cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Trust-based Data Management in Mobile Ad Hoc Networks
Creators: name: Gupta, Sheetal
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Computer Science (0984)

description: The problem of data management has been studied widely in the field of mobile ad hoc networks and pervasive computing. An issue is that finding the required data depends on chance encounter with the source of data. Most existing research take the semantics of data into account while caching data onto mobile devices from the wired sources. In this work, we propose that the mobile devices decide what to cache based on the queries they encounter. The scheme involves a distributed technique for estimating the global query distribution in the network. The devices proactively increase the availability of popular data in the network. They use their estimate of query frequencies to push popular data and to guide their caching decisions. We also address the issue of data tampering in MANETs. The answers obtained from peer devices may not be reliable. This propagation of incorrect data may be either intentional or out of ignorance. We propose a Bayesian approach to infer the correct answer. The suggested answers and the reputation values of the sources themselves are used to determine the most likely answer. We implement these techniques in the network simulator, Glomosim and show that our scheme improves data availability, response latency and data accuracy.
Selective separation of C8 aromatics by an interpenetrating metal−organic framework material
Creators: name: Sun, Na
name: Zhou, Xue
name: Yu, Han
name: Si, Xiuwen
name: Ding, Fu
name: Sun, Yaguang
name: Zaworotko, Michael
Publisher: name: University of Limerick
Year: 2024
Subjects: classificationCode: 34
subject: Chemical sciences
subject: FOS: Chemical sciences

description: O-xylene (OX) is an important chemical raw material, but it is often produced in mixtures with other C8 aromatics. Similar physicochemical properties of the C8 isomers make their separation and purification very difficult and energy intensive. There is an unmet need for an adsorbent that would be effective for the separation of OX from the other C8 isomers. This work reports a three-dimensional interpenetrated metal−organic framework, SYUCT-110, that interacts with each of the single-component C8 isomers to form. The selectivity of C8 aromatic hydrocarbons was determined through liquid-phase batch uptake experiments. The results revealed that the selectivity order was OX > PX > MX > ethylbenzene (EB). The selectivity values were found to be 2.63, 1.58, 5.51, 3.71, 1.86, and 3.02 for OX/MX, OX/PX, OX/EB, PX/MX, MX/EB, and PX/EB, respectively. The adsorption capacity of OX was 71 mg/g. Grand Canonical Monte Carlo simulations were used to study the C8 adsorption sites, revealing that π···π interactions are the main reason for the observed adsorption selectivity. The adsorption energy calculation results also verified the selectivity of SYUCT-110 for the synthesis of OX.
The Cut-Constructible Part of QCD Amplitudes
Creators: name: Britto, Ruth
name: Feng, Bo
name: Mastrolia, Pierpaolo
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Unitarity cuts are widely used in analytic computation of loop amplitudes in gauge theories such as QCD. We expand upon the technique introduced in hep-ph/0503132 to carry out any finite unitarity cut integral. This technique naturally separates the contributions of bubble, triangle and box integrals in one-loop amplitudes and is not constrained to any particular helicity configurations. Loop momentum integration is reduced to a sequence of algebraic operations. We discuss the extraction of the residues at higher-order poles. Additionally, we offer concise algebraic formulas for expressing coefficients of three-mass triangle integrals. As an application, we compute all remaining coefficients of bubble and triangle integrals for nonsupersymmetric six-gluon amplitudes.
description: 78 pages, 3 figs
Transfer in the Context of Reinforcement Learning Mapping Q-tables
Creators: name: Ray, Soumi
Publisher: name: Maryland Shared Open Access Repository
Year: 2007
Subjects: Computer Science (0984)

description: Transfer in machine learning is the process of using knowledge learned in a source domain to speedup learning in one or more related target domains. In human learning, transfer is a ubiquitous phenomenon. In machine learning, transfer is far less common. In this thesis we present a transfer method for reinforcement learning when the learner does not have access to a model of either the source or the target domains (i.e., the transition and reward probabilities are unknown) and there is no prior knowledge about how to map states or actions in the source domain to corresponding or similar states or actions in the target domain. Empirical results in a variety of grid worlds and a multi-agent block loading domain that is exceptionally difficult to solve using standard reinforcement learning algorithms show significant speedups in learning in the target domain.
