cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Μοντελοποίηση της διάδοσης του νευρικού ερεθίσματος: ηλεκτρομηχανική θεώρηση
Creators: name: Τσιτλακίδης, Αβραάμ Κωνσταντίνου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Δυναμικό δράσης
Μηχανική παραμόρφωση
Νευράξονας
Action potential
Mechanical deformation
Axon

description: Ένας παράγοντας που ελάχιστα έχει μελετηθεί στην παθοφυσιολογία διαφόρων καταστάσεων είναι η επίδραση της μη καταστοφικής μηχανικής παραμόρφωσης στη λειτουργία των νευρικών κυττάρων, δηλαδή την παραγωγή και διάδοση του δυναμικού δράσης. Αφού αναλυθούν προϋπάρχοντα μοντέλα, για τη μελέτη της σύζευξης των μηχανικών και ηλεκτρικών ιδιοτήτων του νευρικού κυττάρου, προτείνονται μοντέλα που βασίζονται στις εξισώσεις των Fitzhugh και Nagumo και στη θεώρηση του νευράξονα τόσο ως ένα σύνολο ηλεκτρικών στοιχείων όσο και ως υλικού. Συγκεκριμένα, μελετάται το φαινόμενο του καμπτοηλεκτρισμού και της επίδρασης της παραμόρφωσης της κυτταρικής μεμβράνης στην κινητική των διαύλων καλίου, δηλαδή στο ρυθμό ενεργοποίησης και απενεργοποίησής τους, αλλά και της εμφάνισης χρονοκαθυστέρησης. Ακόμη, αναλύονται μεταβολές στην ταχύτητα διάδοσης του νευρικού ερεθίσματος που οφείλονται στην παραμόρφωση του νευράξονα. Τα μοντέλα που αναπτύσσονται υποστηρίζονται από πειραματικά δεδομένα, παρότι η μελέτη τέτοιων φαινομένω παρουσίάζει ιδιαίτερες τεχνικές δυσκολίες. Η ηλεκτρομηχανική θεώρηση της διάδοσης του νευρικού ερεθίσματος αποτελεί ένα πεδίο με ιδιαίτερα σημαντικό κλινικό ενδιαφέρον, αλλά και ευρείες προοπτικές για περαιτέρω έρευνα.
description: A least studied factor in the pathophysiology of various diseases is the influence of non-destructive mechanical deformation on the function of the neural cells, namely the formation and propagation of the action potential. After having analyzed existing models, in order to study the coupling of the mechanical and electrical properties of the neural cell, models based on the equations of Fitzhugh and Nagumo and the consideration of the axon both as a set of electrical elements and as a material are suggested. In specific, flexoelectricity and the effect of the deformation of the cellular membrane on the kinetics of potassium channels is studied, namely their activation and inactivation pace, as well as the appearance of time delay. Furthermore, changes in the propagation velocity of the neural impulse due to the deformation of the axon are analyzed. The suggested models are supported by experimental results, although the study of such phenomena is particularly arduous. The electromechanical consideration of the propagation of the neural impulse is a field with very important clinical implications and wide perspectives for further research.
Renormalization of two-loop diagrams in scalar lattice field theory
Creators: name: Borasoy, B.
name: Krebs, H.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We present a method to calculate to very high precision the coefficients of the divergences occuring in two-loop diagrams for a massive scalar field on the lattice. The approach is based on coordinate space techniques and extensive use of the precisely known Green's function.
description: 22 pages, 2 figures, additional results included
DeepiSign: Invisible Fragile Watermark to Protect the Integrityand Authenticity of CNN
Creators: name: Abuadbba, Alsharif
name: Kim, Hyoungshick
name: Nepal, Surya
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Convolutional Neural Networks (CNNs) deployed in real-life applications such as autonomous vehicles have shown to be vulnerable to manipulation attacks, such as poisoning attacks and fine-tuning. Hence, it is essential to ensure the integrity and authenticity of CNNs because compromised models can produce incorrect outputs and behave maliciously. In this paper, we propose a self-contained tamper-proofing method, called DeepiSign, to ensure the integrity and authenticity of CNN models against such manipulation attacks. DeepiSign applies the idea of fragile invisible watermarking to securely embed a secret and its hash value into a CNN model. To verify the integrity and authenticity of the model, we retrieve the secret from the model, compute the hash value of the secret, and compare it with the embedded hash value. To minimize the effects of the embedded secret on the CNN model, we use a wavelet-based technique to transform weights into the frequency domain and embed the secret into less significant coefficients. Our theoretical analysis shows that DeepiSign can hide up to 1KB secret in each layer with minimal loss of the model's accuracy. To evaluate the security and performance of DeepiSign, we performed experiments on four pre-trained models (ResNet18, VGG16, AlexNet, and MobileNet) using three datasets (MNIST, CIFAR-10, and Imagenet) against three types of manipulation attacks (targeted input poisoning, output poisoning, and fine-tuning). The results demonstrate that DeepiSign is verifiable without degrading the classification accuracy, and robust against representative CNN manipulation attacks.
