cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
ERICC Policy Brief _ State of Effectiveness Research on Support to Children’s Education in Conflicts and Protracted Crises
Creators: name: ERICC Consortium
name: Diazgranados Ferráns, Silvia
name: Sloane, Phoebe
name: Thuo, Bernard
name: Al Masri, Anas
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 390201
subject: Education policy

description: This policy brief synthesises findings from a forthcoming review of effectiveness research on education interventions in conflict and protracted crisis settings. It outlines the types of effectiveness research available, the populations targeted, and the learning drivers and outcomes pursued. It shows that evidence of impact for education interventions remains limited in strength and scope and is virtually missing for interventions targeting youth. A case study presented then illustrates best practice in this research area, demonstrating the need for rigorous and disaggregated evidence to drive education impact that is (cost-)effective and equitable. The brief concludes with recommended actions to address the limitations identified in the current research landscape, including expansion of research on the impact of early childhood and youth education interventions, remote delivery methods, and strategies to maintain educational continuity during disruptions. Key recommendations also include mainstreaming the collection and analysis of costing data to assess cost-effectiveness, disaggregating data to support equitable interventions, and investing in robust causal research methodologies.
On metrizable enveloping semigroups
Creators: name: Glasner, Eli
name: Megrelishvili, Michael
name: Uspenskij, Vladimir V.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Dynamical Systems (math.DS)
subject: General Topology (math.GN)
subject: FOS: Mathematics
subject: 54H20 (Primary). 22A25, 22F05, 37B05, 46B10, 46B22, 54H15 (Secondary)

description: When a topological group $G$ acts on a compact space $X$, its enveloping semigroup $E(X)$ is the closure of the set of $g$-translations, $g\in G$, in the compact space $X^X$. Assume that $X$ is metrizable. It has recently been shown by the first two authors that the following conditions are equivalent: (1) $X$ is hereditarily almost equicontinuous; (2) $X$ is hereditarily non-sensitive; (3) for any compatible metric $d$ on $X$ the metric $d_G(x,y):=\sup\{d(gx,gy): g\in G\}$ defines a separable topology on $X$; (4) the dynamical system $(G,X)$ admits a proper representation on an Asplund Banach space. We prove that these conditions are also equivalent to the following: the enveloping semigroup $E(X)$ is metrizable.
description: 11 pages. Revised version 20 September 2006. Minor improvements
Asymptotic $P_N$ Approximation in Radiative Transfer Problems
Creators: name: Harel, Re'em
name: Burov, Stanislav
name: Heizler, Shay I.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: We study the validity of the time-dependent asymptotic $P_N$ approximation in radiative transfer of photons. The time-dependent asymptotic $P_N$ is an approximation which uses the standard $P_N$ equations with a closure that is based on the asymptotic solution of the exact Boltzmann equation for a homogeneous problem, in space and time. The asymptotic $P_N$ approximation for radiative transfer requires careful treatment regarding the closure equation. Specifically, the mean number of particles that are emitted per collision ($ω_{\mathrm{eff}}$) can be larger than one due to inner or outer radiation sources and the coefficients of the closure must be extended for these cases. Our approximation is tested against a well-known radiative transfer benchmark. It yields excellent results, with almost correct particle velocity that controls the radiative heat-wave fronts.
description: 18 pages, 5 figures
Exact Quantization Rule to the Kratzer-Type Potentials: An Application to the Diatomic Molecules
Creators: name: Ikhdair, Sameer M.
name: Sever, RAmazan
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: For any arbitrary values of $n$ and $l$ quantum numbers, we present a simple exact analytical solution of the $D$-dimensional ($D\geq 2$) hyperradial Schr% ödinger equation with the Kratzer and the modified Kratzer potentials within the framework of the exact quantization rule (EQR) method. The exact energy levels $(E_{nl})$ of all the bound-states are easily calculated from this EQR method. The corresponding normalized hyperradial wave functions $% (ψ_{nl}(r))$ are also calculated. The exact energy eigenvalues for these Kratzer-type potentials are calculated numerically for the typical diatomic molecules $LiH,$ $CH,$ $HCl,$ $CO,$ $NO,$ $O_{2},$ $N_{2}$ and $I_{2}$ for various values of $n$ and $l$ quantum numbers. Numerical tests using the energy calculations for the interdimensional degeneracy ($D=2-4$) for $I_{2}, $ $LiH,$ $HCl,$ $O_{2},$ $NO$ and $CO$ are also given. Our results obtained by EQR are in exact agreement with those obtained by other methods.
