251 research outputs found
Differences in the epidemiology of theileriosis on smallholder dairy farms in contrasting agro-ecological and grazing strata of highland Kenya
A prospective cohort study was conducted in five purposively-sampled agro-ecological zone (AEZ)-grazing system strata in Murang’a District, Kenya, between March 1995 and June 1996. The study strata were selected based on a preliminary characterization study to represent the widest range of risks to East Coast fever (ECF) in the District and included zero-grazing and open-grazing farms. In total, 225 calves from 188 smallholder farms were examined from birth to 6 months of age and visited within the first 2 weeks of life and thereafter at bi-weekly intervals for up to 14 visits.
The purpose of the study was to characterize the differences in epidemiology (risks of infection, morbidity and mortality) and potential control of ECF between the selected strata. Evidence of Theileria parva infection was assessed by increased antibody levels as measured in an indirect ELISA assay by the percent positivity (PP) of serum samples relative to a strong positive reference serum.
Sero-conversion risks of T. parva were highest in the open-grazing strata. Antibody prevalence in adult cattle and ECF morbidity and mortality risks were also highest in open-grazing strata. While different, all five AEZ-grazing strata were considered to be endemically unstable for ECF. East Coast fever challenge was low in all zero-grazing strata and this challenge is likely to remain low due to continuing intensification of smallholder farming in the central highlands. In the open-grazing strata, there was higher challenge and a greater impact of ECF.
ILRI publication no.: 99017
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SCALING UP THE OXYGENIC PHOTOGRANULE (OPG) WASTEWATER TREATMENT PROCESS
Photogranular biomass has yet to be utilized at large scale for wastewater treatment despite their potential to lower energy demand due to self-aerating capacity in addition to better process control compared to conventional technologies. An evaluation of critical driving factors affecting scaling up has yet to be undertaken. The current generation of oxygenic photogranules under hydrostatic conditions (a deviation from orthodox conditions creating other granules) limit seeding of larger reactors in time and scale. In addition, evaluating the photosynthetic productivity of granules which exist as closely commingled consortia with tightly coupled production and consumption processes, has yet to be undertaken.
We experimentally evaluate the alternative generation of oxygenic photogranules under hydrodynamic conditions. The photochemical capacity of oxygenic photogranules under variable light conditions was also determined. Concomitantly, we evaluate the effects of light intensity on the performance of reactors of varying scales and the light demand therewith. Finally, granular physical attributes that impact hydrodynamic behaviour and interaction with the bulk fluid due to agitation were assessed.
Oxygenic photogranules were formed only under some combinations of different pressures in 8 days, suggesting a ‘goldilocks zone’ of selection pressure interaction fostering granulation. Rapid generation of multiple granules would ease seeding of reactors higher volume reactors.
OPGs phototrophic capacity was also found to increase with light intensity to a curvilinear maximum beyond which photoinhibition ensues. This implies the existence of light-limited operating conditions below maximal sunlight intensities. Photoelasticity was also observed for granules treated under different light stress with apparent adaptability to abiotic stresses. Moreover, the light dependency is influenced by reactor design and operation, allowing for recovery of the photosynthetic mechanism and selecting for different microbial dominance. This, in turn, affects different treatment metrics in rectors at a different scale. No linear relationship was observed between reactor performance and increasing light intensity while density, porosity and permeability were found to be in the range of other granular biomass.
No spontaneous granulation has been recorded in conventional wastewater basins. We surmise that this could be due to a mismatch of conditions suppressing potential granulation. Altering the magnitudes of these o could potentially result in the formation of granular aggregates
Effects on mortality of a nutritional intervention for malnourished HIV-infected adults referred for antiretroviral therapy: a randomised controlled trial.
Malnourished HIV-infected African adults are at high risk of early mortality after starting antiretroviral therapy (ART). We hypothesized that short-course, high-dose vitamin and mineral supplementation in lipid nutritional supplements would decrease mortality
Discovery and Validation of Biomarkers to Guide Clinical Management of Pneumonia in African Children
Background
Pneumonia is the leading cause of death in children globally. Clinical algorithms remain suboptimal for distinguishing severe pneumonia from other causes of respiratory distress such as malaria or distinguishing bacterial pneumonia and pneumonia from others causes, such as viruses. Molecular tools could improve diagnosis and management.
