cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Magnetic Flux Leakage Method: Large-Scale Approximation
Creators: name: Pimenova, Anastasiya V.
name: Goldobin, Denis S.
name: Levesley, Jeremy
name: Ivantsov, Andrey O.
name: Elkington, Peter
name: Bacciarelli, Mark
Publisher: name: arXiv
Year: 2015
Subjects: subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: We consider the application of the magnetic flux leakage (MFL) method to the detection of defects in ferromagnetic (steel) tubulars. The problem setup corresponds to the cases where the distance from the casing and the point where the magnetic field is measured is small compared to the curvature radius of the undamaged casing and the scale of inhomogeneity of the magnetic field in the defect-free case. Mathematically this corresponds to the planar ferromagnetic layer in a uniform magnetic field oriented along this layer. Defects in the layer surface result in a strong deformation of the magnetic field, which provides opportunities for the reconstruction of the surface profile from measurements of the magnetic field. We deal with large-scale defects whose depth is small compared to their longitudinal sizes---these being typical of corrosive damage. Within the framework of large-scale approximation, analytical relations between the casing thickness profile and the measured magnetic field can be derived.
description: 12 pages, 3 figures
The Internet with Privacy Policies: Measuring The Web Upon Consent
Creators: name: Jha, Nikhil
name: Trevisan, Martino
name: Vassio, Luca
name: Mellia, Marco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: To protect users' privacy, legislators have regulated the usage of tracking technologies, mandating the acquisition of users' consent before collecting data. Consequently, websites started showing more and more consent management modules -- i.e., Privacy Banners -- the visitors have to interact with to access the website content. They challenge the automatic collection of Web measurements, primarily to monitor the extensiveness of tracking technologies but also to measure Web performance in the wild. Privacy Banners in fact limit crawlers from observing the actual website content. In this paper, we present a thorough measurement campaign focusing on popular websites in Europe and the US, visiting both landing and internal pages from different countries around the world. We engineer Priv-Accept, a Web crawler able to accept the privacy policies, as most users would do in practice. This let us compare how webpages change before and after. Our results show that all measurements performed not dealing with the Privacy Banners offer a very biased and partial view of the Web. After accepting the privacy policies, we observe an increase of up to 70 trackers, which in turn slows down the webpage load time by a factor of 2x-3x.
description: ACM Transactions on the Web (2022)
Effect of three-body forces on response functions in infinite neutron matter
Creators: name: Davesne, D.
name: Holt, J. W.
name: Pastore, A.
name: Navarro, J.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We study the impact of three-body forces on the response functions of cold neutron matter. These response functions are determined in the random phase approximation (RPA) from a residual interaction expressed in terms of Landau parameters. Special attention is paid to the non-central part, including all terms allowed by the relevant symmetries. Using Landau parameters derived from realistic nuclear two- and three-body forces grounded in chiral effective field theory, we find that the three-body term has a strong impact on the excited states of the system and in the static and long-wavelength limit of the response functions for which a new exact formula is established.
Force Correlations in Disordered Magnets
Creators: name: ter Burg, Cathelijne
name: Bohn, Felipe
name: Durin, Gianfranco
name: Sommer, Rubem Luis
name: Wiese, Kay Joerg
Publisher: name: arXiv
Year: 2021
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We present a proof of principle for the validity of the functional renormalization group, by measuring the force correlations in Barkhausen-noise experiments. Our samples are soft ferromagnets in two distinct universality classes, differing in the range of spin interactions, and the effects of eddy currents. We show that the force correlations have a universal form predicted by the functional renormalization group, distinct for short-range and long-range elasticity, and mostly independent of eddy currents. In all cases correlations grow linearly at small distances, as in mean-field models, but in contrast to the latter are bounded at large distances. As a consequence, avalanches are anti-correlated. We derive bounds for these anti-correlations, which are saturated in the experiments, showing that the multiple domain walls in our samples effectively behave as a single wall.
description: 11 pages, 21 figures. v3 close to the published version
Reconstructing the projected gravitational potential of Abell 1689 from X-ray measurements
Creators: name: Tchernin, Celine
name: Majer, Charles L.
