cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The Solar Neighborhood. XX. Discovery and Characterization of 21 New Nearby White Dwarf Systems
Creators: name: Subasavage, John P.
name: Henry, Todd J.
name: Bergeron, P.
name: Dufour, P.
name: Hambly, Nigel C.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present medium resolution spectroscopy and multi-epoch VRI photometry for 21 new nearby (< 50 pc) white dwarf systems brighter than V ~ 17. Of the new systems, ten are DA (including a wide double degenerate system with two DA components), eight are DC, two are DZ, and one is DB. In addition, we include multi-epoch VRI photometry for eleven known white dwarf systems that do not have trigonometric parallax determinations. Using model atmospheres relevant for various types of white dwarfs (depending on spectral signatures), we perform spectral energy distribution modeling by combining the optical photometry with the near-infrared JHK from the Two Micron All-Sky Survey to derive physical parameters (i.e., effective temperature and distance estimates). We find that twelve new and six known white dwarf systems are estimated to be within the NStars and Catalog of Nearby Stars horizons of 25 pc. Coupled with identical analyses of the 56 white dwarf systems presented in Paper XIX of this series, a total of 20 new white dwarf systems and 18 known white dwarf systems are estimated to be within 25 pc. These 38 systems of the 88 total studied represent a potential 34% increase in the 25 pc white dwarf population (currently known to consist of 110 systems with trigonometric parallaxes of varying qualities). We continue an ongoing effort via CTIOPI to measure trigonometric parallaxes for the systems estimated to be within 25 pc to confirm proximity and further fill the incompleteness gap in the local white dwarf population. Another 38 systems (both new and known) are estimated to be between 25 and 50 pc and are viable candidates for ground-based parallax efforts wishing to broaden the horizon of interest.
description: 10 pages, 7 figures, accepted for publication in Astronomical Journal
Locating the zeros of partial sums of exp(z) with Riemann-Hilbert methods
Creators: name: Kriecherbauer, T.
name: Kuijlaars, A. B. J.
name: McLaughlin, K. D. T-R
name: Miller, P. D.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 30C15, 35Q15

description: In this paper we derive uniform asymptotic expansions for the partial sums of the exponential series. We indicate how this information will be used in a later publication to obtain full and explicitly computable asymptotic expansions with error bounds for all zeros of the Taylor polynomials $p_{n-1}(z) = \sum_{k=0}^{n-1} z^k/ k!$. Our proof is based on a representation of $p_{n-1}(nz)$ in terms of an integral of the form $\int_γ \frac{e^{nϕ(s)}}{s-z}ds$. We demonstrate how to derive uniform expansions for such integrals using a Riemann-Hilbert approach. A comparison with classical steepest descent analysis shows the advantages of the Riemann-Hilbert analysis in particular for points $z$ that are close to the critical points of $ϕ$.
description: 13 pages, 3 figures; to appear in proceedings of "Integrable Systems, Random Matrices, and Applications, a conference in honor of Percy Deift's 60th birthday"
Crowdsourcing through Cognitive Opportunistic Networks
Creators: name: Mordacchini, M.
name: Passarella, A.
name: Conti, M.
name: Allen, S. M.
name: Chorley, M. J.
name: Colombo, G. B.
name: Tanasescu, V.
name: Whitaker, R. M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Artificial Intelligence (cs.AI)
subject: Human-Computer Interaction (cs.HC)
subject: FOS: Computer and information sciences
subject: I.6.1

description: Untile recently crowdsourcing has been primarily conceived as an online activity to harness resources for problem solving. However the emergence of opportunistic networking (ON) has opened up crowdsourcing to the spatial domain. In this paper we bring the ON model for potential crowdsourcing in the smart city environment. We introduce cognitive features to the ON that allow users' mobile devices to become aware of the surrounding physical environment. Specifically, we exploit cognitive psychology studies on dynamic memory structures and cognitive heuristics, i.e. mental models that describe how the human brain handle decision-making amongst complex and real-time stimuli. Combined with ON, these cognitive features allow devices to act as proxies in the cyber-world of their users and exchange knowledge to deliver awareness of places in an urban environment. This is done through tags associated with locations. They represent features that are perceived by humans about a place. We consider the extent to which this knowledge becomes available to participants, using interactions with locations and other nodes. This is assessed taking into account a wide range of cognitive parameters. Outcomes are important because this functionality could support a new type of recommendation system that is independent of the traditional forms of networking.
