cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Phase Structure of the Random-Plaquette Z_2 Gauge Model: Accuracy Threshold for a Toric Quantum Memory
Creators: name: Ohno, Takuya
name: Arakawa, Gaku
name: Ichinose, Ikuo
name: Matsui, Tetsuo
Publisher: name: arXiv
Year: 2004
Subjects: subject: Quantum Physics (quant-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We study the phase structure of the random-plaquette Z_2 lattice gauge model in three dimensions. In this model, the "gauge coupling" for each plaquette is a quenched random variable that takes the value βwith the probability 1-p and -βwith the probability p. This model is relevant for the recently proposed quantum memory of toric code. The parameter p is the concentration of the plaquettes with "wrong-sign" couplings -β, and interpreted as the error probability per qubit in quantum code. In the gauge system with p=0, i.e., with the uniform gauge couplings β, it is known that there exists a second-order phase transition at a certain critical "temperature", T(\equiv β^{-1}) = T_c =1.31, which separates an ordered(Higgs) phase at TT_c. As p increases, the critical temperature T_c(p) decreases. In the p-T plane, the curve T_c(p) intersects with the Nishimori line T_{N}(p) at the certain point (p_c, T_{N}(p_c)). The value p_c is just the accuracy threshold for a fault-tolerant quantum memory and associated quantum computations. By the Monte-Carlo simulations, we calculate the specific heat and the expectation values of the Wilson loop to obtain the phase-transition line T_c(p) numerically. The accuracy threshold is estimated as p_c \simeq 0.033.
description: 24 pages, 14 figures, some clarifications
Contrast-Generated Illusory Motion as a Potential Diagnostic Tool
Creators: name: Nigam, Divya Laxmi
Publisher: name: American University
Year: 2023

description: The modulation of luminance contrast at an object’s edge can create the illusory appearance that a stationary object is moving continuously in a single direction (Shapiro and Flynn, submitted). Since this motion can occur when the edges are extremely narrow less than minimum of visual angle), it is conceivable that a continuous motion phenomenon can serve as a test of visual acuity and contrast sensitivity. We have examined the feasibility of using this form of motion as a non-invasive tool. The stimuli (Motion Diamond Stimulus-MDS) consists of physically stationary diamond shapes. By altering the temporal phase of the contrast of the diamond edges, the diamonds can appear to move upward, downward, left, down, outward, or inward. Experiment 1 measured psychometric functions for observer’s ability to report correct directions as a function, while Experiment 2 measured threshold functions with a larger range of parametric manipulation. These experiments depicted psychometric functions increasing monotonically with contrast modulation with functions being flatter for higher contrast gain. Maximal sensitivity occurred at edge length 4 (width of edge 4 min of visual angle) corroborating with past literature. Initial observations also indicate a correlation of threshold sensitivity on the MDS and clinical (Pelli Robson) sensitivity values.
O stars effective temperature and HII regions ionization parameter gradients in the Galaxy
Creators: name: Morisset, C.
Publisher: name: arXiv
Year: 2003
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Extensive photoionization model grids are computed for single star HII regions using stellar atmosphere models from the WM-basic code. Mid-IR emission line intensities are predicted and diagnostic diagrams of [NeIII]/[NeII] and [SIV]/[SIII] excitation ratio are build, taking into account the metallicities of both the star and the HII region. The diagrams are used in conjunction with galactic HII region observations obtained with the ISO Observatory to determine the effective temperature Teff of the exciting O stars and the mean ionization parameter U. Teff and U are found to increase and decrease, respectively, with the metallicity of the HII region represented by the [Ne/Ne_sol] ratio. No evidence is found for gradients of Teff or U with galactocentric distance Rgal. The observed excitation sequence with Rgal is mainly due to the effect of the metallicity gradient on the spectral ionizing shape, upon which the effect of an increase in Teff with Z is superimposed. We show that not taking properly into account the effect of metallicity on the ionizing shape of the stellar atmosphere would lead to an apparent decrease of Teff with Z and an increase of Teff with Rgal.
description: Accepted in ApJ
title: A case study of the statutory review system for older people in care homes in one local authority
Creators: name: Scourfield, Peter
Publisher: name: The Open University
Year: 2013