name: Meyer, Sven
name: Sarli, Eleonora
name: Eckert, Dominique
name: Bartelmann, Matthias
Publisher: name: arXiv
Year: 2015
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Context. Galaxy clusters can be used as cosmological probes, but to this end, they need to be thoroughly understood. Combining all cluster observables in a consistent way will help us to understand their global properties and their internal structure. Aims. We provide proof of the concept that the projected gravitational potential of galaxy clusters can directly be reconstructed from X-ray observations. We also show that this joint analysis can be used to locally test the validity of the equilibrium assumptions in galaxy clusters. Methods. We used a newly developed reconstruction method, based on Richardson-Lucy deprojection, that allows reconstructing projected gravitational potentials of galaxy clusters directly from X-ray observations. We applied this algorithm to the well-studied cluster Abell 1689 and compared the gravitational potential reconstructed from X-ray observables to the potential obtained from gravitational lensing measurements. [...] Results. Assuming spherical symmetry and hydrostatic equilibrium, the potentials recovered from gravitational lensing and from X-ray emission agree very well beyond 500 kpc. Owing to the fact that the Richardson-Lucy deprojection algorithm allows deprojecting each line of sight independently, this result may indicate that non-gravitational effects and/or asphericity are strong in the central regions of the clusters. Conclusions. We demonstrate the robustness of the potential reconstruction method based on the Richardson-Lucy deprojection algorithm and show that gravitational lensing and X-ray emission lead to consistent gravitational potentials. Our results illustrate the power of combining galaxy-cluster observables in a single, non-parametric, joint reconstruction of consistent cluster potentials that can be used to locally constrain the physical state of the gas.
description: 8 pages, 4 figures. Accepted in A&A
The Recovery of Anterograde and Retrograde Amnesia following Traumatic Brain Injury
Creators: name: CAROLINE MAY ROBERTS
Publisher: name: Figshare
Year: 2018
Subjects: subject: 170101 Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology)
subject: FOS: Psychology

description: This thesis examines the recovery of anterograde (post-injury) and retrograde (pre-injury) memories following moderate to severe traumatic brain injury. The findings suggest that retrograde autobiographical memory deficits are common in this population, and that broadening focus to consider life before the injury contributes valuable information with respect to the mechanisms underlying memory recovery and an individual’s ability to reintegrate into the community.
A Free-Form Prediction for the Reappearance of Supernova Refsdal in the Hubble Frontier Fields Cluster MACSJ1149.5+2223
Creators: name: Diego, Jose M.
name: Broadhurst, Tom
name: Chen, Cuncheng
name: Lim, Jeremy
name: Zitrin, Adi
name: Chan, Brian
name: Coe, Dan
name: Ford, Holland C.
name: Lam, Daniel
name: Zheng, Wei
Publisher: name: arXiv
Year: 2015
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The massive cluster MACSJ1149.5+2223(z=0.544) displays five very large lensed images of a well resolved spiral galaxy at $z_{\rm spect}=1.491$. It is within one of these images that the first example of a multiply-lensed supernova has been detected recently as part of the Grism Lens-Amplified Survey from Space. The depth of this data also reveals many HII regions within the lensed spiral galaxy which we identify between the five counter-images. Here we expand the capability of our free-form method to incorporate these HII regions locally, with other reliable lensed galaxies added for a global solution. This improved accuracy allows us to estimate when the Refsdal supernova will appear within the other lensed images of the spiral galaxy to an accuracy of $\sim$ 7\%. We predict this supernova will reappear in one of the counter-images (RA=11:49:36.025, DEC=+22:23:48.11, J2000) and on November 1$^{st}$ 2015 (with an estimated error of $\pm$ 25 days) it will be at the same phase as it was when it was originally discovered, offering a unique opportunity to study the early phases of this supernova and to examine the consistency of the mass model and the cosmological model that have an impact on the time delay prediction.
description: 12 images, 11 pages. Mateches accepted version in MNRAS. MNRAS in press
Image Captioning for Effective Use of Language Models in Knowledge-Based Visual Question Answering
Creators: name: Salaberria, Ander
name: Azkune, Gorka
name: de Lacalle, Oier Lopez
name: Soroa, Aitor
name: Agirre, Eneko
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Integrating outside knowledge for reasoning in visio-linguistic tasks such as visual question answering (VQA) is an open problem. Given that pretrained language models have been shown to include world knowledge, we propose to use a unimodal (text-only) train and inference procedure based on automatic off-the-shelf captioning of images and pretrained language models. Our results on a visual question answering task which requires external knowledge (OK-VQA) show that our text-only model outperforms pretrained multimodal (image-text) models of comparable number of parameters. In contrast, our model is less effective in a standard VQA task (VQA 2.0) confirming that our text-only method is specially effective for tasks requiring external knowledge. In addition, we show that increasing the language model's size improves notably its performance, yielding results comparable to the state-of-the-art with our largest model, significantly outperforming current multimodal systems, even though augmented with external knowledge. Our qualitative analysis on OK-VQA reveals that automatic captions often fail to capture relevant information in the images, which seems to be balanced by the better inference ability of the text-only language models. Our work opens up possibilities to further improve inference in visio-linguistic tasks
description: Under review. 25 pages with 4 figures
title: Advanced control schemes for wind power plants and renewable energy-based islanded microgrids
Creators: name: Shabbir, Md Nasmus Sakib Khan
Publisher: name: Memorial University of Newfoundland
Year: 2021

