cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Quark orbital angular momentum: can we learn about it from GPDs and TMDs?
Creators: name: Avakian, H.
name: Efremov, A. V.
name: Schweitzer, P.
name: Teryaev, O. V.
name: Zavada, P.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: It is known how to access information on quark orbital angular momentum from generalized parton distribution functions, in a certain specified framework. It is intuitively expected, that such information can be accessed also through transverse momentum dependent distribution functions, but not known how. Now quark models provide promising hints. Recent results are reviewed.
description: proceeding of the "4th Workshop on Exclusive Reactions at High Momentum Transfer," 18-21 May 2010, Jefferson Lab
Analytical Model of the Evolution of Surface Topography During Sliding Wear
Creators: name: Brunetière, Noël
Publisher: name: arXiv
Year: 2025
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: During the wear process of surfaces in sliding friction, there is a running-in period during which the topography of surfaces changes with time before reaching the steady wear regime. In the steady wear regime, the statistical parameters used to describe the topography of the surfaces remain almost constant. Some experimental studies have shown that starting friction tests with different surface finish levels leads to the same final topography of surfaces in the regime of steady wear. This article proposes an analytical model to describe the evolution of the topography of surfaces during sliding wear. First of all, the Greenwood and Williamson approach is used to describe the contact between nominally flat rough surfaces. The asperities in contact may undergo plastic deformation or adhesion with the opposing surface. Using a plasticity criterion and an adhesion criterion, it is possible to obtain a differential equation for the evolution of the standard deviation of the asperities of the surfaces. This equation has an analytical solution that is in good agreement with experimental results from the literature. It is shown that the final surface topography is the result of the competition between abrasive wear and adhesive wear. The model is then used to describe different wear processes from polishing to galling.
Analytical model of brittle destruction based on hypothesis of scale similarity
Creators: name: Arakcheev, A. S.
name: Lotov, K. V.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: The size distribution of dust particles in nuclear fusion devices is close to the power function. A function of this kind can be the result of brittle destruction. From the similarity assumption it follows that the size distribution obeys the power law with the exponent between -4 and -1. The model of destruction has much in common with the fractal theory. The power exponent can be expressed in terms of the fractal dimension. Reasonable assumptions on the shape of fragments concretize the power exponent, and vice versa possible destruction laws can be inferred on the basis of measured size distributions.
description: 10 pages, 3 figures
Curvatures on the Teichmüller curve
Creators: name: Guo, Ren
name: Gupta, Subhojoy
name: Huang, Zheng
Publisher: name: arXiv
Year: 2010
Subjects: subject: Differential Geometry (math.DG)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 32G15, 53C43, 53C21

description: The Teichmüller curve is the fiber space over Teichmüller space of closed Riemann surfaces, where the fiber over a point in Teichmüller space is the underlying surface. We derive formulas for sectional curvatures on the Teichmüller curve. In particular, our method can be applied to investigate the geometry of the Weil-Petersson geodesic as a three-manifold, and the degeneration of the curvatures near the infinity of the augmented Teichmüller space along a Weil-Petersson geodesic, as well as the minimality of hyperbolic surfaces in this three-manifold.
description: 16 pages
Towards Microscopic Ab Initio Calculations of Astrophysical S-Factors
Creators: name: Neff, Thomas
name: Feldmeier, Hans
name: Langanke, Karlheinz
Publisher: name: arXiv
Year: 2010
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Low energy capture cross sections are calculated within a microscopic many-body approach using an effective Hamiltonian derived from the Argonne V18 potential. The dynamics is treated within Fermionic Molecular Dynamics (FMD) which uses a Gaussian wave-packet basis to represent the many-body states. A phase-shift equivalent effective interaction derived within the Unitary Correlation Operator Method (UCOM) that treats explicitly short-range central and tensor correlations is employed. As a first application the 3He(alpha,gamma)7Be reaction is presented. Within the FMD approach the microscopic many-body wave functions of the 3/2- and 1/2- bound states in 7Be as well as the many-body scattering states in the 1/2+, 3/2+ and 5/2+ channels are calculated as eigenstates of the same microscopic effective Hamiltonian. Finally the S-factor is calculated from E1 transition matrix elements between the many-body scattering and bound states. For 3He(alpha,gamma)7Be the S-factor agrees very well, both in absolute normalization and energy dependence, with the recent experimental data from the Weizmann, LUNA, Seattle and ERNA experiments. For the 3H(alpha,gamma)7Li reaction the calculated S-factor is about 15% above the data.
