cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Synthetic CO emission and the $X_{\rm CO}$ factor of young molecular clouds: a convergence study
Creators: name: Borchert, Elisabeth M. A.
name: Walch, Stefanie
name: Seifried, Daniel
name: Clarke, Seamus D.
name: Franeck, Annika
name: Nürnberger, Pierre
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The properties of synthetic CO emission from 3D simulations of forming molecular clouds are studied within the SILCC-Zoom project. Since the time scales of cloud evolution and molecule formation are comparable, the simulations include a live chemical network. Two sets of simulations with an increasing spatial resolution (d$x=3.9$ pc to d$x=0.06$ pc) are used to investigate the convergence of the synthetic CO emission, which is computed by post-processing the simulation data with the RADMC-3D radiative transfer code. To determine the excitation conditions, it is necessary to include atomic hydrogen and helium alongside H$_2$, which increases the resulting CO emission by ~7-26 per cent. Combining the brightness temperature of $^{12}$CO and $^{13}$CO, we compare different methods to estimate the excitation temperature, the optical depth of the CO line and hence, the CO column density. An intensity-weighted average excitation temperature results in the most accurate estimate of the total CO mass. When the pixel-based excitation temperature is used to calculate the CO mass, it is over-/underestimated at low/high CO column densities where the assumption that $^{12}$CO is optically thick while $^{13}$CO is optically thin is not valid. Further, in order to obtain a converged total CO luminosity and hence factor, the 3D simulation must have d$x\lesssim0.1$ pc. The evolves over time and differs for the two clouds; yet pronounced differences with numerical resolution are found. Since high column density regions with a visual extinction larger than 3~mag are not resolved for d$x\gtrsim 1$~pc, in this case the H$_2$ mass and CO luminosity both differ significantly from the higher resolution results and the local $X_{\rm CO}$ is subject to strong noise. Our calculations suggest that synthetic CO emission maps are only converged for simulations with d$x\lesssim 0.1$ pc.
description: 23 pages, 22 figures, accepted for publication in MNRAS
Characterization of a novel bacterial transducer based on genetically engineered bioluminescence
Creators: name: Blouin, Kim
Publisher: name: University of British Columbia
Year: 2009

description: The research described in this thesis is aimed at helping with the development of better sensors for instrumentation involved in the monitoring of otherwise difficult-todetect chemical compounds and their toxic effects. The proposed transducer is based on genetically engineered bioluminescence in the biofilm-forming bacterium Caulobacter crescentus. We studied the biochemical mechanisms involved in the bioluminescence process which revealed a complex multi-phase kinetic behaviour. The bioluminescence profiles were characterized in terms of relevant protocol-related parameters such as substrate concentration, environment, order of mixing, etc. A coupled-enzyme model of the bioluminescence mechanism is proposed in order to explain and interpret the complex profiles. The interpretation is supported by an in vitro analysis isolating the two enzymes directly involved in in vivo bioluminescence. This study demonstrates the importance of precise control of protocol-related parameters required to obtain reproducible and meaningful results. A rudimentary toxicity protocol was developed based on the knowledge gained during the characterization studies. The results obtained were comparable to previously published data and hence demonstrated the considerable potential of the bacterial transducer for use as a toxicity sensor. The data generated also supported the validity of the model proposed during the characterization of the bioluminescence mechanism. The bacterial transducer was thus found to be appropriate for future application in a flow-through toxicity assessing instrumentation system. The first stage of this next phase of the project was accomplished by designing and building a prototype of a flow-through system. Some preliminary flow-through data were generated which demonstrated that the prototype (and the flow-through concept) are indeed advantageous and worthy of further development. Some suggestions for specific directions for such further development are outlined and discussed, as well as some other applications for the flow-through instrumentation system.
First Principles Theories of Piezoelectric Materials
Creators: name: Cohen, R. E.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Piezoelectrics have long been studied using parameterized models fit to experimental data, starting with the work of Devonshire in 1954. Much has been learned using such approaches, but they can also miss major phenomena if the materials properties are not well under-stood, as is exemplified by the realization that low-symmetry monoclinic phases are common around morphotropic phase boundaries, which was missed completed by low-order Devonshire models, and can only appear in higher order models. In the last 15 years, a new approach has developed using first-principles computations, based on fundamental physics, with no essential experimental input other than the desired chemistry (nuclear charges). First-principles theory laid the framework for a basic understanding of the origins of ferroelectric behavior and piezoelectric properties. The range of properties accessible to theory continues to expand as does the accuracy of the predictions. We are moving towards the ability to design materials of desired properties computationally. Here some of the fundamental developments of our understanding of piezoelectric material behavior and ability to predict a wide range of properties using theoretical methods are reviewed.
General parametrization of wormhole spacetimes and its application to shadows and quasinormal modes
Creators: name: Bronnikov, Kirill A.
name: Konoplya, Roman A.
name: Pappas, Thomas D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The general parametrization for spacetimes of spherically symmetric Lorentzian, traversable wormholes in an arbitrary metric theory of gravity is presented. The parametrization is similar in spirit to the post-Newtonian parametrized formalism, but with validity that extends beyond the weak field region and covers the whole space. Our method is based on a continued-fraction expansion in terms of a compactified radial coordinate. Calculations of shadows and quasinormal modes for various examples of parametrization of known wormhole metrics that we have performed show that, for most cases, the parametrization provides excellent accuracy already at the first order. Therefore, only a few parameters are dominant and important for finding potentially observable quantities in a wormhole background. We have also extended the analysis to the regime of slow rotation.
description: 31 pages, 4 figures, 12 Tables, version to match the one published in Phys. Rev. D
On the nature of VX Sagitarii: Is it the first galactic super-AGB star found?
Creators: name: Tabernero, Hugo
name: Dorda, Ricardo
name: Negueruela, Ignacio
name: Marfil, Emilio
Publisher: name: Zenodo
Year: 2021
Subjects: Post main sequence cool stars
AGB stars
red supergiants
super-AGB stars

