cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Harald Rau: Qualität in einer Ökonomie der Publizistik. Betriebswirtschaftliche Lösungen für die Redaktion
Creators: name: Wyss, Vinzenz
Publisher: name: Springer
Year: 2008
Subjects: 070: Nachrichtenmedien, Journalismus und Verlagswesen

description: Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)
Permutation Inference for Canonical Correlation Analysis
Creators: name: Winkler, Anderson M.
name: Renaud, Olivier
name: Smith, Stephen M.
name: Nichols, Thomas E.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Methodology (stat.ME)
subject: Statistics Theory (math.ST)
subject: Applications (stat.AP)
subject: Computation (stat.CO)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: Canonical correlation analysis (CCA) has become a key tool for population neuroimaging, allowing investigation of associations between many imaging and non-imaging measurements. As other variables are often a source of variability not of direct interest, previous work has used CCA on residuals from a model that removes these effects, then proceeded directly to permutation inference. We show that such a simple permutation test leads to inflated error rates. The reason is that residualisation introduces dependencies among the observations that violate the exchangeability assumption. Even in the absence of nuisance variables, however, a simple permutation test for CCA also leads to excess error rates for all canonical correlations other than the first. The reason is that a simple permutation scheme does not ignore the variability already explained by previous canonical variables. Here we propose solutions for both problems: in the case of nuisance variables, we show that transforming the residuals to a lower dimensional basis where exchangeability holds results in a valid permutation test; for more general cases, with or without nuisance variables, we propose estimating the canonical correlations in a stepwise manner, removing at each iteration the variance already explained, while dealing with different number of variables in both sides. We also discuss how to address the multiplicity of tests, proposing an admissible test that is not conservative, and provide a complete algorithm for permutation inference for CCA.
description: 49 pages, 2 figures, 10 tables, 3 algorithms, 119 references
Correlations between supermassive black holes and hot gas atmospheres in IllustrisTNG and X-ray observations
Creators: name: Truong, Nhut
name: Pillepich, Annalisa
name: Werner, Norbert
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Recent X-ray observations have revealed remarkable correlations between the masses of central supermassive black holes (SMBHs) and the X-ray properties of the hot atmospheres permeating their host galaxies, thereby indicating the crucial role of the atmospheric gas in tracing SMBH growth in the high-mass regime. We examine this topic theoretically using the IllustrisTNG cosmological simulations and provide insights to the nature of this SMBH -- gaseous halo connection. By carrying out a mock X-ray analysis for a mass-selected sample of TNG100 simulated galaxies at $z=0$, we inspect the relationship between the masses of SMBHs and the hot gas temperatures and luminosities at various spatial and halo scales -- from galactic ($\sim R_{\rm e}$) to group/cluster scales ($\sim R_{\rm 500c}$). We find strong SMBH-X-ray correlations mostly in quenched galaxies and find that the correlations become stronger and tighter at larger radii. Critically, the X-ray temperature ($k_{\rm B}T_{\rm X}$) at large radii ($r\gtrsim5R_{\rm e}$) traces the SMBH mass with a remarkably small scatter ($\sim0.2$ dex). The relations emerging from IllustrisTNG are broadly consistent with those obtained from recent X-ray observations. Overall, our analysis suggests that, within the framework of IllustrisTNG, the present-time $M_{\rm BH}-k_{\rm B}T_{X}$ correlations at the high-mass end ($M_{\rm BH}\gtrsim 10^8 M_\odot$) are fundamentally a reflection of the SMBH mass -- halo mass relation, which at such high masses is set by the hierarchical assembly of structures. The exact form, locus, and scatter of those scaling relations are, however, sensitive to feedback processes such as those driven by star formation and SMBH activity.
description: 22 pages, 8 figures, 2 tables, replaced to match accepted version
On substitution automorphisms with pure singular spectrum
Creators: name: Bufetov, Alexander I.
name: Solomyak, Boris
Publisher: name: arXiv
Year: 2020
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37A30 (Primary), 37B10

