cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Matrix of integrated superconducting single-photon detectors with high timing resolution
Creators: name: Schuck, Carsten
name: Pernice, Wolfram H. P.
name: Minaeva, Olga
name: Li, Mo
name: Gol'tsman, Gregory
name: Sergienko, Alexander V.
name: Tang, Hong X.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We demonstrate a large grid of individually addressable superconducting single photon detectors on a single chip. Each detector element is fully integrated into an independent waveguide circuit with custom functionality at telecom wavelengths. High device density is achieved by fabricating the nanowire detectors in traveling wave geometry directly on top of silicon-on-insulator waveguides. Our superconducting single-photon detector matrix includes detector designs optimized for high detection efficiency, low dark count rate and high timing accuracy. As an example, we exploit the high timing resolution of a particularly short nanowire design to resolve individual photon round-trips in a cavity ring-down measurement of a silicon ring resonator.
description: 7 pages, 7 figures, IEEE Trans. Appl. Supercond. (2013)
Antiferromagnetic ordering of dangling-bond electrons at the stepped Si(001) surface
Creators: name: Lee, Jun-Ho
name: Kim, Sun-Woo
name: Cho, Jun-Hyung
Publisher: name: arXiv
Year: 2013
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Using first-principles density-functional calculations, we explore the possibility of magnetic order at the rebonded $D_B$ step of the Si(001) surface. The rebonded $D_B$ step containing threefold coordinated Si atoms can be treated as a one-dimensional dangling-bond (DB) wire along the step edge. We find that Si atoms composing the step edge are displaced up and down alternatively due to Jahn-Teller-like distortion, but, if Si dimers on the terrace are passivated by H atoms, the antiferromagnetic (AFM) order can be stabilized at the step edge with a suppression of Jahn-Teller-like distortion. We also find that the energy preference of AFM order over Jahn-Teller-like distortion is enhanced in an oscillatory way as the length of DB wires decreases, showing the so-called quantum size effects.
description: 12 pages, 4 figures, Accepted in Journal of Chemical Physics
Measurement and Analysis of Radio-frequency Radiation Exposure Level from Different Mobile Base Transceiver Stations in Ajaokuta and Environs, Nigeria
Creators: name: Ushie, P. O.
name: Nwankwo, Victor U. J.
name: Bolaji, Ayinmode
name: Osahun, O. D.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: We present the result of a preliminary assessment of radio-frequency radiation exposure from selected mobile base stations in Ajaokuta environs. The Power density of RF radiation within a radial distance of 125m was measured. Although values fluctuated due to the influence of other factors, including wave interference from other electromagnetic sources around reference base stations, we show from analysis that radiation exposure level is below the standard limit (4.5W/sqm for 900MHz and 9W/sqm for 18000MHz) set by the International Commission on Non-ionizing Radiation Protection (ICNIRP) and other regulatory agencies.
Quasi-Hamiltonian bookkeeping of WZNW defects
Creators: name: Klimcik, Ctirad
Publisher: name: arXiv
Year: 2013
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Symplectic Geometry (math.SG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We interpret the chiral WZNW model with general monodromy as an infinite dimensional quasi-Hamiltonian dynamical system. This interpretation permits to explain the totality of complicated cross-terms in the symplectic structures of various WZNW defects solely in terms of the single concept of the quasi-Hamiltonian fusion. Translated from the WZNW language into that of the moduli space of flat connections on Riemann surfaces, our result gives a compact and transparent characterisation of the symplectic structure of the moduli space of flat connections on a surface with k handles, n boundaries and m Wilson lines.
description: 22 pages
Coherent Destruction of Tunneling and Dark Floquet State
Creators: name: Luo, Xiaobing
name: Li, Liping
name: You, Li
name: Wu, Biao
Publisher: name: arXiv
Year: 2013
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study a system of three coherently coupled states, where one state is shifted periodically against the other two. We discover such a system possesses a dark Floquet state at zero quasienergy and always with negligible population at the intermediate state. This dark Floquet state manifests itself dynamically in terms of the suppression of inter-state tunneling, a phenomenon known as coherent destruction of tunneling. We suggest to call it dark coherent destruction of tunneling (DCDT). At high frequency limit for the periodic driving, this Floquet state reduces to the well-known dark state widely used for STIRAP. Our results can be generalized to systems with more states and can be verified with easily implemented experiments within current technologies.
