Operations analysis (study 2.1). Volume 1: Executive summary

Subjects related to future STS operations concepts were investigated. The majority of effort was directed at assessing the benefits of automated space servicing concepts as related to improvements in payload procurement and shuttle utilization. Another subject was directed at understanding shuttle upper stage software development and recurring costs relative to total program projections. Space serving of automated payloads is addressed by examining the broad spectrum of payload applications with the belief that shared logistic operations will be a major contributor to reduction of future program costs. However, there are certain requirements for support of payload operations, such as availability of the payload, that may place demands upon the shuttle fleet. Because future projections of the NASA Mission Model are only representative of the payload traffic, it is important to recognize that it is the general character of operations that is significant rather than service to any single payload program

TNT equivalency study for space shuttle (EOS). Volume 1: Management summary report

The existing TNT equivalency criterion for LO2/LH2 propellant is reevaluated. It addresses the static, on-pad phase of the space shuttle launch operations and was performed to determine whether the use of a TNT equivalency criterion lower than that presently used (60%) could be substantiated. The large quantity of propellant on-board the space shuttle, 4 million pounds, was considered of prime importance to the study. A qualitative failure analysis of the space shuttle (EOS) on the launch pad was made because it was concluded that available test data on the explosive yield of LO2/LH2 propellant was insufficient to support a reduction in the present TNT equivalency value, considering the large quantity of propellant used in the space shuttle. The failure analysis had two objectives. The first was to determine whether a failure resulting in the total release of propellant could occur. The second was to determine whether, if such a failure did occur, ignition could be delayed long enough to allow the degree of propellant mixing required to produce an explosion of 60% TNT equivalency since the explosive yield of this propellant is directly related to the quantities of LH2 and LO2 mixed at the time of the explosion

Welfare to Work in the U.S.: A Model for Other Nations?

The 1996 welfare reform legislation establishing the Temporary Assistance for Needy Families (TANF) program marks a significant change in U.S. social and economic policy. This legislation represents the ascendance of the view that individuals and families need to be self-reliant and that collective support for individual well-being should be minimized. We first describe the major provisions of TANF, providing some background on its differences from prior policy targeted at needy families. Then we catalogue the wide variety of economic changes that are implicit in the new law, stressing those related to changed property rights, fiscal relations among jurisdictions, and economic incentives facing families. Third, we illustrate the form of state reforms that are likely to develop in response to the federal policy change by describing the actions of the state of Wisconsin, which has taken the lead in implementing the new policy. We conclude with a list of yet unanswered questions that will ultimately determine just how far this policy change will slide the nation along the efficiency-equity tradeoff function, away from the equity axis. The answer to these questions will influence the attraction the U.S. reform might hold as a model for other nations concerned with their own safety net programs for poor people.

Inter-image matching

Interimage matching is the process of determining the geometric transformation required to conform spatially one image to another. In principle, the parameters of that transformation are varied until some measure of some difference between the two images is minimized or some measure of sameness (e.g., cross-correlation) is maximized. The number of such parameters to vary is faily large (six for merely an affine transformation), and it is customary to attempt an a priori transformation reducing the complexity of the residual transformation or subdivide the image into small enough match zones (control points or patches) that a simple transformation (e.g., pure translation) is applicable, yet large enough to facilitate matching. In the latter case, a complex mapping function is fit to the results (e.g., translation offsets) in all the patches. The methods reviewed have all chosen one or both of the above options, ranging from a priori along-line correction for line-dependent effects (the high-frequency correction) to a full sensor-to-geobase transformation with subsequent subdivision into a grid of match points

The detectability of eccentric binary pulsars

Studies of binary pulsars provide insight into various theories of physics. Detection of such systems is challenging due to the Doppler modulation of the pulsed signal caused by the orbital motion of the pulsar. We investigated the loss of sensitivity in eccentric binary systems for different types of companions. This reduction of sensitivity should be considered in future population synthesis models for binary pulsars. This loss can be recovered partially by employing the `acceleration search' algorithm and even better by using the `acceleration-jerk search' algorithm.Comment: 2 pages. To appear in the proceeding of "The Metrewavelength Sky Conference" held at NCRA-TIFR, Pune, from December 9-13 2013, to mark 50 years of radio astronomy research at the Tata Institute of Fundamental Research (TIFR), as well as 10 years of operation of the Giant Metrewave Radio Telescope (GMRT) as an international observator

Compensating Wage Differentials and the Duration of Wage Loss

Several reasons are offered why workers will receive larger compensating wage differentials for increases in the duration of wage losses than for increases in the probability of loss that produce the same expected loss. A formal model of occupational choice is developed that shows the extent to which the compensation for increased duration exceeds that for increased risk. Using Panel Study of Income Dynamics data linked to industry data on injuries and unemployment, we find:1) Nearly all the compensating wage differential for losses due to workplace injuries is compensation for increases in the duration of loss; 2) Similarly, nearly all the compensation for losses due to cyclical unemployment is compensation for increases in duration, especially for increases in duration beyond the 26 weeks of unemployment that are usually compensated by unemployment insurance. The compensating differentials for risk of injury are larger for union than for nonunion workers, while those for cyclical unemployment are smaller for union workers.

The Intergenerational Effects of Early Childbearing

Since World War II, the average age at which women experience their first birth has drifted up, but since 1986 there has been a resurgence of births to teenagers. Just as early fertility appears to adversely affect the life chances of the teen mother, it may also have negative effects on her children. We hypothesize that when the children of teen mothers are young adults, they will tend to have lower education, and will be more likely to be economically inactive, to have children when they are teens, and to have children out of wedlock when they are teens. In this paper, we present several models designed to reveal the impact that being born to a teenage mother has on children's chances for success as young adults. Our findings indicate that the children of mothers who first gave birth as teens are adversely affected as young adults.