cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Generalized L$_p$-norm joint inversion of gravity and magnetic data using cross-gradient constraint
Creators: name: Vatankhah, Saeed
name: Liu, Shuang
name: Renaut, Rosemary A.
name: Hu, Xiangyun
name: Gharloghi, Mostafa
Publisher: name: arXiv
Year: 2020
Subjects: subject: Geophysics (physics.geo-ph)
subject: Numerical Analysis (math.NA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: A generalized unifying approach for $L_{p}$-norm joint inversion of gravity and magnetic data using the cross-gradient constraint is presented. The presented framework incorporates stabilizers that use $L_{0}$, $L_{1}$, and $L_{2}$-norms of the model parameters, and/or the gradient of the model parameters. Furthermore, the formulation is developed from standard approaches for independent inversion of single data sets, and, thus, also facilitates the inclusion of necessary model and data weighting matrices that provide, for example, depth weighting and imposition of hard constraint data. The developed efficient algorithm can, therefore, be employed to provide physically-relevant smooth, sparse, or blocky target(s) which are relevant to the geophysical community. Here, the nonlinear objective function, that describes the inclusion of all stabilizing terms and the fit to data measurements, is minimized iteratively by imposing stationarity on the linear equation that results from applying linearization of the objective function about a starting model. To numerically solve the resulting linear system, at each iteration, the conjugate gradient algorithm is used. The general framework is then validated for three-dimensional synthetic models for both sparse and smooth reconstructions, and the results are compared with those of individual gravity and magnetic inversions. It is demonstrated that the presented joint inversion algorithm is practical and significantly improves reconstructed models obtained by independent inversion.
Shared information between residues is sufficient to detect pair-wise epistasis in a protein
Creators: name: Gupta, A.
name: Adami, C.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: FOS: Biological sciences

description: In a comment on our manuscript "Strong selection significantly increases epistatic interactions in the long-term evolution of a protein", Dr. Crona challenges our assertion that shared entropy (that is, information) between two residues implies epistasis between those residues, by constructing an explicit example of three loci (say A, B, and C), where A and B are epistatically linked (leading to shared entropy between A and B), and A and C also depend epistatically (leading to shared entropy between A and C), so that loci B and C are correlated (share entropy).
description: 4 pages, 1 figure. To appear in PLoS Genetics
Suppression of lattice thermal conductivity by mass-conserving cation mutation in multi-component semiconductors
Creators: name: Shibuya, Taizo
name: Skelton, Jonathan M.
name: Jackson, Adam J.
name: Yasuoka, Kenju
name: Togo, Atsushi
name: Tanaka, Isao
name: Walsh, Aron
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: In semiconductors almost all heat is conducted by phonons (lattice vibrations), which is limited by their quasi-particle lifetimes. Phonon-phonon interactions represent scattering mechanisms that produce thermal resistance. In thermoelectric materials, this resistance due to anharmonicity should be maximised for optimal performance. We use a first-principles lattice-dynamics approach to explore the changes in lattice dynamics across an isostructural series where the average atomic mass is conserved: ZnS to CuGaS$_2$ to Cu$_2$ZnGeS$_4$. Our results demonstrate an enhancement of phonon interactions in the multernary materials, and confirm that lattice thermal conductivity can be controlled independently of the average mass and local coordination environments.
description: 13 pages, 4 figures
Revista JRG de Estudos Acadêmicos
Creators: name: Gonçalves, Jonas Rodrigo
Publisher: name: Zenodo
Year: 2018

