cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Vibrational Frequency used as Internal Clock Reference to access Molecule -- Metal Charge Transfer Times
Creators: name: Jakob, Peter
name: Thussing, Sebastian
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Dynamical charge transfer processes at molecule-metal interfaces proceed in the few fs time scale that renders them highly relevant to electronic excitations in optoelectronic devices. Yet, knowledge thereof is limited when electronic ground state situations are considered that implicate charge transfer directly at the fermi energy. Here we show that such processes can be accessed by means of vibrational excitations, with non-adiabatic electron-vibron coupling leading to distinct asymmetric line shapes. Thereby the characteristic time scale of this interfacial dynamical charge transfer can be derived by using the vibrational oscillation period as an internal clock reference.
description: 11 pages, 3 figures
Reward Distance Comparisons Under Transition Sparsity
Creators: name: Nyanhongo, Clement
name: Henrique, Bruno Miranda
name: Santos, Eugene
Publisher: name: arXiv
Year: 2025
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Reward comparisons are vital for evaluating differences in agent behaviors induced by a set of reward functions. Most conventional techniques utilize the input reward functions to learn optimized policies, which are then used to compare agent behaviors. However, learning these policies can be computationally expensive and can also raise safety concerns. Direct reward comparison techniques obviate policy learning but suffer from transition sparsity, where only a small subset of transitions are sampled due to data collection challenges and feasibility constraints. Existing state-of-the-art direct reward comparison methods are ill-suited for these sparse conditions since they require high transition coverage, where the majority of transitions from a given coverage distribution are sampled. When this requirement is not satisfied, a distribution mismatch between sampled and expected transitions can occur, leading to significant errors. This paper introduces the Sparsity Resilient Reward Distance (SRRD) pseudometric, designed to eliminate the need for high transition coverage by accommodating diverse sample distributions, which are common under transition sparsity. We provide theoretical justification for SRRD's robustness and conduct experiments to demonstrate its practical efficacy across multiple domains.
description: Published in the TMLR, https://openreview.net/forum?id=haP586YomL
Symplectic tomography of ultracold gases in tight-waveguides
Creators: name: del Campo, A.
name: Man'ko, V. I.
name: Marmo, G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The phase space is the natural ground to smoothly extrapolate between local and non-local correlation functions. With this objective, we introduce the symplectic tomography of many-body quantum gases in tight-waveguides, and concentrate on the reduced single-particle symplectic tomogram (RSPST) whose marginals are the density profile and momentum distribution. We present an operational approach to measure the RSPST from the time evolution of the density profile after shutting off the interactions in a variety of relevant situations: free expansion, fall under gravity, and oscillations in a harmonic trap. From the RSPST, the one-body density matrix of the trapped state can be reconstructed.
description: 5 pages, no figures
Enhanced current flow through meandering and tilted grain boundaries in YBCO films
Creators: name: Dinner, Rafael B.
name: Moler, Kathryn A.
name: Feldmann, D. Matthew
name: Beasley, M. R.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Grain boundaries (GBs) have been shown to limit critical current density, Jc, in YBa2Cu3O7 (YBCO) coated conductors. Here we use transport measurements and scanning Hall probe microscopy coupled with current reconstruction to demonstrate that GB geometry, such as the in-plane meandering observed in films grown by metalorganic deposition (MOD) on rolling assisted biaxially textured substrate (RABiTS), can lead to higher GB Jc. We observe current-induced flux entry into such a coated conductor, then model its behavior by imaging films with single, straight GBs tilted at various angles to the applied current.
description: 3 pages, 3 figures. For submission to Applied Physics Letters. Movies and higher resolution figures at http://www.stanford.edu/group/moler/rdinner/
DeGaS-MC: Dense Gas Survey in the Magellanic Clouds I -- An APEX survey of HCO+ and HCN(2-1) toward the LMC and SMC
Creators: name: Galametz, M.
name: Schruba, A.
name: De Breuck, C.
name: Immer, K.
name: Chevance, M.
name: Galliano, F.
name: Gusdorf, A.
name: Lebouteiller, V.
name: Lee, M. Y.
name: Madden, S. C.
name: Polles, F. L.
name: van Kempen, T. A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Investigating star formation requires precise knowledge of the properties of the dense molecular gas. The low metallicity and wide range of star formation activity of the Large and Small Magellanic Clouds make them prime laboratories to study how local physical conditions impact the dense gas reservoirs. The aim of the Dense Gas Survey for the Magellanic Clouds (DeGaS-MC) project is to expand our knowledge of the relation between dense gas properties and star formation activity by targeting the LMC and SMC observed in the HCO+(2-1) and HCN(2-1) transitions. We carried out a pointing survey toward 30 LMC and SMC molecular clouds using the SEPIA180 instrument installed on the APEX telescope and a follow-up mapping campaign in 13 star-forming regions. This first paper provides line characteristic catalogs and integrated line-intensity maps of the sources. HCO+(2-1) is detected in 20 and HCN(2-1) in 8 of the 29 pointings observed. The dense gas velocity pattern follows the line-of-sight velocity field derived from the stellar population. The HCN emission is less extended than the HCO+ emission. The HCO+(2-1)/HCN(2-1) brightness temperature ratios range from 1 to 7, which is consistent with the large ratios commonly observed in low-metallicity environments. A larger number of young stellar objects are found at high HCO+ intensities and lower HCO+/HCN flux ratios, and thus toward denser lines of sight. The dense gas luminosities correlate with the star formation rate traced by the total infrared luminosity over the two orders of magnitude covered by our observations, although substantial region-to-region variations are observed.
