cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The cosmological evolution of ultralight axionlike scalar fields
Creators: name: Norton, Cameron E.
name: Scherrer, Robert J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We examine the cosmological evolution of ultralight axionlike (ULA) scalar fields with potentials of the form $V(ϕ) = m^2 f^2[1 - \cos(ϕ/f)]^n$, with particular emphasis on the deviation in their behavior from the corresponding small$-ϕ$ power-law approximations to these potentials: $V(ϕ) \propto ϕ^{2n}$. We show that in the slow-roll regime, when $\dot ϕ^2/2 \ll V(ϕ)$, the full ULA potentials yield a more interesting range of possibilities for quintessence than do the corresponding power law approximations. For rapidly oscillating scalar fields, we derive the equation of state parameter and oscillation frequency for the ULA potentials and show how they deviate from the corresponding power-law values. We derive an analytic expression for the equation of state parameter that better approximates the ULA value than does the pure power-law approximation.
description: 9 pages, 6 figures
Compressed Sensing in Astronomy
Creators: name: Bobin, J.
name: Starck, J-L
name: Ottensamer, R.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recent advances in signal processing have focused on the use of sparse representations in various applications. A new field of interest based on sparsity has recently emerged: compressed sensing. This theory is a new sampling framework that provides an alternative to the well-known Shannon sampling theory. In this paper we investigate how compressed sensing (CS) can provide new insights into astronomical data compression and more generally how it paves the way for new conceptions in astronomical remote sensing. We first give a brief overview of the compressed sensing theory which provides very simple coding process with low computational cost, thus favoring its use for real-time applications often found on board space mission. We introduce a practical and effective recovery algorithm for decoding compressed data. In astronomy, physical prior information is often crucial for devising effective signal processing methods. We particularly point out that a CS-based compression scheme is flexible enough to account for such information. In this context, compressed sensing is a new framework in which data acquisition and data processing are merged. We show also that CS provides a new fantastic way to handle multiple observations of the same field view, allowing us to recover information at very low signal-to-noise ratio, which is impossible with standard compression methods. This CS data fusion concept could lead to an elegant and effective way to solve the problem ESA is faced with, for the transmission to the earth of the data collected by PACS, one of the instruments on board the Herschel spacecraft which will be launched in 2008.
description: 30 pages - submitted to IEEE Journal on Selected Topics in Signal Processing
: Η επανενίσχυση της άρνησης (συγκριτική ανάλυση της ελληνικής και ρωσικής):
Creators: name: Nedvyga, Olena Viatseslav (Νεντβίγκα, Ελένη)
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Επανενίσχυση της άρνησης
Γενική της άρνησης
Ρωσικά
Reinforcement of negation
Genitive of negation
Russian

description: Σκοπός της διπλωματικής ήταν η μελέτη του φαινομένου της επανενίσχυσης της άρνησης στη βάση του ελαχίστου στα πλαίσια της συγκριτικής ανάλυσης των δύο γλωσσών: ελληνικής και ρωσικής. Παρουσιάσαμε την ορολογία και τις κυριαρχούσες θεωρίες που χρησιμοποιούνται ως βάση για τη θεωρία πολικότητας στα πλαίσια της οποίας εξετάσαμε τις εκφράσεις του ελαχίστου που λειτουργούν ως Στοιχεία Αρνητικής Πολικότητας όταν επανενισχύουν την άρνηση. Εντοπίσαμε τις εκφράσεις του ελαχίστου της ρωσικής, τα περιβάλλοντα στα οποία νομιμοποιούνται και λειτουργούν ως ΣΑΠ. Αναλύσαμε τις ομοιότητες και τις διαφορές των δύο υπό εξέταση γλωσσών. Εξετάσαμε επιπλέον το φαινόμενο της Γενικής της Άρνησης στη ρωσική βάσει της σημασιολογικής έννοιας της μεταβατικότητας. Ασχοληθήκαμε με την διαχρονική εξέλιξη της δομής. Ανακαλύψαμε ότι η Γενική της Άρνησης είναι γραμματικοποιημένο μέσο της επανενίσχυσης της άρνησης στη ρωσική, το οποίο νομιμοποιεί τις εκφράσεις του ελαχίστου που λειτουργούν ως εμφατικά ΣΑΠ.
description: The aim of the present thesis was the study of phenomenon of reinforcement of negation and minimizers which function as emphatic Negative Polarity Items. The research was based on the comparative analysis of two languages: Greek and Russian. We presented the terminology and the dominating theories that are used as base for the Polarity Theory in the frame of which we examined the minimizers which function as NPIs when they reinforce the negation. We detected the minimizers of Russian, the environments in which they are licensed as NPIs. Furthermore, we analyzed the similarities and differences between the two languages under review. We also examined the phenomenon of Genitive of Negation in Russian. The analysis was based on the semantic notion of Transitivity. Moreover we examined the diachronic development of the Genitive of Negation structure. We discovered that the structure under review is the grammaticalized means of reinforcement of negation in Russian.
