cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Enhancing the Spectral Hardening of Cosmic TeV Photons by Mixing with Axionlike Particles in the Magnetized Cosmic Web
Creators: name: Montanino, Daniele
name: Vazza, Franco
name: Mirizzi, Alessandro
name: Viel, Matteo
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Large-scale extragalactic magnetic fields may induce conversions between very-high-energy photons and axionlike particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. However, in simplified "cell" models, used so far to represent extragalactic magnetic fields, this mechanism would be strongly suppressed by current astrophysical bounds. Here we consider a recent model of extragalactic magnetic fields obtained from large-scale cosmological simulations. Such simulated magnetic fields would have large enhancement in the filaments of matter. As a result, photon-ALP conversions would produce a significant spectral hardening for cosmic TeV photons. This effect would be probed with the upcoming Cherenkov Telescope Array detector. This possible detection would give a unique chance to perform a tomography of the magnetized cosmic web with ALPs.
description: 10 pages, 8 figures. Revised version, figures 1 and 3 changed, one figure added in the supplemental material. References added. Conclusions unchanged. Matches the published paper in PRL
The curl operator on odd-dimensional manifolds
Creators: name: Baer, Christian
Publisher: name: arXiv
Year: 2017
Subjects: subject: Differential Geometry (math.DG)
subject: Spectral Theory (math.SP)
subject: FOS: Mathematics
subject: 58J50, 78A40

description: We study the spectral properties of curl, a linear differential operator of first order acting on differential forms of appropriate degree on an odd-dimensional closed oriented Riemannian manifold. In three dimensions its eigenvalues are the electromagnetic oscillation frequencies in vacuum without external sources. In general, the spectrum consists of the eigenvalue 0 with infinite multiplicity and further real discrete eigenvalues of finite multiplicity. We compute the Weyl asymptotics and study the zeta-function. We give a sharp lower eigenvalue bound for positively curved manifolds and analyze the equality case. Finally, we compute the spectrum for flat tori, round spheres and 3-dimensional spherical space forms.
description: published version
Hydrostatic Chandra X-ray analysis of SPT-selected galaxy clusters - I. Evolution of profiles and core properties
Creators: name: Sanders, J. S.
name: Fabian, A. C.
name: Russell, H. R.
name: Walker, S. A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We analyse Chandra X-ray Observatory observations of a set of galaxy clusters selected by the South Pole Telescope using a new publicly-available forward-modelling projection code, MBProj2, assuming hydrostatic equilibrium. By fitting a powerlaw plus constant entropy model we find no evidence for a central entropy floor in the lowest-entropy systems. A model of the underlying central entropy distribution shows a narrow peak close to zero entropy which accounts for 60 per cent of the systems, and a second broader peak around 130 keV cm^2. We look for evolution over the 0.28 to 1.2 redshift range of the sample in density, pressure, entropy and cooling time at 0.015 R_500 and at 10 kpc radius. By modelling the evolution of the central quantities with a simple model, we find no evidence for a non-zero slope with redshift. In addition, a non-parametric sliding median shows no significant change. The fraction of cool-core clusters with central cooling times below 2 Gyr is consistent above and below z=0.6 (~30-40 per cent). Both by comparing the median thermodynamic profiles, centrally biased towards cool cores, in two redshift bins, and by modelling the evolution of the unbiased average profile as a function of redshift, we find no significant evolution beyond self-similar scaling in any of our examined quantities. Our average modelled radial density, entropy and cooling-time profiles appear as powerlaws with breaks around 0.2 R_500. The dispersion in these quantities rises inwards of this radius to around 0.4 dex, although some of this scatter can be fit by a bimodal model.
description: Accepted by MNRAS, 19 pages, 13 figures and appendices. Source code available at https://github.com/jeremysanders/mbproj2. This version now assumes positive K0 in the entropy analysis and includes discussion of the inner profile slopes
title: System Design Choice in the Sharing Economy: How Different Institutional Logics Drive Consumer Perception and Consumers’ Intention to Use Sharing Systems
Creators: name: Clemens, Valentin
name: Sabel, Christopher Albert
name: Foege, Johann Nils
name: Nüesch, Stephan
Publisher: name: University of Muenster, Institutional Repository MIAMI
Year: 2023
Subjects: subject: 330 Economics

description: The sharing economy provides consumers with temporary access to various products. As a growing business trend that continuously attracts new consumers, it motivates businesses to rapidly develop new system designs. In this study, we investigate how the system design choices of sharing systems for products affect consumers’ perceptions of the system and consequently their intention to use a system. Building on institutional logics, we examine how the logics inherent in two system designs—the community logic in peer-to-peer (P2P) systems and the corporate logic in business-to-consumer (B2C) systems—affect consumer perceptions. We argue that consumers perceive P2P and B2C logics differently regarding logics’ economic benefits, product scarcity, sustainability benefits, and social benefits. To test our theory, we conducted a scenario experiment with 1259 participants from the UK. Our findings suggest that consumers perceive P2P systems as yielding higher economic, sustainability, and social benefits than B2C systems, and that these benefits increase consumers’ intention to use the system. However, we also find that P2P systems suffer from the risk of product scarcity, reducing consumers’ intention to use such systems. In summary, our findings show that system design affects consumers’ perceptions and that different designs attract consumer groups with different preferences.
description: Finanziert über die DEAL-Vereinbarung mit Wiley 2019-2022.
