cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
XMM-Newton view of the shock heating in an early merging cluster, CIZA J1358.9$-$4750
Creators: name: Omiya, Y.
name: Nakazawa, K.
name: Matsushita, K.
name: Kobayashi, S. B.
name: Okabe, N.
name: Sato, K.
name: Tamura, T.
name: Fujita, Y.
name: Gu, L.
name: Kitayama, T.
name: Akahori, T.
name: Kurahara, K.
name: Yamaguchi, T.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: CIZA J1358.9-4750 is a nearby galaxy cluster in the early phase of a major merger. The two-dimensional temperature map using XMM-Newton EPIC-PN observation confirms the existence of a high temperature region, which we call the "hot region", in the "bridge region" connecting the two clusters. The ~ 500 kpc wide region between the southeast and northwest boundaries also has higher pseudo pressure compared to the unshocked regions, suggesting the existence of two shocks. The southern shock front is clearly visible in the X-ray surface brightness image and has already been reported by Kato et al. (2015). The northern one, on the other hand, is newly discovered. To evaluate their Mach number, we constructed a three-dimensional toy merger model with overlapping shocked and unshocked components in line of sight. The unshocked and preshock ICM conditions are estimated based on those outside the interacting bridge region assuming point symmetry. The hot region spectra are modeled with two-temperature thermal components, assuming that the shocked condition follows the Rankin-Hugoniot relation with the preshock condition. As a result, the shocked region is estimated to have a line-of-sight depth of ~ 1 Mpc with a Mach number of ~ 1.3 in the southeast shock and ~ 1.7 in the northwest shock. The age of the shock waves is estimated to be ~ 260 Myr. This three dimensional merger model is consistent with the Sunyaev-Zeldovich signal obtained using the Planck observation within the CMB fluctuations. The total flow of the kinetic energy of the ICM through the southeast shock was estimated to be ~ 2.2 x $10^{42}$ erg/s. Assuming that 10 % of this energy is converted into ICM turbulence, the line-of-sight velocity dispersion is calculated to be ~ 200 km/s, which is basically resolvable via coming high spectral resolution observations.
Bayesian optimization of discrete dislocation plasticity of two-dimensional precipitation hardened crystals
Creators: name: Sarvilahti, Mika
name: Laurson, Lasse
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Discovering relationships between materials' microstructures and mechanical properties is a key goal of materials science. Here, we outline a strategy exploiting Bayesian optimization to efficiently search the multidimensional space of microstructures, defined here by the size distribution of precipitates (fixed impurities or inclusions acting as obstacles for dislocation motion) within a simple two-dimensional discrete dislocation dynamics model. The aim is to design a microstructure optimizing a given mechanical property, e.g., maximizing the expected value of shear stress for a given strain. The problem of finding the optimal discretized shape for a distribution involves a norm constraint, and we find that sampling the space of possible solutions should be done in a specific way in order to avoid convergence problems. To this end, we propose a general mathematical approach that can be used to generate trial solutions uniformly at random while enforcing an Euclidean norm constraint. Both equality and inequality constraints are considered. A simple technique can then be used to convert between Euclidean and other Lebesgue $p$-norm (the 1-norm in particular) constrained representations. Considering different dislocation-precipitate interaction potentials, we demonstrate the convergence of the algorithm to the optimal solution and discuss its possible extensions to the more complex and realistic case of three-dimensional dislocation systems where also the optimization of precipitate shapes could be considered.
description: 12 pages, 10 figures, accepted for publication in Physical Review Materials
Path integral suppression of badly behaved causal sets
Creators: name: Carlip, P.
name: Carlip, S.
name: Surya, S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Causal set theory is a discrete model of spacetime that retains a notion of causal structure. We understand how to construct causal sets that approximate a given spacetime, but most causal sets are not at all manifold-like, and must be dynamically excluded if something like our universe is to emerge from the theory. Here we show that the most common of these "bad" causal sets, the Kleitman-Rothschild orders, are strongly suppressed in the gravitational path integral, and we provide evidence that a large class of other "bad" causal sets are similarly suppressed. It thus becomes plausible that continuum behavior could emerge naturally from causal set quantum theory.
description: 10 pages, 2 figures
Line shape parameters of PH₃ transitions: Theoretical studies of self-broadened widths and line mixing effects
Creators: name: Boulet, Christian
name: Ma, Qiancheng
Publisher: name: Columbia University
Year: 2020
Subjects: Chemistry, Physical and theoretical
Gas laws (Physical chemistry)
Molecular rotation
Radiative transitions

description: Line mixing effects have been calculated in various parallel and perpendicular bands of self-broadened PH₃ lines and compared with recent experimental data. The theoretical approach is an extension to symmetric tops with high inversion barrier of the formalism previously developed for NH₃ (Q. Ma and C. Boulet J. Chem. Phys. 144, 224303 (2016)). The model takes into account the non diagonality of the scattering operator within the linespace as well as, in a correct way, the double degeneracy of the j, k levels when k ≠ 0. Transitions between such levels should be considered as doublets whose components may be coupled by the line mixing process. It has been shown that, at low pressure, the inversion of the experimental data will strongly depend on the splitting between the two components of a doublet. When it is significant, one can measure independently both the width of one component and the intra-doublet coupling matrix element. Otherwise, one can only measure the sum of these two elements. Comparisons with measurements show that the present formalism leads to accurate predictions of the experimental line shapes.
title: Ενσωματωμένο σύστημα για ιχνηλάτηση σταθερών κατευθυντικών κεραιών από κινούμενα οχήματα
Creators: name: Αποστολάκης Σταύρος
Publisher: name: Technical University of Crete
Year: 2011