Η τέχνη στην σκέψη του Αριστοτέλη του Πλάτωνα. Οι θεωρίες τους για τη μίμηση:
Creators: name: Λυμπιτσιούνη, Μαλαματένια Δημητρίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2011
Subjects: Μίμηση
Τέχνη
Αισθητική
Mimesis
Art
Aesthetic

description: Σκοπός της διατριβής ήταν η μελέτη των θεωριών της μίμησης από τους δύο μεγαλύτερους φιλοσόφους της αρχαιότητας τον Πλάτωνα και τον Αριστοτέλη. Εξετάσθηκε αρχικά η έννοια του όρου τέχνη στη σκέψη του Πλάτωνα και του Αριστοτέλη. Στη συνέχεια παρουσιάστηκαν αναλυτικά σε τέσσερα μεγάλα έργα του Πλάτωνα οι απόψεις του ,οι σκέψεις του και η θεωρία του για τη μίμηση. Τα έργα στα οποία έγινε η μελέτη είναι: το 10ο βιβλίο της Πολιτείας , ο Σοφιστής, ο Κρατύλος και τέλος ο Φίληβος. Ακολουθεί η μελέτη για τη θεωρία της μίμησης του Αριστοτέλη σε δύο από τα μεγαλύτερα έργα του. Στο «περί ποιητικής» και στη» Ρητορική». Στο τελευταίο μέρος της διατριβής διαπιστώνονται οι διαφορές και οι ομοιότητες μεταξύ του Πλάτωνα και του Αριστοτέλη στις θεωρίες τους για τη μίμηση .
description: The present thesis aimed to study two theories on Mimesis formed by two of the greatest Greek ancient philosophers, Plato and Aristotle. Initially, we went through the term “Art” in Plato’s and Aristotle’s thought. Moreover, we presented analytically Plato’s opinions, thoughts and his theory on Mimesis in four great works of his: the 10th book of The Republic, the Sophist, Cratylus and Philebus. What follows is a study on Aristotle’s theory on mimesis in two of his most important works: Poetics and Rhetoric. Finally, in the last chapter of the thesis we quoted the similarities and differences between Plato’s and Aristotle’s theories on mimesis.
Life Cycle Assessment of Maritime Pine Wood: A Portuguese Case Study
Creators: name: Ferreira, José
name: Jones, Dennis
name: Esteves, Bruno
name: Cruz-Lopes, Luisa
name: Pereira, Helena
name: Domingos, Idalina
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Cell Biology
subject: Environmental Sciences not elsewhere classified
subject: Ecology
subject: FOS: Biological sciences
subject: Biological Sciences not elsewhere classified
subject: Science Policy
subject: Hematology
subject: Computational Biology

description: Life Cycle Assessment has become one of the most recognized and internationally accepted method for examining the environmental performance of forest products and processes. The main aim of this study was to evaluate the potential environmental impact associated with different commercial outputs of maritime pine wood (round, industrial, and residual) produced in the Portuguese forest under natural regeneration. Identifying the hotspots in the life cycle (cradle-to-gate) of each sort of maritime pine was another objective of the study. SimaPro software was used for this study, whilst the CML-IA (baseline) method was chosen to assess the environmental impacts. The study showed that round wood presented the highest values in all impact categories and industrial wood presented the lowest values except in photochemical oxidation where residual wood was the best co-product when economic allocation is chosen. The major hot spots appeared to be the felling and hauling processes due to fossil fuel combustion in the chainsaw and forwarder, respectively. The co-product that should be more environmentally friendly considerably depends on the allocation procedure chosen.
Towards Engineering Intrinsic Linewidths and Line-Broadening in Perovskite Nanoplatelets
Creators: name: Liu, Albert
name: Nagamine, Gabriel
name: Bonato, Luiz G.
name: Almeida, Diogo B.
name: Zagonel, Luiz F.
name: Nogueira, Ana F.
name: Padilha, Lazaro A.
name: Cundiff, Steven T.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optics (physics.optics)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Perovskite nanoplatelets possess extremely narrow absorption and emission linewidths, which are crucial characteristics for many optical applications. However, their underlying intrinsic and extrinsic line-broadening mechanisms are poorly understood. Here, we apply multi-dimensional coherent spectroscopy to determine the homogeneous line-broadening of colloidal perovskite nanoplatelet ensembles. We demonstrate control of not only their intrinsic linewidths, but also control of various broadening mechanisms by tuning the platelet geometry. Remarkably, we find that decreasing nanoplatelet thickness by a single polyhedral layer results in a 2-fold reduction of the inhomogeneous linewidth and a 3-fold reduction of the intrinsic homogeneous linewidth to the sub-meV regime. In addition, our measurements suggest homogeneously broadened exciton resonances in 3-layer (but not necessarily 4-layer) nanoplatelets at room-temperature.
Absence of HI in the Bootes Dwarf Spheroidal Galaxy
Creators: name: Bailin, Jeremy
name: Ford, Alyson
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Neutral hydrogen observations towards the Bootes dwarf spheroidal galaxy, a very low luminosity metal-poor Galactic satellite, were obtained using the Parkes Radio Telescope. We do not detect any HI in or around Bootes to a 3sigma upper limit of 180 Msun within the optical half light radius and 8000 Msun within 1.6 kpc. Its HI mass-to-light ratio is less than 0.002 Msun/Lsun, making Bootes one of the most gas-poor galaxies known. Either reionisation severely inhibited gas infall onto the proto-Bootes, or large amounts of gas have been removed by ram pressure and/or tidal stripping. Since Bootes lies on the mass-metallicity fundamental line, this relation and the inefficiency of star formation at the faintest end of the galaxy luminosity function must be partly driven, or at least not disrupted, by extreme gas loss in such low luminosity galaxies. We also do not detect any HI associated with the leading tidal tail of the Sagittarius dSph galaxy, which fortuitously passes through the observed field, to a 3sigma column density limit of 2 x 10^17 cm^-2. This suggests that either the leading gaseous tail is ionised, or the gas in the trailing tail was removed before the current tidal disruption of the parent dSph began.
