cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Automated search for galactic star clusters in large multiband surveys: I. Discovery of 15 new open clusters in the Galactic anticenter region
Creators: name: Koposov, S. E.
name: Glushkova, E. V.
name: Zolotukhin, I. Yu.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Aims: According to some estimations, there are as many as 100000 open clusters in the Galaxy, but less than 2000 of them have been discovered, measured, and cataloged. We plan to undertake data mining of multiwavelength surveys to find new star clusters. Methods: We have developed a new method to search automatically for star clusters in very large stellar catalogs, which is based on convolution with density functions. We have applied this method to a subset of the Two Micron All Sky Survey catalog toward the Galactic anticenter. We also developed a method to verify whether detected stellar groups are real star clusters, which tests whether the stars that form the spatial density peak also fall onto a single isochrone in the color-magnitude diagram. By fitting an isochrone to the data, we estimate at the same time the main physical parameters of a cluster: age, distance, color excess. Results: For the present paper, we carried out a detailed analysis of 88 overdensity peaks detected in a field of $16\times16$ degrees near the Galactic anticenter. From this analysis, 15 overdensities were confirmed to be new open clusters and the physical and structural parameters were determined for 12 of them; 10 of them were previously suspected to be open clusters by Kronberger (2006) and Froebrich (2007). The properties were also determined for 13 yet-unstudied known open clusters, thus almost tripling the sample of open clusters with studied parameters in the anticenter. The parameters determined with this method showed a good agreement with published data for a set of well-known clusters.
description: accepted to A&A
Hawking radiation received at infinity in higher dimensional Reissner-Nordström black hole spacetimes
Creators: name: Lin, Kai
name: Qian, Wei-Liang
name: Fan, Xilong
name: Wang, Bin
name: Abdalla, Elcio
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In this work, we investigate the Hawking radiation in higher dimensional Reissner-Nordström black holes as received by an observer, resides at infinity. The frequency-dependent transmission rates, which deform the thermal radiation emitted in the vicinity of the black hole horizon, are evaluated numerically. Apart from the case of four-dimensional spacetime, the calculations are extended to higher dimensional Reissner-Nordström metrics, and the results are found to be somewhat sensitive to the spacetime dimension. In general, it is observed that the transmission coefficients practically vanishes when the frequency of the emitted particle approaches zero. It increases with increasing frequency and eventually saturates to some value. For four-dimensional spacetime, the above result is shown to be mostly independent of the metric's parameter, neither of the orbital quantum number of the particle, once the location of the event horizon, $r_h$, and the product of the charges of the black hole and the particle $qQ$ are given. For higher-dimensional cases, on the other hand, the convergence becomes more slowly. Moreover, the difference between states with different orbital quantum numbers is found to be more significant. As the magnitude of the product of charges $qQ$ becomes more significant, the transmission coefficient exceeds one. In other words, the resultant spectral flux is amplified, which results in an accelerated process of black hole evaporation. The relation between the calculated outgoing transmission coefficient with existing results on the greybody factor is discussed.
Triplet Extended Supersymmetric Standard Model
Creators: name: Di Chiara, Stefano
name: Hsieh, Ken
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We revisit an extension of the MSSM by adding a hypercharge-neutral, SU(2)-triplet chiral superfield. Similar to the NMSSM, the triplet gives an additional contribution to the quartic coupling in the Higgs potential, and the mass of the lightest CP-even Higgs boson can be greater than tne mass of the Z-bosn at tree-level. In addition to discussing the perturbativity, fine-tuning, and decoupling issues of this model, we compute the dominant 1-loop corrections to the mass of the lightest CP-even Higgs boson from the triplet sector. When the Higgs-Higgs-Triplet coupling in the superpotential is comparable to the top Yukawa coupling, we find that the Higgs mass can be as heavy as 140 GeV even without the traditional contributions from the top--s-top sector, and at the same time consistent with the precision electroweak constraints. At the expense of having Landau poles before the GUT scale, this opens up a previously forbidden region in the MSSM parameter space where both s-tops are light. In addition to having relatively small fine-tuning (about one part in 30), this leads to a gluo-philic Higgs boson whose production via gluon-gluon fusion at the LHC can be twice as large as the SM prediction.
description: 26 pages, 19 figures. Errors on the RGEs corrected and consequential changes applied. Plots updated and discussion broadened. Version to appear in PRD
Mixing of Quantum Walks on Generalized Hypercubes
Creators: name: Best, Ana
name: Kliegl, Markus
name: Mead-Gluchacki, Shawn
name: Tamon, Christino
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study continuous-time quantum walks on graphs which generalize the hypercube. The only known family of graphs whose quantum walk instantaneously mixes to uniform is the Hamming graphs with small arities. We show that quantum uniform mixing on the hypercube is robust under the addition of perfect matchings but not much else. Our specific results include: (1) The graph obtained by augmenting the hypercube with an additive matching is instantaneous uniform mixing whenever the parity of the matching is even, but with a slower mixing time. This strictly includes Moore-Russell's result on the hypercube. (2) The class of Hamming graphs is not uniform mixing if and only if its arity is greater than 5. This is a tight characterization of quantum uniform mixing on Hamming graphs; previously, only the status of arity less than 5 was known. (3) The bunkbed graph B(A[f]), defined by a hypercube-circulant matrix A and a Boolean function f, is not uniform mixing if the Fourier transform of f has small support. This explains why the hypercube is uniform mixing and why the join of two hypercubes is not.