Electrochemical Oxygen Intercalation into Sr$_2$IrO$_4$
Creators: name: Fruchter, L.
name: Brouet, V.
name: Colson, D.
name: Moussy, J. -B.
name: Forget, A.
name: Li, Z. Z.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Oxygen was electrochemically intercalated into Sr$_2$IrO$_4$ sintered samples, single crystals and a thin film. We estimate the diffusion length to a few $μ$m and the concentration of the intercalated oxygen to $δ$ $\simeq$ 0.01. The latter is thus much smaller than for the cuprate and nickelate parent compounds, for which $δ$ $>$ 0.1 is obtained, which could be a consequence of larger steric effects. The influence of the oxygen doping state on resistivity is small, indicating also a poor charge transfer to the conduction band. It is shown that electrochemical intercalation of oxygen may also contribute to doping, when gating thin films with ionic liquid in the presence of water.
Connecting Fisher information to bulk entanglement in holography
Creators: name: Banerjee, Souvik
name: Erdmenger, Johanna
name: Sarkar, Debajyoti
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In the context of relating AdS/CFT to quantum information theory, we propose a holographic dual of Fisher information metric for mixed states in the boundary field theory. This amounts to a holographic measure for the distance between two mixed quantum states. For a spherical subregion in the boundary we show that this is related to a particularly regularized volume enclosed by the Ryu-Takayanagi surface. We further argue that the quantum correction to the proposed Fisher information metric is related to the quantum correction to the boundary entanglement entropy. We discuss consequences of this connection.
description: v3: 28 pages, 1 figure. Accepted for publication in JHEP. Major update: added section 2.2 which discusses our proposal for states under scalar perturbations as well. Conclusions unchanged. Typos corrected, references added
Software compensation in Particle Flow reconstruction
Creators: name: Tran, Huong Lan
name: Krüger, Katja
name: Sefkow, Felix
name: Green, Steven
name: Marshall, John
name: Thomson, Mark
name: Simon, Frank
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The particle flow approach to calorimetry benefits from highly granular calorimeters and sophisticated software algorithms in order to reconstruct and identify individual particles in complex event topologies. The high spatial granularity, together with analogue energy information, can be further exploited in software compensation. In this approach, the local energy density is used to discriminate electromagnetic and purely hadronic sub-showers within hadron showers in the detector to improve the energy resolution for single particles by correcting for the intrinsic non-compensation of the calorimeter system. This improvement in the single particle energy resolution also results in a better overall jet energy resolution by improving the energy measurement of identified neutral hadrons and improvements in the pattern recognition stage by a more accurate matching of calorimeter energies to tracker measurements. This paper describes the software compensation technique and its implementation in particle flow reconstruction with the Pandora Particle Flow Algorithm (PandoraPFA). The impact of software compensation on the choice of optimal transverse granularity for the analogue hadronic calorimeter option of the International Large Detector (ILD) concept is also discussed.
description: 13 pages, 13 figures, v2 with wording and figure improvements, published in EPJ C
Density-of-states of many-body quantum systems from tensor networks
Creators: name: Schrodi, Fabian
name: Silvi, Pietro
name: Tschirsich, Ferdinand
name: Fazio, Rosario
name: Montangero, Simone
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We present a technique to compute the microcanonical thermodynamical properties of a manybody quantum system using tensor networks. The Density Of States (DOS), and more general spectral properties, are evaluated by means of a Hubbard-Stratonovich transformation performed on top of a real-time evolution, which is carried out via numerical methods based on tensor networks. As a consequence, the free energy and thermal averages can be also calculated. We test this approach on the one-dimensional Ising and Fermi-Hubbard models. Using matrix product states, we show that the thermodynamical quantities as a function of temperature are in very good agreement with the exact results. This approach can be extended to higher-dimensional system by properly employing other types of tensor networks.
description: 8 pages, 7 figures
Deep Text Classification Can be Fooled
Creators: name: Liang, Bin
name: Li, Hongcheng
name: Su, Miaoqiang
name: Bian, Pan
name: Li, Xirong
name: Shi, Wenchang
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cryptography and Security (cs.CR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: In this paper, we present an effective method to craft text adversarial samples, revealing one important yet underestimated fact that DNN-based text classifiers are also prone to adversarial sample attack. Specifically, confronted with different adversarial scenarios, the text items that are important for classification are identified by computing the cost gradients of the input (white-box attack) or generating a series of occluded test samples (black-box attack). Based on these items, we design three perturbation strategies, namely insertion, modification, and removal, to generate adversarial samples. The experiment results show that the adversarial samples generated by our method can successfully fool both state-of-the-art character-level and word-level DNN-based text classifiers. The adversarial samples can be perturbed to any desirable classes without compromising their utilities. At the same time, the introduced perturbation is difficult to be perceived.
