cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The Arecibo Arp 220 Spectral Census I: Discovery of the Pre-Biotic Molecule Methanimine and New Cm-wavelength Transitions of Other Molecules
Creators: name: Salter, C. J.
name: Ghosh, T.
name: Catinella, B.
name: Lebron, M.
name: Lerner, M. S.
name: Minchin, R.
name: Momjian, E.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: An on-going Arecibo line search between 1.1 and 10 GHz of the prototypical starburst/megamaser galaxy, Arp 220, has revealed a spectrum rich in molecular transitions. These include the ``pre-biotic'' molecules: methanimine (CH$_{2}$NH) in emission, three $v_{2}=1$ direct l-type absorption lines of HCN, and an absorption feature likely to be from either $^{18}$OH or formic acid (HCOOH). In addition, we report the detection of two, possibly three, transitions of $λ$4-cm excited OH not previously detected in Arp~220 which are seen in absorption, and a possible absorption feature from the 6.668-GHz line of methanol. This marks the first distant extragalactic detection of methanimine, a pre-biotic molecule. Also, if confirmed, the possible methanol absorption line presented here would represent the first extragalactic detection of methanol at a distance further than 10 Mpc. In addition, the strong, previously undetected, cm-wave HCN $v_{2}=1$ direct l-type lines will aid the study of dense molecular gas and active star-forming regions in this starburst galaxy.
description: 25 pages, 10 figures. Accepted for publication in AJ
Another chiral critical end-point induced by neutral color superconductivity
Creators: name: Zhang, Zhao
name: Fukushima, Kenji
name: Kunihiro, Teiji
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: This paper has been withdrawn by the authors, due to it's incompleteness.
description: This paper has been withdrawn by the authors, due to it's incompleteness
A Double Myers-Perry Black Hole in Five Dimensions
Creators: name: Herdeiro, Carlos A. R.
name: Rebelo, Carmen
name: Zilhao, Miguel
name: Costa, Miguel S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Using the inverse scattering method we construct a six-parameter family of exact, stationary, asymptotically flat solutions of the 4+1 dimensional vacuum Einstein equations, with U(1)^2 rotational symmetry. It describes the superposition of two Myers-Perry black holes, each with a single angular momentum parameter, both in the same plane. The black holes live in a background geometry which is the Euclidean C-metric with an extra flat time direction. This background possesses conical singularities in two adjacent compact regions, each corresponding to a set of fixed points of one of the U(1) actions in the Cartan sub-algebra of SO(4). We discuss several aspects of the black holes geometry, including the conical singularities arising from force imbalance, and the torsion singularity arising from torque imbalance. The double Myers-Perry solution presented herein is considerably simpler than the four dimensional double Kerr solution and might be of interest in studying spin-spin interactions in five dimensional general relativity.
description: 23 pages, 7 figures, LaTeX. v2: minor changes, references added; version published in JHEP
Properties of an interacting one-dimensional fermion system
Creators: name: Friesen, Waldemar Isebrand
Publisher: name: University of British Columbia
Year: 2010

description: For nearly a decade, quasi-one-dimensional conductors have been the subject of intensive study. Theoretically, much attention has been devoted to the development of one-dimensional Fermi gas models, some which may be solved exactly, and to the calculation of their response functions. After a review of this theory, a different approach is adopted in the investigation of two models. The dielectric response theory of the three-dimensional Coulomb gas has been applied to an anisotropic system in which the particles interact with an effective one-dimensional long-range potential. Within the framework of the approximation of Singwi, Tosi, Land, and Sjolander, the dielectric properties of the model are examined in order to determine the conditions under which it is unstable with respect to formation of a charge density wave state. It is found that the positive neutralizing background must be polarizable in order for such an instability to occur. The same approximation method, when applied to a one-dimensional fermion gas with a ʃ-function interaction may be compared with the exact solution of Yang. This solution, which exists in the form of coupled integral equations, has been calculated numerically, and, as predicted by the Lieb-Mattis theorem, the ground state is found to be non-magnetic. The approximation of Singwi et al. proves to give better correlation energies than other inexact methods, particularly at higher densities.
Interplay between coarsening and nucleation in an Ising model with dipolar interactions
Creators: name: Cannas, S. A.
name: Michelon, M. F.
name: Stariolo, D. A.
name: Tamarit, F. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We study the dynamical behavior of a square lattice Ising model with exchange and dipolar interactions by means of Monte Carlo simulations. After a sudden quench to low temperatures we find that the system may undergo a coarsening process where stripe phases with different orientations compete or alternatively it can relax initially to a metastable nematic phase and then decay to the equilibrium stripe phase through nucleation. We measure the distribution of equilibration times for both processes and compute their relative probability of occurrence as a function of temperature and system size. This peculiar relaxation mechanism is due to the strong metastability of the nematic phase, which goes deep in the low temperature stripe phase. We also measure quasi-equilibrium autocorrelations in a wide range of temperatures. They show a distinct decay to a plateau that we identify as due to a finite fraction of frozen spins in the nematic phase. We find indications that the plateau is a finite size effect. Relaxation times as a function of temperature in the metastable region show super-Arrhenius behavior, suggesting a possible glassy behavior of the system at low temperatures.
