cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Feedback from Clustered Sources During Reionization
Creators: name: Kramer, Roban Hultman
name: Haiman, Zoltan
name: Oh, S. Peng
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The reionization history of the intergalactic medium (IGM) at high redshift (z > 6) was likely strongly shaped by several global feedback processes. Because the earliest ionizing sources formed at the locations of the rare density peaks, their spatial distribution was strongly clustered. Here we demonstrate that this clustering significantly boosts the impact of feedback processes operating at high redshift. We build a semi-analytical model to include feedback and clustering simultaneously, and apply this model to the suppression of star-formation in minihalos due to photoionization. The model is built on the excursion-set-based formalism of Furlanetto, Zaldarriaga and Hernquist (2004), which incorporates the clustering of ionizing sources, and which we here extend to include suppression of star formation in minihalos. We find that clustering increases the mean HII bubble size by a factor of several, and it dramatically increases the fraction of minihalos that are suppressed, by a factor of up to 60 relative to a randomly distributed population. This enhanced suppression can significantly reduce the electron scattering optical depth, as required by the three-year data from the Wilkinson Microwave Anisotropy Probe (WMAP). We argue that source clustering is likely to similarly boost the importance of a variety of other feedback mechanisms.
description: submitted to ApJ, 9 emulateapj pages with 7 figures
Ανίχνευση και ποσδιορισμός αζωχρωμάτων και προϊόντων διάπλασης αυτών με ανάπτυξη ηλεκτροχημικής μεθόδου κατεργασίας αποβλήτων βαφείων και υφαντουργείων
Creators: name: Σακαλής, Αναστάσιος
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Sewage
Αζωχρώματα
Azodyes

description: Στόχος της διατριβής ήταν αρχικά η ανάπτυξη ηλεκτροχημικής μεθόδου κατεργασίας αποβλήτων βαφείων και υφαντουργείων που περιέχουν αζωχρώματα. Εν συνεχεια επιχειρήθηκε ο προσδιορισμός των αζωχρωμάτων και η ανίχνευση και ταυτοποίηση των προϊόντων διάσπασης κατά την ηλεκτροχημική κατεργασία. Η ηλεκτροχημική μέθοδος βασίστηκε στην ηλεκτρολυτική διάσπαση των χρωμάτων χρησιμοποιώντας κατάλληλα υλικά ως ηλεκτρόδια. Τα αρχικά αζωχρώματα προσδιορίζονται φωτομετρικά βολταμμετρικά. Επίσης καθαρίζονται από προσμίξεις και άλατα με εκχύλιση στερεάς φάσης, διαχωρίζονται με υγρή χρωματογραφία υψηλής πίεσης(HPLC) και ταυτοποιούνται με φασματομετρία μαζών(MS). Τα τελικά προϊόντα διάσπασης καθαρίζονται με εκχύλιση στερεάς φάσης και ταυτοποιούνται
description: The primitive aim of the PhD Thesis is the development of an electrochemical method for textile wastewater treatment, which contains non biodegradable azodyes. Consequently, primary azodyes are determined using UV-Vis spectrometric and voltammetric techniques. Additionally, they are separated and identified using High Pressure Liquid Chromatography (HPLC) and Mass Spectrometry (MS). Final degradation products are also separated and identified using HPLC coupled with Mass Spectrometer (LC-MS). Solid Phase Extraction is used for chemical interferences and salts removal. Electrochemical method under electrolytic conditions using suitable materials as electrodes, achieves quick decoloration up to 90%, without any sludge formation and any chemical additives. Environmental parameters such as COD, BOD5 and TOC are satisfactory reduced and final degradation products are determined in very low concentrations.
Mott transition and magnetism in a fragile topological insulator
Creators: name: Joshi, Ashish
name: Peters, Robert
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study the effects of electronic correlations on fragile topology using dynamical mean-field theory. Fragile topological insulators (FTIs) offer obstruction to the formation of exponentially localized Wannier functions, but they can be trivialized by adding certain trivial degrees of freedom. For the same reason, FTIs do not host symmetry-protected flow of edge states between bulk bands in cylindrical boundary conditions but are expected to have a spectral flow between the fragile bands and other bands under certain twisted boundary conditions. We here analyze commonly observed effects of strong correlations, such as the Mott-insulator transition and magnetism, on a known model hosting fragile topology. We show that in the nonmagnetic case, fragile topology, along with the twisted boundary states, is stable with interactions below a critical interaction strength. Above this interaction strength, a transition to the Mott insulating phase occurs, and the twisted boundary states disappear. Furthermore, by applying a homogeneous magnetic field, the fragile topology is destroyed. However, we show that a magnetic field can induce a topological phase transition which converts a fragile topological insulator to a Chern insulator. Finally, we study ferromagnetic solutions of the fragile topological model.
description: 11 pages, 7 figures
Three-Dimensional Simulations of the Deflagration Phase of the Gravitationally Confined Detonation Model of Type Ia Supernovae
Creators: name: Jordan, G C
name: Fisher, R T
name: Townsley, D M
name: Calder, A C
name: Graziani, C
name: Asida, S
name: Lamb, D Q
name: Truran, J W
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report the results of a series of three-dimensional (3-D) simulations of the deflagration phase of the gravitationally confined detonation mechanism for Type Ia supernovae. In this mechanism, ignition occurs at one or several off-center points, resulting in a burning bubble of hot ash that rises rapidly, breaks through the surface of the star, and collides at a point opposite breakout on the stellar surface. We find that detonation conditions are robustly reached in our 3-D simulations for a range of initial conditions and resolutions. Detonation conditions are achieved as the result of an inwardly-directed jet that is produced by the compression of unburnt surface material when the surface flow collides with itself. A high-velocity outwardly-directed jet is also produced. The initial conditions explored in this paper lead to conditions at detonation that can be expected to produce large amounts of $^{56}$Ni and small amounts of intermediate mass elements. These particular simulations are therefore relevant only to high luminosity Type Ia supernovae. Recent observations of Type Ia supernovae imply a compositional structure that is qualitatively consistent with that expected from these simulations.
description: Accepted by ApJ
Η εκπαίδευση των εκπαιδευτικών στην Ελλάδα και στην Αγγλία: αρχική εκπαίδευση και επιμόρφωση των εκπαιδευτικών της δευτεροβάθμιας εκπαίδευσης
Creators: name: Γεωργιάδης, Μιχάλης
Publisher: name: Aristotle University of Thessaloniki
Year: 2002
Subjects: Εκπαίδευση εκπαιδευτικών
Συνεχιζόμενη επαγγελματική εκπαίδευση των εκπαιδευτικών
Επιμόρφωση των εκπαιδευτικών
Συγκριτική παιδαγωγική
Αρχική εκπαίδευση εκπαιδευτικών
Παιδαγωγική κατάρτιση εκπαιδευτικών
Teacher education
Continuing professional teacher education
In service teacher education
Comparative education
Initial teacher education
Paedagogical training of teachers

