Projection volumes of hyperplane arrangements

We prove that for any finite real hyperplane arrangement the average projection volumes of the maximal cones is given by the coefficients of the characteristic polynomial of the arrangement. This settles the conjecture of Drton and Klivans that this held for all finite real reflection arrangements. The methods used are geometric and combinatorial. As a consequence we determine that the angle sums of a zonotope are given by the characteristic polynomial of the order dual of the intersection lattice of the arrangement

Micro-fluid exchange coupling apparatus

In a macro-fluid exchange, a hollow needle, such as a syringe needle, is provided for penetrating the fluid conduit of the animal. The syringe needle is coupled to a plenum chamber having an inlet and outlet port. The plenum chamber is coupled to the syringe needle via the intermediary of a standard quick disconnect coupling fitting. The plenum chamber is carried at the end of a drive rod which is coupled to a micrometer drive head. The micrometer drive head is slidably and pivotably coupled to a pedestal for adjusting the height and angle of inclination of the needle relative to a reference base support. The needle is positioned adjacent to the incised trachea or a blood vessel of a small animal and the micrometer drive head is operated for penetrating the fluid conduit of the animal

Heteroepitaxial InP solar cells on Si and GaAs substrates

The characteristics of InP cells processed from thin layers of InP heteroepitaxially grown on GaAs, on silicon with an intervening GaAs layer, and on GaAs with intervening Ga(x)In(1-x)As layers are described, and the factors affecting cell efficiency are discussed. Under 10 MeV proton irradiations, the radiation resistances of the heteroepitaxial cells were superior to that of homoepitaxial InP cells. The superior radiation resistance is attributed to the high dislocation densities present in the heteroepitaxial cells

New directions in InP solar cell research

Recent research efforts representing new directions in InP solar cell research are reviewed. These include heteroepitaxial growth on silicon and gallium arsenide substrates, V-grooved cells, large area high efficiency cells, and surface passivation. Improvements in heteroepitaxial cell efficiency are described together with processing of 19.1 percent, 4 sq cm cells. Recommendations are made for improvements in processing leading to increased efficiencies

Defect behavior, carrier removal and predicted in-space injection annealing of InP solar cells

Defect behavior, observed by deep level transient spectroscopy (DLTS), is used to predict carrier removal and the effects of simultaneous electron irradiation and injection annealing of the performance of InP solar cells. For carrier removal, the number of holes trapped per defect is obtained from measurements of both carrier concentrations and defect concentrations during an isochronal anneal. In addition, from kinetic considerations, the behavior of the dominant defect during injection annealing is used to estimate the degradation expected from exposure to the ambient electron environment in geostationary orbit

Building Healthy Places with People and for People: Community Engagement for Healthy and Sustainable Communities

Over a 25 year period, residents of the El Sereno  community in Los Angeles have opposed efforts of  investors seeking to build luxury homes on the area  known as Elephant Hill.  After years of community  organizing—canvassing door to door, developing a  broad-based coalition and mobilizing supporters to  attend public hearings—residents declared victory after  the City Council agreed to settle a lawsuit with the  developers by buying the 20-acre site for $6 million to  create a future park.  Residents are glad that a chunk of one of Los Angeles' last undeveloped hillsides  will remain open space in this park poor, working-class Latino community.  Opposition efforts reignited  in 2004 not only to preserve open space, but also to encourage public safety and counter threats to  gentrification.  Elva Yañez, the El Sereno resident who led the most recent efforts to preserve Elephant  Hill, hailed the settlement as a victory for environmental justice: "After a long and hard fought struggle,  the residents of this community have been afforded the environmental protections that are rightfully theirs.   We are pleased that this poorly planned project is not moving forward and environmental justice has  prevailed." [Contreras & Sanchez, 2009; Yañez, personal communication, 2010