description: A Revista JRG de Estudos Acadêmicos é um periódico científico, eletrônico, totalmente gratuito, de acesso aberto, de periodicidade semestral com publicação contínua, que recebe submissões de trabalhos inéditos e em fluxo contínuo, nos idiomas Português, Espanhol ou Inglês. A “Revista JRG de Estudos Acadêmicos” tem por missão contribuir para a evolução do conhecimento no campo das ciências em geral, que envolvam os diversos campos interdisciplinares e multidisciplinares do conhecimento científico, contemplando aspectos relativos às organizações sociais e empresariais, públicas e privadas, e outras questões de relevo social. Objetiva-se, com este periódico, divulgar a produção científica dos discentes de stricto sensu, docentes, pesquisadores, cientistas e demais membros da comunidade acadêmica instituições do Brasil e do exterior, que contribuam para promover o debate de ideias e estimular a pesquisa científica. Objetivando-se também manter a interlocução social sempre realizada pela Editora JRG, mantenedora desta revista acadêmica, o periódico, ainda, divulgará estudos, entrevistas e pesquisas desenvolvidas no âmbito das atividades de extensão, em que a parceria entre a Instituição e a comunidade se torne cada vez mais intensa, possibilitando uma real integração entre a comunidade acadêmica e a sociedade em geral. A “Revista JRG de Estudos Acadêmicos” poderá acrescentar, além das edições normais, números temáticos e especiais, enquanto números-extra, incorporando novas seções, conforme desdobramentos da política editorial. O Conselho Editorial da Revista é composto de maneira exógena por professores de Ensino Superior de diversas universidades, centros universitários e faculdades, envolvendo coordenadores de cursos e pesquisadores. A Instituição espera que esta publicação se torne um instrumento dinâmico de reflexão e debate, contribuindo para a solução dos problemas sociais. Revista JRG de Estudos Acadêmicos
Influence of electron-neutral elastic collisions on the instability of an ion-contaminated cylindrical electron cloud: 2D3V PIC-with-MCC simulations
Creators: name: Sengupta, Meghraj
name: Ganesh, Rajaraman
Publisher: name: arXiv
Year: 2016
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: This paper is a simulation based investigation of the effect of elastic collisions and effectively elastic-like excitation collisions between electrons and background neutrals on the dynamics of a cylindrically trapped electron cloud that also has an ion contaminant mixed in it. Effects of the collisions on the instability are evident from alteration in the growth rate and energetics of the ion resonance instability caused by the presence of background neutrals as compared to a vacuum background. Further in order to understand if the non-ionizing collisions can independently be a cause of destabilization of an electron cloud, a second set of numerical experiments were performed with pure electron plasmas making non-ionizing collisions with different densities of background neutrals. These experiments reveal that the nature of potential energy extraction from the electron cloud by the non-ionizing collisions is not similar to the potential energy extraction of other destabilizing processes \textit{e.g.} a resistive wall instability. This difference in the energy extraction process renders these non-ionizing collisions incapable of independently triggering an instability of the cloud.
A Caputo fractional derivative of a function with respect to another function
Creators: name: Almeida, Ricardo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics

description: In this paper we consider a Caputo type fractional derivative with respect to another function. Some properties, like the semigroup law, a relationship between the fractional derivative and the fractional integral, Taylor's Theorem, Fermat's Theorem, etc, are studied. Also, a numerical method to deal with such operators, consisting in approximating the fractional derivative by a sum that depends on the first-order derivative, is presented. Relying on examples, we show the efficiency and applicability of the method. Finally, an application of the fractional derivative, by considering a Population Growth Model, and showing that we can model more accurately the process using different kernels for the fractional operator is provided.
description: This is a preprint of a paper whose final and definite form will be published in the journal Communications in Nonlinear Science and Numerical Simulation
Joint spectra of the tensor product representation of the direct sum of two solvable Lie algebras
Creators: name: Boasso, Enrico
Publisher: name: arXiv
Year: 2016
Subjects: subject: Functional Analysis (math.FA)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 47A13, 47L10 (Primary), 47A53, 17B30 (Secondary)