description: 5 pages, 3 figures
The closest black holes
Creators: name: Fender, Rob
name: Maccarone, Tom
name: Heywood, Ian
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Starting from the assumption that there is a large population (> 10^8) of isolated, stellar-mass black holes (IBH) distributed throughout our galaxy, we consider the detectable signatures of accretion from the interstellar medium (ISM) that may be associated with such a population. We simulate the nearby (radius 250 pc) part of this population, corresponding to the closest ~35 000 black holes, using current best estimates of the mass distribution of stellar mass black holes combined with two models for the velocity distribution of stellar-mass IBH which bracket likely possibilities. We distribute this population of objects appropriately within the different phases of the ISM and calculate the Bondi-Hoyle accretion rate, modified by a further dimensionless efficiency parameter λ. Assuming a simple prescription for radiatively inefficient accretion at low Eddington ratios, we calculate the X-ray luminosity of these objects, and similarly estimate the radio luminosity from relations found empirically for black holes accreting at low rates. The latter assumption depends crucially on whether or not the IBH accrete from the ISM in a manner which is axisymmetric enough to produce jets. Comparing the predicted X-ray fluxes with limits from hard X-ray surveys, we conclude that either the Bondi-Hoyle efficiency parameter λ, is rather small (< 0.01), the velocities of the IBH are rather high, or some combination of both. The predicted radio flux densities correspond to a population of objects which, while below current survey limits, should be detectable with the Square Kilometre Array (SKA). Converting the simulated space velocities into proper motions, we further demonstrate that such IBH could be identified as faint high proper motion radio sources in SKA surveys.
description: Accepted for publication in MNRAS
Towards understanding the relation between the gas and the attenuation in galaxies at kpc scales
Creators: name: Boquien, M.
name: Boselli, A.
name: Buat, V.
name: Baes, M.
name: Bendo, G.
name: Boissier, S.
name: Ciesla, L.
name: Cooray, A.
name: Cortese, L.
name: Eales, S.
name: Koda, J.
name: Lebouteiller, V.
name: de Looze, I.
name: Smith, M. W. L.
name: Spinoglio, L.
name: Wilson, C. D.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: [abridged] Aims. The aim of the present paper is to provide new and more detailed relations at the kpc scale between the gas surface density and the face-on optical depth directly calibrated on galaxies, in order to compute the attenuation not only for semi-analytic models but also observationally as new and upcoming radio observatories are able to trace gas ever farther in the Universe. Methods. We have selected a sample of 4 nearby resolved galaxies and a sample of 27 unresolved galaxies from the Herschel Reference Survey and the Very Nearby Galaxies Survey, for which we have a large set of multi-wavelength data from the FUV to the FIR including metallicity gradients for resolved galaxies, along with radio HI and CO observations. For each pixel in resolved galaxies and for each galaxy in the unresolved sample, we compute the face-on optical depth from the attenuation determined with the CIGALE SED fitting code and an assumed geometry. We determine the gas surface density from HI and CO observations with a metallicity-dependent XCO factor. Results. We provide new, simple to use, relations to determine the face-on optical depth from the gas surface density, taking the metallicity into account, which proves to be crucial for a proper estimate. The method used to determine the gas surface density or the face-on optical depth has little impact on the relations except for galaxies that have an inclination over 50d. Finally, we provide detailed instructions on how to compute the attenuation practically from the gas surface density taking into account possible information on the metallicity. Conclusions. Examination of the influence of these new relations on simulated FUV and IR luminosity functions shows a clear impact compared to older oft-used relations, which in turn could affect the conclusions drawn from studies based on large scale cosmological simulations.
description: 24 pages, 21 figures, accepted for publication in A&A
Effect of Optical Feedback on the Wavelength Tuning in DBR Lasers
Creators: name: Happach, Magnus
name: De Felipe, David
name: Friedhoff, Victor Nicolai
name: Irmscher, Gelani
name: Kresse, Martin
name: Kleinert, Moritz
name: Zawadzki, Crispin
name: Brinker, Walter
name: Mohrle, Martin
name: Keil, Norbert
name: Hofmann, Werner
name: Schell, Martin
Publisher: name: Institute of Electrical and Electronics Engineers (IEEE)
Year: 2020
Subjects: subject: 500 Naturwissenschaften und Mathematik::530 Physik::535 Licht, Infrarot- und Ultraviolettphänomene
subject: continuous tuning
subject: DBR laser
subject: external cavity
subject: optical feedback interferometry
subject: optical feedback
subject: tunable laser