A 57Fe Moessbauer Spectroscopy Study of the 7 K Superconductor LaFePO
Creators: name: Tegel, Marcus
name: Schellenberg, Inga
name: Pöttgen, Rainer
name: Johrendt, Dirk
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: A polycrystalline sample of superconducting LaFePO was prepared in a tin flux at 1123 K. The structure was determined from single crystal data (ZrCuSiAs-type, P4/nmm, a = 3.9610(1), c = 8.5158(2) A, Z = 2) and the phase analysis was performed by the Rietveld method. LaFePO is Pauli-paramagnetic and becomes superconducting at 7 K after removing the ferromagnetic impurity phase Fe2P from the sample. 57Fe Moessbauer spectroscopy measurements at 298, 77, 4.2 and 4 K show single signals at isomer shifts around 0.35 mm/s, subject to weak quadrupole splitting. At 4 K, a symmetric line broadening appears, resulting from a small transferred magnetic hyperfine field of 1.15(1) T and accompanied by an angle of 54.7(5) between Bhf and Vzz, the main component of the electric field gradient tensor.
description: submitted to Z. Naturforsch. B
A Line-Of-Sight Galaxy Cluster Collision: Simulated X-Ray Observations
Creators: name: Zuhone, J. A.
name: Ricker, P. M.
name: Lamb, D. Q.
name: Yang, H. -Y.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Several lines of evidence have suggested that the the galaxy cluster Cl~0024+17, an apparently relaxed system, is actually a collision of two clusters, the interaction occurring along our line of sight. In this paper we present a high-resolution $N$-body/hydrodynamics simulation of such a collision. We have created mock X-ray observations of our simulated system using MARX, a program that simulates the on-orbit performance of the Chandra X-ray Observatory. We analyze these simulated data to generate radial profiles of the surface brightness and temperature. At later times, $t = 2.0-3.0$ Gyr after the collision, the simulated surface brightness profiles are better fit by a superposition of two $β$-model profiles than a single profile, in agreement with the observations of Cl~0024+17. In general, due to projection effects, much of the post-collision density and temperature structure of the clusters is not seen in the observations. In particular, the observed temperatures from spectral fitting are much lower than the temperature of the hottest gas. We determine from our fitted profiles that if the system is modeled as a single cluster, the hydrostatic mass estimate is a factor $\sim$2-3 less than the actual mass, but if the system is modeled as two galaxy clusters in superposition, a hydrostatic mass estimation can be made which is accurate to within $\sim$10%. We examine some implications of these results for galaxy cluster X-ray surveys.
description: 14 pages (emulateapj), 13 figures. Updated text to match accepted version
StreamBrain: An HPC Framework for Brain-like Neural Networks on CPUs, GPUs and FPGAs
Creators: name: Podobas, Artur
name: Svedin, Martin
name: Chien, Steven W. D.
name: Peng, Ivy B.
name: Ravichandran, Naresh Balaji
name: Herman, Pawel
name: Lansner, Anders
name: Markidis, Stefano
Publisher: name: arXiv
Year: 2021
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Machine Learning (cs.LG)
subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: The modern deep learning method based on backpropagation has surged in popularity and has been used in multiple domains and application areas. At the same time, there are other -- less-known -- machine learning algorithms with a mature and solid theoretical foundation whose performance remains unexplored. One such example is the brain-like Bayesian Confidence Propagation Neural Network (BCPNN). In this paper, we introduce StreamBrain -- a framework that allows neural networks based on BCPNN to be practically deployed in High-Performance Computing systems. StreamBrain is a domain-specific language (DSL), similar in concept to existing machine learning (ML) frameworks, and supports backends for CPUs, GPUs, and even FPGAs. We empirically demonstrate that StreamBrain can train the well-known ML benchmark dataset MNIST within seconds, and we are the first to demonstrate BCPNN on STL-10 size networks. We also show how StreamBrain can be used to train with custom floating-point formats and illustrate the impact of using different bfloat variations on BCPNN using FPGAs.
description: Accepted for publication at the International Symposium on Highly Efficient Accelerators and Reconfigurable Technologies (HEART 2021)
A Projector-Camera System Using Hybrid Pixels with Projection and Capturing Capabilities
Creators: name: Yamamoto, Kenta
name: Iwai, Daisuke
name: Sato, Kosuke
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Graphics (cs.GR)
subject: FOS: Computer and information sciences

description: We propose a novel projector-camera system (ProCams) in which each pixel has both projection and capturing capabilities. Our proposed ProCams solves the difficulty of obtaining precise pixel correspondence between the projector and the camera. We implemented a proof-of-concept ProCams prototype and demonstrated its applicability to a dynamic projection mapping.
