793 research outputs found

    NiO Nanofibers as a Candidate for a Nanophotocathode

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    p-type NiO nanofibers have been synthesized from a simple electrospinning and sintering procedure. For the first time, p-type nanofibers have been electrospun onto a conductive fluorine doped tin oxide (FTO) surface. The properties of the NiO nanofibers have been directly compared to that of bulk NiO nanopowder. We have observed a p-type photocurrent for a NiO photocathode fabricated on an FTO substrate

    A Mid-Infrared Imaging Survey of Proto-Planetary Nebula Candidates

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    We present the data from a mid-infrared imaging survey of 66 proto-planetary nebula candidates using two mid-IR cameras (MIRAC2 and Berkcam) at the NASA Infrared Telescope Facility and the United Kingdom Infrared Telescope. The goal of this survey is to determine the size, flux, and morphology of the mid-IR emission regions, which sample the inner regions of the circumstellar dust shells of proto-planetary nebulae. We imaged these proto-planetary nebulae with narrow-band filters (Ī”Ī»/Ī»āˆ¼10\Delta\lambda / \lambda \sim 10%) at wavelengths of notable dust features. With our typical angular resolution of 1\arcsec, we resolve 17 sources, find 48 objects unresolved, and do not detect 1 source. For several sources, we checked optical and infrared associations and positions of the sources. In table format, we list the size and flux measurements for all the detected objects and show figures of all the resolved sources. Images for all the detected objects are available on line in FITS format from the Astronomy Digital Image Library at the National Center for Supercomputing Application. The proto-planetary nebula candidate sample includes, in addition to the predominant proto-planetary nebulae, extreme asymptotic giant branch stars, young planetary nebulae, a supergiant, and a luminous blue variable. We find that dust shells which are cooler (Tāˆ¼150\rm T \sim 150 K) and brighter in the infrared are more easily resolved. Eleven of the seventeen resolved sources are extended and fall into one of two types of mid-IR morphological classes: core/elliptical or toroidal. Core/elliptical structures show unresolved cores with lower surface brightness elliptical nebulae. Toroidal structures show limb-brightened peaks suggesting equatorial density enhancements. We argue that core/ellipticals have denser dust shells than toroidals.Comment: 32 pages, 5 tables, 2 e/ps figures (fig3 is available through ADIL [see text]), to be published in ApJS May 1999 issu

    Processing CCD Images to Detect Transits of Earth-Sized Planets: Maximizing Sensitivity While Achieving Reasonable Downlink Requirements

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    We have performed end-to-end laboratory and numerical simulations to demonstrate the capability of differential photometry under realistic operating conditions to detect transits of Earth-sized planets orbiting solar-like stars. Data acquisition and processing were conducted using the same methods planned for the proposed Kepler Mission. These included performing aperture photometry on large-format CCD images of an artificial star fields obtained without a shutter at a readout rate of 1 megapixel/sec, detecting and removing cosmic rays from individual exposures and making the necessary corrections for nonlinearity and shutterless operation in the absence of darks. We will discuss the image processing tasks performed `on-board' the simulated spacecraft, which yielded raw photometry and ancillary data used to monitor and correct for systematic effects, and the data processing and analysis tasks conducted to obtain lightcurves from the raw data and characterize the detectability of transits. The laboratory results are discussed along with the results of a numerical simulation carried out in parallel with the laboratory simulation. These two simulations demonstrate that a system-level differential photometric precision of 10-5 on five- hour intervals can be achieved under realistic conditions

    Examination of the Structural Response of the Orion European Service Module to Reverberant and Direct Field Acoustic Testing