description: The 36th ACM SIGAPP Symposium on Applied Computing (ACM SAC)
Efficient Response to Cascading Disaster Spreading
Creators: name: Buzna, Lubos
name: Peters, Karsten
name: Ammoser, Hendrik
name: Kuehnert, Christian
name: Helbing, Dirk
Publisher: name: arXiv
Year: 2006
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: We study the effectiveness of recovery strategies for a dynamic model of failure spreading in networks. These strategies control the distribution of resources based on information about the current network state and network topology. In order to assess their success, we have performed a series of simulation experiments. The considered parameters of these experiments are the network topology, the response time delay and the overall disposition of resources. Our investigations are focused on the comparison of strategies for different scenarios and the determination of the most appropriate strategy. The importance of prompt response and the minimum sufficient quantity of resources are discussed as well.
description: 8 pages, 6 figures
YOUTUBE VIDEO UTILIZATION TO ENHANCE THE STUDENTS GRAMMATICAL COMPETENCE
Creators: name: Muico, Earl Jones
Publisher: name: figshare
Year: 2022
Subjects: subject: 200401 Applied Linguistics and Educational Linguistics
subject: FOS: Languages and literature
subject: 130306 Educational Technology and Computing
subject: FOS: Educational sciences

description: Innovative language teaching strategies are necessary for language teachers. This quasi experimental study sought to determine the grammatical competence of the participants after watching YouTube videos. The constructs included were: phonology, morphology, syntax and vocabulary. Specifically, the study utilized the one-group, pre-posttest design which involved 45 second year Business Administration major in Marketing Management students of the University of Mindanao Tagum College. To gather the necessary data, the researcher developed a questionnaire which underwent the validity and reliability test. In addition, lesson logs were used to incorporate the utilization of YouTube in the lesson. The experiment lasted for 10 days with an hour allotted for each day. The study revealed that after the utilization of YouTube in the class, there was an evident improvement in the scores of the participants; there was also a significant difference on the mean gain scores of the pre and posttest of the experimental group; thus, the study rejected the null hypotheses. Based on the result, the researcher recommends that language teachers should utilize YouTube videos in the classroom because of its positive effects on the students’ grammatical competence.
On the sensitivity, selectivity, sensory information and optimal size of resistive chemical sensors
Creators: name: Kish, Laszlo B.
name: Smulko, Janusz
name: Heszler, Peter
name: Granqvist, Claes-Goran
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Physics (physics.gen-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Information theoretical tools are applied for the study of the sensitivity and selectivity enhancements of resistive fluctuation-enhanced sensors. General considerations are given for the upper limit of selectivity enhancement. The signal-to-noise ratio and information channel capacity of fluctuation-enhanced chemical sensors is compared to that of classical sensors providing a single output. The considerations are done at the generic level with a few concrete examples and include the estimation of scaling relations between the sensor size, speed of measurements, sampling rate, measurement time, signal power and noise power.
description: Second version of draft/preprint of invited paper in the journal Nanotechnology Perceptions. Small corrections
Informal settlement upgrading in Durban, South Africa : building institutional capacity to sustain the improvement process
Creators: name: Van Horen, Basil
Publisher: name: University of British Columbia
Year: 2009

description: This research examines the planning of the Besters Camp informal settlement in-situ upgrading project in Durban, South Africa. International experience indicates that in-situ upgrading has generally been successful in delivering services to the urban poor. It also confirms, however, that benefits of upgrading are mostly confined to project localities, and that the institutional capacity necessary for ongoing improvement in the lives of settlement residents is seldom created. Drawing from experience as a planner in some of South Africa's first generation of settlement upgrading projects, this research focuses on the question of how informal settlement upgrading can be planned in order to contribute to the continuity of the settlement improvement process. An important implication of the 'informalization' process in many Third World cities is that parts of cities in which the de facto rules of the game are dominant are growing considerably more rapidly than the 'formal city', which is governed according to the de jure instruments of control, such as statutory law, planning regulation, and legal administrative authority. In this context, the most common approach to planning the upgrading of shack settlements is to attempt to legalize, or 'formalize the informal'. Experience in Besters Camp upgrade elucidates ways of moving beyond a narrow focus on legalization, and onto more flexible regularization strategies. These strategies attempt to bridge the gap between de jure and de facto systems by integrating elements of both into the planning process, and thereby contributing to an amended legal regulatory framework appropriate to planning in informal settlements. Regularization involves putting in place the institutions - that is, the norms and structures - that are economically and politically viable, and which have the potential to carry the consolidation process forward into the longer term. Regularization takes as its starting point the delivery of services, which provides an activity into which capacity building initiatives can be integrated. Importantly, in order to sustain the impacts of upgrading projects, it is necessary to connect local settlement-level institutions and metropolitan-level institutions in such a way as to provide a relationship of complementary autonomy at both levels.
