cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Photon-jet correlations in $pp$ and $p \bar p$ collisions
Creators: name: Pietrycki, Tomasz
name: Szczurek, Antoni
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We compare results of the $k_t$-factorization approach and the next-to-leading order collinear-factorization approach for photon-jet correlations in $pp$ and $p \bar p$ collisions at RHIC and Tevatron energies. We discuss correlations in the azimuthal angle as well as in the two-dimensional space of transverse momentum of photon and jet. Different unintegrated parton distributions (UPDF) are included in the $k_t$-factorization approach. The results depend on UPDFs used. The standard collinear approach gives cross section comparable to the $k_t$-factorization approach. For correlations of the photon and any jet the NLO contributions dominate at relatively small azimuthal angles as well as for asymmetric transverse momenta. For correlations of the photon with the leading jet (the one having the biggest transverse momentum) the NLO approach gives zero contribution at $ϕ_{-} < π/2$ which opens a possibility to study higher-order terms and/or UPDFs in this region.
description: 14 pages, 17 figures
Generalized Vanishing Theorems for Yukawa Couplings in Heterotic Compactifications
Creators: name: Anderson, Lara B.
name: Gray, James
name: Larfors, Magdalena
name: Magill, Matthew
name: Schneider, Robin
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Heterotic compactifications on Calabi-Yau threefolds frequently exhibit textures of vanishing Yukawa couplings in their low energy description. The vanishing of these couplings is often not enforced by any obvious symmetry and appears to be topological in nature. Recent results in the literature used differential geometric methods to explain the origin of some of this structure. A vanishing theorem was given which showed that the effect could be attributed, in part, to the embedding of the Calabi-Yau manifolds of interest inside higher dimensional ambient spaces, if the gauge bundles involved descended from vector bundles on those larger manifolds. In this paper, we utilize an algebro-geometric approach to provide an alternative derivation of some of these results, and are thus able to generalize them to a much wider arena than has been considered before. For example, we consider cases where the vector bundles of interest do not descend from bundles on the ambient space. In such a manner we are able to highlight the ubiquity with which textures of vanishing Yukawa couplings can be expected to arise in heterotic compactifications, with multiple different constraints arising from a plethora of different geometric features associated to the gauge bundle.
description: 34 pages
Flat bands, electron interactions and magnetic order in magic-angle mono-trilayer graphene
Creators: name: Goodwin, Zachary A. H.
name: Klebl, Lennart
name: Vitale, Valerio
name: Liang, Xia
name: Gogtay, Vivek
name: van Gorp, Xavier
name: Kennes, Dante M.
name: Mostofi, Arash A.
name: Lischner, Johannes
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Starting with twisted bilayer graphene, graphene-based moiré materials have recently been established as a new platform for studying strong electron correlations. In this paper, we study twisted graphene monolayers on trilayer graphene and demonstrate that this system can host flat bands when the twist angle is close to the magic-angle of 1.16$^\circ$. When monolayer graphene is twisted on ABA trilayer graphene, the flat bands are not isolated, but are intersected by a Dirac cone with a large Fermi velocity. In contrast, graphene twisted on ABC trilayer graphene (denoted AtABC) exhibits a gap between flat and remote bands. Since ABC trilayer graphene and twisted bilayer graphene are known to host broken-symmetry phases, we further investigate the ostensibly similar magic angle AtABC system. We study the effect of electron-electron interactions in AtABC using both Hartree theory and an atomic Hubbard theory to calculate the magnetic phase diagram as a function of doping, twist angle, and perpendicular electric field. Our analysis reveals a rich variety of magnetic orderings, including ferromagnetism and ferrimagnetism, and demonstrates that a perpendicular electric field makes AtABC more susceptible to magnetic ordering.
Electron scattering by magnetic impurity in Weyl semimetals
Creators: name: Díaz-Fernández, A.
name: Domínguez-Adame, F.
name: de Abril, O.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Weyl semimetals are prominent examples of topologically protected quantum matter. These materials are the three-dimensional counterparts of graphene and great efforts are being devoted to achieve a thorough understanding of their fundamental physics. In this work, we aim at contributing to this end by discussing the effect of a single magnetic impurity in Weyl semimetals as a first step towards considering a larger number of impurities. We find that resonances appear in the local density of states with a Friedel-like behaviour, oscillating as a function of distance. By studying the spin-resolved local density of states, we can observe non-trivial and anisotropic spin textures where the spin components perpendicular to the spin of the impurity wind around the latter, until the spin becomes completely parallel to the impurity right at the interface. Friedel oscillations also play a relevant role in the form of the spin textures, forming an oscillatory pattern. We believe our results can pave the way to further studies which consider the presence of a large number of random magnetic impurities.
Documento de Trabajo No. 12 | Ojos que no ven, ciudadanos que no votan… ¿Cómo se ha regulado el acceso a los medios de comunicación en tiempos electorales en América Latina?
