cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Node mixing and group structure of complex software networks
Creators: name: Šubelj, Lovro
name: Žitnik, Slavko
name: Blagus, Neli
name: Bajec, Marko
Publisher: name: arXiv
Year: 2015
Subjects: subject: Social and Information Networks (cs.SI)
subject: Software Engineering (cs.SE)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Large software projects are among most sophisticated human-made systems consisting of a network of interdependent parts. Past studies of software systems from the perspective of complex networks have already led to notable discoveries with different applications. Nevertheless, our comprehension of the structure of software networks remains to be only partial. We here investigate correlations or mixing between linked nodes and show that software networks reveal dichotomous node degree mixing similar to that recently observed in biological networks. We further show that software networks also reveal characteristic clustering profiles and mixing. Hence, node mixing in software networks significantly differs from that in, e.g., the Internet or social networks. We explain the observed mixing through the presence of groups of nodes with common linking pattern. More precisely, besides densely linked groups known as communities, software networks also consist of disconnected groups denoted modules, core/periphery structures and other. Moreover, groups coincide with the intrinsic properties of the underlying software projects, which promotes practical applications in software engineering.
description: 26 pages, 14 figures, 11 tables
Students Perceptions of Sustainable Universities in Hungary. An Importance-Performance Analysis
Creators: name: Nagy, Szabolcs
name: Somosi, Mariann Veresne
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Economics (econ.GN)
subject: FOS: Economics and business

description: In order to succeed, universities are forced to respond to the new challenges in the rapidly changing world. The recently emerging fourth-generation universities should meet sustainability objectives to better serve their students and their communities. It is essential for universities to measure their sustainability performance to capitalise on their core strengths and to overcome their weaknesses. In line with the stakeholder theory, the objective of this study was to investigate students perceptions of university sustainability including their expectations about and satisfaction with the efforts that universities make towards sustainability. This paper proposes a new approach that combines the sustainable university scale, developed by the authors, with the importance-performance analysis to identify key areas of university sustainability. To collect data, an online survey was conducted in Hungary in 2019. The sustainable university scale was found to be a reliable construct to measure different aspects of university sustainability. Results of the importance-performance analysis suggest that students consider Hungarian universities unsustainable. Research findings indicate that Hungarian universities perform poorly in sustainable purchasing and renewable energy use, but their location and their efforts towards separate waste collection are their major competitive advantages. The main domains of university sustainability were also discussed. This study provides university decision-makers and researchers with insightful results supporting the transformation of traditional universities into sustainable, fourth-generation higher education institutions.
Resurgence and the Nekrasov-Shatashvili limit: connecting weak and strong coupling in the Mathieu and Lamé systems
Creators: name: Başar, G.
name: Dunne, G.V.
Publisher: name: Springer Verlag
Year: 2015

description: Abstract: The Nekrasov-Shatashvili limit for the low-energy behavior of N=2 and N=2* supersymmetric SU(2) gauge theories is encoded in the spectrum of the Mathieu and Lamé equations, respectively. This correspondence is usually expressed via an all-orders Bohr-Sommerfeld relation, but this neglects non-perturbative effects, the nature of which is very different in the electric, magnetic and dyonic regions. In the gauge theory dyonic region the spectral expansions are divergent, and indeed are not Borel-summable, so they are more properly described by resurgent trans-series in which perturbative and non-perturbative effects are deeply entwined. In the gauge theory electric region the spectral expansions are convergent, but nevertheless there are non-perturbative effects due to poles in the expansion coefficients, and which we associate with worldline instantons. This provides a concrete analog of a phenomenon found recently by Drukker, Mariño and Putrov in the large N expansion of the ABJM matrix model, in which non-perturbative effects are related to complex space-time instantons. In this paper we study how these very different regimes arise from an exact WKB analysis, and join smoothly through the magnetic region. This approach also leads to a simple proof of a resurgence relation found recently by Dunne and Ünsal, showing that for these spectral systems all non-perturbative effects are subtly encoded in perturbation theory, and identifies this with the Picard-Fuchs equation for the quantized elliptic curve.
Starspots, chromospheric emission lines, and flares of zero-age main-sequence stars
Creators: name: Yamashita, Mai
name: Itoh, Yoichi
name: Oasa, Yumiko
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Zero-age main-sequence (ZAMS) stars are considered to have enormous starspots and show strong chromospheric emission lines because of their strong surface magnetic field. We discuss the dynamo activities of ZAMS stars with respect to their periodic light variation caused by a starspot and with respect to the strength of the chromospheric emission lines. The light curves of $33$ ZAMS stars in IC 2391 and IC 2602 were obtained from \textit{TESS} photometric data. The light curves can be grouped into the following four categories: single frequency, possible shape changer, beater, and complex variability. The amplitudes of the light curves are $0.001-0.145\,\mathrm{mag}$, similar to those of ZAMS stars in Pleiades. The starspot coverages are $0.1-21\%$. We found that the light variations and Ca\,\emissiontype{II} emission line strength of ZAMS stars in IC 2391, IC 2602, and the Pleiades cluster are as large as those of the most active superflare stars and two orders larger than those of the Sun, and are located on the extensions of the superflare stars. These results suggest that superflare stars link the properties of the Sun to those of the ZAMS stars of ages between $30$ and $120\,\mathrm{Myr}$. ZAMS stars with a single frequency or possible shape change in the light curve tend to have both large light variation, indicating large spot coverage, and saturated Ca\,\emissiontype{II} emission line strength. ZAMS stars with beat or complex variability have small spot coverage and a faint Ca\,\emissiontype{II} emission line. We also detected $21$ flares in the \textit{TESS} light curves of $12$ ZAMS stars in IC 2391 and IC 2602, where most of these stars have saturated chromospheric Ca\,\emissiontype{II} emission lines. The energies of the flares are estimated to be $\sim 10^{33}-10^{35}\,\mathrm{erg}$, which is comparable with the energy of a superflare.
description: Accepted for publication in PASJ
The relationship between content marketing and the traditional marketing communication tools
Creators: name: Nagy, Szabolcs
name: Hajdu, Gergo
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Economics (econ.GN)
subject: FOS: Economics and business

