cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The Casimir effect within scattering theory
Creators: name: Lambrecht, A.
name: Neto, P. A. Maia
name: Reynaud, S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We review the theory of the Casimir effect using scattering techniques. After years of theoretical efforts, this formalism is now largely mastered so that the accuracy of theory-experiment comparisons is determined by the level of precision and pertinence of the description of experimental conditions. Due to an imperfect knowledge of the optical properties of real mirrors used in the experiment, the effect of imperfect reflection remains a source of uncertainty in theory-experiment comparisons. For the same reason, the temperature dependence of the Casimir force between dissipative mirrors remains a matter of debate. We also emphasize that real mirrors do not obey exactly the assumption of specular reflection, which is used in nearly all calculations of material and temperature corrections. This difficulty may be solved by using a more general scattering formalism accounting for non-specular reflection with wavevectors and field polarizations mixed. This general formalism has already been fruitfully used for evaluating the effect of roughness on the Casimir force as well as the lateral Casimir force appearing between corrugated surfaces. The commonly used `proximity force approximation' turns out to lead to inaccuracies in the description of these two effects.
description: 15 pages, 12 figures
The clustering of narrow-line AGN in the local Universe
Creators: name: Li, Cheng
name: Kauffmann, Guinevere
name: Wang, Lan
name: White, Simon D. M.
name: Heckman, Timothy M.
name: Jing, Y. P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have analyzed the clustering of ~ 90,000 narrow-line AGN drawn from the Data Release 4 (DR4) of the SDSS. We compute the cross-correlation between AGN and a reference sample of galaxies, and compare this to results for control samples of inactive galaxies matched simultaneously in redshift,stellar mass,concentration, velocity dispersion and the 4000A break strength. We also compare near-neighbour counts around AGN and around the control galaxies. On scales larger than a few Mpc, AGN have almost the same clustering amplitude as the control sample. This demonstrates that AGN host galaxies and inactive galaxies populate dark matter halos of similar mass.On scales between 100kpc and 1Mpc,AGN are clustered more weakly than the control galaxies. We use mock catalogues constructed from high-resolution N-body simulations to interpret this anti-bias, showing that the observed effect is easily understood if AGN are preferentially located at the centres of their dark matter halos. On scales less than 70 kpc, AGN cluster marginally more strongly than the control sample, but the effect is weak. When compared to the control sample, we find that only one in a hundred AGN has an extra neighbour within a radius of 70 kpc. This excess increases as a function of the accretion rate onto the black hole, but it does not rise above the few percent level. Although interactions between galaxies may be responsible for triggering nuclear activity in a minority of nearby AGN, some other mechanism is required to explain the activity seen in the majority of the objects in our sample. (abridged)
description: 14 pages, 11 figures, accepted to MNRAS, Fig.2 redrawn and text slightly changed
R examples -- Reduced Animal Models Fitting Only Equations for Phenotyped Animals
Creators: name: Nilforooshan, Mohammad Ali
name: Garrick, Dorian
Publisher: name: figshare
Year: 2021
Subjects: subject: 70201 Animal Breeding
subject: FOS: Animal and dairy science
subject: Genetics
subject: FOS: Biological sciences

description: The provided materials are R scripts to produce the example data and perform the analyses in a study of reduced animal models to fit equations for phenotyped animals. Below, a short description is given to each file.
* e31data.R: Produces data for example 3.1 of Mrode (2005, doi: 10.1079/9780851990002.0000)* e34data.R: Produces data for example 3.4 of Mrode (2005, doi: 10.1079/9780851990002.0000)* e41data.R: Produces data for example 4.1 of Mrode (2005, doi: 10.1079/9780851990002.0000)* e53data.R: Produces data for example 5.3 of Mrode (2005, doi: 10.1079/9780851990002.0000)* e61data.R: Produces data for example 6.1 of Mrode (2005, doi: 10.1079/9780851990002.0000)* e31.R: BLUP function used to solve the full and the reduced BLUP, GBLUP and ssGBLUP for the data produced by e31data.R, and the reduced BLUP for the data produced by e34data.R* e34.R: BLUP function used to solve the full BLUP for the data produced by e34data.R* e41.R: BLUP function used to solve the full and the reduced BLUP for the data produced by e41data.R* e53.R: BLUP function used to solve the full and the reduced BLUP for the data produced by e53data.R* e61.R: BLUP function used to solve the full and the reduced BLUP for the data produced by e61data.R* getPhi.R: getPhi function to calculate the Phi matrix for the reduced animal model given the A^-1 matrix and the list of phenotyped animals* makeGi.R: Produces a G^-1 matrix for the data produced by e31data.R* check.R: check function for element-wise comparison of the solutions of the full and the reduced animal model
การพัฒนารูปแบบตัวอักษรไทยมุสลิมด้วยแนวคิดท้องถิ่นภิวัตน์เพื่อสะท้อนอัตลักษณ์ชาวไทยมุสลิม
Creators: name: ดนุ ภู่มาลี, เกรียงศักดิ์ เขียวมั่ง, สุชาติ เถาทอง
Publisher: name: สำนักวิทยบริการ มหาวิทยาลัยสงขลานครินทร์ วิทยาเขตปัตตานี
Year: 2019
Subjects: รูปแบบตัวอักษร, ท้องถิ่นภิวัตน์, อัตลักษณ์, ชาวไทยมุสลิม, typeface design, localization, identities, Thai-Muslim

description: วารสารวิทยบริการ มหาวิทยาลัยสงขลานครินทร์, 30, 2, 11-22
Low-frequency noise and tunnelling magnetoresistance in Fe(110)/MgO(111)/Fe(110) epitaxial magnetic tunnel junctions
Creators: name: Guerrero, R.