description: 13 pages, 4 figures
A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
Creators: name: Hopkins, Philip F.
name: Hernquist, Lars
name: Cox, Thomas J.
name: Keres, Dusan
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: (Abridged) We develop a model for the cosmological role of mergers in the evolution of starbursts, quasars, and spheroidal galaxies. Combining halo mass functions (MFs) with empirical halo occupation models, we calculate where major galaxy-galaxy mergers occur and what kinds of galaxies merge, at all redshifts. We compare with observed merger MFs, clustering, fractions, and small-scale environments, and show that this yields robust estimates in good agreement with observations. Making the simple ansatz that major, gas-rich mergers cause quasar activity, we demonstrate that this naturally reproduces the observed rise and fall of the quasar luminosity density from z=0-6, as well as quasar LFs, fractions, host galaxy colors, and clustering as a function of redshift and luminosity. The observed excess of quasar clustering on small scales is a natural prediction of the model, as mergers preferentially occur in regions with excess small-scale galaxy overdensities. We show that quasar environments at all observed redshifts correspond closely to the empirically determined small group scale, where mergers of gas-rich galaxies are most efficient. We contrast with a secular model in which quasar activity is driven by bars/disk instabilities, and show that while these modes probably dominate at Seyfert luminosities, the constraints from clustering (large and small-scale), pseudobulge populations, disk MFs, luminosity density evolution, and host galaxy colors argue that they must be a small contributor to the z>1 quasar luminosity density.
description: 34 pages, 27 figures, submitted to ApJ. Fixed appearance of Figure 1
Exponential clogging time for a one dimensional DLA
Creators: name: Benjamini, Itai
name: Hoffman, Christopher
Publisher: name: arXiv
Year: 2007
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: When considering DLA on a cylinder it is natural to ask how many particles it takes to clog the cylinder, e.g. modeling clogging of arteries. In this note we formulate a very simple DLA clogging model and establish an exponential lower bound on the number of particles arriving before clogging appears.
Monopoles of the Dirac type and color confinement in QCD
Creators: name: Suzuki, Tsuneo
name: Hiraguchi, Atsuki
name: Ishiguro, Katsuya
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We present results of $SU(3)$ Monte-Carlo studies of a new color confinement scheme proposed recently due to Abelian-like monopoles of the Dirac type corresponding in the continuum limit to violation of the non-Abelian Bianchi identities (VNABI). The simulations are done without any additional gauge-fixing smoothing the vacuum. We get for the first time, in pure $SU(3)$ simulations with the standard Wilson action, (1) the perfect Abelian dominance with respect to the static potentials on $12^4\sim 16^4$ lattices at $β=5.6-5.8$ using the multilevel method. (2) The perfect monopole as well as Abelian dominances with respect to the static potentials by evaluating the Polyakov loop correlators on $24^3\times4$ at $β=5.6$. The Abelian photon part gives zero string tension. (3) The Abelian dual Meissner effect is observed with respect to the Abelian gauge field and Abelian monopoles. The Abelian electric field of a color is squeezed due to the solenoidal monopole current with the corresponding color. Although the scaling and the volume dependence are not yet studied in $SU(3)$, the present results and the previous $SU(2)$ results are consistent with the new Abelian picture of color confinement that each one of eight (three in $SU(2)$) colored electric flux is squeezed by the corresponding colored Abelian-like monopole of the Dirac type corresponding to VNABI.
description: 15 pages, 9 figures, talk given at the 38th International Symposium on Lattice Field Theory (LATTICE2021), 26th-30th July 2021, Zoom/Gather@Massachusetts Institute of Technology
Editorial
Creators: name: Blum, Sabine
name: Kaufmann, Stefan
name: Wichum, Ricky
Publisher: name: BEHEMOTH - A Journal on Civilisation
Year: 2014

description: BEHEMOTH - A Journal on Civilisation, Resilienz, hg. von Sabine Blum, Stefan Kaufmann, Ricky Wichum (Vol. 7, No. 2)
Supersymmetric sources, integrability and generalized-structure compactifications
Creators: name: Koerber, Paul
name: Tsimpis, Dimitrios
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In the context of supersymmetric compactifications of type II supergravity to four dimensions, we show that orientifold sources can be compatible with a generalized SU(3) x SU(3)-structure that is neither strictly SU(3) nor static SU(2). We illustrate this with explicit examples, obtained by suitably T-dualizing known solutions on the six-torus. In addition we prove the following integrability statements, valid under certain mild assumptions: (a) for general type II supergravity backgrounds with orientifold and/or D-brane generalized-calibrated sources, the source-corrected Einstein and dilaton equations of motion follow automatically from the supersymmetry equations once the likewise source-corrected form equations of motion and Bianchi identities are imposed; (b) in the special case of supersymmetric compactifications to four-dimensional Minkowski space, the equations of motion of all fields, including the NSNS three-form, follow automatically once the supersymmetry and the Bianchi identities of the forms are imposed. Both (a) and (b) are equally valid whether the sources are smeared or localized. As a byproduct we obtain the calibration form for a space-filling NS5-brane.