description: Accepted for publication in A&A; 25 pages, 13 figures, 5 tables
Reaction-noise induced homochirality
Creators: name: Hochberg, David
name: Zorzano, Maria-Paz
Publisher: name: arXiv
Year: 2007
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Chemical Physics (physics.chem-ph)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Starting from the chemical master equation, we employ field theoretic techniques to derive Langevin-type equations that exactly describe the stochastic dynamics of the Frank chiral amplification model with spatial diffusion. The intrinsic multiplicative noise properties are completely and rigorously derived by this procedure. We carry out numerical simulations in two spatial dimensions. When the inherent spatio-temporal fluctuations are properly included, then complete chiral amplification results from a purely racemic initial configuration. Phase separation can also arise in which the enantiomers coexist in spatially segregated domains separated by a sharp racemic interface or boundary.
description: 11 pages, 3 figures in color
CL-MAPF: Multi-Agent Path Finding for Car-Like Robots with Kinematic and Spatiotemporal Constraints
Creators: name: Wen, Licheng
name: Zhang, Zhen
name: Chen, Zhe
name: Zhao, Xiangrui
name: Liu, Yong
Publisher: name: arXiv
Year: 2020
Subjects: subject: Robotics (cs.RO)
subject: Multiagent Systems (cs.MA)
subject: FOS: Computer and information sciences

description: Multi-Agent Path Finding has been widely studied in the past few years due to its broad application in the field of robotics and AI. However, previous solvers rely on several simplifying assumptions. They limit their applicability in numerous real-world domains that adopt nonholonomic car-like agents rather than holonomic ones. In this paper, we give a mathematical formalization of Multi-Agent Path Finding for Car-Like robots (CL-MAPF) problem. For the first time, we propose a novel hierarchical search-based solver called Car-like Conflict-Based Search to address this problem. It applies a body conflict tree to address collisions considering shapes of the agents. We introduce a new algorithm called Spatiotemporal Hybrid-State A* as the single-agent path planner to generate path satisfying both kinematic and spatiotemporal constraints. We also present a sequential planning version of our method for the sake of efficiency. We compare our method with two baseline algorithms on a dedicated benchmark containing 3000 instances and validate it in real-world scenarios. The experiment results give clear evidence that our algorithm scales well to a large number of agents and is able to produce solutions that can be directly applied to car-like robots in the real world. The benchmark and source code are released in https://github.com/APRIL-ZJU/CL-CBS.
Συντηρητική κατάσχεση πλοίου και σχετικά ζητήματα ναυτικού δικαίου:
Creators: name: Σαμλίδης, Ελευθέριος Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Συντηρητική κατάσχεση
Πλοίο
Διεθνής Σύμβαση των Βρυξελλών της 10ης Μαΐου 1952
Απαγόρευση απόπλου
Arrest
Ship
International Convention Relating to the Arrest of Sea-Going Ships - Brussels, May 10, 1952
Detention

description: Στην παρούσα διπλωματική εργασία επιχειρείται η μελέτη του θεσμού της συντηρητικής κατάσχεσης πλοίου, όπως αυτός ρυθμίζεται από το ελληνικό δίκαιο και συγκεκριμένα τον Κώδικα Πολιτικής Δικονομίας και τον Κώδικα Ιδιωτικού Ναυτικού Δικαίου, καθώς και από τη Διεθνή Σύμβαση των Βρυξελλών της 10ης Μαΐου 1952 «περί ενοποιήσεως κανόνων τινών επί συντηρητικής κατασχέσεως θαλασσοπλοούντων πλοίων». Συγκεκριμένα, εξετάζονται οι ουσιαστικές προϋποθέσεις και η διαδικασία επιβολής του εν λόγω ασφαλιστικού μέτρου, όταν ζητείται από ελληνικό δικαστήριο. Επιπλέον, μελετώνται οι επερχόμενες συνέπειες της επιβολής του, καθώς και οι περιπτώσεις άρσης του. Επιπρόσθετα, η παρούσα αντιμετωπίζει τέσσερα θέματα που άπτονται της ευρύτερης ύλης του ναυτικού δικαίου και συγκεκριμένα τον τρόπο απόκτησης πλοίου και τις μορφές πλοιοκτησίας, την ευθύνη του κυρίου του πλοίου για απαιτήσεις που πηγάζουν από τον εφοπλισμό, το ζήτημα των Δημόσιων πλοίων, σε σχέση με το εξεταζόμενο ασφαλιστικό μέτρο και, τέλος, το ζήτημα της πολλαπλότητας των κατασχέσεων.
description: This thesis attempts to study the institution of the arrest of ships, as regulated by the Greek Code of Civil Procedure and the Greek Code of Private Maritime Law, and also by the International Convention (Brussels, May 10, 1952) "for the unification of certain rules relating to the arrest of sea-going ships”. Specifically, it considers the substantive conditions and the procedure for the arrest of ships, under the authority of a Greek court. Moreover, it studies the upcoming consequences of the measure’s enforcement, as well as the cases of its lifting. In addition, this treatise addresses four issues of the broader matter of maritime law, and in particular the way the ship acquisition and ownership forms, the responsibility of the ship owner for claims related to the outfitting, the issue of public vessels, related to the arrest of ships and, finally, the issue of multiplicity of arrests.