description: Μη διαθέσιμο
CIV Line-Width Anomalies: The Perils of Low S/N Spectra
Creators: name: Denney, Kelly D.
name: Pogge, Richard W.
name: Assef, Roberto J.
name: Kochanek, Christopher S.
name: Peterson, Bradley M.
name: Vestergaard, Marianne
Publisher: name: arXiv
Year: 2013
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Comparison of six high-redshift quasar spectra obtained with the Large Binocular Telescope with previous observations from the Sloan Digital Sky Survey shows that failure to correctly identify absorption and other problems with accurate characterization of the CIV emission line profile in low S/N data can severely limit the reliability of single-epoch mass estimates based on the CIV emission line. We combine the analysis of these new high-quality data with a reanalysis of three other samples based on high S/N spectra of the CIV emission line region. We find that a large scatter between the Hbeta- and CIV-based masses remains even for this high S/N sample when using the FWHM to characterize the BLR velocity dispersion and the standard virial assumption to calculate the mass. However, we demonstrate that using high-quality data and the line dispersion to characterize the CIV line width leads to a high level of consistency between CIV- and Hbeta-based masses, with <0.3 dex of observed scatter, and an estimated ~0.2 dex intrinsic scatter, in the mass residuals.
description: 15 pages of emulate-ApJ text, including 8 figures + 5 included tables. Accepted for publication in The Astrophysical Journal (v2 represents changes over v1 including minor revision from referee suggestions and a newly included discussion section showing our results in context to those of Park et al. 2013, ApJ, 770, 87)
Effect of reaction time on the phase transformation and photocatalytic activity under solar irradiation of tungsten oxide nanocuboids prepared via facile hydrothermal method
Creators: name: Nguyen, Cong Tu
name: Pham, Ngoc Linh
name: Nguyen, Thi Thuy
name: Tho, Duc
name: Luu, T. Lan Anh
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Biochemistry
subject: Microbiology
subject: FOS: Biological sciences
subject: Cell Biology
subject: Molecular Biology
subject: Biotechnology
subject: Evolutionary Biology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Inorganic Chemistry

description: Monoclinic WO3 nanocuboids were synthesized via a one-pot hydrothermal method in a highly acidic environment at 180°C for different reaction times (12, 24, and 48 h). The phase transformation from orthorhombic to monoclinic and then to oxygen-deficient Magnéli phase and an increase in optical bandgap from 2.43 to 2.70 eV were observed when the reaction time increased from 12 to 24 h and then to 48 h. All samples showed photocatalytic activity towards the degradation of methylene blue (MB) under solar light irradiation, which was strongly enhanced in the presence of hydrogen peroxide (H2O2). Sample prepared for 24 h showed the highest MB removal efficiency of 31.4% in the absence of H2O2, which was enhanced to 76% and 92% when adding 0.2 and 0.5 mL of H2O2, respectively. These results give insights into the phase transformation and photocatalytic mechanism of WO3 nanocuboids prepared via the hydrothermal method.
"Where Do You Stand?"
Creators: name: Flowers, Deidre Bennett
Publisher: name: Columbia University
Year: 2016
Subjects: African American women college students
College students--Political activity
African American universities and colleges
Civil rights movements