On electrostatic modes in multi-ion and pair-ion collisional plasmas
Creators: name: Vranjes, J.
name: Petrovic, D.
name: Pandey, B. P.
name: Poedts, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: The physics of plasmas containing positive and negative ions is discussed with special attention to the recently produced pair-ion plasma containing ions of equal mass and opposite charge. The effects of the density gradient in the direction perpendicular to the ambient magnetic field vector, observed in the experiment, are discussed. In addition, the possible presence of electrons is discussed in the context of plasma modes propagating at an angle with respect to the magnetic field vector. The electrons may either be added to the plasma or enter the plasma attached to negative ions and then become released from the ions as a result of collisions. It is shown that the electron plasma mode in a cold plasma may become a backward mode in the presence of a density gradient, and this behavior may be controlled either by the electron number density or the mode number in the perpendicular direction. In plasmas with hot electrons an instability may develop, driven by the combination of electron collisions and the density gradient, and in the regime when the ions' response is similar to a sound mode, i.e., for un-magnetized ions, implying mode frequencies much above the ion gyro-frequency or mode wave-lengths shorter than the ion gyro-radius. In the case of a pure pair-ion plasma, for lower frequencies and for parameters close to those used in the recent experiments, the perturbed ions may feel the effects of the magnetic field. In this case the plasma mode also becomes backward, resembling features of an experimentally observed but yet unexplained backward mode.
description: 17 pages plus 5 figures
title: JeromeDL - a Semantic Digital Library
Creators: name: Kruk, Sebastian Ryszard
name: Woroniecki, Tomasz
name: Gzella, Adam
name: Dabrowski, Maciej
Publisher: name: University of Galway
Year: 2007
Subjects: subject: Digital libraries
subject: Metadatabases
subject: Semantic Web

description: JeromeDL is a Semantic Digital Library engine. It uses SemanticWeb and Social Networking technologies to improve browsing and searching for resources. With JeromeDL¿s social and semantic services every library user can bookmark interesting books, articles, or other materials in semantically annotated directories. Users can allow others to see their bookmarks and annotations and share their knowledge within a social network. JeromeDL can also treat a single library resource as a blog post. Users can comment the content of the resource and reply to others¿ comments and this way create new knowledge. All data stored in the library is available in RDF format for querying and processing by other applications. Also the result of every search or browse action is immediately available as a link to RDF. Innovative MBB (MultiBeeBrowse) component offers multifaceted navigation and provides SOA for integration with other applications. TagsTreeMaps allows to easily filter out resources using clustered tags and presented with treemaps layout. Users can also navigate through the presented search results using SIMILE Exhibit component.
Note Illustrative della Carta geologica d'Italia alla scala 1:50.000, F. 609-596 Termini Imerese-Capo Plaia, Servizio Geologico d'Italia - ISPRA
Creators: name: Catalano, R.
name: Avellone, G.
name: Basilone, L.
name: Contino, A.
name: Agate, M.
Publisher: name: INFN Open Access Repository
Year: 2023
Subjects: carta geologica, Termini Imerese, Capo Plaia, Sicilia, Regione Siciliana, CARG, stratigrafia, tettonica, sottosuolo, geological map, stratigraphy, tectonics, subsurface

description: Note illustrative redatte per il Foglio geologico n. 609-596 Termini Imerese-Capo Plaia della Carta Geologica d'Italia alla scala 1:50.000. 224 pp.
GRB 060206 and the quandary of achromatic breaks in afterglow light curves
Creators: name: Curran, P. A.
name: van der Horst, A. J.
name: Wijers, R. A. M. J.
name: Starling, R. L. C.
name: Castro-Tirado, A. J.
name: Fynbo, J. P. U.
name: Gorosabel, J.
name: Jarvinen, A. S.
name: Malesani, D.
name: Rol, E.
name: Tanvir, N. R.
name: Wiersema, K.
name: Burleigh, M. R.
name: Casewell, S. L.
name: Dobbie, P. D.
name: Guziy, S.
name: Jakobsson, P.
name: Jelinek, M.
name: Laursen, P.
name: Levan, A. J.
name: Mundell, C. G.
name: Naranen, J.
name: Piranomonte, S.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Gamma-ray burst afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared to the BeppoSAX era. We present our multi-wavelength analysis of GRB 060206 as an illustrative example of how inferences of jet breaks from optical and X-ray data might differ. The results of temporal and spectral analyses are compared, and attempts are made to fit the data within the context of the standard blast wave model. We find that while the break appears more pronounced in the optical and evidence for it from the X-ray alone is weak, the data are actually consistent with an achromatic break at about 16 hours. This break and the light curves fit standard blast wave models, either as a jet break or as an injection break. As the pre-Swift sample of afterglows are dominated by optical observations, and in the Swift era most well sampled light curves are in the X-ray, caution is needed when making a direct comparison between the two samples, and when making definite statements on the absence of achromatic breaks.
description: 5 pages including 1 figure; accepted for publication in MNRAS Letters after minor revisions
Statistical mechanical theory of an oscillating isolated system. The relaxation to equilibrium
Creators: name: Perez-Madrid, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: In this contribution we show that a suitably defined nonequilibrium entropy of an N-body isolated system is not a constant of the motion in general and its variation is bounded, the bounds determined by the thermodynamic entropy, i.e., the equilibrium entropy. We define the nonequilibrium entropy as a convex functional of the set of n-particle reduced distribution functions (n=0,......., N) generalizing the Gibbs fine-grained entropy formula. Additionally, as a consequence of our microscopic analysis we find that this nonequilibrium entropy behaves as a free entropic oscillator. In the approach to the equilibrium regime we find relaxation equations of the Fokker-Planck type, particularly for the one-particle distribution function.
