Protocol for Future Amino Acid Analyses of Samples Returned by the Stardust Mission

We have demonstrated that LC-ToF-MS coupled with UV fluorescence detection is a powerful tool for the detection of amino acids in meteorite extracts. Using this new analytical technique we were able to identify the extraterrestrial amino acid AIB extracted from fifteen 20 micron sized Murchison meteorite grains. We found that the amino acid contamination levels in Stardust aerogels was much lower than the levels observed in the Murchison meteorite. In addition, the alpha-dialkyl amino acids AIB and isovaline which are the most abundant amino acids in Murchison were not detected in the aerogel above blank levels. We are currently integrating LIF detection capability to our existing nanoflow LC-ToF-MS for enhanced sensitivity required for the analysis of amino acids in Stardust samples

Submicrometer Organic Grains: Widespread Constituents of the Early Solar System

Primitive meteorites and interplanetary dust particles (IDPs) contain remants of interstellar organic matter, marked by anomalous H and N isotopic ratios. These isotopic anomalies are attributed to mass fractionation during chemical reactions at cryogenic temperatures (10-100K) in a cold molecular cloud. Significant variations in the chemistry and isotopic compositions of organic compounds within and between these samples suggest varying histories of alteration and dilution of the presolar components. Recent studies have reported large H and N isotopic anomalies preserved in sub-m organic inclusions in both meteorites and IDPs. In the Tagish Lake meteorite, the largest H and N isotopic anomalies are associated with sub-m, hollow organic globules. The common physical, chemical, and isotopic characteristics of these globules suggest that they formed before being incorporated into their parent meteorite. These organic globules probably originated as organic ice coatings that formed on preexisting ice or mineral grains in a cold molecular cloud. Radiation driven photochemistry may have processed them into refractory organic grains. This model implies that submicrometer organic grains were widely distributed throughout the solar nebula during the epoch of planet formation. Submicrometer organic particles were detected by the Giotto and Vega encounters with comet Halley, termed CHON particles based on their major element chemistry. The first direct samples of cometary dust (comet Wild-2) were returned by the Stardust spacecraft in January 2006. These samples exhibit widely varying, fine grained mineralogy similar to anhydrous IDPs, including submicrometer carbonaceous grains. The submicrometer organic grains from comet Wild-2 exhibit H and N isotopic anomalies of similar magnitude to those commonly observed in primitive meteorites and IDPs. Isotopically anomalous, submicrometer organic grains have now been observed in meteorites, IDPs, the Oort-cloud comet Halley, and the Kuiper-belt comet Wild-2, suggesting that such grains were prevalent throughout the protoplanetary disk

Infrared, UV/VIS and Raman Spectroscopy of Comet Wild-2 Samples Returned by the Stardust Mission

Results from the preliminary examination of Stardust samples obtained using various spectroscopic methods will be presented

High Precision Oxygen Three Isotope Analysis of Wild-2 Particles and Anhydrous Chondritic Interplanetary Dust Particles

One of the most important discoveries from comet Wild-2 samples was observation of crystalline silicate particles that resemble chondrules and CAIs in carbonaceous chondrites. Previous oxygen isotope analyses of crystalline silicate terminal particles showed heterogeneous oxygen isotope ratios with delta(sup 18)O to approx. delta(sup 17)O down to -50% in the CAI-like particle Inti, a relict olivine grain in Gozen-sama, and an olivine particle. However, many Wild-2 particles as well as ferromagnesian silicates in anhydrous interplanetary dust particles (IDPs) showed Delta(sup 17)O values that cluster around -2%. In carbonaceous chondrites, chondrules seem to show two major isotope reservoirs with Delta(sup 17)O values at -5% and -2%. It was suggested that the Delta(sup 17)O = -2% is the common oxygen isotope reservoir for carbonaceous chondrite chondrules and cometary dust, from the outer asteroid belt to the Kuiper belt region. However, a larger dataset with high precision isotope analyses (+/-1-2%) is still needed to resolve the similarities or distinctions among Wild-2 particles, IDPs and chondrules in meteorites. We have made signifi-cant efforts to establish routine analyses of small particles (< or =10micronsm) at 1-2% precision using IMS-1280 at WiscSIMS laboratory. Here we report new results of high precision oxygen isotope analyses of Wild-2 particles and anhydrous chondritic IDPs, and discuss the relationship between the cometary dust and carbonaceous chondrite chondrules

Nature and evolution of the dominant carbonaceous matter in interplanetary dust particles: effects of irradiation and identification with a type of amorphous carbon

