Influence of interlayer tunneling on the quantized Hall phases in intentionally disordered multilayer structures

Stability of the quantized Hall phases is studied in weakly coupled multilayers as a function of the interlayer correlations controlled by the interlayer tunneling and by the random variation of the well thicknesses. A strong enough interlayer disorder destroys the symmetry responsible for the quantization of the Hall conductivity, resulting in the breakdown of the quantum Hall effect. A clear difference between the dimensionalities of the metallic and insulating quantum Hall phases is demonstrated. The sharpness of the quantized Hall steps obtained in the coupled multilayers with different degrees of randomization was found consistent with the calculated interlayer tunneling energies. The observed width of the transition between the quantized Hall states in random multilayers is explained in terms of the local fluctuations of the electron density.

Compressibility of electron liquid in the quantized Hall phase of GaAs/AlGaAs multi-layers

Magneto-capacitance was studied in narrow miniband GaAs/AlGaAs superlattices where quasi-two dimensional electrons revealed the integer quantum Hall effect. The interwell tunneling was shown to reduce the effect of the quantization of the density of states on the capacitance of the superlattices. In such case the minimum of the capacitance observed at the filling factor nu = 2 was attributed to the decrease of the electron compressibility due to the formation of the incompressible quantized Hall phase. In accord with the theory this phase was found strongly inhomogeneous. The incompressible fraction of the quantized Hall phase was demonstrated to rapidly disappear with the increasing temperature. (C) 2008 Elsevier B.V. All rights reserved.

Spectroscopic evidence of extended states in quantized Hall phase of weakly coupled GaAs/AlGaAs multi-layers

The influence of the interlayer coupling on formation of the quantized Hall conductor phase at the filling factor v = 2 was studied in the multi-layer GaAs/AlGaAs heterostructures. The disorder broadened Gaussian photoluminescence line due to the localized electrons was found in the quantized Hall phase of the isolated multi-quantum well structure. On the other hand, the quantized Hall phase of the weakly coupled multi-layers emitted an unexpected asymmetrical line similar to that one observed in the metallic electron systems. We demonstrated that the observed asymmetry is caused by a partial population of the extended electron states formed in the quantized Hall conductor phase due to the interlayer percolation. A sharp decrease of the single-particle scattering time associated with these extended states was observed at the filling factor v = 2. (c) 2007 Elsevier B.V. All rights reserved.

Vi och de andra : En studie av hur män och kvinnor med invandrarbakgrund framställs i svenska invandrarfilmer från år 2000

Syftet med den här uppsatsen har varit att visa hur män och kvinnor med invandrarbakgrund framställs i svenska så kallade invandrarfilmer från år 2000. De frågeställningar jag arbetat utifrån är: Hur porträtteras män samt kvinnor med invandrarbakgrund i de svenska ”invandrarfilmerna” från år 2000? Vilka stereotyper kan man tänkas finna? Har det skett någon förändring i hur män och kvinnor med invandrarbakgrund porträtterats i svensk film? För att få svar på frågorna har jag genomfört textanalyser av fem filmer - Jalla! Jalla! av Josef Fares, Före stormen av Reza Parsa, Vingar av glas av Reza Bagher, Det nya landet av Geir Hansteen Jörgensen samt Bastarderna i paradiset av Luis R. Vera - utifrån teorier om genus, ”ras” och etnicitet. Teorierna har jag hämtat från bland andra Anthony Giddens, Yvonne Hirdman, Laura Mulvey, Paulina de los Reyes, Charles Ramírez Berg och Stuart Hall. Dessutom har jag jämfört filmerna med Rochelle Wrights studie av svenska filmer med invandrarkaraktärer från 1970-1990-talet för att se om det har skett någon förändring i gestaltningen av personer från andra delar av världen. Analyserna har visat att trots att filmerna från år 2000 är regisserade av personer som själva har invandrarbakgrund, så gestaltas invandrarna generellt sätt utifrån grova stereotyper. Det mest framträdande dragen i stereotyperna är att dessa, oavsett kön, gestaltas som avvikande samt som en del i en familjegrupp. Invandrarmän framställs som barnsliga, våldsbenägna, aggressiva samt som förtryckande gentemot kvinnor. Invandrarkvinnor framställs som konstiga, maktlösa, isolerade, okunniga offer samt som underordnad gentemot män. De filmer som delvis avviker, och som därmed uppvisar förändringar jämfört med tidigare filmer, är Före stormen och Det nya landet. I Före stormen har man nämligen kastat om könsrollerna. Invandrarmannen är underordnad gentemot kvinnorna, samtidigt som han gestaltas som en helt vanlig individ. I Det nya landet gestaltar man invandrarmän på ett mer positivt sätt. Fastän dessa gestaltas som grova stereotyper, revideras de på ett påtagligt sätt. De omarbetas genom att man tillskriver invandrare fördjupade egenskaper som är oförutsägbara under filmens gång. Vidare attribuerar man dem en logik som bidrar till att åskådarna nu får tillgång till att se på invandrarmän ur ett annat perspektiv, bortom den ensidiga stereotypbilden.