Local Control of Supercurrent Density in Epitaxial Planar Josephson Junctions
Creators: name: Elfeky, Bassel H.
name: Lotfizadeh, Neda
name: Schiela, William F.
name: Strickland, William M.
name: Dartiailh, Matthieu
name: Sardashti, Kasra
name: Hatefipour, Mehdi
name: Yu, Peng
name: Pankratova, Natalia
name: Lee, Hanho
name: Manucharyan, Vladimir E.
name: Shabani, Javad
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The critical current response to an applied out-of-plane magnetic field in a Josephson junction provides insight into the uniformity of its current distribution. In Josephson junctions with semiconducting weak links, the carrier density and, therefore the overall current distribution could be modified electrostatically via metallic gates. Here, we show local control of the current distribution in an epitaxial Al-InAs Josephson junction equipped with five mini-gates. We demonstrate that not only can the junction width be electrostatically defined but also we can locally adjust the current profile to form superconducting quantum interference devices. Our studies show enhanced edge conduction in such long junctions, which can be eliminated by mini-gates to create a uniform current distribution.
The 21cm Power Spectrum After Reionization
Creators: name: Wyithe, Stuart
name: Loeb, Abraham
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We discuss the 21cm power spectrum (PS) following the completion of reionization. In contrast to the reionization era, this PS is proportional to the PS of mass density fluctuations, with only a small modulation due to fluctuations in the ionization field on scales larger than the mean-free-path of ionizing photons. We derive the form of this modulation, and demonstrate that its effect on the 21cm PS will be smaller than 1% for physically plausible models of damped Ly-alpha systems. In contrast to the 21cm PS observed prior to reionization, in which HII regions dominate the ionization structure, the simplicity of the 21cm PS after reionization will enhance its utility as a cosmological probe by removing the need to separate the PS into physical and astrophysical components. As a demonstration, we consider the Alcock-Paczynski test and show that the next generation of low-frequency arrays could measure the angular distortion of the PS at the percent level for z~3-5.
description: 10 pages, 5 figures. Replaced with version to be published in MNRAS
Efficient implementation of finite volume methods in Numerical Relativity
Creators: name: Alic, Daniela
name: Bona, Carles
name: Bona-Casas, Carles
name: Massó, Joan
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Centered finite volume methods are considered in the context of Numerical Relativity. A specific formulation is presented, in which third-order space accuracy is reached by using a piecewise-linear reconstruction. This formulation can be interpreted as an 'adaptive viscosity' modification of centered finite difference algorithms. These points are fully confirmed by 1D black-hole simulations. In the 3D case, evidence is found that the use of a conformal decomposition is a key ingredient for the robustness of black hole numerical codes.
description: Revised version, 10 pages, 6 figures. To appear in Phys. Rev. D
Periódicos, literatura y reciclaje: aprovechamiento de elementos anticoloniales en el discurso profranquista en Filipinas
Creators: name: Casanova, Rocío Ortuño
Publisher: name: Zenodo
Year: 2022
Subjects: Philippine periodicals, Francoism, Digital Humanities

description: Resumen: La llegada de la falange a Filipinas caló de forma profunda en la sociedad hispanohablante de Manila, como describe Florentino Rodao, llevando a autores hispanofilipinos a escribir odas a Franco (como Lorenzo Pérez Tuells), a que recibieran la orden de Isabel la Católica (como la sufragista y dramaturga Rosa Sevilla de Alvero), o a que escribieran poemas exaltadores del catolicismo y el imperio en periódicos franquistas (como hizo Manuel Bernabé). La hipótesis que se propone en esta presentación para justificar tal entusiasmo por la ideología franquista y las contradicciones que conllevó en el archipiélago es que la penetración del franquismo en la alta sociedad manileña hispanohablante tuvo que ver con un conservadurismo previo y una nostalgia del estatus quo colonial español frente a la invasión estadounidense que cuarenta años antes de la Guerra Civil había copado el debate literario filipino. Varios agentes culturales afiliados a diversas familias del franquismo que habían estado en Filipinas antes de la Guerra Civil y que volverían después, como Federico García Sanchiz, Conrado Blanco y Antonio Pérez de Olaguer, detectaron estos valores en la literatura previa e impulsaron un reciclaje de discursos decimonónicos para promover un franquismo en Filipinas que justificara en parte la vocación de imperio falangista, en precaria situación ante la oposición de la mayoría de las repúblicas latinoamericanas al régimen de Franco. A partir de una aproximación digital de la prensa filipina en español durante los primeros años de la ocupación estadounidense (1898-1915) y en las décadas de 1940 y 1950, junto con un análisis de algunos discursos y poemas se intentará probar este reciclaje retórico.