description: Given two complex Banach spaces $X_1$ and $X_2$, a tensor product $X_1\tilde{\otimes} X_2$ of $X_1$ and $X_2$ in the sense of [14], two complex solvable finite dimensional Lie algebras $L_1$ and $L_2$, and two representations $ρ_i\colon L_i\to {\rm L}(X_i)$ of the algebras, $i=1$, $2$, we consider the Lie algebra $L=L_1\times L_2$, and the tensor product representation of $L$, $ρ\colon L\to {\rm L}(X_1\tilde{\otimes}X_2)$, $ρ=ρ_1\otimes I +I\otimes ρ_2$. In this work we study the Słodkowski and the split joint spectra of the representation $ρ$, and we describe them in terms of the corresponding joint spectra of $ρ_1$ and $ρ_2$. Moreover, we study the essential Słodkowski and the essential split joint spectra of the representation $ρ$, and we describe them by means of the corresponding joint spectra and the corresponding essential joint spectra of $ρ_1$ and $ρ_2$. In addition, with similar arguments we describe all the above-mentioned joint spectra for the multiplication representation in an operator ideal between Banach spaces in the sense of [14]. Finally, we consider nilpotent systems of operators, in particular commutative, and we apply our descriptions to them.
description: original research article, 46 pages
A partially overdetermined problem in domains with partial umbilical boundary in space forms
Creators: name: Guo, Jinyu
name: Xia, Chao
Publisher: name: arXiv
Year: 2020
Subjects: subject: Analysis of PDEs (math.AP)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: In the first part of this paper, we consider a partially overdetermined mixed boundary value problem in space forms and generalize the main result in \cite{GX} into the case of general domains with partial umbilical boundary in space forms. Precisely, we prove that a partially overdetermined problem in a domain with partial umbilical boundary admits a solution if and only if the rest part of the boundary is also part of an umbilical hypersurface. In the second part of this paper, we prove a Heintze-Karcher-Ros type inequality for embedded hypersurfaces with free boundary lying on a horosphere or an equidistant hypersurface in the hyperbolic space. As an application, we show Alexandrov type theorem for constant mean curvature hypersurfaces with free boundary in these settings.
description: 22 pages,4 figures,final version,to appear in Adv.Calc.Var
Sample Efficient Optimization for Learning Controllers for Bipedal Locomotion
Creators: name: Antonova, Rika
name: Rai, Akshara
name: Atkeson, Christopher G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Robotics (cs.RO)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Learning policies for bipedal locomotion can be difficult, as experiments are expensive and simulation does not usually transfer well to hardware. To counter this, we need al- gorithms that are sample efficient and inherently safe. Bayesian Optimization is a powerful sample-efficient tool for optimizing non-convex black-box functions. However, its performance can degrade in higher dimensions. We develop a distance metric for bipedal locomotion that enhances the sample-efficiency of Bayesian Optimization and use it to train a 16 dimensional neuromuscular model for planar walking. This distance metric reflects some basic gait features of healthy walking and helps us quickly eliminate a majority of unstable controllers. With our approach we can learn policies for walking in less than 100 trials for a range of challenging settings. In simulation, we show results on two different costs and on various terrains including rough ground and ramps, sloping upwards and downwards. We also perturb our models with unknown inertial disturbances analogous with differences between simulation and hardware. These results are promising, as they indicate that this method can potentially be used to learn control policies on hardware.
description: To appear in International Conference on Humanoid Robots (Humanoids '2016), IEEE-RAS. (Rika Antonova and Akshara Rai contributed equally)
Monogamy constraints on entanglement of four-qubit pure states
Creators: name: Sharma, S. Shelly
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We report a set of monogamy constraints on one-tangle, two-tangles, three-tangles and four-way correlations of a general four-qubit pure state. It is found that given a two-qubit marginal state $ρ$ of a four qubit pure state $\left\vert Ψ_{4}\right\rangle $, the non-Hermitian matrix $ρ\widetildeρ$ where $\widetildeρ$ $=\left( σ_{y} \otimesσ_{y}\right) ρ^{\ast}\left( σ_{y}\otimesσ_{y}\right) $, contains information not only about the entanglement properties of the two-qubits in state $ρ$ but also about three tangles involving the selected pair as well as four-way correlations of the pair of qubits in $\left\vert Ψ_{4}\right\rangle $. To extract information about tangles of a four-qubit state $\left\vert Ψ_{4}\right\rangle $, the coefficients in the characteristic polynomial of matrix $ρ\widetildeρ$ are analytically expressed in terms of $2\times2$ matrices of state coefficients. Four-tangles distinguish between different types of entangled four-qubit pure states.
description: 20 pages, Three figures, An expanded new version with additional sections on classification of four-qubit states and entanglement transfer. This version is an application to four-qubits of the general formalism reported in a recently uploaded letter "Beyond the entanglement of qubit pair in a mixed state"
title: Revista Portuguesa de Investigação Educacional, 2020: Especial
title: Especial
titleType: AlternativeTitle
Creators: name: Revista Portuguesa De Investigação Educacional
Publisher: name: Revista Portuguesa de Investigação Educacional
Year: 2020

description: Apresentação...11-13 A relação pedagógica a partir do olhar de futuros professores: implicações do(s) ambiente(s) de ensino e aprendizagem...14-35 Alterando a organização pedagógica da escola. Um caso em estudo...36-56 As salas de aula nas escolas modernizadas pela Parque Escolar. Entre um voluntarismo retórico e uma míngua de efeitos nos processos educativos...57-84 As plataformas informáticas como instrumentos de regulação da organização e gestão escolar...85-110 Contributos para o desenvolvimento de um sistema de auto e multirregulação educativa...111-143 Culturas escolares, lideranças e resultados: apresentação de resultados de um estudo de caso duplo...144-171 Autonomia e flexibilidade curricular: quando as escolas são desafiadas pelo governo...172-192 Conceções sobre a supervisão pedagógica: prática(s) e teoria(s) de uma instituição pública...193-214 Fundamentalismo, complexidade e inclusão. Contributos para uma educação inclusiva...215-227 Managers as promoters of educational improvement...228-256 Caso ESCO turismo | projetos integradores & internacionais formar profissionais e cidadãos, melhorar o acesso às oportunidades de aprendizagem e fomentar o gosto pelo saber fora dos muros da escola...257-288
Giant amplification of noise in fluctuation-induced pattern formation
Creators: name: Biancalani, Tommaso
name: Jafarpour, Farshid
name: Goldenfeld, Nigel
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: The amplitude of fluctuation-induced patterns might be expected to be proportional to the strength of the driving noise, suggesting that such patterns would be difficult to observe in nature. Here, we show that a large class of spatially-extended dynamical systems driven by intrinsic noise can exhibit giant amplification, yielding patterns whose amplitude is comparable to that of deterministic Turing instabilities. The giant amplification results from the interplay between noise and non-orthogonal eigenvectors of the linear stability matrix, yielding transients that grow with time, and which, when driven by the ever-present intrinsic noise, lead to persistent large amplitude patterns. This mechanism provides a robust basis for fluctuation-induced biological pattern formation based on the Turing mechanism, without requiring fine tuning of diffusion constants.
Sampling Kaczmarz Motzkin Method for Linear Feasibility Problems: Generalization & Acceleration
Creators: name: Morshed, Md Sarowar
name: Islam, Md Saiful
name: Noor-E-Alam, Md.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: Randomized Kaczmarz (RK), Motzkin Method (MM) and Sampling Kaczmarz Motzkin (SKM) algorithms are commonly used iterative techniques for solving a system of linear inequalities (i.e., $Ax \leq b$). As linear systems of equations represent a modeling paradigm for solving many optimization problems, these randomized and iterative techniques are gaining popularity among researchers in different domains. In this work, we propose a Generalized Sampling Kaczmarz Motzkin (GSKM) method that unifies the iterative methods into a single framework. In addition to the general framework, we propose a Nesterov type acceleration scheme in the SKM method called as Probably Accelerated Sampling Kaczmarz Motzkin (PASKM). We prove the convergence theorems for both GSKM and PASKM algorithms in the $L_2$ norm perspective with respect to the proposed sampling distribution. Furthermore, we prove sub-linear convergence for the Cesaro average of iterates for the proposed GSKM and PASKM algorithms.From the convergence theorem of the GSKM algorithm, we find the convergence results of several well-known algorithms like the Kaczmarz method, Motzkin method and SKM algorithm. We perform thorough numerical experiments using both randomly generated and real-world (classification with support vector machine and Netlib LP) test instances to demonstrate the efficiency of the proposed methods. We compare the proposed algorithms with SKM, Interior Point Method (IPM) and Active Set Method (ASM) in terms of computation time and solution quality. In the majority of the problem instances, the proposed generalized and accelerated algorithms significantly outperform the state-of-the-art methods.
Citizen Science Installationen - Verbindung von analoger Öffentlichkeit und digitalem Labor
Creators: name: Wuensche, Hannes
Publisher: name: Zenodo
Year: 2018
Subjects: Citizen Science
Open Science
Digital Participation
Installation Art
Public