description: Στην εργασία αναλύονται τα προγράμματα της πανεπιστημιακής εκπαίδευσης των εκπαιδευτικών που προορίζονται για την ελληνική δευτεροβάθμια εκπαίδευση καθώς και της εκπαίδευσης των εκπαιδευτικών της τεχνικής εκπαίδευσης. Διερευνάται επίσης το θεσμικό πλαίσιο για τη λειτουργία των θεσμών για την επιμόρφωση των εκπαιδευτικών της ίδιας βαθμίδας. Όλα τα στοιχεία που αναφέρονται τοποθετούνται μέσα στο ιστορικό τους πλαίσιο και στο πλαίσιο της εκπαιδευτικής πολιτικής, αλλά και της γενικότερης συζήτησης για τα αντίστοιχα θέματα. Αντιστοίχως, διερευνάται η εκπαιδευτική πραγματικότητα της Αγγλίας, όπου μια μορφή επαγγελματικής εκπαίδευσης για τους εκπαιδευτικούς της δευτεροβάθμιας εκπαίδευσης έχει θεσπισθεί από τις αρχές του 20ου αιώνα, ενώ στην παρούσα φάση επιχειρείται να ενισχυθεί το πρακτικό και σχολικό στοιχείο των σχετικών προγραμμάτων και η ενδοσχολική επιμόρφωση έχει καταστεί αποκλειστική μορφή επιμόρφωσης. Αντίθετα, στην Ελλάδα μέχρι σήμερα απουσιάζουν τα επαγγελματικά κριτήρια στο σχεδιασμό των προγραμμάτων. Κάτι τέτοιο δεν συμβαίνει στην περίπτωση των εκπαιδευτικών της τεχνικής εκπαίδευσης, ενώ η επιμόρφωση έχει εισέλθει σε μια περίοδο αναζήτησης της πολυτυπίας και πολυμορφίας.
description: This thesis includes a critical analysis f secondary teacher education curricula in Greek universities for those who teach in general secondary education and technical secondary education as well. It is also investigates the institutional context for in service teacher education. All the elements mentioned above are examined in the context of educational policy, in their historical context and in their ideological context. The same elements of English education system are also submitted to critical analysis. In the English education system a kind of professional training for teachers has been established since the beginning of 20th century and in the last twenty years, the enhancement of practical element is being promoted. The school based in service training has become the dominant form. On the contrary, there is a lack of professional element in the teacher education curricula of Greek universities and the in service training passes through a period of transition.
Space Division Multiple Access with a Sum Feedback Rate Constraint
Creators: name: Huang, Kaibin
name: Heath,, Robert W.
name: Andrews, Jeffrey G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Information Theory (cs.IT)
subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: On a multi-antenna broadcast channel, simultaneous transmission to multiple users by joint beamforming and scheduling is capable of achieving high throughput, which grows double logarithmically with the number of users. The sum rate for channel state information (CSI) feedback, however, increases linearly with the number of users, reducing the effective uplink capacity. To address this problem, a novel space division multiple access (SDMA) design is proposed, where the sum feedback rate is upper-bounded by a constant. This design consists of algorithms for CSI quantization, threshold based CSI feedback, and joint beamforming and scheduling. The key feature of the proposed approach is the use of feedback thresholds to select feedback users with large channel gains and small CSI quantization errors such that the sum feedback rate constraint is satisfied. Despite this constraint, the proposed SDMA design is shown to achieve a sum capacity growth rate close to the optimal one. Moreover, the feedback overflow probability for this design is found to decrease exponentially with the difference between the allowable and the average sum feedback rates. Numerical results show that the proposed SDMA design is capable of attaining higher sum capacities than existing ones, even though the sum feedback rate is bounded.
description: 29 pages; submitted to IEEE Transactions on Signal Processing
The effects of surface fossil magnetic fields on massive star evolution: III. The case of $τ$ Sco
Creators: name: Keszthelyi, Z.
name: Meynet, G.
name: Martins, F.
name: de Koter, A.
name: David-Uraz, A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: $τ$ Sco, a well-studied magnetic B-type star in the Upper Sco association, has a number of surprising characteristics. It rotates very slowly and shows nitrogen excess. Its surface magnetic field is much more complex than a purely dipolar configuration which is unusual for a magnetic massive star. We employ the CMFGEN radiative transfer code to determine the fundamental parameters and surface CNO and helium abundances. Then, we employ MESA and GENEC stellar evolution models accounting for the effects of surface magnetic fields. To reconcile $τ$ Sco's properties with single-star models, an increase is necessary in the efficiency of rotational mixing by a factor of 3 to 10 and in the efficiency of magnetic braking by a factor of 10. The spin down could be explained by assuming a magnetic field decay scenario. However, the simultaneous chemical enrichment challenges the single-star scenario. Previous works indeed suggested a stellar merger origin for $τ$ Sco. However, the merger scenario also faces similar challenges as our magnetic single-star models to explain $τ$ Sco's simultaneous slow rotation and nitrogen excess. In conclusion, the single-star channel seems less likely and versatile to explain these discrepancies, while the merger scenario and other potential binary-evolution channels still require further assessment as to whether they may self-consistently explain the observables of $τ$ Sco.
description: Accepted for publication in MNRAS. A full reproduction package is shared on zenodo in accordance with the Research Data Management plan of the Anton Pannekoek Institute for Astronomy at the University of Amsterdam: https://doi.org/10.5281/zenodo.4633408
title: The Relevance of Potential Indicators of External Load for Movement Evaluation in Elite Football Training
Creators: name: Green, M
Publisher: name: Liverpool John Moores University
Year: 2018