description: A case study of the statutory care home review system in one Local Authority. Statutory reviews of older people's care home placements are a legacy of the Community Care reforms of the 1990s in the UK. Using a mixed method approach this small-scale qualitative study was designed to explore how the statutory care home review system operated from the perspectives of its multiple stakeholders, but paying particular attention to the role played by the older person. The study also set out to assess the relevance and usefulness of the concept of 'street-level bureaucracy' as developed by Upsky (1980) in understanding how discretion was used in operating the system. It is argued that, in a context in which the adult social care sector has been 'transformed' by processes of privatisation, marketization and 'modernisation', the exercise of discretion is no longer the sale preserve of 'street-level bureaucrats' (front-line practitioners), but rather, it is dispersed among the various statutory and non-statutory actors in the review system, including managers, care home providers relatives and older -people themselves. The study revealed a system which had undergone multiple reorganisations in response to a variety of national and local policy initiatives and, against this context, was struggling to cope with the implementation of ambiguous and, often, conflicting policy agendas. Overall, the system was compromised by the need to balance ensuring care standards with the need to meet performance targets, often leading managers, practitioners and care providers to have to tolerate sub-optimal standards of care. It is proposed that, generally, in order for review actors to manage the tensions inherent in the system, it was helpful if the older person either voluntarily adopted or was steered into a position of passive participation in care reviews, suggesting that reviews can be as much a source of disempowerment for older people as empowerment.
A DISCRIMINANT ANALYSIS OF QUOTA/PERMIT SUPPLY CONTROL FOR BEEF IN SOUTH AFRICA
Creators: name: Elliott, M. B.
name: Nieuwoudt, W. L.
name: Darroch, M. A. G.
name: Elliott, M. B.
name: Nieuwoudt, W. L.
name: Darroch, M. A. G.
Publisher: name: Unknown
Year: 1987
Subjects: Agricultural and Food Policy
Livestock Production/Industries

description: Opinions of beef farmers regarding the quota/ permit beef scheme were studied in a stratified country-wide sample of 178 beef farmers. A discriminant and principal component analysis of factors related to the successful application of quotas/ permits was conducted focusing on the following variables: size, regularity in supply of livestock and percentage of gross farm income from non-beef enterprises. The study indicates that the method of restricting supply favours the large farmer who is a regular supplier of beef.
Topological Defect Networks for Fractons of all Types
Creators: name: Aasen, David
name: Bulmash, Daniel
name: Prem, Abhinav
name: Slagle, Kevin
name: Williamson, Dominic J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Fracton phases exhibit striking behavior which appears to render them beyond the standard topological quantum field theory (TQFT) paradigm for classifying gapped quantum matter. Here, we explore fracton phases from the perspective of defect TQFTs and show that topological defect networks---networks of topological defects embedded in stratified 3+1D TQFTs---provide a unified framework for describing various types of gapped fracton phases. In this picture, the sub-dimensional excitations characteristic of fractonic matter are a consequence of mobility restrictions imposed by the defect network. We conjecture that all gapped phases, including fracton phases, admit a topological defect network description and support this claim by explicitly providing such a construction for many well-known fracton models, including the X-Cube and Haah's B code. To highlight the generality of our framework, we also provide a defect network construction of a novel fracton phase hosting non-Abelian fractons. As a byproduct of this construction, we obtain a generalized membrane-net description for fractonic ground states as well as an argument that our conjecture implies no type-II topological fracton phases exist in 2+1D gapped systems. Our work also sheds light on new techniques for constructing higher order gapped boundaries of 3+1D TQFTs.
description: 19+10 pages, 25 figures
title: Genetic and environmental factors affecting Alzheimer's disease pathogenic mechanism: the role of sirtuins
Creators: name: Polito, Letizia
Publisher: name: The Open University
Year: 2012

description: Alzheimer's disease (AD) is the leading cause of senile dementia and the current lack of effective treatments provides a strong incentive for an improved therapeutic strategy. In particular, non-pharmacological treatments, such as calorie restriction (CR), were shown to be useful in delaying or preventing AD onset. This has given insight into the molecular pathways involved. Sirtuins (SIRT1-7) are evolutionary conserved enzymes that modulate life expectancy in simple organisms. In mammals, sirtuins are involved in pathways linked to age-related diseases, such as AD. In particular, they seem to be the molecular effectors of some beneficial effects mediated by external stimuli such as CR and physical activity. This thesis aims at investigating, for the first time, the involvement of all 7 sirtuins in AD. The relevance of sirtuin gene variation to AD risk was assessed by a combined mutation screening and case-control genetic study design. Sirtuin expression levels were also assessed in a transgenic mouse model of AD (APP23 mice) and within the application of a non-pharmacological approach (environmental enrichment-EE). Finally, the possible role of SIRT1 in AD pathogenesis was better elucidated through in vitro studies. Overall, in vitro studies confirmed the neuroprotective role of SIRT1 activator resveratrol in etiopathological contexts related to AD. Moreover, genetic studies have highlighted SIRT2 could be involved in modulating AD etiology. In particular, a common polymorphism in SIRT2 could be a weak genetic risk factor for AD. Finally, in vivo studies confirmed the beneficial effects of an EE protocol in delaying AD onset. However, despite sirtuin involvement in other environmental paradigms, no apparent modulation was registered under EE.
Peculiar roles of spins in the thermal conductivity of pure and doped La_{2}CuO_{4}: Comparison with CuGeO_{3}
Creators: name: Ando, Yoichi
name: Sun, X. F.
name: Takeya, J.
name: Komiya, Seiki
Publisher: name: arXiv
Year: 2003
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: In-plane and out-of-plane thermal conductivities (κ_{ab} and κ_{c}) are measured on single crystals of pure, 1%-hole-doped, and 1%-Zn-doped La_{2}CuO_{4}. The roles of magnons and the spin stripes in the heat transport in these samples are discussed. Comparison with the heat transport in CuGeO_{3}, which shows similar κ(T) behavior as that of La_{2}CuO_{4}, gives us a lesson of how the heat transport can probe the difference in the spin ground state.
description: 2 pages, 2 figures, invited paper at LT23 Conference
Mixed Integer Multiobjective Stochastic Optimization (MIMOSO)
Creators: name: Yulu, Huang
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 370599
subject: Geology not elsewhere classified
classificationCode: 370799
subject: Hydrology not elsewhere classified