description: 8 pages
Reshetnyak rigidity for Riemannian manifolds
Creators: name: Kupferman, Raz
name: Maor, Cy
name: Shachar, Asaf
Publisher: name: arXiv
Year: 2017
Subjects: subject: Differential Geometry (math.DG)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 53C24, 58E20, 74B20

description: We prove two rigidity theorems for maps between Riemannian manifolds. First, we prove that a Lipschitz map $f:M\to N$ between two oriented Riemannian manifolds, whose differential is almost everywhere an orientation-preserving isometry, is an isometric immersion. This theorem was previously proved using regularity theory for conformal maps; we give a new, simple proof, by generalizing the Piola identity for the cofactor operator. Second, we prove that if there exists a sequence of mapping $f_n:M\to N$, whose differentials converge in $L^p$ to the set of orientation-preserving isometries, then there exists a subsequence converging to an isometric immersion. These results are generalizations of celebrated rigidity theorems by Liouville (1850) and Reshetnyak (1967) from Euclidean to Riemannian settings. Finally, we describe applications of these theorems to non-Euclidean elasticity and to convergence notions of manifolds.
description: Formerly titled: Asymptotic rigidity of Riemannian manifolds. Version 2: a completely rewritten Section 2 (Section 3 in version 1) with new proofs; major edits in Sections 1 and 3.1 (formerly 2.2) and the appendices. Version 3: Title change; Section 1.3 (applications) expanded; other minor changes
Irreducible components of minuscule affine Deligne-Lusztig varieties
Creators: name: Hamacher, Paul
name: Viehmann, Eva
Publisher: name: arXiv
Year: 2017
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: We examine the set of $J_b(F)$-orbits in the set of irreducible components of affine Deligne-Lusztig varieties for a hyperspecial subgroup and minuscule coweight $μ$. Our description implies in particular that its number of elements is bounded by the dimension of a suitable weight space in the Weyl module associated with $μ$ of the dual group.
description: 21 pages, v2: small corrections, removed Lemma 1.3
A neural marker of obsessive-compulsive disorder from whole-brain functional connectivity
Creators: name: Takagi, Yu
name: Sakai, Yuki
name: Lisi, Giuseppe
name: Yahata, Noriaki
name: Abe, Yoshinari
name: Nishida, Seiji
name: Nakamae, Takashi
name: Morimoto, Jun
name: Kawato, Mitsuo
name: Narumoto, Jin
name: Tanaka, Saori C.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: FOS: Biological sciences

description: Obsessive-compulsive disorder (OCD) is a common psychiatric disorder with a lifetime prevalence of 2-3 percent. Recently, brain activity in the resting state is gathering attention as a new means of exploring altered functional connectivity in psychiatric disorders. Although previous resting-state functional magnetic resonance imaging studies investigated neurobiological abnormalities of patients with OCD, there are concerns that should be addressed. One concern is the validity of the hypothesis employed. Most studies used seed-based analysis of the fronto-striatal circuit, despite the potential for abnormalities in other regions. A hypothesis-free study is a promising approach in such a case, while it requires researchers to handle a dataset with large dimensions. Another concern is the reliability of biomarkers derived from a single dataset, which may be influenced by cohort-specific features. Here, by employing a recently developed machine-learning algorithm to avoid these concerns, we identified the first OCD biomarker that is generalized to an external dataset. We also demonstrated that the functional connectivities that contributed to the classification were widely distributed rather than locally constrained. Our generalizable classifier has the potential not only to deepen our understanding of the abnormal neural substrates of OCD but also to find use in clinical applications.
description: 47 pages, 3 figures
Digital Engagement Focus Report
Creators: name: Bonelli, Giulia
name: Boscolo, Marco
name: Tola, Elisabetta
Publisher: name: Zenodo
Year: 2022
Subjects: Engagement
Engaged science journalism
ENJOI
innovation

description: * New version available * This Digital Engagement Focus Report (Deliverable 7.1) is the result of a first track of research exploring how digital media have exploited engagement in covering science.
description: ENJOI WP7. Exploring the existing landscape of innovation and openness in science journalism and communication
Digital Engagement Focus Report
Creators: name: Bonelli, Giulia
name: Boscolo, Marco
name: Tola, Elisabetta
Publisher: name: Zenodo
Year: 2021
Subjects: Engagement
Engaged science journalism
ENJOI
innovation

description: This Digital Engagement Focus Report (Deliverable 7.1) is the result of a first track of research exploring how digital media have exploited engagement in covering science.