description: Digitalization is making a significant impact on marketing. New marketing approaches and tools are emerging which are not always clearly categorised. This article seeks to investigate the relationship between one of the novel marketing tools, content marketing, and the five elements of the traditional marketing communication mix. Based on an extensive literature review, this paper analyses the main differences and similarities between them. This article aims to generate a debate on the status of content marketing. According to the authors' opinion, content marketing can be considered as the sixth marketing communication mix element. However, further research is needed to fill in the existing knowledge gap.
description: Keywords: content marketing, trends, advertising, sales promotion, direct marketing, personal selling, public relations
Bose-Fermi degeneracies in large N adjoint QCD
Creators: name: McGady, D.
name: Basar, G.
name: Cherman, A.
Publisher: name: Springer Verlag
Year: 2015

description: Abstract: We analyze the large N limit of adjoint QCD, an SU(N) gauge theory with Nf flavors of massless adjoint Majorana fermions, compactified on S3 × S1. We focus on the weakly-coupled confining small-S3 regime. If the fermions are given periodic boundary conditions on S1, we show that there are large cancellations between bosonic and fermionic contributions to the twisted partition function. These cancellations follow a pattern previously seen in the context of misaligned supersymmetry, and lead to the absence of Hagedorn instabilities for any S1 size L, even though the bosonic and fermionic densities of states both have Hagedorn growth. Adjoint QCD stays in the confining phase for any L ∼ N0, explaining how it is able to enjoy large N volume independence for any L. The large N boson-fermion cancellations take place in a setting where adjoint QCD is manifestly non-supersymmetric at any finite N, and are consistent with the recent conjecture that adjoint QCD has emergent fermionic symmetries in the large N limit.
Casimir Energy of Confining Large N Gauge Theories
Creators: name: Cherman, A.
name: Yamazaki, M.
name: Başar, G.
name: McGady, D.A.
Publisher: name: American Physical Society
Year: 2015

description: Four-dimensional asymptotically free large N gauge theories compactified on SR3×R have a weakly coupled confining regime when R is small compared to the strong scale. We compute the vacuum energy of a variety of confining large N nonsupersymmetric gauge theories in this calculable regime, where the vacuum energy can be thought of as the S3 Casimir energy. The N= renormalized vacuum energy turns out to vanish in the class of theories we have examined. This matches an implication of a recently observed temperature-reflection symmetry of such systems.
Experimental investigation of quantum correlations in a two-qutrit spin system
Creators: name: Fu, Yue
name: Liu, Wenquan
name: Ye, Xiangyu
name: Wang, Ya
name: Zhang, Chengjie
name: Duan, Chang-Kui
name: Rong, Xing
name: Du, Jiangfeng
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We report an experimental investigation of quantum correlations in a two-qutrit spin system in a single nitrogen-vacancy center in diamond at room temperatures. Quantum entanglement between two qutrits was observed at room temperature and the existence of non-classical correlations beyond entanglement in the qutrit case has been revealed. Our work demonstrates the potential of the NV centers as the multi-qutrit system to execute quantum information tasks and provides a powerful experimental platform for studying fundamental physics of high-dimensional quantum systems in future.
Comment on "Energy conditions in $f(Q)$ gravity"
Creators: name: De, Avik
name: How, Loo Tee
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In Phys. Rev. D 102, 024057 (2020), the authors studied energy conditions in $f(Q)$ theory following the same path as researchers handled the energy conditions in the curvature-based modified gravity theories, like $f(R)$ or $f(R,G)$ theories. However, the field equations in the $f(Q)$ theory was not expressed as an effective theory in the literature earlier and in the above mentioned paper [1], the authors claimed that the pressure and energy density follow a set of energy condition criteria without showing how they came to this conclusion. In this comment, we express $f(Q)$ theory as an effective theory in Friedmann-Lemaître-Robertson-Walker (FLRW) universe. And from there, the correct energy conditions are obtained in the traditional (general relativistic) way. Unfortunately, some missing terms in the published work [1] are noticed.
description: Accepted for publication in Phy. Rev. D
Scalable Multi-Output Label Prediction: From Classifier Chains to Classifier Trellises
Creators: name: Read, J.
name: Martino, L.
name: Olmos, P.
name: Luengo, D.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Machine Learning (stat.ML)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Data Structures and Algorithms (cs.DS)
subject: Machine Learning (cs.LG)
subject: Computation (stat.CO)
subject: FOS: Computer and information sciences