Optimizing Engine Oil Cooling in Textile Mills: A  Twisted Shell and Tube Heat Exchanger Approach
Creators: name: Khan Yishtiaq, Raatul
Publisher: name: Zenodo
Year: 2023
Subjects: Heat Exchanger
Shell and Tube
Copper Tubes
Mild Steel Shell
Tubing Layout
Heat Transfer
Thermal Proficiency
Materials Selection
Corrosion Resistance
Turbulence Augmentation
Experimental Arrangement
Water Circulation
Engine Oil
Performance Evaluations
Efficiency Appraisal
Temperature Profiles
Heat Transfer Coefficients
Overall Efficiency
Methodology
Experimental Procedures

description: This technical report chronicles the development, fabrication, and performance assessment of a distinctive shell and tube heat exchanger system. Featuring copper tubes encased in a mild steel shell with a unique twist in tubing layout, the design focuses on maximizing heat transfer effectiveness and thermal proficiency.The selection of materials, incorporating copper tubes and a mild steel shell, was deliberate to ensure longevity and resistance to corrosion, pivotal aspects in industrial settings. The introduction of twisted pipes within the system is aimed at augmenting turbulence and fostering improved heat transfer.In this experimental arrangement, water circulated through the copper tubes, while the shell side accommodated engine oil. Exhaustive performance evaluations were conducted to appraise the efficiency of the heat exchanger under varied conditions. The findings yield valuable insights into the heat transfer capabilities of this innovative design.This report furnishes a thorough scrutiny of the methodology, experimental procedures, and outcomes, encompassing temperature profiles, heat transfer coefficients, and overall efficiency. The gathered data and observations are anticipated to enrich the broader comprehension of heat exchanger design and operation, especially in applications involving dissimilar fluids.
Reaction of lime and coal mineral matter with hydrogen
Creators: name: Chuang, Winnie Hueu-Liang
Publisher: name: University of British Columbia
Year: 2009

description: Removal of H₂S from gasification product gases is a necessary step in integrated gasification combined cycle power generation. H₂S capture by lime and coal ashes at 850°C from N₂ and N₂-steam mixtures with 200-2300 ppmv inlet H₂S concentration was studied in a packed bed reactor. Experiments were carried out on Texada lime (d[sub p] = 770 μrn) and ash from three kinds of coal: Highvale, Costello, Minto, with particle diameters between 144 and 303 um. The breakthrough curves of H₂S* under various conditions were obtained from N₂ containing up to 40 vol% steam content. In the absence of steam, Texada lime was superior to all coal ashes for H₂S capture, yielding spent sorbents with greater than 35 wt% S compared to the possible 44.5 wt% S for pure CaS. Coal ash from Highvale and Costello coals reacted 4 and 10 wt% S, respectively. Coal ash appeared to promote some H₂S cracking, rather than solely sulphide formation. For Mint ash, sulphide level of 18.8 wt% was achieved. Iron oxide appears to be the primary reacting species in this ash. The results indicate that the sulphur capture by lime is limited by the equilibrium of the H₂S-CaO reaction. In the presence of steam, sulphur removal by Texada lime was reduced. As the steam content increased from 0 vol% to 40 vol%, the sulphur content in spent Texada lime (0.3 g) decreased from 35 wt% to 24 wt%. For spent Costello ash containing the equivalent amount of CaO, S content decreased from 10 wt% to 8 wt%. For Highvale ash, no H₂S was captured in the presence of steam, on the contrary, some residual sulphur in ash was released to the gas. With Highvale and Costello ash, SO₂ was detected; the SO₂ production was enhanced by increasing amount of sorbent, inlet H₂S concentration, and steam content. The forward reaction of dry H₂S and CaO in the fixed bed was analyzed by available reaction models. The disappearance of H₂S could be modeled as a first order process with rate constant kʹ=1.275 (min⁻¹) in the early stage of reaction. To obtain appropriate rate expression for the late stages of reaction, the grain model was applied to the fixed bed system to describe the single particle behavior. The chemical reaction constant on the grain surface is evaluated as k=1.85x10⁻⁴(cm/s) by assuming the initial reaction rate is controlled by chemical reaction only. The influence of effective intrapellet diffusion and diffusion in the product layer of each grain were also considered in the overall reaction rate expression. The approach of Krishnan and Sotirchos where effective diffusivities decrease as increasing solid conversion, X, was applied to this case. By assuming reaction being in the extreme cases, the resulting intrapellet diffusivity, De[sub eff] and intragrain diffusivity, De , were 0.3e⁻¹⁰[sup x] (cm²/s)and l 1.1x10⁻⁵e⁻¹³ [sup x]. (cm²/s) respectively, and they both provided good prediction on the solid conversion in the present system.
