cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Dynamics of Bright Soliton Under Cubic-Quartic Interactions in Quasi One-Dimensional Geometry
Creators: name: Debnath, Argha
name: Khan, Ayan
name: Panigrahi, Prasanta K
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Recent inspection of liquid-like state in ultracold atomic gases due to the stabilization mechanism through the delicate balance between effective mean-field and beyond mean-field (BMF) interactions, has motivated us to study the modified/extended Gross-Pitaevskii (eGP) equation which includes the BMF contribution. In this article, we focus on variational analysis of solitonic regime with eGP equation while the soliton is subjected to an obstacle. This reveals different scattering scenarios of the soliton with explicit dependence of the BMF interaction. The results show the existence of tunneling, partial and complete trappings, in different parameter domains. These observations are further corroborated by the fast-Fourier transform method. In the later part we also extend our analysis to trapped systems. The controlled trapping in defect potential and its release can be potentially useful for quantum information storage.
description: 11 pages, 27 figures; To be published in European Physical Journal Plus
Kurumsal Sosyal Sorumluluk
Creators: name: SİLSÜPÜR, Özer
Publisher: name: Zenodo
Year: 2023
Subjects: Kurumsal Sosyal Sorumluluk
KSS'nin Kronolojik Süreci
KSS Alanları
Halkla İlişkiler

description: -
Development of Fe$_2$O$_3$/YSZ ceramic plates for cryogenic operation of resistive-protected gaseous detectors
Creators: name: Olano-Vegas, L.
name: Pardo, I.
name: Leardini, S.
name: Morales, M.
name: Carreira, A. R.
name: Corral, R. M.
name: González-Díaz, D.
name: Tesi, A.
name: Moleri, L.
name: Azevedo, C. D. R.
name: Carramate, L.
name: Guitián, F.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: We present a ceramic material based on hematite (Fe$_2$O$_3$) and zirconia stabilized with yttria at 8% molar (YSZ), that exhibits stable electrical properties with transported charge and that can be tuned to the resistivities necessary to induce spark-quenching in gaseous detectors ($ρ= 10^9-10^{12}$ $Ω\cdot$cm), from room temperature down to the liquid-vapor coexistence point of nitrogen (77 K). It, thus, allows covering the operating temperatures of most immediate interest to gaseous instrumentation. The ceramics have been produced in a region of mass concentrations far from what has been usually explored in literature: optimal characteristics are achieved for Fe$_2$O$_3$ concentrations of 75%wt (LAr boiling temperature), 35%wt (LXe boiling temperature), and 100%wt (room temperature). The nine order of magnitude enhancement observed for the electrical conductivity of the mixed phases relative to that of pure Fe$_2$O$_3$ is startling, however it can be qualitatively understood based on existing literature. Plates of 4 cm x 4 cm have been manufactured and, prior to this work, operated in-detector at the LXe boiling point (165 K), demonstrating spark-free operation. Preliminary results obtained for the first time on a spark-protected amplification structure (RP-WELL) at around the LAr boiling point (90 K) are now presented, too.
The role of shear in dissipative gravitational collapse
Creators: name: Govender, M.
name: Reddy, K. P.
name: Maharaj, S. D.
Publisher: name: arXiv
Year: 2013
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In this paper we investigate the physics of a radiating star undergoing dissipative collapse in the form of a radial heat flux. Our treatment clearly demonstrates how the presence of shear affects the collapse process; we are in a position to contrast the physical features of the collapsing sphere in the presence of shear with the shear-free case. By employing a causal heat transport equation of the Maxwell-Cattaneo form we show that the shear leads to an enhancement of the core temperature thus emphasizing that relaxational effects cannot be ignored when the star leaves hydrostatic equilibrium.
description: 15 pages, To appear in Int. J. Mod. Phys. D
Electronic Supplementary Material FINAL_1R.docx
Creators: name: Sosa-Pivatto, María
name: Cosacov, Andrea
name: Sérsic, Alicia N.
Publisher: name: figshare
Year: 2025
Subjects: classificationCode: 310405
subject: Evolutionary ecology
classificationCode: 310406
subject: Evolutionary impacts of climate change

description: Glacial refugia are habitats where species can persist during climate changes and they are of high conservation value due to their role as hotspots of genetic diversity. Therefore, it is relevant to understand factors that determine the distribution of these refugia across species’ ranges and of their mutualists. According to the Central Peripheral Hypothesis, as genetic diversity is highest in the geographic range centre of the species' distribution, it is expected that refugia coincide with this centre, if the geographic and environmental centroids are coupled. We proposed an integrative framework that combines genetic diversity, current and past distribution range, and historical ecological niche to investigate the association between Pleistocene refugia and geographic and environmental centrality in a plant-pollinator mutualism from Patagonia. We identified a clear pattern in which genetic diversity was negatively associated with distance to environmental centroids and positively with distance to geographic centres of Centris cineraria, Calceolaria polyrhiza and their mutualistic interaction. Our results show that glacial refugia can be geographically peripheral but ecologically central and that highly specialized mutualism would share the same refugia. Focusing on spatio-temporal dynamics of environmental rather than geographic centroids can contribute to better understanding aspects related to the conservation and evolution of species’ populations.