name: Aliev, F. G.
name: Villar, R.
name: Hauch, J.
name: Fraune, M.
name: Guntherodt, G.
name: Rott, K.
name: Bruckl, H.
name: Reiss, G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We report on tunnelling magnetoresistance (TMR), current-voltage (IV) characteristics and low frequency noise in epitaxially grown Fe(110)/MgO(111)/Fe(110) magnetic tunnel junctions (MTJs) with dimensions from 2x2 to 20x20 um2. The evaluated MgO energy barrier (0.50+/-0.08 eV), the barrier width (13.1+/-0.5 angstrom) as well as the resistance times area product (7+/-1 Mohmsum2) show relatively small variation, confirming a high quality epitaxy and uniformity of all MTJs studied. The noise power, though exhibiting large variation, was observed to be roughly anticorrelated with the TMR. Surprisingly, for the largest junctions we observed a strong enhancement of the normalized low-frequency noise in the antiparallel magnetic configuration. This behaviour could be related to an interplay between the magnetic state and the local barrier defects structure of the epitaxial MTJs
description: 9 pages and 3 figures
Supersymmetry breaking in a warped slice with Majorana-type masses
Creators: name: Abe, Hiroyuki
name: Sakamura, Yutaka
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the five-dimensional (5D) supergravity compactified on an orbifold S^1/Z_2, where the U(1)_R symmetry is gauged by the graviphoton with Z_2-even coupling. In contrast to the case of gauging with Z_2-odd coupling, this class of models has Majorana-type masses and allows the Scherk-Schwarz (SS) twist even in the warped spacetime. Starting from the off-shell formulation, we show that the supersymmetry is always broken in an orbifold slice of AdS_5, irrespective of the value of the SS twist parameter. We analyze the spectra of gaugino and gravitino in such background, and find the SS twist can provide sizable effects on them in the small warping region.
description: 1+20 pages, 6 figures
รูปแบบการพัฒนาภาวะผู้นำเชิงพหุวัฒนธรรมของผู้บริหารสถานศึกษา สังกัดสำนักงานเขตพื้นที่การศึกษามัธยมศึกษา เขต 15
Creators: name: ชวลิต เกิดทิพย์, วรภาคย์ ไมตรีพันธ์, สุดารัตน์ พรหมแก้ว, บรรจง รุ่งฟ้าสาง
Publisher: name: สำนักวิทยบริการ มหาวิทยาลัยสงขลานครินทร์ วิทยาเขตปัตตานี
Year: 2019
Subjects: ภาวะผู้นำ, พหุวัฒนธรรม, ผู้บริหารสถานศึกษา, สำนักงานเขตพื้นที่การศึกษามัธยมศึกษา, leadership, multicultural, school administrators, Secondary Education Service Area Office

description: วารสารวิทยบริการ มหาวิทยาลัยสงขลานครินทร์, 30, 2, 23-33
Towards a model-independent reconstruction approach for late-time Hubble data
Creators: name: Bernardo, Reginald Christian
name: Said, Jackson Levi
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Gaussian processes offers a convenient way to perform nonparametric reconstructions of observational data assuming only a kernel which describes the covariance between neighbouring points in a data set. We approach the ambiguity in the choice of kernel in Gaussian processes with two methods -- (a) approximate Bayesian computation with sequential Monte Carlo sampling and (b) genetic algorithm -- and use the overall resulting method to reconstruct the cosmic chronometers and supernovae type Ia data sets. The results have shown that the Matérn$\left( ν= 5/2 \right)$ kernel emerges on top of the two-hyperparameter family of kernels for both cosmological data sets. On the other hand, we use the genetic algorithm in order to select a most naturally-fit kernel among a competitive pool made up of a ten-hyperparameters class of kernels. Imposing a Bayesian information criterion-inspired measure of the fitness, the results have shown that a hybrid of the Radial Basis Function and the Matérn$\left( ν= 5/2 \right)$ kernel best represented both data sets. The kernel selection problem is not totally closed and may benefit from further analysis using other strategies to resolve an optimal kernel for a particular data set.
description: 21 pages, 6 figures, 7 tables, v2: typos fixed, discussion improved, references added, to appear at JCAP
Theory of quantum metal to superconductor transitions in highly conducting systems
Creators: name: Spivak, B.
name: Oreto, P.
