7,022 research outputs found

    Paper Session II- B - Alternative Fuel Transport using semi volatile Ammonia

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    A major constraint to exploring space is the ability to carry the necessary fuel and oxidizer for a return trip. The aerospace community is continuously looking for methods to derive the fuel or oxidizer from In-situ resources. In the case of Mars, one option would be to derive the oxidizer from the C02 rich atmosphere. This process relies on the ability to deliver hydrogen from earth to mars. The weight of the fuel is only 5%-10% of the overall system weight required to transport it. The Space Shuttle and some expendable launch vehicles utilize liquid hydrogen providing a high density storage technique. Alternative storage methods that would achieve hydrogen capacities greater than 10% are much sought after for both terrestrial and space based applications. This paper describes one method of transporting hydrogen to Mars by anhydrous ammonia. By chemically binding the hydrogen in the ammonia a storage capacity greater than 15% (mass of hydrogen to mass of total system) is theoretically possible. The ammonia is then dissociated into hydrogen and nitrogen using a patented microwave electro-thermal plasma reactor. The hydrogen is then available as a feedstock for processing or as a fuel for a fuel cell or propulsion system

    The evolution of RNAs with multiple functions

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    Increasing numbers of transcripts have been reported to transmit both protein-coding and regulatory information. Apart from challenging our conception of the gene, this observation raises the question as to what extent this phenomenon occurs across the genome and how and why such dual encoding of function has evolved in the eukaryotic genome. To address this question, we consider the evolutionary path of genes in the earliest forms of life on Earth, where it is generally regarded that proteins evolved from a cellular machinery based entirely within RNA. This led to the domination of protein-coding genes in the genomes of microorganisms, although it is likely that RNA never lost its other capacities and functionalities, as evidenced by cis-acting riboswitches and UTRs. On the basis that the subsequent evolution of a more sophisticated regulatory architecture to provide higher levels of epigenetic control and accurate spatiotemporal expression in developmentally complex organisms is a complicated task, we hypothesize: (i) that mRNAs have been and remain subject to secondary selection to provide trans-acting regulatory capability in parallel with protein-coding functions; (ii) that some and perhaps many protein-coding loci, possibly as a consequence of gene duplication, have lost protein-coding functions en route to acquiring more sophisticated trans-regulatory functions; (iii) that many transcripts have become subject to secondary processing to release different products; and (iv) that novel proteins have emerged within loci that previously evolved functionality as regulatory RNAs. In support of the idea that there is a dynamic flux between different types of informational RNAs in both evolutionary and real time, we review recent observations that have arisen from transcriptomic surveys of complex eukaryotes and reconsider how these observations impact on the notion that apparently discrete loci may express transcripts with more than one function. In conclusion, we posit that many eukaryotic loci have evolved the capacity to transact a multitude of overlapping and potentially independent functions as both regulatory and protein-coding RNAs

    CPCP: Colorado Plateau Coring Project — 100 Million Years of Early Mesozoic Climatic, Tectonic, and Biotic Evolution of an Epicontinental Basin Complex

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    Early Mesozoic epicontinental basins of western North America contain a spectacular record of the climatic and tectonic development of northwestern Pangea as well as what is arguably the world's richest and most-studied Triassic-Jurassic continental biota. The Colorado Plateau and its environs (Fig. 1) expose the textbook example of these layered sedimentary records (Fig. 2). Intensely studied since the mid-nineteenth century, the basins, their strata, and their fossils have stimulated hypotheses on the development of the Early Mesozoic world as reflected in the international literature. Despite this long history of research, the lack of numerical time calibration, the presence of major uncertainties in global correlations, and an absence of entire suites of environmental proxies still loom large and prevent integration of this immense environmental repository into a useful global picture. Practically insurmountable obstacles to outcrop sampling require a scientific drilling experiment to recover key sedimentary sections that will transform our understanding of the Early Mesozoic world

    A robust, multisite Holocene history of drift ice off northern Iceland: implications for North Atlantic climate

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    An important indicator of Holocene climate change is provided by evidence for variations in the extent of drift ice. A proxy for drift ice in Iceland waters is provided by the presence of quartz. Quantitative xray diffraction analysis of the \u3c 2 mm sediment fraction was undertaken on 16 cores from around Iceland. The quartz weight (wt.)% estimates from each core were integrated into 250-yr intervals between −0.05 and 11.7 cal. ka BP. Median quartz wt.% varied between 0.2 and 3.4 and maximum values ranged between 2.8 and 11.8 wt.%. High values were attained in the early Holocene and minimum values were reached 6–7 cal. ka BP. Quartz wt.% then rose steadily during the late Holocene. Our data exhibit no correlation with counts on haematite-stained quartz (HSQ) grains from VM129-191 west of Ireland casting doubt on the ice-transport origin. A pilot study on the provenance of Fe oxide grains in two cores that cover the last 1.3 and 6.1 cal. ka BP indicated a large fraction of the grains between 1 and 6 cal. ka BP were from either Icelandic or presently unsampled sources. However, there was a dramatic increase in Canadian and Russian sources from the Arctic Ocean ~1 cal. ka BP. These data may indicate the beginning of an Arctic Oscillation-like climate mode

