cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Couplings between a single massless tensor field with the mixed symmetry (3,1) and one vector field
Creators: name: Bizdadea, C.
name: Ciobirca, C. C.
name: Negru, I.
name: Saliu, S. O.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Under the hypotheses of smoothness in the coupling constant, locality, Lorentz covariance, and Poincare invariance of the deformations, combined with the preservation of the number of derivatives on each field, the consistent interactions between a single free massless tensor gauge field with the mixed symmetry of a two-column Young diagram of the type (3,1) and one Abelian vector field have been investigated. The computations are done with the help of the deformation theory based on a cohomological approach, in the context of the antifield-BRST formalism. The main result is that there exist nontrivial cross-couplings between these types of fields in five spatiotemporal dimensions, which break the PT invariance and allow for the deformation of the gauge transformations of the vector field, but not of the gauge algebra.
description: LaTeX, 34 pages
Nonlinear dynamics in an alternating gradient guide for neutral particles
Creators: name: Tarbutt, M. R.
name: Hinds, E. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: Neutral particles can be guided and focussed using electric field gradients that focus in one transverse direction and defocus in the other, alternating between the two directions. Such a guide is suitable for transporting particles that are attracted to strong electric fields, which cannot be guided using static fields. Particles are only transmitted if their initial positions and transverse speeds lie within the guide's phase space acceptance. Nonlinear forces are always present in the guide and can severely reduce this acceptance. We consider the effects of the two most important nonlinear forces, a term in the force that is cubic in the off-axis displacement, and a nonlinear term which couples together the two transverse motions. We use approximate analytical techniques, along with numerical methods, to calculate the influence of these nonlinear forces on the particle trajectories and on the phase space acceptance. The cubic term alters the focussing and defocussing powers, leading either to an increase or a decrease of the acceptance depending on its sign. We find an approximate analytical result for the phase space acceptance including this cubic term. Using a perturbation method we show how the coupling term leads to slow changes in the amplitudes of the transverse oscillations. This term reduces the acceptance when it reduces the focussing power, but has little influence when it increases that power. It is not possible to eliminate both nonlinear terms, but one can be made small at the expense of the other. We show how to choose the guide parameters so that the acceptance is optimized.
description: 31 pages, 12 figures
Massive Lyman Break Galaxies at z~3 in the Spitzer Extragalactic First Look Survey
Creators: name: Shim, Hyunjin
name: Im, Myungshin
name: Choi, Phillip
name: Yan, Lin
name: Storrie-Lombardi, Lisa
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate the properties of 1088 Lyman Break Galaxies (LBGs) at z~3 selected from a ~2.63$ deg2 sub-region of the First Look Survey field using the ground-based multi-color data and the Spitzer Space Telescope mid-infrared data at 3--8 and 24 um. With the wide area and the broad wavelength coverage, we sample a large number of ``rare'' u-band dropouts which are massive (M* > 10^11 Msun), allowing us to perform a statistical analysis of these subsets of LBGs that have not been studied in detail. Optically bright (R(AB) < 24.5 mag) LBGs detected in mid-infrared (S_{3.6um} > 6 uJy) reside at the most massive and dusty end of the LBG population, with relatively high and tight $M/L$ in rest-frame near-infrared. Most infrared-luminous LBGs (S_{24um} > 100 uJy) are dusty star-forming galaxies with star formation rates of 100--1000 Msun/yr, total infrared luminosity of > 10^12 Lsun. By constructing the UV luminosity function of massive LBGs, we estimate that the lower limit for the star formation rate density from LBGs more massive than 10^11 Msun at z~3 is > 3.3 x 10^-3 Msun/yr/Mpc^3, showing for the first time that the UV-bright population of massive galaxies alone contributes significantly to the global star formation rate density at z~3. When combined with the star formation rate densities at z < 2, our result reveals a steady increase in the contribution of massive galaxies to the global star formation from z=0 to z=3, providing strong support to the downsizing of galaxy formation.
description: 15 pages, 13 figures. Accepted for publication in ApJ
Photometric redshifts with machine learning, lights and shadows on a complex data science use case
Creators: name: Brescia, Massimo
name: Cavuoti, Stefano
name: Razim, Oleksandra
name: Amaro, Valeria
name: Riccio, Giuseppe
name: Longo, Giuseppe
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The current role of data-driven science is constantly increasing its importance within Astrophysics, due to the huge amount of multi-wavelength data collected every day, characterized by complex and high-volume information requiring efficient and as much as possible automated exploration tools. Furthermore, to accomplish main and legacy science objectives of future or incoming large and deep survey projects, such as JWST, LSST and Euclid, a crucial role is played by an accurate estimation of photometric redshifts, whose knowledge would permit the detection and analysis of extended and peculiar sources by disentangling low-z from high-z sources and would contribute to solve the modern cosmological discrepancies. The recent photometric redshift data challenges, organized within several survey projects, like LSST and Euclid, pushed the exploitation of multi-wavelength and multi-dimensional data observed or ad hoc simulated to improve and optimize the photometric redshifts prediction and statistical characterization based on both SED template fitting and machine learning methodologies. But they also provided a new impetus in the investigation on hybrid and deep learning techniques, aimed at conjugating the positive peculiarities of different methodologies, thus optimizing the estimation accuracy and maximizing the photometric range coverage, particularly important in the high-z regime, where the spectroscopic ground truth is poorly available. In such a context we summarize what learned and proposed in more than a decade of research.