Spin evolution of neutron stars in two modes: implication for millisecond pulsars
Creators: name: Bhattacharyya, Sudip
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: An understanding of spin frequency ($ν$) evolution of neutron stars in the low-mass X-ray binary (LMXB) phase is essential to explain the observed $ν$-distribution of millisecond pulsars (MSPs), and to probe the stellar and binary physics, including the possibility of continuous gravitational wave emission. Here, using numerical computations we conclude that $ν$ can evolve in two distinctly different modes, as $ν$ may approach a lower spin equilibrium value ($ν_{\rm eq,per}$) for persistent accretion for a long-term average accretion rate ($\dot{M}_{\rm av}$) greater than a critical limit ($\dot{M}_{\rm av,crit}$), and may approach a higher effective spin equilibrium value ($ν_{\rm eq,eff}$) for transient accretion for $\dot{M}_{\rm av} < \dot{M}_{\rm av,crit}$. For example, when $\dot{M}_{\rm av}$ falls below $\dot{M}_{\rm av,crit}$ for an initially persistent source, $ν$ increases considerably due to transient accretion, which is counterintuitive. We also find that, contrary to what was suggested, a fast or sudden decrease of $\dot{M}_{\rm av}$ to zero in the last part of the LMXB phase is not essential for the genesis of spin-powered MSPs, and neutron stars could spin up in this $\dot{M}_{\rm av}$-decreasing phase. Our findings imply that the traditional way of $ν$-evolution computation is inadequate in most cases, even for initially persistent sources, and may not even correctly estimate whether $ν$ increases or decreases.
description: 5 pages, 3 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society Letters
Leveraging Computer Vision for Quantitative Analysis of Stained Organoid Images to Evaluate Glioblastoma Drug Efficacy
Creators: name: Vedanth Venkatesh
Publisher: name: Zenodo
Year: 2023

description: Glioblastoma, also referred to as a grade IV astrocytoma, is a fast-growing and aggressive braintumor. Despite years of research, the life expectancy after diagnosis with treatment remains at 14 to 16months. When cancer recurs, which is not uncommon, no treatment options are available for patients.Organoid culture has slowly replaced traditional cell culture in chemotherapeutic drug testing for variouscancers. Characterization of organoids is done with immunohistochemistry analysis, and viability in drugstudies is corroborated with live/dead assays. These imaging studies are primarily qualitative.This research study proposes enhancing this qualitative analysis with quantitative insights from theComputer Vision(CV) principles of Artificial Intelligence(AI). The proposed algorithm automates theprocessing of any set of organoid images to identify and numerically count stained cells, extractingobjective viability percentages from visual data. This research showcases the potential of Computer Visionengineering to accelerate and improve Glioblastoma research by supplementing qualitative observationswith rigorous computational metrics. Integrating these quantification methods with traditional visualevaluation could lead to more consistent, unbiased, and insightful drug testing, potentially expeditingGlioblastoma therapy discovery
Pair correlations in nuclei involved in neutrinoless double beta decay: 76Ge and 76Se
Creators: name: Freeman, S. J.
name: Schiffer, J. P.
name: Villari, A. C. C.
name: Clark, J. A.
name: Deibel, C.
name: Gros, S.
name: Heinz, A.
name: Hirata, D.
name: Jiang, C. L.
name: Kay, B. P.
name: Parikh, A.
name: Parker, P. D.
name: Qian, J.
name: Rehm, K. E.
name: Tang, X. D.
name: Werner, V.
name: Wrede, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Precision measurements were carried out to test the similarities between the ground states of 76Ge and 76Se. The extent to which these two nuclei can be characterized as consisting of correlated pairs of neutrons in a BCS-like ground state was studied. The pair removal (p,t) reaction was measured at the far forward angle of 3 degrees. The relative cross sections are consistent (at the 5% level) with the description of these nuclei in terms of a correlated pairing state outside the N=28 closed shells with no pairing vibrations. Data were also obtained for 74Ge and 78Se.
The quaternionic Goos-Haenchen shift
Creators: name: De Leo, Stefano
name: Ducati, Gisele C.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the lateral displacement of electronic waves when partially and totally reflected by a quaternionic potential. Following the analogy between Quantum Mechanics and Optics we introduce a refractive index for the complex and the pure quaternionic case. For incidence greater than the critical one (total reflection) the quaternionic potentials amplify the lateral displacement found in the complex case. For incidence below the critical angle, we find, in the quaternionic case, an additional shift. The analytical formula found for the quaternionic lateral displacement gives the possibility to observe quantitative and qualitative differences between the complex and quaternionic Goos-Haenchen shift.
description: 12 pages, 4 figures
Ο διάλογος και το σχέδιο ζωγραφικής ως αποτελεσματικές τεχνικές για την κατανόηση της περιθωριοποίησης.
Creators: name: Μιχαηλίδου, Αντωνία
name: Αγγελίδης, Παναγιώτης
Publisher: name: Παιδαγωγική Επιθεώρηση
Year: 2015

description: Researchers who deal with inclusive education have made great efforts to listen to the voices of children in order to understand marginalization. Despite the fact that these efforts take place, the voices of many children fail to be heard and hence many children continue to be marginalized. In this paper we will develop and implement a technique in order to understand and address mar¬ginalization. We will develop a technique that uses children’s drawings and a simultaneous talk with children to reveal voices of marginalization. We first define the technique by presenting its theoretical background and then illustrate how the method has been used. Using evidence from a school in Cyprus, we demonstrate how children’s drawings and simultaneous discussion with the creator of the drawing can help us develop a richer understanding of marginalization.