description: 26 pages
Quantum critical point in graphene approached in the limit of infinitely strong Coulomb interaction
Creators: name: Son, D. T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Motivated by the physics of graphene, we consider a model of N species of 2+1 dimensional four-component massless Dirac fermions interacting through a 3D instantaneous Coulomb interaction. We show that in the limit of infinitely strong Coulomb interaction the system approaches a quantum critical point, at least for sufficiently large fermion degeneracy. In this regime the system exhibits invariance under scale transformations in which time and space scale by different factors. The elementary excitations are fermions with dispersion relation omega ~ p^z, where the dynamic critical exponent z depends on N. In the limit of large N we find z=1-4/(π^2 N). We argue that due to the numerically large Coulomb coupling, graphene (freely suspended) in vacuum stays near the scale-invariant regime in a large momentum window, before eventually flowing to the trivial fixed point at very low momentum scales.
description: 14 pages, 5 figures; added an Appendix with technical details
Proton decay, supersymmetry breaking and its mediation
Creators: name: Bajc, Borut
name: Senjanovic, Goran
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the breaking of supersymmetry and its transmission to the light states in the context of the minimal SU(5) grand unified theory, with no additional singlets. This simple theory can be taken as a prototype for a program of breaking simultaneously grand unified symmetry and supersymmetry. The main predictions are: (i) d=6 proton decay is completely negligible and d=5 is in accord with experiment, (ii) supersymmetry breaking is mainly mediated by gravity.
description: 18 pages
In--Flight ($K^-,p$) Reactions for the Formation of Kaonic Atoms and Kaonic Nuclei in Green function method
Creators: name: Yamagata, J.
name: Nagahiro, H.
name: Hirenzaki, S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study theoretically the kaonic atom and kaonic nucleus formations in the in--flight ($K^-,p$) reactions using the Green function method, which is suited to evaluate formation rates both of stable and unstable bound systems. We consider $^{12}$C and $^{16}$O as the targets and calculate the spectra of the ($K^-,p$) reactions. We conclude that a no peak structure due to kaonic nucleus formation is expected in the reaction spectra calculated with the chiral unitary kaon--nucleus optical potential. In the spectra with the phenomenological deep kaon--nucleus potential, we may have possibilities to observe some structures due to kaonic nucleus states. For all cases, we have peaks due to the kaonic atom formations in the reaction spectra.
description: 10 pages, 9 figures, newly calculated results added, revisions and updated references, to appear in Physical Review C
The U(1)_A Anomaly and QCD Phenomenology
Creators: name: Shore, G. M.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The role of the $U(1)_A$ anomaly in QCD phenomenology is reviewed, focusing on the relation between quark dynamics and gluon topology. Topics covered include a generalisation of the Witten-Veneziano formula for the mass of the $η'$, the determination of pseudoscalar meson decay constants, radiative pseudoscalar decays and the $U(1)_A$ Goldberger-Treiman relation. Sum rules are derived for the proton and photon structure functions $g_1^p$ and $g_1^\c$ measured in polarised deep-inelastic scattering. The first moment sum rule for $g_1^p$ (the `proton spin' problem) is confronted with new data from COMPASS and HERMES on the deuteron structure function and shown to be quantitatively explained in terms of topological charge screening. Proposals for experiments on semi-inclusive DIS and polarised two-photon physics at future $ep$ and high-luminosity $e^+ e^-$ colliders are discussed.
description: 50 pages, 17 figures
Σύνθετα υλικά οξειδίου του γραφίτη και χιτοζάνης/ μαγνητικής χιτοζάνης: παρασκευή και συγκριτική μελέτη απομάκρυνσης χρωστικής Reactive Black 5 από υδατικά διαλύματα
Creators: name: Τραυλού, Νικολίνα-Ελένη Αθανασίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Οξείδιο του γραφίτη
Χιτοζάνη
χρωστικές
Graphite oxide
Chitosan
dyes

description: Σκοπός της παρούσας εργασίας είναι η ανάπτυξη και εξέταση νέων προσροφητικών υλικών που βασίζονται στο οξείδιο του γραφίτη για την απομάκρυνση της χρωστικής αντίδρασης Reactive Black 5 από υδατικά διαλύματα, με τη μέθοδο της ρόφησης . Συνεπώς, στην εργασία παρασκευάστηκαν, τα εξής ροφητικά υλικά: α) οξείδιο του γραφίτη (GO), β) χιτοζάνη, γ) μαγνητικό οξείδιο του γραφίτη, δ) μαγνητική χιτοζάνη. Επίσης, παρασκευάστηκαν σύνθετα υλικά του οξειδίου του γραφίτη με βάση τη χιτοζάνη και τη μαγνητική χιτοζάνη, τα οποία είναι τα εξής: ε) οξείδιο του γραφίτη-χιτοζάνη και στ) οξείδιο του γραφίτη- μαγνητική χιτοζάνη. Τα παραπάνω υλικά χαρακτηρίστηκαν, ενώ μελετήθηκαν και οι παράγοντες που επηρεάζουν την προσροφητική ικανότητα. Οι προσροφητικές χωρητικότητες βρέθηκαν υψηλότερες σε σύγκριση με αυτές της βιβλιογραφίας. Η προσρόφηση απεδείχθει πιο αποτελεσματική σε χαμηλές τιμές pH και υψηλές θερμοκρασίες. Επίσης μελετήθηκαν τα θερμοδυναμικά δεδομένα. Έτσι, η αύξηση υης ιονικής ισχύος ενισχύει την απομάκρυνση της χρωστικής RB5,, σε υψηλές συγκεντρώσεις. Τα αποτελέσματα φανερώνουν ότι τα προσροφητικά υλικά με βάση το οξείδιο του γραφίτη είναι τα πλέον κατάλληλα για την επεξεργασία των υγρών αποβλήτων βιομηχανιών χρωμάτων.