Aims.Interplanetary dust particle (IDP) matter probably evolved under irradiation in the interstellar medium (ISM) and the solar nebula. Currently IDPs are exposed to irradiation in the Solar System. Here the effects of UV and proton processing on IDP matter are studied experimentally. The structure and chemical composition of the bulk of carbon matter in IDPs is characterized. Methods: .Several IDPs were further irradiated in the laboratory using ultraviolet (UV) photons and protons in order to study the effects of such processing. By means of infrared and Raman spectroscopy, IDPs were also compared to different materials that serve as analogs of carbon grains in the dense and diffuse ISM. Results: .The carbonaceous fraction of IDPs is dehydrogenated by exposure to hard UV photons or 1 MeV protons. On the other hand, proton irradiation at lower energies (20 keV) leads to an efficient hydrogenation of the carbonaceous IDP matter. The dominant type of carbon in IDPs, observed with Raman and infrared spectroscopy, is found to be either a form of amorphous carbon (a-C) or hydrogenated amorphous carbon (a-C:H), depending on the IDP, consisting of aromatic units with an average domain size of 1.35 nm (5-6 rings in diameter), linked by aliphatic chains. Conclusions: .The D- and 15N-enrichments associated to an aliphatic component in some IDPs are probably the result of chemical reactions at cold temperatures. It is proposed that the amorphous carbon in IDPs was formed by energetic processing (UV photons and cosmic rays) of icy grains, maybe during the dense cloud stage, and more likely on the surface of the disk during the T Tauri phase of our Sun. This would explain the isotopic anomalies and morphology of IDPs. Partial annealing, 300-400°C, is required to convert an organic residue from ice photoprocessing into the amorphous carbon with low heteroatom content found in IDPs. Such annealing might have occurred as the particles approached the Sun and/or during atmospheric entry heating

The genome of the protozoan parasite Cystoisospora suis and a reverse vaccinology approach to identify vaccine candidates

Vaccine development targeting protozoan parasites remains challenging, partly due to the complex interactions between these eukaryotes and the host immune system. Reverse vaccinology is a promising approach for direct screening of genome sequence assemblies for new vaccine candidate proteins. Here, we applied this paradigm to Cystoisospora suis, an apicomplexan parasite that causes enteritis and diarrhea in suckling piglets and economic losses in pig production worldwide. Using Next Generation Sequencing we produced an ∼84 Mb sequence assembly for the C. suis genome, making it the first available reference for the genus Cystoisospora. Then, we derived a manually curated annotation of more than 11,000 protein-coding genes and applied the tool Vacceed to identify 1,168 vaccine candidates by screening the predicted C. suis proteome. To refine the set of candidates, we looked at proteins that are highly expressed in merozoites and specific to apicomplexans. The stringent set of candidates included 220 proteins, among which were 152 proteins with unknown function, 17 surface antigens of the SAG and SRS gene families, 12 proteins of the apicomplexan-specific secretory organelles including AMA1, MIC6, MIC13, ROP6, ROP12, ROP27, ROP32 and three proteins related to cell adhesion. Finally, we demonstrated in vitro the immunogenic potential of a C. suis-specific 42 kDa transmembrane protein, which might constitute an attractive candidate for further testing

Optimizing Vaccine Allocation at Different Points in Time during an Epidemic

For current pandemic influenza H1N1, vaccine production started in the early summer, and vaccination started in the fall. In most countries, by the time vaccination started, the second wave of H1N1 was already under way. With limited supplies of vaccine, it might be a good strategy to vaccinate the high-transmission groups earlier in the epidemic, but it might be a better use of resources to protect instead the high-risk groups later on. We develop a deterministic epidemic model with two age-groups (children and adults) and further subdivide each age group in low and high risk. We compare optimal vaccination strategies started at various points in time in two different settings: a population in the United States (US) where children account for 24% of the population, and a population in Senegal, where children make up for the majority of the population, 55%. For each of these populations, we minimize mortality and we find an optimal vaccination vector that gives us the best vaccine allocation given a starting vaccination date and vaccine coverage level. We find that there is a switch in the optimal vaccination strategy at some time point just before the peak of the epidemic. For instance, with 25% vaccine coverage, it is better to protect the high-transmission groups before this point, but it is optimal to protect the most vulnerable groups afterward

