Thermal and cryogenic design study for space infrared telescope facility (SIRTF)

A study was conducted to determine the ability of an all superfluid helium design to meet the performance requirements of background limited to 200 micrometer, and a two year lifetime for a one meter class free flying infrared observatory. Both a 98 deg and 28.5 deg inclination orbits were examined, and aperture shade designs were developed for both orbits. A unique forebaffle cooling design significantly reduces the sensitivity to aperture heat loads. With certain restrictions on observing modes, the study determined that an all superfluid helium Dewar will meet the temperature and lifetime requirements. A dual cryogen SFHe/SH2 system was also investigated for the 28.5 deg orbit and found to provide a more constant forebaffle temperature but with only a slight improvement in lifetime

In-trail dynamics of multiple CDTI-equipped aircraft queues

One of the potential problems of in-trail self-spacing with a Cockpit Display of Traffic Information (CDTI) is whether dynamic oscillations would occur in a queue of aircraft flying an approach, similar to the ""accordion'' effect seem with the queue of automobiles in stop-and-go traffic. In order to gain some insight into this potential problem, a brief experiment was conducted with the Transport Systems Research Vehicle (TSRV) ground-based simulator equipped with CDTI which presented the position of other aircraft in the area. Three simulation sessions were conducted wherein queues of up to nine aircraft were built, each one self-spacing on the preceding aircraft. The aircraft crews were rotated to ensure that the pilots had no prior knowledge of the lead aircraft behavior they would be following. Two different spacing criteria were employed: a constant time predictor criterion and a constant time delay criterion. The experiment failed to uncover any dynamic oscillatory tendencies in queues of seven to nine aircraft

Assessing student perceptions of the Pharm.D. degree at a private tertiary medical university in India

Background: Pharmacy education in India has expanded to include the Doctorate of Pharmacy degree (Pharm.D.). With clinical practice in early development, job opportunities in India are limited. Graduates often consider pharmacy opportunities abroad. Aims: This study compares Indian students’ career aspirations related to the Pharm.D. degree before and after beginning their programmes. Methods: A 5-point Likert scale paper survey with open ended questions was distributed to all Pharm.D. students (Year 1- 6) at a medical university in India. Results: With a response rate of 83% (144/173), over half of the students’ primary goal was to pursue careers abroad post-graduation (54.2% before, 51.4% after). Data from the last three graduating classes indicated that 28.3% travelled abroad for future studies while 62.3% secured positions in India. Conclusions: Opportunities abroad remain challenging for Indian trained Pharm.D.s’; graduates may consider the expanding clinical opportunities in India

Space shuttle OMS helium regulator design and development

Analysis, design, fabrication and design verification testing was conducted on the technological feasiblity of the helium pressurization regulator for the space shuttle orbital maneuvering system application. A prototype regulator was fabricated which was a single-stage design featuring the most reliable and lowest cost concept. A tradeoff study on regulator concepts indicated that a single-stage regulator with a lever arm between the valve and the actuator section would offer significant weight savings. Damping concepts were tested to determine the amount of damping required to restrict actuator travel during vibration. Component design parameters such as spring rates, effective area, contamination cutting, and damping were determined by test prior to regulator final assembly. The unit was subjected to performance testing at widely ranging flow rates, temperatures, inlet pressures, and random vibration levels. A test plan for propellant compatibility and extended life tests is included

Arkansas Small-Grain Cultivar Performance Tests 2004-2005

Small-grain cultivar performance tests are conducted each year in Arkansas by the Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and/or marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for smallgrain producers

Maquiladoras and market mamas

"This study analyzes work, childcare arrangements, and earnings of mothers in the poor neighborhoods of Guatemala City and Greater Accra, Ghana, two urban areas where formal- and informal-sector work differ in importance. Unlike previous studies on childcare that take mother's work status as given, this paper treats childcare choice and labor force participation of women as joint decisions. Our empirical results indicate that participation in the labor market and use of formal day care are, in fact, jointly determined. In both Guatemala and Accra, life cycle and household demographic factors, notably child age, appear to have important effects on both decisions. In both cities, higher household wealth reduces the mothers' chances of working, presumably via an income effect. Controlling for endogeneity of labor market participation and formal day-care use, in Guatemala, day-care prices do not have significant impacts on earnings; neither does the number of day-care centers within a 10-minute walk affect earnings in Accra. In Guatemala, maternal education is an important determinant of utilization of formal day care, but does not have large effects on whether she works for pay or not. In contrast, in Accra, maternal education does not affect either the demand for formal care or the decision to work. In Guatemala, greater travel time from home to the day-care center reduces utilization of this type of care, but a larger supply of day-care centers in the community does not affect use of formal care in Accra. The lack of importance of formal day-care supply variables in Accra compared to the effect of some variables such as travel time to day-care centers in Guatemala suggests that provision of formal day care may not be as critical an intervention to increase mothers' labor force participation rates in cities where the informal sector dominates, such as in Accra. In more urbanized settings like Guatemala City, where the formal sector generates a higher proportion of jobs for women, formal day care is more important to mothers' decision to work." Author's AbstractRural poor ,

Maquiladoras and market mamas

"This study analyzes work, childcare arrangements, and earnings of mothers in the poor neighborhoods of Guatemala City and Greater Accra, Ghana, two urban areas where formal- and informal-sector work differ in importance. Unlike previous studies on childcare that take mother's work status as given, this paper treats childcare choice and labor force participation of women as joint decisions. Our empirical results indicate that participation in the labor market and use of formal day care are, in fact, jointly determined. In both Guatemala and Accra, life cycle and household demographic factors, notably child age, appear to have important effects on both decisions. In both cities, higher household wealth reduces the mothers' chances of working, presumably via an income effect. Controlling for endogeneity of labor market participation and formal day-care use, in Guatemala, day-care prices do not have significant impacts on earnings; neither does the number of day-care centers within a 10-minute walk affect earnings in Accra. In Guatemala, maternal education is an important determinant of utilization of formal day care, but does not have large effects on whether she works for pay or not. In contrast, in Accra, maternal education does not affect either the demand for formal care or the decision to work. In Guatemala, greater travel time from home to the day-care center reduces utilization of this type of care, but a larger supply of day-care centers in the community does not affect use of formal care in Accra. The lack of importance of formal day-care supply variables in Accra compared to the effect of some variables such as travel time to day-care centers in Guatemala suggests that provision of formal day care may not be as critical an intervention to increase mothers' labor force participation rates in cities where the informal sector dominates, such as in Accra. In more urbanized settings like Guatemala City, where the formal sector generates a higher proportion of jobs for women, formal day care is more important to mothers' decision to work." Author's AbstractRural poor ,

The FDM demodulating characteristics of non-linear phase-locked loops

FDM demodulation characteristics of nonlinear phase locked loop

Operations planning simulation model extension study. Volume 5: Mariner Jupiter orbiter PL-12-A automated payload (upper stage used)

For abstract, see N75-20432