cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
Creators: name: Van Reeth, T.
name: Tkachenko, A.
name: Aerts, C.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: CONTEXT. Gamma Doradus stars (hereafter gamma Dor stars) are known to exhibit gravity- and/or gravito-intertial modes that probe the inner stellar region near the convective core boundary. The non-equidistant spacing of the pulsation periods is an observational signature of the stars' evolution and current internal structure and is heavily influenced by rotation. AIMS. We aim to constrain the near-core rotation rates for a sample of gamma Dor stars, for which we have detected period spacing patterns. METHODS. We combined the asymptotic period spacing with the traditional approximation of stellar pulsation to fit the observed period spacing patterns using chi-squared optimisation. The method was applied to the observed period spacing patterns of a sample of stars and used for ensemble modelling. RESULTS. For the majority of stars with an observed period spacing pattern we successfully determined the rotation rates and the asymptotic period spacing values, though the uncertainty margins on the latter were typically large. This also resulted directly in the identification of the modes corresponding with the detected pulsation frequencies, which for most stars were prograde dipole gravity and gravito-inertial modes. The majority of the observed retrograde modes were found to be Rossby modes. We further discuss the limitations of the method due to the neglect of the centrifugal force and the incomplete treatment of the Coriolis force. CONCLUSION. Despite its current limitations, the proposed methodology was successful to derive the rotation rates and to identify the modes from the observed period spacing patterns. It forms the first step towards detailed seismic modelling based on observed period spacing patterns of moderately to rapidly rotating gamma Dor stars.
description: 12 pages, 15 figures, 5 tables. Accepted for publication in Astronomy & Astrophysics
Structure and stability of high-redshift galaxies in cosmological simulations
Creators: name: Meng, Xi
name: Gnedin, Oleg Y.
name: Li, Hui
Publisher: name: arXiv
Year: 2018
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We investigate the structure of galaxies formed in a suite of high-resolution cosmological simulations. Consistent with observations of high-redshift galaxies, our simulated galaxies show irregular, prolate shapes, which are dominated by turbulent motions instead of rotation. Yet molecular gas and young stars are restricted to a relatively thin plane. We examine the accuracy of applying the Toomre linear stability analysis to predict the location and amount of gas available for star formation. We find that the Toomre criterion still works for these irregular galaxies, after correcting for multiple gas and stellar components: the $Q$ parameter in $\rm{H_2}$ rich regions is in the range $0.5-1$, remarkably close to unity. Due to the violent stellar feedback from supernovae and strong turbulent motions, young stars and molecular gas are not always spatially associated. Neither the $Q$ map nor the $\rm{H_2}$ surface density map coincide with recent star formation exactly. We argue that the Toomre criterion is a better indicator of future star formation than a single $\rm{H_2}$ surface density threshold because of the smaller dynamic range of $Q$. The depletion time of molecular gas is below 1~Gyr on kpc scale, but with large scatter. Centering the aperture on density peaks of gas/young stars systematically biases the depletion time to larger/smaller values and increases the scatter.
description: 17 pages, 11 figures; accepted for publication in MNRAS
The Radical Pair Mechanism of Animal Magnetoreception
Creators: name: D'Souza, Edeline M
name: Jones, Alex R
name: Kattnig, Daniel R
name: Jiménez, José I
Publisher: name: Zenodo
Year: 2020
Subjects: Magnetoreception, radical pair mechanism, quantum biology

description: Animal magnetoreception is the phenomenon by which some night-migratory birds can make seasonal migrations by utilising a light-dependent response to the Earth’s magnetic field (MF) for directional information. At ~25-65µT, the geomagnetic field is generally considered impotent upon biological molecules [1]. Cryptochrome (CRY), a circadian regulator protein, is the proposed, a priori magnetoreceptor molecule. It is thought to generate spin-correlated radical pairs that can be modulated by an external MF; known as the ‘radical pair mechanism’ (RPM). Although relatively well-modelled in computational biophysics as a result [2,3], the biological mechanism of ‘the avian compass’ in migrating birds is yet to be determined. By comparison of CRYs from disparate sources - avian, insect, mammalian and plant - and engineering variants in E. coli, the ultimate aim is to elucidate the role of cryptochrome in the mechanism of molecular magnetosensory processing. This can subsequently be instrumental in developing less invasive and phototoxic (magneto-)optogenetic therapies.
