cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Combined 1D-2D intersubband excitations and 1D single-particle spectrum in narrow quantum wires
Creators: name: Biese, G.
name: Schüller, Christian
name: Kurth, T.
name: Heitmann, Detlef
name: Grambow, P.
name: Eberl, Karl
Publisher: name: Universität Regensburg
Year: 1996
Subjects: subject: Gallium arsenide; Light scattering; Quantum wells; Raman scattering spectroscopy; Semiconductor-semiconductor heterostructures
subject: 530 Physik

description: Electronic excitations in AlGaAs-GaAs quantum wires have been investigated by means of resonant inelastic light scattering. Besides a rich spectrum of 1D electronic excitations at low frequencies we fin d at higher frequencies transitions in the regime of the original 2D intersubband excitations. Interestingly, we observe not only the original 2D intersubband excitations but additional modes ωk in polarized scattering geometry. The experimental observation is that the frequencies of these modes obey the relationship, ω2k = ω22D + ω21D, where ω2D is the vertical intersubband plasmon frequency and ω1D the lateral confined plasmon frequency. This relationship suggests that the additional modes are combined 2D-1D intersubband excitations of collective charge-density type.
Runup of tsunami waves in U-shaped bays
Creators: name: Didenkulova, Ira
name: Pelinovsky, Efim
Publisher: name: arXiv
Year: 2010
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: The problem of tsunami wave shoaling and runup in U-shaped bays (such as fjords) and underwater canyons is studied in the framework of shallow water theory. The wave shoaling in bays, when the depth varies smoothly along the channel axis, is studied with the use of asymptotic approach. In this case a weak reflection provides significant shoaling effects. The existence of traveling (progressive) waves, propagating in bays, when the water depth changes significantly along the channel axis, is studied. It is shown that traveling waves do exist for certain bay bathymetry configurations and may propagate over large distances without reflection. The tsunami runup in such bays is significantly larger than for a plane beach.
description: submitted for "Pure and Applied Geophysics"
Interactions of nanorod particles in the strong coupling regime
Creators: name: Huang, Cheng-ping
name: Yin, Xiao-gang
name: Kong, Ling-bao
name: Zhu, Yong-yuan
Publisher: name: arXiv
Year: 2010
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The plasmon coupling in a nanorod dimer obeys the exponential size dependence according to the Universal Plasmon Ruler Equation. However, it was shown recently that such a model does not hold at short nanorod distance (Nano Lett. 2009, 9, 1651). Here we study the nanorod coupling in various cases, including nanorod dimer with the asymmetrical lengths and symmetrical dimer with the varying gap width. The asymmetrical nanorod dimer causes two plasmon modes: one is the attractive lower- energy mode and the other the repulsive high-energy mode. Using a simple coupled LC-resonator model, the position of dimer resonance has been determined analytically. Moreover, we found that the plasmon coupling of symmetrical cylindrical (or rectangular) nanorod dimer is governed uniquely by gap width scaled for the (effective) rod radius rather than for the rod length. A new Plasmon Ruler Equation without using the fitting parameters has been proposed, which agrees well with the FDTD calculations. The method has also been extended to study the plasmonic wave-guiding in a linear chain of gold nanorod particles. A field decay length up to 2700nm with the lateral mode size about 50nm (~wavelength/28) has been suggested.
description: 31 pages, 6 figures, 58 references
Electric Field Dependent Zeeman Splitting of Excitons in Diluted Two-Dimensional Electron Systems
Creators: name: Broocks, K.-B.
name: Ebeling, T.
name: Karsten, L.
name: Schüller, Christian
name: Heyn, Christian
name: Heitmann, Detlef
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik
subject: 71.35.-y; 71.35.Ji; 71.70.Ej; 78.55.Cr; 78.67.De; S7.12

description: We investigate modulation-doped GaAs-AlGaAs quantum wells by photoluminescence spectroscopy. External gates allow us to tune the carrier densities below 1011 cm - 2, where we observe a crossover from an extended two-dimensional electron system to a regime where negatively charged excitons start to appear. By applying an external magnetic field, we can clearly resolve singlet and triplet excitons and neutral excitons. We find that the Zeeman splittings of the singlet and neutral excitons depend characteristically on the applied magnetic and electric fields. While the Zeeman splitting of the singlet exciton at high magnetic fields is always positive, the splitting of the neutral exciton can be tuned from negative to positive values by the external electric field.
Spatial Light Modulators for the Manipulation of Individual Atoms
Creators: name: Brandt, Lukas
name: Muldoon, Cecilia
name: Thiele, Tobias
name: Dong, Jian
name: Brainis, Edouard
name: Kuhn, Axel
Publisher: name: arXiv
Year: 2010
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We propose a novel dipole trapping scheme using spatial light modulators (SLM) for the manipulation of individual atoms. The scheme uses a high numerical aperture microscope to map the intensity distribution of a SLM onto a cloud of cold atoms. The regions of high intensity act as optical dipole force traps. With a SLM fast enough to modify the trapping potential in real time, this technique is well suited for the controlled addressing and manipulation of arbitrarily selected atoms.
description: 9 pages, 5 figures
Resonant Inelastic Light Scattering on GaAs-AlGaAs Quantum Dots
Creators: name: Steinebach, Christoph
name: Schüller, Christian
name: Ulrichs, E.
name: Heyn, Christian
name: Heitmann, Detlef
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: 530 Physik
subject: 73.21.La; 78.30.Fs; 78.67.Hc; S7.12