Creators: name: Cáceres, Karina
Publisher: name: figshare
Year: 2021
Subjects: subject: 160699 Political Science not elsewhere classified
subject: FOS: Political science

description: Documento de Trabajo para el Observatorio de Reformas Electorales de América Latina (UNAM-México) donde se analizan las reformas electorales que los países de América Latina realizaron sobre el acceso a medios de comunicación en tiempos electorales.

reformas electorales, medios de comunicación, financiamiento público, campañas electorales
Biodiversidade: o que é?
Creators: name: Miyahira, Igor C.
name: Carvalho, Thuany Felipe
name: Neves, Raquel A. F.
Publisher: name: Zenodo
Year: 2024

description: Este produto técnico integra o projeto interinstitucional Meio Ambiente Informa, desenvolvido pela Pró-Reitoria de Extensão e Cultura (ProExC) da Universidade Federal do Estado do Rio de Janeiro (UNIRIO) e pelo Instituto Realizando o Futuro (IRF) sob convênio n° 941759/2023.
Applying the Principles of Augmented Learning to Photonics Laboratory Work
Creators: name: Fischer, Ulrich H. P.
name: Reinboth, Christian
name: Just, Jens-Uwe
name: Haupt, Matthias
Publisher: name: arXiv
Year: 2007
Subjects: subject: Optics (physics.optics)
subject: Popular Physics (physics.pop-ph)
subject: FOS: Physical sciences

description: This paper introduces "OPTOTEACH", a new teaching system for photonics lab work, designed by Harz University and successfully released on the German market by HarzOptics. OPTOTEACH is the first POF-WDM teaching system, specifically designed to cover a multitude of lab experiments in the field of optical communication technology. It is illustrated, how this lab system is supplemented by a newly developed optical teaching software - "OPTOSOFT" - and how the combination of system and software creates a unique augmented learning environment. The paper details, how the didactic concept for the software was conceptualised and introduces the latest beta version. OPTOSOFT is specifically designed not only as an attachment to OPTOTEACH, it also allows students to rehearse various aspects of theoretical optics and experience a fully interactive and feature-rich self-learning environment. The paper further details the first experiences educators at Harz University have made working with the lab system as well as the teaching software. So far, the augmented learning concept was received mostly positive, although there is some potential for further optimisation concerning integration and pacing of various interactive modules.
description: Published at the ETOP (Education and Training in Optics and Photonics) Conference in 2007
Effect of natural gamma background radiation on portal monitor radioisotope unmixing
Creators: name: Weiss, Matthew
name: Fang, Ming
name: Altmann, Yoann
name: Paff, Marc G.
name: Di Fulvio, Angela
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: National security relies on several layers of protection. One of the most important is the traffic control at borders and ports that exploits Radiation Portal Monitors (RPMs) to detect and deter potential smuggling attempts. Most portal monitors rely on plastic scintillators to detect gamma rays. Despite their poor energy resolution, their cost effectiveness and the possibility of growing them in large sizes makes them the gamma-ray detector of choice in RPMs. Unmixing algorithms applied to organic scintillator spectra can be used to reliably identify the bare and unshielded radionuclides that triggered an alarm, even with fewer than 1,000 detected counts and in the presence of two or three nuclides at the same time. In this work, we experimentally studied the robustness of a state-of-the-art unmixing algorithm to different radiation background spectra, due to varying atmospheric conditions, in the 16 $^\circ$C to 28 $^\circ$C temperature range. In the presence of background, the algorithm is able to identify the nuclides present in unknown radionuclide mixtures of three nuclides, when at least 1,000 counts from the sources are detected. With fewer counts available, we found larger differences of approximately 35.9$\%$ between estimated nuclide fractions and actual ones. In these low count rate regimes, the uncertainty associated by our algorithm with the identified fractions could be an additional valuable tool to determine whether the identification is reliable or a longer measurement to increase the signal-to-noise ratio is needed. Moreover, the algorithm identification performances are consistent throughout different data sets, with negligible differences in the presence of background types of different intensity and spectral shape.
Expanding and Self-Organizing 2D Universe Models Emerging from Frozen Trivalent Spin Networks
Creators: name: Dantas, Christine C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We revisit the topic of self-organized criticality (SOC) in simple statistical graph models, with the purpose of capturing essential processes leading to the emergence of macroscopic spacetime from the microscopic dynamics in loop quantum gravity (LQG). We performed a large set of simulations based on extensions of the frozen trivalent spin network (TSN) model explored previously by Ansari and Smolin. Their model mimicked the sandpile dynamics by the application of random vertex propagation rules in the TSN, leading to a SOC behavior in the distribution of the avalanche sizes, as well as a slowly expanding, $2$-dimensional dual (triangulated) space. Here we show that a growth scheme for the stochastic, slow external driving force, differing from the classical sandpile model, also resulted in power-law distributed avalanche sizes. Our simulations also produced expanding dual spaces, with two basic classes of evolution: one with power-law correlations in "space" and "time", and the other with "loitering" and exponential phases. Our work expands the range of models in which critical states in the TSN may lead to expansion effects in the dual space, without fine-tuning.