description: The ultimate goal of this study is to develop and examine new sorbents based on graphite oxide and chitosan for the removal of Reactive Black 5 (RB5) from aqueous solutions by adsorption. Consequently, in this study the materials which were prepared are the following : a) graphite oxide (GO), b) chitosan, c) magnetic graphite oxide and d) magnetic chitosan. Nanocomposites of graphite oxide were also produced using chitosan and magnetic chitosan in order to prepare: e) graphite oxide – chitosan and f) graphite oxide – magnetic chitosan. The above materials were characterized, while, the factors affecting the removal behavior were studied. The absorption capacities were high compared to the literature. The removal process is fast and more efficient at lower pH values and at higher temperatures while, thermodynamics of the removal process were clarified. The increase of ionic strength would further enhance the removal process when RB5 concentration is high. The results indicate that GO-based adsorbents can be applied in treating industrial effluent and contaminated natural water. The implications to graphite oxide-based environmental technologies are discussed.
University students’ conceptual understanding and application of meiosis
Creators: name: Lai, Patrick K. T.
Publisher: name: University of British Columbia
Year: 2009

description: Studies in the general literature of genetics learning have identified the students' understanding of meiosis for diploid organisms at both the high school and college levels. It was generally believed by these researchers that a canonical, conceptual understanding of meiosis is sufficient for students to advance in genetics. No prior research has documented the students' application of knowledge of meiosis to a realistic genetics problem that involves haploid organisms. This study has extended the genetics learning literature by identifying some of the problems which students encounter when asked to explain their conceptual understanding and when solving a problem from their undergraduate genetics programme. In particular, the study focused on the topic area of meiosis. Three areas of students' understanding were scrutinized: their conceptualizations of meiosis for a diploidcell; their approaches to addressing a genetics problem which involved a haploid organism; and, the possible relationships between the approaches and the meiosis conceptualizations. The research approach taken was embedded in a research perspective known as "phenomenography" (Marton, 1981). Phenomenography is the study of the qualitatively different ways in which people conceptualize various aspects of phenomena. The data source for the study included a set of interviews conducted with ten undergraduate genetics students using two different task contexts. These included i) a meiosis task and ii) an applied genetics question that involved the concept of meiosis, using a haploid organism. The outcomes of the study yielded an identification and description of the students' conceptualizations of meiosis and a description of their approaches to addressing the genetics problem. The findings indicated that a good understanding of meiosis is a necessary but not sufficient condition for the students to solve the novel problem. A close examination of the successful approaches revealed that a sound understanding of the biology of the haploid organism and of the processes of non-disjunction and crossing-over were necessary for the students to generate reasonable hypotheses about the data given in this problem. Implications for further research and for the teaching of genetics are discussed.
Comet 2P/Encke in apparitions of 2013 and 2017: I. Imaging photometry and long-slit spectroscopy
Creators: name: Rosenbush, Vera
name: Ivanova, Oleksandra
name: Kleshchonok, Valerii
name: Kiselev, Nikolai
name: Afanasiev, Viktor
name: Shubina, Olena
name: Petrov, Dmitry
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We present the results of imaging photometric and long-slit spectroscopic observations of comet 2P/Encke performed at the heliocentric distance 0.56 au, geocentric distance 0.65 au, and phase angle 109.2 deg on November 4, 2013 and at 1.05 au, 1.34 au, and 46.8 deg on January 23, 2017. Observations were carried out at the 6-m BTA telescope of the Special Astrophysical Observatory (Russia) with the multimode focal reducer SCORPIO-2. In 2013, the direct images of comet Encke were obtained with the broad-band V filters, whereas in 2017 the narrow-band cometary BC, RC, and NH2 filters as well as the medium-band SED500 and broad-band r-sdss filters were used for observations. About 60 emissions belonging to the CN, C2, C3, NH2, CH, and CO+ molecules were identified within the range 3750-7100 Å. The ratios of the production rates C2/CN and C3/CN correspond to the typical comets, not depleted in the carbon-chain. A complex structure of the coma was detected in both observational periods. In January 2017, the dust was in general concentrated near the nucleus, the dust/gas ratio was 2.9 in the r-sdss filter, however, this ratio was larger than 1 at distances 3000-40000 km from the nucleus. We found that about 75% of the flux of the reflected light in the central pixel was due to the nucleus, whereas the nucleus's flux contributed 48% in the total intensity of the 2000 km area of the coma. We found that after correction for the dust coma contamination the nucleus magnitude is 18.8m+/-0.2m.