Bubble nucleation as seen by different observers
Creators: name: Chen, Yilin
name: Vilenkin, Alexander
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Pair production in a constant electric field is closely analogous to bubble nucleation in a false vacuum. The classical trajectories of the pairs are Lorentz invariant, but this invariance should be broken by the nucleation process. Garriga et al. used a model detector, consisting of other particles interacting with the pairs, to investigate how pair production is seen by different Lorentzian observers. They found that particles (antiparticles) of the pair are predominantly observed moving in the direction of (opposite to) the electric field and concluded that observers see pairs nucleating preferentially in the detector's rest frame. Here, we apply this approach to the case where two detectors moving relative to one another are used to observe the particle and antiparticle of the same pair. We find that each detector will still observe nucleation to occur in its rest frame, regardless of the motion of the other detector. However, if the relative velocity of the two detectors is sufficiently high, the particle and antiparticle of the pair can be observed moving towards one another with arbitrarily large momenta, contrary to the usual expectation.
description: Extended discussion of the results
Vortex unpinning due to crustquake initiated neutron excitation and pulsar glitches
Creators: name: Layek, Biswanath
name: Yadav, Pradeepkumar
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Pulsars undergoing crustquake release strain energy, which can be absorbed in a small region inside the inner crust of the star and excite the free superfluid neutrons therein. The scattering of these neutrons with the surrounding pinned vortices may unpin a large number of vortices and effectively reduce the pinning force on vortex lines. Such unpinning by neutron scattering can produce glitches for Crab like pulsars and Vela pulsar of size in the range $\sim 10^{-8} - 10^{-7}$, and $\sim 10^{-9} - 10^{-8}$, respectively. Although we discuss here the crustquake initiated excitation, the proposal is very generic and equally applicable for any other sources, which can excite the free superfluid neutrons, or can be responsible for superfluid - normal phase transition of neutron superfluid in the inner crust of a pulsar.
description: 9 pages, 1 figure, accepted for publication in Monthly notices of Royal Astronomical Society (MNRAS)
GenKI im Lateinunterricht – Texte im Spracherwerb
Creators: name: Beyer, Andrea
Publisher: name: Zenodo
Year: 2024
Subjects: generative AI
Latin classes
language acquisition

description: Generative KI (genKI) im Lateinunterricht (LU) beschäftigt nicht nur die einzelnen Lehrenden, sondern auch die Fortbildungsplaner. In diesem Vortrag wird eine sehr knappe Einführung zum Begriff generative KI und Prompting geboten. Kern der Fortbildung sind Anwendungsszenarien von genKI bei der Textarbeit im Lateinunterricht. Von besonderem Interesse sind die lateinischen, didaktisierten Texte im Rahmen des Spracherwerbs.
Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud
Creators: name: Heyer, Mark
name: Gong, Hao
name: Ostriker, Eve
name: Brunt, Christopher
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Velocity anisotropy induced by MHD turbulence is investigated using computational simulations and molecular line observations of the Taurus molecular cloud. A new analysis method is presented to evaluate the degree and angle of velocity anisotropy using spectroscopic imaging data of interstellar clouds. The efficacy of this method is demonstrated on model observations derived from three dimensional velocity and density fields from the set of numerical MHD simulations that span a range of magnetic field strengths. The analysis is applied to 12CO J=1-0 imaging of a sub-field within the Taurus molecular cloud. Velocity anisotropy is identified that is aligned within 10 degrees of the mean local magnetic field direction derived from optical polarization measurements. Estimated values of the field strength based on velocity anisotropy are consistent with results from other methods. When combined with new column density measurements for Taurus, our magnetic field strength estimate indicates that the envelope of the cloud is magnetically subcritical. These observations favor strong MHD turbulence within the low density, sub-critical, molecular gas substrate of the Taurus cloud.
description: Accepted for publication in ApJ,
Towards Relational Theory Formation from Undifferentiated Sensor Data
Creators: name: Pickett, Marc Joseph
Publisher: name: Maryland Shared Open Access Repository
Year: 2011
Subjects: Artificial Intelligence
Concept Formation
Developmental Robotics
Machine Learning
Neural Modeling
Unsupervised Learning

description: Human adults have rich theories in their heads of how the world works.  These theories include objects and relations for both concrete and abstract concepts.  Everything we know either must be innate or learned through experience.  Yet it's unclear how much of this model needs to be innate for a computer.  The core question this dissertation addresses is how a computer can develop rich relational theories using only its raw sensor data.  We address this by outlining a bridge between raw sensors and a rich relational theory.  We have implemented parts of this bridge, with other parts as feasibility studies, while others remain conceptual. At the core of this bridge is Ontol, a system that constructs a conceptual structure or ontology from feature-set data.  Ontol is inspired by cortical models that have been shown to be able to express invariant concepts, such as images independent of any translation or rotation.  As a demonstration of the utility of the ontologies created by Ontol, we present a novel semi-supervised learning algorithm that learns from only a handful of positive examples.  Like humans, this algorithm doesn't require negative examples.  Instead, this algorithm uses the ontologies created by Ontol from unlabeled data, and searches for a Bayes-optimal theory given this background knowledge. The rest of the dissertation shows in principle how Ontol can be used as the workhorse for a system that finds analogies, discovers useful mappings, and might ultimately create theories, such as a gisty theory of number.