The Gromov-Hausdorff propinquity for metric Spectral Triples
Creators: name: Latremoliere, Frederic
Publisher: name: arXiv
Year: 2018
Subjects: subject: Operator Algebras (math.OA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 46L89, 46L30, 58B34

description: We define a metric on the class of metric spectral triples, which is null exactly between spectral triples with unitary equivalent Dirac operators and *-isomorphic underlying C*-algebras. This metric dominates the propinquity, and thus implies metric convergence of the compact quantum metric spaces induced by metric spectral triples. In the process of our construction, we also introduce the covariant modular propinquity, as a key component for the definition of the spectral propinquity.
description: 46 pages. Revised version corrects various typos, and adopts certain standard conventions about C*-correspondences
Accelerated Sampling Kaczmarz Motzkin Algorithm for The Linear Feasibility Problem
Creators: name: Morshed, Md Sarowar
name: Islam, Md Saiful
name: Noor-E-Alam, Md.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: The Sampling Kaczmarz Motzkin (SKM) algorithm is a generalized method for solving large scale linear systems of inequalities. Having its root in the relaxation method of Agmon, Schoenberg, and Motzkin and the randomized Kaczmarz method, SKM outperforms the state of the art methods in solving large-scale Linear Feasibility (LF) problems. Motivated by SKM's success, in this work, we propose an Accelerated Sampling Kaczmarz Motzkin (ASKM) algorithm which achieves better convergence compared to the standard SKM algorithm on ill conditioned problems. We provide a thorough convergence analysis for the proposed accelerated algorithm and validate the results with various numerical experiments. We compare the performance and effectiveness of ASKM algorithm with SKM, Interior Point Method (IPM) and Active Set Method (ASM) on randomly generated instances as well as Netlib LPs. In most of the test instances, the proposed ASKM algorithm outperforms the other state of the art methods.
description: Journal of Global Optimization, Oct 2019
Augmentations and link group representations
Creators: name: Gao, Honghao
Publisher: name: arXiv
Year: 2019
Subjects: subject: Geometric Topology (math.GT)
subject: Symplectic Geometry (math.SG)
subject: FOS: Mathematics

description: We construct the augmentation representation. It is a representation of the fundamental group of the link complement associated to an augmentation of the framed cord algebra. This construction connects representations of two link invariants of different types. We also study properties of the augmentation representation.
description: 31 pages, 14 figures. Published version without journal formatting
Bicategories in Univalent Foundations
Creators: name: Ahrens, Benedikt
name: Frumin, Dan
name: Maggesi, Marco
name: Veltri, Niccolò
name: van der Weide, Niels
Publisher: name: arXiv
Year: 2019
Subjects: subject: Category Theory (math.CT)
subject: Logic in Computer Science (cs.LO)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: We develop bicategory theory in univalent foundations. Guided by the notion of univalence for (1-)categories studied by Ahrens, Kapulkin, and Shulman, we define and study univalent bicategories. To construct examples of univalent bicategories in a modular fashion, we develop displayed bicategories, an analog of displayed 1-categories introduced by Ahrens and Lumsdaine. We demonstrate the applicability of this notion, and prove that several bicategories of interest are univalent. Among these are the bicategory of univalent categories with families and the bicategory of pseudofunctors between univalent bicategories. Furthermore, we show that every bicategory with univalent hom-categories is weakly equivalent to a univalent bicategory. All of our work is formalized in Coq as part of the UniMath library of univalent mathematics.
description: v1: 16 pages; v2: Veltri added as coauthor, extended version, 32 pages, list of changes given in Section "Publication history"; v3: final journal version to be published in Mathematical Structures in Computer Science; v4: fixed some typos that remain in the MSCS version
Can Bioinformatics Be Considered as an Experimental Biological Science?
Creators: name: Ilzins, Olaf
name: Isea, Raul
name: Hoebeke, Johan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Other Quantitative Biology (q-bio.OT)
subject: FOS: Biological sciences

description: The objective of this short report is to reconsider the subject of bioinformatics as just being a tool of experimental biological science. To do that, we introduce three examples to show how bioinformatics could be considered as an experimental science. These examples show how the development of theoretical biological models generates experimentally verifiable computer hypotheses, which necessarily must be validated by experiments in vitro or in vivo.
description: 3 pages, Open Access
Computing the Language of Life: NLP Approaches to Feature Extraction for Protein Classification
Creators: name: Ananthan Nambiar
name: Hopkins, Mark
name: Ritz, Anna
Publisher: name: F1000 Research Limited
Year: 2020

description: Biologists have long viewed both deoxyribonucleic acid (DNA) and proteins as languages that make up life and predicting protein function from sequence information is an active area of research. We studied the effectiveness of several natural language processing methods (text embedding and convolutional neural networks), including existing methods such as ProtVec, DeepFam and seq2vec, on protein family classification. Using two datasets from SwissProt and Clusters of Orthologous Groups (COGs), we found that low level features of protein sequences have the potential to contribute to powerful classifiers. Based on this analysis, we evaluated an additional simpler approach based on term frequency and logistic regression. This simpler method obtained an average accuracy of 0.98 on the binary classification task of determining whether a protein belongs to a particular family, which is competitive with the state-of-the-art approaches. This suggests that, at least in the binary case, protein family classification may be a simpler problem than expected. Further, we found that methods that extract low level features can be powerful enough to classify proteins with reasonable accuracy.
