Contaminants standards

Contaminant and toxic hazards during manned space flight

Human performance in adverse environments

Human performance testing of astronaut capabilities during prolonged space fligh

"Contagious Love": A Qualitative Study of the Couple Relationships of Ten AIDS Carriers

The qualitative study in this article portrays the couple relationship among AIDS carriers, based on Sternberg's triangular love theory (involving domains of intimacy, passion and commitment). The central study hypothesis is that certain components of the Sternberg model will be more significant than others among the AIDS carrier population. The study was conducted on ten AIDS carriers aged 21-37 who had experienced a couple relationship. Six men and four women participated; most of them were in a romantic couple relationship of homosexual orientation

Using default constraints of the spindle assembly checkpoint to estimate the associated chemical rates

<p/> <p>Background</p> <p>Default activation of the spindle assembly checkpoint provides severe constraints on the underlying biochemical activation rates: on one hand, the cell cannot divide before all chromosomes are aligned, but on the other hand, when they are ready, the separation is quite fast, lasting a few minutes. Our purpose is to use these opposed constraints to estimate the associated chemical rates.</p> <p>Results</p> <p>To analyze the above constraints, we develop a markovian model to describe the dynamics of Cdc20 molecules. We compute the probability for no APC/C activation before time t, the distribution of Cdc20 at equilibrium and the mean time to complete APC/C activation after all chromosomes are attached.</p> <p>Conclusions</p> <p>By studying Cdc20 inhibition and the activation time, we obtain a range for the main chemical reaction rates regulating the spindle assembly checkpoint and transition to anaphase.</p

Kinetic study of the selective hydrogenation of styrene over a Pd egg-shell composite catalyst

This is a study on the kinetics of the liquid-phase hydrogenation of styrene to ethylbenzene over a catalyst of palladium supported on an inorganic–organic composite. This support has a better mechanical resistance than other commercial supports, e.g. alumina, and yields catalysts with egg-shell structure and a very thin active Pd layer. Catalytic tests were carried out in a batch reactor by varying temperature, total pressure and styrene initial concentration between 353–393 K, 10–30 bar, and 0.26–0.60 mol L−1. Kinetic models were developed on the assumptions of dissociative hydrogen chemisorption and non-negligible adsorption of hydrogen and styrene. Final chemical reaction expressions useful for reactor design were obtained. The models that best fitted the experimental data were those ones that considered the surface reaction as the limiting step. In this sense, a two-step Horiuti–Polanyi working mechanism with half hydrogenation intermediates gave the best fit of the experimental data. The heats of adsorption of styrene and ethylbenzene were also estimated.The authors are gratefully indebted to CONICET, ANPCyT and Universidad Nacional del Litoral for financially sponsoring this research work

Conditional targeting of MAD1 to kinetochores is sufficient to reactivate the spindle assembly checkpoint in metaphase

Fidelity of chromosome segregation is monitored by the spindle assembly checkpoint (SAC). Key components of the SAC include MAD1, MAD2, BUB1, BUB3, BUBR1, and MPS1. These proteins accumulate on kinetochores in early prometaphase but are displaced when chromosomes attach to microtubules and/or biorient on the mitotic spindle. As a result, stable attachment of the final chromosome satisfies the SAC, permitting activation of the anaphase promoting complex/cyclosome (APC/C) and subsequent anaphase onset. SAC satisfaction is reversible, however, as addition of taxol during metaphase stops cyclin B1 degradation by the APC/C. We now show that targeting MAD1 to kinetochores during metaphase is sufficient to reestablish SAC activity after initial silencing. Using rapamycin-induced heterodimerization of FKBP-MAD1 to FRB-MIS12 and live monitoring of cyclin B1 degradation, we show that timed relocalization of MAD1 during metaphase can stop cyclin B1 degradation without affecting chromosome-spindle attachments. APC/C inhibition represented true SAC reactivation, as FKBP-MAD1 required an intact MAD2-interaction motif and MPS1 activity to accomplish this. Our data show that MAD1 kinetochore localization dictates SAC activity and imply that SAC regulatory mechanisms downstream of MAD1 remain functional in metaphase. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00412-014-0458-9) contains supplementary material, which is available to authorized users

Shells and humans: molluscs and other coastal resources from the earliest human occupations at the Mesolithic shell midden of El Mazo (Asturias, Northern Spain)

