25 research outputs found
Investigation of multi-phase tubular permanent magnet linear generator for wave energy converters
In this article, an investigation into different magnetization topologies for a long stator tubular permanent magnet linear generator is performed through a comparison based on the cogging force disturbance, the power output, and the cost of the raw materials of the machines. The results obtained from finite element analysis simulation are compared with an existing linear generator described in [1]. To ensure accurate results, the generator developed in [1] is built with 3D CAD and simulated using the finite-element method, and the obtained results are verified with the source.The PRIMaRE project
Investigation of a suspected diarrhoeal illness outbreak in Upington – ZF Mgcawu District, Northern Cape, South Africa, March – July 2015
Study of different mathematical approaches in determining the dynamic rating of overhead power lines and a comparison with real time monitoring data
Electricity generation is changing as new, renewable and smaller generation facilities are created, and classic topologies have to accommodate this distributed generation. These changes lead to the creation of smart grids in which advanced generation, information and communication technologies are needed.
Information metering is important, and one of the most important grid parameters to be measured and controlled is the temperature of overhead conductors due to their relation to the maximum allowable sag of the line.
The temperature and current of an overhead conductor and the weather conditions surrounding the cable are measured every 8 min for more than a year. With these data, the accuracies of the different algorithms presented in the standards (CIGRE TB601 and IEEE 738) are studied by implementing them in MATLAB®.
The use of precise measurements of solar radiation and low wind speeds with ultrasonic anemometers, improves the accuracy of the estimated temperature compared with the real measured conductor temperature. Additionally, using dynamic algorithms instead of assuming a steady state analysis increases the accuracy. However, an equilibrium between the accuracy and mathematical complexity should be obtained depending on the specific needs.This work was supported by the Spanish Government under the R+D initiative INNPACTO with reference IPT-2011-1447-920000 and Spanish R+D initiative with reference ENE2013-42720-
Epidemiologic Aspects of an Emerging Focus of Visceral Leishmaniasis in Tbilisi, Georgia
Visceral leishmaniasis (VL) has emerged as a public health problem in Tbilisi, the capital of Georgia. Dogs are the main infection reservoirs for transmission by sand flies of Leishmania infantum to humans, many of whom may become infected without developing disease. Since majority of cases are in children we were interested to know the rate of infection in children and in dogs living within the area where cases of VL have been found, and what factors may affect the risk of infection. Using a test that detects the presence of antibodies in blood as a marker of infection, 7.3% of 4,250 children examined were positive at the baseline survey, and 6% became positive after one year. Overall, 18.2% of domestic and 15.3% of stray dogs were seropositive. The infected children were more apt to live in areas where clustered flying insects and stray dogs were observed, and were far more likely to have experienced a persistent fever in the 6 months before the survey. We conclude that there is very active transmission of L. infantum to both humans and dogs in Tbilisi, and that children remain at high risk of developing clinical disease and sub-clinical infection
Adapting Agriculture to Climate Change: A Synopsis of Coordinated National Crop Wild Relative Seed Collecting Programs across Five Continents
The Adapting Agriculture to Climate Change Project set out to improve the diversity,
quantity, and accessibility of germplasm collections of crop wild relatives (CWR). Between 2013 and
2018, partners in 25 countries, heirs to the globetrotting legacy of Nikolai Vavilov, undertook seed
collecting expeditions targeting CWR of 28 crops of global significance for agriculture. Here, we
describe the implementation of the 25 national collecting programs and present the key results. A total
of 4587 unique seed samples from at least 355 CWR taxa were collected, conserved ex situ, safety
duplicated in national and international genebanks, and made available through the Multilateral
System (MLS) of the International Treaty on Plant Genetic Resources for Food and Agriculture (Plant
Treaty). Collections of CWR were made for all 28 targeted crops. Potato and eggplant were the most
collected genepools, although the greatest number of primary genepool collections were made for
rice. Overall, alfalfa, Bambara groundnut, grass pea and wheat were the genepools for which targets
were best achieved. Several of the newly collected samples have already been used in pre-breeding
programs to adapt crops to future challenges.info:eu-repo/semantics/publishedVersio
The importation and establishment of community transmission of SARSCoV- 2 during the first eight weeks of the South African COVID-19 epidemic
BACKGROUND : We describe the epidemiology of COVID-19 in South Africa following importation and during
implementation of stringent lockdown measures.
METHODS : Using national surveillance data including demographics, laboratory test data, clinical presentation,
risk exposures (travel history, contacts and occupation) and outcomes of persons undergoing COVID-19 testing
or hospitalised with COVID-19 at sentinel surveillance sites, we generated and interpreted descriptive
statistics, epidemic curves, and initial reproductive numbers (Rt).
