cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The catabolism of the last two rings of cholesterol by Mycobacterium tuberculosis
Creators: name: Crowe, Adam Michael
Publisher: name: University of British Columbia
Year: 2018

description: Cholesterol, a four-ringed steroid with an alkyl side chain, is an important growth substrate for Mycobacterium tuberculosis (Mtb) during infection. Many aspects of this catabolism remain unknown although steroid catabolism is a defining feature of mycobacteria and the related rhodococci. Using a variety of approaches, I elucidated key aspects of cholesterol catabolism in Mtb and other bacteria, particularly with respect to 3aα-H-4α(3'-propanoate)-7aβ-methylhexahydro-1,5-indane-dione (HIP), a metabolite that contains the last two steroid rings (C/D). Chapter 2 demonstrates that the first two steroid rings (A/B) are degraded prior to the side chain in mycobacteria and rhodococci. This was established by targeting HsaD, the final ings A/B-degrading enzyme. Thus, a ΔhsaD mutant of Rhodococcus jostii RHA1 accumulated cholesterol-derived catabolites with partially degraded side-chains. Moreover, HsaD from Mtb had 100-fold higher specificity (kcat/KM) for a metabolite with a partially-degraded side chain. Chapter 3 presents a mechanism for KstR2, a TetR family transcriptional repressor that regulates the HIP catabolic genes, including ipdABCF and echA20. The KstR2 dimer bound two equivalents of HIP-CoA with high affinity (KD = 80±10 nM). Crystallographic analyses revealed that HIP-CoA binding induces conformational changes in the dimer that preclude DNA-binding. Mutagenesis substantiated the roles of Arg162 and Trp166 in HIP-CoA binding. In Chapter 4, key HIP catabolic steps are elucidated. Two previously undescribed metabolites, 3aα-H-4α(carboxyl-CoA)-5-hydroxy-7aβ-methylhexahydro-1-indanone (5-OH-HIC-CoA) and (R)-2-(2-carboxyethyl)-3-methyl-6-oxocyclohex-1-ene-1-carboxyl-CoA (COCHEA-CoA) were identified using deletion mutants of ipdC and ipdAB, respectively, combined with novel metabolomics approaches. Together, purified IpdC, IpdF and EchA20 transformed 5-OH-HIC-CoA to COCHEA-CoA. These data, along with those from additional mutants, were used to formulate a HIP catabolic pathway and to predict that cholesterol catabolism yields four propionyl-CoA, four acetyl-CoA, one pyruvate, and one succinate. Chapter 5 establishes that IpdAB catalyzes a retro-Claisen-like ring-opening of COCHEA-CoA (kcat/KM = 2±0.7 × 10⁵ M⁻¹s⁻¹) despite structural similarity with Class I CoA transferases. Based on crystal structures of IpdAB and biochemical data, a mechanism for ring-cleavage is proposed in which conserved Glu105 acts as a catalytic base. Overall, this work significantly advances our understanding of bacterial steroid catabolism and facilitates the development of novel therapeutics to treat TB.
InTaVia/idm-rdf: v0.4-alpha: Release for internal discussion
Creators: name: Ebel, Carla
name: Schlögl, Matthias
name: Touminen, Jouni
name: De Boer, Victor
Publisher: name: Zenodo
Year: 2021

description: The core of the data model (Biographies and Cultural Heritage objects) is included in this release. For a detailed description please check the updated README.md. added CHO Proxy Properties (largely mapped to EDM and IDM-json) updated data properties according to Cidoc CRM 7.1.1. to come stringent modeling of the relations between Cidoc CRM and EDM classes (now modeled with equivalent to to show the intersection between Cidoc and EDM) append classes and properties for the CHO's media files and their digital rights (see issues) add bibliographic source modeling (bibliographic named graph, see issues) add model for provenance graph (PROV-O) add preliminary model for NLP data
Midinfrared intersubband electroluminescence of Si/SiGe quantum cascade structures
Creators: name: Bormann, I.
name: Brunner, K.
name: Hackenbuchner, S.
name: Zandler, G.
name: Abstreiter, Gerhard
name: Schmult, Stefan
name: Wegscheider, Werner
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 530 Physik

description: Unipolar intersubband lasers like quantum cascade laser structures might be realized not only in III–V semiconductors but also in Si/SiGe multiple layer structures since no optical transitions across the indirect band gap are involved. We report on well-defined intersubband electroluminescence emission of Si/SiGe quantum cascade structures with different active quantum wells parameters. The complex valence band structure and a nonradiative relaxation rate of about 400 fs were calculated by multiband k·p formalism including Si/Ge segregation effects. The observed spectral shift of the electroluminescence peak from 146 to 159 meV is described well by quantum confinement of the two lowest heavy hole subbands. The electroluminescence observed reveals transverse magnetic polarization, a spectral line shape that changes with the direction of the current, and low-energy line broadening with an increase in temperature and current. All these features are described well by the k·p model calculation.
InTaVia/idm-rdf: v0.5: Beta release for IDM-RDF
Creators: name: Ebel, Carla
name: Schlögl, Matthias
name: Touminen, Jouni
name: De Boer, Victor
Publisher: name: Zenodo
Year: 2022