description: Author's version of a paper published at IDW (International Display Workshops) 2020
Dynamical polarization, screening, and plasmons in gapped graphene
Creators: name: Pyatkovskiy, P. K.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The one-loop polarization function of graphene has been calculated at zero temperature for arbitrary wavevector, frequency, chemical potential (doping), and band gap. The result is expressed in terms of elementary functions and is used to find the dispersion of the plasmon mode and the static screening within the random phase approximation. At long wavelengths the usual square root behaviour of plasmon spectra for two-dimensional (2D) systems is obtained. The presence of a small (compared to a chemical potential) gap leads to the appearance of a new undamped plasmon mode. At greater values of the gap this mode merges with the long-wavelength one, and vanishes when the Fermi level enters the gap. The screening of charged impurities at large distances differs from that in gapless graphene by slower decay of Friedel oscillations ($1/r^2$ instead of $1/r^3$), similarly to conventional 2D systems.
description: 8 pages, 8 figures, v2: to match published version
First Resolved Images of the Eclipsing and Interacting Binary Beta Lyrae
Creators: name: Zhao, M.
name: Gies, D.
name: Monnier, J. D.
name: Thureau, N.
name: Pedretti, E.
name: Baron, F.
name: Merand, A.
name: Brummelaar, T. ten
name: McAlister, H.
name: Ridgway, S. T.
name: Turner, N.
name: Sturmann, J.
name: Sturmann, L.
name: Farrington, C.
name: Goldfinger, P. J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the first resolved images of the eclipsing binary Beta Lyrae, obtained with the CHARA Array interferometer and the MIRC combiner in the H band. The images clearly show the mass donor and the thick disk surrounding the mass gainer at all six epochs of observation. The donor is brighter and generally appears elongated in the images, the first direct detection of photospheric tidal distortion due to Roche-lobe filling. We also confirm expectations that the disk component is more elongated than the donor and is relatively fainter at this wavelength. Image analysis and model fitting for each epoch were used for calculating the first astrometric orbital solution for Beta Lyrae, yielding precise values for the orbital inclination and position angle. The derived semi-ma jor axis also allows us to estimate the distance of Beta Lyrae; however, systematic differences between the models and the images limit the accuracy of our distance estimate to about 15%. To address these issues, we will need a more physical, self-consistent model to account for all epochs as well as the multi-wavelength information from the eclipsing light curves.
description: 13 Pages, 3 Figures; Accepted by ApJL
ZeroFake: Zero-Shot Detection of Fake Images Generated and Edited by Text-to-Image Generation Models
Creators: name: Sha, Zeyang
name: Tan, Yicong
name: Li, Mingjie
name: Backes, Michael
name: Zhang, Yang
Publisher: name: CISPA
Year: 2024

description: The text-to-image generation model has attracted significant interest from both academic and industrial communities. These models can generate the images based on the given prompt descriptions. Their potent capabilities, while beneficial, also present risks. Previous efforts relied on the approach of training binary classifiers to detect the generated fake images, which is inefficient, lacking in generalizability, and non-robust. In this paper, we propose the novel zero-shot detection method, called ZeroFake, to distinguish fake images apart from real ones by utilizing a perturbation-based DDIM inversion technique. ZeroFake is inspired by the findings that fake images are more robust than real images during the process of DDIM inversion and reconstruction. Specifically, for a given image, ZeroFake first generates noise with DDIM inversion guided by adversary prompts. Then, ZeroFake reconstructs the image from the generated noise. Subsequently, it compares the reconstructed image with the original image to determine whether it is fake or real. By exploiting the differential response of fake and real images to the adversary prompts during the inversion and reconstruction process, our model offers a more robust and efficient method to detect fake images without the extensive data and training costs. Extensive results demonstrate that the proposed ZeroFake can achieve great performance in fake image detection, fake artwork detection, and fake edited image detection. We further illustrate the robustness of the proposed ZeroFake by showcasing its resilience against potential adversary attacks. We hope that our solution can better assist the community in achieving the arrival of a more efficient and fair AGI.
Measurement of the Beta-Neutrino Correlation of Sodium-21 using Shakeoff Electrons
Creators: name: Vetter, P. A.
name: Abo-Shaeer, J. R.
name: Freedman, S. J.
name: Maruyama, R.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The beta-neutrino correlation coefficient, $a_{βν}$, is measured in sodium-21 by detecting the time-of-flight of the recoil nucleus detected in coincidence with the atomic electrons shaken off in beta decay. The sample of sodium-21 is confined in a magneto-optic trap. High detection efficiency allows low trap density, which suppresses the photoassociation of molecular sodium, which can cause a large systematic error. Suppressing the fraction of trapped atoms in the excited state using a dark trap also reduces the photoassociation process, and data taken with this technique are consistent. The largest remaining systematic uncertainties come from the measurement of the position and size of the atom trap, and the subtraction of background. We find $a_{βν}$ =0.5502(60), in agreement with the Standard Model prediction of $a_{βν}$ =0.553(2), and disagreeing with a previous measurement which was susceptible to an error introduced by the presence of molecular sodium.
