756 research outputs found

    Herbivore Effects on Productivity Vary by Guild: Cattle Increase Mean Productivity While Wildlife Reduce Variability

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    Wild herbivores and livestock share the majority of rangelands worldwide, yet few controlled experiments have addressed their individual, additive, and interactive impacts on ecosystem function. While ungulate herbivores generally reduce standing biomass, their effects on aboveground net primary production (ANPP) can vary by spatial and temporal context, intensity of herbivory, and herbivore identity and species richness. Some evidence indicates that moderate levels of herbivory can stimulate aboveground productivity, but few studies have explicitly tested the relationships among herbivore identity, grazing intensity, and ANPP. We used a long- term exclosure experiment to examine the effects of three groups of wild and domestic ungulate herbivores (megaherbivores, mesoherbivore wildlife, and cattle) on herbaceous productivity in an African savanna. Using both field measurements (productivity cages) and satellite imagery, we measured the effects of different herbivore guilds, separately and in different combinations, on herbaceous productivity across both space and time. Results from both productivity cage measurements and satellite normalized difference vegetation index (NDVI) demonstrated a positive relationship between mean productivity and total ungulate herbivore pressure, driven in particular by the presence of cattle. In contrast, we found that variation in herbaceous productivity across space and time was driven by the presence of wild herbivores (primarily mesoherbivore wildlife), which significantly reduced heterogeneity in ANPP and NDVI across both space and time. Our results indicate that replacing wildlife with cattle (at moderate densities) could lead to similarly productive but more heterogeneous herbaceous plant communities in rangelands

    Male partner antenatal attendance and HIV testing in eastern Uganda: a randomized facility-based intervention trial

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    <p>Abstract</p> <p>Background</p> <p>The objective of the study was to evaluate the effect of a written invitation letter to the spouses of new antenatal clinic attendees on attendance by couples and on male partner acceptance of HIV testing at subsequent antenatal clinic visits.</p> <p>Methods</p> <p>The trial was conducted with 1060 new attendees from October 2009 to February 2010 in an antenatal clinic at Mbale Regional Referral Hospital, Mbale District, eastern Uganda. The intervention comprised an invitation letter delivered to the spouses of new antenatal attendees, while the control group received an information letter, a leaflet, concerning antenatal care. The primary outcome measure was the proportion of pregnant women who attended antenatal care with their male partners during a follow-up period of four weeks. Eligible pregnant women were randomly assigned to the intervention or non-intervention groups using a randomization sequence, which was computer generated utilizing a random sequence generator (RANDOM ORG) that employed a simple randomization procedure. Respondents, health workers and research assistants were masked to group assignments.</p> <p>Results</p> <p>The trial was completed with 530 women enrolled in each group. Participants were analyzed as originally assigned (intention to treat). For the primary outcome, the percentage of trial participants who attended the antenatal clinic with their partners were 16.2% (86/530) and 14.2% (75/530) in the intervention and non-intervention groups, respectively (OR = 1.2; 95% CI: 0.8, 1.6). For the secondary outcome, most of the 161 male partners attended the antenatal clinic; 82 of 86 (95%) in the intervention group and 68 of 75 (91%) in the non-intervention group were tested for HIV (OR = 2.1; 95% CI: 0.6 to 7.5).</p> <p>Conclusions</p> <p>The effect of the intervention and the control on couple antenatal attendance was similar. In addition, the trial demonstrated that a simple intervention, such as a letter to the spouse, could increase couple antenatal clinic attendance by 10%. Significantly, the majority of male partners who attended the antenatal clinic accepted HIV testing. Therefore, to further evaluate this simple and cost-effective intervention method, adequately powered studies are required to assess its effectiveness in increasing partner participation in antenatal clinics and the programme for prevention of mother to child transmission of HIV.</p> <p>Trial Registration</p> <p><b>ClinicalTrials.gov Identifier</b>: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01144234">NCT01144234</a>.</p

    Bone mineral density reductions after tenofovir disoproxil fumarate initiation and changes in phosphaturia: a secondary analysis of ACTG A5224s

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    Background: It is unknown if the greater reductions in bone mineral density (BMD) associated with initiation of tenofovir disoproxil fumarate compared with abacavir in previously untreated HIV-infected participants in the ACTG A5224s clinical trial were associated with potentially worsening tenofovir-related phosphaturia. Methods: We correlated changes in BMD at the hip and spine with changes in phosphaturia [transtubular reabsorption of phosphorus (TRP) and tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/GFR)] from entry through week 96 in those initiating tenofovir ( n  =   134) versus abacavir ( n  =   135) with efavirenz or atazanavir/ritonavir in A5224s. We also correlated changes in BMD with tenofovir AUC measured between weeks 4 and 24. Results: Changes in TRP and TmP/GFR through week 96 between the tenofovir and abacavir arms were not significantly different (both P  ≥   0.70) and did not differ with use of efavirenz versus atazanavir/ritonavir. There were no significant correlations between changes in either TRP or TmP/GFR and with either hip or spine BMD in the tenofovir arms. Tenofovir AUC was significantly correlated with changes in hip BMD, but not spine BMD, at week 24 ( r  =   -0.22, P  =   0.028) and week 48 ( r  =   -0.26, P  =   0.010), but not at week 96 ( r  =   -0.14, P  =   0.18). Conclusions: Changes in phosphaturia were not different between the tenofovir and abacavir arms in A5224s. Changes in hip and spine BMD with tenofovir were not related to changes in phosphaturia. However, tenofovir exposure was weakly associated with changes in hip BMD through week 48