Kinetics of a Network of Vortex Loops in He II and a Theory of Superfluid Turbulence
Creators: name: Nemirovskii, Sergey K.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A theory is developed to describe the superfluid turbulence on the base of kinetics of the merging and splitting vortex loops. Because of very frequent reconnections the vortex loops (as a whole) do not live long enough to perform any essential evolution due to the deterministic motion. On the contrary, they rapidly merge and split, and these random recombination processes prevail over other slower dynamic processes. To develop quantitative description we take the vortex loops to have a Brownian structure with the only degree of freedom, which is the length $l$ of the loop. We perform investigation on the base of the Boltzmann type kinetic equation for the distribution function $n(l)$ of number of loops with length $l$. By use of the special ansatz in the collision integral we have found the exact power-like solution to kinetic equation in the stationary case. This solution is not (thermodynamically) equilibrium, but on the contrary, it describes the state with two mutual fluxes of the length (or energy) in space of sizes of the vortex loops. The term flux means just redistribution of length (or energy) among the loops of different sizes due to reconnections. Analyzing this solution we drew several results on the structure and dynamics of the vortex tangle in the turbulent superfluid helium. In particular, we evaluated the mean radius of the curvature and the full rate of the reconnection events. We also studied the evolution of the full length of vortex loops per unit volume-the so-called vortex line density. It is shown this evolution to obey the famous Vinen equation. The properties of the Vinen equation from the point of view of the developed approach had been discussed.
description: 34 pages, 9 Postscript figures, [aps,preprint,12pt]{revtex4}
Electronic states of laterally coupled quantum rings
Creators: name: Planelles, J.
name: Rajadell, F.
name: Climente, J. I.
name: Royo, M.
name: Movilla, J. L.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The conduction band electron states of laterally-coupled semiconductor quantum rings are studied within the frame of the effective mass envelope function theory. We consider the effect of axial and in-plane magnetic fields for several inter-ring distances, and find strong changes in the energy spectrum depending on the coupling regime. Our results indicate that the magnetic response accurately monitors the quantum ring molecule dissociation process. Moreover, the anisotropic response of the electron states to in-plane magnetic fields provides information on the orientation of the quantum ring molecule.
description: 7 pages, 4 figures, submitted to proceedings of ICN+T 2006 (Basel) -J.Phys. Conference Series
Quasi-elastic solutions to the nonlinear Boltzmann equation for dissipative gases
Creators: name: Barrat, Alain
name: Trizac, E.
name: Ernst, M. H.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The solutions of the one-dimensional homogeneous nonlinear Boltzmann equation are studied in the QE-limit (Quasi-Elastic; infinitesimal dissipation) by a combination of analytical and numerical techniques. Their behavior at large velocities differs qualitatively from that for higher dimensional systems. In our generic model, a dissipative fluid is maintained in a non-equilibrium steady state by a stochastic or deterministic driving force. The velocity distribution for stochastic driving is regular and for infinitesimal dissipation, has a stretched exponential tail, with an unusual stretching exponent $b_{QE} = 2b$, twice as large as the standard one for the corresponding $d$-dimensional system at finite dissipation. For deterministic driving the behavior is more subtle and displays singularities, such as multi-peaked velocity distribution functions. We classify the corresponding velocity distributions according to the nature and scaling behavior of such singularities.
Large-scale Huygens metasurfaces for holographic 3D near-eye displays
Creators: name: Song, Weitao
name: Liang, Xinan
name: Li, Shiqiang
name: Li, Dongdong
name: Paniagua-Dominguez, Ramon
name: Lai, Keng Heng
name: Lin, Qunying
name: Zheng, Yuanjin
name: Kuznetsov, Arseniy I.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Novel display technologies aim at providing the users with increasingly immersive experiences. In this regard, it is a long-sought dream to generate three-dimensional (3D) scenes with high resolution and continuous depth, which can be overlaid with the real world. Current attempts to do so, however, fail in providing either truly 3D information, or a large viewing area and angle, strongly limiting the user immersion. Here, we report a proof-of-concept solution for this problem, and realize a compact holographic 3D near-eye display with a large exit pupil of 10mm x 8.66mm. The 3D image is generated from a highly transparent Huygens metasurface hologram with large (>10^8) pixel count and subwavelength pixels, fabricated via deep-ultraviolet immersion photolithography on 300 mm glass wafers. We experimentally demonstrate high quality virtual 3D scenes with ~50k active data points and continuous depth ranging from 0.5m to 2m, overlaid with the real world and easily viewed by naked eye. To do so, we introduce a new design method for holographic near-eye displays that, inherently, is able to provide both parallax and accommodation cues, fundamentally solving the vergence-accommodation conflict that exists in current commercial 3D displays.
description: 21 pages, 9 figures
Mathisson Equations: Non-Oscillatory Solutions in a Schwarzschild Field
Creators: name: Plyatsko, Roman
name: Stefanyshyn, Oleksandr
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The Mathisson equations under the Frenkel-Mathisson supplementary condition are studied in a Schwarzschild field. The choice of solutions, which describe the motions of the proper center of mass of a spinning test particle, is discussed, and the calculation procedure for highly relativistic motions is proposed. The very motions are important for astrophysics while investigating possible effects of the gravitational spin-orbit interaction on the particle's world line and trajectory.