Adversarial Approximate Inference for Speech to Electroglottograph Conversion
Creators: name: P., Prathosh A.
name: Srivastava, Varun
name: Mishra, Mayank
Publisher: name: arXiv
Year: 2019
Subjects: subject: Audio and Speech Processing (eess.AS)
subject: Machine Learning (cs.LG)
subject: Sound (cs.SD)
subject: Machine Learning (stat.ML)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Speech produced by human vocal apparatus conveys substantial non-semantic information including the gender of the speaker, voice quality, affective state, abnormalities in the vocal apparatus etc. Such information is attributed to the properties of the voice source signal, which is usually estimated from the speech signal. However, most of the source estimation techniques depend heavily on the goodness of the model assumptions and are prone to noise. A popular alternative is to indirectly obtain the source information through the Electroglottographic (EGG) signal that measures the electrical admittance around the vocal folds using dedicated hardware. In this paper, we address the problem of estimating the EGG signal directly from the speech signal, devoid of any hardware. Sampling from the intractable conditional distribution of the EGG signal given the speech signal is accomplished through optimization of an evidence lower bound. This is constructed via minimization of the KL-divergence between the true and the approximated posteriors of a latent variable learned using a deep neural auto-encoder that serves an informative prior. We demonstrate the efficacy of the method at generating the EGG signal by conducting several experiments on datasets comprising multiple speakers, voice qualities, noise settings and speech pathologies. The proposed method is evaluated on many benchmark metrics and is found to agree with the gold standard while proving better than the state-of-the-art algorithms on a few tasks such as epoch extraction.
description: Submitted to IEEE/ACM Transactions on Audio, Speech and Language Processing
Quasinormal modes of black holes in a toy-model for cumulative quantum gravity
Creators: name: Barrau, Aurélien
name: Martineau, Killian
name: Martinon, Jeremy
name: Moulin, Flora
Publisher: name: arXiv
Year: 2019
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The idea that quantum gravity effects might leak outside the horizon of a black hole has recently been intensively considered. In this study, we calculate the quasinormal modes as a function of the location and amplitude of a generic metric perturbation distorting to the Schwarzschild spacetime. We conclude on the possible observability of quantum metric corrections by current and future gravitational wave experiments.
Asymptotic approximations of the continuous Hahn polynomials and their zeros
Creators: name: Cao, Li-Hua
name: Li, Yu-Tian
name: Lin, Yu
Publisher: name: arXiv
Year: 2019
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics
subject: 41A60, 33C45

description: Asymptotic approximations for the continuous Hahn polynomials and their zeros as the degree grows to infinity are established via their three-term recurrence relation. The methods are based on the uniform asymptotic expansions for difference equations developed by Wang and Wong (\textit{Numer. Math.}, 2003) and the matching technique in the complex plane developed by Wang (\textit{J. Approx. Theory}, 2014).
description: 23 pages
Electronic and Optical Properties of Oligothiophene-F4TCNQ Charge-Transfer Complexes: The Role of Donor Conjugation Length
Creators: name: Valencia, Ana M.
name: Cocchi, Caterina
Publisher: name: arXiv
Year: 2019
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigate from first-principles many-body theory the role of the donor conjugation length in doped organic semiconductors forming charge-transfer complexes (CTCs) exhibiting partial charge transfer. We consider oligothiophenes (nT) with an even number of rings ranging from four to ten, doped by the strong acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ). The decrease of the electronic gaps upon increasing nT size is driven by the reduction of the ionization energy with the electron affinity remaining almost constant. The optical gaps exhibit a different trend, being at approximately the same energy regardless of the donor length. The first excitation retains the same oscillator strength and Frenkel-like character in all systems. While in 4T-F4TCNQ also higher-energy excitations preserve this nature, in CTCs with longer nT oligomers charge-transfer excitations and Frenkel excitons localized on the donor appear above the absorption onset. Our results offer important insight into the structure-property relations of CTCs, thus contributing to a deeper understanding of doped organic semiconductors.
description: Supporting Information available free of charge from the journal page
Translation of GDPR article 32 into effective privacy governance and management practices. A view on GDPR ambiguity, non-compliancy risks and effectiveness of ISO 27701:2019 as Privacy Management System
Creators: name: Kuijper, Nico J W
Publisher: name: Zenodo
Year: 2020
Subjects: GDPR
Privacy
ISO27701
Privacy governance
Privacy management
GDPR Violations
GDPR article 32
Security
DPO
DPA
PIMS
GDPRtEXT ontology,
principle-agent-problem
ISO 27701:2019

description: Many organizations seem to struggle to translate the GDPR legislation into specific and effective (data privacy) governance, management & operational activities. The GDPR Enforcement Tracker (Law firm C|M|S, 2020) reported that the European Data Privacy Authorities fined non-compliance with the GDPR (up to 03.2020) with a total cumulative fine of € 332.000.000, a substantial materialized risk. Organizations with a focus on privacy risk mitigation often turn to worldwide accepted standards for guidance.
