Advanced technologies for Mission Control Centers

Advance technologies for Mission Control Centers are presented in the form of the viewgraphs. The following subject areas are covered: technology needs; current technology efforts at GSFC (human-machine interface development, object oriented software development, expert systems, knowledge-based software engineering environments, and high performance VLSI telemetry systems); and test beds

Why is Polygyny More Prevalent in Western Africa?: An African Slave Trade Perspective

Polygyny rates are higher in Western Africa than in Eastern Africa. The African slave trades explain this difference. More male slaves were exported in the trans-Atlantic slave trades from Western Africa, while more female slaves were exported in the Indian Ocean and Red Sea slave trades from Eastern Africa. The slave trades led to prolonged periods of abnormal sex ratios, which impacted the rates of polygyny across Africa. In order to assess these claims, we construct a unique ethnicity-level data set linking current rates of polygyny with historical trade flow data from the African slave trades. Our OLS estimates show a positive correlation between the trans-Atlantic slave trades and polygyny. An IV approach shows the relationship is causal and statistically signicant. We also provide cross-country evidence corroborating our findings.slave trades; polygyny; Africa; development

The New Goods Margin in Japanese-Chinese Trade *

Abstract This paper uses the methodology developed i

Development of a Low Tech Assistive Technology Kit

This project’s goal was to develop and implement a low-tech assistive technology kit in collaboration with the Seven Hills Foundation. The kit will be used to assemble AT solutions to help these individuals achieve independence. We conducted site assessments and assembled solutions with the staff and participants of Seven Hills. Ultimately, we found that our kit will not be beneficial to all participants due to the variation of disabilities between each individual and will need to be personalized

Operational Status of the International Space Station Plasma Contactor Hollow Cathode Assemblies July 2001 to May 2013

The International Space Station has onboard two Aerojet Rocketdyne developed plasma contactor units that perform the function of charge control. The plasma contactor units contain NASA Glenn Research Center developed hollow cathode assemblies. NASA Glenn Research Center monitors the on-orbit operation of the flight hollow cathode assemblies. As of May 31, 2013, HCA.001-F has been ignited and operated 123 times and has accumulated 8072 hours of operation, whereas, HCA.003-F has been ignited and operated 112 times and has accumulated 9664 hours of operation. Monitored hollow cathode ignition times and anode voltage magnitudes indicate that they continue to operate nominally

Operational Status of the International Space Station Plasma Contactor Hollow Cathode Assemblies from July 2011 to May 2013

The International Space Station has onboard two Aerojet Rocketdyne developed plasma contactor units that perform the function of charge control. The plasma contactor units contain NASA Glenn Research Center developed hollow cathode assemblies. NASA Glenn Research Center monitors the onorbit operation of the flight hollow cathode assemblies. As of May 31, 2013, HCA.001-F has been ignited and operated 123 times and has accumulated 8072 hours of operation, whereas, HCA.003-F has been ignited and operated 112 times and has accumulated 9664 hours of operation. Monitored hollow cathode ignition times and anode voltage magnitudes indicate that they continue to operate nominally

Being Bad by Being Good: Owner and Captain Value-Added in the Slave Trade *

Abstract We use slave voyage data from 18th century Great Britain and France to answer two questions: 1) How important was the managerial quality of owners and captains in slave trading? and 2) What explains the substantial variation in managerial quality? Utilizing the Trans-Atlantic Slave Trade Database, in which we observe the performance of owners and captains in each of their voyages, we estimate the value-added of owners and captains to slave voyage output, i.e. the number of slaves arriving in the Americas. Several results emerge. First, if we replace all owners with the 90th percentile owner in the country, slave voyage output would be 16% and 21% higher than if we replaced all owners with the 10th percentile owner in Great Britain and in France. This 90/10 ratio is 1.22 for British captains. If we replace all owners with their country's 90th percentile owner, approximately 217,000 more slaves would have been exported over the course of the 18th century. Likewise, if all British captains were replaced with the 90th percentile captain, approximately 211,000 more slaves would have been exported. Second, owner value-added is negatively associated with family businesses and positively associated with the level of competition. A comparison of owner value-added before and after the unexpected outbreak of the Seven Years' War, which historians suggest decreased (increased) competition in the French (British) slave trade, suggests competition's effect on owner value-added might be causal. JEL Classification: N73, N77, F1

Why is Polygyny More Prevalent in Western Africa?: An African Slave Trade Perspective

Polygyny rates are higher in Western Africa than in Eastern Africa. The African slave trades explain this difference. More male slaves were exported in the trans-Atlantic slave trades from Western Africa, while more female slaves were exported in the Indian Ocean and Red Sea slave trades from Eastern Africa. The slave trades led to prolonged periods of abnormal sex ratios, which impacted the rates of polygyny across Africa. In order to assess these claims, we construct a unique ethnicity-level data set linking current rates of polygyny with historical trade flow data from the African slave trades. Our OLS estimates show a positive correlation between the trans-Atlantic slave trades and polygyny. An IV approach shows the relationship is causal and statistically signicant. We also provide cross-country evidence corroborating our findings

Why is Polygyny More Prevalent in Western Africa?: An African Slave Trade Perspective

Polygyny rates are higher in Western Africa than in Eastern Africa. The African slave trades explain this difference. More male slaves were exported in the trans-Atlantic slave trades from Western Africa, while more female slaves were exported in the Indian Ocean and Red Sea slave trades from Eastern Africa. The slave trades led to prolonged periods of abnormal sex ratios, which impacted the rates of polygyny across Africa. In order to assess these claims, we construct a unique ethnicity-level data set linking current rates of polygyny with historical trade flow data from the African slave trades. Our OLS estimates show a positive correlation between the trans-Atlantic slave trades and polygyny. An IV approach shows the relationship is causal and statistically signicant. We also provide cross-country evidence corroborating our findings

The Slave Trade and Conflict in Africa, 1400-2000

Can the slave trade explain Africa's propensity for conflict? Using variation in slave exports driven by the interaction between foreign demand shocks and heterogeneity in trade costs, we show that the slave trade increased conflict propensities in pre-colonial Africa and that this effect has persisted to the present. Moreover, we find empirical evidence suggesting two related mechanisms for this persistence--natural resources and national institutions. These results "decompress" history by connecting the short-run and long-run effects of the African slave trade