name: Kivelson, S. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We derive the theory of the quantum (zero temperature) superconductor to metal transition in disordered materials when the resistance of the normal metal near criticality is small compared to the quantum of resistivity. This can occur most readily in situations in which ``Anderson's theorem'' does not apply. We explicitly study the transition in superconductor-metal composites, in an s-wave superconducting film in the presence of a magnetic field, and in a low temperature disordered d-wave superconductor. Near the point of the transition, the distribution of the superconducting order parameter is highly inhomogeneous. To describe this situation we employ a procedure which is similar to that introduced by Mott for description of the temperature dependence of the variable range hopping conduction. As the system approaches the point of the transition from the metal to the superconductor, the conductivity of the system diverges, and the Wiedemann-Franz law is violated. In the case of d-wave (or other exotic) superconductors we predict the existence of (at least) two sequential transitions as a function of increasing disorder: a d-wave to s-wave, and then an s-wave to metal transition.
Dual permeability modeling of fractured media
Creators: name: Clemo, Thomas Meldon
Publisher: name: University of British Columbia
Year: 2009

description: Dual permeability is introduced as an approach to modeling flow and transport through fractured media. The approach allows a large reduction in the number of fractures that are represented explicitly in a discrete fracture network. The most important fractures in terms of fluid flow are identified using their physical characteristics. These fractures form a sub-network that divides the entire fracture network into smaller domains. The fractures of the smaller domains are approximated. The approximations do not rely on continuum assumptions. They are determined individually and independently for each small domain, resulting in a parallel structure to the calculations. An exploratory model is developed for steady state fluid flow and solute transport in two dimensional fracture networks and compared to a discrete fracture model that represents all of the fractures explicitly. Individual fractures are represented by finite lines with constant hydraulic transmissivity. Solute transport calculations use particle tracking. The dual permeability model is shown to provide acceptably accurate solutions while reducing the maximum number of simultaneous equations by well over an order of magnitude. The dual permeability approach takes advantage of the hydraulic behavior of highly heterogeneous media. Channeling of flow that develops in such media is used to reduce errors introduced through the sub-continuum approximations. The dual permeability approach works better when the fracture system has a broad range in the scale of fracturing as demonstrated by transport calculations for fracture networks with a high degree of clustering or with a fractal nature. A study of sub-REV fracture networks reveals that averaged flow through fractured media can be represented using tensor notation in much smaller domains than an REV. At these scales, heterogeneity within a fracture domain causes the tensor representation to be asymmetric, unlike the continuum representation of granular porous media. Hydraulic heads within a heterogeneous fracture network do not vary in a smooth fashion. The hydraulic head reflects the distribution of heterogeneity within the domain. The approximations developed for the dual permeability model required that the boundary conditions imposed on the small domains reflect heterogeneity both within the domains and external to them.
A metal rich molecular cloud surrounds GRB 050904 at redshift 6.3
Creators: name: Campana, S.
name: Lazzati, D.
name: Ripamonti, E.
name: Perna, R.
name: Covino, S.
name: Tagliaferri, G.
name: Moretti, A.
name: Romano, P.
name: Cusumano, G.
name: Chincarini, G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: GRB050904 is the gamma-ray burst with the highest measured redshift. We performed time resolved X-ray spectroscopy of the late GRB and early afterglow emission. We find robust evidence for a decrease with time of the soft X-ray absorbing column. We model the evolution of the column density due to the flash ionization of the GRB and early afterglow photons. This allows us to constrain the metallicity and geometry of the absorbing cloud. We conclude that the progenitor of GRB050904 was a massive star embedded in a dense metal enriched molecular cloud with Z~0.03 Z_solar. This is the first local measurement of metallicity in the close environment of a GRB and one of the highest redshift metallicity measurements. We also find that the dust associated with the cloud cannot be similar to that of our Galaxy but must be either sizably depleted or dominated by silicate grains. We discuss the implications of these results for GRB progenitors and high redshift star formation.
description: 4 pages, 2 figures. Accepted for publication on Astrophysical Journal Letters
Simulation of Collective Neutrino Oscillations on a Quantum Computer
Creators: name: Hall, Benjamin
name: Roggero, Alessandro
name: Baroni, Alessandro
name: Carlson, Joseph
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In astrophysical scenarios with large neutrino density, like supernovae and the early universe, the presence of neutrino-neutrino interactions can give rise to collective flavor oscillations in the out-of-equilibrium collective dynamics of a neutrino cloud. The role of quantum correlations in these phenomena is not yet well understood, in large part due to complications in solving for the real-time evolution of the strongly coupled many-body system. Future fault-tolerant quantum computers hold the promise to overcome much of these limitations and provide direct access to the correlated neutrino dynamic. In this work, we present the first simulation of a small system of interacting neutrinos using current generation quantum devices. We introduce a strategy to overcome limitations in the natural connectivity of the qubits and use it to track the evolution of entanglement in real-time. The results show the critical importance of error-mitigation techniques to extract meaningful results for entanglement measures using noisy, near term, quantum devices.
description: 12 pages, 12 figures
Superconductivity in an extreme strange metal
Creators: name: Nguyen, D. H.
name: Sidorenko, A.
name: Taupin, M.
name: Knebel, G.
name: Lapertot, G.