description: 32 pages, 1 table, v2: added references, v3: corrected mistake in (4.1) leading to factor 2 mistake in (B.6), corrected (B.5), smaller typos
Period Doubling in Small Multiply Connected Superconductors
Creators: name: Vakaryuk, Victor
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: It is shown that for superconductors with circumference $2πR$ approaching BCS coherence length $ξ_0$ minimal period of the response of all thermodynamic quantities to external magnetic field is set by $hc/e$ i.e. twice the corresponding value for the bulk case. This is explained by the dependence of internal energy of Cooper pairs on their center of mass motion which leads, in particular, to a transition offset between different current-carrying states. Explicit calculation of the transition offset is done for the case of s-wave superconducting cylinder with $R \gg ξ_0$ and turns out to be exponentially small. A possible enhancement of the effect for nodal superconductors is suggested. Similar conclusions should also apply to the response of charged or neutral superfluids to rotation.
description: Reference 13 added
How to Draw Tropical Planes
Creators: name: Herrmann, Sven
name: Jensen, Anders
name: Joswig, Michael
name: Sturmfels, Bernd
Publisher: name: arXiv
Year: 2008
Subjects: subject: Combinatorics (math.CO)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 05B35, 52B40, 14M15

description: The tropical Grassmannian parameterizes tropicalizations of linear spaces, while the Dressian parameterizes all planes in $\TP^{n-1}$. We study these parameter spaces and we compute them explicitly for $n \leq 7$. Planes are identified with matroid subdivisions and with arrangements of trees. These representations are used to draw pictures.
description: 22 pages, 10 figures; correction of the definition of an 'abstract tree arrangement' on page 10
Liquid Structures: a novel Computational Fluid Dynamics (CFD) inspired metamaterial
Creators: name: Gallina, Paolo
name: Gei, Massimiliano
name: Scalera, Lorenzo
name: Seriani, Stefano
Publisher: name: arXiv
Year: 2021
Subjects: subject: Classical Physics (physics.class-ph)
subject: Numerical Analysis (math.NA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We present a theoretical framework for new structural metamaterials we refer to as liquid structures: a topology of bistable mechanisms made up of a high number of cells that are sub-mechanisms composed of pseudo-rigid links and joints. The name liquid structures comes from the similarities they present with the kinematics of the constant flow of incompressible fluids they are inspired by in a limited domain. The layout of the cells are obtained through a two-step process where: (i) the node displacements are computed by means of a Computational Fluid Dynamics tool feeding and (ii) the kinematic synthesis of each cell that is subsequently performed. We report two illustrative examples where star- and diamond-type cells are employed. The paper concludes with a detailed discussion about future theoretical and manufacturing challenges arising from this new metamaterial paradigm.
Aspetti Moderni della Fisica Greca [Modern Aspects of Ancient Greek Physics]
Creators: name: Recami, Erasmo
Publisher: name: arXiv
Year: 2007
Subjects: subject: Physics Education (physics.ed-ph)
subject: Popular Physics (physics.pop-ph)
subject: FOS: Physical sciences

description: Plutarchus, circa 100 AD, in his early book on "astrophysics" --in which he exposed, in a sense, a general theory of gravitation-- wrote the noticeable passage: <>. While Posidonius (circa 135-51 BC) had written: <>. These two examples show how "modern" was part of the ancient Greek physics, frequently overlooked since it is sometimes known through the praiseworthy translations of scholars often competent in humanities, more than in science. [A more extended English summary appears at the beginning of this article, which is in Italian.]
description: 18 pages, in Italian: but with a more extended summary in English. A preliminary version of this paper did already appear in the journal specified below:
Evidence for a ferromagnetic quantum critical point in URhGe doped with Ru
Creators: name: Huy, N. T.
name: de Nijs, D. E.
name: Gasparini, A.
name: Klaasse, J. C. P.
name: de Visser, A.
name: van Dijk, N. H.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We have investigated the evolution of ferromagnetic order in the correlated metal series URh_{1-x}Ru_{x}Ge. Magnetization, transport and specific heat measurements provide convincing evidence for a ferromagnetic quantum critical point at the critical concentration x_{c} = 0.38. Here we report ac-susceptibility and magnetization measurements on selected samples with Ru doping concentrations near the critical point.