 A new ISO standard that has been released in 2019, ISO 27701:2019, aims to deliver specific guidance for the setup of a PIMS (Privacy Information Management System). This context has led to the formulation of the main research question of this paper:
 What are the most violated GDPR articles/aspects in combination with the highest fines? What are the (perceived) risks, ambiguities, the required governance and (change) management activities of this most violated GDPR article and are these effectively addressed in ISO 27701 as Privacy Information Management System?
A Search For X-ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries
Creators: name: Getman, Konstantin V.
name: Broos, Patrick S.
name: Kospal, Agnes
name: Salter, Demerese M.
name: Garmire, Gordon P.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged sample of all 4 binaries the current X-ray data show an increasing average X-ray flux near periastron (at about 2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries can not be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.
description: Accepted for publication in The Astronomical Journal; 19 pages including 6 figures and 3 tables
A novel model for query expansion using pseudo-relevant web knowledge
Creators: name: Azad, Hiteshwar Kumar
name: Deepak, Akshay
Publisher: name: arXiv
Year: 2019
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: In the field of information retrieval, query expansion (QE) has long been used as a technique to deal with the fundamental issue of word mismatch between a user's query and the target information. In the context of the relationship between the query and expanded terms, existing weighting techniques often fail to appropriately capture the term-term relationship and term to the whole query relationship, resulting in low retrieval effectiveness. Our proposed QE approach addresses this by proposing three weighting models based on (1) tf-itf, (2) k-nearest neighbor (kNN) based cosine similarity, and (3) correlation score. Further, to extract the initial set of expanded terms, we use pseudo-relevant web knowledge consisting of the top N web pages returned by the three popular search engines namely, Google, Bing, and DuckDuckGo, in response to the original query. Among the three weighting models, tf-itf scores each of the individual terms obtained from the web content, kNN-based cosine similarity scores the expansion terms to obtain the term-term relationship, and correlation score weighs the selected expansion terms with respect to the whole query. The proposed model, called web knowledge based query expansion (WKQE), achieves an improvement of 25.89% on the MAP score and 30.83% on the GMAP score over the unexpanded queries on the FIRE dataset. A comparative analysis of the WKQE techniques with other related approaches clearly shows significant improvement in the retrieval performance. We have also analyzed the effect of varying the number of pseudo-relevant documents and expansion terms on the retrieval effectiveness of the proposed model.
description: 32 pages
Double-oracle sampling method for Stackelberg Equilibrium approximation in general-sum extensive-form games
Creators: name: Karwowski, Jan
name: Mańdziuk, Jacek
Publisher: name: arXiv
Year: 2019
Subjects: subject: Computer Science and Game Theory (cs.GT)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences
subject: I.2.8

description: The paper presents a new method for approximating Strong Stackelberg Equilibrium in general-sum sequential games with imperfect information and perfect recall. The proposed approach is generic as it does not rely on any specific properties of a particular game model. The method is based on iterative interleaving of the two following phases: (1) guided Monte Carlo Tree Search sampling of the Follower's strategy space and (2) building the Leader's behavior strategy tree for which the sampled Follower's strategy is an optimal response. The above solution scheme is evaluated with respect to expected Leader's utility and time requirements on three sets of interception games with variable characteristics, played on graphs. A comparison with three state-of-the-art MILP/LP-based methods shows that in vast majority of test cases proposed simulation-based approach leads to optimal Leader's strategies, while excelling the competitive methods in terms of better time scalability and lower memory requirements.
Nuclear Fusion in Laser-Driven Counter-Streaming Collisionless Plasmas
Creators: name: Zhang, Xiaopeng
name: Zhao, Jiarui
name: Yuan, Dawei
name: Fu, Changbo
name: Bao, Jie
name: Chen, Liming
name: He, Jianjun
name: Hou, Long
name: Li, Liang
name: Li, Yanfei
name: Li, Yutong
name: Liao, Guoqiang
name: Rhee, Yongjoo
name: Sun, Yang
name: Xu, Skiwei
name: Zhao, Gang
name: Zhu, Baojun
name: Zhu, Jianqiang
name: Zhang, Zhe
name: Zhang, Jie
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: Nuclear fusion reactions are the most important processes in nature to power stars and produce new elements, and lie at the center of the understanding of nucleosynthesis in the universe. It is critically important to study the reactions in full plasma environments that are close to true astrophysical conditions. By using laser-driven counter-streaming collisionless plasmas, we studied the fusion D$+$D$\rightarrow n +^3$He in a Gamow-like window around 27 keV. The results show that astrophysical nuclear reaction yield can be modulated significantly by the self-generated electromagnetic fields and the collective motion of the plasma. This plasma-version mini-collider may provide a novel tool for studies of astrophysics-interested nuclear reactions in plasma with tunable energies in earth-based laboratories.