description: Stars with initial masses above ~10 M⊙ have an internal evolution completely different from those in the range between 4 and ~10 M⊙. The former are able to ignite all the elements up to Fe in their cores without degeneration (becoming into red supergiants; RSGs). The latter are not, and they become into red giants first, and later into asymptotic branch giant (AGB) stars. Despite their internal differences, externally, both AGB stars and RSGs are evolved cool stars with similarly cool. The main difference between both groups is their luminosity, as typical RSGs have bolometric magnitudes in the range -9<Mbol< -7.8 mag and most luminous confirmed AGB stars have Mbol ~ -8 mag. However, according to theoretical predictions, AGB stars with masses above ~8 M⊙ (which can be even higher than ~10 M⊙ under the right conditions) can reach extremely high luminosities. In this context, we studied one of the most luminous (Mbol ~ -8.6 mag) galactic RSGs, VX Sgr, and we found clear proofs that it is not a RSGs. We examined the alternatives, and we found that its characteristic fit better with a AGB with unprecedentedly high mass (in the range between 10 and ~12 M⊙), making it a strong candidate (and the first identified in the Galaxy) to be a super-AGB star (an AGB star which has ignited its Carbon core). These findings are not only important for the understanding of the most massive AGB stars, because we provided one observational case, but also for the study of the most extreme RSGs, because one of them is in fact an AGB star, showing that there may be other high-mass AGB stars concealed among RSGs.
Modeling semi-conductor thermal properties. The dispersion role
Creators: name: Terris, Damian
name: Joulain, Karl
name: Lacroix, David
name: Lemonnier, Denis
Publisher: name: arXiv
Year: 2008
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: We study heat transport in semiconductor nanostructures by solving the Boltzmann Transport Equation (BTE) by means of the Discrete Ordinate Method (DOM). Relaxation time and phase and group velocitiy spectral dependencies are taken into account. The Holland model of phonon relaxation time is revisited and recalculated from dispersion relations (taken in litterature) in order to match bulk silicon and germanium values. This improved model is then used to predict silicon nanowire and nanofilm thermal properties in both ballistic and mesoscopic regimes.
TFAW K2 survey: an insight into a few hundreds of new Earth-sized planetary candidates
Creators: name: del Alcázar, M.
name: del Ser, D.
name: Fors, O.
Publisher: name: Zenodo
Year: 2021
Subjects: Cool Stars on the main sequence
Stars with Planets

