Four-level systems and a universal quantum gate

We discuss the possibility of implementing a universal quantum XOR gate by using two coupled quantum dots subject to external magnetic fields that are parallel and slightly different. We consider this system in two different field configurations. In the first case, parallel external fields with the intensity difference at each spin being proportional to the time-dependent interaction between the spins. A general exact solution describing this system is presented and analyzed to adjust field parameters. Then we consider parallel fields with intensity difference at each spin being constant and the interaction between the spins switching on and off adiabatically. In both cases we adjust characteristics of the external fields (their intensities and duration) in order to have the parallel pulse adequate for constructing the XOR gate. In order to provide a complete theoretical description of all the cases, we derive relations between the spin interaction, the inter-dot distance, and the external field. (C) 2008 WILEYNCH Verlag GmbH & Co. KGaA. Weinheim.

Energy-momentum tensor in thermal strong-field QED with unstable vacuum

Themean value of the one-loop energy-momentum tensor in thermal QED with an electric-like background that creates particles from vacuum is calculated. The problem is essentially different from calculations of effective actions ( similar to the action of Heisenberg-Euler) in backgrounds that respect the stability of vacuum. The role of a constant electric background in the violation of both the stability of vacuum and the thermal character of particle distribution is investigated. Restrictions on the electric field and the duration over which one can neglect the back-reaction of created particles are established.

Etniska stereotyper på film : med utgångspunkt i amerikansk film med ryska motiv (2008-2011)

Filmmediet idag är den mest populära formen av masskultur. Med sin världstäckande genomslagskraft och sitt stereotypa porträtterande av verklighet, påverkar filmen världsåskådningen för människor runtom i världen. Ett brinnande ämne i amerikansk film har alltid varit Ryssland, på grund av de politiska motsättningarna och den historiska rivaliteten med USA. Studiens syfte är att undersöka hur Ryssland porträtteras i amerikanska filmer från perioden för presidenterna Dmitrij Medvedevs respektive Barack Obamas första mandatperiod. Frågeställningen för uppsatsen är: hur ser stereotypa föreställningar om Ryssland ut i amerikansk film 2008-2011? Trettiotal filmer med ryska motiv valdes ut för undersökningen och analyserades utifrån de visuella och sociala aspekterna. Resultatet visar på att det förekommer tre skikt av stereotyper om Ryssland: de eviga, som har existerat i hundratals år och spridits av resenärer; stereotyper från epoken för det kalla kriget; och stereotyper om det moderna Ryssland inspirerade av medias nyhetsrapporteringar.

Duality-symmetric eleven-dimensional supergravity and its coupling to M-branes

The standard eleven-dimensional supergravity action depends on a three-form gauge field and does not allow direct coupling to five-branes. Using previously developed methods, we construct a covariant eleven-dimensional supergravity action depending on a three-form and six-form gauge field in a duality-symmetric manner. This action is coupled to both the M-theory two-brane and five-brane, and corresponding equations of motion are obtained. Consistent coupling relates D = 11 duality properties with self-duality properties of the M5-brane. From this duality-symmetric formulation, one derives an action describing coupling of the M-branes to standard D = 11 supergravity. © 1998 Elsevier Science B.V.

Climate change in Latin America: impacts and mitigation policy options

Includes bibliography.

A publicidade na canção: diversão como sedução de solução

This article intends to cause reflection on the advertisement strategy applied by Fernanda Abreu (FA) in order to understand the song “Disco Club 2 (Melo Radical)” from the album SLA radical dance disco club by FA. The composition seduces the subjects involved in the song process to listen to it somehow. The analysis is based on chronotopy, conception developed by the Bakhtin, Medvedev and Volochinov Circle. The idea carried by the song is a meeting at night at a funk club where FA is with other people. Therefore, the song becomes its own advertisement as a product of consumerism.

Pérola gera arte: (re)ações entre gêneros

This paper is part of a larger project. The purpose of this paper is to discuss the movie Girl With a Pearl Earring (2003) by Peter Webber using the theoretical perspective of dialogue from the Bakhtin Circle, Medved, Volochinov. The multidisciplinary and interartistic potential of cinema is considered in this paper when the linguistic organization and the translinguistic elements in the corpus are focused on and understood as an example of cinema genre as discussed in the Russian Circle. The study of the ways of incorporation of different genericities by cinema, illustrated by the dialogues between the pictorial genre, the novel and the movies contribute to the recognition of the cinema as a genre that is composed by the incorporation of other genres. The construction of the cinematographic work in analysis will be regarded in its architectonic (form, content and style) and in the activity field in which it circulates.

Purification and characterization of aprotinin from porcine lungs

Aprotinin, the most studied serine proteinase inhibitor, was isolated from porcine lung for the first time. The purified porcine aprotinin had an Mr value of similar to 7 kDa. It cross- reacted with polyclonal serum anti- commercial aprotinin. About 1 mu g porcine aprotinin inhibited 6 mu g trypsin whereas 1 mu g commercial soybean inhibitor inhibited only 1 mu g trypsin. The aprotinin gene was also isolated from porcine lung: the deduced amino acid sequence showed 74% identity to bovine aprotinin.

Nonlinear (magnetic) correction to the field of a static charge in an external field

We find the first nonlinear correction to the field produced by a static charge at rest in a background constant magnetic field. It is quadratic in the charge and purely magnetic. The third-rank polarization tensor-the nonlinear response function-is written within the local approximation of the effective action in an otherwise model-and approximation-independent way within any P-invariant nonlinear electrodynamics, QED included. DOI: 10.1103/PhysRevD.86.125028