    Attitudes to routine HIV counselling and testing, and knowledge about prevention of mother to child transmission of HIV in eastern Uganda: a cross-sectional survey among antenatal attendees

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    <p>Abstract</p> <p>Background</p> <p>HIV testing rates have exceeded 90% among the pregnant women at Mbale Regional Referral Hospital in Mbale District, eastern Uganda, since the introduction of routine antenatal counselling and testing for HIV in June 2006. However, no documented information was available about opinions of pregnant women in eastern Uganda about this HIV testing approach. We therefore conducted a study to assess attitudes of antenatal attendees towards routine HIV counselling and testing at Mbale Hospital. We also assessed their knowledge about mother to child transmission of HIV and infant feeding options for HIV-infected mothers.</p> <p>Methods</p> <p>The study was a cross-sectional survey of 388 women, who were attending the antenatal clinic for the first time with their current pregnancy at Mbale Regional Referral Hospital from August to October 2009. Data were collected using a pre-tested questionnaire and analysed using descriptive statistics and logistic regression. Permission to conduct the study was obtained from the Makerere University College of Health Sciences, the Uganda National Council of Science and Technology, and Mbale Hospital.</p> <p>Results</p> <p>The majority of the antenatal attendees (98.5%, 382/388) had positive attitudes towards routine HIV counselling and testing, and many of them (more than 60%) had correct knowledge of how mother to child transmission of HIV could occur during pregnancy, labour and through breastfeeding, and ways of preventing it. After adjusting for independent variables, having completed secondary school (odds ratio: 2.5, 95% confidence interval: 1.3-4.9), having three or more pregnancies (OR: 2.5, 95% CI: 1.4-4.5) and belonging to a non-Bagisu ethnic group (OR: 1.7, 95% CI: 1.0-2.7) were associated with more knowledge of exclusive breastfeeding as one of the measures for prevention of mother to child transmission of HIV. Out of 388 antenatal attendees, 386 (99.5%) tested for HIV and 382 (98.5%) received same-day HIV test results.</p> <p>Conclusions</p> <p>Routine offer of antenatal HIV counselling and testing is largely acceptable to the pregnant women in eastern Uganda and has enabled most of them to know their HIV status as part of the prevention of mother to child transmission of HIV package of services. Our findings call for further strengthening and scaling up of this HIV testing approach in many more antenatal clinics countrywide in order to maximize its potential benefits to the population.</p

    Causal datasheet for datasets: an evaluation guide for real-world data analysis and data collection design using Bayesian networks

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    Developing data-driven solutions that address real-world problems requires understanding of these problems’ causes and how their interaction affects the outcome–often with only observational data. Causal Bayesian Networks (BN) have been proposed as a powerful method for discovering and representing the causal relationships from observational data as a Directed Acyclic Graph (DAG). BNs could be especially useful for research in global health in Lower and Middle Income Countries, where there is an increasing abundance of observational data that could be harnessed for policy making, program evaluation, and intervention design. However, BNs have not been widely adopted by global health professionals, and in real-world applications, confidence in the results of BNs generally remains inadequate. This is partially due to the inability to validate against some ground truth, as the true DAG is not available. This is especially problematic if a learned DAG conflicts with pre-existing domain doctrine. Here we conceptualize and demonstrate an idea of a “Causal Datasheet” that could approximate and document BN performance expectations for a given dataset, aiming to provide confidence and sample size requirements to practitioners. To generate results for such a Causal Datasheet, a tool was developed which can generate synthetic Bayesian networks and their associated synthetic datasets to mimic real-world datasets. The results given by well-known structure learning algorithms and a novel implementation of the OrderMCMC method using the Quotient Normalized Maximum Likelihood score were recorded. These results were used to populate the Causal Datasheet, and recommendations could be made dependent on whether expected performance met user-defined thresholds. We present our experience in the creation of Causal Datasheets to aid analysis decisions at different stages of the research process. First, one was deployed to help determine the appropriate sample size of a planned study of sexual and reproductive health in Madhya Pradesh, India. Second, a datasheet was created to estimate the performance of an existing maternal health survey we conducted in Uttar Pradesh, India. Third, we validated generated performance estimates and investigated current limitations on the well-known ALARM dataset. Our experience demonstrates the utility of the Causal Datasheet, which can help global health practitioners gain more confidence when applying BNs

    Detection of the spotted wing drosophila, Drosophila suzukii, in continental sub-Saharan Africa