description: 5 pages; 4figures
Prioritized Garbage Collection: Explicit GC Support for Software Caches
Creators: name: Nunez, Diogenes
name: Guyer, Samuel Z.
name: Berger, Emery D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Programming Languages (cs.PL)
subject: FOS: Computer and information sciences
subject: D.3.4

description: Programmers routinely trade space for time to increase performance, often in the form of caching or memoization. In managed languages like Java or JavaScript, however, this space-time tradeoff is complex. Using more space translates into higher garbage collection costs, especially at the limit of available memory. Existing runtime systems provide limited support for space-sensitive algorithms, forcing programmers into difficult and often brittle choices about provisioning. This paper presents prioritized garbage collection, a cooperative programming language and runtime solution to this problem. Prioritized GC provides an interface similar to soft references, called priority references, which identify objects that the collector can reclaim eagerly if necessary. The key difference is an API for defining the policy that governs when priority references are cleared and in what order. Application code specifies a priority value for each reference and a target memory bound. The collector reclaims references, lowest priority first, until the total memory footprint of the cache fits within the bound. We use this API to implement a space-aware least-recently-used (LRU) cache, called a Sache, that is a drop-in replacement for existing caches, such as Google's Guava library. The garbage collector automatically grows and shrinks the Sache in response to available memory and workload with minimal provisioning information from the programmer. Using a Sache, it is almost impossible for an application to experience a memory leak, memory pressure, or an out-of-memory crash caused by software caching.
description: to appear in OOPSLA 2016
Origin of Giant Stellar Clumps in High-Redshift Galaxies
Creators: name: Meng, Xi
name: Gnedin, Oleg Y.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We examine the nature of kpc-scale clumps seen in high-redshift galaxies using a suite of cosmological simulations of galaxy formation. We identify rest-frame UV clumps in mock HST images smoothed to 500 pc resolution, and compare them with the intrinsic 3D clumps of young stars identified in the simulations with 100 pc resolution. According to this comparison, we expect that the stellar masses of the observed clumps are overestimated by as much as an order of magnitude, and that the sizes of these clumps are also overestimated by factor of several, due to a combination of spatial resolution and projection. The masses of young stars contributing most of the UV emission can also be overestimated by factor of a few. We find that most clumps of young stars present in a simulation at one time dissolve on a timescale shorter than $\sim$150 Myr. Some clumps with dense cores can last longer but eventually disperse. Most of the clumps are not bound structures, with virial parameter $α_{\rm vir}$ > 1. We find similar results for clumps identified in mock maps of H$α$ emission measure. We examine the predictions for effective clump sizes from the linear theory of gravitational perturbations and conclude that they are inconsistent with being formed by global disc instabilities. Instead, the observed clumps represent random projections of multiple smaller star-forming regions.
description: 13 pages, 5 figures, accepted for publication in MNRAS
Analytic solutions for links and triangles distributions in finite Barabási-Albert networks
Creators: name: Ferreira, Ricardo M.
name: de Almeida, Rita M. C.
name: Brunnet, Leonardo G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Barabási-Albert model describes many different natural networks, often yielding sensible explanations to the subjacent dynamics. However, finite size effects may prevent from discerning among different underlying physical mechanisms and from determining whether a particular finite system is driven by Barabási-Albert dynamics. Here we propose master equations for the evolution of the degrees, links and triangles distributions, solve them both analytically and by numerical iteration, and compare with numerical simulations. The analytic solutions for all these distributions predict the network evolution for systems as small as 100 nodes. The analytic method we developed is applicable for other classes of networks, representing a powerful tool to investigate the evolution of natural networks.