description: Preprint version of the manuscript to appear in the Volume: "The Physical Challenges of Astrostatistics", special issue of "Frontiers in Astronomy and Space Sciences"
Primordial massive supernovae as the first molecular factories in the early universe
Creators: name: Cherchneff, Isabelle
name: Lilly, Simon
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the ejecta chemistry of a zero-metallicity progenitor, massive, supernova using a novel approach based on chemical kinetics. Species considered span the range of simple, di-atomic molecules such as CO or SiO to more complex species involved in dust nucleation processes. We describe their formation from the gas phase including all possible relevant chemical processes and apply it to the ejecta of a primordial 170 Msun supernova. Two ejecta cases are explored: full mixing of the heavy elements, and a stratified ejecta reflecting the progenitor nucleosynthesis. Penetration of hydrogen from the progenitor envelope is considered. We show that molecules form very efficiently in the ejecta of primordial supernovae whatever the level of mixing and account for 13 to 34% of the total progenitor mass, equivalent to 21 to 57 Msun of the ejecta material in molecular form. The chemical nature of molecules depends on mixing of heavy elements and hydrogen in the ejecta. Species produced include O2, CO, CO2, SiS, SO, SiO and H2. Consequently, molecules can be used as observational tracers of supernova mixing after explosion. We conclude that primordial massive supernovae are the first molecule providers to the early universe.
description: Accepted to the ApJ Letters
Simulation of electromagnetic transients in underground cables with frequency-dependent modal transformation matrics
Creators: name: Marti, Luis
Publisher: name: University of British Columbia
Year: 2010

description: This thesis presents a new model to simulate the behaviour of underground cable systems under transient conditions. The new cable model belongs to the class of time-domain, frequency-dependent models, and it is directly compatible with the solution algorithm of the EMTP (Electromagnetic Transients Program). The most important feature of the new model is that it takes into account the frequency dependence of the modal transformation matrices and cable parameters, thus overcoming the main limitation of currently-used transmission line and cable models, which assume that the modal transformation matrices are constant Conceptually, the new model is relatively simple. The system parameters which define the behaviour of an underground cable (namely the modal characteristic admittance matrix, the modal propagation matrix, and the modal transformation matrix), are expressed in closed form by approximating them with rational functions in the frequency domain. Therefore, in the time domain, all numerical convolutions can be expressed recursively. The host transients program (to which the model is interfaced) sees the new model as a constant, real admittance matrix, in parallel with a continuously-updated vector current source. The accurate approximation by rational functions of the modal transformation matrix is possible when its elements are continuous and smooth functions of frequency. Standard eigenvalue/eigenvector algorithms are not well suited for this purpose. Therefore, a new procedure to generate eigenvalues and eigenvectors has been developed. This procedure is based on the Jacobi method, and it produces the desired smooth functions of frequency. This manuscript presents a number of simulations where the performance of the new cable model is compared with exact analytical solutions. These simulations show an excellent agreement between analytical and numerical answers. The effects of not taking into account the frequency dependence of the modal transformation matrices is illustrated with the simulation of a line-to-ground fault on a three-phase cable. The response of the new cable model is also compared with results measured in a field test The new cable model is numerically stable. Its computational speed is comparable to that of frequency-dependent line models with constant transformation matrices. The new cable model is general. Its extension to the simulation of multiple-circuit overhead transmission lines should also be of considerable practical importance.