description: Renewable energy sources are increasingly integrated in power grids, creating significant challenges for control and system operation. Among various renewable energy sources, wind power is one of the dominant forms, mainly generated from large-scale transmission-connected wind power plants (WPPs). The grid-connected WPPs are required to follow grid codes to maintain a predefined power factor range under normal operation and supply required reactive power under faulty conditions. To meet grid code requirements, a WPP control architecture is developed in this thesis. The control system consists of a central WPP controller and a local wind turbine generator (WTG) controller, both operate in the voltage control mode. Therefore, the controller can respond faster and is robust to communication failures. Under normal operating conditions, the proposed controller regulates the WPP’s operation within its steady-state reactive power capability and meets the power factor limits. Under faulty conditions, the controller forces the WPP to its maximum capability to contribute more reactive power support to the grid. Two mathematical models representing the steady-state and maximum reactive power capability of the WPP are developed through regression and analytic approaches, respectively. In the second part of the thesis, a model predictive control (MPC)-based distributed generation (DG) controller is proposed to regulate the voltage and frequency at the point of common coupling (PCC) in an islanded microgrid. A data-driven input-output Box-Jenkins polynomial predictive model for DG control is developed using the Gauss-Newton-based nonlinear least square method with the prediction optimization focus. The model inputs are direct- and quadrature-axis components of the control signal, and the model outputs are deviations of the voltage and frequency from their nominal values at the PCC. The proposed MPC controller operates using the PCC data and does not require the microgrid’s central controllers or DG-to-DG communication networks. It can effectively compensate voltage and frequency deviations at the PCC and ensure proportional reactive power sharing among DGs without a secondary controller and a virtual impedance loop. The integrated Kalman filter in the MPC structure enables a robust controller design when subjected to impedance variations and measurement noises.
On the Dynamics of Political Discussions on Instagram: A Network Perspective
Creators: name: Ferreira, Carlos H. G.
name: Murai, Fabricio
name: Silva, Ana P. C.
name: Almeida, Jussara M.
name: Trevisan, Martino
name: Vassio, Luca
name: Mellia, Marco
name: Drago, Idilio
Publisher: name: arXiv
Year: 2021
Subjects: subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences

description: Instagram has been increasingly used as a source of information especially among the youth. As a result, political figures now leverage the platform to spread opinions and political agenda. We here analyze online discussions on Instagram, notably in political topics, from a network perspective. Specifically, we investigate the emergence of communities of co-commenters, that is, groups of users who often interact by commenting on the same posts and may be driving the ongoing online discussions. In particular, we are interested in salient co-interactions, i.e., interactions of co-commenters that occur more often than expected by chance and under independent behavior. Unlike casual and accidental co-interactions which normally happen in large volumes, salient co-interactions are key elements driving the online discussions and, ultimately, the information dissemination. We base our study on the analysis of 10 weeks of data centered around major elections in Brazil and Italy, following both politicians and other celebrities. We extract and characterize the communities of co-commenters in terms of topological structure, properties of the discussions carried out by community members, and how some community properties, notably community membership and topics, evolve over time. We show that communities discussing political topics tend to be more engaged in the debate by writing longer comments, using more emojis, hashtags and negative words than in other subjects. Also, communities built around political discussions tend to be more dynamic, although top commenters remain active and preserve community membership over time. Moreover, we observe a great diversity in discussed topics over time: whereas some topics attract attention only momentarily, others, centered around more fundamental political discussions, remain consistently active over time.
Additional file 1 of Estimated projection of incidence and mortality of alcohol-related liver disease in China from 2022 to 2040: a modeling study
Creators: name: Wu, Meiyu
name: Qin, Shuxia
name: Tan, Chongqing
name: Li, Sini
name: Xie, Ouyang
name: Wan, Xiaomin
Publisher: name: figshare
Year: 2023
Subjects: subject: Medicine
subject: Biotechnology
subject: Chemical Sciences not elsewhere classified
subject: Sociology
subject: FOS: Sociology
subject: Marine Biology
subject: Science Policy

description: Additional file 1. More details of the model construction and input parameters. Table S1. Baseline data source summary for the model. Table S2. Key parameters for the model. Fig S1. Comparison of model predictions and GBD reported values. Fig S2. The number and prevalence of excessive alcohol consumption for all projected scenarios.
Time crystal and chaos in the hybrid atom-optomechanics system
Creators: name: Xu, Xingran
name: Krisnanda, Tanjung
name: Liew, Timothy C. H.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We consider atoms in two different periodic potentials induced by different lasers, one of which is coupled to a mechanical membrane via radiation pressure force. The atoms are intrinsically two-level systems that can absorb or emit photons, but the dynamics of their position and momentum are treated classically. On the other hand, the membrane, the cavity field, and the intrinsic two-level atoms are treated quantum mechanically. We show that the mean excitation of the three systems can be stable, periodically oscillating, or in a chaotic state depending on the strength of the coupling between them. We define regular, time crystal, and chaotic phases, and present a phase diagram where the three phases can be achieved by manipulating the field-membrane and field-atom coupling strengths. The first and second-order correlation functions in different phases are also calculated, which can be observed in experiments. Our proposal offers a new way to generate and tune time crystal and chaotic phases in a well-established atom-optomechanics system.
