cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers
Creators: name: Hoell, A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: We propose a collective Thomson scattering experiment at the VUV free electron laser facility at DESY (FLASH) which aims to diagnose warm dense matter at near-solid density. The plasma region of interest marks the transition from an ideal plasma to a correlated and degenerate many-particle system and is of current interest, e.g. in ICF experiments or laboratory astrophysics. Plasma diagnostic of such plasmas is a longstanding issue. The collective electron plasma mode (plasmon) is revealed in a pump-probe scattering experiment using the high-brilliant radiation to probe the plasma. The distinctive scattering features allow to infer basic plasma properties. For plasmas in thermal equilibrium the electron density and temperature is determined from scattering off the plasmon mode.
description: 25 pages, 10 figures. Proceedings of the international conference "Radiative Properties of Hot Dense Matter", Sept. 11-15, 2006, Albufeira, Portugal. To appear in"High Energy Density Physics"
Molecular remnant of Nova 1670 (CK Vulpeculae). II. A three-dimensional view on the gas distribution and velocity field
Creators: name: Kamiński, T.
name: Steffen, W.
name: Bujarrabal, V.
name: Tylenda, R.
name: Menten, K. M.
name: Hajduk, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: CK Vul is the remnant of an energetic eruption known as Nova 1670 that is thought to be caused by a stellar merger. The remnant is composed of (1) a large hourglass nebula of recombining gas (of 71\arcsec size), very similar to some classical planetary and pre-planetary nebulae (PPNe), and (2) of a much smaller and cooler inner remnant prominent in millimeter-wave emission from molecules. We investigate the three-dimensional spatio-kinematic structure of both components. The analysis of the hourglass structure yields a revised distance to the object of >2.6 kpc, at least 3.7 times greater than so far assumed. At this distance, the stellar remnant has a bolometric luminosity >12 L$_{\odot}$ and is surrounded by molecular material of total mass >0.8 M$_{\odot}$ (the latter value has a large systematic uncertainty). We also analyzed the architecture of the inner molecular nebula using ALMA observations of rotational emission lines obtained at subarcsecond resolution. We find that the distribution of neutral and ionized gas in the lobes can be reproduced by several nested and incomplete shells or jets with different velocity fields and varying orientations. The analysis indicates that the molecular remnant was created in several ejection episodes, possibly involving an interacting binary system. We calculated the linear momentum ($\approx$10$^{40}$ g cm s$^{-1}$) and kinetic energy ($\approx$10$^{47}$ erg) of the CK Vul outflows and find them within the limits typical for classical PPNe. Given the similarities of the CK Vul outflows to PPNe, we suggest there may CK Vul analogs among wrongly classified PPNe with low intrinsic luminosities, especially among PPNe with post-red-giant-branch central stars.
description: 12 pages, animations at: https://bit.ly/3hR6jSF and https://shorturl.at/gwzOT . Comments welcomed
Weak localisation in bilayer graphene
Creators: name: Gorbachev, R. V.
name: Tikhonenko, F. V.
name: Mayorov, A. S.
name: Horsell, D. W.
name: Savchenko, A. K.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We have performed the first experimental investigation of quantum interference corrections to the conductivity of a bilayer graphene structure. A negative magnetoresistance - a signature of weak localisation - is observed at different carrier densities, including the electro-neutrality region. It is very different, however, from the weak localisation in conventional two-dimensional systems. We show that it is controlled not only by the dephasing time, but also by different elastic processes that break the effective time-reversal symmetry and provide invervalley scattering.
description: 4 pages, 4 figures (to be published in PRL)
Derivation of the relativistic "proper-time" quantum evolution equations from Canonical Invariance
Creators: name: Shapiro, Moshe
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Based on 1) the spectral resolution of the energy operator; 2) the linearity of correspondence between physical observables and quantum Hermitian operators; 3) the definition of conjugate coordinate-momentum variables in classical mechanics; and 4) the fact that the physical point in phase space remains unchanged under (canonical) transformations between one pair of conjugate variables to another, we are able to show that , the proper-time rest-energy transformation matrices, are given as a*exp[-iE_s t_s/\hbar], from which we obtain the proper-time rest -energy evolution equation i\hbar{\partial/\partial t_s} |Psi>= \hat{E_s}|Psi>. For special relativistic situations this equation can be reduced to the usual i\hbar{\partial/\partial t}|Psi>=\hat{E}|Psi> dynamical equations, where t is the "reference time" and E is the total energy. Extension of these equations to accelerating frames is then provided.
