Measuring the Hubble Constant with the Hubble Space Telescope

Ten years ago our team completed the Hubble Space Telescope Key Project on the extragalactic distance scale. Cepheids were detected in some 25 galaxies and used to calibrate four secondary distance indicators that reach out into the expansion field beyond the noise of galaxy peculiar velocities. The result was H_0 = 72 +/- 8 km/sec/Mpc and put an end to galaxy distances uncertain by a factor of two. This work has been awarded the Gruber Prize in Cosmology for 2009.Comment: Gruber Prize Lecture to be published in Transactions of the IA

Static internal performance characteristics of two thrust reverser concepts for axisymmetric nozzles

The statis performance of two axisymmetric nozzle thrust reverser concepts was investigated. A rotating vane thrust reverser represented a concept in which reversing is accomplished upstream of the nozzle throat, and a three door reverser concept provided reversing downstream of the nozzle throat. Nozzle pressure ratio was varied from 2.0 to approximately 6.0. The results of this investigation indicate that both the rotating vane and three door reverser concepts were effective static thrust spoilers with the landing approach nozzle geometry and were capable of providing at least a 50 percent reversal of static thrust when fully deployed with the ground roll nozzle geometry

Static internal performance including thrust vectoring and reversing of two-dimensional convergent-divergent nozzles

The effects of geometric design parameters on two dimensional convergent-divergent nozzles were investigated at nozzle pressure ratios up to 12 in the static test facility. Forward flight (dry and afterburning power settings), vectored-thrust (afterburning power setting), and reverse-thrust (dry power setting) nozzles were investigated. The nozzles had thrust vector angles from 0 deg to 20.26 deg, throat aspect ratios of 3.696 to 7.612, throat radii from sharp to 2.738 cm, expansion ratios from 1.089 to 1.797, and various sidewall lengths. The results indicate that unvectored two dimensional convergent-divergent nozzles have static internal performance comparable to axisymmetric nozzles with similar expansion ratios

Static internal performance of single-expansion-ramp nozzles with various combinations of internal geometric parameters

The effects of five geometric design parameters on the internal performance of single-expansion-ramp nozzles were investigated at nozzle pressure ratios up to 10 in the static-test facility of the Langley 16-Foot Transonic Tunnel. The geometric variables on the expansion-ramp surface of the upper flap consisted of ramp chordal angle, ramp length, and initial ramp angle. On the lower flap, the geometric variables consisted of flap angle and flap length. Both internal performance and static-pressure distributions on the centerlines of the upper and lower flaps were obtained for all 43 nozzle configurations tested

Static internal performance of a single-engine onaxisymmetric-nozzle vaned-thrust-reverser design with thrust modulation capabilities

An investigation has been conducted at wind-off conditions in the stati-test facility of the Langley 16-Foot Transonic Tunnel. The tests were conducted on a single-engine reverser configuration with partial and full reverse-thrust modulation capabilities. The reverser design had four ports with equal areas. These ports were angled outboard 30 deg from the vertical impart of a splay angle to the reverse exhaust flow. This splaying of reverser flow was intended to prevent impingement of exhaust flow on empennage surfaces and to help avoid inlet reingestion of exhaust gas when the reverser is integrated into an actual airplane configuration. External vane boxes were located directly over each of the four ports to provide variation of reverser efflux angle from 140 deg to 26 deg (measured forward from the horizontal reference axis). The reverser model was tested with both a butterfly-type inner door and an internal slider door to provide area control for each individual port. In addition, main nozzle throat area and vector angle were varied to examine various methods of modulating thrust levels. Other model variables included vane box configuration (four or six vanes per box), orientation of external vane boxes with respect to internal port walls (splay angle shims), and vane box sideplates. Nozzle pressure ratio was varied from 2.0 approximately 7.0