description: 11 pages, 3 figures
Ευρωμεσογειακή Συνεργασία και Ένωση για τη Μεσόγειο
Creators: name: Κάντζα, Ευθυμία Ανδρέα
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Ένωση για τη Μεσόγειο
Ευρωμεσωγειακή Συνεργασία
Ευρωπαϊκές Εξωτερικές Σχέσεις
Union for the Mediterranean
Euro-Mediterranean Partnership
European/ EU External Relations

description: Με την παρούσα θα γίνει μία προσπάθεια σκιαγράφησης των ευρωμεσογειακών σχέσεων. Αρχικά θα τις εξετάσουμε μέσα από το πρίσμα των ευρωπαικών εξωτερικών σχέσεων και τον πολιτικών της Ευρωπαϊκής Ένωσης στον τομέα αυτό, με κυριότερη την Ευρωπαϊκή Πολιτική Γειτονίας, ενώ θα γίνει μία σύντομη παρουσίαση των δράσεων της Διαδικασίας της Βαρκελώνης. Στη συνέχεια θα ασχοληθούμε με τη νεοσύστατη Ένωση για τη Μεσόγειο, ως ένωση προγραμμάτων, στα οποία θα γίνει αναφορά και κυρίως σε ό, τι αφορά στο Μεσογειακό Σχέδιο Ηλιακής Ενέργειας.
description: The aim of the present thesis is to provide a scheme for the Euro - Mediterranean relations. Initially, these shall be seen in the light of the European Union’s External Relations taking into consideration all relevant EU policies, especially the European Neighbourhood Policy, and shortly discussing actions being launched under the Barcelona Process. Furthermore, the newly established Union for the Mediterranean shall be examined as a union of projects, to which reference shall be made with special regard to the Mediterranean Solar Plan.
Optical properties of current carrying molecular wires
Creators: name: Galperin, Michael
name: Nitzan, Abraham
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We consider several fundamental optical phenomena involving single molecules in biased metal-molecule-metal junctions. The molecule is represented by its highest occupied and lowest unoccupied molecular orbitals, and the analysis involves the simultaneous consideration of three coupled fluxes: the electronic current through the molecule, energy flow between the molecule and electron-hole excitations in the leads and the incident and/or emitted photon flux. Using a unified theoretical approach based on the non-equilibrium Green function method we derive expressions for the absorption lineshape (not an observable but a ueful reference for considering yields of other optical processes) and for the current induced molecular emission in such junctions. We also consider conditions under which resonance radiation can induce electronic current in an unbiased junction. We find that current driven molecular emission and resonant light induced electronic currents in single molecule junctions can be of observable magnitude under appropriate realizable conditions. In particular, light induced current should be observed in junctions involving molecular bridges that are characterized by strong charge transfer optical transitions. For observing current induced molecular emission we find that in addition to the familiar need to control the damping of molecular excitations into the metal substrate the phenomenon is also sensitive to the way in which the potential bias si distributed on the junction.
description: 56 pages, 8 figures; submitted to JCP
Relativistic Dynamics of Non-ideal Fluids: Viscous and heat-conducting fluids I. General Aspects and 3+1 Formulation for Nuclear Collisions
Creators: name: Muronga, Azwinndini
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Theory (nucl-th)
subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Relativistic non-ideal fluid dynamics is formulated in 3+1 space--time dimensions. The equations governing dissipative relativistic hydrodynamics are given in terms of the time and the 3-space quantities which correspond to those familiar from non-relativistic physics. Dissipation is accounted for by applying the causal theory of relativistic dissipative fluid dynamics. As a special case we consider a fluid without viscous/heat couplings in the causal system of transport/relaxation equations. For the study of physical systems we consider pure (1+1)-dimensional expansion in planar geometry, (1+1)-dimensional spherically symmetric ({\em fireball}) expansion, (1+1)-dimensional cylindrically symmetric expansion and a (2+1)-dimensional expansion with cylindrical symmetry in the transverse plane ({\em firebarell} expansion). The transport/relaxation equations are given in terms of the spatial components of the dissipative fluxes, since these are not independent. The choice for the independent components is analogous to the non-relativistic equations.
