cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
title: Erlernen effizienter Constraints in der Antwortmengenprogrammierung
Creators: name: Tarzariol, Alice
Publisher: name: Gesellschaft für Informatik e.V.
Year: 2024

description: Für das effiziente Lösen kombinatorischer Probleme kann das Herausfiltern symmetri-
scher Lösungskandidaten aus dem Suchraum entscheidend sein. Die meisten existierenden Ansätze
sind instanzspezifisch und konzentrieren sich auf die automatische Berechnung von sogenannten
Symmetry Breaking Constraints (SBCs) für eine gegebene Probleminstanz. Die Anwendbarkeit sol-
cher Ansätze auf große Instanzen oder nicht-triviale Problemmodelle wird jedoch dadurch einge-
schränkt, dass eine große Anzahl spezialisierter SBCs berechnet werden müssen, die sich weder
sinnvoll interpretieren lassen noch auf andere Instanzen übertragbar sind. Infolgedessen ist vor je-
dem Aufruf eines Lösungssystems eine zeitaufwändige Neuberechnung der SBCs erforderlich. Um
derartige Schwierigkeiten zu überwinden, stellen wir einen neuen modellorientierten Ansatz für die
Antwortmengenprogrammierung vor, der die SBCs einfacher Probleminstanzen in interpretierba-
re prädikatenlogische Beschränkungen überführt und dafür eine Form des maschinellen Lernens
namens Inductive Logic Programming verwendet. Ausgehend von der Behandlung prototypischer
kombinatorischer Probleme ermöglichen spezifische Erweiterungen unseres Ansatzes das Lösen
fortgeschrittener, aus industriellen Anwendungen stammender Such- und Optimierungsprobleme.
$G_2$ generating technique for minimal D=5 supergravity and black rings
Creators: name: Bouchareb, Adel
name: Chen, Chiang-Mei
name: Clement, Gerard
name: Gal'tsov, Dmitri V.
name: Scherbluk, Nikolai G.
name: Wolf, Thomas
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: A solution generating technique is developed for D=5 minimal supergravity with two commuting Killing vectors based on the $G_2$ U-duality arising in the reduction of the theory to three dimensions. The target space of the corresponding 3-dimensional sigma-model is the coset $G_{2(2)}/(SL(2,R)\times SL(2,R))$. Its isometries constitute the set of solution generating symmetries. These include two electric and two magnetic Harrison transformations with the corresponding two pairs of gauge transformations, three $SL(2,R) S$-duality transformations, and the three gravitational scale, gauge and Ehlers transformations (altogether 14). We construct a representation of the coset in terms of $7\times 7$ matrices realizing the automorphisms of split octonions. Generating a new solution amounts to transforming the coset matrices by one-parametric subgroups of $G_{2(2)}$ and subsequently solving the dualization equations. Using this formalism we derive a new charged black ring solution with two independent parameters of rotation.
description: 21 pages revtex-4, 1 figure, typo corrected in Eq. (103)
Direct observation of nanometer-scale pinning sites in (Nd$_{0.33}$,Eu$_{0.20}$,Gd$_{0.47}$)Ba$_2$Cu$_3$O$_{7-δ}$ single crystals
Creators: name: Das, P.
name: Koblischka, M. R.
name: Turner, S.
name: van Tendeloo, G.
name: Wolf, Th.
name: Jirsa, M.
name: Hartmann, U.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report on the observation of self-organized stripe-like structures on the as-grown surface and in the bulk of (Nd,Eu,Gd)Ba$_2$Cu$_3$O$_y$ single crystals. The periodicity of the stripes on the surface lies between 500 and 800 nm. These are possibly the growth steps of the crystal. Transmission electron microscopy investigations revealed stripes of periodicity in the range of 20 to 40 nm in the bulk. From electron back scattered diffraction investigations, no crystallographic misorientation due to the nanostripes has been found. Scanning tunneling spectroscopic experiments revealed nonsuperconducting regions, running along twin directions, which presumably constitute strong pinning sites.
description: 4 pages, 5 Figures
Cerium (III) and (IV) containing mesoporous glasses/alginate beads for bone regeneration: bioactivity, biocompatibility and reactive oxygen species activity
Creators: name: Varini, E.
name: Sanchez-Salcedo, S.
name: Malavasi, G.
name: Lusvardi, G.
name: Vallet-Regi, M.
name: Salinas, A. J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Tissues and Organs (q-bio.TO)
subject: FOS: Biological sciences