Classical Physics of Thermal Scalar Radiation in Two Spacetime Dimensions
Creators: name: Boyer, Timothy H.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: Thermal scalar radiation in two spacetime dimensions is treated within relativistic classical physics. Part I involves an inertial frame where are given the analogues both of Boltzmann's derivation of the Stefan-Boltzmann law and also Wien's derivation of the displacement theorem using the scaling of relativitic radiation theory. Next the spectrum of classical scalar zero-point radiation in an inertial frame is derived both from scale invariance and from Lorentz invariance. Part II involves the behavior of thermal radiation in a coordinate frame undergoing (relativistic) constant acceleration, a Rindler frame. The radiation normal modes in a Rindler frame are obtained. The classical zero-point radiation of inertial frames is transformed over to the coordinates of a Rindler frame. Although for zero-point radiation the two-field correlation function at different spatial points at a single time is the same between inertial and Rindler frames, the correlation function at two different times at a single Rindler spatial coordinate is different, and has a natural extension to non-zero temperature. The thermal spectrum in the Rindler frame is then transferred back to an inertial frame, giving the familar Planck spectrum.
description: 31 pages
Change‐Point Detection in the Conditional Correlation Structure of Multivariate Volatility Models
Creators: name: Barassi, Marco
name: Horváth, Lajos
name: Zhao, Yuqian
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: Cancer
subject: Science Policy

description: We propose semiparametric CUSUM tests to detect a change-point in the correlation structures of nonlinear multivariate models with dynamically evolving volatilities. The asymptotic distributions of the proposed statistics are derived under mild conditions. We discuss the applicability of our method to the most often used models, including constant conditional correlation (CCC), dynamic conditional correlation (DCC), BEKK, corrected DCC, and factor models. Our simulations show that, our tests have good size and power properties. Also, even though the near-unit root property distorts the size and power of tests, de-volatizing the data by means of appropriate multivariate volatility models can correct such distortions. We apply the semiparametric CUSUM tests in the attempt to date the occurrence of financial contagion from the US to emerging markets worldwide during the great recession. Supplementary materials for this article are available online.
Model-Independent Searches for New Quarks at the LHC
Creators: name: Atre, Anupama
name: Azuelos, Georges
name: Carena, Marcela
name: Han, Tao
name: Ozcan, Erkcan
name: Santiago, José
name: Unel, Gokhan
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: New vector-like quarks can have sizable couplings to first generation quarks without conflicting with current experimental constraints. The coupling with valence quarks and unique kinematics make single production the optimal discovery process. We perform a model-independent analysis of the discovery reach at the Large Hadron Collider for new vector-like quarks considering single production and subsequent decays via electroweak interactions. An early LHC run with 7 TeV center of mass energy and 1 fb-1 of integrated luminosity can probe heavy quark masses up to 1 TeV and can be competitive with the Tevatron reach of 10 fb-1. The LHC with 14 TeV center of mass energy and 100 fb-1 of integrated luminosity can probe heavy quark masses up to 3.7 TeV for order one couplings.
description: 37 pages, 11 figures, 7 tables
A possible mathematics for the unification of quantum mechanics and general relativity
Creators: name: Kryukov, Alexey A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: This paper summarizes and generalizes a recently proposed mathematical framework that unifies the standard formalisms of special relativity and quantum mechanics. The framework is based on Hilbert spaces H of functions of four space-time variables x,t, furnished with an additional indefinite inner product invariant under Poincaré transformations, and isomorphisms of these spaces that preserve the indefinite metric. The indefinite metric is responsible for breaking the symmetry between space and time variables and for selecting a family of Hilbert subspaces that are preserved under Galileo transformations. Within these subspaces the usual quantum mechanics with Schrödinger evolution and t as the evolution parameter is derived. Simultaneously, the Minkowski space-time is isometrically embedded into H, Poincaré transformations have unique extensions to isomorphisms of H and the embedding commutes with Poincaré transformations. The main new result is a proof that the framework accommodates arbitrary pseudo-Riemannian space-times furnished with the action of the diffeomorphism group.
Strategy report for offering traceable calibration for testing machines under continuous and dynamic forces
Creators: name: Jonas, Sander
name: Kumme Rolf
name: Falk, Tegtmeier
name: Davood, Mirian
name: Miha, Hiti
name: Nitschke Arnd
name: Gerber Siegfried
name: Mikolaj, Wozniak
name: Andy, Knott
name: Vavrečka, Lukáš
name: Haldun, Dizdar
name: Bulent, Aydemir
name: Korhonen Jani
name: Soares, Oliveira Rafael
name: Machado Renato, R.
