, beta = -1.75 +- 0.56, compared to the mass functions based on quasars below z of 3, which display typical slopes of beta =~ -3.3; the latter are consistent with the mass functions at similar redshifts based on the SDSS Data Release 3 quasar catalog presented by Vestergaard et al. We see clear evidence of cosmic downsizing in the comoving space density distribution of active black holes in the LBQS sample alone. In forthcoming papers, further analysis, comparison, and discussion of these mass functions will be made with other existing black hole mass functions, notably that based on the SDSS DR3 quasar catalog. We present the relationships used to estimate the black hole mass based on the MgII emission line; the relations are calibrated to the Hbeta and CIV relations by means of several thousand high quality SDSS spectra. Mass estimates of the individual black holes of these samples are also presented.
description: Accepted for publication in Astrophysical Journal. 22 pages, including 11 figures and 11 tables
More on the covariant retarded Green's function for the electromagnetic field in de Sitter spacetime
Creators: name: Higuchi, Atsushi
name: Lee, Yen Cheong
name: Nicholas, Jack R.
Publisher: name: arXiv
Year: 2009
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In a recent paper (Phys. Rev. D78, 084031 (2008), arXiv:0808.0642, Ref. [1]) it was shown in examples that the covariant retarded Green's functions in particular gauges for electromagnetism and linearized gravity can be used to reproduce field configurations correctly in spite of the spacelike nature of past infinity in de Sitter spacetime. In this paper we extend the work of Ref. [1] concerning the electromagnetic field and show that the covariant retarded Green's function with an arbitrary value of the gauge parameter reproduces the electromagnetic field from two opposite charges at antipodal points of de Sitter spacetime.
description: 4 pages, addendum to PRD 78, 084031 (2008) [arXiv:0808.0642]
Holographic integral equations and walking technicolour
Creators: name: Alvares, Raul
name: Evans, Nick
name: Gebauer, Astrid
name: Weatherill, George James
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study chiral symmetry breaking in the holographic D3-D7 system in a simple model with an arbitrary running coupling. We derive equations for the D7 embedding and show there is a light pion. In particular we present simple integral equations, involving just the running coupling and the quark self energy, for the quark condensate and the pion decay constant. We compare these to the Pagels-Stokar or constituent quark model equivalent. We discuss the implications for walking Technicolour theories. We also perform a similar analysis in the four dimensional field theory whose dual is the non-supersymmetric D3-D5 system and propose that it represents a walking theory in which the quark condensate has dimension 2 + sqrt{3}.
description: 17 pages, 4 Figures, small added analysis
A Privacy-Preserving Platform for Recording COVID-19 Vaccine Passports
Creators: name: Barati, Masoud
name: Buchanan, William J.
name: Lo, Owen
name: Rana, Omer
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: Digital vaccine passports are one of the main solutions which would allow the restart of travel in a post COVID-19 world. Trust, scalability and security are all key challenges one must overcome in implementing a vaccine passport. Initial approaches attempt to solve this problem by using centralised systems with trusted authorities. However, sharing vaccine passport data between different organisations, regions and countries has become a major challenge. This paper designs a new platform architecture for creating, storing and verifying digital COVID-19 vaccine certifications. The platform makes use of the InterPlanetary File System (IPFS) to guarantee there is no single point of failure and allow data to be securely distributed globally. Blockchain and smart contracts are also integrated into the platform to define policies and log access rights to vaccine passport data while ensuring all actions are audited and verifiably immutable. Our proposed platform realises General Data Protection Regulation (GDPR) requirements in terms of user consent, data encryption, data erasure and accountability obligations. We assess the scalability and performance of the platform using IPFS and Blockchain test networks.