description: 2 pages, conference paper, submitted to the proceedings of SCES'07
Sound waves in the intracluster medium of the Centaurus cluster
Creators: name: Sanders, J. S
name: Fabian, A. C.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report the discovery of ripple-like X-ray surface brightness oscillations in the core of the Centaurus cluster of galaxies, found with 200 ks of Chandra observations. The features are between 3 to 5 per cent variations in surface brightness with a wavelength of around 9 kpc. If, as has been conjectured for the Perseus cluster, these are sound waves generated by the repetitive inflation of central radio bubbles, they represent around 5x10^42 erg/s of spherical sound-wave power at a radius of 30 kpc. The period of the waves would be 10^7 yr. If their power is dissipated in the core of the cluster, it would balance much of the radiative cooling by X-ray emission, which is around 1.3x10^43 erg/s within the inner 30 kpc. The power of the sound waves would be a factor of four smaller that the heating power of the central radio bubbles, which means that energy is converted into sound waves efficiently.
description: 5 page letter, 5 figures, accepted by MNRAS
PoGOLite - A High Sensitivity Balloon-Borne Soft Gamma-ray Polarimeter
Creators: name: Kamae, Tuneyoshi
name: Andersson, Viktor
name: Arimoto, Makoto
name: Axelsson, Magnus
name: Bettolo, Cecilia Marini
name: Björnsson, Claes-Ingvar
name: Bogaert, Gilles
name: Carlson, Per
name: Craig, William
name: Ekeberg, Tomas
name: Engdegård, Olle
name: Fukazawa, Yasushi
name: Gunji, Shuichi
name: Hjalmarsdotter, Linnea
name: Iwan, Bianca
name: Kanai, Yoshikazu
name: Kataoka, Jun
name: Kawai, Nobuyuki
name: Kazejev, Jaroslav
name: Kiss, Mózsi
name: Klamra, Wlodzimierz
name: Larsson, Stefan
name: Madejski, Grzegorz
name: Mizuno, Tsunefumi
name: Ng, Johnny
name: Pearce, Mark
name: Ryde, Felix
name: Suhonen, Markus
name: Tajima, Hiroyasu
name: Takahashi, Hiromitsu
name: Takahashi, Tadayuki
name: Tanaka, Takuya
name: Thurston, Timothy
name: Ueno, Masaru
name: Varner, Gary
name: Yamamoto, Kazuhide
name: Yamashita, Yuichiro
name: Ylinen, Tomi
name: Yoshida, Hiroaki
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200mCrab point-like sources between 25 and 80keV in one 6 hour flight. Polarisation measurements in the soft gamma-ray band are expected to provide a powerful probe into high-energy emission mechanisms as well as the distribution of magnetic fields, radiation fields and interstellar matter. At present, only exploratory polarisation measurements have been carried out in the soft gamma-ray band. Reduction of the large background produced by cosmic-ray particles has been the biggest challenge. PoGOLite uses Compton scattering and photo-absorption in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence shield and a thick polyethylene neutron shield. The narrow FOV (1.25msr) obtained with well-type phoswich detector technology and the use of thick background shields enhance the detected S/N ratio. Event selections based on recorded phototube waveforms and Compton kinematics reduce the background to that expected for a 40-100mCrab source between 25 and 50keV. A 6 hour observation on the Crab will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5 sigma; and also cleanly identify the Compton reflection component in the Cygnus X-1 hard state. The first flight is planned for 2010 and long-duration flights from Sweden to Northern Canada are foreseen thereafter.
description: 11 pages, 11 figures, 2 tables
Sloppiness, robustness, and evolvability in systems biology
Creators: name: Daniels, Bryan C.
name: Chen, Yan-Jiun
name: Sethna, James P.
name: Gutenkunst, Ryan N.
name: Myers, Christopher R.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantitative Methods (q-bio.QM)
subject: FOS: Biological sciences

description: The functioning of many biochemical networks is often robust -- remarkably stable under changes in external conditions and internal reaction parameters. Much recent work on robustness and evolvability has focused on the structure of neutral spaces, in which system behavior remains invariant to mutations. Recently we have shown that the collective behavior of multiparameter models is most often 'sloppy': insensitive to changes except along a few 'stiff' combinations of parameters, with an enormous sloppy neutral subspace. Robustness is often assumed to be an emergent evolved property, but the sloppiness natural to biochemical networks offers an alternative non-adaptive explanation. Conversely, ideas developed to study evolvability in robust systems can be usefully extended to characterize sloppy systems.