description: Multi-output inference tasks, such as multi-label classification, have become increasingly important in recent years. A popular method for multi-label classification is classifier chains, in which the predictions of individual classifiers are cascaded along a chain, thus taking into account inter-label dependencies and improving the overall performance. Several varieties of classifier chain methods have been introduced, and many of them perform very competitively across a wide range of benchmark datasets. However, scalability limitations become apparent on larger datasets when modeling a fully-cascaded chain. In particular, the methods' strategies for discovering and modeling a good chain structure constitutes a mayor computational bottleneck. In this paper, we present the classifier trellis (CT) method for scalable multi-label classification. We compare CT with several recently proposed classifier chain methods to show that it occupies an important niche: it is highly competitive on standard multi-label problems, yet it can also scale up to thousands or even tens of thousands of labels.
description: (accepted in Pattern Recognition)
Models of R-supercompactness
Creators: name: Rodriguez, Daniel
Publisher: name: Figshare
Year: 2018
Subjects: subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics

description: Under various appropriate hypotheses it is shown that there is only one determinacy model of the form L(R, μ) in which μ is a supercompact measure on P!1 (R). In particular, this gives a positive answer to a question asked by W.H. Woodin in 1983. It is also proven that it is relatively consistent that there are different ZF models of the form L(R, μ) in which μ witnesses that !1 is R-supercompact.
Photonic crystals with topological defects
Creators: name: Liew, Seng Fatt
name: Knitter, Sebastian
name: Xiong, Wen
name: Cao, Hui
Publisher: name: arXiv
Year: 2014
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We introduce topological defect to a square lattice of elliptical cylinders. Despite the broken translational symmetry, the long-range positional order of the cylinders leads to residual photonic bandgap in the density of optical states. However, the band-edge modes are strongly modified by the spatial variation of ellipse orientation. The $Γ-X$ band-edge mode splits into four regions of high intensity and the output flux becomes asymmetric due to the formation of crystalline domains with different orientation. The $Γ-M$ band-edge mode has the energy flux circulates around the topological defect center, creating an optical vortex. By removing the elliptical cylinders at the center, we create localized defect states which are dominated by either clockwise or counter-clockwise circulating waves. The flow direction can be switched by changing the ellipse orientation. The deterministic aperiodic variation of the unit cell orientation adds another dimension to the control of light in photonic crystals, enabling creation of diversified field pattern and energy flow landscape.
description: 6 pages, 7 figures
Multi-objective Algorithms for Coupled Optimization of Mechanical and Electromagnetic Systems
Creators: name: Brinster, Irina
Publisher: name: Figshare
Year: 2018
Subjects: subject: Computer Engineering
subject: 90699 Electrical and Electronic Engineering not elsewhere classified
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Modern mobile devices incorporate several transmit and receive antennas in highly constrained volumes. As miniaturized antennas impinge upon fundamental physical limits on efficiency, new design approaches are required to support ever-smaller devices with more varied and robust communication performance. We take an unconventional design approach in which an arbitrary metallic structure and its components can be modified to act as efficient radiators. Using eigenmode analysis and the theory of characteristic modes (TCM), we develop algorithms that allow for effective integration of antennas with mechanical structures and enable structure reuse, helping meet stringent space and weight constraints without sacrificing electromagnetic performance. We derive TCM-based objectives for effective exploration of the design space in the electromagnetic (EM) domain. The procedure includes a feed placement technique that identifies viable excitation points on the structure without running full EM analysis. In addition to computational advantages, this provides a point of comparison among a variety of antenna shapes. Empirical evaluation shows that the estimates of radiated power from TCM can effectively guide optimization toward structures with improved radiating properties. Automated feed placement increases the proportion of good-quality designs among the explored candidates by consistently selecting the most promising feed positions. The ability of the TCM-based algorithm to direct the search is further validated on two real-world applications: integration of a GPS antenna with the frame of a mobile phone and integration of an S-band antenna with the frame of a small spacecraft. To the best of our knowledge, this is the first work that applies TCM to automated optimization of antennas. We investigate how to leverage domain-specific methods and solution representations in the coupled optimization of antennas. We develop a novel multi-objective optimization framework based on local search in each domain. In this procedure, the local optima in each objective are obtained and modified to create a new population of candidate designs. On a number of benchmark problems, the proposed technique is competitive with leading multi-objective algorithms: while it finds a less uniform distribution along the Pareto front, it shows better performance in locating solutions at the boundaries of the tradeo  curve. The local search algorithm is successfully applied to topology optimization of an antenna for a CubeSat, a small low-cost satellite platform.
Triangle anomaly in Weyl semimetals
Creators: name: Başar, G.
name: Kharzeev, D.E.
name: Yee, H.-U.
Publisher: name: American Physical Society
Year: 2014

