2,620 research outputs found

    Feasibility of observer system for determining orientation of balloon borne observational platforms

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    An observer model for predicting the orientation of balloon borne research platforms was developed. The model was employed in conjunction with data from the LACATE mission in order to determine the platform orientation as a function of time

    Effect of wind gusts on the motion of a balloon-borne observation platform

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    The effect of wind gusts on the magnitude of the pendulation angles of a balloon-borne observation platform is determined. A system mathematical model is developed and the solution of this model is used to determine the magnitude of the observation platforms pendulation angles

    Support and power plant documentation for the gas turbine powered bus demonstration program

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    The operational experience obtained for the GT404-4 gas turbine engines in the intercity and intracity Bus Demonstration Programs is described for the period January 1980 through September 1981. Support for the engines and automatic transmissions involved in this program provided engineering and field service, spare parts and tools, training, and factory overhauls. the Greyhound (intercity) coaches accumulated 183,054 mi (294,595 km) and 5154 hr of total operation. The Baltimore Transit (intracity) coaches accumulated 40,567 mi (65,285 km) and 1840 hr of total operation. In service, the turbine powered Greyhound and Transit coaches achieved approximately 25% and 40% lower fuel mileage, respectively, than did the production diesel powered coaches. The gas turbine engine will require the advanced ceramic development currently being sponsored by the DOE and NASA to achieve fuel economy equivalent not only to that of today's diesel engines but also to the projected fuel economy of the advanced diesel engines of the 1990s. Sufficient experience was not achieved with the coaches prior to the start of service to identify and eliminate many of the problems associated with the startup of new equipment. Because of these problems, the mean miles between incident were unacceptably low. The future gas turbine system should be developed sufficiently to establish satisfactory durability prior to evaluation in revenue service. Commercialization of the gas turbine bus engine remains a viable goal for the future

    On the Integrable Structure of the Ising Model

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    Starting from the lattice A3A_3 realization of the Ising model defined on a strip with integrable boundary conditions, the exact spectrum (including excited states) of all the local integrals of motion is derived in the continuum limit by means of TBA techniques. It is also possible to follow the massive flow of this spectrum between the UV c=1/2c=1/2 conformal fixed point and the massive IR theory. The UV expression of the eigenstates of such integrals of motion in terms of Virasoro modes is found to have only rational coefficients and their fermionic representation turns out to be simply related to the quantum numbers describing the spectrum.Comment: 18 pages, no figure

    Working Parents and Child Care: Charting a New Course for Quality

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    Close to two-thirds of children in Maine under the age of five need child care while their parents work. The quality of child care is a critical policy concern, since research has found that early childhood experience plays a major role in later-life success for individuals. The authors report on findings from three studies regarding child care arrangements in Maine and the quality of child care in the state and nationally. They describe the development and implementation of Maine’s new Quality Rating System (QRS) for child care facilities, Quality for ME, and the role that it can play both in improving child care and in helping parents chose quality care

    microRNA-377-3p downregulates the oncosuppressor T-cadherin in colorectal adenocarcinoma cells

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    Colorectal cancer (CRC) is the second leading cause of death of malignant tumors worldwide. Recent studies point to a role for the adiponectin-receptor axis in colorectal carcinogenesis, and in particular to the oncosuppressive properties of the T-cadherin receptor. In addition, the loss of T-cadherin expression in tumor tissues has been linked to cancer progression and attributed to aberrant methylation of its promoter. Recognizing the pivotal role of microRNAs in CRC, this study explores their possible contribution to the downregulation of T-cadherin. A systematic bioinformatics analysis, restricted by microRNA expression data in the colon or in cultured colorectal cell lines, predicted twelve top-ranking target miRNA sites within the 3ʹ UTR of T-cadherin. Experimental validation analyses based on luciferase reporter constructs and miRNA mimic or miRNA inhibitor transfections toward colorectal adenocarcinoma cell lines indicated that miR-377-3p was able to directly bind to the T-cadherin sequence, and thus downregulating its expression. Given the oncogenic activity of miR-377 and the oncosuppressive activity of T-cadherin in CRC, the regulatory circuit highlighted in this study may add new insights into molecular mechanisms driving colorectal carcinogenesis, and perspectively it could be exploited to identify novel biomarkers and therapeutic targets

    Attitude determination of a high altitude balloon system. Part 1: Development of the mathematical model

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    A mathematical model for predicting the three dimensional motion of the balloon system is developed, which includes the effects of bounce, pendulation and spin of each subsystem. Boundary layer effects are also examined, along with the aerodynamic forces acting on the balloon. Various simplified forms of the system mathematical model were developed, based on an order of magnitude analysis

    Microbial communities at the borehole observatory on the Costa Rica Rift flank (Ocean Drilling Program Hole 896A)