description: Football is an intermittent (Bangsbo, 1994; Shephard, 1999; Reilly, 2005) and non-linear team sport. Coaches and practitioners must, therefore, prepare players to complete relatively large volumes of multidirectional activity that are short in duration due to frequent changes. One key aspect of ensuring the appropriateness of any training strategy is to develop and implement an effective training load monitoring strategy. Global Positioning Systems (GPS) incorporated into Micro-Electro-Mechanical Systems (MEMS) devices appear to be the technology that has been most widely adopted to determine activity (Akenhead & Nassis, 2016). The commonly used GPS technologies are regularly accompanied with tri-axial accelerometer within the MEMS hardware. It may be hypothesised that the progression of multiplanar MEMS accelerometer technologies may allow the frequent change of directions and velocities to be more accurately measured and, therefore, evaluate elite football training more effectively. There is, however, currently a lack of applied research, which has attempted to establish the utility of MEMS accelerometers to appropriately capture the movement requirements associated with elite football training. The overall aim of the research contained within the present thesis was, therefore, to investigate the relevance of indicators of external load for the evaluation of the movement requirements in elite football.
Ο γονότυπος της Prion - πρωτεϊνης των προβάτων της Κύπρου και η σχέση του με την τρομώδη νόσο (Scrapie)
Creators: name: Παπασάββα-Στυλιανού, Πηνελόπη
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Γονότυπος της PvP των προβάτων
PvP genotype of sheep
Σπογγιόμορφη εγκεφαλοπάθεια

description: Η τρομώδης νόσος(scrapie) η οποία είναι γνωστή στην Ευρώπη εδώ και 270 χρόνια, διαγνώσθηκε για πρώτη φορά στην Κύπρο το 1985. Παρά τα έντονα μέτρα τα οποία πάρθηκαν από τις Κτηνιατρικές Υπηρεσίες για έλεγχο της νόσου από το 1987, ο αριθμός των μολυσμένων με τρομώδη νόσο κοπαδιών αυξανόνταν ανησυχιτικά. Ερευνες που έχουν γίνει στο εξωτερικό, έχουν δείξει ότι πολυμορφισμοί στο γονίδιο PvP των προβάτων οι οποίοι βρίσκονται κυρίως στα κωδικόνια 136, 154 & 171 συνδέονται στενά με την τρομώδη νόσο, τόσο με την ευαισθησία όσο και την ανθεκτικότητα σ'αυτή. Σκοπός της έρευνας μας ήταν η μείωση της συχνότητας εμφάνισης της νόσου στην Κύπρο με την εφαρμογή προγράμματος επιλεκτικής αναπαραγωγής, το οποίο να βασίζεται στον καθορισμό του γονοτύπου της PvP των προβάτων της Κύπρου. Για το σκοπό αυτό διερευνήσαμε : α) το γονίδιο της PvP των προβάτων των φυλών Χίου και "Ντόπιας", β) το γονίδιο της PvP των θετικών προβάτων και προβάτων "μαρτύρων" - υγιών δηλ. ζώων που ανήκαν σε κοπάδια όπου βρέθηκαν θετικά πρόβατα. Τα αποτελέσματα της έρευνά μας απέδειξαν ότι οι επικρατέστερος γονότυπος της PvP στα πρόβατα της Κύπρου είναι ο ευαίσθητος γονότυπος AA136RR154QQ171
description: Scrapie which is known in Europe for the past 270 years was first diagnosed in Cyprus sheep in 1985. In spite of the control the disease since 1987, the number of the scrapie affected flocks increases every year causing some concern. Results of research abroad have shown that polymosphisms within the PvP gene, mainly located at codons 136, 154 & 171 are closely associated with scrapie susceptibility or resistance. The purpose of this study was to contribute to the application of a selective breading progamme, which should be based on the determonation of the PvP genotype of the Cyprus sheep. For these purpose we investigated : a) the PvP gene of the sheep of breeds Chios and Local(breed survey) and b) the PvP gene of scrapie-affected sheep and "healthy" control sheep. The results of our studies revealed that the predominant genotype of Cyprus sheep is the susceptible genotype AA136RR154QQ171
Gravitational Radiation from Standing Accretion Shock Instability in Core-Collapse Supernovae
Creators: name: Kotake, Kei
name: Ohnishi, Naofumi
name: Yamada, Shoichi
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the results of numerical experiments, in which we study how the asphericities induced by the growth of the standing accretion shock instability (SASI) produce the gravitational waveforms in the postbounce phase of core-collapse supernovae. To obtain the neutrino-driven explosions, we parameterize the neutrino fluxes emitted from the central protoneutron star and approximate the neutrino transfer by a light-bulb scheme. We find that the waveforms due to the anisotropic neutrino emissions show the monotonic increase with time, whose amplitudes are up to two order-of-magnitudes larger than the ones from the convective matter motions outside the protoneutron stars. We point out that the amplitudes begin to become larger when the growth of the SASI enters the nonlinear phase, in which the deformation of the shocks and the neutrino anisotropy become large. From the spectrum analysis of the waveforms, we find that the amplitudes from the neutrinos are dominant over the ones from the matter motions at the frequency below $\sim 100$ Hz, which are suggested to be within the detection limits of the detectors in the next generation such as LCGT and the advanced LIGO for a supernova at 10 kpc. As a contribution to the gravitational wave background, we show that the amplitudes from this source could be larger at the frequency above $\sim$ 1 Hz than the primordial gravitational wave backgrounds, but unfortunately, invisible to the proposed space-based detectors.
description: 22 pages, 10 figures, revised version including referee's comments and with a new high-resolution simulation, accepted by ApJ
Evidence that short period AM CVn systems are diverse in outburst behaviour
Creators: name: Duffy, C.
name: Ramsay, G.
name: Steeghs, D.
name: Dhillon, V.
name: Kennedy, Mark R.
name: Sánchez, D. Mata
name: Ackley, K.
name: Dyer, M.
name: Lyman, J.
name: Ulaczyk, K.
name: Galloway, D. K.
name: O'Brien, P.
name: Noysena, K.
name: Nuttall, L.
name: Pollacco, D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present results of our analysis of up to 15 years of photometric data from eight AM CVn systems with orbital periods between 22.5 and 26.8 min. Our data has been collected from the GOTO, ZTF, Pan-STARRS, ASAS-SN and Catalina all-sky surveys and amateur observations collated by the AAVSO. We find evidence that these interacting ultra-compact binaries show a similar diversity of long term optical properties as the hydrogen accreting dwarf novae. We found that AM CVn systems in the previously identified accretion disc instability region are not a homogenous group. Various members of the analysed sample exhibit behaviour reminiscent of Z Cam systems with long super outbursts and standstills, SU UMa systems with regular, shorter super outbursts, and nova-like systems which appear only in a high state. The addition of TESS full frame images of one of these systems, KL Dra, reveals the first evidence for normal outbursts appearing as a precursor to super outbursts in an AM CVn system. Our results will inform theoretical modelling of the outbursts of hydrogen deficient systems.
description: 11 Pages, 7 Figures, 2 Tables. Accepted for publication in MNRAS. Author's final submitted version
Μελέτη της περίθλασης από φράγματα όγκου εγγεγραμμένων σε φωτοδιαθλαστικά υλικά
Creators: name: Δεληολάνης, Νικόλαος Χ.
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Οπτική
Φράγματα όγκου
Φωτοδιαθλαστικά υλικά
Ηλεκτροστροφικό φαινόμενο
Περιθλαστική ικανότητα
Optics
Volume gratings
Photorefractive materials
Electrogyration
Diffraction efficiency