description: Revised version addressing comments by the referees: 22 pages, 7 figures, one appendix; conclusions were significantly expanded
Optimisation of the total population size with respect to the initial condition for semilinear parabolic equations: Two-scale expansions and symmetrisations
Creators: name: Mazari, Idriss
name: Nadin, Grégoire
name: Marrero, Ana Isis Toledo
Publisher: name: arXiv
Year: 2021
Subjects: subject: Analysis of PDEs (math.AP)
subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: 35Q92, 49J99, 34B15

description: In this article, we propose in-depth analysis and characterisation of the optimisers of the following optimisation problem: how to choose the initial condition $u_0$ in order to maximise the spatial integral at a given time of the solution of the semilinear equation $u_t-Δu=f(u)$, under $L^\infty$ and $L^1$ constraints on $u_0$? Our contribution in the present paper is to give a characterisation of the behaviour of the optimiser $\overline{u}_0$ when it does not saturate the $L^\infty$ constraints, which is a key step in implementing efficient numerical algorithms. We give such a characterisation under mild regularity assumptions by proving that in that case $\overline{u}_0$ can only take values in the "zone of concavity" of $f$. This is done using two-scale asymptotic expansions. We then show how well-known isoperimetric inequalities yield a full characterisation of maximisers when $f$ is convex. Finally, we provide several numerical simulations in one and two dimensions that illustrate and exemplify the fact that such characterisations significantly improves the computational time. All our theoretical results are in the one-dimensional case and we offer several comments about possible generalisations to other contexts, or obstructions that may prohibit doing so.
Accretion Disk Illumination in Schwarzschild and Kerr Geometries: Fitting Formulae
Creators: name: Fukumura, Keigo
name: Kazanas, Demosthenes
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We describe the methodology and compute the illumination of geometrically thin accretion disks around black holes of arbitrary spin parameter $a$ exposed to the radiation of a point-like, isotropic source at arbitrary height above the disk on its symmetry axis. We then provide analytic fitting formulae for the illumination as a function of the source height $h$ and the black hole angular momentum $a$. We find that for a source on the disk symmetry axis and $h/M > 3$, the main effect of the parameter $a$ is allowing the disk to extend to smaller radii (approaching $r/M \to 1$ as $a/M \to 1$) and thus allow the illumination of regions of much higher rotational velocity and redshift. We also compute the illumination profiles for anisotropic emission associated with the motion of the source relative to the accretion disk and present the fractions of photons absorbed by the black hole, intercepted by the disk or escaping to infinity for both isotropic and anisotropic emission for $a/M=0$ and $a/M=0.99$. As the anisotropy (of a source approaching the disk) increases the illumination profile reduces (approximately) to a single power-law, whose index, $q$, because of absorption of the beamed photons by the black hole, saturates to a value no higher than $q \gtrsim 3$. Finally, we compute the fluorescence Fe line profiles associated with the specific illumination and compare them among various cases.
description: 26 pages, 21 b/w figures, accepted for publication in the Astrophysical Journal as of 4/16/2007
Pseudospherical surfaces on time scales: a geometric definition and the spectral approach
Creators: name: Cieslinski, Jan L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Differential Geometry (math.DG)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 53A05, 39A12, 37K35, 52C07

description: We define and discuss the notion of pseudospherical surfaces in asymptotic coordinates on time scales. Thus we extend well known notions of discrete pseudospherical surfaces and smooth pseudosperical surfaces on more exotic domains (e.g, the Cantor set). In particular, we present a new expression for the discrete Gaussian curvature which turns out to be valid for asymptotic nets on any time scale. We show that asymptotic Chebyshev nets on an arbitrary time scale have constant negative Gaussian curvature. We present also the quaternion-valued spectral problem (the Lax pair) and the Darboux-Backlund transformation for pseudospherical surfaces (in asymptotic coordinates) on arbitrary time scales.
description: 20 pages
Characterization of Instrumental Phase Stability
Creators: name: Kubo, D. Y.
name: Hunter, T. R.
name: Christensen, R. D.
name: Yamaguchi, P. I.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Atmospheric water vapor causes significant undesired phase fluctuations for the Submillimeter Array (SMA) interferometer, particularly in its highest frequency observing band of 690 GHz. One proposed solution to this atmospheric effect is to observe simultaneously at two separate frequency bands of 230 and 690 GHz. Although the phase fluctuations have a smaller magnitude at the lower frequency, they can be measured more accurately and on shorter timescales due to the greater sensitivity of the array to celestial point source calibrators at this frequency. In theory, we can measure the atmospheric phase fluctuations in the 230 GHz band, scale them appropriately with frequency, and apply them to the data in 690 band during the post-observation calibration process. The ultimate limit to this atmospheric phase calibration scheme will be set by the instrumental phase stability of the IF and LO systems. We describe the methodology and initial results of the phase stability characterization of the IF and LO systems.