Cognitive predictors of treatment outcomes in individuals with methamphetamine use disorder
Creators: name: ADAM JAMES RUBENIS
Publisher: name: Figshare
Year: 2018
Subjects: subject: 170205 Neurocognitive Patterns and Neural Networks
subject: FOS: Psychology

description: Treatment outcomes are consistently poor for individuals recovering from methamphetamine dependence and may be related to cognitive deficits documented in this population. This thesis examines how cognitive functioning at treatment entry predicts a range of outcomes six weeks later. Specifically, poorer working memory predicts higher rates of methamphetamine use, higher impulsivity predicts less improvement in social and psychological functioning, and poorer sustained attention predicts less improvement in treatment motivation. Rehabilitating these cognitive deficits early in treatment may improve outcomes in this population and reduce the social and economic burden associated with methamphetamine use.
Image Subtraction in Fourier Space
Creators: name: Hu, Lei
name: Wang, Lifan
name: Chen, Xingzhuo
name: Yang, Jiawen
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Image subtraction is essential for transient detection in time-domain astronomy. The point spread function (PSF), photometric scaling, and sky background generally vary with time and across the field-of-view for imaging data taken with ground-based optical telescopes. Image subtraction algorithms need to match these variations for the detection of flux variability. An algorithm that can be fully parallelized is highly desirable for future time-domain surveys. Here we show the Saccadic Fast Fourier Transform (SFFT) algorithm for image differencing. SFFT uses $δ$-function basis for kernel decomposition, and the image subtraction is performed in Fourier Space. This brings about a remarkable improvement of computational performance of about an order of magnitude compared to other published image subtraction codes. SFFT can accommodate the spatial variations in wide-field imaging data, including PSF, photometric scaling, and sky background. However, the flexibility of the $δ$-function basis may also make it more prone to overfitting. The algorithm has been tested extensively in real astronomical data taken by a variety of telescopes. Moreover, the SFFT code allows for the spatial variations of the PSF and sky background to be fitted by spline functions.
description: 25 pages, 14 figures, 9 tables, Accepted for publication in ApJ, comprehensive comparisons added, software available at https://github.com/thomasvrussell/sfft
Control of active polymeric filaments by chemically-powered nanomotors
Creators: name: Qiao, Lilan
name: Kapral, Raymond
Publisher: name: arXiv
Year: 2021
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Active materials with distinctive nonequilibrium properties have diverse materials science applications. Active systems are common in living matter, such as the filament network in the cell that is activated by molecular motors, and in materials science as exemplified by hydrogels activated by chemical reactions. Here we describe another class of active polymeric filament systems where the filaments are activated by embedded chemically-powered nanomotors that have catalytic and noncatalytic parts. Chemical reactions on the catalytic surfaces produce forces that act on the polymeric filaments. By changing the nonequilibrium conditions these forces can be made to change sign and thereby compress or expand the filaments. The embedded motors provide both the source of activity and the means to control the filament conformational structure. As an example of control, we show that oscillatory variations of the chemical constraints yield gel-like networks that oscillate between expanded or compressed forms, much like those of hydrogels.
description: 8 pages, 7 figures
A Focused, Hard X-ray Look at Arp 299 with NuSTAR
Creators: name: Ptak, A.
name: Hornschemeier, A.
name: Zezas, A.
name: Lehmer, B.
name: Yukita, M.
name: Wik, D.
name: Antoniou, V.
name: Argo, M. K.
name: Ballo, L.
name: Bechtol, K.
name: Boggs, S.
name: Della Ceca, R.
name: Christensen, F. E.
name: Craig, W. W.
name: Hailey, C. J.
name: Harrison, F. A.
name: Krivonos, R.
name: Maccarone, T. J.
name: Stern, D.
name: Tatum, M.
name: Venters, T.
