Environmental interactions of the Space Station Freedom electric power system

The Space Station Freedom operates in a low earth orbit (LEO) environment. Such operation results in different potential interactions with the Space Station systems including the Electric Power System (EPS). These potential interactions result in environmental effects which include neutral species effects such as atomic oxygen erosion, effects of micrometeoroid and orbital debris impacts, plasma effects, ionizing radiation, and induced contamination degradation effects. The EPS design and its interactions with the LEO environment are briefly described and the results of analyses and testing programs planned and performed thus far to resolve environmental concerns related to the EPS and its function in LEO environment

An Economic Analysis of Adult Obesity: Results from the Behavioral Risk Factor Surveillance System

Since the late 1970s, the number of obese adults in the United States has grown by over 50 percent. This paper examines the factors that may be responsible for this rapidly increasing prevalence rate. To study the determinants of adult obesity and related outcomes, we employ micro-level data from the 1984-1999 Behavioral Risk Factor Surveillance System. These repeated cross sections are augmented with state level measures pertaining to the per capita number of fast- food restaurants, the per capita number of full-service restaurants, the price of a meal in each type of restaurant, the price of food consumed at home, the price of cigarettes, clean indoor air laws, and hours of work per week and hourly wage rates by age, gender, race, years of formal schooling completed, and marital status. Our main results are that these variables have the expected effects on obesity and explain a substantial amount of its trend. These findings control for individual-level measures of household income, years of formal schooling completed, and marital status.

Assessing replicated coral trace element (Sr/Ca and Mg/Ca) variability and skeletal growth records from the tropical Pacific

To gain a more complete history and understanding of the full amplitude of climate variability prior to instrumental records, science must rely on natural proxy archives that are sensitive to fluctuations in key climate parameters. Calcium carbonate skeletons of long-living hermatypic corals in some locations have been shown to be natural archives of surface ocean variability. This study investigated the fidelity and reproducibility of coral derived Sr/Ca time series from Clipperton Atoll, Fiji, and Tonga as accurate proxies of sea surface temperature (SST). The replicated high-resolution Sr/Ca time series record monthly and bimonthly SST changes, though with a greater magnitude of variability than instrumental records. Coupled measurements of coral Sr/Ca and δ18O records were also used to reconstruct δ 18O of seawater from each region, and showed good agreement with in situ sea surface salinity (SSS) measurements. Longer-term, lower-frequency trends in the proxy records appear to reflect the changing position of the Intertropical Convergence Zone (ITCZ) and the South Pacific Convergence Zone (SPCZ). Coral skeletal growth parameters were then examined for possible effects of ocean acidification. These results showed some coral colonies with increasing calcification while others showed decreasing calcification, suggesting other effects play an important role. The results of the analyses of growth and paleoclimatology proxy reconstructions were also inconclusive, since slight influences were present in some but not all colonies. Finally, inter- and intra-colony comparisons were made using Mg/Ca as the proxy results in the Fiji and Tonga colonies. However, because of alterations and discontinuities in the skeletal material, Mg/Ca lacked coherence at long timescales and should not be considered as a reliable SST proxy

Singular value decomposition on SIMD hypercube and shuffle-exchange computers

AbstractThis paper reports several parallel singular value decomposition (SVD) algorithms on the hypercube and shuffle-exchange SIMD computers. Unlike previously published hypercube SVD algorithms which map a column pair of a matrix onto a processor, the algorithms presented in this paper map a matrix column pair onto a column of processors. In this way, a further reduction in time complexity is achieved. The paper also introduces the concept of two-dimensional shuffle-exchange networks, and corresponding SVD algorithms for one-dimensional and two-dimensional shuffle-exchange computers are developed

Identification of a WNT5A-Responsive Degradation Domain in the Kinesin Superfamily Protein KIF26B.

Noncanonical WNT pathways function independently of the β-catenin transcriptional co-activator to regulate diverse morphogenetic and pathogenic processes. Recent studies showed that noncanonical WNTs, such as WNT5A, can signal the degradation of several downstream effectors, thereby modulating these effectors' cellular activities. The protein domain(s) that mediates the WNT5A-dependent degradation response, however, has not been identified. By coupling protein mutagenesis experiments with a flow cytometry-based degradation reporter assay, we have defined a protein domain in the kinesin superfamily protein KIF26B that is essential for WNT5A-dependent degradation. We found that a human disease-causing KIF26B mutation located at a conserved amino acid within this domain compromises the ability of WNT5A to induce KIF26B degradation. Using pharmacological perturbation, we further uncovered a role of glycogen synthase kinase 3 (GSK3) in WNT5A regulation of KIF26B degradation. Lastly, based on the identification of the WNT5A-responsive domain, we developed a new reporter system that allows for efficient profiling of WNT5A-KIF26B signaling activity in both somatic and stem cells. In conclusion, our study identifies a new protein domain that mediates WNT5A-dependent degradation of KIF26B and provides a new tool for functional characterization of noncanonical WNT5A signaling in cells