Reliability considerations for communication satellites

A detailed program covering all phases of reliability for a communication satellite was presented. In long mission programs such as this one, reliability is the prime consideration in assuring a successful accomplishment of the stringent goals set forth. Reliability principles and methods were incorporated in delineating each major task in the program. These principles and methods not only aided the reliability personnel in performing their duties better, but also assisted the design group, manufacturing personnel, and the testing and evaluation group in performing their jobs efficiently by being aware and knowledgeable of reliability engineering. Various reliability disciplines were imposed, as requirements, on the different groups assigned to the high reliability program. As each group in the program organization became aware of the many problems encountered in this type of program, the reliability personnel worked with each one, incorporating the methods and controls of reliability. These methods and controls aided the design group in designing a system with reliability as the prime consideration. The manufacturing personnel received training and indoctrination instructions in reliability practices, thus enabling them to build a system at the highest level of reliability. The testing and evaluation group used reliability and statistical analysis techniques in their testing programs to check out the design and manufacturing of the satellite. The results and accomplishments speak for themselves. Checking the record to date shows a very successful phase of communications by way of satellite. The feasibility of satellite communications has been proven and the future for more sophisticated techniques looks excellent

Имитация распределенной обработки информации в вычислительных системах и локальных вычислительных сетях

Предложено использовать для анализа вариантов организации распределенной обработки информации в вычислительных системах и локальных вычислительных сетях вероятностный граф реализации вычислительного процесса с явными связями типа вероятностных сетевых графиков.Запропоновано використовувати для аналізу варіантів організації розподіленої обробки інформації в обчислювальних системах і в локальних обчислювальних мережах імовірнісний граф реалізації обчислювального процесу з явними зв’язками типу імовірнісних сіткових графіків.It іs оffered to use for analyzing variants of organization of distributed information processing in computing systems and local computing networks a probabilistic graph for realizing a computing process with evident relationships of the type probabilistic network diagrams

Pre- and Postnatal Dietary Exposure to a Pesticide Cocktail Disrupts Ovarian Functions in 8-Week-Old Female Mice

International audienceFemale infertility has a multifactorial origin, and exposure to contaminants, including pesticides, with endocrine-disrupting properties is considered to be involved in this reproductive disorder, especially when it occurs during early life. Pesticides are present in various facets of the environment, and consumers are exposed to a combination of multiple pesticide residues through food intake. The consequences of such exposure with respect to female fertility are not well known. Therefore, we aimed to assess the impact of pre- and postnatal dietary exposure to a pesticide mixture on folliculogenesis, a crucial process in female reproduction. Mice were exposed to the acceptable daily intake levels of six pesticides in a mixture (boscalid, captan, chlorpyrifos, thiacloprid, thiophanate and ziram) from foetal development until 8 weeks old. Female offspring presented with decreased body weight at weaning, which was maintained at 8 weeks old. This was accompanied by an abnormal ovarian ultrastructure, a drastic decrease in the number of corpora lutea and progesterone levels and an increase in ovary cell proliferation. In conclusion, this study shows that this pesticide mixture that can be commonly found in fruits in Europe, causing endocrine disruption in female mice with pre- and postnatal exposure by disturbing folliculogenesis, mainly in the luteinisation process

Alchimie et philosophie à la Renaissance

Si les alchimistes se désignaient eux-mêmes sous le nom de « philosophes », cette qualité leur fut déniée dès le Moyen-Âge par bien des représentants plus officiels de la « philosophie ». Aujourd’hui, l’importance des doctrines alchimiques dans l’histoire des idées n’est plus guère contestée. Pourtant, les rapports entre la « philosophie hermétique » ou « chymique » et la philosophie au sens habituel restent mal étudiés. C’est afin d’apporter des éléments de réponse à cette question que s’est tenu le colloque dont ce volume constitue les Actes. L’originalité des contributions est de présenter l’alchimie de la Renaissance (xve-xviie siècles) non comme un tout cohérent, donné une fois pour toutes dans la dimension anhistorique d’une « secrète science », mais comme un corpus théorique traversé par une multiplicité de tendances. Cette multiplicité est ici illustrée par l’analyse d’œuvres ou de courants particuliers ayant contribué au développement des doctrines alchimiques, comme la Summa perfectionis de Geber, les traités attribués à Arnaud de Villeneuve, les œuvres de Guillaume Sedacer, Paracelse, Gérard Dorn, Evangelista Quattrami, Jacques Gohory, Michel Maier, Pierre-Jean Fabre, etc. Elle l’est aussi à travers l’étude de la représentation de l’alchimie et de son influence chez des philosophes ou savants eux-mêmes non alchimistes, tels Michel Savonarole, Marsile Ficin, André Thevet, Tycho Brahé, Giordano Bruno, Campanella, Naudé, ou Mersenne

Grooming for tolerance? Two mechanisms of exchange in wild tufted capuchin monkeys

The strategies used by individuals to deploy altruistic behaviors have long captured research attention. Two general mechanisms can account for the decision-making process underpinning the deployment of altruistic behaviors among nonkin. The first mechanism, referred to here as "temporal relation between events," corresponds to classical reciprocal altruism; as such, it is strictly within-dyad and has a strong temporal component. The second mechanism, labeled here as "partner choice based on benefits received," relies on across-dyad comparisons. Although these 2 mechanisms are both theoretically plausible and are not mutually exclusive, very little is known about their relative importance in the deployment of altruistic behaviors. To partially fill this gap, we explored the occurrence of exchanges between grooming and tolerance by assessing the roles of both temporal relations between events and of partner choice based on benefits received in wild tufted capuchin monkeys (Cebus apella nigritus). Data on grooming and cofeeding on contestable resources (as a measure of tolerance) were collected both in natural contexts and during supplemental feeding on provisioning platforms. Overall, our results document reciprocal exchanges between grooming and tolerance over food resources and thus represent the first evidence in wild New World primates for partner choice based on benefits received. More interestingly, partner choice was found to drive the reciprocal exchange much more strongly than the temporal relation between events. Our findings suggest that the role of partner choice based on benefits received should be given much more attention in studies investigating the mechanisms underlying altruism among nonkin. Copyright 2011, Oxford University Press.

Comparison of the deflated preconditioned conjugate gradient method and algebraic multigrid for composite materials

Many applications in computational science and engineering concern composite materials, which are characterized by large discontinuities in the material properties. Such applications require fine-scale finite-element meshes, which lead to large linear systems that are challenging to solve with current direct and iterative solutions algorithms. In this paper, we consider the simulation of asphalt concrete, which is a mixture of components with large differences in material stiffness. The discontinuities in material stiffness give rise to many small eigenvalues that negatively affect the convergence of iterative solution algorithms such as the preconditioned conjugate gradient (PCG) method. This paper considers the deflated preconditioned conjugate gradient (DPCG) method in which the rigid body modes of sets of elements with homogeneous material properties are used as deflation vectors. As preconditioner we consider several variants of the algebraic multigrid smoothed aggregation method. We evaluate the performance of the DPCG method on a parallel computer using up to 64 processors. Our test problems are derived from real asphalt core samples, obtained using CT scans. We show that the DPCG method is an efficient and robust technique for solving these challenging linear systems.Structural EngineeringCivil Engineering and Geoscience