name: Zhang, W. W.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report on simultaneous observations of the local starburst system Arp 299 with NuSTAR and Chandra, which provides the first resolved images of this galaxy up to energies of ~ 45 keV. Fitting the 3-40 keV spectrum reveals a column density of $N_{\rm H}$ ~ 4 x10^{24} cm^{-2}, characteristic of a Compton-thick AGN, and a 10-30 keV luminosity of 1.2x 10^{43} ergs s^{-1}. The hard X-rays detected by NuSTAR above 10 keV are centered on the western nucleus, Arp 299-B, which previous X-ray observations have shown to be the primary source of neutral Fe-K emission. Other X-ray sources, including Arp 299-A, the eastern nucleus which is also thought to harbor an AGN, as well as X-ray binaries, contribute $\lesssim 10%$ to the 10-20 keV emission from the Arp 299 system. The lack of significant emission above 10 keV other than that attributed to Arp 299-B suggests that: a) any AGN in Arp 299-A must be heavily obscured ($N_{\rm H}$ > 10^{24} cm^{-2}) or have a much lower luminosity than Arp 299-B and b) the extranuclear X-ray binaries have spectra that cut-off above ~10 keV. Such soft spectra are characteristic of ultraluminous X-ray (ULX) sources observed to date by NuSTAR.
description: 9 pages; accepted for publication in Astrophysical Journal
More bang for buck in global HIV resource allocation
Creators: name: SHERRIE LYNNE KELLY
Publisher: name: Figshare
Year: 2018
Subjects: subject: 140303 Economic Models and Forecasting
subject: FOS: Economics and business
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: 111799 Public Health and Health Services not elsewhere classified

description: The Optima HIV model was applied to assess the impact of scale-up of HIV interventions in Swaziland and estimate the cost per new infection and AIDS-related death averted, as well as to optimize spending for achieving the HIV strategic plan for Armenia and determine coverage required to warrant increased funding for migrant programs. The model was then expanded to generate regional and global optimal resource allocations to minimize new HIV infections from national and subnational HIV resource allocation optimizations to address research and public health HIV questions and to provide evidence for improvements in HIV resource allocation on the global scale.
Supplemental Materials from Of Popsicles and Crackers: When Spatio-Temporal Memory is Not Integrated into Children’s Decision-Making
Creators: name: Coughlin, Christine
name: Karjack, Sabrina
name: Pospisil, Jacqueline
name: Lee, Joshua
name: Ghetti, Simona
Publisher: name: The Royal Society
Year: 2024
Subjects: classificationCode: 310901
subject: Animal behaviour

description: Popsicle_SM_R1_Clean.pdf
Physical and chemical differentiation of the luminous star-forming region W49A - Results from the JCMT Spectral Legacy Survey
Creators: name: Nagy, Z.
name: van der Tak, F. F. S.
name: Fuller, G. A.
name: Plume, R.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The massive and luminous star-forming region W49A is a well known Galactic candidate to probe the physical conditions and chemistry similar to those expected in external starburst galaxies. We aim to probe the physical and chemical structure of W49A on a spatial scale of ~0.8 pc based on the JCMT Spectral Legacy Survey, which covers the frequency range between 330 and 373 GHz. The wide 2x2 arcminutes field and the high spectral resolution of the HARP instrument on JCMT provides information on the spatial structure and kinematics of the cloud. For species where multiple transitions are available, we estimate excitation temperatures and column densities. We detected 255 transitions corresponding to 60 species in the 330-373 GHz range at the center position of W49A. Excitation conditions can be probed for 16 molecules. The chemical composition suggests the importance of shock-, PDR-, and hot core chemistry. Many molecular lines show a significant spatial extent across the maps including high density tracers (e.g. HCN, HNC, CS, HCO+) and tracers of UV-irradiation (e.g. CN and C2H). Large variations are seen between the sub-regions with mostly blue-shifted emission toward the Eastern tail, mostly red-shifted emission toward the Northern clump, and emission peaking around the expected source velocity toward the South-west clump. A comparison of column density ratios of characteristic species observed toward W49A to Galactic PDRs suggests that while the chemistry toward the W49A center is driven by a combination of UV-irradiation and shocks, UV-irradiation dominates for the Northern Clump, Eastern tail, and South-west clump regions. A comparison to a starburst galaxy and an AGN suggests similar C2H, CN, and H2CO abundances (with respect to the dense gas tracer 34CS) between the ~0.8 pc scale probed for W49A and the >1 kpc regions in external galaxies with global star-formation.
description: Proposed for acceptance in A&A, abstract abridged
Diffusion of Ga adatoms at the surface of GaAs(001) c(4x4) $α$ and $β$ reconstructions
Creators: name: Mińkowski, Marcin
name: Załuska-Kotur, Magdalena A.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Diffusion of Ga adatom at the As rich, low temperature c(4$\times$4) reconstructions of GaAs(001) surface is analyzed. We use known energy landscape for the motion of Ga adatom at two different $α$ and $β$ surface phases to calculate diffusion tensor by means of the variational approach. Diffusion coefficient describes the character of low density adatom system motion at the surface. The resulting expressions allow to identify main paths of an adatom diffusion and to calculate an activation energy of this process. It is shown that diffusion at the $α$ surface is slower and more anisotropic than this for the $β$ surface.
de Sitter space and extremal surfaces for spheres
Creators: name: Narayan, K.
