5,086 research outputs found
Variable geometry manned orbital vehicle Patent
Variable geometry manned orbital vehicle having high aerodynamic efficiency over wide speed range and incorporating auxiliary pivotal wing
Comparison of Space Shuttle Orbiter low-speed static stability and control derivatives obtained from wind-tunnel and approach and landing flight tests
Tests were conducted in the 8 foot transonic pressure tunnel to obtain wind tunnel data for comparison with static stability and control parameters measured on the space shuttle orbiter approach and landing flight tests. The longitudinal stability, elevon effectiveness, lateral directional stability, and aileron effectiveness derivatives were determined from the wind tunnel data and compared with the flight test results. The comparison covers a range of angles of attack from approximately 2 deg to 10 deg at subsonic Mach numbers of 0.41 to 0.56. In general the wind tunnel results agreed well with the flight test results, indicating the wind tunnel data is applicable to the design of entry vehicles for subsonic speeds over the angle of attack range studied
Criminal Liability for "Photographic Piracy"?
The author is a Professor Emeritus of Cambridge University, where for many years Tony Smith was his friend and valued colleague. In this article he critically analyses the existing law in relation to taking or publishing photographs of other people without their consent and considers the desirability of extending criminal liability for such behaviour by the creation of a new criminal offence
Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine
Length-frequency data collected from inshore and offshore locations in the Gulf of Maine in 1966-1968 indicated that ovigerous female northern shrimp (Pandalus borealis) first appeared offshore in August and September and migrated
inshore in the fall and winter. Once eggs hatched, surviving females returned offshore. Juveniles and males migrated offshore during their first two years of life. Sex transition occurred in both inshore and oll'shore waters, but most males changed sex offshore during their third and fourth years. Most shrimp changed sex and matured as females for the first time in their fourth year. Smaller females and females exposed to colder bottom temperatures spawned first. The incidence of egg parasitism peaked in January and was higher for shrimp exposed to warmer bottom temperatures. Accelerated growth at higher temperatures appeared to result in earlier or more rapid sex transition. Males and non-ovigerous females were observed to make diurnal vertical migrations, but were not found in near-
surface waters where the temperature exceeded 6°C. Ovigerous females fed more heavily on benthic molluscs in inshore waters in the winter, presumably because the egg masses they were carrying prevented them from migrating vertically at night.
Northern shrimp were more abundant in the southwestern region of the Gulf of Maine where bottom temperatures remain low throughout the year. Bottom trawl catch rates were highest in Jeffreys Basin where bottom temperatures were lower than at any other sampling location. Catch rates throughout the study area were inversely related to bottom temperature and reached a maximum at 3°C.
An increase of 40% in fecundity between 1973 and 1979 was associated with a decline of 2-3°C in April-July offshore bottom temperatures. Furthermore, a decrease in mean fecundity per 25 mm female between 1965 and 1970 was linearly related to reduced landings between 1969 and 1974. It is hypothesized that temperature-induced changes in fecundity and, possibly, in the extent of egg mortality
due to parasitism, may provide a mechanism which could partially account for changes in the size of the Gulf of Maine northern shrimp population during the last thirty years. (PDF file contains 28 pages.
Deconstructing bioluminescence: from molecular detail to in vivo imaging.
Bioluminescence is the chemical production of light that results when a luciferase enzyme catalyzes the luminogenic oxidation of a small-molecule luciferin substrate. The numerous luciferases and luciferins nature has evolved can be used to illuminate biological processes, from in vitro assays to imaging processes in live animals. However, we can improve the utility of bioluminescence through modification of these enzymes and substrates. My thesis work focuses on developing reporters that expand the bioluminescent toolkit and improving our understanding of how bioluminescence works on a molecular level.
The first part of my thesis focuses on characterizing luciferases and luciferins that improve bioluminescence imaging in vivo. Some of our luciferins can outperform the natural D-luciferin substrate in live mouse imaging, while others are selectively utilized by mutant luciferases in live mouse brain. We also engineered luciferins that can selectively report on endogenous enzymatic activity in live mice.
The second part of my thesis focuses on determining the molecular details of how enzymes related to firefly luciferase, long-chain fatty acyl-CoA synthetases (ACSLs), can function as latent luciferases. I have determined the structure for one of these enzymes and improved its bioluminescent activity with synthetic luciferins enough to image in live mouse brain. I also characterized the selectivity in chimerized enzymes that combine firefly luciferase and ACSLs. In summary, my work improves the utility of bioluminescence for in vivo use and informs us about how evolutionarily-related enzymes function as luciferases on a molecular level
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