Towards Implementation of a Pattern Recognition System based on a Working Theory of the Learning Rule for Dendritic Integration
Creators: name: Patel, Shamit Atul
Publisher: name: Maryland Shared Open Access Repository
Year: 2012
Subjects: computational neuroscience
dendritic integration
Hierarchical Temporal Memory
machine learning
neural networks
pattern recognition

description: My goal is to develop a working theory of the learning rule for dendritic integration by performing appropriate neurophysiological experimentation, and to then implement a pattern recognition system based on that learning algorithm so that the algorithm can be evaluated for its generalization ability. This thesis is a first step toward reaching that goal in that it presents an implementation of Jeff Hawkins and Dileep George's Hierarchical Temporal Memory (HTM) pattern recognition system based on an existing theory of the learning rule for dendritic integration - spike-timing-dependent synaptic plasticity (STDP). I define probabilistic classification as the task of assigning a testing pattern a group of labels, where the pattern is classified correctly if its label is in that group, and classified incorrectly otherwise. I found that for visual pattern recognition, the STDP HTM system achieved much better overall probabilistic classification ability and far better generalization ability than the baseline HTM system.
New final doublets and power densities for the ILC small crossing angle layout
Creators: name: Appleby, R.
name: Bambade, P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Accelerator Physics (physics.acc-ph)
subject: FOS: Physical sciences

description: In this paper we use current and proposed final doublet magnet technologies to reoptimise the interaction region of the International Linear Collider and reduce the power losses. The result is a set of three new final doublet layouts with improved beam transport properties. The effect of localised power deposition is considered, and its reduction using Tungsten liners.
description: Talk given by R. Appleby at the the Linear Collider Workshop ``LCWS06'', 9-13 March 2006, I.I.Sc Bangalore, India
Ultraviolet Spectroscopy of HD 44179
Creators: name: Sitko, Michael L.
name: Bernstein, Lawrence S.
name: Glinski, Robert J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have re-analyzed the ultraviolet spectrum of HD 44179, the central star(s) of the Red Rectangle nebula, providing improved estimates of the column density, rotational, and vibrational temperatures of the 4th Positive A-X system of CO in absorption. The flux shortward of 2200 A is a complex blend of CO features with no discernible stellar photosphere, making the identification of other molecular species difficult, and the direct derivation of the dust extinction curve impossible. We confirm that the spin-forbidden CO (a-X) Cameron bands are likely produced by either collisional excitation or a chemical reaction, not photoexcitation, but with a higher internal vibrational excitation than previously determined. We also detect the spin-forbidden CO a'-X, d-X, and e-X absorption features. The hot CO (A-X) bands exhibit a blue-shift of ~300 km/s, likely occurring close to the white dwarf star(s) suspected as the original source of the ultraviolet flux in the system, and forming the base of the outflow of material in the Red Rectangle. The OH "comet-band" system near 3000 A is also analyzed, and estimates of its rovibrational temperatures determined. The source of the molecules studied in this system is still unknown, but may be a combination of gaseous material associated with the star(s), or processed material from the surrounding dust torus.
description: 40 pages, 14 figures
[Rb/Zr] ratio in Ba stars as diagnostics of the companion AGB stellar mass
Creators: name: Shejeelammal, J.
name: Goswami, Aruna
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Understanding the nucleosynthesis and evolution of Asymptotic Giant Branch (AGB) stars is of primary importance as they are the main producers of some of the key elements in the Universe. They are the predominant sites for the slow neutron-capture nucleosynthesis. The exact physical conditions and nucleosynthetic processes occuring at the interior of AGB stars are not clearly understood, that hinders a better understanding of the contribution of these stars to the Galactic chemical enrichment. The extrinsic stars, which are known to have received products of AGB phase of evolution via binary mass transfer mechanisms, form vital tools to trace the AGB nucleosynthesis. The [Rb/Zr] ratio is an important diagnostic to understand the average neutron density at the s-process site and provide important clues to the mass of the companion AGB stars. In this work we have presented the estimate of [Rb/Zr] ratios, based on the high resolution spectroscopic analysis for a sample of Ba stars, and discussed how it can be used to understand the characteristics of the AGB star. Results from an analysis based on parametric model to confirm the mass of the companion AGB star are also presented.
description: arXiv admin note: substantial text overlap with arXiv:2010.06949
Solar and stellar system tests of the cosmological constant
Creators: name: Sereno, M.