description: 10 pages, 12 figures, presented in poster form in May 2006 at the SPIE conference: Astronomical Telescopes and Instrumentation 2006, in the section on Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III
Universal spectral correlations from the ballistic sigma model
Creators: name: Müller, Jan
name: Micklitz, Tobias
name: Altland, Alexander
Publisher: name: arXiv
Year: 2007
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We consider the semiclassical ballistic sigma-model as an effective theory describing the quantum mechanics of classically chaotic systems. Specifically, we elaborate on close analogies to the recently developed semiclassical theory of quantum interference in chaotic systems and show how semiclassical 'diagrams' involving near action degenerate sets of periodic orbits emerge in the field theoretical description. We further discuss how the universality phenomenon (i.e. the fact that individual chaotic systems behave according to the prescriptions of random matrix theory) can be understood from the perspective of the field theory.
description: 10 pages, 3 figures
Localization of injective modules over arithmetical rings
Creators: name: Couchot, Francois
Publisher: name: arXiv
Year: 2007
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 13F05, 13C11

description: It is proved that localizations of injective $R$-modules of finite Goldie dimension are injective if $R$ is an arithmetical ring satisfying the following condition: for every maximal ideal $P$, $R_P$ is either coherent or not semicoherent. If, in addition, each finitely generated $R$-module has finite Goldie dimension, then localizations of finitely injective $R$-modules are finitely injective too. Moreover, if $R$ is a Prüfer domain of finite character, localizations of injective $R$-modules are injective.
Passive Control Architecture for Virtual Humans
Creators: name: Rennuit, Antoine
name: Micaelli, Alain
name: Merlhiot, Xavier
name: Andriot, Claude
name: Guillaume, François
name: Chevassus, Nicolas
name: Chablat, Damien
name: Chedmail, Patrick
Publisher: name: arXiv
Year: 2007
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: In the present paper, we introduce a new control architecture aimed at driving virtual humans in interaction with virtual environments, by motion capture. It brings decoupling of functionalities, and also of stability thanks to passivity. We show projections can break passivity, and thus must be used carefully. Our control scheme enables task space and internal control, contact, and joint limits management. Thanks to passivity, it can be easily extended. Besides, we introduce a new tool as for manikin's control, which makes it able to build passive projections, so as to guide the virtual manikin when sharp movements are needed.
Modified Coulomb Law in a Strongly Magnetized Vacuum
Creators: name: Shabad, Anatoly E.
name: Usov, Vladimir V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We study electric potential of a charge placed in a strong magnetic field B>>4.4x10^{13}G, as modified by the vacuum polarization. In such field the electron Larmour radius is much less than its Compton length. At the Larmour distances a scaling law occurs, with the potential determined by a magnetic-field-independent function. The scaling regime implies short-range interaction, expressed by Yukawa law. The electromagnetic interaction regains its long-range character at distances larger than the Compton length, the potential decreasing across the magnetic field faster than along. Correction to the nonrelativistic ground-state energy of a hydrogenlike atom is found. In the infinite-magnetic-field limit the modified potential becomes the Dirac delta-function plus a regular background. With this potential the ground-state energy is finite - the best pronounced effect of the vacuum polarization.
description: Revtex 4, 4 pages, 2 figures
Structure Calculation and Reconstruction of Discrete State Dynamics from Residual Dipolar Couplings using REDCRAFT
Creators: name: Cole, Casey A.
name: Mukhapadhyay, Rishi
name: Omar, Hanin
name: Hennig, Mirko
name: Valafar, Homayoun
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: Residual Dipolar Couplings (RDCs) acquired by Nuclear Magnetic Resonance (NMR) spectroscopy can be an indispensable source of information in investigation of molecular structures and dynamics. Here we present a complete strategy for structure calculation and reconstruction of discrete state dynamics from RDC data. Our method utilizes the previously presented REDCRAFT software package and its dynamic-profile analysis to complete the task of fragmented structure determination and identification of the onset of dynamics from RDC data. Fragmented structure determination was used to demonstrate successful structure calculation of static and dynamic domains for several models of dynamics. We provide a mechanism of producing an ensemble of conformations for the dynamical regions that describe any observed order tensor discrepancies between the static and dynamic domains within a protein. In addition, the presented method is capable of approximating relative occupancy of each conformational state. The developed methodology has been evaluated on simulated RDC data with 1Hz of error from an 83 residue α protein (PDBID 1A1Z), and a 213 residue α/\b{eta} protein DGCR8 (PDBID 2YT4). Using 1A1Z, various models of arc and complex two and three discrete-state dynamics were simulated. MD simulation was used to generate a 2-state dynamics for DGCR8. In both instances our method reproduced structure of the protein including the conformational ensemble to within less than 2Å. Based on our investigations, arc motions with more than 30° of rotation are recognized as internal dynamics and are reconstructed with sufficient accuracy. Furthermore, states with relative occupancies above 20% are consistently recognized and reconstructed successfully. Arc motions with magnitude of 15° or relative occupancy of less than 10% are consistently unrecognizable as dynamical regions.