Publisher: name: Zenodo
Year: 2023
Subjects: ComTraForce
continuous force
dynamic force
strategy report
calibration procedure

description: The first part of the document delivers the strategy to amend the developed continuous force calibration procedure of testing machines, in the form of three proposed annexes to the ISO standards ISO 376 and ISO 7500-1 (see figure 1). Details of these two standards are provided together with details of how the proposed annexes could be incorporated. The second part of the document delivers the required strategy to implement the developed calibration procedure for the dynamic calibration of material testing machines within a new guideline document DKD-R 9-4, which uses for traceability the existing standards ISO 376, DKD-R 3-2 and DKD-R 3-10 Sheet 2 (see figure 2). Details of these existing standards are described below, together with details of how the proposed guideline shall be implemented.
description: The ComTraForce project 18SIB08 has received funding from the European Metrology Programme for Innovation and Research (EMPIR) as well as the European Association of National Metrology Institutes (Euramet).
title: Investigation of the industrial NH3 oxidation by CFD simulations including detailed surface kinetics
Creators: name: Wiser, Artur
Publisher: name: UNSPECIFIED
Year: 2020

description: In the Ostwald process ammonia is catalytically oxidized to NO at short contact times on platinum/rhodium gauzes. Besides NO as main product, N2 and N2O are also produced. Especially the formation of N2O is critical because of its large environmental influence as greenhouse gas. This work describes a modelling approach where a mechanistic model of ammonia oxidation on platinum previously published by Kraehnert and Baerns was implemented in a CFD simulation using the rate mapping approach. Three main application fields for this modelling approach have been handled in this work and the following has been found: • Geometry influence on the process performance of the catalytic gauze The design of catalyst geometries can be improved using the knowledge which has been acquired by CFD simulations with included detailed kinetics. The geometry of the gauzes can be designed avoiding the area with “hot spot” mass transfer coefficients and increased N2O production. Furthermore, using the CFD simulations, the prototype for the geometry can be modeled and tested “in silico” without producing a large number of test samples. This will reduce the costs needed for the design process and the time to market for a new catalysts geometry. • Influence of the catalyst surface restructuring on the process performance It has been shown that the selectivity on the restructured surface are not uniform. The cauliflower excrescences are much stronger involved in the ongoing reaction and produce the largest amount of N2O. • CFD modelling of the laboratory scale reactor including complex chemistry on the wire gauzes. It was found that the existing reactor has very strong wall effects, which influence the production rates of NO and N2O. The heat loss of the catalyst to the wall has a significant impact. Due to a large catalyst area with a low temperature, the production of N2O becomes very high.
The Role of Jumps in Volatility Spillovers in Foreign Exchange Markets: Meteor Shower and Heat Waves Revisited
Creators: name: Lahaye, Jérôme
name: Neely, Christopher
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Biophysics
subject: Genetics
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Evolutionary Biology
subject: 69999 Biological Sciences not elsewhere classified
subject: Cancer
subject: Science Policy

description: This article extends the literature on geographic (heat waves) and intertemporal (meteor showers) foreign exchange volatility transmission to characterize the role of jumps and cross-rate propagation. We employ multivariate heterogenous autoregressive (HAR) models to capture the quasi-long memory properties of volatility and both Shapley–Owen R2’s and portfolio optimization exercises to quantify the contributions of information sets. We conclude that meteor showers (MS) are substantially more influential than heat waves (HW), that jumps play a modest but significant role in volatility transmission, that cross-market propagation of volatility is important, and that allowing for differential HW and MS effects and differential parameters across intraday market segments is valuable. Finally, we illustrate what types of news weaken or strengthen heat wave, meteor shower, continuous, and jump patterns with sensitivity analysis. Supplementary materials for this article are available online.
Repair of magnetism in oxidized graphene nanoribbons
Creators: name: Boukhvalov, D. W.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Novel route for the establishing of magnetism in realistic oxidized graphene nanoribbons is proposed. Modelling of the migration of hydroxyl groups from central part to the zig-zag edges of graphene nanoribbons passivated by oxygen are performed with using density functional theory. The presence of hydroxyl groups near the edges leads formation of dangling bonds there instead saturated due to oxidation and repairs of magnetism diminished by edges oxidation. The route of manufacturing and stability of new type of magnetic graphene nanoribbons are also discussed.
description: 14 pages 6 figures, accepted to Chem. Phys. Lett
Emerging multidisciplinary research across database management systems
Creators: name: Nica, Anisoara
name: Suchanek, Fabian
name: Varde, Aparna
Publisher: name: arXiv
Year: 2011
Subjects: subject: Databases (cs.DB)
subject: FOS: Computer and information sciences

description: The database community is exploring more and more multidisciplinary avenues: Data semantics overlaps with ontology management; reasoning tasks venture into the domain of artificial intelligence; and data stream management and information retrieval shake hands, e.g., when processing Web click-streams. These new research avenues become evident, for example, in the topics that doctoral students choose for their dissertations. This paper surveys the emerging multidisciplinary research by doctoral students in database systems and related areas. It is based on the PIKM 2010, which is the 3rd Ph.D. workshop at the International Conference on Information and Knowledge Management (CIKM). The topics addressed include ontology development, data streams, natural language processing, medical databases, green energy, cloud computing, and exploratory search. In addition to core ideas from the workshop, we list some open research questions in these multidisciplinary areas.