description: This blog post highlights the activism of the women students at Bennett College for Women as articulated by Roslyn Cheagle, president of the college's Student Senate. Cheagle's article is a call to action for students in the Greensboro, North Carolina area to take a stand against segregation. The student's actions continue the College's long history of involvement in protest and activism that dates back to the early years after its conversion, in 1926, to a college solely for women.
Real-space BCS-BEC crossover in FeSe monolayer
Creators: name: Lin, Haicheng
name: Huang, Wantong
name: Rai, Gautam
name: Yin, Yuguo
name: He, Lianyi
name: Xue, Qi-Kun
name: Haas, Stephan
name: Kettemann, Stefan
name: Chen, Xi
name: Ji, Shuai-Hua
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The quantum many body states in the BCS-BEC crossover regime are of long-lasting interest. Here we report direct spectroscopic evidence of BCS-BEC crossover in real-space in a FeSe monolayer thin film by using spatially resolved scanning tunneling spectra. The crossover is driven by the shift of band structure relative to the Fermi level. The theoretical calculation based on a two-band model qualitatively reproduces the measured spectra in the whole crossover range. In addition, the Zeeman splitting of the quasi-particle states is found to be consistent with the characteristics of a condensate. Our work paves the way to study the exotic states of BCS-BEC crossover in a two-dimensional crystalline material at the atomic scale.
Prediction of first-order martensitic transitions in strained epitaxial films
Creators: name: Schönecker, Stephan
name: Richter, Manuel
name: Koepernik, Klaus
name: Eschrig, Helmut
Publisher: name: arXiv
Year: 2013
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Coherent epitaxial growth allows to produce crystalline films with strained structures which are unstable in the bulk. Thereby, the relationship between the lattice parameters of the overlayer in the interface plane, $(a,b)$, and its minimum-energy out-of-plane lattice parameter, $c_{\text{min}}(a,b)$, need not be continuous. This general statement is proven by examples of total energy calculations. As a consequence, $c_{\text{min}}$, which is determined by the choice of the substrate, and $c_{\text{min}}$-dependent intrinsic properties of the overlayer cannot always be tuned in a continuous way as one may aim to do by means of strained epitaxy. Employing the model of the epitaxial Bain path we predict that such discontinuities occur in films of the elements V, Nb, Ru, La, Os, and Ir. The abrupt change of $c_{\text{min}}$ can be exploited to switch properties specific to the overlayer material. This is demonstrated for the example of the superconducting critical temperature of a V film which we predict to jump by 20% at a discontinuity of $c_{\text{min}}$
Non-Hermitian dynamics of a two-spin system with PT symmetry
Creators: name: Komineas, Stavros
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: A system of interacting spins that are under the influence of spin-polarized currents can be described using a complex functional, or a non-Hermitian (NH) Hamiltonian. We study the dynamics of two exchange-coupled spins on the Bloch sphere. In the case of currents leading to PT symmetry, an exceptional point that survives also in the nonlinear system is identified. The nonlinear system is bistable for small currents and it exhibits stable oscillating motion or it can relax to a fixed point. The oscillating motion of the two spins is akin to synchronized spin-torque oscillators. For the full nonlinear system, we derive two conserved quantities that furnish a geometric description of the spin trajectories in phase space and indicate stability of the oscillating motion. Our analytical results provide tools for the description of the dynamics of NH systems that are defined on the Bloch sphere.
Physical significance of generalized boundary conditions: an Unruh-DeWitt detector viewpoint on $\text{AdS}_2 \times \mathbb{S}^2$
Creators: name: Campos, Lissa de Souza
name: Dappiaggi, Claudio
name: Sinibaldi, Luca
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: On $\text{AdS}_2 \times \mathbb{S}^2$, we construct the two-point correlation functions for the ground and thermal states of a real Klein-Gordon field admitting generalized $(γ,v)$-boundary conditions. We follow the prescription recently outlined in [1] for two different choices of secondary solutions. For each of them, we obtain a family of admissible boundary conditions parametrized by $γ\in\left[0,\fracπ{2}\right]$. We study how they affect the response of a static Unruh-DeWitt detector. The latter not only perceives variations of $γ$, but also distinguishes between the two families of secondary solutions in a qualitatively different, and rather bizarre, fashion. Our results highlight once more the existence of a freedom in choosing boundary conditions at a timelike boundary which is greater than expected and with a notable associated physical significance.
description: 9 pages, 2 figs, 1 table
Udo Kindermann. Kunstdenkmäler zwischen Antwerpen und Trient. Beschreibungen und Bewertungen des Jesuiten Daniel Papebroch aus dem Jahre 1660
Creators: name: Lozar, Angelika
Publisher: name: Forum Classicum
Year: 2017

description: Rezension zu: Udo Kindermann. Kunstdenkmäler zwischen Antwerpen und Trient. Beschreibungen und Bewertungen des Jesuiten Daniel Papebroch aus dem Jahre 1660. Erstedition, Übersetzung, Kommentar, Böhlau Verlag Köln 2002. 527 S. (ISBN 3-412-16701-0).
description: Forum Classicum, Nr. 1 (2003): Forum Classicum
Kürschners Deutscher Gelehrtenkalender 2003. Bio-bibliographisches Verzeichnis deutschsprachiger Wissenschaftler der Gegenwart. 19. Ausgabe
Creators: name: Werner, Jürgen
Publisher: name: Forum Classicum
Year: 2017

description: Rezension zu: Kürschners Deutscher Gelehrtenkalender 2003. Bio-bibliographisches Verzeichnis deutschsprachiger Wissenschaftler der Gegenwart. 19. Ausgabe. 3 Bände. München, K. G. Saur. XIII, 4554 S. (ISBN 3-598-32607-7).
description: Forum Classicum, Nr. 1 (2003): Forum Classicum
Quantum simulations of gauge theories with ultracold atoms: local gauge invariance from angular momentum conservation
Creators: name: Zohar, Erez
name: Cirac, J. Ignacio
name: Reznik, Benni
Publisher: name: arXiv
Year: 2013
Subjects: subject: Quantum Physics (quant-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Quantum simulations of High Energy Physics, and especially of gauge theories, is an emerging and exciting direction in quantum simulations. However, simulations of such theories, compared to simulations of condensed matter physics, must satisfy extra restrictions, such as local gauge and Lorentz invariance. In this paper we discuss these special requirements, and present a new method for quantum simulation of lattice gauge theories using ultracold atoms. This method allows to include local gauge invariance as a fundamental symmetry of the atomic Hamiltonian, arising from natural atomic interactions and conservation laws (and not as a property of a low energy sector). This allows us to implement elementary gauge invariant interactions for three lattice gauge theories: compact QED (U(1)), SU(N) and Z_N, which can be used to build quantum simulators in 1+1 dimensions. We also present a new loop method, which uses the elementary interactions as building blocks in the effective construction of quantum simulations for d+1 dimensional lattice gauge theories (d>1), without having to use Gauss's law as a constraint, as in previous proposals. We discuss in detail the quantum simulation of 2+1 dimensional compact QED and provide a numerical proof of principle. The simplicity of the already gauge invariant elementary interactions of this model suggests it may be useful for future experimental realizations.
description: 28 pages, 16 figures. Third version - references updated
Assessing Meaning
Creators: name: Purpura, James Enos
Publisher: name: Columbia University
Year: 2016
Subjects: Education
Educational tests and measurements
Language and languages--Study and teaching
Language and languages--Study and teaching--Ability testing