description: We investigate theoretically and experimentally the resonant Raman scattering on modulation-doped, deep-etched GaAs-AlGaAs quantum dots. The observation of so called single-particle excitations (SPE) in electronic Raman scattering on GaAs-AlGaAs nanostructures has been a puzzle for a long time. Our experimental investigations show that these excitations occur under conditions of extreme resonance, when the frequency of the incoming laser photons are close to the fundamental bandgap of the structure. To get a deeper understanding of the character of the SPE, we present an intriguing comparison of Kohn-Sham calculations with results of an exact many-body treatment by numerical diagonalization. We demonstrate that even for six electrons per quantum dot, single-particle-like excitations can be expected. In particular, we concentrate on a microscopic picture and show how the excitations can be described by a superposition of Hartree-Fock states.
Two-center Interferences in Photoionization of Dissociating H$_2^+$ Molecule
Creators: name: Picón, A.
name: Bahabad, A.
name: Kapteyn, H. C.
name: Murnane, M. M.
name: Becker, A.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We analyze two-center interference effects in the yields of ionization of a dissociating hydrogen molecular ion by an ultrashort VUV laser pulse. To this end, we performed numerical simulations of the time-dependent Schrödinger equation for a H$_2^+$ model ion interacting with two time-delayed laser pulses. The scenario considered corresponds to a pump-probe scheme, in which the first (pump) pulse excites the molecular ion to the first excited dissociative state and the second (probe) pulse ionizes the electron as the ion dissociates. The results of our numerical simulations for the ionization yield as a function of the time delay between the two pulses exhibit characteristic oscillations due to interferences between the partial electron waves emerging from the two protons in the dissociating hydrogen molecular ion. We show that the photon energy of the pump pulse should be in resonance with the $σ_g - σ_u$ transition and the pump pulse duration should not exceed 5 fs in order to generate a well confined nuclear wavepacket. The spreading of the nuclear wavepacket during the dissociation is found to cause a decrease of the amplitudes of the oscillations as the time delay increases. We develop an analytical model to fit the oscillations and show how dynamic information about the nuclear wavepacket, namely velocity, mean internuclear distance and spreading, can be retrieved from the oscillations. The predictions of the analytical model are tested well against the results of our numerical simulations.
The excitation function for Li+HF-->LiF+H at collision energies below 80 meV
Creators: name: Bobbenkamp, Rolf
name: Loesch, Hansjurgen
name: Mudrich, Marcel
name: Stienkemeier, Frank
Publisher: name: arXiv
Year: 2011
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: We have measured the dependence of the relative integral cross section of the reaction Li+HF-->LiF+H on the collision energy using crossed molecular beams. By varying the intersection angle of the beams from 37° to 90° we covered the energy range 25 meV < E_tr < 131 meV. We observe a monotonous rise of the cross section with decreasing energy over the entire energy range indicating that a possible translational energy threshold to the reaction is significantly smaller than 25 meV. The steep rise is quantitatively recovered by a Langevin-type excitation function based on a vanishing threshold and a mean interaction potential energy ~R^-2.5 where R is the distance between the reactants. To date all threshold energies deduced from ab-initio potentials and zero-point vibrational energies are at variance with our results, however, our findings support recent quantum scattering calculations that predict significant product formation at collision energies far below these theoretical thresholds.
description: 8 pages, 7 figures
Linear and ultrafast optical spectroscopy in the regime of the quantum Hall effect
Creators: name: Brooks, K.-B.
name: Su, B.
name: Schröter, P.
name: Heyn, Ch.
name: Heitmann, D.
name: Wegscheider, Werner
name: Apalkov, V. M.
name: Chakraborty, Tapash
name: Perakis, I. E.
name: Schüller, Christian
Publisher: name: Universität Regensburg
Year: 2008
Subjects: subject: 530 Physik
subject: 71.30.+h • 73.43.Lp • 73.63.Kv

description: We review our optical experiments on two-dimensional electron systems (2DES) of different mobilities, realized in modulation-doped GaAs-AlGaAs single quantum wells, in quantizing magnetic fields. The carrier densities of the 2DESs could be tuned in a quite broad range between about 1 × 1010 cm-2 and 2 × 1011 cm-2 via gate electrodes. In photoluminescence (PL) and absorption experiments on 2DES with moderate mobility, at very low electron densities, we have observed the formation of negatively charged excitons. In these experiments, we could identify a dark triplet exciton, which is observable at temperatures below 1 K and for electron filling factors v < 1/3 i.e., in the fractional quantum Hall regime, only. In experiments where we have increased the density of the 2DES so that a uniform 2DES starts to form, we have found a strong energetic anomaly of the charged excitons in the vicinity of filling factor 1/3. The anomaly could be explained by a model, assuming that at very low temperatures localized charged excitons and a uniform Laughlin liquid coexist. Furthermore, we report on ultrafast optical experiments at the v = 1 quantum Hall state of a high-mobility 2DES in a GaAs-AlGaAs single quantum well. By spectrally-resolved four-wave-mixing experiments, we have investigated the coherent dynamics of photo-excited electron-hole pairs and found extraordinarily long decoherence times for electrons, excited into the upper spin level, around v = 1 We attribute the observed faster decay of the dephasing time for v < 1 as compared to v > 1 presumably to the coherent coupling of the spin levels via spin waves. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Digital Innovations in Healthcare: An Analysis of Requirements and Drivers Towards a Stakeholder Network
Creators: name: Arlinghaus, Tim
Publisher: name: Universität Osnabrück
Year: 2023
Subjects: subject: Wirtschaftsinformatik
subject: Digitalisierung
subject: Gesundheitswesen
subject: Innovation
subject: 004 - Informatik
subject: 54.08 - Informatik in Beziehung zu Mensch und Gesellschaft