description: 20 pages, 7 figures
Preheating with Non-Standard Kinetic Term
Creators: name: Lachapelle, Jean
name: Brandenberger, Robert H.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider reheating after inflation in theories with a non-standard kinetic term. We show that the equation that exhibits parametric resonance is the Hill-Whittaker equation, which is a particular case of the more general Hill equation. This equation is in general more unstable than the Mathieu equation, such that narrow resonance preheating may be efficient in theories with a non-canonical kinetic term.
description: 7 pages, 3 figures, a couple of typos corrected, a sentence added to the discussion section
Derivation of effective field theories
Creators: name: Uzunov, Dimo I.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A general self-consistency approach allows a thorough treatment of the corrections to the mean-field approximation (MFA). The natural extension of standard MFA with the help of a cumulant expansion leads to a new point of view on the effective field theories. The proposed approach can be used for a systematic treatment of fluctuation effects of various length scales and, perhaps, for the development of a new coarse graining procedure. We outline and justify our method by some preliminary calculations. Results are given for the critical temperature and the Landau parameters of the $ϕ^4$-theory -- the field counterpart of the Ising model. An important unresolved problem of the modern theory of phase transitions -- the problem for the calculation of the true critical temperature, is considered within the framework of the present approach. A comprehensive description of the ground state properties of many-body systems is also demonstrated.
Quantum algorithms for spin models and simulable gate sets for quantum computation
Creators: name: Nest, M. Van den
name: Dür, W.
name: Raussendorf, R.
name: Briegel, H. J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present elementary mappings between classical lattice models and quantum circuits. These mappings provide a general framework to obtain efficiently simulable quantum gate sets from exactly solvable classical models. For example, we recover and generalize the simulability of Valiant's match-gates by invoking the solvability of the free-fermion eight-vertex model. Our mappings furthermore provide a systematic formalism to obtain simple quantum algorithms to approximate partition functions of lattice models in certain complex-parameter regimes. For example, we present an efficient quantum algorithm for the six-vertex model as well as a 2D Ising-type model. We finally show that simulating our quantum algorithms on a classical computer is as hard as simulating universal quantum computation (i.e. BQP-complete).
description: 6 pages, 2 figures
Geometric Entanglement in a One-Dimensional Valence Bond Solid State
Creators: name: Orus, Roman
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: In this paper we provide the analytical derivation of the global geometric entanglement per block for the valence bond solid ground state of the spin-1 AKLT chain. In particular, we show that this quantity saturates exponentially fast to a constant when the sizes of the blocks are sufficiently large. Our result provides the first known example of an analytical calculation of the geometric entanglement for a gapped quantum many-body system in one dimension and far away from a quantum critical point.
description: 4 pages, 2 figures, 1 table
Scanning magnetic field microscope with a diamond single-spin sensor
Creators: name: Degen, C. L.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We describe a scanning device where a single spin is used as an ultrasensitive, nanoscale magnetic field sensor. As this "probe spin" we consider a single nitrogen-vacancy defect center in a diamond nanocrystal, attached to the tip of the scanning device. Changes in the local field seen by the probe spin are detected by optically monitoring its electron paramagnetic resonance transition. The room-temperature scanning device may be useful for performing nanoscale magnetic resonance imaging and spectroscopy, and for the characterization of magnetic nanostructures down to the single atom level.
description: 4 pages, 1 figure, 1 table
Observation of B+->b_1+K0 and search for B-meson decays to b_10K0 and b_1pi0
Creators: name: The BABAR Collaboration
name: Aubert, B.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We present the results of searches for decays of B mesons to final states with a b_1 meson and a neutral pion or kaon. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465 million BBbar pairs produced in e+e- annihilation. The results for the branching fractions are, in units of 1e-6, BR(B+ to b_1+K0) = 9.6+/-1.7+/-0.9, BR(B0 to b_10K0) = 5.1+/-1.8+/-0.5 (<7.8), BR(B+ to b_1+pi0) = 1.8+/-0.9+/-0.2 (<3.3), and BR(B0 to b_10pi0) = 0.4+/-0.8+/-0.2 (<1.9), with the assumption that BR(B_1 to omega pi)=1. We also measure the charge asymmetry A_ch(B+ to b_1+K0) = -0.03+/-0.15+/-0.02. The first error quoted is statistical, the second systematic, and the upper limits in parentheses indicate the 90% confidence level.
description: 7 pages, 2 postscript figures, submitted to PRD RC
On the phase diagrams of the ferromagnetic superconductors ZrZn2 and UGe2
Creators: name: Cottam, Michael G.
name: Shopova, Diana V.
name: Uzunov, Dimo I.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Astrophysics (astro-ph)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A general phenomenological theory is presented for the phase behavior of ferromagnetic superconductors with spin-triplet electron Cooper pairing. The theory accounts in detail for the temperature-pressure phase diagram of ZrZn$_2$, while the main features of the diagram for UGe$_2$ are also described. Quantitative criteria are deduced for the U-type (type I) and Zr-type (type II) unconventional ferromagnetic superconductors with spin-triplet Cooper electron pairing. Some basic properties of quantum phase transitions are also elucidated.