description: ENJOI WP7. Exploring the existing landscape of innovation and openness in science journalism and communication
Anisotropic hydrodynamic modeling of 2.76 TeV Pb-Pb collisions
Creators: name: Alqahtani, Mubarak
name: Nopoush, Mohammad
name: Ryblewski, Radoslaw
name: Strickland, Michael
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We compare phenomenological results from 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) with experimental data collected in LHC 2.76 TeV Pb-Pb collisions. In particular, we present comparisons of particle spectra, average transverse momentum, elliptic flow, and HBT radii. The aHydroQP model relies on the introduction of a single temperature-dependent quasiparticle mass which is fit to lattice QCD data. By taking moments of the resulting Boltzmann equation, we obtain the dynamical equations used in the hydrodynamic stage which include the effects of both shear and bulk viscosities. At freeze-out, we use anisotropic Cooper-Frye freeze-out performed on a fixed-energy-density hypersurface to convert to hadrons. To model the production and decays of the hadrons we use THERMINATOR 2 which is customized to sample from ellipsoidal momentum-space distribution functions. Using smooth Glauber initial conditions, we find very good agreement with many heavy-ion collision observables.
description: 31 pages, 9 figures. v2 - improvements to HBT calculation + typos fixed; PRC version. arXiv admin note: text overlap with arXiv:1703.05808
Semantic component selection
Creators: name: Sjachyn, Maxym
Publisher: name: University of Westminster
Year: 2009

description: The means of locating information quickly and efficiently is a growing area of research. However the real challenge is not related to locating bits of information, but finding those that are relevant. Relevant information resides within unstructured ‘natural’ text. However, understanding natural text and judging information relevancy is a challenge. The challenge is partially addressed by use of semantic models and reasoning approaches that allow categorisation and (within limited fashion) provide understanding of this information. Nevertheless, many such methods are dependent on expert input and, consequently, are expensive to produce and do not scale. Although automated solutions exist, thus far, these have not been able to approach accuracy levels achievable through use of expert input. This thesis presents SemaCS - a novel nondomain specific automated framework of categorising and searching natural text. SemaCS does not rely on expert input; it is based on actual data being searched and statistical semantic distances between words. These semantic distances are used to perform basic reasoning and semantic query interpretation. The approach was tested through a feasibility study and two case studies. Based on reasoning and analyses of data collected through these studies, it can be concluded that SemaCS provides a domain independent approach of semantic model generation and query interpretation without expert input. Moreover, SemaCS can be further extended to provide a scalable solution applicable to large datasets (i.e. World Wide Web). This thesis contributes to the current body of knowledge by establishing, adapting, and using novel techniques to define a generic selection/categorisation framework. Implementing the framework outlined in the thesis improves an existing algorithm of semantic distance acquisition. Finally, as a novel approach to the extraction of semantic information is proposed, there exists a positive impact on Information Retrieval domain and, specifically, on Natural Language Processing, word disambiguation and Web/Intranet search.
Counting Arithmetical Structures on Paths and Cycles
Creators: name: Braun, Benjamin
name: Corrales, Hugo
name: Corry, Scott
name: Puente, Luis David García
name: Glass, Darren
name: Kaplan, Nathan
name: Martin, Jeremy L.
name: Musiker, Gregg
name: Valencia, Carlos E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Combinatorics (math.CO)
subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: Let $G$ be a finite, simple, connected graph. An arithmetical structure on $G$ is a pair of positive integer vectors $\mathbf{d},\mathbf{r}$ such that $(\mathrm{diag}(\mathbf{d})-A)\mathbf{r}=0$, where $A$ is the adjacency matrix of $G$. We investigate the combinatorics of arithmetical structures on path and cycle graphs, as well as the associated critical groups (the cokernels of the matrices $(\mathrm{diag}(\mathbf{d})-A)$). For paths, we prove that arithmetical structures are enumerated by the Catalan numbers, and we obtain refined enumeration results related to ballot sequences. For cycles, we prove that arithmetical structures are enumerated by the binomial coefficients $\binom{2n-1}{n-1}$, and we obtain refined enumeration results related to multisets. In addition, we determine the critical groups for all arithmetical structures on paths and cycles.
