32 research outputs found
Rocket instrumentation for the measurement of D-region electron density and collision frequencies Scientific report no. 244
Black Brant II sounding rocket instrumentation for measurement of D layer electron density and collision rat
Potential use of radar differential reflectivity measurements at orthogonal polarizations for measuring precipitation
Includes bibliographical references (pages 75-76).The potential use of differential reflectivity measurements at orthogonal polarizations to determine rainfall rate is examined. The method involves measurements of ZH and ZV, the radar reflectivity factors due to horizontally and vertically polarized incident waves respectively. The differential reflectivity, ZDR= 10 log (ZH/ZV), which should be precisely determinate, occurs as a result of the distortion of raindrops as they fall at terminal velocity. The approximate theory of Gans for electromagnetic scattering by spheroids is applied to the distorted raindrops. Assuming a general exponential form for the raindrop size distribution, equation sare derived relating the distribution parameters to the measurements. The determination of rainfall rate follows directly. Finally, the sensitivity of the distribution parameters to radar inaccuracies is examined, and several methods of implementing the measurements are suggested. It is concluded that good estimates of rainfall rate using a single non-attenuating wavelength radar are possible under ideal conditions
Invariant imbedding theory of mode conversion in inhomogeneous plasmas. II. Mode conversion in cold, magnetized plasmas with perpendicular inhomogeneity
A new version of the invariant imbedding theory for the propagation of
coupled waves in inhomogeneous media is applied to the mode conversion of high
frequency electromagnetic waves into electrostatic modes in cold, magnetized
and stratified plasmas. The cases where the external magnetic field is applied
perpendicularly to the direction of inhomogeneity and the electron density
profile is linear are considered. Extensive and numerically exact results for
the mode conversion coefficients, the reflectances and the wave electric and
magnetic field profiles inside the inhomogeneous plasma are obtained. The
dependences of mode conversion phenomena on the magnitude of the external
magnetic field, the incident angle and the wave frequency are explored in
detail.Comment: 11 figures, to be published in Physics of Plasma
Less is more: Antibiotics at the beginning of life
Antibiotic exposure at the beginning of life can lead to increased antimicrobial resistance and perturbations of the developing microbiome. Early-life microbiome disruption increases the risks of developing chronic diseases later in life. Fear of missing evolving neonatal sepsis is the key driver for antibiotic overtreatment early in life. Bias (a systemic deviation towards overtreatment) and noise (a random scatter) affect the decision-making process. In this perspective, we advocate for a factual approach quantifying the burden of treatment in relation to the burden of disease balancing antimicrobial stewardship and effective sepsis management