name: Schuberth, E.
name: Paschen, S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Some of the highest-transition-temperature superconductors across various materials classes exhibit linear-in-temperature `strange metal' or `Planckian' electrical resistivities in their normal state. It is thus believed by many that this behavior holds the key to unlock the secrets of high-temperature superconductivity. However, these materials typically display complex phase diagrams governed by various competing energy scales, making an unambiguous identification of the physics at play difficult. Here we use electrical resistivity measurements into the micro-Kelvin regime to discover superconductivity condensing out of an extreme strange metal state -- with linear resistivity over 3.5 orders of magnitude in temperature. We propose that the Cooper pairing is mediated by the modes associated with a recently evidenced dynamical charge localization-delocalization transition, a mechanism that may well be pertinent also in other strange metal superconductors.
description: 8 pages, 4 figures, 2 tables plus supplementary information (6 pages, 3 figures)
Casimir effect in rugby-ball type flux compactifications
Creators: name: Elizalde, Emilio
name: Minamitsuji, Masato
name: Naylor, Wade
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: As a continuation of the work in \cite{mns}, we discuss the Casimir effect for a massless bulk scalar field in a 4D toy model of a 6D warped flux compactification model,to stabilize the volume modulus. The one-loop effective potential for the volume modulus has a form similar to the Coleman-Weinberg potential. The stability of the volume modulus against quantum corrections is related to an appropriate heat kernel coefficient. However, to make any physical predictions after volume stabilization, knowledge of the derivative of the zeta function, $ζ'(0)$ (in a conformally related spacetime) is also required. By adding up the exact mass spectrum using zeta function regularization, we present a revised analysis of the effective potential. Finally, we discuss some physical implications, especially concerning the degree of the hierarchy between the fundamental energy scales on the branes. For a larger degree of warping our new results are very similar to the previous ones \cite{mns} and imply a larger hierarchy. In the non-warped (rugby-ball) limit the ratio tends to converge to the same value, independently of the bulk dilaton coupling.
description: 13 pages, 6 figures, accepted for publication in PRD
Complex BPS Skyrmions with real energy
Creators: name: Correa, Francisco
name: Fring, Andreas
name: Taira, Takanobu
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We propose and investigate several complex versions of extensions and restrictions of the Skyrme model with a well-defined Bogomolny-Prasad-Sommerfield (BPS) limit. The models studied possess complex kink, anti-kink, semi-kink, massless and purely imaginary compacton BPS solutions that all have real energies. The reality of the energies for a particular solution is guaranteed when a modified antilinear CPT-symmetry maps the Hamiltonian functional to its parity time-reversed complex conjugate and the solution field to itself or a new field with degenerate energy. In addition to the known BPS Skyrmion configurations we find new types that we refer to as step, cusp, shell, and purely imaginary compacton solutions.
description: 21 pages, 7 figures
Towards a Principled, Computational, and Risk-Based Perspective in Dark Networks
Creators: name: Shaheen, Joseph
Publisher: name: figshare
Year: 2021
Subjects: subject: 160510 Public Policy
subject: FOS: Political science
subject: 160509 Public Administration
subject: 160206 Private Policing and Security Services
subject: FOS: Law

description: In the domain of utilizing network data to ensure safety and national security, the paradigm of Dark Networks offers a systemic approach to identifying 'nodes of interest' in social networks. This paradigm is primarily based on the well-developed concepts of Social Network Analysis, but relies heavily on heuristic approaches that are often unprincipled (though powerful) from a statistical perspective. Recent advances in Network Science as well as greater availability of computational resources allow for more cautious approaches designed for risk-considered target policy-making.
Turbulence and transport in two-dimensional magnetized electron plasmas
Creators: name: Shaikh, Dastgeer
name: Shukla, P. K.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Electron plasmas confined by an external magnetic field exhibit variations in a two-dimensional plane orthogonal to the confining magnetic field. A nonlinear fluid simulation code to investigate the properties of 2-D electron plasma wave turbulence in a nonuniform magnetoplasma has been developed. It is found that the presence of the density gradient convection by mean electric fields considerably influence the characteristic nonlinear interaction processes, such as the energy cascades and the cross-field electron transport. The initial random turbulent state evolves towards an intermittent state where forward cascade of vorticity coexists with an inverse cascade of electric potential fluctuations. The latter lead to the formation of large scale entities in 2D electron plasmas and can be alternatively understood by seeking exact nonlinear coherent vortex solutions in the form of a dipolar-like configuration. The energy cascades are governed typically by the Kolmogorov-like $k^{-5/3}$ spectrum. In agreement with the experimental observations, we find that the electron transport is improved significantly by the application of an externally imposed electric field.