description: 5 pages, MNRAS, accepted
Fuzzy Extractors: How to Generate Strong Keys from Biometrics and Other Noisy Data
Creators: name: Dodis, Yevgeniy
name: Ostrovsky, Rafail
name: Reyzin, Leonid
name: Smith, Adam
Publisher: name: arXiv
Year: 2006
Subjects: subject: Cryptography and Security (cs.CR)
subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: We provide formal definitions and efficient secure techniques for - turning noisy information into keys usable for any cryptographic application, and, in particular, - reliably and securely authenticating biometric data. Our techniques apply not just to biometric information, but to any keying material that, unlike traditional cryptographic keys, is (1) not reproducible precisely and (2) not distributed uniformly. We propose two primitives: a "fuzzy extractor" reliably extracts nearly uniform randomness R from its input; the extraction is error-tolerant in the sense that R will be the same even if the input changes, as long as it remains reasonably close to the original. Thus, R can be used as a key in a cryptographic application. A "secure sketch" produces public information about its input w that does not reveal w, and yet allows exact recovery of w given another value that is close to w. Thus, it can be used to reliably reproduce error-prone biometric inputs without incurring the security risk inherent in storing them. We define the primitives to be both formally secure and versatile, generalizing much prior work. In addition, we provide nearly optimal constructions of both primitives for various measures of ``closeness'' of input data, such as Hamming distance, edit distance, and set difference.
description: 47 pp., 3 figures. Prelim. version in Eurocrypt 2004, Springer LNCS 3027, pp. 523-540. Differences from version 3: minor edits for grammar, clarity, and typos
Supplementary Tables and Figures to “Why Does Library Holding Format Really Matter for Book Impact Assessment? Comprehensive Study of Print and Eholdings and 14 Other Metrics”
Creators: name: Maleki, Ashraf
Publisher: name: figshare
Year: 2020
Subjects: subject: Library and Information Studies
subject: FOS: Media and communications

description: This file is the online appendix to “Why Does Library Holding Format Really Matter for Book Impact Assessment? Comprehensive Study of Print and Eholdings and 14 Other Metrics”.All figures and tables are reported in one file. Browse content in the List of Figures and Tables.
Endothelial cell adhesion molecules: expression, upregulation and modulation of human brain microvessel endothelial cell-leukocyte interactions
Creators: name: Wong, Donald Chun Kit
Publisher: name: University of British Columbia
Year: 2009

description: Endothelial cells (EC) lining the cerebral blood vessels are responsible for the formation and maintenance of a unique structural and functional barrier, the blood-brain barrier (BBB), that normally prevents the movement of white blood cells from blood into brain. Inflammatory and infectious diseases of the central nervous system (CNS), including multiple sclerosis, encephalitis, meningitis and infarction, are characterized by increased BBB permeability and infiltration of the brain by leukocytes. The mechanisms that regulate the traffic of leukocytes across the BBB have not yet been elucidated. A group of EC surface molecules called adhesion molecules, have been implicated in interactions between inflammatory cells and extracerebral EC. They include E-selectin, vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and platelet/endothelial cell adhesion molecule-1 (PECAM-1). Blocking these molecules with antibodies (Abs) reduces leukocyte traffic across EC. One of these molecules, ICAM-1, has been demonstrated in inflammatory CNS lesions. The objective of this study was to investigate the expression and function of four EC adhesion molecules in an in vitro model of the human BBB. The results indicate that primary cultures of unstimulated human brain microvessel EC (HBMEC) form high resistance monolayers and express low levels of E-selectin, VCAM-1 and ICAM-1 that can be significantly upregulated following stimulation with cytokines and LPS. PECAM-1 is strongly expressed by all cells constitutively. Treatment of HBMEC with TNF increases monolayer permeability, and augments adhesion and migration of polymorphonuclear leukocytes (PMN) and T-lymphocytes across the monolayers. Adhesion of resting T-lymphocytes to activated endothelium is mediated by VCAM-1 and ICAM-1. ICAM-1, E-selectin and PECAM-1 participate in T-lymphocyte migration across HBMEC monolayers. Adhesion of PMN to activated HBMEC is mediated by ICAM-1 and E-selectin, while ICAM-1 is involved in the migration process. Anti-adhesion molecule Abs reduce adhesion and/or migration but have no effect on the increased endothelial permeability secondary to leukocyte migration. These studies indicate that EC adhesion molecules, induced by cytokines, mediate cerebral EC-leukocyte interactions which, in association with a concurrent increase in endothelial permeability, may facilitate leukocyte traffic across the BBB in the early stages of CNS inflammation.