description: Das Konzept der Citizen Science Installationen verfolgt das Ziel Aufmerksamkeit für offene Wissenschaft zu schaffen und die Interaktion zwischen Bürger:innen und Forschenden im öffentlichen Raum zu ermöglichen. Dies wird erreicht, indem es eine Verbindung zwischen analoger Öffentlichkeit und digitalem Labor herstellt. Durch diese hybriden, analog-digitalen Räume gibt es Bürger:innen die Möglichkeit an Forschungsprozessen teilzunehmen sowie Forschungsdaten und Informationen zu erhalten.
description: This work has been funded by the Federal Ministry of Education and Research of Germany (BMBF) under grant no. 16DII111 ("Deutsches Internet-Institut").
Inflationary Dynamics Reconstruction via Inverse-Scattering Theory
Creators: name: Mastache, Jorge
name: Zago, Fernando
name: Kosowsky, Arthur
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The evolution of inflationary fluctuations can be recast as an inverse scattering problem. In this context, we employ the Gel'fand-Levitan method from inverse-scattering theory to reconstruct the evolution of both the inflaton field freeze-out horizon and the Hubble parameter during inflation. We demonstrate this reconstruction procedure numerically for a scenario of slow-roll inflation, as well as for a scenario which temporarily departs from slow-roll. The field freeze-out horizon is reconstructed from the accessible primordial scalar power spectrum alone, while the reconstruction of the Hubble parameter requires additional information from the tensor power spectrum. We briefly discuss the application of this technique to more realistic cases incorporating estimates of the primordial power spectra over limited ranges of scales and with specified uncertainties.
description: 10 pages, 7 figures
Periods and $(χ,b)$-factors of Cuspidal Automorphic Forms of Metaplectic Groups
Creators: name: Wu, Chenyan
Publisher: name: arXiv
Year: 2020
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: We give constraints on the existence of $(χ,b)$-factors in the global $A$-parameter of a genuine cuspidal automorphic representation $σ$ of a metaplectic group in terms of the invariant, lowest occurrence index, of theta lifts to odd orthogonal groups. We also give a refined result that relates the invariant, first occurrence index, to non-vanishing of period integrals of residues of Eisenstein series associated to the cuspidal datum $χ\otimesσ$. This complements our previous results for symplectic groups.
description: 35 pages. Clarifies the $L$-function for metaplectic group used. See Remark 2.2
Performance studies of MRPC prototypes for CBM
Creators: name: Deppner, I.
name: Herrmann, N.
name: Frühauf, J.
name: Kiš, M.
name: Lyu, P.
name: Loizeau, P. -A.
name: Shi, L.
name: Simon, C.
name: Wang, Y.
name: Xie, B.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Multi-gap Resistive Plate Chambers (MRPCs) with multi-strip readout are considered to be the optimal detector candidate for the Time-of-Flight (ToF) wall in the Compressed Baryonic Matter (CBM) experiment. In the R&D phase MRPCs with different granularities, low-resistive materials and high voltage stack configurations were developed and tested. Here, we focus on two prototypes called HD-P2 and THU-strip, both with strips of 27 cm$^2$ length and low-resistive glass electrodes. The HD-P2 prototype has a single-stack configuration with 8 gaps while the THU-strip prototype is constructed in a double-stack configuration with 2 $\times$ 4 gaps. The performance results of these counters in terms of efficiency and time resolution carried out in a test beam time with heavy-ion beam at GSI in 2014 are presented in this proceeding.
description: 7 pages, 6 figures, to be submitted to JINST
Nonlinear Power Method for Computing Eigenvectors of Proximal Operators and Neural Networks
Creators: name: Bungert, Leon
name: Hait-Fraenkel, Ester
name: Papadakis, Nicolas
name: Gilboa, Guy
Publisher: name: arXiv
Year: 2020
Subjects: subject: Spectral Theory (math.SP)
subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: 65H17, 47J10

