1,289 research outputs found

    Interview with Louis P. Christman

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    Discusses Wright airplanes (especially 1905 model he restored), DeHavilland airplanes, Orville Wright, Wilbur Wright, and Edward A. (Colonel) Deeds

    Hot-wire Anemometer Behaviour In Low Velocity Air Flow

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    The behavior characteristics of a commercially available hot-wire anemometer have been examined in the presence of low velocities, lwss than 0.1 m/s for the most part, and in both horizontal and vertical air flows. The orientation of the probe in a horizontal flow has been found to have a definite effect on velocity measurements, and a lower limit to the reliable application of hot-wire anemometry has been evaluated for a particular type of probe. Vertical flow measurements have resulted in the discovery of the magnitude of natural convective velocity, and a possible method for determining the dimensions of the temperature jump distance has been developed indirectly from the description of the shape of the calibration curve

    Previously Unidentified Changes in Renal Cell Carcinoma Gene Expression Identified by Parametric Analysis of Microarray Data

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    BACKGROUND. Renal cell carcinoma is a common malignancy that often presents as a metastatic-disease for which there are no effective treatments. To gain insights into the mechanism of renal cell carcinogenesis, a number of genome-wide expression profiling studies have been performed. Surprisingly, there is very poor agreement among these studies as to which genes are differentially regulated. To better understand this lack of agreement we profiled renal cell tumor gene expression using genome-wide microarrays (45,000 probe sets) and compare our analysis to previous microarray studies. METHODS. We hybridized total RNA isolated from renal cell tumors and adjacent normal tissue to Affymetrix U133A and U133B arrays. We removed samples with technical defects and removed probesets that failed to exhibit sequence-specific hybridization in any of the samples. We detected differential gene expression in the resulting dataset with parametric methods and identified keywords that are overrepresented in the differentially expressed genes with the Fisher-exact test. RESULTS. We identify 1,234 genes that are more than three-fold changed in renal tumors by t-test, 800 of which have not been previously reported to be altered in renal cell tumors. Of the only 37 genes that have been identified as being differentially expressed in three or more of five previous microarray studies of renal tumor gene expression, our analysis finds 33 of these genes (89%). A key to the sensitivity and power of our analysis is filtering out defective samples and genes that are not reliably detected. CONCLUSIONS. The widespread use of sample-wise voting schemes for detecting differential expression that do not control for false positives likely account for the poor overlap among previous studies. Among the many genes we identified using parametric methods that were not previously reported as being differentially expressed in renal cell tumors are several oncogenes and tumor suppressor genes that likely play important roles in renal cell carcinogenesis. This highlights the need for rigorous statistical approaches in microarray studies.National Institutes of Healt

    State Takeover, School Restructuring, Private Management, and Student Achievement in Philadelphia

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    Following a state takeover of the Philadelphia public schools in 2002, 45 schools were turned over to private managers, making Philadelphia the site of the nation's largest experiment in the private management of public schools. This collaborative study by RAND Corporation and Research for Action examines achievement effects in the privately managed schools, as well as in schools with district-led interventions, and examines these effects in the context of districtwide trends in achievement

    Gene expression in the deep biosphere

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    Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 499 (2013): 205-208, doi:10.1038/nature12230.Scientific ocean drilling has revealed a deep biosphere of widespread microbial life in sub-seafloor sediment. Microbial metabolism in the marine subsurface likely plays an important role in global biogeochemical cycles1-3 but deep biosphere activities are not well understood1. Here, we describe and analyze the first subseafloor metatranscriptomes from anaerobic Peru Margin sediment up to 159 meters below seafloor (mbsf) represented by over 1 billion cDNA sequence reads. Anaerobic metabolism of amino acids, carbohydrates, and lipids appear to be dominant metabolic processes, and profiles of dissimilatory sulfite reductase (Dsr) transcripts are consistent with porewater sulfate concentration profiles1. Moreover, transcripts involved in cell division increase as a function of microbial cell concentration, indicating that increases in subseafloor microbial abundance are a function of cell division across all three domains of life. These data support calculations1 and models4 of subseafloor microbial metabolism and represent the first holistic picture of deep biosphere activities.This work was fostered by a Center for Dark Energy Biosphere Investigations (CDEBI) grant OCE-0939564 to WO and a NSF IOS grant 1238801 to JFB.2013-12-1

    Intrinsic Energy Localization through Discrete Gap Breathers in One-Dimensional Diatomic Granular Crystals

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    We present a systematic study of the existence and stability of discrete breathers that are spatially localized in the bulk of a one-dimensional chain of compressed elastic beads that interact via Hertzian contact. The chain is diatomic, consisting of a periodic arrangement of heavy and light spherical particles. We examine two families of discrete gap breathers: (1) an unstable discrete gap breather that is centered on a heavy particle and characterized by a symmetric spatial energy profile and (2) a potentially stable discrete gap breather that is centered on a light particle and is characterized by an asymmetric spatial energy profile. We investigate their existence, structure, and stability throughout the band gap of the linear spectrum and classify them into four regimes: a regime near the lower optical band edge of the linear spectrum, a moderately discrete regime, a strongly discrete regime that lies deep within the band gap of the linearized version of the system, and a regime near the upper acoustic band edge. We contrast discrete breathers in anharmonic FPU-type diatomic chains with those in diatomic granular crystals, which have a tensionless interaction potential between adjacent particles, and highlight in that the asymmetric nature of the latter interaction potential may lead to a form of hybrid bulk-surface localized solutions

    Adequacy of Cancer Screening in Adult Women with Congenital Heart Disease

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    Adults with congenital heart disease (ACHD) face noncardiac healthcare challenges as the population ages. We assessed whether women with ACHD have comparable cancer screening rates to non-ACHD women in a cardiac practice and to the general population. We performed a retrospective review of 175 adult women seen in a cardiac care center in 2009–2011. Data on Pap tests, mammography, and colonoscopies, were collected through electronic medical records and primary care provider records. Adequate documentation was available for 100 individuals with ACHD and 40 comparator cardiac patients. The adequacy of screening was determined using guidelines set forth by the American Cancer Society in 2010. Compared with the national average, ACHD patients had significantly lower rates of Pap tests (60% versus 83%, P < 0.001) and mammography (48% versus 72%, P < 0.001). Compared with non-ACHD women in the same practice, ACHD patients had consistently lower rates of mammography (48% versus 81%, P = 0.02) and colonoscopies (54% versus 82%, P = 0.23). As the population of ACHD individuals ages, attention to cancer screening becomes increasingly important but may be overlooked in this population. Primary care physicians and cardiologists should collaborate to ensure appropriate cancer screening for this growing population
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