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    The NASA Orion Multi-Purpose Crew Vehicle (MPCV), comprised of the Service Module, the Crew Module, and the Launch Abort System, is the next generation human spacecraft designed and built for deep space exploration. Orion will launch on NASAs new heavy-lift rocket, the Space Launch System. The European Space Agency (ESA) is responsible for providing the propulsion sub-assembly of the Service Module to NASA, called the European Service Module (ESM). The ESM is being designed and built by Airbus Safran Launchers for ESA. Traditionally, NASA has utilized reverberant acoustic testing for qualification of spaceflight hardware. The ESM Structural Test Article (E-STA) was tested at the NASA Plum Brook Stations (PBS) Reverberant Acoustic Test Facility in April-May 2016. However, Orion is evaluating an alternative acoustic test method, using direct field acoustic excitation, for the MPCVs Service Module and Crew Module. Lockheed Martin is responsible for the Orion proof-of-concept direct field acoustic test program. The E-STA was exposed to direct field acoustic testing at NASA PBS in February 2017. This paper compares the dynamic response of the E-STA structure and its components to both the reverberant and direct field acoustic test excitations. Advantages and disadvantages of direct field acoustic test excitation method are discussed

    Precision exercise medicine: understanding exercise response variability

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    There is evidence from human twin and family studies as well as mouse and rat selection experiments that there are considerable interindividual differences in the response of cardiorespiratory fitness (CRF) and other cardiometabolic traits to a given exercise programme dose. We developed this consensus statement on exercise response variability following a symposium dedicated to this topic. There is strong evidence from both animal and human studies that exercise training doses lead to variable responses. A genetic component contributes to exercise training response variability. In this consensus statement, we (1) briefly review the literature on exercise response variability and the various sources of variations in CRF response to an exercise programme, (2) introduce the key research designs and corresponding statistical models with an emphasis on randomised controlled designs with or without multiple pretests and post-tests, crossover designs and repeated measures designs, (3) discuss advantages and disadvantages of multiple methods of categorising exercise response levels-a topic that is of particular interest for personalised exercise medicine and (4) outline approaches that may identify determinants and modifiers of CRF exercise response. We also summarise gaps in knowledge and recommend future research to better understand exercise response variability531811411153The consensus meeting that led to the writing of this manuscript was held with the financial support of the Pennington Biomedical Research Foundation, the Pennington Biomedical Research Center Division of Education, the LSU Boyd Professorship and the John W. Barton, Sr. Chair in Genetics and Nutrition. No funding and/or honorarium was provided to any member of the writing group for the production of this manuscrip

    Risk stratification for arrhythmic death in an emergency department cohort: a new method of nonlinear PD2i analysis of the ECG

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    Heart rate variability (HRV) reflects both cardiac autonomic function and risk of sudden arrhythmic death (AD). Indices of HRV based on linear stochastic models are independent risk factors for AD in postmyocardial infarction (MI) cohorts. Indices based on nonlinear deterministic models have a higher sensitivity and specificity for predicting AD in retrospective data. A new nonlinear deterministic model, the automated Point Correlation Dimension (PD2i), was prospectively evaluated for prediction of AD. Patients were enrolled (N = 918) in 6 emergency departments (EDs) upon presentation with chest pain and being determined to be at risk of acute MI (AMI) >7%. Brief digital ECGs (>1000 heartbeats, āˆ¼15 min) were recorded and automated PD2i results obtained. Out-of-hospital AD was determined by modified Hinkle-Thaler criteria. All-cause mortality at 1 year was 6.2%, with 3.5% being ADs. Of the AD fatalities, 34% were without previous history of MI or diagnosis of AMI. The PD2i prediction of AD had sensitivity = 96%, specificity = 85%, negative predictive value = 99%, and relative risk >24.2 (p ā‰¤ 0.001). HRV analysis by the time-dependent nonlinear PD2i algorithm can accurately predict risk of AD in an ED cohort and may have both life-saving and resource-saving implications for individual risk assessment

    Lower pneumonia risk in COPD patients initiating fixed dose combination (FDC) inhaler comprising extrafine beclometasone dipropionate versus fluticasone