description: The data and source codes of implementing the mixed integer multiobjective stochastic optimization method at the real-world case.
Экспериментальное исследование низкочастотной эффективности малогабаритного звукоизолирующего кожуха
Creators: name: В.Ю. Кирпичников
name: Кощеев А.П.
name: Добрынин Д.Г.
name: Л.Ф. Дроздова
Publisher: name: figshare
Year: 2020
Subjects: subject: 91301 Acoustics and Noise Control (excl. Architectural Acoustics)
subject: FOS: Mechanical engineering

description: Выполнены экспериментальные исследования звукоизлучения крышки малогабаритного звукоизолирующего кожуха на низших резонансных частотах изгибных колебаний при отсутствии и наличии на ней тонкого армированного вибропоглощающего покрытия. Показано, что облицовка крышки покрытием, содержащим полимерную пленку на основе поливинилацетата, приводит к повышению эффективности кожуха на частотах, где звукопоглощающие материалы с существенно бо́льшими толщинами не работают.
Accelerated expansion and the Goldstone ghost
Creators: name: Holdom, B.
Publisher: name: arXiv
Year: 2004
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: A vacuum instability due to a massless ghost in a hidden sector can lead to an effective equation of state for dark energy that changes smoothly from $w=-3/2$ at large redshifts, to $w\approx-1.2$ today, to $w=-1$ in the future. We discuss how this ghost can be the Goldstone boson of Lorentz symmetry breaking, and we find that this breaking in the hidden sector should occur at a scale below $\sim$10 KeV. The normal particles that are produced along with the ghosts are then predominantly neutrinos.
description: 12 pages, 2 figures, some improvement in discussion, published version
Formulating turbulence closures using sparse regression with embedded form invariance
Creators: name: Beetham, S.
name: Capecelatro, J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: A data-driven framework for formulation of closures of the Reynolds-Average Navier--Stokes (RANS) equations is presented. In recent years, the scientific community has turned to machine learning techniques to distill a wealth of highly resolved data into improved RANS closures. While the body of work in this area has primarily leveraged Neural Networks (NNs), we alternately leverage a sparse regression framework. This methodology has two important properties: (1) The resultant model is in a closed, algebraic form, allowing for direct physical inferences to be drawn and naive integration into existing computational fluid dynamics solvers, and (2) Galilean invariance can be guaranteed by thoughtful tailoring of the feature space. Our approach is demonstrated for two classes of flows: homogeneous free shear turbulence and turbulent flow over a wavy wall. This work demonstrates equivalent performance to that of modern NNs but with the added benefits of interpretability, increased ease-of-use and dissemination, and robustness to sparse training datasets.
Marketing strategy for railing materials made of small diameter Douglas fir
Creators: name: Ding, Mineral Yingxiang
name: Hsieh, David
Publisher: name: The University of British Columbia
Year: 2014

description: Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”
Contrast-Generated Illusory Motion as a Potential Diagnostic Tool
Creators: name: Nigam, Divya Laxmi
Publisher: name: ProQuest
Year: 2023
Subjects: classificationCode: 52
subject: Psychology
subject: FOS: Psychology