description: 4 pages, 3 figures; typos and minor mistakes has been removed
Coherent control of spontaneous emission of a three-level atom in a coherent photonic band gap reservoir
Creators: name: Cheng, Szu-Cheng
name: Wu, Jing-Nuo
name: Yang, Tzong-Jer
name: Hsieh, Wen-Feng
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: By studying the fluorescence and optical properties of a three-level system, we propose a new point of view on the coherent control of these spectra. With the definite phase difference between the fields of the air band and dielectric band in photonic band gap (PBG) reservoirs, the spectra of spontaneous emission, absorption, and dispersion exhibit the coherent property and quantum interference effect. This coherent interference depending on the position of the embedded atom and the width of band gap causes the coupling of the free-space light and the PBG light to result in blue shift of spectra and the appearance of dark lines and kinks. By coherently controlling the position-dependent dispersion, we can tune the frequency of slow light.
description: 13 pages, 4 figures
Corrigendum to "Knot Floer homology detects fibred knots"
Creators: name: Ni, Yi
Publisher: name: arXiv
Year: 2008
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: We correct a mistake on the citation of JSJ theory in \cite{Ni}. Some arguments in \cite{Ni} are also slightly modified accordingly.
description: 3 pages
title: Επιχειρηματικό σχέδιο για την ανάπτυξη και λειτουργία τουριστικής μονάδας στο νησί της Ζακύνθου
title: Business plan analysis for the development and operation of a tourist unit on the island of Zakynthos
Creators: name: Γκουσκος Ιωαννης
Publisher: name: Technical University of Crete
Year: 2021

description: Η διπλωματική εργασία έχει ως θέμα την δημιουργία ενός business plan για την ανάπτυξη και την λειτουργία μιας τουριστικής μονάδας. Πιο αναλυτικά, πέρα από την οικονομική ανάλυση του κόστους ανέγερσης της τουριστικής μονάδας θα γίνει ανάλυση της οργανωτικής δομής, θα διαμορφωθεί το σχέδιο marketing, θα προσδιοριστούν οι ανάγκες σε κεφάλαιο κίνησης καθώς και οποιαδήποτε άλλη ανάλυση απαιτείται ώστε να γίνει σωστή και ολοκληρωμένη μελέτη. ΢ΣΟΧΟΙ: Στόχος της εργασίας είναι να απαντήσει στον πελάτη αν αξίζει να επενδύσει τα χρήματα του στο εν λόγο έργο, κάτι που είναι εξαιρετικά σημαντικό διότι ακόμη και ένα μικρό λάθος συμπέρασμα μπορεί να προκαλέσει μεγάλη οικονομική ζημία στον επενδυτή. Όφελος από τα αποτελέσματα της θα έχει ο επενδυτής, στον οποίο θα παρουσιαστούν αναλυτικά όλα τα στοιχεία του business plan που απαιτούνται για την υλοποιήσει του έργου, καθώς και την μετέπειτα διαχείριση της τουριστικής μονάδας. ΜΕΘΟΔΟΛΟΓΙΑ: Σε πρώτη φάση, θα γίνει αναλυτική οικονομική μελέτη για την κατασκευή του έργου (κόστος αδειών, εκσκαφές, σκυρόδεμα, περιβάλλον χώρος κτλ) και στην συνέχεια λαμβάνοντας υπόψη διάφορα πιθανά σενάρια θα υπολογιστούν οι πιθανές οικονομικές απολαβές για την επόμενη δεκαετία. Αυτό πρακτικά σημαίνει ότι θα ακολουθηθεί τόσο η ποιοτική όσο και η ποσοτική μεθοδολογία έρευνας. Επίσης, για την εξαγωγή αποτελεσμάτων θα χρησιμοποιηθούν βάσεις δεδομένων που θα περιέχουν πληρότητες και τιμές ενοικίασης αντίστοιχων μονάδων στο νησί της Ζακύνθου (π.χ. Booking, Airbnb). Με το πέρας του business plan θα έχει γίνει σαφές στον επενδυτή εάν η επένδυση καθιστάτε αποδεκτή ή όχι. Στην λήψη της απόφασης αυτής θα παίξει σημαντικό ρόλο η SWOT ανάλυση η οποία αποτελεί ένα βασικό εργαλείο στρατηγικού σχεδιασμού. ΑΝΑΜΕΝΟΜΕΝΑ ΑΠΟΣΕΛΕ΢ΜΑΣΑ: Τα αποτελέσματα του business plan θα είναι υπολογισμένα αναλυτικά και παρουσιασμένα με σαφήνεια ώστε να είναι απολύτως κατανοητά. Στην περίπτωση που η έκβαση της μελέτης είναι θετική (κάτι που είναι πιθανό λόγο της ραγδαίας ανάπτυξης του τουρισμού στο νησί), θα πραγματοποιηθεί το συγκεκριμένο έργο μέσα στα επόμενα 3-5 χρόνια από επιχειρηματία που θέλει να ασχοληθεί πιο άμεσα με τον κλάδο του τουρισμού στο νησί της Ζακύνθου.