On a semiclassical formula for non-diagonal matrix elements
Creators: name: Lev, O.
name: Stovicek, P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Let $H(\hbar)=-\hbar^2d^2/dx^2+V(x)$ be a Schrödinger operator on the real line, $W(x)$ be a bounded observable depending only on the coordinate and $k$ be a fixed integer. Suppose that an energy level $E$ intersects the potential $V(x)$ in exactly two turning points and lies below $V_\infty=\liminf_{|x|\to\infty} V(x)$. We consider the semiclassical limit $n\to\infty$, $\hbar=\hbar_n\to0$ and $E_n=E$ where $E_n$ is the $n$th eigen-energy of $H(\hbar)$. An asymptotic formula for $$, the non-diagonal matrix elements of $W(x)$ in the eigenbasis of $H(\hbar)$, has been known in the theoretical physics for a long time. Here it is proved in a mathematically rigorous manner.
description: LaTeX2e
Lattice dynamics and electron-phonon coupling in Sr2RuO4
Creators: name: Braden, M.
name: Reichardt, W.
name: Sidis, Y.
name: Mao, Z.
name: Maeno, Y.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The lattice dynamics in Sr$_2$RuO$_4$ has been studied by inelastic neutron scattering combined with shell-model calculations. The in-plane bond-stretching modes in Sr$_2$RuO$_4$ exhibit a normal dispersion in contrast to all electronically doped perovskites studied so far. Evidence for strong electron phonon coupling is found for c-polarized phonons suggesting a close connection with the anomalous c-axis charge transport in Sr$_2$RuO$_4$.
description: 11 pages, 8 figures 2 tables
A CO-to-H$_2$ ratio of $\approx 10^{-5}$ towards the Herbig Ae star HK Ori
Creators: name: Cauley, P. Wilson
name: France, Kevin
name: Herzceg, Gregory J.
name: Johns-Krull, Christopher M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Measurements of gas mass in protoplanetary gas disks form the basis for estimating the conditions of planet formation. Among the most important constraints derived from disk diagnostics are the abundances of gas-phase species critical for understanding disk chemistry. Towards this end, we present direct line-of-sight measurements of H$_{2}$ and CO, employing UV absorption spectroscopy from $HST$-COS to characterize disk composition, molecular excitation temperatures, and spatial distribution in the circumstellar material around the Herbig Ae stars HK Ori and T Ori. We observe strong CO (N(CO) = 10$^{15.5}$ cm$^{-2}$; T$_{rot}$(CO) = 19 K) and H$_{2}$ (N(H$_{2}$) = 10$^{20.34}$ cm$^{-2}$; T$_{rot}$(H$_{2}$) = 141 K) absorption towards HK Ori with a CO/H$_{2}$ ratio ($\equiv$ N(CO)/N(H$_{2}$)) = 1.3$^{+1.6}_{-0.7}$~$\times$~10$^{-5}$. These measurements place direct empirical constraints on the CO-to-H$_{2}$ conversion factor in the disk around a Herbig Ae star for the first time, although there is uncertainty concerning the exact viewing geometry of the disk. The spectra of T Ori show CO (N(CO) = 10$^{14.9}$ cm$^{-2}$; T$_{rot}$(CO) = 124 K) absorption. Interestingly, we do not detect any H$_{2}$ absorption towards this star (N(H$_{2}$) $
description: 15 pages, 11 figures. Accepted to AAS journals on 02/24/2021
Multi-scale semi-Lagrangian lattice Boltzmann method
Creators: name: Kallikounis, N. G.
name: Dorschner, B.
name: Karlin, I. V.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: We present a multi-scale lattice Boltzmann scheme, which adaptively refines particles' velocity space. Different velocity sets, i.e., higher- and lower-order lattices, are consistently and efficiently coupled, allowing us to use the higher-order lattice only when and where needed. This includes regions of either high Mach number or high Knudsen number. The coupling procedure of different lattices consists of either projection of the moments of the higher-order lattice onto the lower-order lattice or lifting of the lower-order lattice to the higher-order velocity space. Both lifting and projection are local operations, which enable a flexible adaptive velocity set. The proposed scheme can be formulated both in a static and an optimal, co-moving reference frame, in the spirit of the recently introduced Particles on Demand method. The multi-scale scheme is first validated through a convected athermal vortex and also studied in a jet flow setup. The performance of the proposed scheme is further investigated through the shock structure problem and a high Knudsen Couette flow, typical examples of highly non-equilibrium flows in which the order of the velocity set plays a decisive role. The results demonstrate that the proposed multi-scale scheme can operate accurately, with flexibility in terms of the underlying models and with reduced computational requirements.