description: A very small number of biomaterials investigated for bone regeneration was reported as able to prevent the oxidative stress. In this study beads based on alginate hydrogel and mesoporous glasses (MG) containing different amounts of cerium oxides (Ce3+/Ce4+) exhibiting antioxidant properties were investigated as a good approach to mimic the action of antioxidant enzymes in our organism. The effect of cerium contents on the bioactivity and biocompatibility of beads were investigated. Moreover, the potential capability of Ce-containing MG to prevent the oxidative stress caused by the activity of reactive oxygen species (ROS) was here investigated for the first time. The increment of cerium oxide from 1.2, to 3.6 and 5.3 mol-% decreases the surface area and porosity of MG and increases the catalase mimetic activity after 168 h. Swelling tests in different cell culture media (D- and α-MEM) demonstrated the rehydration capability of beads. The presence of beads with the highest Ce-contents (3.6 and 5.3 %) improved the proliferation of pre-osteoblastic cells MC3T3-C1 cells. However, the cell differentiation decreased when increased the cerium content. Lactate dehydrogenase assays showed beads are cytocompatible materials. Moreover, oxidative stress tests with H2O2 showed a better response related to cell viability and the elimination of oxidant species when increased cerium content. Beads of glasses with 1.2 and 3.6 % of CeO2 are excellent candidates as bioactive scaffolds for bone regeneration capable of counteract the oxidative stress.
description: 40 pages, 8 figures
Observations of Galactic Gamma-Ray Sources with H.E.S.S
Creators: name: Berge, D.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: H.E.S.S. results from the first three years of nominal operation are presented. Among the many exciting measurements that have been made, most gamma-ray sources are of Galactic origin. I will concentrate here on an overview of Galactic observations and summarise and discuss observations of selected objects of the different source types.
description: 13 pages, 10 figures, based on a talk presented at the workshop 'Energy Budget in the High Energy Universe', Kashiwa, Japan 22 - 24 February 2006
title: Modellbasierte Regelung dezentraler Systeme in unbekannten Umgebungen
Creators: name: Puzicha, Alexander
Publisher: name: Gesellschaft für Informatik e.V.
Year: 2024

description: Diese Arbeit entwickelt eine Softwareumgebung zur Simulation, Emulation und Regelung
autonomer Roboterschwärme insbesondere zum Einsatz in Katastrophengebieten. Die Realisierung
des Ansatzes und die Integration dieses in einen Prototypen wird ebenfalls dargelegt. Dazu werden
Anforderungen aus der Einsatzbeschreibung abgeleitet und die verfügbaren Regelungsalgorithmen
auf ihre Anwendbarkeit hin untersucht. Da keines der betrachteten Verfahren hinreichend ist, wird
ein probabilistisch planender modellbasierter Regler entwickelt, der auf „Control Particle Belief Pro-
pagation“ aufbaut und mit den anderen Verfahren ausgiebig verglichen wird. Als weiterer wichtiger
Baustein des dezentralen Schwarms wird ein mobiles ad hoc Netzwerk auf Basis der „Long Range“
Technologie entwickelt. Die beiden entwickelten Softwarekomponenten bilden je ein Modul des mo-
dularen und stark parallelisierten Autonomiekerns. Dieser ist plattform- und architekturunabhängig,
somit kann er ohne Anpassung sowohl in Simulationen als auch auf eingebetteten Systemen ver-
wendet werden. Die dezentrale aber emergente Verhaltensmodellierung fußt auf einer erweiterten
Potenzialfeldtechnik, die beliebige Aggregationen und globale Lösungen ermöglicht. Die Validie-
rung erfolgt anhand der Integration eines realen Prototypen in Kombination mit der Simulation und
einer Emulation.
WIMP Annihilation and Cooling of Neutron Stars
Creators: name: Kouvaris, Chris
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the effect of WIMP annihilation on the temperature of a neutron star. We shall argue that the released energy due to WIMP annihilation inside the neutron stars, might affect the temperature of stars older than 10 million years, flattening out the temperature at $\sim 10^4$ K for a typical neutron star.
description: 20 pages, 2 figures
The VISCACHA survey -- III. Star clusters counterpart of the Magellanic Bridge and Counter-Bridge in 8D
Creators: name: Dias, B.
name: Angelo, M. S.
name: Oliveira, R. A. P.
name: Maia, F.
name: Parisi, M. C.
name: De Bortoli, B.
name: Souza, S. O.
name: Santrich, O. J. Katime
name: Bassino, L. P.
name: Barbuy, B.
name: Bica, E.
name: Geisler, D.
name: Kerber, L.
name: Pérez-Villegas, A.
name: Quint, B.
name: Sanmartim, D.
name: Santos, J. F. C.
name: Westera, P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Context. The interactions between the SMC and LMC created the Magellanic Bridge, a stream of gas and stars pulled out of the SMC towards the LMC about 150 Myr ago. The tidal counterpart of this structure, which should include a trailing arm, has been predicted by models but no compelling observational evidence has confirmed the Counter-Bridge so far. Aims. The main goal of this work is to find the stellar counterpart of the Magellanic Bridge and Counter-Bridge. We use star clusters in the SMC outskirts as they provide 6D phase-space vector, age and metallicity that help characterise the outskirts of the SMC. Methods. Distances, ages and photometric metallicities are derived from fitting isochrones to the colour-magnitude diagrams from the VISCACHA survey. Radial velocities and spectroscopic metallicities are derived from the spectroscopic follow-up using GMOS in the CaII triplet region. Results. Among the seven clusters analysed in this work, five belong to the Magellanic Bridge and one belongs to the Counter-Bridge and the other to the transition region. Conclusions. The existence of the tidal counterpart of the Magellanic Bridge is evidenced by star clusters. The stellar component of the Magellanic Bridge and Counter-Bridge are confirmed in the SMC outskirts. These results are an important constraint for models that seek to reconstruct the history of the orbit and interactions between LMC-SMC and constrain their future interaction including with the Milky Way.
description: 10 pages, 7 figures. Astronomy and Astrophysics Letter, accepted. For associated video file (fig.A.4), see https://drive.google.com/file/d/1mSx3z6vDjHUneEeVq1i-MHwXZ1O0pZ-f
title: Skalierbares SAT Solving und dessen Anwendung
Creators: name: Schreiber, Dominik
Publisher: name: Gesellschaft für Informatik e.V.
Year: 2024