Dynamics around Non-Spherical Symmetric Bodies: I. The case of a spherical body with mass anomaly
Creators: name: Madeira, G.
name: Winter, S. M. Giuliatti
name: Ribeiro, T.
name: Winter, O. C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Dynamical Systems (math.DS)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: The space missions designed to visit small bodies of the Solar System boosted the study of the dynamics around non-spherical bodies. In this vein, we study the dynamics around a class of objects classified by us as Non-Spherical Symmetric Bodies, including contact binaries, triaxial ellipsoids, spherical bodies with a mass anomaly, among others. In the current work, we address the results for a body with a mass anomaly. We apply the pendulum model to obtain the width of the spin-orbit resonances raised by non-asymmetric gravitational terms of the central object. The Poincare surface of section technique is adopted to confront our analytical results and to study the system's dynamics by varying the parameters of the central object. We verify the existence of two distinct regions around an object with a mass anomaly: a chaotic inner region that extends beyond the corotation radius and a stable outer region. In the latter, we identify structures remarkably similar to those of the classical restrict and planar 3-body problem in the Poincare surface of sections, including asymmetric periodic orbits associated with 1:1+p resonances. We apply our results to a Chariklo with a mass anomaly, obtaining that Chariklo rings are probably related to first kind periodic orbits and not with 1:3 spin-orbit resonance, as proposed in the literature. We believe that our work presents the first tools for studying mass anomaly systems.
description: Accepted 2021 December 02. Received 2021 November 10; in original form 2021 August 06 - MNRAS
Implementation of an experimental facility and modeling studies for time varying images.
Creators: name: Jensen, Olav Velling
Publisher: name: University of British Columbia
Year: 2011

description: A wealth of experiments have been performed studying image encoding techniques as applied to non-time varying or single-frame images. However, to date little work has been done to apply these techniques to time varying images, with most of such works emphasizing various ad hoc redundancy reduction techniques. In this work, a computer based experimental system is implemented which makes more methodological studies of time varying images possible. Particular attention is devoted to obtaining very accurate inter-frame registration and uniform quantization of the images. Using this system, a selection of 35 mm movie film images are digitized and stored on computer magnetic tape in a format compatible with many other computing installations, providing a standard data base for future experiments. An often used model for describing picture data is the stationary Gauss-Markov model. In this work, the appropriateness of this model for describing time varying images is studied by comparing the autocorrelation functions as described by the model and as obtained by computation from the picture data. These results indicate that the autocorrelation function is best described by a function which is separable in the time dimension and nonseparable in the spacial dimensions. A number of DPCM communication systems are then studied as a vehicle for evaluating the effect of using the Gauss-Markov model. These results indicate that, for the sample images studied here, the estimated performance using the Gauss-Markov model is good when the model is a good fit to the first data point of the computed autocorrelation function.
Translating Politeness Across Cultures: Case of Hindi and English
Creators: name: Kumar, Ritesh
name: Jha, Girish Nath
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: In this paper, we present a corpus based study of politeness across two languages-English and Hindi. It studies the politeness in a translated parallel corpus of Hindi and English and sees how politeness in a Hindi text is translated into English. We provide a detailed theoretical background in which the comparison is carried out, followed by a brief description of the translated data within this theoretical model. Since politeness may become one of the major reasons of conflict and misunderstanding, it is a very important phenomenon to be studied and understood cross-culturally, particularly for such purposes as machine translation.
Performance of a cryo-cooled crystal monochromator illuminated by hard X-rays with MHz repetition rate at the European X-ray Free-Electron Laser
Creators: name: Petrov, I.
name: Boesenberg, U.
name: Bushuev, V. A.
name: Hallmann, J.
name: Kazarian, K.
name: Lu, W.
name: Möller, J.
name: Reiser, M.
name: Rodriguez-Fernandez, A.
name: Samoylova, L.
name: Scholz, M.
name: Sinn, H.
name: Zozulya, A.
name: Madsen, A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: We present experimental data illustrating how heat load affects the performance of a cryogenically cooled monochromator under intense X-ray Free-Electron Laser pulses. The measurements are in good agreement with a depth-uniform model of X-ray dynamical diffraction taking beam absorption and heat deformation of the crystals into account.
