24,356 research outputs found

    Computer code for single-point thermodynamic analysis of hydrogen/oxygen expander-cycle rocket engines

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    This analysis and this computer code apply to full, split, and dual expander cycles. Heat regeneration from the turbine exhaust to the pump exhaust is allowed. The combustion process is modeled as one of chemical equilibrium in an infinite-area or a finite-area combustor. Gas composition in the nozzle may be either equilibrium or frozen during expansion. This report, which serves as a users guide for the computer code, describes the system, the analysis methodology, and the program input and output. Sample calculations are included to show effects of key variables such as nozzle area ratio and oxidizer-to-fuel mass ratio

    Complementary transcriptomic, lipidomic, and targeted functional genetic analyses in cultured Drosophila cells highlight the role of glycerophospholipid metabolism in Flock House virus RNA replication

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    Abstract Background Cellular membranes are crucial host components utilized by positive-strand RNA viruses for replication of their genomes. Published studies have suggested that the synthesis and distribution of membrane lipids are particularly important for the assembly and function of positive-strand RNA virus replication complexes. However, the impact of specific lipid metabolism pathways in this process have not been well defined, nor have potential changes in lipid expression associated with positive-strand RNA virus replication been examined in detail. Results In this study we used parallel and complementary global and targeted approaches to examine the impact of lipid metabolism on the replication of the well-studied model alphanodavirus Flock House virus (FHV). We found that FHV RNA replication in cultured Drosophila S2 cells stimulated the transcriptional upregulation of several lipid metabolism genes, and was also associated with increased phosphatidylcholine accumulation with preferential increases in lipid molecules with longer and unsaturated acyl chains. Furthermore, targeted RNA interference-mediated downregulation of candidate glycerophospholipid metabolism genes revealed a functional role of several genes in virus replication. In particular, we found that downregulation of Cct1 or Cct2, which encode essential enzymes for phosphatidylcholine biosynthesis, suppressed FHV RNA replication. Conclusion These results indicate that glycerophospholipid metabolism, and in particular phosphatidylcholine biosynthesis, plays an important role in FHV RNA replication. Furthermore, they provide a framework in which to further explore the impact of specific steps in lipid metabolism on FHV replication, and potentially identify novel cellular targets for the development of drugs to inhibit positive-strand RNA viruses.http://deepblue.lib.umich.edu/bitstream/2027.42/78268/1/1471-2164-11-183.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/2/1471-2164-11-183-S3.XLShttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/3/1471-2164-11-183-S2.XLShttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/4/1471-2164-11-183.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/5/1471-2164-11-183-S4.XLShttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/6/1471-2164-11-183-S1.XLSPeer Reviewe

    New records, nomenclatural changes, and taxonomic notes for select North American leaf beetles (Coleoptera: Chrysomelidae)