description: J. Phys. A, accepted for publication
Coherent Beam Combination of Ultrafast Fiber Lasers
Creators: name: Klenke, Arno
name: Müller, Michael
name: Stark, Henning
name: Kienel, Marco
name: Jauregui, Cesar
name: Tünnermann, Andreas
name: Limpert, Jens
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The performance of fiber laser systems has drastically increased over recent decades, which has opened up new industrial and scientific applications for this technology. However, currently a number of physical effects prevents further power scaling. Coherent combination of beams from multiple emitters has been established as a power scaling technique beyond these limitations. It is possible to increase the average power and, for pulsed laser systems, also parameters such as the pulse energy and the peak power. To realize such laser systems, various aspects have to be taken into account which include beam combination elements, stabilization systems and the output parameters of the individual amplifiers. After an introduction to the topic, various ways of implementing coherent beam combination for ultrashort pulses are explored. Besides the spatial combination of beams, the combination of pulses in time will also be discussed. Recent experimental results will be presented, including multi-dimensional (i.e. spatial and temporal) combination. Finally, an outlook on possible further developments is given, focused on scaling the number of combinable beams and pulses.
Harmonic analysis of iterated function systems with overlap
Creators: name: Jorgensen, Palle E. T.
name: Kornelson, Keri A.
name: Shuman, Karen L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mathematical Physics (math-ph)
subject: Dynamical Systems (math.DS)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 33C50, 42C15, 46E22, 47B32

description: In this paper we extend previous work on IFSs without overlap. Our method involves systems of operators generalizing the more familiar Cuntz relations from operator algebra theory, and from subband filter operators in signal processing.
description: 37 pages
A Medium to Transform the Power of the Sun: Light, Space, and the Technological Apparatus
Creators: name: Ruff, Georgina Elizabeth
Publisher: name: University of Illinois at Chicago
Year: 2021
Subjects: Uncategorized

description: This study considers the implications of luminary technology used by artists László Moholy-Nagy, Otto Piene, and Olafur Eliasson, whose immersive installations of light in the 20th and 21st centuries are anchored by visible and familiar apparatuses. The deployment of the apparatus in these works forges ideological and/or social connections with actively engaged viewers, hindering the destruction of the aura by technology as theorized by Walter Benjamin. Analyzing the implications of the technological apparatus through the lens of a contemporary theory leads to the conclusion that while the physical, technological apparatus will necessarily obsolesce and tend toward the status of an artifact, it is the presence and critical engagement of the viewer with that apparatus upon which the aura of the work hinges. László Moholy-Nagy, in the construction of "Lichtrequisit einer elektrischen Bühne" (1930) sought to broaden the human sensorium and facilitate social change in a manner similar to that of his contemporary, Bertolt Brecht, who theorized productivity as the goal of the nascent radio. In the development of his "Lichtballette," Otto Piene shifted his positioning of the viewer from passive to active in relation to the apparatus: an evolution that resonates with the theories of Jean-Louis Baudry and Jean-Louis Comolli concerning the ideological and social power of the apparatus. In his intentional creation of larger dispositifs – as outlined by Michel Foucault, Giorgio Agamben, and Gilles Deleuze – Olafur Eliasson uses the physical technological apparatus as both a tangible connection to this larger system of relations, and as a facilitating aspect of the technological sublime as defined by David Nye. With an analysis of the physical technological apparatus which ideologically represents the artist and mediates the viewer’s experience, this study answers the call for a multi-valent approach to light-based installation works.
A Formally Verified Fail-Operational Safety Concept for Automated Driving
Creators: name: Fu, Yuting
name: Terechko, Andrei
name: Groote, Jan Friso
name: Saberi, Arash Khabbaz
Publisher: name: arXiv
Year: 2020
Subjects: subject: Robotics (cs.RO)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Formal Languages and Automata Theory (cs.FL)
subject: Systems and Control (eess.SY)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: B.8.1; C.3; J.7; C.0

description: Modern Automated Driving (AD) systems rely on safety measures to handle faults and to bring vehicle to a safe state. To eradicate lethal road accidents, car manufacturers are constantly introducing new perception as well as control systems. Contemporary automotive design and safety engineering best practices are suitable for analyzing system components in isolation, whereas today's highly complex and interdependent AD systems require novel approach to ensure resilience to multi-point failures. We present a holistic safety concept unifying advanced safety measures for handling multiple-point faults. Our proposed approach enables designers to focus on more pressing issues such as handling fault-free hazardous behavior associated with system performance limitations. To verify our approach, we developed an executable model of the safety concept in the formal specification language mCRL2. The model behavior is governed by a four-mode degradation policy controlling distributed processors, redundant communication networks, and virtual machines. To keep the vehicle as safe as possible our degradation policy can reduce driving comfort or AD system's availability using additional low-cost driving channels. We formalized five safety requirements in the modal mu-calculus and proved them against our mCRL2 model, which is intractable to accomplish exhaustively using traditional road tests or simulation techniques. In conclusion, our formally proven safety concept defines a holistic design pattern for designing AD systems.