description: The core of the data model (Biographies and Cultural Heritage objects) is included in this release. For a detailed description please check the updated README.md. added correct domains and ranges for bio-crm classes CHO_Proxy for CHO data added proxies for persons and groups added more CRM classes for CHO objects made bio-crm classes superclasses of IDM classes added E24_Physical_Human-Made_Thing instead of E18 added P82a/b and set the range to xsd:dateTime added joining and leaving events for groups and minor fixes
Diophantine tori and Weyl laws for non-selfadjoint operators in dimension two
Creators: name: Hitrik, Michael
name: Sjoestrand, Johannes
Publisher: name: arXiv
Year: 2011
Subjects: subject: Spectral Theory (math.SP)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 35P15, 35P20, 37J35, 37J40, 47A55, 53D22, 58J37, 58J40

description: We study the distribution of eigenvalues for non-selfadjoint perturbations of selfadjoint semiclassical analytic pseudodifferential operators in dimension two, assuming that the classical flow of the unperturbed part is completely integrable. An asymptotic formula of Weyl type for the number of eigenvalues in a spectral band, bounded from above and from below by levels corresponding to Diophantine invariant Lagrangian tori, is established. The Weyl law is given in terms of the long time averages of the leading non-selfadjoint perturbation along the classical flow of the unperturbed part.
Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor
Creators: name: Smet, J. H.
name: Deutschmann, R. A.
name: Ertl, F.
name: Wegscheider, Werner
name: Abstreiter, Gerhard
name: Klitzing, Klaus von
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 530 Physik

description: Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for both information processing and the study of fundamental solid-state physics issues. Here we report procedures that carry out the controlled transfer of spin angular momentum between electrons—confined to two dimensions and subjected to a perpendicular magnetic field—and the nuclei of the host semiconductor, using gate voltages only. We show that the spin transfer rate can be enhanced near a ferromagnetic ground state of the electron system, and that the induced nuclear spin polarization can be subsequently stored and 'read out'. These techniques can also be combined into a spectroscopic tool to detect the low-energy collective excitations in the electron system that promote the spin transfer. The existence of such excitations is contingent on appropriate electron–electron correlations, and these can be tuned by changing, for example, the electron density via a gate voltage.
Número de Ramsey multipartido para grafos bipartidos
Creators: name: Perondi, Pablo Henrique
Publisher: name: Zenodo
Year: 2019

description: Abordaremos a versão multipartida do número de Ramsey no caso onde os

grafos monocromáticos requisitados são bipartidos. Neste sentido, usare-

mos argumentos de densidade para apresentaremos um limite superior que

generaliza resultados clássicos de Chung, Graham e Irving. Além disso, usa-

remos grafos fortemente regulares e matrizes de Hadamard para construir

um limitante inferior que estende a construção feita por Exoo, Harborth e

Mengersen.
Soluble Interleukin-2 Receptors Inhibit Interleukin 2-Dependent Proliferation and Cytotoxicity: Explanation for Diminished Natural Killer Cell Activity in Cutaneous T-Cell Lymphomas In Vivo?
Creators: name: Dummer, Reinhard
name: Posseckert, Gerhard
name: Nestle, Frank
name: Witzgall, Ralph
name: Burger, Mathias
name: Becker, Jürgen C.
name: Schäfer, Erwin
name: Wiede, Johannes
name: Sebald, Walter
name: Burg, Günter
Publisher: name: Universität Regensburg
Year: 1992
Subjects: subject: 610 Medizin

description: In patients with cutaneous T-cell lymphomas (CTCL), soluble interleukin-2 receptor serum levels (sIL-2R) were determined by ELISA technique, and natural killer cell (NK) activity, by a 4-h chromium-51 release assay. Decrease of NK activity correlated with the augmentation of serum sIL-2R. After a 4-d stimulation with interleukin 2 CTCL patients' peripheral mononuclear cells (PMC) showed an increase of cytotoxic activity similar to that in healthy donors' PMC. Normal donors' PMC demonstrated a diminished IL-2-induced cytotoxic activity in 25% CTCL serum (sIL-2R of 3000, 7330, and 10700 U/mI, respectively) compared to control serum (sIL-2R of 400, 340, and 420 U/ml, respectively). IL-2-dependent proliferation of 2-d phytohemagglutinin (PHA) blasts was lower in CTCL serum than in control serum. sIL-2R was enriched from one CTCL patient's serum by IL-2 affinity chromatography. Transfection of the Tac gene into NIH/3T3 fibroblasts resulted in the production of a recombinant sIL-2R. The presence Of enriched native or recombinant slL-2R inhibited interleukin-2-dependent generation of cytotoxic activity and PHA blast proliferation. We suggest that elevated sIL- 2R levels account for diminished NK activity by neutralizing iriterleukin 2 in CTCL patients.
Relations among characteristic classes and existence of singular maps
Creators: name: Kalmar, Boldizsar
name: Terpai, Tamas
Publisher: name: arXiv
Year: 2010
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57R45 (Primary) 57R75 (Secondary) 57R25, 57R20

description: We obtain relations among the characteristic classes of a manifold M admitting corank one maps. Our relations yield strong restrictions on the cobordism class of M and also nonexistence results for singular maps of the projective spaces. We obtain our results through blowing up a manifold along the singular set of a smooth map and perturbing the arising non-generic corank one map.
description: 25 pages
Unravelling the typicity of 17 rum terroirs by GC-FID and aroma compound mapping
Creators: name: Malfondet, Nicolas
name: Thibaud, Fannie
name: Gabriel, Alexandre
Publisher: name: Zenodo
Year: 2022
Subjects: rum
terroir
typicity
GC-FID
aroma compound mapping

