cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
On the evaluation of two-loop electroweak box diagrams for $e^+e^- \to HZ$ production
Creators: name: Song, Qian
name: Freitas, Ayres
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Precision studies of the Higgs boson at future $e^+e^-$ colliders can help to shed light on fundamental questions related to electroweak symmetry breaking, baryogenesis, the hierarchy problem, and dark matter. The main production process, $e^+e^- \to HZ$, will need to be controlled with sub-percent precision, which requires the inclusion of next-to-next-to-leading order (NNLO) electroweak corrections. The most challenging class of diagrams are planar and non-planar double-box topologies with multiple massive propagators in the loops. This article proposes a technique for computing these diagrams numerically, by transforming one of the sub-loops through the use of Feynman parameters and a dispersion relation, while standard one-loop formulae can be used for the other sub-loop. This approach can be extended to deal with tensor integrals. The resulting numerical integrals can be evaluated in minutes on a single CPU core, to achieve about 0.1% relative precision.
description: 16 pages, 4 figures and 1 table
Magnetic quadri-dipolar stars rotating in vacuum
Creators: name: Pétri, J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Main sequence stars and compact objects like white dwarfs and neutron stars are usually embedded in magnetic fields that strongly deviate from a pure dipole located right at the stellar centre. An off-centred dipole can sometimes better adjust existing data and offer a simple geometric picture to include multipolar fields. However, such configurations are usually to restrictive, limiting multipolar components to strength less than the underlying dipole. In this paper, we consider the most general lowest order multipolar combination given by a dipole and a quadrupole magnetic field association in vacuum. Following the general formalism for multipolar field computations, we derive the full electromagnetic field outside a rotating quadridipole. Exact analytical expressions for the Poynting flux and the electromagnetic kick are given. Such geometry is useful to study the magnetosphere of neutron stars for which more and more compelling observations reveals hints for at least quadridipolar fields. We also show that for sufficiently high quadrupole components at the stellar surface, the electromagnetic kick imprinted to a neutron star can reach thousands of km/s for a millisecond period at birth.
description: 11 pages, 15 figures, accepted for publication in MNRAS
Measurement of the Scintillation Efficiency of Na Recoils in NaI(Tl) down to 10 keV Nuclear Recoil Energy relevant to Dark Matter Searches
Creators: name: Chagani, H.
name: Majewski, P.
name: Daw, E. J.
name: Kudryavtsev, V. A.
name: Spooner, N. J. C.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: We present preliminary results of measurements of the quenching factor for Na recoils in NaI(Tl) at room temperature, made at a dedicated neutron facility at the University of Sheffield. Measurements have been performed with a 2.45 MeV mono-energetic neutron generator in the energy range from 10 keV to 100 keV nuclear recoil energy. A BC501A liquid scintillator detector was used to tag neutrons. Cuts on pulse-shape discrimination from the BC501A liquid scintillator detector and neutron time-of-flight were performed on pulses recorded by a digitizer with a 2 ns sampling time. Measured quenching factors range from 19% to 26%, in agreement with other experiments. From pulse-shape analysis, a mean time of pulses from electron and nuclear recoils are compared down to 2 keV electron equivalent energy.
description: to appear in Proc. 6th Int. Workshop on the Identification of Dark Matter, 11-16 September 2006, Rhodes, Greece; 6 pages, 4 figures; corrected preliminary theoretical estimation curve plotted in figure 4
Proposal for a loophole-free Bell test with electron spins of donors
Creators: name: Hong, Fang-Yu
name: Xiong, Shi-Jie
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: So far, all experimental tests of Bell inequalities which must be satisfied by all local realistic hidden-variable theories and are violated by quantum mechanical predictions have left at least one loophole open. We propose a feasible setup allowing for a loophole-free test of the Bell inequalities. Two electron spin qubits of phosphorus donors in semiconductors in different cavities 300 m apart are entangled through a bright coherent light and postselections using homodyne measurements. The electron spins are then read out randomly and independently by Alice and Bob, respectively, with unity efficiency in less than 0.7$μ$s by using optically induced spin to charge transduction detected by radio-frequency single electron transistor. A violation of Bell inequality larger than 37% and 18% is achievable provided that the detection accuracy is 0.99 and 0.95, respectively.
description: 4 pages,4 figures
Structural Motifs and Bonding in Two Families of Boron Structures Predicted at Megabar Pressures
Creators: name: Hilleke, Katerina P.
name: Zurek, Eva
name: Ogitsu, Tadashi
name: Zhang, Shuai
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The complex crystal chemistry of elemental boron has led to numerous proposed structures with distinctive motifs as well as contradictory findings. Herein, evolutionary structure searches performed at 100 GPa have uncovered a series of potential new metastable phases of boron, and bonding analyses were carried out to elucidate their electronic structure. These polymorphs, dynamically stable at 100 GPa, were grouped into two families. The first was derived from the thermodynamic minimum at these conditions, $α$-Ga, whereas channels comprised the second. Two additional intergrowth structures were uncovered, and it was shown they could be constructed by stacking layers of $α$-Ga-like and channel-like allotropes on top of each other. A detailed bonding analysis revealed networks of four-center $σ$-bonding functions linked by two-center B-B bonds in the $α$-Ga based structures, and networks that were largely composed of three-center $σ$-bonding functions in the channel-based structures. Seven of these high pressure phases were found to be metastable at atmospheric conditions, and their Vickers hardnesses were estimated to be $\sim$36 GPa.