description: 11 pages, 5 figures, 3 tables
Recent advances in terahertz photonic technologies based on graphene and their applications
Creators: name: Guo, Tianjing
name: Argyropoulos, Christos
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Graphene is a unique two-dimensional (2D) material that has been extensively investigated owing to its extraordinary photonic, electronic, thermal, and mechanical properties. Excited plasmons along its surface and other unique features are expected to play an important role in many emerging photonic technologies with drastically improved and tunable functionalities. This review is focused on presenting several recently introduced photonic phenomena based on graphene, beyond its usual linear response, such as nonlinear, active, topological, and nonreciprocal effects. The physical mechanisms and various envisioned photonic applications corresponding to these novel intriguing functionalities are also reported. The presented graphene-based technologies promise to revolutionize the field of photonics at the relatively unexplored terahertz (THz) frequency range. They are envisioned to lead to the design of compact harmonic generators, low-power wave mixers, linear and nonlinear sensors, magnet-free isolators and circulators, photonic topological insulators, modulators, compact coherent optical radiation sources, and subwavelength imaging devices.
Quantum Brownian motion for periodic coupling to an Ohmic bath
Creators: name: Piilo, J.
name: Maniscalco, S.
name: Suominen, K. -A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We show theoretically how the periodic coupling between an engineered reservoir and a quantum Brownian particle leads to the formation of a dynamical steady state which is characterized by an effective temperature above the temperature of the environment. The average steady state energy of the system has a higher value than expected from the environmental properties. The system experiences repeatedly a non-Markovian behavior -- as a consequence the corresponding effective decay for long evolution times is always on average stronger than the Markovian one. We also highlight the consequences of the scheme to the Zeno--anti-Zeno crossover which depends, in addition to the periodicity $τ$, also on the total evolution time of the system.
description: 7 pages, 3 figures. V2: Minor modifications according to the referee's suggestions and title modified
A Medium to Transform the Power of the Sun: Light, Space, and the Technological Apparatus
Creators: name: Ruff, Georgina Elizabeth
Publisher: name: University of Illinois at Chicago
Year: 2020
Subjects: Uncategorized

description: This study considers the implications of luminary technology used by artists László Moholy-Nagy, Otto Piene, and Olafur Eliasson, whose immersive installations of light in the 20th and 21st centuries are anchored by visible and familiar apparatuses. The deployment of the apparatus in these works forges ideological and/or social connections with actively engaged viewers, hindering the destruction of the aura by technology as theorized by Walter Benjamin. Analyzing the implications of the technological apparatus through the lens of a contemporary theory leads to the conclusion that while the physical, technological apparatus will necessarily obsolesce and tend toward the status of an artifact, it is the presence and critical engagement of the viewer with that apparatus upon which the aura of the work hinges. László Moholy-Nagy, in the construction of "Lichtrequisit einer elektrischen Bühne" (1930) sought to broaden the human sensorium and facilitate social change in a manner similar to that of his contemporary, Bertolt Brecht, who theorized productivity as the goal of the nascent radio. In the development of his "Lichtballette," Otto Piene shifted his positioning of the viewer from passive to active in relation to the apparatus: an evolution that resonates with the theories of Jean-Louis Baudry and Jean-Louis Comolli concerning the ideological and social power of the apparatus. In his intentional creation of larger dispositifs – as outlined by Michel Foucault, Giorgio Agamben, and Gilles Deleuze – Olafur Eliasson uses the physical technological apparatus as both a tangible connection to this larger system of relations, and as a facilitating aspect of the technological sublime as defined by David Nye. With an analysis of the physical technological apparatus which ideologically represents the artist and mediates the viewer’s experience, this study answers the call for a multi-valent approach to light-based installation works.
Using decision analysis to identify good institutional arrangements for local planning
Creators: name: Hunter, Dale William
Publisher: name: University of British Columbia
Year: 2009

description: This paper addresses a complex policy problem: "What are good institutional arrangements for local or neighbourhood planning in Vancouver?" The question has been the subject of analysis, debate and planning in a number of different forums over the past two decades and more, most recently in CityPlan, a large-scale participatory planning exercise. The study described here approached this issue as a decision analysis problem. Decision analysis is a set of analysis procedures that has been used successfully to incorporate public and multiplestakeholder input into complex decision making, in resource management issues for example. This analysis approach focusses on systematic identification and structuring of objectives that are correlated to values of stakeholders. It is used to analyze how alternatives perform from the point of view of different stakeholders who weight objectives (and predict impacts) differently from each other. Case studies suggest that this analysis framework has heuristic power and is capable of identifying and structuring good-fit solutions for conflicting interests. The key question addressed in this paper is whether this analysis approach can be used to advantage in an urban planning setting where there is citizen participation in complex policy questions. The analysis process described here was undertaken with the participation of 30 individuals from a range of stakeholder types, including citizens, developers, city staff, and city council. It completed three steps of decision analysis: identifying and structuring objectives; identifying and structuring alternatives; and predicting the impacts of alternatives on objectives. The results permit some initial judgements about the acceptability and potential productivity of this analysis approach in the study setting.