description: The flavour composition of a large number of rum samples coming from different terroirs has been analysed by GC-FID. A graph (called the “aroma compound mapping”) has been drawn using the quantitative data of esters and higher alcohols contained in the rums. The samples plotted on the mapping allow to explain the differences in their making processes, which symbolises the typicity of each rum terroir. This methodology represents a useful tool to highlight and better understand the specificities of rum production among the terroirs and their impact in the flavour composition of the final product.
Electronic properties of antidot lattices fabricated by atomic force lithography
Creators: name: Dorn, A.
name: Sigrist, Martin
name: Fuhrer, A.
name: Ihn, Thomas
name: Ensslin, Klaus
name: Wegscheider, Werner
name: Bichler, Max
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 530 Physik

description: Antidot lattices were fabricated by atomic force lithography using local oxidation. High quality finite 20×20 lattices are demonstrated with periods of 300 nm. The low-temperature magnetoresistance shows well developed commensurability oscillations as well as a quenching of the Hall effect around zero magnetic field. In addition, we find B-periodic oscillations superimposed on the classical commensurability peaks at temperatures as high as 1.7 K. These observations indicate the high electronic quality of our samples.
Minimum-error discrimination of entangled quantum states
Creators: name: Lu, Yang
name: Coish, Nick
name: Kaltenbaek, Rainer
name: Hamel, Deny R.
name: Croke, Sarah
name: Resch, Kevin J.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Strategies to optimally discriminate between quantum states are critical in quantum technologies. We present an experimental demonstration of minimum error discrimination between entangled states, encoded in the polarization of pairs of photons. Although the optimal measurement involves projecting onto entangled states, we use a result of Walgate et al. to design an optical implementation employing only local polarization measurements and feed-forward, which performs at the Helstrom bound. Our scheme can achieve perfect discrimination of orthogonal states and minimum error discrimination of non-orthogonal states. Our experimental results show a definite advantage over schemes not using feed-forward.
description: 4 pages, 4 figures
Mapped Karst Groundwater Basins in the Tell City and Part of the Jasper 30 x 60 Minute Quadrangles
Creators: name: Ray, Joseph A.
name: Moody, Jack R.
name: Blair, Robert J.
name: Currens, James C.
name: Paylor, Randall L.
Publisher: name: Kentucky Geological Survey, University of Kentucky
Year: 2009

description: Copyright:
Symmetric and asymmetric solitons and vortices in linearly coupled two-dimensional waveguides with the cubic-quintic nonlinearity
Creators: name: Dror, Nir
name: Malomed, Boris A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: It is well known that the two-dimensional (2D) nonlinear Schrödinger equation (NLSE) with the cubic-quintic (CQ) nonlinearity supports a family of stable fundamental solitons, as well as solitary vortices (alias vortex rings), which are stable for sufficiently large values of the norm. We study stationary localized modes in a symmetric linearly coupled system of two such equations, focusing on asymmetric states. The model may describe "optical bullets" in dual-core nonlinear optical waveguides (including spatiotemporal vortices that were not discussed before), or a Bose-Einstein condensate (BEC) loaded into a "dual-pancake" trap. Each family of solutions in the single-component model has two different counterparts in the coupled system, one symmetric and one asymmetric. Similarly to the earlier studied coupled 1D system with the CQ nonlinearity, the present model features bifurcation loops, for fundamental and vortex solitons alike: with the increase of the total energy (norm), the symmetric solitons become unstable at a point of the direct bifurcation, which is followed, at larger values of the energy, by the reverse bifurcation restabilizing the symmetric solitons. However, on the contrary to the 1D system, the system may demonstrate a double bistability for the fundamental solitons. The stability of the solitons is investigated via the computation of instability growth rates for small perturbations. Vortex rings, which we study for two values of the "spin", s = 1 and 2, may be subject to the azimuthal instability, like in the single-component model. We also develop a quasi-analytical approach to the description of the bifurcations diagrams, based on the variational approximation. Splitting of asymmetric vortices, induced by the azimuthal instability, is studied by means of direct simulations. Interactions between initially quiescent solitons of different types are studied too.
description: Physica D, in press
Characterising the Structural and Mechanical Properties of a Cargo Encapsulating DNA Origami Nanostructure Using oxDNA
Creators: name: Hello World
Publisher: name: Zenodo
Year: 2019

description: Within this repository are the input and output files that were obtained when the lid and box structures of an encapsulating DNA origami nanostructure were simulated using oxDNA to characterise their structural and mechanical properties. Information on the specifics of the steps that we took are included in the 'readme.rtf' file.
Fantasies
Creators: name: Kuo, Chia Lin
Publisher: name: University of British Columbia
Year: 2018