Tracking the Complex Absorption in NGC 2110 with Two Suzaku Observations
Creators: name: Rivers, Elizabeth
name: Markowitz, Alex
name: Rothschild, Richard
name: Bamba, Aya
name: Fukazawa, Yasushi
name: Okajima, Takashi
name: Reeves, James
name: Terashima, Yuichi
name: Ueda, Yoshihiro
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We present spectral analysis of two Suzaku observations of the Seyfert 2 galaxy, NGC 2110. This source has been known to show complex, variable absorption which we study in depth by analyzing these two observations set seven years apart and by comparing to previously analyzed observations with the XMM-Newton and Chandra observatories. We find that there is a relatively stable, full-covering absorber with a column density of ~3$\times 10 ^{22}$ cm$^{-2}$, with an additional patchy absorber that is likely variable in both column density and covering fraction over timescales of years, consistent with clouds in a patchy torus or in the broad line region. We model a soft emission line complex, likely arising from ionized plasma and consistent with previous studies. We find no evidence for reflection from an accretion disk in this source with no contribution from relativistically broadened Fe Ka line emission nor from a Compton reflection hump.
description: Accepted to ApJ: March, 2014
AMS-02 and Next-to-Minimal Universal Extra Dimensions
Creators: name: Gao, Yu
name: Kong, Kyoungchul
name: Marfatia, Danny
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The anomaly detected by AMS-02 and PAMELA in the cosmic-ray positron flux when interpreted as arising from dark matter annihilation suggests that dark matter may interact differently with hadrons and leptons so as to remain compatible with cosmic-ray antiproton data. Such a scenario is readily accommodated in models with extra spatial dimensions. We study indirect detection of Kaluza-Klein (KK) dark matter in Universal Extra Dimensions with brane-localized terms and fermion bulk masses: Next-to-Minimal Universal Extra Dimensions. So that an excess of antiprotons is not produced in explaining the positron anomaly, it is necessary that the KK bulk masses in the lepton and hadron sectors be distinct. Even so, we find that cosmic-ray data disfavor a heavy KK photon dark matter scenario. Also, we find these scenarios with flavor-universal bulk masses to be in conflict with dijet and dilepton searches at the LHC.
description: 5 pages, 3 figures
Model trees with topic model preprocessing: An approach for data journalism illustrated with the WikiLeaks Afghanistan war logs
Creators: name: Rusch, Thomas
name: Hofmarcher, Paul
name: Hatzinger, Reinhold
name: Hornik, Kurt
Publisher: name: arXiv
Year: 2013
Subjects: subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: The WikiLeaks Afghanistan war logs contain nearly $77,000$ reports of incidents in the US-led Afghanistan war, covering the period from January 2004 to December 2009. The recent growth of data on complex social systems and the potential to derive stories from them has shifted the focus of journalistic and scientific attention increasingly toward data-driven journalism and computational social science. In this paper we advocate the usage of modern statistical methods for problems of data journalism and beyond, which may help journalistic and scientific work and lead to additional insight. Using the WikiLeaks Afghanistan war logs for illustration, we present an approach that builds intelligible statistical models for interpretable segments in the data, in this case to explore the fatality rates associated with different circumstances in the Afghanistan war. Our approach combines preprocessing by Latent Dirichlet Allocation (LDA) with model trees. LDA is used to process the natural language information contained in each report summary by estimating latent topics and assigning each report to one of them. Together with other variables these topic assignments serve as splitting variables for finding segments in the data to which local statistical models for the reported number of fatalities are fitted. Segmentation and fitting is carried out with recursive partitioning of negative binomial distributions. We identify segments with different fatality rates that correspond to a small number of topics and other variables as well as their interactions. Furthermore, we carve out the similarities between segments and connect them to stories that have been covered in the media. This gives an unprecedented description of the war in Afghanistan and serves as an example of how data journalism, computational social science and other areas with interest in database data can benefit from modern statistical techniques.
description: Published in at http://dx.doi.org/10.1214/12-AOAS618 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Phase diagram of the frustrated quantum-XY model on the honeycomb lattice studied by series expansions: Evidence for proximity to a bicritical point
Creators: name: Oitmaa, Jaan
name: Singh, Rajiv R. P.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study the nearest-neighbor exchange ($J_1$) and second-neighbor exchange ($J_2$) XY antiferromagnet on the honeycomb lattice using ground state series expansions around N{é}el, columnar and dimer phases. The conventional two-sublattice XY N{é}el order at small $J_2$ vanishes at $J_2/J_1=0.22\pm 0.01$ in agreement with results from Density Matrix Renormalization Group (DMRG) studies. Near the transition, we find evidence for an {\it approximate} emergent symmetry between XY and Ising degrees of freedom, namely the nearest-neighbor Ising and XY spin correlations become nearly equal. This suggests that the system is close to a bicritical point separating XY and Ising orders. At still larger $J_2/J_1$ the columnar and dimer energies are found to be nearly degenerate. At even larger $J_2$ the columnar phase is obtained. The ground state energies in all three phases are in good agreement with the values found in the DMRG studies.