name: Jetzer, Ph.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Some tests of gravity theories - periastron shift, geodetic precession, change in mean motion and gravitational redshift - are applied in solar and stellar systems to constrain the cosmological constant. We thus consider a length scale range from 10^8 to 10^{15} km. Best bounds from the solar system come from perihelion advance and change in mean motion of Earth and Mars, Lambda < 10^{-36} km^{-2}. Such a limit falls very short to estimates from observational cosmology analyses but a future experiment performing radio ranging observations of outer planets could improve it by four orders of magnitude. Beyond the solar system, together with future measurements of periastron advance in wide binary pulsars, gravitational redshift of white dwarfs can provide bounds competitive with Mars data.
description: 4 pages; this is a preprint of an article accepted for publication in Physical Review D
A Polarimetric Study of the B[e] star HD 45677
Creators: name: Patel, M.
name: Oudmaijer, R. D.
name: Vink, J.
name: Mottram, J. C.
name: Davies, B.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present new medium-resolution spectropolarimetric observations of HD 45677 in the B and R-bands. A change in polarisation is detected across Halpha, Hbeta and Hgamma confirming that the ionised region around the star is aspherical. (Q,U) points associated with these emission lines occur away from the continuum, defining a polarisation vector which points in the same direction for each of the lines at an average intrinsic polarisation angle of 164 +/- 3 degrees. These data were combined with past photometric and polarimetric data from the literature to investigate any variability. We find that HD 45677 is both photometrically and polarimetrically variable and that these changes are linked. We suggest that these variations may be caused by an aspherical blowout and by deriving a least-squares fit to the B-band polarimetric data in Q-U space, we show that the blowout occurs at an intrinsic polarisation angle of 175 +/- 1 degrees, along the same angle as the proposed geometry of the ionised region.
description: 7 pages, 4 figures, accepted MNRAS
Deconfined criticality, runaway flow in the two-component scalar electrodynamics and weak first-order superfluid-solid transitions
Creators: name: Kuklov, Anatoly
name: Prokof'ev, Nikolay
name: Svistunov, Boris
name: Troyer, Matthias
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We perform a comparative Monte Carlo study of the easy-plane deconfined critical point (DCP) action and its short-range counterpart to reveal close similarities between the two models for intermediate and strong coupling regimes. For weak coupling, the structure of the phase diagram depends on the interaction range: while the short-range model features a tricritical point and a continuous U(1)xU(1) transition,the long-range DCP action is characterized by the runaway renormalization flow of coupling into a first (I) order phase transition. We develop a "numerical flowgram" method for high precision studies of the runaway effect, weakly I-order transitions, and polycritical points. We prove that the easy-plane DCP action is the field theory of a weakly I-order phase transition between the valence bond solid and the easy-plane antiferromagnet (or superfluid, in particle language) for any value of the weak coupling strength. Our analysis also solves the long standing problem of what is the ultimate fate of the runaway flow to strong coupling in the theory of scalar electrodynamics in three dimensions with U(1)xU(1) symmetry of quartic interactions
description: 25 pages, 18 figures, Mottness and quantum criticality conference (to appear in Annals of physics)
Multipole expansions and Fock symmetry of the Hydrogen atom
Creators: name: Meremianin, A. V.
name: Rost, J-M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: The main difficulty in utilizing the O(4) symmetry of the Hydrogen atom in practical calculations is the dependence of the Fock stereographic projection on energy. This is due to the fact that the wave functions of the states with different energies are proportional to the hyperspherical harmonics (HSH) corresponding to different points on the hypersphere. Thus, the calculation of the matrix elements reduces to the problem of re-expanding HSH in terms of HSH depending on different points on the hypersphere. We solve this problem by applying the technique of multipole expansions for four-dimensional HSH. As a result, we obtain the multipole expansions whose coefficients are the matrix elements of the boost operator taken between hydrogen wave functions (i.e. hydrogen form-factors). The explicit expressions for those coefficients are derived. It is shown that the hydrogen matrix elements can be presented as derivatives of an elementary function. Such an operator representation is convenient for the derivation of recurrency relations connecting matrix elements between states corresponding to different values of the quantum numbers $n$ and $l$.
description: 26 pages, 2 figures
Nanoscale heat transfer at contact between a hot tip and a substrate
Creators: name: Lefèvre, Stéphane
name: Volz, Sebastian
name: Chapuis, Pierre-Olivier
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Hot tips are used either for characterizing nanostructures by using scanning thermal microscopes or for local heating to assist data writing. The tip-sample thermal interaction involves conduction at solid-solid contact as well as conduction through the ambient gas and through the water meniscus. We analyze those three heat transfer modes with experimental data and modeling. We conclude that the three modes contribute in a similar manner to the thermal contact conductance but they have distinct contact radii ranging from 30 nm to 1 micron. We also show that any scanning thermal microscope has a 1-3 microns resolution when used in ambient air.
