Study of ballistic mode comet Encke mission opportunities

An analysis was conducted of the space mission to intercept the comet Encke. The two basic types of flight geometry considered for the mission are described. The primary interactions between time-of-flight and performance characteristics are displayed. The representative spacecraft characteristics for the Titan 3/Centaur launch vehicle are tabulated. The navigation analyses for the two missions are developed to show: (1) assessment of the navigation feasibility of the missions, (2) determination of the total velocity budget for the trim maneuvers, and (3) evaluation of dispersions at comet encounter

Dislocated Worker Human Capital Depreciation and Recovery

Previous studies have estimated the human capital depreciation of women re-entering the work force after voluntary, lengthy interruptions. Those studies have found reduced real wages and furthermore the decrease is positively related to the length of the interruption. Upon re-entry, however, real wages grow rapidly as human capital is restored. This paper develops a model of the wage histories of dislocated workers. Similar to labor force re-entrants, those dislocated workers who become re-employed would experience wages below their final wage prior to dislocation and the decrease should be associated with the length of dislocation. However, the model suggests that since the career disruptions are involuntary and since occupational shifts generally occur, recovery will not be rapid nor complete. The model is estimated with data from a sample of workers in Ohio who had been dislocated and received services under Title III of the Job Training Partnership Act (JTPA). This data set has the limitation that the observations are for workers who chose to receive services, but it also has the advantage that the effects of a variety of training interventions on outcomes can be determined

Axon Outgrowth: Motor Protein Moonlights in Microtubule Sliding

SummaryNeurons develop from small, spherical precursors into the largest, most asymmetric of all metazoan cells by extending thin axonal processes over enormous distances. Although the forces for this extension have been unclear, recent work shows that the initial axonal extension may involve an unexpected mechanism: sliding of microtubules, driven by a motor protein previously thought to be deployed only in organelle transport