7,074 research outputs found

    Characterization of a new iron-on-zeolite Y Fischer-Tropsch catalyst

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    Iron pentacarbonyl adsorbed on dry Na-Y zeolite can be oxidized at subambient temperatures into Fe203 located in the zeolite supercages (catalyst I). When catalyst I is hydrogen reduced at 575 K most of the iron has agglomerated externally to the zeolite (catalyst 11). When the iron carbonyl is thermally decomposed in vacuo at 525 K, an iron phase with a very low degree of dispersion is again obtained (catalyst 111). During a Fischer-Tropsch reaction most of the iron is transformed into a Hagg-type carbide phase, located externally to the zeolite. Catalysts I1 and 111 rapidly reach steady state and show a Schulz-Flory-type of product distribution, the Hagg carbide being the active phase. Catalyst I slowly moves to steady state and Schulz-Flory behavior. Product selectivity is only found on this catalyst during transient conditions. The physical information on the three catalysts before and after reaction was obtained with transmission electron microscopy and Mossbauer and EXAFS spectroscopies. These techniques supplied consistent and complementary evidenc

    Space Architecture: Lunar Base Scenarios

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    A study of design alternatives for a lunar base settlement. The research explores the lunar environment requirements, program development, goal identification and processes involved in lunar design solutions. The report is the result of a 1987 graduate design studio at the UWM Department of Architecture. Graphic presentations involved the use of computer-aided design techniques (CAD). Highly illustrated.https://dc.uwm.edu/caupr_mono/1048/thumbnail.jp

    The origin of green icebergs in Antarctica

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    A comparison of samples from a translucent green iceberg with a core from the Ronne Ice Shelf revealed an excellent agreement in isotopic composition, crystal structure, and incorporated sediment particles. Marine shelf ice which constitutes the basal portion of some ice shelves is considered to be the source of green icebergs. It most likely results from "ice pump" processes which produce large amounts of ice platelets in the water column beneath ice shelves. These subsequently accumulate and become compacted into bubble-free, desalinated ice. Iceberg and drift-buoy trajectories indicate that green icebergs observed in the Weddell Sea originate from the Amery Ice Shelf rather than from the Ronne Ice Shelf, although the latter ice shelf is also a potential source

    Polymyxin B in Combination with Rifampin and Meropenem against Polymyxin B-Resistant KPC-Producing Klebsiella pneumoniae

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    Safe and effective therapies are urgently needed to treat polymyxin-resistant KPC-producing K. pneumoniae and suppress the emergence of resistance. We investigated the pharmacodynamics of polymyxin B, rifampin, and meropenem alone and as polymyxin B-based double and triple combinations against KPC-producing K. pneumoniae . The rate and extent of killing with polymyxin B (1-128mg/L), rifampin (2-16mg/L), and meropenem (10-120mg/L) were evaluated against polymyxin B-susceptible (PB S ) and -resistant (PB R ) clinical isolates using 48h static time-kills. Additionally, humanized triple drug regimens of polymyxin B (C ss : 0.5, 1, 2mg/L), rifampin 600mg every 12 or 8h, and meropenem 1 or 2g every 8h dosed as an extended 3h infusion were simulated over 48h using a one-compartment in vitro dynamic infection model. Serial bacterial counts were measured to quantify pharmacodynamic effect. Population analysis profiles (PAPs) were used to assess the emergence of polymyxin B resistance. Monotherapy was ineffective against both isolates. Polymyxin B with rifampin demonstrated early bactericidal activity against the PB S isolate followed by regrowth by 48h. Bactericidal activity was sustained at all polymyxin B concentrations ≥2 mg/L in combination with meropenem. No two-drug combinations were effective against the PB R isolate, but all simulated triple-drug regimens showed early bactericidal activity by 8h that was sustained over 48h against both strains. PAPs did not reveal the emergence of resistant subpopulations. The triple drug combination of polymyxin B, rifampin, and meropenem may be a viable consideration for the treatment of PB R KPC-producing K. pneumoniae . Further investigation is warranted to optimize triple combination therapy

    Kepler Eclipsing Binary Stars. VI. Identification of Eclipsing Binaries in the K2 Campaign 0 Data-set

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    The original {\it Kepler} mission observed and characterized over 2400 eclipsing binaries in addition to its prolific exoplanet detections. Despite the mechanical malfunction and subsequent non-recovery of two reaction wheels used to stabilize the instrument, the {\it Kepler} satellite continues collecting data in its repurposed {\it K2} mission surveying a series of fields along the ecliptic plane. Here we present an analysis of the first full baseline {\it K2} data release: the Campaign 0 data-set. In the 7761 light curves, we have identified a total of 207 eclipsing binaries. Of these, 97 are new discoveries that were not previously identified. Our pixel-level analysis of these objects has also resulted in identification of several false positives (observed targets contaminated by neighboring eclipsing binaries), as well as the serendipitous discovery of two short period exoplanet candidates. We provide catalog cross-matched source identifications, orbital periods, morphologies and ephemerides for these eclipsing systems. We also describe the incorporation of the K2 sample into the Kepler Eclipsing Binary Catalog\footnote{\url{keplerebs.villanova.edu/k2}}, present spectroscopic follow-up observations for a limited selection of nine systems, and discuss prospects for upcoming {\it K2} campaigns.Comment: Accepted for publication in MNRAS. 51 pages [20 figures, 8 tables]. Results available online in the Kepler Eclipsing Binary Star Catalog http://keplerebs.villanova.edu/k