description: Das Problem der aussagenlogischen Erfüllbarkeit (Propositional Satisfiability, SAT) besteht darin, eine Variablenbelegung für eine gegebene aussagenlogische Formel zu finden, sodass die Formel “wahr” ergibt, oder, wenn keine solche Belegung existiert, Unerfüllbarkeit zu attestieren.

Das Lösen derartiger Probleme, genannt SAT Solving, hat aufgrund seiner theoretischen Bedeutung,
seiner generischen Natur und seiner breiten Anwendbarkeit auf eine Vielzahl von Problemen viel
Beachtung erlangt. In der vorgestellten Dissertation widmen wir uns einer Reihe von Herausfor-
derungen zur Skalierbarkeit von SAT Solving in modernen Rechenumgebungen. Zunächst stellen
wir einen dezentralen und flexiblen Ressourcenzuteilungs-Ansatz vor, um viele SAT-Aufgaben zu-
gleich möglichst effizient zu lösen. Zweitens präsentieren wir ein vielfach ausgezeichnetes System für paralleles und verteiltes SAT Solving und, damit verbunden, den ersten praktikablen Ansatz, aus derartigen Systemen Beweise der Unerfüllbarkeit zu gewinnen. Zuletzt stellen wir in einer Anwendungsstudie einen radikal neuartigen Ansatz für SAT-basiertes hierarchisches Planen vor.
Does nitrate deposition following astrophysical ionizing radiation events pose an additional threat to amphibians?
Creators: name: Thomas, Brian C.
name: Honeyman, Michelle D.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: Geophysics (physics.geo-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: It is known that amphibians are especially susceptible to the combination of heightened UVB radiation and increased nitrate concentrations. Various astrophysical events have been suggested as sources of ionizing radiation that could pose a threat to life on Earth, through destruction of the ozone layer and subsequent increase in UVB, followed by deposition of nitrate. In this study, we investigate whether the nitrate deposition following an ionizing event is sufficiently large to cause an additional stress beyond that of the heightened UVB previously considered. We have converted predicted nitrate depositions to concentration values, utilizing data from the New York State Department of Environmental Conservation Acid Rain Monitoring Network web site. Our results show that the increase in nitrate concentration in bodies of water following the most intense ionization event likely in the last billion years would not be sufficient to cause a serious additional stress on amphibian populations and may actually provide some benefit by acting as fertilizer.
description: This version is a longer, more detailed draft of an article submitted to the journal Astrobiology
On the physical meaning of the Unruh effect
Creators: name: Akhmedov, Emil T.
name: Singleton, Douglas
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Accelerator Physics (physics.acc-ph)
subject: FOS: Physical sciences

description: We present simple arguments that detectors moving with constant acceleration (even acceleration for a finite time) should detect particles. The effect is seen to be universal. Moreover, detectors undergoing linear acceleration and uniform, circular motion both detect particles for the same physical reason. We show that if one uses a circularly orbiting electron in a constant external magnetic field as the Unruh--DeWitt detector, then the Unruh effect physically coincides with the experimentally verified Sokolov--Ternov effect.
description: 7 pages, 0 figures references added, small changes in text. To be published JETP Letts
Dislocations in gallium arsenide deformed at high temperatures
Creators: name: Gallagher, Patrick John
Publisher: name: University of British Columbia
Year: 2010

description: Test pieces of GaAs were cut from Czochralski grown <100> wafers. Prior to deformation the dislocation configuration was established by cathodoluminescence (CL). Etch pits produced by molten KOH on examined crystal surfaces coincided with the CL images. The test pieces were capped with Si₃N₄, heated to between 950 and 1050°C, and plastically deformed by bending. The dislocation configuration after bending was then compared to that of the undeformed crystal. It was observed that heating to 1050°C did not significantly change the as grown cellular dislocation arrays in the crystal. With strain the dislocation configuration changed appreciably. New bands of dislocations were formed, parallel to the bend axis with dislocation free regions between them. Increasing the strain increased the number of bands. Observations were made on undoped crystals with high and low dislocation densities, and Si doped crystals. The luminescent properties of the dislocations were observed to change with heating and strain. As grown, a dislocation imaged as a dark spot surrounded by a bright halo, giving bright dislocation networks. After heating to 950°C samples showed only the dark spots without halos. After deformation, all the new dislocations appeared as dark spots or lines without halos. At very low strains, the original dislocations were still evident but were distinct from the new arrays. In an attempt to correlate the dislocation images with impurity segregation some observations of the samples were made using secondary ion mass spectroscopy (SIMS). The results suggest the possibility of the dark areas in the CL images being associated with the presence of carbon.
Maximum Power Efficiency and Criticality in Random Boolean Networks
Creators: name: Carteret, Hilary A.
name: Rose, Kelly John
name: Kauffman, Stuart A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Other Quantitative Biology (q-bio.OT)
subject: FOS: Biological sciences