Thermodynamic behaviour and structural properties of an aqueous sodium chloride solution upon supercooling
Creators: name: Corradini, D.
name: Gallo, P.
name: Rovere, M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We present the results of a molecular dynamics simulation study of thermodynamic and structural properties upon supercooling of a low concentration sodium chloride solution in TIP4P water and the comparison with the corresponding bulk quantities. We study the isotherms and the isochores for both the aqueous solution and bulk water. The comparison of the phase diagrams shows that thermodynamic properties of the solution are not merely shifted with respect to the bulk. Moreover, from the analysis of the thermodynamic curves, both the spinodal line and the temperatures of maximum density curve can be calculated. The spinodal line appears not to be influenced by the presence of ions at the chosen concentration, while the temperatures of maximum density curve displays both a mild shift in temperature and a shape modification with respect to bulk. Signatures of the presence of a liquid-liquid critical point are found in the aqueous solution. By analysing the water-ion radial distribution functions of the aqueous solution we observe that upon changing density, structural modifications appear close to the spinodal. For low temperatures additional modifications appear also for densities close to that corresponding to a low density configurational energy minimum.
description: 10 pages, 13 figures, 2 tables. To be published in J. Chem. Phys
The GLEAM 200 MHz Local Radio Luminosity Function for AGN and Star-forming Galaxies
Creators: name: Franzen, T. M. O.
name: Seymour, N.
name: Sadler, E. M.
name: Mauch, T.
name: White, S. V.
name: Jackson, C. A.
name: Chhetri, R.
name: Quici, B.
name: Bell, M. E.
name: Callingham, J. R.
name: Dwarakanath, K. S.
name: For, B.
name: Gaensler, B. M.
name: Hancock, P. J.
name: Hindson, L.
name: Hurley-Walker, N.
name: Johnston-Hollitt, M.
name: Kapinska, A. D.
name: Lenc, E.
name: McKinley, B.
name: Morgan, J.
name: Offringa, A. R.
name: Procopio, P.
name: Staveley-Smith, L.
name: Wayth, R. B.
name: Wu, C.
name: Zheng, Q.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) is a radio continuum survey at 76-227 MHz of the entire southern sky (Declination $ 55$ mJy across an area of $\approx 16,700~\mathrm{deg}^{2}$. From the optical spectra, we identify the dominant physical process responsible for the radio emission from each galaxy: 73 per cent are fuelled by an active galactic nucleus (AGN) and 27 per cent by star formation. We present the local radio luminosity function for AGN and star-forming galaxies at 200 MHz and characterise the typical radio spectra of these two populations between 76 MHz and $\sim 1$ GHz. For the AGN, the median spectral index between 200 MHz and $\sim 1$ GHz, $α_{\mathrm{high}}$, is $-0.600 \pm 0.010$ (where $S \propto ν^α$) and the median spectral index within the GLEAM band, $α_{\mathrm{low}}$, is $-0.704 \pm 0.011$. For the star-forming galaxies, the median value of $α_{\mathrm{high}}$ is $-0.650 \pm 0.010$ and the median value of $α_{\mathrm{low}}$ is $-0.596 \pm 0.015$. Among the AGN population, flat-spectrum sources are more common at lower radio luminosity, suggesting the existence of a significant population of weak radio AGN that remain core-dominated even at low frequencies. However, around 4 per cent of local radio AGN have ultra-steep radio spectra at low frequencies ($α_{\mathrm{low}} < -1.2$). These ultra-steep-spectrum sources span a wide range in radio luminosity, and further work is needed to clarify their nature.
description: 28 pages, 18 figures, accepted for publication in PASA
On Stability of Pseudo-Conformal Blowup for L^2-critical Hartree NLS
Creators: name: Krieger, Joachim
name: Lenzmann, Enno
name: Raphael, Pierre
Publisher: name: arXiv
Year: 2008
Subjects: subject: Analysis of PDEs (math.AP)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 35Q55, 37K40

description: We consider $L^2$-critical focusing nonlinear Schroedinger equations with Hartree type nonlinearity $$i \pr_t u = -\DD u - \big (Φ\ast |u|^2 \big) u \quad {in $\RR^4$},$$ where $Φ(x)$ is a perturbation of the convolution kernel $|x|^{-2}$. Despite the lack of pseudo conformal invariance for this equation, we prove the existence of critical mass finite-time blowup solutions $u(t,x)$ that exhibit the pseudo-conformal blowup rate $$ \| \nabla u(t) \|_{L^2_x} \sim \frac{1}{|t|} \quad {as} \quad t \nearrow 0 . $$ Furthermore, we prove the finite-codimensional stability of this conformal blow up, by extending the nonlinear wave operator construction by Bourgain and Wang (see \cite{Bourgain+Wang1997}) to $L^2$-critical Hartree NLS.
description: 39 pages
Note on the role of friction-induced momentum conservation in the collisional drift wave instability
Creators: name: Vranjes, J.
name: Poedts, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: The collisional drift wave instability is reexamined taking into account the ion response in the direction parallel to the magnetic field lines, which appears due to friction with electrons and which can not be omitted in view of the momentum conservation. A modified instability threshold is obtained. In plasmas with dominant electron collisions with neutrals, the instability threshold is shifted towards higher frequencies, compared to the case of dominant electron collisions with ions. The difference between the two cases vanishes when the ion sound response is negligible, i.e., when the instability threshold disappears, and both ions and neutrals react to the electron friction in the same manner.