From signalling to cell behaviour : modelling multi-scale organization in single and collective cellular systems
Creators: name: Zmurchok, Cole
Publisher: name: University of British Columbia
Year: 2018

description: Individually and collectively, cells are organized systems with many interacting parts. Mathematical models allow us to infer behaviour at one level of organization from information at another level. In this thesis, I explore two biological questions that are answered through the development of new mathematical approaches and novel models. (1) Molecular motors are responsible for transporting material along molecular tracks (microtubules) in cells. Typically, transport is described by a system of reaction-advection-diffusion partial differential equations (PDEs). Recently, quasi-steady-state (QSS) methods have been applied to models with linear reactions to approximate the behaviour of the PDE system. To understand how nonlinear reactions affect the overall transport process at the cellular level, I extend the QSS approach to certain nonlinear reaction models, reducing the full PDE system to a single nonlinear PDE. I find that the approximating PDE is a conservation law for the total density of motors within the cell, with effective diffusion and velocity that depend nonlinearly on the motor densities and model parameters. Cell-scale predictions about the organization and distribution of motors can be drawn from these effective parameters. (2) Rho GTPases are a family of protein regulators that modulate cell shape and forces exerted by cells. Meanwhile, cells sense forces such as tension. The implications of this two-way feedback on cell behaviour is of interest to biologists. I explore this question by developing a simple mathematical model for GTPase signalling and cell mechanics. The model explains a spectrum of behaviours, including relaxed or contracted cells and cells that oscillate between these extremes. Through bifurcation analysis, I find that changes in single cell behaviour can be explained by the strength of feedback from tension to signalling. When such model cells are connected to one another in a row or in a 2D sheet, waves of contraction/relaxation propagate through the tissue. Model predictions are qualitatively consistent with developmental-biology observations such as the volume fluctuations in a cellular monolayer. The model suggests a mechanism for the organization of tissue-scale behaviours from signalling and mechanics, which could be extended to specific experimental systems.
Manganese Abundances in the Globular Cluster Omega Centauri
Creators: name: Cunha, Katia
name: Smith, Verne V.
name: Bergemann, Maria
name: Suntzeff, Nicholas B.
name: Lambert, David L.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present manganese abundances in 10 red-giant members of the globular cluster Omega Centauri; 8 stars are from the most metal-poor population (RGB MP and RGB MInt1) while two targets are members of the more metal rich groups (RGB MInt2 and MInt3). This is the first time Mn abundances have been studied in this peculiar stellar system. The LTE values of [Mn/Fe] in Omega Cen overlap those of Milky Way stars in the metal poor Omega Cen populations ([Fe/H] ~ -1.5 to -1.8), however unlike what is observed in Milky Way halo and disk stars, [Mn/Fe] declines in the two more metal-rich RGB MInt2 and MInt3 targets. Non-LTE calculations were carried out in order to derive corrections to the LTE Mn abundances. The non-LTE results for Omega Cen in comparison with the non-LTE [Mn/Fe] versus [Fe/H] trend obtained for the Milky Way confirm and strengthen the conclusion that the manganese behavior in Omega Cen is distinct. These results suggest that low-metallicity supernovae (with metallicities < -2) of either Type II or Type Ia dominated the enrichment of the more metal-rich stars in Omega Cen. The dominance of low-metallicity stars in the chemical evolution of Omega Cen has been noted previously in the s-process elements where enrichment from metal-poor AGB stars is indicated. In addition, copper, which also has metallicity dependent yields, exhibits lower values of [Cu/Fe] in the RGB MInt2 and MInt3 Omega Cen populations.
description: Accepted for publication in the ApJ
Enhanced Inflation in the Dirac-Born-Infeld framework
Creators: name: Chimento, L. P.
name: Lazkoz, R.
name: Richarte, M. G.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We consider the Einstein equations within the DBI scenario for a spatially flat Friedmann-Robertson-Walker (FRW) spacetime without a cosmological constant. We derive the inflationary scenario by applying the symmetry transformations which preserve the form of the Friedmann and conservation equations. These form invariance transformations generate a symmetry group parametrized by the Lorentz factor $\ga$. We explicitly obtain an inflationary scenario by the cooperative effect of adding energy density into the Friedmann equation. For the case of a constant Lorentz factor, and under the slow roll assumption, we find the transformation rules for the scalar and tensor power spectra of perturbations as well as their ratio under the action of the form invariance symmetry group. Within this case and due to its relevance for the inflationary paradigm, we find the general solution of the dynamical equations for a DBI field driven by an exponential potential and show a broad set of inflationary solutions. The general solution can be split into three subsets and all these behave asymptotically as a power law solution at early and at late times.
description: 9 pages, revtex 4.1
Is a Normal Copula the Right Copula?