description: A sufficient condition for a substitution automorphism to have pure singular spectrum is given in terms of the top Lyapunov exponent of the associated spectral cocycle. As a corollary, singularity of the spectrum is established for an infinite family of self-similar interval exchange transformations.
description: Revision after the referee report; to appear in Mathematische Zeitschrift
Scheme for generating entangled states of two field modes in a cavity
Creators: name: Larson, Jonas
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: This paper considers a two-level atom interacting with two cavity modes with equal frequencies. Applying a unitary transformation, the system reduces to the analytically solvable Jaynes-Cummings model. For some particular field states, coherent and squeezed states, the transformation between the two bare basis's, related by the unitary transformation, becomes particularly simple. It is shown how to generate, the highly non-classical, entangled coherent states of the two modes, both in the zero and large detuning cases. An advantage with the zero detuning case is that the preparation is deterministic and no atomic measurement is needed. For the large detuning situation a measurement is required, leaving the field in either of two orthogonal entangled coherent states.
description: Accepted in J. Mod. Opt.; 12 pages; Replaced with revised version. Extended discussion of experimental realizations, earlier studies in the field and on the frequency dependence in the adiabatic elimination
Possibility of Small Electron States
Creators: name: Sebens, Charles T.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Some authors have claimed that there exists a minimum size (on the order of the Compton radius) for electron states composed entirely of positive-frequency solutions to the free Dirac equation. Other authors have put forward counterexamples to such claims. This article asks how the counterexamples of A. J. Bracken and G. F. Melloy [J. Phys. A. 32, 6127 (1999)] bypass two arguments against their possibility. The first is an old argument that, because of the prohibition on faster-than-light motion, the electron must be larger than a certain minimum size if it is to have the correct angular momentum and magnetic moment. This challenge can be addressed by analyzing the flow of energy and charge for the counterexample states. The second argument is an explicit proof (presented in C.-P. Chuu et al., [Solid State Commun. 150, 533 (2010)]) that there is a minimum size for purely positive-frequency electron states. This proof hinges on the assumption of a small spread in momentum space, which is violated by the counterexamples that have been put forward.
description: 8 pages, 3 figures
Attraktivität der Arbeitgebenden für die Generation Z : eine Mixed Method-Untersuchung aus Sicht der Arbeitnehmenden und Arbeitgebenden
Creators: name: Abdulkadir, Abdi Asis
Publisher: name: ZHAW Zürcher Hochschule für Angewandte Wissenschaften
Year: 2023
Subjects: 658.3: Personalmanagement
658.401: Unternehmensentwicklung

description: Während die Generation der Babyboomer langsam die Arbeitswelt verlässt, nimmt der Anteil an der Generation Z stetig zu. Zusammen mit der Generation Y, den Vorgänger:innen der Generation Z, bildet sie die grösste demografische Altersgruppe auf dem Schweizer Arbeitsmarkt. Durch die Kombination mit dem herrschenden Fachkräftemangel und dem demografischen Wandel sind Arbeitgebende mit signifikanten Herausforderungen konfrontiert. Um ein besseres Verständnis für die Generation Z als Arbeitnehmende zu entwickeln, wurden in der vorliegenden empirischen Bachelorarbeit deren Bedürfnisse und Erwartungen an ihre Arbeitgebende untersucht. Ziel dabei war es die Attraktivitätsmerkmale der Arbeitgebende für die Generation Z und die notwendigen Massnahmen für eine effektive Mitarbeitendenbindung zu ermitteln.
Um der Forschungsfrage nachzugehen, wurde eine ausführliche Literaturrecherche durchgeführt. Daran anknüpfend kam als Forschungsdesign eine Mixed Method zur Anwendung. In einer ersten Phase erfolgte die Durchführung einer quantitativen Online-Umfrage mit einer Stichprobe von über 450 Personen aus der Generation Z. In einer zweiten Phase wurden sieben qualitative Interviews mit branchenführenden Schweizer Grossunternehmen durchgeführt. Diese ermöglichten eine detailliertere Betrachtung der Ergebnisse der ersten Phase sowie eine Integration der Erfahrung aus der Praxis. Darüber hinaus sind alle Unternehmen von national und internationalen Instituten als attraktive Arbeitgebende ausgezeichnet und besitzen viele Berührungspunkte mit der Generation Z.
Die Ergebnisse aus dem Forschungsdesign deuten darauf hin, dass die Generation Z ein signifikantes Bedürfnis nach Anerkennung am Arbeitsplatz aufweist. Ferner wird vom Arbeitgebenden erwartet, den Mitarbeitenden ein fachliches und persönliches Wachstum zu ermöglichen. Aus der Untersuchung geht ebenfalls hervor, dass sich die Motivationsfaktoren der Generation Z am Arbeitsplatz grundlegend von denen der anderen Generationen unterscheidet. Aufgrund der Werte der Generation Z beeinflusst eine Beförderung durch den Arbeitgebenden nur begrenzt ihre Motivation, wohingegen sich der Einfluss des Arbeitsinhalts als sehr gross erweist.
Abschliessend wird Unternehmen geraten, in ihrer Rolle als Arbeitgebende unterschiedliche Wertschätzungsformen am Arbeitsplatz einzubinden. Des Weiteren wird empfohlen die persönlichen Stärken und Interessen der Generation Z bei der Gestaltung des Arbeitsinhaltes in Betracht zu ziehen. Die Implementation von Handlungsempfehlungen wie diese ermöglichen es, die Motivation der Generation Z in der Schweiz zu erhöhen, die Mitarbeitendenbindung zu stärken und daraus resultierend die Wahrnehmung als attraktiven Arbeitgebenden zu steigern.
Comparing early dark energy and extra radiation solutions to the Hubble tension with BBN
Creators: name: Seto, Osamu
name: Toda, Yo
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The shorten sound horizon scale at the recombination epoch by introducing extra energy components such as the extra radiation or early dark energy (EDE) is a simple approach to so-called the Hubble tension. We compare EDE models, an extra radiation model and an EDE and extra radiation co-existing model with paying attention to the fit to big bang nucleosynthesis (BBN). We find that a fit to BBN in EDE models also is somewhat poorer than that in the $Λ$CDM model, because the increased inferred baryon asymmetry leads to smaller deuterium abundance. We find that an extra radiation-EDE co-existing model indicates the largest present Hubble parameter $H_0$ between models studied. We also the examine data sets dependence, whether we include BBN or not. The difference in an extra radiation model is $3.22 < N_\mathrm{eff} < 3.49 \,(68 \%)$ for data sets without BBN and $3.16 < N_\mathrm{eff} < 3.40 \,(68 \%)$ for data sets with BBN, and is so large that the $1σ$ border of the larger side becomes the $2σ$ border.
description: 17 pages,10 figures: discussions, figures and references added, version published in Phys. Rev. D
A Theory of the Risk for Optimization with Relaxation and its Application to Support Vector Machines
Creators: name: Campi, Marco C.
name: Garatti, Simone
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (cs.LG)
subject: Systems and Control (eess.SY)
subject: Optimization and Control (math.OC)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: In this paper we consider optimization with relaxation, an ample paradigm to make data-driven designs. This approach was previously considered by the same authors of this work in Garatti and Campi (2019), a study that revealed a deep-seated connection between two concepts: risk (probability of not satisfying a new, out-of-sample, constraint) and complexity (according to a definition introduced in paper Garatti and Campi (2019)). This connection was shown to have profound implications in applications because it implied that the risk can be estimated from the complexity, a quantity that can be measured from the data without any knowledge of the data-generation mechanism. In the present work we establish new results. First, we expand the scope of Garatti and Campi (2019) so as to embrace a more general setup that covers various algorithms in machine learning. Then, we study classical support vector methods - including SVM (Support Vector Machine), SVR (Support Vector Regression) and SVDD (Support Vector Data Description) - and derive new results for the ability of these methods to generalize. All results are valid for any finite size of the data set. When the sample size tends to infinity, we establish the unprecedented result that the risk approaches the ratio between the complexity and the cardinality of the data sample, regardless of the value of the complexity.
description: https://www.jmlr.org/papers/v22/21-0641.html
ผลของซิลิกอนจากอุตสาหกรรมซีเมนต์และความเค็มต่อการเจริญเติบโต ผลผลิต และการเปลี่ยนแปลงทางสรีรวิทยาของข้าวพันธุ์หอมธรรมศาสตร์
Creators: name: พฤกษ์ ชุติมานุกูล
Publisher: name: Thammasat University
Year: 2019
Subjects: growth
Hom Thammasat rice variety
physiological change
salinity
silicon
yield