Examination of the mineralogical effects of biologically-assisted leaching of a mixed copper sulphide ore from the Ivan mine, Chile
Creators: name: Melluish, Julie Marguerite
Publisher: name: University of British Columbia
Year: 2009

description: A mineralogical and biohydrometallurgical study of a mixed copper-sulphide ore from the Ivan Mine near Antofagasta in northern Chile was conducted by a multidisciplinary group at the University of British Columbia. The purpose of the mineralogical study was to establish an understanding of current knowledge regarding biologically-assisted leaching, especially as it relates to the solids involved, while supplying mineralogical support for the metallurgical experiments. An extensive review of bioleaching, a brief description of the Ivan Mine, a summary of the metallurgical experiments, a discussion of results from computer modeling of a column leach experiment, a report of the results from a detailed mineralogical study of the solid residues from two of the column experiments, and suggestions for future studies are included in this work. Bacteria that utilize energy derived from oxidation of reduced iron and/or sulphur species play an important role in the leaching of copper suiphides by catalizing specific reactions. Although much is known about the leaching process current understanding of the interactions between these bacteria and the solids in the system is incomplete. The simulation of a colunm leach experiment using the computer program PATH supplied useful insights into the chemical processes occurring. Although the overall column reaction was studied here, a modeling program such as this is useful for examining possible reactions in microenvironments within the columns. Detailed mineralogical examination of the solid residues from two of the column experiments revealed several interesting features. The insoluble precipitates forming in the column are jarosite, a non-crystalline iron-phosphate (possibly strengite), and a non-crystalline iron oxide-sulphate (possibly schwertmannite). These precipitates generally occur in porous particle coatings scattered with silicate mineral grains. The leached particles commonly exhibit an increase in the number of veins, voids, and regions of porous silicate alteration, predominantly in rims up to 500 μm thick. Larger veins and regions of porous silicate alteration expose the interiors of many particles to the leach solution. Bornite and anilite appear to alter to covellite before solubilizing. Dissolution of covellite and large chalcopyrite grains (commonly aggregates) occurs along grain boundaries sometimes leaving a porous crust of elemental sulphur.
Flavour symmetry restoration and kaon weak matrix elements in quenched twisted mass QCD
Creators: name: Dimopoulos, P.
name: Heitger, J.
name: Palombi, F.
name: Pena, C.
name: Sint, S.
name: Vladikas, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We simulate two variants of quenched twisted mass QCD (tmQCD), with degenerate Wilson quarks of masses equal to or heavier than half the strange quark mass. We use Ward identities in order to measure the twist angles of the theory and thus check the quality of the tuning of mass parameters to a physics condition which stays constant as the lattice spacing is varied. Flavour symmetry breaking in tmQCD is studied in a framework of two fully twisted and two standard Wilson quark flavours, tuned to be degenerate in the continuum. Comparing pseudoscalar masses, obtained from connected quark diagrams made of tmQCD and/or standard Wilson quark propagators, we confirm that flavour symmetry breaking effects, which are at most 5%, decrease as we approach the continuum limit. We also compute the pseudoscalar decay constant in the continuum limit, with reduced systematics. As a consequence of improved tuning of the mass parameters at $β= 6.1$, we reanalyse our previous $B_K$ results. Our main phenomenological findings are $r_0 f_K = 0.421(7)$ and $\hat B_K = 0.735(71)$.
description: 41 pages, figures included, one reference added. Final version as accepted for publication on Nucl.Phys.B
Communication and Personality Profiles of Global Software Developers
Creators: name: Licorish, Sherlock A.
name: MacDonell, Stephen G.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Context: Prior research has established that a small proportion of individuals dominate team communication during global software development. It is not known, however, how these members' contributions affect their teams' knowledge diffusion process, or whether their personality profiles are responsible for their dominant presence. Objective: We set out to address this gap through the study of repository artifacts. Method: Artifacts from ten teams were mined from the IBM Rational Jazz repository. We employed social network analysis (SNA) to group practitioners into two clusters, Top Members and Others, based on the numbers of messages they communicated and their engagement in task changes. SNA metrics (density, in-degree and closeness) were then used to study practitioners' importance in knowledge diffusion. Thereafter, we performed psycholinguistic analysis on practitioners' messages using linguistic dimensions that had been previously correlated with the Big Five personality profiles. Results: For our sample of 146 practitioners we found that Top Members occupied critical roles in knowledge diffusion, and demonstrated more openness to experience than the Others. Additionally, all personality profiles were represented during teamwork, although openness to experience, agreeableness and extroversion were particularly evident. However, no specific personality predicted members' involvement in knowledge diffusion. Conclusion: Task assignment that promotes highly connected team communication networks may mitigate tacit knowledge loss in global software teams. Additionally, while members expressing openness to experience are likely to be particularly driven to perform, this is not entirely responsible for a global team's success.
description: Journal Paper, 22 pages, 5 figures, 6 tables, 1 appendix. arXiv admin note: substantial text overlap with arXiv:2102.09732
ETN Database
Creators: name: Reubens, Jan
name: Afonso, Pedro
Publisher: name: AtlantOS
Year: 2019

description: D3.21 ETN Database: Development of a European Tracking Network component of researchers and database, sharing common standards and protocols, data formats and platforms, and interlinked to other existing or developing Atlantic Ocean networks in Canada, the USA, Africa, and South America (starting in Brazil) to provide a global Atlantic tracking network. PM45
Vertex corrections in localized and extended systems
Creators: name: Morris, Andrew J.
name: Stankovski, Martin
name: Delaney, Kris T.
name: Rinke, Patrick
name: García-González, P.