description: Kepler's extended mission (K2) Earth-sized planetary legacy is a niche that still remains to be fully exploited. We reanalyzed all light curves in K2 C1-C8, C12-C18 campaigns with a wavelet-based detrending method \texttt{TFAW} developed by our team,
 and the period search algorithm \texttt{TLS}. The combination of these two methods allows to detect and characterize planetary transit candidates around fainter targets ($12.5 < K_{\rm p} < 18.5$) than any previous study.
 We present 220 new planetary candidates as a result of a preliminary survey. All of them have passed a vetting procedure including: candidate periods with SDE$_{\rm TLS}>$9.0, visual inspection of the candidate light curve, inspection of archival Pan-STARRS1 images and Gaia DR2 to discard close stellar companions and statistical FPP$<$2$\%$.
 We assigned our candidates sample three levels of priority: six top-priority detected in two or more separate but overlapping K2 campaigns, 110 high-priority meeting the above requirements, and 104 low-priority still meeting the same requirements, but having either FPP close to 2$\%$ or pending further reanalysis.
 The bulk of our \texttt{TFAW} K2 survey are small planet candidates with $R_{p}<2 R_{\oplus}$, most of them orbiting faint low-mass stars. Our survey adds new candidates to different areas of interest in exoplanetary science: several dozens in the small planet radius gap, four in the Hot-Super-Earths desert, and a few in the Ultra-Short-Period planets. We also present six candidates within the Habitable Zones of their host stars.
Disorder-robust high-field superconducting phase of FeSe single crystals
Creators: name: Zhou, Nan
name: Sun, Yue
name: Xi, C. Y.
name: Wang, Z. S.
name: Zhang, J. L.
name: Zhang, Y.
name: Zhang, Y. F.
name: Xu, C. Q.
name: Pan, Y. Q.
name: Feng, J. J.
name: Meng, Y.
name: Yi, X. L.
name: Pi, L.
name: Tamegai, T.
name: Xing, Xiangzhuo
name: Shi, Zhixiang
Publisher: name: arXiv
Year: 2021
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: When exposed to high magnetic fields, certain materials manifest an exotic superconducting (SC) phase that has attracted considerable attention. A proposed explanation for the origin of the high-field SC phase is the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. This state is characterized by inhomogeneous superconductivity, where the Cooper pairs have finite center-of-mass momenta. Recently, the high-field SC phase was observed in FeSe, and it was deemed to originate from the FFLO state. Here, we synthesize FeSe single crystals with different levels of disorder. The level of disorder is expressed by the ratio of the mean free path to the coherence length and ranges between 35 and 1.2. The upper critical field \textit{B}$_{\rm{c}2}$ was obtained by both resistivity and magnetic torque measurements over a wide range of temperatures, which went as low as $\sim$0.5 K, and magnetic fields, which went up to $\sim$38 T along the \textit{c} axis and in the \textit{ab} plane. In the high-field region parallel to the \textit{ab} plane, an unusual SC phase was confirmed in all the crystals, and the phase was found to be robust against disorder. This result suggests that the high-field SC phase in FeSe is not a conventional FFLO state.
description: 11 pages, 11 figures
Excitation gap of a graphene channel with superconducting boundaries
Creators: name: Titov, M.
name: Ossipov, A.
name: Beenakker, C. W. J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We calculate the density of states of electron-hole excitations in a superconductor/normal-metal/superconductor (SNS) junction in graphene, in the long-junction regime that the superconducting gap is much larger than the Thouless energy. If the normal region is undoped, the excitation spectrum consists of neutral modes that propagate along the boundaries - transporting energy but no charge. These ``Andreev modes'' are a coherent superposition of electron states from the conduction band and hole states from the valence band, coupled by specular Andreev reflection at the superconductor. The lowest Andreev mode has an excitation gap, which depends on the superconducting phase difference across the SNS graphene channel. At high doping the excitation gap vanishes and the usual gapless density of states of Andreev levels is recovered. We use our results to calculate the superconducting phase dependence of the thermal conductance of the graphene channel.
description: 8 pages, 10 figures
Automated protein structure refinement using i3Drefine software and its assessment in CASP10
Creators: name: Debswapna Bhattacharya
name: Jianlin, Cheng
Publisher: name: F1000Research
Year: 2015

description: We present fully automated and computationally efficient protein 3D structure refinement software called i3Drefine, based on an iterative and highly convergent energy minimization algorithm with a powerful all-atom composite physics and knowledge-based force fields and hydrogen bonding (HB) network optimization technique. In the recent community-wide blind experiment, CASP10, i3Drefine (as “MULTICOM-CONSTRUCT”) was ranked as the best method in the server section as per the official assessment of CASP10 experiment. Our analysis demonstrates that i3Drefine is only fully- automated server participating in CASP10 exhibiting consistent improvement over the initial structures in both global and local structural quality metrics. i3Drefine software is freely available at: http://protein.rnet.missouri.edu/i3drefine/.
REFINEpro: A novel conformation ensemble approach to protein structure refinement
Creators: name: Debswapna Bhattacharya
name: Jianlin Cheng
Publisher: name: F1000Research
Year: 2015

description: Improving the overall fold of the initial models is one of the major challenges in protein structure refinement field. Here, we propose a novel conformation ensemble approach, called REFINEpro to tackle this problem. The protocol first identifies the less conserved local regions in the initial structure by consensus approach using ensemble of models produced for the same protein target. We call these regions problematic regions (PRs). Combined with our previous study on protein structure refinement, the qualities of the PRs are then iteratively improved by assembling better-modeled fragments corresponding to these PRs from structures in the ensemble. REFINEpro web service is freely available at: http://sysbio.rnet.missouri.edu/REFINEpro/.
Approximations in transmon simulation
Creators: name: Jones, Tyler
name: Steven, Kaiah
name: Poncini, Xavier
name: Rose, Matthew
name: Fedorov, Arkady
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Classical simulations of time-dependent quantum systems are widely used in quantum control research. In particular, these simulations are commonly used to host iterative optimal control algorithms. This is convenient for algorithms that are too onerous to run in the loop with current-day quantum hardware, as well as for researchers without consistent access to hardware. However, if the model used to represent the system is not selected carefully, an optimised control protocol may be rendered futile when applied to hardware. We present a series of models, ordered in a hierarchy of progressive approximation, which appear in quantum control literature. The validity of each model is characterised experimentally by designing and benchmarking control protocols for an IBMQ cloud quantum device. This result demonstrates error amplification induced by the application of a first-order perturbative approximation. Furthermore, the emergence of errors that cannot be corrected by simple amplitude scaling of control pulses is demonstrated in simulation, due to an underlying mistreatment of noncomputational dynamics. Finally, an evaluation of simulated control dynamics reveals that despite the substantial variance in numerical predictions across the proposed models, the complexity of discovering local optimal control protocols appears invariant in the simple control scheme setting.
description: v1: 13 pages, 9 figures. v2: 16 pages, 11 figures. As published in Phys. Rev. Applied. Major update: mistreatment of noncomputational dynamics by Rabi models results in emergence of errors that cannot be corrected by simple calibration techniques
Entanglement generation in atoms immersed in a thermal bath of external quantum scalar fields with a boundary
Creators: name: Zhang, Jialin
name: Yu, Hongwei
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We examine the entanglement creation between two mutually independent two-level atoms immersed in a thermal bath of quantum scalar fields in the presence of a perfectly reflecting plane boundary. With the help of the master equation that describes the evolution in time of the atom subsystem obtained, in the weak-coupling limit, by tracing over environment (scalar fields) degrees of freedom, we find that the presence of the boundary may play a significant role in the entanglement creation in some circumstances and the new parameter, the distance of the atoms from the boundary, besides the bath temperature and the separation between the atoms, gives us more freedom in manipulating entanglement generation. Remarkably, the final remaining entanglement in the equilibrium state is independent of the presence of the boundary.
description: 19 pages, 4 figures, to be published in PRA
Long-term correlations in solar proxies and solar wind parameters
Creators: name: Reda, Raffaele
name: Alberti, Tommaso
name: Berrilli, Francesco
name: Giobbi, Piermarco
name: Giovannelli, Luca
name: Penza, Valentina
Publisher: name: Zenodo
Year: 2021
Subjects: The Sun and the Heliosphere