description: 14 pages, 12 figures, 3 tables
Reversals in nature and the nature of reversals
Creators: name: Stefani, Frank
name: Xu, Mingtian
name: Sorriso-Valvo, Luca
name: Gerbeth, Gunter
name: Günther, Uwe
Publisher: name: arXiv
Year: 2007
Subjects: subject: Geophysics (physics.geo-ph)
subject: Astrophysics (astro-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: The asymmetric shape of reversals of the Earth's magnetic field indicates a possible connection with relaxation oscillations as they were early discussed by van der Pol. A simple mean-field dynamo model with a spherically symmetric $α$ coefficient is analysed with view on this similarity, and a comparison of the time series and the phase space trajectories with those of paleomagnetic measurements is carried out. For highly supercritical dynamos a very good agreement with the data is achieved. Deviations of numerical reversal sequences from Poisson statistics are analysed and compared with paleomagnetic data. The role of the inner core is discussed in a spectral theoretical context and arguments and numerical evidence is compiled that the growth of the inner core might be important for the long term changes of the reversal rate and the occurrence of superchrons.
description: 24 pages, 12 figures
BRST Invariance of Non-local Charges and Monodromy Matrix of Bosonic String on AdS(5)xS(5)
Creators: name: Kluson, J.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Using the generalized Hamiltonian method of Batalin, Fradkin and Vilkovsky we develop the BRST formalism for the bosonic string on AdS(5)xS(5) formulated as principal chiral model. Then we show that the monodromy matrix and non-local charges are BRST invariant.
description: 26. pages
Ποιότητα ζωής εφήβων και νέων με νοητική ανεπάρκεια: οι αντιλήψεις των εργαζομένων.:
Creators: name: Πισσανίδου, Ολγα ΝΙκολάου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Νοητική Ανεπάρκεια
Ποιότητα ζωής
Αυτοπροσδιορισμός
Intellectual Disabilities
Quality of life
Self Determination

description: Η ποιότητα ζωής αποτελεί μία έννοια που σχετίζεται με την το πώς το άτομο αντιλαμβάνεται και επιθυμεί να κατευθύνει τη ζωή του. Η έννοια της ποιότητας ζωής στα άτομα με νοητική ανεπάρκεια, σχετίζεται με την προσπάθεια που κάνουν τα άτομα αυτά να θεωρούνται αυτόνομο σύστημα, να αυτό-οργανώνονται, να προσανατολίζονται σε προσωπικά τους προβλήματα και να αποβλέπουν στην αυτό-βελτίωση της κατάστασής τους. Στην παρούσα έρευνα διερευνάται η ποιότητας ζωής των νέων και εφήβων με νοητική ανεπάρκεια που φοιτούν σε ειδικά σχολεία. Η παρούσα διατριβή χωρίζεται σε δύο μέρη. Στο πρώτο μέρος (θεωρητικό), γίνεται ανάλυση βασικών εννοιών σχετικών με τη διατριβή, όπως νοητική ανεπάρκεια, ποιότητα ζωής και αυτοπροσδιορισμός. Στο δεύτερο μέρος (ερευνητικό), παρουσιάζονται η μεθοδολογία της έρευνας, τα ευρήματα και τα συμπεράσματα. Η έρευνα αφορούσε 95 μαθητές με νοητική ανεπάρκεια, οι οποίοι φοιτούσαν σε ειδικά σχολεία δευτεροβάθμιας εκπαίδευσης. Η διεξαγωγή της έρευνας πραγματοποιήθηκε με χρήση ερωτηματολογίων, τα οποία συμπληρώθηκαν από ψυχολόγους, κοινωνικούς λειτουργούς, εκπαιδευτικούς και διευθυντές που εργάζονταν στα σχολεία αυτά. Η διατριβή κλείνει με την παρουσίαση των ευρημάτων και τη συζήτηση των αποτελεσμάτων – συμπεράσματα, όπου διαφαίνεται πως οι νέοι και έφηβοι με νοητική ανεπάρκεια παρουσιάζουν μέτρια έως χαμηλά επίπεδα ποιότητας ζωής.
description: The quality of life is a concept that relates to how a person perceives and wants to direct his life. The concept of quality of life, in people with intellectual disabilities, is associated with the effort to make these people to be considered as an autonomous system, to self-organize themselves, to be oriented to their personal problems and to seek self-improvement in their condition. The present research investigates the quality of life of young people and adolescents with intellectual disabilities who attend special schools. The thesis is divided into two parts. The first part (theoretical) analyzes the relevant key concepts to the thesis, such as intellectual disabilities, quality of life and self-determination. The second part (research), presents the research methodology, findings and conclusions. The research involved 95 students with intellectual disabilities who attend special schools of secondary education. The conduction of the research was carried out using questionnaires, which were completed by psychologists, social workers, teachers and principals working in these schools. The thesis concludes with the presentation of findings and the discussion of results - findings which show that young people and adolescents with intellectual disabilities exhibit moderate to low quality of life.