description: 41 pages, 16 figures, 7 tables
Water-Cooled (sub)-Neptunes Get Better Gas Mileage
Creators: name: Yoshida, Tatsuya
name: Gaidos, Eric
Publisher: name: arXiv
Year: 2025
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The demographics of sub-Jovian planets around low-mass stars is dominated by populations of ``sub-Neptunes" and ``super-Earths", distinguished by the presence or absence of envelopes of low-molecular weight volatiles, i.e., H2, He, and H2O. The current paradigm is that sub-Neptunes on close-in orbits evolve into super-Earths via atmospheric escape driven by high-energy stellar irradiation. We use an integrated hydrodynamic-radiation-chemical network model of outflow to demonstrate that this escape is modulated by the abundance of H2O, an efficient infrared coolant. Increasing H2O/H2 at the base of the flow induces an order-of-magnitude decline in escape rate, with definitive consequences for retention of envelopes over Gyr. We show that saturation limits on H2O in the upper atmospheres of temperate sub-Neptunes could explain the paradoxical observations that these objects disappear more rapidly than their counterparts closer to their host stars. We also propose that the scarcity of sub-Neptunes around very low mass stars could be related to the water-poor chemistry of their antecedent protoplanetary disks. Observations of atmospheric H2O by JWST as well as searches for atmospheric escape from younger planets using H and He lines could test these predictions.
description: 11 pages, 4 figures
D1.2 - Plan for the design of a portable test suite
Creators: name: van Leeuwen, Caspar
name: Hoste, Kenneth
name: Peeters, Lara
Publisher: name: Zenodo
Year: 2024
Subjects: MultiXscale, HPC, software , CI/CD , testing , scalability

description: Plan on how to design a test suite for the shared software stack that can run ona wide range of systems.
Evolution of the Quiescent Disk surrounding a Superoutburst of the Dwarf Nova TW Virginis
Creators: name: Dai, Zhibin
name: Szkody, Paula
name: Garnavich, Peter M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Portions of the Kepler K2 Short Cadence light curve of the dwarf nova (DN) TW Vir at quiescence are investigated using light curve modeling. The light curve was separated into 24 sections, each with a data length of $\sim\,$0.93\,d, comprising 4 sections before and 20 after a superoutburst (SO). Due to the morphological differences, the quiescent orbital modulation is classified into three types. Using a fixed disk radius and the two component stellar parameters, all 24 synthetic disk models from the sections show a consistent configuration, consisting of a disk and two hotspots: one at the vertical side of the edge of the disk and the other one on the surface of the disk. Before the SO, the disk and a ringlike surface-hotspot are suddenly enhanced, triggering a precursor and then SO. At the end of the quiescent period following the SO and before the first normal outburst, the edge-hotspot becomes hotter, while the surface-hotspot switches into a ``coolspot" with a coverage of nearly one-half of the disk surface. During quiescence, the surface-hotspot is always located at the outer part of the disk with a constant radial width. A flat radial temperature distribution of the disk is found and appears flatter when approaching the outburst. Like many U\,Gem-type DN with orbital periods of 3-5\,hr, the mass transfer rate is significantly lower than the predictions of the standard/revised models of CV evolution.
description: 23 pages, 13 figures, accepted by AJ
Non-thermal radio emission from O-type stars. II. HD 167971
Creators: name: Blomme, R.
name: De Becker, M.
name: Runacres, M. C.
name: Van Loo, S.
name: Gunawan, D. Y. A. Setia
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: HD 167971 is a triple system consisting of a 3.3-day eclipsing binary (O5-8 V + O5-8 V) and an O8 supergiant. It is also a well known non-thermal radio emitter. We observed the radio emission of HD 167971 with the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA). By combining these data with VLA archive observations we constructed a radio lightcurve covering a 20-yr time-range. We searched for, but failed to find, the 3.3-day spectroscopic period of the binary in the radio data. This could be due to the absence of intrinsic synchrotron radiation at the colliding-wind region between the two components of the eclipsing binary, or due to the large amount of free-free absorption that blocks the synchrotron radiation. We are able to explain many of the observed characteristics of the radio data if the non-thermal emission is produced in a colliding-wind region between the supergiant and the combined winds of the binary. Furthermore, if the system is gravitationally bound, the orbital motion occurs over a period of ~ 20 years, or longer, as suggested by the long-term variability in the radio data. We argue that the variability is due to the free-free absorption that changes with orbital phase or may also in part be due to changes in separation, should the orbit be eccentric.
