597 research outputs found

    Return-to-launch-site three degree of freedom analysis, constant inertial attitude during the fuel dissipation phase

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    Results are presented of a study to show the effect of selecting a constant inertial attitude during the fuel dissipation phase of a return-to-launch-site abort. Results are also presented which show that the selection of the constant inertial attitude will affect the arrival point on the range-velocity target line. An alternate selection of the inertial attitude will provide control over the trajectory shape

    Response of selected microorganisms to experimental planetary environments

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    The anaerobic utilization of phosphite or phosphine and the significance of this conversion to potential contamination of Jupiter were investigated. A sporeforming organism was isolated from Cape Canaveral soil which anaerobically converts hypophosphite to phosphate. This conversion coincides with an increase in turbidity of the culture and with phosphate accumulation in the medium. Investigations of omnitherms (organisms which grow over a broad temperature range, i.e. 3 -55 C were also conducted. The cellular morphology of 28 of these isolates was investigated, and all were demonstrated to be sporeformers. Biochemical characterizations are also presented. Procedures for replicate plating were evaluated, and those results are also presented. The procedures for different replicate-plating techniques are presented, and these are evaluated on the basis of reproducibility, percentage of viable transfer, and ease of use. Standardized procedures for the enumeration of microbial populations from ocean-dredge samples from Cape Canaveral are also presented

    Response of selected microorganisms to experimental planetary environments

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    Experiments indicate that hardy organisms will likely grow in the Martian environment if moisture is available, and that these organisms definitely present a threat to contamination of the biopackage if they are transported to the surface of Mars

    COVID-19 exposure and diagnosis among college student drinkers: links to alcohol use behavior, motives, and context

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    The COVID-19 pandemic is a public health crisis. College student alcohol use is highly prevalent and primarily occurs in social settings where risk for COVID-19 transmission is heightened. This study explored the associations between alcohol use frequency, quantity, motives, and context with: (i) quarantine due to COVID-19 exposure and (ii) a positive diagnosis for COVID-19. A sample of n = 409 college student drinkers completed an online survey about their health and behaviors during the Fall 2020 semester. Since the start of the semester, 36% of students quarantined and 13% of students received a COVID-19 diagnosis. More frequent alcohol use was associated with increased odds of both quarantine and COVID-19 diagnosis. More frequent drinking for social motives was associated with increased likelihood of quarantine, and more frequent drinking for conformity motives was associated with increased likelihood of COVID-19 diagnosis. Participants who often drank alone or with a small group of friends were about half as likely to have quarantined, while those who often drank with a large group of friends were almost twice as likely to have quarantined. Participants who often drank in a bar or nightclub had almost three times the odds of a COVID-19 diagnosis. Frequent alcohol use and drinking for social and conformity motives and in certain contexts are linked to increased likelihood of COVID-19 exposure and diagnosis. Alcohol use prevention efforts, coupled with messaging to discourage large social gatherings in public places, might help to mitigate the spread of COVID-19 among college students

    Scientific access into Mercer Subglacial Lake: Scientific objectives, drilling operations and initial observations

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    The Subglacial Antarctic Lakes Scientific Access (SALSA) Project accessed Mercer Subglacial Lake using environmentally clean hot-water drilling to examine interactions among ice, water, sediment, rock, microbes and carbon reservoirs within the lake water column and underlying sediments. A ∼0.4 m diameter borehole was melted through 1087 m of ice and maintained over ∼10 days, allowing observation of ice properties and collection of water and sediment with various tools. Over this period, SALSA collected: 60 L of lake water and 10 L of deep borehole water; microbes \u3e0.2 μm in diameter from in situ filtration of ∼100 L of lake water; 10 multicores 0.32-0.49 m long; 1.0 and 1.76 m long gravity cores; three conductivity-temperature-depth profiles of borehole and lake water; five discrete depth current meter measurements in the lake and images of ice, the lake water-ice interface and lake sediments. Temperature and conductivity data showed the hydrodynamic character of water mixing between the borehole and lake after entry. Models simulating melting of the ∼6 m thick basal accreted ice layer imply that debris fall-out through the ∼15 m water column to the lake sediments from borehole melting had little effect on the stratigraphy of surficial sediment cores

    Inhibition of Vaginal Lactobacilli by a Bacteriocin-Like Inhibitor Produced by Enterococcus faecium 62-6: Potential Significance for Bacterial Vaginosis