description: Παιδαγωγική Επιθεώρηση, Vol. 47 (2009)
Development and characteristics of the HANARO ex-core neutron irradiation facility for applications in the boron neutron capture therapy field
Creators: name: Kim, Myong-Seop
name: Lee, Byung-Chul
name: Hwang, Sung-Yul
name: Kim, Heonil
name: Jun, Byung-Jin
Publisher: name: arXiv
Year: 2006
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: The HANARO ex-core neutron irradiation facility was developed for various applications in the boron neutron capture therapy (BNCT) field, and its characteristics have been investigated. In order to obtain a sufficient thermal neutron flux with a low level contamination of fast neutrons and gamma-rays, a radiation filtering method is adopted. The radiation filter has been designed by using a silicon single crystal cooled by liquid nitrogen and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room are finished. Experimental measurements of the neutron beam characteristics have been performed by using bare and cadmium covered gold foils and wires. The in-phantom neutron flux distribution was measured for a flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio which can be obtained at this facility are 1.49E9 n/cm2s and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79E9 n/cm2s at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and the significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition is expected to be about 80 cGy/hr. These experimental results are reasonably well supported by the calculated values of the facility design code. This HANARO thermal neutron facility can be used not only for a clinical trial but also for various basic irradiation researches of the BNCT field.
description: 15 pages including 10 figures and 5 tables
Διαχείριση φάσματος με χρήση εξελικτικών αλγορίθμων:
Creators: name: Τέγου, Θωμάς Ηρακλή
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Διαχείριση φάσματος
Εξελικτικοί αλγόριθμοι
Βιογεωγραφική βελτιστοποίηση
Spectrum allocation
Cognitive radio
Evolutionary algorithms

description: Η δυναμική διαχείριση του φάσματος είναι περισσότερο αναγκαία τα τελευταία χρόνια λόγω της αυξημένης ζήτησης ελεύθερων συχνοτήτων. Η διαχείριση φάσματος σε Cognitive Radio δίκτυα αναφέρεται στον βέλτιστο διαμοιρασμό των καναλιών που χρησιμοποιούνται από τους κύριους χρήστες στους δευτερεύοντες χρήστες μιας τοπολογίας, χωρίς να προκαλούνται παρεμβολές. Αυτός ο διαμοιρασμός γίνεται βάση τριών συναρτήσεων κόστους : την Max Sum Reward, που αυξάνει την συνολική ανταμοιβή των δευτερευόντων χρηστών, την Max Min Reward που συμπεριλαμβάνει την έννοια της δικαιοσύνης στον καταμερισμό των καναλιών μεταξύ των δευτερευόντων χρηστών και τέλος την Max Proportional Fair Reward. Οι συναρτήσεις κόστους ποσοτικοποιούν την ανταμοιβή των δευτερευόντων χρηστών και στόχος είναι η μεγιστοποίηση τους, αυτό επιτυγχάνεται, στην παρούσα διπλωματική με τέσσερις αλγορίθμους βελτιστοποίησης: τον BBO (Biogeography Based Optimization), τον CBBO (Chaotic Biogeography Based Optimization), τον GA (Genetic Algorithm) και τον ACO (Ant Colony Optimization). Γίνονται προσομοιώσεις για διάφορες τοπολογίες με διάφορα πλήθη χρηστών και συγκρίνονται οι αλγόριθμοι. Τέλος παρουσιάζονται κάποιες αλλαγές που έγιναν στους ρυθμούς μετανάστευσης λ και μ και στον ρυθμό μετάλλαξης με τις οποίες βελτιώθηκαν οι επιδόσεις των αλγορίθμων ΒΒΟ και CBBO για το συγκεκριμένο πρόβλημα.
description: In recent years the demand for wireless spectrum has been growing dramatically, therefore a more dynamic way of spectrum allocation is necessary. The aim of spectrum allocation problem is to distribute with the best way available channels to secondary users without causing interference. Secondary users reward can be expressed through three fitness functions: Max Sum Reward, which represents the overall reward of secondary users, Max Min Reward, which represents the reward for the bottleneck user and Max Proportional Fair Reward. Four optimization algorithms are used to maximize these fitness functions ΒΒΟ (Biogeography Based Optimization) CBBO (Chaotic Biogeography Based Optimization), GA (Genetic Algorithm) and ACO (Ant Colony Optimization). The performances of these algorithms are compared for different topologies with different numbers of primary and secondary users. Finally some changes to migration (λ ,μ) and mutation rates are introduced to increase performance of BBO and CBBO to the specific problem.
On the Decay of Sunspot Groups and Their Internal Parts in Detail
Creators: name: Muraközy, Judit
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The decay of sunspot groups is a relatively unknown field since most studies have focused mainly on the decay of sunspots or sunspot groups, but only on small samples. As an extension of the recent work of \citet{2020ApJ...892..107M} which is based on a large verified sample, this study investigates not only the long-term behavior of the decay of sunspot groups but also the dynamics of their parts. The aim of the present work is to search for dependencies of the decay process in order to find physical conditions that modify or contribute to the decay. The investigations are based on the catalog of SoHO Debrecen Sunspot Database (SDD ) and the Greenwich Photoheliographic Results (GPR) as well as the Debrecen Photoheliographic Data (DPD). Altogether more than 750 sunspot groups were considered. The decay rates have been calculated for the total, umbral and penumbral area of the groups and in the case of the SDD's groups they have been calculated for both the leading and the following parts. The decay rates depend linearly on the maximum areas and ranged from 30-50 MSH/day for the sunspot groups and penumbrae and 5-10 MSH/day for the umbrae throughout the cycle. The decay rates fall significantly during the Gnevyshev gap and show 4+4 Schwabe cyclical variations in the ascending/descending phases, but it is always higher in the northern hemisphere. There is a slight decrease of the decay rates in the activity range toward higher latitudes.