description: The quintessential quality of communicative success is the ability to effectively express, understand, dynamically co-construct, negotiate and repair variegated meanings in a wide range of language use contexts. It stands to reason then that meaning and meaning conveyance should play a central role in L2 assessment. Instead, since the 1980s, language testers have focused almost exclusively on functional proficiency (the conveyance of functional meaning – e.g., can-do statements), to the exclusion of the conveyance of propositional meanings or implied pragmatic meanings. While the ability to use language to get things done is important, excluding propositional content from the assessment process is like having language ability with nothing to say, and excluding pragmatic meanings guts the heart and soul out of communication. In this chapter, I review how L2 testers have conceptualized “meaning” in models of L2 proficiency throughout the years. This logically leads to a discus- sion of the use of language to encode a range of meanings, deriving not only from an examinee’s topical knowledge but also from an understanding of the contextual factors in language use situations. Throughout the discussion, I also highlight how the expression and comprehension of meaning have been operationalized in L2 assessments. Finally, I argue that despite the complexities of defining and operatio- nalizing meaning in assessments, testers need to seriously think about what mean- ings they want to test and what meanings they are already assessing implicitly.
title: Ανάπτυξη μεθοδολογίας και συστήματος χρονοπρογραμματισμού ευφυών πρακτόρων με χρήση μεθόδων εμπνευσμένων από την φύση
Creators: name: Περιστερόπουλος Αθανάσιος
Publisher: name: Technical University of Crete
Year: 2012

description: Μη διαθέσιμο
Testing and Being Tested in Pandemic Times
Creators: name: Stark, David C.
Publisher: name: Columbia University
Year: 2020
Subjects: subject: Sociology
subject: FOS: Sociology
subject: Examinations
subject: COVID-19 (Disease)
subject: COVID-19 (Disease)--Social aspects

description: The coronavirus pandemic is witness to a great proliferation of two types of tests. The first type is testing – new medical diagnostic tests as well as epidemiological models that simulate and project the course of the virus. In the second type, actors, organizations, and institutions are being tested in this moment of social and political crisis. This essay analyzes the similarities and differences between these two major types of tests in order to understand their entanglements in the crisis. In the process, we find a great diversity of tests operating in multiple registers, themselves not clearly demarcated, often combining and sometimes conflating, for example, scientific and public discourse. The study opens by identifying three aspects of testing, drawn from the sociology of testing. First, tests are frequently proxies (or projections) that stand for something. Second, a test is a critical moment that stands out – whether because it is a moment deliberately separated out or because it is a puzzling or troublesome “situation” that disrupts the flow of social life. Third, when someone or something is put to the test, of interest is whether it stands up to the challenge. These insights serve as the building blocks for addressing three major issues – representation, selection, and accountability – regarding testing in the time of the coronavirus crisis. In this moment we see a new model of testing: from statistical calculation of risk in a population to algorithmic prediction about the riskiness of particular persons.
Engineering Parallel Algorithms for Community Detection in Massive Networks
Creators: name: Staudt, Christian L.
name: Meyerhenke, Henning
Publisher: name: arXiv
Year: 2013
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences

description: The amount of graph-structured data has recently experienced an enormous growth in many applications. To transform such data into useful information, fast analytics algorithms and software tools are necessary. One common graph analytics kernel is disjoint community detection (or graph clustering). Despite extensive research on heuristic solvers for this task, only few parallel codes exist, although parallelism will be necessary to scale to the data volume of real-world applications. We address the deficit in computing capability by a flexible and extensible community detection framework with shared-memory parallelism. Within this framework we design and implement efficient parallel community detection heuristics: A parallel label propagation scheme; the first large-scale parallelization of the well-known Louvain method, as well as an extension of the method adding refinement; and an ensemble scheme combining the above. In extensive experiments driven by the algorithm engineering paradigm, we identify the most successful parameters and combinations of these algorithms. We also compare our implementations with state-of-the-art competitors. The processing rate of our fastest algorithm often reaches 50M edges/second. We recommend the parallel Louvain method and our variant with refinement as both qualitatively strong and fast. Our methods are suitable for massive data sets with billions of edges.
description: 14 pages, first presented at the 2013 International Conference on Parallel Processing, revised accepted for IEEE Transactions on Parallel and Distributed Systems (TPDS)
Regression with Distance Matrices
Creators: name: Faraway, Julian
Publisher: name: arXiv
Year: 2013
Subjects: subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences

description: Data types that lie in metric spaces but not in vector spaces are difficult to use within the usual regression setting, either as the response and/or a predictor. We represent the information in these variables using distance matrices which requires only the specification of a distance function. A low-dimensional representation of such distance matrices can be obtained using methods such as multidimensional scaling. Once these variables have been represented as scores, an internal model linking the predictors and the response can be developed using standard methods. We call scoring the transformation from a new observation to a score while backscoring is a method to represent a score as an observation in the data space. Both methods are essential for prediction and explanation. We illustrate the methodology for shape data, unregistered curve data and correlation matrices using motion capture data from an experiment to study the motion of children with cleft lip.
description: 18 pages, 7 figures
Digital Twin-Empowered Network Planning for Multi-Tier Computing
Creators: name: Zhou, Conghao
name: Gao, Jie
name: Li, Mushu
name: Xuemin
name: Shen
name: Zhuang, Weihua
Publisher: name: arXiv
Year: 2022
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: In this paper, we design a resource management scheme to support stateful applications, which will be prevalent in 6G networks. Different from stateless applications, stateful applications require context data while executing computing tasks from user terminals (UTs). Using a multi-tier computing paradigm with servers deployed at the core network, gateways, and base stations to support stateful applications, we aim to optimize long-term resource reservation by jointly minimizing the usage of computing, storage, and communication resources and the cost from reconfiguring resource reservation. The coupling among different resources and the impact of UT mobility create challenges in resource management. To address the challenges, we develop digital twin (DT) empowered network planning with two elements, i.e., multi-resource reservation and resource reservation reconfiguration. First, DTs are designed for collecting UT status data, based on which UTs are grouped according to their mobility patterns. Second, an algorithm is proposed to customize resource reservation for different groups to satisfy their different resource demands. Last, a Meta-learning-based approach is developed to reconfigure resource reservation for balancing the network resource usage and the reconfiguration cost. Simulation results demonstrate that the proposed DT-empowered network planning outperforms benchmark frameworks by using less resources and incurring lower reconfiguration costs.
description: accepted by the Journal of Communications and Information Networks
title: Ανάπτυξη συστήματος συστάσεων βασιζόμενου στη μοντελοποίηση του προφίλ των χρηστών με στόχο την προσωποποιημένη αναζήτηση
Creators: name: Αγγελούσης Γεώργιος
Publisher: name: Technical University of Crete
Year: 2012

description: Μη διαθέσιμο
Iterative Angular Differential Imaging (IADI): An exploration of recovering disk structures in scattered light with an iterative ADI approach
Creators: name: Stapper, L. M.
name: Ginski, C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Distinguishing signal of young gas rich circumstellar disks from stellar signal in near infrared light is a difficult task. Current techniques such as Angular Differential Imaging (ADI) and Polarimetric Differential Imaging (PDI) cope with drawbacks such as self-subtraction. To address these drawbacks we explore Iterative Angular Differential Imaging (IADI) techniques to increase signal throughput in total intensity observations. This work aims to explore the effectiveness of IADI to recover the self-subtracted regions of disks by applying ADI techniques iteratively. To determine the effectiveness of IADI a model of a disk image is made and post-processed with IADI. In addition, masking based on polarimetric images and a signal threshold for feeding back signal are explored. Asymmetries are a very important factor in recovering the disk due to less overlap of the disk in the data set. In some cases, a factor 75 more flux could be recovered with IADI compared to ADI. The Procrustes distance is used to quantify the impact of the algorithm on the scattering phase function. Depending on the level of noise and the ratio between the stellar signal and disk signal, the phase function can be recovered a factor 6.4 in Procrustes distance better than standard ADI. The amplification and smearing of noise over the image due to many iterations did occur and by using binary masks and a dynamic threshold this feedback was mitigated, but it still is a problem in the final pipeline. Lastly observations of protoplanetary disks made with VLT/SPHERE were processed with IADI giving rise to very promising results. While IADI has problems with low signal-to-noise observations due to noise amplification and star reconstruction, higher signal-to-noise observations show promising results with respect to standard ADI.
description: Accepted for publication in Astronomy and Astrophysics. 16 pages, 12 figures, plus appendix
Lognormality and oscillations in the coverage of high-throughput transcriptomic data towards gene ends
Creators: name: Innocenti, Nicolas
name: Aurell, Erik
Publisher: name: arXiv
Year: 2013
Subjects: subject: Genomics (q-bio.GN)
subject: FOS: Biological sciences

description: High-throughput transcriptomics experiments have reached the stage where the count of the number of reads alignable to a given position can be treated as an almost-continuous signal. This allows to ask questions of biophysical/biotechnical nature, but which may still have biological implications. Here we show that when sequencing RNA fragments from one end, as it is the case on most platforms, an oscillation in the read count is observed at the other end. We further show that these oscillations can be well described by Kolmogorov's 1941 broken stick model. We investigate how the model can be used to improve predictions of gene ends (3' transcript ends) but conclude that with present data the improvement is only marginal. The results highlight subtle effects in high-throughput transcriptomics experiments which do not have a biological origin, but which may still be used to obtain biological information.
title: Μελέτη της μικροστρωματικής δομής κονιαμάτων τοιχογραφιών μέσω ψηφιακής επεξεργασίας εικόνας
Creators: name: Δούκας Νικόλαος
Publisher: name: Technical University of Crete
Year: 2012

