199 research outputs found

    A practical system for regional mobile satellite services

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    The Regional Mobile Satellite (MSAT) concept proposes a worldwide, interconnected mobile satellite service (MSS) network in which MSAT-type satellites provide the space segment services to separate regions (i.e., one or a few countries). Using this concept, mobile communications users across entire continents can now be served by a handful of regionally controlled satellites in geostationary earth orbit (GEO). All requirements, including hand-held telephone capabilities, can be cost-effectively provided using proven technologies. While other concepts of regional or global mobile communications continue to be explored, the Hughes Regional MSAT system demonstrates the near-term viability of the GEO approach

    [Editorial] Habitability Beyond Earth

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    The question of whether Earth is a unique location for life remains one of the most enduring questions of our time. Geochemical data suggests that habitable environments may exist, or may have existed, elsewhere in the Solar System with promising targets including Mars and icy bodies where liquid water is believed to exist (Kargel, 2000; Grotzinger et al., 2014; Glein et al., 2015). Furthermore, potential habitable Exoplanets have been discovered where potentially there is sufficient atmospheric pressure to maintain liquid water (Jenkins et al., 2015; Gillon et al., 2017; Orosei et al., 2018). Yet, for life to exist it is not solely dependent on liquid water as it also needs bio-essential elements, an energy source, and the environmental conditions, that are conducive to life (Nixon et al., 2013). To investigate the feasibility of life elsewhere in the Solar System a combination of field and laboratory based studies, in-situ space experiments, and theoretical modeling is required. Here, we present 14 original research papers, one mini review, and two hypothesis and theory papers highlighting the novel and diverse methods that are employed to investigate potential life beyond the Earth. The overall focus of this collection of work is to understand if terrestrial life could exist elsewhere in the Solar System, and if so, what evidence (bio-signatures) could be used to support or negate the hypothesis of life

    A self-adaptive SEU mitigation system for FPGAs with an internal block RAM radiation particle sensor

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    In this paper, we propose a self-adaptive FPGA- based, partially reconfigurable system for space missions in order to mitigate Single Event Upsets in the FPGA configuration and fabric. Dynamic reconfiguration is used here for an on-demand replication of modules in dependence of current and changing radiation levels. More precisely, the idea is to trigger a redundancy scheme such as Dual Modular Redundancy or Triple Modular Redundancy in response to a continuously monitored Single Event Upset rate measured inside the on-chip memories itself, e.g., any subset (even used) internal Block RAMs. Depending on the current radiation level, the minimal number of replicas is determined at run- time under the constraint that a required Safety Integrity Level for a module is ensured and configured accordingly. For signal processing applications it is shown that this autonomous adaption to the different solar conditions realizes a resource efficient mitigation. In our case study, we show that it is possible to triplicate the data throughput at the Solar Maximum condition (no flares) compared to a Triple Modular Redundancy implementation of a single module. We also show the decreasing Probability of Failures Per Hour by 2 × 104 at flare-enhanced conditions compared with a non-redundant system. Our work is a part of the In-Orbit Verification of the Heinrich Hertz communication satellite

    ANTIBIOTICS RESISTANCE – The Nurses Struggle

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    Bacheloroppgave sykepleie, 2016Bakgrunn: Antibiotikaresistente bakterier er et Þkende problem globalt, men ogsÄ nasjonalt. Som sykepleiere vil vi kunne mÞte pÄ pasienter som har infeksjoner med antibiotikaresistente bakterier. Hva er vÄrt ansvar i mÞte med denne pasientgruppen, og har vi nok kunnskaper til Ä kunne utÞve faglig forsvarlig sykepleie? Metode: Dette er en litteraturstudie hvor vi har anvendt pensumlitteratur, forskningsartikler og annen relevant litteratur for Ä drÞfte oss frem til svar pÄ en problemstilling. Resultater: VÄr rolle som sykepleiere innenfor dette feltet er ikke tydelig definert. Vi har forebyggende, pleiende og helsefremmende funksjoner, uten at det er nÞye beskrevet hva vi skal gjÞre, det finnes dog mange retningslinjer, veiledere og prosedyrer pÄ tiltak. Det er i forskning gjort funn pÄ at sykepleiere med lite kunnskap om antibiotikaresistens fÞler seg mye mer utrygg i mÞte med denne pasientgruppen. I tillegg er det ogsÄ gjort funn pÄ at pasienter som fÄr infeksjoner med antibiotikaresistente bakterier fÞler de fÄr lite informasjon og dÄrlig behandling av helsevesenet. Vi har drÞftet begrepet «opplevelse av sammenheng» og sett pÄ om kunnskapsÞkning vil kunne ha en positiv innvirkning pÄ faglig trygghet og praktisk hÄndtering. Konklusjon: Vi har ikke funnet forskning som sier at kunnskapsÞkning gir den Þnskede effekten vi er ute etter, men mangel pÄ kunnskap kan vÊre en Ärsak pÄ den faglige utryggheten, og den dÄrlige pasientbehandlingen pasientene selv har rapportert inn. Ergo kan det vÊre grunnlag for Ä se at systematisk kunnskapsÞkning vil ha en positiv innvirkning