description: 5 pages, 5 figures
Die Bedeutung der Eröffnungsphasen für die Bearbeitung von substantiellen Lernumgebungen
Creators: name: Wagner, Elisa
name: Wendt, Maria
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Heterogenität
subject: Natürliche Differenzierung
subject: Strukturierte Päckchen
subject: Adressierung
subject: Eröffnungsphasen
subject: Grundschule
subject: Arithmetik
subject: Heterogenität & Inklusion im MU
subject: 510

description: Heterogene Lernvoraussetzungen von Schüler*innen stellen eine große Herausforderung für Grundschullehrkräfte dar. Konzepte der inneren Differenzierung versuchen diesen durch vorrangig unterrichtsorganisatorische Anpassungen (sozial, methodisch, quantitativ) gerecht zu werden (Krauthausen & Scherer, 2010, S. 4). Dem gegenüber steht das Konzept der natürlichen Differenzierung, welche die Grundlage für substantielle Lernumgebungen (SLU) ist. Mithilfe mathematisch gehaltvoller Aufgaben soll damit ein ganzheitlicher Zugang zu mathematischen Problemstellungen ermöglicht werden, der verschiedene Zugänge und mathematische Beschreibungen ermöglicht. Hirt und Wälti (2016) entwickelten mit der Lernumgebung der „Strukturierten Päckchen“ eine SLU, die auf innewohnende Muster und Strukturen der Mathematik aufbaut und dadurch eine vom Fach ausgehende Differenzierungsmöglichkeit bietet (Hirt & Wälti, 2016, S. 14-16, 54).
A Mini Review on the utilization of Reinforcement Learning with OPC UA
Creators: name: Schindler, Simon
name: Uray, Martin
name: Huber, Stefan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Reinforcement Learning (RL) is a powerful machine learning paradigm that has been applied in various fields such as robotics, natural language processing and game playing achieving state-of-the-art results. Targeted to solve sequential decision making problems, it is by design able to learn from experience and therefore adapt to changing dynamic environments. These capabilities make it a prime candidate for controlling and optimizing complex processes in industry. The key to fully exploiting this potential is the seamless integration of RL into existing industrial systems. The industrial communication standard Open Platform Communications UnifiedArchitecture (OPC UA) could bridge this gap. However, since RL and OPC UA are from different fields,there is a need for researchers to bridge the gap between the two technologies. This work serves to bridge this gap by providing a brief technical overview of both technologies and carrying out a semi-exhaustive literature review to gain insights on how RL and OPC UA are applied in combination. With this survey, three main research topics have been identified, following the intersection of RL with OPC UA. The results of the literature review show that RL is a promising technology for the control and optimization of industrial processes, but does not yet have the necessary standardized interfaces to be deployed in real-world scenarios with reasonably low effort.
description: preprint of Paper submitted to INDIN'23
The orbital minimization method for electronic structure calculations with finite-range atomic basis sets
Creators: name: Corsetti, Fabiano
Publisher: name: arXiv
Year: 2013
Subjects: subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The implementation of the orbital minimization method (OMM) for solving the self-consistent Kohn-Sham (KS) problem for electronic structure calculations in a basis of non-orthogonal numerical atomic orbitals of finite-range is reported. We explore the possibilities for using the OMM as an exact cubic-scaling solver for the KS problem, and compare its performance with that of explicit diagonalization in realistic systems. We analyze the efficiency of the method depending on the choice of line search algorithm and on two free parameters, the scale of the kinetic energy preconditioning and the eigenspectrum shift. The results of several timing tests are then discussed, showing that the OMM can achieve a noticeable speedup with respect to diagonalization even for minimal basis sets for which the number of occupied eigenstates represents a significant fraction of the total basis size (>15%). We investigate the hard and soft parallel scaling of the method on multiple cores, finding a performance equal to or better than diagonalization depending on the details of the OMM implementation. Finally, we discuss the possibility of making use of the natural sparsity of the operator matrices for this type of basis, leading to a method that scales linearly with basis size.
description: 23 pages, 10 figures. Comput. Phys. Commun., in publication (2013)
Quick Detection of Contaminants Leaching from Polypropylene Centrifuge Tube with Surface Enhanced Raman Spectroscopy and Ultra Violet Absorption Spectroscopy
Creators: name: Xu, Zhida
name: Liu, Logan
Publisher: name: arXiv
Year: 2014
Subjects: subject: Quantitative Methods (q-bio.QM)
subject: Chemical Physics (physics.chem-ph)
subject: Biomolecules (q-bio.BM)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Anomalous surface enhanced Raman scattering (SERS) peaks are identified for liquid sample stored in polypropylene centrifuge tubes (PP tube) for months. We observed the unexpected Raman peaks during experiments for Thiamine Hydrochloride aqueous solution stored in PP tube for two months. In order to identify the contaminants we have performed SERS experiments for de-ionized water (DI water) stored in polypropylene centrifuge tube for two months and compared them with fresh DI water sample. We have also carried out Ultra Violet (UV) absorption spectra for both fresh and contaminated water. We believe that the water is contaminated because of chemicals leaching from the PP tube. From the GC-MS data the main contaminant was found to be Phthalic acid and its derivatives. Further SERS and UV absorption experiment for Phthalic acid correlates well with the anomalous peaks identified earlier. We qualitatively confirmed the identification and quantitatively estimated the concentration of suspect contaminants as between 1uM and 10uM with both SERS and UV absorption spectroscopy. With UV absorption spectroscopy, we precisely estimate the concentration as 2.1uM. We have shown that sample in PP tube can be contaminated due to leaching chemicals upon long term storage and suggested SERS and UV-absorption spectroscopy as two quick and simple techniques to detect the contamination
Detailed Abundances of Planet-Hosting Wide Binaries. I. Did Planet Formation Imprint Chemical Signatures in the Atmospheres of HD 20782/81?
