175 research outputs found

    A Medieval Boom in the North-west Sahara: Evolving Oasis Landscapes in the Wadi Draa, Morocco (c.700–1500 AD)

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    Modern scholarship on the medieval Sahara has focused on a handful of famous entrepît sites that have their origins in the 8th century or later, and as a result we still understand very poorly the nature and extent of Saharan oasis settlement and agriculture in the golden age of Saharan trade. This article presents the first securely dated chronology for oasis development in the north-west Sahara based on three seasons of archaeological survey and a comprehensive radiocarbon dating programme in the Wadi Draa, Morocco. The Draa Valley contains some of the largest, most populous and most productive oases in the Sahara, as well as serving as an important travel corridor for trading caravans coming from West Africa to access the Atlas passes and reach Marrakech. Focusing on evidence from a large zone of abandoned oases on the Kasr Bounou Plain, this article demonstrates that while oasis agriculture and settlement was taking place between the 4th–8th centuries—well before the Muslim conquest of Morocco—there was a significant increase in settlement and agricultural exploitation from the 9th century. This phenomenon is marked by the appearance of substantial mudbrick settlements, along with irrigation and field systems, and is coterminous with the development of the medieval trading entrepît of Sijilmasa. A settlement boom and significant investment in irrigated oasis agriculture occurred between the 11th and 13th centuries, contemporary with Almoravid and Almohad rule of the Draa, followed by a retraction and abandonment of much of the oasis by the 16th century. The new evidence from the Draa challenges the long-held belief that sedentarization and irrigated oasis agriculture were unique to the medieval period in the north-west Sahara

    Generationing development

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    The articles in this special issue present a persuasive case for accounts of development to recognise the integral and fundamental roles played by age and generation. While the past two decades have witnessed a burgeoning of literature demonstrating that children and youth are impacted by development, and that they can and do participate in development, the literature has tended to portray young people as a special group whose perspectives should not be forgotten. By contrast, the articles collected here make the case that age and generation, as relational constructs, cannot be ignored. Appropriating the term ‘generationing’, the editors argue that a variety of types of age relations profoundly structure the ways in which societies are transformed through development – both immanent processes of neoliberal modernisation and the interventions of development agencies that both respond and contribute to these. Drawing on the seven empirical articles, I attempt to draw some of the ideas together into a narrative that further argues the case for ‘generationing’ but also identifies gaps, questions and implications for further research

    Plastisol Foaming Process. Decomposition of the Foaming Agent, Polymer Behavior in the Corresponding Temperature Range and Resulting Foam Properties

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    The decomposition of azodicarbonamide, used as foaming agent in PVC - plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min-1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g -1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol-1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse

    Acupuncture, Counseling, and Usual care for Depression (ACUDep): study protocol for a randomized controlled trial

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    Background: The evidence on the effect of acupuncture or counseling for depression is not conclusive yet is sufficient to warrant further research. Our aim is to conduct a full-scale RCT to determine the clinical and cost effectiveness of acupuncture and counseling compared to usual care alone. We will explore the experiences and perspectives of patients and practitioners. Methods/Design: Randomized controlled trial with three parallel arms: acupuncture plus usual care, counseling plus usual care, and usual care alone, in conjunction with a nested qualitative study using in-depth interviews with purposive samples of trial participants. Participants: Patients aged over 18 years diagnosed with depression or mood disorder by their GP and with a score of 20 or above on the Beck Depression Inventory (BDI-II). Randomization: Computer randomization by York Trials Unit to acupuncture, counseling, and usual care alone in proportions of 2:2:1, respectively, with secure allocation concealment. Interventions: Patients allocated to acupuncture and counseling groups receive the offer of up to 12 weekly sessions. Both interventions allow flexibility to address patient variation, yet are constrained within defined protocols. Acupuncture is based on traditional Chinese medicine and counseling is non-directive within the humanistic tradition. Outcome: The PHQ-9 is the primary outcome measure, collected at baseline, 3, 6, 9, and 12 months. Also measured is BDI-II, SF-36 Bodily pain subscale, and EQ-5D. Texted mood scores are collected weekly over the first 15 weeks. Health-related resource use is collected over 12 months. Analysis: The sample size target was for 640 participants, calculated for an effect size of 0.32 on the PHQ-9 when comparing acupuncture with counseling given 90% power, 5% significance, and 20% loss to follow-up. Analysis of covariance will be used on an intention-to-treat basis. Thematic analysis will be used for qualitative data. We will compare incremental cost-effectiveness of the three treatment options at 12 months. Discussion: Ethical approval was obtained in October 2009. There were six subsequent protocol amendments, the last of which was approved in January 2012. Recruitment of 755 participants took place over 18 months. Data collection will be completed by June 2012. No interim analyses have been conducted