description: 9 pages, 4 figures, to be published in Optics Express
Bifurcations in a convection problem with temperature-dependent viscosity
Creators: name: Pla, Francisco
name: Herrero, Henar
name: Lafitte, Olivier
Publisher: name: arXiv
Year: 2008
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: A convection problem with temperature-dependent viscosity in an infinite layer is presented. As described, this problem has important applications in mantle convection. The existence of a stationary bifurcation is proved together with a condition to obtain the critical parameters at which the bifurcation takes place. For a general dependence of viscosity with temperature a numerical strategy for the calculation of the critical bifurcation curves and the most unstable modes has been developed. For a exponential dependence of viscosity on temperature the numerical calculations have been done. Comparisons with the classical Rayleigh-Bénard problem with constant viscosity indicate that the critical threshold decreases as the exponential rate parameter increases.
description: 16 pages, 5 figures
Additional file 1 of Exceeding the guideline-recommended maximum daily dose of opioids for long-term treatment of non-cancer pain in Germany – a large retrospective observational study
Creators: name: Schrader, Nils Frederik
name: Niemann, Anja
name: Weitzel, Milena
name: Speckemeier, Christian
name: Abels, Carina
name: Blase, Nikola
name: Giebel, Godwin Denk
name: Riederer, Cordula
name: Nadstawek, Joachim
name: Straßmeir, Wolfgang
name: Wasem, Jürgen
name: Neusser, Silke
Publisher: name: figshare
Year: 2024
Subjects: subject: Medicine
subject: Cell Biology
subject: Pharmacology
subject: Immunology
subject: FOS: Clinical medicine
subject: Cancer
subject: Science Policy

description: Additional File 1. PDF-document, .pdf. Additional File 1 – Dose calculation. Description of opioid dose calculation for the entire observation period and within follow-up quarters.
An Algebra of Pieces of Space -- Hermann Grassmann to Gian Carlo Rota
Creators: name: Crapo, Henry
Publisher: name: arXiv
Year: 2009
Subjects: subject: History and Overview (math.HO)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05B35

description: We sketch the outlines of Gian Carlo Rota's interaction with the ideas that Hermann Grassmann developed in his Ausdehnungslehre of 1844 and 1862, as adapted and explained by Giuseppe Peano in 1888. This leads us past what Rota variously called 'Grassmann-Cayley algebra', or 'Peano spaces', to the Whitney algebra of a matroid, and finally to a resolution of the question "What, really, was Grassmann's regressive product?". This final question is the subject of ongoing joint work with Andrea Brini, Francesco Regonati, and William Schmitt. The present paper was presented at the conference "The Digital Footprint of Gian-Carlo Rota: Marbles, Boxes and Philosophy" in Milano on 17 Feb 2009. It will appear in proceedings of that conference, to be published by Springer Verlag.
description: 28 pages
Ethnicity and residential location
Creators: name: Hier, Marlene F.