description: 12 pages, 7 figures, submitted to Current Opinion in Biotechnology
Locality-aware Channel-wise Dropout for Occluded Face Recognition
Creators: name: He, Mingjie
name: Zhang, Jie
name: Shan, Shiguang
name: Liu, Xiao
name: Wu, Zhongqin
name: Chen, Xilin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Face recognition remains a challenging task in unconstrained scenarios, especially when faces are partially occluded. To improve the robustness against occlusion, augmenting the training images with artificial occlusions has been proved as a useful approach. However, these artificial occlusions are commonly generated by adding a black rectangle or several object templates including sunglasses, scarfs and phones, which cannot well simulate the realistic occlusions. In this paper, based on the argument that the occlusion essentially damages a group of neurons, we propose a novel and elegant occlusion-simulation method via dropping the activations of a group of neurons in some elaborately selected channel. Specifically, we first employ a spatial regularization to encourage each feature channel to respond to local and different face regions. In this way, the activations affected by an occlusion in a local region are more likely to be located in a single feature channel. Then, the locality-aware channel-wise dropout (LCD) is designed to simulate the occlusion by dropping out the entire feature channel. Furthermore, by randomly dropping out several feature channels, our method can well simulate the occlusion of larger area. The proposed LCD can encourage its succeeding layers to minimize the intra-class feature variance caused by occlusions, thus leading to improved robustness against occlusion. In addition, we design an auxiliary spatial attention module by learning a channel-wise attention vector to reweight the feature channels, which improves the contributions of non-occluded regions. Extensive experiments on various benchmarks show that the proposed method outperforms state-of-the-art methods with a remarkable improvement.
On the nature of unabsorbed Seyfert 2 galaxies
Creators: name: Brightman, Murray
name: Nandra, Kirpal
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present an analysis of six 12 um selected Seyfert 2 galaxies that have been reported to be unabsorbed in the X-ray. By comparing the luminosities of these galaxies in the mid-IR (12um), optical ([O III]) and hard X-ray (2-10 keV), we show that they are all under-luminous in the 2-10 keV X-ray band. Four of the objects exhibit X-ray spectra indicative of a hard excess, consistent with a heavily obscured X-ray component and hence a hidden nucleus. In these objects the softer X-rays may be dominated by a strong soft scattered continuum or contamination from the host galaxy, which is responsible for the unabsorbed X-ray spectra observed, and accounts for the anomalously low 2-10 keV X-ray luminosity. We confirm this assertion in NGC4501 with a Chandra observation, which shows hard X-ray emission coincident with the nucleus, consistent with heavy absorption, and a number of contaminating softer sources which account for the bulk of the softer emission. We point out that such 'Compton thick' sources need not necessarily present iron Ka emission of high EW. An example in our sample is IRASF01475-0740, which we know must host an obscured AGN as it hosts a HBLR seen in scattered light (Tran 2003). The X-ray spectrum is nonetheless relatively unobscured and the iron Ka line only moderate in strength. These observations can be reconciled if the hidden nuclear emission is dominated by transmitted, rather than reflected X-rays, which can then be weak compared to the soft scattered light or galactic emission. Despite these considerations, we conclude that NGC3147 & 3660 may intrinsically lack a BLR, confirming the recent results of Bianchi et al. (2008) for NGC3147. Neither X-ray spectrum shows signs of hidden hard emission and both sources exhibit X-ray variability leading us to believe we are viewing the nucleus directly.
description: 10 pages, 5 figures, accepted for publication at MNRAS
Pricing American options under negative rates
Creators: name: Healy, Jherek
Publisher: name: arXiv
Year: 2021
Subjects: subject: Pricing of Securities (q-fin.PR)
subject: Computational Finance (q-fin.CP)
subject: FOS: Economics and business

description: This paper starts by defining the criteria where the early-exercise of an American option is never optimal, under positive, or negative rates. It follows with a short analysis of the various shapes of the exercise region under negative interest rates. It then presents a new integral equation, which establishes the option price, and the two early exercise boundaries, under negative rates. It shows how to solve this new equation, through modifications of the modern and efficient algorithm of Andersen and Lake, from the initial guess of the two boundaries to more subtle changes required in their fixed point method for stability. Finally, the performance and accuracy of the resulting algorithm is assessed against a cutting edge finite difference method implementation.
A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: II. Formation of Red Ellipticals
Creators: name: Hopkins, Philip F.
name: Cox, Thomas J.
name: Keres, Dusan
name: Hernquist, Lars
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: (Abridged) We develop and test a model for the cosmological role of mergers in the formation and quenching of red, early-type galaxies. Making the ansatz that star formation is quenched after a gas-rich, spheroid-forming major merger, we demonstrate that this naturally predicts the turnover in the efficiency of star formation at ~L_star, as well as the observed mass functions/density of red galaxies as a function of redshift, the formation times of spheroids as a function of mass, and the fraction of quenched galaxies as a function of galaxy and halo mass, environment, and redshift. Comparing to a variety of semi-analytic models in which quenching is primarily driven by halo mass considerations or secular/disk instabilities, we demonstrate that our model and different broad classes of models make unique and robust qualitative predictions for a number of observables, including the red fraction as a function of galaxy and halo mass, the density of passive galaxies and evolution of the color-morphology-density relations at high z, and the fraction of disky/boxy spheroids as a function of mass. In each case, the observations favor a model in which galaxies quench after a major merger builds a massive spheroid, and disfavor quenching via secular or pure halo processes. We discuss a variety of physical possibilities for this quenching, and propose a mixed scenario in which traditional quenching in hot, massive halos is supplemented by the feedback associated with star formation and quasar activity in a major merger, which temporarily suppress cooling and establish the conditions of a dynamically hot halo in the central regions of the host, even in low mass halos.