Methods
We conducted a mass spectrometry–based proteomic study to identify and validate markers of severity in 390 Gambian children with pneumonia (n = 204) and age-, sex-, and neighborhood-matched controls (n = 186). Independent validation was conducted in 293 Kenyan children with respiratory distress (238 with pneumonia, 41 with Plasmodium falciparum malaria, and 14 with both). Predictive value was estimated by the area under the receiver operating characteristic curve (AUC).
Results
Lipocalin 2 (Lpc-2) was the best protein biomarker of severe pneumonia (AUC, 0.71 [95% confidence interval, .64–.79]) and highly predictive of bacteremia (78% [64%–92%]), pneumococcal bacteremia (84% [71%–98%]), and “probable bacterial etiology” (91% [84%–98%]). These results were validated in Kenyan children with severe malaria and respiratory distress who also met the World Health Organization definition of pneumonia. The combination of Lpc-2 and haptoglobin distinguished bacterial versus malaria origin of respiratory distress with high sensitivity and specificity in Gambian children (AUC, 99% [95% confidence interval, 99%–100%]) and Kenyan children (82% [74%–91%]).
Conclusions
Lpc-2 and haptoglobin can help discriminate the etiology of clinically defined pneumonia and could be used to improve clinical management. These biomarkers should be further evaluated in prospective clinical studies
A review of electroencephalograms done at the Kenyatta National Hospital, Nairobi
Background: Electroencephalogram based studies done elsewhere suggest that epileptiform activity originates predominantly from the left cortical hemisphere. There is evidence that partial epilepsies (focal spike and wave epileptiform discharges on tracings) connotes focal;secondary structural cortical dysfunction.Studies seeking similar findings have not been done locally.
Objective: To review electroencephalograms (BEGs) done at Kenyatta National Hospital (KNH); looking for various types of epileptiform discharges and their cerebral cortex of origin.
Design: Retrospective observational study.
Setting: Kenyatta National Hospital, Nairobi, Kenya- from January 1986 to June 2004
Results: A total10431EEG records were reviewed. Ninety Eight percent of referrals for EEG evaluation was for clinical differential diagnosis of epilepsy. AbnormalBEGs comprised 32.2% of the study population. Epileptiform abnormalities (i.e.focal spike and wave,generalized spike and wave and 3Hz spike and wave) discharges accounted for75.2% of all abnormal EEG waveform discharges.Of the epileptiform abnormalities, focal spike and wave discharges comprised 71%. Focal spike and wave discharge implies a possible secondary aetiology of epilepsy.The left cerebral hemisphere was the origin of 49.8% of focal spike and wave epileptiform EEG discharges. Multifocal loci in cerebral cortices (i.e. frontal, temporal and parietal) were the foci of origin of abnormal EEG waveforms in 69.9% of recordings.
Conclusion: Focal spike and wave epileptiform discharges, with attendant likely secondary aetiology of epilepsy is predominantly evident in this study. It contrasts findings from western literature.The left cerebral hemisphere is more epileptogenic as is noted in other studies
Activity Budget and Foraging Patterns of Nubian Giraffes (\u3cem\u3eGiraffa camelopardalis camelopardalis\u3c/em\u3e) in Lake Nakuru National Park, Kenya
How animals decide to spend their time has a key impact on their survival and reproduction. These behavioral decisions are shaped by ecological and environmental factors, such as seasonal changes. Foraging patterns show how an animal chooses to forage in its environment as influenced by resource availability, competition, and predation risk. Giraffe activity budget has been investigated in populations across Africa and found to be influenced by body size, diet composition, and sex. The activity budget and foraging patterns of Nubian giraffes vary considerably between ecosystems. The Nubian giraffe, a subspecies of the Northern giraffe species (Giraffa Camelopardalis) is a critically endangered population and occurs only within Kenya, Uganda, Ethiopia, and Southern Sudan. We performed 3 months of behavioral observation on a population of Nubian giraffes in Lake Nakuru National Park, Kenya, to assess seasonal activity budgets and foraging patterns. We found that in the wet and dry seasons giraffe spent approximately the same amount of time (53% and 57%, respectively) foraging. Movement and resting duration decreased slightly from dry to wet seasons 22% to 20% and 25% to 22% respectively. Across both seasons, Vachellia xanthophloea (67%), Maytenus senegalensis (19%), and Solanum incanum (9%) made up the bulk of giraffe\u27s diet. In the dry season, giraffes additionally foraged on Maerua triphylla (2%), Vachellia gerrardi (2%), and Grewia similis (1%); in the wet season, they added Vachellia abyssinica (2%) and Rhus natalensis (2%) to their diet. The most utilized browsing height was 3.5 meters (level 5), below their average height. Giraffes browse at lower heights after they consume the young shoots from the top of the bushes. Overall, seasonality did not appear to influence the Nubian giraffe\u27s activity budget or foraging patterns in LNNP. Planting perennial plants encourage uniform park resource use, boosts forage diversity, and minimizes Vachellia browsing pressure