Semiclassical Approach to Parametric Spectral Correlation with Spin 1/2
Creators: name: Nagao, Taro
name: Saito, Keiji
Publisher: name: arXiv
Year: 2007
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: The spectral correlation of a chaotic system with spin 1/2 is universally described by the GSE (Gaussian Symplectic Ensemble) of random matrices in the semiclassical limit. In semiclassical theory, the spectral form factor is expressed in terms of the periodic orbits and the spin state is simulated by the uniform distribution on a sphere. In this paper, instead of the uniform distribution, we introduce Brownian motion on a sphere to yield the parametric motion of the energy levels. As a result, the small time expansion of the form factor is obtained and found to be in agreement with the prediction of parametric random matrices in the transition within the GSE universality class. Moreover, by starting the Brownian motion from a point distribution on the sphere, we gradually increase the effect of the spin and calculate the form factor describing the transition from the GOE (Gaussian Orthogonal Ensemble) class to the GSE class.
description: 25 pages, 2 figures
Social networks and labour productivity in Europe: An empirical investigation
Creators: name: Di Guilmi, C.
name: Clementi, F.
name: Di Matteo, T.
name: Gallegati, M.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: This paper uses firm-level data recorded in the AMADEUS database to investigate the distribution of labour productivity in different European countries. We find that the upper tail of the empirical productivity distributions follows a decaying power-law, whose exponent $α$ is obtained by a semi-parametric estimation technique recently developed by Clementi et al. (2006). The emergence of "fat tails" in productivity distribution has already been detected in Di Matteo et al. (2005) and explained by means of a model of social network. Here we show that this model is tested on a broader sample of countries having different patterns of social network structure. These different social attitudes, measured using a social capital indicator, reflect in the power-law exponent estimates, verifying in this way the existence of linkages among firms' productivity performance and social network.
description: LaTeX2e; 18 pages with 3 figures; Journal of Economic Interaction and Coordination, in press
On the two-loop contributions to the pion mass
Creators: name: Kaiser, Roland
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We derive a simplified representation for the pion mass to two loops in three-flavour chiral perturbation theory. For this purpose, we first determine the reduced expressions for the tensorial two-loop 2-point sunset integrals arising in chiral perturbation theory calculations. Making use of those relations, we obtain the expression for the pion mass in terms of the minimal set of master integrals. On the basis of known results for these, we arrive at an explicit analytic representation, up to the contribution from K-K-eta intermediate states where a closed-form expression for the corresponding sunset integral is missing. However, the expansion of this function for a small pion mass leads to a simple representation which yields a very accurate approximation of this contribution. Finally, we also give a discussion of the numerical implications of our results.
description: Typos corrected and minor changes in Table 2. Published version. 19 pages, 1 figure, 2 tables
Non-Markovian entanglement dynamics of noisy continuous variable quantum channels
Creators: name: An, Jun-Hong
name: Zhang, Wei-Min
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the entanglement dynamics of continuous-variable quantum channels in terms of an entangled squeezed state of two cavity fields in a general non-Markovian environment. Using the Feynman-Vernon influence functional theory in the coherent-state representation, we derive an exact master equation with time-dependent coefficients reflecting the non-Markovian influence of the environment. The influence of environments with different spectral densities, e.g., Ohmic, sub-Ohmic, and super-Ohmic, is numerically studied. The non-Markovian process shows its remarkable influences on the entanglement dynamics due to the sensitive time-dependence of the dissipation and noise functions within the typical time scale of the environment. The Ohmic environment shows a weak dissipation-noise effect on the entanglement dynamics, while the sub-Ohmic and super-Ohmic environments induce much more severe noise. In particular, the memory of the system interacting with the environment contributes a strong decoherence effect to the entanglement dynamics in the super-Ohmic case.
description: The final version
Charmed Meson Production in Deep Inelastic Scattering
Creators: name: Floter, B.
name: Kopeliovich, B. Z.
name: Pirner, H. J.
name: Raufeisen, J.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Charmed meson production in semi-inclusive deep inelastic scattering is investigated in the color dipole formalism. The transverse momentum distributions are calculated. We find good agreement with the H1 data using a hard fragmentation function.
description: 24 pages, 10 figures
Quantum Fisher Cosmology: Confronting Observations and the Trans-Planckian Problem
Creators: name: Gomez, Cesar
name: Jimenez, Raul
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The aim of Quantum Fisher Cosmology is to use the quantum Fisher information about pure de Sitter states to derive model independent observational consequences of the existence of a primordial phase of the Universe of de Sitter accelerated expansion. These quantum features are encoded in a scale dependent quantum cosmological tilt that defines what we can call the de Sitter universality class. The experimental predictions are: i) A phase transition from red into blue tilt at a scale order $k= 1$ Mpc$^{-1}$ that naturally solves the cosmological trans-Planckian problem, ii) A spectral index for curvature fluctuations at CMB scales $k= 0.05$ Mpc$^{-1}$ equal to $0.0328$, iii) A tilt running at scale $k=0.002$ Mpc$^{-1}$ equal to $-0.0019$, iv) An enhancement of the amplitude of CMB peaks for extremely high multipoles ($l > 10^5$) that can provide a natural mechanism for primordial black hole formation as a source of dark matter, v) A lack of power at scales of $8$ Mpc with respect to the CMB scale that can explain the $σ_8$ tension.