Percolation model for the superconductor-insulator transition in granular films
Creators: name: Strelniker, Yakov M.
name: Frydman, A.
name: Havlin, S.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We study the temperature dependence of the superconductor-insulator transition in granular superconductors. Empirically, these systems are characterized by very broad resistance tails, which depend exponentially on the temperature, and the normal state resistance. We model these systems by a two-dimensional random resistor percolation networks in which the resistance between two grains is governed either by Josephson junction coupling or by quasi particle tunneling. Our numerical simulations as well as an effective medium evaluation explain the experimental results over a wide range of temperatures and resistances. Using effective medium approximation we find an analytical expression for the effective resistance of the system and the value of the critical resistance separating conducting from insulating branches.
description: 4 pages, 2 figures
title: Games with a Purpose for Part-of-Speech Tagging and the Impact of the Applied Game Design Elements on Player Enjoyment and Games with a Purpose Preference
Creators: name: Segundo Díaz, Rosa Lilia
name: Rovelo Ruiz, Gustavo
name: Bouzouita, Miriam
name: Hoste, Véronique
name: Coninx, Karin
Publisher: name: Humboldt-Universität zu Berlin
Year: 2025
Subjects: subject: games with a purpose
subject: evaluation
subject: player enjoyment
subject: game design elements
subject: part-of-speech tagging
subject: 600 Technik und Technologie

description: Linguistic tasks such as Part-of-Speech (PoS) tagging can be tedious, but are crucial for the development of Natural Language Processing (NLP) tools. Games With A Purpose (GWAPs) aim to reduce the monotony of the task for native speakers and non-experts who contribute to crowdsourcing projects. This study focuses on revising and correcting PoS tags in the Corpus Oral y Sonoro del Español Rural (COSER), the largest collection of oral data in the Spanish-speaking world, to create a parsed corpus of European Spanish dialects. It also examines how game design elements (GDEs) affect players’ enjoyment. Three games— Agentes , Tesoros , and Anotatlón —were developed, incorporating different GDEs, such as rewards and challenges. The results show two levels of enjoyment: at the concept level with Anotatlón , and at the level of individual GDEs with Tesoros . This suggests that certain GDEs influence player enjoyment and, consequently, their preference for certain games. However, the study also shows the complexity of evaluating triggers for player enjoyment in games with more than one implemented GDE.
Predicting Vegetation Carbon Density Distribution in different Terrains in Subtropical Forests in China
Creators: name: Ji, Biyong
name: Yin, Jiayang
name: Shi, Yongjun
name: Xu, Lin
name: Tao, Jixing
name: Zhou, Yufeng
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Medicine
subject: Molecular Biology
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Ecology
subject: FOS: Biological sciences
subject: Biological Sciences not elsewhere classified
subject: Developmental Biology
subject: Plant Biology

description: Through large-scale afforestation and reforestation, China has increased its forest area and improved forest quality, making considerable contributions to carbon stocks of the world’s forests. As one of the important indicators of forest quality and carbon potential, vegetation carbon density (VCD) is affected by different factors at different scales, but little is known about the effect of topographic factors on the VCD of subtropical forests in the southeast of China, especially at a large regional scale. Based on the national forest continuous inventory protocols, more than 2000 permanent samples (2061 samples in 2009, 2115 samples in 2014, and 2132 samples in 2016) of major forest types (Bamboo forests (BB), broad-leaved forests (BF), mixed forests (MF), coniferous forests (CF)) were grouped by topographic factors to compare the distribution of VCD in Zhejiang Province of China. The four topographic factors (altitude, slope gradient, aspect, and slope position) explained 16.2%~28.4% of the variance in different forest types in the random forest model and the importance order of the four terrain variables is basically corresponding to the significance in the radar charts. The VCD of each forest type varies significantly at different altitudes (p < .05, except for the BB samples in 2009). In general, VCD tends to be higher at high altitudes. The VCD in BB and BF varies significantly with slope gradient (p < .05, the largest on the steep slope and the smallest on the gentle slope); however, the VCD of CF and MF showed almost no difference in different slope gradients. We found significant differences in VCD between the eight aspects in the mixed forest (p < .05, the largest in the S and SW aspects), but not in the other three forest types. As for different slope positions, the VCD of ridges is relatively large, and the VCD of the upslope is generally larger than that of the downslope (more pronounced in BB and BF, all p < .05). This study made a detailed analysis of the greening distribution in different topographic factors, and the research conclusion could provide a scientific basis for the selection of afforestation location and forest scientific management, and contribute to the improvement of the capability of coping with climate change in subtropical forests.
Graphene Terahertz Devices for Sensing and Communication
Creators: name: Samaha, Anna-Christina
name: Doumani, Jacques
name: Kritzell, T. Elijah
name: Xu, Hongjing
name: Baydin, Andrey
name: Ajayan, Pulickel M.
name: Tahchi, Mario El
name: Kono, Junichiro
Publisher: name: arXiv
Year: 2024
Subjects: subject: Optics (physics.optics)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Graphene-based terahertz (THz) devices have emerged as promising platforms for a variety of applications, leveraging graphene's unique optoelectronic properties. This review explores recent advancements in utilizing graphene in THz technology, focusing on two main aspects: THz molecular sensing and THz wave modulation. In molecular sensing, the environment-sensitive THz transmission and emission properties of graphene are utilized for enabling molecular adsorption detection and biomolecular sensing. This capability holds significant potential, from the detection of pesticides to DNA at high sensitivity and selectivity. In THz wave modulation, crucial for next-generation wireless communication systems, graphene demonstrates remarkable potential in absorption modulation when gated. Novel device structures, spectroscopic systems, and metasurface architectures have enabled enhanced absorption and wave modulation. Furthermore, techniques such as spatial phase modulation and polarization manipulation have been explored. From sensing to communication, graphene-based THz devices present a wide array of opportunities for future research and development. Finally, advancements in sensing techniques not only enhance biomolecular analysis but also contribute to optimizing graphene's properties for communication by enabling efficient modulation of electromagnetic waves. Conversely, developments in communication strategies inform and enhance sensing capabilities, establishing a mutually beneficial relationship.