description: Weyl semimetals possess massless chiral quasiparticles, and they are thus affected by the triangle anomalies. We discuss the features of the chiral magnetic and chiral vortical effects specific to Weyl semimetals, and then propose three phenomena caused by the triangle anomalies in this material: (i) anomaly cooling; (ii) charge transport by soliton waves as described by Burgers' equation, and (iii) the shift of the Berezinskii-Kosterlitz-Thouless phase transition of superfluid vortices coupled to Weyl fermions. In addition, we establish the conditions under which the chiral magnetic current exists in real materials.
Polar circumtriple planets and disks can only form close to a triple star
Creators: name: Lepp, Stephen
name: Martin, Rebecca G.
name: Lubow, Stephen H.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Observations of protoplanetary disks around binary and triple star systems suggest that misalignments between the orbital plane of the stars and the disks are common. Motivated by recent observations of polar circumbinary disks, we explore the possibility for polar circumtriple disks and therefore polar circumtriple planets that could form in such a disk. With n-body simulations and analytic methods we find that the inclusion of the third star, and the associated apsidal precession, significantly reduces the radial range of polar orbits so that circumtriple polar disks and planets can only be found close to the stellar system. Outside of a critical radius, that is typically in the range of 3-10 times the outer binary separation depending upon the binary parameters, the orbits behave the same as they do around a circular orbit binary. For some observed systems that have shorter period inner binaries, the critical radius is considerably larger. If polar circumtriple planets can form, we suggest that it is likely that they form in a disk that was subject to breaking.
description: Accepted for publication in ApJL
Constraints on the non-thermal desorption of methanol in the cold core LDN 429-C
Creators: name: Taillard, A.
name: WakelaM, V.
name: Gratier, P.
name: Dartois, E.
name: Chabot, M.
name: Noble, J. A.
name: Keane, J. V.
name: Boogert, A. C. A.
name: Harsono, D.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Cold cores are an early step of star formation, characterized by densities > 10$^4$ cm$^{-3}$, low temperatures (< 15 K), and very low external UV radiation. We investigate the physico-chemical processes at play to tracing the origin of molecules that are predominantly formed via reactions on dust grain surfaces. We observed the cold core LDN 429-C with the NOEMA interferometer and the IRAM 30m single dish telescope in order to obtain the gas-phase abundances of key species, including CO and CH$_3$OH. Comparing the observed gas phase of methanol to its solid phase previously observed with Spitzer allows us to put quantitative constraints on the efficiency of the non-thermal desorption of this species. With physical parameters determined from available Herschel data, we computed abundance maps of 11 detected molecules with a non-local thermal equilibrium radiative transfer model. These observations allowed us to probe the molecular abundances as a function of density and visual extinction, with the variation in temperature being restrained between 12 and 18 K. We then compared the observed abundances to the predictions of the Nautilus astrochemical model. We find that all molecules have lower abundances at high densities and visual extinctions with respect to lower density regions, except for methanol. Comparing these observations with a grid of chemical models based on the local physical conditions, we were able to reproduce these observations, allowing only the parameter time to vary. Comparing the observed gas-phase abundance of methanol with previous measurements of the methanol ice, we estimate a non-thermal desorption efficiency between 0.002% and 0.09%, increasing with density. The apparent increase in the desorption efficiency cannot be reproduced by our model unless the yield of cosmic-ray sputtering is altered due to the ice composition varying as a function of density.
Speckle Space-Time Covariance in High-Contrast Imaging
Creators: name: Lewis, Briley L.
name: Fitzgerald, Michael P.
name: Dodkins, Rupert H.
name: Davis, Kristina K.
name: Lin, Jonathan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We introduce a new framework for point-spread function (PSF) subtraction based on the spatio-temporal variation of speckle noise in high-contrast imaging data where the sampling timescale is faster than the speckle evolution timescale. One way that space-time covariance arises in the pupil is as atmospheric layers translate across the telescope aperture and create small, time-varying perturbations in the phase of the incoming wavefront. The propagation of this field to the focal plane preserves some of that space-time covariance. To utilize this covariance, our new approach uses a Karhunen-Loéve transform on an image sequence, as opposed to a set of single reference images as in previous applications of Karhunen-Loéve Image Processing (KLIP) for high-contrast imaging. With the recent development of photon-counting detectors, such as microwave kinetic inductance detectors (MKIDs), this technique now has the potential to improve contrast when used as a post-processing step. Preliminary testing on simulated data shows this technique can improve contrast by at least 10-20% from the original image, with significant potential for further improvement. For certain choices of parameters, this algorithm may provide larger contrast gains than spatial-only KLIP.
description: Accepted to AJ
Nonparametric Learning in High Dimensions
Creators: name: Liu, Han
Publisher: name: Figshare
Year: 2018
Subjects: subject: 170203 Knowledge Representation and Machine Learning
subject: FOS: Psychology