Technology applications

A summary of NASA Technology Utilization programs for the period of 1 December 1971 through 31 May 1972 is presented. An abbreviated description of the overall Technology Utilization Applications Program is provided as a background for the specific applications examples. Subjects discussed are in the broad headings of: (1) cancer, (2) cardiovascular disease, (2) medical instrumentation, (4) urinary system disorders, (5) rehabilitation medicine, (6) air and water pollution, (7) housing and urban construction, (8) fire safety, (9) law enforcement and criminalistics, (10) transportation, and (11) mine safety

Introduction to the Spring/Summer 2010 Issue, Strategic Insights, v. 9, issue 1; Strategic Insights, v. 9, issue 1 (Spring/Summer 2010) ; pp. 1-2

This article appeared in Strategic Insights, v.9, issue 1 (Spring/Summer 2010) ; pp. 1-2This issue of Strategic Insights, explores the complex realm of asymmetric warfare, specifically the role it plays in a variety of weak and developing states. Its articles focus on how states can understand, approach, and defend against the many manifestations and evolving nature of asymmetric warfare in an age where globalization increases the interconnectivity of state and non-state actors alike. In its simplest form, asymmetric warfare is characterized as two belligerents with differing military capabilities where each side attempts to exploit the weaknesses of the other with conventional and unconventional strategies and tactics. The 2010 U.S. National Security Strategy warns that, ﾓWars over ideology have given way to wars over religious, ethnic, and tribal identity; nuclear dangers have proliferated; inequality and economic instability have intensified; damage to our environment, food insecurity, and dangers to public health are increasingly shared; and the same tools that empower individuals to build enable them to destroy.Approved for public release; distribution is unlimited

Factors Which Affect Satisfaction And Dissatisfaction Of Teachers In Rural Schools (Nevada; Arizona; Utah)

Sergiovanni, replicating a design developed and used by Herzberg, found that teaching had its own unique set of job satisfiers and dissatisfiers. This study investigated teachers in rural schools for congruency with the job satisfiers and dissatisfiers identified by Sergiovanni; It was hypothesized that when rural school teachers responded to the Sergiovanni factors, there was no significant difference between the proportion of times a given factor was reported as a satisfier and the proportion of times the same factor was reported as a dissatisfier; It was also hypothesized that based on the frequency of job satisfaction and dissatisfaction incidents, teachers in rural schools were no more satisfied nor dissatisfied than teachers in general; This study (replicating the Sergiovanni Study) used the interview method to investigate factors, attitudes, and effects of job satisfaction or dissatisfaction of teachers in rural schools. Sixty-six schools with a teaching staff ranging from one to thirty teachers, selected from sixteen school districts in Nevada, Utah, and Northwestern Arizona, were used to identify a sample of 60 teachers from a 750 teacher population. Statistical analyses were made to determine if significant correlation existed between the research data and job satisfiers or job dissatisfiers as identified by Sergiovanni; The investigation supported the reliability of the Herzberg method in that the results were in general agreement with Herzberg\u27s study. The Sergiovanni study concluded that some satisfaction factors identified by Herzberg were not applicable to teachers. This study identified not only the same non-applicable factors, but additional factors not applicable to teachers in rural schools; It was concluded that as long as a teacher experienced personal success, and was recognized for the success, he/she derived satisfaction from work. It was also concluded that the interpersonal relationship with students allowed for such feelings of personal success. Interpersonal relationship with students remained as a low attitude factor but tended to indicate a strong possibility of being a \u27swing\u27 factor, showing a tendency to be bi-polar

A study of the religious position of Christopher Marlowe as influenced by the Erasmian humanistic tradition

Christopher Marlow still remains a largely undefined dramatist in the twentieth century. Scholarship in the past fifty years has shed much light on the historical facts of his life, but there has been little effort to place his dramatic output in the stream of English letters. He remains to many a curiosity, both in the style and the content of his works. The facts of Marlowe’s life, discovered by scholars, have created as many problems as they have solved. Fragmentary evidence has been utilized in an effort to prove Marlow an atheist, while other fragments have been used in an effort to prove he was a Catholic and still other evidence sees Marlowe as an Anglican in the service of the Queen. All of this conjecture has some basis in fact, but by the contradictory nature of the allegations, Marlowe could not possibly have been all three