description: Στην εργασία αυτή μελετούμε την περίθλαση του φωτός από φράγματα φάσης όγκου που είναι εγγεγραμμένα σε φωτοδιαθλαστικά υλικά για την γενική περίπτωση όπου συμπεριλαμβάνονται ως ελεύθεροι παράμετροι: ο τυχαίος προσανατολισμός του κρυστάλλου, η γενική διεύθυνση εγγραφής του φράγματος, η γενική διεύθυνση εφαρμογής ηλεκτρικού πεδίου κατά την φάση της εγγραφής και της ανάγνωσης του φράγματος, η γενική κατάσταση πόλωσης της δέσμης ανάγνωσης και το πάχος του κρυστάλλου. Η μελέτη επικεντρώνεται στους κρυστάλλους της ομάδας των σιλλενιτών Για την μελέτη των περιθλαστικών ιδιοτήτων των φραγμάτων όγκου υπολογίζεται αναλυτικά η μεταβολή των δεικτών διάθλασης και η ένταση του ηλεκτρικού πεδίου της περιθλώμενης χωρίζοντας το φράγμα σε στοιχειώδεις φέτες και αναλύοντας το φως σε ιδιοκαταστάσεις περίθλασης. Για τον έλεγχο της θεωρίας εκτελέστηκαν πειράματα μέτρησης των περιθλαστικών ιδιοτήτων φραγμάτων σε σιλλενίτες συναρτήσει των γενικών παραμέτρων. Τα πειραματικά αποτελέσματα συμφωνούν με τα θεωρητικά προβλεπόμενα και αποδεικνύουν την ορθότητα της ανάλυσης. Επιπλέον, διερευνήθηκαν θεωρητικά οι περιθλαστικές ιδιότητες συναρτήσει των γενικών παραμέτρων με σκοπό την βελτιστοποίηση της λειτουργίας τους. Τέλος, μελετήθηκε το φαινόμενο της ηλεκτροστροφικότητας στους σιλλενίτες και μετρήθηκε η διασπορά του ηλεκτροστροφικού συντελεστή του BGO στην ορατή περιοχή του φάσματος
description: In this dissertation the diffraction of light from volume phase gratings recorded in photorefractive materials is studied. The study refers to the general case for which the orientation of the crystal, the grating direction, the direction of application of the electric field during recording and readout process, the polarization state of the reading beam, and the crystal thickness are considered as free parameters. The study is focused on the sillenite photorefractive crystals. In order to study the diffractive properties of volume gratings the analytical formulae of the change of the refractive indices are calculated as well as the formulae for the diffracted electric field, by splitting up the grading into elementary slices and analyzing the light into the eigenstates of diffraction. The experimental results are in good agreement with the theoretical predictions and this proves the correctness of the theory. Additionally, the diffractive properties of gratings were investigated theoretically in order to optimize their performance. Finally, the electrogyratory effect was studied in sillenites and the dispersion of the electrogyration coefficient was measured at the visible spectrum.
A Q-switched, cavity-dumped YAG laser for use in plasma physics experiments
Creators: name: Leffler, Steven Roy
Publisher: name: University of British Columbia
Year: 2008

