Overview of Carbon Dioxide Control Issues During International Space Station/Space Shuttle Joint Docked Operations

Crewed space vehicles have a common requirement to remove the carbon dioxide (CO2) created by the metabolic processes of the crew. The space shuttle [Space Transportation System (STS)] and International Space Station (ISS) each have systems in place that allow control and removal of CO2 from the habitable cabin environment. During periods in which the space shuttle is docked to the ISS, known as "joint docked operations," the space shuttle and ISS share a common atmosphere environment. During this period, an elevated amount of CO2 is produced through the combined metabolic activity of the STS and ISS crews. This elevated CO2 production, together with the large effective atmosphere created by collective volumes of the docked vehicles, creates a unique set of requirements for CO2 removal. This paper will describe individual CO2 control plans implemented by STS and ISS engineering teams, as well as the integrated plans used when both vehicles are docked. The paper will also discuss some of the issues and anomalies experienced by both engineering teams

Overview of International Space Station Carbon Dioxide Removal Assembly On-Orbit Operations and Performance

Controlling Carbon Dioxide (CO2) partial pressure in the habitable vehicle environment is a critical part of operations on the International Space Station (ISS). On the United States segment of ISS, CO2 levels are primarily controlled by the Carbon Dioxide Removal Assembly (CDRA). There are two CDRAs on ISS; one in the United States Laboratory module, and one in the Node3 module. CDRA has been through several significant operational issues, performance issues and subsequent re-design of various components, primarily involving the Desiccant Adsorbent Bed (DAB) assembly and Air Selector Valves (ASV). This paper will focus on significant operational and performance issues experienced by the CDRA team from 2008-2012

Caractérisation des sols de la vallée rizicole de Tamra dans l’île de Mar, Centre-Ouest du Sénégal

Tamra est une vallée très sollicitée pour la culture du riz par les  populations des quatre villages implantés dans l’île de Mar. L’étude pédologique a été menée suivant trois toposéquences transversales le long de la vallée. Les différents types de sols rencontrés dans ce milieu fluvio-marin sont disposés d’une manière quasi-concentrique autour de la vallée. Les sols sont affectés par le processus de salinisation et d’acidification. Les causes principales de l’avancée de ce biseau salé le long de la vallée seraient liées à l’environnement climatique peu favorable qui sévit depuis plusieurs années et qui s’exprime par des sécheresses récurrentes. La texture sableuse de ces sols, à dominance de sables fins, et leur niveau topographique font que certains d’entre eux sont exceptionnellement inondés. Ainsi, la réalisation d’une carte d’aptitude culturale des sols s’impose pour une meilleure utilisation des terres de la vallée de Tamra.Mots clés : Tamra, sols, fertilité, salinisation, acidification

Measurement of Condensation Heat Transfer and Pressure Drop for Zeotropic Mixture R-454C and its Components R-32 and R-1234yf in a Horizontal Microfin Tubes

This paper compares the condensation heat transfer and pressure drop for zeotropic refrigerant R454C and its individual components, R32 and R1234yf, in a horizontal microfin tube. The microfin tube has a 4 mm outer diameter, 0.18 mm wall thickness, and a surface area ratio of 1.56. HFOs and HFC/HFO blends like R454C have low global warming potential and can be alternatives to HFC refrigerants when retrofitting a system or producing new equipment. However, there is an additional mass transfer resistance present during phase change for a zeotropic mixture, which results in reduced heat transfer performance. Microfin tubes enhance heat transfer through multiple mechanisms: they increase the internal surface area of the tube, the fins drain condensate from the fin tip to the trough region, and they produce secondary flow structures. Presently, there is limited data of HFO/HFC mixtures in microfin tubes. Thus, experiments are conducted for complete condensation of R454C, R1234yf and R32 for saturation temperatures of 40, 50 and 60 °C and mass fluxes from 100 to 600kgm−2s−1. Experimental heat transfer and pressure drop measurements are compared to wellestablished correlations from the literature. Heat transfer enhancement factors and pressure drop penalty factors are calculated for each refrigerant

Enterprise Architecture Shapes Stakeholder Salience Influence on Enterprise Value-creation

Student research poster, LAI Annual Meeting, Dana Point, C

"Siding with the people" or "Occupying force"? Local perceptions of African Union and ECOWAS interventions in the Gambia

How do African citizens experience and evaluate African regional inter­ventions? This re­search report exa­mines the case of The Gam­bia to assess local percep­tions of the African Union and ECOWAS, particu­larly of their inter­ventions in that country since 2016. It is the result of colla­bora­tive and empiri­cally comprehen­sive research carried out across the country in 2021/2022. We demon­strate that percep­tions of the interven­tions in The Gambia are complex and diverge starkly, at times even contra­dicting each other. We explain this com­plexity as resul­ting from spatial, tempo­ral, and sociopo­litical factors that affect how these Afri­can regio­nal inter­ventions are (diffe­rently) perceived

Differential spatial repositioning of activated genes in \u3ci\u3eBiomphalaria glabrata\u3c/i\u3e snails infected with \u3ci\u3eSchistosoma mansoni\u3c/i\u3e

Schistosomiasis is an infectious disease infecting mammals as the definitive host and fresh water snails as the intermediate host. Understanding the molecular and biochemical relationship between the causative schistosome parasite and its hosts will be key to understanding and ultimately treating and/or eradicating the disease. There is increasing evidence that pathogens that have co-evolved with their hosts can manipulate their hosts\u27 behaviour at various levels to augment an infection. Bacteria, for example, can induce beneficial chromatin remodelling of the host genome. We have previously shown in vitro thatBiomphalaria glabrata embryonic cells co-cultured with schistosome miracidia display genes changing their nuclear location and becoming up-regulated. This also happens in vivo in live intact snails, where early exposure to miracidia also elicits non-random repositioning of genes. We reveal differences in the nuclear repositioning between the response of parasite susceptible snails as compared to resistant snails and with normal or live, attenuated parasites. Interestingly, the stress response gene heat shock protein (Hsp) 70 is only repositioned and then up-regulated in susceptible snails with the normal parasite. This movement and change in gene expression seems to be controlled by the parasite. Other differences in the behaviour of genes support the view that some genes are responding to tissue damage, for example theferritin genes move and are up-regulated whether the snails are either susceptible or resistant and upon exposure to either normal or attenuated parasite. This is the first time host genome reorganisation has been seen in a parasitic host and only the second time for any pathogen. We believe that the parasite elicits a spatio-epigenetic reorganisation of the host genome to induce favourable gene expression for itself and this might represent a fundamental mechanism present in the human host infected with schistosome cercariae as well as in other host-pathogen relationships