Non-linear dissolution mechanisms of sodium calcium phosphate glasses as a function of pH in various aqueous media
Creators: name: Oosterbeek, Reece N.
name: Margaronis, Kalliope I.
name: Zhang, Xiang C.
name: Best, Serena M.
name: Cameron, Ruth E.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Phosphate glasses for bioresorbable implants display dissolution rates that vary significantly with composition, however currently their mechanisms of dissolution are not well understood. Based on this systematic study we present new insights into these mechanisms. Two-stage dissolution was observed, with time dependence initially parabolic and later linear, and a two-stage model was developed to describe this behaviour. Dissolution was accelerated by lower Ca concentration in the glass, and lower pH in the dissolution medium. A new dissolution mechanism is proposed, involving an initial stage where diffusion-controlled formation of a conversion layer occurs. Once the conversion layer is stabilised, layer dissolution reactions become rate-limiting. Under this mechanism the transition time is sensitive to the nature of the conversion layer and solution conditions. These results reveal the dependence of P$_{2}$O$_{5}$-CaO-Na$_{2}$O glass dissolution on solution pH, and provide new insight into the dissolution mechanisms, particularly regarding the transition between the two dissolution stages.
description: 21 pages, 17 figures
Nonuniversal transmission phase lapses through a quantum dot: An exact-diagonalization of the many-body transport problem
Creators: name: Baksmaty, Leslie O.
name: Yannouleas, Constantine
name: Landman, Uzi
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Systematic trends of nonuniversal behavior of electron transmission phases through a quantum dot, with no phase lapse for the transition N=1 -> N=2 and a lapse of pi for the N=2 -> N=3 transition, are predicted, in agreement with experiments, from many-body transport calculations involving exact diagonalization of the dot Hamiltonian. The results favor shape anisotropy of the dot and strong e-e repulsion with consequent electron localization, showing dependence on spin configurations and the participation of excited doorway transmission channels.
description: Published version. REVTEX4. 4 pages with 3 color figures. For related papers, see http://www.prism.gatech.edu/~ph274cy/
Magneto and ferroelectric phase transitions in HoMn2O5 monocrystals
Creators: name: Radulov, I.
name: Lovchinov, V.
name: Daszkiewicz, M.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: From the physical point of view multiferroics present an extremely interesting class of systems and problems. These are essentially of two kinds. One is what are the microscopic conditions, and sometimes constrains, which determine the possibility to combine in one system both magnetic and ferroelectric properties. This turned out to be a quite nontrivial question, and usually, in conventional systems, these two phenomena tend to exclude one another. Why it is the case is an important and still not completely resolved issue. In the present article we report our results from magnetic properties measurements on HoMn2O5 with short discussion about it possible origin.
The Antikythera Mechanism: Web-based VR as a Hypothesis Checking Tool
Creators: name: Weibel, Thomas
Publisher: name: Zenodo
Year: 2025
Subjects: subject: Antikythera
subject: Science/history
subject: Archaeology
subject: Archaeoastronomy
subject: Astronomy
subject: Mechanics
subject: Greece
subject: Antiquity
subject: Virtual Reality
subject: Web Browser

description: Virtual Reality (VR) has become a widely used method for visualizing historical artifacts. However, its applicability in research is often limited by several factors: VR typically requires specialized hardware, such as headsets or dedicated projection systems, and the applications and models involved are often closed-source. In contrast, web-based VR applications are inherently open-source, allowing 3D models to be shared as open data. Furthermore, Web-VR applications can be configured to run in any web browser, without the need for additional hardware or specific platforms. This accessibility allows both the source code and 3D models to be remotely utilized by researchers, facilitating not only the visualization of artifacts but also the testing of hypotheses. Our 3D visualization of the Antikythera Mechanism — an ancient Greek astronomical calculating device from around 150 BCE — provides an opportunity to explore and assess the plausibility of various debated theories.
