cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Analytic Model of the Universal Structure of Turbulent Boundary Layers
Creators: name: L'vov, Victor S.
name: Procaccia, Itamar
name: Rudenko, Oleksii
Publisher: name: arXiv
Year: 2006
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Turbulent boundary layers exhibit a universal structure which nevertheless is rather complex, being composed of a viscous sub-layer, a buffer zone, and a turbulent log-law region. In this letter we present a simple analytic model of turbulent boundary layers which culminates in explicit formulae for the profiles of the mean velocity, the kinetic energy and the Reynolds stress as a function of the distance from the wall. The resulting profiles are in close quantitative agreement with measurements over the entire structure of the boundary layer, without any need of re-fitting in the different zones.
description: 5 pages, 4 figs, JETP Letters, submitted. Comparison with the latest DNS data
Policy Maker's Credibility with Predetermined Instruments for Forward-Looking Targets
Creators: name: Chatelain, Jean-Bernard
name: Ralf, Kirsten
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Economics (econ.GN)
subject: FOS: Economics and business
subject: 91B64

description: The aim of the present paper is to provide criteria for a central bank of how to choose among different monetary-policy rules when caring about a number of policy targets such as the output gap and expected inflation. Special attention is given to the question if policy instruments are predetermined or only forward looking. Using the new-Keynesian Phillips curve with a cost-push-shock policy-transmission mechanism, the forward-looking case implies an extreme lack of robustness and of credibility of stabilization policy. The backward-looking case is such that the simple-rule parameters can be the solution of Ramsey optimal policy under limited commitment. As a consequence, we suggest to model explicitly the rational behavior of the policy maker with Ramsey optimal policy, rather than to use simple rules with an ambiguous assumption leading to policy advice that is neither robust nor credible.
Artificiality in Social Sciences
Creators: name: Rennard, Jean-Philippe
Publisher: name: arXiv
Year: 2007
Subjects: subject: Multiagent Systems (cs.MA)
subject: FOS: Computer and information sciences
subject: I.2.11

description: This text provides with an introduction to the modern approach of artificiality and simulation in social sciences. It presents the relationship between complexity and artificiality, before introducing the field of artificial societies which greatly benefited from the computer power fast increase, gifting social sciences with formalization and experimentation tools previously owned by "hard" sciences alone. It shows that as "a new way of doing social sciences", artificial societies should undoubtedly contribute to a renewed approach in the study of sociality and should play a significant part in the elaboration of original theories of social phenomena.
description: 14 pages
Connecting an effective model of confinement and chiral symmetry to lattice QCD
Creators: name: Fraga, Eduardo
name: Mocsy, Agnes
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We construct an effective model for the chiral field and the Polyakov loop in which we can investigate the interplay between the approximate chiral symmetry restoration and the deconfinement of color in a thermal SU(3) gauge theory with three flavors of massive quarks. The phenomenological couplings between these two sectors can then be related to the recent lattice data on the renormalized Polyakov loop and the chiral condensate close to the critical region.
description: Invited talk at IR-QCD, Rio de Janiero, June 5-9, 2006
title: Variable Selection in Mixture Models with an Uncertainty Component
Creators: name: Schneider, Micha
name: Pößnecker, Wolfgang
name: Tutz, Gerhard
Publisher: name: Universitätsbibliothek der Ludwig-Maximilians-Universität München
Year: 2019

description: Mixture Models as CUB and CUP models provide the opportunity to model discrete human choices as a combination of a preference and an uncertainty structure. In CUB models the preference is represented by shifted binomial random variables and the uncertainty by a discrete uniform distribution. CUP models extend this concept by using ordinal response models as the cumulative model for the preference structure. To reduce model complexity we propose variable selection via group lasso regularization. The approach is developed for CUB and CUP models and compared to a stepwise selection. Both simulated data and survey data are used to investigate the performance of the selection procedures. It is demonstrated that variable selection by regularization yields stable parameter estimates and easy-to-interpret results in both model components and provides a data-driven method for model selection in mixture models with an uncertainty component.