description: Die Komplexität des Gesundheitssektors erfordert eine effektive Zusammenarbeit zwischen verschiedenen Interessengruppen, um eine umfassende Versorgung von Individuen zu gewährleisten. Diese Dissertation untersucht die Herausforderungen und Chancen bei der Weiterentwicklung von Vernetzung und KI-gesteuerter Datenanalyse im deutschen Gesundheitssystem. Die Vorbedingungen für den Aufbau von Vertrauen und Akzeptanz bei Gesundheitsfachleuten für die gemeinsame Vernetzung werden untersucht. Die erste Forschungsfrage (RQ1) konzentriert sich darauf, entscheidende Faktoren und notwendige Bedingungen zur Förderung von Vernetzung und KI-gesteuerter Datenanalyse zu identifizieren. Hierbei wird der Status Quo zu Datentreuhandstellen, KI und Barrieren zur digitalen Vernetzung aufgezeigt. RQ2 beschäftigt sich mit funktionalen und nicht-funktionalen Anforderungen, die digitale Lösungen im Gesundheitssektor erfüllen müssen, um die Akzeptanz der Benutzer zu steigern. Das ungenutzte Potenzial der Digitalisierung im deutschen Gesundheitssektor wird diskutiert, wobei die Notwendigkeit einer effektiven Kommunikation ihrer Vorteile an verschiedene Interessengruppen betont wird. Die Studie zielt darauf ab, Anforderungen zu identifizieren, die für benutzerfreundliche digitale Lösungen entscheidend sind und eine weit verbreitete Akzeptanz fördern. Die dritte Forschungsfrage (RQ3) untersucht die wirtschaftlichen Vorteile der digitalen Vernetzung zwischen Akteuren im Gesundheitswesen und schlägt eine Visualisierungsmethode vor. Trotz der durch Regierungsreformen gelegten Grundlagen für die Digitalisierung bestehen Herausforderungen in der konsistenten Umsetzung. RQ3 der Dissertation zielt darauf ab, die wirtschaftlichen Vorteile der digitalen Vernetzung zu zeigen und Visualisierungsmethoden vorzuschlagen, um den Wertvorschlag für Interessengruppen deutlich zu machen. Durch die Anwendung verschiedener Forschungsmethoden und die Untersuchung unterschiedlicher Aspekte bietet diese Dissertation einen umfassenden Fahrplan für die Digitalisierung im deutschen Gesundheitssektor. Durch die Bearbeitung der Forschungsfragen soll die Studie zu einem nuancierten Verständnis der erforderlichen Schritte für eine erfolgreiche Umsetzung beitragen und die erwarteten wirtschaftlichen Ergebnisse der Integration digitaler Lösungen im Gesundheitswesen hervorheben
Skipping Orbit Electron Motion in GaAs-AlGaAs Quantum Wires Detected by Raman Spectroscopy
Creators: name: Ulrichs, E.
name: Biese, G.
name: Steinebach, C.
name: Schüller, Christian
name: Heitmann, Detlef
name: Eberl, Karl
Publisher: name: Universität Regensburg
Year: 1997
Subjects: subject: 530 Physik

description: We have investigated the elementary electronic excitations of the quasi-one-dimensional (1D) magnetoplasma in GaAs-AlGaAs quantum wires by resonant inelastic light scattering. In narrow quantum wire samples we observe the 1D intrasubband plasmon if a wave vector is transferred parallel to the wire direction. This 1D plasmon shows a negative dispersion with magnetic field, which arises from skipping orbit motion of the individual electrons at the edges of the wires. We find evidence for a coupling between adjacent wires in these samples with relatively small periods. Furthermore, we demonstrate theoretically and experimentally that in Raman experiments on confined magnetoplasmons in quantum wire structures with parabolic confinement the generalized Kohn theorem can be broken by using wave vector transfers q > 0.
Multiple Andreev reflections in hybrid multiterminal junctions
Creators: name: Houzet, M.
name: Samuelsson, P.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We investigate theoretically charge transport in hybrid multiterminal junctions with superconducting leads kept at different voltages. It is found that multiple Andreev reflections involving several superconducting leads give rise to rich subharmonic gap structures in the current-voltage characteristics. The structures are evidenced numerically in junctions in the incoherent regime.
description: 5 pages, 3 figures
A new viable region of the inert doublet model
Creators: name: Lopez-Honorez, Laura
name: Yaguna, Carlos E.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The inert doublet model, a minimal extension of the Standard Model by a second Higgs doublet, is one of the simplest and most attractive scenarios that can explain the dark matter. In this paper, we demonstrate the existence of a new viable region of the inert doublet model featuring dark matter masses between Mw and about 160 GeV. Along this previously overlooked region of the parameter space, the correct relic density is obtained thanks to cancellations between different diagrams contributing to dark matter annihilation into gauge bosons (W+W- and ZZ). First, we explain how these cancellations come about and show several examples illustrating the effect of the parameters of the model on the cancellations themselves and on the predicted relic density. Then, we perform a full scan of the new viable region and analyze it in detail by projecting it onto several two-dimensional planes. Finally, the prospects for the direct and the indirect detection of inert Higgs dark matter within this new viable region are studied. We find that present direct detection bounds already rule out a fraction of the new parameter space and that future direct detection experiments, such as Xenon100, will easily probe the remaining part in its entirety.
description: 27 pages, 16 figures
Nitrogen recovery from municipal wastewater through newberyite to struvite crystallization process
Creators: name: Disha, Afrina Zerin
Publisher: name: University of British Columbia
Year: 2018

