Influence of SiC reinforcement on precipitation and hardening of a metal matrix composite

The influence of fibre reinforcement (10 vol % SiC fibres) on the precipitation and hardening behaviour of a metal matrix composite was studied using microhardness tests and transmission electron microscopy observations. It was shown that the hardening kinetics is enhanced by the SiC reinforcement due to the fact that precipitation preferentially develops on dislocation lines. Moreover, the high-temperature deformation strongly increases the precipitation rate as the material is reinforced.     

Studies on the mechanism of the ursodeoxycholic acid-induced increase in hepatic low-density lipoprotein binding

Previously, we have shown, in golden Syrian hamsters, that chronic feeding of ursodeoxycholic acid (UDCA), in contrast to that of its 7α-epimer, chenodeoxycholic acid (CDCA), produced a significant increment in hepatic low-density lipoprotein (LDL) uptake, despite similar suppression of bile acid synthesis by both bile acids. Evidence for a direct effect of this bile acid on hepatic LDL metabolism was shownin vitro, with isolated hamster hepatocytes, suggesting that this effect was unique to UDCA and specific for receptor-mediated LDL catabolism. The aim of the present study was to define the cellular mechanism(s) associated with this phenomenon, using male golden Syrian hamsters. Regardless of chronic exposure of the liver to either UDCA or CDCA, acute incubation with UDCA consistently resulted in an increase of LDL binding to isolated hepatocytes by 15 to 40%. Furthermore, chronic treatment with either UDCA or CDCA did not result in alterations in lipoprotein particle composition. Likewise, incubation of hepatocytes with UDCA was not associated with a change of the membrane lipid composition. In isolated liver membrane fractions, UDCA increased both the maximum number of LDL binding sites and the affinity constant for LDL by around 35% suggesting an interaction of UDCA with the LDL receptor, at the plasma membrane level, independent of an effect on receptor cycling. The results of the studies support a role for UDCA in the recruitment of cryptic LDL receptors from a cellular membrane pool, possibly due to the unique localization of UDCA in the plasma membrane lipid bilayer.     

Chemical communication in hermaphroditic digenetic trematodes

Adult hermaphroditic digenetic trematodes show a tendency to pair or aggregate in vivo, on the chick chorioallantois, and in vitro. Intraspecific pairing studies onEchinostoma revolutum, Leucochloridiomorpha constantiae, andAmblosoma suwaense are reviewed. Lipophilic excretory-secretory products are involved in chemical communication in hermaphroditic digeneans. Free sterols are involved in chemical attraction inL. constantiae andE. revolutum and sterol esters play a similar role inA. suwaense. In vitro pairing betweenE. revolutum and various other digenean species suggest that interspecific pairing occurs in Digenea and that nonspecific factors are involved.     

Does the transactional–transformational leadership paradigm transcend organizational and national boundaries?

There is universality in the transactional–transformational leadership paradigm. That is, the same conception of phenomena and relationships can be observed in a wide range of organizations and cultures. Exceptions can be understood as a consequence of unusual attributes of the organizations or cultures. Three corollaries are discussed. Supportive evidence has been gathered in studies conducted in organizations in business, education, the military, the government, and the independent sector. Likewise, supportive evidence has been accumulated from all but 1 continent to document the applicability of the paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluoroquinolone prophylaxis for the prevention of bacterial infections in patients with cancer--is it justified?

A method for signal enhancement in a colorimetric, nonradioactive and quantitative microplate hybridization assay is described. The signal enhancement provides for the direct detection of viral DNA in serum samples without the use of DNA amplification.     

C-C chemokines, pivotal in protection against HIV type 1 infection

Exposure to HIV type 1 (HIV-1) does not usually lead to infection. Although this could be because of insufficient virus titer, there is now abundant evidence that some individuals resist infection even when directly exposed to a high titer of HIV. This protection recently has been correlated with homozygous mutations of an HIV-1 coreceptor, namely CCR5, the receptor for the beta-chemokines. Moreover, earlier results already had shown that the same chemokines markedly suppress the nonsyncitial inducing variants of HIV-1, the chief virus type transmitted from person to person. CCR5 mutation, as a unique mechanism of protection, is, however, suspect because HIV-1 variants can use other chemokine receptors as their coreceptor. Moreover, recent results have established that infection can indeed sometimes occur with such mutations. Here, we report on transient natural resistance over time of most of 128 hemophiliacs who were inoculated repeatedly with HIV-1-contaminated Factor VIII concentrate from plasma during 1980-1985 before the development of the HIV blood test. Furthermore, and remarkably, 14 subjects remain uninfected to this date, and in these subjects we found homozygous CCR5 mutations in none but in most of them overproduction of beta chemokines. In vitro experiments confirmed the potent anti-HIV suppressive effect of these chemokines.     

Electron capture in an electron plasma wave

We study the influence of the radial electric field of a plasma wave on the accelerated electrons.     

Comportement transitoire de lignes d’énergie en présence du sol réel

This paper shows the scattering of electromagnetic pulses by thin wire structures of any form, above a homogeneous ground characterized by a conductivity a. The problem from which the capital stage is the determination cf the current induced on the wire, is resolved by integral equations, directly established in spacetime domain, taking into account the presence of the earth. Some applications are chosen in the protection domain of telecommunications equipments and electric or railway systems.     

A simulation model for the analysis of machine deterioration and repair

One particular methodology for machine replacement and repair analysis encompasses a Markov or semi-Markov model consisting of states reflecting various stages of machine deterioration. In this paper the “bathtub curve” of replacement analysis is used as the basis for modeling the time in each state of a state-dependent, control-limit replacement policy. A repair queue is also embedded in the model. Specifically, a Q-GERT network simulation is developed and demonstrated via a case example of the weaving operation of a textile company. Output statistics related to the state movement of machines, new machines acquired, and machine repair are presented and discussed.