Creatable Universes
Creators: name: Ferrando, Joan Josep
name: Lapiedra, Ramon
name: Morales, Juan Antonio
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We consider the question of properly defining energy and momenta for non asymptotic Minkowskian spaces in general relativity. Only spaces of this type, whose energy, linear 3-momentum, and intrinsic angular momentum vanish, would be candidates for creatable universes, that is, for universes which could have arisen from a vacuum quantum fluctuation. Given a universe, we completely characterize the family of coordinate systems for which one could sensibly say that this universe is a creatable universe.
description: 19 pages; v2: we have added an Appendix to make explicit the proof of the quasi-uniqueness of the defined energy and momenta of the Universe, for every space-like 3-surface
Deep u*- and g-band Imaging of the Spitzer Space Telescope First Look Survey Field : Observations and Source Catalogs
Creators: name: Shim, Hyunjin
name: Im, Myungshin
name: Pak, Soojong
name: Choi, Phillip
name: Fadda, Dario
name: Helou, George
name: Storrie-Lombardi, Lisa
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present deep u*-, and g-band images taken with the MegaCam on the 3.6 m Canada-France-Hawaii Telescope (CFHT) to support the extragalactic component of the Spitzer First Look Survey (hereafter, FLS). In this paper we outline the observations, present source catalogs and characterize the completeness, reliability, astrometric accuracy and number counts of this dataset. In the central 1 deg2 region of the FLS, we reach depths of g~26.5 mag, and u*~26.2 mag (AB magnitude, 5$σ$ detection over a 3" aperture) with ~4 hours of exposure time for each filter. For the entire FLS region (~5 deg2 coverage), we obtained u*-band images to the shallower depth of u*=25.0--25.4 mag (5$σ$, 3" aperture). The average seeing of the observations is 0.85" for the central field, and ~1.00" for the other fields. Astrometric calibration of the fields yields an absolute astrometric accuracy of 0.15" when matched with the SDSS point sources between 18
description: 15 pages, 16 figures
Systematic study of two-proton radioactivity with a screened electrostatic barrier
Creators: name: Zou, Y. T.
name: Pan, X.
name: Li, X. H.
name: Liu, H. M.
name: Wu, X. J.
name: He, B.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In this study, a phenomenological model is proposed based on Wentzel-Kramers-Brillouin (WKB) theory and applied to investigate the two-proton ($2p$) radioactive half-lives of nuclei near or beyond the proton drip line. The total diproton-daughter nucleus interaction potential is composed of the Hulthen-type electrostatic term and the centrifugal term. The calculated $2p$ radioactive half-lives can accurately reproduce the existing 10 experimental datasets of five true $2p$ radioactive nuclei with $σ$ = 0.736. In addition, we extend this model to predict the half-lives of possible $2p$ radioactive nuclei whose $2p$ radioactivity is energetically allowed or observed but not yet quantified in NUBASE2016. The predicted results are in agreement with those obtained using the Gamow-like model, generalized liquid drop model, Sreeja formula, and Liu formula.
description: 9 pages, 6 figures
La pittura di Ercolano
Creators: name: Esposito, Domenico
Publisher: name: Università degli Studi di Napoli Federico II
Year: 2006

description: Il presente studio si propone di analizzare nel suo insieme la pittura di Ercolano, che è ancora oggi in gran parte inedita. Lo scopo della ricerca è quello di analizzare il campione ercolanese alla luce delle dinamiche produttive della pittura romana in Campania. Il lavoro è stato articolato in tre sezioni. Nella prima è stato approfondito il rapporto tra spazio e decorazione, sia in ambito pubblico che in quello privato. Nella seconda sezione all’inquadramento di tipo tradizionale delle pitture, basato sull’approccio “stilistico”, è stato affiancato il riconoscimento delle mani dei pittori, allo scopo di rintracciare modalità operative e circolazione delle officine pittoriche. L’ultima sezione è dedicata alla discussione sulla ricostruzione del sistema economico e sociale e sulla cronologia delle pitture di IV stile ad Ercolano.
Additional file 1 of Quality-of-life measures and their psychometric properties used in African chronic kidney disease populations: a systematic review using COSMIN methodology
Creators: name: Faye, Moustapha
name: Manneville, Florian
name: Faye, Adama
name: Frimat, Luc
name: Guillemin, Francis
Publisher: name: figshare
Year: 2024
Subjects: subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Marine Biology
subject: Science Policy

description: Supplementary file 1: Additional file 1. PRISMA 2020 for Abstracts Checklist. Additional file 2. PRISMA checklist. Additional file 3. Search equations.
On the kinematics of the centre of charge of a spinning particle
Creators: name: Rivas, Martin
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Physics (physics.gen-ph)
subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: In particle physics, most of the classical models consider that the centre of mass and centre of charge of an elementary particle, are the same point. This presumes some particular relationship between the charge and mass distribution, a feature which cannot be checked experimentally. In this paper we give three different kinds of arguments suggesting that, if assumed different points, the centre of charge of an elementary spinning particle moves in a helical motion at the speed of light, and it thus satisfies, in general, a fourth order differential equation. If assumed a kind of rigid body structure, it is sufficient the description of the centre of charge to describe also the evolution of the centre of mass and the rotation of the body. This assumption of a separation betwen the centre of mass and centre of charge gives a contribution to the spin of the system and also justifies the existence of a magnetic moment produced by the relative motion of the centre of charge. This corresponds to an improved model of a charged elementary particle, than the point particle case. This means that a Lagrangian formalism for describing elementary spinning particles has to depend, at least, up to the acceleration of the position of the charge, to properly obtain fourth order dynamical equations. This result is compared with the description of a classical Dirac particle obtained from a general Lagrangian formalism for describing spinning particles.