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    The spotted wing drosophila, Drosophila suzukii Matsumura, is an insect pest of soft-skinned fruit, native to Eastern Asia. Since 2008, a world-wide dispersal of D. suzukii is seen, characterized by the establishment of the pest in many Asian, American and European countries. While the potential for invasion of continental Africa by D. suzukii has been predicted, its presence has only been shown for Morocco in Northern Africa. Knowledge about a possible establishment in other parts of the continent is needed as a basis for pest management. In 2019, we carried out a first survey in three counties in Kenya to monitor for the presence of D. suzukii using traps baited with a blend of apple cider vinegar and red wine. A total of 389 D. suzukii flies were captured in a fruit farm at Nakuru county, with more female flies being trapped than males. We confirmed the morphological identification of D. suzukii using DNA barcoding. In 2020, we performed a follow-up survey at 14 locations in six counties to delimit the distribution of D. suzukii in the main berry growing zones in Kenya. The survey indicated that so far D. suzukii is restricted to Nakuru county where it was initially detected. This is the first study to provide empirical evidence of D. suzukii in continental sub-Saharan Africa, confirming that the pest is expanding its geographic range intercontinentally. Given the high dispersal potential of D. suzukii, a concerted effort to develop management strategies is a necessity for containment of the pest

    Etiology of Severe Non-malaria Febrile Illness in Northern Tanzania: A Prospective Cohort Study.

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    The syndrome of fever is a commonly presenting complaint among persons seeking healthcare in low-resource areas, yet the public health community has not approached fever in a comprehensive manner. In many areas, malaria is over-diagnosed, and patients without malaria have poor outcomes. We prospectively studied a cohort of 870 pediatric and adult febrile admissions to two hospitals in northern Tanzania over the period of one year using conventional standard diagnostic tests to establish fever etiology. Malaria was the clinical diagnosis for 528 (60.7%), but was the actual cause of fever in only 14 (1.6%). By contrast, bacterial, mycobacterial, and fungal bloodstream infections accounted for 85 (9.8%), 14 (1.6%), and 25 (2.9%) febrile admissions, respectively. Acute bacterial zoonoses were identified among 118 (26.2%) of febrile admissions; 16 (13.6%) had brucellosis, 40 (33.9%) leptospirosis, 24 (20.3%) had Q fever, 36 (30.5%) had spotted fever group rickettsioses, and 2 (1.8%) had typhus group rickettsioses. In addition, 55 (7.9%) participants had a confirmed acute arbovirus infection, all due to chikungunya. No patient had a bacterial zoonosis or an arbovirus infection included in the admission differential diagnosis. Malaria was uncommon and over-diagnosed, whereas invasive infections were underappreciated. Bacterial zoonoses and arbovirus infections were highly prevalent yet overlooked. An integrated approach to the syndrome of fever in resource-limited areas is needed to improve patient outcomes and to rationally target disease control efforts

    Perception Is Reality: quality metrics in pancreas surgery – a Central Pancreas Consortium (CPC) analysis of 1399 patients

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    Several groups have defined pancreatic surgery quality metrics that identify centers delivering quality care. Although these metrics are perceived to be associated with good outcomes, their relationship with actual outcomes has not been established

    Plant Power:Opportunities and challenges for meeting sustainable energy needs from the plant and fungal kingdoms

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    Societal Impact Statement Bioenergy is a major component of the global transition to renewable energy technologies. The plant and fungal kingdoms offer great potential but remain mostly untapped. Their increased use could contribute to the renewable energy transition and addressing the United Nations Sustainable Development Goal 7 “Ensure access to affordable, reliable, sustainable and modern energy for all.” Current research focuses on species cultivated at scale in temperate regions, overlooking the wealth of potential new sources of small‐scale energy where they are most urgently needed. A shift towards diversified, accessible bioenergy technologies will help to mitigate and adapt to the threats of climate change, decrease energy poverty, improve human health by reducing indoor pollution, increase energy resilience of communities, and decrease greenhouse gas emissions from fossil fuels. Summary Bioenergy derived from plants and fungi is a major component of the global transition to renewable energy technologies. There is rich untapped diversity in the plant and fungal kingdoms that offers potential to contribute to the shift away from fossil fuels and to address the United Nations Sustainable Development Goal 7 (SDG7) “Ensure access to affordable, reliable, sustainable and modern energy for all.” Energy poverty—the lack of access to modern energy services—is most acute in the Global South where biodiversity is greatest and least investigated. Our systematic review of the literature over the last 5 years (2015–2020) indicates that research efforts have targeted a very small number of plant species cultivated at scale, mostly in temperate regions. The wealth of potential new sources of bioenergy in biodiverse regions, where the implementation of SDG7 is most urgently needed, has been largely overlooked. We recommend next steps for bioenergy stakeholders—research, industry, and government—to seize opportunities for innovation to alleviate energy poverty while protecting biodiversity. Small‐scale energy production using native plant species in bioenergy landscapes overcomes many pitfalls associated with bioenergy crop monocultures, such as biodiversity loss and conflict with food production. Targeted trait‐based screening of plant species and biological screening of fungi are required to characterize the potential of this resource. The benefits of diversified, accessible bioenergy go beyond the immediate urgency of energy poverty as more diverse agricultural landscapes are more resilient, store more carbon, and could also reduce the drivers of the climate and environmental emergencies
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