Impact on human health of Salmonella spp. on pork in The Netherlands and the anticipated effects of some currently proposed control strategies

Cell-cell and cell-extracellular matrix interactions are fundamental processes involved in cell migration and tissue remodeling. Both the cyclic regeneration of the human endometrium during the menstrual cycle as well as the process of embryo implantation involve such dynamic interactions. It has become quite clear that integrin adhesion molecules expressed on the surface of cells play critical roles in the transmission of signals from the extracellular milieu to the cells. It is these signals that presumably regulate the behavior of these cells during major morphogenetic processes. In recent years, work in human endometrium and trophoblasts has uncovered both the regulated and constitutive expression of integrin subunits and their extracellular matrix ligands in these tissues. In addition, attempts have been made to correlate pathological states related to either infertility or abnormal pregnancy to the aberrant expression of several of these integrins. The purpose of the present review is to describe briefly our present state of knowledge of the expression of integrins in human endometrium and trophoblasts and provide the reader with the necessary background needed to understand, at the cellular and molecular levels, processes in reproduction such as embryo implantation.     

Radiation from curved single-mode fibres

A study of propagation in curved single-mode fibres shows that the transmission loss increases sharply below a critical bend radius. However the radiation does not leak away uniformly with distance but in a series of discrete well-defined rays.     

Analytic solution for the birefringence produced by thermal stress in polarization-maintaining optical fibers

Polarization-maintaining optical fibers are usually made by inducing a large anisotropic thermal stress in the core so that it appears highly birefringent. A simple analytic solution has been found for the birefringence in terms of the cross-sectional distribution of the high-expansion material used to create the thermal stress. The analysis is able to predict optimal structures which efficiently utilize the available stress and thus maximize the birefringence. It is shown that the optimum structure has a cross-sectional geometry resembling a bow-tie. Design rules are given whereby the dimensions may be chosen and these are verified in a simple experiment.     

Allocation of freeway ramp metering volumes to optimize corridor performance

A simple macroscopic freeway traffic corridor model is formulated for the purpose of developing optimal allocations of freeway on-ramp metering volumes. The model represents a freeway and a single parallel "equivalent surface street," both unidirectional, which are interconnected by freeway on-ramps. Since a choice of routes is included in the problem formulation, the fairly standard methodology of "traffic assignment" is employed to predict how drivers will react to the on-ramp metering. An explicit traffic assignment algorithm which includes ramp queueing is developed. Both the corridor and traffic assignment models are restricted to stationary traffic patterns. Two specific corridor performance criteria, freeway travel rate and total travel-time rate, are formulated in terms of the model variables. Then the problem of choosing ramp metering volumes to optimize a performance criterion is posed. A computationally efficient suboptimal dynamic programming scheme is developed and illustrated by an example.     

The relationship between overinclusive thinking, perceptual rigidity, and the discrimination learning of new concepts.

Compared 19 newly admitted psychiatric inpatients who showed overinclusive thinking on the Payne Object Classification Test with 24 patients matched for age, IQ, and abstraction ability who were not overinclusive. In a concept-attainment experiment, contrary to prediction, overinclusive Ss did not learn overinclusive concepts. There were no significant differences between the groups. However, overinclusive Ss, as predicted, showed an abnormal lack of "Einstellung" rigidity as measured by a flexibility score from the Brengelmann Picture Recognition Test. The overinclusion score of the object classification test correlated highly (.90) with this flexibility score. (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction factors for the determination of optical-fibre refractive-index profiles by the near-field scanning technique

Numerical calculations are presented of the correction factor for use with the near-field scanning method of index profile determination. It is shown that a single curve can be applied to a range of possible profiles, and a numerically obtained average curve is given.     

Space psychology and the inner sanctums.

Comments that a report by Rohles in the "American Psychologist" (1960, 15, 668-669) describes a facility for training animals in order to obtain behavioral data in space flight. The present authors feel that such a facility is indeed potentially an important part of psychology's effort in manned space flight programs. However, Rohles's report is said to contain factual errors which create the impression that, up until now, psychology has been asleep on the launching pad. The authors refer primarily to the first two paragraphs of the report, and will comment on three points. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Finite-Difference Time-Domain Method for the Simulation of Gain Materials With Carrier Diffusion in Photonic Crystals

In this paper, we present a finite-difference time-domain formulation for active gain materials. Our scheme is based on a frequency-dependent conductivity. Experimental material gain is fitted with high accuracy to a multipole Lorentzian model using a semideterministic fitting algorithm. Because our model is an approximation to the full vectorial Maxwell's system of equations, we include carrier diffusion into the rate equations for a two-level system. The material gain is included into the standard set of Maxwell's equations by linking the frequency-dependent conductivity to the rate equations. Lasing is demonstrated for a vertical-cavity-surface-emitting-laser structure and photonic crystal lasers.