Μεσαιωνικά μοτίβα στη σύγχρονη σερβική πεζογραφία: Η περίπτωση της Λιλιάνα Χαμπιάνοβιτς Τζούροβιτς.:
Creators: name: Καζαντσίδης, Γεώργιος Κυριάκου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Λιλιάνα Χαμπιάνοβιτς Τζούροβιτς
Σύγχρονη σερβική λογοτεχνία.
Σερβική λογοτεχνία και μεσαιωνική ιστορία.
Ljiljana Hambjanovic Dzurovic
Contemporary serbian literature
Serbian literature and mediaval history

description: Η μεταπτυχιακή εργασία με τίτλο «Μεσαιωνικά μοτίβα στη σύγχρονη σερβική λογοτεχνία – η περίπτωση της Λίλιανα Χαμπιάνοβιτς Τζούροβιτς» έχει ως αντικείμενο την έρευνα του φαινομένου που παρατηρείται τις δύο τελευταίες δεκαετίες στις λογοτεχνίες των χωρών της Βαλκανικής χερσονήσου και ιδιαίτερα στη Σερβία όπου τα θέματα αντλούνται από τη μεσαιωνική ιστορία των λαών. Ερευνάει τις συγκυρίες που οδήγησαν στην ξαφνική αλλαγή της θεματολογίας του σοσιαλιστικού ρεαλισμού που επικρατούσε ως τότε στην θεολογική και μεσαιωνική θεματολογία. Γίνεται μια προσέγγιση στην σχέση της μεσαιωνικής – βυζαντινής ιστορίας και πολιτισμού με το Σερβικό λαό και τις επιπτώσεις που είχε σ’ αυτούς. Ακολουθεί η παρουσίαση των θεμάτων που κυριαρχούσαν ως την «πτώση του τοίχους» και του υπαρκτού σοσιαλισμού. Εν συνεχεία ακολουθεί η έρευνα της σύγχρονης λογοτεχνίας στην οποία όπως προαναφέρθηκε παρουσιάζεται έντονο το στοιχείο του μεσαίωνα και του χριστιανισμού. Ιδιαίτερη θέση στους Σέρβους λογοτέχνες κατέχει η Λίλιανα Χαμπιάνοβιτς Τζούροβιτς. Επιχειρείται στη συνέχεια η παρουσίαση των ως τώρα έργων της με τα παραπάνω χαρακτηριστικά. Τα έργα της συγγραφέως αυτής γνώρισαν μεγάλη επιτυχία έχουν γίνει best selers αλλά επίσης μεταφράστηκαν σε δώδεκα γλώσσες μεταξύ των άλλων και στην ελληνική και έχουν τύχη της ανάλογης αποδοχή από το αναγνωστικό κοινό.
description: The postgraduate research work entitled " Medieval motives in modern Serbian literature -- the case of Djurovic-Habjanovic Ljiljana " aims to investigate the tendency which is observed in the last two decades in the literature of the Balkan countries and especially in Serbia,where the topics are derived from the medieval history of the nations. The research work examines the coincidences which led in the sudden change of the thematology of socialistic realism which dominated until then in the theological and medieval themes. There is an attempt to approach the relation between the medieval-byzantine history and civilization with the Serbian people and the consequences resulted upon them. Then follows the presentation of the themes which prevailed until the "Fall of the Berlin wall" and the existing socialism. Subsequently follows the search of modern literature in which,as mentioned,there is a strong element of the middle ages and christianity. Among the Serbian literature writers,prominent position holds Djurovic-Habjanovic Ljiljana. Then, there is an attempt to present her up to date works with the above characteristics.These works have been a great success,they became best-sellers, and also they have been translated in twelve languages,among them Greek,and they have been successfully received by the reading public
A Near-Infrared Study of 2MASS Bars in Local Galaxies: An Anchor for High Redshift Studies
Creators: name: Menendez-Delmestre, Karin
name: Sheth, Kartik
name: Schinnerer, Eva
name: Jarrett, Thomas H.
name: Scoville, Nick Z.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have measured the fraction of bars in nearby spiral galaxies using near-infrared J, H, and K_s images of 151 spiral galaxies from 2MASS. This local sample provides an anchor for the study of the evolution of the bar fraction and bar properties with redshift. We identify bars by analyzing the full two-dimensional light distribution and requiring a combined ellipticity and position angle signature. The combined bar signature is found in 59% of the galaxies. The bar fraction increases to 67% when we include "candidate" bars, where only the ellipticity signature is present. We also measure the change in the bar fraction as a function of bar size; the bar fraction drops to 36% for bars with a semi-major axis larger than 4 kpc. We find that infrared bars typically extend to one-third of the galactic disk, with a deprojected relative size of ~ 0.3 +/- 0.2. Early-type spirals host significantly larger bars, consistent with earlier studies. The is two times larger in early-types than in late-types. The typical bar axial ratio (b/a) is \~0.5, with a weak trend of higher axial ratios for larger bars.
