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Search Results: 1 - 10 of 2781 matches for " Guy Severin Mahiane "
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A General HIV Incidence Inference Scheme Based on Likelihood of Individual Level Data and a Population Renewal Equation
Guy Severin Mahiane, Rachid Ouifki, Hilmarie Brand, Wim Delva, Alex Welte
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044377
Abstract: We derive a new method to estimate the age specific incidence of an infection with a differential mortality, using individual level infection status data from successive surveys. The method consists of a) an SI-type model to express the incidence rate in terms of the prevalence and its derivatives as well as the difference in mortality rate, and b) a maximum likelihood approach to estimate the prevalence and its derivatives. Estimates can in principle be obtained for any chosen age and time, and no particular assumptions are made about the epidemiological or demographic context. This is in contrast with earlier methods for estimating incidence from prevalence data, which work with aggregated data, and the aggregated effect of demographic and epidemiological rates over the time interval between prevalence surveys. Numerical simulation of HIV epidemics, under the presumption of known excess mortality due to infection, shows improved control of bias and variance, compared to previous methods. Our analysis motivates for a) effort to be applied to obtain accurate estimates of excess mortality rates as a function of age and time among HIV infected individuals and b) use of individual level rather than aggregated data in order to estimate HIV incidence rates at times between two prevalence surveys.
Statistical Power and Estimation of Incidence Rate Ratios Obtained from BED Incidence Testing for Evaluating HIV Interventions among Young People
Bertran Auvert,Guy Séverin Mahiane,Pascale Lissouba,Thierry Moreau
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021149
Abstract: The objectives of this study were to determine the capacity of BED incidence testing to a) estimate the effect of a HIV prevention intervention and b) provide adequate statistical power, when used among young people from sub-Saharan African settings with high HIV incidence rates.
How Should We Best Estimate the Mean Recency Duration for the BED Method?
John Hargrove, Hayden Eastwood, Guy Mahiane, Cari van Schalkwyk
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049661
Abstract: BED estimates of HIV incidence from cross-sectional surveys are obtained by restricting, to fixed time T, the period over which incidence is estimated. The appropriate mean recency duration () then refers to the time where BED optical density (OD) is less than a pre-set cut-off C, given the patient has been HIV positive for at most time T. Five methods, tested using data for postpartum women in Zimbabwe, provided similar estimates of for C = 0.8: i) The ratio (r/s) of the number of BED-recent infections to all seroconversions over T = 365 days: 192 days [95% CI 168–216]. ii) Linear mixed modeling (LMM): 191 days [95% CI 174–208]. iii) Non-linear mixed modeling (NLMM): 196 days [95% CrI 188–204]. iv) Survival analysis (SA): 192 days [95% CI 168–216]. Graphical analysis: 193 days. NLMM estimates of - based on a biologically more appropriate functional relationship than LMM – resulted in best fits to OD data, the smallest variance in estimates of , and best correspondence between BED and follow-up estimates of HIV incidence, for the same subjects over the same time period. SA and NLMM produced very similar estimates of but the coefficient of variation of the former was >3 times as high. The r/s method requires uniformly distributed seroconversion events but is useful if data are available only from a single follow-up. The graphical method produces the most variable results, involves unsound methodology and should not be used to provide estimates of . False-recent rates increased as a quadratic function of C: for incidence estimation C should thus be chosen as small as possible, consistent with an adequate resultant number of recent cases, and accurate estimation of . Inaccuracies in the estimation of should not now provide an impediment to incidence estimation.
New Dendroclimatological Research of Oak (Quercus robur Lat.) in the Area of Šumadija-Central Serbia  [PDF]
Severin ?ikanja
Open Journal of Forestry (OJF) , 2019, DOI: 10.4236/ojf.2019.91001
Abstract: In this scientific paper, a complete field of research will be presented, with a detailed dendroclimatology of work, with final results, and conclusions. The research area is named as: “ROGOT”, and within the Forestry Office “Kragujevac” (Serbia), one of the holdings of J.P. Serbia-Forest. An oak tree (Quercus robur Lat.) will be analyzed, and this 30-tree will be arranged in three experimental fields. It should be emphasized that in each experimental field, 5 trees of generative, and 5 trees of deciduous origin will be analyzed, (10 trees per field, total of 30 trees) in order to exclude the genetic basis of variability. Luznjak’s forests are in a dense garden unit of approximate age close to 80 years, which is a good starting point for dendroclimate analysis. The work also analyzes the density of wood, and it has been proven that the density of wood of oak varies, depending on the climate change. Finally, the most appropriate statistical data processing is done. In the end, it was concluded that the research was successful, and that oak (Quercus robur Lat.) was proved to be an excellent indicator of climate change. Climate change is a very important topic in the world today.
