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Search Results: 1 - 10 of 1842 matches for " Raphael Senga "
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High prevalence of syphilis among demobilized child soldiers in Eastern Congo: a cross-sectional study
Raphael Senga, Prosper Lutala
Conflict and Health , 2011, DOI: 10.1186/1752-1505-5-16
Abstract: Screening of syphilis using the rapid plasma reagin test and the Treponema pallidum hemagglutination assay was conducted in three transit sites of soldier reintegration in 2005. The Fisher Exact probability test was used to compare results.The prevalence of syphilis was found to be 3.4%, with almost equal distribution in respect to sex, location.Syphilis continues to be highly prevalent in demobilized child soldiers in Eastern Congo. Syphilis screening tests are recommended.Syphilis and to some extent other sexually transmitted infections (STIs) are a major public health issue for soldiers during periods of conflict. In the Democratic Republic of Congo (Congo), these have been exacerbated by widespread sexual violence. Child soldiers are particularly vulnerable due to several factors: incomplete maturation, low social conditions, use as sexual workers by superiors, and their promiscuous environment. During World Wars I and II and subsequent armed conflicts throughout the world, syphilis has played an unprecedented role in soldier morbidity [1]. The Congo, with almost two decades of armed conflicts, is characterized by widespread sexual violence [2,3]. In the Congo and other African countries, recruitment of child soldiers has been largely practiced despite its war-crime characterization as defined by the Rome Statute of the International Criminal Court [4].As a war nears its end, disarmament, demobilization, and reinsertion (DDR) of combatants is a compulsory post-conflict step. In the Congo, all child soldiers undergo this process, which allows soldiers who desire, or who are children, to return to civilian life. At the transit camp soldiers undergo compulsory syphilis testing. To prevent possible spread of the disease upon reintegration, those who test positive undergo treatment.Despite a number of studies dealing with syphilis prevalence in various contexts, to our knowledge, little is known about syphilis prevalence in demobilized soldiers, and particularly in c
Paracheck-Pf? accuracy and recently treated Plasmodium falciparum infections: is there a risk of over-diagnosis?
Todd D Swarthout, Helen Counihan, Raphael Senga, Ingrid van den Broek
Malaria Journal , 2007, DOI: 10.1186/1475-2875-6-58
Abstract: This RDT assessment occurred in conjunction with an ACT efficacy trial. Febrile children were simultaneously screened with both RDT and high quality microscopy and those meeting inclusion criteria were followed for 35 days.358 febrile children were screened with 180 children recruited for five weeks follow-up. On screening, the RDT accurately diagnosed all 235 true malaria cases, indicating 100% RDT sensitivity. Of the 123 negative slides, the RDT gave 59 false-positive results, indicating 52.0% (64/123) RDT specificity. During follow-up after treatment with an artemisinin-based combination therapy, 98.2% (110/112), 94.6% (106/112), 92.0% (103/112) and 73.5% (50/68) of effectively treated children were still false-positive by RDT at days 14, 21, 28 and 35, respectively.Results show that though the use of Paracheck-Pf? is as sensitive as microscopy in detecting true malaria cases, a low specificity did present a high frequency of false-positive RDT results. What's more, a duration of RDT false-positivity was found that significantly surpassed the 'fortnight' after effective treatment reported by its manufacturer. Though further research is needed in assessing RDT accuracy, study results showing the presence of frequent false positivity should be taken into consideration to avoid clinicians inappropriately focusing on malaria, not identifying the true cause of illness, and providing unnecessary treatment.In response to increased antimalarial drug resistance, the past decade has witnessed the introduction of artemisinin-based combination therapy (ACT) by many malaria-endemic countries. With the significantly higher cost of ACT over the previously used chloroquine and sulphadoxine-pyrimethamine, there has been a strong emphasis in avoiding any unnecessary use of ACT and minimizing opportunities for the development of parasite drug resistance. Though clinical diagnosis can be very sensitive, its limited specificity can lead to inappropriate treatment [1]. As such, clinic
PICO-PHYTOPLANKTON DISTRIBUTION IN WESTERN PACIFIC OCEAN ESTIMATED FROM OCEAN COLOR AND SST
Senga,Yasuhiro; Horiuchi,Tomohiro;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000300037
Abstract: to investigate the spatial distribution of pico-phytoplankton in surface water, photosynthetic pigments were analyzed by a high-performance liquid chromatography (hplc) for three cruises in the western pacific ocean carried out on 2000, 2001 and 2002. analyzed chlorophyll-a showed peaks at the equatorial region and near japan. in contrast, zeaxanthin, a specific pigment of pico-phytoplankton such as synechococcus and prochlorococcus showed a broad peak around equatorial region. from these results, we found inverse relationship between the ratio of zeaxanthin to chlorophyll-a concentration (zcr) and chlorophyll-a concentration, and also positive relationship between zcr and sea surface temperature (sst). and we derived a multiple regression equation to estimate zcr from chlorophyll-a concentration and sst. the equation was applied to estimate spatial distribution of zcr in the pacific ocean using satellite chlorophyll-a images and sst images
