1,028 research outputs found

    A Revised Validation Process for Ice Accretion Codes

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    A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from the latest LEWICE release, version 3.5. This program differs from previous releases in its ability to model mixed phase and ice crystal conditions such as those encountered inside an engine. It also has expanded capability to use structured grids and a new capability to use results from unstructured grid flow solvers. A quantitative comparison of the results against a database of ice shapes that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. This paper will extend the comparison of ice shapes between LEWICE 3.5 and experimental data from a previous paper. Comparisons of lift and drag are made between experimentally collected data from experimentally obtained ice shapes and simulated (CFD) data on simulated (LEWICE) ice shapes. Comparisons are also made between experimentally collected and simulated performance data on select experimental ice shapes to ensure the CFD solver, FUN3D, is valid within the flight regime. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases

    Bod1, a novel kinetochore protein required for chromosome biorientation

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    We have combined the proteomic analysis of Xenopus laevis in vitro–assembled chromosomes with RNA interference and live cell imaging in HeLa cells to identify novel factors required for proper chromosome segregation. The first of these is Bod1, a protein conserved throughout metazoans that associates with a large macromolecular complex and localizes with kinetochores and spindle poles during mitosis. Small interfering RNA depletion of Bod1 in HeLa cells produces elongated mitotic spindles with severe biorientation defects. Bod1-depleted cells form syntelic attachments that can oscillate and generate enough force to separate sister kinetochores, suggesting that microtubule–kinetochore interactions were intact. Releasing Bod1-depleted cells from a monastrol block increases the frequency of syntelic attachments and the number of cells displaying biorientation defects. Bod1 depletion does not affect the activity or localization of Aurora B but does cause mislocalization of the microtubule depolymerase mitotic centromere- associated kinesin and prevents its efficient phosphorylation by Aurora B. Therefore, Bod1 is a novel kinetochore protein that is required for the detection or resolution of syntelic attachments in mitotic spindles

    Ptychographic hyperspectral spectromicroscopy with an extreme ultraviolet high harmonic comb

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    We demonstrate a new scheme of spectromicroscopy in the extreme ultraviolet (EUV) spectral range, where the spectral response of the sample at different wavelengths is imaged simultaneously. It is enabled by applying ptychographical information multiplexing (PIM) to a tabletop EUV source based on high harmonic generation, where four spectrally narrow harmonics near 30 nm form a spectral comb structure. Extending PIM from previously demonstrated visible wavelengths to the EUV/X-ray wavelengths promises much higher spatial resolution and more powerful spectral contrast mechanism, making PIM an attractive spectromicroscopy method in both the microscopy and the spectroscopy aspects. Besides the sample, the multicolor EUV beam is also imaged in situ, making our method a powerful beam characterization technique. No hardware is used to separate or narrow down the wavelengths, leading to efficient use of the EUV radiation

    Validation Process for LEWICE by Use of a Navier-Stokes Solver

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    A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from the latest LEWICE release, version 3.5. This program differs from previous releases in its ability to model mixed phase and ice crystal conditions such as those encountered inside an engine. It also has expanded capability to use structured grids and a new capability to use results from unstructured grid flow solvers. A quantitative comparison of the results against a database of ice shapes that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. This paper will extend the comparison of ice shapes between LEWICE 3.5 and experimental data from a previous paper. Comparisons of lift and drag are made between experimentally collected data from experimentally obtained ice shapes and simulated (CFD) data on simulated (LEWICE) ice shapes. Comparisons are also made between experimentally collected and simulated performance data on select experimental ice shapes to ensure the CFD solver, FUN3D, is valid within the flight regime. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases

    Exploring the experiences of frontline nurses during the first 6 months of the COVID-19 pandemic: an integrated literature review

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    Aim: The aim of this study was to explore the experiences of frontline nurses caring for patients during the first 6 months of the COVID-19 pandemic. Design: The JBI manual for evidence synthesis and the PRISMA guidelines for reporting. Data sources: CINAHL Complete, MEDLINE, PsycINFO (EBSCO) and Scopus (Elsevier). Review Methods: The JBI Mixed Methods Data Extraction Tool following a Convergent Integrated Approach. Results: Nineteen studies were included in the review, comprising eight countries and 2525 frontline nurses. Six themes emerged encompassing frontline nurses' COVID-19 experiences including emotional experiences, physical symptoms, ethical and moral challenges, professional impact, risk factors for negative emotional experiences and protective factors for future pandemic events. Conclusion: Frontline nurses have faced numerous challenges during the COVID-19 pandemic. Providing frontline nurses with the required resources and support to perform their roles in global healthcare crises allows for an empowered and resilient workforce ensuring nurses remain in their chosen profession

    Reproductive factors, age at maximum height, and risk of three histologic types of breast cancer.