description: 12 pages, 1 figure
Probing the Progenitors of Type Ia Supernovae using Circumstellar Material Interaction Signatures
Creators: name: Clark, Peter
name: Maguire, Kate
name: Bulla, Mattia
name: Galbany, Lluís
name: Sullivan, Mark
name: Anderson, Joseph P.
name: Smartt, Stephen J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: This work aims to study different probes of Type Ia supernova progenitors that have been suggested to be linked to the presence of circumstellar material (CSM). In particular, we have investigated, for the first time, the link between narrow blueshifted NaID absorption profiles and the presence and strength of the broad high-velocity CaII near infrared triplet absorption features seen in Type Ia supernovae around maximum light. With the probes exploring different distances from the supernova; NaID > 10$^{17}$cm, high-velocity CaII features < 10$^{15}$cm. For this, we have used a new intermediate-resolution X-shooter spectral sample of 15 Type Ia supernovae. We do not identify a link between these two probes, implying either that, one (or both) is not physically related to the presence of CSM or that the occurrence of CSM at the distance explored by one probe is not linked to its presence at the distance probed by the other. However, the previously identified statistical excess in the presence of blueshifted (over redshifted) NaID absorption is confirmed in this sample at high significance and is found to be stronger in Type Ia supernovae hosted by late-type galaxies. This excess is difficult to explain as being from an interstellar-medium origin as has been suggested by some recent modelling, as such an origin is not expected to show a bias for blueshifted absorption. However, a circumstellar origin for these features also appears unsatisfactory based on our new results given the lack of link between the two probes of CSM investigated.
description: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. 25 pages, 16 Figures
Size-dependent enhancement of passive microwave rectification in magnetic tunnel junctions with perpendicular magnetic anisotropy
Creators: name: Valli, A. Sidi El
name: Iurchuk, V.
name: Lezier, G.
name: Bendjeddou, I.
name: Lebrun, R.
name: Lamard, N.
name: Litvinenko, A.
name: Langer, J.
name: Wrona, J.
name: Vila, L.
name: Sousa, R.
name: Prejbeanu, I. L.
name: Dieny, B.
name: Ebels, U.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Spintronic rf detectors were demonstrated, recently, for energy harvesting and wireless communication at low input power. Here we report on the optimization of the rectified output dc voltage using magnetic tunnel junctions (MTJ) with strong perpendicular anisotropy (PMA) of both the polarizing and the free layer. The magnetization of the polarizing layer is fixed out of plane, while the free layer thickness is adjusted so that its magnetization orientation changes from in plane to out of plane. The rectification dc output voltage lies in the mV range for moderate rf powers, with a signal to noise ratio of 10 to 100 for Prf = -25dBm. It shows a strong dependence on the dimensions of the MTJ: it increases by a factor of 5 to 6 when reducing the diameter from 150nm to 20nm. This enhancement can be doubled when reducing the FL thickness from 1.8nm to 1.6nm. This dimensional enhancement is attributed to the change of the effective anisotropy of the excited free layer, and the MTJ resistance. The results are of interest for the design of spintronic based rf detectors with optimized sensitivity.
The VLA Low-frequency Sky Survey
Creators: name: Cohen, A. S.
name: Lane, W. M.
name: Cotton, W. D.
name: Kassim, N. E.
name: Lazio, T. J. W.
name: Perley, R. A.
name: Condon, J. J.
name: Erickson, W. C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The Very Large Array (VLA) Low-frequency Sky Survey (VLSS) has imaged 95% of the 3*pi sr of sky north of declination = -30 degrees at a frequency of 74 MHz (4 meter wavelength). The resolution is 80" (FWHM) throughout, and the typical RMS noise level is ~0.1 Jy/beam. The typical point-source detection limit is 0.7 Jy/beam and so far nearly 70,000 sources have been catalogued. This survey used the 74 MHz system added to the VLA in 1998. It required new imaging algorithms to remove the large ionospheric distortions at this very low frequency throughout the entire ~11.9 degree field of view. This paper describes the observation and data reduction methods used for the VLSS and presents the survey images and source catalog. All of the calibrated images and the source catalog are available online (http://lwa.nrl.navy.mil/VLSS) for use by the astronomical community.
