4,312 research outputs found

    Determination of general relations for the behavior of turbulent boundary layers

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    An analysis has been made of a considerable amount of data for turbulent boundary layers along wings and bodies of various shapes in order to determine the fundamental variables that control the development of turbulent boundary layers. It was found that the type of velocity distribution in the boundary layer could be expressed in terms of a single parameter. This parameter was chosen as the ratio of the displacement thickness to the momentum thickness of the boundary layer. The variables that control the development of the turbulent boundary layer apparently are: (1) the ratio of the nondimensional pressure gradient, expressed in terms of the local dynamic pressure outside the boundary layer and boundary-layer thickness, to the local skin-friction coefficient and (2) the shape of the boundary layer. An empirical equation has been developed in terms of these variables that, when used with the momentum equation and the skin-friction relation, makes it possible to trace the development of the turbulent boundary layer to the separation point

    A Mouse Amidase Specific for N-terminal Asparagine: the gene, the enzyme, and their function in the N-end rule pathway

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    The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. In both fungi and mammals, the tertiary destabilizing N-terminal residues asparagine and glutamine function through their conversion, by enzymatic deamidation, into the secondary destabilizing residues aspartate and glutamate, whose destabilizing activity requires their enzymatic conjugation to arginine, one of the primary destabilizing residues. We report the isolation and analysis of a mouse cDNA and the corresponding gene (termed Ntan1) that encode a 310-residue amidohydrolase (termed NtN-amidase) specific for N-terminal asparagine. The ~17-kilobase pair Ntan1 gene is located in the proximal region of mouse chromosome 16 and contains 10 exons ranging from 54 to 177 base pairs in length. The ~1.4-kilobase pair Ntan1 mRNA is expressed in all of the tested mouse tissues and cell lines and is down-regulated upon the conversion of myoblasts into myotubes. The Ntan1 promoter is located ~500 base pairs upstream of the Ntan1 start codon. The deduced amino acid sequence of mouse NtN-amidase is 88% identical to the sequence of its porcine counterpart, but bears no significant similarity to the sequence of the NTA1-encoded N-terminal amidohydrolase of the yeast Saccharomyces cerevisiae, which can deamidate either N-terminal asparagine or glutamine. The expression of mouse NtN-amidase in S. cerevisiae nta1Delta was used to verify that NtN-amidase retains its asparagine selectivity in vivo and can implement the asparagine-specific subset of the N-end rule. Further dissection of mouse Ntan1, including its null phenotype analysis, should illuminate the functions of the N-end rule, most of which are still unknown

    Experimental and Theoretical Studies of Area Suction for the Control of the Laminar Boundary Layer on an NACA 64a010 Airfoil

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    A low-turbulence wind-tunnel investigation was made of an NACA 64a010 airfoil having a porous surface to determine the reduction in section total-drag coefficient that might be obtained at large Reynolds numbers by the use of suction to produce continuous inflow through the surface of the airfoil (area suction). In addition to the experimental investigation, a related theoretical analysis was made to provide a basis of comparison for the test results

    Impact of changing US cigarette smoking patterns on incident cancer: Risks of 20 smoking-related cancers among the women and men of the NIH-AARP cohort

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    Background: Historically, US women started smoking at a later age than men and had lower relative risks for smoking-related cancers. However, more recent birth cohorts of women and men have similar smoking histories and have now reached the high-risk age for cancer. The impact of these changes on cancer incidence has not been systematically examined. Methods: Relative risks (RR), 95% confidence intervals (CI) and attributable fractions were calculated for cigarette smoking and incidence of 20 smoking-related cancers in 186 057 women and 266 074 men of the National Institutes of Health-AARP cohort, aged 50 to 71 years in 1995 and followed for 11 years. Results: In the cohort, which included participants born between 1924 and 1945, most women and men started smoking as teenagers. RRs for current vs never smoking were similar in women and men for the following cancers: lung squamous-cell (RR women: 121.4, 95% CI: 57.3–257.4; RR men:114.6, 95% CI: 61.2–214.4), lung adenocarcinoma (RR women: 11.7, 95% CI: 9.8–14.0; RR men: 15.6, 95% CI: 12.5–19.6), laryngeal (RR women: 37.0, 95% CI: 14.9–92.3; RR men: 13.8, 95% CI: 9.3–20.2), oral cavity-pharyngeal (RR women:4.4, 95% CI: 3.3–6.0; RR men: 3.8, 95% CI: 3.0–4.7), oesophageal squamous cell (RR women: 7.3, 95% CI: 3.5–15.5; RR men: 6.2, 95% CI: 2.8–13.7), bladder (RR women: 4.7, 95% CI: 3.7–5.8; RR men: 4.0, 95% CI: 3.5–4.5), colon (RR women: 1.3, 95% CI: 1.2–1.5; RR men: 1.3, 95% CI: 1.1–1.4), and at other sites, with similar attributable fractions. Conclusions: RRs for current smoking and incidence of many smoking-related cancers are now similar in US women and men, likely reflecting converging smoking patterns

    Keys to Profitable Summer Annual Forage Production.

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    4 p

    Crimson Clover.

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    6 p

    Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment

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    The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from 'noncompetitive' substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 per thousand. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in C-13, reaching a maximum delta(C-13) value of -42 per thousand. Third, the acetate pool experienced a precipitous decline from greater than 5 mM to less than 20 micro-M and methane production was again dominated by CO2 reduction. The delta(C-13) of methane produced during this final phase ranged from -46 to -58 per thousand. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8 percent of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane emitted from undisturbed Cape Lookout Bight sediment

    JETstream Volume 1 Issue 2

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    The JET Library kicked off 2017 with an always well-received event, our annual “Beat the Blahs” Party, sponsored by the Office of the President. This year, we featured a dessert table where members of the Molloy Community brought in their favorite desserts to share with everyone. We also held our first JET Bake-off, with Karen Cusumano, Executive Assistant in the President’s Office, being awarded a “Certificate in Excellence in Baking” with her “Classic Sour Cream Cheese Cake.” Requests have been received by the library asking if she will share her recipe! Although we definitely did enjoy a delicious feast, I think the consensus is unanimous when I say that the best part of the event was being able to spend time with everyone, engaging in good conversation, laughter and blintzes. In 2016, we welcomed several new members to the library; Tabitha Ochtera, Shikha Joseph and Sean Williams whom we look forward to you getting to know in our “Welcoming our New Additions” section. Theresa Rienzo, Associate Librarian Health Sciences and Head of Patron Services, an integral member of the JET Library is featured in our “Spotlight” article. A new column titled “What we are reading” was added, where our librarians and staff share their opinions on books from our collection. Among the various other articles, we would like to bring special attention to the “Did you know?” article where you can learn more about a new resource recently activated in the Ovid database, as well as SWANK, one of JET Library’s streaming video databases. Last but certainly not least, meet JET Library’s Official Mascot, Luciano
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