description: 12 pages, 4 figures
Quasi-elastic neutrino charged-current scattering cross sections on oxygen
Creators: name: Butkevich, A. V.
name: Kulagin, S. A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The charged-current quasi-elastic scattering of muon neutrinos on oxygen target is computed for neutrino energies between 200 MeV and 2.5 GeV using the relativistic distorted-wave impulse approximation with relativistic optical potential, which was earlier successfully applied to describe electron-nucleus data. We study both neutrino and electron processes and show that the reduced exclusive cross sections for neutrino and electron scattering are similar. The comparison with the relativistic Fermi gas model (RFGM), which is widely used in data analyses of neutrino experiments, shows that the RFGM fails completely when applied to exclusive cross section data and leads to overestimated values of inclusive and total cross sections. We also found significant nuclear-model dependence of exclusive, inclusive and total cross sections for about 1 GeV energy.
description: 30 pages, 11 figures; final version to appear in Phys. Rev. C
On the Stress Tensor for Asymptotically Flat Gravity
Creators: name: Mann, Robert B.
name: Marolf, Donald
name: McNees, Robert
name: Virmani, Amitabh
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The recent introduction of a boundary stress tensor for asymptotically flat spacetimes enabled a new construction of energy, momentum, and Lorentz charges. These charges are known to generate the asymptotic symmetries of the theory, but their explicit formulas are not identical to previous constructions in the literature. This paper corrects an earlier comparison with other approaches, including terms in the definition of the stress tensor charges that were previously overlooked. We show that these terms either vanish identically (for d > 4) or take a form that does not contribute to the conserved charges (for d=4). This verifies the earlier claim that boundary stress tensor methods for asymptotically flat spacetimes yield the same conserved charges as other approaches. We also derive some additional connections between the boundary stress tensor and the electric part of the Weyl tensor.
description: 31 pages, no figure
Solid behavior of anisotropic rigid frictionless bead assemblies
Creators: name: Peyneau, Pierre-Emmanuel
name: Roux, Jean-Noël
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We investigate the structure and mechanical behavior of assemblies of frictionless, nearly rigid equal-sized beads, in the quasistatic limit, by numerical simulation. Three different loading paths are explored: triaxial compression, triaxial extension and simple shear. Generalizing recent results [1], we show that the material, despite rather strong finite sample size effects, is able to sustain a finite deviator stress in the macroscopic limit, along all three paths, without dilatancy. The shape of the yield surface is adequately described by a Lade-Duncan (rather than Mohr-Coulomb) criterion. While scalar state variables keep the same values as in isotropic systems, fabric and force anisotropies are each characterized by one parameter and are in one-to-one correspondence with principal stress ratio along all three loading paths.The anisotropy of the pair correlation function extends to a distance between bead surfaces on the order of 10% of the diameter. The tensor of elastic moduli is shown to possess a nearly singular, uniaxial structure related to stress anisotropy. Possible stress-strain relations in monotonic loading paths are also discussed.
Strong-coupling properties of unbalanced Eliashberg superconductors
Creators: name: Cappelluti, E.
name: Ummarino, G. A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: In this paper we investigate the thermodynamical properties of ``unbalanced'' superconductors, namely, systems where the electron-boson coupling $λ$ is different in the self-energy and in the Cooper channels. This situation is encountered in a variety of situation, as for instance in d-wave superconductors. Quite interesting is the case where the pairing in the self-energy is smaller than the one in the gap equation. In this case we predict a finite critical value $λ_c$ where the superconducting critical temperature $T_c$ diverges but the zero temperature gap is still finite. The specific heat, magnetic critical field and the penetration depth are also evaluated.
description: 9 Revtex pages, 7 eps figures included
Multisensor based fully autonomous non-cooperative collision avoidance system for UAVs
Creators: name: Fasano, Giancarmine
Publisher: name: Università degli Studi di Napoli Federico II
Year: 2008

description: Unmanned Aerial Vehicles will have a safe access to the Civil Airspace only when they will be able to avoid collisions even with non cooperative flying obstacles. Thus, they need to replace the capability of human eye to detect potential mid-air collisions with other airframes
and the pilot experience to find an adequate avoidance trajectory.
This thesis deals with development and test of a fully autonomous system devoted to avoidance of non cooperative intruders. In particular, it focuses on sensors, and processing logics and hardware, required on the unmanned system to acquire situational awareness. The study was carried out in collaboration with the Italian Aerospace Research Center within a research project named TECVOL, funded in the frame of National Aerospace Research
Program. The performed activities covered all the steps in the development process from the analysis of requirements deriving from the application, to the real time implementation of designed logics.