description: A Q-switched, cavity-dumped Nd:YAG laser was developed for use as a diagnostic tool in plasma physics experiments. This laser uses an unstable resonator configuration to produce higher gain and better collimation than would otherwise be possible. Pulses of light with energies of 18±2 mJ and FWHMs of about 12 ns were produced. It was found that more than 100 mJ of light was being emitted in the form of prelase pulses, due to the Pockels cells used having a poor extinction ratio. Efforts were made to correct this problem, with only partial success.
A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei
Creators: name: Gallimore, J. F.
name: Axon, D. J.
name: O'Dea, C. P.
name: Baum, S. A.
name: Pedlar, A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Seyfert galaxies commonly host compact jets spanning 10-100 pc scales, but larger structures (KSRs) are resolved out in long baseline, aperture synthesis surveys. We report a new, short baseline Very Large Array (VLA) survey of a complete sample of Seyfert and LINER galaxies. Out of all of the surveyed radio-quiet sources, we find that 44% (19 / 43) show extended radio structures at least 1 kpc in total extent that do not match the morphology of the disk or its associated star-forming regions. The KSR Seyferts stand out by deviating significantly from the far-infrared - radio correlation for star-forming galaxies, and they are more likely to have a relatively luminous, compact radio source in the nucleus; these results argue that KSRs are powered by the AGN rather than starburst. KSRs probably originate from jet plasma that has been decelerated by interaction with the nuclear ISM. We demonstrate the jet loses virtually all of its power to the ISM within the inner kiloparsec to form the slow KSRs.
description: to appear in the Astronomical Journal, Vol 132 (projected)
Quantum control of a nanoparticle optically levitated in cryogenic free space
Creators: name: Tebbenjohanns, Felix
name: Mattana, M. Luisa
name: Rossi, Massimiliano
name: Frimmer, Martin
name: Novotny, Lukas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Tests of quantum mechanics on a macroscopic scale require extreme control over mechanical motion and its decoherence. Quantum control of mechanical motion has been achieved by engineering the radiation-pressure coupling between a micromechanical oscillator and the electromagnetic field in a resonator. Furthermore, measurement-based feedback control relying on cavity-enhanced detection schemes has been used to cool micromechanical oscillators to their quantum ground states. In contrast to mechanically tethered systems, optically levitated nanoparticles are particularly promising candidates for matter-wave experiments with massive objects, since their trapping potential is fully controllable. In this work, we optically levitate a femto-gram dielectric particle in cryogenic free space, which suppresses thermal effects sufficiently to make the measurement backaction the dominant decoherence mechanism. With an efficient quantum measurement, we exert quantum control over the dynamics of the particle. We cool its center-of-mass motion by measurement-based feedback to an average occupancy of 0.65 motional quanta, corresponding to a state purity of 43%. The absence of an optical resonator and its bandwidth limitations holds promise to transfer the full quantum control available for electromagnetic fields to a mechanical system. Together with the fact that the optical trapping potential is highly controllable, our experimental platform offers a route to investigating quantum mechanics at macroscopic scales.
Experimental investigation on bolted flanged steel pipe joint subjected to flexure
Creators: name: Tafheem, Zasiah
Publisher: name: figshare
Year: 2022
Subjects: subject: 90599 Civil Engineering not elsewhere classified
subject: FOS: Civil engineering

description: This paper presents an experimental study on the behaviour of bolted flanged structural steel pipe joint subjected to bending. The sample was prepared by welding a flange to an end of a pipe segment and then joining the two segments of pipe by placing the flanges face to face and fastening using structural bolts through holes in the flanges. The whole assembly was then subjected to flexure by placing on a simple support arrangement and applying two-point loading. Total 16 flanged pipe joint samples were tested having different pipe diameter, flange thickness, bolt diameter etc. The deformation characteristics of the joint demonstrated two different kinds of behaviour: thin flange behaviour and thick flange behaviour. Thin flange behaviour is characterised by local flexural deformation of the flange accompanied by prying action and some bending of the bolts while thick flange behaviour is characterised by contact separation between flanges accompanied by tensile elongation of the bolts.
A Multi-observing-technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star $ω$ CMa
Creators: name: Ghoreyshi, Mohammad R.
name: Carciofi, Alex C.
name: Jones, Carol E.
name: Faes, Daniel M.
name: Baade, Dietrich
name: Rivinius, Thomas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The observed emission lines of Be stars originate from a circumstellar Keplerian disk that are generally well explained by the Viscous Decretion Disk model. In an earlier work we performed the modeling of the full light curve of the bright Be star $ω$ CMa (Ghoreyshi et al. 2018) with the 1-D time-dependent hydrodynamics code SINGLEBE and the Monte Carlo radiative-transfer code HDUST. We used the V -band light curve that probes the inner disk through four disk formation and dissipation cycles. This new study compares predictions of the same set of model parameters with time-resolved photometry from the near UV through the mid-infrared, comprehensive series of optical spectra, and optical broad-band polarimetry, that overall represent a larger volume of the disk. Qualitatively, the models reproduce the trends in the observed data due to the growth and decay of the disk. However, quantitative differences exist, e.g., an overprediction of the flux increasing with wavelength, too slow decreases in Balmer emission-line strength that are too slow during disk dissipation, and the discrepancy between the range of polarimetric data and the model. We find that a larger value of the viscosity parameter alone, or a truncated disk by a companion star, reduces these discrepancies by increasing the dissipation rate in the outer regions of the disk.
description: 25 pages, 19 figures
Προτάσεις διαμόρφωσης και εφαρμογής συστημάτων ελέγχου των παραμορφώσεων σε φορείς μεγάλου ανοίγματος με τη χρήση καλωδίων
Creators: name: Νικολαϊδης, Θεμιστοκλής Ν.,
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Βέλτιστος έλεγχος
Έλεγχος παθητικός
Ελεγχος παραμορφώσεων
Καλώδια
Έξυπνες κατασκευές
Μονόπλευρες κατασκευές
Optimal control
Passive control
Control of displacement
Cablenets
Smart structures
Unilateral structures