description: 10 pages; 3 figures; accepted by A&A
The History of Nuclidic Masses and of their Evaluation
Creators: name: Audi, G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: History and Philosophy of Physics (physics.hist-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: This paper is centered on some historical aspects of nuclear masses, and their relations to major discoveries. Besides nuclear reactions and decays, the heart of mass measurements lies in mass spectrometry, the early history of which will be reviewed first. I shall then give a short history of the mass unit which has not always been defined as one twelfth of the carbon-12 mass. When combining inertial masses from mass spectrometry with energy differences obtained in reactions and decays, the conversion factor between the two is essential. The history of the evaluation of the nuclear masses (actually atomic masses) is only slightly younger than that of the mass measurements themselves. In their modern form, mass evaluations can be traced back to 1955. Prior to 1955, several tables were established, the oldest one in 1935.
description: 17 pages, Contribution to the special issue of the International Journal of Mass Spectrometry (IJMS) in the honor of the 65th anniversary of Jurgen Kluge's birthday
Resonant absorption in complicated plasma configurations: applications to multi-stranded coronal loop oscillations
Creators: name: Terradas, J.
name: Arregui, I.
name: Oliver, R.
name: Ballester, J. L.
name: Andries, J.
name: Goossens, M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the excitation and damping of transverse oscillations in a multi-stranded model of a straight line-tied coronal loop. The transverse geometry of our equilibrium configuration is quite irregular and more realistic than the usual cylindrical loop model. By numerically solving the time-dependent ideal magnetohydrodynamic equations in two dimensions we show how the global motion of the whole bundle of strands, excited by an external disturbance, is converted into localized Alfvénic motions due to the process of resonant absorption. This process produces the attenuation of the transverse oscillations. At any location in the structure two dominant frequencies are found, the frequency of the global mode, or quasi-mode, and the local Alfvén frequency. We find that the mechanism of mode conversion, due to the coupling between fast and Alfvén waves, is not compromised by the complicated geometry of the model. We also show that it is possible to have energy conversion not only at the external edge of the composite loop but also inside the structure. The implications of these results and their relationship with the observations are discussed.
Online rating system development using blockchain-based distributed ledger technology
Creators: name: Shaker, Monir
name: Aliee, Fereidoon Shams
name: Fotohi, Reza
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: In most websites, the online rating system provides the ratings of products and services to users. Lack of trust in data integrity and its manipulation has hindered fulfilling user satisfaction. Since existing online rating systems deal with a central server, all rating data is stored on the central server. Therefore, all rating data can be removed, modified, and manipulated by the system manager to change the ratings in favor of the service or product provider. In this paper, an online rating system using distributed ledger technologies has been presented as the proposed system to solve all the weaknesses of current systems. Distributed ledger technologies are completely decentralized and there is no centralization on them by any institution. Distributed ledger technologies have different variants. Among distributed ledger technologies, blockchain technology has been used in the proposed rating system because of its support for smart contracts. In the proposed online rating system, the Ethereum platform has been chosen from different blockchain platforms that have a public permission network. In this system, the raters cannot rate unless they submit a request to the system and be authorized to take part in the online product rating process. The important feature of the Ethereum platform is its support for smart contracts, which can be used to write the rating contract in the Solidity language. Also, using Proof of Authority consensus mechanisms, all rating transactions are approved by the surveyors. Since in the real Ethereum system, each rating transaction is sent to the network by the raters, some gas must be paid for each rating transaction. However, since this method is expensive, TestNet blockchain can be used in the rating system. Finally, the proposed rating system was used for rating the restaurants of a website and its features were tested.
description: 25 figures, 5 tables, Journal Wireless Netw (2021)
Split fermion quasi-normal modes
Creators: name: Cho, H. T.
name: Cornell, A. S.
name: Doukas, Jason
name: Naylor, Wade
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In this paper we use the conformal properties of the spinor field to show how we can obtain the fermion quasi-normal modes for a higher dimensional Schwarzschild black hole. These modes are of interest in so called split fermion models, where quarks and leptons are required to exist on different branes in order to keep the proton stable. As has been previously shown, for brane localized fields, the larger the number of dimensions the faster the black hole damping rate. Moreover, we also present the analytic forms of the quasi-normal frequencies in both the large angular momentum and the large mode number limits.
