Evaluation and prediction of long-term environmental effects of nonmetallic materials

The properties of a number of nonmetallic materials were evaluated experimentally in simulated space environments in order to develop models for accelerated test methods useful for predicting such behavioral changes. Graphite-epoxy composites were exposed to thermal cycling. Adhesive foam tapes were subjected to a vacuum environment. Metal-matrix composites were tested for baseline data. Predictive modeling designed to include strength and aging effects on composites, polymeric films, and metals under such space conditions (including the atomic oxygen environment) is discussed. The Korel 8031-00 high strength adhesive foam tape was shown to be superior to the other two tested

Evaluation and prediction of long-term environmental effects on non metallic materials

Predictive modeling of environmental conditions on nonmetallic materials was studied. The in-flight data of the atomic oxygen reaction with carbon and osmium, the laboratory and in-flight data of the atomic oxygen reaction with polymeric films and the effect of electron irradiation on the rates of oxidation are discussed. No information is found that can be used to model such effects on composites. The effects of the space environment on thermal control coatings and its effect on the space station are examined

Shuttle/spacelab contamination environment and effects handbook

This handbook is intended to assist users of the Spacelab/Space Transportation System by providing contamination environments and effects information that may be of value in planning, designing, manufacturing, and operating a space flight experiment. A summary of available molecular and particulate contamination data on the Space Transportation System and its facilities is presented. Contamination models, contamination effects, and protection methods information are also presented. In addition to contamination, the effects of the space environments at STS altitudes on spacecraft materials are included. Extensive references, bibliographies, and contacts are provided

Principles, opportunism and seeing in design : a computational approach

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1991.Includes bibliographical references (leaves 100-103).This thesis introduces elements of a theory of design activity and a computational framework for developing design systems. The theory stresses the opportunistic nature of designing and the complementary roles of focus and distraction, the interdependence of evaluation and generation, the multiplicity of ways of seeing over the history of a design session versus the exclusivity of a given way of seeing over an arbitrarily short period, and the incommensurability of criteria used to evaluate a design. The thesis argues for a principle based rather than rule based approach to designing design systems, and highlights the manifest nature of design documents. The Discursive Generator is presented as a computational framework for implementing specific design systems, and a simple system for arranging blocks according to a set of formal principles is developed by way of illustration. Both shape grammars and constraint based systems are used to contrast current trends in design automation with the discursive approach advocated in the thesis. The Discursive Generator is shown to have some important properties lacking in other types of system, such as dynamism, robustness and the ability to deal with partial designs. When studied in terms of a search metaphor, the Discursive Generator is shown to exhibit behavior which is radically different from some traditional search techniques, and to avoid some of the well-known difficulties associated with them.by Pegor H. Papazian.M.S

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

Spinocerebellar ataxia type 19/22 mutations alter heterocomplex Kv4.3 channel function and gating in a dominant manner

The dominantly inherited cerebellar ataxias are a heterogeneous group of neurodegenerative disorders caused by Purkinje cell loss in the cerebellum. Recently, we identified loss-of-function mutations in the KCND3 gene as the cause of spinocerebellar ataxia type 19/22 (SCA19/22), revealing a previously unknown role for the voltage-gated potassium channel, Kv4.3, in Purkinje cell survival. However, how mutant Kv4.3 affects wild-type Kv4.3 channel functioning remains unknown. We provide evidence that SCA19/22-mutant Kv4.3 exerts a dominant negative effect on the trafficking and surface expression of wild-type Kv4.3 in the absence of its regulatory subunit, KChIP2. Notably, this dominant negative effect can be rescued by the presence of KChIP2. We also found that all SCA19/22-mutant subunits either suppress wild-type Kv4.3 current amplitude or alter channel gating in a dominant manner. Our findings suggest that altered Kv4.3 channel localization and/or functioning resulting from SCA19/22 mutations may lead to Purkinje cell loss, neurodegeneration and ataxia

Frequency of KCNC3 DNA Variants as Causes of Spinocerebellar Ataxia 13 (SCA13)