Creators: name: Mack, Claude E.
name: Schuler, Simon C.
name: Stassun, Keivan G.
name: Pepper, Joshua
name: Norris, John
Publisher: name: arXiv
Year: 2014
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Using high-resolution echelle spectra obtained with Magellan/MIKE, we present a chemical abundance analysis of both stars in the planet-hosting wide binary system HD20782 + HD20781. Both stars are G dwarfs, and presumably coeval, forming in the same molecular cloud. Therefore we expect that they should possess the same bulk metallicities. Furthermore, both stars also host giant planets on eccentric orbits with pericenters $\lesssim 0.2\,$ AU. We investigate if planets with such orbits could lead to the host stars ingesting material, which in turn may leave similar chemical imprints in their atmospheric abundances. We derived abundances of 15 elements spanning a range of condensation temperatures ($T_{C}\approx 40-1660\,$ K). The two stars are found to have a mean element-to-element abundance difference of $0.04\pm0.07\,$ dex, which is consistent with both stars having identical bulk metallicities. In addition, for both stars, the refractory elements ($T_{C} > 900\,$ K) exhibit a positive correlation between abundance (relative to solar) and $T_{C}$, with similar slopes of $\approx$ $1\times10^{-4}\,$ dex K$^{-1}$. The measured positive correlations are not perfect; both stars exhibit a scatter of $\approx$ $5\times10^{-5}\,$ dex K$^{-1}$ about the mean trend, and certain elements (Na, Al, Sc) are similarly deviant in both stars. These findings are discussed in the context of models for giant planet migration that predict the accretion of H-depleted rocky material by the host star. We show that a simple simulation of a solar-type star accreting material with Earth-like composition predicts a positive---but imperfect---correlation between refractory elemental abundances and $T_{C}$. Our measured slopes for HD 20782/81 are consistent with what is predicted for the ingestion of 10--20 Earths by both stars.
description: 8 pages, 6 figures, 2 tables, accepted for publication in The Astrophysical Journal
Zwei intuitive Vorstellungen zur Wahrscheinlichkeit bei Lehramtsstudierenden
Creators: name: Treiber, Eva
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Equiprobability Bias
subject: Falk-Paradoxon
subject: Lehramtsstudierende
subject: Wahrscheinlichkeit
subject: Hochschule
subject: Stochastik
subject: Sonstiges
subject: 510

description: Gemäß dem bayerischen LehrplanPLUS soll schon in der Grundschule „ein Verständnis für den Wahrscheinlichkeitsbegriff angebahnt“ werden (Bayerisches Staatsministerium für Bildung und Kultus, Wissenschaft und Kunst, 2014, S. 109). Bereits bei recht einfach zu verstehenden Aufgabenstellungen zur Wahrscheinlichkeit werden jedoch auch von älteren Schüler*innen oder Erwachsenen noch Antworten gegeben, die mathematisch nicht korrekt sind, sondern auf Intuitionen, mentalen Vorstellungen oder Ansätzen beruhen, die im jeweiligen Kontext mathematisch nicht tragfähig sind (z. B. Falk, 1979; Fishbein, 1997; Lecoutre, 1992; Rolfes & Fahse, 2019). Im Folgenden werden diese als intuitive Vorstellungen bezeichnet.
Perturbation-based Self-supervised Attention for Attention Bias in Text Classification
Creators: name: Feng, Huawen
name: Lin, Zhenxi
name: Ma, Qianli
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: In text classification, the traditional attention mechanisms usually focus too much on frequent words, and need extensive labeled data in order to learn. This paper proposes a perturbation-based self-supervised attention approach to guide attention learning without any annotation overhead. Specifically, we add as much noise as possible to all the words in the sentence without changing their semantics and predictions. We hypothesize that words that tolerate more noise are less significant, and we can use this information to refine the attention distribution. Experimental results on three text classification tasks show that our approach can significantly improve the performance of current attention-based models, and is more effective than existing self-supervised methods. We also provide a visualization analysis to verify the effectiveness of our approach.
