236 research outputs found
Gustatory detection thresholds after parabrachial nuclei lesions in rats
No full textRats with either electrolytic (Experiment 1) or excitotoxic lesions (Experiment 2) that had been electrophysiologically centered in the gustatory zone of the parabrachial nuclei (PBN) were tested for sucrose and NaCl taste detection thresholds in a conditioned avoidance task. With 1 exception, all of these rats had previously shown severe deficits in acquiring an LiCl-based conditioned taste aversion (CTA) to sucrose, NaCl, or alanine. The rats with excitotoxic lesions also had failed to express a depletion-induced sodium appetite. Despite the uniformity of these deficits, the rats with lesions exhibited varied performance in the detectability task. Roughly 1/3 of the rats did not perform competently, 1/3 had elevated thresholds, and 1/3 showed no or only marginal impairments in taste detectability. These findings demonstrate that the elimination of CTA following PBN lesions is not necessarily linked to an impairment in taste signal detection. Thus, PBN-induced deficits on 1 taste-related task do not entirely correspond with impairments on another
Magnetooptical properties of semiconductor quantum structures
No full textTitle: Magnetooptical Properties of Semiconductor Quantum Structures Author: Štěpán Uxa Department: Institute of Physics of Charles University Supervisor: Assoc. Prof. Roman Grill, PhD Supervisor's e-mail address: [email protected] Abstract: In this theoretical work, a detailed study of optical properties of excitons in double quantum wells subject to magnetic and electric fields is presented. Starting from the well-known Luttinger formulae describing the real valence-band structure of III-V semi- conductor compounds, we developed an efficient way to solve the Schrödinger equation of a coulombically-bound pair electron-hole forming an exciton. Derived formulae were illus- trated on relevant figures, giving us an opportunity to better understand the effects of external fields on the studied system. Dispersion relations, the shift of energy levels in an electric field, absorption and photoluminescence spectra, and charge density distribution were calculated and achieved results were discussed in detail. Keywords: exciton, double quantum well, coupled quantum wells, Luttinger (-Kohn) hamiltonian, valence-subband mixin
Magnetooptické vlastnosti polovodičových kvantových struktur
No full textNázev práce: Magnetooptické vlastnosti polovodičových kvantových struktur Autor: Štěpán Uxa Katedra: Fyzikální ústav Univerzity Karlovy Vedoucí diplomové práce: doc. RNDr. Roman Grill, CSc. E-mail vedoucího: [email protected] Abstrakt: V této teoretické práci je představena podrobná studie optických vlastností excitonů v dvojitých kvantových jamách umístěných v magnetickém a electrickém poli. Vycházejíce ze známých Luttingerových vztahů popisujících reálnou strukturu valečního pásu polovodičových sloučenin typu III-V, rozvinuli jsme efektivní způsob řešení Schrödin- gerovy rovnice pro coulombicky vázaný pár elektron-díra tvořící exciton. Odvozené vzta- hy byly ilustrovány na odpovídajících obrázcích, dávajíce nám možnost lépe porozumět efektům vnějších polí na studovaný systém. Byly spočteny disperzní relace, posun energe- tických hladin v elektrickém poli, absorpční a luminiscenční spektra i rozložení nábojové hustoty, a dosažené výsledky byly podrobně diskutovány. Klíčová slova: exciton, dvojitá kvantová jáma, vázané kvantové jámy, Luttingerův (-Kohnův) hamiltonián, míchání stavů ve valenčním pásuTitle: Magnetooptical Properties of Semiconductor Quantum Structures Author: Štěpán Uxa Department: Institute of Physics of Charles University Supervisor: Assoc. Prof. Roman Grill, PhD Supervisor's e-mail address: [email protected] Abstract: In this theoretical work, a detailed study of optical properties of excitons in double quantum wells subject to magnetic and electric fields is presented. Starting from the well-known Luttinger formulae describing the real valence-band structure of III-V semi- conductor compounds, we developed an efficient way to solve the Schrödinger equation of a coulombically-bound pair electron-hole forming an exciton. Derived formulae were illus- trated on relevant figures, giving us an opportunity to better understand the effects of external fields on the studied system. Dispersion relations, the shift of energy levels in an electric field, absorption and photoluminescence spectra, and charge density distribution were calculated and achieved results were discussed in detail. Keywords: exciton, double quantum well, coupled quantum wells, Luttinger (-Kohn) hamiltonian, valence-subband mixingFyzikální ústav UKInstitute of Physics of Charles UniversityFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Mechanisms of top-down facilitation in perception of visual objects studied by fMRI
No full textPrior knowledge regarding the possible identity of an object facilitates its recognition from a degraded visual input, though the underlying mechanisms are unclear. Previous work implicated ventral visual cortex but did not disambiguate whether activity-changes in these regions are causal to or merely reflect an effect of facilitated recognition. We used functional magnetic resonance imaging to study top-down influences on processing of gradually revealed objects, by preceding each object with a name that was congruent or incongruent with the object. Congruently primed objects were recognized earlier than incongruently primed, and this was paralleled by shifts in activation profiles for ventral visual, parietal, and prefrontal cortices. Prior to recognition, defined on a trial-by-trial basis, activity in ventral visual cortex rose gradually but equivalently for congruently and incongruently primed objects. In contrast, prerecognition activity was greater with congruent priming in lateral parietal, retrosplenial, and lateral prefrontal cortices, whereas functional coupling between parietal and ventral visual (and also left lateral prefrontal and parietal) cortices was enhanced in the same context. Thus, when controlling for recognition point and stimulus information, activity in ventral visual cortex mirrors recognition success, independent of condition. Facilitation by top-down cues involves lateral parietal cortex interacting with ventral visual areas, potentially explaining why parietal lesions can lead to deficits in recognizing degraded objects even in the context of top-down knowledge