description: Thai Journal of Science and Technology, 8, 5, 509-516
Density Dependence of the Symmetry energy and the Equation of State of Isospin Asymmetric Nuclear Matter
Creators: name: Shetty, D. V.
name: Yennello, S. J.
name: Souliotis, G. A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Astrophysics (astro-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The density dependence of the symmetry energy in the equation of state of isospin asymmetric nuclear matter is studied using the isoscaling of the fragment yields and the antisymmetrized molecular dynamic calculation. It is observed that the experimental data at low densities are consistent with the form of symmetry energy,E$_{sym}$ $\approx$ 31.6 ($ρ/ρ_{\circ})^{0.69}$, in close agreement with those predicted by the results of variational many-body calculation. A comparison of the present result with those reported recently using the NSCL-MSU data suggests that the heavy ion studies favor a dependence of the form, E$_{sym}$ $\approx$ 31.6 ($ρ/ρ_{\circ})^γ$, where $γ$ = 0.6 - 1.05. This constraints the form of the density dependence of the symmetry energy at higher densities, ruling out an extremely " stiff " and " soft " dependences.
description: 4 pages, 3 figures, minor revison to the text, added few more references
การถ่ายยีนและวิเคราะห์การแสดงออกของยีน OsB2 ที่ควบคุมการสังเคราะห์แอนโทไซยานินในข้าว
Creators: name: ช่อทิพา สกูลสิงหาโรจน์
Publisher: name: Thammasat University
Year: 2019
Subjects: Oryza sativa
OsB2
transformation
anthocyanin