name: Godby, R. W.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Within many-body perturbation theory we apply vertex corrections to various closed-shell atoms and to jellium, using a local approximation for the vertex consistent with starting the many-body perturbation theory from a DFT-LDA Green's function. The vertex appears in two places -- in the screened Coulomb interaction, W, and in the self-energy, Σ-- and we obtain a systematic discrimination of these two effects by turning the vertex in Σon and off. We also make comparisons to standard GW results within the usual random-phase approximation (RPA), which omits the vertex from both. When a vertex is included for closed-shell atoms, both ground-state and excited-state properties demonstrate only limited improvements over standard GW. For jellium we observe marked improvement in the quasiparticle band width when the vertex is included only in W, whereas turning on the vertex in Σleads to an unphysical quasiparticle dispersion and work function. A simple analysis suggests why implementation of the vertex only in W is a valid way to improve quasiparticle energy calculations, while the vertex in Σis unphysical, and points the way to development of improved vertices for ab initio electronic structure calculations.
description: 8 Pages, 6 Figures. Updated with quasiparticle neon results, extended conclusions and references section. Minor changes: Updated references, minor improvements
Constraints for the spectra of generators of quantum dynamical semigroups
Creators: name: Chruscinski, Dariusz
name: Fujii, Ryohei
name: Kimura, Gen
name: Ohno, Hiromichi
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Motivated by a spectral analysis of the generator of completely positive trace-preserving semigroup, we analyze a real functional $$ A,B \in M_n(\mathbb{C}) \to r(A,B) = \frac{1}{2}\Bigl(\langle [B,A],BA\rangle + \langle [B,A^\ast],BA^\ast \rangle \Bigr) \in \mathbb{R} $$ where $\langle A,B\rangle := {\rm tr} (A^\ast B)$ is the Hilbert-Schmidt inner product, and $[A,B]:= AB - BA$ is the commutator. In particular we discuss the upper and lower bounds of the form $c_- \|A\|^2 \|B\|^2 \le r(A,B) \le c_+ \|A\|^2 \|B\|^2$ where $\|A\|$ is the Frobenius norm. We prove that the optimal upper and lower bounds are given by $c_\pm = \frac{1 \pm \sqrt{2}}{2}$. If $A$ is restricted to be traceless, the bounds are further improved to be $c_\pm = \frac{1 \pm \sqrt{2(1-\frac{1}{n})}}{2}$. Interestingly, these upper bounds, especially the latter one, provide new constraints on relaxation rates for the quantum dynamical semigroup tighter than previously known constraints in the literature. A relation with Böttcher-Wenzel inequality is also discussed.
description: 19 pages
Charting Galactic Accelerations: When and How to Extract a Unique Potential from the Distribution Function
Creators: name: An, J.
name: Naik, A.
name: Evans, N. W.
name: Burrage, C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The advent of datasets of stars in the Milky Way with six-dimensional phase-space information makes it possible to construct empirically the distribution function (DF). Here, we show that the accelerations can be uniquely determined from the DF using the collisionless Boltzmann equation, providing the Hessian determinant of the DF with respect to the velocities is non-vanishing. We illustrate this procedure and requirement with some analytic examples. Methods to extract the potential from datasets of discrete positions and velocities of stars are then discussed. Following Green & Ting (arXiv:2011.04673), we advocate the use of normalizing flows on a sample of observed phase-space positions to obtain a differentiable approximation of the DF. To then derive gravitational accelerations, we outline a semi-analytic method involving direct solutions of the over-constrained linear equations provided by the collisionless Boltzmann equation. Testing our algorithm on mock datasets derived from isotropic and anisotropic Hernquist models, we obtain excellent accuracies even with added noise. Our method represents a new, flexible and robust means of extracting the underlying gravitational accelerations from snapshots of six-dimensional stellar kinematics of an equilibrium system.
description: 10 pages, 4 figures, MNRAS, in press
Σχεδιασμός, σύνθεση και χαρακτηρισμός υδραζονικών και πυριτιούχων ετεροκυκλικών υποστρωμάτων για ανάπτυξη προϊόντων προστιθέμενης αξίας
Creators: name: Μανιαδάκη, Αννα Εμμανουήλ
Publisher: name: Aristotle University of Thessaloniki
Year: 2017
Subjects: πυρίτιο
ετεροκυκλικά
υδραζόνες
silicon
heterocycles
hydrazones

description: Ο σχεδιασμός, η σύνθεση και ο χαρακτηρισμός υδραζονικών υποστρωμάτων, καθώς και πυριτιούχων ετεροκυκλικών υποστρωμάτων με πιθανές οπτοηλεκτρονικές ιδιότητες, αποτελούν τα κύρια αντικείμενα της παρούσας μελέτης. Τα υποστρώματα αυτά επρόκειτο να χρησιμοποιηθούν για την ανάπτυξη νέων προïόντων προστιθέμενης αξίας. Συγκεκριμένα, συντέθηκε μία σειρά καρβονυλο υδραζονών της 2-υδροξυ-1-ακετοναφθόνης μέσω της αντίδρασης της 2-υδροξυ-1-ακετοναφθόνης με το κατάλληλο υδραζίδιο σε προπανόλη με θέρμανση με κάθετο ψυκτήρα (reflux) σε πολύ καλές αποδόσεις. Επιπλέον, η κατεργασία των των υδραζονικών υποστρωμάτων που συντέθηκαν με τετραοξικό πυρίτιο παρουσία καταλύτη οδήγησε στο σχηματισμό πυριτιούχων ετεροδικυκλικών υποστρωμάτων σε καλές αποδόσεις. Τα υδραζονικά και τα πυριτιούχα ετεροκυκλικά υποστρώματα χαρακτηρίστηκαν με IR, 1H NMR, 13C NMR, φάσματα μαζών, στοιχειακή ανάλυση, μέτρηση HRMS, καθώς και ανάλυση ακτίνων-Χ
description: The design, the synthesis and the characterization of hydrazonic substrates as well as of silicon heterocyclic substrates with perspective optoelectronic properties are the main objects of this study. These substrates are going to be used for development of new added value products. Specifically, a series of carbonyl hydrazones of 2-hydroxy-1-acetonaphthone have been synthesized via the reaction of 2-hydroxy-1-acetonaphthone with the appropriate hydrazide in propanol under reflux in very good yields. Furthermore, treatment of the synthesized hydrazonic substrates with silicon tetraacetate in presence of catalyst led to the formation of silicon heterobicyclic substrates in good yields. The hydrazonic and the silicon heterocyclic substrates were characterized by IR, 1H NMR, 13C NMR, MS, HRMS and elemental analysis as well as X-Ray analysis
Analyzing Confidentiality and Privacy Concerns: Insights from Android Issue Logs
Creators: name: Licorish, Sherlock A.