description: Solar variability related to its magnetic activity can be quantified by using synthetic indices (e.g. sunspots number) or physical ones (e.g. chromospheric proxies). In order to connect the long-term solar activity variations to solar wind properties, we use Ca II K index and solar wind OMNI data in the time interval between 1965 and 2019, which almost entirely cover the last 5 solar cycles. A time lag in the correlation between the parameters is found. This time shift seems to show a temporal evolution over the different solar cycles. The advantage to use a chromospheric proxy opens the possibility to extend the relation found for the Sun to link stellar variability and stellar wind properties in Sun-like stars.
Η εξωστρέφεια της ελληνικής βιομηχανίας πριν και μετά την κρίση.:
Creators: name: ΠΙστικός, Κωνσταντίνος Παντελή
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Εξωστρέφεια
Οικονομική κρίση
Ελληνική βιομηχανία
Extraversion
Economic crisis
Greek industry

description: Σκοπός της παρούσας εργασίας είναι η εξέταση της τάσης των εξαγωγών πριν και μετά την εκδήλωση της κρίσης για την ελληνική βιομηχανία. Πραγματοποιείται έρευνα για το πώς επηρεάστηκαν οι εξαγωγές της ελληνικής βιομηχανίας μετά την εμφάνιση της οικονομικής κρίσης του 2007. Διερευνώνται, επίσης, ποιοι είναι οι προσδιοριστικοί παράγοντες των εξαγωγών τόσο κατά τη διάρκεια μιας κρίσης όσο και σε περιόδους που δεν υφίσταται κάποιο αρνητικό εξωτερικό σοκ στην οικονομία μιας χώρας. Ακόμη, γίνεται οικονομετρική εξέταση για το ποιες μεταβλητές και σε τι βαθμό σημαντικότητας επηρεάζουν την εξωστρέφεια μιας επιχείρησης και κατ’ επέκταση μιας οικονομίας στο σύνολό της. Για την καλύτερη κατανόηση του ερευνητικού σκοπού της εργασίας διενεργείται έρευνα σε δύο επιχειρήσεις της ελληνικής βιομηχανίας από δύο διαφορετικούς κλάδους. Μετά τη εξέταση και των δύο επιχειρήσεων, καταλήγουμε στο συμπέρασμα ότι οι δύο εταιρείες μετά την εμφάνιση της κρίσης δέχθηκαν τις αρνητικές επιπτώσεις σε όλα τα οικονομικά μεγέθη της λειτουργίας τους και προκειμένου να αντιμετωπίσουν την χαμηλή εγχώρια ζήτηση, που προκλήθηκε από την ύφεση, έδωσαν ιδιαίτερο βάρος στην εξαγωγική τους δραστηριότητα και την ενέτειναν με στόχο να καλύψουν τις ζημιές που σημείωναν από το 2009 και έπειτα.
description: The purpose of this paper is to examine the trend of exports during an economic crisis for the Greek industry. It is investigated how exports of Greek industry affected after the onset of the financial crisis of 2007. It is, also, investigated the determinants of exports doth during a crisis and in case that there isn’t a negative external shock to the economy of a country. Moreover, becomes econometric examination about which variables affect the openness of a company and how important they are for an economy as a whole. For a better comprehension of the searching purpose of the work, it is carried out research in two companies of Greek industry from two different sectors. After examination of both companies, we conclude that the two companies gave emphasis and intensified their export activity in order to offset losses from 2009 onwards, which caused by the recession. All these happened in order to cope with weak domestic demand. After the presentation of the factors affecting the extroversion of Greek industry during a recession, a number of policy responses to openness, to help mitigate the negative effects of the crisis.
Discovery of a Transient X-ray Source in the Compact Stellar Nucleus of NGC 2403
Creators: name: Yukita, Mihoko
name: Swartz, Douglas A.
name: Soria, Roberto
name: Tennant, Allyn F.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report the discovery of an X-ray source coincident with the nuclear star cluster at the dynamical center of the nearby late-type spiral galaxy NGC 2403. The X-ray luminosity of this source varies from below detection levels, ~1e35 erg/s in the 0.5-8.0 keV band, to 7e38 erg/s on timescales between observations of less than 2 months. The X-ray spectrum is well-fit by an accretion disk model consisting of multiple blackbody components and corresponding physically to a compact object mass of greater than approximately 5 solar masses. No pulsations nor aperiodic behavior is evident in its X-ray light curve on the short timescales of the individual observations. The X-ray properties of the source are more similar to those of the nuclear source X-8 in M33, believed to be a low-mass X-ray binary, then to those of the low-luminosity active galactic nucleus in NGC 4395. The brightness of the nuclear star cluster, M_I ~ -11.8 mag, is typical of clusters in late-type spirals but its effective radius, r_e \~ 12 pc, is several times larger than average indicating a relatively relaxed cluster and a low probability of a central massive object. The cluster has a mass 3e6 solar masses and an age of 1.4 Gyr estimating from its observed colors and brightness.
description: 7 pages, submitted to ApJ
Επίδραση διατροφικής προσθήκης στεμφύλων οινοποιΐας στις αποδόσεις και τα ποιοτικά χαρακτηριστικά του αυγού ορνίθων αυγοπαραγωγής:
Creators: name: Κοΐδου, Μαρία Παύλου-Ρωμύλου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Στέμφυλα οινοποιΐας
Όρνιθες αυγοπαραγωγής
Οξειδωτική σταθερότητα
Grape pomace
Laying hens
Oxidative stability