description: This thesis develops flexible and principled nonparametric learning algorithms
to explore, understand, and predict high dimensional and complex
datasets. Such data appear frequently in modern scientific domains and lead
to numerous important applications. For example, exploring high dimensional
functional magnetic resonance imaging data helps us to better understand
brain functionalities; inferring large-scale gene regulatory network is crucial
for new drug design and development; detecting anomalies in high dimensional
transaction databases is vital for corporate and government security.

Our main results include a rigorous theoretical framework and efficient nonparametric
learning algorithms that exploit hidden structures to overcome the
curse of dimensionality when analyzing massive high dimensional datasets.
These algorithms have strong theoretical guarantees and provide high dimensional
nonparametric recipes for many important learning tasks, ranging from
unsupervised exploratory data analysis to supervised predictive modeling. In
this thesis, we address three aspects:

1 Understanding the statistical theories of high dimensional nonparametric
inference, including risk, estimation, and model selection consistency;

2 Designing new methods for different data-analysis tasks, including
regression, classification, density estimation, graphical model learning,
multi-task learning, spatial-temporal adaptive learning;

3 Demonstrating the usefulness of these methods in scientific applications,
including functional genomics, cognitive neuroscience, and meteorology.

In the last part of this thesis, we also present the future vision of high
dimensional and large-scale nonparametric inference.
Scaling relation between pA and AA collisions
Creators: name: Başar, G.
name: Teaney, D.
Publisher: name: American Physical Society
Year: 2014

description: We compare the flowlike correlations in high multiplicity proton-nucleus (p+A) and nucleus-nucleus (A+A) collisions. At fixed multiplicity, the correlations in these two colliding systems are strikingly similar, although the system size is smaller in p+A. Based on an independent cluster model and a simple conformal scaling argument, where the ratio of the mean free path to the system size stays constant at fixed multiplicity, we argue that flow in p+A emerges as a collective response to the fluctuations in the position of clusters, just like in A+A collisions. With several physically motivated and parameter free rescalings of the recent LHC data, we show that this simple model captures the essential physics of elliptic and triangular flow in p+A collisions. We also explore the implications of the model for jet energy loss in p+A, and predict slightly larger transverse momentum broadening in p+A than in A+A at the same multiplicity.
Domain-Specific Text Generation for Machine Translation
Creators: name: Moslem, Yasmin
name: Haque, Rejwanul
name: Kelleher, John D.
name: Way, Andy
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: Preservation of domain knowledge from the source to target is crucial in any translation workflow. It is common in the translation industry to receive highly specialized projects, where there is hardly any parallel in-domain data. In such scenarios where there is insufficient in-domain data to fine-tune Machine Translation (MT) models, producing translations that are consistent with the relevant context is challenging. In this work, we propose a novel approach to domain adaptation leveraging state-of-the-art pretrained language models (LMs) for domain-specific data augmentation for MT, simulating the domain characteristics of either (a) a small bilingual dataset, or (b) the monolingual source text to be translated. Combining this idea with back-translation, we can generate huge amounts of synthetic bilingual in-domain data for both use cases. For our investigation, we use the state-of-the-art Transformer architecture. We employ mixed fine-tuning to train models that significantly improve translation of in-domain texts. More specifically, in both scenarios, our proposed methods achieve improvements of approximately 5-6 BLEU and 2-3 BLEU, respectively, on the Arabic-to-English and English-to-Arabic language pairs. Furthermore, the outcome of human evaluation corroborates the automatic evaluation results.
description: AMTA 2022 - MT Research Track
The Structure of Cholesterol in Lipid Rafts
Creators: name: Toppozini, Laura
name: Meinhardt, Sebastian
name: Armstrong, Clare L.
name: Yamani, Zahra
name: Kucerka, Norbert
name: Schmid, Friederike
name: Rheinstaedter, Maikel C.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Biomolecules (q-bio.BM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Rafts, or functional domains, are transient nano- or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking and lipid/protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short-lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules we observe raft-like structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to ordering of the cholesterol molecules in the raft-like structures were observed and indexed by two different structures: a monoclinic structure of ordered cholesterol pairs of alternating direction in equilibrium with cholesterol plaques, i.e., triclinic cholesterol bilayers.
description: includes supplementary information
Additional file 1 of A critical review: developing a birth integrity framework for epidemiological studies through meta-ethnography
Creators: name: Batram-Zantvoort, Stephanie
name: Wandschneider, Lisa
name: Razum, Oliver
name: Miani, Céline
Publisher: name: figshare
Year: 2024
Subjects: subject: Medicine
subject: Biotechnology
subject: Environmental Sciences not elsewhere classified
subject: Sociology
subject: FOS: Sociology
subject: Science Policy