Human populations exploited coastal areas with intensity during the Mesolithic in Atlantic Europe, resulting in the accumulation of large shell middens. Northern Spain is one of the most prolific regions, and especially the so-called Asturian area. Large accumulations of shellfish led some scholars to propose the existence of intensification in the exploitation of coastal resources in the region during the Mesolithic. In this paper, shell remains (molluscs, crustaceans and echinoderms) from stratigraphic units 114 and 115 (dated to the early Mesolithic c. 9 kys cal BP) at El Mazo cave (Asturias, northern Spain) were studied in order to establish resource exploitation patterns and environmental conditions. Species representation showed that limpets, top shells and sea urchins were preferentially exploited. One-millimetre mesh screens were crucial in establishing an accurate minimum number of individuals for sea urchins and to determine their importance in exploitation patterns. Environmental conditions deduced from shell assemblages indicated that temperate conditions prevailed at the time of the occupation and the morphology of the coastline was similar to today (rocky exposed shores). Information recovered relating to species representation, collection areas and shell biometry reflected some evidence of intensification (reduced shell size, collection in lower areas of exposed shores, no size selection in some units and species) in the exploitation of coastal resources through time. However, the results suggested the existence of changes in collection strategies and resource management, and periods of intense shell collection may have alternated with times of shell stock recovery throughout the Mesolithic.This research was performed as part of the project “The human response to the global climatic change in a littoral zone: the case of the transition to the Holocene in the Cantabrian coast (10,000–5000 cal BC) (HAR2010-22115-C02-01)” funded by the Spanish Ministry of Economy and Competitiveness. AGE was funded by the University of Cantabria through a predoctoral grant and IGZ was funded by the Spanish Ministry of Economy and Competitiveness through a Juan de la Cierva grant. We also would like to thank the University of Cantabria and the IIIPC for providing support, David Cuenca-Solana, Alejandro García Moreno and Lucia Agudo Pérez for their help. We also thank Jennifer Jones for correcting the English. Comments from two anonymous reviewers helped to improve the paper

Cachimbos europeus de cerâmica branca, séculos XVI ao XIX: parâmetros básicos para análise arqueológica

O tabaco foi introduzido na Europa no final do século XV. Desde então, uma das formas mais comuns para o seu consumo foi o cachimbo, além do rapé, do tabaco de mascar, do charuto e, mais recentemente, dos cigarros. Os cachimbos de cerâmica branca, largamente produzidos e utilizados na Europa desde o século XV, são encontrados em sítios arqueológicos históricos ao redor do mundo, incluindo no Brasil, em decorrência do comércio internacional, que gradualmente se intensificou após o início da conquista europeia. Eles funcionam como excelentes elementos para datação de sítios e estratos arqueológicos, tendo sido estudados em vários países a partir dessa abordagem. Ainda, esse tipo de artefato, mais que fornecer datações, permite identificar redes comerciais entre nações e desenvolver discussões de cunho social e cultural. Contudo, eles foram pouco estudados no Brasil. Visando contribuir com os estudos nacionais dessa categoria material, este artigo oferece uma revisão da literatura internacional acerca do histórico da produção dos cachimbos europeus de caulim, incluindo apresentação dos principais centros produtores; da morfologia e decoração desses produtos, considerando a cronologia do fabrico; e dos métodos de análise dos diferentes cachimbos de caulim no âmbito da arqueologia histórica.Tobacco was introduced in Europe at the end of the 15th century. Since then, one of the most traditional means for its use has been the pipe, next to the powder version, chewing, cigars, and, more recently, cigarettes. White clay tobacco pipes, widely produced and used in Europe since the 15th century, are found in historical archaeological sites around the world, including Brazil, due to international trade, which gradually intensified with the European conquest of the New World. They are excellent guides for dating archaeological sites and layers. In addition, this type of artifact, more than a dating tool, permits identifying trading networks between nations and developing discussions of cultural and social nature. These pipes, however, have been understudied in Brazil. In order to contribute to studies of this type of artifact in our country, this paper offers a revision of the international literature on the history of clay pipe production in Europe, including the presentation of main production centers; morphology and decoration of these products, considering issues of fabrication chronology; and the methods used in Historical Archaeology for analyzing clay tobacco pipes