Properties of Bigravity Solutions in a Solvable Class
Creators: name: Katsuragawa, Taishi
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We consider the properties of solutions in the bigravity theory for general models, which are parametrized by two parameters $α_{3}$ and $α_{4}$. Assuming that two metric tensors $g_{μν}$ and $f_{μν}$ satisfy the condition $f_{μν}=C^{2}g_{μν}$ where $C$ is a constant, we investigate the conditions for the parameters so that the solutions with $C\neq1$ could exist. We also discuss the magnitude and the sign of corresponding cosmological constants. For the black hole solution, we consider the black hole entropy to which the massive spin-$2$ field contributes. In order to obtain the black hole entropy, we take an approach which uses the Virasoro algebra and the central charge corresponding to the surface term in the action.
description: 12 pages, 7 figures
title: Investigation of the functional pathogenesis of mild cognitive impairment by localisation-based locus coeruleus resting-state fMRI
Creators: name: Liebe, Thomas
name: Dordevic, Milos
name: Kaufmann, Jörn
name: Avetisyan, Araks
name: Skalej, Martin
name: Müller, Notger Germar
Publisher: name: Universitätsverlag Potsdam
Year: 2023
Subjects: subject: 610 Medizin und Gesundheit

description: Dementia as one of the most prevalent diseases urges for a better understanding of the central mechanisms responsible for clinical symptoms, and necessitates improvement of actual diagnostic capabilities. The brainstem nucleus locus coeruleus (LC) is a promising target for early diagnosis because of its early structural alterations and its relationship to the functional disturbances in the patients. In this study, we applied our improved method of localisation-based LC resting-state fMRI to investigate the differences in central sensory signal processing when comparing functional connectivity (fc) of a patient group with mild cognitive impairment (MCI, n = 28) and an age-matched healthy control group (n = 29). MCI and control participants could be differentiated in their Mini-Mental-State-Examination (MMSE) scores (p < .001) and LC intensity ratio (p = .010). In the fMRI, LC fc to anterior cingulate cortex (FDR p < .001) and left anterior insula (FDR p = .012) was elevated, and LC fc to right temporoparietal junction (rTPJ, FDR p = .012) and posterior cingulate cortex (PCC, FDR p = .021) was decreased in the patient group. Importantly, LC to rTPJ connectivity was also positively correlated to MMSE scores in MCI patients (p = .017). Furthermore, we found a hyperactivation of the left-insula salience network in the MCI patients. Our results and our proposed disease model shed new light on the functional pathogenesis of MCI by directing to attentional network disturbances, which could aid new therapeutic strategies and provide a marker for diagnosis and prediction of disease progression.
description: Zweitveröffentlichungen der Universität Potsdam : Gesundheitswissenschaftliche Reihe; 7
Multiplicity in Early Stellar Evolution
Creators: name: Reipurth, Bo
name: Clarke, Cathie J.
name: Boss, Alan P.
name: Goodwin, Simon P.
name: Rodriguez, Luis Felipe
name: Stassun, Keivan G.
name: Tokovinin, Andrei
name: Zinnecker, Hans
Publisher: name: arXiv
Year: 2014
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Observations from optical to centimeter wavelengths have demonstrated that multiple systems of two or more bodies is the norm at all stellar evolutionary stages. Multiple systems are widely agreed to result from the collapse and fragmentation of cloud cores, despite the inhibiting influence of magnetic fields. Surveys of Class 0 protostars with mm interferometers have revealed a very high multiplicity frequency of about 2/3, even though there are observational difficulties in resolving close protobinaries, thus supporting the possibility that all stars could be born in multiple systems. Near-infrared adaptive optics observations of Class I protostars show a lower binary frequency relative to the Class 0 phase, a declining trend that continues through the Class II/III stages to the field population. This loss of companions is a natural consequence of dynamical interplay in small multiple systems, leading to ejection of members. We discuss observational consequences of this dynamical evolution, and its influence on circumstellar disks, and we review the evolution of circumbinary disks and their role in defining binary mass ratios. Special attention is paid to eclipsing PMS binaries, which allow for observational tests of evolutionary models of early stellar evolution. Many stars are born in clusters and small groups, and we discuss how interactions in dense stellar environments can significantly alter the distribution of binary separations through dissolution of wider binaries. The binaries and multiples we find in the field are the survivors of these internal and external destructive processes, and we provide a detailed overview of the multiplicity statistics of the field, which form a boundary condition for all models of binary evolution. Finally we discuss various formation mechanisms for massive binaries, and the properties of massive trapezia.
description: Accepted for publication as a chapter in Protostars and Planets VI, University of Arizona Press (2014), eds. H. Beuther, R. Klessen, C. Dullemond, Th. Henning
Vorhandene und fehlende Metakognition in Aufgabenbearbeitungen
Creators: name: Sjuts, Johann
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Metakognition
subject: Aufgaben
subject: Verschriftlichung des Denkens
subject: Sek 1
subject: Arithmetik
subject: Argumentieren & Beweisen
subject: 510

description: Metakognition ist bei der Bearbeitung von Aufgaben in Mathematik von Nutzen, und zwar einerseits zur Absicherung von Lösungen und andererseits zur Vorbeugung von Fehlern. Metakognition ist nicht nur erfolgsunterstützend, sondern auch misserfolgsvermindernd. Im Rahmen diesbezüglicher Analysen von Aufgabenstellungen und -lösungen ist ein kategoriales Instrumentarium entstanden, mit dem sich metakognitive Prozesse in Aufgabenbearbeitungen rekonstruieren lassen. Die so gewonnenen Erkenntnisse bieten Anregungen sowohl für die Forschung in Mathematikdidaktik als auch für die Organisation von Lehr-Lern-Prozessen in Mathematik.
