Stress history of the Tharsis Region, Mars

The Tharsis topographic rise of Mars is roughly 5000 km wide and 10 km high and is believed to have originated more than 3.5 BY ago. Within its boundaries lie the four largest volcanoes on the planet. It is also the locus of a series of fracture traces which extend over approximately a hemisphere. The events leading to the formation of the Tharsis region continue to generate debate. Three geophysical models of the formation of Tharsis are now in general contention and each of these models has been used to predict a characteristic stress-field. These models are: the volcanic construct model, the isostatic compensation model, and the lithospheric uplift model. Each has been used by its proponents to predict some of the features observed in the Tharsis region but none accurately accounts for all of the fracture features observed. This is due, in part, to the use of fractures too young to be directly related to the origin of Tharsis. To constrain the origin of Tharsis, as opposed to its later history, one should look for the oldest fractures related to Tharsis and compare these to the predictions made by the models. Mapping of old terrains in and around the Tharsis rise has revealed 175 hitherto unknown old fracture features

Exploring the limits of multiplexed photon-pair sources for the preparation of pure single-photon states

Current sources of heralded single photons based on nonlinear optics operate in a probabilistic manner. In order to build quantum-enhanced devices based around the use of single photons, compact, turn-key and deterministic sources are required. A possible solution is to multiplex a number of sources to increase the single-photon generation probability and in so doing reducing the waiting time to deliver large numbers of photons simultaneously, from independent sources. Previously it has been shown that, in the ideal case, 17 multiplexed sources allow deterministic generation of heralded single photons [Christ and Silberhorn, Phys. Rev. A 85, 023829 (2012)]. Here we extend this analysis to include undesirable effects of detector inefficiency and photon loss on a number of multiplexed sources using a variety of different detectors for heralding. We compare these systems for fixed signal-to-noise ratio to allow a direct comparison of performance for real- world heralded single photon sources.Comment: 10 pages, 7 figures. Equation 18 changed to include power of a half in the binomial facto

Temporal Loop Multiplexing: A resource efficient scheme for multiplexed photon-pair sources

Single photons are a vital resource for photonic quantum information processing. However, even state-of-the-art single photon sources based on photon-pair generation and heralding detection have only a low probability of delivering a single photon when one is requested. We analyse a scheme that uses a switched fibre delay loop to increase the delivery probability per time bin of single photons from heralded sources. We show that, for realistic experimental parameters, combining the output of up to 15 pulses can yield a performance improvement of a factor of 10. We consider the future performance of this scheme with likely component improvements.Comment: 5 pages, 4 figure

Issues and opportunities in space photovoltaics

Space power sources are becoming a central focus for determining man's potential and schedule for exploring and utilizing the benefits of space. The ability to search, probe, survey, and communicate throughout the universe will depend on providing adequate power to the instruments to do these jobs. Power requirements for space platforms are increasing and will continue to increase into the 21st century. Photovoltaics have been a dependable power source for space for the last 30 years and have served as the primary source of power on virtually all DOD and NASA satellites. The performance of silicon (Si) solar cells has increased from 10 percent air mass zero (AM0) solar energy conversion efficiency in the early 60's to almost 15 percent on today's spacecraft. Some technologists even think that the potential for solar photovoltaics has reached a plateau. However, present and near-future Air Force and NASA requirements show needs that, if the problems are looked upon as opportunities, can elevate the photovoltaic power source scientist and array structure engineer into the next technological photovoltaic growth curve

Numerical analysis and simulation of an assured crew return vehicle flow field

A lifting body was proposed as a candidate for the Assured Crew Return Vehicle (ACRV) which will serve as a crew rescue vehicle for the Space Station Freedom. The focus is on body surface definition, both surface and volume grid definition, and the computation of inviscid flow fields about the vehicle at wind tunnel conditions. Very good agreement is shown between the computed aerodynamic characteristics of the vehicle at M(sub infinity) = 10 and those measured in wind tunnel tests at high Reynolds numbers

Experimental Neurosurgery

In July 1973, a three-judge Circuit Corut for Wayne County Mich., ruled that experimental psychosurgery could not be performed on any person involuntarily detained in state mental institutions, even if consent were given to the experiment (Kaimowitz v. Department of Mental Health (1973)). This was the first court case to consider the propriety of psychosurgery. It received considerable national attention and is a striking precedent regarding both psychosurgery and, more generally, medical experimentation with captive populations. The litigation was filed after one subject had been selected by experimenters at the Layfayette Clinic in Detroit, a unit of the State Department of Mental Health affiliated with the Wayne State Universtiy Medical School. Because it was a taxpayer\u27s suit challenging the expenditure of state funds, and had not been filed at the direction of the experimental subject, the Court determined that the subject needed his own counsel and appointed Profs. Robert A. Burt and Francis A. Allen of the University of Michigan Law School as principal counsel and co-counsel respectively. Prof. Andrew S. Watson of the Law School and the U-M Department of Psychiatry examined the subject and testified at the trial. The following is a part of the brief submitted by Burt and Allen, arguing that state-compelled psychosurgery would be cruel and unusual punishmentunder the Eighth Amendment and that state compulsion would inevitably taint any apparent consent for psychosurgery of involuntarily detained mental patients. The Court agreed with the result sought by this brief, though its opinion rested on First Amendment grounds related to the thought control implications of psychosurgery

Specific Rab GTPase-activating proteins define the Shiga toxin and epidermal growth factor uptake pathways

Rab family guanosine triphosphatases (GTPases) together with their regulators define specific pathways of membrane traffic within eukaryotic cells. In this study, we have investigated which Rab GTPase-activating proteins (GAPs) can interfere with the trafficking of Shiga toxin from the cell surface to the Golgi apparatus and studied transport of the epidermal growth factor (EGF) from the cell surface to endosomes. This screen identifies 6 (EVI5, RN-tre/USP6NL, TBC1D10A–C, and TBC1D17) of 39 predicted human Rab GAPs as specific regulators of Shiga toxin but not EGF uptake. We show that Rab43 is the target of RN-tre and is required for Shiga toxin uptake. In contrast, RabGAP-5, a Rab5 GAP, was unique among the GAPs tested and reduced the uptake of EGF but not Shiga toxin. These results suggest that Shiga toxin trafficking to the Golgi is a multistep process controlled by several Rab GAPs and their target Rabs and that this process is discrete from ligand-induced EGF receptor trafficking