Designed prototype system is based on a multi-sensor architecture with a Ka-band pulsed radar as the main sensor, and four electro-optical cameras as aiding sensors. Proper logics and algorithms for real time sensor fusion have been developed, tested in off-line simulations, and later implemented on embedded systems to enable technology flight demonstration.
Numerical results and flight data have shown the potential of the developed system. Also on the basis of the international scenario, this technology demonstration has gained a significant scientific value.
A diagrammatic approach to categorification of quantum groups II
Creators: name: Khovanov, Mikhail
name: Lauda, Aaron D.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics
subject: 81R50, 16S99

description: We categorify one-half of the quantum group associated to an arbitrary Cartan datum.
description: 18 pages, 35 eps files
An Action For Chan-Paton Factors
Creators: name: Payen, Florian
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We show that Chan-Paton factors can be derived from a classical action describing the dynamics of a new group-valued degree of freedom attached to the boundary of an open bosonic string. We discuss the free and the interacting string in the oriented and unoriented cases, as well as the coupling of the string to an external Yang-Mills gauge field, and recover by this approach well-known results.
description: 1+9 pages, no figures
Speeding up the spread of quantum information in chaotic systems
Creators: name: Eccles, Stefan
name: Fischler, Willy
name: Guglielmo, Tyler
name: Pedraza, Juan F.
name: Racz, Sarah
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We explore the effect of introducing mild nonlocality into otherwise local, chaotic quantum systems, on the rate of information spreading and associated rates of entanglement generation and operator growth. We consider various forms of nonlocality, both in 1-dimensional spin chain models and in holographic gauge theories, comparing the phenomenology of each. Generically, increasing the level of nonlocality increases the rate of information spreading, but in lattice models we find instances where these rates are slightly suppressed.
description: 36 pages, 12 figures. V2 includes added citations, credit attributions, and corrected typos
On Guaranteed Optimal Robust Explanations for NLP Models
Creators: name: La Malfa, Emanuele
name: Zbrzezny, Agnieszka
name: Michelmore, Rhiannon
name: Paoletti, Nicola
name: Kwiatkowska, Marta
Publisher: name: arXiv
Year: 2021
Subjects: subject: Artificial Intelligence (cs.AI)
subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: We build on abduction-based explanations for ma-chine learning and develop a method for computing local explanations for neural network models in natural language processing (NLP). Our explanations comprise a subset of the words of the in-put text that satisfies two key features: optimality w.r.t. a user-defined cost function, such as the length of explanation, and robustness, in that they ensure prediction invariance for any bounded perturbation in the embedding space of the left out words. We present two solution algorithms, respectively based on implicit hitting sets and maximum universal subsets, introducing a number of algorithmic improvements to speed up convergence of hard instances. We show how our method can be con-figured with different perturbation sets in the em-bedded space and used to detect bias in predictions by enforcing include/exclude constraints on biased terms, as well as to enhance existing heuristic-based NLP explanation frameworks such as Anchors. We evaluate our framework on three widely used sentiment analysis tasks and texts of up to100words from SST, Twitter and IMDB datasets,demonstrating the effectiveness of the derived explanations.
description: 13 pages (8+5 Appendix). Accepted as long-paper at IJCAI 2021
Conductance of p-n-p graphene structures with 'air-bridge' top gates
Creators: name: Gorbachev, R. V.
name: Mayorov, A. S.
name: Savchenko, A. K.
name: Horsell, D. W.
name: Guinea, F.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We have fabricated graphene devices with a top gate separated from the graphene layer by an air gap--a design which does not decrease the mobility of charge carriers under the gate. This gate is used to realise p-n-p structures where the conducting properties of chiral carriers are studied. The band profile of the structures is calculated taking into account the specifics of the graphene density of states and is used to find the resistance of the p-n junctions expected for chiral carriers. We show that ballistic p-n junctions have larger resistance than diffusive ones. This is caused by suppressed transmission of chiral carriers at angles away from the normal to the junction.
description: to be published in Nano Letters
Hadronic light-by-light contribution to the muon $g-2$ from holographic QCD with massive pions
Creators: name: Leutgeb, Josef
name: Rebhan, Anton
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We extend our previous calculations of the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment in holographic QCD to models with finite quark masses and a tower of massive pions. Analysing the role of the latter in the Wess-Zumino-Witten action, we show that the Melnikov-Vainshtein short-distance constraint is satisfied solely by the summation of contributions from the infinite tower of axial vector meson contributions. There is also an enhancement of the asymptotic behavior of pseudoscalar contributions when their infinite tower of excitations is summed, but this leads only to subleading contributions for the short-distance constraints on light-by-light scattering. We also refine our numerical evaluations, particularly in the pion and $a_1$ sector, which corroborates our previous findings of contributions from axial vector mesons that are significantly larger than those adopted for the effects of axials and short-distance constraints in the recent White Paper on the Standard Model prediction for $(g-2)_μ$.