Association of the ANRS-12126 Male Circumcision Project with HIV Levels among Men in a South African Township: Evaluation of Effectiveness using Cross-sectional Surveys
Bertran Auvert ,Dirk Taljaard,Dino Rech,Pascale Lissouba,Beverley Singh,Julie Bouscaillou,Gilles Peytavin,Séverin Guy Mahiane,Rémi Sitta,Adrian Puren,David Lewis
PLOS Medicine , 2013, DOI: 10.1371/journal.pmed.1001509
Abstract: Background Randomized controlled trials have shown that voluntary medical male circumcision (VMMC) reduces HIV infection by 50% to 60% in sub-Saharan African populations; however, little is known about the population-level effect of adult male circumcision (MC) as an HIV prevention method. We assessed the effectiveness of VMMC roll-out on the levels of HIV in the South African township of Orange Farm where the first randomized controlled trial (RCT) to test the effect of VMMC on HIV acquisition was conducted in 2002–2005. Methods and Findings The Bophelo Pele project is a community-based campaign against HIV, which includes the roll-out of free VMMC. A baseline cross-sectional biomedical survey was conducted in 2007–2008 among a random sample of 1,998 men aged 15 to 49 (survey response rate 80.7%). In 2010–2011, we conducted a follow-up random survey among 3,338 men aged 15 to 49 (survey response rate 79.6%) to evaluate the project. Participants were interviewed, blood samples were collected and tested for HIV and recent HIV infection (using the BED HIV incidence assay), and MC status was assessed through a clinical examination. Data were analyzed using multivariate and propensity statistical methods. Owing to the VMMCs performed in the context of the RCT and the Bophelo Pele project, the prevalence rate of adult MC increased from 0.12 (95% CI 0.10–0.14) to 0.53 (95% CI 0.51–0.55). Without these VMMCs, the HIV prevalence rate in 2010–2011 would have been 19% (95% CI 12%–26%) higher (0.147 instead of 0.123). When comparing circumcised and uncircumcised men, no association of MC status with sexual behavior was detected. Among circumcised and uncircumcised men, the proportion consistently using condoms with non-spousal partners in the past 12 months was 44.0% (95% CI 41.7%–46.5%) versus 45.4% (95% CI 42.2%–48.6%) with weighted prevalence rate ratio (wPRR) = 0.94 (95% CI 0.85–1.03). The proportion having two or more non-spousal partners was 50.4% (95% CI 47.9%–52.9%) versus 44.2% (95% CI 41.3%–46.9%) with wPRR = 1.03 (95% CI 0.95–1.10). We found a reduction of BED-estimated HIV incidence rate ranging from 57% (95% CI 29%–76%) to 61% (95% CI 14%–83%) among circumcised men in comparison with uncircumcised men. Conclusions Findings suggest that the roll-out of VMMC in Orange Farm is associated with a significant reduction of HIV levels in the community. The main limitation of the study is that it was not randomized and cannot prove a causal association. The roll-out of VMMC among adults in sub-Saharan Africa should be an international priority and needs to be
Management of acute heart failure-Is there a paradigm shift around the corner?  [PDF]
C. Pater, T. Severin
World Journal of Cardiovascular Diseases (WJCD) , 2013, DOI: 10.4236/wjcd.2013.32A001
Abstract:

It has become increasingly apparent that the looming epidemic of heart failure calls for systematic treatment approaches tailored to the needs of individual patient phenotypes. Although chronic heart failure (CHF) therapies are continuously evolving based on the increasing understanding of the involved etiology, acute heart failure (AHF) therapies are still based on hemodynamic improvements and symptom alleviation. Guidelines on AHF management have highlighted that the currently administered AHF therapies lack evidence and have raised concerns on the safety and efficacy of some of the hitherto accepted treatment modalities. Additionally, the high mortality and morbidity rates associated with the current AHF therapies also add to the imperative need to revisit AHF management. The last decade has witnessed a paradigm shift in the way we define and diagnose AHF. Apart from it being recognized as a distinct clinical entity, research has also led to new data on the pathophysiological changes associated with AHF. These developments along with the limited short- and long-term effects of currently used therapies may herald a paradigm shift in the way we plan and deliver management strategies to treat the pathological progression of heart failure.

Considerations on the Regulation of Arbitration in The New Civil Procedure Code – with Particular Consideration of Institutionalized Arbitration
Adrian Severin
Law Review , 2008,
Abstract: In the following study, the author makes a relatively exhaustive analysis of the provisions of book IV in the new Romanian Civil Procedure Code (Law no. 134/2010, a Code already published (on 15 July 2010) in the Official Journal of Romania, but not yet in force.In this context, the author examines the provisions of “About arbitration” (art. 533 612) in the new Romanian Civil Procedure Code, (with a special focus on the institutionalized commercial arbitration) in relation both to the corresponding provisions in the current Romanian Civil Procedure Code, and to the provisions contained in the Rules of Arbitration of the Court of International Commercial Arbitration attached to the Chamber of Commerce and Industry of Romania.
On some possible features of motion of a polaron in gyrotropic medium
Alexander Severin
Physics , 2014,
Abstract: We predict the possibility of asymmetric dynamics of polaron in gyrotropic medium and give approximate quantitative estimate of the effect.
Deformations of the discrete Heisenberg group
Severin Barmeier
Mathematics , 2013, DOI: 10.3792/pjaa.89.55
Abstract: We study deformations of the discrete Heisenberg group acting properly discontinuously on the Heisenberg group from the left and right and obtain a complete description of the deformation space.
A method of deforming G-structures
Severin Bunk
Mathematics , 2014, DOI: 10.1016/j.geomphys.2015.06.006
Abstract: We consider deformations of G-structures via the right action on the frame bundle in a base-point-dependent manner. We investigate which of these deformations again lead to G-structures and in which cases the original and the deformed G-structures define the same instantons. Further, we construct a bijection from connections compatible with the original G-structure to those compatible with the deformed G-structure and investigate the change of intrinsic torsion under the aforementioned deformations. Finally, we consider several examples.
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