description: 49 pages, added references, typos added
Η εκπαιδευτική αξιοποίηση της παράδοσης ως μέσο αναγνώρισης του άλλου και βελτίωσης των κοινωνικών σχέσεων των παιδιών στο πολυπολιτισμικό νηπιαγωγείο.:
Creators: name: Ματθαιόπουλος, Ιωακείμ Συμεών
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Παράδοση
Κοινωνικές σχέσεις
Πολυπολιτισμικό νηπιαγωγείο
Tradition
Social relationships
Multicultural kindergarten

description: Στην Ελλάδα του 2012 οι περισσότεροι έλληνες μαθητές καλούνται να φοιτήσουν σε τάξεις πολυπολιτισμικών νηπιαγωγείων. Τα στερεότυπα και οι προκαταλήψεις όμως που αρκετοί φέρουν μαζί τους, τους δημιουργούν μια επικριτική στάση απέναντι στους αλλοδαπούς και συχνά τους οδηγούν σε συγκρούσεις μαζί τους. Ο νηπιαγωγός οφείλει να διαχειριστεί αυτήν την κατάσταση και να βοηθήσει τα παιδιά να καταλάβουν ότι αν και όλοι είμαστε διαφορετικοί, υπάρχουν πολλά κοινά σημεία που μας ενώνουν. Μέσα από ένα πρόγραμμα παρέμβασης, στο οποίο η παράδοση (κυρίως με τα έθιμα του Πάσχα) παίζει τον πρωτεύοντα ρόλο, θα προσπαθήσουμε να βοηθήσουμε τους μαθητές στην αναγνώριση του άλλων και στη βελτίωση των κοινωνικών τους σχέσεων.
description: In Greece of 2012, most of the Greek students are supposed to attend a multicultural kindergarten. The stereotypes and prejudices that many of them have create a critical attitude towards foreigners and often lead to conflicts with them. The kindergarten teacher has to manage this situation and help children understand that although we are all different, there are many commonalities that unite us. Through an intervention program in which tradition (mainly customs of Easter) plays a major role, we will try to help students to recognize each other and improve their social relations.
Van der Waals Ferromagnetic Josephson Junctions
Creators: name: Ai, Linfeng
name: Zhang, Enze
name: Huang, Ce
name: Xie, Xiaoyi
name: Yang, Yunkun
name: Jia, Zehao
name: Zhang, Yuda
name: Liu, Shanshan
name: Li, Zihan
name: Leng, Pengliang
name: Sun, Xingdan
name: Kou, Xufeng
name: Han, Zheng
name: Xiu, Faxian
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Superconductor-ferromagnet (S-F) interfaces in two-dimensional (2D) heterostructures present a unique opportunity to study the interplay between superconductivity and ferromagnetism. The realization of such nanoscale heterostructures in van der Waals (vdW) crystals remains largely unexplored due to the challenge of making an atomically-sharp interface from their layered structures. Here, we build a vdW ferromagnetic Josephson junction (JJ) by inserting a few-layer ferromagnetic insulator Cr2Ge2Te6 into two layers of superconductor NbSe2. Owing to the remanent magnetic moment of the barrier, the critical current and the corresponding junction resistance exhibit a hysteretic and oscillatory behavior against in-plane magnetic fields, manifesting itself as a strong Josephson coupling state. Through the control of this hysteresis, we can effectively trace the magnetic properties of atomic Cr2Ge2Te6 in response to the external magnetic field. Also, we observe a central minimum of critical current in some thick JJ devices, evidencing the coexistence of 0 and π phase coupling in the junction region. Our study paves the way to exploring the sensitive probes of weak magnetism and multifunctional building blocks for phase-related superconducting circuits with the use of vdW heterostructures.
High contrast at small separation -- II. Impact on the dark hole of a realistic optical set-up with two deformable mirrors
Creators: name: Beaulieu, M.
name: Martinez, P.
name: Abe, L.
name: Gouvret, C.
name: Baudoz, P.
name: Galicher, R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Future large space- or ground-based telescopes will offer the resolution and sensitivity to probe the habitable zone of a large sample of nearby stars for exo-Earth imaging. To this end, such facilities are expected to be equipped with a high-contrast instrument to efficiently suppress the light from an observed star to image these close-in companions. These observatories will include features such as segmented primary mirrors, secondary mirrors, and struts, leading to diffraction effects on the star image that will limit the instrument contrast. To overcome these constraints, a promising method consists in combining coronagraphy and wavefront shaping to reduce starlight at small separations and generate a dark region within the image to enhance the exoplanet signal. We aim to study the limitations of this combination when observing short-orbit planets. Our analysis is focused on SPEED, the Nice test bed with coronagraphy, wavefront shaping with deformable mirrors (DMs), and complex telescope aperture shape to determine the main realistic parameters that limit contrast at small separations. We develop an end-to-end simulator of this bench with Fresnel propagation effects to study the impact of large phase and amplitude errors from the test-bed optical components and defects from the wavefront shaping system on the final image contrast. We numerically show that the DM finite stroke and non-functional actuators, coronagraph manufacturing errors, and near-focal-plane phase errors represent the major limitations for high-contrast imaging of exoplanets at small separations. We also show that a carefully defined optical set-up opens the path to high contrast at small separation.