description: The present study evaluated the feasibility of using newberyite (MgHPO₄.6H₂O), a thermal decomposition product of struvite, as an inexpensive source of magnesium and phosphate to achieve high nitrogen removal efficiency from domestic wastewater, through struvite recrystallization. Several bench scale and pilot scale experiments were performed with a different combination of synthetic wastewater, real centrate from the municipal post digestion wastewater stream, synthetic newberyite powder and actual newberyite pellets, derived from thermally decomposing struvite. Ammonia removal efficiency as high as 94% was achieved in bench scale experiments for dewatering centrate from Annacis wastewater treatment plant at pH 8.5. Orthophosphate residual resulting from newberyite dissolution can be kept as low 23.8 mg/l. The recrystallized product was found to be a mixture of newberyite and struvite. Further experiments were carried out to solubilized newberyite, prior to providing a favorable condition for struvite formation. Although no struvite was formed at this stage, the orthophosphate release was lower, compared to model prediction. The reduction in orthophosphate dissolution is potentially due to low hydraulic retention time. The pilot scale experiment in the UBC fluidized bed reactor was inconclusive, due to an inability to continuously produce struvite pellets, instead of fines. The present study illustrates the potential for newberyite to struvite recrystallization technology. However, it is recommended to carry out further research on newberyite solubilization and newberyite to struvite, pelletization kinetics.
Magneto-Optical Investigation of Excitons in Narrow GaAs-AlGaAs Quantum Wires
Creators: name: Rademacher, F.
name: Eggers, H.
name: Wiegard, T. O.
name: Schüller, Christian
name: Bargstädt-Franke, S.
name: Heyn, Christian
name: Eberl, Karl
name: Heitmann, Detlef
Publisher: name: Universität Regensburg
Year: 1997
Subjects: subject: 530 Physik

description: We present a method for the preparation of GaAs-AlGaAs quantum wire arrays starting from holographically prepared masks. The combination of reactive ion etching and stepwise wet-chemical etching allows us to produce narrow quantum wires. We achieved wire widths down to 40 nm. The diamagnetic shift of the magnetoexcitons in our samples shows clear evidence of enhanced Coulomb interaction between photocreated electrons and holes due to the lateral confinement. A decrease of the lateral extension of the excitonic wave function from 10.6 nm in the 2D reference sample to 7.4 nm in the 40 nm wide quantum wires is deduced from the data.
Discriminating Different $Z^\prime$s via Asymmetries at the LHC
Creators: name: Zhou, Zhong-qiu
name: Xiao, Bo
name: Wang, You-kai
name: Zhu, Shou-hua
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: In practice the asymmetry, which is defined based on the angular distribution of the final states in scattering or decay processes, can be utilized to scrutinize underlying dynamics in and/or beyond the standard model (BSM). As one of the possible BSM physics which might be discovered early at the LHC, extra neutral gauge bosons $Z^\prime$s are theoretical well motivated. Once $Z^\prime$s are discovered at the LHC, it is crucial to discriminate different $Z^\prime$s in various BSM. In principle such task can be accomplished by measuring the angular distribution of the final states which are produced via $Z^\prime$-mediated processes. In the real data analysis, asymmetry is always adopted. In literature several asymmetries have been proposed at the LHC. Based on these works, we stepped further on to study how to optimize the asymmetries in the left-right model and the sequential standard model, as the examples of BSM. In this paper, we examined four kinds of asymmetries, namely rapidity-dependent forward-backward asymmetry, one-side forward-backward asymmetry, central charge asymmetry and edge charge asymmetry (see text for details), with $\ell^+\ell^-$ ($\ell=e,μ$), $b\bar b$ and $t\bar t$ as the final states. In the calculations with $b\bar b$ and $t\bar t$ final states, the QCD-induced higher order contributions to the asymmetric cross section were also included. For each kind of final states, we estimated the four kinds of asymmetries and especially the optimal cut usually associated with the definition of the asymmetry. Our numerical results indicated that the capacity to discriminate $Z^\prime$ models can be improved by imposing the optimal cuts.
description: 17 pages, 20 ps files
IO500 Full Ranked List, Supercomputing 2018 (Corrected)
Creators: name: Bent, John
name: Kunkel, Julian
name: Lofstead, Jay
name: Markomanolis, George
Publisher: name: Zenodo
Year: 2018
Subjects: IO500

description: The IO500 Benchmark publishes twice annual ranked lists of all submissions.  This list was first published at the 2018 SC conference but has been corrected to fix a reporting bug in some of the metadata scores.
description: https://www.vi4io.org/io500/list/19-01/start
Collective intersubband excitations in p-doped GaAs-AlGaAs multiple quantum wells
Creators: name: Schüller, Christian
name: Kraus, J.
name: Latussek, V.
name: Schaack, G.
name: Ebeling, J. K.
Publisher: name: Universität Regensburg
Year: 1992
Subjects: subject: 530 Physik

description: We report on Raman spectroscopic investigations of collective spin-density (SDW) and charge-density waves (CDW) in the two-dimensional hole gas of a p-modulation doped GaAs/AlxGa1-xAs multiple quantum-well (MQW) structure and on the consequence of Landau damping of these excitations. From the existence of collective SDW with energies lower than the border of the single-particle continuum we derive that exchange and correlation effects are of considerable strength in such hole gases.
Εναλλακτικές πολιτιστικές διαδρομές, περιήγηση και διαμονή σε νησιωτικούς προορισμούς στη Μεσόγειο. Σχεδιασμός για τα τοπία των οικισμών στην ενδοχώρα της Κέρκυρας
Creators: name: Προβατάς, Στέφανος Σπυρίδωνα
Publisher: name: Aristotle University of Thessaloniki
Year: 2023
Subjects: Εναλλακτικός Τουρισμός
Κέρκυρα
Πολιτιστικές Διαδρομές
Alternative Tourism
Corfu
Cultural Routes

