88,999 research outputs found

    A reference atmosphere for patrick afb, florida, annual /1963 revision/

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    Reference atmosphere for cape kennedy based on statistical parameters of pressure-height, temperature, and relative humidity at constant pressure level

    On the self-similarity in quantum Hall systems

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    The Hall-resistance curve of a two-dimensional electron system in the presence of a strong perpendicular magnetic field is an example of self-similarity. It reveals plateaus at low temperatures and has a fractal structure. We show that this fractal structure emerges naturally in the Hamiltonian formulation of composite fermions. After a set of transformations on the electronic model, we show that the model, which describes interacting composite fermions in a partially filled energy level, is self-similar. This mathematical property allows for the construction of a basis of higher generations of composite fermions. The collective-excitation dispersion of the recently observed 4/11 fractional-quantum-Hall state is discussed within the present formalism.Comment: 7 pages, 4 figures; version accepted for publication in Europhys. Lett., new version contains energy calculations for collective excitations of the 4/11 stat

    Earth satellite orbit computations. part ii- atmospheric effects final report

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    Atmospheric density effect on computation of earth satellite orbit

    Surface temperatures and temperature gradient features of the US Gulf Coast waters

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    Satellite thermal infrared data on the Gulf of Mexico show that a seasonal cycle exists in the horizontal surface temperature structure. In the fall, the surface temperatures of both coastal and deep waters are nearly uniform. With the onset of winter, atmospheric cold fronts, which are accompanied by dry, low temperature air and strong winds, draw heat from the sea. A band of cooler water forming on the inner shelf expands, until a thermal front develops seaward along the shelf break between the cold shelf waters and the warmer deep waters of the Gulf. Digital analysis of the satellite data was carried out in an interactive mode using a minicomputer and software. A time series of temperature profiles illustrates the temporal and spatial changes in the sea-surface temperature field

    Association between osteoarthritis and cardiovascular disease: systematic review and meta-analysis

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    Background: To examine for a possible relationship between osteoarthritis and cardiovascular disease (CVD). Design: A systematic review and meta-analysis Methods: Published and unpublished literature from: MEDLINE, EMBASE, CINAHL, the Cochrane Library, OpenGrey and clinical trial registers. Search to 22nd November 2014. Cohort, case-control, randomised and non-randomised controlled trial papers reporting the prevalence of CVD in osteoarthritis were included. Results: Fifteen studies with 32,278,744 individuals were eligible. Pooled prevalence for overall CVD pathology in people with osteoarthritis was 38.4% (95% Confidence interval (CI): 37.2% to 39.6%). Individuals with osteoarthritis were almost three times as likely to have heart failure (Relative Risk (RR): 2.80; 95% CI: 2.25 to 3.49) or ischaemic heart disease (RR: 1.78; 95% CI: 1.18 to 2.69) compared to matched non-osteoarthritis cohorts. No significant difference was detected between the two groups for the risk of experiencing myocardial infarction or stroke. There was a three-fold decrease in the risk of experiencing a transient ischaemic attack in the osteoarthritis cohort compared to the non-osteoarthritis group. Conclusions: Prevalence of CVD in patients with OA is significant. There was an observed increased risk of incident heart failure and ischaemic heart disease in people with OA compared to matched controls. However the relationship between OA and CVD is not straight-forward and there is a need to better understand the potential common pathways linking pathophysiological mechanisms

    The two-frequency, bistatic radar-occultation method for the study of planetary ionospheres scientific reports no. 1 and no. 7

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    Method for study of planetary ionospheres based on radio wave propagation between earth and spacecraf

    Wind models for the NSTS ascent trajectory biasing for wind load alleviation

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    New concepts are presented for aerospace vehicle ascent wind profile biasing. The purpose for wind biasing the ascent trajectory is to provide ascent wind loads relief and thus decrease the probability for launch delays due to wind loads exceeding critical limits. Wind biasing trajectories to the profile of monthly mean winds have been widely used for this purpose. The wind profile models presented give additional alternatives for wind biased trajectories. They are derived from the properties of the bivariate normal probability function using the available wind statistical parameters for the launch site. The analytical expressions are presented to permit generalizations. Specific examples are given to illustrate the procedures. The wind profile models can be used to establish the ascent trajectory steering commands to guide the vehicle through the first stage. For the National Space Transportation System (NSTS) program these steering commands are called I-loads

    Photosynthesis-irradiance responses in the Ross Sea, Antarctica: a meta-analysis

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    A meta-analysis of photosynthesis-irradiance measurements was completed using data from the Ross Sea, Antarctica, using a total of 417 independent measurements. P-m(B), the maximum, chlorophyll-specific, irradiancesaturated rate of photosynthesis, averaged 1.1 +/- 0.06 mu gC (mu g Chl)(-1) h(-1). Light-limited, chlorophyll-specific photosynthetic rates (alpha(B)) averaged 0.030 +/- 0.023 mu gC (mu g Chl)(-1) h(-1) (mu mol quanta m(-2) s(-1))(-1). Significant variations in P-m(B) and alpha(B) were found as a function of season, with spring maximum photosynthetic rates being 60% greater than those in summer. Similarly, alpha values were 48% greater in spring. There was no detectable effect of sampling location on the photosynthetic parameters, and temperature and macronutrient (NO3) concentrations also did not have an influence. However, irradiance and carbon dioxide concentrations, when altered under controlled conditions, exerted significant influences on photosynthetic parameters. Specifically, reduced irradiance resulted in significantly decreased P-m(B) and increased alpha(B) values, and increased CO2 concentrations resulted in significantly increased P-m(B) and alpha(B) values. Comparison of photosynthetic parameters derived at stations where iron concentrations were above and below 0.1nM indicated that reduced iron levels were associated with significantly increased P-m(B) values, confirming the importance of iron within the photosynthetic process. No significant difference was detected between stations dominated by diatoms and those dominated by the haptophyte Phaeocystis antarctica. The meta-analysis confirms the photosynthetic rates predicted from global analyses that are based solely on temperature and irradiance availability, but suggests that, for more accurate predictions of productivity in polar systems, a more detailed model that includes temporal effects of photosynthetic parameters will be required
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