description: Neural networks have revolutionized the field of data science, yielding remarkable solutions in a data-driven manner. For instance, in the field of mathematical imaging, they have surpassed traditional methods based on convex regularization. However, a fundamental theory supporting the practical applications is still in the early stages of development. We take a fresh look at neural networks and examine them via nonlinear eigenvalue analysis. The field of nonlinear spectral theory is still emerging, providing insights about nonlinear operators and systems. In this paper we view a neural network as a complex nonlinear operator and attempt to find its nonlinear eigenvectors. We first discuss the existence of such eigenvectors and analyze the kernel of ReLU networks. Then we study a nonlinear power method for generic nonlinear operators. For proximal operators associated to absolutely one-homogeneous convex regularization functionals, we can prove convergence of the method to an eigenvector of the proximal operator. This motivates us to apply a nonlinear method to networks which are trained to act similarly as a proximal operator. In order to take the non-homogeneity of neural networks into account we define a modified version of the power method. We perform extensive experiments for different proximal operators and on various shallow and deep neural networks designed for image denoising. Proximal eigenvectors will be used for geometric analysis of graphs, as clustering or the computation of distance functions. For simple neural nets, we observe the influence of training data on the eigenvectors. For state-of-the-art denoising networks, we show that eigenvectors can be interpreted as (un)stable modes of the network, when contaminated with noise or other degradations.
description: Accepted for publication in SIAM Journal on Imaging Sciences
Massive gauge particles versus Goldstone bosons in non-Hermitian non-Abelian gauge theory
Creators: name: Fring, Andreas
name: Taira, Takanobu
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We investigate the Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism for non-Hermitian field theories with local non-Abelian gauge symmetry in different regions of their parameter spaces. We demonstrate that the two aspects of the mechanism, that is giving mass to gauge vector bosons and at the same time preventing the existence of massless Goldstone bosons, remain to be synchronized in all regimes characterized by a modified CPT symmetry. In the domain of parameter space where the "would be Goldstone bosons" can be identified the gauge vector bosons become massive and the Goldstone bosons cease to exist. The mechanism is also in tact at the standard exceptional points. However, at the zero exceptional points, that is when the eigenvalues of the mass squared matrix vanish irrespective of the symmetry breaking, the mechanism breaks down as the Goldstone bosons can not be identified and the gauge vector bosons remain massless. This breakdown coincides with the vanishing of the CPT inner product of symmetry breaking vacua defined on the eigenvector space of mass squared matrix. We verify this behaviour for a theory with SU(N) symmetry in which the complex scalar fields are taken in the fundamental as well as in the adjoint representation.
description: 24 pages, 1 figure, extended version
Enhanced charge ordering transition in doped CaFeO3 through steric templating
Creators: name: Jiang, Lai
name: Saldana-Greco, Diomedes
name: Schick, Joseph T.
name: Rappe, Andrew M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report density functional theory (DFT) investigation of $B$-site doped CaFeO$_3$, a prototypical charge-ordered perovskite. At 290 K, CaFeO$_3$ undergoes a metal-insulator transition and a charge disproportionation reaction 2Fe$^{4+}$$\rightarrow$Fe$^{5+}$+Fe$^{3+}$. We observe that when Zr dopants occupy a (001) layer, the band gap of the resulting solid solution increases to 0.93 eV due to a 2D Jahn-Teller type distortion, where FeO$_6$ cages on the $xy$ plane elongate along $x$ and $y$ alternatively between neighboring Fe sites. Furthermore, we show that the rock-salt ordering of the Fe$^{5+}$ and Fe$^{3+}$ cations can be enhanced when the $B$-site dopants are arranged in a (111) plane due to a collective steric effect that facilitates the size discrepancy between the Fe$^{5+}$O$_6$ and Fe$^{3+}$O$_6$ octahedra and therefore gives rise to a larger band gap. The enhanced charge disproportionation in these solid solutions is verified by rigorously calculating the oxidation states of the Fe cations with different octahedral cage sizes. We therefore predict that the corresponding transition temperature will increase due to the enhanced charge ordering and larger band gap. The compositional, structural and electrical relationships exploited in this paper can be extended to a variety of perovskites and non-perovskite oxides providing guidance in structurally manipulating electrical properties of functional materials.
description: 16 pages, 8 figures
Eurodoc Statement on Open Science 2023
Creators: name: Dolinar, Maja
name: Dahle, Sebastian
name: Rutkowska, Joanna
name: Dengo, Nicola
name: Mueller, Katharina
name: Saugmann, Pil Maria
Publisher: name: Zenodo
Year: 2023
Subjects: Open Science