description: Accepted to ApJ, 15 pages; for high resolution version go to http://www.astro.caltech.edu/~km/2MASSbars/
Στρατηγικές κατανόησης και παραγωγής γραπτού λόγου στο μάθημα των Λατινικών και Μαθησιακές Δυσκολίες:
Creators: name: Πλατιώτη, Αλεξάνδρα Αντωνίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Στρατηγικές
Μαθησιακές Δυσκολίες
Μάθημα Λατινικών
Strategies
Learning Difficulties
Learning Latin

description: Η παρούσα εργασία αποτελεί μία απόπειρα προσέγγισης του μαθήματος των Λατινικών με βασικό έρεισμα στους εξής δύο στοιχειώδεις άξονες: 1) στρατηγικές κατανόησης και παραγωγής γραπτού λόγου και 2) μαθησιακές δυσκολίες. Ειδικότερα, μελετάται ο τρόπος με τον οποίο εμφανίζονται οι μαθησιακές δυσκολίες στο συγκεκριμένο γνωστικό αντικείμενο, το οποίο θα ιδωθεί ως μία δεύτερη / ξένη γλώσσα, που καλούνται οι μαθητές να αφομοιώσουν, με απώτερο σκοπό την εισαγωγή τους στα ιδρύματα της Ανώτερης και Ανώτατης εκπαίδευσης. Στο θεωρητικό πλαίσιο επιχειρείται μια ανασκόπηση της βιβλιογραφίας γύρω από το θέμα που επιχειρεί να διαπραγματευτεί η εργασία, και, κατόπιν, παρουσιάζονται τα χαρακτηριστικά της γλώσσας γενικά και οι παράγοντες που επηρεάζουν την εκμάθηση μιας δεύτερης / ξένης γλώσσας ειδικά. Ακολουθεί εκτενής αναφορά αφενός στα χαρακτηριστικά της κατανόησης και της παραγωγής γραπτού λόγου, αφετέρου στις στρατηγικές που απαιτούνται για τις δύο αυτές δραστηριότητες. Τέλος, αναλύονται τα πορίσματα της έρευνας και διατυπώνονται τα καίριας σημασίας συμπέρασματα που αναδύθηκαν.
description: The present work is an attempt to approach the course with basic Latin basis on the following two basic principles: 1) comprehension strategies and writing skills and 2) learning difficulties. In particular, it examines the way in which learning disabilities occur in a particular subject, which will be seen as a second / foreign language, invited students to digest, with a view to admission to institutions of higher education. The theoretical framework is an attempt to review the literature on the topic attempts to negotiate the work, and then presents the characteristics of the language in general and the factors that affect the learning of a second / foreign language in particular. Below is a comprehensive reference to the characteristics of both comprehension and writing skills, other strategies are required for these two activities. Finally, the paper analyzes the results of the research and the key conclusions that emerged.
MPEC 2024-C100 : 2024 CS1
Creators: name: Minor Planet Center Staff
Publisher: name: The Minor Planet Center
Year: 2024
Subjects: subject: Small Solar System bodies
valueUri: http://astrothesaurus.org/uat/1469
subject: 2024 CS1

description: The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements.  They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Renormalization group study of systems with quadratic band touching
Creators: name: Shah, Jeet
name: Mukerjee, Subroto
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Lifshitz transitions in two 2D systems with a single quadratic band touching point as the chemical potential is varied have been studied here. The effects of interactions have been studied using the renormalization group (RG) and it is found that at the transition a repulsive interaction is marginally relevant and an attractive interaction is marginally irrelevant. We corroborate the results obtained from the RG calculation by studying a microscopic model whose ground state and Green's functions can be obtained exactly. We find that away from the transition, the system displays an instability towards forming and excitonic condensate.
description: 12 pages, 6 figures
Teacher discourse in collaborative action research : a case study of professional and curriculum development
Creators: name: Arndt, Kerrylou Richardson
Publisher: name: University of British Columbia
Year: 2009

description: The directive for "action" to sustain the quality of human life parallels "action research" in education to improve the quality of learning experiences in schools. The purpose of the study was to provide insight and understanding into the features of a team of intermediate teachers interacting in the development of a school-based curriculum project, the Winter Studies Program, in support of environmental education. The case study is an analysis of teacher discourse. It had the aims of: one, illuminating the dynamic features of dialogue that characterized teacher interactions and the processes of change in curriculum development; two, examining the support system and organizational structures that enabled change; and three, reflecting on collaborative action research as a process for professional development. Within a framework of systematic inquiry, data collection included video and audio recordings of teacher team meetings, fieldnotes, and reflection journals. The findings suggest that teacher discourse is characterized by three dynamic features: commonality of understanding of praxis, narratives of experience, and tension. In the establishment of a Professional Support Group teachers interact collaboratively to develop curriculum and in so doing, develop professionally. A support system, inclusive of organizational structures, creates opportunities for change. The study concludes that action research empowers individuals, through reflective inquiry, to change their praxis or the structures that influence their praxis.
