18,218 research outputs found
Space Shuttle External Tank Gaseous Oxygen Vent System
Two problems had to be solved to assure successful elimination of ice on the External Tank (ET). First, an access/support structure was provided from the Launch Complex 39A Fixed Service Structure to the vicinity of the nose cone on the ET approximately 82.3 meters (270 feet) above the surface of the pad and 22.9 meters (75 feet) from the face of the FSS. Second, an umbilical was designed and tested that would seal around the ET gaseous oxygen (GOX) vent louvers and not allow ice to form on the tank or the umbilical. A modified Apollo service arm was chosen. An inflatable vent seal subsystem was chosen, providing a cloth seal around each vent louver with an internal annulus to provide a path for the gaseous oxygen from the ET to a hard duct on the swing arm
The replication of DNA in Escherichia coli
Studies of bacterial transformation and bacteriaphage infection (1-5) strongly indicate that deoxyribonucleic acid (DNA) can carry and transmit hereditary information and can direct its own replication. Hypotheses for the mechanism of DNA replication differ in the predictions they make concerning the distribution among progeny molecules of atoms derived from parental molecules.(6
Adaptive information and animal behaviour: Why motorists stop at red traffic lights
Argues that information, in the animal behaviour or evolutionary context, is correlation/covariation. The alternation of red and green traffic lights is information because it is (quite strictly) correlated with the times when it is safe to drive through the intersection; thus driving in accordance with the lights is adaptive (causative of survival). Daylength is usefully, though less strictly, correlated with the optimal time to breed. Information in the sense of covariance implies what is adaptive; if an animal can infer what the information implies, it increases its chances of survival
Time (in)dependence in general relativity
We clarify the conditions for Birkhoff's theorem, that is, time-independence
in general relativity. We work primarily at the linearized level where guidance
from electrodynamics is particularly useful. As a bonus, we also derive the
equivalence principle. The basic time-independent solutions due to
Schwarzschild and Kerr provide concrete illustrations of the theorem. Only
familiarity with Maxwell's equations and tensor analysis is required.Comment: Revised version of originally titled "Kinder Kerr", to appear in
American Journal of Physic
Segmented back-up bar Patent
Segmented back-up bar for butt welding large tubular structures such as rocket booster bodies or tank
Safe Harbor for Officer Reliance: Comparing the Approaches of the Model Business Corporation Act and Delaware’s General Corporation Law
Balotti and Shaner discuss the duties of and potential for imposing liability on corporate officers. The fiduciary duties of officers is addressed, in differing degrees, under Delaware law, the law frequently applied to corporate-governance disputes, and under the Model Business Corporation Act (MBCA). In discharging their fiduciary duties, directors under both the MBCA and the General Corporation Law are generally protected from personal liability if, in making business decisions, they reasonably rely on the reports and records of officers, employees, advisors, and experts of the corporation
A study of systems implementation languages for the POCCNET system
The results are presented of a study of systems implementation languages for the Payload Operations Control Center Network (POCCNET). Criteria are developed for evaluating the languages, and fifteen existing languages are evaluated on the basis of these criteria
Coercion, vertical trust and entrepreneurism in bureaucracies: evidence from the Nazi Holocaust
Breton and Wintrobe (1982) develop a non-traditional (modern) model of bureaucratic management that is based on the notion of “vertical trust†– the notion that subordinates “trade services†that advance the goals of the bureau''s leadership in return for various “informal payments,†none of which are codified in formal contracts between the two sets of parties. Applying the model to the Nazi bureaucracy explains how Nazi functionaries, such as Adolf Eichmann, acted as bureaucratic entrepreneurs in accomplishing goals relating to “the Jewish question,†and ultimately “the Final Solution,†for their superiors, such as Adolf Hitler and Heinrich Himmler (Breton and Wintrobe, 1986). As an extension of prior research, the current study examines the hypothesis that the use these vertical trust relationships within the borders of their minor Axis partners (e.g., Hungary) worked more effectively for the Germans than coercion, which would have been required to a greater degree within the borders of occupied European countries (e.g., Holland). Specifically, our estimates suggest that, ceteris paribus, owing to their use of vertical trust networks the minor Axis countries each contributed about 152,000 more European Jews to the Nazi Holocaust apparatus than their German-occupied European country counterparts, wherein the Nazis relied more heavily on coercion.bureaucratic entrepreneurship, vertical trust networks, coercion, statistical decomposition tests
Neurohumoral and mechanical factors in the modulation of left ventricular mass
The goals for the research were to define, describe, and study those neuroendocrine and mechanical mechanisms that may play a role in the initiation and maintenance of an increase in, or cause regression of, the mass of the left ventricle. Dynamic changes in heart mass have been observed to occur in man and animals: (1) enlargement of the heart is frequently encountered in patients with hypertensive disease, and (2) decrease in heart mass has been reported for men exposed to prolonged space flight. The basic physiologic processes which may explain how these changes occur, and the effects of gain or loss of myocardial mass on cardiac performance were considered significant questions to be answered for the benefit of the National Aeronautics and Space Administration
Powered-lift aircraft technology
Powered lift aircraft have the ability to vary the magnitude and direction of the force produced by the propulsion system so as to control the overall lift and streamwise force components of the aircraft, with the objective of enabling the aircraft to operate from minimum sized terminal sites. Power lift technology has contributed to the development of the jet lift Harrier and to the forth coming operational V-22 Tilt Rotor and the C-17 military transport. This technology will soon be expanded to include supersonic fighters with short takeoff and vertical landing capability, and will continue to be used for the development of short- and vertical-takeoff and landing transport. An overview of this field of aeronautical technology is provided for several types of powered lift aircraft. It focuses on the description of various powered lift concepts and their operational capability. Aspects of aerodynamics and flight controls pertinent to powered lift are also discussed
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