description: 28 pages, 10 figures, 4 tables; v2: table IV expanded, reference added
Separation and recognition of connected handprinted capital English characters
Creators: name: Ting, Voon-Cheung Roger
Publisher: name: University of British Columbia
Year: 2010

description: The subject of machine recognition of connected characters is investigated. A generic single character recognizer (SCR) assumes there is only one character in the image. The goal of this project is to design a connected character segmentation algorithm (CCSA) without the above assumption. The newly designed CCSA will make use of a readily available SCR. The input image (e.g. a word with touching letters) is first transformed (thinned) into its skeletal form. The CCSA will then extract the image features (nodes and branches) and store them in a hierarchical form. The hierarchy stems from the left-to-right rule of writing of the English language. The CCSA will first attempt to recognize the first letter. When this is done, the first letter is deleted and the algorithm repeats. After extracting the image features, the CCSA starts to create a set of test images from the beginning of the word (i.e. beginning of the description). Each test image contains one more feature than its predecessor. The number of test images in the set is constrained by a predetermined fixed width or a fixed total number of features. The SCR is then called to examine each test image. The recognizable test image(s) in the set are extracted. Let each recognizable test image be denoted by C₁. For each C₁, a string of letters C₂, C₃, CL is formed. C₂ is the best recognized test image in a set of test images created after the deletion of C₁ from the beginning of the current word. C₃ through CL are created by the same method. All such strings are examined to determine which string contains the best recognized C₁. Experimental results on test images with two characters yield a recognition rate of 72.66%. Examples with more than two characters are also shown. Furthermore, the experimental results suggested that topologically simple test images can be more difficult to recognize than those which are topologically more complex.
The Dark Energy Survey Data Management System
Creators: name: Mohr, Joseph J.
name: Barkhouse, Wayne
name: Beldica, Cristina
name: Bertin, Emmanuel
name: Cai, Y. Dora
name: da Costa, Luiz
name: Darnell, J. Anthony
name: Daues, Gregory E.
name: Jarvis, Michael
name: Gower, Michelle
name: Lin, Huan
name: Martelli, leandro
name: Neilsen, Eric
name: Ngeow, Chow-Choong
name: Ogando, Ricardo
name: Parga, Alex
name: Sheldon, Erin
name: Tucker, Douglas
name: Kuropatkin, Nikolay
name: Stoughton, Chris
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: The Dark Energy Survey collaboration will study cosmic acceleration with a 5000 deg2 griZY survey in the southern sky over 525 nights from 2011-2016. The DES data management (DESDM) system will be used to process and archive these data and the resulting science ready data products. The DESDM system consists of an integrated archive, a processing framework, an ensemble of astronomy codes and a data access framework. We are developing the DESDM system for operation in the high performance computing (HPC) environments at NCSA and Fermilab. Operating the DESDM system in an HPC environment offers both speed and flexibility. We will employ it for our regular nightly processing needs, and for more compute-intensive tasks such as large scale image coaddition campaigns, extraction of weak lensing shear from the full survey dataset, and massive seasonal reprocessing of the DES data. Data products will be available to the Collaboration and later to the public through a virtual-observatory compatible web portal. Our approach leverages investments in publicly available HPC systems, greatly reducing hardware and maintenance costs to the project, which must deploy and maintain only the storage, database platforms and orchestration and web portal nodes that are specific to DESDM. In Fall 2007, we tested the current DESDM system on both simulated and real survey data. We used Teragrid to process 10 simulated DES nights (3TB of raw data), ingesting and calibrating approximately 250 million objects into the DES Archive database. We also used DESDM to process and calibrate over 50 nights of survey data acquired with the Mosaic2 camera. Comparison to truth tables in the case of the simulated data and internal crosschecks in the case of the real data indicate that astrometric and photometric data quality is excellent.