Localized Faraday patterns under heterogeneous parametric excitation
Creators: name: Urra, Héctor
name: Marín, Juan F.
name: Páez-Silva, Milena
name: Taki, Majid
name: Coulibaly, Saliya
name: Gordillo, Leonardo
name: García-Ñustes, Mónica A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Faraday waves are a classic example of a system in which an extended pattern emerges under spatially uniform forcing. Motivated by systems in which uniform excitation is not plausible, we study both experimentally and theoretically the effect of heterogeneous forcing on Faraday waves. Our experiments show that vibrations restricted to finite regions lead to the formation of localized subharmonic wave patterns and change the onset of the instability. The prototype model used for the theoretical calculations is the parametrically driven and damped nonlinear Schrödinger equation, which is known to describe well Faraday-instability regimes. For an energy injection with a Gaussian spatial profile, we show that the evolution of the envelope of the wave pattern can be reduced to a Weber-equation eigenvalue problem. Our theoretical results provide very good predictions of our experimental observations provided that the decay length scale of the Gaussian profile is much larger than the pattern wavelength.
description: 10 pages, 9 figures, Accepted
Superconducting-Gravimeter Tests of Local Lorentz Invariance
Creators: name: Flowers, Natasha A.
name: Goodge, Casey
name: Tasson, Jay D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Superconducting-gravimeter measurements are used to test the local Lorentz invariance of the gravitational interaction and of matter-gravity couplings. The best laboratory sensitivities to date are achieved via a maximum-reach analysis for 13 Lorentz-violating operators, with some improvements exceeding an order of magnitude.
description: 5 pages, 1 figure, published version
Harmonic analysis in phase space and finite Weyl-Heisenberg ensembles
Creators: name: Abreu, Luís Daniel
name: Gröchenig, Karlheinz
name: Romero, José Luis
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: Functional Analysis (math.FA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Weyl-Heisenberg ensembles are translation-invariant determinantal point processes on $\mathbb{R}^{2d}$ associated with the Schrödinger representation of the Heisenberg group, and include as examples the Ginibre ensemble and the polyanalytic ensembles, which model the higher Landau levels in physics. We introduce finite versions of the Weyl-Heisenberg ensembles and show that they behave analogously to the finite Ginibre ensembles. More specifically, guided by the observation that the Ginibre ensemble with $N$ points is asymptotically close to the restriction of the infinite Ginibre ensemble to the disk of area $N$, we define finite WH ensembles as adequate finite approximations of the restriction of infinite WH ensembles to a given domain $Ω$. We provide a precise rate for the convergence of the corresponding one-point intensities to the indicator function of $Ω$, as $Ω$ is dilated and the process is rescaled proportionally (thermodynamic regime). The construction and analysis rely neither on explicit formulas nor on the asymptotics for orthogonal polynomials, but rather on phase-space methods. Second, we apply our construction to study the pure finite Ginibre-type polyanalytic ensembles, which model finite particle systems in a single Landau level, and are defined in terms of complex Hermite polynomials. On a technical level, we show that finite WH ensembles provide an approximate model for finite polyanalytic Ginibre ensembles, and we quantify the corresponding deviation. By means of this asymptotic description, we derive estimates for the rate of convergence of the one-point intensity of polyanalytic Ginibre ensembles in the thermodynamic limit.
description: 36 pages, 4 figures
Acoustic Traps and Lattices for Electrons in Semiconductors
Creators: name: Schuetz, Martin J. A.
name: Knörzer, Johannes
name: Giedke, Geza
name: Vandersypen, Lieven M. K.
name: Lukin, Mikhail D.
name: Cirac, J. Ignacio
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We propose and analyze a solid-state platform based on surface acoustic waves (SAWs) for trapping, cooling and controlling (charged) particles, as well as the simulation of quantum many-body systems. We develop a general theoretical framework demonstrating the emergence of effective time-independent acoustic trapping potentials for particles in two- or one-dimensional structures. As our main example we discuss in detail the generation and applications of a stationary, but movable acoustic pseudo-lattice (AL) with lattice parameters that are reconfigurable in situ. We identify the relevant figures of merit, discuss potential experimental platforms for a faithful implementation of such an acoustic lattice, and provide estimates for typical system parameters. With a projected lattice spacing on the scale of 100nm, this approach allows for relatively large energy scales in the realization of fermionic Hubbard models, with the ultimate prospect of entering the low temperature, strong interaction regime. Experimental imperfections as well as read-out schemes are discussed.