description: 14 pages, 9 figures, accepted for publication in ApJ
Οργάνωση και δράση προσφυγικών σωματείων στη Θεσσαλονίκη 1922-1936:
Creators: name: Ρούμελη, Παρασκευή Δημητρίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Προσφυγικά
Σωματεία
Θεσσαλονίκη
Refugee
Associations
Thessaloniki

description: Σκοπός της διατριβής ήταν η μελέτη της οργάνωσης, της δομής και της δράσης των προσφυγικών σωματείων στη Θεσσαλονίκη μεταξύ 1922-1936. Μελετήσαμε τα καταστατικά και τα πρακτικά ίδρυσης περίπου 100 προσφυγικών συλλόγων, ενώ παράλληλα μελετήθηκαν και οι τοπικές εφημερίδες της εποχής, η Μακεδονία και η Εφημερίδα των Βαλκανίων. Τα σωματεία κατηγοριοποιήθηκαν με βάση τους στόχους που έθεταν οι ιδρυτές στα καταστατικά, από όπου αντλήθηκαν και οι πληροφορίες για τη δομή και την οργάνωσή τους. Οι πληροφορίες για τη δράση των προσφυγικών σωματείων στηρίχθηκαν στα φύλλα των εφημερίδων. Επιπρόσθετα, υπάρχει και ένα ειδικό υποκεφάλαιο που αφορά την πολιτική δράση των οργανώσεων αυτών. Τέλος, τη διατριβή συνοδεύουν πλήρως ενημερωμένα παραρτήματα που περιέχουν όλα τα προσφυγικά σωματεία της Θεσσαλονίκης που βρέθηκαν από τις εφημερίδες.
description: The aim of the present thesis was to study the organization, structure and action of refugee associations in Thessaloniki between 1922-1936. We studied the statutes and the practical of foundation of about 100 refugee associations, and at the same time we studied the local newspapers of the time, Macedonia and the Journal of the Balkans. The refugee corporations were classified according to the objectives assigned by the founders in the statutes, from where we also extracted the information about their structure and organization. The information on the effect of refugee associations was based on the newspapers. Additionally, there is a special sub-chapter on the political activity of these organizations. Finally, the thesis is accompanied by fully updated annexes containing all refugee associations in Thessaloniki found in newspapers.
Οδοιπορικό μετάβασης στην αγορά εργασίας των αποφοίτων τριτοβάθμιας εκπαίδευσης της Κύπρου.
Creators: name: Μελετίου-Μαυροθέρη, Μαρία
name: Μαούρη, Χρυστάλλα
name: Χατζηχρήστου, Χρυσή Γ.
Publisher: name: Παιδαγωγική Επιθεώρηση
Year: 2015

description: The study aims to explore the outcomes of locally received higher education in Cyprus in terms of subsequent employment. The study included the entire graduating class of 2003 (N=2180) in both the public and the private higher education sector in Cyprus. The students were administered a questionnaire shortly before graduation concerning their background, educational experi¬ences, future plans and job seeking skills. The second phase of the study was a follow up survey approximately one and a half year after graduation exam¬ining the transition of this cohort into the workplace. In particular we explored the types of jobs and salaries the graduates received, their job satisfaction, an their perceptions on the usefulness of their degree and its relevance their current job requirements. This article utilizes some of the data collected through the longitudinal study to draw the profile of Cypriot students graduating from local higher education institutions and to depict their transition from college to labor force.
description: Παιδαγωγική Επιθεώρηση, Vol. 47 (2009)
Search for extrasolar planets with high-precision relative astrometry
Creators: name: Roell, T.
name: Seifahrt, A.
name: Neuhäuser, R.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present our search program for substellar companions using high-precision relative astronomy. Due to its orbital motion around the star, an unseen substellar companion would produce a periodic "wobble" of the host star, which is the astrometric signal of the unseen companion. By measuring the separation between the components of stellar double and triple systems, we want to measure this astrometric signal of a possible unseen companion indirectly as a relative and periodic change of these separations. Using a new observation mode (the "cube-mode") where the frames were directly saved in cubes with nearly no loss of time during the readout, an adaptive optics system to correct for atmospheric noise and an infrared narrow band filter in the near infrared to suppress differential chromatic refraction (DCR) effects we achive for our first target (the double star HD 19994) a relative precision for the separation measurements of about 100...150 micro-arsecond per epoch. To reach a precision in the micro-arcsec-regime, we use a statistical approach. We take several thousand frames per target and epoche and after a verification of a Gaussian distribution the measurement precision can be calculated as the standard deviation of our measurements divided by the square root of the number of Gaussian distributed measurements. Our first observed target is the stellar binary HD 19994 A & B, where the A component has a known radial velocity planet candidate.