Entropy, Thermostats and Chaotic Hypothesis
Creators: name: Gallavotti, Giovanni
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The chaotic hypothesis is proposed as a basis for a general theory of nonequilibrium stationary states. Version 2: new comments added after presenting this talk at the Meeting mentioned in the Acknowledgement. One typo corrected.
description: 6 pages
Spin-wave focusing induced skyrmion generation
Creators: name: Wang, Zhenyu
name: Li, Z. -X.
name: Wang, Ruifang
name: Liu, Bo
name: Meng, Hao
name: Cao, Yunshan
name: Yan, Peng
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We propose a new method to generate magnetic skyrmions through spin-wave focusing in chiral ferromagnets.A lens is constructed to focus spin waves by a curved interface between two ferromagnetic thin films with different perpendicular magnetic anisotropies. Based on the principle of identical magnonic path length, we derive the lens contour that can be either elliptical or hyperbolical depending on the magnon refractive index. Micromagnetic simulations are performed to verify the theoretical design. It is found that under proper condition magnetic skyrmions emerge near the focus point of the lens where the spin-wave intensity has been significantly enhanced. A close investigation shows that a magnetic droplet first forms and then converts to the skyrmion accompanying with a change of topological charge. Phase diagram about the amplitude and duration-time of the exciting field for skyrmion generation is obtained. Our findings would be helpful for designing novel spintronic devices combining the advantages of skyrmionics and magnonics.
description: 5 pages, 4 figures
A brief guide for the gRNA_create webserver (v0.0.1)
Creators: name: Ahmed, Armaan
Publisher: name: Zenodo
Year: 2021
Subjects: gRNA webserver
gRNA_create
gRNA

description: The gRNA_create webserver* is available here: https://www.ahmedportfolio.com/projects/gRNA_create/ *pre-release version. Major features (genetic algorithm) to be added.
The Positive Mass and Isoperimetric Inequalities for Axisymmetric Black Holes in four and five dimensions
Creators: name: Gibbons, G. W.
name: Holzegel, G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this paper we revisit Brill's proof of positive mass for three-dimensional, time-symmetric, axisymmetric initial data and generalise his argument in various directions. In 3+1 dimensions, we include an apparent horizon in the initial data and prove the Riemannian Penrose inequality in a wide number of cases by an elementary argument. In the case of 4+1 dimensions we obtain the analogue of Brill's formula for initial data admitting a generalised form of axisymmetry. Including an apparent horizon in the initial data, the Riemannian Penrose inequality is again proved for a large class of cases. The results may have applications in numerical relativity.
description: 21 pages, 3 figures
Shot Noise in Magnetic Tunnel Junctions: Evidence for Sequential Tunneling
Creators: name: Guerrero, R.
name: Aliev, F. G.
name: Tserkovnyak, Y.
name: Santos, T. S.
name: Moodera, J. S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel alignment of the ferromagnetic electrodes. We propose a model of sequential tunneling through nonmagnetic and paramagnetic impurity levels inside the tunnel barrier to qualitatively explain the observations.
description: 5 pages, 5 figures
The prompt emission & peculiar break of GRB 060124
Creators: name: Curran, P. A.
name: Kann, D. A.
name: Ferrero, P.
name: Rol, E.
name: Wijers, R. A. M. J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Our multi-wavelength analysis of GRB 060124 shows the unusual behaviour of the decaying lightcurve as well as supporting the recently proposed phenomenon of long-lasting central engine activity. The prompt X-ray emission displays uncommonly well resolved flaring behaviour, with spectral evolution - indicative of central engine activity - which allows us to estimate the energy injection time for each flare. The otherwise smooth X-ray & optical afterglows demonstrate achromatic breaks at about 1 day which differ significantly from the usual jet break in the blastwave model of afterglows.
description: 2 pages, 1 figure (colour). Accepted by "Il Nuovo Cimento" (Proceedings of the Swift-Venice 2006 meeting) after minor changes
Toric surface codes and Minkowski length of polygons
Creators: name: Soprunov, Ivan
name: Soprunova, Evgenia
Publisher: name: arXiv
Year: 2008
Subjects: subject: Algebraic Geometry (math.AG)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 94B27, 14G50, 52B20

description: In this paper we prove new lower bounds for the minimum distance of a toric surface code defined by a convex lattice polygon P. The bounds involve a geometric invariant L(P), called the full Minkowski length of P which can be easily computed for any given P.
