The Aggregation Kinetics of a Simulated Telechelic Polymer

We investigate the aggregation kinetics of a simulated telechelic polymer gel. In the hybrid Molecular Dynamics (MD) / Monte Carlo (MC) algorithm, aggregates of associating end groups form and break according to MC rules, while the position of the polymers in space is dictated by MD. As a result, the aggregate sizes change every time step. In order to describe this aggregation process, we employ master equations. They define changes in the number of aggregates of a certain size in terms of reaction rates. These reaction rates indicate the likelihood that two aggregates combine to form a large one, or that a large aggregate splits into two smaller parts. The reaction rates are obtained from the simulations for a range of temperatures. Our results indicate that the rates are not only temperature dependent, but also a function of the sizes of the aggregates involved in the reaction. Using the measured rates, solutions to the master equations are shown to be stable and in agreement with the aggregate size distribution, as obtained directly from simulation data. Furthermore, we show how temperature induced variations in these rates give rise to the observed changes in the aggregate distribution that characterizes the sol-gel transition.Comment: 9 pages, 10 figure

Augmenter of liver regeneration enhances the success rate of fetal pancreas transplantation in rodents

Background. Treatment of fetal pancreas (FP) isografts with insulin- like growth factor-I greatly improves the rate of conversion to euglycemia in diabetic rats. Complete knowledge of other factors that may facilitate the engraftment and function of FP in vivo is still embryonic. Augmenter of liver regeneration (ALR) is a newly described polypeptide growth factor found in weanling rat livers. ALR has trophic effects on regenerating liver. We studied the effects of in situ administration of this agent on FP isografts in rats. Methods. Streptozotocin-diabetic Lewis rats (blood glucose >300 mg/dl) received 16 FP isografts transplanted intramuscularly. ALR was delivered from day 1 through day 14, in doses of 40 or 400 ng/kg/d. Animals were followed for 3 months with serial weights and blood glucose monitoring. These animals were compared with those treated with vehicle alone. Results. Of the group treated with ALR at 40 ng/kg/day for 14 days, 89% (eight of nine) were euglycemic (P=0.0003). Of the group treated with ALR at 400 ng/kg/day for 14 days, 88% (seven of eight) were euglycemic (P=0.0007). Of the group treated with vehicle alone, none of the six were euglycemic. Euglycemia is defined here as glucose<200 mg/dl for 3 days. Pathology of the intramuscular transplant site showed patches of islet tissue embedded in fat. These patches demonstrated insulin immunoreactivity. Conclusions. Diabetes was reversed in a significantly greater proportion of FP + ALR-treated recipients than those animals treated with vehicle alone. Local delivery of growth factors my be used as an adjunct to FP transplantation to improve the rate of success. This in situ model may be useful to further evaluate other soluble factors

East Asia and the global/transatlantic/Western crisis

This paper introduces the special collection on East Asia and the Global Crisis. After justifying why a focus on East Asia is appropriate, it draws out the main themes that run through the individual contributions. These are the extent to which the region is decoupling from the global economy (or the West), the increasing legitimacy of statist alternatives to neoliberal development strategies, and the impact of crises on the definition of ―region‖ and the functioning of regional institutions and governance mechanisms

Informer, consulter, concerter, codécider pour aménager : Dispositifs de partage des informations et des connaissances pour les processus d'aménagement concerté (DPICPAC) : rapport final

Ce projet applique une approche interdisciplinaire afin de tester l'hypothèse générale et communément admise que la disponibilité et la pertinence de l'information sont cruciaux pour le succès des processus d'aménagement du territoire participatifs (ou collaboratifs) qui impliquent plusieurs groupes d'acteurs, y compris fonctionnaires, des professionnels, des représentants des propriétaires fonciers et du grand public. Cette hypothèse est fondée sur le point de vue "instrumental" que lorsque l'information appropriée est disponible au moment opportun dans le processus de planification, alors il favorisera la réussite de ce processus. Une deuxième hypothèse fondée sur les principes de la «gouvernance» attribue une importance primordiale aux motivations de tous les acteurs et institutions représentés dans le processus de planification. Une troisième hypothèse que la négociation d'un ensemble de règles concernant les rôles et les responsabilités des acteurs et des institutions ainsi que la disponibilité de données appropriées, de statistiques et d'informations sont nécessaires pour une planification collaborative réussie. Cette recherche comprend des études de cas dans la région de langue française de la Suisse (Genève et Lausanne) dans le but d'analyser et d'expliquer comment et pourquoi les statistiques et les informations disponibles peuvent ou non être utilisés efficacement dans les processus décisionnels. La recherche propose un ensemble de lignes directrices pour l'application efficace de ces types de processus dans le futur