description: The principles of Open Science are an integral part of Eurodoc’s mission. Open Science is an evolving movement that challenges traditional research practices by transforming the way research and knowledge are produced, shared, and used. It involves making data publicly accessible, fostering public collaboration, encouraging creative use of digital technology in research endeavours as well as developing more efficient ways for researchers to share their work. Open Science promotes knowledge-sharing among researchers. By enabling open access to data, methods, tools, and results of scientific studies – regardless of field or origin – it provides invaluable opportunities for early career researchers (ECRs). Eurodoc advocates the transition to Open Science by raising awareness about Open Science initiatives, by making recommendations on the implementation of Open Science for higher education institutions, European institutions, and other international institutions, and by advocating for research assessment reform that aligns with Open Science principles. With increased access to data, resources, literature reviews and collaboration opportunities across geographic borders – Open Science empowers ECRs with the tools they need for success. Openness increases transparency while decreasing bias; it supports equitable and reproducible results that can be readily accessed by everyone interested. It also helps foster creativity and innovation within scientific circles as well as encourages cross-disciplinary interactions between diverse sources, which ultimately leads to more meaningful insights into a wide range of questions posed by society.
Superconducting Quantum Interference in Edge State Josephson Junctions
Creators: name: Galambos, Tamás Haidekker
name: Hoffman, Silas
name: Recher, Patrik
name: Klinovaja, Jelena
name: Loss, Daniel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study superconducting quantum interference in a Josephson junction linked via edge states in two-dimensional (2D) insulators. We consider two scenarios in which the 2D insulator is either a topological or a trivial insulator supporting one-dimensional (1D) helical or nonhelical edge states, respectively. In equilibrium, we find that the qualitative dependence of critical supercurrent on the flux through the junction is insensitive to the helical nature of the mediating states and can, therefore, not be used to verify the topological features of the underlying insulator. However, upon applying a finite voltage bias smaller than the superconducting gap to a relatively long junction, the finite-frequency interference pattern in the non-equilibrium transport current is qualitatively different for helical edge states as compared to nonhelical ones.
description: 5+13 pages, 7 figures, 3 tables
Social Sustainability in the Development of Service Robots
Creators: name: Kohl, Jonas Laurenz
name: Van Der Schoor, Michel Joop
name: Syré, Anne Magdalene
name: Göhlich, Dietmar
Publisher: name: Technische Universität Berlin
Year: 2020
Subjects: subject: 600 Technik, Technologie
subject: 620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
subject: 302 Soziale Interaktion
subject: sustainability
subject: case study
subject: design guidelines
subject: automation
subject: service robots

description: We introduce the concept of social sustainability, intertwined with ecological and economic aspects, to the field of service robots and comparable automation technology. It takes a first step towards a comprehensive guideline that operationalizes and applies social sustainability. By applying this guideline to the project MURMEL we offer a concept that collects and rates social key issues to visualize their individual importance. Social sustainability is an important and often overlooked aspect of sustainable technology development which should be considered in the early development phase.
Journée réseau Calames 2023 : actualités
Creators: name: Michel, Brigitte
name: Jestaz, Laure
name: Naddeo, Etienne
Publisher: name: Zenodo
Year: 2023
Subjects: Calames

description: Présentation réalisée lors de la Journée Réseau Calames 2023 "Le voyage des données", 16 juin 2023
Spherical Accretion of Matter by Charged Black Holes on f(T) Gravity
Creators: name: Rodrigues, Manuel E.
name: Junior, Ednaldo L. B.
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We studied the spherical accretion of matter by charged black holes on $f(T)$ Gravity. Considering the accretion model of a isentropic perfect fluid we obtain the general form of the Hamiltonian and the dynamic system for the fluid. We have analysed the movements of an isothermal fluid model with $p=ωe$ and where $p$ is the pressure and $e$ the total energy density. The analysis of the cases shows the possibility of spherical accretion of fluid by black holes, revealing new phenomena as cyclical movement inside the event horizon.
description: 12 pages, revtex4 format. arXiv admin note: text overlap with arXiv:1503.07427, arXiv:1503.07857, arXiv:1509.03267, arXiv:1501.00621
The potential role of NGC 205 in generating Andromeda's vast thin co-rotating plane of satellite galaxies
Creators: name: Angus, Garry W.
name: Coppin, Paul
name: Gentile, Gianfranco
name: Diaferio, Antonaldo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The Andromeda galaxy is observed to have a system of two large dwarf ellipticals and ~13 smaller satellite galaxies that are currently co-rotating in a thin plane, in addition to 2 counter-rotating satellite galaxies. We explored the consistency of those observations with a scenario where the majority of the co-rotating satellite galaxies originated from a subhalo group, where NGC 205 was the host and the satellite galaxies occupied dark matter sub-subhalos. We ran N-body simulations of a close encounter between NGC 205 and M31. In the simulations, NGC 205 was surrounded by massless particles to statistically sample the distribution of the sub-subhalos expected in a subhalo that has a mass similar to NGC 205. We made Monte Carlo samplings and found that, using a set of reference parameters, the probability of producing a thinner distribution of sub-subhalos than the observed NGC 205 + 15 smaller satellites (thus including the 2 counter-rotators, but excluding M32) increased from <1e-8 for the initial distribution to ~0.01 at pericentre. The probability of the simulated sub-subhalos occupying the locations of the observed co-rotating satellites in the line of sight velocity versus projected on-sky distance plane is at most 0.002 for 11 out of 13 satellites. Increasing the mass of M31 and the extent of the initial distribution of sub-subhalos gives a maximum probability of 0.004 for all 13 co-rotating satellites, but the probability of producing the thinness would drop to ~ 0.001.
description: 19 pages, 15 figures, to be published in MNRAS
A geometry-aware attention network for semantic segmentation of MLS point clouds
Creators: name: Wan, Jie
name: Xu, Yongyang
name: Qiu, Qinjun
name: Xie, Zhong
Publisher: name: Taylor & Francis
Year: 2022
Subjects: subject: Biophysics
subject: Space Science
subject: Neuroscience
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics