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Following arXiv:1501.03019 [hep-th], we study de Sitter space and spherical subregions on a constant boundary Euclidean time slice of the future boundary in the Poincare slicing. We show that as in that case, complex extremal surfaces exist here as well: for even boundary dimensions, we isolate the universal coefficient of the logarithmically divergent term in the area of these surfaces. There are parallels with analytic continuation of the Ryu-Takayanagi expressions for holographic entanglement entropy in $AdS/CFT$. We then study the free energy of the dual Euclidean CFT on a sphere holographically using the $dS/CFT$ dictionary with a dual de Sitter space in global coordinates, and a classical approximation for the wavefunction of the universe. For even dimensions, we again isolate the coefficient of the logarithmically divergent term which is expected to be related to the conformal anomaly. We find agreement including numerical factors between these coefficients.
description: Latex, 14pgs, v3: published version, more detailed clarifications added
Noise-Produced Patterns in Images Constructed from Magnetic Flux Leakage Data
Creators: name: Pimenova, Anastasiya V.
name: Goldobin, Denis S.
name: Levesley, Jeremy
name: Elkington, Peter
name: Bacciarelli, Mark
Publisher: name: arXiv
Year: 2015
Subjects: subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Magnetic flux leakage measurements help identify the position, size and shape of corrosion-related defects in steel casings used to protect boreholes drilled into oil and gas reservoirs. Images constructed from magnetic flux leakage data contain patterns related to noise inherent in the method. We investigate the patterns and their scaling properties for the case of delta-correlated input noise, and consider the implications for the method's ability to resolve defects. The analytical evaluation of the noise-produced patterns is made possible by model reduction facilitated by large-scale approximation. With appropriate modification, the approach can be employed to analyze noise-produced patterns in other situations where the data of interest are not measured directly, but are related to the measured data by a complex linear transform involving integrations with respect to spatial coordinates.
description: 11 pages, 2 figures
A simulation sandbox to compare fixed-route, semi-flexible-transit, and on-demand microtransit system designs
Creators: name: Yoon, Gyugeun
name: Chow, Joseph Y. J.
name: Rath, Srushti
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: With advances in emerging technologies, options for operating public transit services have broadened from conventional fixed-route service through semi-flexible service to on-demand microtransit. Nevertheless, guidelines for deciding between these services remain limited in the real implementation. An open-source simulation sandbox is developed that can compare state-of-the-practice methods for evaluating between the different types of public transit operations. For the case of the semi-flexible service, the Mobility Allowance Shuttle Transit (MAST) system is extended to include passenger deviations. A case study demonstrates the sandbox to evaluate and existing B63 bus route in Brooklyn, NY and compares its performance with the four other system designs spanning across the three service types for three different demand scenarios.
Non-Kahler Resolved Conifold, Localized Fluxes in M-Theory and Supersymmetry
Creators: name: Dasgupta, Keshav
name: Emelin, Maxim
name: McDonough, Evan
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The known supergravity solution for wrapped D5-branes on the two-cycle of a Kahler resolved conifold is in general ISD but not supersymmetric, with the supersymmetry being broken by the presence of (1, 2) fluxes. However if we allow a non-Kahler metric on the resolved conifold, supersymmetry can easily be restored. The vanishing of the (1, 2) fluxes here corresponds to, under certain conformal rescalings of the metric, the torsion class constraints. We construct a class of explicit non-Kahler metrics on the resolved conifold satisfying the constraints. All this can also be studied from M-theory, where the fluxes and branes become non-localized G-fluxes on deformed Taub-NUT spaces. Interestingly, the gauge fluctuations on the wrapped D5-branes appear now as localized G-fluxes in M-theory. These localized fluxes are related to certain harmonic two-forms that are normalizable. We compute these forms explicitly and discuss how new constraints on the geometry of the non-Kahler manifolds may appear from M-theory considerations.
description: 40 pages, no figures, LaTeX JHEP format
Supplementary Information from Effects of Visual Diet on Colour Discrimination and Preference.
Creators: name: Skelton, Alice
name: Maule, John
name: Floyd, Simeon
name: Wozniak, Beata
name: Majid, Asifa
name: Bosten, Jenny
name: Franklin, Anna
Publisher: name: The Royal Society
Year: 2024
Subjects: classificationCode: 320999
subject: Neurosciences not elsewhere classified

description: Further information on method and results.
title: In situ TEM studies of relaxation dynamics and crystal nucleation in thin film nanoglasses
Creators: name: Voigt, Hendrik
name: Rigoni, Aaron
name: Boltynjuk, Evgeniy
name: Rösner, Harald
name: Hahn, Horst
name: Wilde, Gerhard
Publisher: name: University of Muenster, Institutional Repository MIAMI
Year: 2024
Subjects: subject: 530 Physics

description: Crystallization processes of glass-glass interfaces in sputtered CuZr thin film nanoglasses were directly studied using in situ heating experiments in a transmission electron microscope (TEM). By combining the in situ technique with a sophisticated symmetry analysis based on nanobeam diffraction patterns (NBDP) and electron correlation microscopy (ECM) to capture the relaxation dynamics in the nanoglass, correlations between excess volume and nucleation kinetics are attained on a microscopic scale. Particularly, glass-glass interfaces with their increased excess volume promote the onset of crystal nucleation.
description: Finanziert durch den Open-Access-Publikationsfonds der Universität Münster.
