The volume elements intercepted by intersecting cylinders

Call number: LD2668 .T4 1935 H3

TASS Mark IV Photometric Survey of the Northern Sky

The Amateur Sky Survey (TASS) is a loose confederation of amateur and professional astronomers. We describe the design and construction of our Mark IV systems, a set of wide-field telescopes with CCD cameras which take simultaneous images in the $V$ and $I_C$ passbands. We explain our observational procedures and the pipeline which processes and reduces the images into lists of stellar positions and magnitudes. We have compiled a large database of measurements for stars in the northern celestial hemisphere with $V$-band magnitudes in the range 7 < V < 13. This paper describes data taken over the four-year period starting November, 2001. One of our results is a catalog of repeated measurements on the Johnson-Cousins system for over 4.3 million stars.Comment: Accepted for publication in December, 2006, issue of PASP. 44 pages including 20 figures. Patches catalog available at http://spiff.rit.edu/tass/patches

An improved approach for flight readiness assessment

An improved methodology for quantitatively evaluating failure risk for a spaceflight system in order to assess flight readiness is presented. This methodology is of particular value when information relevant to failure prediction, including test experience and knowledge of parameters used in engineering analyses of failure phenomena, is limited. In this approach, engineering analysis models that characterize specific failure modes based on the physics and mechanics of the failure phenomena are used in a prescribed probabilistic structure to generate a failure probability distribution that is modified by test and flight experience in a Bayesian statistical procedure. The probabilistic structure and statistical methodology are generally applicable to any failure mode for which quantitative engineering analysis can be employed to characterize the failure phenomenon and are particularly well suited for use under the constraints on information availability that are typical of such spaceflight systems as the Space Shuttle and planetary spacecraft

Radioisotopes as political instruments, 1946-1953

The development of nuclear «piles», soon called reactors, in the Manhattan Project provided a new technology for manufacturing radioactive isotopes. Radioisotopes, unstable variants of chemical elements that give off detectable radiation upon decay, were available in small amounts for use in research and therapy before World War II. In 1946, the U.S. government began utilizing one of its first reactors, dubbed X-10 at Oak Ridge, as a production facility for radioisotopes available for purchase to civilian institutions. This program of the U.S. Atomic Energy Commission was meant to exemplify the peacetime dividends of atomic energy. The numerous requests from scientists outside the United States, however, sparked a political debate about whether the Commission should or even could export radioisotopes. This controversy manifested the tension in U.S. politics between scientific internationalism as a tool of diplomacy, associated with the aims of the Marshall Plan, and the desire to safeguard the country's atomic monopoly at all costs, linked to American anti-Communism. This essay examines the various ways in which radioisotopes were used as political instruments -both by the U.S. federal government in world affairs, and by critics of the civilian control of atomic energy- in the early Cold War

Diabetes and vascular disease: pathophysiology, clinical consequences, and medical therapy: part I

Hyperglycemia and insulin resistance are key players in the development of atherosclerosis and its complications. A large body of evidence suggest that metabolic abnormalities cause overproduction of reactive oxygen species (ROS). In turn, ROS, via endothelial dysfunction and inflammation, play a major role in precipitating diabetic vascular disease. A better understanding of ROS-generating pathways may provide the basis to develop novel therapeutic strategies against vascular complications in this setting. Part I of this review will focus on the most current advances in the pathophysiological mechanisms of vascular disease: (i) emerging role of endothelium in obesity-induced insulin resistance; (ii) hyperglycemia-dependent microRNAs deregulation and impairment of vascular repair capacities; (iii) alterations of coagulation, platelet reactivity, and microparticle release; (iv) epigenetic-driven transcription of ROS-generating and proinflammatory genes. Taken together these novel insights point to the development of mechanism-based therapeutic strategies as a promising option to prevent cardiovascular complications in diabete

Diabetes and vascular disease: pathophysiology, clinical consequences, and medical therapy: part I

Hyperglycemia and insulin resistance are key players in the development of atherosclerosis and its complications. A large body of evidence suggest that metabolic abnormalities cause overproduction of reactive oxygen species (ROS). In turn, ROS, via endothelial dysfunction and inflammation, play a major role in precipitating diabetic vascular disease. A better understanding of ROS-generating pathways may provide the basis to develop novel therapeutic strategies against vascular complications in this setting. Part I of this review will focus on the most current advances in the pathophysiological mechanisms of vascular disease: (i) emerging role of endothelium in obesity-induced insulin resistance; (ii) hyperglycemia-dependent microRNAs deregulation and impairment of vascular repair capacities; (iii) alterations of coagulation, platelet reactivity, and microparticle release; (iv) epigenetic-driven transcription of ROS-generating and proinflammatory genes. Taken together these novel insights point to the development of mechanism-based therapeutic strategies as a promising option to prevent cardiovascular complications in diabetes

The Vietnam-Era Veteran Enters College

During the past few years, new kinds of students have been entering our colleges and universities. No longer can the uppermiddle class white male, who moves smoothly from a college preparatory program in high school directly into college, be regarded as the typical student. Among the various groups of nontraditional students that make for greater heterogeneity within the college population are those from racial or ethnic minorities, those from lower socioeconomic backgrounds, those whose academic ability or high school preparation is relatively poor (as judged by conventional criteria) and those who are older than the average undergraduate. One subgroup of this last category consists of those whose college education was delayed or interrupted by military service during the Vietnam era, whether they actually served in Southeast Asia or not. It is generally recognized that such students may benefit from college at least as much as the typical student

The Development of Wheels for the Lunar Roving Vehicle

The Lunar Roving Vehicle (LRV) was developed for NASA s Apollo program so astronauts could cover a greater range on the lunar surface, carry more science instruments, and return more soil and rock samples than by foot. Because of the unique lunar environment, the creation of flexible wheels was the most challenging and time consuming aspect of the LRV development. Wheels developed for previous lunar systems were not sufficient for use with this manned vehicle; therefore, several new designs were created and tested. Based on criteria set by NASA, the choices were narrowed down to two: the wire mesh wheel developed by General Motors (GM), and the hoop spring wheel developed by the Bendix Corporation. Each of these underwent intensive mechanical, material, and terramechanical analyses, and in the end, the wire mesh wheel was chosen for the LRV. Though the wire mesh wheel was determined to be the best choice for its particular application, it may be insufficient towards achieving the objectives of future lunar missions that could require higher tractive capability, increased weight capacity, or extended life. Therefore lessons learned from the original LRV wheel development and suggestions for future Moon wheel projects are offered