description: Στην παρούσα διατριβή παρουσιάζονται και αναλύονται συστήματα ελέγχων των παραμορφώσεων σε φορείς μεγάλου ανοίγματος με τη χρήση ομάδων καλωδίων. Το σύστημα βασίζεται στην ενισχυμένη δοκό από ομάδα καλωδίων με επιπρόσθετο έλεγχο δια προέκτασης των καλωδίων στηρίξεως έτσι ώστε να βελτιστοποιείται η συμπεριφορά του συστήματος της κατασκευής. Ο σχεδιασμός του προβλήματος παθητικού ελέγχου οδηγεί σε ένα πρόβλημα βέλτιστου ελέγχου για κατασκευές που κυβερνώνται από ανισότητες μεταβολών. Το βέλτιστο σχήμα του υποστηρικτικού προεντεταμένου καλωδίου σε πολλές περιπτώσεις οδηγεί στην επίλυση ενός προβλήματος εύρεσης μορφής της κατασκευής.
description: In the present dissertation, displacement control systems for large span structures using cablenets are here in proposed. The system is based on cable supported beam nets with additional prestressing control of the support cables such as to optimize the structural behavior of the system: the passive control design problem leads to an optimal control problem for structures governed by variational inequalities. The optimal shape of a prestressing support cable in many cases leads to a form-finding problem of the structure.
Enhanced Cosmic Ray Flux and Ionization for Star Formation in Molecular Clouds Interacting with Supernova Remnants
Creators: name: Fatuzzo, M.
name: Adams, F. C.
name: Melia, F.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Molecular clouds interacting with supernova remnants may be subject to a greatly enhanced irradiation by cosmic rays produced at the shocked interface between the ejecta and the molecular gas. Over the past decade, broad-band observations have provided important clues about these relativistic particles and indicate that they may dominate over the locally observed cosmic-ray population by a significant amount. In this paper, we estimate the enhancement and find that the cosmic ray energy density can be up to $\sim$1000 times larger in the molecular cloud than in the field. This enhancement can last for a few Myr and leads to a corresponding increase in the ionization fraction, which has important consequences for star formation. Ionization fractions in] molecular cloud cores determine, in part, the rate of ambipolar diffusion, an important process in core formation and pre-collapse evolution. Ionization fractions in newly formed circumstellar disks affect the magneto-rotational instability mechanism, which in turn affects the rate of disk accretion. As estimated here, the increased ionization acts to increase the ambipolar diffusion time by a factor of $\sim30$ and thereby suppresses star formation. In contrast, the increased ionization fraction reduces the sizes of dead zones in accretion disks (by up to an order of magnitude) and thus increases disk accretion rates (by a comparable factor).
description: Accepted for publication in ApJ Letters
Higher braid groups and regular semigroups from polyadic-binary correspondence
Creators: name: Duplij, Steven
Publisher: name: arXiv
Year: 2021
Subjects: subject: Group Theory (math.GR)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Quantum Algebra (math.QA)
subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 16T25, 17A42, 20B30, 20F36, 20M17, 20N15

description: In this note we first consider a ternary matrix group related to the von Neumann regular semigroups and to the Artin braid group (in an algebraic way). The product of a special kind of ternary matrices (idempotent and of finite order) reproduces the regular semigroups and braid groups with their binary multiplication of components. We then generalize the construction to the higher arity case, which allows us to obtain some higher degree versions (in our sense) of the regular semigroups and braid groups. The latter are connected with the generalized polyadic braid equation and $R$-matrix introduced by the author, which differ from any version of the well-known tetrahedron equation and higher-dimensional analogs of the Yang-Baxter equation, $n$-simplex equations. The higher degree (in our sense) Coxeter group and symmetry groups are then defined, and it is shown that these are connected only in the non-higher case.
description: 17 pages, amslatex
Mechanical unfolding and refolding pathways of ubiquitin
Creators: name: Imparato, A.
name: Pelizzola, A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Biomolecules (q-bio.BM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Mechanical unfolding and refolding of ubiquitin are studied by Monte Carlo simulations of a Go model with binary variables. The exponential dependence of the time constants on the force is verified, and folding and unfolding lengths are computed, with good agreement with experimental results. Furthermore, the model exhibits intermediate kinetic states, as observed in experiments. Unfolding and refolding pathways and intermediate states, obtained by tracing single secondary structure elements, are consistent with simulations of previous all-atom models and with the experimentally observed step sizes.
Αξιολόγηση ελληνικών τροφίμων με προσδιορισμό βιολογικά ενεργών λιπαρών οξέων
Creators: name: Λασκαρίδης, Κώστας Σ.
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Βιολογικά ενεργά λιπαρά οξέα
Σύζηγες λινελαϊκό οξύ
Bioactive fatty acids
Conjugated linoleic acid