description: 4 pages, IAUS 249 conference
Radio telescope total power mode: improving observation efficiency
Creators: name: Pagani, Laurent
name: Frayer, David
name: Pagani, Bruno
name: Lefèvre, Charlène
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Aims. Radio observing efficiency can be improved by calibrating and reducing the observations in total power mode rather than in frequency, beam, or position-switching modes. Methods. We selected a sample of spectra obtained from the Institut de Radio-Astronomie Millimétrique (IRAM) 30-m telescope and the Green Bank Telescope (GBT) to test the feasibility of the method. Given that modern front-end amplifiers for the GBT and direct Local Oscillator injection for the 30 m telescope provide smooth pass bands that are a few tens of megahertz in width, the spectra from standard observations can be cleaned (baseline removal) separately and then co-added directly when the lines are narrow enough (a few km/s), instead of performing the traditional ON minus OFF data reduction. This technique works for frequency-switched observations as well as for position- and beam-switched observations when the ON and OFF data are saved separately. Results. The method works best when the lines are narrow enough and not too numerous so that a secure baseline removal can be achieved. A signal-to-noise ratio improvement of a factor of sqrt(2) is found in most cases, consistent with theoretical expectations. Conclusions. By keeping the traditional observing mode, the fallback solution of the standard reduction technique is still available in cases of suboptimal baseline behavior, sky instability, or wide lines, and to confirm the line intensities. These techniques of total-power-mode reduction can be applied to any radio telescope with stable baselines as long as they record and deliver the ONs and OFFs separately, as is the case for the GBT.
description: 8 pages, 12 figures, A&A in press
Axion-Like Particles at the ILC Giga-Z
Creators: name: Steinberg, Noah
name: Wells, James D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Axion-Like Particles (ALPs) are a generic, calculable, and well motivated extension of the Standard Model with far reaching phenomenology. ALPs that couple only to hypercharge represent one subset of such models, coupling the ALP to both photons and the $Z$ boson. We examine the current constraints on this class of models with an ALP mass in the 100 MeV to 100 GeV range, paying particular attention to the region between 100 MeV to 10 GeV, a portion of parameter space which is ill constrained by current experiments. We show that the more than $10^{9}$ $Z$ bosons produced in the Giga-Z mode of the future ILC experiment, combined with the highly granular nature of its detectors, will allow for ALPs coupled to hypercharge to be discovered with couplings down to nearly $10^{-5}\,\rm{GeV^{-1}}$ over a range of masses from 0.4 to 50 GeV.
description: 18 pages, 10 figures
Δύο μελέτες περίπτωσης για την κατανομή του χρόνου μιας διευθύντριας και ενός διευθυντή δημοτικού σχολείου.
Creators: name: Κυριάκου, Κυριάκου
name: Λοϊζίδου, Χαρά
name: Παναγή, Παναγιώτης
name: Χαραλάμπους, Ανθή
name: Πασιαρδής, Πέτρος
Publisher: name: Παιδαγωγική Επιθεώρηση
Year: 2015

description: How do school principals allocate their time in today’s constantly changing environment? This question is the starting point of the present paper that deals with time management and specifically the way school principals use and al¬locate their working time during the exercise of their duties. In particular, the findings of the research were drawn from the shadowing of two principals, the one in an urban and the other in a rural primary school in Nicosia, Cyprus. Both principals were shadowed for a week. The data analysis reveals the main 
which each principal allocates his/her time and a comparison between carried out. At the same time, the research findings are compared with ings of similar studies in Cyprus as well as abroad.
description: Παιδαγωγική Επιθεώρηση, Vol. 47 (2009)
A New Quasi-local Mass and Positivity
Creators: name: Zhang, Xiao
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Differential Geometry (math.DG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We use an idea of Wang and Yau to give a new definition of quasi-local mass for a topological sphere in an initial date set. The new definition modifies Brown-York's definition by using certain spinor norm as lapse function. And it requires mean curvature of the topological sphere satisfies apparent horizon conditions, the topological sphere can be isometrically into Euclidean 3-space and mean curvature of the initial date set does not change sign. The positivity holds if we further assume the image of the topological sphere in Euclidean 3-space has nonnegative mean curvature.
description: 13 pages, final version, the limiting case in Theorem 1 corrected, remark 1 and new references added, Acta Mathematica Sinica (English Series), to appear
Modeling of steady state heat release, oxygen profile and temperature profile in circulating fluidized bed combustors
Creators: name: Ju, Dale Wen-Ching
Publisher: name: University of British Columbia
Year: 2009

description: A computer model, using the Monte Carlo method, was developed to predict heat release, oxygen profiles and temperature profiles in Circulating Fluidized Bed (CFB) combustors. The model includes initial devolatilization of the coal feed, a correction in the evolved volatiles region based on the plume model, char combustion, an oxygen mass balance to determine the oxygen profile, and an energy balance to detenriine the temperature profile. The highly non-linear energy balance equation includes conduction, particle and gas convection and radiative heat transfer terms. A number of studies were conducted to observe how the model's prediction changes with superficial gas velocities of 6 m/s and 7 m/s, and solids recirculation rates of 15, 30 and 50 kg/m²s, for both the UBC CFB and the Studsvik CFB. A validation of the model's partial pressure of oxygen profile predictions compared to experimental data was made for the UBC CFB test case.
