873 research outputs found
On-Orbit Teflon(trademark) FEP Degradation
During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multi-layer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(trademark) FEP sample evaluation and additional testing of pristine Teflon FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations, and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the Teflon(trademark) FEP
The Hubble Space Telescope (HST) Contamination Control Program
Over the past two decades, the Hubble Space Telescope (HST) Contamination Control Program has evolved from a ground-based integration program to a space-based science-sustaining program. On-orbit, the telescope s primary contamination requirement was maintaining a low contamination flux in the telescope s optical path. In addition, to maintain the scientific capability of the telescope, the contamination requirements and specific contamination controls from the second- and third-generation Scientific Instruments and Orbital Replacement Units were captured within the HST Contamination Control Program. Contamination controls were developed for on-orbit operations and four Servicing Missions (Orbiter, Astronauts, and mission). Long-term on-orbit scientific data has shown that these contamination controls successfully protected the HST from contamination
Assessing Washington State Landowners\u27 Interest and Concerns Regarding Growing Bioenergy Crops
Bioenergy industries will depend, in part, on interested and informed landowners who are willing to grow bioenergy crops. We surveyed landowners in Washington State to gain insight into their knowledge and interest regarding bioenergy crops and the importance of various cropping decision factors. The majority of landowners surveyed were not familiar with bioenergy crops and/or were unlikely to grow them. They indicated that profit, soil and land preservation, and water quality are all important factors to consider when making cropping decisions. Our results provide Extension professionals with an enhanced understanding of perceived challenges and advantages related to growing bioenergy crops
Genetic Variation and Differentiation in Mexican Populations of Common Bush-Tanagers and Chestnut-Capped Brush-Finches
Genetic differentiation among four Mexican populations each of Common Bush-tanagers (Chlorospingus ophthalmicus) and Chestnut-capped Brush-finches (Atlapetes brunneinucha) was evaluated using allozyme electrophoresis. In both species, although levels of within-population variation are moderate, among-population variation is extreme, including fixed differences among populations. Genetic variation is significantly reduced in some populations on the smallest habitat islands. Differentiation is apparently unrelated to geographic distance among populations, and effects of habitat island size and isolation on genetic differentiation are not clear. Populations of the Sierra de los Tuxtlas in Veracruz, however, are strongly differentiated in both species
Tools for Assessing Climate Impacts on Fish and Wildlife
Climate change is already affecting many fish and wildlife populations. Managing these populations requires an understanding of the nature, magnitude, and distribution of current and future climate impacts. Scientists and managers have at their disposal a wide array of models for projecting climate impacts that can be used to build such an understanding. Here, we provide a broad overview of the types of models available for forecasting the effects of climate change on key processes that affect fish and wildlife habitat (hydrology, fire, and vegetation), as well as on individual species distributions and populations. We present a framework for how climate-impacts modeling can be used to address management concerns, providing examples of model-based assessments of climate impacts on salmon populations in the Pacific Northwest, fire regimes in the boreal region of Canada, prairies and savannas in the Willamette Valley-Puget Sound Trough-Georgia Basin ecoregion, and marten Martes americana populations in the northeastern United States and southeastern Canada. We also highlight some key limitations of these models and discuss how such limitations should be managed. We conclude with a general discussion of how these models can be integrated into fish and wildlife management
Extension Professionals\u27 Perspectives on Supporting Feedstock Production for Biofuels: Concerns, Challenges, and Opportunities
The development of successful bioenergy programs will depend on informed and prepared Extension professionals who are willing and equipped to provide technical support. A survey of Extension professionals in the Pacific Northwest revealed barriers to program development, including limits on time and knowledge and concerns about economic returns for biofuel crops. Without the promise of market opportunities, Extension professionals may be unwilling to devote requisite resources to bioenergy programs. However, government policies and mandates make the rise of biofuels highly likely. Extension professionals should look to the future and consider blending bioenergy education into existing programs
Growing Green Energy: A Review of Extension\u27s Role in the Development of Advanced Biofuels
The development of advanced biofuels is expanding the possibilities for purpose-grown energy crops. Growers, producers, and other stakeholders will need a reliable source of information to assist with decision-making regarding renewable fuel supply chains. This review examines Extension\u27s role in the innovation of advanced biofuels by documenting and summarizing Extension work in existing biomass-derived energy programs. This review highlights strategies used by Extension programs that help make renewable energy innovations successful
Evaluation and Selection of Replacement Thermal Control Materials for the Hubble Space Telescope
The mechanical and optical properties of the metallized Teflon(Registered Trademark) FEP thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. A Failure Review Board was established to investigate the damage to the MLI and identify a replacement material. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain structural integrity for at least ten years. Ten candidate materials were selected and exposed to ten-year HST-equivalent doses of simulated orbital environments. Samples of the candidates were exposed sequentially to low and high energy electrons and protons, atomic oxygen, x-ray radiation, ultraviolet radiation and thermal cycling. Following the exposures, the mechanical integrity and optical properties of the candidates were investigated using Optical Microscopy, Scanning Electron Microscopy (SEM), and a Laboratory Portable Spectroreflectometer (LPSR). Based on the results of these simulations and analyses, the FRB selected a replacement material and two alternates that showed the highest likelihood of providing the requisite thermal properties and surviving for ten years in orbit.