Publisher: name: University of British Columbia
Year: 2011

description: A predominant feature of Canadian society is the presence of a variety of ethnic minority groups which maintain distinctive values and patterns of behavior and which reside in readily identifiable ethnic concentrations. Literature describing ethnic minority residential clustering and dispersion stresses that because of the low socio-economic status of the members of these immigrant groups and because of their strong ethno-religious ties, they formed their own ethnic communities in urban core areas. As members, and their children and grandchildren particularly, improved their economic status and as their ethno-religious ties weakened, they began to move from the urban core ethnic concentration to ethnically mixed suburban communities. . This study focused upon Jews and Italians, two ethnic minorities which concentrate in ethnic clusters in the City of Vancouver and which have a substantial number of their members living in the suburban communities of Richmond, Burnaby, North Vancouver and West Vancouver. The research primarily addressed itself to exploring the associations between residential location and the following variables: ethno-religious identification, socio-economic status, generation status, and the nature and extent of social networks based on kith and kin. Responses to 157 questionnaires, which were administered to select groups of Jews, Italians, and Anglo-Saxons, were analyzed by multivariate statistical techniques. The results indicate that for both the Jewish and Italian groups, the intensity of ethno-religious identification is strongest among cluster residents. Although suburban groups, in general, display a less intense ethno-religious identification than do the cluster groups, they are not homogeneous in this respect. Residents of the Italian urban cluster belong mostly to the foreign-born generation. Second, third-, and subsequent - generations are more apt to locate in suburbia. Such is not the case for Jews. A substantial proportion of Jewish urban cluster residents are third - and subsequent - generation Jews. Stronger familial ties and more extensive friendships with members of the same ethnic group are characteristic of Jews and Italians resident in ethnic clusters compared to suburban ethnic members. For Italians, socio-economic status among cluster residents is significantly lower than that of most suburban Italians. For Jews, this it not the case. Jewish cluster residents are significantly higher in socio-economic status than most suburban Jews. Planners should be aware that ethnic minority groups are not homogeneous. They are internally differentiated by ethno-religious identification, socioeconomic status, generation status, and the extent and intensity of social networks. These differences should be considered in the formulation of plans.
Starburst-Driven Galactic Winds: Filament Formation and Emission Processes
Creators: name: Cooper, J. L.
name: Bicknell, G. V.
name: Sutherland, R. S.
name: Bland-Hawthorn, J.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We have performed a series of three-dimensional simulations of the interaction of a supersonic wind with a non-spherical radiative cloud. These simulations are motivated by our recent three-dimensional model of a starburst-driven galactic wind interacting with an inhomogeneous disk, which show that an optically emitting filament can be formed by the break-up and acceleration of a cloud into a supersonic wind. In this study we consider the evolution of a cloud with two different geometries (fractal and spherical) and investigate the importance of radiative cooling on the cloud's survival. We have also undertaken a comprehensive resolution study in order to ascertain the effect of the assumed numerical resolution on the results. We find that the ability of the cloud to radiate heat is crucial for its survival. While an adiabatic cloud is destroyed over a short period of time, a radiative cloud is broken up via the Kelvin-Helmholtz instability into numerous small, dense cloudlets, which are drawn into the flow to form a filamentary structure. The degree of fragmentation is highly dependent on the resolution of the simulation, with the number of cloudlets formed increasing as the Kelvin-Helmholtz instability is better resolved. Nevertheless, there is a clear qualitative trend, with the filamentary structure still persistent at high resolution. We confirm the mechanism behind the formation of the H-alpha emitting filaments found in our global simulations of a starburst-driven wind. Based on our resolution study, we conclude that bow shocks around accelerated gas clouds, and their interaction, are the main source of the soft X-ray emission observed in these galactic-scale winds. [ABRIDGED]
description: Accepted to ApJ, 39 pages, 21 figures, movie file can obtained at http://www.mso.anu.edu.au/~jcooper/movie/halpha.mov
Photonic random walks with traps
Creators: name: Longhi, Stefano
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Random walks behave very differently for classical and quantum particles. Here we unveil a ubiquitous distinctive behavior of random walks of a photon in a one-dimensional lattice in the presence of a finite number of traps, at which the photon can be destroyed and the walk terminates. While for a classical random walk the photon is unavoidably destroyed by the traps, for a quantum walk the photon can remain alive and the walk continues forever. Such an intriguing behavior is illustrated by considering photonic random walks in synthetic mesh lattices with controllable decoherence, which enables to switch from quantum to classical random walks.