description: Optical feedback has an impact on the tunability of lasers. We created a model of a tunable distributed Bragg reflector (DBR) laser describing the effect of optical feedback from a constant reflector distance on the wavelength tuning. Theoretical and experimental results are in good agreement. A further discussion of the model sheds light on design rules to reduce the effect of optical feedback on the tuning behavior. We introduced a new parameter called mode loss difference (MLD) as a metric for the feedback tolerance of the tuning behavior. A large MLD indicates higher tolerance of the laser to cavity length variations.
ПАХТАНИ ҚУРИТИШ БАРАБАНИ 2СБ-10 ГА ҚУРИТИШ АГЕНТИНИ РАДИАЛ КИРИТИШ УСУЛИНИ ТАЖРИБАЛАРИНИ ЎТКАЗИШ МЕТОДИК УСЛУБЛАРИ
Creators: name: Назиров, Р.Р.
name: Каримбаев, Д.Р.
Publisher: name: Zenodo
Year: 2023

description: Тавсия этилган 2СБ-10 барабанли қуритгичининг барабани ичига қуритиш агентининг бир қисмини, тахминан 30-40 % ини қувур орқали радиал киритиб беришни амалга ошириш мақсадида техник ечим ишлаб чиқилган эди [1, 2].
Threshold resummation for polarized (semi-)inclusive deep inelastic scattering
Creators: name: Anderle, Daniele P.
name: Ringer, Felix
name: Vogelsang, Werner
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We explore the effects of the resummation of large logarithmic perturbative corrections to double-longitudinal spin asymmetries for inclusive and semi-inclusive deep inelastic scattering in fixed-target experiments. We find that the asymmetries are overall rather robust with respect to the inclusion of the resummed higher-order terms. Significant effects are observed at fairly high values of x, where resummation tends to decrease the spin asymmetries. This effect turns out to be more pronounced for semi-inclusive scattering. We also investigate the potential impact of resummation on the extraction of polarized valence quark distributions in dedicated high-x experiments.
description: 8 pages, 6 figures
Planar 4-critical graphs with four triangles
Creators: name: Borodin, Oleg V.
name: Dvořák, Zdeněk
name: Kostochka, Alexandr V.
name: Lidický, Bernard
name: Yancey, Matthew
Publisher: name: arXiv
Year: 2013
Subjects: subject: Combinatorics (math.CO)
subject: Discrete Mathematics (cs.DM)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: G.2.2
subject: 05C15, 05C10

description: By the Grunbaum-Aksenov Theorem (extending Grotzsch's Theorem) every planar graph with at most three triangles is 3-colorable. However, there are infinitely many planar 4-critical graphs with exactly four triangles. We describe all such graphs. This answers a question of Erdos from 1990.
description: 20 pages, 7 figures
Quantum Monte Carlo study of the two-dimensional ferromagnet
Creators: name: Conduit, G. J.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We present Quantum Monte Carlo calculations that probe the paramagnet-ferromagnet phase transition in a two-dimensional Stoner Hamiltonian. With a screened Coulomb interaction we observe a first order ferromagnetic transition for short screening lengths, and a second order transition with a longer screening length, accompanied by a rising critical interaction strength. Finally, we discuss the consequences of our results for an ultracold atomic gas with finite ranged interactions.
description: Accepted for publication in Phys. Rev. B
Palatini approach to modified f(R) gravity and its bi-metric structure
Creators: name: Santos, Janilo
name: Santos, Crislane de Souza
Publisher: name: arXiv
Year: 2012
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: f(R) gravity theories in the Palatini formalism has been recently used as an alternative way to explain the observed late-time cosmic acceleration with no need of invoking either dark energy or extra spatial dimension. However, its applications have shown that some subtleties of these theories need a more profound examination. Here we are interested in the conformal aspects of the Palatini approach in extended theories of gravity. As is well known, extremization of the gravitational action a la Palatini, naturally "selects" a new metric h related to the metric g of the subjacent manifold by a conformal transformation. The related conformal function is given by the derivative of f(R). In this work we examine the conformal symmetries of the flat (k=0) FLRW spacetime and find that its Conformal Killing Vectors are directly linked to the new metric h and also that each vector yields a different conformal function.
description: 3 pages, 1 table, talk given at I CosmoSul: Cosmology and Gravitation in the Southern Cone
Hunting the Parent of the Orphan Stream: Identifying Stream Members from Low-Resolution Spectroscopy
Creators: name: Casey, Andrew R.
name: Da Costa, Gary
name: Keller, Stefan C.
name: Maunder, Elizabeth
Publisher: name: arXiv
Year: 2013
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present candidate K-giant members in the Orphan Stream which have been identified from low-resolution data taken with the AAOmega spectrograph on the Anglo-Australian Telescope. From modest S/N spectra and independent cuts in photometry, kinematics, gravity and metallicity we yield self-consistent, highly probable stream members. We find a revised stream distance of 22.5 +/- 2.0 kpc near the celestial equator, and our kinematic signature peaks at Vgsr = 82.1 +/- 1.4 km/s. The observed velocity dispersion of our most probable members is consistent with arising from the velocity uncertainties alone. This indicates that at least along this line-of-sight, the Orphan Stream is kinematically cold. Our data indicates an overall stream metallicity of [Fe/H] = -1.63 +/- 0.19 dex which is more metal-rich than previously found and unbiased by spectral type. Furthermore, the significant metallicity dispersion displayed by our most probable members (0.56 dex) suggests that the unidentified Orphan Stream parent is a dSph satellite. We highlight likely members for high-resolution spectroscopic follow-up.
description: 6 pages, 6 figures. Accepted to ApJ
Modeling of electron emission processes accompanying Radon-$α$-decays within electrostatic spectrometers
Creators: name: Wandkowsky, N.
name: Drexlin, G.
name: Fränkle, F. M.
name: Glück, F.
name: Groh, S.
name: Mertens, S.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Electrostatic spectrometers utilized in high-resolution beta-spectroscopy studies such as in the Karlsruhe Tritium Neutrino (KATRIN) experiment have to operate with a background level of less than 10^(-2) counts per second. This limit can be exceeded by even a small number of Rn-219 or Rn-220 atoms being emanated into the volume and undergoing alpha-decay there. In this paper we present a detailed model of the underlying background-generating processes via electron emission by internal conversion, shake-off and relaxation processes in the atomic shells of the Po-215 and Po-216 daughters. The model yields electron energy spectra up to 400 keV and electron multiplicities of up to 20 which are compared to experimental data.
description: 7 figures
title: Сравнение способов компенсации скоростной ошибки по дальности в алгоритмах оценки дальности и радиальной скорости
Creators: name: ., М.А. Мурзова – аспирант, Московский физико-технический институт (государственный университет); инженер, ПАО «Радиофизика» (Москва) E-mail: mariya.trofimenko@phystech.edu В.Е. Фарбер – д.т.н., профессор, начальник отдела, ПАО «Радиофизика» (Москва); профессор, Московский физико-технический институт (государственный университет) E-mail: vladeffar@mail.ru
Publisher: name: Издательство Радиотехника
Year: 2019