description: 29 pages, 21 figures, submitted to ApJ. Replacement fixes comparison of models in Figures 6 & 9
QIZIL KITOBGA KIRGAN TOSHKENT VILOYATI ÕSIMLIKLARINING ÕZGARISH SABABLARI
Creators: name: O'razbayeva, Adiya
Publisher: name: Zenodo
Year: 2025

description: “Qizil kitobga kirgan Toshkent viloyati oʻsimliklarining oʻzgarish sabablari” maqolasida Toshkent viloyatida joylashgan va Qizil kitobga kiritilgan nadir va yoʻqolib borayotgan oʻsimlik turlarining populyatsiyasidagi oʻzgarishlar va ularga taʼsir etuvchi omillar tadqiq qilinadi.
An Update on the 0Z Project
Creators: name: Cohen, J. G.
name: Christlieb, N.
name: McWilliam, A.
name: Shectman, S.
name: Thompson, I.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We give an update on our 0Z Survey to find more extremely metal poor (EMP) stars with [Fe/H] < -3 dex through mining the database of the Hamburg/ESO Survey. We present the most extreme such stars we have found from ~1550 moderate resolution follow up spectra. One of these, HE1424-0241, has highly anomalous abundance ratios not seen in any previously known halo giant, with very deficient Si, moderately deficient Ca and Ti, highly enhanced Mn and Co, and low C, all with respect to Fe. We suggest a SNII where the nucleosynthetic yield for explosive alpha-burning nuclei was very low compared to that for the hydrostatic alpha-burning element Mg, which is normal in this star relative to Fe. A second, less extreme, outlier star with high [Sc/Fe] has also been found. We examine the extremely metal-poor tail of the HES metallicity distribution function (MDF). We suggest on the basis of comparison of our high resolution detailed abundance analyses with [Fe/H](HES) for stars in our sample that the MDF inferred from follow up spectra of the HES sample of candidate EMP stars is heavily contaminated for [Fe/H](HES) < -3 dex; many of the supposed EMP stars below that metallicity are of substantially higher Fe-metallicity, including most of the very C-rich stars, or are spurious objects.
description: to appear in conference proceedings "First Stars III", ed. B. O'Shea, A. Heger & T.Abel, 4 pages, 2 figures
'CADSketchNet' -- An Annotated Sketch dataset for 3D CAD Model Retrieval with Deep Neural Networks
Creators: name: Manda, Bharadwaj
name: Dhayarkar, Shubham
name: Mitheran, Sai
name: Viekash, V. K.
name: Muthuganapathy, Ramanathan
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Artificial Intelligence (cs.AI)
subject: Graphics (cs.GR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Ongoing advancements in the fields of 3D modelling and digital archiving have led to an outburst in the amount of data stored digitally. Consequently, several retrieval systems have been developed depending on the type of data stored in these databases. However, unlike text data or images, performing a search for 3D models is non-trivial. Among 3D models, retrieving 3D Engineering/CAD models or mechanical components is even more challenging due to the presence of holes, volumetric features, presence of sharp edges etc., which make CAD a domain unto itself. The research work presented in this paper aims at developing a dataset suitable for building a retrieval system for 3D CAD models based on deep learning. 3D CAD models from the available CAD databases are collected, and a dataset of computer-generated sketch data, termed 'CADSketchNet', has been prepared. Additionally, hand-drawn sketches of the components are also added to CADSketchNet. Using the sketch images from this dataset, the paper also aims at evaluating the performance of various retrieval system or a search engine for 3D CAD models that accepts a sketch image as the input query. Many experimental models are constructed and tested on CADSketchNet. These experiments, along with the model architecture, choice of similarity metrics are reported along with the search results.
description: Computers & Graphics Journal, Special Section on 3DOR 2021
TW Hydrae: evidence of stellar spots instead of a Hot Jupiter
Creators: name: Huelamo, N.
name: Figueira, P.
name: Bonfils, X.
name: Santos, N. C.
name: Pepe, F.
name: Guillon, M.
name: Azevedo, R.
name: Barman, T.
name: Fernandez, M.
name: di Folco, E.
name: Guenther, E. W.
name: Lovis, C.
name: Melo, C. H. F.
name: Queloz, D.