description: To be published in the proceedings of the SPIE conference on Astronomical Instrumentation (held in Marseille in June 2008). This preprint is made available with the permission of SPIE. Further information together with preprint containing full quality images is available at http://desweb.cosmology.uiuc.edu/wiki
New oxidative enzimes for industrial application
Creators: name: Miele, Annalisa
Publisher: name: Università degli Studi di Napoli Federico II
Year: 2009

description: Fungal laccases are remarkable green catalysts that have a broad substrate specificity and many potential applications in bioremediation, lignocellulose processing, organic synthesis, and more. The white-rot fungus Pleurotus ostreatus is able to express multiple laccase genes encoding isoenzymes with different and particularly interesting physico-chemical characteristics: POXC, POXA1w, POXA1b, POXA3a and POXA3b. Several P. ostreatus laccases have been successfully expressed in yeasts and the availability of established heterologous recombinant
expression systems has allowed the construction of mutated, “better performing” enzymes through molecular evolution techniques. The cDNAs encoding POXA1b and POXC have been selected as “parent molecules” to guide the evolution of
laccases with higher specific activity and different substrate specificities. Genetic variants were created by random mutagenesis through error prone PCR (EP-PCR) and DNA shuffling. After two round of mutations, four POXA1b mutants (1M9B,1L2B, 1M10B and 3M7C) were selected for their improved activity against nonphenolic substrates.
New criteria of selection were applied in a further screening of the already avalaible 2300 mutants library, using different substrates (e.g. 2,6 dimethoxyphenol,
DMP), assaying the enzyme stability and activity at different operating conditions (different pHs). Three new mutants were selected for their improved performances
and characterized from a structural and functional point of view. They showed stability at pH 5 and at 60°C higher than that of the wild-type enzyme.
A new mutant was rationally designed and constructed. This new mutant, R4, contains the mutations of the two parental enzymes 1M10B and 3M7C. Catalytic and kinetic properties of R4 mutants were analyzed and compared with those of the wildtype enzyme. It showed stability at pH10 2 fold higher than that of the wild-type enzyme. This new clone was used as template for producing a new collection of 1100 mutants. Two new mutants (4M10G and 1H6C) were selected for their
improved activity against ABTS. The isolated mutants were partially purified and fully characterized.
Amino acid substitutions of each mutant were identified and located in POXA1b laccase model. Analysis of possible molecular mechanisms responsible of better performances was carried out.
A parallel session of the project was aimed at overproducing POXA1b laccase and its best variant 1H6C using the filamentous fungi Aspergillus niger as host. The
necessity to produce large amounts of enzymes for biotechnological applications and the low yields of laccases secreted from wild-type fungal organisms claims for an efficient heterologous expression of the enzymes of interest. The two laccases have been expressed in the filamentous fungi A. niger, obtaining an improvement of 100-
fold in the enzyme production. These preliminary results indicate that A. niger could be a promising expression system for P. ostreatus laccases if compared to other
expression systems.
Multidimensional Padé approximation of binomial functions: Equalities
Creators: name: Bennett, Michael A.
name: Martin, Greg
name: O'Bryant, Kevin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Number Theory (math.NT)
subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 41A21, 11J72

description: Let $ω_0,\dots,ω_M$ be complex numbers. If $H_0,\dots,H_M$ are polynomials of degree at most $ρ_0,\dots,ρ_M$, and $G(z)=\sum_{m=0} ^M H_m(z) (1-z)^{ω_m}$ has a zero at $z=0$ of maximal order (for the given $ω_m,ρ_m$), we say that $H_0,\dots,H_M$ are a \emph{multidimensional Padé approximation of binomial functions}, and call $G$ the Padé remainder. We collect here with proof all of the known expressions for $G$ and $H_m$, including a new one: the Taylor series of $G$. We also give a new criterion for systems of Padé approximations of binomial functions to be perfect (a specific sort of independence used in applications).
description: 30 pages, ancillary Mathematica notebook
Extracting and summarizing information from large data repositories
Creators: name: Albanese, Massimiliano
Publisher: name: Università degli Studi di Napoli Federico II
Year: 2006

description: Information retrieval from large data repositories has become an important area of computer science. Research in this field is highly encouraged by the ever-increasing rate with which today's society is able to produce digital data. Unfortunately most of such data (e.g. video recordings, plain text documents) are unstructured. Two major issues thus arise in this scenario: i) extracting structured data -- information -- from unstructured data; ii) summarizing information, i.e. reducing large volumes of information to a short summary or abstract comprising only themost essential facts.
In this thesis, techniques for extracting and summarizing information from large data repositories are presented. In particular the attention is focused onto two kinds of repositories: video data collections and natural language text document repositories. We show how the same principles can be applied for summarizing information in both domains and present solutions tailored to each domain. The thesis presents a novel video summarization algorithm, the Priority Curve Algorithm, that outperforms previous solutions, and three heuristic algorithms, OptStory+, GenStory and DynStory, for creating succinct stories about entities of interest using the information collected by  algorithms that extract structured data from heterogenous data sources. In particular a Text Attribute Extraction (TAE) algorithm for extracting information from natural language text is presented. Experimental results show that our approach to summarization is promising.