Accelerating Value Iteration with Anchoring
Creators: name: Lee, Jongmin
name: Ryu, Ernest K.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Machine Learning (cs.LG)
subject: Optimization and Control (math.OC)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: Value Iteration (VI) is foundational to the theory and practice of modern reinforcement learning, and it is known to converge at a $\mathcal{O}(γ^k)$-rate, where $γ$ is the discount factor. Surprisingly, however, the optimal rate for the VI setup was not known, and finding a general acceleration mechanism has been an open problem. In this paper, we present the first accelerated VI for both the Bellman consistency and optimality operators. Our method, called Anc-VI, is based on an \emph{anchoring} mechanism (distinct from Nesterov's acceleration), and it reduces the Bellman error faster than standard VI. In particular, Anc-VI exhibits a $\mathcal{O}(1/k)$-rate for $γ\approx 1$ or even $γ=1$, while standard VI has rate $\mathcal{O}(1)$ for $γ\ge 1-1/k$, where $k$ is the iteration count. We also provide a complexity lower bound matching the upper bound up to a constant factor of $4$, thereby establishing optimality of the accelerated rate of Anc-VI. Finally, we show that the anchoring mechanism provides the same benefit in the approximate VI and Gauss--Seidel VI setups as well.
Improvements of Track Fitting with Well Tuned Probability Distributions for Silicon Strip Detectors
Creators: name: Landi, Gregorio
name: Landi, Giovanni E.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: The construction of a well tuned probability distributions is illustrated in synthetic way, these probability distributions produce faithful realizations of the impact point distributions for particles in silicon strip detector. Their use for track fitting shows a drastic improvements of a factor two, for the low noise case, and a factor three, for the high noise case, respect to the standard approach. The tracks are well reconstructed even in presence of hits with large errors, with a surprising effect of hit discarding. The applications illustrated are simulations of the PAMELA tracker, but other type of trackers can be handled similarly. The probability distributions are calculated for the center of gravity algorithms, and they are very different from gaussian probabilities. These differences are crucial to accurately reconstruct tracks with high error hits and to produce the effective discarding of the too noisy hits (outliers). The similarity of our distributions with the Cauchy distribution forced us to abandon the standard deviation for our comparisons and instead use the full width at half maximum. A set of mathematical approaches must be developed for these applications, some of them are standard in wide sense, even if very complex. One is essential and, in its absence, all the others are useless. Therefore, in this paper, we report the details of this critical approach. It extracts physical properties of the detectors, and allows the insertion of the functional dependence from the impact point in the probability distributions. Other papers will be dedicated to the remaining parts.
description: 30 pages, 19 figures with captions
Zur Beweisakzeptanz von Lehramtsstudierenden im schulmathematischen Kontext
Creators: name: Szücs, Kinga
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Beweisakzeptanz
subject: Lehramtsstudierende
subject: Beurteilung von Schülerlösungen
subject: Sek 1
subject: Geometrie
subject: Argumentieren & Beweisen
subject: 510

description: Obwohl Beweisen in der Fachwissenschaft Mathematik ein hoher Stellenwert beigemessen wird, werden Beweise in der Schule aktuell kaum thematisiert (Brunner, 2014). Um dieser Diskrepanz langfristig entgegenzuwirken, braucht es Lehrkräfte, die selbst über ausreichendes fachliches und fachdidaktisches Wissen und Können mit Bezug zu Beweisen verfügen. In diesem Sinne wird in der vorliegenden Arbeit bei Lehramtsstudierenden gegen Ende ihrer Ausbildung untersucht, über welches schulrelevante Wissen sie mit Bezug zu Beweisen verfügen.
Large Eddy Simulation of Turbulent Barotropic Flows in Spectral Space on the Sphere
Creators: name: Azadani, Leila N.
name: Staples, Anne E.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Numerical simulations of atmospheric circulation models are limited by their finite spatial resolution, and so large eddy simulation (LES) is the preferred approach to study these models. In LES a low-pass filter is applied to the flow field to separate the large and small scale motions. In implicitly filtered LES the computational mesh and discretization schemes are considered to be the low-pass filter while in the explicitly filtered LES approach the filtering procedure is separated from the grid and discretization operators and allows for better control of the numerical errors. The aim of this paper is to study and compare implicitly filtered and explicitly filtered LES of atmospheric circulation models in spectral space. To achieve this goal we present the results of implicitly filtered and explicitly filtered LES of a barotropic atmosphere circulation model on the sphere in spectral space and compare them with the results obtained from direct numerical simulation (DNS). Our study shows that although in the computation of some integral quantities like total kinetic energy and total enstrophy the results obtained from implicitly filtered LES and explicitly filtered LES show the same good agreement with the DNS results, explicit filtering produces energy spectra that show better agreement with the DNS results. More importantly, explicit filtering captures the location of coherent structures over time while implicit filtering does not.