name: Udry, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: TW Hydrae shows significant radial-velocity variations in the optical regime. They have been attributed to a 10 Jupiter Mass planet orbiting the star at 0.04 AU. In this work, we have tested whether the observed RV variations can be caused by stellar spots. We have also analyzed new optical and infrared data to confirm the signal of the planet companion. We fitted the RV variations of TW Hya using a cool spot model. Our model shows that a cold spot covering 7% of the stellar surface and located at a latitude of 54 deg can reproduce the reported RV variations. The model also predicts a bisector semi-amplitude variation <10 m/s, which is less than the errors of the RV measurements discussed in an earlier publication. The analysis of new optical RV data, with typical errors of 10 m/s, shows a larger RV amplitude that varies depending on the correlation mask used. A slight correlation between the RV variation and the bisector is also observed, although not at a very significant level. The infrared H-band RV curve is almost flat, showing a small variation (<35 m/s) that is not consistent with the optical orbit. All these results support the spot scenario rather than the presence of a hot Jupiter around TW Hya.
description: accepted for publication in A&A
A queueing analysis of a multichannel, integrated voice and data communications system
Creators: name: Haller, Dennis Raymond
Publisher: name: University of British Columbia
Year: 2010

description: A multichannel radio communications system is modeled as a multiserver queue, with two distinct customer classes representing voice and data messages. Data, the class with the shorter average length, is given non-preemptive priority over voice. The queueing model is analyzed as a continuous-time Markov chain with an infinite state space. The infinite set of steady state balance equations is truncated, then solved numerically using the linear programming (LP) technique of Kotiah. Upper and lower bounds are thereby obtained for the mean waiting times of each customer class, and the probability distribution for the number of messages in the system. Exploitation of the Markov chain's property of irreducibility improves the original algorithm by considerably reducing the computational cost. Simulation is used to help analyze the system and to validate the numerical results. The particular four-channel case of the queueing model is treated in detail; both simulation and numerical results are presented. The LP method produces excellent results when the data traffic intensity is less than about 0.1. This corresponds typically to the proportion of data messages being less than 90%. For other traffic mixtures, the upper bounds, especially for waiting times, are often too high to be of practical use. However, the lower bounds of the mean waiting times are of greater use; the simulation results show them to be reasonably good approximations to the true steady state values.
Are all highly liquid securities within the same class?
Creators: name: Queiros, Silvio M. Duarte
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Finance (q-fin.ST)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Economics and business
subject: FOS: Physical sciences

description: In this manuscript we analyse the leading statistical properties of fluctuations of (log) 3-month US Treasury bill quotation in the secondary market, namely: probability density function, autocorrelation, absolute values autocorrelation, and absolute values persistency. We verify that this financial instrument, in spite of its high liquidity, shows very peculiar properties. Particularly, we verify that log-fluctuations belong to the Levy class of stochastic variables.
description: To be published in EPJB
Simulations of a supersymmetry inspired model on a fuzzy sphere
Creators: name: Bietenholz, Wolfgang
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We present a numerical study of a two dimensional model of the Wess-Zumino type. We formulate this model on a sphere, where the fields are expanded in spherical harmonics. The sphere becomes fuzzy by a truncation in the angular momenta. This leads to a finite set of degrees of freedom without explicitly breaking the space symmetries. The corresponding field theory is expressed in terms of a matrix model, which can be simulated. We present first numerical results for the phase structure of a variant of this model on a fuzzy sphere. The prospect to restore exact supersymmetry in certain limits is under investigation.
description: 7 pages, 4 figures, contribution to LAT2007 (updated version)
Yukawa-Casimir Wormholes
Creators: name: Garattini, Remo
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this work, we consider a Yukawa modification of the Casimir wormhole. With the help of an Equation of State, we impose Zero Tidal Forces. We will examine two different approaches: in a first approach, we will fix the form of the shape function of the Casimir wormholes modified by a Yukawa term in three different ways and finally a superposition of different profiles. In the second approach, we will consider the original Casimir source modified by a Yukawa term in three different ways and we will deduce the form of the shape function In both the approaches the reference energy density will be that of the Casimir source. Connection with the Absurdly Benign Traversable Wormhole are also discussed.
description: Revtex4 19 pages
Highest Energy Cosmic Rays and results from the HiRes Experiment
Creators: name: Sokolsky, P.
name: Thomson, G. B.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The status of the field of ultrahigh energy cosmic rays is summarized, from the point of view of the latest results of the High Resolution Fly's Eye (HiRes) Experiment. HiRes results are presented, and compared with those of the Akeno Giant Air Shower Array (AGASA), plus the Telescope Array and Pierre Auger experiments. The HiRes measurements of the cosmic ray spectrum, and the observation of the GZK cutoff are presented. HiRes results on composition, searches for anisotropy, measurement of the proton-air total cross section, and shapes of shower profiles are presented.
description: 31 pages, 18 figures, submitted to Journal of Physics G
Motional Spin Relaxation in Large Electric Fields
Creators: name: Schmid, Riccardo
name: Plaster, B.