description: 11 pages, 7 figures, version 2 added references
Cosmological perturbations with non-ideal fluids:
Creators: name: Kodra, Dritan (Κόντρα, Ντριτάν Φατμίρ)
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Διαταραχές
Κοσμολογία
Ιξώδες
Perturbations
Cosmology
Viscosity

description: Οι διαταραχές που παρατηρούνται στην θερμοκρασία της Κοσμικής Ακτινοβολίας Μικροκυμάτων πιστεύεται ότι χαρακτηρίζουν και την κατανομή της πυκνότητας της ύλης του σύμπαντος την στιγμή της «επανασύνδεσης». Υποθέτοντας ότι η ύλη περιγράφεται από ένα Νευτώνειο μη-ιδανικό ρευστό, εξετάζουμε την εξέλιξη γραμμικών διαταραχών στην πυκνότητά του, με στόχο να μελετήσουμε τα αρχικά στάδια της δημιουργίας της δομής του σύμπαντος. Στην περίπτωση μηδενικής πίεσης, καθώς και στις περιπτώσεις μόνο ισοτροπικής ή μόνο ανισοτροπικής πίεσης, το σύστημα των κοσμολογικών εξισώσεων δέχεται αναλυτικές λύσεις Όταν υπάρχει συνδυασμένη δράση ισοτροπικής πίεσης και ιξώδους, οι λύσεις εντοπίζονται μόνο αριθμητικά. Σε όλες τις περιπτώσεις, διαπιστώνεται ότι σε μεγάλα μήκη κύματος ο ρόλος της πίεσης είναι ουσιαστικά αμελητέος. Αντίθετα, σε μικρές κλίμακες, η παρουσία πίεσης εμποδίζει την αύξηση των διαταραχών.
description: The temperature fluctuations observed in the Cosmic Microwave Background Radiation, are believed to characterize the density distribution of matter in the universe at Recombination as well. Assuming that the cosmic medium is a Newtonian non-ideal fluid, we investigate the evolution of linear density perturbations, in order to study the initial steps of structure formation in the universe. In the case of vanishing pressure, as well as in the case of only isotropic or only viscous pressure, the system of the cosmological equations has analytical solutions. On the other hand, when both the isotropic pressure and viscosity are present, the equations can only be solved numerically. Our results show that on large wavelengths, the role of both pressures is insignificant. On the other hand, on small scales, the presence of pressure stresses always prevents the density perturbations from growing.
Probing exciton localization in non-polar GaN/AlN Quantum Dots by single dot optical spectroscopy
Creators: name: Rol, F.
name: Founta, S.
name: Mariette, H.
name: Daudin, B.
name: Dang, Le Si
name: Bleuse, J.
name: Peyrade, D.
name: Gerard, J. -M.
name: Gayral, B.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We present an optical spectroscopy study of non-polar GaN/AlN quantum dots by time-resolved photoluminescence and by microphotoluminescence. Isolated quantum dots exhibit sharp emission lines, with linewidths in the 0.5-2 meV range due to spectral diffusion. Such linewidths are narrow enough to probe the inelastic coupling of acoustic phonons to confined carriers as a function of temperature. This study indicates that the carriers are laterally localized on a scale that is much smaller than the quantum dot size. This conclusion is further confirmed by the analysis of the decay time of the luminescence.
On Sharp Enhancement of Effective Mass of Quasiparticles and Coefficient of T^{2} Term of Resistivity around First-Order Metamagnetic Transition Observed in UTe_{2}
Creators: name: Miyake, Kazumasa
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The mechanism underlying the enhancement of the Sommerfeld coefficient of quasiparticles at the first-order metamagnetic transition in UTe_2, reported by Miyake et al. in J. Phys. Soc. Jpn. 88, 063706 (2019), is discussed theoretically by taking into account the ferromagnetic order-parameter fluctuations on the basis of the Landau theory of phase transition. We find that the enhanced ferromagnetic spin fluctuation gives rise to the enhancement of the effective mass of the quasiparticles or the Sommerfeld coefficient γ,which is consistent with the experimental observations. At the same time, the Kadowaki-Woods type scaling around the metamagnetic transition, reported by Imajo et al.in J. Phys. Soc. Jpn. 88, 083705 (2019) and Knafo et al. in J. Phys. Soc. Jpn. 88, 063705 (2019), is also understood semi-quantitatively by assuming reasonable values of parameters of Landau-type free energy reproducing key quantities characterizing the metamagnetic transition.
description: Accepted for publication in J. Phys. Soc. Jpn
Sonic journeys : a study of students’ conceptualizations of sound and hearing
Creators: name: Webber, George D.
Publisher: name: University of British Columbia
Year: 2009

description: This study was conducted to investigate changes in students' conceptualizations during the teaching of the following topics related to sound: I) the characteristics of sound (frequency, pitch, frequency ranges, and uses of sound); 2) the transmission of sound; and 3) the reception of sound (the ear's anatomy and physiology). The study was conducted in a Science 8 class in a small British Columbia town. The students' conceptualizations were chronicled and categorized to show how they were influenced by classroom instruction and activities. Four students' conceptualizations during the unit were represented as sonic journeys, to show changes or maintenance of previously held ideas. Comparisons were made between the students' conceptualizations of various sound topics at the beginning, middle and end of the teaching. Additionally, comparisons of the four students' conceptualizations were made. Students' conceptualizations were not static. Their ideas were influenced by the teaching and activities comprising the units on sound and hearing. Students developed scientific conceptualizations more readily for topics related to sound which were concrete (related to their immediate experience) than topics which were abstract (requiring non-experiential, theoretical explanations). Students' prior ideas continued to affect their conceptualizations throughout the course of the study. However, students did change their "ideas" as they became aware of their prior ideas and related them to the new concepts presented in the teaching. Thus real learning requires time for these conceptual changes to occur.