description: "Fantasies" is a sixteen-minute suite for a chamber ensemble that includes eight performers: flute, clarinet, two percussionists, harp, piano, violin, and cello. The work consists of five movements and contains various melodic themes and thematic material. Motivic development is the most important compositional approach that I have applied in this work. In the second and third movements, the initial motives are modified by the motivic fragmentations, and transformed into the new melodies. The dissertation is divided into five chapters. The first chapter offers a basic overview of the piece, my personal inspiration, and other musical influences that led to the composition. The second, third, and four chapters provide a comprehensive analysis of the entire piece. Concluding remarks are made in the fifth chapter, including philosophical and aesthetic associations.
In-Orbit Performance of MAXI Gas Slit Camera (GSC) on ISS
Creators: name: Sugizaki, Mutsumi
name: Mihara, Tatehiro
name: Serino, Motoko
name: Yamamoto, Takayuki
name: Matsuoka, Masaru
name: Kohama, Mitsuhiro
name: Tomida, Hiroshi
name: Ueno, Shiro
name: Kawai, Nobuyuki
name: Morii, Mikio
name: Sugimori, Kousuke
name: Nakahira, Satoshi
name: Yamaoka, Kazutaka
name: Yoshida, Atsumasa
name: Nakajima, Motoki
name: Negoro, Hitoshi
name: Eguchi, Satoshi
name: Isobe, Naoki
name: Ueda, Yoshihiro
name: Tsunemi, Hiroshi
Publisher: name: arXiv
Year: 2011
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report the in-orbit performance of the Gas Slit Camera (GSC) on the MAXI (Monitor of All-sky X-ray Image) mission carried on the International Space Station (ISS). Its commissioning operation started on August 8, 2009, confirmed the basic performances of the effective area in the energy band of 2--30 keV, the spatial resolution of the slit-and-slat collimator and detector with 1.5 degree FWHM, the source visibility of 40-150 seconds for each scan cycle, and the sky coverage of 85% per 92-minute orbital period and 95% per day. The gas gains and read-out amplifier gains have been stable within 1%. The background rate is consistent with the past X-ray experiments operated at the similar low-earth orbit if its relation with the geomagnetic cutoff rigidity is extrapolated to the high latitude. We also present the status of the in-orbit operation and the calibration of the effective area and the energy response matrix using Crab-nebula data.
description: 11 pages, 14 figures, accepted for publication in PASJ
Cyclotron resonance of composite fermions
Creators: name: Kukushkin, I.
name: Smet, J. H.
name: Wegscheider, Werner
name: Klitzing, Klaus von
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 530 Physik

description: It is occasionally possible to interpret strongly interacting many-body systems within a single-particle framework by introducing suitable fictitious entities, or 'quasi-particles'. A notable recent example of the successful application of such an approach is for a two-dimensional electron system that is exposed to a strong perpendicular magnetic field. The conduction properties of the system are governed by electron–electron interactions, which cause the fractional quantum Hall effect1. Composite fermions, electrons that are dressed with magnetic flux quanta pointing opposite to the applied magnetic field, were identified as apposite quasi-particles that simplify our understanding of the fractional quantum Hall effect2, 3. They precess, like electrons, along circular cyclotron orbits, but with a diameter determined by a reduced effective magnetic field4, 5, 6, 7, 8, 9, 10. The frequency of their cyclotron motion has hitherto remained enigmatic, as the effective mass is no longer related to the band mass of the original electrons and is entirely generated from electron–electron interactions. Here we demonstrate enhanced absorption of a microwave field in the composite fermion regime, and interpret it as a resonance with the frequency of their circular motion. From this inferred cyclotron resonance, we derive a composite fermion effective mass that varies from 0.7 to 1.2 times that of the electron mass in vacuum as their density is tuned from 0.6 times 1011 cm-2 to 1.2 times 1011 cm-2.
Updated constraints on the cosmic string tension
Creators: name: Battye, Richard
name: Moss, Adam
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We re-examine the constraints on the cosmic string tension from Cosmic Microwave Background (CMB) and matter power spectra, and also from limits on a stochastic background of gravitational waves provided by pulsar timing. We discuss the different approaches to modeling string evolution and radiation. In particular, we show that the unconnected segment model can describe CMB spectra expected from thin string (Nambu) and field theory (Abelian-Higgs) simulations using the computed values for the correlation length, rms string velocity and small-scale structure relevant to each variety of simulation. Applying the computed spectra in a fit to CMB and SDSS data we find that $Gμ/c^2< 2.6\times 10^{-7}$ ($2 σ$) if the Nambu simulations are correct and $Gμ/c^2< 6.4\times 10^{-7}$ in the Abelian-Higgs case. The degeneracy between $Gμ/c^2$ and the power spectrum slope $n_{\rm S}$ is substantially reduced from previous work. Inclusion of constraints on the baryon density from Big Bang Nucleosynthesis (BBN) imply that $n_{\rm S} <1$ at around the $4σ$ level for both the Nambu and Abelian-Higgs cases. As a by-product of our results, we find there is "moderate-to-strong" Bayesian evidence that the Harrison-Zel'dovich spectrum is excluded (odds ratio of $\sim 100:1$) by the combination of CMB, SDSS and BBN when compared to the standard 6 parameter fit. Using the contribution to the gravitational wave background from radiation era loops as a conservative lower bound on the signal for specific values of $Gμ/c^2$ and loop production size, $α$, we find that $Gμ/c^2< 7\times 10^{-7} $ for $αc^2/(ΓGμ)\ll1$ and $Gμ/c^2 < 5\times 10^{-11}/α$ for $αc^2/(ΓGμ) \gg1$.
description: 12 pages, 6 figures, original submission was not final version and contained some minor errors which was submitted by accident
Unterstützungsbedarf und Möglichkeiten der (Selbst-)Hilfe erwachsener Kinder unipolar und bipolar affektiv Erkrankter
Creators: name: Schmid, Rita
name: Helmbrecht, Marina J.
name: Lukesch, Helmut
name: Spiessl, Hermann
Publisher: name: Universität Regensburg
Year: 2009
Subjects: subject: 150 Psychologie