name: Filippone, B. W.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We discuss the precession of spin-polarized Ultra Cold Neutrons (UCN) and $^{3}$He atoms in uniform and static magnetic and electric fields and calculate the spin relaxation effects from motional $v\times E$ magnetic fields. Particle motion in an electric field creates a motional $v\times E$ magnetic field, which when combined with collisions, produces variations of the total magnetic field and results in spin relaxation of neutron and $^{3}$He samples. The spin relaxation times $T_{1}$ (longitudinal) and $T_{2}$ (transverse) of spin-polarized UCN and $^{3}$He atoms are important considerations in a new search for the neutron Electric Dipole Moment at the SNS \emph{nEDM} experiment. We use a Monte Carlo approach to simulate the relaxation of spins due to the motional $v\times E$ field for UCN and for $^{3}$He atoms at temperatures below $600,\mathrm{mK}$. We find the relaxation times for the neutron due to the $v\times E$ effect to be long compared to the neutron lifetime, while the $^{3}$He relaxation times may be important for the \emph{nEDM} experiment.
description: 5 Pages, 4 Figures, 1 Table. Submitted to Phys. Rev. A
The design and performance of CUBES -- a CubeSat X-ray detector
Creators: name: Kushwah, Rakhee
name: Stana, Theodor A.
name: Pearce, Mark
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: CUBES is a X-ray detector payload which will be installed on the KTH 3U CubeSat mission, MIST. The detector comprises cerium-doped Gd3Al2Ga3O12 (GAGG) scintillators read out with silicon photomultipliers through a Citiroc Application-Specific Integrated Circuit. The detector operates in the energy range $\sim$35-800 keV. The aim of the CUBES mission is to provide experience in the operation of these relatively new technologies in a high-inclination low earth orbit, thereby providing confidence for component selection in more complex satellite missions. The design of the CUBES detector is described, and results from performance characterisation tests carried out on a prototype of CUBES, called Proto-CUBES, are reported. Proto-CUBES was flown on a stratospheric balloon platform from Timmins, Canada, in August 2019. During the $\sim$12 hour long flight, the performance of Proto-CUBES was studied in the near-space environment. As well as measuring the X-ray counts spectra at different atmospheric depths, a 511 keV line from positron annihilation was observed.
description: 25 pages, 19 figures, 3 tables, accepted for publication in JINST
Analytical calculation of the transition to complete phase synchronization in coupled oscillators
Creators: name: Muruganandam, Paulsamy
name: Ferreira, Fernando F.
name: El-Nashar, Hassan F.
name: Cerdeira, Hilda A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: Here we present a system of coupled phase oscillators with nearest neighbors coupling, which we study for different boundary conditions. We concentrate at the transition to total synchronization. We are able to develop exact solutions for the value of the coupling parameter when the system becomes completely synchronized, for the case of periodic boundary conditions as well as for an open chain with fixed ends. We compare the results with those calculated numerically.
description: 5 pages, 3 figures
Tag Clouds for Software Documents Visualization
Creators: name: Al-Msie'deen, Ra'Fat
Publisher: name: arXiv
Year: 2021
Subjects: subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Legacy software documents are hard to understand and visualize. The tag cloud technique helps software developers to visualize the contents of software documents. A tag cloud is a well-known and simple visualization technique. This paper proposes a new method to visualize software documents, using a tag cloud. In this paper, tags visualize in the cloud based on their frequency in an alphabetical order. The most important tags are displayed with a larger font size. The originality of this method is that it visualizes the contents of JavaDoc as a tag cloud. To validate the JavaDocCloud method, it was applied to NanoXML case study, the results of these experiments display the most common and uncommon tags used in the software documents.
description: 4 pages, 5 figures, 2 tables
Perturbation Theory Reloaded II: Non-linear Bias, Baryon Acoustic Oscillations and Millennium Simulation In Real Space
Creators: name: Jeong, Donghui
name: Komatsu, Eiichiro
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We calculate the non-linear galaxy power spectrum in real space, including non-linear distortion of the Baryon Acoustic Oscillations, using the standard 3rd-order perturbation theory (PT). The calculation is based upon the assumption that the number density of galaxies is a local function of the underlying, non-linear density field. The galaxy bias is allowed to be both non-linear and stochastic. We show that the PT calculation agrees with the galaxy power spectrum estimated from the Millennium Simulation, in the weakly non-linear regime (defined by the matter power spectrum) at high redshifts, $1\le z\le6$. We also show that, once 3 free parameters characterizing galaxy bias are marginalized over, the PT power spectrum fit to the Millennium Simulation data yields unbiased estimates of the distance scale, $D$, to within the statistical error. This distance scale corresponds to the angular diameter distance, $D_A(z)$, and the expansion rate, $H(z)$, in real galaxy surveys. Our results presented in this paper are still restricted to real space. The future work should include the effects of non-linear redshift space distortion. Nevertheless, our results indicate that non-linear galaxy bias in the weakly non-linear regime at high redshifts is reasonably under control.
description: 26 pages, 23 figures. (v2) Accepted for publication in ApJ