description: Thai Journal of Science and Technology, 8, 5, 517-531
An Adversarial Approach to Structural Estimation
Creators: name: Kaji, Tetsuya
name: Manresa, Elena
name: Pouliot, Guillaume
Publisher: name: arXiv
Year: 2020
Subjects: subject: Econometrics (econ.EM)
subject: Machine Learning (cs.LG)
subject: Statistics Theory (math.ST)
subject: Methodology (stat.ME)
subject: Machine Learning (stat.ML)
subject: FOS: Economics and business
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: We propose a new simulation-based estimation method, adversarial estimation, for structural models. The estimator is formulated as the solution to a minimax problem between a generator (which generates simulated observations using the structural model) and a discriminator (which classifies whether an observation is simulated). The discriminator maximizes the accuracy of its classification while the generator minimizes it. We show that, with a sufficiently rich discriminator, the adversarial estimator attains parametric efficiency under correct specification and the parametric rate under misspecification. We advocate the use of a neural network as a discriminator that can exploit adaptivity properties and attain fast rates of convergence. We apply our method to the elderly's saving decision model and show that our estimator uncovers the bequest motive as an important source of saving across the wealth distribution, not only for the rich.
description: 56 pages, 3 tables, 11 figures
Asymmetric Zero-Bias Anomaly for Strongly Interacting Electrons in One Dimension
Creators: name: Matveev, K. A.
name: Furusaki, A
name: Glazman, L. I.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study a system of one-dimensional electrons in the regime of strong repulsive interactions, where the spin exchange coupling J is small compared with the Fermi energy, and the conventional Tomonaga-Luttinger theory does not apply. We show that the tunneling density of states has a form of an asymmetric peak centered near the Fermi level. In the spin-incoherent regime, where the temperature is large compared to J, the density of states falls off as a power law of energy εmeasured from the Fermi level, with the prefactor at positive energies being twice as large as that at the negative ones. In contrast, at temperatures below J the density of states forms a split peak with most of the weight shifted to negative ε.
description: 4 pages, 2 figures
First Demonstration of the Use of LG-SiPMs for Optical Readout of a TPC
Creators: name: Gola, A.
name: Majumdar, K.
name: Casse, G.
name: Mavrokoridis, K.
name: Merzi, S.
name: Franca, L. Parsons
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: This paper describes a new method for optical readout of Time Projection Chambers (TPCs), based on the Linearly Graded Silicon Photomultiplier (LG-SiPM). This is a single photon-sensitive detector with excellent timing and 2D position resolution developed at Fondazione Bruno Kessler, Trento (FBK). The LG-SiPM produces time-varying voltage signals that are used to reconstruct the 3D position and energy of ionisation tracks generated inside the TPC. The TPC used in this work contained room-temperature CF$_4$ gas at a pressure of 100 mbar, with two THGEMs to produce secondary scintillation light. A collimated $^{241}$Am source (Q$_α$ = 5.486 MeV) was used to produce the ionisation tracks. The successful reconstruction of these tracks is demonstrated, and the consistency of the methodology characterised through varying the geometry of the tracks within the TPC. Energy reconstruction and deposition studies are also described, demonstrating the feasibility of the LG-SiPM as a potential option for optical TPC readout.
description: Various changes from previous version based on pre-publication review
Spectral Sections
Creators: name: Prokhorova, Marina
Publisher: name: arXiv
Year: 2020
Subjects: subject: Spectral Theory (math.SP)
subject: Analysis of PDEs (math.AP)
subject: Differential Geometry (math.DG)
subject: Functional Analysis (math.FA)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 47B25, 35P05, 47N20, 35J46 (Primary) 58J05, 35J56 (Secondary)

description: The paper is devoted to the notion of a spectral section introduced by Melrose and Piazza. In the first part of the paper we generalize results of Melrose and Piazza to arbitrary base spaces, not necessarily compact. The second part contains a number of applications, including cobordism theorems for families of Dirac type operators parametrized by a non-compact base space. In the third part of the paper we investigate whether Riesz continuity is necessary for existence of a spectral section or a generalized spectral section. In particular, we show that if a graph continuous family of regular self-adjoint operators with compact resolvents has a spectral section, then the family is Riesz continuous.
description: v5: 37 pages; the exposition is improved and the results about Hilbert bundles are moved to a future paper
Phenomenology using lattice QCD
Creators: name: Gupta, Rajan
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter B_K. Precise estimates of these four fundamental parameters of the standard model, i.e., m_u, m_d, m_s and the CP violating parameter eta, help constrain grand unified models and could provide a window to new physics.
description: Plenary talk at PASCOS 2004, August 16-22, Northeastern University, Boston
Cdh Descent for Homotopy Hermitian $K$-Theory of Rings with Involution
Creators: name: Carmody, Daniel
Publisher: name: arXiv
Year: 2020
Subjects: subject: K-Theory and Homology (math.KT)
subject: Algebraic Geometry (math.AG)
subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics

description: We provide a geometric model for the classifying space of automorphism groups of Hermitian vector bundles over a ring with involution $R$ such that $\frac{1}{2} \in R$; this generalizes a result of Schlichting-Tripathi \cite{SchTri}. We then prove a periodicity theorem for Hermitian $K$-theory and use it to construct an $E_\infty$ motivic ring spectrum $\mathbf{KR}^{\mathrm{alg}}$ representing homotopy Hermitian $K$-theory. From these results, we show that $\mathbf{KR}^{\mathrm{alg}}$ is stable under base change, and cdh descent for homotopy Hermitian $K$-theory of rings with involution is a formal consequence.
description: 34 pages: Final version - removed unnecessary hypothesis in theorem 5.1
Iterated differences sets, diophantine approximations and applications
Creators: name: Bergelson, Vitaly
name: Zelada, Rigoberto
Publisher: name: arXiv
Year: 2020
Subjects: subject: Combinatorics (math.CO)
subject: Dynamical Systems (math.DS)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 05D10 (Primary) 11B75, 37A45 (Secondary)