description: Σκοπός της διατριβής ήταν να διερευνηθεί η επίδραση της διατροφικής προσθήκης νωπών στεμφύλων οινοποιΐας, στις αποδόσεις και τη μεταβολή του σωματικού βάρους των ορνίθων, τα ποιοτικά χαρακτηριστικά του αυγού καθώς και την οξειδωτική σταθερότητα της λεκίθου του αυγού. Αφού έγιναν όλες οι απαραίτητες χημικές και εργαστηριακές αναλύσεις, διαπιστώθηκε ότι η προσθήκη στεμφύλων οινοποιΐας στο σιτηρέσιο αυγοπαραγωγών ορνίθων δεν επηρέασε σημαντικά τις αποδόσεις και τα ποιοτικά χαρακτηριστικά του αυγού. Ωστόσο, η κύρια θετική επίδραση συνίσταται στη βελτίωση της οξειδωτικής σταθερότητας της λεκίθου του αυγού.
description: The aim of the present thesis was to determine the effect of grape pomace dietary supplementation in laying hens performance, egg quality traits and oxidative stability of homogenized liquid yolks. After having made all the necessary chemical and laboratory analysis, it was patently obvious that dietary supplementation of grape pomace in laying hens did not influence significantly laying performance and the vast majority of egg quality traits. However, the fore and foremost effect was the improvement of oxidative stability of homogenized liquid yolks.
title: Functionally Graded AA7075 Components Produced via Hot Stamping: A Novel Process Design Inspired from Analysis of Microstructure and Mechanical Properties
Creators: name: Bütev Öcal, Ezgi
name: Sajadifar, Seyed Vahid
name: Sellner, Erik P. K.
name: Vollmer, Malte
name: Heidarzadeh, Akbar
name: Zavašnik, Janez
name: Niendorf, Thomas
name: Groche, Peter
Publisher: name: Wiley-VCH
Year: 2024

description: Herein, functionally graded AA7075 components manufactured via hot stamping are investigated by focusing on the effect of different process variables on localized microstructure evolution. To realize gradation through stamping, an active tool is designed and applied. The design of experiments allows to assess the impact of transfer time from the furnace to the tool, quenching time in the tool, and final quenching media. Related characteristics of mechanical properties throughout the hat‐shaped profile are assessed via hardness and tensile tests. As expected, the sections of the samples formed in the cooled part of the tool are characterized by higher mechanical strength following subsequent aging, while sections formed in the heated part exhibit higher ductility. Moreover, the microstructural analysis reveals that fine precipitates with minimum interparticle distances only form in the cooled section of the samples. Increasing the tool temperature at the heated side to 350 °C results in the formation of coarse precipitates in the grain interior and along the grain boundaries. A sharp gradient in terms of microstructural and mechanical properties is found between these conditions. After reducing the transfer time, an increased volume fraction of fine precipitates leads to further improvements in hardness and mechanical strengths.
Model-based Prediction and Optimal Control of Pandemics by Non-pharmaceutical Interventions
Creators: name: Sameni, Reza
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Mathematics
subject: FOS: Biological sciences

description: A model-based signal processing framework is proposed for pandemic trend forecasting and control, by using non-pharmaceutical interventions (NPI) at regional and country levels worldwide. The control objective is to prescribe quantifiable NPI strategies at different levels of stringency, which balance between human factors (such as new cases and death rates) and cost of intervention per region/country. Due to infrastructural disparities and differences in priorities of regions and countries, strategists are given the flexibility to weight between different NPIs and to select the desired balance between the human factor and overall NPI cost. The proposed framework is based on a \textit{finite-horizon optimal control} (FHOC) formulation of the bi-objective problem and the FHOC is numerically solved by using an ad hoc \textit{extended Kalman filtering/smoothing} framework for optimal NPI estimation and pandemic trend forecasting. The algorithm enables strategists to select the desired balance between the human factor and NPI cost with a set of weights and parameters. The parameters of the model are partially selected by epidemiological facts from COVID-19 studies, and partially trained by using machine learning techniques. The developed algorithm is applied on ground truth data from the Oxford COVID-19 Government Response Tracker project, which has categorized and quantified the regional responses to the pandemic for more than 300 countries and regions worldwide, since January 2020. The dataset was used for NPI-based prediction and prescription during the XPRIZE Pandemic Response Challenge.
description: 11 Pages, 6 figures, 24 references
The subterahertz solar cycle: Polar and equatorial radii derived from SST and ALMA
Creators: name: Menezes, Fabian
Publisher: name: Zenodo
Year: 2021
Subjects: The Sun and the Heliosphere
Solar atmosphere
Center to limb observations
Time series analysis
Solar radio emission