Gain-of function or dominant-negative mutations in the voltage-gated potassium channel KCNC3 (Kv3.3) were recently identified as a cause of autosomal dominant spinocerebellar ataxia. Our objective was to describe the frequency of mutations associated with KCNC3 in a large cohort of index patients with sporadic or familial ataxia presenting to three US ataxia clinics at academic medical centers.DNA sequence analysis of the coding region of the KCNC3 gene was performed in 327 index cases with ataxia. Analysis of channel function was performed by expression of DNA variants in Xenopus oocytes.Sequence analysis revealed two non-synonymous substitutions in exon 2 and five intronic changes, which were not predicted to alter splicing. We identified another pedigree with the p.Arg423His mutation in the highly conserved S4 domain of this channel. This family had an early-onset of disease and associated seizures in one individual. The second coding change, p.Gly263Asp, subtly altered biophysical properties of the channel, but was unlikely to be disease-associated as it occurred in an individual with an expansion of the CAG repeat in the CACNA1A calcium channel.Mutations in KCNC3 are a rare cause of spinocerebellar ataxia with a frequency of less than 1%. The p.Arg423His mutation is recurrent in different populations and associated with early onset. In contrast to previous p.Arg423His mutation carriers, we now observed seizures and mild mental retardation in one individual. This study confirms the wide phenotypic spectrum in SCA13

ReCombine: A Suite of Programs for Detection and Analysis of Meiotic Recombination in Whole-Genome Datasets

In meiosis, the exchange of DNA between chromosomes by homologous recombination is a critical step that ensures proper chromosome segregation and increases genetic diversity. Products of recombination include reciprocal exchanges, known as crossovers, and non-reciprocal gene conversions or non-crossovers. The mechanisms underlying meiotic recombination remain elusive, largely because of the difficulty of analyzing large numbers of recombination events by traditional genetic methods. These traditional methods are increasingly being superseded by high-throughput techniques capable of surveying meiotic recombination on a genome-wide basis. Next-generation sequencing or microarray hybridization is used to genotype thousands of polymorphic markers in the progeny of hybrid yeast strains. New computational tools are needed to perform this genotyping and to find and analyze recombination events. We have developed a suite of programs, ReCombine, for using short sequence reads from next-generation sequencing experiments to genotype yeast meiotic progeny. Upon genotyping, the program CrossOver, a component of ReCombine, then detects recombination products and classifies them into categories based on the features found at each location and their distribution among the various chromatids. CrossOver is also capable of analyzing segregation data from microarray experiments or other sources. This package of programs is designed to allow even researchers without computational expertise to use high-throughput, whole-genome methods to study the molecular mechanisms of meiotic recombination

Functional differences between human NKp44- and NKp44+ RORC+ innate lymphoid cells

Human RORC+ lymphoid tissue inducer cells are part of a rapidly expanding family of innate lymphoid cells (ILC) that participate in innate and adaptive immune responses as well as in lymphoid tissue (re) modeling. The assessment of a potential role for innate lymphocyte-derived cytokines in human homeostasis and disease is hampered by a poor characterization of RORC+ innate cell subsets and a lack of knowledge on the distribution of these cells in adults. Here we show that functionally distinct subsets of human RORC+ innate lymphoid cells are enriched for secretion of IL-17a or IL-22. Both subsets have an activated phenotype and can be distinguished based on the presence or absence of the natural cytotoxicity receptor NKp44. NKp44+ IL-22 producing cells are present in tonsils while NKp44- IL-17a producing cells are present in fetal developing lymph nodes. Development of human intestinal NKp44+ ILC is a programmed event that is independent of bacterial colonization and these cells colonize the fetal intestine during the first trimester. In the adult intestine, NKp44+ ILC are the main ILC subset producing IL-22. NKp44- ILC remain present throughout adulthood in peripheral non-inflamed lymph nodes as resting, non-cytokine producing cells. However, upon stimulation lymph node ILC can swiftly initiate cytokine transcription suggesting that secondary human lymphoid organs may function as a reservoir for innate lymphoid cells capable of participating in inflammatory responses