UNE APPROCHE SOCIO-INSTITUTIONNELLE DE LA PSYCHODYNAMIQUE DU TRAVAIL

En este artículo se presenta una propuesta de comprensión e intervención de las problemáticas psico-biológicas emergentes en empresas grandes y en instituciones de salud pública, a partir de un abordaje psicodinámico del trabajo fundamentado en una epistemología de los sistemas complejos de Piaget. Para lograr este cometido, se exponen dos casos de empresas que vivieron una intervención, a partir del modelo propuesto por el autor, destacando la importancia que tiene reconocer tanto los aspectos estructurales de una determinada realidad laboral, como también los procesos subjetivos de los trabajadores, directivos y clientes que componen una determinada organización. Concretamente, y en términos epistemológicos, el modelo realiza: procesos de validación y demostración de las problemáticas en tensión, a partir una concepción metodológica positivista; estudia la relación subjetividad/actividad/empresa, con lo cual se permite estudiar e intervenir no solo contextos menores sino también empresas de tamaño grande; desarrolla un paradigma operativo denominado campanas concéntricas, que integra las diferentes formas de análisis del problema de forma sintética. De esta manera, se hace un valioso aporte al campo de la psicodinámica del trabajo, buscando generar críticas, nuevas aproximaciones y soluciones ante los problemas que dicho campo interviene. Palabras clave: psicodinámica del trabajo; subjetividad; epistemología de los sistemas complejos; empresa. &nbsp;This article presents a proposal for understanding and intervention of emerging psychobiological problems in large companies and in public health institutions, based on a psychodynamic approach to work based on an epistemology of complex systems of Piaget. In order to achieve this task, two cases of companies that lived an intervention are exposed, based on the model proposed by the author, highlighting the importance of recognizing both the structural aspects of a given labor reality and the subjective processes of workers, Managers and clients that make part of a particular organization. Specifically, and in epistemological terms, the model realizes: processes of validation and demonstration of the problems in tension, from a positivist methodological conception; Studies the relationship subjectivity / activity / company, which allows to study and intervene not only smaller contexts but also large companies; Develops an operational paradigm called concentric bells, which integrates the different ways of analyzing the problem in a synthetic way. In this way, a valuable contribution is made to the field of psychodynamic of work, seeking to generate criticism, new approaches and solutions to the problems that this field intervenes. &nbsp; Key words: Psychodynamic of work; subjectivity; epistemology of complex systems; company. &nbsp;Nesse artigo apresenta-se uma proposta de compreensão e intervenção das problemáticas de Psicobiologias emergentes em grandes empresas e em instituições de saúde pública, a partir de uma abordagem Psicodinâmica do Trabalho fundamentado em uma epistemologia dos sistemas complexos de Piaget. Para alcançar essa obrigação, apresentam-se dois casos de empresas que passaram uma intervenção, a partir do modelo proposto pelo autor, destacando a importância que tem reconhecer tanto os aspectos estruturais de uma determinada realidade laboral, como também os processos subjetivos dos trabalhadores, diretores e clientes que compõem uma determinada organização. Concretamente, e em termos epistemológicos, o modelo realiza: processos de validação e demonstração das problemáticas em pressão, a partir de uma concepção metodológica positivista; estuda a relação subjetividade/atividade/empresa, na qual se permite estudar e intervir não somente contextos menores senão também empresas grandes; desenvolve um paradigma operativo denominado campanhas concêntricas, que integra as diferentes formas de análise do problema de forma sintética. Dessa maneira, faz-se uma valiosa contribuição no campo da Psicodinâmica do Trabalho, buscando gerar críticas, novas aproximações e soluções perante os problemas cujo esse campo participa. &nbsp; Palavras Chave: psicodinâmica do trabalho; subjetividade; epistemologia dos sistemas complexos; empresa. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Dans cet article, nous présentons une proposition de compréhension et de l'intervention des problèmes émergents Psicobiologias dans les grandes entreprises et les institutions de santé publique, d'un psychodynamique du travail à la terre approcher une épistémologie de Piaget systèmes complexes. Pour parvenir à cette exigence, nous présentons deux cas d'entreprises qui ont une intervention du modèle proposé par l'auteur, en soulignant l'importance de reconnaître les aspects structurels d'une réalité particulière du travail, ainsi que les travailleurs des processus subjectifs, les directeurs et les clients qui composent une organisation particulière. Plus précisément, et en termes épistémologiques, le modèle effectue: la validation et la démonstration des problèmes de pression, d'une conception méthodologique positiviste; la subjectivité des études de relation / activité / entreprise, dans laquelle il permet d'étudier et d'intervenir non seulement plus petits mais aussi grands contextes d'affaires; développe un paradigme d'exploitation appelé campagnes concentriques, intégrant différentes formes d'analyse du problème synthétiquement. Ainsi, il est une contribution précieuse dans le domaine de la psychodynamique du travail, cherchant à susciter des critiques, de nouvelles approches et des solutions aux problèmes que ce pays participe. Mots-clés: psychodynamique du travail; la subjectivité; épistémologie des systèmes complexes; société