description: Manuscript: 10.5 pages, 5 figures, 1 table. Appendices: 8 pages, 1 table. v2: version as published, Journal-Ref added
Role of human β-defensins in human burn wounds
Creators: name: Syed, Mobin
Publisher: name: University of Westminster
Year: 2009

description: Background - Burns is a complex condition requiring assessment and addressing of both the wound and the patient in a holistic way. In spite of tremendous improvements in burn care, infection continues to remain an important cause of morbidity and mortality. Human Β Defensins (HBD) are a group of recently discovered antimicrobial peptides. The main subtypes include HBD1, 2 and 3 and are individually known to have other functions apart from being anti-microbial. Some of these are inherently expressed while others are induced in response to microbial challenge. Aims - The aim of the current PhD was to understand the pattern of expression of HBDs in acute burns, their source of expression, and factors influencing the expression, with a view to use these peptides as therapeutic agents in future. Methods - The expression of HBD1, 2 & 3 was determined at mRNA and protein levels in acute burn wounds of different burn durations, using real time rt-PCR and immunohistochemistry, respectively. The influence of type and quantity of bacteria, contribution from blood cells and the influence of stress on HBD expression was determined in separate clinical situations similar to those seen in major burns. Results - The results show that HBD1, 2 and 3 mRNA is highly expressed in both early and late burns, but a parallel increase is not reciprocated at protein levels. The bacteria isolated from the burn wounds showed a trend changing from colonising organisms to more resistant forms in time, however no significant correlation with HBD was established. Peripheral blood cells produced HBD in response to inflammatory mediator’s in-vivo, thus suggesting to a possible contribution of HBD 1, 2 and 3 from blood cells in granulating burn wounds. There was no down regulation of HBD1, 2 and 3 in the presence of increased cortisol levels – a reflection of heightened stress as seen in burns. HBD1 and 3 mRNA expressions showed an early up-regulation, followed by elevation in HBD2 mRNA levels. There was no HBD2 mRNA and protein expression in keloid tissue specimens from various parts of the body. The absence of HBD2 – a unique intrinsic peptide with an ability to trigger the anti-fibrotic cytokines suggests to the possibility that HBD’s are implicated in the pathogenesis of keloids, which are usually associated with burn scars. Conclusion - The studies suggest a possible role of HBD in the pathogenesis of burn wounds and the potential to use these as therapeutic peptides to prevent infections and scarring associated with burns.
Mediated encounters in diasporic space:exploring processes of transculturation syncretism and identity redefinition in the Ghanaian diaspora in London
Creators: name: Adjetey, Nii
Publisher: name: University of Westminster
Year: 2010

description: This thesis explores the diasporic experiences of Ghanaians in London and assesses how Ghanaian identity is redefined and constructed in new contexts. The mediated experience dimension of this exploration considers the difference that the diverse menu of cultural resources offered by television is making to dispositions, cultural proclivities, and patterns of identification across intergenerational differences among Ghanaian-Londoners. The study qualitatively assembles and analyses empirical data from primary sources and integrates material from secondary sources to draw its conclusions. The thesis traces the development of the black diaspora as the historical antecedent or precursor to more recent black diasporic formations. The concept of the black diaspora provides a context for understanding or imagining the fledgling Ghanaian diaspora as another offshoot within the family of black identities in Britain. It is argued that the perceptions of blackness that Ghanaian- Londoners encountered in Britain were derived from the racial construction of blackness as the antithesis of whiteness and hence its construction as deviance. This was purveyed in discourses and reinforced in the public imagination through the media. Not only did it run counter to their self-perceptions, it impinged on their experiences as black people as they were confronted with unflattering stereotypes which they repudiated. In marginal spaces they endeavoured to reinstitute traditions from the homeland and to establish a distinctive presence in the ensemble of black identities in Britain, which in part challenges the monolithic imaginations of blackness from ‘othering’ perspectives, and also highlights an area of blackness underrepresented in academic discourses. Furthermore, the study finds that in their cultural consumption, a factor of their diasporic experience, they exhibited a critical edge and a comparative attitude to screen representations, reflecting the dual and sometimes multiple perspectives of their diasporic condition which enabled them to critique or valorise certain cultural practices from the different worlds of their experience, an indication of processes of cultural negotiation, synthesis, and hybridisation. Overall, this thesis contributes to current academic debates around mediated experience and cultural transformations, and the understanding of processes at the intersections between modernity, diaspora and culture in the era of globalization.
Firm-level responses to monetary union and exchange rate regime: evidence from Cote D’Ivoire and Ghana
Creators: name: Atsin, Sika
Publisher: name: University of Westminster
Year: 2010

description: This study investigated the impact of the exchange rate regime as well as monetary union on businesses in West African countries based on two cases: Cote d’Ivoire and Ghana. Explicitly, the main hypothesis covers Ivorian and Ghanaian firms’ responses to monetary union and exchange rate regime. Two sets of questionnaires needed one in French for Ivorian firms and the other one in English for companies in Ghana. 250 questionnaires had been sent across both countries, Cote d’Ivoire and Ghana. 57 Ivorian companies responded while only 43 Ghanaian were available to fill the questionnaire in. This represents a total response rate of 40 percent, which is appropriate, efficient and adequate for this research study. Mostly, the empirical results based on the primary information and supported with secondary data, strongly confirmed all of the research hypotheses. The study found that being member of the CFA zone with a pegged currency to the Euro has helped expand Cote d’Ivoire’s trade with the European Union in comparison with Ghana. The trade statistics in chapter 5 sections 5.3 of the thesis shows evidence of high trade flows from Cote d’Ivoire to the European Union as well as the Rest of the World. That trade expansion has helped Cote d’Ivoire’s growth despite its instability due to the military and political upraising. Exports played a vital role in the development of African countries, especially in Cote d’Ivoire. During the period 1973-2005, exports represent on average 39.9 percent of the Ivorian GDP and imports of goods and services 35.9 percent. While Ghana’s exports represent only 20 percent of its GDP and its imports of goods and services 27.2 percent for the same period. Again, the questionnaire-survey shows that overwhelmingly, all firms in both Cote d’Ivoire and Ghana agreed on issues related to the benefit of a monetary union and trade with the European Union with a strong passion on the benefit of operating in a fixed exchange rate regime. Therefore, they all supported the hypothesis that membership of a monetary union is beneficial to member states. At the microeconomic level, a monetary union has to be a strong combination of competitiveness and solidarity by taking into account modernisation of social policies. Also, it has to be based on growth or output, higher employment and higher productivity. Finally, a monetary union brings small and medium size enterprises more choices and business opportunities, which will be stronger and more competitive. Large corporations enjoy the eradication of cross-border operations and competition. Again, wealth is created at the microeconomic level through the ability for firms to produce valuable goods and services using efficient methods.