description: Let $v$ be an odd real polynomial (i.e. a polynomial of the form $\sum_{j=1}^\ell a_jx^{2j-1}$). We utilize sets of iterated differences to establish new results about sets of the form $\mathcal R(v,ε)=\{n\in\mathbb{N}\,|\,\|v(n)\|{<ε\}}$ where $\|\cdot\|$ denotes the distance to the closest integer. We then apply the new diophantine results to obtain applications to ergodic theory and combinatorics. In particular, we obtain a new characterization of weakly mixing systems as well as a new variant of Furstenberg-Sárközy theorem.
description: 43 pages, referees' comments included, minor errors in the proofs of Theorem 4.1 and Lemma 5.3 were corrected
Gravitational waves in neutrino plasma and NANOGrav signal
Creators: name: Pandey, Arun Kumar
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The recent finding of the gravitational wave (GW) signal by the NANOGrav collaboration in the nHZ frequency range has opened up the door for the existence of stochastic GWs. In the present work, we have argued that in a hot dense neutrino asymmetric plasma, GWs could be generated due to the instability caused by the finite difference in the number densities of the different species of the neutrinos. The generated GWs have amplitude and frequency in the sensitivity range of the NANOGrav observation. We have shown that the GWs generated by this mechanism could be one of the possible explanations for the observed NANOGrav signal. We have also discussed generation of GWs in an inhomogeneous cosmological neutrino plasma, where GWs are generated when neutrinos enter a free streaming regime. We show that the generated GWs in an inhomogeneous neutrino plasma cannot explain the observed NANOGrav signal. We have also calculated the lower bound on magnetic fields' strength using the NANOGrav signal and found that to explain the signal, the magnetic fields' strength should have atleast value $\sim 10^{-12}$ G at an Mpc length scale.
description: 7 Pages and 1 figures
Dissemination & Communication Report
Creators: name: Beruete, Clio
name: Tenorio Fornés, Ámbar
name: Leligou, Helen C. (Nelly)
name: Trevisan, Olga
Publisher: name: Zenodo
Year: 2025

description: In this document we present the evolution of the Dissemination and Communication Plan designed to disseminate and communicate DAFNE+ project, the social media communication strategy, and the user engagement strategy for each use case along the first 18 months of the project. Also, the challenges that we have encountered and the next steps we have ahead of us.
BFKL resummation effects in gamma* gamma* --> rho rho
Creators: name: Enberg, R.
name: Pire, B.
name: Szymanowski, L.
name: Wallon, S.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We calculate the leading order BFKL amplitude for the exclusive diffractive process γ*_L(Q1^2) γ*_L(Q2^2) \to ρ_L^0 ρ_L^0 in the forward direction, which can be studied in future high energy e^+e^- linear colliders. The resummation effects are very large compared to the fixed-order calculation. We also estimate the next-to-leading logarithmic corrections to the amplitude by using a specific resummation of higher order effects and find a substantial growth with energy, but smaller than in the leading logarithmic approximation.
description: 23 pages, 13 figures. Numerical bug affecting plots in Figs 12 and 13 corrected
A Grassmann Manifold Handbook: Basic Geometry and Computational Aspects
Creators: name: Bendokat, Thomas
name: Zimmermann, Ralf
name: Absil, P. -A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Numerical Analysis (math.NA)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 15-02, 15A16, 15A18, 15B10, 22E70, 51F25, 53C80, 53Z99

description: The Grassmann manifold of linear subspaces is important for the mathematical modelling of a multitude of applications, ranging from problems in machine learning, computer vision and image processing to low-rank matrix optimization problems, dynamic low-rank decompositions and model reduction. With this mostly expository work, we aim to provide a collection of the essential facts and formulae on the geometry of the Grassmann manifold in a fashion that is fit for tackling the aforementioned problems with matrix-based algorithms. Moreover, we expose the Grassmann geometry both from the approach of representing subspaces with orthogonal projectors and when viewed as a quotient space of the orthogonal group, where subspaces are identified as equivalence classes of (orthogonal) bases. This bridges the associated research tracks and allows for an easy transition between these two approaches.
 Original contributions include a modified algorithm for computing the Riemannian logarithm map on the Grassmannian that is advantageous numerically but also allows for a more elementary, yet more complete description of the cut locus and the conjugate points. We also derive a formula for parallel transport along geodesics in the orthogonal projector perspective, formulae for the derivative of the exponential map, as well as a formula for Jacobi fields vanishing at one point.
description: 38 pages, 4 figures
Finite reflection groups and symmetric extensions of Laplacian
Creators: name: Stempak, Krzysztof
Publisher: name: arXiv
Year: 2020
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics

description: Let $W$ be a finite reflection group associated with a root system $R$ in $\mathbb R^d$. Let $C_+$ denote a positive Weyl chamber. Consider an open subset $Ω$ of $\mathbb R^d$, symmetric with respect to reflections from $W$. Let $Ω_+=Ω\cap C_+$ be the positive part of $Ω$. We define a family $\{-Δ_η^+\}$ of self-adjoint extensions of the Laplacian $-Δ_{Ω_+}$, labeled by homomorphisms $η\colon W\to \{1,-1\}$. In the construction of these $η$-Laplacians $η$-symmetrization of functions on $Ω$ is involved. The Neumann Laplacian $-Δ_{N,Ω_+}$ is included and corresponds to $η\equiv1$. If $H^{1}(Ω)=H^{1}_0(Ω)$, then the Dirichlet Laplacian $-Δ_{D,Ω_+}$ is either included and corresponds to $η={\rm sgn}$; otherwise the Dirichlet Laplacian is considered separately. Applying the spectral functional calculus we consider the pairs of operators $Ψ(-Δ_{N,Ω})$ and $Ψ(-Δ_η^+)$, or $Ψ(-Δ_{D,Ω})$ and $Ψ(-Δ_{D,Ω_+})$, where $Ψ$ is a Borel function on $[0,\infty)$. We prove relations between the integral kernels for the operators in these pairs, which are given in terms of symmetries governed by $W$.
description: 30 pages
Conformal Weyl gravity via two stages of quasinormal ringing and late-time behavior
Creators: name: Konoplya, R. A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Black hole (BH) solution in the conformal Weyl gravity is a generalization of the Schwarzschild spacetime which includes two additional constants appearing when integrating the third order differential equations for gravitational field. One constant looks like the effective cosmological constant providing the de Sitter asymptotic of the solution. The other constant allows one to describe flat rotation of galaxies without introducing of the dark matter. Here we show that the effective "dark matter" term in the metric function drastically changes the asymptotic behavior of the evolution of the wave function of a scalar field: after the Schwarzschild-like ringing phase, the ringing at another, non-Schwarzschildian, longer-lived frequency takes place before the beginning of the exponential asymptotic tail. Thus the evolution of the scalar field consists of the three qualitatively different stages: the Schwarzschild-like ringing phase, the effective dark matter ringing phase and the de Sitter phase characterized by exponential tails. The late time behavior of the electromagnetic field is qualitatively different as well: the exponential tails appear even in the absence of the effective de Sitter term.
description: 7 pages, 4 figures, revtex, the version to match the published one
Spin-dependent tunneling between individual superconducting bound states
Creators: name: Huang, Haonan
name: Senkpiel, Jacob
name: Padurariu, Ciprian
name: Drost, Robert
name: Villas, Alberto
name: Klees, Raffael L.
name: Yeyati, Alfredo Levy
name: Cuevas, Juan Carlos
name: Kubala, Björn
name: Ankerhold, Joachim
name: Kern, Klaus
name: Ast, Christian R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Magnetic impurities on superconductors induce discrete bound levels inside the superconducting gap, known as Yu-Shiba-Rusinov (YSR) states. YSR levels are fully spin-polarized such that the tunneling between YSR states depends on their relative spin orientation. Here, we use scanning tunneling spectroscopy to resolve the spin dynamics in the tunneling process between two YSR states by experimentally extracting the angle between the spins. To this end, we exploit the ratio of thermally activated and direct spectral features in the measurement to directly extract the relative spin orientation between the two YSR states. We find freely rotating spins down to 7mK, indicating a purely paramagnetic nature of the impurities. Such a non-collinear spin alignment is essential not only for producing Majorana bound states but also as an outlook manipulating and moving the Majorana state onto the tip.
description: 22 pages, 7 figures, including supplementary material
Supercritical transition to turbulence in an inertially-driven von Karman closed flow
Creators: name: Ravelet, Florent
name: Chiffaudel, Arnaud
name: Daviaud, Francois
Publisher: name: arXiv
Year: 2008
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We study the transition from laminar flow to fully developed turbulence for an inertially-driven von Karman flow between two counter-rotating large impellers fitted with curved blades over a wide range of Reynolds number (100 - 1 000 000). The transition is driven by the destabilisation of the azimuthal shear-layer, i.e., Kelvin-Helmholtz instability which exhibits travelling/drifting waves, modulated travelling waves and chaos below the emergence of a turbulent spectrum. A local quantity -the energy of the velocity fluctuations at a given point- and a global quantity -the applied torque- are used to monitor the dynamics. The local quantity defines a critical Reynolds number Rec for the onset of time-dependence in the flow, and an upper threshold/crossover Ret for the saturation of the energy cascade. The dimensionless drag coefficient, i.e., the turbulent dissipation, reaches a plateau above this finite Ret, as expected for a "Kolmogorov"-like turbulence for Re -> infinity. Our observations suggest that the transition to turbulence in this closed flow is globally supercritical: the energy of the velocity fluctuations can be considered as an order parameter characterizing the dynamics from the first laminar time-dependence up to the fully developed turbulence. Spectral analysis in temporal domain moreover reveals that almost all of the fluctuations energy is stored in time-scales one or two orders of magnitude slower than the time-scale based on impeller frequency.
Evolution and use cases of FairMQ
Creators: name: Rybalchenko, A.
name: Al-Turany, M.
name: Winckler, N.
Publisher: name: GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
Year: 2015
Subjects: Physics