NOMA-Aided Joint Radar and Multicast-Unicast Communication Systems
Creators: name: Mu, Xidong
name: Liu, Yuanwei
name: Guo, Li
name: Lin, Jiaru
name: Hanzo, Lajos
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Theory (cs.IT)
subject: Signal Processing (eess.SP)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: The novel concept of non-orthogonal multiple access (NOMA) aided joint radar and multicast-unicast communication (Rad-MU-Com) is investigated. Employing the same spectrum resource, a multi-input-multi-output (MIMO) dual-functional radar-communication (DFRC) base station detects the radar-centric users (R-user), while transmitting mixed multicast-unicast messages both to the R-user and to the communication-centric user (C-user). In particular, the multicast information is intended for both the R- and C-users, whereas the unicast information is only intended for the C-user. More explicitly, NOMA is employed to facilitate this double spectrum sharing, where the multicast and unicast signals are superimposed in the power domain and the superimposed communication signals are also exploited as radar probing waveforms. First, a beamformer-based NOMA-aided joint Rad-MU-Com framework is proposed for the system having a single R-user and a single C-user. Based on this framework, the unicast rate maximization problem is formulated by optimizing the beamformers employed, while satisfying the rate requirement of multicast and the predefined accuracy of the radar beam pattern. The resultant non-convex optimization problem is solved by a penalty-based iterative algorithm to find a high-quality near-optimal solution. Next, the system is extended to the scenario of multiple pairs of R- and C-users, where a cluster-based NOMA-aided joint Rad-MU-Com framework is proposed. A joint beamformer design and power allocation optimization problem is formulated for the maximization of the sum of the unicast rate at each C-user, subject to the constraints on both the minimum multicast rate for each R&C pair and on accuracy of the radar beam pattern for detecting multiple R-users. The resultant joint optimization problem is efficiently solved by another penalty-based iterative algorithm developed.
description: 14 pages, 12 figures, this work is accepeted for the publication in IEEE Journal on Selected Areas in Communications
title: “Keeping on top of it”: how livestock farmers manage their workloads and the demands of farm assurance
Creators: name: Smalley, Rebecca
Publisher: name: University of Reading
Year: 2022

description: This study explores how livestock farmers in the UK are managing their workloads and the need to comply with sustainability standards, at a time when farm workforces are constrained by financial pressures and labour shortages. Whereas the labour implications of agri-environment schemes have been expertly studied, there has been less research on private-sector farm assurance schemes. Using a mixed-methods approach, the study combines analysis of scheme documents, data from the English Farm Business Survey, a postal survey of 230 farms and telephone interviews with 34 farmers, focusing on businesses with cattle or sheep in the English counties of Herefordshire, Shropshire and Wiltshire. The study identifies an increase in operational demands that farms must comply with to qualify for grant payments, remain certified and access markets. Livestock farms also face demands for increasingly sophisticated measures of record-keeping, planning and monitoring which require IT literacy and an experimental approach. To date the greatest burden has fallen on dairy farms, but the requirements for beef and lamb producers are growing. The study uses theories of farm resilience to conceptualise how farms accommodate the demands of farm assurance and other labour pressures. It finds that most livestock farms have the capacity to stretch their labour force, which helps them to cope with fluctuating workloads. Livestock farms are also adept at postponing non-urgent tasks and adjusting their production systems to bring their workloads in balance with their available labour. However, the study identified farms whose labour systems were under strain. Going forward, livestock farms must confront a widening range of external requirements in order to fulfil agri�environment demands of the state, meet the sustainability commitments of mainstream buyers or pursue alternative marketing channels. The study finds that if they are to fully implement these requirements and avoid becoming over-stretched, many livestock farms will need to find ways to afford and access additional help. Already, the financial and labour costs of compliance were prompting some sheep farmers in the study to consider dropping out of the Red Tractor scheme. The study contributes to research on farm-level resilience and change by paying close attention to how such labour issues affect farm decisions.