Outer membrane protein OprF of P. aeruginosa
Creators: name: Rawling, Eileen Grace
Publisher: name: University of British Columbia
Year: 2009

description: An OprF-deficient mutant of P. aeruginosa strain M-2 was constructed by Ω mutagenesis. This strain was unable to grow in low osmolarity media and was 70% the length of the parental strain. These results confirmed that these phenotypes were not strain specific. Consistent with the appearance of OprF-deficient strains in clinical situations, an OprF-deficient strain was shown to not have a major growth disadvantage in an in vivo chamber model. Plasmids encoding truncated and cysteine-to-serine mutants of OprF were constructed by linker-insertion mutagenesis, PCR and subcloning of a previously characterized mutant. Analysis of the resulting proteins indicated that between 102 and 163 N-terminal amino acids of OprF was required for protein expression as determined by Western immunoblotting. All of the truncated mutants expressed were associated with the outer membrane, indicating that the N-terminal 163 amino acids of OprF were sufficient for this association. None of the truncated-OprF mutants tested were associated with the peptidoglycan, indicating that more than 215 N-terminal amino acids of OprF are required for this association. Strains that encoded at least two cysteines were 2-mercaptoethanol modifiable. The full-length cloned OprF and the truncated mutant expressing the N-terminal 290 amino acids were normally heat modifiable. When denatured prior to electrophoresis, the remaining truncated mutants had apparent molecular weights lower than those of untreated samples indicating that between 215 and 290 amino acids were required for the protein to be normally heat modified. Although the truncated-OprF mutants were able to grow in low osmolarity media and were significantly longer than the OprF-deficient strain, the C-terminal half of OprF appeared to be required for the wild-type growth and length. The cysteine-to-serine OprF mutants were associated with the outer membrane and were heat modifiable. Analysis of these mutants with and without 2-mercaptoethanol was consistent with the hypothesis that wild-type OprF has two disulphide bonds Monoclonal antibody reactivity with overlapping octapeptides equivalent to the primary sequence of OprF localized three epitopes. Indirect immunofluorescence and opsonic phagocytosis studies identified the surface location of epitopes binding nine OprF-specific monoclonal antibodies. This information was incorporated into an updated secondary structure model of OprF.
Off-Line Arabic Handwritten Words Segmentation using Morphological Operators
Creators: name: AbdAllah, Nisreen
name: Viriri, Serestina
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Computation and Language (cs.CL)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: The main aim of this study is the assessment and discussion of a model for hand-written Arabic through segmentation. The framework is proposed based on three steps: pre-processing, segmentation, and evaluation. In the pre-processing step, morphological operators are applied for Connecting Gaps (CGs) in written words. Gaps happen when pen lifting-off during writing, scanning documents, or while converting images to binary type. In the segmentation step, first removed the small diacritics then bounded a connected component to segment offline words. Huge data was utilized in the proposed model for applying a variety of handwriting styles so that to be more compatible with real-life applications. Consequently, on the automatic evaluation stage, selected randomly 1,131 images from the IESK-ArDB database, and then segmented into sub-words. After small gaps been connected, the model performance evaluation had been reached 88% against the standard ground truth of the database. The proposed model achieved the highest accuracy when compared with the related works.
description: 16 pages,27 figures
Ground state energy and magnetization curve of a frustrated magnetic system from real-time evolution on a digital quantum processor
Creators: name: Szasz, Aaron
name: Younis, Ed
name: de Jong, Wibe Albert
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Models of interacting many-body quantum systems that may realize new exotic phases of matter, notably quantum spin liquids, are challenging to study using even state-of-the-art classical methods such as tensor network simulations. Quantum computing provides a promising route for overcoming these difficulties to find ground states, dynamics, and more. In this paper, we argue that recently developed hybrid quantum-classical algorithms based on real-time evolution are promising methods for solving a particularly important model in the search for spin liquids, the antiferromagnetic Heisenberg model on the two-dimensional kagome lattice. We show how to construct efficient quantum circuits to implement time evolution for the model and to evaluate key observables on the quantum computer, and we argue that the method has favorable scaling with increasing system size. We then restrict to a 12-spin star plaquette from the kagome lattice and a related 8-spin system, and we give an empirical demonstration on these small systems that the hybrid algorithms can efficiently find the ground state energy and the magnetization curve. For these demonstrations, we use four levels of approximation: exact state vectors, exact state vectors with statistical noise from sampling, noisy classical emulators, and (for the 8-spin system only) real quantum hardware, specifically the Quantinuum H1-1 processor; for the noisy simulations and hardware demonstration, we also employ error mitigation strategies based on the symmetries of the Hamiltonian. Our results strongly suggest that these hybrid algorithms present a promising direction for studying quantum spin liquids and more generally for resolving important unsolved problems in condensed matter theory and beyond.
