On Optimal Two-Impulse Earth-Moon Transfers in a Four-Body Model

In this paper two-impulse Earth-Moon transfers are treated in the restricted four-body problem with the Sun, the Earth, and the Moon as primaries. The problem is formulated with mathematical means and solved through direct transcription and multiple shooting strategy. Thousands of solutions are found, which make it possible to frame known cases as special points of a more general picture. Families of solutions are defined and characterized, and their features are discussed. The methodology described in this paper is useful to perform trade-off analyses, where many solutions have to be produced and assessed

Drivers of diversification and pluriactivity among smallholder farmers—evidence from Nigeria

Diversification and pluriactivity have become a norm among farm business owners (FBOs) due to persistent low farm income. This study applies the resource-based theory to examine drivers of diversification and livelihood income-oriented towards a sustainable livelihood. Our framework develops hypotheses about the impact of internal and external resources on livelihood choices at the household level. We use a survey of 480 rural Nigerian farmers (agripreneurs), applying a Multivariate Tobit to test our framework. We find that education plays the most significant role in all types of employment options. The more FBOs are educated, the more the likelihood that they will choose non-farm or wage employment. This study revealed that while the agriculture sector’s share of rural employment is declining, non-farm is on the increase. More so, there is a decline in farming among the young generation, marital status bias and gender influence in resource allocation. The socioeconomic (income and food security) and socio-cultural (employment and rural-urban migration) implications of rural sustainability linked to UN Development Goals have been highlighted and analysed in this article

A Flexible Inexact-Restoration Method for Constrained Optimization

We introduce a new flexible inexact-restoration algorithm for constrained optimization problems. in inexact-restoration methods, each iteration has two phases. the first phase aims at improving feasibility and the second phase aims to minimize a suitable objective function. in the second phase, we also impose bounded deterioration of the feasibility, obtained in the first phase. Here, we combine the basic ideas of the Fischer-Friedlander approach for inexact-restoration with the use of approximations of the Lagrange multipliers. We present a new option to obtain a range of search directions in the optimization phase, and we employ the sharp Lagrangian as merit function. Furthermore, we introduce a flexible way to handle sufficient decrease requirements and an efficient way to deal with the penalty parameter. Global convergence of the new inexact-restoration method to KKT points is proved under weak constraint qualifications.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Inst Sci & Technol, Sao Jose Dos Campos, SP, BrazilUniv São Paulo, Inst Math & Stat, Dept Appl Math, São Paulo, SP, BrazilUniv Estadual Campinas, Inst Math Stat & Sci Comp, Dept Appl Math, Campinas, SP, BrazilUniversidade Federal de São Paulo, Inst Sci & Technol, Sao Jose Dos Campos, SP, BrazilCNPq: E-26/171.164/2003 - APQ1FAPESP: 2010/19720-5FAPESP: 2013/05475-7FAPESP: 201307375-0Web of Scienc

NIDA’s Clinical Trials Network: An Opportunity for HIV Research in Community Substance Abuse Treatment Programs

BACKGROUND/OBJECTIVES: HIV continues to be a significant problem among substance users and their sexual partners in the United States. The National Drug Abuse Treatment Clinical Trials Network (CTN) offers a national platform for effectiveness trials of HIV interventions in community substance abuse treatment programs. This article presents the HIV activities of the CTN during its first 10 years. RESULTS: While emphasizing CTN HIV protocols, this article reviews the (1) HIV context for this work; (2) the collaborative process among providers, researchers, and National Institute on Drug Abuse CTN staff, on which CTN HIV work was based; (3) results of CTN HIV protocols and HIV secondary analyses in CTN non-HIV protocols; and (4) implications for future HIV intervention effectiveness research in community substance abuse treatment programs. CONCLUSION/SIGNIFICANCE: While the feasibility of engaging frontline providers in this research is highlighted, the limitations of small to medium effect sizes and weak adoption and sustainability in everyday practice are also discussed