The Metal Content of Bulge Field Stars from FLAMES-GIRAFFE Spectra. I. Stellar parameters and Iron Abundances
Creators: name: Zoccali, M.
name: Hill, V.
name: Lecureur, A.
name: Barbuy, B.
name: Renzini, A.
name: Minniti, D.
name: Gomez, A.
name: Ortolani, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes b=-4 deg, b=-6 deg, and b=-12 deg. A fourth field including NGC6553 is also included in the discussion. About 800 bulge field K giants were observed with the GIRAFFE spectrograph of FLAMES@VLT at spectral resolution R~20,000. Several of them were observed again with UVES at R~45,000 to insure the accuracy of the measurements. The LTE abundance analysis yielded stellar parameters and iron abundances that allowed us to construct an IDF for the bulge that, for the first time, is based on high-resolution spectroscopy for each individual star. The IDF derived here is centered on solar metallicity, and extends from [Fe/H]~ -1.5 to [Fe/H]~ +0.5. The distribution is asymmetric, with a sharper cutoff on the high-metallicity side, and it is narrower than previously measured. A variation in the mean metallicity along the bulge minor axis is clearly between b=-4 deg and b=-6 deg ([Fe/H] decreasing by ~ 0.6 dex per kpc). The field at b=-12 deg is consistent with the presence of a gradient, but its quantification is complicated by the higher disk/bulge fraction in this field. Our findings support a scenario in which both infall and outflow were important during the bulge formation, and then suggest the presence of a radial gradient, which poses some challenges to the scenario in which the bulge would result solely from the vertical heating of the bar.
description: A&A in press
Dissipative and nonequilibrium effects near a superconductor-metal quantum critical point
Creators: name: Mitra, Aditi
Publisher: name: arXiv
Year: 2008
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We present a microscopic derivation of the effect of current flow on a system near a superconductor-metal quantum critical point. The model studied is a 2d itinerant electron system where the electrons interact via an attractive interaction and are coupled to an underlying normal metal substrate which provides a source of dissipation, and also provides a source of inelastic scattering that allows a nonequilibrium steady state to reach. A nonequilibrium Keldysh action for the superconducting fluctuations on the normal side is derived. Current flow, besides its minimal coupling to the order parameter is found to give rise to two new effects. One is a source of noise that acts as an effective temperature $T_{eff} = e E v_F τ_{sc}$ where $E$ is the external electric field, $v_F$ the Fermi velocity, and $τ_{sc}$ is the escape time into the normal metal substrate. Secondly current flow also produces a drift of the order-parameter. Scaling equations for the superconducting gap and the current are derived and are found to be consistent with previous phenomenological treatments as long as a temperature $T \sim T_{eff}$ is included. The current induced drift is found to produce additional corrections to the scaling which are smaller by a factor of ${\cal O}(\frac{1}{E_F τ_{sc}})$, $E_F$ being the Fermi energy.
description: 18 pages, 1 figure, discussion added
GLAST and Lorentz violation
Creators: name: Lamon, Raphael
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study possible Lorentz violations by means of gamma-ray bursts (GRB) with special focus on the Large Array Telescope (LAT) of GLAST. We simulate bursts with gtobssim and introduce a Lorentz violating term in the arrival times of the photons. We further perturb these arrival times and energies with a Gaussian distribution corresponding to the time resp. energy resolution of GLAST. We then vary the photon flux in gtobssim in order to derive a relation between the photon number and the standard deviation of the Lorentz violating term. We conclude with the fact that our maximum likelihood method as first developed in [1] is able to make a statement whether Nature breaks the Lorentz symmetry if the number of bursts with known redshifts is of the order of 100.
description: 13 pages, 8 figures and 2 tables, Accepted for publication by JCAP after a couple of revisions
Periodized discrete elasticity models for defects in graphene
Creators: name: Carpio, A.
name: Bonilla, L. L.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The cores of edge dislocations, edge dislocation dipoles and edge dislocation loops in planar graphene have been studied by means of periodized discrete elasticity models. To build these models, we have found a way to discretize linear elasticity on a planar hexagonal lattice using combinations of difference operators that do not involve symmetrically all the neighbors of an atom. At zero temperature, dynamically stable cores of edge dislocations may be heptagon-pentagon pairs (glide dislocations) or octagons (shuffle dislocations) depending on the choice of initial configuration. Possible cores of edge dislocation dipoles are vacancies, pentagon-octagon-pentagon divacancies, Stone-Wales defects and 7-5-5-7 defects. While symmetric vacancies, divacancies and 7-5-5-7 defects are dynamically stable, asymmetric vacancies and 5-7-7-5 Stone-Wales defects seem to be unstable.
