Electric arc discharge damage to ion thruster grids

Arcs representative of those occurring between the grids of a mercury ion thruster were simulated. Parameters affecting an arc and the resulting damage were studied. The parameters investigated were arc energy, arc duration, and grid geometry. Arc attenuation techniques were also investigated. Potentially serious damage occurred at all energy levels representative of actual thruster operating conditions. Of the grids tested, the lowest open-area configuration sustained the least damage for given conditions. At a fixed energy level a long duration discharge caused greater damage than a short discharge. Attenuation of arc current using various impedances proved to be effective in reducing arc damage. Faults were also deliberately caused using chips of sputtered materials formed during the operation of an actual thruster. These faults were cleared with no serious grid damage resulting using the principles and methods developed in this study

Turbulent flow over a wavy boundary

CER71-72PSB-JEC44.Includes bibliographical references (pages 53-57).May 1972.An experimental study was made of turbulent flow over a wavy surface. Sinusoidal waves of three sizes were used to explore the variations of flow with wave size. Measurements of mean and turbulent velocities were taken with a two-wire method. Local heat transfer rates and pressures on the wavy surface were also measured. An equilibrium turbulent boundary layer, which conforms to Rotta's and Clauser's self-preservation requirements, develops in the region far downstream from the first wave. In the lower portion of this layer, the mean velocity is represented by the logarithmic velocity profile when the form-drag measurements of skin friction are used to determine the shift-in-origin. The roughness function is related to the wave height since the wavy surface is shown to be a "k" type surface. The velocity defect profile in the logarithmic form extends to higher values of yu*/ϐ*U∞ than those for smooth wall flows. Eddy viscosity results support the assumed logarithmic velocity variation in the lower part of the boundary layer. Measurements of shear stress by either the two-wire or the heated-film method disagree with the form drag measurements of skin friction. The wavy surface is an extended surface windbreak since it reduces the overall wind speed above the surface and creates vortices between the waves. However, surface shear stresses are increased, and the erosion rate of field waves is a function of wave height.U.S. Department of Interior, Office of Water Resources Research, Contract No. 14-01-0001, U.S. Department of Defense, Office of Naval Research, Contract No. N00014-68-A-0493-0001

Editorial Board

This nursery was organized in response to the need for improving adaptation and obtaining genetic information on the resistance or reaction to the different stress environments (biotic and abiotic) to which beans are subjected in production areas. Results are given for the best black- and red-seeded lines of the 1987 VIDAC, covering characteristics such as 100 seeds, days to flowering and physiological maturity, wt. of and response to diseases such as rust (Uromyces phaseoli), bacterioses (Xanthomonas phaseoli), BGMV, and web blight (Thanatephorus cucumeris). The yield potential and genetic adaptation of the best materials over different sites are also analyzed. Information on these national and regional trials should be collected in an efficient regional information and documentation center. (CIAT)Este vivero se organizo con base en la necesidad de conseguir una mejor adaptacion e informacion genetica sobre la resistencia o la reaccion a los diferentes ambientes de estres (bioticos o abioticos) a los cuales se somete el frijol en las areas de produccion. Se presentan los resultados de las mejores lineas de semilla negra y semilla roja de los VIDAC de 1987, para las caracteristicas de peso de 100 semillas, dias a floracion y a madurez fisiologica, y respuesta a enfermedades como roya (Uromyces phaseoli), bacteriosis (Xanthomonas phaseoli), BGMV y mustia hilachosa (Thanathephorus cucumeris). Tambien, se examinan el potencial de rendimiento y la adaptacion genetica de los mejores materiales en diferentes sitios. Es necesario reunir gran cantidad de informacion sobre estos ensayos nacionales y regionales en un centro de informacion y documentacion regional eficiente. (CIAT

Conductivity in Jurkat cell suspension after ultrashort electric pulsing

Ultrashort electric pulses applied to similar cell lines such as Jurkat and HL-60 cells can produce markedly different results , which have been documented extensively over the last few years. We now report changes in electrical conductivity of Jurkat cells subjected to traditional electroporation pulses (50 ms pulse length) and ultrashort pulses (10 ns pulse length) using time domain dielectric spectroscopy (TDS). A single 10 ns, 150 kV/cm pulse did not noticeably alter suspension conductivity while a 50 ms, 2.12 kV/cm pulse with the same energy caused an appreciable conductivity rise. These results support the hypothesis that electroporation pulses primarily interact with the cell membrane and cause conductivity rises due to ion transport from the cell to the external media, while pulses with nanosecond duration primarily interact with the membranes of intracellular organelles. However, multiple ultrashort pulses have a cumulative effect on the plasma membrane, with five pulses causing a gradual rise in conductivity up to ten minutes post-pulsing

