6,950 research outputs found
Variance Control in Weak Value Measurement Pointers
The variance of an arbitrary pointer observable is considered for the general
case that a complex weak value is measured using a complex valued pointer
state. For the typical cases where the pointer observable is either its
position or momentum, the associated expressions for the pointer's variance
after the measurement contain a term proportional to the product of the weak
value's imaginary part with the rate of change of the third central moment of
position relative to the initial pointer state just prior to the time of the
measurement interaction when position is the observable - or with the initial
pointer state's third central moment of momentum when momentum is the
observable. These terms provide a means for controlling pointer position and
momentum variance and identify control conditions which - when satisfied - can
yield variances that are smaller after the measurement than they were before
the measurement. Measurement sensitivities which are useful for estimating weak
value measurement accuracies are also briefly discussed.Comment: submitted to Phys Rev
Polar orbit electrostatic charging of objects in shuttle wake
A survey of DMSP data has uncovered several cases where precipitating auroral electron fluxes are both sufficiently intense and energetic to charge spacecraft materials such as teflon to very large potentials in the absence of ambient ion currents. Analytical bounds are provided which show that these measured environments can cause surface potentials in excess of several hundred volts to develop on objects in the orbiter wake for particular vehicle orientations
Optical constants of uranium plasma Final report
Thermodynamic and optical properties of uranium plasma in proposed gaseous core nuclear rocket
Holographic Superconductors with Ho\v{r}ava-Lifshitz Black Holes
We discuss the phase transition of planar black holes in Ho\v{r}ava-Lifshitz
gravity by introducing a Maxwell field and a complex scalar field. We calculate
the condensates of the charged operators in the dual CFTs when the mass square
of the complex scalar filed is and , respectively. We
compute the electrical conductivity of the \hl superconductor in the probe
approximation. In particular, it is found that there exists a spike in the
conductivity for the case of the operator with scaling dimension one. These
results are quite similar to those in the case of Schwarzschild-AdS black
holes, which demonstrates that the holographic superconductivity is a robust
phenomenon associated with asymptotic AdS black holes.Comment: 12 pages, 7 figures,refs adde
Additional application of the NASCAP code. Volume 1: NASCAP extension
The NASCAP computer program comprehensively analyzes problems of spacecraft charging. Using a fully three dimensional approach, it can accurately predict spacecraft potentials under a variety of conditions. Several changes were made to NASCAP, and a new code, NASCAP/LEO, was developed. In addition, detailed studies of several spacecraft-environmental interactions and of the SCATHA spacecraft were performed. The NASCAP/LEO program handles situations of relatively short Debye length encountered by large space structures or by any satellite in low earth orbit (LEO)
Analysis of the charging of the SCATHA (P78-2) satellite
The charging of a large object in polar Earth orbit was investigated in order to obtain a preliminary indication of the response of the shuttle orbiter to such an environment. Two NASCAP (NASA Charging Analyzer Program) models of SCATHA (Satellite Charging at High Altitudes) were used in simulations of charging events. The properties of the satellite's constituent materials were compiled and representations of the experimentally observed plasma spectra were constructed. Actual charging events, as well as those using test environments, were simulated. Numerical models for the simulation of particle emitters and detectors were used to analyze the operation of these devices onboard SCATHA. The effect of highly charged surface regions on the charging conductivity within a photosheath was used to interpret results from the onboard electric field experiment. Shadowing calculations were carried out for the satellite and a table of effective illuminated areas was compiled
Space, Place, and COVID-19: Introduction to the Special Issue
The COVID-19 pandemic alerted the U.S. populace to spatial patterns of health outcomes. Trusted sources of information such as the Johns Hopkins University and The New York Times mapped COVID-19 indicators at the county-level, bringing widespread attention to the timing and clustering of case rates, mortality, and vaccine uptake. The severity of the pandemic has motivated the research community to share data and conduct analyses to illuminate and project trends that would be useful for healthcare providers and policy makers in their communities. This special issue of the Journal of Rural Social Sciences explores the roles space and place have on COVID-19 outcomes and experiences. The contributing authors consider the importance of context, individual-level factors within those environments, and what mitigation efforts might be most useful in improving health outcomes
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