Year-Round Forage Production for Sustainable Goat Farming
Creators: name: Karki, Uma
name: Karki, Uma
Publisher: name: Unknown
Year: 2020
Subjects: subject: Farm Management
subject: Livestock Production/Industries
subject: Year-Round Forage Production
subject: Forage Production
subject: Sustainable Goat Farming
subject: Sustainable Farming
subject: Grazing

description: Goat farming in the U.S. is based on grazing lands. Forages available for grazing throughout most of the year are essential for supplying required nutrition for goats and minimizing production costs. Most goat farmers do not have pastures productive for an extended period. This situation results in poor performing animals and high production costs. Forage availability can improve by enhancing the productivity, quality, and production duration of pastures. The inclusion of browse species in grazing systems will also improve diet variety, minimize internal parasite problems, and better utilize the soil resources. Grazing opportunity can be extended by developing a woodland grazing system. Farmers can consider establishing a silvopasture system after the first and second thinning of forests or plantations by growing suitable forages and/or combinations in spaces between trees. Such operations diversify farmers’ income opportunities and increase environmental quality and social acceptance of land resources.
Filling the Black Hole Mass Gap: Avoiding Pair Instability in Massive Stars through Addition of Non-Nuclear Energy
Creators: name: Ziegler, Joshua
name: Freese, Katherine
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: In standard stellar evolution, stars with masses ranging from approximately $150$ to $240 M_\odot$ are expected to evolve to a pair instability supernova with no black hole (BH) remnant. This evolutionary behavior leads to a predicted gap in the black hole mass function from approximately $50$ to $140 M_\odot$. Yet the LIGO and Virgo Collaborations[1] recently discovered black holes of masses $66 M_\odot$ and $85 M_\odot$ in the gravitational wave event GW190521. We propose a new method to populate the BH mass gap. If an energy source is added throughout the star in addition to nuclear fusion, it is possible for the altered evolution to avoid the complete destruction of a pair instability supernova, and instead a BH remnant is left behind. An example of an extra energy source is dark matter annihilation within the star, but our results hold more generally. We show this phenomenon by exploring the effect of adding an energy source independent of temperature and density to a $180 M_\odot$ star, using the MESA one-dimensional stellar evolution software. If $\sim50$\% of the star's energy is due to this new source, the star is capable of avoiding the pair instability entirely and evolving towards a core-collapse supernova and ultimately a BH remnant with mass $\sim 120 M_\odot$.
description: 20 pages, 9 figures, 2 tables
Non-Singular Bouncing Universes in Loop Quantum Cosmology
Creators: name: Singh, Parampreet
name: Vandersloot, Kevin
name: Vereshchagin, G. V.
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Non-perturbative quantum geometric effects in Loop Quantum Cosmology predict a $ρ^2$ modification to the Friedmann equation at high energies. The quadratic term is negative definite and can lead to generic bounces when the matter energy density becomes equal to a critical value of the order of the Planck density. The non-singular bounce is achieved for arbitrary matter without violation of positive energy conditions. By performing a qualitative analysis we explore the nature of the bounce for inflationary and Cyclic model potentials. For the former we show that inflationary trajectories are attractors of the dynamics after the bounce implying that inflation can be harmoniously embedded in LQC. For the latter difficulties associated with singularities in cyclic models can be overcome. We show that non-singular cyclic models can be constructed with a small variation in the original Cyclic model potential by making it slightly positive in the regime where scalar field is negative.
description: Minor changes and one figure added to improve presentation. References added. To appear in Physical Review D
Scipp: Scientific data handling with labeled multi-dimensional arrays for C++ and Python
Creators: name: Heybrock, Simon
name: Arnold, Owen
name: Gudich, Igor
name: Nixon, Daniel
name: Vaytet, Neil
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mathematical Software (cs.MS)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Scipp is heavily inspired by the Python library xarray. It enriches raw NumPy-like multi-dimensional arrays of data by adding named dimensions and associated coordinates. Multiple arrays are combined into datasets. On top of this, scipp introduces (i) implicit handling of physical units, (ii) implicit propagation of uncertainties, (iii) support for histograms, i.e., bin-edge coordinate axes, which exceed the data's dimension extent by one, and (iv) support for event data. In conjunction these features enable a more natural and more concise user experience. The combination of named dimensions, coordinates, and units helps to drastically reduce the risk for programming errors. The core of scipp is written in C++ to open opportunities for performance improvements that a Python-based solution would not allow for. On top of the C++ core, scipp's Python components provide functionality for plotting and content representations, e.g., for use in Jupyter Notebooks. While none of scipp's concepts in isolation is novel per-se, we are not aware of any project combining all of these aspects in a single coherent software package.
description: Proceedings of ICANS-XXIII, 13 pages, 5 figures
Helical Symmetry in Linear Systems
Creators: name: Bicak, Jiri
name: Schmidt, Bernd G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate properties of solutions of the scalar wave equation and Maxwell's equations on Minkowski space with helical symmetry. Existence of local and global solutions with this symmetry is demonstrated with and without sources. The asymptotic properties of the solutions are analyzed. We show that the Newman--Penrose retarded and advanced scalars exhibit specific symmetries and generalized peeling properties.