title: The extended atmospheres of red supergiants
Creators: name: Gonzalez I Tora, G
Publisher: name: Liverpool John Moores University
Year: 2023

description: Red supergiants (RSGs) are evolved massive stars in a stage preceding core-collapse supernova. Investigating evolved-phases of these stars is key to understanding the cosmic matter cycle of our Universe, since they enrich the cosmos with newly formed elements. The work shown in this thesis has two main focuses: one of these aims is to probe the temperature dependence of RSGs on metallicity. In context, the temperatures of RSGs are thought to be a manifestation of the Hayashi limit, which fixes the minimum effective temperature a star can have while still maintaining hydrostatic equilibrium. The Hayashi limit is expected to depend on metallicity (Z) in such a way that lower-Z RSGs are warmer. This prediction could be tested by studying the average effective temperatures of RSGs in galaxies with different metallicities. We investigate the Z-dependence of the Hayashi limit by analysing RSGs in the low-Z galaxy Wolf-Lundmark-Mellote (WLM), and compare with the RSGs in the higher-Z environments of the Small Magellanic Cloud (SMC) and Large Magellanic Cloud (LMC). We find a correlation between metallicity and the observed effective temperatures. We also compare the observations with evolutionary models, and find that while the trend is similar, there is a shift between observations and model predictions. This mismatch between observations and models could be due to wrong assumptions in the description of convection for massive stars. Secondly, the work in this thesis succeeds on modelling the spatially extended atmospheres of RSGs, where the mass loss is initiated, by plugging in the effect of a stellar wind in a stellar structure model. The physical processes that extend the atmospheres of RSGs are still not fully understood, and remain one of the key questions in stellar astrophysics. In this thesis, we propose a new 1D method to study the extended atmospheres of these cold stars, by adding the effect of a semi-empirical stellar wind based on observations of Betelgeuse. We then can compute the intensities, spectral energy distributions and visibilities matching the observations for the different instruments in the Very Large Telescope Interferometer (VLTI). Specifically, the work first discusses the robustness of our results when comparing with the atmospheric structure of HD 56879 and V602 Car of published VLTI/AMBER data, comprising the wavelength range of $1.8<\lambda<2.5\,\mu$m. Then, we also compare our extended model to newly acquired data of AH Sco, KW Sgr, V602 Car, CK Car and V460 Car with the instruments VLTI/GRAVITY and MATISSE, that comprise a broader wavelength range ($1.8<\lambda<13\,\mu$m). This later work represents the most complete spectro-interferometric study up to date of RSGs. We find that our model can accurately match these observations for the first time, showing the enormous potential of this methodology to reproduce extended atmospheres of RSGs and to constrain temperature and density stratifications as well as mass-loss rates.
Vacuum energy of the Bukhvostov-Lipatov model
Creators: name: Bazhanov, Vladimir V.
name: Lukyanov, Sergei L.
name: Runov, Boris A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Bukhvostov and Lipatov have shown that weakly interacting instantons and anti-instantons in the $O(3)$ non-linear sigma model in two dimensions are described by an exactly soluble model containing two coupled Dirac fermions. We propose an exact formula for the vacuum energy of the model for twisted boundary conditions, expressing it through a special solution of the classical sinh-Gordon equation. The formula perfectly matches predictions of the standard renormalized perturbation theory at weak couplings as well as the conformal perturbation theory at short distances. Our results also agree with the Bethe ansatz solution of the model. A complete proof the proposed expression for the vacuum energy based on a combination of the Bethe ansatz techniques and the classical inverse scattering transform method is presented in the second part of this work [40].
description: 28 pages, 10 figures
A Generic Metaheuristic Approach to Sequential Security Games
Creators: name: Żychowski, Adam
name: Mańdziuk, Jacek
Publisher: name: arXiv
Year: 2019
Subjects: subject: Computer Science and Game Theory (cs.GT)
subject: FOS: Computer and information sciences

description: The paper introduces a generic approach to solving Sequential Security Games (SGs) which utilizes Evolutionary Algorithms. Formulation of the method (named EASG) is general and largely game-independent, which allows for its application to a wide range of SGs with just little adjustments addressing game specificity. Comprehensive experiments performed on 3 different types of games (with 300 instances in total) demonstrate robustness and stability of EASG, manifested by repeatable achieving optimal or near-optimal solutions in the vast majority of the cases. The main advantage of EASG is time efficiency. The method scales visibly better than state-of-the-art approaches and consequently can be applied to SG instances which are beyond capabilities of the existing methods. Furthermore, due to anytime characteristics, EASG is very well suited for time-critical applications, as the method can be terminated at any moment and still provide a reasonably good solution - the best one found so far.