description: Der Unterstützungsbedarf ist auch bei erwachsenen Kindern affektiv Erkrankter groß (vgl. zusammenfassende Tabelle 3), jedoch können sie - anders als minderjährige Kinder – meist leichter zur Selbsthilfe befähigt werden. Professionelle Unterstützungsprogramme sollten möglichst niederschwellig angelegt sein, um weitere Stigmatisierung und Ausgrenzungen zu vermeiden. Die Angebote sollten einerseits über die Erkrankung aufklären und Tipps zum Umgang mit dem Erkrankten vermitteln sowie die Kinder von ihren vielfältigen emotionalen Belastungen entlasten. Die Programme sollten ferner insbesondere die erwachsenen Kinder im Sinne der Selbsthilfe anleiten, achtsam und selbstbewusst ihre eigenen Ressourcen und familiären Unterstützungssysteme zur Krankheitsbewältigung zu nützen.
Nonlinear optical response of highly energetic excitons in GaAs: Microscopic electrodynamics at semiconductor interfaces
Creators: name: Betz, M.
name: Göger, G.
name: Leitenstorfer, A.
name: Bichler, Max
name: Wegscheider, Werner
name: Abstreiter, Gerhard
Publisher: name: Universität Regensburg
Year: 2002
Subjects: subject: 530 Physik
subject: 71.35.Cc, 71.36.+c, 72.15.Lh, 78.47.+p

description: A spectroscopic investigation of bound electron-hole pairs in GaAs propagating with large center-of-mass momentum is presented. The approach is based on transmission experiments exploiting the coupling of excitonic polarization to the electromagnetic field of femtosecond laser pulses. The dispersion relations of the coherent excitations are determined up to excess energies of 300 meV above the band edge. A surprisingly low Fröhlich coupling of light-hole excitons is observed in excellent agreement with theoretical simulations. The influence of different phonon scattering processes on the excitonic damping is discussed. The interaction dynamics of excitonic wave packets with nonthermal carrier distributions is analyzed with femtosecond time resolution. A theoretical model based on the exciton-polariton concept including additional boundary conditions reproduces our experimental results. The observations in extremely thin samples show deviations from our phenomenological model. This finding is important for a detailed understanding of the microscopic polarizability near semiconductor surfaces.
Unified analysis of terminal-time control in classical and quantum systems
Creators: name: Pechen, Alexander
name: Rabitz, Herschel
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Many phenomena in physics, chemistry, and biology involve seeking an optimal control to maximize an objective for a classical or quantum system which is open and interacting with its environment. The complexity of finding an optimal control for maximizing an objective is strongly affected by the possible existence of sub-optimal maxima. Within a unified framework under specified conditions, control objectives for maximizing at a terminal time physical observables of open classical and quantum systems are shown to be inherently free of sub-optimal maxima. This attractive feature is of central importance for enabling the discovery of controls in a seamless fashion in a wide range of phenomena transcending the quantum and classical regimes.
description: 10 pages
Temperature Models for Pricing Weather Derivatives
Creators: name: Schiller, Frank
name: Seidler, Gerold
name: Wimmer, Maximilian
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: Weather Derivatives, Stochastic Processes, Temperature Dynamics, Heating Degree Days, Cooling Degree Days, Daily Simulation
subject: 330 Wirtschaft
subject: C52
subject: G13
subject: Q40

description: We present four models for predicting temperatures that can be used for pricing weather derivatives. Three of the models have been suggested in previous literature, and we propose another model which uses splines to remove trend and seasonality effects from temperature time series in a flexible way. Using historical temperature data from 35 weather stations across the United States, we test the performance of the models by evaluating virtual heating degree days (HDD) and cooling degree days (CDD) contracts. We find that all models perform better when predicting HDD indices than predicting CDD indices. However, all models based on a daily simulation approach significantly underestimate the variance of the errors.
A study on the texture and microstructure development in extruded AA3003 alloys and the relevant mechanical behaviour
Creators: name: Chen, Jingqi
Publisher: name: University of British Columbia
Year: 2018