Wetting behavior of a colloidal particle trapped at a composite liquid-vapor interface of a binary liquid mixture
Creators: name: Kim, Hyojeong
name: Schimmele, Lothar
name: Dietrich, S.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: A partially miscible binary liquid mixture, composed of A and B particles, is considered theoretically under conditions for which a stable A-rich liquid phase is in thermal equilibrium with the vapor phase. The B-rich liquid is metastable. The liquids and the thermodynamic conditions are chosen such, that the interface between the A-rich liquid and the vapor contains an intervening wetting film of the B-rich phase. In order to obtain information about the large-scale fluid structure around a colloidal particle, which is trapped at such a composite liquid-vapor interface, three related and linked wetting phenomena at planar liquid-vapor, wall-liquid, and wall-vapor interfaces are studied analytically, using classical density functional theory in conjunction with the sharp-kink approximation for the number density profiles of the A and B particles. If in accordance with the so-called mixing rule the strength of the A-B interaction is given by the geometric mean of the strengths of the A-A and B-B interactions, and similarly the ratio between the wall-A and the wall-B interaction, the scenario, in which the colloid is enclosed by a film of the B-rich liquid, can be excluded. Up to six distinct wetting scenarios are possible, if the above mixing rules for the fluid-wall and for the fluid-fluid interactions are relaxed. The way the space of system parameters is divided into domains corresponding to the six scenarios, and which of the domains actually appear, depends on the signs of the deviations from the mixing rule prescriptions. Relevant domains emerge, if the ratio between the strengths of the wall-A and the wall-B interactions is reduced as compared to the mixing rule prescription, or if the strength of the A-B interaction is increased to values above the one from the mixing rule prescription. The range, within which the contact angle may vary inside the various domains, is also studied.
description: 28 pages, 6 figures
Thermal production of gravitinos
Creators: name: Rychkov, Vyacheslav S.
name: Strumia, Alessandro
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: We reconsider thermal production of gravitinos in the early universe, adding to previously considered 2 -> 2 gauge scatterings: a) production via 1 -> 2 decays, allowed by thermal masses; b) the effect of the top Yukawa coupling; c) a proper treatment of the reheating process. Our final result behaves physically (larger couplings give a larger rate) and is twice larger than previous results, implying e.g. a twice stronger constraint on the reheating temperature. Accessory results about (supersymmetric) theories at finite temperature and gravitino couplings might have some interest.
description: 33 pages (long appendices), 12 figures. Final version to appear on PRD
Evidence for particle-hole excitations in the triaxial strongly-deformed well of ^{163}Tm
Creators: name: Pattabiraman, N. S.
name: Gu, Y.
name: Frauendorf, S.
name: Garg, U.
name: Li, T.
name: Nayak, B. K.
name: Wang, X.
name: Zhu, S.
name: Ghugre, S. S.
name: Janssens, R. V. F.
name: Chakrawarthy, R. S.
name: Whitehead, M.
name: Macchiavelli, A. O.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Two interacting, strongly-deformed triaxial (TSD) bands have been identified in the Z = 69 nucleus ^{163}Tm. This is the first time that interacting TSD bands have been observed in an element other than the Z = 71 Lu nuclei, where wobbling bands have been previously identified. The observed TSD bands in ^{163}Tm appear to be associated with particle-hole excitations, rather than wobbling. Tilted-Axis Cranking (TAC) calculations reproduce all experimental observables of these bands reasonably well and also provide an explanation for the presence of wobbling bands in the Lu nuclei, and their absence in the Tm isotopes.
description: 13 pages, 7 figures
Ο σύγχρονος καλλιτέχνης ως σταρ:
Creators: name: Παπαθανασίου, Ευαγγελία Αντωνίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2011
Subjects: Σύγχρονη τέχνη
Σταρ σύστεμ
Ντάμιεν Χιρστ
Damien Hirst
Contemporary art
Art and management

description: Η μελέτη με τον τίτλο ‘Ο Σύγχρονος Καλλιτέχνης ως Σταρ’, αφορά την πορεία του σύγχρονου καλλιτέχνη, με αφετηρία τη δεκαετία του ’70 όπου και συντελείται η μεγάλη τομή όσον αφορά στην υπόστασή του, μέχρι τη σημερινή, ολοκληρωτική κυριαρχία του καλλιτεχνικού υποκειμένου έναντι του-καλλιτεχνικού- αντικειμένου. Μια πορεία που πλέον αμβλύνει τα όρια ανάμεσα στην καλλιτεχνική και βιομηχανική παραγωγή. Αφορά επίσης τη διαμόρφωση της ‘εικόνας’ του καλλιτέχνη, εικόνα που ξεπερνά την καλλιτεχνική του δημιουργία και προχωρά στη διαμόρφωση μιας «persona», με τον ίδιο να αποτελεί πλέον ένα ‘brand’, αντίστοιχης εμβέλειας με εκείνα των εμπορικών και καταναλωτικών αγαθών, αποτελώντας ταυτόχρονα και την καλύτερη διαφήμιση του έργου του. Σε αυτό το πλαίσιο εξετάζονται οι περιπτώσεις δύο καλλιτεχνών: του Andy Warhol, του πρώτου καλλιτέχνη που επιδίωξε και κατάφερε μια τόσο πετυχημένη μετατόπιση του ενδιαφέροντος από το έργο στον δημιουργό, και του Damien Hirst, του σύγχρονου καλλιτέχνη που άλλαξε άρδην το σκηνικό στην παγκόσμια τέχνη, επαναδιαπραγματεύτηκε το έργο του με οικονομικούς όρους, προσπέρασε το σκόπελο των γκαλερί, και έγινε ο ίδιος το ‘εμπορικό σήμα’(brand) που αποφέρει αξία στο έργο του, δίνοντας στην εικαστική δημιουργία δευτερεύοντα ρόλο.