description: Semantic segmentation of mobile laser scanning (MLS) point clouds can provide meaningful 3 D semantic information of urban facilities for various applications. However, it still remains a challenge to extract accurate 3 D semantic information from MLS point cloud data due to its irregular 3 D geometric structure in a large-scale outdoor scene. To this end, this study develops a geometry-aware attention point network (GAANet) with geometric properties of the point cloud as a reference. Specifically, the proposed method first builds a graph-like region for each input point to establish the geometric correlation toward its neighbors for robustly descripting local geometry-aware features. Thereafter, the method introduces a novel multi-head attention mechanism to efficiently learn local discriminative features on the constructed graphs and a feature combination operation to capture both local and global geometric dependencies inside fused point features for significantly facilitating the segmentation of small or incomplete 3 D objects at point-level. Finally, an adaptive loss function is appended to handle class imbalance for the overall performance improvement. The validation experiments on two challenging benchmarks demonstrate the effectiveness and powerful generation ability of the proposed method, which achieves state-of-the-art performance with mean IoU of 65.09% and 95.20% in the Toronto-3D and Oakland 3-D MLS dataset, respectively.
On the Effect of Dropping Layers of Pre-trained Transformer Models
Creators: name: Sajjad, Hassan
name: Dalvi, Fahim
name: Durrani, Nadir
name: Nakov, Preslav
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computation and Language (cs.CL)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Transformer-based NLP models are trained using hundreds of millions or even billions of parameters, limiting their applicability in computationally constrained environments. While the number of parameters generally correlates with performance, it is not clear whether the entire network is required for a downstream task. Motivated by the recent work on pruning and distilling pre-trained models, we explore strategies to drop layers in pre-trained models, and observe the effect of pruning on downstream GLUE tasks. We were able to prune BERT, RoBERTa and XLNet models up to 40%, while maintaining up to 98% of their original performance. Additionally we show that our pruned models are on par with those built using knowledge distillation, both in terms of size and performance. Our experiments yield interesting observations such as, (i) the lower layers are most critical to maintain downstream task performance, (ii) some tasks such as paraphrase detection and sentence similarity are more robust to the dropping of layers, and (iii) models trained using a different objective function exhibit different learning patterns and w.r.t the layer dropping.
Trend surface analysis of geographic flows
Creators: name: Guo, Beiyang
name: Pei, Tao
name: Song, Ci
name: Shu, Hua
name: Wu, Mingbo
name: Guo, Sihui
name: Jiang, Jingyu
name: Du, Peijun
Publisher: name: Taylor & Francis
Year: 2022
Subjects: subject: Medicine
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Cancer
subject: Inorganic Chemistry
subject: FOS: Chemical sciences
subject: Plant Biology
subject: Computational Biology

description: An origin-destination (OD) flow is the movement of objects from an origin to a destination. Determining how the flows vary across geographic locations helps understand the mechanism of flow distributions; however, it has rarely been studied. Here, we propose a trend surface model with polynomial functions to quantify the flow distribution with coordinates in the flow space. This model assumes that an observed data-record is composed of the trend value and the residual, and is represented by the orthogonal polynomial with O and D coordinates as independent variables and flow properties as dependent variables. The simulation experiments based on the linear and quadratic models indicated that the trend surface function could reflect the increasing/decreasing variation of flows with OD locations (i.e. flow trends) in different patterns. Applying this model to a case study of taxi OD flows in the broad Central Business District of Beijing, we found that the flows exhibited a rising trend toward the southwest. The trend surface characteristics are associated with the distributions of urban functional patches, where the workplaces and residences increased toward the southwest in the study area. Notably, the spatial deviations of trend surface model can help in identifying site pairs that attract flows at a high density (e.g. commerce centers and big communities), facilitating the planning of public transportation to mitigate the congestion.
A note on the asymptotic normality of sums of extreme values
Creators: name: Lo, Gane Samb
Publisher: name: arXiv
Year: 2016
Subjects: subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences
subject: 62E20, 62G30, 60F05

