98,314 research outputs found
Demographic and Socio-economic Determinants of Birth Interval Dynamics in Manipur: A Survival Analysis
The birth interval is a major determinant of levels of fertility in high fertility populations. A house-to-house survey of 1225 women in Manipur, a tiny state in North Eastern India was carried out to investigate birth interval patterns and its determinants. Using survival analysis, among the nine explanatory variables of interest, only three factors – infant mortality, Lactation and use of contraceptive devices have highly significant effect (P<0.01) on the duration of birth interval and only three factors – age at marriage of wife, parity and sex of child are found to be significant (P<0.05) on the duration variable
Effects of the Scale-dependent Vacuum Expectation Values in the Renormalization Group Analysis of Neutrino Masses
The contribution of scale-dependent vacuum expectation values (VEVs) of Higgs
scalars, which gives significant effects in the evolution of fundamental
fermion masses in the Minimal Supersymmetric Standard Model (MSSM), is now
considered in the derivation of the one-loop analytic expression for the
evolution of the left-handed Majorana neutrino masses with energies. The
inclusion of such effect of the running VEV increases the stability of the
neutrino masses under quantum corrections and leads to a mild decrease of
neutrino masses with higher energies.Comment: 11 Pages, 4 Figure
Arcing and discharges in high-voltage subsystems of Space Station
Arcing and other types of electrical discharges are likely to occur in high-voltage subsystems of the Space Station. Results from ground and space experiments on the arcing of solar cell arrays are briefly reviewed, showing that the arcing occurs when the conducting interconnects in the arrays are at negative potential above a threshold, which decreases with the increasing plasma density. Furthermore, above the threshold voltages the arcing rate increases with the plasma density. At the expected operating voltages (approximately 200 V) in the solar array for the space station, arcing is expected to occur even in the ambient ionospheric plasma. If the ionization of the contaminants increases the plasma density near the high-voltage systems, the adverse effects of arcing on the solar arrays and the space station are likely to be enhanced, In addition to arcing other discharge processes are likely to occur in high-voltage subsystems. For example, Paschen discharge is likely to occur when the neutral density N sub n greater that 10 to the 12th cu cm, the corresponding neutral pressure P greater than 3 x 10 to the -5 Torr
Dissipative electron-phonon system photoexcited far from equilibrium
We derive the steady-state electron distribution function for a semiconductor
driven far from equilibrium by the inter-band photoexcitation assumed
homogeneous over the nanoscale sample. Our analytical treatment is based on the
generalization of a stochastic model known for a driven dissipative granular
gas. The generalization is physically realizable in a semiconducting sample
where electrons are injected into the conduction band by photoexcitation, and
removed through the electron-hole recombination process at the bottom of the
conduction band. Here the kinetics of the electron-electron and the
electron-phonon (bath) scattering processes, as also the partitioning of the
total energy in the inelastic collisions, are duly parametrized by certain rate
constants. Our analytical results give the steady-state-energy distribution of
the classical (non-degenerate) electron gas as function of the phonon (bath)
temperature and the rates of injection (cw pump) and depletion (recombination).
Interestingly, we obtain an accumulation of the electrons at the bottom of the
conduction band in the form of a delta-function peak a non-equilibrium
classical analogue of condensation. Our model is specially appropriate to a
disordered, indirect band-gap, polar semiconducting sample where energy is the
only state label, and the electron-phonon coupling is strong while the
recombination rate is slow. A possible mechanism for the dissipative inelastic
collisions between the electrons is also suggested.Comment: 4 page
Active Optical Remote Sensing Sensors and Instrumentation for NASAs Future Earth and Space Science Measurements/Missions
AbstractActive optical (Laser/Lidar) measurement techniques are critical for the future National Aeronautics and Space Administration (NASA) Earth, Planetary Science, Exploration, and Aeronautics measurements. The latest science decadal surveys recommend a number of missions requiring active optical systems to meet the science measurement objectives and the aeronautics community continues to use Laser/Lidar technologies to meet the aeronautics measurement objectives. This presentation will provide an overview of NASA efforts in developing and maturing state-of-the-art advanced solid-state flight laser/lidar systems for airborne and space-borne remote sensing measurements. The presentation will also provide details of a strategic approach for active optical technologies and techniques to meet the NASAs future Earth and Space Science measurement ments for space-based applications
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