description: At subterahertz frequencies – i.e., millimeter and submillimeter wavelengths – there is a gap of measurements of the solar radius as well as other parameters of the solar atmosphere. As the observational wavelength changes, the radius varies because the altitude of the dominant electromagnetic radiation is produced at different heights in the solar atmosphere. Moreover, radius variations throughout long time series are indicative of changes in the solar atmosphere that may be related to the solar cycle. Therefore, the solar radius is an important parameter for the calibration of solar atmospheric models enabling a better understanding of the atmospheric structure. In this work we use data from the So- lar Submillimeter-wave Telescope (SST) and from the Atacama Large Millimeter/submillimeter Array (ALMA), at the frequencies of 100, 212, 230, and 405 GHz, to measure the equatorial and polar radii of the Sun. The radii measured with extensive data from the SST agree with the radius-vs-frequency trend present in the literature. The radii derived from ALMA maps at 230 GHz also agree with the radius-vs-frequency trend, whereas the 100-GHz radii are slightly above the values reported by other authors. In addition, we analyze the equatorial and polar radius behavior over the years, by determining the correlation coefficient between solar activity and subterahertz radii time series at 212 and 405 GHz (SST). The variation of the SST-derived radii over 13 years are correlated to the solar activity when considering equatorial regions of the solar atmosphere, and anticorrelated when considering polar regions. The ALMA derived radii time series for 100 and 230 GHz show very similar behaviors with those of SST.
Hole dynamics in canted antiferromagnets
Creators: name: Hamad, I. J.
name: Manuel, L. O.
name: Martinez, G.
name: Trumper, A. E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We have analyzed the dynamics of a single hole doped in a canted antiferromagnet using the t-J model. Within the self consistent Born approximation we have found that the hole propagates at two different energy scales along the antiferromagnetic and the ferromagnetic components of the canted order, respectively. While the many body quasiparticle excitation has its origin in the coherent coupling of the hole with the magnon excitations of the antiferromagnetic component, the ferromagnetic component gives rise to a free like hole motion at higher energies. We have found a non-trivial behavior of the hole spectral function with the canting angle. In particular, in the strong coupling regime, the quasiparticle weight strongly depends on the momenta, vanishing inside the magnetic Brillouin zone for a canting angle greater than 60 degree.
description: 8 pages, 6 figures
Radiation Feedback and Fragmentation in Massive Protostellar Cores
Creators: name: Krumholz, Mark R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Star formation generally proceeds inside-out, with overdense regions inside protostellar cores collapsing rapidly and progressively less dense regions following later. Consequently, a small protostar will form early in the evolution of a core, and collapsing material will fall to the protostellar surface and radiate away its gravitational potential energy. The resulting accretion luminosity will heat the core and may substantially affect the process of fragmentation. This is of particular interest for massive cores that, at their initial temperatures, have masses much greater than a thermal Jeans mass and thus might be expected to fragment into many stars during collapse. Here I show that accretion luminosity can heat the inner parts of a core to >100 K very early in the star formation process, and that this in turn strongly suppresses fragmentation. This has implications for a number of outstanding problems in star formation, including the mechanism of massive star formation, the origin of the stellar initial mass function and its relationship to the core mass function, the demographics of massive binaries, and the equation of state in star-forming gas.
description: Accepted for publication in ApJL. 4 pages, 2 figures, emulateapj format
X-ray Spectra of Circumgalactic Medium Around Star-Forming Galaxies: Connecting Simulations to Observations
Creators: name: Vijayan, Aditi
name: Li, Miao
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The hot component of the circum-galactic medium (CGM) around star forming galaxies is detected as diffuse X-ray emission. The X-ray spectra from the CGM depend on the temperature and metallicity of the emitting plasma, providing important information about the feeding and feedback of the galaxy. The observed spectra are commonly fitted using simple 1-Temperature (1-T) or 2-T models. However, the actual temperature distribution of the gas can be complex because of the interaction between galactic outflows and halo gas. Here we demonstrate this by analysing 3-D hydrodynamical simulations of the CGM with a realistic outflow model. We investigate the physical properties of the simulated hot CGM, which shows a broad distribution in density, temperature, and metallicity. By constructing and fitting the simulated spectra, we show that, while the 1-T and 2-T models are able to fit the synthesized spectra reasonably well, the inferred temperature(s) does not bear much physical meaning. Instead, we propose a log-normal distribution as a more physical model. The log-normal model better fits the simulated spectra while reproducing the gas temperature distribution. We also show that when the star formation rate is high, the spectra inside the bi-conical outflows are distinct from that outside, as outflows are generally hotter and more metal-enriched. Finally, we produce mock spectra for future missions with the eV-level spectral resolution, such as Athena, Lynx, HUBS and XRISM.
description: 15 pages, 17 figures. Accepted for publication in MNRAS
Die Magier- und Gelehrtenparodien bei E.T.A. Hoffmann
Creators: name: Τενεκετζή, Χριστίνα Ελευθερίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Μάγοι
Επιστήμονες
Παρωδία
Wizards
Scientists
Parody