description: 11 pages
Wireless Power Transfer with Distributed Antennas: System Design, Prototype, and Experiments
Creators: name: Shen, Shanpu
name: Kim, Junghoon
name: Song, Chaoyun
name: Clerckx, Bruno
Publisher: name: arXiv
Year: 2020
Subjects: subject: Signal Processing (eess.SP)
subject: Information Theory (cs.IT)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: In this paper, we design and experiment a far-field wireless power transfer (WPT) architecture based on distributed antennas, so-called WPT DAS, that dynamically selects transmit antenna and frequency to increase the output dc power. Uniquely, spatial and frequency diversities are jointly exploited in the proposed WPT DAS with low complexity, low cost, and flexible deployment to combat the wireless fading channel. A numerical experiment is designed to show the benefits using antenna and frequency selections in spatially and frequency selective fading channels for single-user and multi-user cases. Accordingly, the proposed WPT DAS for single-user and two-user cases is prototyped. At the transmitter, we adopt antenna selection to exploit spatial diversity and adopt frequency selection to exploit frequency diversity. A low-complexity over-the-air limited feedback using an IEEE 802.15.4 RF interface is designed for antenna and frequency selections and reporting from the receiver to the transmitter. The proposed WPT DAS prototype is demonstrated in a real indoor environment. The measurements show that WPT DAS can boost the output dc power by up to 30 dB in single-user case and boost the sum of output dc power by up to 21.8 dB in two-user case and broaden the service coverage area in a low cost, low complexity, and flexible manner.
Predicting the flow field in a U-bend with deep neural networks
Creators: name: Hajgató, Gergely
name: Gyires-Tóth, Bálint
name: Paál, György
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (cs.LG)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: This paper describes a study based on computational fluid dynamics (CFD) and deep neural networks that focusing on predicting the flow field in differently distorted U-shaped pipes. The main motivation of this work was to get an insight about the justification of the deep learning paradigm in hydrodynamic hull optimisation processes that heavily depend on computing turbulent flow fields and that could be accelerated with models like the one presented. The speed-up can be even several orders of magnitude by surrogating the CFD model with a deep convolutional neural network. An automated geometry creation and evaluation process was set up to generate differently shaped two-dimensional U-bends and to carry out CFD simulation on them. This process resulted in a database with different geometries and the corresponding flow fields (2-dimensional velocity distribution), both represented on 128x128 equidistant grids. This database was used to train an encoder-decoder style deep convolutional neural network to predict the velocity distribution from the geometry. The effect of two different representations of the geometry (binary image and signed distance function) on the predictions was examined, both models gave acceptable predictions with a speed-up of two orders of magnitude.
description: Conference paper, 8 pages, 10 figures
Αναγνώριση κινήσεων και χειρονομιών από δεδομένα βάθους σε πραγματικό χρόνο:
Creators: name: Μαδεμλής, Ιωάννης Βασιλείου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Αναγνώριση κίνησης
Δεδομένα βάθους
Πραγματικού χρόνου
Activity recognition
Depth data
Real-time

description: Στην εργασία αυτή διερευνάται η εφαρμογή ενός στατιστικού ταξινομητή σε προβλήματα αναγνώρισης κινήσεων και χειρονομιών σε πραγματικό χρόνο, αξιοποιώντας δεδομένα βίντεο παρεχόμενα από αισθητήρες βάθους (αλληλουχίες από καρέ βάθους). Δεδομένα τέτοιου τύπου προσφέρουν πληροφορίες για τη γεωμετρία επιφάνειας του εικονιζόμενου ανθρώπινου υποκειμένου. Για την ταξινόμηση χρησιμοποιείται ο αλγόριθμος PREMONN (Predictive Modular Neural Network), ο οποίος επιτρέπει on-line λειτουργία αναγνώρισης, ενώ για την εξαγωγή χαρακτηριστικών από τα δεδομένα βάθους υπολογίζεται ένα κινούμενο νέφος τριδιάστατων σημείων για κάθε ζεύγος διαδοχικών καρέ. Στο νέφος αυτό εφαρμόζεται Ανάλυση Κυρίων Συνιστωσών (PCA) και ως χαρακτηριστικά περιγραφής του καρέ αξιοποιούνται οι προκύπτουσες κύριες συνιστώσες της τρέχουσας κίνησης, από κοινού με μία συμπαγή στατιστική σύνοψη του αντίστοιχου καρέ βάθους. Η μικρή διάσταση και ο ταχύς υπολογισμός του διανύσματος χαρακτηριστικών επιτρέπουν την αναγνώριση κινήσεων και χειρονομιών σε πραγματικό χρόνο.
description: In this thesis the application of a statistical classifier is studied, regarding the problem of recognizing human activities and gestures in real-time by exploiting video data coming from depth sensors (depth frame sequences). Such data provide information about the surface geometry of the pictured human subject. The algorithm PREMONN (Predictive Modular Neural Network), which may be used for timeseries recognition in on-line mode, is employed as classifier, while the necessary feature extraction from the depth data is performed by computing a moving 3-dimensional point cloud for every pair of consecutive frames. Principal Component Analysis (PCA) is applied on this cloud and the resultant current motion principal components, as well as a compact statistical summary of the corresponding depth frame, are used as features for frame description. The low dimensionality and the rapid computation of the feature vector permit activity and gesture recognition in real-time.