description: 53 pages, including 3 tables and 15 figures. Has been accepted for publication in the Astronomical Journal
A Social Cognitive Heuristic for Adaptive Data Dissemination in Mobile Opportunistic Networks
Creators: name: Mordacchini, Matteo
name: Passarella, Andrea
name: Conti, Marco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Human-Computer Interaction (cs.HC)
subject: Multiagent Systems (cs.MA)
subject: FOS: Computer and information sciences
subject: I.6.1; I.6.5; I.2.11

description: It is commonly agreed that data will be one of the cornerstones of Future Internet systems. In this context, mobile Opportunistic Networks (ONs) are one of the key paradigms to support, in a self-organising and decentralised manner, the growth of data generated by localized interactions between users mobile devices, and between them and nearby devices such as IoT nodes. In ONs, the spontaneous collaboration among mobile devices is exploited to disseminate data toward interested users. However, the limited resources and knowledge available at each node, and the vast amount of data available, make it difficult to devise efficient schemes to accomplish this task. Recent solutions propose to equip each device with data filtering methods derived from human data processing schemes, known as Cognitive Heuristics, i.e. very effective methods used by the brain to quickly drop useless information, while keeping the most relevant one. These solutions can become less effective when facing dynamic scenarios or situations where nodes cannot fully collaborate. One of the reasons is that the solutions proposed so far do not take take into account the social structure of the environment where the nodes move in. To be more effective, the selection of information performed by each node should take into consideration this dimension of the environment. In this paper we propose a social-based data dissemination scheme, based on the cognitive Social Circle Heuristic. This evaluation method exploits the structure of the social environment to make inferences about the relevance of discovered information. We show how the Social Circle Heuristic, coupled with a cognitive-based community detection scheme, can be exploited to design an effective data dissemination algorithm for ONs. We provide a detailed analysis of the performance of the proposed solution via simulation.
High-field vortices in Josephson junctions with alternating critical current density
Creators: name: Moshe, M.
name: Mints, R. G.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We study long Josephson junctions with the critical current density alternating along the junction. New equilibrium states, which we call the field synchronized or FS states, are shown to exist if the applied field is from narrow intervals centered around equidistant series of resonant fields, $H_m$. The values of $H_m$ are much higher than the flux penetration field, $H_s$. The flux per period of the alternating critical current density, $ϕ_i$, is fixed for each of the FS states. In the $m$-th FS state the value of $ϕ_i$ is equal to an integer amount of flux quanta, $ϕ_i =mϕ_0$. Two types of single Josephson vortices carrying fluxes $ϕ_0$ or/and $ϕ_0/2$ can exist in the FS states. Specific stepwise resonances in the current-voltage characteristics are caused by periodic motion of these vortices between the edges of the junction.
description: 4 pages, 5 figures
Cool Subdwarf Investigations (CSI) I: New Thoughts for the Spectral Types of K and M Subdwarfs
Creators: name: Jao, Wei-Chun
name: Henry, Todd J.
name: Beaulieu, Thomas D.
name: Subasavage, John P.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Using new spectra of 88 K and M-type subdwarfs, we consider novel methods for assigning their spectral types and take steps toward developing a comprehensive spectral sequence for subdwarf types K3.0 to M6.0. The types are assigned based on the overall morphology of spectra covering 6000Åto 9000Å. The types and sequence presented link the spectral types of cool subdwarfs to their main sequence counterparts, with emphasis on the relatively opacity-free region from 8200--9000Å. When available, supporting abundance, kinematic, and trigonometric parallax information is used to provide more complete portraits of the observed subdwarfs. We find that the CaHn (n $=$ 1--3) and TiO5 indices often used for subdwarf spectral typing are affected in complicated ways by combinations of subdwarfs' temperatures, metallicities, and gravities, and we use model grids to evaluate the trends in all three parameters. Because of the complex interplay of these three characteristics, it is not possible to identify a star as an ``extreme'' subdwarf simply based on very low metallicity, and we suggest that the modifiers ``extreme'' or ``ultra'' only outline locations on spectroscopic indices plots, and should not be used to imply low or very low metallicity stars. In addition, we propose that ``VI'' be used to identify a star as a subdwarf, rather than the confusing ``sd'' prefix, which is also used for hot O and B subdwarfs that are unrelated to the cool subdwarfs discussed in this paper.
description: 84 pages, 35 figures, accepted to AJ
Total Collisions in the N-Body Shape Space
Creators: name: Mercati, Flavio
name: Reichert, Paula
Publisher: name: arXiv
Year: 2021
Subjects: subject: Classical Physics (physics.class-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We discuss the total collision singularities of the gravitational N-body problem on shape space. Shape space is the relational configuration space of the system obtained by quotienting ordinary configuration space with respect to the similarity group of total translations, rotations, and scalings. For the zero-energy gravitating N-body system, the dynamics on shape space can be constructed explicitly and the points of total collision, which are the points of central configuration and zero shape momenta, can be analyzed in detail. It turns out that, even on shape space where scale is not part of the description, the equations of motion diverge at (and only at) the points of total collision. We construct and study the stratified total-collision manifold and show that, at the points of total collision on shape space, the singularity is essential. There is, thus, no way to evolve the solutions through these points. This mirrors closely the big bang singularity of general relativity, where the homogeneous-but-not-isotropic cosmological model of Bianchi IX shows an essential singularity at the big bang. A simple modification of the general-relativistic model (the addition of a stiff matter field) changes the system into one whose shape-dynamical description allows for a deterministic evolution through the singularity. We suspect that, similarly, some modification of the dynamics would be required in order to regularize the total collision singularity of the N-body model.