description: 18 pages, 9 figures
Tiny Encryption Algorithm for Cryptographic Gradient Noise
Creators: name: Zafar, Fahad
Publisher: name: Maryland Shared Open Access Repository
Year: 2010
Subjects: Computer Graphics
GPU
Gradient Noise
Noise
Random Numbers
Tiny Encryption Algorithm

description: Random numbers have many uses in computer graphics, from Monte Carlo sampling for realistic image synthesis to noise generation for artistic shader construction. The random number generators used in GPUs (Graphics Processing Units) today mostly produce poor quality random numbers and run slowly due to their sequential nature, hence they find only limited use for numerical simulations and synthetic noise generation. The ones that do produce acceptable results do so at high execution cost. This thesis explores use of some cryptographic algorithms as hash functions that produce random numbers with minimum correlation, map well to the GPU architectures and are easy to implement. We compare results for a variety of hash functions based on speed and quality. We also show how these hash functions can be used with the band-limited gradient noise rendering primitive. This noise is entirely computational and does not require any texture lookups. Our hash function allows a speed/quality trade off, and we show that faster versions can be used for noise generation, resulting in a noise that is efficient, does not suffer from discernible periodicity and produces better results, while slower versions can be used for numeric simulation, providing random numbers that pass the NIST and DIEHARD randomness test suites.
A survey for nanodiamond features in the 3 micron spectra of Herbig Ae/Be stars
Creators: name: Acke, B.
name: Ancker, M. E. van den
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have carried out a survey of 60 Herbig Ae/Be stars in the 3 micron wavelength region in search for the rare spectral features at 3.43 and 3.53 micron. These features have been attributed to the presence of large, hot, hydrogen-terminated nanodiamonds. Only two Herbig Ae/Be stars, HD 97048 and Elias 3-1 are known to display both these features. We have obtained medium-resolution spectra (R ~2500) with the ESO near-IR instrument ISAAC in the 3.15-3.65 micron range. In our sample, no new examples of sources with prominent nanodiamond features in their 3 micron spectra were discovered (detection rate less than 4%). We report tentative 3.53 micron detections in V921 Sco (=CD-42.11721), HD 163296 and T CrA. The sources which display the nanodiamond features are not exceptional in the group of Herbig stars with respect to disk properties, stellar characteristics, or disk and stellar activity. Moreover, the nanodiamond sources are very different from each other in terms of these parameters. We do not find evidence for a recent supernova in the vicinity of any of the nanodiamond sources. We have analyzed the PAH 3.3 micron feature and the Pfund delta hydrogen emission line, two other spectral features which occur in the 3 micron wavelength range. We reinforce the conclusion of previous authors that flared-disk systems display significantly more PAH emission than self-shadowed-disk sources. The Pf delta line detection rate is higher in self-shadowed-disk sources than in the flared-disk systems. We discuss the possible origin and paucity of the (nano)diamond features in Herbig stars. Different creation mechanisms have been proposed in the literature, amongst others in-situ and supernova-induced formation. Our data set is inconclusive in proving or disproving either formation mechanism.
description: 22 pages, 9 figures, 5 tables; accepted for publication in A&A (acceptance date 16/06/2006)
A Banach Principle for Semifinite von Neumann Algebras
Creators: name: Chilin, Vladimir
name: Litvinov, Semyon
Publisher: name: arXiv
Year: 2006
Subjects: subject: Functional Analysis (math.FA)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics

description: Utilizing the notion of uniform equicontinuity for sequences of functions with the values in the space of measurable operators, we present a non-commutative version of the Banach Principle for $L^\infty$.
description: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/
TIME-VARYING COMPRESSION AMPLIFICATION WITH SPECTRAL SHARPENING
Creators: name: Siraj, Zaker
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Engineering, Electronics and Electrical (0544)

description: Multichannel amplitude compression processing is used to reduce the level variations of speech to fit the reduced dynamic ranges of listeners with sensorineural hearing loss. This processing, however, can result in smearing of temporal information, artifacts due to spectral discontinuities at fixed channel edges, and spectral flattening due to reduced peak-to-valley ratios. An implementation of a time-varying compression processing algorithm based on a sinusoidal speech model (Col-SM) operates on a time-varying, stimulus-dependent basis to adjust to the speech variations and the listener's hearing profile. The algorithm provides fast-acting compression with minimal audible artifact, has time-varying frequency channels, is computationally inexpensive and preserves the important spectral peaks in speech. Presented here is a Col-SM based algorithm that determines the levels of key spectral peaks and valleys to achieve time-varying compression amplification with spectral sharpening. The amount of sharpening can be set individually based on the needs of the listener. The algorithm has been adapted to operate in noisy environment. Preliminary subject tests will be presented.
