790 research outputs found

    The Lac au Renard Tephra Cluster: a record of Lochkovian (Lower Devonian) volcanism in the Indian Point Formation, Gaspe Peninsula, Quebec, Canada

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    Approximately twenty tephra beds, comprising the Lac au Renard Tephra Cluster (new), occur in the Rosebush Cove and Petit Portage members of the Indian Point Formation (Chaleurs Group) on the Gaspe Peninsula of Quebec, Canada. The tephra beds range in thickness from <1.0 cm to 82 cm and occur in a mudrock-dominated sequence with coarser tempestite interbeds. Mineralogically and texturally graded accumulations of phenocrysts mark the bases of the thickest tephra beds. Early diagenetic concretions in one composite tephra preserve pre-compaction fabrics and original hypocrystalline textures with microphenocrysts and devitrified glass shards. The presence of plagioclase, quartz, K-feldspar, biotite, apatite, and zircon suggest a rhyolitic source. The coarseness of the microphenocrysts in the basal accumulations, along with the abundance and thickness of the tephras, suggest that deposition in the Gaspe area was in a proximal position relative to the volcanic source. The zonal graptolites Monograptus praehercynicus and Monograptus aequabilis ssp. from the Petit Portage Member indicate a middle Lochkovian age for the Lac au Renard Tephra Cluster of the Indian Point Formation. Correlation with the tephra cluster that includes the Judds Falls Bentonite in the New Scotland Formation and other possible tephras in the Kalkberg Formation (Helderberg Group) of New York and the Corriganville and Mandata formations of Pennsylvania is likely. The graptolite fauna of the Indian Point and probable correlations to New York may provide additional biostratigraphic constraints on a U–Pb zircon radiometric age determination of 417.6 Ma from New York that has been used to estimate the age of the Silurian–Devonian boundary.Une vingtaine d’amoncellements de tĂ©phras, dont l’amas de tĂ©phras du lac au Renard (nouvel amas), sont prĂ©sents dans les membres de l’anse Rosebush et de Petit Portage de la Formation d’Indian Point (groupe de Chaleurs) en GaspĂ©sie, au QuĂ©bec, Canada. Les strates de tĂ©phras, dont l’épaisseur varie entre <1,0 cm et 82 cm, se manifestent dans une sĂ©quence Ă  prĂ©dominance de pĂ©lite interlitĂ©e de tempestite plus grossiĂšre. Des accumulations de phĂ©nocristaux dont la composition minĂ©ralogique et la texture varient progressivement marquent les bases des strates les plus Ă©paisses de tĂ©phras. Des concrĂ©tions diagĂ©nĂ©tiques prĂ©coces dans un amas de tĂ©phras composite prĂ©servent les fabriques prĂ©alables Ă  la compaction et les textures hĂ©micristallines originales en compagnie de microphĂ©nocristaux et d’éclats de verre dĂ©vitrifiĂ©s. La prĂ©sence de plagioclase, de quartz, de feldspath potassique, de biotite, d’apatite et de zircon laisse supposer une source rhyolitique. La grossiĂšretĂ© des microphĂ©nocristaux dans les accumulations basales de mĂȘme que l’abondance et l’épaisseur des amas de tĂ©phras permettent de supposer que le dĂ©pĂŽt des tĂ©phras en GaspĂ©sie est survenu Ă  proximitĂ© d’une source volcanique. Les graptolites zonaux – sous-espĂšces Monograptus praehercynicus et Monograptus aequabilis – du membre de Petit Portage confĂšrent Ă  l’amas de tĂ©phras du lac au Renard de la Formation d’Indian Point un Ăąge le situant au Lochkovien moyen. Il est probable qu’il puisse ĂȘtre corrĂ©lĂ© Ă  l’amas de tĂ©phras englobant la bentonite des chutes Judds dans la Formation de New Scotland et d’autres tĂ©phras possibles dans la Formation de Kalkberg (groupe de Helderberg) de New York ainsi que les formations de Corriganville et de Mandata en Pennsylvanie. La faune de graptolites d’Indian Point et les corrĂ©lations probables avec New York pourraient imposer d’autres contraintes biostratigraphiques Ă  la datation radiomĂ©trique U–Pb sur zircon de 417,6 Ma obtenue de New York qui a servi Ă  l’estimation de l’ñge de la limite siluro-dĂ©vonienne

    Spectra and positions of galactic gamma-ray sources

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    The UCSD/MIT Hard X-Ray and Low Energy Gamma-Ray Experiment aboard HEAO-1 scanned the galactic center region during three epochs in 1977 and 1978 from 13 to 180 keV. The results are presented from the scanning epoch of 1978 September. Twenty-two known 2 to 10 keV source positions were necessary for an acceptable fit to the data. The spectra of the 16 strongest, least confused sources are all consistent with power laws with photon spectral indices ranging from 2.1 to 7.2. Acceptable fits to thermal bremsstrahlung models are also possible for most sources. No one source in this survey can be extrapolated to higher energy to match the intensity of the gamma-ray continuum as measured by HEAO-1 large field of view detectors, which implies that the continuum is a composite of contributions from a number of sources

    A gear selection aid for agricultural tractors

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    Call number: LD2668 .T4 ME 1987 M37Master of ScienceMechanical and Nuclear Engineerin

    Advanced techniques for high resolution spectroscopic observations of cosmic gamma-ray sources

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    An advanced gamma-ray spectrometer that is currently in development is described. It will obtain a sensitivity of 0.0001 ph/sq cm./sec in a 6 hour balloon observation and uses innovative techniques for background reduction and source imaging

    Actinorhodopsin genes discovered diverse in freshwater habitats and among cultivated Actinobacteria