description: Рассмотрены особенности фильтров первого порядка, реализующих процесс автосопровождения по дальности объектов радиолокационными станциями с ЛЧМ-сигналом.
Проанализирована взаимосвязь и проведено сравнение характеристик фильтров первого порядка, производящих оценку истинной и смещенной дальности. Получены выражения для определения коэффициентов диффузии, обеспечивающих заданную память фильтра. Рассмотрены вопросы формирования начальных параметров (завязка) траектории.
title: Моделирование поляризационных матриц рассеяния объектов наблюдения в полном поляризационном базисе
Creators: name: ., Е.Г. Паринов – студент, Московский физико-технический институт (государственный университет); инженер, ПАО «Радиофизика» (Москва) E-mail: evgeny.parinov@frtk.ru И.В. Зимин – к.т.н., вед. науч. сотрудник, зав. лабораторией «Радиофизика и спутниковая связь», Московский физико-технический институт (государственный университет)
Publisher: name: Издательство Радиотехника
Year: 2019

description: Разработана модель расчета поляризационных матриц рассеяния объектов наблюдения в полном поляризационном базисе.
Проведено моделирование поляризационных матриц рассеяния различных классов осесимметричных объектов наблюдения, соответствующих резонансной области.
Представлены графики зависимости эффективной площади рассеяния рассмотренных объектов от времени наблюдения и угла между осью симметрии объекта наблюдения и линией визирования.
title: Характеристики излучения антенных решеток с переплетающимися схемами возбуждения для сканирования в ограниченном секторе
Creators: name: С.П. Скобелев – д.ф.-м.н., вед. науч. сотрудник, ПАО «Радиофизика» (Москва); доцент, Московский физико-технический институт (государственный университет) E-mail: s.p.skobelev@mail.ru, С.П. Скобелев – д.ф.-м.н., вед. науч. сотрудник, ПАО «Радиофизика» (Москва); доцент, Московский физико-технический институт (государственный университет) E-mail: s.p.skobelev@mail.ru
Publisher: name: Издательство Радиотехника
Year: 2019

description: Проведен сравнительный анализ диаграмм направленности перекрывающихся подрешеток и эффективности использования управляемых элементов в решетках с переплетающимися и шахматными схемами возбуждения.
Показано, что хотя использование аттенюаторов в переплетающихся схемах питания подрешеток обеспечивает наиболее широкий сектор сканирования при низком уровне интерференционных максимумов, оно также приводит к заметному увеличению числа управляемых элементов как по сравнению с антенными решетками с шахматными схемами, так и по сравнению с антенными решетками с переплетающимися схемами без аттенюаторов.
title: Оценка интегральных энергетических характеристик приемопередающего модуля АФАР, работающего в импульсном режиме
Creators: name: П.А. Тушнов – гл. технолог, ПАО «Радиофизика» (Москва) E-mail: tushnov.p@radiofizika.com, П.А. Тушнов – гл. технолог, ПАО «Радиофизика» (Москва) E-mail: tushnov.p@radiofizika.com
Publisher: name: Издательство Радиотехника
Year: 2019

description: Проведена оценка интегральных энергетических характеристик приемопередающего модуля (ППМ), работающего в импульсном режиме (ИР), с учетом схемы его построения, характеристик активных и пассивных узлов.
Предложена формула, определяющая зависимость КПД ППМ от КПД транзистора выходного и предварительного усилителей мощности СВЧ-канала и скважности.
Представлены результаты измерений энергетических характеристик ППМ S диапазона, полученные в процессе технологической подготовки серийного изготовления партии ППМ S диапазона.
title: Сравнение методов обработки сигнала при калибровке цифровых приемных ФАР
Creators: name: А.М. Шитиков – к.т.н., начальник сектора, ПАО «Радиофизика» (Москва); преподаватель, Московский физико-технический институт (государственный университет) E-mail: shitikov.a@radiofizika.com, А.М. Шитиков – к.т.н., начальник сектора, ПАО «Радиофизика» (Москва); преподаватель, Московский физико-технический институт (государственный университет) E-mail: shitikov.a@radiofizika.com
Publisher: name: Издательство Радиотехника
Year: 2019

