Search for and analysis of radioactive halos in lunar material

The lunar halo search was conducted because halos in terrestrial minerals serve as pointers to localized radioactivity, and make possible analytical studies on the problems of isotopic dating and mode of crystallization of the host mineral. Ancillary studies were conducted on terrestrial halos and on certain samples of special origin such as tektites and meteorites

Haptic dancing: human performance at haptic decoding with a vocabulary

The inspiration for this study is the observation that swing dancing involves coordination of actions between two humans that can be accomplished by pure haptic signaling. This study implements a leader-follower dance to be executed between a human and a PHANToM haptic device. The data demonstrates that the participants' understanding of the motion as a random sequence of known moves informs their following, making this vocabulary-based interaction fundamentally different from closed loop pursuit tracking. This robot leader does not respond to the follower's movement other than to display error from a nominal path. This work is the first step in an investigation of the successful haptic coordination between dancers, which will inform a subsequent design of a truly interactive robot leader

Monitoring and predicting tropical cyclone movement using geosynchronous satellite remote sensing techniques

Data collected on special hurricane days by the VISSR Atmospheric Sounder (VAS) instrument flown on a satellite in 1981 and 1982 were studied for their usefulness in forecasting motion of hurricanes. The retrieved constant pressure heights for the 500-mb surface provided the basis for reasonable forecasts of 24 hour hurricane motion. The conclusions are illustrated with examples from Hurricane Harvey (1981) and Hurricane Irene (1981). Recommendations are made for future use of the VAS type instruments for tropical cyclone forecasting

Human-human haptic collaboration in cyclical Fitts' tasks

Understanding how humans assist each other in haptic interaction teams could lead to improved robotic aids to solo human dextrous manipulation. Inspired by experiments reported in Reed et al. (2004), which suggested two-person haptically interacting teams could achieve a lower movement time (MT) than individuals for discrete aiming movements of specified accuracy, we report that two-person teams (dyads) can also achieve lower MT for cyclical, continuous aiming movements. We propose a model, called endpoint compromise, for how the intended endpoints of both subjects' motion combine during haptic interaction; it predicts a ratio of /spl radic/2 between slopes of MT fits for individuals and dyads. This slope ratio prediction is supported by our data

The Tax Benefits of Not-for-Profit Hospitals

This paper investigates three special tax provisions for not-for-profit (NFP) hospitals. First taxes -- both income and property taxes. Second, they issue tax-exempt bonds so lenders do not pay income taxes on interest received. Third, donors deduct charitable contributions from their income tax bases. The rationale for these policies is that the NFP hospitals provide community benefits, the definition of which is often loosely-specified. The value of capital tax exemptions depends on the capital intensity of NFP hospitals, and for income taxes, the hospitals' profitability. For 1995, the aggregate value of the exemption from income taxes is $4.6 billion; the median hospital receives benefits of 1.8 percent of total assets. For the property tax exemption, we estimate an aggregate value of$1.7 billion. The value of the property tax exemption varies across hospitals depending on state and local tax policies and the hospital asset mix. Tax-exempt bonds and deductible contributions are concentrated among larger hospitals. Only 19.7 percent of NFP hospitals had outstanding tax-exempt debt in 1994. Almost half of existing bond debt could be replaced by using hospital endowments; we calculate an annual aggregate benefit of $354 million from using tax-exempt bonds. For charitable contributions, roughly four percent of hospitals receive 71 percent of the contributions. We estimate that the lost tax revenue from these contributions is$1.1 billion in 1994.

"Success Taxes," Entrepreneurial Entry, and Innovation

Interest in the role of entrepreneurial entry in innovation raises the question of the extent to which tax policy encourages or discourages entry. We find that, while the level of the marginal tax rate has a negative effect in entrepreneurial entry, the progressivity of the tax also discourages entrepreneurship, and significantly so for some groups of households. These effects are principally traceable to the upside' or success' convexity of the household tax schedule. Prospective entrants from a priori innovative industries and occupations are no less affected by the considerations we examine than other prospective entrants. In terms of destination-based industry and occupation measures of innovative entrepreneurs, we find mixed evidence on whether innovative entrepreneurs differ from the general population; the results for entrepreneurs moving to innovative industries suggest that they may be unaffected by tax convexity but the possible endogeneity of this measure of innovative entrepreneurs confounds interpreting this specification. Using education as a measure of potential for innovation, we find that tax convexity discourages entry into self-employment for people of all educational backgrounds. Overall, we find little evidence that the tax effects are focused simply on the employment changes of less skilled or less promising potential entrants.

Monitoring tropical cyclone intensity using wind fields derived from short-interval satellite images

Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere

Longitudinal aerodynamics of a low-wing lift-fan transport including hover characteristics in and out of ground effect

A wind-tunnel investigation was conducted in the Langley V/STOL tunnel to determine the longitudinal aerodynamic characteristics of a six-fan, tip-driven (remote) lift-fan VTOL transport throughout transition. The large midspan lift-fan pods and cruise fans were removed to determine their influence on the stability and control of the configuration. Data were obtained in the hovering mode for ranges of model height above ground. The data are presented without analysis or discussion

The role of the equivalent blackbody temperature in the study of Atlantic Ocean tropical cyclones

Satellite measured equivalent blackbody temperatures of Atlantic Ocean tropical cyclones are used to investigate their role in describing the convection and cloud patterns of the storms and in predicting wind intensity. The high temporal resolution of the equivalent blackbody temperature measurements afforded with the geosynchronous satellite provided sequential quantitative measurements of the tropical cyclone which reveal a diurnal pattern of convection at the inner core during the early developmental stage; a diurnal pattern of cloudiness in the storm's outer circulation throughout the life cycle; a semidiurnal pattern of cloudiness in the environmental atmosphere surrounding the storms during the weak storm stage; an outward modulating atmospheric wave originating at the inner core; and long term convective bursts at the inner core prior to wind intensification