Shubnikov-de Haas oscillations and electronic correlations in the layered organic metal $κ$-(BETS)$_2$Mn[N(CN)$_2$]$_3$
Creators: name: Kartsovnik, M. V.
name: Zverev, V. N.
name: Biberacher, W.
name: Simonov, S. V.
name: Sheikin, I.
name: Kushch, N. D.
name: Yagubskii, E. B.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We present magnetoresistance studies of the quasi-two-dimensional organic conductor $κ$-(BETS)$_2$Mn[N(CN)$_2$]$_3$, where BETS stands for bis\-(ethylene\-dithio)\-tetra\-selena\-fulvalene. Under a moderate pressure of 1.4\,kbar, required for stabilizing the metallic ground state, Shubnikov - de Haas oscillations, associated with a classical and a magnetic-breakdown cyclotron orbits on the cylindrical Fermi surface, have been found at fields above 10\,T. The effective cyclotron masses evaluated from the temperature dependence of the oscillation amplitudes reveal strong renormalization due to many-body interactions. The analysis of the relative strength of the oscillations corresponding to the different orbits and its dependence on magnetic field suggests an enhanced role of electron-electron interactions on flat parts of the Fermi surface.
description: 6 pages, 4 figures
Fast non-convex low-rank matrix decomposition for separation of potential field data using minimal memory
Creators: name: Zhu, Dan
name: Renaut, Rosemary
name: Li, Hongwei
name: Liu, Tianyou
Publisher: name: arXiv
Year: 2019
Subjects: subject: Geophysics (physics.geo-ph)
subject: Numerical Analysis (math.NA)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 65F22, 65F55, 86A20

description: A fast non-convex low-rank matrix decomposition method for potential field data separation is proposed. The singular value decomposition of the large size trajectory matrix, which is also a block Hankel matrix, is obtained using a fast randomized singular value decomposition algorithm in which fast block Hankel matrix-vector multiplications are implemented with minimal memory storage. This fast block Hankel matrix randomized singular value decomposition algorithm is integrated into the \texttt{Altproj} algorithm, which is a standard non-convex method for solving the robust principal component analysis optimization problem. The improved algorithm avoids the construction of the trajectory matrix. Hence, gravity and magnetic data matrices of large size can be computed. Moreover, it is more efficient than the traditional low-rank matrix decomposition method, which is based on the use of an inexact augmented Lagrange multiplier algorithm. The presented algorithm is also robust and, hence, algorithm-dependent parameters are easily determined. The improved and traditional algorithms are contrasted for the separation of synthetic gravity and magnetic data matrices of different sizes. The presented results demonstrate that the improved algorithm is not only computationally more efficient but it is also more accurate. Moreover, it is possible to solve far larger problems. As an example, for the adopted computational environment, matrices of sizes larger than $205 \times 205$ generate "out of memory" exceptions with the traditional method, but a matrix of size $2001\times 2001$ can be calculated in $1062.29$s with the new algorithm. Finally, the improved method is applied to separate real gravity and magnetic data in the Tongling area, Anhui province, China. Areas which may exhibit mineralizations are inferred based on the separated anomalies.
Hermite-Hadamard and Hermite-Hadamard-Fejér type Inequalities for Generalized Fractional Integrals
Creators: name: Chen, Hua
name: Katugampola, Udita N.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics
subject: 26A33, 26D10, 26D15

description: In this paper we obtain the Hermite-Hadamard and Hermite-Hadamard-Fejér type inequalities for fractional integrals which generalize the two familiar fractional integrals namely, the Riemann-Liouville and the Hadamard fractional integrals into a single form. We prove that, in most cases, we obtain the Riemann--Liouville and the Hadamard equivalence just by taking limits when a parameter $ρ\rightarrow 1$ and $ρ\rightarrow 0^+$, respectively.
description: Accepted Manuscript. 14 pages, Journal of Mathematical Analysis and Applications (2016)
A Tutorial and Open Source Software for the Efficient Evaluation of Gravity and Magnetic Kernels
Creators: name: Hogue, Jarom D
name: Renaut, Rosemary A
name: Vatankhah, Saeed
Publisher: name: arXiv
Year: 2019
Subjects: subject: Numerical Analysis (math.NA)
subject: Computational Engineering, Finance, and Science (cs.CE)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: Fast computation of three-dimensional gravity and magnetic forward models is considered. Measurement data is assumed to be obtained on a uniform grid which is staggered with respect to the discretization of the parameter volume. Then, the resulting kernel sensitivity matrices exhibit block-Toeplitz Toeplitz-block (BTTB) structure. These matrices are symmetric for the gravity problem but non-symmetric for the magnetic problem. In each case, the structure facilitates fast forward computation using two-dimensional fast Fourier transforms. The construction of the kernel matrices and the application of the transform for fast forward multiplication, for each problem, is carefully described. But, for purposes of comparison with the transform approach, the generation of the unique entries that define a given kernel matrix is also explained. It is also demonstrated how the matrices, and hence transforms, are adjusted when padding around the volume domain is introduced. The transform algorithms for fast forward matrix multiplication with the sensitivity matrix and its transpose, without the direct construction of the relevant matrices, are presented. Numerical experiments demonstrate the significant reduction in computation time that is achieved using the transform implementation. Moreover, it becomes feasible, both in terms of reduced memory requirements and computational time, to implement the transform algorithms for large three-dimensional volumes. All presented algorithms, including with variable padding, are coded for optimal memory, storage and computation as an open source MATLAB code which can be adapted for any convolution kernel which generates a BTTB matrix. This work, therefore, provides a general tool for the efficient simulation of gravity and magnetic field data, as well as any formulation which admits a sensitivity matrix with the required structure.