description: Matches accepted version to JCAP. Added a longer explanation on the role of the alpha-vacua and how quantum fisher is evaluated in their presence. Results unchanged
Post-buckling Dynamics of Spherical Shells
Creators: name: Mokbel, Marcel
name: Djellouli, Adel
name: Quilliet, Catherine
name: Aland, Sebastian
name: Coupier, Gwennou
Publisher: name: arXiv
Year: 2021
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Classical Physics (physics.class-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We explore the intrinsic dynamics of spherical shells immersed in a fluid in the vicinity of their buckled state, through experiments and 3D axisymmetric simulations. The results are supported by a theoretical model that accurately describes the buckled shell as a two-variable-only oscillator. We quantify the effective "softening" of shells above the buckling threshold, as observed in recent experiments on interactions between encapsulated microbubbles and acoustic waves. The main dissipation mechanism in the neighboring fluid is also evidenced.
Reactive Navigation Framework for Mobile Robots by Heuristically Evaluated Pre-sampled Trajectories
Creators: name: Akmandor, Neşet Ünver
name: Padır, Taşkın
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: This paper describes and analyzes a reactive navigation framework for mobile robots in unknown environments. The approach does not rely on a global map and only considers the local occupancy in its robot-centered 3D grid structure. The proposed algorithm enables fast navigation by heuristic evaluations of pre-sampled trajectories on-the-fly. At each cycle, these paths are evaluated by a weighted cost function, based on heuristic features such as closeness to the goal, previously selected trajectories, and nearby obstacles. This paper introduces a systematic method to calculate a feasible pose on the selected trajectory, before sending it to the controller for the motion execution. Defining the structures in the framework and providing the implementation details, the paper also explains how to adjust its offline and online parameters. To demonstrate the versatility and adaptability of the algorithm in unknown environments, physics-based simulations on various maps are presented. Benchmark tests show the superior performance of the proposed algorithm over its previous iteration and another state-of-art method. The open-source implementation of the algorithm and the benchmark data can be found at \url{https://github.com/RIVeR-Lab/tentabot}.
description: This paper is published by International Journal of Robotic Computing (IJRC). arXiv admin note: substantial text overlap with arXiv:2001.09199
title: Process-Reengineering im Zusammenhang mit der galvanischen Beschichtung einer Dieselmotor-Komponente
Creators: name: Kleinsasser, Alexander
Publisher: name: TU Wien
Year: 2022
Subjects: subject: Prozessoptimierung
subject: Lean Management
subject: Produktionsoptimierung

description: Arbeit an der Bibliothek noch nicht eingelangt - Daten nicht geprueft - gesperrte Arbeit (bis 2024-01-26+01:00)
description: Abweichender Titel nach Übersetzung der Verfasserin/des Verfassers
Extreme Emission-Line Galaxies in SDSS. I. Empirical and model-based calibrations of chemical abundances
Creators: name: Pérez-Montero, E.
name: Amorín, R.
name: Almeida, J. Sánchez
name: Vílchez, J. M.
name: García-Benito, R.
name: Kehrig, C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Local star-forming galaxies show properties that are thought to differ from galaxies in the early Universe. Among them, the ionizing stellar populations and the gas geometry make the recipes designed to derive chemical abundances from nebular emission lines to differ from those calibrated in the Local Universe. A sample of 1969 Extreme Emission Line Galaxies (EELGs) at a redshift 0 < z < 0.49, selected from the Sloan Digital Sky Survey (SDSS) to be local analogues of high-redshift galaxies, was used to analyze their most prominent emission lines and to derive total oxygen abundances and nitrogen-to-oxygen ratios following the direct method in the ranges 7.7 < 12+log(O/H) < 8.6 and -1.8 < log(N/O) < -0.8. They allow us to obtain new empirically calibrated strong-line methods and to evaluate other recipes based on photoionization models that can be later used for a chemical analysis of actively star-forming galaxies in very early stages of galaxy evolution. Our new relations are in agreement with others found for smaller samples of objects at higher redshifts. When compared with other relations calibrated in the local Universe, they differ when the employed strong-line ratio depends on the hardness of the ionizing radiation, such as O32 or Ne3O2, but they do not when the main dependence is on the ionization parameter, such as S23. In the case of strong-line ratios depending on [NII] lines, the derivation of O/H becomes very uncertain due to the very high N/O values derived in this sample, above all in the low-metallicity regime. Finally, we adapt the bayesian-like code HII-Chi-mistry for the conditions found in this kind of galaxies and we prove that it can be used to derive within errors both O/H and N/O, in consistency with the direct method .
description: 16 pages, 13 figures. Accepted for publication by MNRAS
Ανάπτυξη νέων νανοσύνθετων υλικών εποξειδικών ρητίνων με προηγμένες νανοδομές πυριτίας
Creators: name: Γκιλιόπουλος, Δημήτρης Ι.