description: Let $X_1$, $X_2$,... be a sequence of independent random variables with common distribution function $F$ in the domain of attraction of a Gumbel extreme value distribution and for each integer $n\geq 1$, let $X_{1,n} \leq ... X_{n,n}$ denote the order statistics based on the first $n$ of these random variables. Along with related results it is shown that for any sequence of positive integers $k_n \rightarrow +\infty$ and $k_{n}/n \rightarrow 0$ as $n \rightarrow 0$ the sum of the upper $k_n$ extreme values $X_{n-k_{n},n}+...+X_{n,n}$, when properly centered and normalized, converges in distribution to a standard normal random variable $N(0, 1)$. These results constitute an extension of results by S. Csörgő and D.M. Mason (1985).
description: 12
Extracting Biological Pathway Models From NLP Event Representations
Creators: name: Spranger, Michael
name: Palaniappan, Sucheendra K.
name: Ghosh, Samik
Publisher: name: arXiv
Year: 2016
Subjects: subject: Computation and Language (cs.CL)
subject: Molecular Networks (q-bio.MN)
subject: FOS: Computer and information sciences
subject: FOS: Biological sciences

description: This paper describes an an open-source software system for the automatic conversion of NLP event representations to system biology structured data interchange formats such as SBML and BioPAX. It is part of a larger effort to make results of the NLP community available for system biology pathway modelers.
A fast methodology for large-scale focusing inversion of gravity and magnetic data using the structured model matrix and the $2D$ fast Fourier transform
Creators: name: Renaut, Rosemary A.
name: Hogue, Jarom D.
name: Vatankhah, Saeed
Publisher: name: arXiv
Year: 2020
Subjects: subject: Geophysics (physics.geo-ph)
subject: Numerical Analysis (math.NA)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 65F10

description: Focusing inversion of potential field data for the recovery of sparse subsurface structures from surface measurement data on a uniform grid is discussed. For the uniform grid the model sensitivity matrices exhibit block Toeplitz Toeplitz block structure, by blocks for each depth layer of the subsurface. Then, through embedding in circulant matrices, all forward operations with the sensitivity matrix, or its transpose, are realized using the fast two dimensional Fourier transform. Simulations demonstrate that this fast inversion algorithm can be implemented on standard desktop computers with sufficient memory for storage of volumes up to size $n \approx 1M$. The linear systems of equations arising in the focusing inversion algorithm are solved using either Golub Kahan bidiagonalization or randomized singular value decomposition algorithms in which all matrix operations with the sensitivity matrix are implemented using the fast Fourier transform. These two algorithms are contrasted for efficiency for large-scale problems with respect to the sizes of the projected subspaces adopted for the solutions of the linear systems. The presented results confirm earlier studies that the randomized algorithms are to be preferred for the inversion of gravity data, and that it is sufficient to use projected spaces of size approximately $m/8$, for data sets of size $m$. In contrast, the Golub Kahan bidiagonalization leads to more efficient implementations for the inversion of magnetic data sets, and it is again sufficient to use projected spaces of size approximately $m/8$. Moreover, it is sufficient to use projected spaces of size $m/20$ when $m$ is large, $m \approx 50000$, to reconstruct volumes with $n \approx 1M$. Simulations support the presented conclusions and are verified on the inversion of a practical magnetic data set that is obtained over the Wuskwatim Lake region in Manitoba, Canada.
description: 39 pages. 16 figures
Stability of mass transfer from massive giants: double black-hole binary formation and ultra-luminous X-ray sources
Creators: name: Pavlovskii, K.
name: Ivanova, N.
name: Belczynski, K.
name: Van, K. X.
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: The mass transfer in binaries with massive donors and compact companions, when the donors rapidly evolve after their main sequence, is one of the dominant formation channels of merging double stellar-mass black hole binaries. This mass transfer was previously postulated to be unstable and was expected to lead to a common envelope event. The common envelope event then would end with either double black hole formation, or with the merger of the two stars. We re-visit the stability of this mass transfer, and find that for a large range of the binary orbital separations this mass transfer is stable. This newly found stability allows us to reconcile the theoretical rate for double black hole binary mergers predicted by population synthesis studies, and the empirical rate obtained by LIGO. Futhermore, the stability of the mass transfer leads to the formation of ultra-luminous X-ray sources. The theoretically predicted formation rates of ultra-luminous X-ray sources powered by a stellar-mass BH, as well as the range of produced X-ray luminosity, can explain the observed bright ultra-luminous X-ray sources.
description: 10 pages,3 figures, 1 table, submitted to MNRAS