Creators: name: Amengual, Dante
name: Sentana, Enrique
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Neuroscience
subject: Biotechnology
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics
subject: Cancer
subject: Science Policy

description: We derive computationally simple and intuitive expressions for score tests of Gaussian copulas against generalized hyperbolic alternatives, including symmetric and asymmetric Student t, and many other examples. We decompose our tests into third and fourth moment components, and obtain one-sided Likelihood Ratio analogs, whose standard asymptotic distribution we provide. Our Monte Carlo exercises confirm the reliable size of parametric bootstrap versions of our tests, and their substantial power gains over alternative procedures. In an empirical application to CRSP stocks, we find that short-term reversals and momentum effects are better captured by non-Gaussian copulas, whose parameters we estimate by indirect inference. Supplementary materials for this article are available online.
Curvature properties and isotropic planes of Riemannian and almost Hermitian manifolds of indefinite metrics
Creators: name: Borisov, Adrijan
name: Ganchev, Georgi
name: Kassabov, Ognian
Publisher: name: arXiv
Year: 2010
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53B30

description: We study two types of isotropic planes: weakly isotropic and strongly isotropic planes. We prove that a Riemannian manifold of indefinite metric is conformally flat if and only if its curvature tensor vanishes on all the strongly isotropic planes. We specialize the plane axiom for Riemannian manifolds of indefinite metrics. We show that manifolds satisfying plane axiom of weakly (strongly) isotropic planes are of constant sectional curvature (conformaly flat). Further we study analogous problems on almost Hermitian manifolds of indefinite metrics.
description: 11 pages
A Comparison of Two Quantile Models With Endogeneity
Creators: name: Wüthrich, Kaspar
Publisher: name: Taylor & Francis
Year: 2019
Subjects: subject: Medicine
subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics
subject: Science Policy

description: This article studies the relationship between the two most-used quantile models with endogeneity: the instrumental variable quantile regression (IVQR) model (Chernozhukov and Hansen 2005) and the local quantile treatment effects (LQTE) model (Abadie, Angrist, and Imbens 2002). The key condition of the IVQR model is the rank similarity assumption, a restriction on the evolution of individual ranks across treatment states, under which population quantile treatment effects (QTE) are identified. By contrast, the LQTE model achieves identification through a monotonicity assumption on the selection equation but only identifies QTE for the subpopulation of compliers. This article shows that, despite these differences, there is a close connection between both models: (i) the IVQR estimands correspond to QTE for the compliers at transformed quantile levels and (ii) the IVQR estimand of the average treatment effect is equal to a convex combination of the local average treatment effect and a weighted average of integrated QTE for the compliers. These results do not rely on the rank similarity assumption and therefore provide a characterization of IVQR in settings where this key condition is violated. Underpinning the analysis are novel closed-form representations of the IVQR estimands. I illustrate the theoretical results with two empirical applications.
An Improved Metallicity Calibration with UBV Photometry
Creators: name: Karaali, S.
name: Bilir, S.
name: Ak, S.
name: Yaz, E.
name: Coskunoglu, B.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We used the data of 701 stars covering the colour index interval 0.32
description: 12 pages, including 10 figures and 6 tables, accepted for publication in PASA
Unveiling the Structure of Pre-Transitional Disks
Creators: name: Espaillat, C.
name: D'Alessio, P.
name: Hernández, J.
name: Nagel, E.
name: Luhman, K. L.
name: Watson, D. M.
name: Calvet, N.
name: Muzerolle, J.