    A robust, multisite Holocene history of drift ice off northern Iceland: implications for North Atlantic climate

    Get PDF
    An important indicator of Holocene climate change is provided by evidence for variations in the extent of drift ice. A proxy for drift ice in Iceland waters is provided by the presence of quartz. Quantitative xray diffraction analysis of the \u3c 2 mm sediment fraction was undertaken on 16 cores from around Iceland. The quartz weight (wt.)% estimates from each core were integrated into 250-yr intervals between −0.05 and 11.7 cal. ka BP. Median quartz wt.% varied between 0.2 and 3.4 and maximum values ranged between 2.8 and 11.8 wt.%. High values were attained in the early Holocene and minimum values were reached 6–7 cal. ka BP. Quartz wt.% then rose steadily during the late Holocene. Our data exhibit no correlation with counts on haematite-stained quartz (HSQ) grains from VM129-191 west of Ireland casting doubt on the ice-transport origin. A pilot study on the provenance of Fe oxide grains in two cores that cover the last 1.3 and 6.1 cal. ka BP indicated a large fraction of the grains between 1 and 6 cal. ka BP were from either Icelandic or presently unsampled sources. However, there was a dramatic increase in Canadian and Russian sources from the Arctic Ocean ~1 cal. ka BP. These data may indicate the beginning of an Arctic Oscillation-like climate mode

    Effect of the Angiotensin I Converting Enzyme Inhibitor, MK-421, on Experimentally Induced Drinking

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    MK-421, the ethyl ester maleate salt of N-(S)-1-(ethoxycarbonyl)-3-phenyl-propyl- Ala-L-Pro, is an angiotensin I converting enzyme inhibitor. An initial objective was to determine whether MK-421, administered at 0, 2.5, 5.0, 10.0, 20.0 and 40.0 mg/kg, ip to 96 female rats 15 min prior to administration of the beta-adrenergic agonist, isoproterenol (25 microgram/kg, ip), would inhibit the drinking induced by isoproterenol during 2 h after its administration. The water intake induced by isoproterenol was inhibited significantly by 2.5 mg MK-421/kg. When a similar experiment was performed using Angiotensin I (AI) (200 microgram/kg, ip) as the dipsogenic agent, MK-421 (5 mg/kg, ip), administered 15 min prior to AI, inhibited significantly both the dipsogenic and the diuretic effect of AI. However, administration of angiotensin II (AII, 200 microgram/kg, ip) 15 min after MK-421 (5mg/kg) was accompanied by a water intake that did not differ from AII alone. The drink induced by ip administration of 1.0 m NaCl solution (1% of body wt, ip) was not inhibited by administration of MK-421 (5 mg/kg) 15 min prior to allowing access to water while the drink induced by a 24 h dehydration was partially inhibited. Thus, the drinks induced by administraition of either isoproterenol or AI are dependent on formation of AII. That induced by dehydration is partially dependent, while that induced by hypertonic siilinc is independent of the formation of AII

    Bear Facts

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    https://openspace.dmacc.edu/banner_news/1491/thumbnail.jp

    A Robust, Multisite Holocene History of Drift Ice off Northern Iceland: Implications for North Atlantic Climate

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    An important indicator of Holocene climate change is provided by evidence for variations in the extent of drift ice. A proxy for drift ice in Iceland waters is provided by the presence of quartz. Quantitative xray diffraction analysis of the \u3c 2 mm sediment fraction was undertaken on 16 cores from around Iceland. The quartz weight (wt.)% estimates from each core were integrated into 250-yr intervals between −0.05 and 11.7 cal. ka BP. Median quartz wt.% varied between 0.2 and 3.4 and maximum values ranged between 2.8 and 11.8 wt.%. High values were attained in the early Holocene and minimum values were reached 6–7 cal. ka BP. Quartz wt.% then rose steadily during the late Holocene. Our data exhibit no correlation with counts on haematite-stained quartz (HSQ) grains from VM129-191 west of Ireland casting doubt on the ice-transport origin. A pilot study on the provenance of Fe oxide grains in two cores that cover the last 1.3 and 6.1 cal. ka BP indicated a large fraction of the grains between 1 and 6 cal. ka BP were from either Icelandic or presently unsampled sources. However, there was a dramatic increase in Canadian and Russian sources from the Arctic Ocean ~1 cal. ka BP. These data may indicate the beginning of an Arctic Oscillation-like climate mode

    A Framework for Integrating and Managing Expectations of Multiple Stakeholder Groups in a Collaborative Partnership

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    The success of collaborative partnerships depends on the integration and management of multiple stakeholder expectations to develop mutually agreeable solutions that lead to desired environmental conditions and social well-being. The North Carolina Sentinel Landscapes Partnership (NCSLP) provides an example of a coalition representing Extension, military, conservation, natural resources, and economic interests to address conservation of forest and farm lands. This article presents a framework for determining the diverse expectations of large collaborative programs and integrating them into an outcome-based decision making model
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