Optimized approach for CFD simulations of HVAC systems with grill air diffusers
No full textA proper CFD simulation of air distribution within a room requires the correct representation of inlet conditions from ventilation grids. Those elements are usually characterized by blades with a certain inclination angle or even by a curvature, whose correct representation by finite volumes approaches requires the employment of very fine meshes. The coupling of those fine inlet domains with the coarser mesh of the environment can lead to unacceptable costs for common computational resources. In this work, an optimized methodology is presented to simulate the inlet flow conditions of an air diffuser within a bigger environment, like a room or a transport vehicle cabin. The method aims at reducing the computational cost of CFD simulations, by solving the velocity field of the diffuser in a local domain, and then mapping this velocity to the surrounding domain. Additionally, this allows us to solve the diffuser only once and reuse the velocity field multiple times for different room configurations.The author Jordi Vera has been financially supported by the Ministerio de Educación y Ciencia (MEC), Spain, (FPI grant PRE2018-084017). The author E.Schillaci acknowledges the financial support of the Programa Torres Quevedo (PTQ2018-010060).Postprint (published version
Judith Cohen, art historian and author of Cowtown Moderne
No full textAuthor and art historian Judith (Judy) Cohen sits on a reproduction Le Corbusier chaise from her personal collection of Art Deco style pieces. The railing seen behind her is made from a decorative grill from the restaurant in the Striplings building and the grate on the wall in the background is from the Aviation Building, which was located at Seventh and Main streets. She is the author of the book Cowtown Moderne.https://mavmatrix.uta.edu/specialcollections_startelegram1990s/1123/thumbnail.jp
Louis Adamic and Vatro Grill: a partnership of equals?
No full textIn 1956 Anton Melik, Professor of Geography at the University of Ljubljana, published a travelogue Amerika in ameriska Slovenija (America and American Slovenia). The author points out in his "notes" the pride of American people regarding their ·achievements, social and racial antagonisms which exist in the United States, and the fate of Slovene immigrants who must have found it difficult "to establish for themselves an equal position with other immigrants and old settlers due to their insufficient education and lack of knowledge of English".' A large part of Melik's book is devoted to his encounters with American Slovenes. Among them he also mentions his conversations with Vatro Gril, who knew Louis Adamic well and was a close friend of his. Melik says that Adamic and Grill were members of the same generation, they even attended the same secondary school in Ljubljana and they left for America in the same year, in 1913. When they met they discovered that they had the same or very similar views upon problems Slovene immigrants had in America. Melik also suggests that when a book is going to be written about Louis Adamic, Grill is the right person to contribute to it
Photo-Hall effect spectroscopy and laser-induced transient currents in CdTe-based semiconductor radiation detectors
No full textTitle: Photo-Hall effect spectroscopy and laser-induced transient currents in CdTe-based semiconductor radiation detectors Author: Artem Musiienko Department / Institute: Institute of Physics, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Prof. RNDr. Roman Grill, CSc, Institute of Physics, Faculty of Mathematics and Physics, Charles University Abstract: Cadmium Telluride, Cadmium Zinc Telluride, and Cadmium Manganese Telluride are important semiconductors with applications in radiation detection, solar cells, and electro-optic modulators. Their electrical and optical properties are principally controlled by defects forming energy levels within the bandgap. Such defects create recombination and trapping centers capturing photo- created carriers and depreciating the performance of the detector. Simultaneously, the changed occupancy of levels leads to the charging of detector's bulk, which results in the screening of applied bias and the loss of detector's sensitivity. Detailed knowledge of crystal defect structure is thus necessary for the predictable detector work and also for the possibility to reduce the structural defects concentration. This thesis reports on the investigation of deep energy levels in CdTe-based high resistivity and detector-grade materials by..
Judith Cohen, art historian and author of Cowtown Moderne
No full textAuthor and art historian Judith (Judy) Cohen sits on a reproduction Le Corbusier chaise from her personal collection of Art Deco style pieces. The railing seen behind her is made from a decorative grill from the restaurant in the Striplings building and the grate on the wall in the background is from the Aviation Building, which was located at Seventh and Main streets. She is seen holding her book Cowtown Moderne in her lap.https://mavmatrix.uta.edu/specialcollections_startelegram1990s/1122/thumbnail.jp
The author, a self-confessed martini snob, evaluates Chicky\u27s Fine Diner in We
No full textThe author, a self-confessed martini snob, evaluates Chicky\u27s Fine Diner in Westbrook and nine places in Portland that serve memorable martinis, including: Katahdin Restaurant, Una Wine Bar and Lounge, the Armory Lounge at the Portland Regency, David\u27s Restaurant, Village Cafe, Top of the East, Fore Street, Old Port Sea Grill, and Street & Company
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