name: McClure, M.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: In the past few years, several disks with inner holes that are empty of small dust grains have been detected and are known as transitional disks. Recently, Spitzer has identified a new class of "pre-transitional disks" with gaps; these objects have an optically thick inner disk separated from an optically thick outer disk by an optically thin disk gap. A near-infrared spectrum provided the first confirmation of a gap in the pre-transitional disk of LkCa 15 by verifying that the near-infrared excess emission in this object was due to an optically thick inner disk. Here we investigate the difference between the nature of the inner regions of transitional and pre-transitional disks using the same veiling-based technique to extract the near-infrared excess emission above the stellar photosphere. We show that the near-infrared excess emission of the previously identified pre-transitional disks of LkCa 15 and UX Tau A in Taurus as well as the newly identified pre-transitional disk of ROX 44 in Ophiuchus can be fit with an inner disk wall located at the dust destruction radius. We also model the broad-band SEDs of these objects, taking into account the effect of shadowing by the inner disk on the outer disk, considering the finite size of the star. The near-infrared excess continua of these three pre-transitional disks, which can be explained by optically thick inner disks, are significantly different from that of the transitional disks of GM Aur, whose near-infrared excess continuum can be reproduced by emission from sub-micron-sized optically thin dust, and DM Tau, whose near-infrared spectrum is consistent with a disk hole that is relatively free of small dust. The structure of pre-transitional disks may be a sign of young planets forming in these disks and future studies of pre-transitional disks will provide constraints to aid in theoretical modeling of planet formation.
description: Accepted for publication in ApJ on May 10, 2010; 29 pages
Is a normal copula the right copula?
Creators: name: Amengual, Dante
name: Sentana, Enrique
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Neuroscience
subject: Biotechnology
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics
subject: Science Policy

description: We derive computationally simple and intuitive expressions for score tests of Gaussian copulas against Generalized Hyperbolic alternatives, including symmetric and asymmetric Student t, and many other examples. We decompose our tests into third and fourth moment components, and obtain one-sided Likelihood Ratio analogues, whose standard asymptotic distribution we provide. Our Monte Carlo exercises confirm the reliable size of parametric bootstrap versions of our tests, and their substantial power gains over alternative procedures. In an empirical application to CRSP stocks, we find that short-term reversals and momentum effects are better captured by non-Gaussian copulas, whose parameters we estimate by indirect inference.
The stellar evolution of Luminous Red Galaxies, and its dependence on colour, redshift, luminosity and modelling
Creators: name: Tojeiro, Rita
name: Percival, Will J.
name: Heavens, Alan F.
name: Jimenez, Raul
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present a series of colour evolution models for Luminous Red Galaxies (LRGs) in the 7th spectroscopic data release of the Sloan Digital Sky Survey (SDSS), computed using the full-spectrum fitting code VESPA on high signal-to-noise stacked spectra. The colour-evolution models are computed as a function of colour, luminosity and redshift, and we do not a-priori assume that LRGs constitute a uniform population of galaxies in terms of stellar evolution. By computing star-formation histories from the fossil record, the measured stellar evolution of the galaxies is decoupled from the survey's selection function, which also evolves with redshift. We present these evolutionary models computed using three different sets of Stellar Population Synthesis (SPS) codes. We show that the traditional fiducial model of purely passive stellar evolution of LRGs is broadly correct, but it is not sufficient to explain the full spectral signature. We also find that higher-order corrections to this model are dependent on the SPS used, particularly when calculating the amount of recent star formation. The amount of young stars can be non-negligible in some cases, and has important implications for the interpretation of the number density of LRGs within the selection box as a function of redshift. Dust extinction, however, is more robust to the SPS modelling: extinction increases with decreasing luminosity, increasing redshift, and increasing r-i colour. We are making the colour evolution tracks publicly available at http://www.icg.port.ac.uk/~tojeiror/lrg_evolution/.
description: 29 pages, 34 figures, re-submitted to MNRAS after addressing the referee's report
- Inscription on the image of Umāmaheśvara from Tepe Skandar
Creators: name: Shoshin Kuwayama
Publisher: name: Zenodo
Year: 2020

description: [caption id="attachment_6333" align="alignnone" width="344"] Tepe Skandar (Afghanistan). Transcription and rubbing of the Umāmaheśvara inscription.[/caption] Working transcription 12/2020.
Correlated Supernova Systematics and Ground Based Surveys
Creators: name: Kim, Alex G.
name: Linder, Eric V.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Supernova distances provide a direct probe of cosmic acceleration, constraining dark energy. This leverage increases with survey redshift depth at a rate bounded by the systematic uncertainties. We investigate the impact of a wavelength-dependent, global correlation model of systematics in comparison to the standard local-redshift correlation model. This can arise from subclass uncertainties as features in the supernova spectrum redshift out of the observer photometric filters or spectral range. We explore the impact of such a systematic on ground-based supernova surveys such as Dark Energy Survey and LSST, finding distinctive implications. Extending the wavelength sensitivity to 1.05 microns through "extreme red" CCDs can improve the dark energy figure of merit by up to a factor 2.
description: 8 pages, 5 figures
The tidal tails of NGC 2298
Creators: name: Balbinot, Eduardo
name: Santiago, Basílio X.