description: GSI Scientific Report 2014 - GSI Report 2015-1
Numerical issues in maximum likelihood parameter estimation for Gaussian process interpolation
Creators: name: Basak, Subhasish
name: Petit, Sébastien
name: Bect, Julien
name: Vazquez, Emmanuel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: Computation (stat.CO)
subject: FOS: Computer and information sciences

description: This article investigates the origin of numerical issues in maximum likelihood parameter estimation for Gaussian process (GP) interpolation and investigates simple but effective strategies for improving commonly used open-source software implementations. This work targets a basic problem but a host of studies, particularly in the literature of Bayesian optimization, rely on off-the-shelf GP implementations. For the conclusions of these studies to be reliable and reproducible, robust GP implementations are critical.
Benchmarking the Benchmark -- Analysis of Synthetic NIDS Datasets
Creators: name: Layeghy, Siamak
name: Gallagher, Marcus
name: Portmann, Marius
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Cryptography and Security (cs.CR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Network Intrusion Detection Systems (NIDSs) are an increasingly important tool for the prevention and mitigation of cyber attacks. A number of labelled synthetic datasets generated have been generated and made publicly available by researchers, and they have become the benchmarks via which new ML-based NIDS classifiers are being evaluated. Recently published results show excellent classification performance with these datasets, increasingly approaching 100 percent performance across key evaluation metrics such as accuracy, F1 score, etc. Unfortunately, we have not yet seen these excellent academic research results translated into practical NIDS systems with such near-perfect performance. This motivated our research presented in this paper, where we analyse the statistical properties of the benign traffic in three of the more recent and relevant NIDS datasets, (CIC, UNSW, ...). As a comparison, we consider two datasets obtained from real-world production networks, one from a university network and one from a medium size Internet Service Provider (ISP). Our results show that the two real-world datasets are quite similar among themselves in regards to most of the considered statistical features. Equally, the three synthetic datasets are also relatively similar within their group. However, and most importantly, our results show a distinct difference of most of the considered statistical features between the three synthetic datasets and the two real-world datasets. Since ML relies on the basic assumption of training and test datasets being sampled from the same distribution, this raises the question of how well the performance results of ML-classifiers trained on the considered synthetic datasets can translate and generalise to real-world networks. We believe this is an interesting and relevant question which provides motivation for further research in this space.
description: 25 pages, 13 figures
Characterizing the Adaptive Optics Off-Axis Point-Spread Function. II. Methods for Use in Laser Guide Star Observations
Creators: name: Steinbring, E.
name: Faber, S. M.
name: Macintosh, B. A.
name: Gavel, D.
name: Gates, E. L.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Most current astronomical adaptive optics (AO) systems rely on the availability of a bright star to measure the distortion of the incoming wavefront. Replacing the guide star with an artificial laser beacon alleviates this dependency on bright stars and therefore increases sky coverage, but it does not eliminate another serious problem for AO observations. This is the issue of PSF variation with time and field position near the guide star. In fact, because a natural guide star is still necessary for correction of the low-order phase error, characterization of laser guide star (LGS) AO PSF spatial variation is more complicated than for a natural guide star alone. We discuss six methods for characterizing LGS AO PSF variation that can potentially improve the determination of the PSF away from the laser spot, that is, off-axis. Calibration images of dense star fields are used to determine the change in PSF variation with field position. This is augmented by AO system telemetry and simple computer simulations to determine a more accurate off-axis PSF. We report on tests of the methods using the laser AO system on the Lick Observatory Shane Telescope. [Abstract truncated.]
description: 31 pages, 5 figures, accepted by PASP
Generic and modular design for FairMQ devices
Creators: name: Winckler, N.
name: Al-Turany, M.
name: Bertini, D.
name: Karabowicz, R.
name: Kresan, D.
name: Lebedev, A.
name: Manafov, A.
name: Rybalchenko, A.
name: Uhlig, F.
Publisher: name: GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
Year: 2015
Subjects: Physics

