1,030 research outputs found

    Dynamic Modeling of Ascent Abort Scenarios for Crewed Launches

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    For the last 30 years, the United States' human space program has been focused on low Earth orbit exploration and operations with the Space Shuttle and International Space Station programs. After over 40 years, the U.S. is again working to return humans beyond Earth orbit. To do so, NASA is developing a new launch vehicle and spacecraft to provide this capability. The launch vehicle is referred to as the Space Launch System (SLS) and the spacecraft is called Orion. The new launch system is being developed with an abort system that will enable the crew to escape launch failures that would otherwise be catastrophic as well as probabilistic design requirements set for probability of loss of crew (LOC) and loss of mission (LOM). In order to optimize the risk associated with designing this new launch system, as well as verifying the associated requirements, NASA has developed a comprehensive Probabilistic Risk Assessment (PRA) of the integrated ascent phase of the mission that includes the launch vehicle, spacecraft and ground launch facilities. Given the dynamic nature of rocket launches and the potential for things to go wrong, developing a PRA to assess the risk can be a very challenging effort. Prior to launch and after the crew has boarded the spacecraft, the risk exposure time can be on the order of three hours. During this time, events may initiate from either the spacecraft, the launch vehicle, or the ground systems, thus requiring an emergency egress from the spacecraft to a safe ground location or a pad abort via the spacecraft's launch abort system. Following launch, again either the spacecraft or the launch vehicle can initiate the need for the crew to abort the mission and return home. Obviously, there are thousands of scenarios whose outcome depends on when the abort is initiated during ascent and how the abort is performed. This includes modeling the risk associated with explosions and benign system failures that require aborting a spacecraft under very dynamic conditions, particularly in the lower atmosphere, and returning the crew home safely. This paper will provide an overview of the PRA model that has been developed of this new launch system, including some of the challenges that are associated with this effort

    Dynamic Modeling of Ascent Abort Scenarios for Crewed Launches

    Get PDF
    For the last 30 years, the United States's human space program has been focused on low Earth orbit exploration and operations with the Space Shuttle and International Space Station programs. After nearly 50 years, the U.S. is again working to return humans beyond Earth orbit. To do so, NASA is developing a new launch vehicle and spacecraft to provide this capability. The launch vehicle is referred to as the Space Launch System (SLS) and the spacecraft is called Orion. The new launch system is being developed with an abort system that will enable the crew to escape launch failures that would otherwise be catastrophic as well as probabilistic design requirements set for probability of loss of crew (LOC) and loss of mission (LOM). In order to optimize the risk associated with designing this new launch system, as well as verifying the associated requirements, NASA has developed a comprehensive Probabilistic Risk Assessment (PRA) of the integrated ascent phase of the mission that includes the launch vehicle, spacecraft and ground launch facilities. Given the dynamic nature of rocket launches and the potential for things to go wrong, developing a PRA to assess the risk can be a very challenging effort. Prior to launch and after the crew has boarded the spacecraft, the risk exposure time can be on the order of three hours. During this time, events may initiate from either of the spacecraft, the launch vehicle, or the ground systems, thus requiring an emergency egress from the spacecraft to a safe ground location or a pad abort via the spacecraft's launch abort system. Following launch, again either the spacecraft or the launch vehicle can initiate the need for the crew to abort the mission and return to the home. Obviously, there are thousands of scenarios whose outcome depends on when the abort is initiated during ascent as to how the abort is performed. This includes modeling the risk associated with explosions and benign system failures that require aborting a spacecraft under very dynamic conditions, particularly in the lower atmosphere, and returning the crew home safely. This paper will provide an overview of the PRA model that has been developed of this new launch system, including some of the challenges that are associated with this effort. Key Words: PRA, space launches, human space program, ascent abort, spacecraft, launch vehicle

    Characterization of queen specific components of the fluid released by fighting honey bee queens

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    Swarming honey bee (Apis mellifera L.) colonies rear supernumerary young queens that compete for the limited resources (workers) necessary for founding a new colony. Young queens often fight to death. Queens show several adaptations to fight and conflict, such as short developmental time and early onset of venom production. During fights, queens often release rectal fluid with a strong smell of wine grapes, after which they temporarily stop fighting. This potentially reduces individual overall risk of deadly injury. The fluid and one of its components, ortho-aminoacetophenone, were previously found to have a pheromonal effect on workers, but the evidence is equivocal. Recently, it has been suggested that the effects of this substance may be context- or concentration-specific. We performed semi-quantitative gas-chromatography mass spectrometry (GC/MS) analysis of the fluid (1) released by queens during their first fight, (2) released during a subsequent fight, and (3) obtained by dissecting the hindgut of queens and (4) of workers. Following preliminary results by Page et al. 1988 (Experientia 44: 270-271), we scored presence / absence of eight substances. Five substances (ortho-aminoacetophenone, decanoic acid, dodecanoic acid, octyl decanoate, and decyl decanoate) were characteristic of queens only. ortho-Aminoacetophenone was detected in all queen and in none of the worker samples, in agreement with previous findings that worker faeces do not have any pheromonal effect. The fluid released by queens on their second fight also contained ortho-aminoacetophenone, but in smaller quantities. These data substantiate previous bioassay results, and provide estimates of ortho-aminoacetophenone concentration as required to design experiments addressing the function and adaptive significance of this behaviour