PICO-PHYTOPLANKTON DISTRIBUTION IN WESTERN PACIFIC OCEAN ESTIMATED FROM OCEAN COLOR AND SST
Yasuhiro Senga,Tomohiro Horiuchi
Gayana (Concepción) , 2004,
Abstract: To investigate the spatial distribution of pico-phytoplankton in surface water, photosynthetic pigments were analyzed by a high-performance liquid chromatography (HPLC) for three cruises in the western Pacific Ocean carried out on 2000, 2001 and 2002. Analyzed chlorophyll-a showed peaks at the equatorial region and near Japan. In contrast, zeaxanthin, a specific pigment of pico-phytoplankton such as Synechococcus and Prochlorococcus showed a broad peak around equatorial region. From these results, we found inverse relationship between the ratio of zeaxanthin to chlorophyll-a concentration (ZCR) and chlorophyll-a concentration, and also positive relationship between ZCR and sea surface temperature (SST). And we derived a multiple regression equation to estimate ZCR from chlorophyll-a concentration and SST. The equation was applied to estimate spatial distribution of ZCR in the Pacific Ocean using satellite chlorophyll-a images and SST images
Impurity-induced in-gap state and Tc in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors
Yuko Senga,Hiroshi Kontani
Physics , 2008, DOI: 10.1088/1367-2630/11/3/035005
Abstract: The sign-reversing fully gapped superconducting state, which is expected to be realized in oxypnictide superconductors, can be prominently affected by nonmagnetic impurities due to the interband scattering of Cooper pairs. We study this problem based on the isotropic two-band BCS model: In oxypnictide superconductors, the interband impurity scattering $I'$ is not equal to the intraband one $I$. In the Born scattering regime, the reduction in Tc is sizable and the impurity-induced density of states (DOS) is prominent if $I\sim I'$, due to the interband scattering. Although impurity-induced DOS can yield a power-law temperature dependence in $1/T_1$, a sizable suppression in Tc is inevitably accompanied. In the unitary scattering regime, in contrast, impurity effect is very small for both Tc and DOS except at $I=I'$. By comparing theory and experiments, we expect that the degree of anisotropy in the $s_\pm$-wave gap function strongly depends on compounds.
Impurity Effects in Sign Reversing Fully-Gapped Superconductors: Analysis of FeAs Superconductors
Y. Senga,H. Kontani
Physics , 2008, DOI: 10.1143/JPSJ.77.113710
Abstract: To understand the impurity effect on Tc in FeAs superconductors, we analyze a simple two-band BCS model with repulsive interband interaction. The realized fully-gapped superconducting state with sign reversal, which is predicted by spin fluctuation theories in this compound, is suppressed by impurities due to the interband hopping of Cooper pairs, if the interband impurity scattering $I'$ is equal to the intraband one $I$. When $|I'/I| < 1$, in highly contrast, Tc is almost unchanged by strong impurity scattering since the interband scattering is almost prohibited by the multiple scattering effect. Since $|I'/I| \sim 0.5$ is expected, the robustness of superconductivity against impurities in FeAs superconductors is naturally understood in term of the sign reversing fully-gapped state.
A Method for Determining Batillaria attramentaria Distribution Using Aerial Balloon Photography and a Vegetation Index Camera: Demonstration at the Yatsu Tidal Flat, Chiba Prefecture  [PDF]
Yohei Shiraki, Toshiyuki Kitazawa, Seongwon Lee, Yukiko Senga
Advances in Remote Sensing (ARS) , 2018, DOI: 10.4236/ars.2018.71002
Abstract: Located in Chiba Prefecture, the Yatsu Tidal Flat is an important stopover for birds migrating between cold regions such as Siberia and warm regions such as Southeast Asia and Australia. Its importance led to its selection in 1993 as the first tidal flat in Japan to be registered under the Convention on Wetlands of International Importance especially as Waterfowl Habitat (the Ramsar Convention). However, the Yatsu Tidal Flat has in more recent years witnessed blooms of Ulva spp. (sea lettuce) and an increase in exotic species such as Batillaria attramentaria (Japanese mud snail) and Mercenaria mercenaria (hard clam), fueling concerns that the increasing spatial domination of the tidal flat by such species and competition with other species for food may drive a decline in the habitat’s self-cleaning capabilities. For this study, we focused on Batillaria attramentaria, which is now so widely distributed in the Yatsu Tidal Flat as to preclude reliable monitoring via aerial photographs or satellite imagery. Accordingly, we tested the utility of a simplified method for obtaining data on the distribution of Batillaria attramentaria by using aerial balloon photography and a vegetation index camera capable of generating NDVI data. Our results show that under certain conditions, this method can indeed be used to determine Batillaria attramentaria distribution.