description: In this study, a model alloy (i.e. AA3003) was used to examine microstructure and texture development in the extrusions and the relevant mechanical response. In particular, two homogenization heat treatments were studied as the initial condition, i.e. at 375 °C for 24 h, which produces a high density of dispersoids, and at 600 °C for 24 h, which produces a condition with almost no dispersoids. Three nearly ideal deformation modes were studied, i.e. (i) axisymmetric extension (the central region of a round bar extrusion), (ii) plane strain deformation (the central region of a strip extrusion), and (iii) simple shear deformation (using torsion tests). Electron backscatter diffraction (EBSD) was the main technique to characterize the texture and microstructure of the materials. For the axisymmetric extension and plane strain deformation, it is proposed that the high density of dispersoids in the material causes a large Zener drag, which inhibits grain boundary migration and thereby maintaining the deformation texture and microstructure in the extrusions. For the materials with almost no dispersoids, it is proposed that continuous dynamic recrystallization (CDRX, which is characterized as the subgrain coarsening or the grain boundary migration) occurs during and after the extrusion, and therefore, the texture and microstructure transform from the as-deformed to the recrystallized state. In contrast, for simple shear deformation (i.e. torsion), there is little difference observed between these two materials. However, with an increase in the level of equivalent strain, the texture changes from a deformation to a recrystallized texture. Geometric dynamic recrystallization (GDRX, which is characterized as the phenomenon of the grains continuously pinched off during the deformation) is proposed as the mechanism for the case of the simple shear deformation. For the mechanical behaviour of the extruded materials, it was found that the surface layer has little effect on the measured stress-strain curves. However, the surface layer has a large effect on the R-values, i.e. a characteristic value of the material formability. It is suggested that the large R-value difference between the surface layer and the central region of the sample is attributed to the different textures.
Anisotropic plasmons in a two-dimensional electron gas with spin-orbit interaction
Creators: name: Badalyan, Samvel M.
name: Matos-Abiague, Alex
name: Vignale, Giovanni
name: Fabian, Jaroslav
Publisher: name: Universität Regensburg
Year: 2009
Subjects: subject: 530 Physik
subject: 71.45.Gm
subject: 72.25.Dc
subject: 73.21.Fg
subject: 73.63.Hs

description: Spin-orbit coupling-induced anisotropies of plasmon dynamics are investigated in two-dimensional semiconductor structures. The interplay of the linear Bychkov-Rashba and Dresselhaus spin-orbit interactions drastically affects the plasmon spectrum: the dynamical structure factor exhibits variations over several decades, prohibiting plasmon propagation in specific directions. While this plasmon filtering makes the presence of spin-orbit coupling in plasmon dynamics observable, it also offers a control tool for plasmonic devices. Remarkably, if the strengths of the two interactions are equal, not only the anisotropy but all the traces of the linear spin-orbit coupling in the collective response disappear.
Turbocompressor test facility operating with Nelium mixtures and heat transfer effects
Creators: name: Podeur, Maxime
name: Vogt, Damian
Publisher: name: Zenodo
Year: 2021
Subjects: EASITrain; FCC; Nelium test rig; light gases; turbocompressor

description: Within the framework of the Future Circular Collider (FCC) and the EASITrain project, a major revision of the entire cryogenic cycle for the new machine is investigated in comparison to the LHC architecture. In particular, a closed-loop cryogenic cycle relying on turbocompressors and operating with Nelium mixtures is foreseen to enable the pre-cooling of helium. To better understand the challenges and opportunities associated with the design and operation of radial compressors with such light gases, a closed loop test facility has been designed, built and commissioned at the ITSM (University of Stuttgart). The test facility has been developed to operate with air as well as with helium-neon gas mixtures of varying mixing ratios. In this presentation, an overview of the test facility is first presented with its architecture, the components used together with a description of the operating procedure. Experimental results are then provided and validated against numerical evaluations. Moreover, the compressor motor being liquid cooled, a heat transfer between the coolant and the operating fluid leads to a modification of the operating fluid temperature and with it the measured aerodynamic efficiency. A model valid for all operating points and gases has been developed to remove this effect from measurements and is introduced here.
Nonlinear photogalvanic effect induced by monopolar spin orientation of holes in QWs
Creators: name: Ganichev, Sergey
name: Danilov, Sergey
name: Belkov, Vassilij
name: Ivchenko, Eougenious
name: Ketterl, Hermann
name: Wegscheider, Werner
name: Vorobjev, L. E.
name: Bichler, Max
name: Prettl, Wilhelm
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: Photogalvanic effect; Monopolar spin orientation
subject: 530 Physik
subject: 73.50.Mx; 73.50.Pz; 68.85.tq; 78.30.Fs

description: We report on the first observation of the circular photogalvanic effect (CPGE) induced by optical monopolar spin orientation of holes in p-doped quantum-well structures. It is shown that monopolar optical spin orientation of free carriers causes an electric current which reverses its direction upon changing from left to right circularly polarized radiation. The effect has been observed in (0 0 1)- and (3 1 1)A-oriented p-GaAs/AlGaAs quantum wells at normal incidence of far-infrared radiation. The photocurrent is proportional to the light intensity at low power levels and gradually saturates with increasing intensity. The CPGE can be utilized to investigate separately spin polarization of electrons and holes and to determine spin-relaxation times.
Current-induced spatial patterns of photoluminescence in AlxGa1-xAs/GaAs heterojunctions at quantizing magnetic fields
Creators: name: Novák, V.
name: Svonoda, P.
name: Kreuzer, Sebastian
name: Wegscheider, Werner
name: Prettl, Wilhelm
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik
subject: 73.43.Fj, 78.55.-m

description: A strong spontaneous spatial modulation of the photoluminescence near the AlGaAs/GaAs heterojunction has been found, if an external current and a quantizing magnetic field were applied to a homogeneously illuminated sample. A pattern of quenched and enhanced photoluminescence has been observed whose form varies synchronously with Shubnikov–de Haas oscillations. A phenomenological model of the effect is presented.
Audible developments : geographies of capitalism, nature, and sound on BC's North Coast
Creators: name: Ritts, Max Jacob
Publisher: name: University of British Columbia
Year: 2018