description: v3: 36 pages, 23 figures. Reformatted for publication; v2: 31 pages, 23 figures. Small corrections to eqs (16) and (28), and to cost-scaling with system size on pg 12; v1: 29 pages, 22 figures
The Spitzer Survey of the Small Magellanic Cloud: FIR Emission and Cold Gas in the SMC
Creators: name: Leroy, Adam
name: Bolatto, Alberto
name: Stanimirovic, Snezana
name: Mizuno, Norikazu
name: Israel, Frank
name: Bot, Caroline
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present new far infrared maps of the Small Magellanic Cloud (SMC) at 24, 70, and 160 microns obtained as part of the Spitzer Survey of the Small Magellanic Cloud (S3MC,Bolatto et al. 2006). These maps cover most of the active star formation in the SMC Bar and the more quiescent Wing. We combine our maps with literature data to derive the dust surface density across the SMC. We find a total dust mass of Mdust = 3 10^5 Msun, implying a dust-to-hydrogen ratio over the region studied of log D/H = -2.86, or 1-to-700, which includes H_2. Assuming the dust to trace the total gas column, we derive H_2 surface densities across the SMC. We find a total H_2 mass M_H2 = 3.2 10^7 Msun in a distribution similar to that of the CO, but more extended. We compare profiles of CO and H_2 around six molecular peaks and find that on average H_2 is more extended than CO by a factor of \sim 1.3. The implied CO-to-H_2 conversion factor over the whole SMC is XCO = 13 +/- 1 10^21 cm^-2 (K km/s)^-1. Over the volume occupied by CO we find a lower conversion factor, XCO = 6 +/- 1 10^21 cm^-2 (K km/s)^-1, which is still a few times larger than that found using virial mass methods. The molecular peaks have H_2 surface densities Σ_H2 \approx 180 +/- 30 Msun pc^-2, similar to those in Milky Way GMCs, and correspondingly low extinctions, A_V \sim 1 - 2 mag. To reconcile these measurements with predictions by the theory of photoionization-regulated star formation, which requires A_V \sim 6, the GMCs must be \sim 3 times smaller than our 46 pc resolution element. We find that for a given hydrostatic gas pressure, the SMC has a 2 - 3 times lower ratio of molecular to atomic gas than spiral galaxies. Combined with the lower mean densities in the SMC this may explain why this galaxy has only 10% of its gas in the molecular phase.
description: 24 pages, 16 figures, accepted by ApJ. A version with nice figures is available at http://celestial.berkeley.edu/spitzer/publications/
Fermi-liquid instabilities at magnetic quantum phase transitions
Creators: name: Löhneysen, Hilbert v.
name: Rosch, Achim
name: Vojta, Matthias
name: Wölfle, Peter
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: This review discusses instabilities of the Fermi-liquid state of conduction electrons in metals with particular emphasis on magnetic quantum critical points. Both the existing theoretical concepts and experimental data on selected materials are presented; with the aim of assessing the validity of presently available theory. After briefly recalling the fundamentals of Fermi-liquid theory, the local Fermi-liquid state in quantum impurity models and their lattice versions is described. Next, the scaling concepts applicable to quantum phase transitions are presented. The Hertz-Millis-Moriya theory of quantum phase transitions is described in detail. The breakdown of the latter is analyzed in several examples. In the final part experimental data on heavy-fermion materials and transition-metal alloys are reviewed and confronted with existing theory.
description: 62 pages, 29 figs, review article for Rev. Mod. Phys; (v2) discussion extended, refs added; (v3) shortened; final version as published
On the degree of irrationality of low genus $K3$ surfaces
Creators: name: Moretti, Federico
name: Rojas, Andrés
Publisher: name: arXiv
Year: 2024
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 14E05, 14F08, 14J28

description: Given a general polarized $K3$ surface $S\subset \mathbb P^g$ of genus $g\le 14$, we study projections $S\hookrightarrow \mathbb P^g\dashrightarrow \mathbb P^2$ of minimal degree and their variational structure. In particular, we prove that the degree of irrationality of all such surfaces is at most $4$, and that for $g=7,8,9,11$ there are no rational maps $S\dashrightarrow \mathbb P^2$ of degree $3$ induced by the primitive linear system. Our methods combine vector bundle techniques à la Lazarsfeld with derived category tools, and also make use of the rich theory of singular curves on $K3$ surfaces.
description: 32 pages, 1 figure. Comments welcome. Accepted version, to appear in Journal of the Institute of Mathematics of Jussieu
Wahrscheinlichkeitsdichte des Betrags im R² zweier unabhängiger standardnormalverteilter Zufallsgrößen
Creators: name: Schröer, Harald
Publisher: name: Zenodo
Year: 2019
Subjects: Wahrscheinlichkeitsdichte, Betrag,euklidisch, standard, Normalverteilung, Polarkoordinaten, Ebene, Transformation,Differenzieren, Integral, Ableitung, unabhängig

description: Vorausgesetzt werden unabhängige standardnormalverteilte Zufallsvariablen. Die Wahrscheinlichkeitsdichte des euklidischen Betrags im R² wird berechnet.
Current-driven ferromagnetic resonance, mechanical torques and rotary motion in magnetic nanostructures
Creators: name: Kovalev, Alexey A.
name: Bauer, Gerrit E. W.
name: Brataas, Arne
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study theoretically the detection and possible utilization of electric current-induced mechanical torques in ferromagnetic-normal metal heterostructures that are generated by spin-flip scattering or the absorption of transverse spin currents by a ferromagnet. To this end, we analyze the DC voltage signals over a spin valve that is driven by an AC current. In agreement with recent studies, this "rectification", measured as a function of AC frequency and applied magnetic field, contains important information on the magnetostatics and --dynamics. Subsequently, we show that the vibrations excited by spin-transfer to the lattice can be detected as a splitting of the DC voltage resonance. Finally, we propose a concept for a spin-transfer-driven electric nanomotor based on integrating metallic nanowires with carbon nanotubes, in which the current-induced torques generate a rotary motion.