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    Objective: Bacterial vaginosis (BV) is characterized by a shift in vaginal tract ecology, which includes a decrease in the concentration and/or prevalence of facultative lactobacilli. Currently, mechanisms which could account for the disappearance of lactobacilli are not well understood. The objective of this study was to determine whether vaginal streptococci/enterococci can produce bacteriocin-like inhibitors antagonistic to vaginal lactobacilli. Methods: Seventy strains of vaginal streptococci or enterococci were tested for antagonistic activities against vaginal lactobacilli using the deferred antagonism technique. Results: One strain, Enterococcus faecium 62-6, which strongly inhibited growth of lactobacilli was selected for further characterization. The spectrum of inhibitory activity of strain 62-6 included Gram-positive organisms from the vaginal environment, although native lactobacilli from the same host were resistant to inhibitor action. Following growth inMRSbroth the strain 62-6 inhibitor was shown to be heat- (100℃, 30 minutes), cold- (4℃, less than 114 days) and pH- (4–7) stable. The sensitivity of inhibitor-containing supernatants to pepsin and α-chymotrypsin suggested an essential proteinaceous component. The inhibitor was sensitive to lipase but resistant to lysozyme. Dialysis of inhibitor-containing culture supernatants suggested a molecular mass greater than 12 000 Da. All physicochemical properties were consistent with its classification as a bacteriocin-like inhibitor. Kinetic assays demonstrated a sharp onset of inhibitor production coinciding with a concentration of 62-6 of 10(7) cfu/ml, suggesting that production may be regulated by quorum sensing. Conclusions: These results may have clinical significance as a novel mechanism to account for the decline of vaginal Lactobacillus populations and contribute to both the establishment and recurrence of BV

    Characterization of TEM1/endosialin in human and murine brain tumors

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    <p>Abstract</p> <p>Background</p> <p><it>TEM1/endosialin </it>is an emerging microvascular marker of tumor angiogenesis. We characterized the expression pattern of <it>TEM1/endosialin </it>in astrocytic and metastatic brain tumors and investigated its role as a therapeutic target in human endothelial cells and mouse xenograft models.</p> <p>Methods</p> <p><it>In situ </it>hybridization (ISH), immunohistochemistry (IH) and immunofluorescence (IF) were used to localize <it>TEM1/endosialin </it>expression in grade II-IV astrocytomas and metastatic brain tumors on tissue microarrays. Changes in <it>TEM1/endosialin </it>expression in response to pro-angiogenic conditions were assessed in human endothelial cells grown <it>in vitro</it>. Intracranial U87MG glioblastoma (GBM) xenografts were analyzed in nude <it>TEM1/endosialin </it>knockout (KO) and wildtype (WT) mice.</p> <p>Results</p> <p><it>TEM1/endosialin </it>was upregulated in primary and metastatic human brain tumors, where it localized primarily to the tumor vasculature and a subset of tumor stromal cells. Analysis of 275 arrayed grade II-IV astrocytomas demonstrated <it>TEM1/endosialin </it>expression in 79% of tumors. Robust <it>TEM1/endosialin </it>expression occurred in 31% of glioblastomas (grade IV astroctyomas). <it>TEM1/endosialin </it>expression was inversely correlated with patient age. TEM1/endosialin showed limited co-localization with CD31, αSMA and fibronectin in clinical specimens. <it>In vitro</it>, <it>TEM1/endosialin </it>was upregulated in human endothelial cells cultured in matrigel. Vascular <it>Tem1/endosialin </it>was induced in intracranial U87MG GBM xenografts grown in mice. <it>Tem1/endosialin </it>KO vs WT mice demonstrated equivalent survival and tumor growth when implanted with intracranial GBM xenografts, although <it>Tem1/endosialin </it>KO tumors were significantly more vascular than the WT counterparts.</p> <p>Conclusion</p> <p><it>TEM1/endosialin </it>was induced in the vasculature of high-grade brain tumors where its expression was inversely correlated with patient age. Although lack of <it>TEM1/endosialin </it>did not suppress growth of intracranial GBM xenografts, it did increase tumor vascularity. The cellular localization of <it>TEM1/endosialin </it>and its expression profile in primary and metastatic brain tumors support efforts to therapeutically target this protein, potentially via antibody mediated drug delivery strategies.</p
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