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    Microbial rhodopsins are membrane proteins that utilize a retinal chromophore to harvest sunlight for energetic and photosensory functions. Recently, a group of novel rhodopsin sequences named ‘actinorhodopsins’ (ActRs) was hypothesized to exist among uncultured planktonic Actinobacteria. ActRs were discovered by mining metagenomic data obtained during the Venter Institute’s Global Ocean Sampling expedition, from a hypersaline lagoon, two estuaries and a freshwater lake. On the basis of these findings, and many studies that show Actinobacteria are common inhabitants of lakes, we predicted that ActR genes would likely be present in other freshwater habitats and among the genomes of cultivated Actinobacteria. Using degenerate polymerase chain reaction primers, we discovered an ActR gene present in an actinobacterial isolate of the family Microbacteriaceae. Isolate MWH-Uga1 was cultivated prior to this study from a freshwater pond in Uganda and belongs to a group of Actinobacteria previously identified in freshwater ecosystems. ActR genes were also discovered present in numerous mixed cultures containing freshwater Actinobacteria and among environmental DNA samples obtained from three freshwater sources; a small woodland pond and the Laurentian Great Lakes Superior and Erie. An analysis of small subunit ribosomal RNA genes from metagenomic DNA samples harboring ActR genes suggests that organisms belonging to the acI lineage, an uncultured group of Actinobacteria commonly present in fresh waters, may utilize rhodopsins. The co-occurrence of an acI organism with a specific ActR variant in a mixed culture supports our hypothesis

    Reliability Exercise for the Polymyalgia Rheumatica Classification Criteria Study: The Oranjewoud Ultrasound Substudy

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    Objective. A study supported by the EULAR and the ACR being conducted to establish classification criteria for polymyalgia rheumatica (PMR) will include ultrasound examination of the shoulders and hips. Ultrasound (US) depicts glenohumeral joint effusion, biceps tenosynovitis, subdeltoid bursitis, hip joint synovitis, and trochanteric bursitis in PMR. These findings may aid in distinguishing PMR from other diseases. The purpose of this study was to assess standards and US interreader agreement of participants in the PMR classification criteria study. Methods. Sixteen physicians in four groups examined shoulders and hips of 4 patients and 4 healthy adults with ultrasound. Overall agreement and interobserver agreement were calculated. Results. The overall agreement (OA) between groups was 87%. The OA for healthy shoulders was 88.8%, for healthy hips 100%, for shoulders with pathology 85.2%, and 74.3% for hips with pathology, respectively. Conclusion. There was a high degree of agreement found for the examination of healthy shoulders and pathologic hips. Agreement was moderate for pathologic shoulders and perfect for healthy hips. US of shoulder and hips performed by different examiners is a reliable and feasible tool for assessment of PMR related disease pathology and can be incorporated into a classification criteria study

    Insights into the efficacy of golimumab plus methotrexate in patients with active rheumatoid arthritis who discontinued prior anti-tumour necrosis factor therapy: post-hoc analyses from the GO-AFTER study

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    OBJECTIVE: Evaluate golimumab in patients with active rheumatoid arthritis (RA) and previous tumour necrosis factor-alpha (TNF) inhibitor use. METHODS: Patients (n=461) previously receiving \u3e /=1 TNF inhibitor were randomised to subcutaneous injections of placebo, golimumab 50 mg or golimumab 100 mg q4 weeks. Primary endpoint ( \u3e /=20% improvement in American College of Rheumatology (ACR20) criteria at week 14) findings have been reported for all patients in the trial. Reported herein are further assessments of efficacy/safety among patients receiving golimumab+methotrexate (MTX). RESULTS: Among efficacy-evaluable patients who received MTX at baseline, more receiving golimumab+MTX (n=201) than placebo+MTX (n=103) achieved ACR20 (40.8% vs 14.6%), ACR50 (20.9% vs 3.9%), and ACR70 (11.4% vs 2.9%) responses at week 24. Among the 137 patients who had received only one prior TNF inhibitor (adalimumab, n=33; etanercept, n=47; and infliximab, n=57), week 24 ACR20 rates were 30.3%, 46.8% and 50.9%, respectively, and thus lowest among those who previously used adalimumab. ACR20 response rates were 44.5% (61/137), 36.2% (17/47) and 23.5% (4/17) among patients who had received one, two or three TNF inhibitors, respectively. Adverse event (AE) rates were comparable across type/number of prior anti-TNF agents, but appeared somewhat higher among patients who discontinued previous TNF inhibitor(s) due to intolerance (37/49, 75.5%) versus lack of efficacy (LOE, 113/191, 59.2%). CONCLUSIONS: Patients with active RA previously treated with \u3e /=1 TNF inhibitor had clinically relevant improvement with golimumab+MTX, which appeared somewhat enhanced among those who received only etanercept or infliximab as their prior TNF inhibitor. Golimumab+MTX safety appeared similar across patients, regardless of TNF inhibitor(s) previously used, with fewer AEs occurring among patients who discontinued prior therapy for LOE. already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions

    Job Search Behavior of Employed Managers

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    Job search typically has been thought of as an antecedent to voluntary turnover or job choice behavior. This study extends the existing literature by proposing a model of the job search process and examining the job search behavior of employed managers. Managers were initially surveyed about their job search activity over the past year. Approximately one year later, the same managers were surveyed to assess whether they had changed jobs since the initial survey, and the circumstances surrounding the job change. This survey data was matched with job, organizational, and personal information contained in the data base of a large executive search firm. Results suggest that dissatisfaction with different aspects of the organization and job were more strongly related to job search than were perceptions of greener pastures. Moreover, although some job search activity does facilitate turnover, a considerable amount of search does not lead to turnover. Thus, it appears that search serves many purposes. Implications of managerial job search on organizations are discussed
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