description: Random Boolean networks are models of disordered causal systems that can occur in cells and the biosphere. These are open thermodynamic systems exhibiting a flow of energy that is dissipated at a finite rate. Life does work to acquire more energy, then uses the available energy it has gained to perform more work. It is plausible that natural selection has optimized many biological systems for power efficiency: useful power generated per unit fuel. In this letter we begin to investigate these questions for random Boolean networks using Landauer's erasure principle, which defines a minimum entropy cost for bit erasure. We show that critical Boolean networks maximize available power efficiency, which requires that the system have a finite displacement from equilibrium. Our initial results may extend to more realistic models for cells and ecosystems.
description: 4 pages RevTeX, 1 figure in .eps format. Comments welcome, v2: minor clarifications added, conclusions unchanged. v3: paper rewritten to clarify it; conclusions unchanged
Closure methods for the single-server retrial queue
Creators: name: Sabo, David Warren
Publisher: name: University of British Columbia
Year: 2010

description: This work focuses on the development and evaluation of so-called "closure methods" for solving the equations governing the time-dependent behaviour of single-server retrial queues. These methods involve assuming that particular known algebraic relationships between various characteristics of the corresponding steady-state queue also apply approximately when the queue is not at steady-state. The objective is to replace a problem requiring the solution of dozens or hundreds of simultaneous linear differential equations with a system of a few differential equations that has a solution that approximates those queue characteristics of immediate interest. The viability of such closure methods is assessed by examining the results of a series of test calculations. The methods described in this thesis apply to a retrial queue in which inter-arrival times for new customers, inter-retrial times, and service times are all assumed to be exponentially distributed. The steady-state solution for such a queue is described in some detail. A survey of the literature indicates that the description of this steady-state retrial queue has become quite sophisticated, whereas only very tentative steps have been taken in the study of the time-dependent behaviour of such queues. On the other hand, the time-dependent behaviour of the simple M/M/s queues have been studied to a much greater extent. The apparent value of closure methods in computing approximations to various basic time-dependent M/M/s queue characteristics motivated this examination of the extension of such methods to the single-server retrial queue. After discussing the basic approach to be used in devising and testing prospective closure methods for the single-server retrial queue, a variety of such methods is presented, with each being tested in considerable detail. It is found that three of the methods devised give results of comparable or better accuracy than those closure methods for the simple M/M/s queues which motivated this study. All recommended closure methods developed here involve systems of either two or three differential equations and permit the calculation of good approximations to four of the characteristics of greatest interest for non-stationary queues: the probability that the server is idle, the mean queue length, the variance of the queue length, and the conditional mean number of customers in the system given that the server is idle. Each of the methods presented is tested for queues with constant mean arrival, retrial and service rates, as well as for queues in which arrival and retrial rates vary sinusoidally with time.
A spectroscopic search for non-radial pulsations in the delta Scuti star gamma Bootis
Creators: name: Ventura, R.
name: Catanzaro, G.
name: Christensen-Dalsgaard, J.
name: Di Mauro, M. P.
name: Paterno', L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: High-resolution spectroscopic observations of the rapidly rotating delta Scuti star gamma Bootis have been carried out on 2005, over 6 consecutive nights, in order to search for line-profile variability. Time series, consisting of flux measurements at each wavelength bin across the TiII 4571.917 A line profile as a function of time, have been Fourier analyzed. The results confirm the early detection reported by Kennelly et al. (1992) of a dominant periodic component at frequency 21.28 c/d in the observer's frame, probably due to a high azimuthal order sectorial mode. Moreover, we found other periodicities at 5.06 c/d, 12.09 c/d, probably present but not secure, and at 11.70 c/d and 18.09 c/d, uncertain. The latter frequency, if present, should be identifiable as another high azimuthal order sectorial mode and three additional terms, probably due to low-l modes, as proved by the analysis of the first three moments of the line. Owing to the short time baseline and the one-site temporal sampling we consider our results only preliminary but encouraging for a more extensive multisite campaign. A refinement of the atmospheric physical parameters of the star has been obtained from our spectroscopic data and adopted for preliminary computations of evolutionary models of gamma Bootis.
description: 9 pages, 7 figures, to be published in MNRAS
title: Resilienz von service-orientierten und zeitkritischen Netzen
Creators: name: Ergenc, Doganalp
Publisher: name: Gesellschaft für Informatik e.V.
Year: 2024