Hubble Space Telescope Metallized Teflon(registered trademark) FEP Thermal Control Materials: On-Orbit Degradation and Post-Retrieval Analysis
During the Hubble Space Telescope (HST) Second Servicing Mission (SM2), degradation of unsupported Teflon(Registered Trademark) FEP (fluorinated ethylene propylene), used as the outer layer of the multilayer insulation (MLI) blankets, was evident as large cracks on the telescope light shield. A sample of the degraded outer layer was retrieved during the mission and returned to Earth for ground testing and evaluation. The results of the Teflon(Registered Trademark) FEP sample evaluation and additional testing of pristine Teflon(Registered Trademark) FEP led the investigative team to theorize that the HST damage was caused by thermal cycling with deep-layer damage from electron and proton radiation which allowed the propagation of cracks along stress concentrations , and that the damage increased with the combined total dose of electrons, protons, UV and x-rays along with thermal cycling. This paper discusses the testing and evaluation of the retrieved Teflon(Registered Trademark) FEP
Bird faunas of the humid montane forests of Mesoamerica: biogeographic patterns and priorities for conservation
The distribution of 335 species of birds in 33 islands of humid montane forest in
Mesoamerica is summarized, and patterns of distribution, diversity and endemism are
analysed. The montane forests of Costa Rica and western Panama far exceed other habitat
islands considered for species-richness, richness of species endemic to Mesoamerica,
and richness of species ecologically restricted to humid montane forests. Other regions,
such as the Sierra Madre del Sur of Guerrero and Oaxaca, the Los Tuxtlas region of
southern Veracruz and the mountains of Chiapas and Guatemala, also hold rich and
endemic avifaunas. Based on patterns of similarity of avifaunas, the region can be divided
into seven regions holding distinctive avifaunas (Costa Rica and western Panama;
northern Central America and northern Chiapas; southern Chiapas; eastern Mexico north
of the Isthmus of Tehuantepec; Sierra Madre del Sur; interior Oaxaca; and Transvolcanic
Belt and Sierra Madre Occidental), which serve as useful guides for the setting of
priorities for conservation action.
Se resumen las distribuciones de 335 especies de aves en 33 islas de bosque humedo de
montana en Mesoamerica, y se analizan patrones de distribution, diversidad y
endemismo. Los bosques montanos de Costa Rica y del oeste de Panama tienen la mas
alta riqueza de especies, riqueza de especies endemicas a Mesoamerica, y riqueza de
especies ecologicamente restringidas a bosque humedo de montana. Otras regiones, tales
como la Sierra Madre del Sur de Guerrero y Oaxaca, la region de Los Tuxtlas y las
montanas de Chiapas y Guatemala, tambien tienen avifaunas ricas en especies y en
endemicas. Basado en patrones de similitud de avifaunas, se puede dividir Mesoamerica
en siete regiones que tienen avifaunas distintas (Costa Rica y el oeste de Panama; el
norte de Centroamerica y el norte de Chiapas; el sur de Chiapas; el este de Mexico; la
Sierra Madre del Sur; el interior de Oaxaca; y el Eje Neovolcanico y la Sierra Madre
Occidental), las cuales pueden servir como guias en el establecimiento de prioridades
para la conservation
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