4,670 research outputs found

    One Thousand Ceasarean Sections in the Modern Era of Obstetrics

    Get PDF

    Biomarkers of Acute Myocardial Infarction in the Elderly: Troponin and Beyond

    Get PDF
    In the broadest context, biological markers, or biomarkers, are molecules that characterize a biological system or process. In the setting of cardiovascular disease, a number of biomarkers have become an integral part of diagnostic and risk stratification strategies. In this review, we will discuss classic and emerging biomarkers of cardiovascular disease and the role of these biomarkers in the diagnosis and prognosis of elderly patients presenting with acute myocardial infarction

    Determination of the Stability and Control Characteristics of a Tailless All-Wing Airplane Model with Sweepback in the Langley Free-Flight Tunnel

    Get PDF
    Force and flight tests were performance on an all-wing model with windmilling propellers. Tests were conducted with deflected and retracted flaps, with and without auxiliary vertical tail surfaces, and with different centers of gravity and trim coefficients. Results indicate serious reduction of stick-fixed longitudinal stability because of wing-tip stalling at high lift coefficient. Directional stability without vertical tail is undesirably low. Low effective dihedral should be maintained. Elevator and rudder control system is satisfactory

    The Effect of Mass Distribution on the Lateral Stability and Control Characteristics of an Airplane as Determined by Tests of a Model in the Free-Flight Tunnel

    Get PDF
    The effects of mass distribution on lateral stability and control characteristics of an airplane have been determined by flight tests of a model in the NACA free-flight tunnel. In the investigation, the rolling and yawing movements of inertia were increased from normal values to values up to five times normal. For each moment-of-inertia condition, combinations of dihedral and vertical-tail area representing a variety of airplane configurations were tested. The results of the flight tests of the model were correlated with calculated stability and control characteristics and, in general, good agreement was obtained. The tests showed the following effects of increased rolling and yawing moments of inertia: no appreciable change in spiral stability; reductions in oscillatory stability that were serious at high values of dihedral; a reduction in the sensitivity of the model to gust disturbances; and a reduction in rolling acceleration provided by the ailerons, which caused a marked increase in time to reach a given angle of bank. The general flight behavior of the model became worse with increasing moments of inertia but, with combinations of small effective dihedral and large vertical-tail area, satisfactory flight characteristics were obtained at all moment-of-inertia conditions

    Genetic recombination and complementation between bacteriophage T7 and cloned fragments of T7 DNA

    Get PDF
    Fragments of phage T7 DNA have been cloned in Escherichia coli by using the plasmid pMB9. Such cloned fragments are able to recombine with infecting phages, thus providing a means to integrate the physical and genetic maps of T7 DNA. Approximately 65% of the T7 DNA molecule has been found in clones so far, and analysis of these clones has mapped genes 12-17 with an accuracy of about 1% the total length of T7 DNA. At least some cloned segments can supply T7 functions to infecting phages

    The Effect of Mass Distribution on the Lateral Stability and Control Characteristics of an Airplane as Determined by Tests of a Model in the Free-flight Tunnel

    Get PDF
    The effects of mass distribution on lateral stability and control characteristics of an airplane have been determined by flight tests of a model in the NACA free-flight tunnel. In the investigation, the rolling and yawing moments of inertia were increased from normal values to values up to five times normal. For each moment-of-inertia condition, combinations of dihedral and vertical-tail area representing a variety of airplane configurations were tested. The results of the flight tests of the model were correlated with calculated stability and control characteristics and, in general, good agreement was obtained

    Are Consumers Willing to Pay More for Biodegradable Containers Than for Plastic Ones? Evidence from Hypothetical Conjoint Analysis and Nonhypothetical Experimental Auctions

    Get PDF
    This study used and compared hypothetical conjoint analysis and nonhypothetical experimental auctions to elicit floral customers’ willingness to pay for biodegradable plant containers. The results of the study show that participants were willing to pay a price premium for biodegradable containers, but the premium is not the same for different types of containers. This article also shows the mixed ordered probit model generates more accurate results when analyzing the conjoint analysis Internet survey data than the ordered probit model.biodegradable, willingness to pay, marketing, carbon footprint, waste composition, green industry, nursery crops, floriculture crops, Agribusiness, Agricultural and Food Policy, Environmental Economics and Policy, Financial Economics, Food Consumption/Nutrition/Food Safety, Marketing, Public Economics, Research and Development/Tech Change/Emerging Technologies, D12, Q13,

    Modeling potential hydrochemical responses to climate change and increasing CO2 at the Hubbard Brook Experimental Forest using a dynamic biogeochemical model (PnET-BGC)

    Get PDF
    Dynamic hydrochemical models are useful tools for understanding and predicting the interactive effects of climate change, atmospheric CO2, and atmospheric deposition on the hydrology and water quality of forested watersheds. We used the biogeochemical model, PnET-BGC, to evaluate the effects of potential future changes in temperature, precipitation, solar radiation, and atmospheric CO2 on pools, concentrations, and fluxes of major elements at the Hubbard Brook Experimental Forest in New Hampshire, United States. Future climate projections used to run PnET-BGC were generated specifically for the Hubbard Brook Experimental Forest with a statistical technique that downscales climate output (e.g., air temperature, precipitation, solar radiation) from atmosphere-ocean general circulation models (AOGCMs) to a finer temporal and spatial resolution. These climate projections indicate that over the twenty-first century, average air temperature will increase at the site by 1.7 degrees C to 6.5 degrees C with simultaneous increases in annual average precipitation ranging from 4 to 32 cm above the long-term mean (1970–2000). PnET-BGC simulations under future climate change show a shift in hydrology characterized by later snowpack development, earlier spring discharge (snowmelt), greater evapotranspiration, and a slight increase in annual water yield (associated with CO2 effects on vegetation). Model results indicate that under elevated temperature, net soil nitrogen mineralization and nitrification markedly increase, resulting in acidification of soil and stream water, thereby altering the quality of water draining from forested watersheds. Invoking a CO2 fertilization effect on vegetation under climate change substantially mitigates watershed nitrogen loss, highlighting the need for a more thorough understanding of CO2 effects on forest vegetation

    Graphene formation on SiC substrates

    Full text link
    Graphene layers were created on both C and Si faces of semi-insulating, on-axis, 4H- and 6H-SiC substrates. The process was performed under high vacuum (<10-4 mbar) in a commercial chemical vapor deposition SiC reactor. A method for H2 etching the on-axis sub-strates was developed to produce surface steps with heights of 0.5 nm on the Si-face and 1.0 to 1.5 nm on the C-face for each polytype. A process was developed to form graphene on the substrates immediately after H2 etching and Raman spectroscopy of these samples confirmed the formation of graphene. The morphology of the graphene is described. For both faces, the underlying substrate morphology was significantly modified during graphene formation; sur-face steps were up to 15 nm high and the uniform step morphology was sometimes lost. Mo-bilities and sheet carrier concentrations derived from Hall Effect measurements on large area (16 mm square) and small area (2 and 10 um square) samples are presented and shown to compare favorably to recent reports.Comment: European Conference on Silicon Carbide and Related Materials 2008 (ECSCRM '08), 4 pages, 4 figure
    • …
    corecore