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Νανοσύνθετα Πολυμερή
Εποξειδικές Ρητίνες
Μεσοπορώδης Πυριτία
Οργανική Τροποποίηση
Polymer Nanocomposites
Epoxy Resins
Mesoporous Silica
Organic Functionalization

description: Σκοπός της παρούσας διατριβής είναι η παρασκευή νανοσύνθετων ελαστομερών και υαλωδών εποξειδικών πολυμερών χρησιμοποιώντας νανοδομημένες μεσοπορώδεις πυριτίες τύπου SBA-15 και MCF, καθώς και μικρο/νανοσωματίδια πυριτίας τύπου PEI-SiO2 και η μελέτη των μηχανικών, θερμομηχανικών και θερμικών ιδιοτήτων τους. Πιο συγκεκριμένα, θα εξεταστούν η επίδραση της συγκέντρωσης, του πορώδους, της μορφολογίας και της οργανικής τροποποίησης των νανοδομημένων πυριτίων. Επίσης, οι ιδιότητες των νέων νανοσύνθετων υλικών θα συγκριθούν με αυτές νανοσύνθετων υλικών με περισσότερο κλασσικά νανοπρόσθετα, όπως φυλλόμορφες αργίλους, νανοσωλήνες άνθρακα και πυρογενής νανο-πυριτία.
description: The aim of the present thesis is the production of rubbery and glassy nanocomposite epoxy polymers using nanostructured mesoporous silica of SBA-15 and MCF type, as well as micro/nanoparticle silica of PEI-SiO2 type and the study of the mechanical, thermomechanical and thermal properties. More specifically, the effect of concentration, porosity, morphology and organic functionalization of nanostructured silica will be examined. Additionally, the properties of the novel nanocomposite materials will be compared with those of nanocomposite materials with classic nanoadditives, such as layered silicates, carbon nanotubes and fumed nanosilica.
Spatial prediction of sparse events using a discrete global grid system; a case study of hate crimes in the USA
Creators: name: Jendryke, Michael
name: McClure, Stephen C.
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Medicine
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics
subject: Science Policy
subject: Plant Biology

description: Spatial prediction of any geographic phenomenon can be an intractable problem. Predicting sparse and uncertain spatial events related to many influencing factors necessitates the integration of multiple data sources. We present an innovative approach that combines data in a Discrete Global Grid System (DGGS) and uses machine learning for analysis. A DGGS provides a structured input for multiple types of spatial data, consistent over multiple scales. This data framework facilitates the training of an Artificial Neural Network (ANN) to map and predict a phenomenon. Spatial lag regression models (SLRM) are used to evaluate and rank the outputs of the ANN. In our case study, we predict hate crimes in the USA. Hate crimes get attention from mass media and the scientific community, but data on such events is sparse. We trained the ANN with data ingested in the DGGS based on a 50% sample of hate crimes as identified by the Southern Poverty Law Center (SPLC). Our spatial prediction is up to 78% accurate and verified at the state level against the independent FBI hate crime statistics with a fit of 80%. The derived risk maps are a guide to action for policy makers and law enforcement.
Measurement of the e+e- -> K+K- cross section in the energy range s**(1/2) = 1.04 - 1.38 GeV with the SND detector in the experiment at the VEPP-2M e+e- collider
Creators: name: Achasov, M. N.
name: Beloborodov, K. I.
name: Berdyugin, A. V.
name: Bogdanchikov, A. G.
name: Bukin, A. D.
name: Bukin, D. A.
name: Dimova, T. V.
name: Druzhinin, V. P.
name: Golubev, V. B.
name: Koop, I. A.
name: Korol, A. A.
name: Koshuba, S. V.
name: Pakhtusova, E. V.
name: Perevedentsev, E. A.
name: Serednyakov, S. I.
name: Shatunov, Yu. M.
name: Silagadze, Z. K.
name: Skrinsky, A. N.
name: Usov, Yu. V.
name: Vasiljev, A. V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The cross section of the process $e^+e^- \to K^+K^-$ was measured in the energy range $\sqrt{s}$ = 1.04--1.38 GeV in the SND experiment at the VEPP-2M $e^+e^-$ collider. The measured cross section is described by the model of vector meson dominance with contributions from the light vector mesons $ρ$, $ω$, $ϕ$ and their lowest excitations. The mean statistical accuracy of the measurement is 4.4 %, and the systematic uncertainty is 5.2 %.
description: 20 pages, 11 figures
Metastable two-component solitons near an exceptional point
Creators: name: Zezyulin, Dmitry A.
name: Kartashov, Yaroslav V.
name: Konotop, Vladimir V.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We consider a two-dimensional nonlinear waveguide with distributed gain and losses. The optical potential describing the system consists of an unperturbed complex potential depending only on one transverse coordinate, i.e., corresponding to a planar waveguide, and a small non-separable perturbation depending on both transverse coordinates. It is assumed that the spectrum of the unperturbed planar waveguide features an exceptional point (EP), while the perturbation drives the system into the unbroken phase. Slightly below the EP, the waveguide sustains two-component envelope solitons. We derive one-dimensional equations for the slowly varying envelopes of the components and show their stable propagation. When both traverse directions are taken into account within the framework of the original model, the obtained two-component bright solitons become metastable and persist over remarkably long propagation distances.