description: This resubmission corrects typos in Appendix A 26 pages, 7 figures
The escaping set of a quasiregular mapping
Creators: name: Bergweiler, Walter
name: Fletcher, Alastair
name: Langley, Jim
name: Meyer, Janis
Publisher: name: arXiv
Year: 2008
Subjects: subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 30C65, 30C62, 37F10

description: We show that if the maximum modulus of a quasiregular mapping f grows sufficiently rapidly then there exists a non-empty escaping set I(f) consisting of points whose forward orbits under iteration tend to infinity. This set I(f) has an unbounded component but, in contrast to the case of entire functions on the complex plane, the closure of I(f) may have a bounded component.
description: 10 pages
In vitro διαχρονική συγκριτική μελέτη της αντοχής δεσμού πρόσφυσης του Resilon-Epiphany se στην οδοντίνη με τη χρήση Push out test:
Creators: name: Δεμερτζή, Ελένη Ηλία
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Αντοχή δεσμού πρόσφυσης
Resilon-epiphany SE
Pust out test
Bong strenght

description: Στόχος της παρούσας μελέτης είναι να μελετήσει την αντοχή δεσμού πρόσφυσης του αυτοαδροποιούμενου φυράματος Epiphany SE με την επιφάνεια της οδοντίνης σε βάθος χρόνου. Για την πραγματοποίηση της μελέτης χρησιμοποιήθηκαν 60 μονόρριζα δόντια ανθρώπινης προέλευσης. Από τα 60 δείγματα τα μισά εμφράχθηκαν με φύραμα AH26 και gutta-percha και τα υπόλοιπα με Resilon/ Epiphnay SE. Tα μισά δείγματα από κάθε ομάδα τοποθετήθηκαν σε επωαστικό κλίβανο με 100% υγρασία για 14 ημέρες και τα υπόλοιπα για 12 μήνες. Στη συνέχεια κάθε δείγμα χωρίστηκε σε τρία τμήματα με εγκάρσιες τομές και όλες οι τομές υποβλήθηκαν σε push-out test. Ακολούθησε παρατήρηση των τομών σε οπτικό μικροσκόπιο. Σύμφωνα με τις μετρήσεις του push-out test δεν διαπιστώθηκε διαφορά των συστημάτων μεταξύ τους μετά από παραμονή 14 ημερών σε επωαστικό κλίβανο. Αντίθετα μετά από 12 μήνες η αντοχή δεσμού του Resilon/Epiphany SE μειώθηκε σημαντικά σε σχέση με το AH26 και gutta-percha. Μεγαλύτερη μείωση παρατηρήθηκε με το σύστημα Resilon/Epiphany SE. Ωστόσο δεν διαπιστώθηκαν στατιστικά σημαντικές διαφορές. Υπό τους περιορισμούς της παρούσας μελέτης συμπεραίνεται ότι η μικρομηχανική συμπεριφορά του δεσμού οδοντίνης και Epiphany SE μεταβάλλεται με την επίδραση της υγρασίας και του χρόνου. Η αντοχή του δεσμού του συστήματος Resilon/Epiphany SE ήταν υποδεέστερη του ΑΗ26/gutta-percha μετά από πάροδο 12 μηνών.
description: The aim of the present in vitro study is to investigate the long term bond strength produced by Resilon/Epiphany Self-etch to root canal dentin. In order to conduct the study 60 human single-root teeth were used. Half of the sample was obturated with AH26/gutta-percha. The other half with Resilon/Epiphany SE. In order to investigate the aging of the materials half the specimens of each group were stored in an incubator of 37ο C and 100% humidity, for 14 days and the other half for 12 months. Each root was horizontally sectioned into tree slices. Afterwards push-out test was conducted for each slice. All slices were observed under optical microscope. According to measurements of the push-out test no significant differences were observed between AH26/gutta-percha and Resilon/Epiphany SE after 14 days storage in the incubator. However after 12 months of storage significant differences were measured between AH26/gutta-percha and Resilon/Epiphany SE. Under the limitations of this in vitro study it can be concluded that the micromechanical behavior of the bond between dentin and Epiphany SE is compromised by humid environment and time. Bond strength of Resilon/Epiphany SE is lower than AH26/gutta-percha after 12 months.
Combinatorial approach to multipartite quantum systems:basic formulation
Creators: name: Hassan, Ali Saif M.
name: Joag, Pramod
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this paper we give a method to associate a graph with an arbitrary density matrix referred to a standard orthonormal basis in the Hilbert space of a finite dimensional quantum system. We study the related issues like classification of pure and mixed states, Von-Neumann entropy, separability of multipartite quantum states and quantum operations in terms of the graphs associated with quantum states. In order to address the separability and entanglement questions using graphs, we introduce a modified tensor product of weighted graphs, and establish its algebraic properties. In particular, we show that Werner's definition [1] of a separable state can be written in terms of a graphs, for the states in a real or complex Hilbert space. We generalize the separability criterion (degree criterion) due to S.L. Braunstein, S. Ghosh, T. Mansour, S. Severini, R.C. Wilson [2], to a class of weighted graphs with real weights. We have given some criteria for the Laplacian associated with a weighted graph to be positive semidefinite.