description: Στην εργασία αυτή αξιολογούνται ελληνικά τρόφιμα ως πηγές των ω3 λιπαρών οξέων και του CLA. Οι πηγές που χρησιμοποιήθηκαν για την απομόνωση και την ανάλυση των ω3 λιπαρών οξέων είναι θαλάσσιοι ζωικοί οργανισμοί, ενώ οι πηγές του CLA που χρησιμοποιήθηκαν είναι ελληνικά τυριά. Επίσης γίνεται προσπάθεια για την εξακρίβωση των παραγόντων οι οποίοι επιδρούν στο περιεχόμενο αυτών των λιπαρών οξέων στις συγκεκριμένες τροφές καθώς και η εξεύρεση πηγών ως πρώτη ύλη για την παραγωγή συμπληρωμάτων διατροφής. Από τα αποτελέσματα προέκυψε η σχέση της τάξης των μαλακίων που αναλύθηκαν και των περιεχόμενων λιπαρών οξέων. Τα κεφαλόποδα μαλάκια αν και περιέχουν υψηλούς λόγους πρωτεΐνης προς λίπος, αποτελούν καλές πηγές των ω3 λιπαρών οξέων. Επίσης οι πλούσιες θρεπτικές ύλες του μυδιού το καθιστούν εξαιρετική πρώτη ύλη για την παραγωγή συμπληρωμάτων διατροφής. Από τις αναλύσεις τυριών οι οποίες διεξήχθησαν βρέθηκε ότι τα ελληνικά σκληρά τυριά είναι καλύτερες πηγές CLA από οποιοδήποτε άλλο τυρί αναφέρεται στην παγκόσμια βιβλιογραφία. Επίσης προκύπτει η σχέση της αυξημένης περιεκτικότητας σε CLA και του γαλακτοφόρου ζώου. Ένας πρόσθετος παράγοντας που οδηγεί στην μεγάλη περιεκτικότητα CLA των ελληνικών τυριών είναι η επιλεκτική τυροκόμηση κατά τους εαρινούς και καλοκαιρινούς μήνες
description: In this thesis, some Greek foods were examined as sources of ω3 fatty acids and CLA. In particular, mollusks (i.e. bivalves, cephalopods and gastropods) were analyzed with respect their ω3 fatty acid content, while Greek cheeses were analyzed with respect their CLA content. Parameters affecting the fatty acid composition of these foods were studied and new sources for the production of dietary supplements were found out. The results show that the ω3 fatty acid content depends strongly on the order of sea organisms. Despite the fact that cephalopods contain high protein to fat ratio, they are good sources of ω3 fatty acids. In addition, the Mediterranean blue mussel is an excellent source for the production of dietary supplements. From the examination of cheeses it was found out that Greek hard cheeses are better CLA sources than any other cheese reported in the literature. Also it was shown that CLA content of cheeses is related to the kind of milk-producing animal. On the other hand, the production of the most Greek traditional cheeses takes place mainly during spring and summer and it was proved that this is an additional factor affecting the CLA content
CHARACTERIZATION OF THE BACTERIOCIN-LIKE SUBSTANCE FROM LACTOCOCCUS LACTIS SUBSP. LACTIS WX153 AGAINST SWINE PATHOGEN STREPTOCOCCUS SUIS
Creators: name: Nopparat Srimark
name: Nongpanga Khunajakr
Publisher: name: Chulalongkorn Universtiy Press
Year: 2015
Subjects: Streptococcus suis, Lactococcus lactis,Probiotic,Bacteriocin

description: 4, 29, Journal of Health Research
Nonlinear waves in a dispersive vacuum described with a high order derivative electromagnetic Lagrangian
Creators: name: Pegoraro, Francesco
name: Bulanov, Sergei
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: In this article we use an electromagnetic Lagrangian constructed so as to include dispersive effects in the description of an electromagnetic wave propagating in the Quantum Electrodynamic Vacuum. This Lagrangian is Lorentz invariant, includes contributions up to six powers in the electromagnetic fields and involves both fields and their first derivatives. Conceptual limitations inherent to the use of this higher derivative Lagrangian approach are discussed. We consider the one-dimensional spatial limit and obtain an exact solution of the nonlinear wave equation recovering the Korteveg-de Vries type periodic waves and solitons given in S. V. Bulanov et al., Phys. Rev. D, 101, 016016 (2020).
description: 11 pages
DRINKING PATTERNS AND THEIR PREDICTIVE FACTORS : A CASE STUDY OF A COMMUNITY IN PHAYAO PROVINCE, THAILAND
Creators: name: Donnapa Hongtong
name: Nantika Ananchaipattana
name: PimpimonWongchaiya
Publisher: name: Chulalongkorn Universtiy Press
Year: 2015
Subjects: Predictive factors,Alcohol consumption,Rural community,Thailand

description: 4, 29, Journal of Health Research
Magnetic Ordering of CoCl_{2}-GIC: a Spin Ceramic -Hierarchical Successive Transitions and the Intermediate Glassy Phase-
Creators: name: Suzuki, Masatsugu
name: Suzuki, Itsuko S.
name: Matsuura, Motohiro
Publisher: name: arXiv
Year: 2006
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: Stage-2 CoCl$_{2}$-GIC is a spin ceramic and shows hierarchical successive transitions at $T_{cu}$ (= 8.9 K) and $T_{cl}$ (= 7.0 K) from the paramagnetic phase into an intra-cluster (two-dimensional ferromagnetic) order with inter-cluster disorder and then to an inter-cluster (three-dimensional antiferromagnetic like) order over the whole system. The nature of the inter-cluster disorder was suggested to be of spin glass by nonlinear magnetic response analyses around $T_{cu}$ and by studies on dynamical aspects of ordering between $T_{cu}$ and $T_{cl}$. Here, we present a further extensive examination of a series of time dependence of zero-field cooled magnetization $M_{ZFC}$ after the aging protocol below $T_{cu}$. The time dependence of the relaxation rates $S_{ZFC}(t) = (1/H)dM_{ZFC}(t)/d\ln t$ dramatically changes from the curves of simple spin glass aging effect below $T_{cl}$ to those of two peaks above $T_{cl}$. The characteristic relaxation behavior apparently indicates that there coexist two different kinds of glassy correlated regions below $T_{cu}$.
description: 6 pages, 3 figures, Proceeding of HFM2006, J. Phys.: Condensed Matter (accepted for publication)
VALIDATION OF BEHAVIORAL REGULATION IN EXERCISE QUESTIONNAIRE-2 (BREQ-2) AND DIETARY SELF-REGULATION (DSR) IN OVERWEIGHT HIGH SCHOOL STUDENTS IN THAILAND
Creators: name: Kanlayanee  No-In
name: Arunya  Tuicomepee
name: Wiroj  JiamjarasrangsiPornchai  Sithisarankul1, *
Publisher: name: Chulalongkorn Universtiy Press
Year: 2015
Subjects: Scale validation,Dietary self-regulation,Behavioral regulation in exercise questionnaire,Overweight,High school students,Thailand