Literature research about Denial of Service attacks: Comparison of different modes of DoS attacks, Analysis of DoS defense schemes in information system environments and networks and Overview of secur:
Creators: name: Ζλάτης, Χρήστος Ιωάννη
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: DDoS επιθέσεις
Μηχανισμοί άμυνας DDoS επιθέσεων
Αρχές ασφαλείας
Denial of service attacks
DDoS defense schemes
Security principles

description: Σκοπός της διπλωματικής ήταν η μελέτη των διαδικτυακών επιθέσεων DoS και DDoS, η λεπτομερής παρουσίαση των διαφόρων μορφών τους καθώς και η μελέτη των επιδράσεων τις οποίες μπορούν να δημιουργήσουν σε επιχειρησιακά περιβάλλοντα. Πιο συγκεκριμένα, αρχικά παρουσιάσαμε τις βασικές μορφές επιθέσεων δικτύου. Στη συνέχεια κάναμε μια αναλυτική περιγραφή των διαφόρων ειδών επιθέσεων DoS και DDoS και μελετήσαμε διάφορους μηχανισμούς επίθεσης και άμυνας σε πληροφοριακά συστήματα και δίκτυα. Στη συνέχεια αναφερθήκαμε στις κύριες πολιτικές ασφαλείας για την αποτροπή και αντιμετώπιση τέτοιου είδους επιθέσεων. Παρουσιάσαμε στατιστικές προσεγγίσεις σχετικά με τη μελέτη και πρόληψη διαδικτυακών επιθέσεων και στο τέλος της εργασίας αναφερθήκαμε σε πρόσφατες μελέτες και έρευνες σχετικά με την επίδραση των διαδικτιακών επιθέσεων DoS σε επιχειρηματικά περιβάλλοντα και στο διαδίκτυο γενικότερα.
description: The aim of the thesis was to study the DoS s and DDoS attacks with a detailed presentation of the various forms of these attacks and the study of the effects which they can have in business environments. More specifically, firstly we presented the basic forms of network attacks. Then, we made a detailed description of the various types of DoS and DDoS attacks and we studied various mechanisms of attack and defense schemes in information systems and networks. Also, we discussed the main security principles to prevent and counter such kind of attacks. We presented statistical approaches to the study and prevention of DDoS attacks and after that we referred to recent studies and research on the impact of DDoS attacks in business environments and the web in general.
Spin-chirality decoupling in Heisenberg spin glasses and related systems
Creators: name: Kawamura, Hikaru
Publisher: name: arXiv
Year: 2006
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: Recent studies on the spin and the chirality orderings of the three-dimensional Heisenberg spin glass and related systems are reviewed with particular emphasis on the possible spin-chirality decoupling phenomena. Chirality scenario of real spin-glass transition and its experimental consequence on the ordering of Heisenberg-like spin glasses are discussed.
description: An invited paper of the ICM2006 conference. To appear in J. Mag. Mag. Mater
On the validity of entropy production principles for linear electrical circuits
Creators: name: Bruers, Stijn
name: Maes, Christian
name: Netocny, Karel
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We discuss the validity of close-to-equilibrium entropy production principles in the context of linear electrical circuits. Both the minimum and the maximum entropy production principle are understood within dynamical fluctuation theory. The starting point are Langevin equations obtained by combining Kirchoff's laws with a Johnson-Nyquist noise at each dissipative element in the circuit. The main observation is that the fluctuation functional for time averages, that can be read off from the path-space action, is in first order around equilibrium given by an entropy production rate. That allows to understand beyond the schemes of irreversible thermodynamics (1) the validity of the least dissipation, the minimum entropy production, and the maximum entropy production principles close to equilibrium; (2) the role of the observables' parity under time-reversal and, in particular, the origin of Landauer's counterexample (1975) from the fact that the fluctuating observable there is odd under time-reversal; (3) the critical remark of Jaynes (1980) concerning the apparent inappropriateness of entropy production principles in temperature-inhomogeneous circuits.
description: 19 pages, 1 fig
Form-function relations in student discourse contextualized by classroom language activities : a case study of an elementary Chinese as a foreign language program
Creators: name: Huang, Jingzi
Publisher: name: University of British Columbia
Year: 2009

description: Recent studies in language education have advocated the integration of language and content learning, assuming that classroom discourse will display appropriate formfunction relations. But Swain (1988) reveals that even good content teaching may result in classroom discourse where form-function relations are neither appropriate nor transparent, and calls for intentional teacher planning of classroom activities. Thus major areas for research are intentional planning for integration and functional discourse analysis. Approaches to the form-function analysis of discourse include register (Halliday 1985), genre (Martin 1992) and knowledge structures (Mohan 1990). All three provide a theoretical basis for functional discourse analysis and intentional planning. In this qualitative, eight-month study of Chinese as a foreign language and culture class for beginning elementary anglophone students, the teachers designed student tasks around knowledge structures, using graphic representations to mediate between language and content. Data included lesson plans, informal interviews, field notes, and discourse data from student interactions and written work. The discourse was analyzed lexicogrammatically with a view to form-function relations, particularly the formal realizations of knowledge structures. Major questions were: how were foreign language teaching and cultural learning intentionally organized around knowledge structures at the level of both curriculum design and classroom implementation? What systematic formfunction relations appeared in the discourse data. How are knowledge structures formally realized in the interactions and written work of young foreign language learners? The results throw light on the possibilities of systematic form-function relations in the classroom, the integration of language and content learning, and on further directions for intentional planning.