Connecting Us Back to Ourselves: Aesthetic Experience as a Means to Growth after Trauma
This article examines the experience and effects of a trauma-responsive program that uses creative methods to address the ongoing psychosocial impacts of transgenerational trauma and youth suicide, which disproportionately affect First Nations people in Australia. Our aim is to understand how the aesthetic (sensory-affective) dimensions of such a program serve to promote experiences of growth after trauma, manifesting in a sense of connection to both self and community. The paper focuses on the second of two immersive, experiential workshops delivered seven months apart in the regional town of Warwick in Queensland, Australia. In the light of self-reports of growth and personal transformation following the initial workshop, the paper examines the key drivers of such growth, focusing in particular on how trauma-related experience is metabolised through cultural containment. It builds on Bion’s concept of container/contained, combining analysis of the affordances of immersion. Framed in cultural rather than medical terms, the larger goal of the paper is to establish how cultural programs fill a gap in trauma informed support, facilitating the processing of trauma
High boost-ratio bidirectional converter for interfacing low-voltage battery energy storage system to a DC bus
Supply and demand mismatches in renewable energy systems are addressed by integrating battery banks. Selecting battery bank terminal voltage to match DC-bus voltage (350–450 V for single-phase AC loads), necessitates employing battery banks with long-string connections along with their attendant shortcomings. To employ short-string battery banks, high-boost-ratio bidirectional interfaces are required between the DC-bus and battery bank. Current literature lacks a single source where high-boost-ratio converters’ are categorised and their strengths and weaknesses identified. Comprehensive literature review is hence carried out to determine attributes of various high-boost-ratio DC–DC converters and also categorise them. The key attributes of a topology to interface battery storage to a DC-bus are determined. Based on these a bidirectional tapped-inductor boost converter emerges as the best candidate. Moreover, in order to regulate output voltage, voltage-gain versus duty-ratio characteristics should not be very steep. Since battery terminal voltage varies with state-of-charge, closed-loop control is necessary. Converter's small-signal transfer-functions are derived and a two-loop controller to regulate output voltage and inductor current while allowing bidirectional power flow designed. A novel bidirectional passive lossless snubber circuit is employed to clamp the voltage spikes across the active switches, without altering the normal operation of the converter.https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=4475725hj2019Electrical, Electronic and Computer Engineerin
State of the climate in 2013
In 2013, the vast majority of the monitored climate variables reported here maintained trends established in recent decades. ENSO was in a neutral state during the entire year, remaining mostly on the cool side of neutral with modest impacts on regional weather patterns around the world. This follows several years dominated by the effects of either La Niña or El Niño events. According to several independent analyses, 2013 was again among the 10 warmest years on record at the global scale, both at the Earths surface and through the troposphere. Some regions in the Southern Hemisphere had record or near-record high temperatures for the year. Australia observed its hottest year on record, while Argentina and New Zealand reported their second and third hottest years, respectively. In Antarctica, Amundsen-Scott South Pole Station reported its highest annual temperature since records began in 1957. At the opposite pole, the Arctic observed its seventh warmest year since records began in the early 20th century. At 20-m depth, record high temperatures were measured at some permafrost stations on the North Slope of Alaska and in the Brooks Range. In the Northern Hemisphere extratropics, anomalous meridional atmospheric circulation occurred throughout much of the year, leading to marked regional extremes of both temperature and precipitation. Cold temperature anomalies during winter across Eurasia were followed by warm spring temperature anomalies, which were linked to a new record low Eurasian snow cover extent in May. Minimum sea ice extent in the Arctic was the sixth lowest since satellite observations began in 1979. Including 2013, all seven lowest extents on record have occurred in the past seven years. Antarctica, on the other hand, had above-average sea ice extent throughout 2013, with 116 days of new daily high extent records, including a new daily maximum sea ice area of 19.57 million km2 reached on 1 October. ENSO-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific had the largest impacts on the global sea surface temperature in 2013. The North Pacific reached a historic high temperature in 2013 and on balance the globally-averaged sea surface temperature was among the 10 highest on record. Overall, the salt content in nearsurface ocean waters increased while in intermediate waters it decreased. Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 mm yr-1 over the past two decades. A portion of this trend (0.5 mm yr-1) has been attributed to natural variability associated with the Pacific decadal oscillation as well as to ongoing contributions from the melting of glaciers and ice sheets and ocean warming. Global tropical cyclone frequency during 2013 was slightly above average with a total of 94 storms, although the North Atlantic Basin had its quietest hurricane season since 1994. In the Western North Pacific Basin, Super Typhoon Haiyan, the deadliest tropical cyclone of 2013, had 1-minute sustained winds estimated to be 170 kt (87.5 m s-1) on 7 November, the highest wind speed ever assigned to a tropical cyclone. High storm surge was also associated with Haiyan as it made landfall over the central Philippines, an area where sea level is currently at historic highs, increasing by 200 mm since 1970. In the atmosphere, carbon dioxide, methane, and nitrous oxide all continued to increase in 2013. As in previous years, each of these major greenhouse gases once again reached historic high concentrations. In the Arctic, carbon dioxide and methane increased at the same rate as the global increase. These increases are likely due to export from lower latitudes rather than a consequence of increases in Arctic sources, such as thawing permafrost. At Mauna Loa, Hawaii, for the first time since measurements began in 1958, the daily average mixing ratio of carbon dioxide exceeded 400 ppm on 9 May. The state of these variables, along with dozens of others, and the 2013 climate conditions of regions around the world are discussed in further detail in this 24th edition of the State of the Climate series. © 2014, American Meteorological Society. All rights reserved
Design and descriptive epidemiology of the Infectious Diseases of East African Livestock (IDEAL) project, a longitudinal calf cohort study in western Kenya
BACKGROUND: There is a widely recognised lack of baseline epidemiological data on the dynamics and impacts of infectious cattle diseases in east Africa. The Infectious Diseases of East African Livestock (IDEAL) project is an epidemiological study of cattle health in western Kenya with the aim of providing baseline epidemiological data, investigating the impact of different infections on key responses such as growth, mortality and morbidity, the additive and/or multiplicative effects of co-infections, and the influence of management and genetic factors. A longitudinal cohort study of newborn calves was conducted in western Kenya between 2007-2009. Calves were randomly selected from all those reported in a 2 stage clustered sampling strategy. Calves were recruited between 3 and 7 days old. A team of veterinarians and animal health assistants carried out 5-weekly, clinical and postmortem visits. Blood and tissue samples were collected in association with all visits and screened using a range of laboratory based diagnostic methods for over 100 different pathogens or infectious exposures. RESULTS: The study followed the 548 calves over the first 51 weeks of life or until death and when they were reported clinically ill. The cohort experienced a high all cause mortality rate of 16% with at least 13% of these due to infectious diseases. Only 307 (6%) of routine visits were classified as clinical episodes, with a further 216 reported by farmers. 54% of calves reached one year without a reported clinical episode. Mortality was mainly to east coast fever, haemonchosis, and heartwater. Over 50 pathogens were detected in this population with exposure to a further 6 viruses and bacteria. CONCLUSION: The IDEAL study has demonstrated that it is possible to mount population based longitudinal animal studies. The results quantify for the first time in an animal population the high diversity of pathogens a population may have to deal with and the levels of co-infections with key pathogens such as Theileria parva. This study highlights the need to develop new systems based approaches to study pathogens in their natural settings to understand the impacts of co-infections on clinical outcomes and to develop new evidence based interventions that are relevant
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