description: The modulation of luminance contrast at an object’s edge can create the illusory appearance that a stationary object is moving continuously in a single direction (Shapiro and Flynn, submitted). Since this motion can occur when the edges are extremely narrow less than minimum of visual angle), it is conceivable that a continuous motion phenomenon can serve as a test of visual acuity and contrast sensitivity. We have examined the feasibility of using this form of motion as a non-invasive tool. The stimuli (Motion Diamond Stimulus-MDS) consists of physically stationary diamond shapes. By altering the temporal phase of the contrast of the diamond edges, the diamonds can appear to move upward, downward, left, down, outward, or inward. Experiment 1 measured psychometric functions for observer’s ability to report correct directions as a function, while Experiment 2 measured threshold functions with a larger range of parametric manipulation. These experiments depicted psychometric functions increasing monotonically with contrast modulation with functions being flatter for higher contrast gain. Maximal sensitivity occurred at edge length 4 (width of edge 4 min of visual angle) corroborating with past literature. Initial observations also indicate a correlation of threshold sensitivity on the MDS and clinical (Pelli Robson) sensitivity values.
Precise determination of proton magnetic radius from electron scattering data
Creators: name: Alarcón, J. M.
name: Higinbotham, D. W.
name: Weiss, C.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We extract the proton magnetic radius from the high-precision electron-proton elastic scattering cross section data. Our theoretical framework combines dispersion analysis and chiral effective field theory and implements the dynamics governing the shape of the low-$Q^2$ form factors. It allows us to use data up to $Q^2\sim$ 0.5 GeV$^2$ for constraining the radii and overcomes the difficulties of empirical fits and $Q^2 \rightarrow 0$ extrapolation. We obtain a magnetic radius $r_M^p$ = 0.850 $\pm$0.001 (fit 68%) $\pm$0.010 (theory full range) fm, significantly different from earlier results obtained from the same data, and close to the extracted electric radius $r_E^p$ = 0.842 $\pm$0.002 (fit) $\pm$0.010 (theory) fm.
description: 5 pages, 2 figures
REMOTE CONTROLS ILLUSION: STRANGE INTERACTIONS ACROSS SPACE CANNOT BE EXPLAINED BY SIMPLE CONTRAST FILTERS
Creators: name: Hedjar, Laysa
Publisher: name: American University
Year: 2023

description: The visual system has separable visual encoding for luminance and for contrast modulation (Shapiro, 2008); the two dimensions can be represented with a luminance contrast vs. luminance plane. Here we use a contrast asynchrony paradigm to explore contextual effects on luminance contrast modulation: two identical rectangular bars (0.5x2.5 deg) have luminance levels that modulate at 2 Hz; when one bar is placed on a bright field and the other bar on a dark field, observers perceive the bars modulating in antiphase with each other and yet becoming light and dark at the same time. The antiphase perception corresponds to the change in contrast between the bars and their surrounds (a change along the contrast axis of the plane); the in-phase perception corresponds to the luminance modulation (a change along the luminance axis of the plane). We examine spatial interaction by adding bright rectangular (0.5x2.5 deg) flankers on both sides of the dark-field bar and dark flankers on both sides of the bright-field bar. Remarkably, flankers produce an in-phase appearance when separated from the bars by between 2' and 4' of visual angle, and produce antiphase appearance when they directly adjoin the bars or are separated by more than 8'. To estimate the dimensions of the spatial interaction, we parametrically adjust the size of the gap between bars and flankers and the length of the flankers. We attempt to account for the results with models based on rectified difference of Gaussian (DoG) filters and with rectified oriented difference of Gaussian (ODOG) filters. The models can account for the results when the flankers are the same height as bars, but are unable to account for the effects of increasing the flanker length. The models therefore suggest that the spatial interaction across distances requires more complex interactions of contrast filters.
THE INFLUENCE OF MORE EFFICIENT UTILISATION OF THE COMBINE ON THE PRODUCT MIX AND PROFITABILITY OF A SIMULATED CENTRAL SWARTLAND FARM
Creators: name: Van Der Westhuyzen, B.
name: Kleynhans, T. E.
name: Van Der Westhuyzen, B.
name: Kleynhans, T. E.
Publisher: name: Unknown
Year: 1988
Subjects: Production Economics
Research and Development/Tech Change/Emerging Technologies

description: In seeking greater efficiency and profit in farming, it is important to use the available capacity in power-driven machinery as fully as possible. In this investigation using a simulated central Swartland farm, the profitability was increased by eliminating under-utilised power-driven machinery, resulting in a reduction in mechanisation expenses. The change arising from this in the mechanised system has a further effect on the existing farming system in that wheat production, the most important branch, undergoes a structural change. Cost savings (working capital and interest) and the increased income from the expansion of the stock factor compensate for the loss of income caused by sowing less. The determining factor influencing profitability is, however, the saving in mechanisation expenses, which represent a fixed cost component.
Effect of Co-Mo catalyst preparation and CH4/H2 flow on carbon nanotube synthesis
Creators: name: Lobiak, Egor V.
name: Viktoriia R. Kuznetsova
name: Flahaut, Emmanuel
name: Okotrub, Alexander V.
name: Bulusheva, Lyubov G.
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Biochemistry
subject: Pharmacology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: Computational Biology