description: The essay titled ‘Contemporary Artist as Star’, is an essay about contemporary art and artists, starting from the 70’s when we are presented with new approaches towards art, until today that we experience how the artistic object completely took over the artistic subject. A course that makes the boundaries between artistic and industrial production disappear. This essay is also about the “image” of the artist, an image that goes beyond his artistic production, to the creation of a “persona”, with the artist himself being a “brand” as If another commercial product, while at the same time he is the best advertisement for his work. At this context two artists are being examined: Andy Warhol, the first artist who attempted and completed such a successful swift from the “work” of art to the “creator” of it, and Damien Hirst, the contemporary artist who changed completely all our thoughts on what contemporary art had been so far, since he introduced us with the economical terms and aspects of-contemporary-art. As far as his own artistic creation was regarded, he overcame galleries and became himself the brandname that made his work valuable, while artistic creativity started ever since play a far less important part.
Molecular simulation of thermosetting polymer hardening: reactive events enabled by controlled topology transfer
Creators: name: Meißner, Robert H.
name: Konrad, Julian
name: Boll, Benjamin
name: Fiedler, Bodo
name: Zahn, Dirk
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: We present a quantum mechanical / molecular mechanics (QM/MM) to tackle chemical reactions with substantial molecular reorganization. For this, molecular dynamics simulations with smoothly switched interaction models are used to suggest suitable product states, whilst a Monte Carlo algorithm is employed to assess the reaction likeliness subject to energetic feasibility. As a demonstrator, we study the cross-linking of bisphenol F diglycidyl ether (BFDGE) and 4,6-diethyl-2-methylbenzene-1,3-diamine (DETDA). The modeling of epoxy curing was supplemented by Differential Scanning Calorimetry (DSC) measurements, which confirms the degrees of cross-linking as a function of curing temperature. Likewise, the heat of formation and the mechanical properties of the resulting thermosetting polymer are found to be in good agreement with previous experiments.
description: To be published in ACS Macromolecules
Development and Characterization of a Precisely Adjustable Fiber Polishing Arm
Creators: name: Smith, Michael P.
name: Chattopadhyay, Sabyasachi
name: Hauser, Andrew
name: Oppor, Joshua E
name: Bershady, Matthew A
name: Wolf, Marsha J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The development of bare fiber or air-gapped microlens-fiber coupled Integral Field Units (IFUs) for astronomical applications requires careful treatment of the fiber end-faces (terminations). Previous studies suggest that minimization of fiber end face irregularity leads to better optical performance in terms of the diminishing effect of focal ratio degradation. Polishing has typically been performed using commercial rotary polishers with multiple gradually decreasing grit sizes. These polishers generally lack the ability to carefully adjust angular position and polishing force. Control of these parameters vastly help in getting a repeatable and controllable polish over a variety of glass/epoxy/metal matrices that make up integral filed units and fiber slits. A polishing arm is developed to polish the fiber terminations (IFU, mini-bundles and v-grooves) of the NIR Fiber System for the RSS spectrograph at SALT. The polishing arm angular adjustments ensure the correct position and orientation of each termination on the polishing surface during the polish. Various studies have indicated that the fiber focal ratio also degrades if the fiber end face comes under excessive stress. The polishing arm is fitted with a load cell to enable control of the polishing force. We have explored the minimal applicable end stress by applying different loads while polishing. The arm is modular to hold a variety of fiber termination styles. The polishing arm is also designed to access a fiber inspection microscope without removing the fiber termination from the arm. This enables inspection of the finish quality at various stages through polishing process.
Early feasibility of an embedded bi-directional brain-computer interface for ambulation
Creators: name: Lim, Jeffrey
name: Wang, Po T.
name: Sohn, Wonjoon
name: Serrano-Amenos, Claudia
name: Ibrahim, Mina
name: Lin, Derrick
name: Thaploo, Shravan
name: Shaw, Susan J.
name: Armacost, Michelle
name: Gong, Hui
name: Lee, Brian
name: Lee, Darrin
name: Andersen, Richard A.
name: Heydari, Payam
name: Liu, Charles Y.
name: Nenadic, Zoran
name: Do, An H.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantitative Methods (q-bio.QM)
subject: FOS: Biological sciences
subject: 92C55

description: Current treatments for paraplegia induced by spinal cord injury (SCI) are often limited by the severity of the injury. The accompanying loss of sensory and motor functions often results in reliance on wheelchairs, which in turn causes reduced quality of life and increased risk of co-morbidities. While brain-computer interfaces (BCIs) for ambulation have shown promise in restoring or replacing lower extremity motor functions, none so far have simultaneously implemented sensory feedback functions. Additionally, many existing BCIs for ambulation rely on bulky external hardware that make them ill-suited for non-research settings. Here, we present an embedded bi-directional BCI (BDBCI), that restores motor function by enabling neural control over a robotic gait exoskeleton (RGE) and delivers sensory feedback via direct cortical electrical stimulation (DCES) in response to RGE leg swing. A first demonstration with this system was performed with a single subject implanted with electrocorticography electrodes, achieving an average lag-optimized cross-correlation of 0.80$\pm$0.08 between cues and decoded states over 5 runs.
