Causal probabilistic model for evaluating future transoceanicairline separations

With the advent of automatic dependent surveillance (ADS), a detailed probability model of aircraft cross-track deviations is required to determine the impact of ADS. A suitable causal probability model is presented where normal navigation, degradation, pilot blunder, and failure are each modeled by Gaussian density functions with mean and standard deviations defined by the physics of the event. The overall model is a weighted sum of the Gaussian error probabilities and is thus amenable to extrapolation. Overlap and encroachment probabilities are derived,and the effect of ADS on this is model determined. It is shown that by using a simple form of ADS separation standards can be reduced, and transmitting a figure of merit (FOM) providing information on failures and degradations can further reduce separation standards. The results suggest an improvement by a factor of two from current separation standards     

Detecting gravitational waves from accreting neutron stars

The gravitational waves emitted by neutron stars carry unique information about their structure and composition. Direct detection of these gravitational waves, however, is a formidable technical challenge. In a recent study we quantified the hurdles facing searches for gravitational waves from the known accreting neutron stars, given the level of uncertainty that exists regarding spin and orbital parameters. In this paper we reflect on our conclusions, and issue an open challenge to the theoretical community to consider how searches should be designed to yield the most astrophysically interesting upper limits. With this in mind we examine some more optimistic emission scenarios involving spin-down, and show that there are technically feasible searches, particularly for the accreting millisecond pulsars, that might place meaningful constraints on torque mechanisms. We finish with a brief discussion of prospects for indirect detection.     

Cultures of human liver cells in simulated microgravity environment.

We used microgravity-simulated bioreactors that create the unique environment of low shear force and high-mass transfer to establish long-term cultures of primary human liver cells (HLC). To assess the feasibility of establishing HLC cultures, human liver cells obtained either from cells dissociated by collagenase perfusion or minced tissues were cultured in rotating vessels. Formation of multidimensional tissue-like spheroids (up to 1.0 cm) comprised of hepatocytes and biliary epithelial cells that arranged as bile duct-like structures along newly formed vascular sprouts were observed. Electron microscopy revealed clusters of round hepatocytes and bile canaliculi with multiple microvilli and tight junctions. Scanning EM revealed rounded hepatocytes that were organized in tight clusters surrounded by a complex mesh of extracellular matrix. Also, we observed that co-culture of hepatocytes with endothelial cells stimulate albumin mRNA expression. In summary, a simulated microgravity environment is conducive for the establishment of long-term HLC cultures and allows the dissection of the mechanism of liver regeneration and cell-to-cell interactions that resembles in vivo conditions.     

The Emirates Mars Mission (EMM) Emirates Mars InfraRed Spectrometer (EMIRS) Instrument

Space Science Reviews - Modern observatories have revealed the ubiquitous presence of magnetohydrodynamic waves in the solar corona. The propagating waves (in contrast to the standing waves) are...     

Auto Reconfiguration of Reaction Wheels in IRS

The Indian remote sensing satellite (IRS) employs four reaction wheels for attitude control. The fourth, a skew wheel, provides redundancy to the failure of any of the orthogonal wheels. To avoid attitude loss before the redundant skew wheel takes over due to failure of any of the orthogonal wheels, an automatic reconfiguration scheme has been developed and implemented through a microprocessor. The details of reconfiguration logic and the computer simulation results are presented.