The Fornax Deep Survey (FDS) with the VST XI. The search for signs of preprocessing between the Fornax main cluster and Fornax A group
Creators: name: Su, Alan H.
name: Salo, Heikki
name: Janz, Joachim
name: Laurikainen, Eija
name: Venhola, Aku
name: Peletier, Reynier F.
name: Iodice, Enrica
name: Hilker, Michael
name: Cantiello, Michele
name: Napolitano, Nicola
name: Spavone, Marilena
name: Raj, Maria A.
name: van de Ven, Glenn
name: Mieske, Steffen.
name: Paolillo, Maurizio
name: Capaccioli, Massimo
name: Valentijn, Edwin A.
name: Watkins, Aaron E.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We investigate the structural properties of cluster and group galaxies by studying the Fornax main cluster and the infalling Fornax A group, exploring the effects of galaxy preprocessing in this showcase example. Additionally, we compare the structural complexity of Fornax galaxies to those in the Virgo cluster and in the field. Our sample consists of 582 galaxies from the Fornax main cluster and Fornax A group. We quantified the light distributions of each galaxy based on a combination of aperture photometry, Sérsic+PSF (point spread function) and multi-component decompositions, and non-parametric measures of morphology (Concentration $C$; Asymmetry $A$, Clumpiness $S$; Gini $G$; second order moment of light $M_{20}$), and structural complexity based on multi-component decompositions. These quantities were then compared between the Fornax main cluster and Fornax A group. The structural complexity of Fornax galaxies were also compared to those in Virgo and in the field. Overall, we find significant differences in the distributions of quantities derived from Sérsic profiles ($g'-r'$, $r'-i'$, $R_e$, and $\barμ_{e,r'}$), and non-parametric indices ($A$ and $S$) between the Fornax main cluster and Fornax A group. Moreover, we find significant cluster-centric trends with $r'-i'$, $R_e$, and $\barμ_{e,r'}$, as well as $A$, $S$, $G$, and $M_{20}$ for galaxies in the Fornax main cluster. We find the structural complexity of galaxies increases as a function of the absolute $r'$-band magnitude (and stellar mass), with the largest change occurring between -14 mag $\lesssim M_{r'}\lesssim$ -19 mag. This same trend was observed for galaxies in the Virgo cluster and in the field, which suggests that the formation or maintenance of morphological structures (e.g. bulges, bar) is largely dependent on the stellar mass of the galaxies, rather than their environment.
description: Submitted to A&A 9th October 2020, accepted 11th January 2021. For decompositions see https://www.oulu.fi/astronomy/FDS_DECOMP/main/index.html (username=password=sundial)
Regular black holes in quadratic gravity
Creators: name: Berej, Waldemar
name: Matyjasek, Jerzy
name: Tryniecki, Dariusz
name: Woronowicz, Mariusz
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The first-order correction of the perturbative solution of the coupled equations of the quadratic gravity and nonlinear electrodynamics is constructed, with the zeroth-order solution coinciding with the ones given by Ayón-Beato and Garc{\'ı}a and by Bronnikov. It is shown that a simple generalization of the Bronnikov's electromagnetic Lagrangian leads to the solution expressible in terms of the polylogarithm functions. The solution is parametrized by two integration constants and depends on two free parameters. By the boundary conditions the integration constants are related to the charge and total mass of the system as seen by a distant observer, whereas the free parameters are adjusted to make the resultant line element regular at the center. It is argued that various curvature invariants are also regular there that strongly suggests the regularity of the spacetime. Despite the complexity of the problem the obtained solution can be studied analytically. The location of the event horizon of the black hole, its asymptotics and temperature are calculated. Special emphasis is put on the extremal configuration.
Big wheels keep on rolling : the Canadian Museum of Rail Travel
Creators: name: Thorkelsson, Paul Hunter
Publisher: name: University of British Columbia
Year: 2009

description: The project under investigation here is a museum facility to house the full collection of historic Canadian trains currently on display at the existing Canadian Museum of Rail Travel located in Cranbrook, British Columbia. The site of the proposed museum is on a narrow strip of vacant land bordered along one edge by an operating railway yard and on the other by Highway 3/21 the major transportation route through Southern British Columbia. The intention of this siting is to allow the proposed museum to act as a backdrop to the city providing both a buffer between it and the industrial developments beyond the rail yards, as well as a reconnection of the City to the railway on which its history and development has been so dependant. The building itself is organized as two buildings (or layers) lying along side each other like rail cars on a series of tracks. The first building (entry building) houses the public activities of the museum including entry and information, gift shop, tea room/ cafe, temporary gallery, administration offices, archives, shipping/receiving and entrance to the orientation theatre. The second building (the train shed) houses the body of the collection and museum including the restored train sets and cars, elevated discussion space, orientation theatre, and restoration workshops. These two main buildings are connected by a long narrow spine which provides circulation from the entry building through the orientation theatre into the train shed and the collection itself. The spine also houses display areas and visible archives along its length which provide the passing viewer with further explanation of particular aspects of the museum's collection.