    Orale Mukositis bei Patienten unter Tumortherapie

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    Zusammenfassung: Zu den unerwünschten Nebenwirkungen bestimmter Chemo- und Radiotherapien gehört die orale Mukositis, eine Entzündung der Mundschleimhaut. Da sie die Lebensqualität der Patienten in hohem Maße beeinträchtigen kann, sollten Pflegende der Mundhygiene einen besonders hohen Stellenwert beimessen. In der täglichen Praxis wird die orale Mukositis oft kontrovers diskutiert. In diesem Artikel werden aktuelle theoriebasierte und erfahrungsbasierte Grundlagen und Anleitungen für die Pflege und Behandlung vorgestell

    Interleukin-1 Receptor antagonist Production by Human Keratinocytes

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    Human keratinocytes produce biologically active pro–IL-Iα and inactive pro-IL-1β with most protein remaining intracellular. IL-1 receptor antagonist (IL-1ra) is a newly described member of the IL-1 family that is secreted by stimulated monocytes and binds competitively to IL-1 receptors without stimulating target cells. We examined the characteristics of IL-1ra production by cultured human keratinocytes. By ELISA, keratinocyte lysates contained 390 ng IL-1ra/mg total protein with little IL-1ra detected in supernatants. In contrast, monocytes produced 297 ng IL- 1ra/mg total protein during 24 h of culture on adherent IgG with about half of the IL-1ra detected in supernatants. By Western blot analysis, keratinocyte IL-1ra was ≈ 20 kD in size and was slightly larger than recombinant monocyte IL- 1ra. In contrast to monocytes, human keratinocyte IL-1ra was not secreted in 22- 25-kD molecular weight glycosylated forms. Affinity-purified keratinocyte IL-1ra exhibited identical biologic activity to recombinant monocyte IL-1ra, each inhibiting IL-1 -dependent augmentation of murint thymocyte proliferation to the same degree per amount protein. An IL-1ra mRNA of 1.8 kb was detected by Northern blot analysis in RNA extracted from keratinocytes. in order to determine the effect of differentiation on IL-1 and IL-1ra production, human keratinocytes were cultured for 72 h in low (0.03 mM), medium (0.15 mM), or high (1.0 mM) -calcium concentrations. The absolute amounts of IL-1ra increased twofold and the ratio of IL-1ra to IL-1ra in keratinocyte lysates increased from ≈ 12: 1 to 25: 1 during differentiation. These results indicate that keratinocytes constitutively produce large amounts of a biologically active intracellular variant of IL-1ra that increase with differentiation. IL-1ra released during keratinocyte damage may be important in modifying the inflammatory effects of IL-1α in human skin

    Seasonal Home Ranges of Raccoons, Procyon lotor, Using a Common Feeding Site in Rural Eastern Ontario: Rabies Management Implications

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    Thirteen adult Raccoons (Procyon lotor) (six females, seven males) that fed at a garbage dump north of Kingston, Ontario were radio-tracked from 21 June to 16 October 1995 to assess their seasonal home ranges and movements. Average Minimum Convex Polygon (MCP) summer and fall home ranges for the collared Raccoons were 78.4 ha (SD=46.2 ha) and 45.6 ha (SD=29.7 ha), respectively. Average grid cell summer and fall home ranges for the collared Raccoons were 143.3 ha (SD=40.0 ha) and 116.9 ha (SD=24.9 ha), respectively. Summer ranges of the Raccoons were significantly larger than fall ranges using both the MCP method (P=0.05) and the grid cell method (P=0.073). Yearling Raccoons travelled an average summer maximum distance from the dump of 2608 m (SD=1964, n=3), more than double the distance of adults (≥2 yr) at 1239 m (SD=547, n=10). The population density for the study area in late August 1995 was estimated at 1 Raccoon/12 ha based on an effective area surrounding the dump of 234 ha. Home range and movement data may be useful to design a strategy to control Raccoon rabies in Ontario

    Messenger RNAs localized to distal projections of human stem cell derived neurons

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    The identification of mRNAs in distal projections of model organisms has led to the discovery of multiple proteins that are locally synthesized for functional roles such as axon guidance, injury signaling and regeneration. The extent to which local protein synthesis is conserved in human neurons is unknown. Here we used compartmentalized microfluidic chambers to characterize the transcriptome of distal projections of human embryonic stem cells differentiated using a protocol which enriched for glutamatergic neurons (hESC-neurons). Using gene expression analysis, we identified mRNAs proportionally enriched in these projections, representing a functionally unique local transcriptome as compared to the human neuronal transcriptome inclusive of somata. Further, we found that the most abundant mRNAs within these hESC-neuron projections were functionally similar to the axonal transcriptome of rat cortical neurons. We confirmed the presence of two well characterized axonal mRNAs in model organisms, β-actin and GAP43, within hESC-neuron projections using multiplexed single molecule RNA-FISH. Additionally, we report the novel finding that oxytocin mRNA localized to these human projections and confirmed its localization using RNA-FISH. This new evaluation of mRNA within human projections provides an important resource for studying local mRNA translation and has the potential to reveal both conserved and unique translation dependent mechanisms

    Utah\u27s 1977 Drought

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    The Utah Drought of 1976-1977 has been characterized as the wettest drought in history. It was produced by the driest winter season of record followed by summer rains which were much wetter than normal in many regions of the state. Stream-flow is highly correlated with winter rather than summer precipitation and therefore the most severe impacts of the drought were related to the record low stream-flow during 1977 plus the ski industry impacts which were directly related to 1976-1977 snowfall. Drought impacts upon several sectors of the economy plus the extensive responses of all levels of government in the form of drought relief programs are described and quantified
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