description: Рассмотрены два метода обработки сигнала при калибровке цифровой фазированной антенной решетки на прием: 1) накопление и усреднение комплексных отсчетов сигналов каналов, затем вычисление отношений усредненных величин; 2) вычисление набора частных отношений для комплексных отсчетов разных каналов, а затем – усреднение.
Показано, что второй метод обработки существенно устойчивее в условиях дрейфа фазы при измерениях.
title: Оценка влияния фазовых флуктуаций гетеродинных сигналов на результат оптимальной фильтрации ЛЧМ-сигналов в РЛС с когерентным накоплением импульсов
Creators: name: Е.М. Макарычев – аспирант, Московский физико-технический институт (государственный университет); инженер, ПАО «Радиофизика» (Москва) E-mail: makarychev@phystech.edu И.А. Григорьев – начальник сектора, ПАО «Радиофизика» (Москва) E-mail: iv.grigoryev@gmail.com Д.С. Очков – к.т.н., ст. науч. сотрудник, руководитель подразделения, ПАО «Радиофизика» (Москва) E-mail: d-ochkov@mail.ru, Е.М. Макарычев – аспирант, Московский физико-технический институт (государственный университет); инженер, ПАО «Радиофизика» (Москва) E-mail: makarychev@phystech.edu И.А. Григорьев – начальник сектора, ПАО «Радиофизика» (Москва) E-mail: iv.grigoryev@gmail.com Д.С. Очков – к.т.н., ст. науч. сотрудник, руководитель подразделения, ПАО «Радиофизика» (Москва) E-mail: d-ochkov@mail.ru
Publisher: name: Издательство Радиотехника
Year: 2019

description: Представлены результаты численной оценки влияния фазовых флуктуаций гетеродинных сигналов на результат оптимальной обработки ЛЧМ-сигналов в моноимпульсном режиме и режиме когерентного накопления импульсов.
Проведен анализ для моноимпульсного режима при различных значениях длительности импульса и дальности до цели. Рассмотрены различные спектральные характеристики фазовых шумов гетеродина. Анализ работы РЛС в режиме когерентного накопления пачки импульсов проведен при дополнительном варьировании времени накопления.
title: Влияние отрицательных температур на запуск и фазовые шумы высокочастотных кварцевых генераторов
Creators: name: Е.А. Силаев – начальник сектора, ПАО «Радиофизика» (Москва) E-mail: evgeniysilaev@hotmail.com, Е.А. Силаев – начальник сектора, ПАО «Радиофизика» (Москва) E-mail: evgeniysilaev@hotmail.com
Publisher: name: Издательство Радиотехника
Year: 2019