description: 5 pages, 6 figures, two tables, also submitted to IEEE EMBC 2024 conference
Excited-state quantum phase transitions in spinor Bose-Einstein condensates
Creators: name: Feldmann, Polina
name: Klempt, Carsten
name: Smerzi, Augusto
name: Santos, Luis
name: Gessner, Manuel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Excited-state quantum phase transitions (ESQPTs) extend the notion of quantum phase transitions beyond the ground state. They are characterized by closing energy gaps amid the spectrum. Identifying order parameters for ESQPTs poses however a major challenge. We introduce spinor Bose-Einstein condensates as a versatile platform for studies of ESQPTs. Based on the mean-field dynamics, we define a topological order parameter that distinguishes between excited-state phases, and discuss how to interferometrically access the order parameter in current experiments. Our work opens the way for the experimental characterization of excited-state quantum phases in atomic many-body systems.
description: 14 pages, 3 figures
The iron abundance of the Magellanic Bridge
Creators: name: Dufton, P. L.
name: Ryans, R. S. I.
name: Thompson, H. M. A.
name: Street, R. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: High-resolution HST ultra-violet spectra for five B-type stars in the Magellanic Bridge and in the Large and Small Magellanic Clouds have been analysed to estimate their iron abundances. Those for the Clouds are lower than estimates obtained from late-type stars or the optical lines in B-type stars by approximately 0.5 dex. This may be due to systematic errors possibly arising from non-LTE effects or from errors in the atomic data as similar low Fe abundances having previously been reported from the analysis of the ultra-violet spectra of Galactic early-type stars. The iron abundance estimates for all three Bridge targets appear to be significantly lower than those found for the SMC and LMC by approximately -0.5 dex and -0.8 dex respectively and these differential results should not be affected by any systematic errors present in the absolute abundance estimates. These differential iron abundance estimates are consistent with the underabundances for C, N, O, Mg and Si of approximately -1.1 dex relative to our Galaxy previously found in our Bridge targets. The implications of these very low metal abundances for the Magellanic Bridge are discussed in terms of metal deficient material being stripped from the SMC.
description: Accepted for publication in MNRAS
Moiré optical phonons dancing with heavy electrons in magic-angle twisted bilayer graphene
Creators: name: Shi, Hao
name: Miao, Wangqian
name: Dai, Xi
Publisher: name: arXiv
Year: 2024
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Electron-phonon coupling in magic-angle twisted bilayer graphene is an important but difficult topic. We propose a scheme to simplify and understand this problem. Weighted by the coupling strength with the low-energy heavy electrons ($f$ orbitals), several moiré optical phonons are singled out which strongly couple to the flat bands. These modes have localized envelopes in the moiré scale, while in the atomic scale they inherit the monolayer oscillations like the Kekulé pattern. They flip the flavor of $f$ orbitals, helping stabilize some symmetry-breaking orders. Such electron-phonon couplings are incorporated into an effective extended Holstein model, where both phonons and electrons are written as moiré scale basis. We hope this model will inspire some insights guiding further studies about the superconductivity and other correlated effects in this system.
Early universe in view of a modified theory of gravity
Creators: name: Mandal, Ranajit
name: Saha, Dalia
name: Alam, Mohosin
name: Sanyal, Abhik Kumar
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the quantum evolution of the early universe, its semi-classical analogue together with inflationary regime, in view of a generalized modified theory of gravity. The action is built by supplementing the non-minimally coupled scalar-tensor theory of gravity with scalar curvature squared term and a Gauss-Bonnet-dilatonic coupled term. It is generalized, since all the parameters are treated as arbitrary functions of the scalar field. It is interesting to explore the fact that instead of considering additional flow parameters, an effective potential serves the purpose of finding inflationary parameters. The dilaton stabilization issue appears here as a problem with reheating. Addition of a cosmological constant term alleviates the problem, and inflation is effectively driven by the vacuum energy density. Thus Gauss-Bonnet term might play a significant role in describing late-time cosmic evolution.
description: 26 pages, 4 figures. arXiv admin note: text overlap with arXiv:2004.04332
Non-Kaehler attracting manifolds
Creators: name: Dall'Agata, Gianguido
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We observe that the new attractor mechanism describing IIB flux vacua for Calabi-Yau compactifications has a possible extension to the landscape of non-Kaehler vacua that emerge in heterotic compactifications with fluxes. We focus on the effective theories coming from compactifications on generalized half-flat manifolds, showing that the Minkowski "attractor points'' for 3-form fluxes are special-hermitian manifolds.
description: 18 pages. v2: Minor polishing, reference added. v3: More cleanup, final version for JHEP
The white dwarf binary pathways survey V. The Gaia white dwarf plus AFGK binary sample and the identification of 23 close binaries
Creators: name: Ren, J. -J.
name: Raddi, R.
name: Rebassa-Mansergas, A.
name: Hernandez, M. S.
name: Parsons, S. G.
name: Irawati, P.
name: Rittipruk, P.
name: Schreiber, M. R.
name: Gansicke, B. T.