Tuning structural relaxations, mechanical properties, and degradation timescale of PLLA during hydrolytic degradation by blending with PLCL-PEG
Creators: name: Oosterbeek, Reece N.
name: Kwon, Kyung-Ah
name: Duffy, Patrick
name: McMahon, Sean
name: Zhang, Xiang C.
name: Best, Serena M.
name: Cameron, Ruth E.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Poly-L-lactide (PLLA) is a popular choice for medical devices due to its bioresorbability and superior mechanical properties compared with other polymers. However, although PLLA has been investigated for use in bioresorbable cardiovascular stents, it presents application-specific limitations which hamper device therapies. These include low toughness and strength compared with metals used for this purpose, and slow degradation. Blending PLLA with novel polyethylene glycol functionalised poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL-PEG) materials has been investigated here to tailor the mechanical properties and degradation behaviour of PLLA. This exciting approach provides a foundation for a next generation of bioresorbable materials whose properties can be rapidly tuned. The degradation of PLLA was significantly accelerated by addition of PLCL-PEG. After 30 days of degradation, several structural changes were observed in the polymer blends, which were dependent on the level of PLCL-PEG addition. Blends with low PLCL-PEG content displayed enthalpy relaxation, resulting in embrittlement, while blends with high PLCL-PEG content displayed crystallisation, due to enhanced chain mobility brought on by chain scission, also causing embrittlement. Moderate PLCL-PEG additions (10% PLCL(70:30)-PEG and 20 - 30% PLCL(80:20)-PEG) stabilised the structure, reducing the extent of enthalpy relaxation and crystallisation and thus retaining ductility. Compositional optimisation identified a sweet spot for this blend strategy, whereby the ductility was enhanced while maintaining strength. Our results indicate that blending PLLA with PLCL-PEG provides an effective method of tuning the degradation timescale and mechanical properties of PLLA, and provides important new insight into the mechanisms of structural relaxations that occur during degradation, and strategies for regulating these.
description: 17 pages, 11 figures
Switching via quantum activation: A parametrically modulated oscillator
Creators: name: Marthaler, M.
name: Dykman, M. I.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study switching between period-two states of an underdamped quantum oscillator modulated at nearly twice its natural frequency. For all temperatures and parameter values switching occurs via quantum activation: it is determined by diffusion over oscillator quasienergy, provided the relaxation rate exceeds the rate of interstate tunneling. The diffusion has quantum origin and accompanies relaxation to the stable state. We find the semiclassical distribution over quasienergy. For T=0, where the system has detailed balance, this distribution differs from the distribution for $T\to 0$; the T=0 distribution is also destroyed by small dephasing of the oscillator. The characteristic quantum activation energy of switching displays a typical dependence on temperature and scaling behavior near the bifurcation point where period doubling occurs.
description: 15 pages, 10 figures, typos corrected
Search for double $β$-decay modes of $^{64}$Zn using purified zinc
Creators: name: Bellini, F.
name: Beretta, M.
name: Cardani, L.
name: Carniti, P.
name: Casali, N.
name: Celi, E.
name: Chiesa, D.
name: Clemenza, M.
name: Dafinei, I.
name: Di Domizio, S.
name: Ferroni, F.
name: Gironi, L.
name: Gorbenko, Yu. V.
name: Gotti, C.
name: Kovtun, G. P.
name: Laubenstein, M.
name: Nagorny, S.
name: Nisi, S.
name: Pagnanini, L.
name: Pattavina, L.
name: Pessina, G.
name: Pirro, S.
name: Previtali, E.
name: Rusconi, C.
name: Schaffner, K.
name: Shcherban, A. P.
name: Solopikhin, D. A.
name: Virich, V. D.
name: Tomei, C.
name: Vignati, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: The production of ultra-pure raw material is a crucial step to ensure the required background level in rare event searches. In this work, we establish an innovative technique developed to produce high-purity (99.999%) granular zinc. We demonstrate the effectiveness of the refining procedure by measuring the internal contaminations of the purified zinc with a high-purity germanium detector at the Laboratori Nazionali del Gran Sasso. The total activity of cosmogenic activated nuclides is measured at the level of a few mBq/kg, as well as limits on naturally occurring radionuclides are set to less than mBq/kg. The excellent radiopurity of the zinc sample allows us to search for electron capture with positron emission and neutrinoless double electron capture of $^{64}$Zn, setting the currently most stringent lower limits on their half-lives, $T_{1/2}^{\varepsilonβ^+} > 2.7 \times 10^{21}\text{yr}$ (90% C.I.), and $T_{1/2}^{0\nu2\varepsilon}> 2.6 \times 10^{21}\text{yr}$ (90% C.I.), respectively.
The X10 Flare on 2003 October 29: Triggered by Magnetic Reconnection between Counter-Helical Fluxes?