Comparison of the Iterated Equation of Motion Approach and the Density Matrix Formalism for the Quantum Rabi Model
Creators: name: Kalthoff, Mona H.
name: Keim, Frederik
name: Krull, Holger
name: Uhrig, Götz S.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The density matrix formalism and the equation of motion approach are two semi-analytical methods that can be used to compute the non-equilibrium dynamics of correlated systems. While for a bilinear Hamiltonian both formalisms yield the exact result, for any non-bilinear Hamiltonian a truncation is necessary. Due to the fact that the commonly used truncation schemes differ for these two methods, the accuracy of the obtained results depends significantly on the chosen approach. In this paper, both formalisms are applied to the quantum Rabi model. This allows us to compare the approximate results and the exact dynamics of the system and enables us to discuss the accuracy of the approximations as well as the advantages and the disadvantages of both methods. It is shown to which extent the results fulfill physical requirements for the observables and which properties of the methods lead to unphysical results.
description: 13 pages, 4 figures
Non-Markovianity Quantifier of an Arbitrary Quantum Process
Creators: name: Debarba, Tiago
name: Fanchini, Felipe F.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Calculating the degree of non-Markovianity of a dissipative process is a difficult task, even for the dynamics of a single qubit, given the complex maximization problem. In this work, focusing on the entanglement-based quantifier of non-Markovianity, we present an analytical solution for such an optimization problem. We then propose a computable non-Markovianity measure based on generalized robustness of entanglement, an entanglement measure that can be readily calculated by a semidefinite programming method. We show that the non-Markovianity, in a given interval of time, can be witnessed by calculating the expectation value of an observable, making it attractive for experimental investigations.
description: 7 pages, 2 figures
Daten zur Vogelwelt in Deutschland
Creators: name: Reiners, Tobias Erik
name: Katzenberger, Jakob
name: Schwarz, Johannes
name: Wahl, Johannes
name: Sudfeldt, Christoph
Publisher: name: Zenodo
Year: 2022
Subjects: AllHands4Biodiv
Monitoring

description: Der Dachverband Deutscher Avifaunisten e.V. (DDA) ist der Zusammenschluss aller landesweiten und vieler regionaler ornithologischer Fachverbände in Deutschland. Er berät das Bundesumweltministerium, das Bundesamt für Naturschutz sowie entsprechende Einrichtungen der Bundesländer in fachlichen Fragen zur Erhaltung und zum Schutz der heimischen Artenvielfalt. Zusammen mit Akteuren der Biodiversitätsforschung führt der DDA wissenschaftliche Projekte durch; zur Erfüllung seiner Vereinszwecke organisiert und koordiniert er zudem das bundesweite Monitoring zur Erfassung von Brutund Rastvögeln und betreibt das Online-Portal ornitho.de. Insgesamt stellen mehr als 50.000 Ehrenamtliche jährlich mehr als 10 Millionen Beobachtungsdaten für vorgenannte Zwecke zur Verfügung. Ziel des Use Case ist es, die umfangreichen Datensätze des DDA zur Verbreitung und Häufigkeit von Vogelarten für die NFDI nutzbar zu machen, sie mit anderen Datensätzen zu verknüpfen, sie an die gemeinsame NFDI-Infrastruktur anzuschließen und sie für die Forschungsgemeinschaft wie auch die Öffentlichkeit sichtbar zu machen.