O modelo de hall para estimação de poder de mercado: uma discussão sobre aplicabilidade nos estudos para a indústria brasileira

None

Applying DEMO to model and automate a process in a workflow system: a case study in a city hall

Organizations are Complex systems. A conceptual model of the enterprise is needed that is: coherent the distinguished aspect models constitute a logical and truly integral comprehensive all relevant issues are covered consistent the aspect models are free from contradictions or irregularities concise no superfluous matters are contained in it essential it shows only the essence of the enterprise, i.e., the model abstracts from all realization and implementation issues. The world is in great need for transparency about the operation of all the systems we daily work with, ranging from the domestic appliances to the big societal institutions. In this context the field of enterprise ontology has emerged with the aim to create models that help to understand the essence of the construction and operation of complete systems; more specifically, of enterprises. Enterprise ontology arises in the way to look through the distracting and confusing appearance of an enterprise right into its deep kernel. This, from the perspective of the system designer gives him the tools needed to design a successful system in a way that’s reflects the desires and needs of the workers of the enterprise. This project’s context is the use of DEMO (Design and Engineering Methodology for Organizations) for (re)designing or (re)engineering of an enterprise, namely a process of the construction department of a city hall, the lack of a well-founded theory about the construction and operation of this processes that was the motivation behind this work. The purpose of studying applying the DEMO theory and method was to optimize the process, automating it as much as possible, while reducing paper and time spent between tasks and provide a better service to the citizens.

Construção de um sistema de caracterização das propriedades de transporte de filmes finos pelo efeito Hall

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Leaf anatomy as a contribution to the taxonomy of Salacioideae N.Hall, ex Thorne & Reveal (Celastraceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Finite-momentum condensate of magnetic excitons in a bilayer quantum Hall system

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Permanent Magnet Hall Thruster for satellite orbit raising with low power energy consumption

Electric propulsion is now a succeful method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Thruster, so called Hall Thruster or SPT (Stationary Plasma Thruster), was primarily conceived in USSR (the ancient Soviet Union) and, since then, it has been developed by space agencies, space research institutes and industries in several countries such as France, USA, Israel, Russian Federation and Brazil. In this work we present the main features of the Permanent Magnet Hall Thruster (PMHT) developed at the Plasma Laboratory of the University of Brasilia. The idea of using an array of permanent magnets, instead of an electromagnet, to produce a radial magnetic field inside the plasma channel of the thruster is very significant. It allows the development of a Hall Thruster with power consumption low enough to be used in small and medium size satellites. Description of a new vacuum chamber used to test the second prototype of the PMHT (PHALL II) will be given. PHALL II has an aluminum plasma chamber and is smaller with 15 cm diameter and will contain rare earth magnets. We will show plasma density and temperature space profiles inside and outside the thruster channel. Ion temperature measurements based on Doppler broadening of spectral lines and ion energy measurements are also shown. Based on the measured plasma parameters we constructed an aptitude figure of the PMHT. It contains the specific impulse, total thrust, propellant flow rate and power consumption necessary for orbit raising of satellites. Based on previous studies of geosyncronous satellite orbit positioning we perform numerical simulations of satellite orbit raising from an altitude of 700 km to 36000 km using a PMHT operating in the 100 mN - 500 mN thrust range. In order to perform these calculations integration techniques were used. The main simulation paraters were orbit raising time, fuel mass, total satellite mass, thrust and exaust velocity. We conclude comparing our results with results obtainned with known space missions performed with Hall Thrusters. © 2008 by the American Institute of Aeronautics and Astronautics, Inc.

Tra[D]ição e o jogo da diferença em Marajó, de Dalcídio Jurandir

Este trabalho, que escolheu como tema a presença da tradição no romance Marajó de Dalcídio Jurandir, procura investigar como a escritura do romance citado dialoga intertextualmente com a tradição literária, mitológica e oral, sem anular o caráter social da ficção dalcidiana. Defendo a hipótese de que o jogo intertextual presente na obra não está a favor de uma exaltação das fontes ou como mera transposição de influências, mas se projeta como diferença. A base teórica do trabalho se fundamentou, sobretudo, a partir das discussões sobre “fonte” e “influência” estabelecidas pela literatura comparada nas figuras de autores como Tania Franco Carvalhal e Silviano Santiago e de algumas considerações de escritores importantes da literatura moderna como T. S. Eliot e Jorge Luis Borges, reconhecidos como os iniciadores das discussões acerca do legado da tradição, retomada pela literatura modernista. A escolha da literatura comparada possibilitou a presente leitura, uma abertura teórica em que entram em cena, na abordagem, a Psicanálise freudiana, a escritura-jogo de Roland Barthes, Júlia Kristeva e Jacques Derrida, além de outros pressupostos analíticos de pesquisadores da ficção de Dalcídio Jurandir como os professores Vicente Salles, Marli Tereza Furtado, Paulo Nunes, Audemaro Taranto Goulart e Pedro Maligo e estudiosos da tradição como Anthony Giddens, Homi Bhabha, Stuart Hall e Walter Benjamin.