name: MacDonell, Stephen G.
name: Clear, Tony
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Context: Post-release user feedback plays an integral role in improving software quality and informing new features. Given its growing importance, feedback concerning security enhancements is particularly noteworthy. In considering the rapid uptake of Android we have examined the scale and severity of Android security threats as reported by its stakeholders. Objective: We systematically mine Android issue logs to derive insights into stakeholder perceptions and experiences in relation to certain Android security issues. Method: We employed contextual analysis techniques to study issues raised regarding confidentiality and privacy in the last three major Android releases, considering covariance of stakeholder comments, and the level of consistency in user preferences and priorities. Results: Confidentiality and privacy concerns varied in severity, and were most prevalent over Jelly Bean releases. Issues raised in regard to confidentiality related mostly to access, user credentials and permission management, while privacy concerns were mainly expressed about phone locking. Community users also expressed divergent preferences for new security features, ranging from more relaxed to very strict. Conclusion: Strategies that support continuous corrective measures for both old and new Android releases would likely maintain stakeholder confidence. An approach that provides users with basic default security settings, but with the power to configure additional security features if desired, would provide the best balance for Android's wide cohort of stakeholders.
description: Conference paper, 10 pages, 3 figures, 7 tables
On Albanese torsors and the elementary obstruction
Creators: name: Wittenberg, Olivier
Publisher: name: arXiv
Year: 2006
Subjects: subject: Algebraic Geometry (math.AG)
subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: We show that the elementary obstruction to the existence of 0-cycles of degree 1 on an arbitrary variety X (over an arbitrary field) can be expressed in terms of the Albanese 1-motives associated with dense open subsets of X. Arithmetic applications are given.
Twinkle Twinkle Little Star: ET Wonders How You Are
Creators: name: Couperus, Andrew
name: Henry, Todd
name: Osten, Rachel
name: Jao, Wei-Chun
name: Vrijmoet, Eliot
name: RECONS Team
Publisher: name: Zenodo
Year: 2021
Subjects: Cool Stars on the main sequence
Very low mass stars

description: We present results of two projects examining the magnetic activity of nearby M dwarfs, a population of stars around which a plethora of planets is being revealed. As part of efforts by the REsearch Consortium On Nearby Stars (RECONS, www.recons.org) to characterize the Sun's neighbors, we explore stellar activity cycles in partially and fully convective M dwarfs using more than two decades of RECONS time series photometry at the CTIO/SMARTS 0.9m. We showcase light curves for several high-quality M dwarf stellar cycles in our data, with periods spanning roughly 5-30 years. These cycles have been analyzed utilizing a Gaussian Process-based method that maps periodic signals created simultaneously by long-term spot cycles and short-term rotation activity. Our second project examines magnetic activity and rotation rates for a sample of 36 M dwarf wide binaries that are made up of “twin” stars with nearly identical masses, ages, and compositions. Evolutionary models and conventional thinking suggest that such sets of twin stars should evolve nearly co-equally, resulting in similar levels of magnetic activity, and it is this assumption that we seek to test and constrain. We are targeting these systems with five ongoing observing campaigns, including short- and long-baseline optical photometry, speckle imaging, optical spectroscopy, and X-ray imaging via the Chandra X-ray observatory. We present preliminary results that indicate notable differences in magnetic activity between components for multiple twin pairs, thereby challenging our understanding of how such activity behaves. This work has been supported by the National Science Foundation through grants AST-0507711, AST-0908402, AST-1109445, AST-141206, and AST-1715551, as well as the SMARTS Consortium.
description: {"references": ["T. J. Henry et al. 2006, AJ, 132, 2360.", "T. J. Henry et al. 2018, AJ, 155, 265."]}