Sterile neutrinos in cosmology
Creators: name: Abazajian, Kevork N.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Sterile neutrinos are natural extensions to the standard model of particle physics in neutrino mass generation mechanisms. If they are relatively light, less than approximately 10 keV, they can alter cosmology significantly, from the early Universe to the matter and radiation energy density today. Here, we review the cosmological role such light sterile neutrinos can play from the early Universe, including production of keV-scale sterile neutrinos as dark matter candidates, and dynamics of light eV-scale sterile neutrinos during the weakly-coupled active neutrino era. We review proposed signatures of light sterile neutrinos in cosmic microwave background and large scale structure data. We also discuss keV-scale sterile neutrino dark matter decay signatures in X-ray observations, including recent candidate $\sim$3.5 keV X-ray line detections consistent with the decay of a $\sim$7 keV sterile neutrino dark matter particle.
description: Accepted version of an invited review for Physics Reports. 33 pages, 7 figures, approximately 16,000 words; v3: expanded discussion of low reheating temperature universe models with a new figure, large scale structure effects, scalar decay models
Integrating formal reasoning into component-based approach to reconfigurable distributed systems
Creators: name: Basso, Alessandro
Publisher: name: University of Westminster
Year: 2010

description: Distributed computing is becoming ubiquitous in recent years in many areas, especially the scientific and industrial ones, where the processing power - even that of supercomputers - never seems to be enough. Grid systems were born out of necessity, and had to grow quickly to meet requirements which evolved over time, becoming today’s complex systems. Even the simplest distributed system nowadays is expected to have some basic functionalities, such as resources and execution management, security and optimization features, data control, etc. The complexity of Grid applications is also accentuated by their distributed nature, making them some of the most elaborate systems to date. It is often too easy that these intricate systems happen to fall in some kind of failure, it being a software bug, or plain simple human error; and if such a failure occurs, it is not always the case that the system can recover from it, possibly meaning hours of wasted computational power. In this thesis, some of the problems which are at the core of the development and maintenance of Grid software applications are addressed by introducing novel and solid approaches to their solution. The difficulty of Grid systems to deal with unforeseen and unexpected circumstances resulting from dynamic reconfiguration can be identified. Such problems are often related to the fact that Grid applications are large, distributed and prone to resource failures. This research has produced a methodology for the solution of this problem by analysing the structure of distributed systems and their reliance on the environment which they sit upon, often overlooked when dealing with these types of scenarios. It is concluded that the way that Grid applications interact with the infrastructure is not sufficiently addressed and a novel approach is developed in which formal verification methods are integrated with distributed applications development and deployment in a way that includes the environment. This approach allows for reconfiguration scenarios in distributed applications to proceed in a safe and controlled way, as demonstrated by the development of a prototype application.
Calculation of quantum discord in arbitrary dimensions, especially for X- and other specialized states
Creators: name: Rau, A. R. P.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum discord, a kind of quantum correlation based on entropic measures, is defined as the difference between quantum mutual information and classical correlation in a bipartite system. Procedures are available for analytical calculation of discord when one of the parties is a qubit with dimension two and measurements made on it to get that one-way discord. We extend now to systems when both parties are of larger dimension, of interest to qudit-quDit with d, D > 2 or spin chains of spins > 1/2. While recognizing that no universal scheme is feasible, applicable to all density matrices, nevertheless a procedure similar to that for d=2 that works for many mixed-state density matrices remains of interest as shown by recent such applications. We focus on this method that uses unitary operations to describe measurements, reducing them to a compact form so as to minimize the number of variables needed for extremizing the classical correlation, often the most difficult part of the discord calculation. Results are boiled down to a simple recipe for that extremization; for some classes of density matrices, the procedure even gives trivially the final value of the classical correlation without that extremization. A qutrit-qutrit (d=D=3) system is discussed in detail with specific applications to density matrices for whom other calculations involved difficult numerics. Special attention is given to the so-called X-states and Werner and isotropic states when the calculations become particularly simple. An appendix discusses an independent but related question of the systematics of X-states of arbitrary dimension. It forms a second, separate, part of this paper, extending our previous group-theoretic considerations of systematics for qubits now to higher d.
description: 8 pages, changes from v1
KO'HNA XAROBALAR SARI YO'L – TUPROQQAL'A TARIXIDAN
Creators: name: Zaripboyeva, Umida
Publisher: name: Zenodo
Year: 2024

description: Ushbu maqolada Xorazmning qadimgi poytaxtlaridan biri bo’lgan va hozirga qadar saqlanib qolgan, yirik arxeologik inshoot, Xorazmning qadimgi davri haqida batafsil ma’lumot beruvchi Tuproqqal’a qal’asi va uning tarixi haqida ma’lumot.
Three-body interaction effects on the ground state of one-dimensional anyons
Creators: name: Arcila-Forero, J.
name: Franco, R.
name: Silva-Valencia, J.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: A quantum phase transition driven by the statistics was observed in an anyon-Hubbard model with local three-body interactions. Using a fractional Jordan-Wigner transformation, we arrived at a modified Bose-Hubbard model, which exhibits Mott insulator and superfluid phases. The absence of a Mott insulator state with one particle per site depends on the anyonic angle, and a quantum phase transition from a superfluid to a Mott insulator state is obtained for a fixed value of the hopping. The critical points were estimated with the von Neumann block entropy and increase as the hopping grows. The statistics modify the ground state, and three different superfluid regions were observed for larger values of the anyonic angle.
description: 8 pages, 9 figures. The title of the paper changed. Published version