Persistent random walk model for transport trough thin slabs

We present a model for transport in multiply scattering media based on a three-dimensional generalization of the persistent random walk. The model assumes that photons move along directions that are parallel to the axes. Although this hypothesis is not realistic, it allows us to solve exactly the problem of multiple scattering propagation in a thin slab. Among other quantities, the transmission probability and the mean transmission time can be calculated exactly. Besides being completely solvable, the model could be used as a benchmark for approximation schemes to multiple light scattering

On the Role of Biomedical Knowledge in Clinical Reasoning by Experts, Intermediates and Novices

In two studies the role of biomedical knowledge in the diagnosis of clinical cases was explored. Experiment 1 demonstrated a decrease in the use of biomedical knowledge with increasing expertise. This result appeared to be at variance with some findings reported in the literature (e.g., Lesgold, 1984), but supported those of others (e.g., Patel, Evans, & Groen, 1989). In Experiment 2, three possible explanations for this phenomenon were investigated: (1) rudimentation of biomedical knowledge, (2) inertia, and (3) encapsulation of biomedical knowledge under higher order concepts. Using a combined think-aloud and post-hoc explanation methodology, it was shown that experts have more in-depth biomedical knowledge than

Casein fractions of ultra high temperature milk with different somatic cell counts Frações de caseína de leite longa-vida com diferentes contagens de células somáticas

The objective of this work was to evaluate the effect of somatic cell counts (SCC) in casein fractions of ultra high temperature (UHT) milk. Raw milks were categorized in SCC groups of low (200,000-320,000 cells mL-1), intermediate (380,000-560,000 cells mL-1) and high cells (600,000-800,000 cells mL-1). Five replicates of UHT milks within each SCC category were analyzed for casein fractions after 8, 30, 60, 90 and 120 days of storage through high performance liquid chromatography. SCC showed effect only on beta-casein reduction. SCC in raw milk increases the proteolysis of UHT milk, as a consequence of beta-casein degradation.<br>O objetivo deste estudo foi avaliar o efeito da contagem de células somáticas (CCS) do leite nas frações de caseína do leite longa-vida. Os leites crus foram categorizados em grupos de CCS de baixa (200.000-320.000 células mL-1 ), intermediária (380.000-560.000 células mL-1 ) e alta contagem (600.000-800.000 células mL-1 ). Cinco lotes de leite longa-vida, em cada categoria de CCS, foram analisados por cromatografia líquida de alta eficiência quanto às frações de caseína, após 8, 30, 60, 90 e 120 dias de armazenamento. A CCS apresentou efeito somente sobre a beta-caseína. A alta CCS no leite cru aumenta a proteólise do leite longa-vida, como conseqüência da degradação da beta-caseína