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    New records, nomenclatural changes and taxonomic notes are presented for select North American leaf beetles (Coleoptera: Chrysomelidae). The following genera are newly recorded from the United States: Nesaecrepida Blake, 1964; Acallepitrix Bechyne, 1959; Margaridisa Bechyne, 1958; Parchicola Bechyne and Springlova de Bechyne, 1975; (all Galerucinae: Alticini); and Demotina Baly, 1874 (Eumolpinae). The following species are newly recorded from the United States: Neolema dorsalis (Olivier, 1791) (Criocerinae); Charidotella bifossulata Boheman, 1855 (Hispinae: Cassidini); Syphrea flauicollis (Jacoby, 1884) (Galerucinae: Alticini); and Promecosoma inflatum Lefevre, 1877, and Demotina modesta Baly, 1874 (Eumolpinae). The following new synonymies are proposed: Deloyala clauata, var. diuersicollis Schaeffer, 1925, transferred from synonymy with Plagiometriona clauata (Fabricius, 1798) to synonymy withP. clauata testudinaria (Boheman, 1855); Chrysomela hybrida Say, 1824, downgraded from subspecies of Calligrapha lunata (Fabricius, 1787) to full synonym of CaZZigrapha lunata (Fabricius); Chrysomela casta Rogers, 1856, downgraded from subspecies of Zygogramma suturalis (Fabricius, 1775) to full synonym of Zygogrammasuturalis (Fabricius); Trirhabdagurneyi Blake, 1951, downgraded to synonym of Trirhabda caduca Horn, 1893; Scelida mimula Wilcox, 1965, downgraded to synonym of Scelida nigricornis (Jacoby, 1888); Exoracalifornica Wilcox, 1953, downgraded to synonym of Pte leon breuicornis (Jacoby, 1887); alaeothonaarizonensis Blake, 1950, downgraded to synonym ofLupraea discrepans (Schaeffer, 1932); Haltica nigritula Linell, 1898, downgraded to synonym of Nesaecrepida asphalt ina (Suffrian, 1868); Cryptocephalus reinhardi Sundman, 1965, downgraded to synonym of Cryptocephalus nwtabilis Melsheimer, 1847. The tribes Chalepini Wiese, 1910, and Uroplatini Weise, 1910 (Hispinae), are synonymized, and both of these family-group names are recognized as nomina protecta. The family-group name Octotomites Chapuis, 1875, is recognized as a nomen oblitum. Coptocycla testudinaria Boheman, 1855, is downgraded from specific status to a subspecies of Plagiometriona clauata (Fabricius, 1798); Cassida bicolor (Fabricius, 1798) is recognized as a valid subspecies of Charidotellasexpunctata (Fabricius). The genus Hemiphrynus Horn, 1889, is removed from synonymy with Phrynocepha and reinstated as a valid genus; Rhabdopterus weisei (Schaeffer, 1920) is removed from synonymy with Rhabdopterus praetextus (Say) and reinstated as a valid species. The following new combinations are proposed: Synetocephalus wallacei (Wilcox, 1965), transferred from Pseudoluperus; Nesaecrepida infuscata (Schaeffer, 1906), transferred from Monomacra; Acallepitrix nitens (Horn, 1889), transferred from Epitrix; Margaridisa atriuentris (Melsheimer, 1847), transferred from Hornaltica; Parchicola iris (Olivier, 1808) and P. tibialis (Olivier, 1808), transferred from Monomacra; and Coleothorpa panochensis (Gilbert, 1981), transferred from Coscinoptera; Promecosoma arizonae (Crotch, 1873), transferred from Metaxyonycha; Tymnes chrysis (Olivier, 1808), T. oregonensis (Crotch, 1873), and T. thaleia (Blake, 1977), transferred from Colaspis. The following new replacement name is proposed: Triarius nigroflaulls, for Luperodes flauoniger Blake, 1942 (not Laboissiere, 1925). The identities of Griburius equestris (Olivier, 1808) and G. laruatlls (Newman, 1840) are discussed

    Seismic stratigraphy and history of deep circulation and sediment drift development in Baffin Bay and the Labrador Sea