Electromagnetic Transition Form Factors of Nucleon Resonances
Creators: name: Burkert, Volker D.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data resolve a long-standing puzzle of the nature of the Roper resonance, and confirm the assertion of the symmetric constituent quark model of the Roper as the first radial excitation of the nucleon. The data on $nπ^+$ production at high $Q^2$ confirm the slow fall off of the $S_{11}(1535)$ transition form factor with $Q^2$, and better constrain the branching ratios $β_{Nπ}=0.50$ and $β_{Nη}=0.45$. Also, new results on the transition amplitudes for the $D_{13}(1520)$ resonance are presented showing a rapid change from helicity 3/2 dominance seen at the real photon point to helicty 1/2 dominance at higher $Q^2$.
description: 5 pages, 7 figures
A Computational Approach to Essential and Nonessential Objective Functions in Linear Multicriteria Optimization
Creators: name: Malinowska, Agnieszka B.
name: Torres, Delfim F. M.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: 90B50; 90C29

description: The question of obtaining well-defined criteria for multiple criteria decision making problems is well-known. One of the approaches dealing with this question is the concept of nonessential objective function. A certain objective function is called nonessential if the set of efficient solutions is the same both with or without that objective function. In this paper we put together two methods for determining nonessential objective functions. A computational implementation is done using a computer algebra system.
description: To be partially presented at the 23rd IFIP TC 7 International Conference on System Modelling and Optimization, Cracow, Poland, July 23-27, 2007. Work supported by KBN under Bialystok Technical University grant W/WI/17/07; and the R&D unit CEOC of the University of Aveiro through FCT and FEDER/POCI 2010
title: D-FOAF - Distributed Identity Management based on Social Networks
Creators: name: Kruk, Sebastian Ryszard
name: Gzella, Adam
name: Grzonkowski, Slawomir
Publisher: name: University of Galway
Year: 2006
Subjects: subject: Identity management
subject: Distributed computing
subject: Social networking
subject: Cyberinfrastructure
subject: Online social networks

description: Contemporary Web consists of more than just information, it provides a large number of services, which often require identi¿cation of it¿s users. Since distributed or shared identi¿cation systems are not yet widely adopted many users have to maintain a large number of different credentials for different services. Furhermore current authorisation systems require strict centralisation of the authorisation procedure. Although the feature of enabling user¿s friends or good friends of a friends to access user resources would be beneficial for services and business on the Web, it is not usually offered by existing systems. In this article we present D-FOAF, a distributed identity management system that utilizes social networks. We show how information inherent in social networks can be utilised to provide community driven access rights delegation and distributed authorisation.
Relaxation dynamics of aftershocks after large volatility shocks in the SSEC index
Creators: name: Mu, Guo-Hua
name: Zhou, Wei-Xing
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Finance (q-fin.ST)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Economics and business
subject: FOS: Physical sciences

description: The relaxation dynamics of aftershocks after large volatility shocks are investigated based on two high-frequency data sets of the Shanghai Stock Exchange Composite (SSEC) index. Compared with previous relevant work, we have defined main financial shocks based on large volatilities rather than large crashes. We find that the occurrence rate of aftershocks with the magnitude exceeding a given threshold for both daily volatility (constructed using 1-minute data) and minutely volatility (using intra-minute data) decays as a power law. The power-law relaxation exponent increases with the volatility threshold and is significantly greater than 1. Taking financial volatility as the counterpart of seismic activity, the power-law relaxation in financial volatility deviates remarkably from the Omori law in Geophysics.
description: 8 EPL pages including 3 figures and 3 tables
The decarbonylation of aldehydes using ruthenium porphyrins
Creators: name: Tarpey, Bláithín
Publisher: name: University of British Columbia
Year: 2010

description: The topic of this thesis is the catalytic and stoichiometric decarbonylation of aldehydes. A carbonylation reaction, the reaction of RuTPP(n-Bu₃P)₂ with CO gas was also studied. A catalytic decarbonylation system, using RuTPP(PPh₃)₂ as catalyst plus added excess tri-n-butylphosphine in acetonitrile-dichloromethane, was employed to decarbonylate several organic aldehydes. This system proved to be an effective decarbonylation agent, which also exhibited some selectivity. Some mechanistic studies were carried out in an attempt to elucidate the details of the reaction mechanism. From these and other findings in this laboratory, a tentative mechanism was proposed for the decarbonylation reaction. A radical mechanism, involving Ru(III) intermediates was favoured on the basis of e.s.r. data, spectral evidence and cyclic voltammetry studies. However, no intermediates were isolated. The full details of the mechanism, such as the precise nature of the postulated intermediates, have not been fully determined, although there are indications that solvated species, like RuTPP(CO)(CH₃CN), may be important. The stoichiometric reaction between RuTPP(n-Bu₃P)₂ and phenylacetaldehyde was also studied. The kinetic analysis indicated that the reaction, equation i, RuTPP(n-Bu₃P)₂ + C₆H₅CH₂CH0 --> RuTPP(CO)(n-Bu₃P) + n-Bu₃P + C₆H₅CH₃ equation i followed a pseudo-first-order rate law in the absence of excess phosphine, however, the actual k obsd values were found to be irreproducible. Some features of this reaction, such as the failure of the reaction to go to completion, and also the effect of trace oxygen on the reaction were investigated. The carbonylation of RuTPP(n-Bu₃P)₂ by CO gas was of interest, with respect to the catalytic reaction, which seems to involve pretreatment with CO (or aldehyde) to form a phosphine monocarbonyl. The reaction was found to follow a simple dissociative mechanism, which is similar to that observed for analogous M(porp)L₂, where M = Ru or Fe. A K value of 0.054 at 26°C was obtained and individual rate constants were calculated also. The temperature dependence of K was used to find the thermodynamic parameters ΔS° and ΔH° for the reaction. Some electrochemical studies were performed on RuTPP(n-Bu₃P)₂ and the corresponding monocarbonyl, RuTPP(CO)(n-Bu₃P). Electrochemical oxidation of RuTPP(CO)(n-Bu₃P) yielded a ir-cation radical, whereas bromine oxidation appeared to effect oxidation of the metal.
