First passages in bounded domains: When is the mean first passage time meaningful?

We study the first passage statistics to adsorbing boundaries of a Brownian motion in bounded two-dimensional domains of different shapes and configurations of the adsorbing and reflecting boundaries. From extensive numerical analysis we obtain the probability P(\omega) distribution of the random variable \omega=\tau_1/(\tau_1+\tau_2), which is a measure for how similar the first passage times \tau_1 and \tau_2 are of two independent realisations of a Brownian walk starting at the same location. We construct a chart for each domain, determining whether P(\omega) represents a unimodal, bell-shaped form, or a bimodal, M-shaped behaviour. While in the former case the mean first passage time (MFPT) is a valid characteristic of the first passage behaviour, in the latter case it is an insufficient measure for the process. Strikingly we find a distinct turnover between the two modes of P(\omega), characteristic for the domain shape and the respective location of absorbing and reflective boundaries. Our results demonstrate that large fluctuations of the first passage times may occur frequently in two-dimensional domains, rendering quite vague the general use of the MFPT as a robust measure of the actual behaviour even in bounded domains, in which all moments of the first passage distribution exist.Comment: 9 pages, 6 figure

Caracterização dos solos em áreas manejadas com bacurizeiros nativos nas mesorregiões do Nordeste paraense e Marajó.

A distribuição geográfica de bacurizeiros (Platonia insignis Mart.) é controlada por fatores naturais e antrópicos que contribuem para sua ocorrência e concentração de populações manejadas desta espécie, nas mesorregiões do Nordeste Paraense e Marajó. Com base nessa hipótese, este trabalho teve como objetivo a caracterização dos solos de sítios com bacurizeiros manejados nestas duas mesorregiões..

Thermal analysis of byproducts from fast-pyrolysis of Eucalyptus flour.

Fast pyrolysis is the thermal decomposition of biomass in the absence of oxygen. This study aims to evaluate thermal analysis of byproducts from fast-pyrolysis of Eucalyptus wood fines. The pyrolysis was conducted in a pilot-scale at 500°C and 100 mm H2O. Charcoal from this process showed high ash content (over than 20%) and incomplete carbonization. Aqueous extract and bio-oil showed similar thermal decomposition events. However, mass percentage decomposed at each temperature was different between these samples.Edição dos Anais do 7º Simpósio de Análise Térmica, 2015, Bauru

Host status of fruit plants to meloidogyne enterolobii.

Edição dos Proceedings do 6th International Congress of Nematology, Cape Town, South Africa, May 2014

Methicillin-resistant Staphylococcus epidermidis carrying biofilm formation genes: detection of clinical isolates by multiplex PCR

Staphylococcus epidermidis is the most prevalent coagulase-negative Staphylococcus (CNS) and is a major cause of hospital bacteremia. Based on 18 reference strains and 149 Staphylococcus clinical strains, used in a novel multiplex PCR method, the aim of this study was to identify S. epidermidis with respect to the sequence of three genes: recN, which encodes a recombination/repair protein, mecA (methicillin resistance), and icaAB, which is involved in biofilm formation. Amplicons of 219 bp (S. epidermidis-recN gene), 154 bp (mecA gene), and 546 bp (icaAB genes) were obtained. Reliableresults were achieved for 100% of the evaluated strains, suggesting that this new multiplex-PCR approach could be useful forthe accurate identification of methicillin-resistant S. epidermidis with the potential to produce biofilm. [Int Microbiol 2011;14(1):13-17