description: Additional file 1. Search strategy, inclusion and exclusion criteria, and data extraction.
Modeling Dislocation Sources and Plastic Flow through Grain Boundaries in Mesoscopic Field Dislocation Mechanics
Creators: name: Saurabh  Puri
Publisher: name: Figshare
Year: 2018
Subjects: subject: 90799 Environmental Engineering not elsewhere classified
subject: FOS: Environmental engineering
subject: 90599 Civil Engineering not elsewhere classified
subject: FOS: Civil engineering

description: This work involves the modeling and understanding of mechanical behavior of crystalline materials using a continuum approach, Phenomenological Mesoscopic Field Dislocation Mechanics (PMFDM; Acharya and Roy, 2006). Specifically, this thesis contains three major parts. The first part involves the modeling of some aspects of dislocation sources that represent the emission of dislocation dipoles. The developed strategy is then used to investigate the dependence of mechanical response on the external dimensions of idealized single crystalline cubical samples with varying source and initial excess dislocation density distribution. The second part involves the modeling of plastic flow through grain boundaries in polycrystalline materials. The model is then used to analyze dislocation microstructure development in polycrystalline thin films and its effect on the mechanical response. The effect of thickness and the presence/absence of surface passivation on the plastic deformation of thin films is also studied. Results from these simulations are found to be in good qualitative agreement with experimental observations. The last part involves the numerical implementation of finite deformation PMFDM theory. The developed computational tool is capable of analyzing the deformation of crystalline materials under geometric and material nonlinearity.
Vegetation reconstruction during the Holocene period in east Turkana Basin, using phytolith analysis
Creators: name: Mashaka, Husna
Publisher: name: Zenodo
Year: 2023
Subjects: Languages of Tanzania
Tanzanian Rift Valley
vegetation reconstruction
Turkana Basin
phytoliths

description: This study demonstrates the application of phytolith analyses as a proxy to reconstruct vegetation history. Phytoliths are plant silica cells that preserve for a long period even when plants are dead. The study was conducted in two localities in the east Turkana basin, Ileret and Karari. The main goal of this study is to understand how vegetation cover changes over time. Relating these changes with archaeological and geological data published from the region, inferences of the key drivers contributing to these changes are presented. There are two specific objectives of this study; the first is the correlation between modern phytolith assemblages and the above-ground vegetation cover to explain the impact of modern pastoralists and climate on modern vegetation cover. Second, analyses of phytolith assemblages collected from archaeological sediments/sites to determine vegetation cover changes during the Holocene. To achieve the first objective, plant species inside and outside abandoned boma were identified, tallied, and recorded. Transects were established outside bomas to understand the plant diversity and abundance between inside and outside abandoned bomas. Soil samples were collected from recently abandoned bomas from inside and outside. Also, dung (donkeys, sheep/goats, and cattle) was collected from inside to determine their biased phytolith input against outside boma. To achieve the second objective, sediment samples were collected from Early and mid-Holocene sites to compare and reconstruct the vegetation history. In conclusion, our results indicate that phytoliths from modern soil samples correlate with the above-ground vegetation composition and reflect the human impact on the landscape. Reconstructing the palaeoenvironment through phytolith analysis revealed that herbs and grasses dominate vegetation cover. The modern and fossil phytoliths can accurately predict past vegetation cover, especially in classifying different habitats such as grasslands, wooded grasslands, and wooded vegetation.
description: -Note: This talk has not gone through a process of peer review, and findings should therefore be treated as preliminary and subject to change.
-Acknowledgement and citation: Mashaka, Husna. 2023. Vegetation reconstruction during the Holocene period in east Turkana Basin, using phytolith analysis. Talk Given at Rift Valley Webinar Series 06/09/2023.
X-ray Emission from Charge Exchange in the Cygnus Loop SNR
Creators: name: Roberts, Shawn R.
name: Wang, Q. Daniel
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The Cygnus Loop has been the focus of substantial debate concerning the contribution of charge exchange (CX) to supernova remnant (SNR) X-ray emission. We take advantage of a distinct feature of CX, enhanced Kα forbidden line emission, and employ the energy centroid of the OVII Kα triplet as a diagnostic. Based on X-ray spectra extracted from an extensive set of Suzaku observations, we measure the energy centroid shifts of the triplet on and off the shock rim of the remnant. We find that enhanced forbidden to resonance line emission exists throughout much of the rim and this enhancement azimuthally correlates with non-radiative Hα filaments, a tracer of strong neutral-plasma interaction in the optical. We also show that alternative mechanisms cannot explain the enhancement observed. These results demonstrate the need to model the CX contribution to the X-ray emission of SNRs, particularly for shocks propagating in a partially neutral medium. Such modeling may be critically important to the correct measurements of the ionization, thermal, and chemical properties of SNRs.
description: 8 pages, 5 figures, MNRAS accepted
Magneto-sonoluminescence and its signatures in photon and dilepton production in relativistic heavy ion collisions
Creators: name: Shuryak, E.V.
name: Kharzeev, D.E.
name: Başar, G.
Publisher: name: American Physical Society
Year: 2014

