On the use of approximate analytical solutions in solving optimum trajectory problems

Method for numerical solutions of nonlinear optimum trajectory problems using approximate analytic metho

Applying integrals of motion to the numerical solution of differential equations

A method is developed for using the integrals of systems of nonlinear, ordinary differential equations in a numerical integration process to control the local errors in these integrals and reduce the global errors of the solution. The method is general and can be applied to either scaler or vector integrals. A number of example problems, with accompanying numerical results, are used to verify the analysis and support the conjecture of global error reduction

Development of a method for optimal maneuver analysis of complex space missions

A system that allows mission planners to find optimal multiple-burn space trajectories easily is described. Previously developed methods with different gravity assumptions perform the optimization function. The power of these programs is extended by a method of costate estimation. A penalty function method of constraining coast arc times to be positive is included. The capability of the method is demonstrated by finding the optimal control for three different space missions. These include a shuttle abort-once-around mission and two- and three-burn geosynchronous satellite-placement missions

Duality properties of Gorringe-Leach equations

In the category of motions preserving the angular momentum's direction, Gorringe and Leach exhibited two classes of differential equations having elliptical orbits. After enlarging slightly these classes, we show that they are related by a duality correspondence of the Arnold-Vassiliev type. The specific associated conserved quantities (Laplace-Runge-Lenz vector and Fradkin-Jauch-Hill tensor) are then dual reflections one of the othe

Primer vector theory and applications

A method developed to compute two-body, optimal, N-impulse trajectories was presented. The necessary conditions established define the gradient structure of the primer vector and its derivative for any set of boundary conditions and any number of impulses. Inequality constraints, a conjugate gradient iterator technique, and the use of a penalty function were also discussed

The MSX1 allele 4 homozygous child exposed to smoking at periconception is most sensitive in developing nonsyndromic orofacial clefts

Nonsyndromic orofacial clefts (OFC) are common birth defects caused by certain genes interacting with environmental factors. Mutations and association studies indicate that the homeobox gene MSX1 plays a role in human clefting. In a Dutch case-control triad study (mother, father, and child), we investigated interactions between MSX1 and the parents' periconceptional lifestyle in relation to the risk of OFC in their offspring. We s

Targeting host glycolysis as a strategy for antimalarial development

Glycolysis controls cellular energy, redox balance, and biosynthesis. Antiglycolytic therapies are under investigation for treatment of obesity, cancer, aging, autoimmunity, and microbial diseases. Interrupting glycolysis is highly valued as a therapeutic strategy, because glycolytic disruption is generally tolerated in mammals. Unfortunately, anemia is a known dose-limiting side effect of these inhibitors and presents a major caveat to development of antiglycolytic therapies. We developed specific inhibitors of enolase - a critical enzyme in glycolysis - and validated their metabolic and cellular effects on human erythrocytes. Enolase inhibition increases erythrocyte susceptibility to oxidative damage and induces rapid and premature erythrocyte senescence, rather than direct hemolysis. We apply our model of red cell toxicity to address questions regarding erythrocyte glycolytic disruption in the context o

Conducting Health Research in Korean American Churches: Perspectives from Church Leaders

Korean Americans experience many challenges to obtaining adequate health care coverage and access to needed services. Because a large proportion of Korean Americans attend churches on a regular basis, churches may be a promising venue where health programs can be delivered. In order to gain an in-depth understanding of Korean American churches with respect to conducting future health intervention research, we conducted exploratory interviews and focus groups with 58 leaders from 23 Korean American churches and three community organizations. From these interviews and focus groups, we found that Korean churches and church leaders seek to meet a variety of social and health needs of their congregation and their surrounding community. Several leaders have stated that assisting with social and medical needs of their members is an important component of their current ministry. They described profound health needs of their congregations and have suggested various ways in which the university can partner with the local churches to help address these needs through research. Additionally, they described various resources churches can provide to researchers such as: their personal assistance, church volunteer base, church facility, and church network and contacts. Our findings suggest that Korean churches have a high potential to serve an important role in the health of Korean Americans. On the basis of the promising results of the present study, we are planning to conduct a cross sectional survey of Korean church leaders and members in Los Angeles County to substantiate our findings in a larger representative sample