    The toxic continuum from incivility to violence: What can HRD do

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    Abstract The frequency, intensity, and duration of uncivil behavior should be a concern to leaders in any organization. All too often seemingly isolated, subtle uncivil incidents (e.g., instigating a joke) can lead to patterns of uncivil behavior (e.g., bullying) and even physical violence. Each is a form of aggressive behavior. Inasmuch as uncivil behavior is linked to poorer individual-(e.g., job performance) and organizational-level (e.g., costs) outcomes, human resource development (HRD) is increasingly being called to implement useful strategies for dealing effectively with this vital workplace issue. The article traces the more subtle forms of uncivil behavior that tend to be ambiguous in intent to more intentional forms of uncivil behavior, that is, bullying and physical violence. The article suggests that HRD can make a strong, positive contribution to reducing the likelihood of uncivil behaviors, which in turn can play a meaningful role in increasing the success of the organization. Finally, a summary of the eight articles are presented that comprise this issue

    Weddell Sea iceberg drift: Five years of observations

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    Since 1999, 52 icebergs have been tagged with GPS buoys in the Weddell Seato enable monitoring of their position. The chosen icebergs were of small tomedium size, with a few icebergs larger than 10 km associatedwith the calving of icebergs A38 and A43 from the Ronne Ice Shelf.The majority of icebergs were tagged off Neumayer Station (8E, 70S).It was found that smaller bergs with edges shorter than 200 m had the shortestlife cycle (< 0.5 yr). Iceberg and thus freshwater export out of theWeddell Sea was found to be highly variable. In one year the majority of buoysdeployed remained in the Weddell Sea, constituting about 40 % of the NCEP P-Efreshwater input, whereas in other years all of the tagged icebergs were exported.The observed drifts of icebergs and sea-ice showed a remarkably coherent motion.The analysis of an iceberg - sea-ice buoy array in the western Weddell Seaand an iceberg array in the eastern Weddell Sea showed a coherent sea-iceiceberg drift in sea-ice concentrations above 86 %. Dynamic kinematic parameter(DKP) during the course of coherent movement were low and deviations from the meancourse associated with the passage of low-pressure system. The length scale ofcoherent movement was estimated to be less than 250km; about half the value found forthe Arctic Ocean

    International Guillain-Barré Syndrome Outcome Study (IGOS): protocol of a prospective observational cohort study on clinical and biological predictors of disease course and outcome in Guillain-Barré syndrome

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    Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy with a highly variable clinical presentation, course, and outcome. The factors that determine the clinical variation of GBS are poorly understood which complicates the care and treatment of individual patients. The protocol of the ongoing International GBS Outcome Study (IGOS), a prospective, observational, multi-centre cohort study that aims to identify the clinical and biological determinants and predictors of disease onset, subtype, course and outcome of GBS is presented here. Patients fulfilling the diagnostic criteria for GBS, regardless of age, disease severity, variant forms, or treatment, can participate if included within two weeks after onset of weakness. Information about demography, preceding infections, clinical features, diagnostic findings, treatment, course and outcome is collected. In addition, cerebrospinal fluid and serial blood samples for serum and DNA is collected at standard time points. The original aim was to include at least 1000 patients with a follow-up of 1-3 years. Data are collected via a web-based data entry system and stored anonymously. IGOS started in May 2012 and by January 2017 included more than 1400 participants from 143 active centres in 19 countries across 5 continents. The IGOS data/biobank is available for research projects conducted by expertise groups focusing on specific topics including epidemiology, diagnostic criteria, clinimetrics, electrophysiology, antecedent events, antibodies, genetics, prognostic modelling, treatment effects and long-term outcome of GBS. The IGOS will help to standardize the international collection of data and biosamples for future research of GBS. ClinicalTrials.gov Identifier: NCT01582763

    Differentiating normal and problem gambling: a grounded theory approach.

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    A previous study (Ricketts &amp; Macaskill, 2003) delineated a theory of problem gambling based on the experiences of treatment seeking male gamblers and allowed predictions to be made regarding the processes that differentiate between normal and problem gamblers. These predictions are the focus of the present study, which also utilised a grounded theory approach, but with a sample of male high frequency normal gamblers. The findings suggest that there are common aspects of gambling associated with arousal and a sense of achievement. The use of gambling to manage negative emotional states differentiated normal and problem gambling. Perceived self-efficacy , emotion management skills and perceived likelihood of winning money back were intervening variables differentiating problem and normal gamblers.</p
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