Quantisation of bending flows
Creators: name: Falqui, Gregorio
name: Musso, Fabio
Publisher: name: arXiv
Year: 2006
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: We briefly review the Kapovich-Millson notion of Bending flows as an integrable system on the space of polygons in ${\bf R}^3$, its connection with a specific Gaudin XXX system, as well as the generalisation to $su(r), r>2$. Then we consider the quantisation problem of the set of Hamiltonians pertaining to the problem, quite naturally called Bending Hamiltonians, and prove that their commutativity is preserved at the quantum level.
description: 7 pages, submitted to Czech. J. Phys
The Globular Cluster M15. I. Identification, Discovery, and Period Determination of Variable Stars
Creators: name: Corwin, T. M.
name: Borissova, J.
name: Stetson, P. B.
name: Catelan, M.
name: Smith, H. A.
name: Kurtev, R.
name: Stephens, A. W.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present new $BVI$ CCD photometry for variables in the globular cluster M15. Our photometry was obtained using both the image subtraction package ISIS and DAOPHOT/ALLFRAME. The data were acquired in 2001 on two observing runs on 11 observing nights using the 2-m telescope of the Bulgarian National Astronomical Observatory ``Rozhen'' with a Photometrics CCD camera. For 40 previously known variables, we present a period for the first time, and improved periods were obtained for many previously known variables. Fourteen new variables are reported. We present updated Bailey diagrams for the cluster and discuss its Oosterhoff classification. Although many of M15's RRab pulsators fall at an intermediate locus between Oosterhoff types I and II in the Bailey diagram, we argue that M15 is indeed a bona-fide Oosterhoff type II
description: 48 pages, 7 figures, 3 tables
The Comparison of Online Social Networks In Terms of Strucure and Evolution
Creators: name: Wilson, Marcella
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: Computer Science (0984)

description: Social network systems on the Internet, such MySpace and LinkedIn, are growing in popularity around the world. The level of such activity is now comparable to that associated with email and blogs. Our research addresses the question of whether people in different demographic groups use these systems in the same way. We also examined the relationship between membership in on-line social networks and face-to-face networks, especially with respect to different age cohorts. Older Americans tend to use email the same way as Americans in general. The usage of blogs, however, is different, with significant differences in the temporal and structural patterns of post and response in blogs being evident in different demographics. Our research has implications for the design of social network software for older Americans, as well as the algorithms used in search engines for such systems.
Vector current conservation and neutrino emission from singlet-paired baryons in neutron stars
Creators: name: Leinson, L. B.
name: Perez, A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Neutrino emission caused by singlet Cooper pairing of baryons in neutron stars is recalculated by accurately taking into account for conservation of the vector weak currents. The neutrino emissivity via the vector weak currents is found to be several orders of magnitude smaller than that obtained before by different authors. This makes unimportant the neutrino radiation from singlet pairing of protons or hyperons.
description: 5 pages, 1 figure
MUSE reveals extended circumnuclear outflows in the Seyfert 1 NGC 7469
Creators: name: Robleto-Orús, A. C.
name: Torres-Papaqui, J. P.
name: Longinotti, A. L.
name: Ortega-Minakata, R. A.
name: Sánchez, S. F.
name: Ascasibar, Y.
name: Bellocchi, E.
name: Galbany, L.
name: Chow-Martínez, M.
name: Trejo-Alonso, J. J.
name: Morales-Vargas, A.
name: Romero-Cruz, F. J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: NGC 7469 is a well known Luminous IR Galaxy, with a circumnuclear star formation ring ($\sim 830$ pc radius) surrounding a Seyfert 1 AGN. Nuclear unresolved winds were previously detected in X-rays and UV, as well as an extended biconical outflow in IR coronal lines. We search for extended outflows by measuring the kinematics of the $\mathrm{Hβ}$ and [O III] $λ5007$ optical emission lines, in data of the VLT/MUSE integral field spectrograph. We find evidence of two outflow kinematic regimes: one slower regime extending across most of the star formation ring -- possibly driven by the massive star formation -- and a faster regime (with a maximum velocity of $-715 \ \mathrm{km \ s^{-1}}$), only observed in [O III], in the western region between the AGN and the massive star forming regions of the ring, likely AGN-driven. This work shows a case where combined AGN/star-formation feedback can be effectively spatially-resolved, opening up a promising path toward a deeper understanding of feedback processes in the central kiloparsec of AGN.
description: 10 pages, 5 figures. Accepted for publication in The Astrophysical Journal Letters
Selective recoupling and stochastic dynamical decoupling
Creators: name: Kern, O.
name: Alber, G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: An embedded selective recoupling method is proposed which is based on the idea of embedding the recently proposed deterministic selective recoupling scheme of Yamaguchi et al. [quant-ph/0411099] into a stochastic dynamical decoupling method, such as the recently proposed Pauli-random-error-correction-(PAREC) scheme [Eur. Phys. J. D 32, 153, quant-ph/0407262]. The recoupling scheme enables the implementation of elementary quantum gates in a quantum information processor by partial suppression of the unwanted interactions. The random dynamical decoupling method cancels a significant part of the residual interactions. Thus the time scale of reliable quantum computation is increased significantly. Numerical simulations are presented for a conditional two-qubit swap gate and for a complex iterative quantum algorithm.