description: Moderne Mission-critical Systeme (MCS) haben sich zu komplexen technologischen Ökosystemen, bestehend aus einer Vielzahl miteinander verbundener Dienste,
entwickelt. MCS müssen strenge Anforderungen an die Dienstgüte und die Resilienz gegenüber Ausfällen und Cyber-Angriffen erfüllen. Aufgrund mangelhafter Konfigurierbarkeit und Erweiterbarkeit können hier keine herkömmlichen System- und Netzwerktechnologien angewendet werden. Daher kommen in MCS mittlerweile verstärkt flexiblere Paradigmen wie Service-Orientierte Architekturen (SOA) und Time Sensitive Networking (TSN) zum Einsatz. In meiner Dissertation präsentiere ich mehrere Beiträge zur Entwicklung zukünftiger MCS auf der Basis von SOA und TSN. So stelle ich präsentiere Resilienzmechanismen zur Erhöhung von Autonomie, Fehlertoleranz und IT-Sicherheit vor, sowie weitere Lösungen um die optimale und zuverlässige Nutzung und Konfiguration der genannten Paradigmen zu behandeln.
Failure of the simultaneous block diagonalization technique applied to complete and cluster synchronization of random networks
Creators: name: Panahi, Shirin
name: Amaya, Nelson
name: Klickstein, Isaac
name: Novello, Galen
name: Sorrentino, Francesco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Systems and Control (eess.SY)
subject: FOS: Physical sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: We discuss here the application of the simultaneous block diagonalization (SBD) of matrices to the study of the stability of both complete and cluster synchronization in random (generic) networks. For both problems, we define indices that measure success (or failure) of application of the SBD technique in decoupling the stability problem into problems of lower dimensionality. We then see that in the case of random networks the extent of the dimensionality reduction achievable is the same as that produced by application of a trivial transformation.
description: Accepted for publication in PRE
A gradient system on the quantum information space that realizes the Karmarkar flow for linear programming
Creators: name: Uwano, Yoshio
name: Yuya, Hiromi
Publisher: name: arXiv
Year: 2008
Subjects: subject: Dynamical Systems (math.DS)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 53Z05, 37N99

description: In the paper of Uwano [Czech. J. of Phys., vol.56, pp.1311-1316 (2006)], a gradient system is found on the space of density matrices endowed with the quantum SLD Fisher metric (to be referred to as the quantum information space) that realizes a generalization of a gradient system on the space of multinomial distributions studied by Nakamura [Japan J. Indust. Appl. Math., vol.10, pp.179-189 (1993)]. On motived by those papers, the present paper aims to construct a gradient system on the quantum information space that realizes the Karmarkar flow, the continuous limit of the Karmarkar projective scaling algorithm for linear programming.
Hidden Vibronic and Excitonic Structure and Vibronic Coherence Transfer in the Bacterial Reaction Center
Creators: name: Policht, Veronica R.
name: Niedringhaus, Andrew
name: Willow, Rhiannon
name: Laible, Philip D.
name: Bocian, David F.
name: Kirmaier, Christine
name: Holten, Dewey
name: Mančal, Tomáš
name: Ogilvie, Jennifer P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: We report two-dimensional electronic spectroscopy (2DES) experiments on the bacterial reaction center (BRC) from purple bacteria, revealing hidden excitonic and vibronic structure. Through analysis of the coherent dynamics of the BRC we resolve specific coherent signatures that allow us to definitively assign the upper exciton energy of the "special pair." This assignment is supported by simulations of coherent dynamics of a reduced excitonic model of the BRC. The simulations also identify nonsecular vibronic coherence transfer processes neglected in standard models of photosynthetic energy transfer and charge separation. In addition, the coherent dynamics reveal multiple quasi-resonances between key intramolecular pigment vibrations and excited state energy gaps in the BRC. The functional significance of such electronic-vibrational resonances for photosynthetic energy transfer and charge separation remains an open question.
description: 23 pages, 5 figures, submitted to Nature Communications
Reflections on the photodissociation of CO in circumstellar envelopes
Creators: name: Groenewegen, Martin
name: Saberi, Maryam
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Carbon monoxide (CO) is the most abundant molecule after molecular hydrogen and is important for the chemistry in circumstellar envelopes around evolved stars. When modelling the strength and shape of molecular lines, the size of the CO envelope is an input parameter and influences the derived mass-loss rates. In particular the low-J transition CO lines are sensitive to the CO photodissociation radius. Recently, new CO photodissociation radii have been published using different formalisms that differ considerably. One set of calculations is based on an escape-probability formalisms that uses numerical approximations derived in the early-eighties. The accuracy of these approximations is investigated and it is shown that they are less accurate than claimed. Improved formalism are derived. Nevertheless, the changes in CO envelope size are small to moderate, less than 2\% for models with $10^{-7}< \dot{M}< 10^{-4}$ \msolyr\ and at most 7\% for model with $\dot{M} = 10^{-8}$ \msolyr.
description: A&A, accepted for publication
Some Entanglement Features of Highly Entangled Multiqubit States
Creators: name: Borras, A.
name: Casas, M.
name: Plastino, A. R.
name: Plastino, A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We explore some basic entanglement features of multiqubit systems that are relevant for the development of algorithms for searching highly entangled states. In particular, we compare the behaviours of multiqubit entanglement measures based (i) on the von Neumann entropy of marginal density matrices and (ii) on the linear entropy of those matrices.
description: To appear in the special issue of IJQI "Noise, Information and Complexity at Quantum Scale", eds. S. Mancini and F. Marchesoni (2008)
Do photosynthetic complexes use quantum coherence to increase their efficiency? Probably not
Creators: name: Zerah-Harush, Elinor
name: Dubi, Yonatan
Publisher: name: arXiv
Year: 2021
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Answering the titular question has become a central motivation in the field of quantum biology, ever since the idea was raised following a series of experiments demonstrating wave-like behavior in photosynthetic complexes. Here, we report a direct evaluation of the effect of quantum coherence on the efficiency of three natural complexes. An open quantum systems approach allows us to simultaneously identify their level of "quantumness" and efficiency, under natural physiological conditions. We show that these systems reside in a mixed quantum-classical regime, characterized by dephasing-assisted transport. Yet, we find that the change in efficiency at this regime is minute at best, implying that the presence of quantum coherence does not play a significant role in enhancing efficiency. However, in this regime efficiency is independent of any structural parameters, suggesting that evolution may have driven natural complexes to their parameter regime in order to "design" their structure for other uses.
description: Science Advances 17 Feb 2021. https://advances.sciencemag.org/content/7/8/eabc4631
From multiplicative unitaries to quantum groups II
Creators: name: Sołtan, Piotr M.
name: Woronowicz, S. L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 46L89, 58B32, 22D25