description: Η ακόλουθη μεταπτυχιακή διπλωματική εργασία εξετάζει την παρωδία του μάγου και του επιστήμονα στον E.T.A. Hoffmann. Ο Hoffmann ήταν μια από τις πιο σπουδαίες προσωπικότητες της εποχής του. Ως εκπρόσωπος του ρομαντισμού έστρεφε την προσοχή του κυρίως στο Φανταστικό. Ιδιαίτερα στα παραμύθια του γίνεται ευδιάκριτο, ότι το φανταστικό παρουσιάζεται μέσα σε έναν καθημερινό, αστικό κόσμο. Διαφορετικά απο άλλους Ρομαντικούς, οι οποίοι διεισδύουν στον κόσμο του Φανταστικού, ο Hoffmann ασχολείται στα έργα του με τον πραγματικό κόσμο. Συνδέει τους δύο κόσμους, αυτόν της πραγματικότητας με αυτόν της φαντασίας. Αντικείμενο της ανάλυσης αποτελεί μία ποικιλία κειμένων από το εκτενές έργο του Hoffmann. Η εργασία ασχολειται με πέντε από τα έργα του, δίνοντας βαρύτητα στο να περιγράψει και να εξετάσει την παρωδία του μάγου και του επιστήμονα, έτσι ώστε να υπογραμμίσει το παράλογο και το γκροτέσκο. Τα έργα, που χρησιμοποιήθηκαν για ανάλυση είναι: Der goldene Topf (1814), Klein Zaches, genannt Zinnober(1819), Der Elementargeist(1821), Haimatochare(1819), και Meister Floh (1822). Η εργασία χωρίζεται σε τρία μέρη, όπου γίνεται η ερμηνεία των επιλεγμένων κειμένων. Σε κάθε έργο εξετάστηκαν από άλλη οπτική γωνία τα μαγικά πλάσματα και δίνεται περισσότερη έμφαση στη χρήση της επιστήμης και την πνευματική και ψυχική ικανότητα των επιστημώνων. Στο τέλος ανακεφαλαιώνται τα σημαντικότερα χαρακτηριστικά και συμπεράσματα της παρούσας εργασίας.
description: The following postgraduate paper examines the parody of the wizard and scientist in E.T.A. Hoffmann. Hoffmann was one of the most prominent personalities of his era. As a representative of Romance, he placed more emphasis on the fictitious world. Especially, in his tales it is evident that “fiction” is presented in an every-day, urban world. Unlike other Romantics, who penetrate in the world of “fiction”, Hoffmann deals with the real world in his books. He connects the two worlds, the one of real life and the other of “fiction”. The object of the analysis is a variety of texts from Hoffmann’s extensive work. The paper deals with five of his books, with a stress on describing and examining the parody of wizards and scientist, in order to highlight the “absurd” and “grotesque”. His books which have been used for analysis are: Der goldene Topf (1814), Klein Zaches, genannt Zinnober (1819), Der Elementargeist (1821), Haimatochare (1819), and Meister Floh (1822). The paper is divided into three parts, where the interpretation of the chosen texts takes place. In every book the fictitious creatures were examined from a different ankle and more attention is paid on the use of science and the spiritual and mental ability of scientists. In the end, the most important characteristics and conclusions of the present paper are summarised.
The geometrical nature and some properties of the capacitance coefficients based on Laplace's Equation
Creators: name: Herrera, William J.
name: Diaz, Rodolfo A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Classical Physics (physics.class-ph)
subject: Physics Education (physics.ed-ph)
subject: FOS: Physical sciences

description: The fact that the capacitance coefficients for a set of conductors are geometrical factors is derived in most electricity and magnetism textbooks. We present an alternative derivation based on Laplace's equation that is accessible for an intermediate course on electricity and magnetism. The properties of Laplace's equation permits to prove many properties of the capacitance matrix. Some examples are given to illustrate the usefulness of such properties.
description: 6 pages, 2 figures, 1 table, 2 appendices, examples corrected, minor changes in wording. Version to appear in American Journal of Physics
Common dynamo scaling in late-type main sequence and evolved stars
Creators: name: Lehtinen, Jyri
name: Spada, Federico
name: Käpylä, Maarit
name: Olspert, Nigul
name: Käpylä, Petri
Publisher: name: Zenodo
Year: 2021