A new attempt towards the unification of space-time and internal gauge symmetries
Creators: name: Aldaya, V.
name: Sánchez-Sastre, E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The neat formulation that describes the gauge interactions associated with internal symmetries is extended to the case of a simple, yet non-trivial, symmetry group structure which mixes gravity and electromagnetism by associating a gauge symmetry with a central extension of the Poincaré group.
description: 20 pages
Competing Orders and Hidden Duality Symmetries in Two-leg Spin Ladder Systems
Creators: name: Lecheminant, P.
name: Totsuka, K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A unifying approach to competing quantum orders in generalized two-leg spin ladders is presented. Hidden relationship and quantum phase transitions among the competing orders are thoroughly discussed by means of a low-energy field theory starting from an SU(4) quantum multicritical point. Our approach reveals that the system has a relatively simple phase structure in spite of its complicated interactions. On top of the U(1)-symmetry which is known from previous studies to mixes up antiferromagnetic order parameter with that of the p-type nematic, we find an emergent U(1)-symmetry which mixes order parameters dual to the above. On the basis of the field-theoretical- and variational analysis, we give a qualitative picture for the global structure of the phase diagram. Interesting connection to other models (e.g. bosonic t-J model) is also discussed.
description: 33 pages incl. 8 figures, accepted for publication in Phys.Rev.B
Enhancement of the electron spin memory by localization on donors in a quantum well
Creators: name: Tribollet, J.
name: Aubry, E.
name: Karczewski, G.
name: Sermage, B.
name: Bernardot, F.
name: Testelin, C.
name: Chamarro, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We present easily reproducible experimental conditions giving long electron spin relaxation and dephasing times at low temperature in a quantum well. The proposed system consists in an electron localized by a donor potential, and immerged in a quantum well in order to improve its localization with respect to donor in bulk. We have measured, by using photoinduced Faraday rotation technique, the spin relaxation and dephasing times of electrons localized on donors placed in the middle of a 80A CdTe quantum well, and we have obtained 15ns and 18ns, respectively, which are almost two orders of magnitude longer than the free electron spin relaxation and dephasing times obtained previously in a similar CdTe quantum well (J. Tribollet et al. PRB 68, 235316 (2003)).
description: 15 pages, 4 figures
A common framework for aspect mining based on crosscutting concern sorts
Creators: name: Marin, Marius
name: Moonen, Leon
name: van Deursen, Arie
Publisher: name: arXiv
Year: 2006
Subjects: subject: Software Engineering (cs.SE)
subject: Programming Languages (cs.PL)
subject: FOS: Computer and information sciences

description: The increasing number of aspect mining techniques proposed in literature calls for a methodological way of comparing and combining them in order to assess, and improve on, their quality. This paper addresses this situation by proposing a common framework based on crosscutting concern sorts which allows for consistent assessment, comparison and combination of aspect mining techniques. The framework identifies a set of requirements that ensure homogeneity in formulating the mining goals, presenting the results and assessing their quality. We demonstrate feasibility of the approach by retrofitting an existing aspect mining technique to the framework, and by using it to design and implement two new mining techniques. We apply the three techniques to a known aspect mining benchmark and show how they can be consistently assessed and combined to increase the quality of the results. The techniques and combinations are implemented in FINT, our publicly available free aspect mining tool.
description: 14 pages
On the Essential Spectrum of Many-Particle Pseudorelativistic Hamiltonians with Permutational Symmetry Account
Creators: name: Zhislin, Grigorii
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: Spectral Theory (math.SP)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: In this paper we formulate our results on the essential spectrum of many-particle pseudorelativistic Hamiltonians without magnetic and external potential fields in the spaces of functions, having arbitrary type $α$ of the permutational symmetry. We discover location of the essential spectrum for all $α$ and for some cases we establish new properties of the lower bound of this spectrum, which are useful for study of the discrete spectrum.
description: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/
Improvement of algorithms for dynamical overlap fermions
Creators: name: JLQCD Collaboration
name: Matsufuru, Hideo
name: Fukaya, Hidenori
name: Hashimoto, Shoji
name: Kanaya, Kazuyuki
name: Kaneko, Takashi
name: Ogawa, Kenji
name: Okamoto, Masataka
name: Onogi, Tetsuya
name: Yamada, Norikazu
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We investigate the algorithms for dynamical overlap fermions aiming at improving the performance for large-scale simulations. We look for the best combination of Hybrid Monte Carlo options and iterative quark solvers with respect to the numerical costs. Our main target is a $N_f=2$ simulation with overlap fermion on a $16^3\times 32$ lattice at lattice spacing around 0.12 fm.
description: 7 pages, 8 figures, talk given at Lattice 2006 (Algorithms, Machines, and Networks), to appear in Proceedings Of Science, POS(LAT2006)031