description: Μη διαθέσιμο
Nuclear high-ionisation outflow in the Compton-thick AGN NGC6552 as seen by the JWST mid-infrared instrument
Creators: name: Álvarez-Márquez, J.
name: Labiano, A.
name: Guillard, P.
name: Dicken, D.
name: Argyriou, I.
name: Patapis, P.
name: Law, D. R.
name: Kavanagh, P. J.
name: Larson, K. L.
name: Gasman, D.
name: Mueller, M.
name: Alberts, A.
name: Brandl, B. R.
name: Colina, L.
name: García-Marín, M.
name: Jones, O. C.
name: Noriega-Crespo, A.
name: Shivaei, I.
name: Temim, T.
name: Wright, G. S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: During the commissioning of the James Webb Space Telescope (JWST), the mid-infrared instrument (MIRI) observed NGC6552 with the MIRI Imager and the medium-resolution spectrograph (MRS). NGC6552 is an active galactic nucleus (AGN) at redshift 0.0266 classified as a Seyfert 2 nucleus in the optical, and Compton-thick AGN in X-rays. This work exemplifies and demonstrates the MRS capabilities to study the mid-infrared (mid-IR) spectra and characterize the physical conditions and kinematics of the ionized and molecular gas in the nuclear regions of nearby galaxies. We obtained the nuclear, circumnuclear, and central mid-IR spectra of NGC6552. They provide the first clear observational evidence for a nuclear outflow in NGC6552. The outflow contributes to 67$\pm$7% of the total line flux independent of the ionization potential (27 to 187 eV) and critical densities (10$^4$ to 4$\times$10$^{6}$ cm$^{-3}$), showing an average blue-shifted peak velocity of -127$\pm$45 kms$^{-1}$ and an outflow maximal velocity of 698$\pm$80 kms$^{-1}$. Since the mid-IR photons penetrate dusty regions as efficiently as X-ray keV photons, we interpret these results as the evidence for a highly ionized, non-stratified, AGN-powered, and fast outflowing gas in a low density environment (few 10$^{3}$ cm$^{-3}$) located very close (<0.2kpc) to the Compton-thick AGN. Nine pure rotational molecular Hydrogen lines are detected and spectrally resolved, and exhibit symmetric Gaussian profiles, consistent with the galactic rotation, and with no evidence of outflowing H$_{2}$ material. We detect a warm H$_{2}$ mass of $1.9\pm1.1\times10^7 M_{\odot}$ in the central region (1.8 kpc in diameter) of the galaxy, with almost 30% of that mass in the circum-nuclear region. Line ratios confirm that NGC6552 has a Seyfert nucleus with a black hole mass estimated in the range of 0.6 to 6 million solar masses.
description: 13 pages, 5 figures, 5 tables, accepted in A&A
title: Αριθμητική επίλυση των υδροδυναμικών εξισώσεων ροής ελεύθερης επιφάνειας σε μη δομημένα υπολογιστικά πλέγματα
Creators: name: Ανεζάκης Γεώργιος Μ.
Publisher: name: Technical University of Crete
Year: 2009

description:  Εισαγωγή -- 2. Μαθηματικό μοντέλο -- 3. Αριθμητικό σχήμα -- 4. Κατασκευή υπολογιστικού πλέγματος
title: Μελέτη ηλεκτροθετικών ενισχυτών στην καταλυτική αποδοτικότητα του Ir κατά την αναγωγή των οξειδίων του αζώτου
Creators: name: Κατζουράκης Παύλος
Publisher: name: Technical University of Crete
Year: 2009