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    Grant support: This study was funded by Chiesi Farmaceutici S.p.A. David Price has grants and unrestricted funding for investigator-initiated studies (conducted through Observational and Pragmatic Research Institute Pte Ltd) from AstraZeneca, Boehringer Ingelheim, Chiesi, Mylan, Novartis, Regeneron Pharmaceuticals, Respiratory Effectiveness Group, Sanofi Genzyme, Theravance and UK National Health Service; is a peer reviewer for grant committees of the UK Efficacy and Mechanism Evaluation programme, and Health Technology Assessment; and was an expert witness for GlaxoSmithKline.Peer reviewe

    The workā€“recovery cycle of kidney strain and inflammation in sugarcane workers following repeat heat exposure at work and at home

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    PurposeTo examine heat exposure at work and home and the workā€“recovery cycle and temporal variation of kidney strain, muscle injury and inflammation biomarkers in sugarcane workers.Methods20 male sugarcane workers (age: 33ā€‰Ā±ā€‰7 years) with a workplace Rest.Shade.Hydration (RSH) intervention were observed over 4 days, at the end (18 h post-shift recovery) and beginning of a work week (42 h post-shift recovery). Measures included work intensity (heart rate), gastro-intestinal temperature, estimated body core temperature (using heart rate), fluid consumption, pre- and post-work blood and urine samples, physical activity (accelerometery) away from work, plus ambient heat exposure at work and home.ResultsOn workdays, workers awakened at approx. 02:40 after 5 h sleep inā€‰~ā€‰30 Ā°C. Across work shifts, daily average WBGT ranged from 26 to 29 Ā°C (cooler than normal) and average workload intensity ranged from 55 to 58%HRmax. Workers reported consumingā€‰~ā€‰8 L of water and ~ā€‰4ā€‰Ć—ā€‰300 mL bags of electrolyte fluid each day. Serum creatinine, cystatin C and creatine phosphokinase markedly increased post-work and decreased during recovery; serum potassium did the opposite (all pā€‰&lt;ā€‰0.01). Biomarker concentration changes were similar between recovery periods (18 h vs. 42 h; all pā€‰&gt;ā€‰0.27). C-reactive protein was the highest at the end of the work week (pā€‰=ā€‰0.01).ConclusionDespite RSH intervention, cross-shift kidney strain was marked (recovering overnight) and systemic inflammation increased over the work week. Thus, biomonitoring of kidney function in occupational populations should be performed before a work shift at any point in the work week. This is essential knowledge for field studies and surveillance.<br/

    Non-culprit MACE-rate in LRP:The influence of optimal medical therapy using DAPT and statins

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    Background/Purpose: The Lipid Rich Plaque (LRP) study demonstrated the association between coronary plaque lipid content and outcomes. In this LRP substudy, we assessed the impact of optimal medical therapy (OMT) on the occurrence of non-culprit major adverse cardiac events (NC-MACE). Advanced intracoronary imaging modalities are able to identify patients with vulnerable coronary lesion morphology associated with future events. Methods/Materials: A total of 1270 patients who underwent cardiac catheterization for suspected coronary artery disease (CAD) with evaluable maxLCBI4mm in non-culprit vessels and known medical therapy after discharge were followed for 2 years. OMT was defined as the use of a statin and dual antiplatelet therapy (DAPT). Results: Among the 1270 patients included in this substudy, 1110 (87.7%) had PCI for an index event, and 1014 (80%) patients received OMT. Estimated cumulative incidence functions of NC-MACE did not differ significantly between patients treated with or without OMT (log-rank p-value = 0.876). In patients labeled high risk (maxLCBI4mm > 400), cumulative incidence function also did not differ between patients treated with vs without OMT (log-rank p-value = 0.19). Conclusions: In the current LRP analysis, we could not identify a beneficial effect of OMT in the reduction of NC-MACE rate, even in patients with high-risk plaques during 24-month follow-up
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