    Nutritional status of woody species of two semideciduous forests in UberlĂąndia, MG

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    O estudo teve como objetivo determinar a influĂȘncia da fertilidade sobre nutrição mineral e distribuição das espĂ©cies nativas em duas florestas semidecĂ­duas na Fazenda Experimental de GlĂłria (FEG) e Estação EcolĂłgica do Panga (EEP) em UberlĂąndia, MG. Foram amostradas de duas a quatro ĂĄrvores, com circunferĂȘncia mĂ­nima de 10 cm, a altura de 1,30 m do solo, de todas as espĂ©cies encontradas em 50 parcelas contĂ­guas de 10 m X 10 m, em cada floresta. Foram analisadas amostras de solo dos horizontes A1 e A3 de cada parcela nas duas florestas. O solo da EEP apresentou menor acidez, associada Ă  maior disponibilidade de Ca e menor disponibilidade de Al, Fe, Zn e Cu. A disponibilidade Mn foi menor no horizonte A3 e maior no A1 na EEP. As concentraçÔes foliares de Ca e K foram maiores nas espĂ©cies da EEP. As diferenças no teor de Ca refletiram a maior disponibilidade do nutriente no solo. NĂŁo houve diferenças nas concentraçÔes foliares de P e Mg. O teor mĂ©dio de N foi maior na floresta FEG do que na EEP, apenas em espĂ©cies exclusivas. As concentraçÔes de Mn foram menores na EEP, refletindo a influĂȘncia do pH na absorção deste nutriente. Assim, a ocorrĂȘncia de espĂ©cies presentes exclusivamente na EEP pode estar associada Ă  capacidade de absorver K e Mg de solos com altos teores de Ca.The objective of this study was to determine the influence of soil fertility on the mineral nutrition and distribution of native species in two semideciduous forests at the Experimental Farm at Gloria (FEG) and the Ecological Station at Panga (EEP) in UberlĂąndia, MG. Leaf samples were collected from two to four individuals with a minimum circumference of 10 cm at 1,30 m height of all species within 50 contiguous plots of 10 m X 10 m in each forest. Soil samples were analyzed from the A1 e A3 horizons of each plot of both areas. The soil of EEP showed lower acidity, higher availability of Ca and lower availability of Al, Fe, Zn and Cu. The availability of Mn was lower in the A3 horizon and higher in the A1 horizon at EEP. The foliar concentrations of Ca e K were higher at EEP which reflected the higher levels in soil. There were no differences in the concentrations of P, Mg, Fe, Cu and Zn. The N concentrations were higher among species occurring exclusively at FEG. The Mn concentrations were lower at EEP, reflecting the effect of pH on its absorption. Thus the occurrence of some species exclusively at EEP seemed to be associated with their ability to absorb K and Mg from soils with high Ca availability

    Abundant phosphorus expected for possible life in Enceladus’s ocean

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    Saturn’s moon Enceladus has a potentially habitable subsurface water ocean that contains canonical building blocks of life (organic and inorganic carbon, ammonia, possibly hydrogen sulfide) and chemical energy (disequilibria for methanogenesis). However, its habitability could be strongly affected by the unknown availability of phosphorus (P). Here, we perform thermodynamic and kinetic modeling that simulates P geochemistry based on recent insights into the geochemistry of the ocean–seafloor system on Enceladus. We find that aqueous P should predominantly exist as orthophosphate (e.g., HPO42−), and total dissolved inorganic P could reach 10−7 to 10−2 mol/kg H2O, generally increasing with lower pH and higher dissolved CO2, but also depending upon dissolved ammonia and silica. Levels are much higher than <10−10 mol/kg H2O from previous estimates and close to or higher than ∌10−6 mol/kg H2O in modern Earth seawater. The high P concentration is primarily ascribed to a high (bi)carbonate concentration, which decreases the concentrations of multivalent cations via carbonate mineral formation, allowing phosphate to accumulate. Kinetic modeling of phosphate mineral dissolution suggests that geologically rapid release of P from seafloor weathering of a chondritic rocky core could supply millimoles of total dissolved P per kilogram of H2O within 105 y, much less than the likely age of Enceladus’s ocean (108 to 109 y). These results provide further evidence of habitable ocean conditions and show that any oceanic life would not be inhibited by low P availability
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