    Alternative patterns of sex chromosome differentiation in Aedes aegypti (L).

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    BACKGROUND: Some populations of West African Aedes aegypti, the dengue and zika vector, are reproductively incompatible; our earlier study showed that divergence and rearrangements of genes on chromosome 1, which bears the sex locus (M), may be involved. We also previously described a proposed cryptic subspecies SenAae (PK10, Senegal) that had many more high inter-sex FST genes on chromosome 1 than did Ae.aegypti aegypti (Aaa, Pai Lom, Thailand). The current work more thoroughly explores the significance of those findings. RESULTS: Intersex standardized variance (FST) of single nucleotide polymorphisms (SNPs) was characterized from genomic exome capture libraries of both sexes in representative natural populations of Aaa and SenAae. Our goal was to identify SNPs that varied in frequency between males and females, and most were expected to occur on chromosome 1. Use of the assembled AaegL4 reference alleviated the previous problem of unmapped genes. Because the M locus gene nix was not captured and not present in AaegL4, the male-determining locus, per se, was not explored. Sex-associated genes were those with FST values ≄ 0.100 and/or with increased expected heterozygosity (H exp , one-sided T-test, p < 0.05) in males. There were 85 genes common to both collections with high inter-sex FST values; all genes but one were located on chromosome 1. Aaa showed the expected cluster of high inter-sex FST genes proximal to the M locus, whereas SenAae had inter-sex FST genes along the length of chromosome 1. In addition, the Aaa M-locus proximal region showed increased H exp levels in males, whereas SenAae did not. In SenAae, chromosomal rearrangements and subsequent suppressed recombination may have accelerated X-Y differentiation. CONCLUSIONS: The evidence presented here is consistent with differential evolution of proto-Y chromosomes in Aaa and SenAae

    Malaria vector research and control in Haiti: a systematic review

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    BACKGROUND: Haiti has a set a target of eliminating malaria by 2020. However, information on malaria vector research in Haiti is not well known. This paper presents results from a systematic review of the literature on malaria vector research, bionomics and control in Haiti. METHODS: A systematic search of literature published in French, Spanish and English languages was conducted in 2015 using Pubmed (MEDLINE), Google Scholar, EMBASE, JSTOR WHOLIS and Web of Science databases as well other grey literature sources such as USAID, and PAHO. The following search terms were used: malaria, Haiti, Anopheles, and vector control. RESULTS: A total of 132 references were identified with 40 high quality references deemed relevant and included in this review. Six references dealt with mosquito distribution, seven with larval mosquito ecology, 16 with adult mosquito ecology, three with entomological indicators of malaria transmission, eight with insecticide resistance, one with sero-epidemiology and 16 with vector control. In the last 15 years (2000–2015), there have only been four published papers and three-scientific meeting abstracts on entomology for malaria in Haiti. Overall, the general literature on malaria vector research in Haiti is limited and dated. DISCUSSION: Entomological information generated from past studies in Haiti will contribute to the development of strategies to achieve malaria elimination on Hispaniola. However it is of paramount importance that malaria vector research in Haiti is updated to inform decision-making for vector control strategies in support of malaria elimination
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