description: Σκοπός της παρούσας ερευνητικής εργασίας ήταν η δημιουργία ενός εναλλακτικού μοντέλου τουρισμού για την Κέρκυρα, εστιάζοντας στην περιήγηση των επισκεπτών, την εξερεύνηση ιστορικών, θρησκευτικών και φυσικών χώρων, καθώς και την προστασία της τοπικής ταυτότητας. Βασισμένη σε ανάλυση γεωγραφικών δεδομένων και συστημάτων GIS, η μεθοδολογία συνδυάζει διάφορες μορφές εναλλακτικού τουρισμού για μια πιο ολοκληρωμένη βιωματική εμπειρία. Η εργασία ολοκληρώνεται με την πρόταση που στηρίζεται στις διαδρομές και την ανάλυση που τις συνοδεύει με την χρήση πληροφοριών από διάφορα γεωγραφικά συστήματα.
description: The aim of the present thesis was to create an alternative tourism model for Corfu, focusing on visitor exploration, the investigation of historical, religious, and natural sites, as well as the protection of local identity. Based on the analysis of geographical data and GIS systems, the methodology combines various forms of alternative tourism for a more comprehensive experiential experience. The work is completed with the proposal that is supported by the routes and the accompanying analysis using information from various geographical systems.
Electronic Raman scattering in p-doped GaAs/Ga1-xAlxAs quantum-well structures: Scattering mechanisms and many-particle interactions
Creators: name: Schüller, Christian
name: Krause, Jürgen
name: Schaack, G.
name: Weimann, G.
name: Panzlaff, K.
Publisher: name: Universität Regensburg
Year: 1994
Subjects: subject: 530 Physik
subject: 73.20.Mf, 73.20.Dx, 78.30.Fs

description: By means of resonance Raman spectroscopy we have investigated intersubband transitions of quasi-two-dimensional (2D) hole gases in p-type modulation-doped GaAs/Ga1-xAlxAs quantum-well structures. The observed excitations have an essentially single-particle character due to Landau damping of collective excitations and due to single-particle scattering by energy-density fluctuations under conditions of extreme resonance. In samples with well widths of typically 100–200 Å and 2D hole densities ρ∼1011 cm-2, we observe a characteristic variation of intersubband-transition energies with laser frequency in depolarized and in polarized scattering configurations. This variation is caused by the nonparabolic subband dispersion of the 2D single-particle hole subbands. Experiments under variation of p, by illuminating the sample with photons that have energies above the band gap of the Ga1-xAlxAs barriers, allow an estimate of the relative strengths of direct and exchange Coulomb interactions. From these experiments a greater relative strength of the exchange interaction, in comparison to that found for 2D electron gases, can be deduced.
Spin Accumulation in Diffusive Conductors with Rashba and Dresselhaus Spin-Orbit Interaction
Creators: name: Duckheim, Mathias
name: Loss, Daniel
name: Scheid, Matthias
name: Richter, Klaus
name: Adagideli, İnanç
name: Jacquod, Philippe
Publisher: name: Universität Regensburg
Year: 2010
Subjects: subject: 530 Physik
subject: 73.23.-b, 72.25.Dc, 75.80.+q, 85.75.-d