description: Μη διαθέσιμο
Photon propagation in a material medium on a curved spacetime
Creators: name: Guerrieri, Amanda
name: Novello, Mario
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We consider a nonlinear dielectric medium surrounding a static, charged and spherically symmetric compact body which gravitational field is driven by General Relativity (GR). Considering the propagating waves on the dielectric medium, we describe the trajectory of light as geodesics on an effective geometry given by Hadamard's discontinuities. We analyze some consequences of the effective geometry in the propagation of light, with relation to the predictions of the background gravitational field, that includes corrections on the geometrical redshift and on the gravitational deflection of light. We show that the background electromagnetic field polarize the material medium, such that different polarizations of light are distinguished by different corrections on these quantities. As a consequence, we have two possible paths for the trajectory of light in such configuration, that coincide if we turn off the electromagnetic field or if the permittivity is constant. We show that the effective metric associated to the negative polarization, for a given dependence of the dielectric permittivity, is conformally flat.
description: 21 pages, 1 figure
Half-Quantized Hall Effect at the Parity-Invariant Fermi Surface
Creators: name: Zou, Jin-Yu
name: Chen, Rui
name: Fu, Bo
name: Wang, Huan-Wen
name: Hu, Zi-Ang
name: Shen, Shun-Qing
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Condensed matter realization of a single Dirac cone of fermions in two dimensions is a long-standing issue. Here we report the discovery of a single gapless Dirac cone of half-quantized Hall conductance in a magnetically-doped topological insulator heterostructure. It demonstrates that the Hall conductance is half-quantized in the unit e^{2}/h when the parity symmetry is invariant near the Fermi surface. The gapless Dirac point is stable and protected by the local parity symmetry and the topologically nontrivial band structure of the topological insulator. The one-half Hall conductance observed in a recent experiment [Mogi et al, Nat. Phys. 18, 390 (2022)] is attributed to the existence of the gapless Dirac cone. The results suggest a condensed matter realization of a topological phase with a one-half topological invariant.
description: 6 pages with 4 figures
The 125 GeV boson: A composite scalar?
Creators: name: Doff, Adriano
name: Luna, Emerson G. S.
name: Natale, Adriano A.
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Assuming that the 125 GeV particle observed at the LHC is a composite scalar and responsible for the electroweak gauge symmetry breaking, we consider the possibility that the bound state is generated by a non-Abelian gauge theory with dynamically generated gauge boson masses and a specific chiral symmetry breaking dynamics motivated by confinement. The scalar mass is computed with the use of the Bethe-Salpeter equation and its normalization condition as a function of the SU(N) group and the respective fermionic representation. If the fermions that form the composite state are in the fundamental representation of the SU(N) group, we can generate such light boson only for one specific number of fermions for each group. In the case of small groups, like SU(2) to SU(5), and two fermions in the adjoint representation we find that is quite improbable to generate such light composite scalar.
description: 24 pages, 5 figures, discussion extended, references added; version to appear in Phys. Rev. D
Revising the Hubble constant, spatial curvature and dark energy dynamics with the latest observations of quasars
Creators: name: Liu, Tonghua
name: Cao, Shuo
name: Li, Xiaolei
name: Zheng, Hao
name: Liu, Yuting
name: Guo, Wuzheng
name: Zheng, Chenfa
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: In this paper, we use a newly compiled sample of ultra-compact structure in radio quasars and strong gravitational lensing systems with quasars acting as background sources to constrain six spatially flat and non-flat cosmological models ($Λ$CDM, PEDE and DGP). These two sets of quasar data (the time-delay measurements of six strong lensing systems and 120 intermediate-luminosity quasars calibrated as standard rulers) could break the degeneracy between cosmological parameters ($H_0$, $Ω_m$ and $Ω_k$) and therefore provide more stringent cosmological constraints for the six cosmological models we study. A joint analysis of the quasar sample provides model-independent estimations of the Hubble constant $H_0$, which is strongly consistent with that derived from the local distance ladder by SH0ES collaboration in the $Λ$CDM and PEDE model. However, in the framework of a DGP cosmology (especially for the flat universe), the measured Hubble constant is in good agreement with that derived from the the recent Planck 2018 results. In addition, our results show that zero spatial curvature is supported by the current lensed and unlensed quasar observations and there is no significant deviation from a flat universe. For most of cosmological model we study (the flat $Λ$CDM, non-flat $Λ$CDM, flat PEDE, and non-flat PEDE models), the derived matter density parameter is completely consistent with $Ω_m\sim 0.30$ in all the data sets, as expected by the latest cosmological observations. Finally, according to the the statistical criteria DIC, although the joint constraints provide substantial observational support to the flat PEDE model, they do not rule out dark energy being a cosmological constant and non-flat spatial hypersurfaces.
description: 11 pages, 5 figures, accepted for publication in A&A
The Study of Cable Behavior with Two Spring-Dampers and One Viscous Damper
Creators: name: Shakouri Mahmoudabadi, Nasim
Publisher: name: figshare
Year: 2023
Subjects: Civil geotechnical engineering
Civil engineering not elsewhere classified
Structural engineering

description: The objective of this research was to investigate the behavior of cables with two springs-damper and one viscous damper. To this end, a major mode is adopted to control the vibration of the cable. In this mode, two damping springs are connected to both ends of the cable. The purpose is to reduce the vibrations of the cable by placing a third damper. In this case, employing spectral power density diagrams, the impact of the third damper on declining the vibration of the cable in the first three modes was presented for various values of damping coefficient for all three dampers and different damping installation places
Learning from 27F: A Comparative Assessment Of Urban Reconstruction Processes After The 2010 Eathquake In Chile
Creators: name: Irazabal Zurita, Clara E.
name: Marchant, Mario
name: Bresciani, Luis Eduardo
name: Cuadros, Genaro
name: De Castro Mazarro, Alejandro
name: Diaz, Francisco
name: Fustes, Xenia
name: Ihle, Carolina
name: Imilan, Walter
name: Letelier, Francisco
name: Moris, Roberto
name: Orta, Paula
name: Pino, Francisco
name: Razmilic, Rayna
name: Salinas, Tamara
name: Serra, Isabel
name: Silva, Ernesto
name: Stutzin, Nicolas
name: Walker, Rosario
name: Gonzalez, Luis Eduardo
name: Larenas, Jorge
Publisher: name: Columbia University
Year: 2015
Subjects: Emergency management--Evaluation
Disaster relief--Evaluation
Earthquakes--Planning
Chile Earthquake (Chile : 2010 February 27)

description: The earthquake followed by a tsunami that hit Chile in February 2010 not only left a wave of destruction and a number of deaths of over 500 people, too started a number of relief and recovery initiatives led by different institutions, from the government to universities, private companies to NGOs. However, the roles of these actors, their interactions and the effects of these on post-disaster reconstruction have not been to date actually evaluated. There is still not enough information to judge whether all those well-intentioned efforts were or were not the best way to mobilize resources for help and recovery. The purpose of this report is precisely to collect and analyze projects, programs and policies related to the reconstruction and redevelopment in the cities of Curicó, Talca, Constitución, Pelluhue and Dichato in order to develop an independent and comprehensive assessment of the reactions for disaster relief and reconstruction in 2010.
Social network modeling and applications, a tutorial
Creators: name: Espín-Noboa, Lisette
name: Peixoto, Tiago
name: Karimi, Fariba
Publisher: name: arXiv
Year: 2023
Subjects: subject: Social and Information Networks (cs.SI)
subject: Discrete Mathematics (cs.DM)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Social networks have been widely studied over the last century from multiple disciplines to understand societal issues such as inequality in employment rates, managerial performance, and epidemic spread. Today, these and many more issues can be studied at global scale thanks to the digital footprints that we generate when browsing the Web or using social media platforms. Unfortunately, scientists often struggle to access to such data primarily because it is proprietary, and even when it is shared with privacy guarantees, such data is either no representative or too big. In this tutorial, we will discuss recent advances and future directions in network modeling. In particular, we focus on how to exploit synthetic networks to study real-world problems such as data privacy, spreading dynamics, algorithmic bias, and ranking inequalities. We start by reviewing different types of generative models for social networks including node-attributed and scale-free networks. Then, we showcase how to perform a network selection analysis to characterize the mechanisms of edge formation of any given real-world network.
description: Presented at The ACM Web Conference 2023
title: Μελέτη ενίσχυση κτιρίου φέρουσας τοιχοποιίας με πλαισιακό φορέα οπλισμένου σκυροδέματος, υπό συνθήκες δυναμικής φόρτισης
Creators: name: Πατεράκη Αικατερίνη Μ.
Publisher: name: Technical University of Crete
Year: 2009