description: 24 pages, 7 figures; comment on model with 3 slip directions, calculation of defect energies, typos corrected
Noncommutative Corrections to the Robertson-Walker metric
Creators: name: Fabi, S.
name: Harms, B.
name: Stern, A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Upon applying Chamseddine's noncommutative deformation of gravity we obtain the leading order noncommutative corrections to the Robertson-Walker metric tensor. We get an isotropic inhomogeneous metric tensor for a certain choice of the noncommutativity parameters. Moreover, the singularity of the commutative metric at $t=0$ is replaced by a more involved space-time structure in the noncommutative theory. In a toy model we construct a scenario where there is no singularity at $t=0$ at leading order in the noncommutativity parameter. Although singularities may still be present for nonzero $t$, they need not be the source of all time-like geodesics and the result resembles a bouncing cosmology.
description: 13 pages
Dislocations in cubic crystals described by discrete models
Creators: name: Bonilla, L. L.
name: Carpio, A.
name: Plans, I.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Discrete models of dislocations in cubic crystal lattices having one or two atoms per unit cell are proposed. These models have the standard linear anisotropic elasticity as their continuum limit and their main ingredients are the elastic stiffness constants of the material and a dimensionless periodic function that restores the translation invariance of the crystal and influences the dislocation size. For these models, conservative and damped equations of motion are proposed. In the latter case, the entropy production and thermodynamic forces are calculated and fluctuation terms obeying the fluctuation-dissipation theorem are added. Numerical simulations illustrate static perfect screw and 60$^\circ$ dislocations for GaAs and Si.
description: 26 pages, 4 figures
Probing the ZZgamma and Zgammagamma Couplings Through the Process e+e- --> nu anti-nu gamma
Creators: name: Gutierrez-Rodriguez, A.
name: Hernandez-Ruiz, M. A.
name: Perez, M. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the sensitivity for testing the anomalous triple gauge couplings $ZZγ$ and $Zγγ$ via the process $e^+e^-\to ν\barνγ$ at high energy linear colliders. For integrated luminosities of 500 $fb^{-1}$ and center of mass energies between 0.5 and 1.5 $TeV$, we find that this process can provide tests of the triple neutral gauge boson couplings of order $10^{-4}$, one order of magnitude lower than the standard model prediction.
description: 12 pages, 6 figures
Observation of the Little-Parks Oscillations in a System of Asymmetric Superconducting Rings
Creators: name: Burlakov, A. A.
name: Gurtovoi, V. L.
name: Dubonos, S. V.
name: Nikulov, A. V.
name: Tulin, V. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Little-Parks oscillations are observed in a system of 110 series-connected aluminum rings 2000 nm in diameter with the use of measuring currents from 10 nA to 1000 nA. The measurements show that the amplitude and character of the oscillations are independent of the relation between the measuring current and the amplitude of the persistent current. By using asymmetric rings, it is demonstrated that the persistent current has clockwise or contra-clockwise direction. This means that the total current in one of the semi-rings may be directed against the electric field at measurement of the Little-Parks oscillations. The measurements at zero and low measuring current have revealed that the persistent current, like the conventional circulating current, causes a potential difference on the semi-rings with different cross sections in spite of the absence of the Faraday's voltage.
description: 5 pages, 6 figures
Suppressed conductance in a metallic graphene nano-junction
Creators: name: Li, Haidong
name: Wang, Lin
name: Zheng, Yisong
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The linear conductance spectrum of a metallic graphene junction formed by interconnecting two gapless graphene nanoribbons is calculated. A strong conductance suppression appears in the vicinity of the Dirac point. We found that such a conductance suppression arises from the antiresonance effect associated with the edge state localized at the zigzag-edged shoulder of the junction. The conductance valley due to the antiresonance is rather robust in the presence of the impurity and vacancy scattering. And the center of the conductance valley can be readily tuned by an electric field exerted on the wider nanoribbon.
description: 14 pages, 4 figures
Zero mode contribution in quarkonium correlators and in-medium properties of heavy quarks
Creators: name: Datta, Saumen
name: Petreczky, Peter
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We calculate the low energy contribution to quarkonium correlators in Euclidean time in lattice QCD. This contribution was found to give the dominant source of the temperature dependence of the correlators. We have found that the low energy contribution is well described by a quasi-particle model and have determined the effective temperature dependent heavy quark mass.
description: Contribution to QM2008, 4 pages, LaTeX, uses iopart.cls, corrected typos
Critical behaviour in quantum gravitational collapse
Creators: name: Husain, Viqar
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the gravitational collapse of an inhomogeneous scalar field with quantum gravity corrections associated with singularity avoidance. Numerical simulations indicate that there is critical behaviour at the onset of black hole formation as in the classical theory, but with the difference that black holes form with a mass gap.
description: 8 pages, 3 figures. Typos corrected -- version to appear in a special issue of Adv. Science Lett. (Ed. M. Bojowald)
The Lorentz group and its finite field analogues: local isomorphism and approximation
Creators: name: Foldes, Stephan
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Finite Lorentz groups acting on 4-dimensional vector spaces coordinatized by finite fields with a prime number of elements are represented as homomorphic images of countable, rational subgroups of the Lorentz group acting on real 4-dimensional space-time. Bounded subsets of the real Lorentz group are retractable with arbitrary accuracy to finite subsets of such rational subgroups. These finite retracts correspond, via local isomorphisms, to well-behaved subsets of Lorentz groups over finite fields. This establishes a relationship of approximation between the real Lorentz group and Lorentz groups over very large finite fields.