description: It is shown that all important features of a $\mathrm{C}^*$-algebraic quantum group $(A,Δ)$ defined by a modular multiplicative $W$ depend only on the pair $(A,Δ)$ rather than the multiplicative unitary operator $W$. The proof is based on thorough study of representations of quantum groups. As an application we present a construction and study properties of the universal dual of a quantum group defined by a modular multiplicative unitary - without assuming existence of Haar weights.
description: 19 pages, LaTeX
title: Evolutionäre Multikriterielle Optimierung von Pfadsuchproblemen
Creators: name: Weise, Jens
Publisher: name: Gesellschaft für Informatik e.V.
Year: 2024

description: Diese Arbeit befasst sich mit den Herausforderungen der multikriteriellen Pfadsuche in
verschiedenen Bereichen. Entscheidungsträger müssen mehrere Ziele miteinander in Einklang bringen,
was zu großen Suchräumen führt. Während klassische Optimierungsansätze zeitaufwändig sind,
bieten Metaheuristiken wie evolutionäre Algorithmen schnellere Lösungen. In dieser Arbeit werden
Methoden zur Erzeugung skalierbarer Pfadfindungs-Benchmarks und zur Optimierung des Prozesses
für eine verbesserte Lösungsqualität vorgestellt. Die Ergebnisse zeigen, dass sich die Qualität der
Lösungen verbessert hat. Darüber hinaus werden die Herausforderungen von Entscheidungsträgern bei
der Auswahl einer Lösung aus Pareto-optimalen Alternativen angesprochen und Ansätze vorgeschlagen,
die die Entscheidungsfindung in der Praxis unterstützen.
D2 to M2 Procedure for D2-Brane DBI Effective Action
Creators: name: Kluson, J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We apply the procedure that was suggested in [arXiv:0806.1639] to the case of abelian D2-brane Dirac-Born-Infeld effective action and discuss its limitation. Then we suggest an alternative form of this procedure that is based on an existence of interpolating action proposed in [hep-th/9707113,hep-th/9707011].
description: 15 pages, typos corrected, references added
title: Über die Vertrauenswürdigkeit digitaler Beweismittel und wie diese etabliert werden kann
Creators: name: Schneider, Janine
Publisher: name: Gesellschaft für Informatik e.V.
Year: 2024