description: Supported Co-Mo catalysts with a given ratio of metals were prepared from polyoxomolybdate Mo12O28(μ2-OH)12{Со(H2O)3}4 using impregnation and combustion methods. Effects of the type of catalyst and the ratio and flow of methane and hydrogen gases on the structure of carbon nanotubes (CNTs) synthesized by catalytic chemical vapor deposition (CCVD) method were studied using transmission electron microscopy and Raman spectroscopy. The catalyst prepared by combustion method yielded mainly individualized CNTs, while the CNTs were highly entangled or bundled when impregnation method was used. In both cases, addition of hydrogen to methane led to reduction of the CNT yield. The samples synthesized using two different catalysts and the same CH4/H2 ratio and flow of gases were tested in electrochemical capacitors. A higher specific surface area of the CNTs grown over impregnation-prepared catalyst caused a better performance at scan rates from 2 to 1000 mV/s.
REMOTE CONTROLS ILLUSION: STRANGE INTERACTIONS ACROSS SPACE CANNOT BE EXPLAINED BY SIMPLE CONTRAST FILTERS
Creators: name: Hedjar, Laysa
Publisher: name: ProQuest
Year: 2023
Subjects: classificationCode: 52
subject: Psychology
subject: FOS: Psychology

description: The visual system has separable visual encoding for luminance and for contrast modulation (Shapiro, 2008); the two dimensions can be represented with a luminance contrast vs. luminance plane. Here we use a contrast asynchrony paradigm to explore contextual effects on luminance contrast modulation: two identical rectangular bars (0.5x2.5 deg) have luminance levels that modulate at 2 Hz; when one bar is placed on a bright field and the other bar on a dark field, observers perceive the bars modulating in antiphase with each other and yet becoming light and dark at the same time. The antiphase perception corresponds to the change in contrast between the bars and their surrounds (a change along the contrast axis of the plane); the in-phase perception corresponds to the luminance modulation (a change along the luminance axis of the plane). We examine spatial interaction by adding bright rectangular (0.5x2.5 deg) flankers on both sides of the dark-field bar and dark flankers on both sides of the bright-field bar. Remarkably, flankers produce an in-phase appearance when separated from the bars by between 2' and 4' of visual angle, and produce antiphase appearance when they directly adjoin the bars or are separated by more than 8'. To estimate the dimensions of the spatial interaction, we parametrically adjust the size of the gap between bars and flankers and the length of the flankers. We attempt to account for the results with models based on rectified difference of Gaussian (DoG) filters and with rectified oriented difference of Gaussian (ODOG) filters. The models can account for the results when the flankers are the same height as bars, but are unable to account for the effects of increasing the flanker length. The models therefore suggest that the spatial interaction across distances requires more complex interactions of contrast filters.
Dynamical I-V Characteristics of SNS Junctions
Creators: name: Spahr, Kevin
name: Graveline, Jonathan
name: Lupien, Chrustian
name: Aprili, Marco
name: Reulet, Bertrand
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We have probed the switching dynamics of the Josephson critical current of a superconducting weak link by measuring its voltage/current characteristics while applying an ac current bias in the range 1-200 MHz. The weak link between two Nb reservoirs is formed by an mesoscopic Al wire above its critical temperature. We observe a dynamical phase transition as a function of the frequency and amplitude of the ac current. While at low frequency the transition driven by increasing the current bias is well described by the standard Kramers theory, at high frequency the switching histograms become hysteretic and much narrower than expected by thermal fluctuations. The crossover frequency between the two regimes is set by the electron-phonon interaction rate in the normal metal.
description: 5 pages, 4 figures
Mass loss and the Eddington parameter: a new mass-loss recipe for hot and massive stars
Creators: name: Bestenlehner, Joachim M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Mass loss through stellar winds plays a dominant role in the evolution of massive stars. In particular the mass-loss rates of very massive stars (VMSs, $> 100\,M_{\odot}$) are highly uncertain. Such stars display Wolf-Rayet spectral morphologies (WNh) whilst on the main-sequence. Metal-poor VMSs are progenitors of gamma-ray bursts and pair instability supernovae. In this study we extended the widely used stellar wind theory by Castor, Abbott & Klein from the optically thin (O star) to the optically thick main-sequence (WNh) wind regime. In particular we modify the mass-loss rate formula in a way that we are able to explain the empirical mass-loss dependence on the Eddington parameter ($Γ_{\rm e}$). The new mass-loss recipe is suitable for incorporation into current stellar evolution models for massive and very massive stars. It makes verifiable predictions, namely how the mass-loss rate scales with metallicity and at which Eddington parameter the transition from optically thin O star to optically thick WNh star winds occurs. In the case of the star cluster R136 in the Large Magellanic Cloud we find in the optically thin wind regime $\dot{M} \propto Γ_{\rm e}^{3}$ while in the optically thick wind regime $\dot{M} \propto 1/ (1 - Γ_{\rm e})^{3.5}$. The transition from optically thin to optically thick winds occurs at $Γ_{\rm e, trans} \approx 0.47$. The transition mass-loss rate is $\log \dot{M}~(M_{\odot} \mathrm{yr}^{-1}) \approx -4.76 \pm 0.18$, which is in line with the prediction by Vink & Gräfener assuming a volume filling factor of $f_{\rm V} = 0.23_{-0.15}^{+0.40}$.
description: Accepted for publication in MNRAS, 9 pages, 5 figures
Detweiler's redshift invariant for extended bodies orbiting a Schwarzschild black hole
Creators: name: Bini, Donato
name: Geralico, Andrea
name: Steinhoff, Jan
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We compute the first-order self-force contribution to Detweiler's redshift invariant for extended bodies endowed with both dipolar and quadrupolar structure (with spin-induced quadrupole moment) moving along circular orbits on a Schwarzschild background. Our analysis includes effects which are second order in spin, generalizing previous results for purely spinning particles. The perturbing body is assumed to move on the equatorial plane, the associated spin vector being orthogonal to it. The metric perturbations are obtained by using a standard gravitational self-force approach in a radiation gauge. Our results are accurate through the 6.5 post-Newtonian order, and are shown to reproduce the corresponding post-Newtonian expression for the same quantity computed by using the available Hamiltonian from an effective field theory approach for the dynamics of spinning binaries.
description: 18 pages, revtex macros
Connecting Dualities and Machine Learning
Creators: name: Betzler, Philip
name: Krippendorf, Sven
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Machine Learning (cs.LG)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Machine Learning (stat.ML)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Dualities are widely used in quantum field theories and string theory to obtain correlation functions at high accuracy. Here we present examples where dual data representations are useful in supervised classification, linking machine learning and typical tasks in theoretical physics. We then discuss how such beneficial representations can be enforced in the latent dimension of neural networks. We find that additional contributions to the loss based on feature separation, feature matching with respect to desired representations, and a good performance on a `simple' correlation function can lead to known and unknown dual representations. This is the first proof of concept that computers can find dualities. We discuss how our examples, based on discrete Fourier transformation and Ising models, connect to other dualities in theoretical physics, for instance Seiberg duality.
description: 35 pages, 19 figures
OPTIMUM RESOURCE ALLOCATION: ESTIMATES FOR FRESH-MILK PRODUCERS IN NATAL
Creators: name: Gordijn, R. J.
name: Ortmann, G. F.
name: Gordijn, R. J.
name: Ortmann, G. F.
Publisher: name: Unknown
Year: 1988
Subjects: Livestock Production/Industries
Resource /Energy Economics and Policy