On a Brownian motion conditioned to stay in an open set
Creators: name: Riabov, Georgii V.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics

description: Distribution of a Brownian motion conditioned to start from the boundary of an open set $G$ and to stay in $G$ for a finite period of time is studied. Characterizations of such distributions in terms of certain singular stochastic differential equations are obtained. Results are applied to the study of boundaries of clusters in some coalescing stochastic flows on $\mathbb{R}.$
Disc light variability in the FUor star V646 Puppis as observed by TESS and from the ground
Creators: name: Siwak, Michał
name: Ogłoza, Waldemar
name: Krzesiński, Jerzy
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We investigate small-scale light variations in V646 Pup occurring on different timescales with the aim to investigate whether this variability is similar to that observed in FU Ori. We observed V646 Pup at the SAAO and CTIO between 2013 and 2018 with Johnson and Sloan filters, typically using a one-day cadence maintained for 1-4 weeks. We also utilised the public-domain 1512-day-long ASAS-SN light curve and TESS photometry obtained in 2019 over 24.1 days with a 30 min cadence. New SAAO low-resolution spectra assist in updating major disc parameters, while the archival high-resolution Keck spectra are used to search for temporal changes in the disc rotational profiles. The ground-based observations confirm the constantly decreasing brightness of V646 Pup at the rate of 0.018 mag/yr. Precise TESS data show that the slight, 0.005-0.01 mag, light variations imposed on this general trend do consist of a few independent wave trains of an apparently time-coherent nature. Assuming that this is typical situation, based on an analysis of colour-magnitude diagrams obtained for earlier epochs, we were able to make a preliminarily inference that the bulk of the light changes observed could be due to the rotation of disc photosphere inhomogeneities, arising between 10-12 solar radii from the star. We do not exclude the possibility that these inhomogeneities could also manifest themselves in the rotational profiles of the disc, as obtained from the high-resolution spectra. Assuming Keplerian rotation of these inhomogeneities, we give a preliminary determination of the stellar mass at 0.7-0.9 solar mass. These preliminary results are similar to those better established for FU Ori, which suggests a common driving mechanism(s).
description: Accepted by A&A
Monogamy and ground-state entanglement in highly connected systems
Creators: name: Ferraro, Alessandro
name: Garcia-Saez, Artur
name: Acin, Antonio
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We consider the ground-state entanglement in highly connected many-body systems, consisting of harmonic oscillators and spin-1/2 systems. Varying their degree of connectivity, we investigate the interplay between the enhancement of entanglement, due to connections, and its frustration, due to monogamy constraints. Remarkably, we see that in many situations the degree of entanglement in a highly connected system is essentially of the same order as in a low connected one. We also identify instances in which the entanglement decreases as the degree of connectivity increases.
description: 7 pages, 11 figures. Considerably extended version, with new numerical and analytical results
Influences on the practice of novice home economics teachers
Creators: name: Pelech, Judia
Publisher: name: University of British Columbia
Year: 2009

description: Feiman-Nemser and Floden (1986) described teacher socialization as learning to be a teacher and negotiating between idealism and what is possible in particular school settings. This study explored the influences of personal history and idealisms on novice home economics teachers' images of teaching. The second aspect of this study examined the ways in which these influences are recognized and negotiated in teaching practices. The research focus is of particular interest, because of the subject matter of home economics education. The home economics teacher enables students to define and solve problems within family dynamics and it is of interest to study whether the home economics teacher's personal history influences his or her practice of teaching. One first year teacher and three student teachers participated in this study. Life history and ethnographic interviewing were used to capture the stories of the subjects. The conversations were audiotaped and transcribed for analysis. Two central themes were elicited from analysis of the interviews. The themes centered on 1) personal history; and 2) being a good teacher. The theme on personal history included the areas of family, family dynamics and responsibility, and former teachers. The areas of family, former teachers, and being a good teacher were common influences to all four subjects. The area of responsibility applied to two of the subjects. The findings of this study indicate that people of significance, that is, parents, grandparents, siblings and former teachers, have some bearing on novice home economics teachers' images and practices of teaching. Although the novice teachers recognized these influences, they were not always comfortable with these influences on their teaching practices. Novice home economics teachers constantly strive within their practices to realize their ideals of teaching. These findings have implications in teacher education, classroom practice and for future research. Curriculum and instruction courses in teacher education programs need to provide ways for prospective teachers to discuss and acknowledge and critically reflect on influences in their life histories which have led them to teaching and shaped their images of teaching and their teaching practice. It may be that family has been particularly influential in the lives of home economics teachers because it is also the subject matter they teach. Research with novice teachers in other subject area specializations could provide data to compare with the home economics teachers in this study.