Evolving the Technical Infrastructure of the Planetary Data System for the 21st Century

The Planetary Data System (PDS) was established in 1989 as a distributed system to assure scientific oversight. Initially the PDS followed guidelines recommended by the National Academies Committee on Data Management and Computation (CODMAC, 1982) and placed emphasis on archiving validated datasets. But overtime user demands, supported by increased computing capabilities and communication methods, have placed increasing demands on the PDS. The PDS must add additional services to better enable scientific analysis within distributed environments and to ensure that those services integrate with existing systems and data. To face these challenges the Planetary Data System (PDS) must modernize its architecture and technical implementation. The PDS 2010 project addresses these challenges. As part of this project, the PDS has three fundamental project goals that include: (1) Providing more efficient client delivery of data by data providers to the PDS (2) Enabling a stable, long-term usable planetary science data archive (3) Enabling services for the data consumer to find, access and use the data they require in contemporary data formats. In order to achieve these goals, the PDS 2010 project is upgrading both the technical infrastructure and the data standards to support increased efficiency in data delivery as well as usability of the PDS. Efforts are underway to interface with missions as early as possible and to streamline the preparation and delivery of data to the PDS. Likewise, the PDS is working to define and plan for data services that will help researchers to perform analysis in cost-constrained environments. This presentation will cover the PDS 2010 project including the goals, data standards and technical implementation plans that are underway within the Planetary Data System. It will discuss the plans for moving from the current system, version PDS 3, to version PDS 4

PDS4: Developing the Next Generation Planetary Data System

The Planetary Data System (PDS) is in the midst of a major upgrade to its system. This upgrade is a critical modernization of the PDS as it prepares to support the future needs of both the mission and scientific community. It entails improvements to the software system and the data standards, capitalizing on newer, data system approaches. The upgrade is important not only for the purpose of capturing results from NASA planetary science missions, but also for improving standards and interoperability among international planetary science data archives. As the demands of the missions and science community increase, PDS is positioning itself to evolve and meet those demands

Family history of prostate and colorectal cancer and risk of colorectal cancer in the Women's health initiative.

BackgroundEvidence suggests that risk of colorectal and prostate cancer is increased among those with a family history of the same disease, particularly among first-degree relatives. However, the aggregation of colorectal and prostate cancer within families has not been well investigated.MethodsAnalyses were conducted among participants of the Women's Health Initiative (WHI) observational cohort, free of cancer at the baseline examination. Subjects were followed for colorectal cancer through August 31st, 2009. A Cox-proportional hazards regression modeling approach was used to estimate risk of colorectal cancer associated with a family history of prostate cancer, colorectal cancer and both cancers among first-degree relatives of all participants and stratified by race (African American vs. White).ResultsOf 75,999 eligible participants, there were 1122 colorectal cancer cases diagnosed over the study period. A family history of prostate cancer alone was not associated with an increase in colorectal cancer risk after adjustment for confounders (aHR =0.94; 95% CI =0.76, 1.15). Separate analysis examining the joint impact, a family history of both colorectal and prostate cancer was associated with an almost 50% increase in colorectal cancer risk (aHR = 1.48; 95% CI = 1.04, 2.10), but similar to those with a family history of colorectal cancer only (95% CI = 1.31; 95% CI = 1.11, 1.54).ConclusionsOur findings suggest risk of colorectal cancer is increased similarly among women with colorectal cancer only and among those with both colorectal and prostate cancer diagnosed among first-degree family members. Future studies are needed to determine the relative contribution of genes and shared environment to the risk of both cancers

Electron Beam Ion Source Pre-Injector Diagnostics

ABSTRACT NOT PROVIDE

Nanosecond electric pulses penetrate the nucleus and enhance speckle formation

Nanosecond electric pulses generate nanopores in the interior membranes of cells and modulate cellular functions. Here, we used confocal microscopy and flow cytometry to observe Smith antigen antibody (Y12) binding to nuclear speckles, known as small nuclear ribonucleoprotein particles (snRNPs) or intrachromatin granule clusters (IGCs), in Jurkat cells following one or five 10 ns, 150 kV/cm pulses. Using confocal microscopy and flow cytometry, we observed changes in nuclear speckle labeling that suggested a disruption of pre-messenger RNA splicing mechanisms. Pulse exposure increased the nuclear speckled substructures by 2.5-fold above basal levels while the propidium iodide (PI) uptake in pulsed cells was unchanged. The resulting nuclear speckle changes were also cell cycle dependent. These findings suggest that 10 ns pulses directly influenced nuclear processes, such as the changes in the nuclear RNA–protein complexes