description:  Εισαγωγή -- 2. Δυναμική συμπεριφορά κατασκευών από φέρουσα τοιχοποιία και οπλισμένο σκυρόδεμα -- 3. Αναφορές στην αλληλεπίδραση γειτονικών κατασκευών από διαφορετικά υλικά -- 4. Προσομοίωση με τη μέθοδο των πεπερασμένων στοιχείων -- 5. Ενίσχυση κτιρίου από φέρουσα τοιχοποιία με φορέα οπλισμένου σκυροδέματος
title: Η αναπηρία στη σύγχρονη κοινωνία
Creators: name: Καλογιάννη Αντωνία
Publisher: name: Technical University of Crete
Year: 2009

description: φ. 1: Αναπηρία και προσωπικότητα. Τα αρνητικά στερεότυπα και οι πραγματικοί συσχετισμοί -- Κεφ. 2: Σύγχρονη υποστηρικτική τεχνολογία και καπιταλιστικό σύστημα παραγωγής. Οι εντυπωσιακές δυνατότητες και οι περιορισμοί -- Κεφ. 3: Εκπαίδευση και άτομα με αναπηρία. Οι αδυναμίες της ειδικής αγωγήςκαι η ανάγκη για την εφαρμογή μιας κοινωνικής παιδαγωγικής
title: Κέντρο μελέτης της ελιάς στη Μαλεσίνα Φθιώτιδας
Creators: name: Ασημακη Ευσταθια
Publisher: name: Technical University of Crete
Year: 2014

description: Η παρούσα διπλωματική εργασία «Κέντρο μελέτης της ελιάς» μελετά επέμβαση στην περιοχή της Μαλεσίνας Φθιώτιδας διαμέσου δημιουργίας εκπαιδευτικού κέντρου για την ελιά και το ελαιόλαδο. Η περιοχή μελέτης επικεντρώνεται βορειοανατολικά του οικισμού,  πλησίον της Ιεράς Μονής του Αγίου Γεωργίου, δημιουργώντας ένα νέο πόλο έλξης για τους κατοίκους και για τον επισκέπτη, διατηρώντας τις ήδη υπάρχουσες εγκαταστάσεις (αθλητικές, κατασκήνωση, παλιο και νέο μοναστήρι του Αγίου Γεωργίου και ελαιοτριβείο). Πηγή έμπνευσης αποτελεί ο μεγάλος αριθμός ελαιώνων και η στενή σχέση της περιοχής με την ελιά. Μέσω της επέμβασης επιθυμούμε τη δημιουργία ενός εκπαιδευτικού κέντρου για αγρότες και μη, όπου σκοπό θα έχει την ενδελεχή εκπαίδευσή τους αλλά και ένα χώρο αναψυχής και προσέλκυσης των κατοίκων, ως ένα ζωντανό κύτταρο της κωμόπολης.
         Η πρόταση εστιάζει στο κέντρο μελέτης το οποίο αποτελείται από το εκπαιδευτικό κέντρο που περιλαμβάνει αίθουσες εκπαίδευσης, εργαστήρια, πρότυπο ελαιοτριβείο, αποθήκες και ελαιώνα. Παράλληλα με το εκπαιδευτικό κέντρο θα λειτουργεί η βιβλιοθήκη,  το εργαστήριο γευσιγνωσίας, το εμπορικό κατάστημα πώλησης προϊόντων και το εστιατόριο. Ακόμη, στο χώρο του κέντρου μελέτης υπάρχει το αμφιθέατρο χωρητικότητας 350 ατόμων και η αίθουσα πολλαπλών χρήσεων. Οι χώροι αυτοί θα μπορούν να χρησιμοποιούνται τόσο από το κέντρο μελέτης όσο και από το μοναστήρι και τους κατοίκους. Συμπληρωματικά στο κέντρο μελέτης διαμορφώσαμε δρόμους και πεζοδρόμους από τη Μαλεσίνα μέχρι την περιοχή  και τη δημιουργία  υπαίθριων πλατειών.
        Τέλος, διατηρώντας το πευκόδασος όπου υπάρχει και σε συνδιασμό με τους ελαιώνες και τα διάφορα είδη καλλωπιστικών και αρωματικών φυτών δημιουργούμε ένα πάρκο εναρμονισμένο με το κέντρο μελέτης και την περιοχή.