description: 4, 29, Journal of Health Research
Propagation of edge magnetoplasmons in semiconductor quantum-well structures
Creators: name: Mikhailov, S. A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The wavelength and the propagation length of the edge magnetoplasmons, running along the edge of a two-dimensional electron layer in a semiconductor quantum-well structure are theoretically studied as a function of frequency, magnetic field, electron density, mobility, and geometry of the structure. The results are intended to be used for analysis and optimization of operation of recently invented quantum-well microwave spectrometers operating at liquid-nitrogen temperatures (I. V. Kukushkin {\em et al}, Appl. Phys. Lett. {\bf 86}, 044101 (2005)).
description: 4 pages, including 4 figures. Accepted for publication in Appl. Phys. Lett
Θεωρητική μελέτη και ανάλυση ηλεκτρονικών ιδιοτήτων μονοδιάστατων κβαντικών αγωγών
Creators: name: Βαργιαμίδης, Βασίλειος
Publisher: name: Aristotle University of Thessaloniki
Year: 2003
Subjects: Κβαντικοί αγωγοί
Κβαντική αγωγιμότητα
Στένωση
Ηλεκτρονικοί κυματαγωγοί
Διέλευση
Quantum wires
Quantum conductance
Constriction
Electron waveguides
Transmission

description: Σκοπός αυτής της διδακτορικής διατριβής είναι να συμβάλλει στη συνεχιζόμενη ερευνητική προσπάθεια που γίνεται την τελευταία δεκαετία στα συστήματα χαμηλών διαστάσεων και πιο συγκεκριμένα στην συμπεριφορά και στις ηλεκτρονιακές ιδιότητες μονοδιάστατων κβαντικών αγωγών. Το πλάτος αυτών των αγωγών είναι αρκετά μικρό και συγκρίσιμο με το μήκος κύματος de Broglie των ηλεκτρονίων (μερικά νανόμετρα). Ετσι, υπάρχει εμφάνιση κβαντικών φαινομένων. Βρέθηκε ότι η αγωγιμότητα ως συνάρτηση του πλάτους του αγωγού μεταβάλλεται με κβαντικά βήματα. Μελέτησα την επίδραση προσμίξεων στην σκέδαση και στην αγωγιμότητα ενός ευθύγραμμου κβαντικού αγωγού. Χρησιμοποίησα την εξίσωση Lippmann-Schwinger της κβαντομηχανικής θεωρίας σκέδασης για τον υπολογισμό των κυματοσυναρτήσεων. Βρήκα ότι η παρουσία προσμίξεων αυξάνει την ανάκλαση. Μελέτησα επίσης την επίδραση της μορφής της εγκάρσιας διατομής του αγωγού στην αγωγιμότητα. Η μελέτη αυτή έγινε με και χωρίς μαγνητικό πεδίο. Απουσία μαγνητικού πεδίου βρήκα ότι όσο αυξάνει η ανισοτροπία της εγκάρσιας διατομής η διέλευση μειώνεται. Όταν υπάρχει μαγνητικό πεδίο η κατεύθυνση του οποίου είναι κατά μήκος του μικρότερου άξονα της διατομής τότε η αγωγιμότητα αυξάνει ραγδαία.
description: The purpose of this doctoral thesis is to contribute to the ongoing research in low dimensional systems and more specifically in the electronic properties in one dimensional quantum wires. The width of the wire is small enough to be comparable with the de Broglie wavelength (i.e., few nanometers). So, quantum mechanical effects become important. It has been found that the conductance as a function of the width of the wire increases in quantized steps. I studied the effects of impurities on the conductance of a rectilinear quantum wire by using the Lippmann-Schwinger equation of scattering theory. I found that the presence of impurities increases reflection and the quantization is destroyed. I also studied the effects of the cross-sectional shape of the wire on the conductance. The analysis was done with and without a magnetic field. In the absence of a magnetic field, increasing the anisotropy of the transverse cross section causes enhanced reflection. In the presence of a magnetic field oriented along the smaller axis of the cross section there is a dramatic increase of the conductance.
Quantum tunnelling of muonium in copper(I) chloride
Creators: name: MacFarlane, W. Andrew
Publisher: name: University of British Columbia
Year: 2008

description: The unusual behaviour of paramagnetic muonium centres in the binary semiconductor Copper(I) Chloride at low temperatures lacks a satisfactory explanation. In this thesis, after a brief review of the experimental results to date, a model for the spin dynamics of the muon as it undergoes local quantum tunnelling motion amongst four wells arranged in a tetrahedron is presented. Calculations based on this model suggest that a level crossing resonance associated with the tunnel splitting could be observed in a 1iSR experiment.