description: 6 pages, 3 figures, accepted for publication in Optics Letters
Elastic stability of Ga$_2$O$_3$: Addressing the $β$ to $α$ phase transition from first principles
Creators: name: Lion, Konstantin
name: Pavone, Pasquale
name: Draxl, Claudia
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Elastic and structural properties of $β$-Ga$_2$O$_3$ and $α$-Ga$_2$O$_3$ are investigated from first principles. The full elastic tensors and elastic moduli of both phases at $0$ K are computed in the framework of semi-local density-functional theory. We determine mechanical instabilities of $β$-Ga$_2$O$_3$ by evaluating the full stiffness tensor under load for a range of hydrostatic pressure values. While a phase transition from the $β$ to $α$ phase is found to be energetically favored at $2.6$ GPa, we show that the $β$ phase is only mechanically unstable for much higher pressures ($>30$ GPa), which agrees well with experimental results. Our employed approach is based on the Born stability criterion, is independent of crystal symmetry, and thus can be readily applied to different materials.
description: 8 pages, 3 figures, 5 tables
Dephasing-induced mobility edges in quasicrystals
Creators: name: Longhi, Stefano
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Physics (quant-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Mobility edges (ME), separating Anderson-localized states from extended states, are known to arise in the single-particle energy spectrum of certain one-dimensional lattices with aperiodic order. Dephasing and decoherence effects are widely acknowledged to spoil Anderson localization and to enhance transport, suggesting that ME and localization are unlikely to be observable in the presence of dephasing. Here it is shown that, contrary to such a wisdom, ME can be created by pure dephasing effects in quasicrystals in which all states are delocalized under coherent dynamics. Since the lifetimes of localized states induced by dephasing effects can be extremely long, rather counter-intuitively decoherence can enhance localization of excitation in the lattice. The results are illustrated by considering photonic quantum walks in synthetic mesh lattices.
description: 17 pages, 9 figures (main text + supplementary material), accepted for publication in the Physical Review Letters
Geometry of pure states of N spin-J system
Creators: name: Kolenderski, Piotr
Publisher: name: arXiv
Year: 2009
Subjects: subject: Quantum Physics (quant-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We present the geometry of pure states of an ensemble of N spin-J systems using a generalisation of the Majorana representation. The approach is based on Schur-Weyl duality that allows for simple interpretation of the state transformation under the action of general linear and permutation groups. We show an exemplary application in theory of decoherence free subspaces and noiseless subsystems.
A Proposal of Automatic Error Correction in Text
Creators: name: Luna-Ramírez, Wulfrano A.
name: Jaimez-González, Carlos R.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computation and Language (cs.CL)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: The great amount of information that can be stored in electronic media is growing up daily. Many of them is got mainly by typing, such as the huge of information obtained from web 2.0 sites; or scaned and processing by an Optical Character Recognition software, like the texts of libraries and goverment offices. Both processes introduce error in texts, so it is difficult to use the data for other purposes than just to read it, i.e. the processing of those texts by other applications like e-learning, learning of languages, electronic tutorials, data minning, information retrieval and even more specialized systems such as tiflologic software, specifically blinded people-oriented applications like automatic reading, where the text would be error free as possible in order to make easier the text to speech task, and so on. In this paper it is showed an application of automatic recognition and correction of ortographic errors in electronic texts. This task is composed of three stages: a) error detection; b) candidate corrections generation; and c) correction -selection of the best candidate. The proposal is based in part of speech text categorization, word similarity, word diccionaries, statistical measures, morphologic analisys and n-grams based language model of Spanish.
description: 15 pages, 3 figures, 11 tables, 1 algorithm. Formerly published on Journal of Research in Computer Science - Intl Conference on Computer CORE2012
Tests of Electric Polarizability on the Lattice
Creators: name: Guerrero, Victor X.
name: Wilcox, Walter
name: Christensen, Joe
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: Using clover fermions on CP-PACS dynamical configurations, we consider a number of ways of measuring hadronic electric polarizability, an $|\mathbf{E}|^{2}$ effect in hadron masses, using lattice techniques. We consider the effects of periodic and Dirichlet boundary conditions, the field linearization postulate as well as a quantized electric field. We also consider two ways of formulating the classical vector potential which describes a uniform electric field in combination with the other possibilities.
description: Presented at 26th International Symposium on Lattice Field Theory, Williamsburg, VA, USA, 14-19 Jul 2008