description: We calculate the electrically induced spin accumulation in diffusive systems due to both Rashba (with strength $\alpha)$ and Dresselhaus (with strength $\beta)$ spin-orbit interaction. Using a diffusion equation approach we find that magnetoelectric effects disappear and that there is thus no spin accumulation when both interactions have the same strength, $\alpha=\pm \beta$. In thermodynamically large systems, the finite spin accumulation predicted by Chaplik, Entin and Magarill, [Physica E {\bf 13}, 744 (2002)] and by Trushin and Schliemann [Phys. Rev. B {\bf 75}, 155323 (2007)] is recovered an infinitesimally small distance away from the singular point $\alpha=\pm \beta$. We show however that the singularity is broadened and that the suppression of spin accumulation becomes physically relevant (i) in finite-sized systems of size $L$, (ii) in the presence of a cubic Dresselhaus interaction of strength $\gamma$, or (iii) for finite frequency measurements. We obtain the parametric range over which the magnetoelectric effect is suppressed in these three instances as (i) $|\alpha|-|\beta| \lesssim 1/mL$, (ii)$|\alpha|-|\beta| \lesssim \gamma p_{\rm F}^2$, and (iii) $|\alpha|-|\beta| \lesssiM \sqrt{\omega/m p_{\rm F}\ell}$ with $\ell$ the elastic mean free path and $p_{\rm F}$ the Fermi momentum. We attribute the absence of spin accumulation close to $\alpha=\pm \beta$ to the underlying U (1) symmetry. We illustrate and confirm our predictions numerically.
Surveillance Disguised as Protection: A Comparative Analysis of Sideloaded and In-Store Parental Control Apps
Creators: name: Maier, Eva-Maria
name: Tanczer, Leonie Maria
name: Klausner, Lukas Daniel
Publisher: name: arXiv
Year: 2025
Subjects: subject: Cryptography and Security (cs.CR)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Parental control applications, software tools designed to manage and monitor children's online activities, serve as essential safeguards for parents in the digital age. However, their usage has sparked concerns about security and privacy violations inherent in various child monitoring products. Sideloaded software (i. e. apps installed outside official app stores) poses an increased risk, as it is not bound by the regulations of trusted platforms. Despite this, the market of sideloaded parental control software has remained widely unexplored by the research community. This paper examines 20 sideloaded parental control apps and compares them to 20 apps available on the Google Play Store. We base our analysis on privacy policies, Android package kit (APK) files, application behaviour, network traffic and application functionalities. Our findings reveal that sideloaded parental control apps fall short compared to their in-store counterparts, lacking specialised parental control features and safeguards against misuse while concealing themselves on the user's device. Alarmingly, three apps transmitted sensitive data unencrypted, half lacked a privacy policy and 8 out of 20 were flagged for potential stalkerware indicators of compromise (IOC).
description: 18 pages, 2 figures
Flavour violating up-squark decays at LHC
Creators: name: Eberl, H.
name: Bartl, A.
name: Herrmann, B.
name: Hidaka, K.
name: Majerotto, W.
name: Porod, W.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the effect of squark generation mixing on squark production and decays at the LHC in the Minimal Supersymmetric Standard Model (MSSM). We show that the effect can be very large despite the very strong constraints on quark flavour violation (QFV) from experimental data on B mesons. We find that the two lightest up-type squarks ${\tilde u}_{1,2}$ can have large branching ratios for the decays into $c {\tildeχ_1^0}$ and $t {\tildeχ_1^0}$ at the same time, leading to QFV signals '$p p \to c \bar t\, (t \bar c)$ + missing-$E_T$ + $X$' with a significant rate. The observation of this remarkable signature would provide a powerful test of supersymmetric QFV at LHC. This could have a significant impact on the search for squarks and the determination of the underlying MSSM parameters.
description: 4 pages, 4 figures, contribution to the proceedings of "School and Workshops on the Standard Model and Beyond - Cosmology", Corfu, August 29 - September 5, 2010. To appear in FdP
Observation of finite-thickness effects on the spin-density excitations in quantum wires
Creators: name: Steinebach, Christoph
name: Schüller, Christian
name: Biese, G.
name: Heitmann, Detlef
name: Eberl, Karl
Publisher: name: Universität Regensburg
Year: 1998
Subjects: subject: 530 Physik
subject: 73.20.Dx, 73.20.Mf, 78.30.-j, 78.66.Fd

description: We investigate the effect of finite thickness of quantum wires on spin-density excitations (SDEs). In contrast to plasmon excitations, SDEs depend sensitively on the force law that describes the electron-electron interaction. We find that, especially for low electron densities, the corrections due to a three-dimensional interaction are very important. We use both the time-dependent Hartree-Fock and local-density approximations to calculate the first confined collective SDE. The results are compared with Raman experiments. The agreement is excellent and shows that a three-dimensional treatment is absolutely necessary to explain the experiments.
Internal structure of nanoparticles of Al generated by laser ablation in liquid ethanol
Creators: name: Viau, G.
name: Colliere, V.
name: Shafeev, G. A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Al NPs are synthesized by laser ablation of a bulk Al target immersed into liquid ethanol saturated with hydrogen at atmospheric pressure. The nanoparticles possess a well-distinguished core-shell structure. High Resolution Transmission Electron Microscopy shows several layers inside the Al nanoparticle: oxide layer, amorphous Al, single crystal Al, and a cavity in the center. Formation of the cavity is attributed to the sharp increase of hydrogen dissolution in Al upon its melting and its eventual release after the solidification.
Jessica's Case Study: Appraising research for rigour and relevance
Creators: name: Gleeson, Jo
name: Cutler, Blake
name: Hall, Genevieve
name: Rickinson, Mark
name: Walsh, Lucas
Publisher: name: Monash University
Year: 2023
Subjects: Professional education and training
Teacher education and professional development of educators
Educational administration, management and leadership

description: This practitioner case study shares the journey of Jessica and how she approached the quality use of research in her context. This case study was developed by the Monash Q Project (2019-2023) and published as part of the resources for the Monash Faculty of Education short course "An introduction to using research to inform educational practice." The course is designed for teachers, school leaders and education system actors who are beginning to use research in their work and are looking to use research evidence to support their practice.
One-dimensional plasmons in magnetic fields
Creators: name: Ulrichs, E.
name: Biese, G.
name: Steinebach, C.
name: Schüller, Christian
name: Heitmann, D.
Publisher: name: Universität Regensburg
Year: 1997
Subjects: subject: 530 Physik
subject: 73.20.Dx, 73.20.Mf, 78.30.Fs, 71.45.Gm

description: We have investigated the wave-vector (q) and magnetic-field (B) dependence of plasmons propagating along quantum wires by means of resonant Raman spectroscopy. We observe a mode with a well-pronounced negative B dispersion that arises from the skipping-orbit motion of the individual electrons within the collective excitation. At higher frequencies we find a set of additional modes that represent a superposition of freely propagating oscillations along the wire and confined oscillations perpendicular to the wires. These modes exhibit in a magnetic field a strong interaction with harmonics, n=2,3…, of the cyclotron frequency nωc.
Faddeev-type equations for three-body symmetry violating scattering amplitudes
Creators: name: Gudkov, Vladimir
name: Song, Young-Ho
Publisher: name: arXiv
Year: 2010
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The equations which relate three-body and two-body symmetry violating scattering amplitudes are derived in the first order of symmetry violating interactions. They can be used to obtain three-body symmetry violating scattering amplitudes from two-body symmetry violating scattering amplitudes calculated in low energy effective field theory.
Selectively enhanced inelastic light scattering of electronic excitations in a semiconductor microcavity
Creators: name: Kipp, T.
name: Rolf, L.
name: Schüller, Christian
name: Endler, D.
name: Heyn, Christian
name: Heitmann, Detlef
Publisher: name: Universität Regensburg
Year: 2001
Subjects: subject: aluminium compounds, gallium arsenide, III-V semiconductors, microcavity lasers, semiconductor quantum wells, light scattering
subject: 530 Physik
subject: 73.21.-b; 73.20.Mf; 78.30.-j; 78.66.Fd