name: Torres, S.
name: Wang, H. -J.
name: Zhang, J. -B.
name: Zhao, Y.
name: Zhou, Y. -T.
name: Han, Z. -W.
name: Wang, B.
name: Liu, C.
name: Liu, X. -W.
name: Wang, Y.
name: Zheng, J.
name: Wang, J. -F.
name: Zhao, F.
name: Cui, K. -M.
name: Shi, J. -R.
name: Tian, H.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Close white dwarf binaries consisting of a white dwarf and an A, F, G or K type main sequence star, henceforth close WD+AFGK binaries, are ideal systems to understand the nature of type Ia supernovae progenitors and to test binary evolution models. In this work we identify 775 WD+AFGK candidates from TGAS (The Tycho-Gaia Astrometric Solution) and Gaia Data Release 2 (DR2), a well-defined sample of stars with available parallaxes, and we measure radial velocities (RVs) for 275 of them with the aim of identifying close binaries. The RVs have been measured from high resolution spectra obtained at the Xinglong 2.16m Telescope and the San Pedro Mártir 2.12m Telescope and/or from available LAMOST DR6 (low-resolution) and RAVE DR5 (medium-resolution) spectra. We identify 23 WD+AFGK systems displaying more than 3$σ$ RV variation among 151 systems for which the measured values are obtained from different nights. Our WD+AFGK binary sample contains both AFGK dwarfs and giants, with a giant fraction $\sim$43%. The close binary fractions we determine for the WD+AFGK dwarf and giant samples are $\simeq$24% and $\simeq$15%, respectively. We also determine the stellar parameters (i.e. effective temperature, surface gravity, metallicity, mass and radius) of the AFGK companions with available high resolution spectra. The stellar parameter distributions of the AFGK companions that are members of close and wide binary candidates do not show statistically significant differences.
description: 22 pages, 17 figures, 9 tables. Accepted for publication in The Astrophysical Journal
Αριθμητική Διερεύνηση μεθόδων επίλυσης διαφορικών εξισώσεων με έμφαση στις μεθόδους Fehlberg- Εφαρμογές με προγράμματα σε matlab:
Creators: name: Γεωργιάδης, Νικόλαος Απόστολου
Publisher: name: Aristotle University of Thessaloniki
Year: 2011
Subjects: Διαφορικές εξισώσεις
Runge-Kutta μέθοδοι
Fehlberg μέθοδοι
Differential Equations
Runge-Kutta methods
Fehlberg methods

description: Πολλά φυσικά φαινόμενα περιγράφονται μαθηματικά από διαφορικές εξισώσεις είτε είναι συνήθεις διαφορικές εξισώσεις είτε διαφορικές εξισώσεις με μερικές παραγώγους. Δυστυχώς λίγες διαφορικές εξισώσεις λύνονται αναλυτικά γι αυτό ήδη από τις αρχές του αιώνα έγιναν προσπάθειες για να βρεθούν αριθμητικές μέθοδοι επίλυσης των διαφορικών εξισώσεων. To κύριο μέρος της έρευνας στην αριθμητική επίλυση διαφορικών εξισώσεων ξεκίνησε από την δημιουργία των πρώτων ηλεκτρονικών υπολογιστών. Η αριθμητική επίλυση των διαφορικών εξισώσεων συνίσταται στην κατασκευή αλγορίθμων και στην συνέχεια η υλοποίηση τους με λογισμικό Η/Υ. Μεγάλο μέρος της έρευνας στα εφαρμοσμένα μαθηματικά αποτελεί η κατασκευή τέτοιων αλγορίθμων. Οι αριθμητικές μέθοδοι επίλυσης συνήθων διαφορικών εξισώσεων επιλύουν προβλήματα αρχικών τιμών πρώτης και δεύτερης τάξης (όλα τα άλλα προβλήματα ανάγονται σε αυτά). Δύο μεγάλες ομάδες μεθόδων επίλυσης διαφορικών εξισώσεων είναι οι μέθοδοι απλού βήματος και οι πολυβηματικές μέθοδοι (Multistep methods). Υπάρχουν αρκετές μέθοδοι απλού βήματος. Μεταξύ αυτών είναι και οι μέθοδοι Runge Kutta και Runge Kutta Nystrom. Η μεγάλη ακρίβεια και η ευκολία εφαρμογής των αλγορίθμων Runge-Kutta και Runge Kutta Nystrom τις κατατάσσουν στις πιο εύχρηστες και δημοφιλείς μεθόδους επίλυσης προβλημάτων.
description: A lot of natural phenomena are described mathematically by differential equations ordinary differential equations or partial differential equations. Unfortunately few differential equations are solved analytically for this reason from the beginning of century became efforts in order to found numerical methods for the solution of differential equations. The main part of research in the numerical solution of differential equations began from the creation of first computers. The numerical solution of differential equations consists of the construction of algorithms and in continuation their realization with computational PC. Big part of research in the applied mathematics constitutes the construction of such algorithms. The numerical methods of solving ordinary differential equations which solve problems with initial conditions first and second order (all the other problems are reduced in such problems). Two big categories of methods for the solution of differential equations are the methods of simple step and the Multistep methods. There are several single steps methods. Among them are the methods of Runge Kutta and Runge Kutta Nystrom. The big precision and the facility of application of algorithms Runge-Kutta and Runge Kutta Nystrom classify them in the most useful and popular methods of solving such problems.