Comprehension of demoulding mechanisms at the formwork/oil/concrete interface

The implementation of concrete and its association with a release agent influence the aesthetics of the concrete facings. The mineral oils tend to be replaced by vegetable formulations, to reduce the impact of the substances spilled in the environment. From a technical point of view, it is important to characterize the action of these new formulations at the interface concrete/oil/formwork. Two performing techniques have been used to study the physicochemical processes, the tribometry and electrochemical impedance spectroscopy. The correlation of the results obtained allowed to improve the understanding of the mechanisms involved at the interface mould/oil, in connection with the use of an acidifier in the formulation

Inativação seletiva de esporos mantendo atividade larvicida em Bt sorovar israelensis irradiada com raios gama

Bacillus thuringiensis is used to produce biopesticides against target-insects of importance in agroindustry and human health. However, B. thuringiensis can carry the same enterotoxin-encoding genes as Bacillus cereus, suggesting a potential risk of food poisoning. The objective of this work was to study the application of gamma radiation to eliminate spores in biopesticides based on B. thuringiensis serovar israelensis in order to avoid the liberation of these spores in the environment. The application of 20 kGy of radiation ensures total inactivation of the spores in the insecticide without changing the larvicidal activity. Results showed that it is possible to develop formulations containing B. thuringiensis serovar israelensis (IPS-82) eliminating viable spores with gamma radiation without affecting the larvicidal activity. Irradiated formulations would be safer for the environment and humans since the elimination of viable spores abolishes the pathogenic potential of B. thuringiensis strains.Keywords: biopesticides, gamma radiation, larvicidal insecticides.Bacillus thuringiensis é usado na produção de biopesticidas contra insetos-alvo de importância na agroindústria e na saúde pública. Contudo, B. thuringiensis pode apresentar os mesmos genes codificadores de enterotoxinas presentes em Bacillus cereus, sugerindo a possível existência de risco para intoxicação alimentar. O objetivo deste trabalho foi estudar a aplicação de radiação gama para a eliminação de esporos em preparações de biopesticidas de B. thuringiensis sorovar israelensis de forma a se evitar a liberação de esporos viáveis no ambiente. Observou-se que a aplicação de 20 kGy garante a inativação total dos esporos no inseticida sem que haja mudança na atividade larvicida. Os resultados obtidos demonstram que é possível desenvolver formulações contendo B. thuringiensis sorovar israelensis (IPS-82) eliminando-se esporos viáveis sem alteração da atividade larvicida. As formulações irradiadas seriam mais seguras para o meio-ambiente e para seres humanos uma vez que a eliminação dos esporos viáveis neutraliza o potencial patogênico de cepas de B. thuringiensis.Palavras-chave: biopesticidas, radiação gama, inseticidas larvicidas

Disruption of Protein Kinase A in Mice Enhances Healthy Aging

Mutations that cause a reduction in protein kinase A (PKA) activity have been shown to extend lifespan in yeast. Loss of function of mammalian RIIβ, a regulatory subunit of PKA expressed in brain and adipose tissue, results in mice that are lean and insulin sensitive. It was therefore hypothesized that RIIB null (RIIβ−/−) mice would express anti-aging phenotypes. We conducted lifespan studies using 40 mutant and 40 wild type (WT) littermates of equal gender numbers and found that both the median and maximum lifespans were significantly increased in mutant males compared to WT littermates. The median lifespan was increased from 884 days to 1005 days (p = 0.006 as determined by the log rank test) and the 80% lifespan (defined here as 80% deaths) was increased from 941 days to 1073 days (p = 0.004 as determined by the Wang-Allison test). There was no difference in either median or 80% lifespan in female genotypes. WT mice of both genders became increasingly obese with age, while mutant mice maintained their lean phenotype into old age. Adiposity was found to correlate with lifespan for males only. 50% of male mice between 30 and 35 g, corresponding to about 5% body fat, for either genotype lived over 1000 days. No male mouse outside of this weight range achieved this lifespan. During their last month of life, WT mice began losing weight (a total of 8% and 15% of body weight was lost for males and females, respectively), but RIIβ−/− male mice maintained their lean body mass to end of life. This attenuation of decline was not seen in female mutant mice. Old male mutant mice were insulin sensitive throughout their life. Both genders showed modestly lower blood glucose levels in old mutants compared to WT. Male mutants were also resistant to age-induced fatty liver. Pathological assessment of tissues from end of life male mutant mice showed a decrease in tumor incidence, decreased severity of renal lesions, and a trend towards a decrease in age-related cardiac pathology. These findings help establish the highly conserved nature of PKA and suggest that disruption of PKA affects physiological mechanisms known to be associated with healthy aging