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    Numerous studies have evaluated the association between factors related to maturation and reproduction and breast cancer risk, but few have assessed how these factors are related to different histologic types of breast cancer among postmenopausal women. We used polytomous logistic regression to assess the effect of age at maximum height and reproductive factors on risk of invasive breast cancer by histologic type in three case groups (524 ductal, 324 lobular, and 196 ductal-lobular) and 469 controls enrolled in a population-based case-control study of women ages 55 to 74 years residing in the Seattle-Puget Sound region of Washington State (2000-2004). Histologic type was determined by a centralized tissue review for 83% of cases. Age at menarche and age at maximum height were inversely associated with risk of ductal-lobular carcinoma (P(trend) = 0.04 for both exposures) but not ductal or lobular carcinoma. Relative to nulliparous women, parous women had a 50% reduced risk of all histologic types of breast cancer. We observed similar increases in risk across histologic types associated with having a first live birth at ages > or = 30 years compared with ages < or = 19 years. Compared with parous women who never breast-fed, those who breast-fed had a reduced risk of ductal carcinoma (odds ratio, 0.7; 95% confidence interval, 0.5-0.9) but not lobular or ductal-lobular carcinoma. Further exploration of breast cancer risk by histology is merited to understand differences in the etiology of ductal, lobular, and ductal-lobular carcinoma

    The Loneliest Galaxies in the Universe: A GAMA and GalaxyZoo Study on Void Galaxy Morphology

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    The large-scale structure (LSS) of the Universe is comprised of galaxy filaments, tendrils, and voids. The majority of the Universe's volume is taken up by these voids, which exist as underdense, but not empty, regions. The galaxies found inside these voids are expected to be some of the most isolated objects in the Universe. This study, using the Galaxy and Mass Assembly (GAMA) and Galaxy Zoo surveys, aims to investigate basic physical properties and morphology of void galaxies versus field (filament and tendril) galaxies. We use void galaxies with stellar masses of 9.35<log(M/M⊙)<11.259.35 < log(M/M_\odot) < 11.25, and this sample is split by identifying two redshift-limited regions, 0 < z < 0.075, and, 0.075<z<0.150.075 < z < 0.15. To find comparable objects in the sample of field galaxies from GAMA and Galaxy Zoo, we identify "twins" of void galaxies as field galaxies within ±\pm0.05 dex and ±\pm0.15 dex of M and specific star formation rate. We determine the statistical significance of our results using the Kolmogorov-Smirnov (KS) test. We see that void galaxies, in contrast with field galaxies, seem to be disk-dominated and have predominantly round bulges (with > 50 percent of the Galaxy Zoo citizen scientists agreeing that bulges are present).Comment: 13 pages, 16 figures, 3 tables, accepted by MNRA

    Migraine in postmenopausal women and the risk of invasive breast cancer.

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    BACKGROUND: The frequency of migraine headache changes at various times of a woman's reproductive cycle. Menarche, menses, pregnancy, and perimenopause may carry a different migraine risk conceivably because of fluctuating estrogen levels, and in general, migraine frequency is associated with falling estrogen levels. Given the strong relationship between endogenous estrogen levels and breast cancer risk, migraine sufferers may experience a reduced risk of breast cancer. METHODS: We combined data from two population-based case-control studies to examine the relationship between migraine and risk of postmenopausal invasive breast cancer among 1,199 ductal carcinoma cases, 739 lobular carcinoma cases, and 1,474 controls 55 to 79 years of age. Polytomous logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). RESULTS: Women who reported a clinical diagnosis of migraine had reduced risks of ductal carcinoma (OR, 0.67; 95% CI, 0.54-0.82) and lobular carcinoma (OR, 0.68; 95% CI, 0.52-0.90). These associations were primarily limited to hormone receptor-positive tumors as migraine was associated with a 0.65-fold (95% CI, 0.51-0.83) reduced risk of estrogen receptor-positive (ER+)/progesterone receptor-positive (PR+) ductal carcinoma. The reductions in risk observed were seen among migraine sufferers who did and did not use prescription medications for their migraines. CONCLUSIONS: These data suggest that a history of migraine is associated with a decreased risk of breast cancer, particularly among ER+/PR+ ductal and lobular carcinomas. Because this is the first study to address an association between migraine history and breast cancer risk, additional studies are needed to confirm this finding
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