715 research outputs found

    The contexts and early Acheulean archaeology of the EF-HR paleo-landscape (Olduvai Gorge, Tanzania).

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    Renewed fieldwork at the early Acheulean site of EF-HR (Olduvai Gorge, Tanzania) has included detailed stratigraphic studies of the sequence, extended excavations in the main site, and has placed eleven additional trenches within an area of nearly 1 km2, to sample the same stratigraphic interval as in the main trench across the broader paleo-landscape. Our new stratigraphic work suggests that EF-HR is positioned higher in the Bed II sequence than previously proposed, which has implications for the age of the site and its stratigraphic correlation to other Olduvai Middle Bed II sites. Geological research shows that the main EF-HR site was situated at the deepest part of an incised valley formed through river erosion. Archaeological excavations at the main site and nearby trenches have unearthed a large new assemblage, with more than 3000 fossils and artefacts, including a hundred handaxes in stratigraphic position. In addition, our test-trenching approach has detected conspicuous differences in the density of artefacts across the landscape, with a large cluster of archaeological material in and around the main trench, and less intense human activity at the same level in the more distant satellite trenches. All of these aspects are discussed in this paper in the light of site formation processes, behavioral contexts, and their implications for our understanding of the early Acheulean at Olduvai Gorge

    Macrofossils and pollen representing forests of the pre-Taupo volcanic eruption (c. 1850 yr BP) era at Pureora and Benneydale, central North Island, New Zealand.

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    Micro- and macrofossil data from the remains of forests overwhelmed and buried at Pureora and Benneydale during the Taupo eruption (c. 1850 conventional radiocarbon yr BP) were compared. Classification of relative abundance data separated the techniques, rather than the locations, because the two primary clusters comprised pollen and litter/wood. This indicates that the pollen:litter/wood within-site comparisons (Pureora and Benneydale are 20 km apart) are not reliable. Plant macrofossils represented mainly local vegetation, while pollen assemblages represented a combination of local and regional vegetation. However, using ranked abundance and presence/absence data, both macrofossils and pollen at Pureora and Benneydale indicated conifer/broadleaved forest, of similar forest type and species composition at each site. This suggests that the forests destroyed by the eruption were typical of mid-altitude west Taupo forests, and that either data set (pollen or macrofossils) would have been adequate for regional forest interpretation. The representation of c. 1850 yr BP pollen from the known buried forest taxa was generally consistent with trends determined by modern comparisons between pollen and their source vegetation, but with a few exceptions. A pollen profile from between the Mamaku Tephra (c. 7250 yr BP) and the Taupo Ignimbrite indicated that the Benneydale forest had been markedly different in species dominance compared with the forest that was destroyed during the Taupo eruption. These differences probably reflect changes in drainage, and improvements in climate and/or soil fertility over the middle Holocene

    Monitoring the South African National Antiretroviral Treatment Programme, 2003 - 2007: The IeDEA Southern Africa collaboration

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    Objectives. To introduce the combined South African cohortsof the International epidemiologic Databases to EvaluateAIDS Southern Africa (IeDEA-SA) collaboration as reflectingthe South African national antiretroviral treatment (ART)programme; to characterise patients accessing these services;and to describe changes in services and patients from 2003 to2007.Design and setting. Multi-cohort study of 11 ART programmesin Gauteng, Western Cape, Free State and KwaZulu-Natal.Subjects. Adults and children

    Transmission of HIV-1 infection in sub-Saharan Africa and effect of elimination of unsafe injections

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    During the past year, a group has argued that unsafe injections are a major if not the main mode of HIV-1 transmission\ud in sub-Saharan Africa. We review the main arguments used to question the epidemiological interpretations on the lead\ud role of unsafe sex in HIV-1 transmission, and conclude there is no compelling evidence that unsafe injections are a\ud predominant mode of HIV-1 transmission in sub-Saharan Africa. Conversely, though there is a clear need to eliminate\ud all unsafe injections, epidemiological evidence indicates that sexual transmission continues to be by far the major\ud mode of spread of HIV-1 in the region. Increased efforts are needed to reduce sexual transmission of HIV-1

    Socio-Demographic Determinants of Condom Use Among Sexually Active Young Adults in Rural KwaZulu-Natal, South Africa