Improving the frequency response of Savitzky-Golay filters via colored-noise models
Creators: name: Kennedy, Hugh L
Publisher: name: arXiv
Year: 2019
Subjects: subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Savitzky-Golay (SG) filters are finite impulse response (FIR) realizations of least-squares polynomial regression and they are widely used for filtering (e.g. smoothing, interpolating, predicting, differentiating) and processing (e.g. detecting and classifying) non-stationary signals in non-Gaussian noise. For such inputs, the Wiener filter is biased and the Kalman filter is sub-optimal. Sequentially-correlated (i.e. colored) noise models are an integral part of the Wiener filter and an optional addition to the Kalman filter; however, their use in SG-filters has been overlooked in recent times. It is shown here that colored (wide-band and narrow-band) noise models are readily incorporated into a standard SG-filter and that this also addresses the well-known deficiency of their poor frequency-selectivity/configurability. A wide-band noise model sets the main-lobe/side-lobe width/height and provides physical justification for band-limited design procedures described elsewhere. The proposed narrow-band noise model, with arbitrarily placed side-lobe nulls, has the potential to outperform other SG filters when sinusoidal interferers of known frequency are present. The utility of these whitened SG-filters is illustrated in a hypothetical pulse/peak-detection application using a test statistic that is shaped by the noise model.
description: Fixed a typo in Equation 4b that appears in the published version
First multicolour polarimetry of TeV gamma-ray binary HESS J0632+057 close to periastron passage
Creators: name: Yudin, R. V.
name: Potter, S. B.
name: Townsend, L. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present the results of UBVRI polarimetry of the TeV gamma-ray binary HESS J0632+057 obtained on 2015 March 24 (JD 2457106) and 2015 December 12 (JD 2457369). The detected polarisation values of HESS J0632+057, just after periastron passage (March 24), are higher than all previously published values (p(V) ~ 4.2%) and the position angle (theta ~ 171-172 degrees) is also different by ~6-10 degrees from previously published values. The data obtained just before the subsequent periastron passage (December 12) show statistically lower polarisation in all photometric bands (p(V) ~ 3.9%) and a different position angle theta ~ 167-168 degrees. From observations of a nearby field star, the interstellar component of the measured polarisation was estimated as p_is(V) ~ 0.65% and theta_is ~ 153 degrees. This estimate was used with the previous "V"-band estimation by "field-stars method" (p(V) ~ 2% and theta_is ~ 165 degrees) of Yudin (2014) to identify the wavelength dependence of the intrinsic polarisation in HESS J0632+057. It was found that after subtraction of the interstellar component (for both p_is estimates), the wavelength dependence of the intrinsic polarisation in HESS J0632+057 is essentially flat. We propose that the formation of an additional source of polarisation or some perturbation of circumstellar material at this orbital phase can explain the changes in the level of polarisation in HESS J0632+057 close to periastron passage.
description: 7 pages, 4 figures, Accepted for publication in MNRAS on 2016 October 14
Trapped arrays of alkaline earth Rydberg atoms in optical tweezers
Creators: name: Wilson, Jack
name: Saskin, Samuel
name: Meng, Yijian
name: Ma, Shuo
name: Dilip, Rohit
name: Burgers, Alex
name: Thompson, Jeff
Publisher: name: arXiv
Year: 2019
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: Neutral atom qubits with Rydberg-mediated interactions are a leading platform for developing large-scale coherent quantum systems. In the majority of experiments to date, the Rydberg states are not trapped by the same potential that confines ground state atoms, resulting in atom loss and constraints on the achievable interaction time. In this work, we demonstrate that the Rydberg states of an alkaline earth atom, ytterbium, can be stably trapped by the same red-detuned optical tweezer that also confines the ground state, by leveraging the polarizability of the Yb$^+$ ion core. Using the previously unobserved \tripletS series, we demonstrate trapped Rydberg atom lifetimes exceeding $100\,μ$s, and observe no evidence of auto- or photo-ionization from the trap light for these states. We measure a coherence time of $T_2 = 59$ $μ$s between two Rydberg levels, exceeding the 28 $μ$s lifetime of untrapped Rydberg atoms under the same conditions. These results are promising for extending the interaction time of Rydberg atom arrays for quantum simulation and computing, and are vital to capitalize on the extended Rydberg lifetimes in circular states or cryogenic environments.
description: edited references