Constraints on $R$-process Nucleosynthesis from $^{129}$I and $^{247}$Cm in the Early Solar System
Creators: name: Banerjee, Projjwal
name: Wu, Meng-Ru
name: K, Jeena S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: GW170817 has confirmed binary neutron star mergers as one of the sites for rapid neutron capture ($r$) process. However, there are large theoretical and experimental uncertainties associated with the resulting nucleosynthesis calculations and additional sites may be needed to explain all the existing observations. In this regard, abundances of short-lived radioactive isotopes (SLRIs) in the early solar system (ESS), that are synthesized exclusively by $r$-process, can provide independent clues regarding the nature of $r$-process events. In this work, we study the evolution of $r$-process SLRIs $^{129}$I and $^{247}$Cm as well as the corresponding reference isotopes $^{127}$I and $^{235}$U at the Solar location. We consider up to three different sources that have distinct $^{129}$I/$^{247}$Cm production ratios corresponding to the varied $r$-process conditions in different astrophysical scenarios. In contrast to the results found by Côté et al. (2021), we find that $^{129}$I and $^{247}$Cm in the ESS do not come entirely from a single major event but get contributions from at least two more minor contributors. This has a dramatic effect on the evolution of the $^{129}$I/$^{247}$Cm ratio, such that the measured ESS value in meteorites may not correspond to that of the "$last$" major $r$-process event. Interestingly, however, we find that the $^{129}$I/$^{247}$Cm ratio, in combination with the observed $^{129}$I/$^{127}$I and $^{247}$Cm/$^{235}$U ratio in the ESS, can still provide important constraints on the properties of proposed $r$-process sources operating in the Milky Way.
description: 14 pages, 5 figures, 7 tables
Are generalized and transverse momentum dependent parton distributions related ?
Creators: name: Meissner, S.
name: Metz, A.
name: Goeke, K.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The present knowledge on non-trivial relations between generalized parton distributions on the one hand and transverse momentum dependent distributions on the other is reviewed. While various relations can be found in the framework of spectator models, so far no model-independent non-trivial relations have been established.
description: 4 pages, talk given at the conference DIS 2007
Deformed boson-fermion correspondence, Q-bosons, and topological strings on the conifold
Creators: name: Sułkowski, Piotr
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Other Condensed Matter (cond-mat.other)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We consider two different physical systems for which the basis of the Hilbert space can be parametrized by Young diagrams: free complex fermions and the phase model of strongly correlated bosons. Both systems have natural, well-known deformations parametrized by a parameter Q: the former one is related to the deformed boson-fermion correspondence introduced by N. Jing, while the latter is the so-called Q-boson, arising also in the context of quantum groups. These deformations are equivalent and can be realized in the same way in the algebra of Hall-Littlewood symmetric functions. Without a deformation, these reduce to Schur functions, which can be used to construct a generating function of plane partitions, reproducing a topological string partition function on $C^3$. We show that a deformation of both systems leads then to a deformed generating function, which reproduces topological string partition function of the conifold, with the deformation parameter Q identified with the size of $P^1$. Similarly, a deformation of the fermion one-point function results in the A-brane partition function on the conifold.
description: 20 pages, 1 figure; version published in JHEP
title: Mensch-Computer-Interaktion als zentrales Gebiet der Informatik – Bestandsaufnahme, Trends und Herausforderungen
Creators: name: Koch, Michael
name: Ziegler, Jürgen
name: Reuter, Christian
name: Schlegel, Thomas
name: Prilla, Michael
Publisher: name: Springer
Year: 2022

description: Mensch-Computer-Interaktion (MCI) beschäftigt sich mit Fragen rund um die benutzer- und kontextegerechte Gestaltung von IT-Systemen. Ohne MCI ist die vielbeschworene digitale Transformation nicht möglich, da Systeme, die nicht benutzbar (gebrauchstauglich) sind, für ihre Nutzer wertlos oder sogar gefährlich sind – erst Nutzbarkeit schafft Nutzen! In diesem Beitrag sammeln wir einige Beispiele dafür, wo und wie MCI in der Entwicklung zukünftiger IT-Systeme relevant ist – von nutzerzentrierter künstlicher Intelligenz über benutzbare Sicherheit, cyberphysische Systeme und digital Arbeit hin zu Augmented Reality und Virtual Reality.