1,570 research outputs found
The increasing burden of tuberculosis in rural South Africa - impact of the HIV epidemic
Objective. To determine the impact of the HIV epidemic on tuberculosis caseload in rural South Africa.Setting. Hlabisa health district, Kwazulu-Natal.Methods. Demographic and clinical data were extracted from the tuberculosis database for the period, May 1991 June 1995. The attributable fraction of HIV-infected tuberculosis cases was estimated from the prevalence of HIV infection in tuberculosis cases and the prevalence of HIV infection in women attending antenatal clinics.Results. Between 1991 and 1995, the annual tuberculosis caseload increased from 301 to 839 cases. Tuberculosis accounted for 4.7% of all admissions in 1989 and 8.3% in 1995 (P < 0.0001). The incidence of tuberculosis increased from 154/1 00 000 in 1991, to 413/100 000 in 1995. The proportion with smear-positive pulmonary disease fell from 65% to 56% (P = 0.04), and pleural tuberculosis accounted for 7.5% of disease in 1991 and 18% in 1995 (P = 0.002). The minimum HIV prevalence in patients with tuberculosis increased from 8.7% in 1991 to 28.3% in 1995, and the proportion of tuberculosis cases attributable to HIV infection was estimated to be at least 44% in 1995.Conclusion. The burden of HIV-related tuberculosis is increasing rapidly in rural South Africa and is exerting a negative impact. Innovative approaches to control will be needed to cope with it effectively
Magnetisation transfer imaging in the study of early relapsing-remitting multiple sclerosis.
Multiple sclerosis is a common cause of neurological disability in the young adult, but, at present, disease modifying medication may have little, if any, effect upon long term clinical impairment. For this reason, there is a continuing need to understand the mechanisms that lead to long term disability and - in the context of clinical trials - to develop reliable surrogate markers of disease progression. It may be especially useful to describe the early evolution of abnormality within normal-appearing white matter (NAWM) and grey matter firstly because pathology in early MS may be a key determinant of later disability, and secondly because there is only a modest relationship between white matter lesion load and clinical impairment. This thesis presents a series of studies, investigating NAWM and grey matter abnormality in a cohort of patients with early relapsing-remitting MS. A key question was whether MRI measures were able to detect accumulating abnormality in NAWM and grey matter early in the clinical course. An initial investigation, using Ti relaxation time estimation, did not detect strong evidence for a net change over time. Attention was therefore turned to the magnetisation transfer ratio (MTR) and results from a series of studies, investigating NAWM, grey matter and thalamic MTR abnormalities in early relapsing-remitting MS are presented. Of note, a clinically relevant reduction in grey matter MTR was apparent, and there was evidence for increasing MTR abnormality in the grey matter, NAWM and the thalamus over a two year follow-up period. In part three of this thesis, a model for the MT effect is used to estimate two underlying MT parameters - the semi-solid proton fraction (/) and the semi-solid T2 (T2B) in sixty patients with clinically-definite MS. The aim was to assess the clinical relevance of these novel parameters
Sr–Pb isotope differences in pre- and post-burial human bone, teeth, and hair keratin: implications for isotope forensics
The isotopic signatures of human tissues can provide valuable information on geographic origin for medicolegal investigations involving unidentified persons. It is important to understand the impact of diagenetic processes on isotopic signatures, as alterations could result in incorrect estimation of geographic origin. This study examines alterations in isotope signatures of different tissues of five human body donors studied throughout decomposition at the Forensic Anthropology Research Facility (FARF), San Marcos, TX. Two body donors were buried, two were placed in open pits, and one was first allowed to naturally mummify and then buried. Remains were recovered after a period of 7–34 months. The preplacement and post-recovery Sr–Pb isotope data of scalp hair, bone (iliac and tibia), and tooth enamel and dentine were compared. The hair samples record significant shifts in Sr-Pb isotope compositions, with hair keratin Pb isotope composition shifting towards the Pb signature of local soil samples. Hair keratin Sr isotope compositions were altered by the burial environment and possibly also by the lab sample cleaning method. The spongy iliac bone samples show inconsistencies in the recoverability of the preplacement Sr–Pb isotope signatures. The post-placement signatures of the buried donors show slight elevation over preplacement signatures. The post-placement signatures of donors placed in open pits are significantly elevated. The tibia and dental samples record the most consistent isotopic data with the least alteration. These more densely mineralised elements show good recoverability of the preplacement isotope signatures in burials and open pits and are thus deemed better targets for forensic investigative purposes
HiQuake: The Human-Induced Earthquake Database
HiQuake—The Human‐Induced Earthquake Database is the most complete database of anthropogenic projects proposed, on scientific grounds, to have induced earthquake sequences. It is freely available to download from the website given in Data and Resources. At the time this article was written, HiQuake contained ∼730∼730 anthropogenic projects proposed to have induced earthquakes, as well as associated project‐related and seismic data. The most commonly reported anthropogenic activities proposed to have induced earthquakes are mining and water reservoir impoundment. In recent years, the number of earthquake sequences proposed to have been induced by fluid‐injection activities has grown. The most commonly reported maximum observed magnitude in an induced earthquake sequence is 3≤MMAX<43≤MMAX<4 . The largest earthquake in HiQuake proposed to have been induced had a magnitude of MwMw 7.9 and occurred in China. Such large earthquakes release mostly stress of natural tectonic origin, but are conceivably triggered by small anthropogenic stress changes. The data in HiQuake are of variable quality because they are drawn from publications that span almost a century. We estimate underreporting to be ∼30%∼30% for M∼4M∼4 events, ∼60%∼60% for M∼3M∼3 events, and ∼90%∼90% for M∼2M∼2 events. The degree of certitude that the given earthquake sequences were anthropogenically induced is variable. HiQuake includes all earthquake sequences proposed on scientific grounds to have been human induced without regard to the strength of the case made. HiQuake is offered freely as a resource to interested parties, and judging the reliability of any particular case is the responsibility of the database user. HiQuake will be routinely updated to correct errors, update existing entries, and add new entries. It has the potential to help improve our understanding of induced earthquakes and to manage their impact on society