description: The matter produced in the early stages of heavy ion collisions consists mostly of gluons, and is penetrated by the coherent magnetic field produced by spectator nucleons. The fluctuations of gluonic matter in an external magnetic field couple to real and virtual photons through virtual quark loops. We study the resulting contributions to photon and dilepton production that stem from the fluctuations of the stress tensor Tμν in the background of a coherent magnetic field B Our study extends significantly the earlier work [G. Basar, D. E. Kharzeev, and V. Skokov, Phys. Rev. Lett. 109, 202303 (2012)PRLTAO0031- 900710.1103/PhysRevLett.109.202303], in which only the fluctuations of the trace of the stress tensor Tμμ were considered (the coupling of Tμμ to electromagnetic fields is governed by the scale anomaly). In the present paper we derive more general relations using the operator product expansion (OPE). We also extend the previous study to the case of dileptons, which offers the possibility to discriminate between various production mechanisms. Among the phenomena that we study are magneto-sonoluminescence [MSL, the interaction of magnetic field B (x,t) with the sound perturbations of the stress tensor δTμν(x,t)] and magneto-thermoluminescence [MTL, the interaction of B (x,t) with smooth average Tμν]. We calculate the rates of these process and find that they can dominate the photon and dilepton production at early stages of heavy ion collisions. We also point out the characteristic signatures of MSL and MTL that can be used to establish their presence and to diagnose the produced matter.
A Systematic Study of the Short-Term X-ray Variability of Seyfert Galaxies I. Diversity of the X-ray Rms Spectra
Creators: name: Hu, Jingwei
name: Jin, Chichuan
name: Cheng, Huaqing
name: Yuan, Weimin
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The X-ray variability of active galactic nuclei (AGN) carries crucial information about the X-ray radiation mechanism. We performed a systematic study of the X-ray short-term (1-100 ks timescale) variability for a large sample of 78 Seyferts with 426 deep XMM-Newton observations. In this paper, we present the time-averaged spectra and rms spectra for the entire sample, which show a variety of properties. Based on the spectral shape, we divide the rms spectra into five subtypes and the time-averaged spectra into four subtypes. The most common shape of the rms spectra is concave-down where the rms peaks at $\sim$ 1 keV. We find that different sources can show similar time-averaged spectra and rms spectra. However, there is no one-to-one mapping between the subtypes of the time-averaged spectra and rms spectra, as similar time-averaged spectra can be accompanied by different rms spectra, and vice versa. This is likely because different physical mechanisms can produce similar rms spectra. For every subtype of the time-averaged spectra, we report its preferred subtypes of the rms spectra in both low- and high-frequency bands. We also compare the statistical properties for different subtypes, such as the black hole mass and Eddington ratio. Finally, we investigate the rms in the Fe K$α$ line regime and find that those with a broad and extended red-wing profile tend to show stronger variability than those showing a narrow or relatively symmetric profile. Our results demonstrate the necessity of performing joint spectral and variability modeling in order to understand the mechanism of the X-ray emission in AGN. All of the rms spectra have been made publicly available.
description: 25 pages, 10 figures, 4 tables, accepted for publication in The Astrophysical Journal, data available under https://gohujingwei.github.io/rms.html
Resurgence theory, ghost-instantons, and analytic continuation of path integrals
Creators: name: Başar, G.
name: Ünsal, M.
name: Dunne, G.V.
Publisher: name: Springer Verlag
Year: 2013