Tunneling in two dimensional QCD
Creators: name: Olesen, Poul
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: The spectral density for two dimensional continuum QCD has a non-analytic behavior for a critical area. Apparently this is not reflected in the Wilson loops. However, we show that the existence of a critical area is encoded in the winding Wilson loops: Although there is no non-analyticity or phase transition in these Wilson loops, the dynamics of these loops consists of two smoothly connected domains separated by the critical area, one domain with a confining behavior for large winding Wilson loops, and one (below the critical size) where the string tension disappears. We show that this can be interpreted in terms of a simple tunneling process between an ordered and a disordered state. In view of recent results by Narayanan and Neuberger this tunneling may also be relevant for four dimensional QCD.
description: 10 pages. Clarifying remarks have been added
Electronic correlations decimate the ferroelectric polarization of multiferroic HoMn2O5
Creators: name: Giovannetti, Gianluca
name: Brink, Jeroen van den
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We show that electronic correlations decimate the intrinsic ferroelectric polarization of the recently discovered class of multiferroic manganites RMn$_2$O$_5$, where R is a rare earth element. Such is manifest from {\it ab initio} bandstructure computations that account for the strong local Coulomb interactions between the manganese 3d electrons --the root of magnetism in these materials. When including these the computed electronic, magnetic and lattice structure of multiferroic HoMn$_2$O$_5$ results in an amplitude and direction of polarization that is in accordance with experiment. The microscopic mechanism behind the decimation is a near cancellation of the ionic polarization induced by ferroelectric lattice displacements and the electronic one caused by valence charge redistributions.
description: 4 pages, 4 figures
Optical Verification Experiments of Sub-scale Starshades
Creators: name: Harness, Anthony
name: Shaklan, Stuart
name: Willems, Phillip
name: Kasdin, N. Jeremy
name: Balasubramanian, K.
name: Dumont, Philip
name: White, Victor
name: Yee, Karl
name: Muller, Rich
name: Galvin, Michael
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Starshades are a leading technology to enable the detection and spectroscopic characterization of Earth-like exoplanets. In this paper we report on optical experiments of sub-scale starshades that advance critical starlight suppression technologies in preparation for the next generation of space telescopes. These experiments were conducted at the Princeton starshade testbed, an 80 m long enclosure testing 1/1000th scale starshades at a flight-like Fresnel number. We demonstrate 1e-10 contrast at the starshade's geometric inner working angle across 10% of the visible spectrum, with an average contrast at the inner working angle of 2.0e-10 and contrast floor of 2e-11. In addition to these high contrast demonstrations, we validate diffraction models to better than 35% accuracy through tests of intentionally flawed starshades. Overall, this suite of experiments reveals a deviation from scalar diffraction theory due to light propagating through narrow gaps between the starshade petals. We provide a model that accurately captures this effect at contrast levels below 1e-10. The results of these experiments demonstrate that there are no optical impediments to building a starshade that provides sufficient contrast to detect Earth-like exoplanets. This work also sets an upper limit on the effect of unknowns in the diffraction model used to predict starshade performance and set tolerances on the starshade manufacture.
description: 67 pages; 25 figures; submitted to Journal of Astronomical Telescopes, Instruments, and Systems
Is There Still a B -> pi K Puzzle?
Creators: name: Baek, Seungwon
name: London, David
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We perform a fit to the 2006 B -> pi K data and show that there is a disagreement with the standard model. That is, the B -> pi K puzzle is still present. In fact, it has gotten worse than in earlier years. Assuming that one new-physics (NP) operator dominates, we show that a good fit is obtained only when the electroweak penguin amplitude is modified. The NP amplitude must be sizeable, with a large weak phase.
description: 4 pages, revtex, no figures. References changed; analysis and conclusions unaltered
Ανάπτυξη και επικύρωση μεθόδου αέριας χρωματογραφίας με ανιχνευτή αζώτου-φωσφόρου για τον προσδιορισμό τριών αντιψυχωσικών φαρμάκων και ενός αντιχολινεργικού φαρμάκου σε ούρα μετά από εκχύλιση με ακροφύσιο μιας χρήσης (DPX)
Creators: name: Σταθάτος, Χρήστος Γεράσιμου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: αντιψυχωσικά φάρμακα
αέρια χρωματογραφία
εκχύλιση με ακροφύσιο μίας χρήσης
antipsychotic drugs
gas chromatography
Disposable Pipette Extraction

description: Η χρήση αντιψυχωσικών φαρμάκων εμφανίζει αλματώδη αύξηση. Επομένως, είναι απαραίτητη η διάθεση φθηνών, γρήγορων και αξιόπιστων μεθόδων, που θα επιτρέπουν την ανίχνευση και τον προσδιορισμό των φαρμάκων αυτών σε βιολογικά δείγματα. Στην παρούσα εργασία, η χλωροπρομαζίνη, η κλοζαπίνη, η ολανζαπίνη και η βιπεριδένη, προσδιορίστηκαν σε ούρα με την τεχνική της αέριας χρωματογραφίας (GC) με ανιχνευτή αζώτου-φωσφόρου (NPD), μετά από εκχύλιση με ακροφύσιο μιας χρήσης (DPX). Η μέθοδος που αναπτύχθηκε ήταν ικανοποιητική, γρήγορη και οικονομική. Η προκατεργασία των ούρων για την απομόνωση των συγκεκριμένων φαρμάκων, που πραγματοποιήθηκε για πρώτη φορά με την τεχνική DPX και τη χρήση προσροφητικού αντίστροφης φάσης, είχε ικανοποιητικά αποτελέσματα. Με τη μέθοδο που αναπτύχθηκε αναλύθηκαν επιτυχώς τρία διαφορετικά νεκροτομικά δείγματα ούρων.