name: da Costa, Luiz N.
name: Makler, Martin
name: Maia, Marcio A. G.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present an implementation of the matched-filter technique to detect tidal tails of globular clusters. The method was tested using SDSS data for the globular cluster Palomar 5 revealing its well known tidal tails. We also ran a simulation of a globular cluster with a tidal tail where we successfully recover the tails for a cluster at the same position and with the same characteristics of NGC 2298. Based on the simulation we estimate that the matched-filter increases the contrast of the tail relative to the background of stars by a factor of 2.5 for the case of NGC 2298. We also present the photometry of the globular cluster NGC 2298 using the MOSAIC2 camera installed on the CTIO 4m telescope. The photometry covers ~ 3deg2 reaching V ~ 23. A fit of a King profile to the radial density profile of NGC 2298 shows that this cluster has a tidal radius of 15.91' \pm 1.07' which is twice as in the literature. The application of the matched-filter to NGC 2298 reveals several extra-tidal structures, including a leading and trailing tail. We also find that NGC 2298 has extra-tidal structures stretching towards and against the Galactic disk, suggesting strong tidal interaction. Finally, we assess how the matched-filter performs when applied to a globular cluster with and without mass segregation taken into account. We find that disregarding the effects of mass segregation may significantly reduce the detection limit of the matched-filter.
description: 11 pages, 9 figures, 1 table. Accepted for publication on MNRAS main journal
Words are the New Numbers: A Newsy Coincident Index of the Business Cycle
Creators: name: Thorsrud, Leif Anders
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Medicine
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: Science Policy
subject: 110309 Infectious Diseases
subject: FOS: Health sciences

description: I construct a daily business cycle index based on quarterly GDP growth and textual information contained in a daily business newspaper. The newspaper data are decomposed into time series representing news topics, while the business cycle index is estimated using the topics and a time-varying dynamic factor model where dynamic sparsity is enforced upon the factor loadings using a latent threshold mechanism. The resulting index classifies the phases of the business cycle with almost perfect accuracy and provides broad-based high-frequency information about the type of news that drive or reflect economic fluctuations. In out-of-sample nowcasting experiments, the model is competitive with forecast combination systems and expert judgment, and produces forecasts with predictive power for future revisions in GDP. Thus, news reduces noise. Supplementary materials for this article are available online.
Competition between pairing and ferromagnetic instabilities in ultracold Fermi gases near Feshbach resonances
Creators: name: Pekker, David
name: Babadi, Mehrtash
name: Sensarma, Rajdeep
name: Zinner, Nikolaj
name: Pollet, Lode
name: Zwierlein, Martin W.
name: Demler, Eugene
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We study the quench dynamics of a two-component ultracold Fermi gas from the weak into the strong interaction regime, where the short time dynamics are governed by the exponential growth rate of unstable collective modes. We obtain an effective interaction that takes into account both Pauli blocking and the energy dependence of the scattering amplitude near a Feshbach resonance. Using this interaction we analyze the competing instabilities towards Stoner ferromagnetism and pairing.
description: 4+epsilon pages, 4 figures
Understanding online consumers' utilization of multiple advice sources
Creators: name: Kim, Hongki
Publisher: name: University of British Columbia
Year: 2018

description: As increasing numbers of online stores provide multiple advice sources and increasing numbers of shoppers access these sources on the Internet, shoppers develop decision-making strategies to manage a wide variety of information, some of it conflicting. By identifying these decision-making strategies, information system scholars have developed theoretical foundations for designing decision aids. However, few studies have investigated two important aspects: i) online shoppers’ new decision- making strategies in using multiple advice sources that offer diverse opinions; and ii) new decision aids that support such decision-making strategies. My research addresses this gap and consists of three laboratory-based studies. Study #1 identifies new consistency strategies that embed consistency as a key heuristic through verbal protocol analysis. It also shows that online shoppers use consistency strategies to identify products that deserve to be examined and support their belief in the quality of the products. Study #2 proposes consistency distance identification tools (CDITs) that present objective consistency/inconsistency measures as graphical representations. It also finds that the impact of the CDITs on decision quality and efforts is contingent on the fit between shoppers’ trustworthiness of advice sources, their goals in building a low/high level of understanding of advice sources and products, and the functionalities of the CDITs in supporting shoppers’ task and/or goals in the lab experiments. Study #3 proposes inconsistency reduction tools that clarify why advice sources are inconsistent by identifying the differences of preferences between the online shopper and advice sources, as well as facilitating interactions with a recommendation agent (RA). My research reveals two major findings: i) inconsistency among advice sources increases not only online shoppers’ attribution to the RA, but also the perceived incompetence and deceptiveness of the RA; and ii) utilization of inconsistency reduction tools decreases such online shoppers’ reactions to inconsistency among advice sources.