description: Proceeding from Denning's (2015) claim that sound is fundamental to social and political analysis, and hence, constitutive of 'audiopolitics', the dissertation argues for sound as an expressive medium of industrial development politics on the North Coast of British Columbia (BC), 2007-2015. Informed by sound studies, political ecology, and critical ethnography (Hart 2006), and drawing on eighteen-months of fieldwork (2012-2015), the dissertation identifies connections between large-scale development forces and communities experiencing uneven change. Chapter 2 engages environmental conservation activities through acoustically-mediated whale research, finding that situated conceptions of 'nature experience,' linked to institutionally sanctioned practices of interspecies listening, hold formal consistencies with Adorno's (1951) culture industry. Chapter 3 proceeds as a comparative study of noise abatement in the restructuring city of Prince Rupert, and follows three community campaigns which entangled themselves in locally-operative forms of neoliberal eco-governance. It argues that collective expressions of left melancholy (Brown 1999), and the reified conception of situated 'past-ness' they articulate, emerged from efforts to contest industrial sounds without challenging the logics they relied upon. Chapter 4 considers techno-scientific efforts to chart the biological impacts of ocean noise, now considered an emergent marine hazard linked to cavitating ship propellers. The chapter understands the consensus around the regional management of ocean noise 'risk' as evidence of hegemonization (Gramsci 2011), revealing a correspondence between marine bio-acoustics practices and capitalist efforts to attain sustainable growth trajectories in 'risky' marine space. Chapter 5 examines Gyibaaw (2006-2012), a musical project founded by two teenagers from the Gitga'at First Nation. Using Hall's (2017) concepts of articulation and conjuncture, it presents Gyibaaw as decolonial audiopolitics, and insists upon the significance of 'Indigenous black metal' at a contemporary nexus of Indigenous resurgence, resource extractivism, and ascendant white ethno-nationalism. Across these cases, sounds materialize as potent yet uncertain objects of social mediation, with their political valence not known in advance. The dissertation consistently observes deepening conditions of technological mediation, co-productive of new sonic natures and capitalist social forms, with consequences for local capacities to negotiate socio-ecological change and chart progressive futures.
Spatial quadratic solitons guided by narrow layers of a nonlinear material
Creators: name: Shapira, Asia
name: Voloch-Bloch, Noa
name: Malomed, Boris A.
name: Arie, Ady
Publisher: name: arXiv
Year: 2011
Subjects: subject: Optics (physics.optics)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We report analytical solutions for spatial solitons supported by layers of a quadratically nonlinear material embedded into a linear planar waveguide. A full set of symmetric, asymmetric, and antisymmetric modes pinned to a symmetric pair of the nonlinear layers is obtained. The solutions describe a bifurcation of the subcritical type, which accounts for the transition from the symmetric to asymmetric modes. The antisymmetric states (which do not undergo the bifurcation) are completely stable (the stability of the solitons pinned to the embedded layers is tested by means of numerical simulations). Exact solutions are also found for nonlinear layers embedded into a nonlinear waveguide, including the case when the uniform and localized nonlinearities have opposite signs (competing nonlinearities). For the layers embedded into the nonlinear medium, stability properties are explained by comparison to the respective cascading limit.
description: J. Opt. Soc. Am. B, in press
Remaining Resources of the Springfield Coal
Creators: name: Weisenfluh, Gerald A.
Publisher: name: Kentucky Geological Survey, University of Kentucky
Year: 2010

description: Abstract:
Historically, the Springfield (W. Ky. No. 9) opal bed has been the leading source of coal production in the Western Kentucky Coal Field. With 2009 production more than 21 million tons and another 8 million tons of idle capacity, it is also the most important resource in the state of Kentucky. The Springfield coal is known for its lateral continuity in terms of both thickness and quality. It is a medium-sulfur product, desirable for power plants with sulfur-reduction capability, and has higher Btu values and lower chlorine contents compared to other Illinois Basin areas north of Kentucky. It is estimated to have the largest original and remaining resource in the Western Kentucky Coal Field (Greb and others, 1992). This map presents a revised interpretation of coal thickness since the last assessment (Andrews and others, 2000), uses newly acquired data, and presents updated mining information.
Copyright: © 2010, University of Kentucky, Kentucky Geological Survey
Analysis of the temperature-dependent quantum point contact conductance in relation to the metal-insulator transition in two dimensions
Creators: name: Senz, V.
name: Heinzel, Thomas
name: Ihn, Thomas
name: Lindemann, S.
name: Held, R.
name: Ensslin, Klaus
name: Wegscheider, Werner
name: Bichler, Max
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik

description: The temperature dependence of the conductance of a quantum point contact has been measured. The conductance as a function of the Fermi energy shows temperature-independent fixed points, located at roughly multiple integers of e2/h. Around the first fixed point at e2/h, the experimental data for different temperatures can be scaled onto a single curve. For pure thermal smearing of the conductance steps, a scaling parameter of one is expected. The measured scaling parameter, however, is significantly larger than 1. The deviations are interpreted as a signature of the potential landscape of the quantum point contact, and of the source-drain bias voltage. We relate our results phenomenologically to the metal-insulator transition in two dimensions.
LiquidXML: Adaptive XML Content Redistribution
Creators: name: Camacho-Rodríguez, Jesús
name: Katsifodimos, Asterios
name: Manolescu, Ioana
name: Roatis, Alexandra
Publisher: name: arXiv
Year: 2010
Subjects: subject: Databases (cs.DB)
subject: FOS: Computer and information sciences