description: 55 pages,24 figures. Comments are welcome
Enhanced Direct Delta Mush
Creators: name: Kalentchouk, Serguei
name: Hutchinson, Michael
name: Tolani, Deepak
Publisher: name: arXiv
Year: 2021
Subjects: subject: Graphics (cs.GR)
subject: FOS: Computer and information sciences

description: Direct Delta Mush is a novel skinning deformation technique introduced by Le and Lewis (2019). It generalizes the iterative Delta Mush algorithm of Mancewicz et al (2014), providing a direct solution with improved efficiency and control. Compared to Linear Blend Skinning, Direct Delta Mush offers better quality of deformations and ease of authoring at comparable performance. However, Direct Delta Mush does not handle non-rigid joint transformations correctly which limits its application for most production environments. This paper presents an extension to Direct Delta Mush that integrates the non-rigid part of joint transformations into the algorithm. In addition, the paper also describes practical considerations for computing the orthogonal component of the transformation and stability issues observed during the implementation and testing.
Searching for Gas-Rich Disks around T Tauri Stars in Lupus
Creators: name: van Kempen, T. A.
name: van Dishoeck, E. F.
name: Brinch, C.
name: Hogerheijde, M. R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: AIMS : To characterize the molecular environment of classical T Tauri stars in Lupus observed with the Spitzer Space Telescope and to search for gas-rich disks toward these sources. METHODS : Submillimeter observations of 12CO, 13CO and C18O in the J=3-2 and 2-1 lines were obtained with the James Clerk Maxwell Telescope toward a sample of 21 T Tauri stars with disks in the Lupus molecular clouds. Pointings at the sources and at selected off-positions are presented in order to disentangle material associated with disks from ambient cloud material. RESULTS : One source, IM Lup (Sz 82), has been found with double-peaked 12CO and 13CO profiles characteristic of a large rotating gas disk. The inclination of the disk is found to be ~20 degrees, with an outer radius of 400-700 AU. For most other sources, including GQ Lup with its substellar companion, the single-dish 12CO lines are dominated by extended cloud emission with a complex velocity structure. No evidence for molecular outflows is found. Compact C18O emission due to dense circumstellar material has been detected toward only two sources. Future searches for gas-rich disks in Lupus should either use interferometers or perform very deep single-dish integrations in dense gas tracers to separate the cloud and disk emission.
description: 8 pages, with online section, accepted by A&A
Highly efficient phase-tunable photonic thermal diode
Creators: name: Marchegiani, G.
name: Braggio, A.
name: Giazotto, F.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We investigate the photon-mediated thermal transport between a superconducting electrode and a normal metal. When the quasiparticle contribution can be neglected, the photon-mediated channel becomes an efficient heat transport relaxation process for the superconductor at low temperatures, being larger than the intrinsic contribution due to the electron-phonon interaction. Furthermore, the superconductor-normal metal system acts as a nearly-perfect thermal diode, with a rectification factor up to $10^8$ for a realistic aluminum superconducting island. The rectification factor can be also tuned in a phase-controlled fashion through a non-galvanic coupling, realized by changing the magnetic flux piercing a superconducting quantum interference device (SQUID), which modifies the coupling impedance between the superconductor and the normal metal. The scheme can be exploited for passive cooling in superconducting quantum circuits by transferring heat toward normal metallic pads where it dissipates more efficiently or for more general thermal management purposes.
A scan for new N=1 vacua on twisted tori
Creators: name: Graña, Mariana
name: Minasian, Ruben
name: Petrini, Michela
name: Tomasiello, Alessandro
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We perform a systematic search for N=1 Minkowski vacua of type II string theories on compact six-dimensional parallelizable nil- and solvmanifolds (quotients of six-dimensional nilpotent and solvable groups, respectively). Some of these manifolds have appeared in the construction of string backgrounds and are typically called twisted tori. We look for vacua directly in ten dimensions, using the a reformulation of the supersymmetry condition in the framework of generalized complex geometry. Certain algebraic criteria to establish compactness of the manifolds involved are also needed. Although the conditions for preserved N=1 supersymmetry fit nicely in the framework of generalized complex geometry, they are notoriously hard to solve when coupled to the Bianchi identities. We find solutions in a large-volume, constant-dilaton limit. Among these, we identify those that are T-dual to backgrounds of IIB on a conformal T^6 with self-dual three-form flux, and hence conceptually not new. For all backgrounds of this type fully localized solutions can be obtained. The other new solutions need multiple intersecting sources (either orientifold planes or combinations of O-planes and D-branes) to satisfy the Bianchi identities; the full list of such new solution is given. These are so far only smeared solutions, and their localization is yet unknown. Although valid in a large-volume limit, they are the first examples of Minkowski vacua in supergravity which are not connected by any duality to a Calabi-Yau. Finally, we discuss a class of flat solvmanifolds that may lead to AdS_4 vacua of type IIA strings.
