844 resultados para Modular and Semisimple Group Algebras


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A construction relating the structures of super Lie and super Jordan algebras is proposed. This may clarify the role played by field theoretical realizations of super Jordan algebras in constructing representations of super Kač-Moody algebras. The case of OSP(m, n) and super Clifford algebras involving independent Fermi fields and symplectic bosons is discussed in detail.

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Starting from the Schwinger unitary operator bases formalism constructed out of a finite dimensional state space, the well-known q-deformed commutation relation is shown to emerge in a natural way, when the deformation parameter is a root of unity.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Let D be a division ring with center k, and let D-dagger be its multiplicative group. We investigate the existence of free groups in D-dagger, and free algebras and free group algebras in D. We also go through the case when D has an involution * and consider the existence of free symmetric and unitary pairs in D-dagger.

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We present a simultaneous optical signal-to-noise ratio (OSNR) and differential group delay (DGD) monitoring method based on degree of polarization (DOP) measurements in optical communications systems. For the first time in the literature (to our best knowledge), the proposed scheme is demonstrated to be able to independently and simultaneously extract OSNR and DGD values from the DOP measurements. This is possible because the OSNR is related to maximum DOP, while DGD is related to the ratio between the maximum and minimum values of DOP. We experimentally measured OSNR and DGD in the ranges from 10 to 30 dB and 0 to 90 ps for a 10 Gb/s non-return-to-zero signal. A theoretical analysis of DOP accuracy needed to measure low values of DGD and high OSNRs is carried out, showing that current polarimeter technology is capable of yielding an OSNR measurement within 1 dB accuracy, for OSNR values up to 34 dB, while DGD error is limited to 1.5% for DGD values above 10 ps. For the first time to our knowledge, the technique was demonstrated to accurately measure first-order polarization mode dispersion (PMD) in the presence of a high value of second-order PMD (as high as 2071 ps(2)). (C) 2012 Optical Society of America

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La tesi è dedicata allo studio delle rappresentazioni delle algebre di Lie semisemplici su un campo algebricamente chiuso di caratteristica zero. Mediante il teorema di Weyl sulla completa riducibilità, ogni rappresentazione di dimensione finita di una algebra di Lie semisemplice è scrivibile come somma diretta di sottorappresentazioni irriducibili. Questo permette di poter concentrare l'attenzione sullo studio delle rappresentazioni irriducibili. Inoltre, mediante il ricorso all'algebra inviluppante universale si ottiene che ogni rappresentazione irriducibile è una rappresentazione di peso più alto. Perciò è naturale chiedersi quando una rappresentazione di peso più alto sia di dimensione finita ottenendo che condizione necessaria e sufficiente perché una rappresentazione di peso più alto sia di dimensione finita è che il peso più alto sia dominante. Immediata è quindi l'applicazione della teoria delle rappresentazioni delle algebre di Lie semisemplici nello studio delle superalgebre di Lie, in quanto costituite da un'algebra di Lie e da una sua rappresentazione, dove viene utilizzata la tecnica della Z-graduazione che viene utilizzata per la prima volta da Victor Kac nello studio delle algebre di Lie di dimensione infinita nell'articolo ''Simple irreducible graded Lie algebras of finite growth'' del 1968.

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Zarna is witness to the disappearance of the Swabian community in Santana, a process which seems to date back to before the major changes in Central and Eastern Europe. His project showed how a strong German ethnic community, formed more than 250 years ago, has virtually disappeared from the village of Santana (Romania). Zarna presents the causes leading to the loss of their ethnic identity, of their culture, traditions and of the collective reproduction of their ethnicity, although the last Swabians remaining in the village have preserved their individual identity and not let themselves be assimilated. The policy of the former communist regime is not sufficient to explain the decline of the German ethnic group, nor is the present international context with its varying effects on the form and reproduction of their ethnic identity. Zarna has analysed the origins of the Swabian community, its development, historical changes (both desired and imposed) and the disappearance of elements that determined their German culture and their pride in being German. The Germans have demobilised more rapidly than other ethnic groups in Romania, partly because of Germany's pro-emigration policy over the last two decades. Many of the emigrants were however, poorly prepared for emigration and have not been able to recreate the prosperous financial situation which they left. The prevalent feeling among those interviewed was disappointment and this increases with age and education.

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We validate, extend, and empirically and theoretically criticize the cultural dimension of humane orientation of the project GLOBE (Global Leadership and Organizational Behavior Effectiveness Research Program). Theoretically, humane orientation is not just a one-dimensionally positive concept about being caring, altruistic, and kind to others as discussed by Kabasakal and Bodur (2004), but there is also a certain ambivalence to this concept. We suggest differentiating humane orientation toward in-group members from humane orientation toward out-group members. A multicountry construct validation study used student samples from 25 countries that were either high or low in humane orientation (N = 876) and studied their relation to the traditional GLOBE scale and other cultural-level measures (agreeableness, religiosity, authoritarianism, and welfare state score). Findings revealed a strong correlation between humane orientation and agreeableness, welfare state score, and religiosity. Out-group humane orientation proved to be the more relevant subfacet of the original humane orientation construct, suggesting that future research on humane orientation should make use of this measure instead of the vague original scale. The ambivalent character of out-group humane orientation is displayed in its positive correlation to high authoritarianism. Patriotism was used as a control variable for noncritical acceptance of one’s society but did not change the correlations. Our findings are discussed as an example of how rigid expectations and a lack of tolerance for diversity may help explain the ambivalent nature of humane orientation

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Thigmomorphogenesis, the characteristic phenotypic changes by which plants react to mechanical stress, is a widespread and probably adaptive type of phenotypic plasticity. However, little is known about its genetic basis and population variation. Here, we examine genetic variation for thigmomorphogenesis within and among natural populations of the model system Arabidopsis thaliana. Offspring from 17 field-collected European populations was subjected to three levels of mechanical stress exerted by wind. Overall, plants were remarkably tolerant to mechanical stress. Even high wind speed did not significantly alter the correlation structure among phenotypic traits. However, wind significantly affected plant growth and phenology, and there was genetic variation for some aspects of plasticity to wind among A. thaliana populations. Our most interesting finding was that phenotypic traits were organized into three distinct and to a large degree statistically independent covariance modules associated with plant size, phenology, and growth form, respectively. These phenotypic modules differed in their responsiveness to wind, in the degree of genetic variability for plasticity, and in the extent to which plasticity affected fitness. It is likely, therefore, that thigmomorphogenesis in this species evolves quasi-independently in different phenotypic modules.

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Rhinoviruses (RVs) are associated with exacerbations of cystic fibrosis (CF), asthma and COPD. There is growing evidence suggesting the involvement of the interferon (IFN) pathway in RV-associated morbidity in asthma and COPD. The mechanisms of RV-triggered exacerbations in CF are poorly understood. In a pilot study, we assessed the antiviral response of CF and healthy bronchial epithelial cells (BECs) to RV infection, we measured the levels of IFNs, pattern recognition receptors (PRRs) and IFN-stimulated genes (ISGs) upon infection with major and minor group RVs and poly(IC) stimulation. Major group RV infection of CF BECs resulted in a trend towards a diminished IFN response at the level of IFNs, PRRs and ISGs in comparison to healthy BECs. Contrary to major group RV, the IFN pathway induction upon minor group RV infection was significantly increased at the level of IFNs and PRRs in CF BECs compared to healthy BECs.