Radio pulsar populations
Creators: name: Lorimer, D. R.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The goal of this article is to summarize the current state of play in the field of radio pulsar statistics. Simply put, from the observed sample of objects from a variety of surveys with different telescopes, we wish to infer the properties of the underlying sample and to connect these with other astrophysical populations (for example supernova remnants or X-ray binaries). The main problem we need to tackle is the fact that, like many areas of science, the observed populations are often heavily biased by a variety of selection effects. After a review of the main effects relevant to radio pulsars, I discuss techniques to correct for them and summarize some of the most recent results. Perhaps the main point I would like to make in this article is that current models to describe the population are far from complete and often suffer from strong covariances between input parameters. That said, there are a number of very interesting conclusions that can be made concerning the evolution of neutron stars based on current data. While the focus of this review will be on the population of isolated Galactic pulsars, I will also briefly comment on millisecond and binary pulsars as well as the pulsar content of globular clusters and the Magellanic Clouds.
description: 16 pages, 6 figures, to appear in Proceedings of ICREA Workshop on The High-Energy Emission from Pulsars and their Systems, Sant Cugat, Spain, 2010 April 12-16 (Springer)
Old open clusters and the Galactic metallicity gradient: Berkeley 20, Berkeley 66, and Tombaugh 2
Creators: name: Andreuzzi, Gloria
name: Bragaglia, Angela
name: Tosi, Monica
name: Marconi, Gianni
Publisher: name: arXiv
Year: 2010
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: To study the crucial range of Galactocentric distances between 12 and 16 kpc, where little information is available, we have obtained VI CCD imaging of Berkeley 20 and BVI CCD imaging of Berkeley 66 and Tombaugh 2, three distant, old open clusters. Using the synthetic colour magnitude diagram (CMD) technique with three types of evolutionary tracks of different metallicities, we have determined age, distance, reddening and indicative metallicity of these systems. The CMD of Be 20 is best reproduced by stellar models with a metallicity about half of solar (Z=0.008 or 0.01), in perfect agreement with high resolution spectroscopic estimates. Its age is between 5 and 6 Gyr from stellar models with overshooting and between 4.3 and 4.5 Gyr from models without it. The distance modulus from the best fitting models is always (m-M)0=14.7 (corresponding to a Galactocentric radius of about 16 kpc), and the reddening E(B-V) ranges between 0.13 and 0.16. A slightly lower metallicity (Z ~ 0.006) appears to be more appropriate for Be 66. This cluster is younger, (age of 3 Gyr), and closer, (m-M)0=13.3 (i.e., at 12 kpc from the Galactic centre), than Be 20, and suffers from high extinction, 1.2 < E(B-V) < 1.3, variable at the 2-3 per cent level. Finally, the results for To 2 indicate that it is an intermediate age cluster, with an age of about 1.4 Gyr or 1.6-1.8 Gyr for models without and with overshooting, respectively. The metallicity is about half of solar (Z=0.006 to 0.01), in agreement with spectroscopic determinations. The distance modulus is (m-M)0=14.5, implying a distance of about 14 kpc from the Galactic centre; the reddening E(B-V) is 0.31-0.4, depending on the model and metallicity, with a preferred value around 0.34.
description: 19 pages, 19 figures, 8 tables Accepted 2010 November 5. Received 2010 November
Temperature switchable self-propulsion activity of liquid crystalline microdroplets
Creators: name: Kumar, Manoj
name: Sane, Siddharth
name: Murali, Aniruddh
name: Thutupalli, Shashi
Publisher: name: arXiv
Year: 2025
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We report on a switchable emulsion droplet microswimmer by utilizing a temperature-dependent transition of the droplet phase. The droplets, made from a liquid crystalline (LC) smectic phase material ($T =$ 25 $^{\circ}$C), self-propel only in their nematic and isotropic phases at elevated temperatures ($T\ge$ 33.5 $^{\circ}$C). This transition between motile and non-motile states is fully reversible - in the motile state, the droplets exhibit persistent motion and directional memory over multiple heating-cooling cycles. Further, we distinguish the state of rest from the state of motion by characterizing the chemical and hydrodynamic fields of the droplets. Next, we map the motility behaviour of the droplets across varying surfactant concentrations and temperatures, observing that swimming occurs only at sufficiently high surfactant concentrations above and temperatures above the smectic-nematic phase transition temperature $\textit{i.e.}$ $T\ge$ 33.5 $^{\circ}$C. Our work envisions the potential of LC emulsion droplets as switchable microswimmers.
description: 13 pages, 5 figures. Soft Matter (2025)