description: arXiv admin note: substantial text overlap with arXiv:1404.1423
Un_Fähigkeitszuschreibungen von Schüler*innen im inklusiven Mathematikunterricht
Creators: name: Viermann, Mia
name: Ehrenberg, Katrin
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Grundschule
subject: interdisziplinär
subject: Heterogenität & Inklusion im MU
subject: 510

description: In der erziehungswissenschaftlichen Schul- und Unterrichtsforschung entwickelt sich der Differenzbegriff zunehmend zu einer bedeutenden Analysefigur inklusiven Unterrichts, da er es ermöglicht, Praktiken von Zuschreibung und Nicht-Zuschreibung sozialer Nicht_Zugehörigkeiten im Unterricht offenzulegen (Imholz & Lindmeier, 2018). Entsprechendes Potenzial bietet der Differenzbegriff auch für die Analyse und Reflexion inklusiven Mathematikunterrichts, der sowohl behinderungsbezogene Heterogenitätsaspekte als auch darüberhinausgehende „Diversitätsaspekte wie z. B. Lernstände, Zugangsweisen, Geschlecht, Migrationshintergrund, Alter, [und] Sprachkompetenzen“ berücksichtigt (Gemeinsame Kommission Lehrerbildung der GDM, DMV und MNU, 2017, S. 42). Merl (2019) rekonstruiert in seiner Studie zur Herstellung von Differenz im Unterricht inklusiver Schulklassen zudem die Bedeutung von Un_Fähigkeitszuschreibungen für das Nicht_Gelingen inklusiven Unterrichts, da in Bildungskontexten Un_Fähigkeitskonstruktionen beurteilende Zuschreibungen von Bildungsfähigkeit hervorrufen (Tenorth, 2013). „Diejenigen Bildungsteilnehmer _innen, die die Normalitätserwartungen nicht voraussetzungslos erfüllen, werden damit nicht nur als Andere, sondern auch als defizitäre Andere hervorgebracht und als solche in ausgrenzender Weise ins Bildungssystem einbezogen. Der konzeptionelle Ausdruck einer solchen Einstellung findet sich z. B. in spezifischen Förderangeboten, die als einseitige, zielgruppenspezifische und kompensatorische ,Sonderveranstaltungen' ausgerichtet werden“ (Arens et al., 2013, S. 13). Deutlich wird hier auch, dass Differenzkonstruktionen mit Hegemoniepraktiken und Statuszuschreibungen einhergehen (Becker-Schmidt, 2007). Das Benennen von der Norm abweichender „Anderer“ sichert die eigene Normalität und führt zu einer Sicherung bzw. Aufwertung der eigenen sozialen Position (Riegel, 2016, S. 57). Die verschiedenen schulischen Akteur* innen sind dabei in der Unterrichtspraxis zugleich (Re-)produzierende sozialer Zuschreibungen als auch Adressat*innen dieser (Lindmeier, 2019).
On the determination of the spin and disc truncation of accreting black holes using X-ray reflection
Creators: name: Fabian, A. C.
name: Parker, M. L.
name: Wilkins, D. R.
name: Miller, J. M.
name: Kara, E.
name: Reynolds, C. S.
name: Dauser, T.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We discuss the application of simple relativistically-blurred X-ray reflection models to the determination of the spin and the inner radius of the disc in accreting black holes. Observationally, the nature of the corona is uncertain a priori, but a robust determination of the inner disk radius can be made when the disc emissivity index is tightly constrained. When the inner disc is well illuminated, the black hole spin can also be determined. Using reflection modelling derived from ray tracing, we show that robust determination of disc truncation requires that the location of the coronal source is quasi-static and at a height and radius less than the truncation radius of the disc. Robust spin measurements require that at least part of the corona lies less than about 10 gravitational radii above the black hole in order that the innermost regions, including the innermost stable circular orbit, are well illuminated. The width of the blurring kernel (e.g., the iron line) has a strong dependence on coronal height. These limitations may be particularly applicable at low Eddington fractions (e.g. the low/hard state, and low-luminosity AGN) where the height of the corona may be relatively large, or outflowing, and tied to jet production.
description: 7 pages, 5 figures, MNRAS in press
Individuelle Zugänge zum Darstellen von Daten in der Primarstufe
Creators: name: Spree, Theresa
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Daten
subject: Repräsentationen
subject: Grundschule
subject: Stochastik
subject: Darstellen
subject: 510

description: Im Alltag, aber auch in vielen Unterrichtsfächern, lässt sich die hohe Relevanz von Daten und zugehörigen grafischen Darstellungen erkennen. Im Mathematikunterricht der Primarstufe sollen grundlegende Kenntnisse zum Bereich „Daten und Häufigkeit“ vermittelt werden, zu denen neben dem Sammeln und Strukturieren auch das Darstellen von Daten in Tabellen oder Diagrammen gehört (KMK, 2004). Das Erkenntnisinteresse der vorliegenden Untersuchung richtet sich auf die Rekonstruktion von Aktivitäten von Schüler*innen im Umgang mit gegebenen Daten. Der Schwerpunkt dieses Beitrages liegt auf der individuellen Konstruktion von Datendarstellungen in Form von Eigenproduktionen durch Lernende der Primarstufe.