Improved Photometric Calibrations for Red Stars Observed with the SDSS Photometric Telescope
Creators: name: Davenport, James R. A.
name: Bochanski, John J.
name: Covey, Kevin R.
name: Hawley, Suzanne L.
name: West, Andrew A.
name: Schneider, Donald P.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5-m Photometric Telescope (PT) and the SDSS 2.5-m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5-m photometry. Systematic differences between the PT and native SDSS 2.5-m {\it ugriz} photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching $\sim 43,000$ stars observed with both the PT and SDSS 2.5-m, we extend the present relations to include low-mass stars with colors $0.6 \le r-i \le 1.7$. These corrections will allow us to place photometry of bright, low-mass trigonometric parallax stars previously observed with the PT on the 2.5-m system. We present new transformation equations and discuss applications of these data to future low-mass star studies using the SDSS.
description: 8 Pages, 5 Figures. Accepted to AJ
Improved noninvasive determination of blood pressure by oscillometry in the presence of motion artifacts
Creators: name: Bussani, Carlo Robert
Publisher: name: University of British Columbia
Year: 2010

description: Blood pressure measurements provide information regarding the status of the cardiovascular system to aid in diagnosing pathological conditions, maintaining patient stability during surgery, and adapting tourniquet pressures. However, the performance of commercially available techniques of measuring blood pressure is often degraded during clinical measurements in the presence of motion artifacts. A prototype system based on oscillometry that uses algorithms which take advantage of a multi-bladder cuff has the potential to improve measurements of blood pressure in noisy environments by detecting noise and rapidly estimating blood pressure using only data uncorrupted by noise. This system and strategy, implemented in one version to track limb occlusion pressure (the minimum cuff pressure required to occlude underlying arteries), was evaluated along with a typical commercial, JLV available oscillometric blood pressure monitor to compare their ability to track limb occlusion pressure in the presence of varying noise conditions encountered during lab trials and clinical trials. Results showed that the prototype consistently estimated limb occlusion pressure more rapidly, more accurately, and more reliably than the oscillometric monitor in noise conditions typical of surgical procedures. The results also indicate that the prototype is feasible for incorporation into an adaptive tourniquet.
Interactions between a massless tensor field with the mixed symmetry of the Riemann tensor and a massless vector field
Creators: name: Bizdadea, C.
name: Ciobirca, C. C.
name: Cioroianu, E. M.
name: Saliu, S. O.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Consistent couplings between a massless tensor field with the mixed symmetry of the Riemann tensor and a massless vector field are analyzed in the framework of Lagrangian BRST cohomology. Under the assumptions on smoothness, locality, Lorentz covariance, and Poincare invariance of the deformations, combined with the requirement that the interacting Lagrangian is at most second-order derivative, it is proved that there are no consistent cross-interactions between a single massless tensor field with the mixed symmetry of the Riemann tensor and one massless vector field.
description: LaTeX, 24 pages
BTZ Black Hole Entropy: A spin foam model description
Creators: name: Garcia-Islas, J. Manuel
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We present a microscopical explanation of the entropy of the BTZ black hole using discrete spin foam models of quantum gravity. The entropy of a black hole is given in geometrical terms which lead us to think that its statistical description must be given in terms of a quantum geometry. In this paper we present it in terms of spin foam geometrical observables at the horizon of the black hole.
description: 10 pages, 2 figures, Final Version
Field- and current-driven magnetic domain-wall inverter and diode
Creators: name: Luo, Zhaochu
name: Schären, Stefan
name: Hrabec, Aleš
name: Dao, Trong Phuong
name: Sala, Giacomo
name: Finizio, Simone
name: Feng, Junxiao
name: Mayr, Sina
name: Raabe, Jörg
name: Gambardella, Pietro
name: Heyderman, Laura J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We investigate the inversion process of magnetic domain walls (DWs) propagating through synthetic noncollinear magnetic textures, whereby an up/down DW can be transformed into a down/up DW and vice versa. We exploit the lateral coupling between out-of-plane and in-plane magnetic regions induced by the interfacial Dzyaloshinskii-Moriya interaction in Pt/Co/AlOx trilayers to realize both field-driven and current-driven magnetic DW inverters. The inverters consist of narrow in-plane magnetic regions embedded in out-of-plane DW racetracks. Magnetic imaging and micromagnetic simulations provide insight into the DW inversion mechanism, showing that DW inversion proceeds by annihilation of the incoming domain on one side of the in-plane region and nucleation of a reverse domain on the opposite side. By changing the shape of the in-plane magnetic region, we show that the DW inversion efficiency can be tuned by adjusting the ratio between the chiral coupling energy at the inverter boundary and the energy cost of nucleating a reverse domain. Finally, we realize an asymmetric DW inverter that has nonreciprocal inversion properties and demonstrate that such a device can operate as a DW diode. Our results provide input for the versatile manipulation of DWs in magnetic racetracks and the design of efficient DW devices for nonvolatile magnetic logic schemes.