description: Digitale Beweismittel können an Vertrauenswürdigkeit verlieren, wenn bestimmte Eigenschaften nicht mehr gegeben sind. Ist beispielsweise die Herkunft eines Beweismittels nicht nachvollziehbar oder der Prozess der Beweismittelerhebung intransparent, kann die Vertrauenswürdigkeit leiden. Digitale Beweismittel können zudem an Vertrauenswürdigkeit verlieren, wenn die Beweismittel durch Manipulation (ganz oder teilweise) unzuverlässig werden. In dieser Arbeit untersuchen wir deshalb, welche Anforderungen erfüllt sein müssen, um vertrauenswürdige Beweismittel zu erhalten, wann diese Anforderungen nicht mehr erfüllt sind und wie vertrauensbildende Maßnahmen aussehen können. Konkret untersuchen wir, wie digitale Beweismittel (unbemerkt) manipuliert werden können, wie sich mehrdeutige Datenstrukturen auf digital-forensische Analysen auswirken und welche Auswirkungen NAND-Flash Chip Recycling auf die Vertrauenswürdigkeit hat. Darüber hinaus schaffen wir Vertrauen, indem wir vertrauensbildende Merkmale in den Prozess der digital-forensischen Analyse integrieren.
Adaptive optics imaging and optical spectroscopy of a multiple merger in a luminous infrared galaxy
Creators: name: Vaisanen, P.
name: Mattila, S.
name: Kniazev, A.
name: Adamo, A.
name: Efstathiou, A.
name: Farrah, D.
name: Johansson, P. H.
name: Ostlin, G.
name: Buckley, D. A. H.
name: Burgh, E. B.
name: Crause, L.
name: Hashimoto, Y.
name: Lira, P.
name: Loaring, N.
name: Nordsieck, K.
name: Romero-Colmenero, E.
name: Ryder, S.
name: Still, M.
name: Zijlstra, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: (abridged) We present near-infrared (NIR) adaptive optics imaging obtained with VLT/NACO and optical spectroscopy from the Southern African Large Telescope (SALT) of a luminous infrared galaxy (LIRG) IRAS 19115-2124. These data are combined with archival HST imaging and Spitzer imaging and spectroscopy, allowing us to study this disturbed interacting/merging galaxy, dubbed the Bird, in extraordinary detail. In particular, the data reveal a triple system where the LIRG phenomenon is dominated by the smallest of the components. One nucleus is a regular barred spiral with significant rotation, while another is highly disturbed with a surface brightness distribution intermediate to that of disk and bulge systems, and hints of remaining arm/bar structure. We derive dynamical masses in the range 3-7x10^10 M_solar for both. The third component appears to be a 1-2x10^10 M_solar mass irregular galaxy. The total system exhibits HII galaxy-like optical line ratios and strengths, and no evidence for AGN activity is found from optical or mid-infrared data. The star formation rate is estimated to be 190 M_solar/yr. We search for SNe, super star clusters, and detect 100-300 km/s outflowing gas from the Bird. Overall, the Bird shows kinematic, dynamical, and emission line properties typical for cool ultra luminous IR galaxies. However, the interesting features setting it apart for future studies are its triple merger nature, and the location of its star formation peak - the strongest star formation does not come from the two major K-band nuclei, but from the third irregular component. Aided by simulations, we discuss scenarios where the irregular component is on its first high-speed encounter with the more massive components.
description: 24 pages, 16 figures. Accepted MNRAS version, minor corrections only, references added. Higher resolution version (1.3MB) is available from http://www.saao.ac.za/~petri/bird/ulirg_bird_highres_vaisanen_v2.pdf
The dynamical state of A548 from XMM-Newton data: X-ray and radio connection
Creators: name: Solovyeva, L.
name: Anokhin, S.
name: Feretti, L.
name: Sauvageot, J. L.
name: Teyssier, R.
name: Giovannini, G.
name: Govoni, F.
name: Neumann, D.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present a detailed study of the X-ray properties of the galaxy cluster Abell 548b (z=0.04), using XMM-Newton data, and discuss the connection between the thermal properties and the presence of two extended relic radio sources located at the cluster periphery. We wish to analyze the dynamical state of the cluster and confirm the presence of a major merger. We will discuss the merger effects on the extended nonthermal emission. From the analysis of the temperature distribution and of the surface brightness profiles, we find evidence of a shock in the northern cluster region, just before the location of the two extended peripheral relics. From the optical analysis, we find that the cluster galaxies show a large $σ_V$, and two components are needed to fit their velocity distribution. Observational results were compared with a cluster simulation. The maps of gas temperature and density distribution from the simulation agree with the observational data in the case of a cluster merger nearly perpendicular to the plane of the sky and in the state after the maximum core collapse. We conclude that we are observing a galaxy cluster in a major merger phase, just after the maximum core collapse. The mass ratio is about 1:2, and the merger collision is nearly perpendicular to the plane of the sky. A shock is present in the northern cluster region, and it is very likely responsible for the electron reacceleration and the magnetic field amplification that will give cause the cluster relics. The relative position of the shock and the relics is strongly affected by projection effects.
description: A&A, accepted March 20, 2008, (better quality of figures you can look in A&A after publication)
The Millennium Galaxy Catalogue: The connection between close pairs and asymmetry; implications for the galaxy merger rate
Creators: name: De Propris, R.
name: Conselice, C. J.
name: Driver, S. P.
name: Liske, J.
name: Patton, D.
name: Graham, A.
name: Allen, P.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We compare the use of galaxy asymmetry and pair proximity for measuring galaxy merger fractions and rates for a volume limited sample of 3184 galaxies with -21 < M(B) -5 log h < -18 mag. and 0.010 < z < 0.123 drawn from the Millennium Galaxy Catalogue. Our findings are that: (i) Galaxies in close pairs are generally more asymmetric than isolated galaxies and the degree of asymmetry increases for closer pairs. At least 35% of close pairs (with projected separation of less than 20 h^{-1} kpc and velocity difference of less than 500 km s^{-1}) show significant asymmetry and are therefore likely to be physically bound. (ii) Among asymmetric galaxies, we find that at least 80% are either interacting systems or merger remnants. However, a significant fraction of galaxies initially identified as asymmetric are contaminated by nearby stars or are fragmented by the source extraction algorithm. Merger rates calculated via asymmetry indices need careful attention in order to remove the above sources of contamination, but are very reliable once this is carried out. (iii) Close pairs and asymmetries represent two complementary methods of measuring the merger rate. Galaxies in close pairs identify future mergers, occurring within the dynamical friction timescale, while asymmetries are sensitive to the immediate pre-merger phase and identify remnants. (iv) The merger fraction derived via the close pair fraction and asymmetries is about 2% for a merger rate of (5.2 +- 1.0) 10^{-4} h^3 Mpc^{-3} Gyr^{-1}. These results are marginally consistent with theoretical simulations (depending on the merger time-scale), but imply a flat evolution of the merger rate with redshift up to z ~1.
description: 10 pages, 10 figures, emulateapj format. ApJ, accepted
A geometric approach to evaluation-transversality techniques in generic bifurcation theory
Creators: name: Aalto, Søren Karl
Publisher: name: University of British Columbia
Year: 2010