description: 75 pages, 1 figure. v.2: minor corrections, references added; v3: several changes and clarifications
In-situ measurements of whole-dish reflectivity for VERITAS
Creators: name: Archambault, Simon
name: Chernitsky, Gabriel
name: Griffin, Sean
name: Hanna, David
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The VERITAS array is a set of four imaging atmospheric Cherenkov telescopes (IACTs) sensitive to gamma rays with energies above 80 GeV. Each telescope is based on a tessellated mirror, 12 metres in diameter, which reflects light from a gamma-ray-induced air shower to form an image on a pixellated `camera' comprising 499 photomultiplier tubes. The image brightness is the primary measure of the gamma ray's energy so a knowledge of the mirror reflectivity is important. We describe here a method, pioneered by members of the MAGIC collaboration, to measure the whole-dish reflectivity, quickly and regularly, so that effects of mirror aging can be monitored. A CCD camera attached near the centre of the dish simultaneously acquires an image of both a star and its reflection on a target made of Spectralon, a highly-reflective material, placed at the focus of the telescope. The ratio of their brightnesses, as recorded by the CCD, along with geometric factors, provides an estimate of the dish reflectivity with few systematic errors. A filter wheel is deployed with the CCD camera, allowing one to measure the reflectivity as a function of wavelength. We present results obtained with the VERITAS telescopes since 2014.
description: 11 pages, 7 figures, Accepted for publication in Astroparticle Physics. arXiv admin note: text overlap with arXiv:1307.8358
Similarities and Differences between Coronal Holes and the Quiet Sun: Are Loop Statistics the Key?
Creators: name: Wiegelmann, T.
name: Solanki, S. K.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Coronal holes (CH) emit significantly less at coronal temperatures than quiet-Sun regions (QS), but can hardly be distinguished in most chromospheric and lower transition region lines. A key quantity for the understanding of this phenomenon is the magnetic field. We use data from SOHO/MDI to reconstruct the magnetic field in coronal holes and the quiet Sun with the help of a potential magnetic model. Starting from a regular grid on the solar surface we then trace field lines, which provide the overall geometry of the 3D magnetic field structure. We distinguish between open and closed field lines, with the closed field lines being assumed to represent magnetic loops. We then try to compute some properties of coronal loops. The loops in the coronal holes (CH) are found to be on average flatter than in the QS. High and long closed loops are extremely rare, whereas short and low-lying loops are almost as abundant in coronal holes as in the quiet Sun. When interpreted in the light of loop scaling laws this result suggests an explanation for the relatively strong chromospheric and transition region emission (many low-lying, short loops), but the weak coronal emission (few high and long loops) in coronal holes. In spite of this contrast our calculations also suggest that a significant fraction of the cool emission in CHs comes from the open flux regions. Despite these insights provided by the magnetic field line statistics further work is needed to obtain a definite answer to the question if loop statistics explain the differences between coronal holes and the quiet Sun.
description: 26 pages, 11 figures
THE PROBLEMS OF TRANSLATING MEDICAL TERMS IN "BABURNAME" INTO RUSSIAN
Creators: name: Altmisheva, Y.M.
Publisher: name: Zenodo
Year: 2024

description: The article analyzes the translation of medical terms based on the material of comparing the original and the translation of «Baburname» into Russian. The author considers the result of incorrect translation of terms from the point of view of the impact on the reader.
The fluid dynamics of collective vortex structures of plant-animal worms
Creators: name: Fortune, George T.
name: Worley, Alan
name: Sendova-Franks, Ana B.
name: Franks, Nigel R.
name: Leptos, Kyriacos C.
name: Lauga, Eric
name: Goldstein, Raymond E.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Fluid Dynamics (physics.flu-dyn)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Circular milling, a stunning manifestation of collective motion, is found across the natural world, from fish shoals to army ants. It has been observed recently that the plant-animal worm $Symsagittifera~roscoffensis$ exhibits circular milling behaviour, both in shallow pools at the beach and in Petri dishes in the laboratory. Here we investigate this phenomenon, through experiment and theory, from a fluid dynamical viewpoint, focusing on the effect that an established circular mill has on the surrounding fluid. Unlike systems such as confined bacterial suspensions and collections of molecular motors and filaments that exhibit spontaneous circulatory behaviour, and which are modelled as force dipoles, the front-back symmetry of individual worms precludes a stresslet contribution. Instead, singularities such as source dipoles and Stokes quadrupoles are expected to dominate. A series of models is analyzed to understand the contributions of these singularities to the azimuthal flow fields generated by a mill, in light of the particular boundary conditions that hold for flow in a Petri dish. A model that treats a circular mill as a rigid rotating disc that generates a Stokes flow is shown to capture basic experimental results well, and gives insights into the emergence and stability of multiple mill systems.