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    Drilling results and seismic-reflection records at and across Ocean Drilling Program (ODP) Sites 645 (western Baffin Bay), 646, and 647 (Labrador Sea) provide important constraints on the history of deep-water circulation and sedimentation in response to Cenozoic climatic change, as well as the tectonic evolution of the region. Sites 646 and 647 were drilled on the flanks of two sediment drift deposits—the Eirik Ridge and Gloria Drift, respectively. Age control at Site 645 was poor because of the restricted biotas there, but the drill site provides a continuous sequence from the lower Miocene to the present. Sediment at Site 646 was deposited at high rates, providing a high resolution record of the last 8.5 Ma. At Site 647 sedimentation was variable and discontinuous, but a complete upper-lower Eocene through lower Oligocene sequence was recovered, whereas the upper Oligocene to Holocene sequence was interrupted by several hiatuses. The drift sequence at Site 646 was constructed after the middle to early Pliocene (ca. 4.5 Ma). Before that time, evidence exists for variable bottom-current activity, with events at about 7.5 Ma (a change in water-mass characteristics and decreasing velocities) and 5.6 Ma (an increase in current velocity preceding the major 4.5-Ma event; R2 regional reflector). The 7.5-Ma event produced a major regional reflector (R3/R4), which was originally thought to be Eocene/ Oligocene in age. A major water-mass change also occurred at the onset of ice-rafting at about 2.5 Ma in the late Pliocene. In seismic records no evidence exists of drift building before the early Pliocene, but a probable late-middle Miocene erosional event occurred on the south flank of Eirik Ridge and along the West Greenland margin. Sediment supply from the Imarssuak mid-ocean canyon (IMOC) increased concurrently with the advent of drift construction. Gloria Drift also was built largely after the late Miocene. A major increase in sediment supply occurred in the early Pliocene, following a major hiatus (5.6 to 2.5 Ma; equivalent to the youngest possible age for the R2 reflector underlying Gloria Drift), and most seismic records exhibit sediment waves above this horizon. This increased sediment supply is the result of hemipelagic deposition from encroaching deposits of the North Atlantic mid-ocean canyon, as well as to supply of ice-rafted detritus in the late Pliocene. A hiatus encompasses the interval from approximately 17.5 to 8,2 Ma, and the interval between the two major hiatuses is extremely condensed. A deeper reflector (R3) corresponds to a change from calcareous (below) to opal-rich hemipelagic strata in the lower Oligocene, not to a regional unconformity reflecting increased bottom-water activity, as previously thought. However, some evidence exists to support a latest Eocene-earliest Oligocene increase in bottom-current activity on Gloria Drift. In Baffin Bay, there is evidence for bottom-water activity from textural studies of cores and from apparent drift features exhibited in multichannel lines along the western margin. Probable contour-currents have been active since at least the late middle Miocene, with episodes of decreasing intensity that apparently occurred in the late Miocene and Quaternary. The record from Site 645 and in seismic lines may indicate that formation of bottom water occurred in the late Neogene in Baffin Bay in conjunction with climatic deterioration, but Baffin Bay was not an important source of deep-water masses to the Labrador Sea after the late Pliocene. Not surprisingly, many of the Labrador Sea deep-circulation events correspond closely to major North Atlantic events and to important global climatic and paleoceanographic events, but a major drift-building episode may have occurred later in the Labrador Sea than it did in either the eastern North Atlantic or the western North Atlantic

    The evolution of mass loaded supernova remnants: II. Temperature dependent mass injection rates

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    We investigate the evolution of spherically symmetric supernova remnants in which mass loading takes place due to conductively driven evaporation of embedded clouds. Numerical simulations reveal significant differences between the evolution of conductively mass loaded and the ablatively mass loaded remnants studied in Paper I. A main difference is the way in which conductive mass loading is extinguished at fairly early times, once the interior temperature of the remnant falls below ~ 107 K. Thus, at late times remnants that ablatively mass load are dominated by loaded mass and thermal energy, while those that conductively mass load are dominated by swept-up mass and kinetic energy. Simple approximations to the remnant evolution, complementary to those in Paper I, are given

    Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells

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    We demonstrate enhanced external quantum efficiency and current-voltage characteristics due to scattering by 100 nm silver nanoparticles in a single 2.5 nm thick InGaN quantum well photovoltaic device. Nanoparticle arrays were fabricated on the surface of the device using an anodic alumina template masking process. The Ag nanoparticles increase light scattering, light trapping, and carrier collection in the III-N semiconductor layers leading to enhancement of the external quantum efficiency by up to 54%. Additionally, the short-circuit current in cells with 200 nm p-GaN emitter regions is increased by 6% under AM 1.5 illumination. AFORS-Het simulation software results were used to predict cell performance and optimize emitter layer thickness

    Displacement Data Assimilation

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    We show that modifying a Bayesian data assimilation scheme by incorporating kinematically-consistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information important. While the displacement transformation is not tied to any particular assimilation scheme, here we implement it within an ensemble Kalman Filter and demonstrate its effectiveness in tracking stochastically perturbed vortices.Comment: 26 Pages, 9 figures, 5 table
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