Particle Creation by a Moving Boundary with Robin Boundary Condition

We consider a massless scalar field in 1+1 dimensions satisfying a Robin boundary condition (BC) at a non-relativistic moving boundary. We derive a Bogoliubov transformation between input and output bosonic field operators, which allows us to calculate the spectral distribution of created particles. The cases of Dirichlet and Neumann BC may be obtained from our result as limiting cases. These two limits yield the same spectrum, which turns out to be an upper bound for the spectra derived for Robin BC. We show that the particle emission effect can be considerably reduced (with respect to the Dirichlet/Neumann case) by selecting a particular value for the oscillation frequency of the boundary position

An alternative theoretical approach to describe planetary systems through a Schrodinger-type diffusion equation

In the present work we show that planetary mean distances can be calculated with the help of a Schrodinger-type diffusion equation. The obtained results are shown to agree with the observed orbits of all the planets and of the asteroid belt in the solar system, with only three empty states. Furthermore, the equation solutions predict a fundamental orbit at 0.05 AU from solar-type stars, a result confirmed by recent discoveries. In contrast to other similar approaches previously presented in the literature, we take into account the flatness of the solar system, by considering the flat solutions of the Schrodinger-type equation. The model has just one input parameter, given by the mean distance of Mercury.Comment: 6 pages. Version accepted for publication in Chaos, Solitons & Fractal

Inertial forces in the Casimir effect with two moving plates

We combine linear response theory and dimensional regularization in order to derive the dynamical Casimir force in the low frequency regime. We consider two parallel plates moving along the normal direction in $D-$dimensional space. We assume the free-space values for the mass of each plate to be known, and obtain finite, separation-dependent mass corrections resulting from the combined effect of the two plates. The global mass correction is proportional to the static Casimir energy, in agreement with Einstein's law of equivalence between mass and energy for stressed rigid bodies.Comment: 9 pages, 1 figure; title and abstract changed; to appear in Physical Review

Dynamical Casimir effect with cylindrical waveguides

I consider the quantum electromagnetic field in a coaxial cylindrical waveguide, such that the outer cylindrical surface has a time-dependent radius. The field propagates parallel to the axis, inside the annular region between the two cylindrical surfaces. When the mechanical frequency and the thickness of the annular region are small enough, only Transverse Electromagnetic (TEM) photons may be generated by the dynamical Casimir effect. The photon emission rate is calculated in this regime, and compared with the case of parallel plates in the limit of very short distances between the two cylindrical surfaces. The proximity force approximation holds for the transition matrix elements in this limit, but the emission rate scales quadratically with the mechanical frequency, as opposed to the cubic dependence for parallel plates.Comment: 6 page

Uso de modelos lineares generalizados para estimar germinação carpogênica de escleródios de S. sclerotioroum.

Sclerotinia sclerotiorum é um fungo que tem causado epidemias de mofo branco em diversas regiões do país. Apotécios, produzidos através da germinação carpogênica de escleródios são considerados o inóculo inicial da doença. O objetivo deste estudo foi desenvolver um modelo de previsão para produção de apotécios em laboratório, determinando as relações entre temperatura do solo (10, 13, 15, 18, 20, 23, 25 e 30º C), umidade do solo (61, 68, 75, 82, 89, 95, 100, 105, 110, 115 e 120 % da capacidade de campo, CC) e escleródios germinados. O experimento foi conduzido em delineamento inteiramente aleatorizado, com arranjo fatorial 8 x 11 e quatro repetições. As parcelas foram compostas por 20 escleródios dispostos sobre 150g de solo, em embalagens de plástico transparente de 500g. Foi ajustado um modelo de linear generalizado com função de ligação logística (?logit?), considerando a distribuição binomial (regressão logística) para estimar a probabilidade de germinação de escleródios em função da umidade e da temperatura do solo. A qualidade do ajuste foi avaliada pela ?deviance?, correlações entre valores observados e preditos pelo modelo e pelo padrão gráfico dos resíduos. Apesar da forte evidência de efeito dos preditores linear e quadrático para ambos os fatores, o modelo proposto apresentou qualidade de ajuste regular, o que indica necessidade de melhoria. Segundo esse modelo, condições de temperatura entre 15° e 17°C e umidades próximas de 100% CC são mais favoráveis à germinação de escleródios, em condições de ambiente controlado