Cross-Correlation of Station-to-Station Free Surface Elevation Time Series for Breaking Water Waves  [PDF]
Raphael Mukaro
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.92010
Abstract:
Free surface elevation time series of breaking water waves were measured in a laboratory flume. This was done in order to analyze changes in wave characteristics as the waves propagated from deep water to the shore. A pair of parallel- wire capacitive wave gages was used to simultaneously measure free surface elevations at different positions along the flume. One gage was kept fixed near the wave generator to provide a reference while the other was moved in steps of 0.1 m in the vicinity of the break point. Data from these two wave gages measured at the same time constitute station-to-station free surface elevation time series. Fast Fourier Transform (FFT) based cross-correlation techniques were employed to determine the time lag between each pair of the time series. The time lag was used to compute the phase shift between the reference wave gage and that at various points along the flume. Phase differences between two points spaced 0.1 m apart were used to calculate local mean wave phase velocity for a point that lies in the middle. Results show that moving from deep water to shallow water, the measured mean phase velocity decreases almost linearly from about 1.75 m/s to about 1.50 m/s at the break point. Just after the break point, wave phase velocity abruptly increases to a maximum value of 1.87 m/s observed at a position 30 cm downstream of the break point. Thereafter, the phase velocity decreases, reaching a minimum of about 1.30 m/s.
Explaining variation in GP referral rates for x-rays for back pain
Rachel Baker, Jan Lecouturier, Senga Bond
Implementation Science , 2006, DOI: 10.1186/1748-5908-1-15
Abstract: Qualitative, semi-structured interviews with 29 GPs with high and low referral rates for LSX in North East England. Thematic analysis used constant comparative techniques.Common and divergent themes were identified among high- and low-users of LSX. Themes that were similar in both groups included an awareness of current guidelines for the use of LSX for patients with LBP and the pressure from patients and institutional factors to order a LSX. Differentiating themes for the high-user group included: a belief that LSX provides reassurance to patients that can outweigh risks, pessimism about the management options for LBP, and a belief that denying LSX would adversely affect doctor-patient relationships. Two specific differentiating themes are considered in more depth: GPs' awareness of their use of lumbar spine radiology relative to others, and the perceived risks associated with LSX radiation.Several key factors differentiate the accounts of GPs who have high and low rates of referral for LSX, even though they are aware of clinical guideline recommendations. Intervention studies that aim to increase adherence to guideline recommendations on the use of LSX by changing the ordering behaviour of practitioners in primary care should focus on these factors.Low back pain (LBP) is a global and increasing problem [1]. Estimates of point prevalence range between 12% and 35% and lifetime prevalence between 49% and 80% [2]. The cost of LBP in the United Kingdom is high, both to the NHS (National Health Service) and in terms of the wider societal costs [2,3]. While there are a number of serious conditions that cause LBP, most LBP is non-specific, benign, and self limiting, although it may become recurrent [4,5]. Non-specific LBP is classified by the duration of symptoms into acute (less than 3–6 weeks), sub-acute (less than three months) and chronic (more than three months) [6-8]. One distinction between the acute and chronic forms of non-specific LBP is that the prognosis for t
Optimization of an Ammonia Synthesis Converter  [PDF]
Jackson Gunorubon Akpa, Nwokoma Raphael Raphael
World Journal of Engineering and Technology (WJET) , 2014, DOI: 10.4236/wjet.2014.24032
Abstract: A scheme that optimizes the converter of an ammonia synthesis plant to determine optimal inlet temperatures of the catalyst beds has been developed. The optimizer maximizes an objective function—The fractional conversion of nitrogen on the four catalyst beds of the converter subject to variation of the inlet temperature to each catalyst bed. An iterative procedure was used to update the initial values of inlet temperature thus ensuring accurate results and quick convergence. Converter model results obtained with optimized operating conditions showed significant increase in fractional conversion of 42.38% (from 0.1949 to 0.2586), increased rate of reaction evident in a 13.18% (0.5317 to 0.4616) and 23.84% (0.1946 to 0.1482) reduction in reactants (hydrogen and nitrogen) concentration respectively and a 56.48% increase (from 0.1181 to 0.1838) in ammonia concentration at the end of the fourth catalyst bed compared to results obtained with industrial operating conditions.
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