Tunable pure spin currents in a triple-quantum-dot ring
Creators: name: Gong, Weijiang
name: Zheng, Yisong
name: Lv, Tianquan
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Electron transport properties in a triple-quantum-dot ring with three terminals are theoretically studied. By introducing local Rashba spin-orbit interaction on an individual quantum dot, we calculate the charge and spin currents in one lead. We find that a pure spin current appears in the absence of a magnetic field. The polarization direction of the spin current can be inverted by altering the bias voltage. In addition, by tuning the magnetic field strength, the charge and spin currents reach their respective peaks alternately.
description: 5 pages, 2 Figures
In search of multipolar order on the Penrose tiling
Creators: name: Vedmedenko, E. Y.
name: Mandel, Shahar Even-Dar
name: Lifshitz, Ron
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Based on Monte Carlo calculations, multipolar ordering on the Penrose tiling, relevant for two-dimensional molecular adsorbates on quasicrystalline surfaces and for nanomagnetic arrays, has been analyzed. These initial investigations are restricted to multipolar rotors of rank one through four - described by spherical harmonics Ylm with l=1...4 and restricted to m=0 - positioned on the vertices of the rhombic Penrose tiling. At first sight, the ground states of odd-parity multipoles seem to exhibit long-range multipolar order, indicated by the appearance of a superstructure in the form of the decagonal Hexagon-Boat-Star tiling, in agreement with previous investigations of dipolar systems. Yet careful analysis establishes that long-range multipolar order is absent in all cases investigated here, and only short-range order exists. This result should be taken as a warning for any future analysis of order in either real or simulated arrangements of multipoles on quasiperiodic templates.
Phonon anharmonicity: a pertinent review of recent progress and perspective
Creators: name: Wei, Bin
name: Sun, Qiyang
name: Li, Chen
name: Hong, Jiawang
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Anharmonic lattice vibrations govern the thermal dynamics in materials and present how the atoms interact and how they conduct heat. An indepth understanding of the microscopic mechanism of phonon anharmonicity in condensed systems is critical for developing better functional and energy materials. In recent years, a variety of novel behaviors in condense matters are driven by phonon anharmonic effects in some way or another, such as soft mode phase transition, negative thermal expansion, multiferroicity, ultralow thermal conductivity or high thermal resistance, and high-temperature superconductivity, etc. All these properties have endowed anharmonicity with many promising applications and provided remarkable opportunities for developing anharmonicity engineering, regulating heat transport towards excellent performance in materials. In this work, we review the recent development of the study on phonon anharmonic effect and summarize its origination, influence and mechanism, research methods, and applications. Besides, the remaining challenges, future trends, and prospects of phonon anharmonicity are also put forward.
Dynamics of the multiferroic LiCuVO4 influenced by electric field
Creators: name: Gotovko, S. K.
name: Marchenko, V. I.
name: Prokofiev, A.
name: Svistov, L. E.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We present the electron spin resonance study of the influence of an electric field on the low-field multiferroic magnetic state in LiCuVO4. The shift of the magnetic resonance spectra in the electric field has been observed experimentally. Symmetry analysis has been conducted in order to describe the static properties of the magnetic system. The low-frequency dynamics of LiCuVO4 in magnetic and electric fields was considered in the framework of hydrodynamic approach. It was shown that the application of the external electric field leads to the change of the configuration of the magnetic system before and after spin-flop reorientation. Satisfactory agreement was obtained between the results of experimental studies and theoretical consideration.
description: 9 pages, 8 figures
Probing modified gravitational wave propagation with strongly lensed coalescing binaries
Creators: name: Finke, Andreas
name: Foffa, Stefano
name: Iacovelli, Francesco
name: Maggiore, Michele
name: Mancarella, Michele
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: It has been recently shown that quadruply lensed gravitational-wave (GW) events due to coalescing binaries can be localized to one or just a few galaxies, even in the absence of an electromagnetic counterpart. We discuss how this can be used to extract information on modified GW propagation, which is a crucial signature of modifications of gravity at cosmological scales. We show that, using quadruply lensed systems, it is possible to constrain the parameter $Ξ_0$ that characterizes modified GW propagation, without the need of imposing a prior on $H_0$. A LIGO/Virgo/Kagra network at target sensitivity might already get a significant measurement of $Ξ_0$, while a third generation GW detector such as the Einstein Telescope could reach a very interesting accuracy.
description: 11 pages, 5 figures