description: The allocation of some of the more important inputs in the production of fresh milk in three regions of Natal is assessed with the use of production functions. The marginal rate of substitution criteria is used to establish least cost combinations of concentrates and pastures in East Griqualand and in the Natal Midlands, and concentrates and forages in the Ixopo area. Estimates of profit-maximizing combinations of inputs are also presented for the three regions. The results indicate that fresh-milk farmers need to reassess their combinations of inputs to improve profits.
The CrMES scheme as an alternative to Importance Sampling: The tail regime of the order-parameter distribution
Creators: name: Malakis, Anastasios
name: Fytas, Nikolaos G.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We review the recently developed critical minimum energy-subspace (CrMES) technique. This scheme produces an immense optimization of popular algorithms, such as the Wang-Landau (WL) and broad histogram methods, by predicting the essential part of the energy space necessary for the estimation of the critical behavior and provides a new route of critical exponent estimation. A powerful and efficient CrMES entropic sampling scheme is proposed as an alternative to the traditional importance sampling methods. Utilizing the WL random walk process in the dominant energy subspace (CrMES-WL sampling) and using the WL approximation of the density of states and appropriate microcanonical estimators we determine the magnetic properties of the 2D Ising model. Updating $(E,M)$ histograms during the high level WL-iterations, we provide a comprehensive alternative scheme to the Metropolis algorithm and by applying this procedure we present a convincing analysis for the far tail regime of the order-parameter probability distribution.
description: 7 pages, 5 figures, Proceedings of the third NEXT Sigma Phi International Conference, Kolymbari, Greece (2005)
A MODEL FOR AGRICULTURAL COMMODITY R & D
Creators: name: Donovan, P. A.
name: Nieuwoudt, W. L.
name: Donovan, P. A.
name: Nieuwoudt, W. L.
Publisher: name: Unknown
Year: 1988
Subjects: Agricultural and Food Policy
Research and Development/Tech Change/Emerging Technologies