Simultaneously Transmitting and Reflecting (STAR)-RISs: A Coupled Phase-Shift Model
Creators: name: Liu, Yuanwei
name: Mu, Xidong
name: Schober, Robert
name: Poor, H. Vincent
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Theory (cs.IT)
subject: Signal Processing (eess.SP)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: A simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) aided communication system is investigated, where an access point sends information to two users located on each side of the STAR-RIS. Different from current works assuming that the phase-shift coefficients for transmission and reflection can be independently adjusted, which is non-trivial to realize for purely passive STAR-RISs, a coupled transmission and reflection phase-shift model is considered. Based on this model, a power consumption minimization problem is formulated for both non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA). In particular, the amplitude and phase-shift coefficients for transmission and reflection are jointly optimized, subject to the rate constraints of the users. To solve this non-convex problem, an efficient element-wise alternating optimization algorithm is developed to find a high-quality suboptimal solution, whose complexity scales only linearly with the number of STAR elements. Finally, numerical results are provided for both NOMA and OMA to validate the effectiveness of the proposed algorithm by comparing its performance with that of STAR-RISs using the independent phase-shift model and conventional reflecting/transmitting-only RISs.
description: 14 pages, 3 figures
Optimizing and extending light-sculpting microscopy for fast functional imaging in neuroscience
Creators: name: Rupprecht, Peter
name: Prevedel, Robert
name: Groessl, Florian
name: Haubensak, Wulf E.
name: Vaziri, Alipasha
Publisher: name: arXiv
Year: 2015
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A number of questions in systems biology such as understanding how dynamics of neuronal networks are related to brain function require the ability to capture the functional dynamics of large cellular populations at high speed. Recently, this has driven the development of a number of parallel and high speed imaging techniques such as light-sculpting microscopy, which has been used to capture neuronal dynamics at the whole brain and single cell level in small model organism. However, the broader applicability of light-sculpting microscopy is limited by the size of volumes for which high speed imaging can be obtained and scattering in brain tissue. Here, we present strategies for optimizing the present tradeoffs in light-sculpting microscopy. Various scanning modalities in light-sculpting microscopy are theoretically and experimentally evaluated, and strategies to maximize the obtainable volume speeds, and depth penetration in brain tissue using different laser systems are provided. Design-choices, important parameters and their trade-offs are experimentally demonstrated by performing calcium-imaging in acute mouse-brain slices. We further show that synchronization of line-scanning techniques with rolling-shutter read-out of the camera can reduce scattering effects and enhance image contrast at depth.
description: 16 pages, 5 figures
Messdaten im Physikunterricht auswerten – wann sind Messunsicherheiten wichtig?
Creators: name: Kok, Karel
name: Boczianowski, Franz
name: Priemer, Burkhard
Publisher: name: Humboldt-Universität zu Berlin
Year: 2020
Subjects: subject: Messunsicherheiten
subject: Experimentieren
subject: Physik Unterricht
subject: Didaktik
subject: Measurement uncertainties
subject: Experimenting
subject: Physics Education
subject: Didactics
subject: 530 Physik

description: Erstveröffentlichung in: MNU Journal 73(4), 2020
description: Experimente dienen im Physikunterricht verschiedenen didaktischen Zielen. Mit ihnen können Phänomene anschaulich oder Zusammenhänge plausibel gemacht werden. Darüber hinaus werden Experimente durchgeführt, um Gesetze empirisch aus Daten zu folgern. Bei Letzterem ist es unerlässlich, Qualitätskriterien für die Vereinbarkeit von Experiment und Theorie zu heranzuziehen. In diesem Beitrag wird die Bedeutung von Unsicherheiten als Qualitätskriterium allgemein und an einem Beispiel begründet.
Implicit Bias of Linear Equivariant Networks
Creators: name: Lawrence, Hannah
name: Georgiev, Kristian
name: Dienes, Andrew
name: Kiani, Bobak T.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Group equivariant convolutional neural networks (G-CNNs) are generalizations of convolutional neural networks (CNNs) which excel in a wide range of technical applications by explicitly encoding symmetries, such as rotations and permutations, in their architectures. Although the success of G-CNNs is driven by their \emph{explicit} symmetry bias, a recent line of work has proposed that the \emph{implicit} bias of training algorithms on particular architectures is key to understanding generalization for overparameterized neural nets. In this context, we show that $L$-layer full-width linear G-CNNs trained via gradient descent for binary classification converge to solutions with low-rank Fourier matrix coefficients, regularized by the $2/L$-Schatten matrix norm. Our work strictly generalizes previous analysis on the implicit bias of linear CNNs to linear G-CNNs over all finite groups, including the challenging setting of non-commutative groups (such as permutations), as well as band-limited G-CNNs over infinite groups. We validate our theorems via experiments on a variety of groups, and empirically explore more realistic nonlinear networks, which locally capture similar regularization patterns. Finally, we provide intuitive interpretations of our Fourier space implicit regularization results in real space via uncertainty principles.
description: 21 pages, 19 figures