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    The microbiology of subsurface, hydrothermally influenced basaltic crust flanking mid-ocean ridges has remained understudied, due to the difficulty in accessing the subsurface environment. The instrumented boreholes resulting from scientific ocean drilling offer access to samples of the formation fluids circulating through oceanic crust. We analyzed the phylogenetic diversity of bacterial communities of fluid and microbial mat samples collected in situ from the observatory at Ocean Drilling Program Hole 896A, drilled into ~6.5 million-year-old basaltic crust on the flank of the Costa Rica Rift in the equatorial Pacific Ocean. Bacterial 16S rRNA gene sequences recovered from borehole fluid and from a microbial mat coating the outer surface of the fluid port revealed both unique and shared phylotypes. The dominant bacterial clones from both samples were related to the autotrophic, sulfur-oxidizing genus Thiomicrospira. Both samples yielded diverse gamma- and alphaproteobacterial phylotypes, as well as members of the Bacteroidetes, Planctomycetes, and Verrucomicrobia. Analysis of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) genes (cbbL and cbbM) from the sampling port mat and from the borehole fluid demonstrated autotrophic carbon assimilation potential for in situ microbial communities; most cbbL genes were related to those of the sulfur-oxidizing genera Thioalkalivibrio and Thiomicrospira, and cbbM genes were affiliated with uncultured phylotypes from hydrothermal vent plumes and marine sediments. Several 16S rRNA gene phylotypes from the 896A observatory grouped with phylotypes recovered from seawater-exposed basalts and sulfide deposits at inactive hydrothermal vents, but there is little overlap with hydrothermally influenced basaltic boreholes 1026B and U1301A on the Juan de Fuca Ridge flank, suggesting that site-specific characteristics of Hole 896A (i.e., seawater mixing into borehole fluids) affect the microbial community composition

    Distribution and Community Characteristics of Staging Shorebirds on the Northern Coast of Alaska

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    Avian studies conducted in the 1970s on Alaska’s Arctic Coastal Plain (ACP) indicated that coastal littoral habitats are important to Arctic-breeding shorebirds for staging prior to fall migration. However, relatively little recent, broad-scale, or quantitative information exists on shorebird use of staging areas in this region. To locate possible shorebird concentration areas in the littoral zone of the ACP, we conducted aerial surveys from the southwest end of Kasegaluk Lagoon on the Chukchi Sea to Demarcation Point on the Beaufort Sea during the summers of 2005–07. These surveys identified persistent within- and between-year concentrations of staging shorebirds at Peard Bay, Point Barrow/Elson Lagoon, Cape Simpson, and Smith Bay to Cape Halkett. Among river deltas in the Beaufort Sea, the Sagavanirktok and Kongakut deltas had large concentrations of staging shorebirds. We also collected data on shorebird community characteristics, staging phenology, and habitat use in 2005 and 2006 by conducting land-based surveys at six camps: Kasegaluk Lagoon, Peard Bay, Point Barrow/Elson Lagoon, Colville Delta, Sagavanirktok Delta, and Okpilak Delta. The shorebird community was more even and diverse (evenness E and Shannon Weiner H’) along the Beaufort Sea compared to the Chukchi Sea and in 2005 versus 2006. Staging phenology varied by species and location and differed for several species from that reported in previous studies. Our results suggest the existence of three foraging habitat guilds among the shorebird species observed in this study: gravel beach, mudflat, and salt marsh/pond edge. A comparison to data collected in the mid-1970s suggests that these foraging associations are conserved through time. Results from this research will be useful to land managers for monitoring the effects of changing environmental conditions and human activity on shorebirds and their habitats in Arctic Alaska.Des études aviaires réalisées dans les années 1970 sur la plaine côtière de l’Arctique en Alaska ont permis de constater que les habitats du littoral côtier revêtent de l’importance pour les oiseaux de rivage nicheurs de l’Arctique en halte migratoire avant la migration d’automne. Cependant, relativement peu d’information récente, à grande échelle ou quantitative existe à propos de l’utilisation que font les oiseaux de rivage des haltes migratoires de cette région. Afin de localiser des zones de concentration possibles d’oiseaux de rivage dans la région littorale de la plaine côtière de l’Arctique, nous avons effectué des levés aériens du sud-ouest de la lagune Kasegaluk dans la mer des Tchouktches jusqu’à Demarcation Point dans la mer de Beaufort au cours des étés allant de 2005 à 2007. Ces levés ont permis de repérer des concentrations durables d’oiseaux de rivage en halte migratoire au cours d’une même année ainsi que d’une année à l’autre à la baie Peard, à pointe Barrow et à la lagune Elson, au cap Simpson de même que de la baie Smith jusqu’au cap Halkett. Parmi les deltas de rivières de la mer de Beaufort, les deltas Sagavanirktok et Kongakut comptaient de fortes concentrations d’oiseaux de rivage en halte migratoire. Nous avons également recueilli des données sur les caractéristiques des populations d’oiseaux de rivage, sur la phénologie des haltes migratoires de même que sur l’utilisation des habitats en 2005 et en 2006 au moyen de levés terrestres effectués à six camps, soit celui de la lagune Kasegaluk, de la baie Peard, de la pointe Barrow et de la lagune Elson, du delta Colville, du delta Sagavanirktok et du delta Okpilak. La population d’oiseaux de rivage était plus homogène et diverse (homogénéité E et Shannon Weiner H’) le long de la mer de Beaufort comparativement à la mer des Tchouktches, ainsi qu’en 2005 par rapport à 2006. La phénologie en halte migratoire variait selon les espèces et les emplacements, et différait pour plusieurs espèces de celles signalées dans le cadre d’études ultérieures. Nos résultats laissent croire à l’existence de trois guildes d’habitats de fourrage chez les espèces d’oiseaux de rivage observées dans cette étude : plage de gravier, vasière et marais salant ou bordure d’étang. La comparaison des données recueillies au milieu des années 1970 laisse entendre que ces associations de fourrage se sont conservées au fil du temps. Les résultats découlant de cette recherche seront utiles aux gestionnaires de terres dans le cadre de la surveillance des effets des conditions environnementales changeantes et de l’activité humaine sur les oiseaux de rivage et leurs habitats de l’Arctique alaskien
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