description: We propose to demonstrate LiquidXML, a platform for managing large corpora of XML documents in large-scale P2P networks. All LiquidXML peers may publish XML documents to be shared with all the network peers. The challenge then is to efficiently (re-)distribute the published content in the network, possibly in overlapping, redundant fragments, to support efficient processing of queries at each peer. The novelty of LiquidXML relies in its adaptive method of choosing which data fragments are stored where, to improve performance. The "liquid" aspect of XML management is twofold: XML data flows from many sources towards many consumers, and its distribution in the network continuously adapts to improve query performance.
Targeting autophagy in chronic myeloid leukemia through inhibition of the core autophagy protein ATG4B
Creators: name: Porter, Vanessa Lynn
Publisher: name: University of British Columbia
Year: 2018

description: Treatment of chronic myeloid leukemia (CML) targets the BCR-ABL1 fusion oncoprotein that characterizes its pathogenesis using tyrosine kinase inhibitors (TKIs); however, drug resistance and relapse can occur when BCR-ABL1-independant survival pathways such as autophagy are activated. Our lab found that the key autophagy enzyme ATG4B is upregulated in CML stem/progenitor cells from patients that clinically do not respond to TKIs vs. patients that do. Knockdown of ATG4B was found to suppress autophagy and sensitize CML cells to TKIs. This study investigates if combined suppression of BCR-ABL1 and ATG4B by novel ABL1 and ATG4B inhibitors in autophagy-inducing conditions may present a novel therapeutic approach to overcome TKI-resistance in CML. I found that inhibition of ATG4B by DB2 significantly inhibits growth and induces apoptosis in CML cell lines alone and in combination with TKIs when autophagy is induced during serum deprivation. There also is a decrease in colony forming cells after DB2+TKI treatment compared to TKIs alone in non-responding CML cells (p<0.05) but is well tolerated in normal bone marrow. Inhibition of ATG4B by DB inhibitors alters autophagy as seen by an accumulation of autophagosomes detected by western blots and florescent tracking. When DB2 is combined with TKI treatment in an aggressive mouse leukemia model, there are no significant differences in the leukemia burden between TKI treatment alone and the combination. However, another model shows that when ATG4B knockdown is combined with 70% caloric restriction, LC3B accumulates in the leukemic cells, and the mice have decreased engraftment and prolonged survival compared to the fed scrambled control mice, suggesting activation of autophagy is important to potentiate loss of ATG4B. This study presents ATG4B inhibition as a specific means to target autophagy and circumvent drug resistance in CML.
Cyclotron spin-flip excitations in the extreme quantum limit
Creators: name: Kulik, L. V.
name: Kukushkin, I. V.
name: Kirpichev, V. E.
name: Smet, J. H.
name: Klitzing, Klaus von
name: Wegscheider, Werner
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik
subject: 73.21.-b, 73.43.-f, 73.20.Mf, 78.30.-j

description: The cyclotron spin-flip excitations of a two-dimensional electron system in the extreme quantum limit have been investigated by inelastic light scattering. The electron interaction energy was directly determined from the gap between the charge- and spin-density modes in a broad region of electron filling factors. A comparison of the experimental results with the Hartree-Fock and generalized single mode approximations indicates a strong correlation between electrons at filling factors corresponding to both compressible and incompressible states.
Atomic Dipole Traps with Amplified Spontaneous Emission: A Proposal
Creators: name: Clément, Jean-François
name: Zehnlé, Véronique
name: Garreau, Jean Claude
name: Szriftgiser, Pascal
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We propose what we believe to be a novel type of optical source for ultra-cold atomic Far Off-Resonance optical-dipole Traps (FORTs). The source is based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a high power Erbium Doped Fiber Amplifier (EDFA). The main interest of this source is its very low coherence length, thus allowing an incoherent superposition of several trapping beams without any optical interference. The behavior of the superimposed beams is then a scalar sum greatly simplifying complex configurations. As an illustration, we report an estimation of the intensity noise of this source and an estimation of the atomic excess heating rate for an evaporative cooling experiment application. They are both found to be suitable for cold atoms experiments.
Investigation of Spin Pairing in a Semiconductor Quantum Dot
Creators: name: Lüscher, S.
name: Heinzel, Thomas
name: Ensslin, Klaus
name: Wegscheider, Werner
name: Bichler, Max
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik
subject: 73.21.La • 73.23.Hk

description: Semiconductor quantum dots have been patterned into a Ga[Al]As heterostructure by local oxidation of the GaAs cap layer with an Atomic Force Microscope. The combination of high electron density and reduced shape deformation allows us to observe spin pairs in the dot's energy level spectrum, which is demonstrated via correlated parametric evolution of the Coulomb blockade resonances in perpendicular magnetic fields. Here, we investigate the systematic change of the spacing between correlated Coulomb peaks as the magnetic field is increased. Furthermore we look at the distribution of even and odd nearest neighbor level separations and find a clear difference between the respective statistics.