Robust Visual Tracking via Statistical Positive Sample Generation and Gradient Aware Learning
Creators: name: Lin, Lijian
name: Chen, Haosheng
name: Liang, Yanjie
name: Yan, Yan
name: Wang, Hanzi
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: In recent years, Convolutional Neural Network (CNN) based trackers have achieved state-of-the-art performance on multiple benchmark datasets. Most of these trackers train a binary classifier to distinguish the target from its background. However, they suffer from two limitations. Firstly, these trackers cannot effectively handle significant appearance variations due to the limited number of positive samples. Secondly, there exists a significant imbalance of gradient contributions between easy and hard samples, where the easy samples usually dominate the computation of gradient. In this paper, we propose a robust tracking method via Statistical Positive sample generation and Gradient Aware learning (SPGA) to address the above two limitations. To enrich the diversity of positive samples, we present an effective and efficient statistical positive sample generation algorithm to generate positive samples in the feature space. Furthermore, to handle the issue of imbalance between easy and hard samples, we propose a gradient sensitive loss to harmonize the gradient contributions between easy and hard samples. Extensive experiments on three challenging benchmark datasets including OTB50, OTB100 and VOT2016 demonstrate that the proposed SPGA performs favorably against several state-of-the-art trackers.
description: 6 pages
Inelastic collisions in an exactly solvable two-mode Bose-Einstein Condensate
Creators: name: Fuentes-Schuller, I.
name: Barberis-Blostein, P.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Inelastic collisions occur in Bose-Einstein condensates, in some cases, producing particle loss in the system. Nevertheless, these processes have not been studied in the case when particles do not escape the trap. We show that such inelastic processes are relevant in quantum properties of the system such as the evolution of the relative population, the self trapping effect and the probability distribution of particles. Moreover, including inelastic terms in the model of the two-mode condensate allows for an exact analytical solution. Using this solution, we show that collisions favor the generation of entanglement between the modes of the condensate as long as the collision rate does not exceed the natural frequency of the system.
Brotate and Tribike: Designing Smartphone Control for Cycling
Creators: name: Woźniak, Paweł W.
name: Dekker, Lex
name: Kiss, Francisco
name: Velner, Ella
name: Kuijt, Andrea
name: Donker, Stella
Publisher: name: arXiv
Year: 2020
Subjects: subject: Human-Computer Interaction (cs.HC)
subject: FOS: Computer and information sciences

description: The more people commute by bicycle, the higher is the number of cyclists using their smartphones while cycling and compromising traffic safety. We have designed, implemented and evaluated two prototypes for smartphone control devices that do not require the cyclists to remove their hands from the handlebars - the three-button device Tribike and the rotation-controlled Brotate. The devices were the result of a user-centred design process where we identified the key features needed for a on-bike smartphone control device. We evaluated the devices in a biking exercise with 19 participants, where users completed a series of common smartphone tasks. The study showed that Brotate allowed for significantly more lateral control of the bicycle and both devices reduced the cognitive load required to use the smartphone. Our work contributes insights into designing interfaces for cycling.
description: 22nd International Conference on Human-Computer Interaction with Mobile Devices and Services (MobileHCI '20), October 5--8, 2020, Oldenburg, Germany
The Search for a Counterpart to NuSTAR J053449+2126.0
Creators: name: Rodriguez, Antonio C.
name: Yao, Yuhan
name: De, Kishalay
name: Kulkarni, S. R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Tumer et al. 2022, ATel #15171, have recently reported the discovery of an X-ray source, NuSTAR J053449+2126.0, during a calibration observation which took place on 25 April 2020. We scan the Zwicky Transient Facility (ZTF) alerts and archival photometry to determine the nature of the source. Palomar Gattini-IR is searched as well. We identify no obvious counterpart candidate. Follow-up X-ray and optical studies are needed to determine the true counterpart.
description: Accepted and Published in RNAAS
Precision of silicon oxynitride refractive-index profile retrieval using optical characterization
Creators: name: Kanclíř, Vít
name: Václavík, Jan
name: Žídek, Karel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optics (physics.optics)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Layers with gradient refractive-index profile are an attractive alternative to conventional homogeneous stack coatings. However, the optical characterization and monitoring of the graded refractive-index profile is a complex issue, which has been typically solved by using a simplified model of mixed materials. Although this approach provides a solution to the problem, the precision, which can be expected from optical characterization of the refractive index gradient, remains unclear. In this work, we study optical characterization of SiO_xN_y layers deposited via reactive dual ion beam sputtering. To characterize the deposited layers, we use several methods including reflectance, and transmittance spectra at a broad range of incident angles, together with spectral ellipsometry. All the data were simultaneously fitted with a general profile of refractive index. The expected profile used in our fit was based on characterization of SiO_xN_y layers with a varying stoichiometry. By altering of the profile, we discussed sensitivity of such alternation on fit quality and we studied ambiguity of merit-function minimization. We demonstrate that while the scanning of particular parameters of the profile can be seemingly very precise, we obtain a very good agreement between the experimental data and model for a broad range of gradient shapes, where the refractive-index value on major part of the profile can differ as much as 0.02 from the mean value.