description: We report a strong selective enhancement of electronic intersubband excitations of a modulation-doped GaAs-Al0.2Ga0.8As quantum well placed inside an AlAs-Al0.4Ga0.6As planar lambda microcavity. By using specific angles for the incident and scattered light, both the exciting laser and the scattered photons can be tuned into resonance with the cavity mode. Since the width of the high-quality cavity mode is smaller than the widths of the electronic excitations, we can, in the double-resonance case, selectively enhance parts of the excitations by about 3 orders of magnitude compared to the single-resonance condition. This offers the possibility to selectively study weak electronic excitations in low-dimensional electron systems.
Φαρμακογνωστική μελέτη του φυτού Cyanus cyanoides (Wahlenb.) Wagenitz & Greuter
Creators: name: Καραβέργου, Σοφία Αλέξιου
Publisher: name: Aristotle University of Thessaloniki
Year: 2023
Subjects: Δευτερογενείς μεταβολίτες
Χρωματογραφία
Βιολογική δράση
Secondary metabolites
Chromatography
Biological activity

description: Στόχος αυτής της διπλωματικής εργασίας είναι η απομόνωση και η ταυτοποίηση των δευτερογενών μεταβολιτών των εναέριων τμημάτων του είδους Cyanus cyanoides (Wahlenb.) Wagenitz & Greuter της οικογένειας Asteraceae, η in silico πρόβλεψη της βιοδιαθεσιμότητας και της βιοδραστικότητας των απομονωμένων ουσιών και η in vitro μελέτη των βιολογικών δράσεων των εκχυλισμάτων του φυτού. Με τη χρήση χρωματογραφικών και φασματοσκοπικών τεχνικών απομονώθηκαν και ταυτοποιήθηκαν από μία γ-βουτυρολακτόνη: 2-deoxy-D-1,4-ribonolactone (1), τρία φαινολικά οξέα: p-hydroxy benzoic acid (2), protocatechuic acid (3), vanillic acid (4) και δύο φλαβονοειδή: apigenin (5) και quercetin (6). Τα εκχυλίσματα που προέκυψαν από τις κατανομές του αρχικού μεθανολικού εκχυλίσματος του φυτού μελετήθηκαν με in vitro τεχνικές ως προς την περιεκτικότητα τους σε φαινολικές ενώσεις με την μέθοδο Folin-Ciocalteu, ως προς την αντιοξειδωτική τους δράση με τη δοκιμασία αλληλεπίδρασης με το DPPH (ρίζα 2,2-διφαίνυλο-1-πικρυλυδραζυλίου) και ως προς την αντιφλεγμονώδη δράση με τις τεχνικές αναστολής της λιπιδικής υπεροξείδωσης (AAPH) και της αναστολής του ενζύμου της φυτικής προέλευσης λιποξυγονάσης (LOX)
description: The aim of this study is to isolate and identify the secondary metabolites from the aerial parts of the species Cyanus cyanoides (Wahlenb.) Wagenitz & Greuter that belongs to the family Asteraceae, predict the bioavailability and bioactivity of the isolated compounds by in silico techniques and evaluate the biological activities of the plant extracts by in vitro techniques. Applying chromatography and spectroscopy methods, we isolated and identified one γ-butyrolactone: 2-deoxy-D-1,4-ribonolactone (1), three phenolic acids: p-hydroxy benzoic acid (2), protocatechuic acid (3), vanillic acid (4) and two flavonoids: apigenin (5) και quercetin (6). The fractionated extracts, derived from the crude methanolic extract, were studied for their total amount in phenolic compounds using Folin- Ciocalteu assay and for their antioxidant capacity based on the DPPH assay (2,2-diphenyl-1-picrylhydrazyl radical). Finally, the anti-inflammatory potential of the extracts was tested by assessing their ability to inhibit lipid peroxidation (AAPH) and the enzyme soybean lipoxygenase (LOX)
Quantum singularities in FRW universe revisited
Creators: name: Letelier, Patricio S.
name: Pitelli, João Paulo M.
Publisher: name: arXiv
Year: 2010
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The components of the Riemann tensor in the tetrad basis are quantized and, through the Einstein equation, we find the local expectation value in the ontological interpretation of quantum mechanics of the energy density and pressure of a perfect fluid with equation of state $p=\frac{1}{3}ρ$ in the flat Friedmann-Robertson-Walker quantum cosmological model. The quantum behavior of the equation of state and energy conditions are then studied and it is shown that the later is violated since the singularity is removed with the introduction of quantum cosmology, but in the classical limit both the equation of state and the energy conditions behave as in the classical model. We also calculate the expectation value of the scale factor for several wave packets in the many-worlds interpretation in order to show the independence of the non singular character of the quantum cosmological model with respect to the wave packet representing the wave function of the Universe. It is also shown that, with the introduction of non-normalizable wave packets, solutions of the Wheeler-DeWitt equation, the singular character of the scale factor, can be recovered in the ontological interpretation.
description: 15 pages, revtex, accepted for publication in PRD
Gate control of low-temperature spin dynamics in two-dimensional hole systems
Creators: name: Kugler, M.
name: Andlauer, T.
name: Korn, Tobias
name: Wagner, Christoph
name: Fehringer, S.
name: Schulz, Robert
name: Kubová, M.
name: Gerl, Christian
name: Schuh, Dieter
name: Wegscheider, Werner
name: Vogl, P.
name: Schüller, Christian
Publisher: name: Universität Regensburg
Year: 2009
Subjects: subject: aluminium compounds, Faraday effect, gallium arsenide, g-factor, III-V semiconductors, localised states, optical Kerr effect, photoluminescence, semiconductor quantum wells, spin dynamics, spin polarised transport, time resolved spectra, two-dimensional hole gas
subject: 530 Physik
subject: 78.67.De
subject: 78.55.Cr