description: GSI Scientific Report 2014 - GSI Report 2015-1
Asymptotic structure of the Rarita-Schwinger theory in four spacetime dimensions at spatial infinity
Creators: name: Fuentealba, Oscar
name: Henneaux, Marc
name: Majumdar, Sucheta
name: Matulich, Javier
name: Neogi, Turmoli
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We investigate the asymptotic structure of the free Rarita-Schwinger theory in four spacetime dimensions at spatial infinity in the Hamiltonian formalism. We impose boundary conditions for the spin-3/2 field that are invariant under an infinite-dimensional (abelian) algebra of non-trivial asymptotic fermionic symmetries. The compatibility of this set of boundary conditions with the invariance of the theory under Lorentz boosts requires the introduction of boundary degrees of freedom in the Hamiltonian action, along the lines of electromagnetism. These boundary degrees of freedom modify the symplectic structure by a surface contribution appearing in addition to the standard bulk piece. The Poincaré transformations have then well-defined (integrable, finite) canonical generators. Moreover, improper fermionic gauge symmetries, which are also well-defined canonical transformations, are further enlarged and turn out to be parametrized by two independent angle-dependent spinor functions at infinity, which lead to an infinite-dimensional fermionic algebra endowed with a central charge. We extend next the analysis to the supersymmetric spin-$(1,3/2)$ and spin-$(2,3/2)$ multiplets. First, we present the canonical realization of the super-Poincaré algebra on the spin-$(1,3/2)$ multiplet, which is shown to be consistently enhanced by the infinite-dimensional abelian algebra of angle-dependent bosonic and fermionic improper gauge symmetries associated with the electromagnetic and the Rarita-Schwinger fields, respectively. A similar analysis of the spin-$(2,3/2)$ multiplet is then carried out to obtain the canonical realization of the super-Poincaré algebra, consistently enhanced by the abelian improper bosonic gauge transformations of the spin-$2$ field (BMS supertranslations) and the abelian improper fermionic gauge transformations of the spin-$3/2$ field.
description: 33 pages, no figures, minor changes made in the text and some equations simplified, this version matches the one published in JHEP
A Communication-Efficient and Privacy-Aware Distributed Algorithm for Sparse PCA
Creators: name: Wang, Lei
name: Liu, Xin
name: Zhang, Yin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: Sparse principal component analysis (PCA) improves interpretability of the classic PCA by introducing sparsity into the dimension-reduction process. Optimization models for sparse PCA, however, are generally non-convex, non-smooth and more difficult to solve, especially on large-scale datasets requiring distributed computation over a wide network. In this paper, we develop a distributed and centralized algorithm called DSSAL1 for sparse PCA that aims to achieve low communication overheads by adapting a newly proposed subspace-splitting strategy to accelerate convergence. Theoretically, convergence to stationary points is established for DSSAL1. Extensive numerical results show that DSSAL1 requires far fewer rounds of communication than state-of-the-art peer methods. In addition, we make the case that since messages exchanged in DSSAL1 are well-masked, the possibility of private-data leakage in DSSAL1 is much lower than in some other distributed algorithms.
FairMQ application example in CbmRoot
Creators: name: Winckler, N.
name: Al-Turany, M.
name: Bertini, D.
name: Karabowicz, R.
name: Kresan, D.
name: Lebedev, A.
name: Manafov, A.
name: Rybalchenko, A.
name: Uhlig, F.
Publisher: name: GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
Year: 2015
Subjects: Physics

description: GSI Scientific Report 2014 - GSI Report 2015-1
Study of metal binding site of methyl parathion hydrolase
Creators: name: Azizan, Nur
Publisher: name: The Australian National University
Year: 2015

description: Metal ions are an essential component of numerous proteins. In some cases they have a structural role, but their more important roles are redox proteins and enzymes. Metals interact quite differently with proteins depending upon the function of the protein. In enzymes metals are coordinated to the protein, but maintain vacant coordination sites to allow them to interact with substrates or to activate nucleophiles for attack. In binuclear metalloenzymes, metals have the potential to function in both capacities where they can bind substrate and can also activate water for attack. Most studies of binuclear metalloenzymes focus on the native enzyme how it might interact with the substrate. Clearly, the interaction between protein and substrate depends critically upon the metal centers. This study sets out to study the metal centers, to identify the role of particular residues in binding metals and the effect of perturbing the metal centers on catalytic activity. This study was never intended to make a detailed study of catalytic activity, but rather to provide background information for such studies. It was also hoped that data collected during the course of this study might shed some light on previous mechanistic studies. To achieve the objected outlined above a suitable enzyme was selected for study, which is methyl-parathion hydrolase (MPH). Its active site residues were mutated and the resulting protein variants were subjected to a variety of experiments. The effects of mutations on metal binding affinity, catalytic activity as well as overall protein stability were determined. Very early in the study, it became clear that metals ions had a significant effect on protein stability and that the apo-protein was much less stable that the fully metal bound form. Some mutations had a profound effect on activity yet caused minor changes in stability while other mutants exhibited the opposite effect. Surprisingly, in some cases removing the side-chain of a coordinating group had little effect on the affinity of the protein for the metal or on its catalytic activity. However, it was also clear that two metal ions were essential for activity; little activity was observed with a single metal ion bound to the protein. MPH has evolved to accommodate two metal ions in its active site such that minor alterations to the coordinating residues results in a loss of either stability or activity. These observation suggest that MPH has evolved to optimize activity as well as stability; the latter being important for the long-term ability of the enzyme to be an efficient catalyst.