Is there New Physics in B Decays ?
Creators: name: Datta, Alakabha
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Rare decays of the $B$ meson are sensitive to new physics effects. Several experimental results on these decays have been difficult to understand within the standard model (SM) though more precise measurements and a better understanding of SM theory predictions are needed before any firm conclusions can be drawn. In this talk we try to understand the present data assuming the presence of new physics. We find that the data points to new physics of an extended Higgs sector and we present a two higgs doublet model with a 2-3 flavor symmetry in the down type quark sector that can explain the deviations from standard model reported in several rare B decays.
description: 8 pages, Talk presented at Theory Canada II, Perimeter Institute, Waterloo, Canada. New references added and updated
A Broad Absorption Line Outflow Associated with the Broad Emission Line Region in the Quasar SDSS J075133.35+134548.3
Creators: name: Liu, Bo
name: Zhou, Hongyan
name: Shu, Xinwen
name: Zhang, Shaohua
name: Ji, Tuo
name: Pan, Xiang
name: Jiang, Peng
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We report the discovery of unusual broad absorption lines (BALs) in the bright quasar SDSS J075133.35+134548.3 at z~1, and present a detailed study of BAL and emission lines using the archived and newly obtained optical and NIR spectroscopic data. The BALs are detected tentatively in Mg II, Al III and reliably in HeI*3889, HeI*10830, which show complexed velocity structures splitting into two components: a high-velocity component (HV), with a blueshifted velocity range of -9300 ~ -3500 km/s, can be reliably detected tentatively in Mg II, Al III and reliably in HeI* 10830, whereas it is undetectable in HeI* 3889; and low-Velocity component (LV), with the velocity of -3500 ~ -1800 km/s, is only detected in HeI*3889 and HeI* 10830. With the BALs from different ions, the HV outflowing gas can be constrained to have a density n_H~10^10.3-10^11.4 cm^-3, a column density N_H~10^21 cm^-2 and an ionization parameter U~10^-1.83 - 10^-1.72; and thus inferring a distance of R_HV~0.5 pc from the central continuum source with a monochromatic luminosity of 7.0*10^45 erg/s at 5100 A. This distance is remarkable similar to that of normal broad emission line region (BLR) estimated according to the luminosity-distance from the reverberation experiments, suggesting the association between the BLR and the HV BAL outflowing gas. Interestingly enough, a blueshifted component is also significantly detected in Mg II and Al III broad emission lines (BELs), and the Al III/Mg II of such a BEL component can be reproduced by the physical parameters inferred from the HV BAL gas. The LV BAL gas very likely have a larger column density and a higher ionization level than the HV BAL gas, and hence a smaller distance than that of the latter. Further spectroscopy with high S/N ratio and broader wavelength coverage is needed to confirm this and shed new light on the possible connection between BALs and BELs.
Normal transport properties for a classical particle coupled to a non-Ohmic bath
Creators: name: Lafitte, P.
name: Parris, P. E.
name: De Bievre, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We study the Hamiltonian motion of an ensemble of unconfined classical particles driven by an external field F through a translationally-invariant, thermal array of monochromatic Einstein oscillators. The system does not sustain a stationary state, because the oscillators cannot effectively absorb the energy of high speed particles. We nonetheless show that the system has at all positive temperatures a well-defined low-field mobility over macroscopic time scales of order exp(-c/F). The mobility is independent of F at low fields, and related to the zero-field diffusion constant D through the Einstein relation. The system therefore exhibits normal transport even though the bath obviously has a discrete frequency spectrum (it is simply monochromatic) and is therefore highly non-Ohmic. Such features are usually associated with anomalous transport properties.
A High-Altitude, Station-Keeping Astronomical Platform
Creators: name: Fesen, Robert A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Several commercial telecommunication ventures together with a well funded US military program make it a likely possibility that an autonomous, high-altitude, light-than-air (LTA) vehicle which could maneuver and station-keep for weeks to many months will be a reality in a few years. Here I outline how this technology could be used to develop a high-altitude astronomical observing platform which could return high-resolution optical data rivaling those from space-based platforms but at a fraction of the cost.
description: 11 pages, 10 figures. To appear in Proc. SPIE 6267, "Ground-based and Airborne Telescopes", 2006 May 24-31, Orlando, Florida USA (6267-15)