Латинська Америка в дослідженнях російських етнографів за останні тридцять років
Статья посвящена истории исследований в области латиноамериканистики российскими и советскими учёными на примере научной деятельности сотрудников Института этнографии им. Н. Н. Миклухо-Маклая АН СССР (московское и ленинградское отделения).The article is dedicated to the Latin American researches provided by the Russian and Soviet scientists illustrated with the scientific activities of the representatives of the Soviet Academy of Science’s Myklukho-Maklai Ethnographical Institute (Moscow and Leningrad branches)
Spatial variation in the effects of size and age on reproductive dynamics of common coral trout Plectropomus leopardus
The effects of size and age on reproductive dynamics of common coral trout Plectropomus leopardus populations were compared between coral reefs open or closed (no-take marine reserves) to fishing and among four geographic regions of the Great Barrier Reef (GBR), Australia. The specific reproductive metrics investigated were the sex ratio, the proportion of vitellogenic females and the spawning fraction of local populations. Sex ratios became increasingly male biased with length and age, as expected for a protogyne, but were more male biased in southern regions of the GBR (Mackay and Storm Cay) than in northern regions (Lizard Island and Townsville) across all lengths and ages. The proportion of vitellogenic females also increased with length and age. Female P. leopardus were capable of daily spawning during the spawning season, but on average spawned every 4·3 days. Mature females spawned most frequently on Townsville reserve reefs (every 2·3 days) and Lizard Island fished reefs (every 3·2 days). Females on Mackay reefs open to fishing showed no evidence of spawning over 4 years of sampling, while females on reserve reefs spawned only once every 2–3 months. No effect of length on spawning frequency was detected. Spawning frequency increased with age on Lizard Island fished reefs, declined with age on Storm Cay fished reefs, and declined with age on reserve reefs in all regions. It is hypothesized that the variation in P. leopardus sex ratios and spawning frequency among GBR regions is primarily driven by water temperature, while no-take management zones influence spawning frequency depending on the region in which the reserve is located. Male bias and lack of spawning activity on southern GBR, where densities of adult P. leopardus are highest, suggest that recruits may be supplied from central or northern GBR. Significant regional variation in reproductive traits suggests that a regional approach to management of P. leopardus is appropriate and highlights the need for considering spatial variation in reproduction where reserves are used as fishery or conservation management tools
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Sr and Nd isotopes were determined using new thermal ionisation mass spectrometry (TIMS) techniques for a suite of 21 olivine-hosted (85-92mol% Fo) melt inclusions selected from potassic and ultra-potassic lavas from the Italian peninsula. Sr isotopes were measured using default 1
Coupled trace element and Sr-Nd-(Pb) isotopes in olivine-hosted melt inclusions from the Mariana arc
The Mariana arc forms part of the 2500 km Izu–Bonin–Mariana arc system caused by westward subduction of the Pacific Plate beneath the Philippine Sea Plate over the last ~45 Myr. The magmatism produced in this comparatively simple arc setting records a moderate flux of fluids and sediments from the downgoing plate, however, the low MgO (<6 wt.%) of the lavas imply that magma mixing, crystal fractionation and crustal assimilation mask the primitive melt compositions. Olivine-hosted melt inclusions (MIs), in contrast, provide access to melt trapped deep in the magmatic plumbing system allowing more precise determination of the nature and quantity of recycled components. Here we analyse coupled trace element and Sr-Nd(-Pb) isotope compositions of olivine-hosted MIs in five samples from four islands within the Central Island province: Agrigan (AGR2, AGR6), Pagan (PAG3), Guguan (GUG6) and Sarigan (SAG1). Bulk rock MgO contents range from 4 to 5.7 wt.% [1]. We specifically target melt inclusions in olivine phenocrysts with the highest fortsterite content (Fo = Mg/(Mg+Fe)*100): AGR: 80-86; PAG: 76-81; GUG: 76-88; SAG: 84-88 mol%. Trace element contents and ratios of the selected MIs record marked differences between islands and show larger variability compared to published bulk rock and MI compositions [2]. Ba/La and Th/Nb or La/Sm ratios – indicators of slab fluids versus sediment melts, respectively – confirm that Guguan inclusions are dominated by a fluid component whereas Agrigan and Sarigan reflect a larger sediment contribution. Pagan inclusions show intermediate compositions and a restricted range indicating the influence of both fluids and sediments. Sr-Nd-(Pb) isotope compositions of individual and pooled melt inclusions will be determined by wet chemistry and TIMS techniques using 10^13 Ω amplifier technology [3] to further identify and quantify the recycled components. [1] Elliott et al. (1997). Journal of Geophysical Research, 102: 14991-15019. [2] Kent & Elliott (2002). Chemical Geology, 183: 263-286. [3] Koornneef et al. (2019). Nature Communications 10, 323
Radiogenic isotopes in minerals and melt inclusions reveal that mantle heterogeneity is masked by mixing
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