description: 28 pages, 9 figures; Supplementary Videos available at website of REG
Optimal, fast, and robust inference of reionization-era cosmology with the 21cmPIE-INN
Creators: name: Schosser, Benedikt
name: Heneka, Caroline
name: Plehn, Tilman
Publisher: name: arXiv
Year: 2024
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Modern machine learning will allow for simulation-based inference from reionization-era 21cm observations at the Square Kilometre Array. Our framework combines a convolutional summary network and a conditional invertible network through a physics-inspired latent representation. It allows for an efficient and extremely fast determination of the posteriors of astrophysical and cosmological parameters, jointly with well-calibrated and on average unbiased summaries. The sensitivity to non-Gaussian information makes our method a promising alternative to the established power spectra.
description: 15+10 pages, 11 figures
The Matrix-Forest Theorem and Measuring Relations in Small Social Groups
Creators: name: Chebotarev, Pavel
name: Shamis, Elena
Publisher: name: arXiv
Year: 2006
Subjects: subject: Combinatorics (math.CO)
subject: Information Retrieval (cs.IR)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: 05C50; 05C05; 15A51

description: We propose a family of graph structural indices related to the Matrix-forest theorem. The properties of the basic index that expresses the mutual connectivity of two vertices are studied in detail. The derivative indices that measure "dissociation," "solitariness," and "provinciality" of vertices are also considered. A nonstandard metric on the set of vertices is introduced, which is determined by their connectivity. The application of these indices in sociometry is discussed.
description: 10 pages
Stability of superfluids in tilted optical lattices with periodic driving
Creators: name: Cruickshank, Robbie
name: Di Carli, Andrea
name: Mitchell, Matthew
name: La Rooij, Arthur
name: Kuhr, Stefan
name: Creffield, Charles E.
name: Haller, Elmar
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Tilted lattice potentials with periodic driving play a crucial role in the study of artificial gauge fields and topological phases with ultracold quantum gases. However, driving-induced heating and the growth of phonon modes restrict their use for probing interacting many-body states. Here, we experimentally investigate phonon modes and interaction-driven instabilities of superfluids in the lowest band of a shaken optical lattice. We identify stable and unstable parameter regions and provide a general resonance condition. In contrast to the high-frequency approximation of a Floquet description, we use the superfluids' micromotion to analyze the growth of phonon modes from slow to fast driving frequencies. Our observations enable the prediction of stable parameter regimes for quantum-simulation experiments aimed at studying driven systems with strong interactions over extended time scales.
description: 12 pages, 9 figures
Dynamical environments of MU69 and similar objects
Creators: name: Rollin, Guillaume
name: Shevchenko, Ivan I.
name: Lages, José
Publisher: name: arXiv
Year: 2020
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We explore properties of the long-term dynamics of particles (moonlets, fragments, debris etc.) around KBO 2014 MU69 (Arrokoth), as well as around similar contact-binary objects potentially present in the Kuiper belt. The chaotic diffusion of particles inside the Hill sphere of MU69 (or, generally, a similar object) is studied by means of construction of appropriate stability diagrams and by application of analytical approaches generally based on the Kepler map theory. The formation and evolution of the particle clouds, due to the chaotic diffusion inside the Hill sphere, are studied and the cloud lifetimes are estimated.
Timescales of merger, starburst and AGN activity in radio galaxy B2 0648+27
Creators: name: Emonts, B. H. C.
name: Morganti, R.
name: Tadhunter, C. N.
name: Holt, J.
name: Oosterloo, T. A.
name: van der Hulst, J. M.
name: Wills, K. A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: In this paper we use neutral hydrogen HI and optical spectroscopic observations to compare the timescales of a merger event, starburst episode and radio-AGN activity in the radio galaxy B2 0648+27. We detect a large ring-like structure of HI in emission around the early-type host galaxy of B2 0648+27 (M_HI = 8.5 x 10^9 Msun, diameter = 190 kpc). We interpret this as the result of a major merger that occurred > 1.5 Gyr ago. From modelling optical long-slit spectra we find that a young stellar population of 0.3 Gyr, indicative of a past starburst event, dominates the stellar light throughout the galaxy. The off-set in time between the merger event and the starburst activity in B2 0648+27 suggests that the starburst was triggered in an advanced stage of the merger, which can be explained if the gas-rich progenitor galaxies contained a bulge. Although the exact age of the radio source remains uncertain, there appears to be a significant time-delay between the merger/starburst event and the current episode of radio-AGN activity. We also observe an outflow of emission-line gas in this system, which is likely related to superwinds driven by the stars that formed during the starburst event. We argue that the radio galaxy B2 0648+27 is a link in the evolutionary sequence between Ultra-Luminous Infrared Galaxies (ULIRGs) and genuine early-type galaxies.
description: 13 pages, 11 figures. Accepted for publication in A&A. A version with full resolution figures is available at http://www.astron.nl/~morganti/Papers/B2_0648.pdf
Deciphering the 3-D Orion Nebula-III: Structure on the NE boundary of the Orion-S Embedded Molecular Cloud
Creators: name: O'Dell, C. R.
name: Ferland, G. J.