description: With constraints on State funds, consideration should be given to the private sector and agricultural commodity organisations undertaking their own R&D. Private organisations tend to adopt a goal-orientated research approach. Examples are the SASA Experiment Station and international private sector poultry research. A model is constructed based on data available from the SASA Experiment Station depicting a detailed functional breakdown of activities and costs of such a research programme
Constraining the properties of the proposed supermassive black hole system in 3c66b: Limits from pulsar timing
Creators: name: Jenet, Fredrick A.
name: Lommen, Andrea
name: Larson, Shane L.
name: Wen, Linqing
Publisher: name: arXiv
Year: 2003
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Data from long term timing observations of the radio pulsar PSR B1855+09 have been searched for the signature of Gravitational waves (G-waves) emitted by the proposed supermassive binary black hole system in 3C66B. For the case of a circular orbit, the emitted G-waves would generate detectable fluctuations in the pulse arrival times of PSR B1855+09. General expressions for the expected timing residuals induced by G-wave emission from a slowly evolving, eccentric, binary black hole system are derived here for the first time. These waveforms are used in a Monte-Carlo analysis in order to place limits on the mass and eccentricity of the proposed black hole system. The reported analysis also demonstrates several interesting features of a gravitational wave detector based on pulsar timing.
description: Submitted to ApJ Letters
One hundred SMUDGes in S-PLUS: ultra-diffuse galaxies flourish in the field
Creators: name: Barbosa, C. E.
name: Zaritsky, D.
name: Donnerstein, R.
name: Zhang, H.
name: Dey, A.
name: de Oliveira, C. Mendes
name: Sampedro, L.
name: Molino, A.
name: Costa-Duarte, M. V.
name: Coelho, P.
name: Cortesi, A.
name: Herpich, F. R.
name: Hernandez-Jimenez, J. A.
name: Santos-Silva, T.
name: Pereira, E.
name: Werle, A.
name: Overzier, R. A.
name: Fernandes, R. Cid
name: Castelli, A. V. Smith
name: Ribeiro, T.
name: Schoenell, W.
name: Kanaan, A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the first systematic study of the stellar populations of ultra-diffuse galaxies (UDGs) in the field, integrating the large area search and characterization of UDGs by the SMUDGes survey with the twelve-band optical photometry of the S-PLUS survey. Based on Bayesian modeling of the optical colors of UDGs, we determine the ages, metallicities and stellar masses of 100 UDGs distributed in an area of $\sim 330$ deg$^2$ in the Stripe 82 region. We find that the stellar masses and metallicities of field UDGs are similar to those observed in clusters and follow the trends previously defined in studies of dwarf and giant galaxies. However, field UDGs have younger luminosity-weighted ages than do UDGs in clusters. We interpret this result to mean that field UDGs have more extended star formation histories, including some that continue to form stars at low levels to the present time. Finally, we examine stellar population scaling relations that show that UDGs are, as a population, similar to other low-surface brightness galaxies.
description: 24 pages, 10 figures, accepted for Publication in ApJS
High Efficiency Carrier Multiplication in PbSe Nanocrystals: Implications for Solar Energy
Creators: name: Schaller, R. D.
name: Klimov, V. I.
Publisher: name: arXiv
Year: 2004
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We demonstrate for the first time that impact ionization (II) [the inverse of Auger recombination (AR)] occurs with very high efficiency in semiconductor nanocrystals (NCs). Interband optical excitation of PbSe NCs at low pump intensities, for which less than one exciton is initially generated per NC on average, results in the formation of two or more excitons (carrier multiplication) when pump photon energies are more than three times the NC band gap energy. Generation of multiexcitons from a single photon absorption event is observed to take place on an ultrafast (picosecond) timescale and occurs with up to 100% efficiency depending upon the excess energy of the absorbed photon. Efficient II in NCs can be used to considerably increase the power conversion efficiency of NC-based solar cells.
description: 16 pages total, 4 figures. This manuscipt has been accepted for publication in Physical Review Letters
Empowering Science through Digital Twins: The interTwin project
Creators: name: Manzi, Andrea
Publisher: name: Zenodo
Year: 2024

description: The interTwin project is an initiative funded by the European Union's Horizon Europe program. It aims to develop an interdisciplinary Digital Twin Engine (DTE), which is a versatile, open-source platform designed to integrate different Digital Twins (DTs) across various scientific domains. The DTE will help manage and simulate highly complex systems in fields like high-energy physics, astroparticle physics, radio astronomy, climate research, and environmental monitoring.The project focuses on creating a prototype of this engine through a collaborative process involving over 30 partner institutions, including technology and infrastructure providers. The poster will showcase the project first Sofware release and 2 prototype DTs for Climate Extreme Events and GW Astrophysics.
Among the Lost
Creators: name: Hunt, Wesley
name: Griffin, Gary
name: Douglass, John
Publisher: name: American University
Year: 2023

