4,485 research outputs found
Introduction to orbital flight planning (1)
This workbook is designed for students interested in space flight planning, who after training, may serve as flight planning aides. Routine flight planning activities requiring engineering-type calculations and analysis are covered. Practice exercises and brief instructions are given for the programming and use of the hand calculator as well as the calculation of position and velocity in the orbital plane. Calculation of relative orbital position is also covered with emphasis upon celestial coordinates and time measurement
Untangling patterns of plant and arthropod diversity in a fire-adapted ecosystem: Dynamic relationships between fire, scale, and trophic interactions in longleaf pine forests.
Fire has been a part of terrestrial ecosystems since the Silurian Period and is an essential process for maintaining both ecosystem function and biological diversity in fire dependent ecosystems, such as longleaf pine (Pinus palustris Mill.). In these frequently burned fire-dependent ecosystems, fire frequency is positively correlated with high species diversity. The removal of fire from the landscape initiates a shifting ecosystem trajectory where fire-adapted species are replaced by other species assemblages, yielding an alternative stable state.Patterns of biodiversity and the mechanisms driving them must be thoroughly understood to guide an effective monitoring and resource management programs. I describe cross-scale spatial and temporal patterns of plant and arthropod diversity, identification of the grain size and sampling effort to maximize efficiency in monitoring diversity, fine-scale examination of the role of fire in driving patterns of diversity, and mechanisms linking fire, biological diversity, and forest structure. Understanding these links mechanistically is critical for both guiding management now and in the future under the novel conditions expected with global change.By sampling arthropod diversity and creating linkages to plant diversity at multiple spatial and temporal scales, I could better understand how both plant and animal communities, as well as their interactions, are organized with respect to presence or absence of fire. My quantification of multiple dimensions of diversity, including taxonomic and functional metrics, reflect the current focus of biodiversity researchers in both basic and applied realms and further provides novel insight into debates about neutrality and correlations between diversity, stability, resiliency, and ecosystem services The interaction diversity measure is particularly important for linking biodiversity to the trillions of dollars of ecosystem services that are provided by natural ecosystems, since those services are all due to a diverse mix of ecological interactions. Taken together, these metrics of diversity can act as more sensitive indicators of how ecological communities respond to management activities, disturbances, or global change parameters
Special Issue: Anti-Inflammatory Activity of Plant Polyphenols
Inflammation is considered the first physiological response of the human body to infection or injury, playing a critical role in both innate and adaptive immunity [...]
A visão dos alunos sobre aquecimento global a partir do documentário verdade inconveniente
Nesse trabalho, alunos da educação básica (10 – 11 anos) assistiram ao documentário Verdade Inconveniente de Al Gore (2003), em que o tema central é o aquecimento global. Centramos nossa discussão em que aspectos foram mais atrativos aos alunos ao assistirem ao vídeo e qual a importância de tais escolhas para o ensino de ciências. Nesse contexto, analisamos as respostas dos estudantes a uma pergunta aberta em relação ao vídeo a partir do padrão de argumento de Stephen Toulmin (2006) visando observar a presença de conceitos científicos apresentados no vídeo. Além disso, analisar quais informações veiculadas são mais significativas aos alunos a partir do referencial da multimodalidade (Jewitt et. al. , 2001)
Reliability of U.S.D.A. beef carcass yield grades in reflecting differences in retail yields
Retail cut-out and U.S.D.A. yield grade data were obtained on 1,121 carcasses of steers from Hereford and Angus dams mated artificially to Hereford, Angus, Jersey, Limousin, South Devon, Simmental and Charolais bulls. Calves were weaned when approximately 215 days old, conditioned 28 days, fed an average of 218 days after weaning before being slaughtered in a commercial slaughter plant. Carcass cooler data were obtained and the right side of each carcass was cut into closely trimmed, essentially boneless retail cuts at the KSU food service building. Beef yield grades do reflect definite differences in retail yields. Statistical tests indicated less than one chance in 1,000 that such differences occurred by chance and that the yield grade differences were real. The average difference in retail product percentage between yield grades was 4.6 percent. The average difference in fat trim percentage was 5.6 percent. For 700-pound carcasses, that\u27s a difference of 39.2 pounds of waste fat, or 32.2 pounds of retail product. The difference in bone percentage would account for the other 7 pounds
Response of glacier flow and structure to proglacial lake development and climate at Fjallsjökull, south-east Iceland
ABSTRACTOver recent decades, the number of outlet glaciers terminating in lakes in Iceland has increased in line with climate warming. The mass-balance changes of these lake-terminating outlet glaciers are sensitive to rising air temperatures, due to altered glacier dynamics and increased surface melt. This study aims to better understand the relationship between proglacial lake development, climate, glacier dynamics and glacier structure at Fjallsjökull, a large, lake-terminating outlet glacier in south-east Iceland. We used satellite imagery to map glacier terminus position and lake extent between 1973 and 2016, and a combination of aerial and satellite imagery to map the structural architecture of the glacier's terminus in 1982, 1994 and 2011. The temporal evolution of ice surface velocities between 1990 and 2018 was calculated using feature tracking. Statistically significant increases in the rate of terminus retreat and lake expansion were identified in 2001, 2009 and 2011. Our surface velocity and structural datasets revealed the development of localised flow ‘corridors’ over time, which conveyed relatively faster flow towards the glacier's terminus. We attribute the overall changes in dynamics and structural architecture at Fjallsjökull to rising air temperatures, but argue that the spatial complexities are driven by glacier specific factors, such as basal topography.</jats:p
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