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    AIM: To investigate patterns, levels and socio-demographic determinants of condom use and consistency of use among young adults aged 15-24 years.BACKGROUND: Condoms are known to prevent HIV infection. However, HIV prevalence and incidence remain high.METHODS: This study was conducted in the Africa Centre Demographic Surveillance Area (ACDSA) in rural KwaZulu-Natal. Analysis focused on resident young adults aged 15-24 years in 2005. In univariable and multivariable analyses, determinants of condom use and consistency of use among 15-24 year olds were estimated using data collected in 2005. 'Ever' condom use was defined as the proportion who reported having used a condom; consistent use among those ever using as "always" using condoms with most recent partner in the last year.RESULTS: 3,914 participants aged 15-24 years reported ever having sex, of whom 52% reported condom use. Adjusting for age, sex, number of partners, residence of partner, partner age difference, type of partner and socio-economic status (SES), having an older partner decreased likelihood (aOR=0.69, p<0.01), while belonging to a household in a higher SES increased likelihood of ever using condoms (aOR=1.82, p<0.01). Being female (aOR=0.61 p<0.01) and having a regular partner (aOR=0.65 p<0.01) were independently associated with low consistent condom use.CONCLUSIONS: In this rural South African setting, condom use remains low, especially among females and with an older partner, situations commonly associated with increased HIV acquisition. Targeted supportive interventions to increase condom use need to be developed if HIV prevention programmes are to be successful

    New excavations at the HWK EE site: Archaeology, paleoenvironment and site formation processes during late Oldowan times at Olduvai Gorge, Tanzania

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    This paper reports the results of renewed fieldwork at the HWK EEsite(Olduvai Gorge, Tanzania). HWK EEis positioned across the boundary between Lower andMiddle Bed II, a crucialinterval for studyingthe emergence of the Acheulean at Olduvai Gorge. Our excavations at HWK EEhave produced one of the largest collections of fossils and artefacts from any Oldowan site, distributed across several archaeological units and a large excavation surface in four separate trenches thatcan be stratigraphically correlated. Here we present the main stratigraphic and archaeological units and discuss site formation processes.Results show a great density of fossils and stone tools vertically through two stratigraphic intervals (Lemuta and Lower Augitic Sandstone)and laterally across an area of around 300 m2, and highlight the confluence of biotic and abiotic agents in the formation of the assemblage. The large size and diversityof the assemblage, as well as its good preservation, qualify HWK EEas a reference sitefor the study of the late Oldowan at Olduvai Gorge and elsewhere in Africa. In addition, thedescriptionof the stratigraphic and archaeological sequenceof HWK EE presented in this paper constitutesthe foundation for further studies on hominin behaviour and palaeoecologyin Lower and Middle Bed II

    Depression and incident HIV in adolescent girls and young women in HPTN 068:Targets for prevention and mediating factors

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    Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2019. This work is written by (a) US Government employee(s) and is in the public domain in the US. The human immunodeficiency virus (HIV) epidemic among adolescent girls and young women (AGYW) in sub-Saharan Africa is a critical public health problem. We assessed whether depressive symptoms in AGYW were longitudinally associated with incident HIV, and identified potential social and behavioral mediators. Data came from a randomized trial of a cash transfer conditional on school attendance among AGYW (ages 13-21 years) in rural Mpumalanga Province, South Africa, during 2011-2017. We estimated the relationship between depressive symptoms and cumulative HIV incidence using a linear probability model, and we assessed mediation using inverse odds ratio weighting. Inference was calculated using the nonparametric bootstrap. AGYW with depressive symptoms had higher cumulative incidence of HIV compared with those without (risk difference = 3.5, 95% confidence interval (CI): 0.1, 7.0). The strongest individual mediators of this association were parental monitoring and involvement (indirect effect = 1.6, 95% CI: 0.0, 3.3) and reporting a partner would hit her if she asked him to wear a condom (indirect effect = 1.5, 95% CI: -0.3, 3.3). All mediators jointly explained two-thirds (indirect effect = 2.4, 95% CI: 0.2, 4.5) of the association between depressive symptoms and HIV incidence. Interventions addressing mental health might reduce risk of acquiring HIV among AGYW

    Mid‐Holocene site formation, diagenesis and human activity at the foothills of Serra da Estrela (Portugal)

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    UIDB/00749/2020 UIDP/00749/2020The Neolithic occupation of Penedo dos Mouros in the foothills of Serra da Estrela, Portugalʼs highest mountain, dates to the 5th to 4th millennia cal B.C. The siteʼs faunal assemblage is extremely rare in the regional prehistoric archaeological record, due to the acidity of the granitic geology. This underlines Penedo dos Mouros importance as a reference site for understanding early pastoralism in the region. Due to the insufficient survival of bone collagen for radiocarbon dating and the homogeneity of the stratigraphy, where most visible contacts are due to postdepositional processes, we chose micromorphology to address the reasons behind the bone preservation and to assess the stratigraphic integrity of the prehistoric deposit. Reworking of eroding saprolitic soils was a major factor in the sediment accumulation, with remains of short human occupation events. Possible evidence for clearance fires linked to the first occurrences of pastoralism practised in the region, creating open spaces for grazing, was identified. Post‐depositional carbonate cementation derived from ashes, identifiable at the microscopic scale, enabled bone preservation. Carbonate and spodic‐like features document water saturation once the sedimentation ceased. This sedimentary dynamic has broader geomorphological implications, such as an inferred post‐Neolithic incision of the stream valley adjacent to the site.publishersversionpublishe
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