Rapid Design of Gravity Assist Trajectories

Several International Solar Terrestrial Physics (ISTP) missions require the design of complex gravity assisted trajectories in order to investigate the interaction of the solar wind with the Earth's magnetic field. These trajectories present a formidable trajectory design and optimization problem. The philosophy and methodology that enable an analyst to design and analyse such trajectories are discussed. The so called 'floating end point' targeting, which allows the inherently nonlinear multiple body problem to be solved with simple linear techniques, is described. The combination of floating end point targeting with analytic approximations with a Newton method targeter to achieve trajectory design goals quickly, even for the very sensitive double lunar swingby trajectories used by the ISTP missions, is demonstrated. A multiconic orbit integration scheme allows fast and accurate orbit propagation. A prototype software tool, Swingby, built for trajectory design and launch window analysis, is described

A Love of Excellence

This is an address delivered by Harry L. Carrico, Chief Justice of the Virginia Supreme Court, at the T. C. Williams School of Law annual banquet honoring merit scholarship sponsors and recipients. At this banquet, Dean Joseph D. Harbaughpresented Justice Carricowith a plaque honoringhim for his unique and extensive contributions both to the legal profession in Virginia and to the T. C. Williams Law School

Impact for Agents

Impact for agents. Most of the agent research community has been predicting greater impact for years and many of us have been working to help the process along. Yet the tremendous growth on the research front has not been met with

In Memoriam: The Honorable Leroy Rountree Hassell, Sr.

Leroy Rountree Hassell, Sr. passed away on February 9, 2011. News of his death devastated those of us associated with him onthe Supreme Court of Virginia. We had lost a dear friend, one always conscious of the needs of his associates and anxious about making sure they were comfortable. Even more, the court lost its peerless leader, and the people of the Commonwealth of Virginialost a dedicated public servant. He will be sorely missed in allcorners of our great state

A designed phenylalanyl-tRNA synthetase variant allows efficient in vivo incorporation of aryl ketone functionality into proteins

Incorporation of non-natural amino acids into proteins in vivo expands the scope of protein synthesis and design. p-Acetylphenylalanine was incorporated into recombinant dihydrofolate reductase (DHFR) in Escherichia coli via a computationally designed mutant form of the phenylalanyl-tRNA synthetase of the host. DHFR outfitted with ketone functionality can be chemoselectively ligated with hydrazide reagents under mild conditions

Reasons for vaccine declination in healthy individuals attending an international vaccine and travel clinic

Little is known about the vaccine-related health behaviors of healthy individuals. We surveyed healthy individuals attending a vaccine center to define the reasons behind vaccine declination when the vaccine is warranted under current guidance. Declination due to perceived risks of the vaccines were by far the most common rationale, suggesting continued need for public health educational campaigns

The impact of the implementation of the African Continental Free Trade Area (AfCFTA) on virtual water trade flows

Through the network of international trade in agricultural goods, water resources are virtually transferred from the country of production to the country of consumption. The volume of agricultural products traded on the global market, and the water embedded in them, has grown rapidly, marking the importance of food security and (other) issues related to this trade in goods. Introduced in 2019, the African Continental Free Trade Area (AfCFTA) is expected to increase trade within the African continent, improving its capacity to ensure food and nutrition security. This project aims to study the effects of AfCFTA implementation on virtual water trade involving the African continent, using the MAGNET computable general equilibrium (CGE) model. We calibrate the baseline with the virtual water trade matrices developed within the CWASI project, and then develop an AfCFTA scenario under the assumption of continent-wide tariff liberalization as well as other complementary measures, including investment in interregional infrastructure. The following paper reports on the first phase of our project: the study of virtual water flow trends both on a global scale and in detail for the state of Burkina Faso and West Africa, as a region subject to strong water-related climate events. Historical trends in Burkina Faso's virtual water fluxes reveal a significant increase in water exchanged through primary agricultural products. However, this increase is not due to an increased demand for water by crops but is the result of an intensification of the trade network over time and an increase in the quantities of products traded

Social Constructivism in Learning: Peer Teaching & Learning

Social constructivism is an educational theory that can be applied in collaborative ways to facilitate student peer teaching and learning. University faculty may be unfamiliar with how to plan, structure, and instruct students in peer teaching and learning projects while providing an emotionally supportive environment. This article will identify characteristics of course activities that promote peer teaching and learning. Two student examples of a three-component peer teaching module will be highlighted along with the grading rubric. This article also describes an assignment module that was offered in a face-to-face second-year course in a professional allied health program. These assignment guidelines could also be utilized in general education courses and upper level courses in various colleges within the university. The peer teaching and learning model could also encourage student engagement in online synchronous or asynchronous learning