description: Проведено экспериментальное исследование влияния температуры минус 80°C на частоту, мощность и спектральную плотность мощности фазовых шумов колебаний кварцевых генераторов с кварцевыми резонаторами АТ-среза, возбуждаемыми по 7 й механической гармонике на частотах около 250 МГц.
Рассмотрены проблемы запуска и поведения генераторов при низких температурах в первые секунды после включения.
Приведены результаты эксперимента.
The Milky Way halo as a QSO absorption-line system. New results from an HST/STIS absorption-line catalogue of Galactic high-velocity clouds
Creators: name: Herenz, Peter
name: Richter, Philipp
name: Charlton, Jane C.
name: Masiero, Joseph R.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We use archival UV absorption-line data from HST/STIS to statistically analyse the absorption characteristics of the high-velocity clouds (HVCs) in the Galactic halo towards more than 40 extragalactic background sources. We determine absorption covering fractions of low- and intermediate ions (OI, CII, SiIII, MgII, FeII, SiIII, CIV, and SiIV) in the range fc = 0.20 - 0.70. For detailed analysis we concentrate on SiII absorption components in HVCs, for which we investigate the distribution of column densities, b-values, and radial velocities. Combining information for SiII and MgII, and using a geometrical HVC model we investigate the contribution of HVCs to the absorption cross section of strong MgII absorbers in the local Universe. We estimate that the Galactic HVCs would contribute on average ~52 % to the total strong MgII cross section of the Milky Way, if our Galaxy were to be observed from an exterior vantage point. We further estimate that the mean projected covering fraction of strong MgII absorption in the Milky Way halo and disc from an exterior vantage point is fc(sMgII) = 0.31 for a halo radius of R = 61 kpc. These numbers, together with the observed number density of strong MgII absorbers at low redshift, indicate that the contribution of infalling gas clouds (i.e., HVC analogues) in the halos of Milky Way-type galaxies to the cross section of strong MgII absorbers is <34 %. These findings are in line with the idea that outflowing gas (e.g., produced by galactic winds) in the halos of more actively star-forming galaxies dominate the absorption-cross section of strong MgII absorbers in the local Universe.
A universal approach to the calculation of the transit light curves
Creators: name: Abubekerov, M. K.
name: Gostev, N. Yu.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We have developed a universal approach to compute accurately the brightness of eclipsing binary systems during the transit of a planet in front of the stellar disk. This approach is uniform for all values of the system parameters and applicable to most limb-darkening laws used in astrophysics. In the cases of linear and quadratic limb-darkening laws we obtained analytical expressions for the light curve and its derivatives in terms of elementary functions, elliptic integrals and piecewise-defined function of one variable. In the cases of logarithmic and square root laws of limb darkening the flux and its derivatives were expressed in terms of integrals which can be efficiently computed using Gaussian quadrature formula, taking into account singularities of the integrand.
description: 9 pages, 1 figures
Oxidizing Borcherds symmetries
Creators: name: Kleinschmidt, Axel
name: Palmkvist, Jakob
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Rings and Algebras (math.RA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: The tensor hierarchy of maximal supergravity in D dimensions is known to be closely related to a Borcherds (super)algebra that is constructed from the global symmetry group E(11-D). We here explain how the Borcherds algebras in different dimensions are embedded into each other and can be constructed from a unifying Borcherds algebra. The construction also has a natural physical explanation in terms of oxidation. We then go on to show that the Hodge duality that is present in the tensor hierarchy has an algebraic counterpart. For D>8 the Borcherds algebras we find differ from the ones existing in the literature although they generate the same tensor hierarchy.
description: 21 pages, 3 figures, 5 tables
Synchrotron and inverse-Compton emission from blazar jets - III. Compton-dominant blazars
Creators: name: Potter, William J.
name: Cotter, Garret
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: In this paper we develop the extended jet model of Potter & Cotter to model the simultaneous multi-wavelength spectra of six Compton-dominant blazars. We include an accelerating parabolic base transitioning to a slowly decelerating conical jet with a geometry set by observations of M87 and consistent with simulations and theory. We investigate several jet models and find that the optically thick to thin synchrotron break in the radio spectrum requires the jet to first come into equipartition at large distances along the jet (10^5 Schwarzschild radii), consistent with the observed transition from parabolic to conical in the jet of M87. We confirm this result analytically and calculate the expected frequency core-shift relations for the models under consideration. We find that a parabolic jet transitioning to a ballistic conical jet, which starts in equipartition and becomes more particle dominated at larger distances, fits the multiwavelength data of the six blazars well, whilst an adiabatic equipartition conical section requires very large bulk Lorentz factors to reproduce the Compton-dominance of the blazars. We find that all these blazars require high power, high bulk Lorentz factor jets observed close to the line of sight as we expect from the blazar sequence and consistent with the results from Paper II. The inverse-Compton emission in our fits is due to inverse-Compton scattering of high-redshift CMB photons at large distances along the jet due to the high bulk Lorentz factors of the jets. We postulate a new interpretation of the blazar sequence based on the radius of the transition region of the jet (where the jet is brightest in synchrotron emission) scaling linearly with black hole mass.
description: 13 pages, 5 figures, accepted for publication in MNRAS
Single-Crystal Diamond Nanomechanical Resonators with Quality Factors exceeding one Million
Creators: name: Tao, Y.
name: Boss, J. M.
name: Moores, B. A.
name: Degen, C. L.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We present nanofabrication and mechanical measurements of single-crystal diamond cantilevers with thickness down to 85 nm, thickness uniformity better than 20 nm, and lateral dimensions up to 240 um. Quality factors exceeding one million are found at room temperature, surpassing those of state-of-the-art single-crystal silicon cantilevers of similar dimensions by roughly an order of magnitude. Force sensitivities of a few hundred zeptonewtons result for the best cantilevers at millikelvin temperatures. Single-crystal diamond could thus directly improve existing force and mass sensors by a simple substitution of resonator material, and lead to quantum nanomechanical devices with exceptionally low energy dissipation.
Validation of a model for Radon-induced background processes in electrostatic spectrometers
Creators: name: Wandkowsky, N.
name: Drexlin, G.
name: Fränkle, F. M.
name: Glück, F.
name: Groh, S.
name: Mertens, S.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: The Karlsruhe Tritium Neutrino (KATRIN) experiment investigating tritium beta-decay close to the endpoint with unprecedented precision has stringent requirements on the background level of less than 10^(-2) counts per second. Electron emission during the alpha-decay of Rn-219 and Rn-220 atoms in the electrostatic spectrometers of KATRIN is a serious source of background exceeding this limit. In this paper we compare extensive simulations of Rn-induced background to specific measurements with the KATRIN pre-spectrometer to fully characterize the observed Rn-background rates and signatures and determine generic Rn emanation rates from the pre-spectrometer bulk material and its vacuum components.
description: 10 figures
Methoden der Feldforschung / Prüfungsunterlagen SoSe 2019
Creators: name: Peter Oberosler
Publisher: name: Zenodo
Year: 2023

description: Methoden der Feldforschung / Prüfungsunterlagen SoSe 2019;
Institut für Musikwissenschaft / Universität Innsbruck;
Prof. Dr. Ammann Raymond / Peter Oberosler M.A.;
Trees under attack: a Ray-Knight representation of Feller's branching diffusion with logistic growth
Creators: name: Le, Vi
name: Pardoux, Etienne
name: Wakolbinger, Anton
Publisher: name: arXiv
Year: 2013
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics

description: We obtain a representation of Feller's branching diffusion with logistic growth in terms of the local times of a reflected Brownian motion $H$ with a drift that is affine linear in the local time accumulated by $H$ at its current level. As in the classical Ray-Knight representation, the excursions of $H$ are the exploration paths of the trees of descendants of the ancestors at time $t=0$, and the local time of $H$ at height $t$ measures the population size at time $t$ (see e.g. \cite{LG4}). We cope with the dependence in the reproduction by introducing a pecking order of individuals: an individual explored at time $s$ and living at time $t=H_s$ is prone to be killed by any of its contemporaneans that have been explored so far. The proof of our main result relies on approximating $H$ with a sequence of Harris paths $H^N$ which figure in a Ray-Knight representation of the total mass of a branching particle system. We obtain a suitable joint convergence of $H^N$ together with its local times {\em and} with the Girsanov densities that introduce the dependence in the reproduction.
Agents and owl-s based semantic web service discovery with user preference support
Creators: name: Rohallah, Benaboud
name: Ramdane, Maamri
name: Zaidi, Sahnoun
Publisher: name: arXiv
Year: 2013
Subjects: subject: Information Retrieval (cs.IR)
subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Service-oriented computing (SOC) is an interdisciplinary paradigm that revolutionizes the very fabric of distributed software development applications that adopt service-oriented architectures (SOA) can evolve during their lifespan and adapt to changing or unpredictable environments more easily. SOA is built around the concept of Web Services. Although the Web services constitute a revolution in Word Wide Web, they are always regarded as non-autonomous entities and can be exploited only after their discovery. With the help of software agents, Web services are becoming more efficient and more dynamic. The topic of this paper is the development of an agent based approach for Web services discovery and selection in witch, OWL-S is used to describe Web services, QoS and service customer request. We develop an efficient semantic service matching which takes into account concepts properties to match concepts in Web service and service customer request descriptions. Our approach is based on an architecture composed of four layers: Web service and Request description layer, Functional match layer, QoS computing layer and Reputation computing layer.
description: 19 pages, 10 figures
SELFAS2 : radio emission from cosmic ray air showers. Effect of realistic air refractive index
Creators: name: Marin, Vincent
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Using the simulation code SELFAS2, we present predictions of the radio signal emitted by extensive air showers (EAS) during their development in the atmosphere. The radio emission in the MHz range coming from air showers is the superposition of two mechanisms: the variation of the transverse current due to the systematic opposite drift of electrons and positrons in the Earth's magnetic field and the variation of the charge excess due to the electrons in excess in the shower front. In this paper, we stress particularly the effect of the realistic air refractive index on the radio signal predicted by SELFAS2.
description: 4 pages, 5 figures
Statistical Analysis of Small Ellerman Bomb Events
Creators: name: Nelson, C. J.
name: Doyle, J. G.
name: Erdelyi, R.
name: Huang, Z.
name: Madjarska, M.
name: Mathioudakis, M.
name: Mumford, S.
name: Reardon, K.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The properties of Ellerman bombs (EBs), small-scale brightenings in the H-alpha line wings, have proved difficult to establish due to their size being close to the spatial resolution of even the most advanced telescopes. Here, we aim to infer the size and lifetime of EBs using high-resolution data of an emerging active region collected using the Interferometric BIdimensional Spectrometer (IBIS) and Rapid Oscillations of the Solar Atmosphere (ROSA) instruments as well as the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We develop an algorithm to track EBs through their evolution, finding that EBs can often be much smaller (around 0.3") and shorter lived (less than 1 minute) than previous estimates. A correlation between G-band magnetic bright points and EBs is also found. Combining SDO/HMI and G-band data gives a good proxy of the polarity for the vertical magnetic field. It is found that EBs often occur both over regions of opposite polarity flux and strong unipolar fields, possibly hinting at magnetic reconnection as a driver of these events.The energetics of EB events is found to follow a power-law distribution in the range of "nano-flare" (10^{22-25} ergs).
description: 19 pages. 7 Figures
Implementation and Institutional Aspects of Integrated Watershed Managemant
Creators: name: Easter, K. William
name: Gibbs, Christopher J.N.
Publisher: name: Unknown
Year: 1985
Subjects: subject: Environmental Economics and Policy
subject: Land Economics/Use
subject: Production Economics
subject: soil erosion
subject: Asia
subject: agricultural productivity
subject: watershed management

description: Paper prepared for the Workshop on Integrated Watershed Managenent. to be held at Environnent and Policy Institute. East-West Center. Honolulu. Hawaii. January 7-12, 1985.
KURASHCHILARDA UMUMIY VA MAXSUS JISMONIY TAYYORGARLIK ASOSLARI
Creators: name: Asrorov, S.
Publisher: name: Zenodo
Year: 2023

description: Mazkur maqolada kurashchilarning sport mashg'ulotlari jismoniy tayyorgarlikning metodik hamda ilmiy jihatlari yoritib berilgan.
Kappa Fornaci, a triple radio-star
Creators: name: Tokovinin, Andrei
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Bright and nearby (22pc) solar-type dwarf Kappa Fornaci (HIP 11072) is a triple system. The close pair of M-type dwarfs Ba,Bb with a tentative period of 3.7 days moves around the main component A on a 26-year orbit. The mass of the "dark companion" Ba+Bb is comparable to the mass of A, causing large motion of the photo-center. The combined spectro-interferometric orbit of AB is derived and the relative photometry of the components A and B is given. A weak signature of Ba and Bb is detected in the high-resolution spectra by cross-correlation and by variable emission in the Bahlmer hydrogen lines. The activity of the M-dwarfs, manifested by a previously detected radio-flare, is likely maintained by synchronization with their tight orbit. We discuss the frequency of similar hidden triple systems, methods of their detection, and the implications for multiple-star statistics.
description: Accepted by AJ. 7 pages, 5 figures, 5 tables
Complete Disorder is Impossible: The Mathematical Work of Walter Deuber
Creators: name: Prömel, Hans Jürgen
Publisher: name: Humboldt-Universität zu Berlin
Year: 2005
Subjects: subject: 510 Mathematik
subject: 004 Informatik