description: There is an increasing use of antipsychotic drugs. Therefore, the availability of a cost-effective, fast and reliable method for their determination in biological samples is of utmost importance. Chlorpromazine, clozapine, olanzapine and biperiden were determined in urine by GC-NPD, following Disposable Pipette Extraction. The method currently developed satisfied the requirements, regarding cost and speed. DPX was used for the first time for the extraction of the particular drugs from urine and yielded acceptable results regarding precision, selectivity and reproducibility. The method currently developed and validated was successfully applied to the analysis of post mortem urine samples.
Archaeological landscapes of the Lower Mainland, British Columbia: a settlement study using a Geographic Information System
Creators: name: Beattie, William Grant
Publisher: name: University of British Columbia
Year: 2009

description: A selection of archaeological sites located in the Lower Mainland area of coastal British Columbia is used to test the use of the landscape in evaluating certain statements about prehistoric human settlement for the region. In total, 62 sites were chosen which show at least some evidence of occupation or limited activity use during the Marpole period (2400-1400 BP). The main problem in describing settlement strategies for this area is the inability to infer site use from subsistence or lithic assemblages recovered through either excavation or surface collection. This lack of information for the majority of the sites makes it impossible to use such traditional approaches to settlement analysis as determining sociopolitical relationships between locations or describing a seasonal round or movement from one type of site to another. An alternative approach to circumventing this dilemma is to use the landscape in the immediate vicinity of each site as a source of new data that can be used to determine some of the criteria involved in making the settlement choice. A Geographic Information System was used to gather information about the terrain, both generally for the region and near the sites and then comparing this local profile with the other sites across the region. This information is presented in a series of tabular and statistical displays that allow evaluations, not only about settlement choices inherent in the collection of sites but also about the efficacy of the landscape approach in archaeological research. The non-randomness of site location decisions is demonstrated along with evidence that certain landscape features were favoured over others. It is also apparent that a preliminary site typology can be affirmed as a result of certain types of sites selecting for specific terrain elements.
Toward Understanding the origin of the Fundamental Plane for Early-Type Galaxies
Creators: name: D'onofrio, M.
name: Valentinuzzi, T.
name: Secco, L.
name: Caimmi, R.
name: Bindoni, D.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present a panoramic review of several observational and theoretical aspects of the modern astrophysical research about the origin of the Fundamental Plane (FP) relation for Early-Type Galaxies (ETGs). The discussion is focused on the problem of the tilt and the tightness of the FP, and on the attempts to derive the luminosity evolution of ETGs with redshift. Finally, a number of observed features in the FP are interpreted from the standpoint of a new theoretical approach based on the two-component tensor virial theorem.
description: 30 pages, 3 figures
3D modelling of magneto-thermal evolution of neutron stars: method and test cases
Creators: name: De Grandis, Davide
name: Turolla, Roberto
name: Wood, Toby S.
name: Zane, Silvia
name: Taverna, Roberto
name: Gourgouliatos, Konstantinos N.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Neutron stars harbour extremely strong magnetic fields within their solid outer crust. The topology of this field strongly influences the surface temperature distribution, and hence the star's observational properties. In this work, we present the first realistic simulations of the coupled crustal magneto-thermal evolution of isolated neutron stars in three dimensions with account for neutrino emission, obtained with the pseudo-spectral code Parody. We investigate both the secular evolution, especially in connection with the onset of instabilities during the Hall phase, and the short-term evolution following episodes of localised energy injection. Simulations show that a resistive tearing instability develops in about a Hall time if the initial toroidal field exceeds ~$10^{15}$ G. This leads to crustal failures because of the huge magnetic stresses coupled with the local temperature enhancement produced by dissipation. Localised heat deposition in the crust results in the appearance of hot spots on the star surface which can exhibit a variety of patterns. Since the transport properties are strongly influenced by the magnetic field, the hot regions tend to drift away and get deformed following the magnetic field lines while cooling. The shapes obtained with our simulations are reminiscent of those recently derived from NICER X-ray observations of the millisecond pulsar PSR J0030+0451.
description: 15 pages, 14 figures, accepted for publication in ApJ
Learning by Doing: Developing a Baseline Information Literacy Assessment
Creators: name: Kiel, Stephen "Mike"
name: Burclaff, Natalie
name: Johnson, Catherine
Publisher: name: Maryland Shared Open Access Repository
Year: 2015
Subjects: Information Literacy
Assessment
Rubrics
Baseline Study

description: Preprint of article
description: This paper details the design and implementation of an initial baseline assessment of information literacy skills at the University of Baltimore. To provide practical advice and experience for a novice audience, the authors discuss how they approached the design and implementation of the study through the use of a rubric-based authentic assessment, employing a pretest and posttest delivered through a course management system. They also present lessons learned through the process of assessment focused on norming, test design and delivery, and the importance of institutional support and flexibility.