Creators: name: Liu, Y.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Vector magnetograms taken at Huairou Solar Observing Station (HSOS) and Mees Solar Observatory (MSO) reveal that the super active region (AR) NOAA 10486 was a complex region containing current helicity flux of opposite signs. The main positive sunspots were dominated by negative helicity fields, while positive helicity patches persisted both inside and around the main positive sunspots. Based on a comparison of two days of deduced current helicity density, pronounced changes were noticed which were associated with the occurrence of an X10 flare that peaked at 20:49 UT, 2003 October 29. The average current helicity density (negative) of the main sunspots decreased significantly by about 50. Accordingly, the helicity densities of counter-helical patches (positive) were also found to decay by the same proportion or more. In addition, two hard X-ray (HXR) `footpoints' were observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI} during the flare in the 50-100 keV energy range. The cores of these two HXR footpoints were adjacent to the positions of two patches with positive current helicity which disappeared after the flare. This strongly suggested that the X10 flare on 2003 Oct. 29 resulted from reconnection between magnetic flux tubes having opposite current helicity. Finally, the global decrease of current helicity in AR 10486 by ~50% can be understood as the helicity launched away by the halo coronal mass ejection (CME) associated with the X10 flare.
description: Solar Physics, 2007, in press
Quantum computing with magnetic atoms in optical lattices of reduced periodicity
Creators: name: Ravaine, Boris
name: Derevianko, Andrei
name: Berman, P. R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We investigate the feasibility of combining Raman optical lattices with a quantum computing architecture based on lattice-confined magnetically interacting neutral atoms. A particular advantage of the standing Raman field lattices comes from reduced interatomic separations leading to increased interatomic interactions and improved multi-qubit gate performance. Specifically, we analyze a $J=3/2$ Zeeman system placed in $% σ_{+}-σ_{-}$ Raman fields which exhibit $λ/4$ periodicity. We find that the resulting CNOT gate operations times are in the order of millisecond. We also investigate motional and magnetic-field induced decoherences specific to the proposed architecture.
CNN-based event classification for alpha-decay events in nuclear emulsion
Creators: name: Yoshida, J.
name: Ekawa, H.
name: Kasagi, A.
name: Nakagawa, M.
name: Nakazawa, K.
name: Saito, N.
name: Saito, T. R.
name: Taki, M.
name: Yoshimoto, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We developed an efficient classifier that sorts alpha-decay events from various vertex-like objects in nuclear emulsion using a convolutional neural network (CNN). Alpha-decay events in the emulsion are standard calibration sources for the relation between the track length and kinetic energy in each emulsion sheet. We trained the CNN using 15,885 images of vertex-like objects including 906 alpha-decay events and tested it using a dataset of 46,948 images including 255 alpha-decay events. By tuning the hyperparameters of the CNN, the trained models achieved an Average Precision Score of 0.740 +/- 0.009 for the test dataset. For the model obtained, a discrimination threshold of the classification can be arbitrarily adjusted according to the balance between the precision and recall. The precision and recall of the classification using previous method without a CNN were 0.081 +/- 0.006 and 0.788 +/- 0.056, respectively, for the same dataset. By contrast, the developed classifier obtained a precision of 0.547 +/- 0.025 when a similar recall value of 0.788 was set. The developed CNN method reduced the human load for further visual inspection after the classification by approximately 1/7 compared to the estimated load of the former method without a CNN.
Quantum healing of classical singularities in power-law spacetimes
Creators: name: Helliwell, T. M.
name: Konkowski, D. A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study a broad class of spacetimes whose metric coefficients reduce to powers of a radius r in the limit of small r. Among these four-parameter "power-law" metrics we identify those parameters for which the spacetimes have classical singularities as r approaches 0. We show that a large set of such classically singular spacetimes is nevertheless nonsingular quantum mechanically, in that the Hamiltonian operator is essentially self-adjoint, so that the evolution of quantum wave packets lacks the ambiguity associated with scattering off singularities. Using these metrics, the broadest class yet studied to compare classical with quantum singularities, we explore the physical reasons why some that are singular classically are "healed" quantum mechanically, while others are not. We show that most (but not all) of the remaining quantum-mechanically singular spacetimes can be excluded if either the weak energy condition or the dominant energy condition is invoked, and we briefly discuss the effect of this work on the strong cosmic censorship hypothesis.
description: 14 pages, 1 figure; extensive revisions
INTEGRAL and XMM-Newton observations towards the unidentified MeV source GRO J1411-64
Creators: name: Torres, Diego F.
name: Zhang, Shu
name: Reimer, Olaf
name: Barcons, Xavier
name: Corral, Amalia
name: Bosch-Ramon, Valenti
name: Paredes, Josep M.
name: Romero, Gustavo E.
name: Qu, Jin Lu
name: Collmar, Werner
name: Schonfelder, V.