name: Abel, N. P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We have extended the work of Papers I and II of this series to determine at higher spatial resolution the properties of the embedded Orion-S Molecular Cloud that lies within the ionized cavity of the Orion Nebula and of the thin ionized layer that lies between the Cloud and the observer. This was done using existing and new [NII](658.3 nm) and [OIII] (500.7 nm) spectra that map the central region of the Orion Nebula (the Huygens Region). However, it remains unclear how the surface brightness of the ionized layer on the Orion-S Molecular Cloud and that of a foreground Nearer Ionized Layer are linked, as the observations show they must be. It is shown that the Cloud modifies the outer parts of the Huygens Region in the direction of the extended hot X-ray gas.
description: 21pages, 7 figures Accepted Astrophysical Journal
CPT violation in long baseline neutrino experiments: a three flavor analysis
Creators: name: Dighe, Amol
name: Ray, Shamayita
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We explore possible signals of CPT violation in neutrinos in the complete three-flavor framework. Employing a systematic expansion in small parameters, we analytically estimate the CPT violating contributions to the survival probabilities of $ν_μ, \barν_μ, ν_e$ and $\barν_e$. The results indicate that, in spite of the large number of CPT violating parameters, only a small number of combinations are relevant for oscillation experiments. We identify the combinations that can be constrained at the long baseline experiments, and show that their contribution to the neutrino Hamiltonian can be bounded to $< 10^{-23}$ GeV, by considering the NOvA experiment for the muon sector, and neutrino factories for the electron sector.This formalism also allows us to translate the bounds on the parameters describing non-standard interactions of neutrinos into the bounds on CPT violating quantities.
description: v2: 23 pages, 8 figures, revtex4. A new section on non-standard interaction (NSI) of neutrinos added. Version to appear in Phys. Rev. D
Intrinsic fluctuations in random lasers
Creators: name: van der Molen, Karen L.
name: Mosk, Allard P.
name: Lagendijk, Ad
Publisher: name: arXiv
Year: 2006
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We present a quantitative experimental and theoretical study of shot-to-shot intensity fluctuations in the emitted light of a random laser. A model that clarifies these intrinsic fluctuations is developed. We describe the output versus input power graphs of the random laser with an effective spontaneous emission factor (beta factor).
description: accepted by Phys. Rev. A. submitted; 7 pages, 5 figures
Prognosis in multiple sclerosis : the predictors and prediction of specific functional impairments
Creators: name: Redekop, William Kenneth
Publisher: name: University of British Columbia
Year: 2009

description: The level of future impairment is difficult to predict with multiple sclerosis (MS). Previous MS prognosis studies have mainly examined mortality or overall impairment and have used limited analytic methods. The primary objectives of this study were to identify the predictors of later functional impairment and to determine how predictable these impairments are. A secondary objective was to compare prognosis modelling techniques. A retrospective cohort study was conducted using patient data from the Vancouver MS clinic (Canada). Some analyses used the level of impairment after 10-15 years of MS as an outcome and involved binary and ordinal logistic regression (BLR, OLR) modelling. Other analyses used the time from onset to a specific level of overall impairment (DSS 6) as the outcome and involved proportional hazards PH) modelling. Candidate predictors were demographic (e.g., onset age) or clinical (e.g., onset symptoms) in form. Model performance was assessed using both cross-validation and data from a Dutch clinic in Groningen. Indicators of performance included receiver-operator characteristic (ROC) curve analysis, Hosmer-Lemeshow chi-square analysis and Somers’ Dxy correlation analysis. Most of the previously recognized predictors were predictive of motor impairment. However, the predictive value of patient characteristics often depended on the type of impairment being predicted. Specific impairment types varied in their predictability. Moreover, differences in the distribution of impairment frequently resulted in underestimates of risk in the Dutch cohort. In terms of the patient characteristics identified as predictive, there was generally good agreement amongst the different models. OLR models performed as well as BLR models. While various predictors exist for all impairment types, the predictability of these impairments is low or moderate. In terms of patient counselling, knowledge of predictors can be communicated to patients about their prognosis. However, patients should also be informed that improved knowledge about predictors of impairments does not translate into high predictability of future function. Regarding the use of predictions in a patient care setting, only terms such as “low risk” or “high risk” should be used. Improvements to the modelling strategy as well as a better understanding of the underlying disease process should help to improve predictability.
Attosecond light pulse induced photo-association
Creators: name: Rivière, Paula
name: Ruiz, Camilo
name: Rost, Jan-Michael
Publisher: name: arXiv
Year: 2008
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We explore stimulated photo-association in the context of attosecond pump-probe schemes of atomic matter. An attosecond pulse -- the probe -- is used to induce photo-association of an electronic wave packet which had been created before, typically with an attosecond pump pulse at an atomic center different from the one of photo-association. We will show that the electron absorption is maximal for a certain delay between the pulses. Two ways of enhancing and controlling stimulated photo-association are proposed, namely using an additional infrared pulse to steer the electronic wave packet and using a train of attosecond pulses instead of a single pair. A direct application of ultrafast stimulated photo-association is the measurement of atomic distances.
description: 7 pages, 8 figures