On the Transmission Probabilities in Quantum Key Distribution Systems over FSO Links
Creators: name: Zhao, Hui
name: Alouini, Mohamed-Slim
Publisher: name: arXiv
Year: 2020
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: In this paper, we investigate the transmission probabilities in three cases (depending only on the legitimate receiver, depending only the eavesdropper, and depending on both legitimate receiver and eavesdropper) in quantum key distribution (QKD) systems over free-space optical links. To be more realistic, we consider a generalized pointing error scenario, where the azimuth and elevation pointing error angles caused by stochastic jitters and vibrations in the legitimate receiver platform are independently distributed according to a non-identical normal distribution. Taking these assumptions into account, we derive approximate expressions of transmission probabilities by using the Gaussian quadrature method. To simplify the expressions and get some physical insights, some asymptotic analysis on the transmission probabilities is presented based on asymptotic expression for the generalized Marcum Q-function when the telescope gain at the legitimate receiver approaches to infinity. Moreover, from the asymptotic expression for the generalized Marcum Q-function, the asymptotic outage probability over Beckmann fading channels (a general channel model including Rayleigh, Rice, and Hoyt fading channels) can be also easily derived when the average signal-to-noise ratio is sufficiently large, which shows the diversity order and array gain.
description: 29 pages, 11 figures
The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results
Creators: name: George, S.
name: Blaum, K.
name: Herfurth, F.
name: Herlert, A.
name: Kretzschmar, M.
name: Nagy, S.
name: Schwarz, S.
name: Schweikhard, L.
name: Yazidjian, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: The highest precision in direct mass measurements is obtained with Penning trap mass spectrometry. Most experiments use the interconversion of the magnetron and cyclotron motional modes of the stored ion due to excitation by external radiofrequency-quadrupole fields. In this work a new excitation scheme, Ramsey's method of time-separated oscillatory fields, has been successfully tested. It has been shown to reduce significantly the uncertainty in the determination of the cyclotron frequency and thus of the ion mass of interest. The theoretical description of the ion motion excited with Ramsey's method in a Penning trap and subsequently the calculation of the resonance line shapes for different excitation times, pulse structures, and detunings of the quadrupole field has been carried out in a quantum mechanical framework and is discussed in detail in the preceding article in this journal by M. Kretzschmar. Here, the new excitation technique has been applied with the ISOLTRAP mass spectrometer at ISOLDE/CERN for mass measurements on stable as well as short-lived nuclides. The experimental resonances are in agreement with the theoretical predictions and a precision gain close to a factor of four was achieved compared to the use of the conventional excitation technique.
description: 12 pages, 14 figures, 2 tables
Direct Visualization of Trimerized States in 1T'-TaTe$_{2}$
Creators: name: Baggari, Ismail El
name: Sivadas, Nikhil
name: Stiehl, Gregory M.
name: Waelder, Jacob
name: Ralph, Daniel C.
name: Fennie, Craig J.
name: Kourkoutis, Lena F.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Transition-metal dichalcogenides containing tellurium anions show remarkable charge-lattice modulated structures and prominent interlayer character. Using cryogenic scanning transmission electron microscopy (STEM), we map the atomic-scale structures of the high temperature (HT) and low temperature (LT) modulated phases in 1T'-TaTe$_{2}$. At HT, we directly show in-plane metal distortions which form trimerized clusters and staggered, three-layer stacking. In the LT phase at 93 K, we visualize an additional trimerization of Ta sites and subtle distortions of Te sites by extracting structural information from contrast modulations in plan-view STEM data. Coupled with density functional theory calculations and image simulations, this approach opens the door for atomic-scale visualizations of low temperature phase transitions and complex displacements in a variety of layered systems.
Facebook Ads: Politics of Migration in Italy
Creators: name: Capozzi, Arthur
name: Morales, Gianmarco De Francisci
name: Mejova, Yelena
name: Monti, Corrado
name: Panisson, Andre
name: Paolotti, Daniela
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Targeted online advertising is on the forefront of political communication, allowing hyper-local advertising campaigns around elections and issues. In this study, we employ a new resource for political ad monitoring -- Facebook Ads Library -- to examine advertising concerning the issue of immigration in Italy. A crucial topic in Italian politics, it has recently been a focus of several populist movements, some of which have adopted social media as a powerful tool for voter engagement. Indeed, we find evidence of targeting by the parties both in terms of geography and demographics (age and gender). For instance, Five Star Movement reaches a younger audience when advertising about immigration, while other parties' ads have a more male audience when advertising on this issue. We also notice a marked rise in advertising volume around elections, as well as a shift to more general audience. Thus, we illustrate political advertising targeting that likely has an impact on public opinion on a topic involving potentially vulnerable populations, and urge the research community to include online advertising in the monitoring of public discourse.