description: The study of bifurcations of vectorfields is concerned with changes in qualitative behaviour that can occur when a non-structurally stable vectorfield is perturbed. In a sense, this is the study of how such a vectorfield fails to be structurally stable. Finding a systematic approach to the study of such questions is a difficult problem. One approach to bifurcations of vectorfields, known as "generic bifurcation theory," is the subject of much of the work of Sotomayor (Sotomayor [1973a], Sotomayor [1973b],Sotomayor [1974]). This approach attempts to construct generic families of k-parameter vectorfields (usually for k=1), for which all the bifurcations can be described. In Sotomayor [1973a] it is stated that the vectorfields associated with the "generic" bifurcations of individual critical elements for k-parameter vectorfields form submanifolds of codimension ≤ k of the Banach space ϰʳ (M) of vectorfields on a compact manifold M. The bifurcations associated with one of these submanifolds of codimension-k are called generic codimension-k bifurcations. In Sotomayor [1974] the construction of these submanifolds and the description of the associated bifurcations of codimension-1 for vectorfields on two dimensional manifolds is presented in detail. The bifurcations that occur are due to the parameterised vectorfield crossing one of these manifolds transversely as the parameter changes. Abraham and Robbin used transversality results for evaluation maps to prove the Kupka-Smale theorem in Abraham and Robbin [1967]. In this thesis, we shall show how an extension of these evaluation transversality techniques will allow us to construct the submanifolds of ϰʳ (M) associated with one type of generic bifurcation of critical elements, and we shall consider how this approach might be extended to include the other well known generic bifurcations. For saddle-node type bifurcations of critical points, we will show that the changes in qualitative behaviour are related to geometric properties of the submanifold Σ₀ of ϰʳ (M) x M, where Σ₀ is the pull-back of the set of zero vectors-or zero section-by the evaluation map for vectorfields. We will look at the relationship between the Taylor series of a vector-field X at a critical point ⍴ and the geometry of Σ₀ at the corresponding point (X,⍴) of ϰʳ (M) x M. This will motivate the non-degeneracy conditions for the saddle-node bifurcations, and will provide a more general geometric picture of this approach to studying bifurcations of critical points. Finally, we shall consider how this approach might be generalised to include other bifurcations of critical elements.
The impact of social media presence and board member composition on new venture success: Evidences from VC-backed U.S. startups
Creators: name: Gloor, P. A.
name: Colladon, A. Fronzetti
name: Grippa, F.
name: Hadley, B. M.
name: Woerner, S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Social and Information Networks (cs.SI)
subject: General Economics (econ.GN)
subject: FOS: Computer and information sciences
subject: FOS: Economics and business
subject: J.4; H.4.0

description: The purpose of this study is to examine the impact of board member composition and board members' social media presence on the performance of startups. Using multiple sources, we compile a unique dataset of about 500 US-based technology startups. We find that startups with more venture capitalists on the board and whose board members are active on Twitter attract additional funding over the years, though they do not generate additional sales. By contrast, startups which have no venture capitalists on the board and whose board members are not on Twitter show an increased ability to translate assets into sales. Consistent with other research, our results indicate that startups potentially benefit from working with VCs because of the opportunity to access additional funding, although their presence does not necessarily translate into sales growth and operational efficiency. We use a number of control variables, including board gender representation and board members' position in the interlocking directorates' network.
Preliminary optical design of PANIC, a wide-field infrared camera for CAHA
Creators: name: Cardenas, M. C.
name: Gomez, J. Rodriguez
name: Lenzen, R.
name: Sanchez-Blanco, E.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: In this paper, we present the preliminary optical design of PANIC (PAnoramic Near Infrared camera for Calar Alto), a wide-field infrared imager for the Calar Alto 2.2 m telescope. The camera optical design is a folded single optical train that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 micron pixel. A mosaic of four Hawaii 2RG of 2k x 2k made by Teledyne is used as detector and will give a field of view of 31.9 arcmin x 31.9 arcmin. This cryogenic instrument has been optimized for the Y, J, H and K bands. Special care has been taken in the selection of the standard IR materials used for the optics in order to maximize the instrument throughput and to include the z band. The main challenges of this design are: to produce a well defined internal pupil which allows reducing the thermal background by a cryogenic pupil stop; the correction of off-axis aberrations due to the large field available; the correction of chromatic aberration because of the wide spectral coverage; and the capability of introduction of narrow band filters (~1%) in the system minimizing the degradation in the filter passband without a collimated stage in the camera. We show the optomechanical error budget and compensation strategy that allows our as built design to met the performances from an optical point of view. Finally, we demonstrate the flexibility of the design showing the performances of PANIC at the CAHA 3.5m telescope.
description: This paper has been presented in the SPIE of Astronomical Telescopes and Instrumentation 2008 in Marseille (France)