description: 9 pages, 5 figures; several typos corrected; final version
CP violation in unpolarized e^+ e^- to charginos at one loop level
Creators: name: Osland, P.
name: Vereshagin, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study CP violation in e^+ e^- to \tildeχ_i^+\tildeχ_j^- in the framework of the MSSM. Though the cross section of this process is CP-even at the tree level even for polarized electron-positron beams, we show that it contains a CP-odd part at the one loop order and there are CP-odd observables that can in principle be measured even using unpolarized electron-positron beams. The relevant diagram calculations are briefly discussed and the results of selected (box) diagram computations are shown.
description: similar to Phys. Rev. D version, but corrected figs. 4, 5, 6 (factor four)
Blue laser cooling transitions in Tm I
Creators: name: Kolachevsky, N.
name: Akimov, A.
name: Tolstikhina, I.
name: Chebakov, K.
name: Sokolov, A.
name: Rodionov, P.
name: Kanorski, S.
name: Sorokin, V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We have studied possible candidates for laser cooling transitions in $^{169}$Tm in the spectral region 410 -- 420 nm. By means of saturation absorption spectroscopy we have measured the hyperfine structure and rates of two nearly closed cycling transitions from the ground state $4\textrm{f}^{13}6\textrm{s}^2(^2\textrm{F}_0)(J_g=7/2)$ to upper states $4\textrm{f}^{12}(^3\textrm{H}_5)5\textrm{d}_{3/2}6\textrm{s}^2(J_e=9/2)$ at 410.6 nm and $4\textrm{f}^{12}(^3\textrm{F}_4)5\textrm{d}_{5/2}6\textrm{s}^2(J_e=9/2)$ at 420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and 48(6) ns respectively. Decay rates from these levels to neighboring opposite-parity levels are evaluated by means of Hartree-Fock calculations. We conclude, that the strong transition at 410.6 nm has an optical leak rate of less then $2\cdot10^{-5}$ and can be used for efficient laser cooling of $^{169}$Tm from a thermal atomic beam. The hyperfine structure of two other even-parity levels which can be excited from the ground state at 409.5 nm and 418.9 nm is also measured by the same technique. In addition we give a calculated value of $7(2)$ s$^{-1}$ for the rate of magnetic-dipole transition at 1.14 $μ$m between the fine structure levels $(J_g=7/2)\leftrightarrow(J'_g=5/2)$ of the ground state which can be considered as a candidate for applications in atomic clocks.
description: 8 pages, 5 figures
คุณลักษณะตามสภาพจริงและคุณลักษณะที่พึงประสงค์ของบัณฑิตระดับปริญญาตรีตามความคิดเห็นขององค์กรผู้ใช้บัณฑิตในจังหวัดนครศรีธรรมราช
Creators: name: พรณพัชร วิมลทรง
Publisher: name: วิทยาลัยเทคโนโลยีภาคใต้
Year: 2555
Subjects: คุณลักษณะตามสภาพจริง, คุณลักษณะที่พึงประสงค์, บัณฑิตระดับปริญญาตรี, ผู้ใช้บัณฑิต

description: 2, 5, วารสารเทคโนโลยีภาคใต้
Water vapor and silicon monoxide maser observations in the protoplanetary nebula OH 231.8+4
Creators: name: Desmurs, J. -F.
name: Alcolea, J.
name: Bujarrabal, V.
name: Contreras, C. Sanchez
name: Colomer, F.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: OH 231.8+4.2 is a well studied preplanetary nebula (pPN) around a binary stellar system that shows a remarkable bipolar outflow. To study the structure and kinematics of the inner 10-80 AU nebular regions we performed high-resolution observations of the H$_2$O 6$_{1,6}$--5$_{2,3}$ and $^{28}$SiO $v$=2, $J$=1--0 maser emissions with the Very Long Baseline Array. The absolute position of both emission distributions were recovered using the phase referencing technique, and accurately registered in HST optical images. H$_2$O maser clumps are found to be distributed in two areas of 20 mas in size spatially displaced by $\sim$60 milli-arcseconds along an axis oriented nearly north-south. SiO masers are tentatively found to be placed between the two H$_2$O maser emitting regions, probably indicating the position of the Mira component of the system. The SiO maser emission traces an inner equatorial component with a diameter of 12 AU, probably a disk rotating around the M-type star. Outwards, we detect in the H$_2$O data a pair of polar caps, separated by 80 AU. We believe that the inner regions of the nebula probably have been altered by the presence of the companion, leading to an equator-to-pole density contrast that may explain the lack of H$_2$O masers and strong SiO maser emission in the denser, equatorial regions.
description: 5 pages, 1 figure, A&A accepted