description: We have investigated spin and carrier dynamics of resident holes in high-mobility two-dimensional hole systems in GaAs/Al0.3Ga0.7As single-quantum wells at temperatures down to 400 mK. Time-resolved Faraday and Kerr rotation as well as time-resolved photoluminescence spectroscopy are utilized in our study. We observe long-lived hole-spin dynamics that are strongly temperature dependent, indicating that in-plane localization is crucial for hole-spin coherence. By applying a gate voltage, we are able to tune the observed hole g factor by more than 50%. Calculations of the hole g tensor as a function of the applied bias show excellent agreement with our experimental findings.
title: H "εμμονή" με το υλικό: σχεδιάζοντας μαζί με τα υλικά και τις τεχνικές τους
title: Exploring material obsession: a comprehensive analysis of strategic planning with materials and material application techniques
Creators: name: Μπενακη Μαρκελα
Publisher: name: Technical University of Crete
Year: 2023

description: Στην αρχιτεκτονική το υλικό και η τεχνική είναι κάτι που δεν μπορούμε να διαχωρίσουμε, όπου υπάρχει υλικό υπάρχει και μια τεχνική με την οποία θα εφαρμοστεί. Η παρούσα ερευνητική εργασία αποσκοπεί στην διερεύνηση των αρχιτεκτόνων που τα υλικά και οι τεχνικές των υλικών, αποτελούν βασικό στοιχείο της αρχιτεκτονική τους. Γίνεται μία βιογραφική ανασκόπηση μερικών από των πιο επιδραστικών αρχιτεκτόνων του 20ου και 21ου αιώνα η οποία ξεκινάει από τα πρώτα χρόνια της ζωής τους και εμβαθύνει στην εξέλιξη της αρχιτεκτονικής τους. Μέσα από αυτή την έρευνα συντάχθηκε ένας συμπερασματικός πίνακας ο οποίος χωρίζει τους αρχιτέκτονες με βάση την γεωγραφική τους καταγωγή σε κατηγορίες ανάλογα με την εμμονή τους στα υλικά, την τεχνική ή συνδυασμός των δύο αλλά και χωρίς υλικό για τους paper architects. Ιδιαίτερη έμφαση δίνεται στην επιλογή τους να χρησιμοποιήσουν τα υλικά πέρα από την ιδιότητα τους ως δομικά μέσα αλλά και ως αισθητικά, με την βοήθεια της θεωρίας του Semper για την επιφάνεια. Στόχος είναι να απαντηθούν ερωτήματα για την εμμονή τους αυτή, εάν οφείλεται σε προσωπική τους έκφραση, εάν επηρρεάστηκαν από το περιβάλλον τους, ακόμα και αν αυτοί οι αρχιτέκτονες έχουν κάτι που τους συνδέει.

description: In architecture, materials and techniques are something we cannot separate, for every material there is a technique which it will be applied. This research work aims to investigate the architects whose materials and techniques are a key element of their architecture. It is a biographical review of some of the most influential architects of the 20th and 21st centurie that begins with their early years and delves into the evolution of their architecture. Through this research, a conclusive table was conducted which divides the architects based on their geographical origin into categories according to their obsession with materials, techniques or a combination of the two but also without material for paper architects. Particular emphasis is placed on their choice to use materials beyond their properties as structural means but also as aesthetic ones, with the help of Semper's theory about surface. The aim is to answer questions about their obsession, if it is due to their personal expression, if they were influenced by their environment or even if these architects have something in common.
Resonant Raman scattering of quantum dots
Creators: name: Steinebach, Christoph
name: Schüller, Christian
name: Heitmann, Detlef
Publisher: name: Universität Regensburg
Year: 1999
Subjects: subject: 530 Physik
subject: 78.30.-j, 73.20.Dx, 73.20.Mf, 78.66.Fd

description: We theoretically investigate the resonant Raman scattering of GaAs quantum dots. The electron system is treated within the time-dependent local-density approximation and the cross section is calculated by including valence-band states as intermediate states in the scattering process. We show that, besides the strongly collective charge-density excitations and spin-density excitations, which dominate the spectra in the nonresonant case, additional modes close to the single-particle level spacings become resonant for certain laser energies in polarized and depolarized geometry. However, these modes are also subjected to a small collective shift and occur at slightly different energies in the two polarization geometries.
Observing different quantum trajectories in cavity QED
Creators: name: Santos, Marcelo França
name: Carvalho, Andre R. R.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The experimental observation of quantum jumps is an example of single open quantum systems that, when monitored, evolve in terms of stochastic trajectories conditioned on measurements results. Here we present a proposal that allows the experimental observation of a much larger class of quantum trajectories in cavity QED systems. In particular, our scheme allows for the monitoring of engineered thermal baths that are crucial for recent proposals for probing entanglement decay and also for entanglement protection. The scheme relies on the interaction of a three-level atom and a cavity mode that interchangeably play the roles of system and probe. If the atom is detected the evolution of the cavity fields follows quantum trajectories and vice-versa.
description: 5 pages, 2 figures