Exciton-Sensitized Second-Harmonic Generation in 2D Heterostructures
Creators: name: Kim, Wontaek
name: Jeong, Gyouil
name: Oh, Juseung
name: Kim, Jihun
name: Watanabe, Kenji
name: Taniguchi, Takashi
name: Ryu, Sunmin
Publisher: name: arXiv
Year: 2023
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The efficient optical second-harmonic generation (SHG) of two-dimensional (2D) crystals, coupled with their atomic thickness that circumvents the phase-match problem, has garnered considerable attention. While various 2D heterostructures have shown promising applications in photodetectors, switching electronics, and photovoltaics, the modulation of nonlinear optical properties in such hetero-systems remains unexplored. In this study, we investigate exciton sensitized SHG in heterobilayers of transition metal dichalcogenides (TMDs), where photoexcitation of one donor layer enhances the SHG response of the other as an acceptor. We utilize polarization-resolved interferometry to detect the SHG intensity and phase of each individual layer, revealing the energetic match between the excitonic resonances of donors and the SHG enhancement of acceptors for four TMD combinations. Our results also uncover the dynamic nature of interlayer coupling, as evidenced by the dependence of sensitization on interlayer gap spacing and the average power of the fundamental beam. This work provides insights into how interlayer coupling of two different layers can modify nonlinear optical phenomena in 2D heterostructures.
description: 24 pages, 5 figures
Magnetic anisotropy and chirality of frustrated Cr nanostructures on Au(111)
Creators: name: Balogh, László
name: Udvardi, László
name: Szunyogh, László
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: By using a fully relativistic embedded cluster Green's function technique we investigated the magnetic anisotropy properties of four different compact Cr trimers (equilateral triangles) and Cr mono-layers deposited on Au(111) surface in both fcc and hcp stackings. For all trimers the magnetic ground state was found a frustrated 120$^\circ$ Néel configuration. Applying global spin rotations to the magnetic ground state, the predictions of an appropriate second order spin Hamiltonian were reproduced with high accuracy by the first principles calculations. For the Cr trimers with adjacent Au atoms in similar geometry we obtained similar values for the in-plane and out-of-plane anisotropy parameters, however, the Dzyaloshinskii-Moriya (DM) interactions appeared to differ remarkably. For two kinds of trimers we found an unconventional magnetic ground state showing 90$^\circ$ in-the-plane rotation with respect to the high symmetry directions. Due to higher symmetry, the in-plane anisotropy term was missing for the mono-layers and distinctly different DM interactions were obtained for the different stackings. The chiral degeneracy of the Néel configurations was lifted by less then 2 meV for the trimers, while this value raised up to about 15 meV per 3 Cr atoms for the hcp packed mono-layer.
description: 4 figures, 1 table
Anwendungsorientierter Unterricht als Prädiktor für das Interesse am Fach Mathematik?
Creators: name: Spreitzer, Carina
name: Müller, Florian H.
name: Krainer, Konrad
Publisher: name: Gesellschaft für Didaktik der Mathematik
Year: 2023
Subjects: subject: Anwendungsorientierter Unterricht
subject: Motivation
subject: Interesse am Fach
subject: Strukturgleichungsanalyse
subject: Sek 1
subject: interdisziplinär
subject: sonstiges
subject: 510

description: Das Ergebnis eines erfolgreichen, qualitätsvollen Unterrichts kann die fachliche Kompetenz (Weinert et al., 1989) oder die Motivation der Schüler*innen sein (Krapp, 1999). Auch im Mathematikunterricht geht es nicht nur um eine Steigerung der fachlichen Kompetenz der Schüler*innen, sondern auch um eine Steigerung des motivationalen und emotionalen Outputs wie zum Beispiel des Interesses am Fach (Kunter, 2005).
Dynamical symmetries in the non-equilibrium dynamics of the directed spherical model
Creators: name: Henkel, Malte
name: Stoimenov, Stoimen
Publisher: name: arXiv
Year: 2023
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The dynamical scaling and ageing in the relaxational dynamics of the quenched directed spherical model is analysed. The exact two-time correlation and response functions display new regimes of ballistic or anisotropic ballistic scaling, at larger distances than probed in the usual regime of diffusive scaling. The rôle of long-ranged initial correlations on the existence of these scaling regimes is clarified. Their dynamical symmetries are described in terms of extensions of the Schrödinger algebra appropriate to non-equilibrium dynamics in that the anisotropic ballistic scaling regime can be interpreted in terms of meta-Schrödinger invariance while the regime of isotropic ballistic scaling is meta-conformally invariant.
description: 29 pages, 2 figures
Smooth Gevrey normal forms of vector fields near a fixed point
Creators: name: Stolovitch, Laurent
Publisher: name: arXiv
Year: 2014
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: We study germs of smooth vector fields in a neighborhood of a fixed point having an hyperbolic linear part at this point. It is well known that the "small divisors" are invisible either for the smooth linearization or normal form problem. We prove that this is completely different in the smooth Gevrey category. We prove that a germ of smooth $\al$-Gevrey vector field with an hyperbolic linear part admits a smooth $\be$-Gevrey transformation to a smooth $\be$-Gevrey normal form. The Gevrey order $\be$ depends on the rate of accumulation to $0$ of the small divisors. We show that a formally linearizable Gevrey smooth germ with the linear part satisfies Brjuno's small divisors condition can be linearized in the same Gevrey class.