Επίδραση των πίστεων για την υγεία στη διαμόρφωση των αντιλήψεων για το ντόπινγκ στον αθλητισμό. Εμπειρική μελέτη σε νεαρούς ποδοσφαιριστές:
Creators: name: Βλαχονάσιος, Αθανάσιος Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Φαρμακοδιέγερση
Μοντέλο των πίστεων για την υγεία
Doping
Health belief model

description: Το μοντέλο πεποιθήσεων για την υγεία (Health Belief Model – HBM) είναι ένα μοντέλο που αναπτύχθηκε το 1950 και αποτελεί κατ’ ουσία ένα μοντέλο για την ατομική τροποποίηση της συμπεριφοράς στην υγεία. Προσπαθεί να εξηγήσει τις διαδικασίες της σκέψης που οδηγούν υιοθέτηση μια υγιεινής συμπεριφοράς. Σκοπός της μελέτης αυτής ήταν να διερευνηθούν οι επιδράσεις των πεποιθήσεων για την υγεία στη διαμόρφωση των αντιλήψεων για το ντόπινγκ στο αθλητισμό, σε νεαρούς ποδοσφαιριστές. Στην έρευνα συμμετείχαν 312 έφηβοι αθλητές ποδοσφαίρου ηλικίας 14 έως 16 ετών. Οι αθλητές που συμμετείχαν στην έρευνα προέρχονταν από ακαδημίες του νομού Θεσσαλονίκης και του νομού Τρικάλων. Τα αποτελέσματα έδειξαν ότι η Βραχυπρόθεσμη Πρόθεση, η Μακροπρόθεσμη Πρόθεση και ο Πειρασμός για χρήση ουσιών ντόπινγκ είχαν στατιστικά σημαντική επίδραση στην πιθανότητα για χρήση ντόπινγκ στον αθλητισμό. Η επίδραση των μεταβλητών αυτών έγινε διαμέσου της Αντιλαμβανόμενης Επιδεκτικότητας, της Σοβαρότητας αλλά και της Αντίληψης της Απειλής. Επίσης, οι ενδείξεις προέβλεψαν σημαντικά την βραχυπρόθεσμη και μακροπρόθεσμη χρήση ουσιών ντόπινγκ. Τέλος, τα αποτελέσματα κατέδειξαν ότι η αισιοδοξία, η ηλικία, η γνώση, το κόστος και το όφελος δεν πρόβλεψαν σημαντικά την βραχυπρόθεσμη και τη μακροπρόθεσμη χρήση ουσιών ντόπινγκ. Από τα αποτελέσματα της έρευνας προκύπτουν σημαντικές πληροφορίες για την επίδραση των πεποιθήσεων για την υγεία στη διαδικασία λήψης απόφασης για τη χρήση ουσιών ντόπινγκ από νεαρούς αθλητές.
description: The Health Belief Model is a model developed in 1950 and is essentially a model developed to foster individual behavior modification towards health by trying to explain the thought processes that are associated to the adoption of a healthy behavior. The purpose of this study was to investigate the role of health beliefs in shaping in young football players doping perceptions in sport. The sample of the study consisted of 312 adolescents football players aged 14-16 years old. Participants were attending football sport academies in Thessaloniki and Trikala. The results of the analyses showed that short-term Intention, long-term Intention and the Temptation to use doping substances produced a statistically significant effect on the probability for using doping in sport. This effect was mediated by Perceived Susceptibility, Severity and Threat Perception. Also, the signs predicted significantly short- and long-term use of doping substances. Finally, the results of the analyses showed that optimism, age, knowledge, costs and benefits were not significant predictors of the possibility for short-term and long-term use of doping substances. The study’s findings provide important information with respect to the influence of health beliefs on decision-making process regarding use of doping substances among young athletes.
Instrumental Variable Quantile Regression
Creators: name: Chernozhukov, Victor
name: Hansen, Christian
name: Wuthrich, Kaspar
Publisher: name: arXiv
Year: 2020
Subjects: subject: Econometrics (econ.EM)
subject: FOS: Economics and business

description: This chapter reviews the instrumental variable quantile regression model of Chernozhukov and Hansen (2005). We discuss the key conditions used for identification of structural quantile effects within this model which include the availability of instruments and a restriction on the ranks of structural disturbances. We outline several approaches to obtaining point estimates and performing statistical inference for model parameters. Finally, we point to possible directions for future research.
description: arXiv admin note: substantial text overlap with arXiv:1303.7050
Το ντροπαλό παιδί όπως το βλέπουν οι εκπαιδευτικοί.
Creators: name: Καραμπατζάκη, Μαρία
name: Κόκκινος, Κωνσταντίνος Μ.
Publisher: name: Παιδαγωγική Επιθεώρηση
Year: 2015

description: One hundred and sixty seven primary school teachers were asked to report their views on 78 items describing both internalizing and externalizing behav¬iors in children, in terms of a. whether the behavior was indicative of shyness, and b. the degree of perceived seriousness of those behaviors which according to their views were indicative of shyness. The results revealed that teachers did not seem to have a clear picture of the behavioral characteristics of shyness. While they tended to attribute the correct behavior characteristics to shyness, they were not able to distinguish it from other internalizing behaviors such as social withdrawal, depression, and behavioral inhibition. A great number of' teachers reported incorrect or imperfect knowledge by attributing also exter¬nalizing behaviors to shyness. In terms of the degree of perceived seriousness of those behaviors perceived as indicative of shyness, most of them were rated as fairly serious, similarly to those behaviors indicative of externalizing symp¬toms, but not relevant to shyness. The results are discussed in terms of their implications to teacher training programs.
description: Παιδαγωγική Επιθεώρηση, Vol. 47 (2009)