Ancient DNA and deep population structure in sub-Saharan African foragers

Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa(1-4). Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations(3,5). Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80-20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch. DNA analysis of 6 individuals from eastern and south-central Africa spanning the past approximately 18,000 years, and of 28 previously published ancient individuals, provides genetic evidence supporting hypotheses of increasing regionalization at the end of the Pleistocene.info:eu-repo/semantics/publishedVersio

Technical efficiency of goat farming in Turkey: a case study of Isparta province

ABSTRACT This study estimates the technical efficiency of goat rearing in the province of Isparta in Turkey using Data Envelopment Analysis (DEA). The data used were collected from 92 goat farmers using the stratified sampling method by means of a questionnaire. The technical efficiency of the goat farming varied widely between 0.13 and 1.00. The mean efficiency of 92 goat farms was calculated to be 0.44 and 0.66 for constant and variable returns to scale assumptions, respectively. The greatest slacks were in feedstuff concentrates and labour used. The most significant factors affecting efficiency of goat production were farmer experience, cooperative membership, milk yield per goat, and family and hired labour. Technical efficiency should be improved by providing farmers with well-organised education, an extension program, and research and development programs on goat rearing

Desvios de custos e prazos em empreendimentos da construção civil: categorização e fatores de influência

Desvios de custos e prazos são desafios recorrentes na construção civil. Neste artigo, os autores objetivaram revisar sistematicamente a literatura relacionada a desvios de prazos e custos para determinar uma estrutura de categorização e respectivos fatores responsáveis por esses desvios. Foi empregada a abordagem Systematic Literature Review (Revisão Sistemática de Literatura - RSL) de maneira metódica, para proporcionar acompanhamento e reprodução futura. Informações relevantes foram extraídas dos artigos selecionados e posteriormente sintetizadas para a obtenção da proposta de categorização e respectivos fatores responsáveis pelos desvios. Nove categorias foram identificadas e definidas com base em seus determinantes: relações governamentais; contratos; organização; gerenciamento; financiamento; projeto e documentação; alterações de escopo; aspectos ambientais e econômicos; e atividades e equipamentos. Além disso, 95 fatores de influência foram identificados e anexados às categorias pertinentes. Apesar de a literatura ser heterogênea em relação a contextos e regiões globais, o que dificulta a condução da RSL, houve boa sustentação para os fatores identificados. Escassez de evidências foram identificadas na América Latina, particularmente no Brasil. A literatura existente em desvios de prazos e custos até o momento se mostrou multifacetada, com 92 artigos publicados em 46 fontes diferentes no intervalo de tempo de 1985 a 2014. A maioria das pesquisas teve como foco o estudo de alguns desses fatores em particular, enquanto esta pesquisa classificou-os e sintetizou-os de forma a possibilitar uma visão nova e mais abrangente sobre o fenômeno

Policy evaluation and efficiency: a systematic literature review

This paper provides a systematic literature review of studies investigating the effect of an intervention on the efficiency of a decision-making unit, when efficiency is computed using nonparametric frontier approaches. This paper offers a guide for future research by identifying patterns in (1) the fields of application, (2) applied efficiency models, and (3) analysis of efficiency determinants. Our findings indicate that, despite the prominent role of frontier techniques in the analysis of public sector performances and the importance of the effectiveness and the policy perspective, these two approaches have long been kept separate. Nevertheless, the combination of efficiency and effectiveness is fundamental to evaluate public interventions and to detect inefficiencies at the policy level, especially in key sectors such as education, health, and environment