Studies on elemental composition and antioxidant capacity in callus cultures and native plants of Vaccinium myrtillus L. local populations

The biological and medical effects of bilberry fruit (Vaccinium myrtillus L.) are mainly due to high anthocyanin content of tissues. Calli containing anthocyanins, derived from bilberry plants, may represent a potential source of natural colouring matter, pharmaceutical and natural antioxidants. In the present study we investigated the occurrence of differences in elemental composition and antioxidant capacity of the three local populations of mountain bilberry collected in the western region of Romania (Arieseni, Retezat and Sebes Valley) in order to compare the anthocyanin production of plant and callus tissues originated from various plant populations. It was found that K, Fe and Zn content was higher in calli than in intact plant leaves. The excess of latter two microelements, Fe and Zn can induce oxidative stress, and, as a result of the accumulation of reactive oxygen species, various antioxidant mechanisms. The total antioxidant capacity of callus cultures determined by FRAP method (ferric reducing antioxidant power) could be enhanced as a function of increasing adenine sulphate (AS) concentration in the culture medium and it depended on the origin of mother plants. The leaves of intact plants contained higher amount of total non-protein sulfhydryl groups than calli, and the decrease was especially significant in tissue cultures originated from the Retezat region. In contrast, depending on the AS concentration, the anthocyanin content could increase in callus cultures. The tissues originated from various populations exhibited different AS concentration optimum. This suggests that bilberry callus cultures can be a suitable source of the anthocyanins

Superluminal Signals: Causal Loop Paradoxes Revisited

Recent results demonstrating superluminal group velocities and tachyonic dispersion relations reopen the question of superluminal signals and causal loop paradoxes. The sense in which superluminal signals are permitted is explained in terms of pulse reshaping, and the self-consistent behavior which prevents causal loop paradoxes is illustrated by an explicit example.Comment: 6 pages, 3 figure

Superluminal solutions to the Klein-Gordon equation and a causality problem

We present a new axially symmetric monochromatic free-space solution to the Klein-Gordon equation propagating with a superluminal group velocity and show that it gives rise to an imaginary part of the causal propagator outside the light cone. We address the question about causality of the spacelike paths and argue that the signal with a well-defined wavefront formed by the superluminal modes would propagate in vacuum with the light speed.Comment: to be published in Physics Letters A, an additional reference to the paper by Buttiker and Washbur

DOCÊNCIA NA EDUCAÇÃO SUPERIOR: POLÍTICAS CONTEMPORÂNEAS DE FORMAÇÃO NO BRASIL

A pesquisa propõe compreender a educação como uma política pública e, na perspectiva de construção da governamentalidade de Estado, inquirir as políticas nacionais de formação docente para o Ensino Superior. O objetivo, por sua vez, consiste em investigar as diferentes configurações para a formação docente adotadas nos programas stricto sensu das Universidades do Sistema Associação Catarinense das Fundações Educacionais - ACAFE. Na fase inicial, a pesquisa foi documental na medida em que recorreu aos documentos (MEC-CAPES) e aos sites dos Programas de Pós-Graduação investigados. No entanto, apesar de configurar-se menos como um modo de tratamento dos dados e mais como uma análise, o método de pesquisa é genealógico na medida em que constitui-se como um modo de interpretação assentado nas contribuições teóricas de Michel Foucault. Considera-se que as políticas públicas educacionais brasileiras vieram numa linha de continuidade e descontinuidades, e que a formação docente foi governamentalizada pela ação de biopolíticas que orientaram políticas públicas específicas. No caso da ACAFE, as disparidades estão presentes no que tange ao oferecimento de disciplinas e estágios docentes, quando não ausente a formação docente

Which group velocity of light in a dispersive medium?

The interaction between a light pulse, traveling in air, and a generic linear, non-absorbing and dispersive structure is analyzed. It is shown that energy conservation imposes a constraint between the group velocities of the transmitted and reflected light pulses. It follows that the two fields propagate with group velocities depending on the dispersive properties of the environment (air) and on the transmission properties of the optical structure, and are one faster and the other slower than the incident field. In other words, the group velocity of a light pulse in a dispersive medium is reminiscent of previous interactions. One example is discussed in detail.Comment: To be submitted on PR

Detection of vorticity in Bose-Einstein condensed gases by matter-wave interference

A phase-slip in the fringes of an interference pattern is an unmistakable characteristic of vorticity. We show dramatic two-dimensional simulations of interference between expanding condensate clouds with and without vorticity. In this way, vortices may be detected even when the core itself cannot be resolved.Comment: 3 pages, RevTeX, plus 6 PostScript figure