description: This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
description: Complete disorder is impossible – this theme of Ramsey Theory, as stated by Theodore S. Motzkin, was a guiding theme throughout Walter Deuber's scientific life.
The Lovász Number of Random Graphs
Creators: name: Coja-Oghlan, Amin
Publisher: name: Humboldt-Universität zu Berlin
Year: 2005
Subjects: subject: 510 Mathematik
subject: 004 Informatik

description: This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
description: We study the Lovász number $\vartheta$ along with two related SDP relaxations $\vartheta_{1/2}$, $\vartheta_2$ of the independence number and the corresponding relaxations $\bar\vartheta$, $\bar\vartheta_{1/2}$, $\bar\vartheta_2$ of the chromatic number on random graphs $G_{n,p}$. We prove that $\vartheta,\vartheta_{1/2},\vartheta_2(G_{n,p})$ are concentrated about their means, and that $\bar\vartheta,\bar\vartheta_{1/2},\bar\vartheta_2(G_{n,p})$ in the case $p0$ is a constant. As an application, we give improved algorithms for approximating the independence number of $G_{n,p}$ and for deciding $k$-colourability in polynomial expected time.
Searching for Spurious Solar and Sky Lines in the Fermi-LAT Spectrum
Creators: name: Whiteson, Daniel
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We search for a unified instrumental explanation of the spectral features seen near $E_γ=130$ GeV in photons collected by Fermi-LAT from the galactic center and from the Earth's limb. We report for the first time a similar feature in photons originating from the vicinity of the Sun, and examine the instrumental characteristics of this Solar feature. To test an instrumental hypothesis, we identify the range of photon incident angles where most of the peak photons are observed in these three spectral features. An examination of the spectrum of photons from the rest of the sky with this characteristic angular range reveals a hint of a spectral feature near $E_γ=130$ GeV. These results cast further doubt on the dark-matter-annihilation interpretation of the galactic center peak.
description: 7 pages, 10 figures
Gravitational Wave Tests of Strong Field General Relativity with Binary Inspirals: Realistic Injections and Optimal Model Selection
Creators: name: Sampson, Laura
name: Cornish, Neil
name: Yunes, Nicolas
Publisher: name: arXiv
Year: 2013
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We study generic tests of strong-field General Relativity using gravitational waves emitted during the inspiral of compact binaries. Previous studies have considered simple extensions to the standard post-Newtonian waveforms that differ by a single term in the phase. Here we improve on these studies by (i) increasing the realism of injections and (ii) determining the optimal waveform families for detecting and characterizing such signals. We construct waveforms that deviate from those in General Relativity through a series of post-Newtonian terms, and find that these higher-order terms can affect our ability to test General Relativity, in some cases by making it easier to detect a deviation, and in some cases by making it more difficult. We find that simple single-phase post-Einsteinian waveforms are sufficient for detecting deviations from General Relativity, and there is little to be gained from using more complicated models with multiple phase terms. The results found here will help guide future attempts to test General Relativity with advanced ground-based detectors.
description: 12 pages, 8 figures
The Effect of the Pre-Detonation Stellar Internal Velocity Profile on the Nucleosynthetic Yields in Type Ia Supernova
Creators: name: Kim, Yeunjin
name: Jordan, G. C.
name: Graziani, Carlo
name: Meyer, B. S.
name: Lamb, D. Q.
name: Truran, J. W.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: A common model of the explosion mechanism of Type Ia supernovae is based on a delayed detonation of a white dwarf. A variety of models differ primarily in the method by which the deflagration leads to a detonation. A common feature of the models, however, is that all of them involve the propagation of the detonation through a white dwarf that is either expanding or contracting, where the stellar internal velocity profile depends on both time and space. In this work, we investigate the effects of the pre-detonation stellar internal velocity profile and the post-detonation velocity of expansion on the production of alpha-particle nuclei, including Ni56, which are the primary nuclei produced by the detonation wave. We perform one-dimensional hydrodynamic simulations of the explosion phase of the white dwarf for center and off-center detonations with five different stellar velocity profiles at the onset of the detonation. We observe two distinct post-detonation expansion phases: rarefaction and bulk expansion. Almost all the burning to Ni56 occurs only in the rarefaction phase, and its expansion time scale is influenced by pre-existing flow structure in the star, in particular by the pre-detonation stellar velocity profile. We find that the mass fractions of the alpha-particle nuclei, including Ni56, are tight functions of the empirical physical parameter rho_up/v_down, where rho_up is the mass density immediately upstream of the detonation wave front and v_down is the velocity of the flow immediately downstream of the detonation wave front. We also find that v_down depends on the pre-detonation flow velocity. We conclude that the properties of the pre-existing flow, in particular the internal stellar velocity profile, influence the final isotopic composition of burned matter produced by the detonation.