description: A masked murderer stalks a small medieval village. As the body count rises, several people try to discover the truth behind the killings: Lucian, a grave-robbing alchemist, who investigates while harboring a grudge against the very people he means to save. Ambrose, the pious priest, comforts his flock but believes the deaths to be God's wrath, cleansing the earth of sinners. Sir Merrick, a chivalrous knight, who arrives from afar and seeks out the killer for his own honor and glory. Gregor, the town's sheriff, who must deal not only with the killer, but the town's panicking and paranoid citizens as well. 2014 ASC Student Heritage Award Nominee.
Impact of magneto-rotational instability on grain growth in protoplanetary disks: I. Relevant turbulence properties
Creators: name: Gong, Munan
name: Ivlev, Alexei V.
name: Zhao, Bo
name: Caselli, Paola
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Turbulence in the protoplanetary disks induces collisions between dust grains, and thus facilitates grain growth. We investigate the two fundamental assumptions of the turbulence in obtaining grain collisional velocities -- the kinetic energy spectrum and the turbulence autocorrelation time -- in the context of the turbulence generated by the magneto-rotational instability (MRI). We carry out numerical simulations of the MRI as well as driven turbulence, for a range of physical and numerical parameters. We find that the convergence of the turbulence $α$-parameter does not necessarily imply the convergence of the energy spectrum. The MRI turbulence is largely solenoidal, for which we observe a persistent kinetic energy spectrum of $k^{-4/3}$. The same is obtained for solenoidal driven turbulence with and without magnetic field, over more than 1 dex near the dissipation scale. This power-law slope appears to be converged in terms of numerical resolution, and to be due to the bottleneck effect. The kinetic energy in the MRI turbulence peaks at the fastest growing mode of the MRI. In contrast, the magnetic energy peaks at the dissipation scale. The magnetic energy spectrum in the MRI turbulence does not show a clear power-law range, and is almost constant over approximately 1 dex near the dissipation scale. The turbulence autocorrelation time is nearly constant at large scales, limited by the shearing timescale, and shows a power-law drop close to $k^{-1}$ at small scales, with a slope steeper than that of the eddy crossing time. The deviation from the standard picture of the Kolmogorov turbulence with the injection scale at the disk scale height can potentially have a significant impact on the grain collisional velocities.
description: Accepted by ApJ
The shelled gastropods of the Solitary Islands Marine Park, northern New South Wales, Australia
Creators: name: Smith, Stephen D. A.
name: Peregrin, Laura S.
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Marine Biology
subject: Inorganic Chemistry
subject: FOS: Chemical sciences
subject: Plant Biology

description: Away from the major population centres, the biodiversity of Australia's shallow coastal marine waters is poorly known. The Tweed-Moreton Bioregion, covering northern New South Wales and south-east Queensland, is both a focus of marine conservation (with three marine parks), and research efforts to predict the effects of climate change through species range extensions and shifts in community composition. Here we provide the first comprehensive list of shallow-water (<30 m) shelled, gastropod macro-molluscs (>5 mm) from the Solitary Islands Marine Park, compiled from a range of sources, including field collections over a 30-year period to 2017. The Cypraeidae (50 spp.), Muricidae (47 spp.) and Conidae (32 spp.) were the most speciose families, accounting for 26% of the total inventory of 500 species from 77 families. A total of 143 species are recorded at their southern limit of distribution on Australia's east coast, most being rare, tropically affiliated taxa found at offshore island sites that receive more frequent contact with the southward-flowing East Australian Current. The inventory confirms the high biodiversity of the Solitary Islands region and the importance of ongoing conservation management.
Among the Lost
Creators: name: Hunt, Wesley
name: Griffin, Gary
name: Douglass, John
Publisher: name: American University (Washington, D.C.)
Year: 2023
Subjects: classificationCode: 3605
subject: Screen and digital media

description: A masked murderer stalks a small medieval village. As the body count rises, several people try to discover the truth behind the killings: Lucian, a grave-robbing alchemist, who investigates while harboring a grudge against the very people he means to save. Ambrose, the pious priest, comforts his flock but believes the deaths to be God's wrath, cleansing the earth of sinners. Sir Merrick, a chivalrous knight, who arrives from afar and seeks out the killer for his own honor and glory. Gregor, the town's sheriff, who must deal not only with the killer, but the town's panicking and paranoid citizens as well. 2014 ASC Student Heritage Award Nominee.
MEASURING PLOT SIZE EFFECTS ON COMMERCIALIZATION OF SMALL-SCALE AGRICULTURE IN KWAZULU: A DISCRIMINANT ANALYSIS APPROACH
Creators: name: Latt, E. A.
name: Nieuwoudt, W. L.
name: Latt, E. A.
name: Nieuwoudt, W. L.
Publisher: name: Unknown
Year: 1988
Subjects: Land Economics/Use
Production Economics

description: The aim of this study was to identify plot size effects on a broadly defined commercialization concept in three regions of rural KwaZulu using discriminant analysis. The division into small and large plot households was based on the mean plot size in each of the regions. A further division was made according to whether or not a household sold agricultural crops. Generally results indicated that the intensity of purchased requisites use was negatively related to plot size, crop sales tended to come from larger plots and households with crop sales tended to make more use of improved technology such as tractor hire and fertilizers. These results compared favourably with those of studies making use of alternative methods.