name: Butt, Yousaf
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The COMPTEL unidentified source GRO J1411-64 was observed by INTEGRAL, and its central part, also by XMM-Newton. The data analysis shows no hint for new detections at hard X-rays. The upper limits in flux herein presented constrain the energy spectrum of whatever was producing GRO J1411-64, imposing, in the framework of earlier COMPTEL observations, the existence of a peak in power output located somewhere between 300-700 keV for the so-called low state. The Circinus Galaxy is the only source detected within the 4$σ$ location error of GRO J1411-64, but can be safely excluded as the possible counterpart: the extrapolation of the energy spectrum is well below the one for GRO J1411-64 at MeV energies. 22 significant sources (likelihood $> 10$) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the COMPTEL source position uncertainty make an association hard to quantify and thus risky. The unique peak of the power output at high energies (hard X-rays and gamma-rays) resembles that found in the SED seen in blazars or microquasars. However, an analysis using a microquasar model consisting on a magnetized conical jet filled with relativistic electrons which radiate through synchrotron and inverse Compton scattering with star, disk, corona and synchrotron photons shows that it is hard to comply with all observational constrains. This and the non-detection at hard X-rays introduce an a-posteriori question mark upon the physical reality of this source, which is discussed in some detail.
Active and Non-Active Site Mutations in Staphylococcus aureus FabI Responsible for Triclosan Resistance
Creators: name: Robel D Demissie
Publisher: name: University of Illinois at Chicago
Year: 2020
Subjects: Uncategorized

description: Up to 30% of the world population is colonized with nasal Staphylococcus aureus and nasal colonization can cause opportunistic and sometimes life-threatening infections. Triclosan is an antimicrobial agent/biocide, originally used in hospital settings as a disinfectant to remove bacterial colonies, including S. aureus, and was incorporated into a variety of consumer products. Triclosan inhibits the enoyl-acyl carrier protein reductase, or FabI, an essential enzyme in the fatty acid biosynthetic pathway in many pathogens including S. aureus. Bacterial cells mutation rate is roughly 0.003 mutations per genome per cell generation; mutations continuously occur naturally. The extensive use of triclosan selects S. aureus enzyme FabI mutants that do not bind triclosan. A simple method to determine which mutant does not bind triclosan is important. We have developed an efficient and economical method to test for triclosan binding to mutants, using a thermal shift method. We applied this method to S. aureus cells with FabI mutants generated randomly in laboratory. We showed that four mutants with mutations in active site did not bind triclosan as expected. We also identified nine mutations that are not located at the active site, but affect triclosan binding. We found that the mutations were in disparate positions in the monomer-monomer and dimer-dimer interface regions. We suggest that these sites may serve as potential allosteric sites that can be targeted by potential therapeutics to inhibit the FabI from S. aureus. In addition, we have observed cellular thermal shift assay results vary for certain mutants when conducted in intact cells compared to lysate conditions. We attribute these differences to quinary interactions that are present in the cell, but mostly abolished in the lysate.
Boundary multifractality in critical 1D systems with long-range hopping
Creators: name: Mildenberger, A.
name: Subramaniam, A. R.
name: Narayanan, R.
name: Evers, F.
name: Gruzberg, I. A.
name: Mirlin, A. D.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: Boundary multifractality of electronic wave functions is studied analytically and numerically for the power-law random banded matrix (PRBM) model, describing a critical one-dimensional system with long-range hopping. The peculiarity of the Anderson localization transition in this model is the existence of a line of fixed points describing the critical system in the bulk. We demonstrate that the boundary critical theory of the PRBM model is not uniquely determined by the bulk properties. Instead, the boundary criticality is controlled by an additional parameter characterizing the hopping amplitudes of particles reflected by the boundary.
description: 7 pages, 4 figures, some typos corrected
Bottomonium spectroscopy in the quark-gluon plasma
Creators: name: Wolschin, Georg
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The spectroscopic properties of heavy quarkonia are substantially different in the quark-gluon plasma (QGP) that is created in relativistic heavy-ion collisions as compared to the vacuum situation that can be tested in pp collisions at the same center-of-mass energy. In this article, a series of recent works about the dissociation of the Y(nS) and chi_b(nP) states in the hot QGP is summarized. Quarkonia dissociation occurs due to (1) screening of the real quark-antiquark potential, (2) collisional damping through the imaginary part of the potential, and (3) gluon-induced dissociation. In addition, reduced feed-down plays a decisive role for the spin-triplet ground state. Transverse-momentum and centrality-dependent data are well reproduced in Pb-Pb collisions at LHC energies. In the asymmetric p-Pb system, alterations of the parton density functions in the lead nucleus account for the leading fraction of the modifications in cold nuclear matter (CNM), but the hot-medium effects turn out to be relevant in spite of the small initial spatial extent of the fireball, providing additional evidence for the generation of a quark-gluon droplet.
description: 22 pages, 24 figures; Invited Review for Int. J. Mod. Phys. A