description: Both the magnetic activity and magnetic field strengths of late-type stars are observed to scale up with stellar rotation up to a certain saturation level. We show strong evidence from chromospheric Ca II H&K line emission observations that the same rotation-activity relation is shared by both main sequence stars and evolved giants. This indicates that the dynamos of both young and evolved stars follow the same underlying principles, irrespective of the stellar internal structure. The common scaling relation can only be found in relation to the Rossby number, i.e. the ratio of rotation period to the convective turnover time, meaning that this shared dynamo must be governed by turbulent convection. A more detailed analysis of the shape of the rotation-activity relation reveals a localised break in its slope at mid-activity levels. This knee point lies close to the threshold where large scale non-axisymmetric activity appears on fast rotating stars. It may thus be connected to a transition between axisymmetric and non-axisymmetric dynamo modes in slow and fast rotating stars.
Probing exosphere of Neptune size planets around M-dwarf using He10830
Creators: name: Ninan, Joe
name: Gudmundur Stefansson
name: Suvrath Mahadevan
name: Bender, Chad
name: Robertson, Paul
name: Terrien, Ryan
name: HPF Team
Publisher: name: Zenodo
Year: 2021
Subjects: Exoplanets around cool stars
Evaporating atmospheres

description: Recently, resonant scattering absorption of meta-stable Helium atoms at 10830 Angstroms has been identified as a powerful probe to detect the extended exospheres from exoplanets. This near-infrared line is observable from the ground and unaffected by the interstellar medium, and has numerous advantages over conventional Ly alpha. The high spectral resolution observations of these meta-stable helium atoms from the exospheres enable us to study the irradiation environment as well as the structure of the outflow from the evaporating atmospheres in M-dwarf planets. In this poster we present our first detection of He10830 in the exosphere of a warm Neptune orbiting an M-dwarf, GJ 3470, using the Habitable-Zone Planet Finder (HPF). We also present our analysis of the outflow structure via line profile analysis, and the EUV irradiation environment on the planet from this detection.
The light pseudoscalar Higgs boson in NMSSM
Creators: name: Arhrib, Abdesslam
name: Cheung, Kingman
name: Hou, Tie-Jiun
name: Song, Kok-Wee
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the associated production of a very light pseudoscalar Higgs boson with a pair of charginos. The novel signature involves a pair of charged leptons from chargino decays and a pair of photons from the pseudoscalar Higgs boson decay, plus large missing energy at the LHC and ILC. The signal may help us to distinguish the NMSSM from MSSM, provided that the experiment can resolve the two photons from the decay of the pseudoscalar Higgs boson.
description: pages, 2 figures; to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 2006
Nextflow: A tool for deploying reproducible computational pipelines
Creators: name: Tommaso, Paolo Di
name: Chatzou, Maria
name: Prieto, Pablo
name: Palumbo, Emilio
name: Notredame, Cedric
Publisher: name: F1000Research
Year: 2015

description: Nextflow is a data-driven framework for computational pipelines that simplifies writing parallel and scalable pipelines in a portable manner.

It is designed around the idea that the Linux platform is the lingua franca of data science. Linux provides many simple command line and scripting tools, which by themselves are powerful, but when chained together facilitate complex data manipulations.

Nextflow extends this approach adding to it the ability to define complex program interactions and an high-level parallel computational environment based on the dataflow programming model.

Moreover Nextflow provides an abstraction over the underlying execution platform. Thus, the resulting pipeline can run on a single workstation, on different grid infrastructures or in a cloud environment.

The integration with Docker containers technology and the Github sharing platform enables pipelines to be deployed, along with all their dependencies, across multiple platforms without any modifications, making it possible to share them and replicate their results in a predictable manner.
Homology and Derived p-Series of Groups
Creators: name: Cochran, Tim D.
name: Harvey, Shelly
Publisher: name: arXiv
Year: 2007
Subjects: subject: Geometric Topology (math.GT)
subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 57M27, 57M07, 20J05 (primary), 55P60 (secondary

description: We prove that groups that are mod-p-homology equivalent are isomorphic modulo any term of their derived p-series, in precise analogy to Stallings' 1963 result for the lower-central p-series. Similarly spaces that are mod-p-homology equivalent have fundamental groups that are isomorphic modulo any term of their p-derived series. Various authors have related the ranks of the successive quotients of the lower central p-series and of the derived p-series of the fundamental group of a 3-manifold M to the volume of M, to whether certain subgroups of the fundamental group of M are free, whether finite index subgroups of the fundamental group of M map onto non-abelian free groups, and to whether finite covers of M are ``large'' in various other senses. Specifically, let A be a finitely-generated group and B be a finitely presented group. If a homomorphism induces an isomorphism (respectively monomorphism) on H_1(- ;Z_p) and an epimorphism on H_2(- ;Z_p), then for each finite n, it induces an isomorphism (respectively monomorphism) between the quotients of A and B by the n-th terms of their respective p-derived series. In fact we prove a stronger version that is analogous to Dwyer's extension of Stallings' theorem.
description: 16 pages, simplified some proofs, added references, added a few applications
The 10.4m Gran Telescopio CANARIAS Instrumentation Capabilities
Creators: name: Garcia-Alvarez, David
Publisher: name: Zenodo
Year: 2021
Subjects: scientific astronomical instruments

description: GTC is producing science in a routinely manner since 2009, but at the same time enhancing its capabilities with the continuous advent of new instruments at the facility. This contribution summarizes the current status of the night operation of the 10.4 m GTC and describe GTC short and medium term instrumentation plan in the period 2020-2025.
description: Poster on instrumental capabilities of the 10.4 Gran Telescopio CANARIAS