description: A general quantum mechanical or quantum field theoretical system in the path integral formulation has both real and complex saddles (instantons and ghost-instantons). Resurgent asymptotic analysis implies that both types of saddles contribute to physical observables, even if the complex saddles are not on the integration path i.e., the associated Stokes multipliers are zero. We show explicitly that instanton-anti-instanton and ghostanti-ghost saddles both affect the expansion around the perturbative vacuum. We study a self-dual model in which the analytic continuation of the partition function to negative values of coupling constant gives a pathological exponential growth, but a homotopically independent combination of integration cycles (Lefschetz thimbles) results in a sensible theory. These two choices of the integration cycles are tied with a quantum phase transition. The general set of ideas in our construction may provide new insights into non-perturbative QFT, string theory, quantum gravity, and the theory of quantum phase transitions.
Competing scanning tunneling microscope tip-interlayer interactions for twisted multilayer graphene on the a-plane SiC surface
Creators: name: Xu, P.
name: Ackerman, M. L.
name: Barber, S. D.
name: Schoelz, J. K.
name: Thibado, P. M.
name: Wheeler, V. D.
name: Nyakiti, L. O.
name: Myers-Ward, R. L.
name: Eddy, C. R.
name: Gaskill, D. K.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Scanning tunneling microscopy (STM) images are obtained for the first time on few layer and twisted multilayer epitaxial graphene states synthesized on n+ 6H-SiC a-plane non-polar surface. The twisted graphene is determined to have a rotation angle of 5.4° between the top two layers, by comparing moiré patterns from stick and ball models of bilayer graphene to experimentally obtained images. Furthermore, the experimental moiré pattern shows dynamic behavior, continuously shuffling between two stable surface arrangements one bond length apart. The moiré pattern shifts by more than 1 nm, making it easy to observe with STM. Explanation of this dynamic behavior is attributed to electrostatic interactions between the STM tip and the graphene sample.
description: 20 pages, 5 figures
Tidal capture of stars by supermassive black holes: implications for periodic nuclear transients and quasi-periodic eruptions
Creators: name: Cufari, M.
name: Nixon, C. J.
name: Coughlin, Eric R.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Stars that plunge into the center of a galaxy are tidally perturbed by a supermassive black hole (SMBH), with closer encounters resulting in larger perturbations. Exciting these tides comes at the expense of the star's orbital energy, which leads to the naive conclusion that a smaller pericenter (i.e., a closer encounter between the star and SMBH) always yields a more tightly bound star to the SMBH. However, once the pericenter distance is small enough that the star is partially disrupted, morphological asymmetries in the mass lost by the star can yield an \emph{increase} in the orbital energy of the surviving core, resulting in its ejection -- not capture -- by the SMBH. Using smoothed-particle hydrodynamics simulations, we show that the combination of these two effects -- tidal excitation and asymmetric mass loss -- result in a maximum amount of energy lost through tides of $\sim 2.5\%$ of the binding energy of the star, which is significantly smaller than the theoretical maximum of the total stellar binding energy. This result implies that stars that are repeatedly partially disrupted by SMBHs many ($\gtrsim 10$) times on short-period orbits ($\lesssim$ few years), as has been invoked to explain the periodic nuclear transient ASASSN-14ko and quasi-periodic eruptions, must be bound to the SMBH through a mechanism other than tidal capture, such as a dynamical exchange (i.e., Hills capture).
description: 4 pages, 2 figures, Accepted for publication in MNRAS
Optically controllable coupling between edge and topological interface modes of graphene metasurfaces
Creators: name: Wang, Yupei
name: Panoiu, Nicolae C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Nonlinear topological photonics has been attracting increasing research interest, as it provides an exciting photonic platform that combines the advantages of active all-optical control offered by nonlinear optics with the unique features of topological photonic systems, such as topologically-protected defect-immune light propagation. In this paper, we demonstrate that topological interface modes and trivial edge modes of a specially designed graphene metasurface can be coupled in a tunable and optically controllable manner, thus providing an efficient approach to transfer optical power to topologically protected states. This is achieved in a pump-signal configuration, in which an optical pump propagating in a bulk mode of the metasurface is employed to tune the band structure of the photonic system and, consequently, the coupling coefficient and wave-vector mismatch between edge and topological interface modes. This tunable coupling mechanism is particularly efficient due to the large Kerr coefficient of graphene. Importantly, we demonstrate that the required pump power can be significantly reduced if the optical device is operated in the slow-light regime. We perform our analysis using both \textit{ab initio} full-wave simulations and a coupled-mode theory that captures the main physics of this active coupler and observe a good agreement between the two approaches. This work may lead to the design of active topological photonic devices with new or improved functionality.
description: 12 pages, 8 figures