FINDINGS : From 4 March to 30 April 2020, 271,670 SARS-CoV-2 PCR tests were performed (462 tests/100,000
persons). Of these, 7,892 (2.9%) persons tested positive (median age 37 years (interquartile range 28 49
years), 4,568 (58%) male, cumulative incidence of 13.4 cases/100,000 persons). Hospitalization records were
found for 1,271 patients (692 females (54%)) of whom 186 (14.6%) died. Amongst 2,819 cases with data, 489/
2819 (17.3%) travelled internationally within 14 days prior to diagnosis, mostly during March 2020 (466
(95%)). Cases diagnosed in April compared with March were younger (median age, 37 vs. 40 years), less likely
female (38% vs. 53%) and resident in a more populous province (98% vs. 91%). The national initial Rt was 2.08
(95% confidence interval (CI): 1.71 2.51).
INTERPRETATION : The first eight weeks following COVID-19 importation were characterised by early predominance
of imported cases and relatively low mortality and transmission rates. Despite stringent lockdown
measures, the second month following importation was characterised by community transmission and
increasing disease burden in more populous provinces.The South African governmenthttps://www.journals.elsevier.com/eclinicalmedicineam2022School of Health Systems and Public Health (SHSPH
Epidemiology of SARS-CoV-2 infection and SARS-CoV-2 positive hospital admissions among children in South Africa
INTRODUCTION : We describe epidemiology and outcomes of confirmed SARS-CoV-2 infection and positive admissions among children <18 years in South Africa, an upper-middle income setting with high inequality.
METHODS : Laboratory and hospital COVID-19 surveillance data, 28 January - 19 September 2020 was used. Testing rates were calculated as number of tested for SARS-CoV-2 divided by population at risk; test positivity rates were calculated as positive tests divided by total number of tests. In-hospital case fatality ratio (CFR) was calculated based on hospitalized positive admissions with outcome data who died in-hospital and whose death was judged SARS-CoV-2 related by attending physician.
FINDINGS : 315 570 children aged <18 years were tested for SARS-CoV-2; representing 8.9% of all 3 548 738 tests and 1.6% of all children in the country. Of children tested, 46 137 (14.6%) were positive. Children made up 2.9% (n = 2007) of all SARS-CoV-2 positive admissions to sentinel hospitals. Among children, 47 died (2.6% case-fatality). In-hospital deaths were associated with male sex [adjusted odds ratio (aOR) 2.18 (95% confidence intervals [CI] 1.08–4.40)] vs female; age <1 year [aOR 4.11 (95% CI 1.08–15.54)], age 10–14 years [aOR 4.20 (95% CI1.07–16.44)], age 15–17 years [aOR 4.86 (95% 1.28–18.51)] vs age 1–4 years; admission to a public hospital [aOR 5.07(95% 2.01–12.76)] vs private hospital and ≥1 underlying conditions [aOR 12.09 (95% CI 4.19–34.89)] vs none.
CONCLUSIONS : Children with underlying conditions were at greater risk of severe SARS-CoV-2 outcomes. Children > 10 years, those in certain provinces and those with underlying conditions should be considered for increased testing and vaccination.SUPPORTING INFORMATION : TABLE S1: Description of SARS-CoV-2 rRT-PCR positive children <18 years in South Africa, 1 March 2020–19 September 2020 (N = 45 609).
TABLE S2: Description of SARS-CoV-2 rRT-PCR positive hospital admissions among children <18 years in South Africa by province, 1 March 2020–19 September 2020 (N = 2007).
TABLE S3: Distribution of non-missing variables among children with complete follow up and included in multivariable model (N = 1817).
TABLE S4: Factors associated with in-hospital death among SARS-CoV-2 rRT-PCR positive admissions in children <18 years, South Africa, 1 March 2020–19 September 2020. FIGURE S1: Number of SARS-CoV-2 rRT-PCR tests*, percent positive tests and associated- hospital admissions among children <18 years by province and epidemiology week, South Africa, 1 March 2020–19 September 2020.National Department of Health, Republic of South Africahttp://wileyonlinelibrary.com/journal/irvhj2022School of Health Systems and Public Health (SHSPH
Labdane and Abietane Diterpenoids from <i>Juniperus oblonga</i> and Their Cytotoxic Activity
A phytochemical investigation of the whole plant of Juniperus oblonga led to the isolation of one previously undescribed labdane diterpenoid, (4R,5S,9S,10R)-13-des-ethyl-13-oxolabda-8(17),11E-dien-19-oic acid (1), together with nine known diterpenoids (2–3, 6–12), two lignans (4, 5), and a coumarin (13). The structures of all the compounds were elucidated on the basis of spectrometric data, primarily one-dimensional (1D)- and two-dimensional (2D)-NMR and mass spectrometry. Electronic circular dichroism (ECD) calculations determined the absolute configuration of 1. In addition, the isolated compounds were evaluated for their cytotoxic activity against three human tumor cell lines (HepG2, MCF-7, and HeLa). 6,12-Dihydroxyabieta-5,8,11,13-tetraen-7-one (6) showed moderate cytotoxicity against all three cell lines with IC50 values ranging from 24.41 μM to 58.39 μM and trilobinone (10) showed weaker activity with IC50 values ranging from 56.93 μM to 79.98 μM. None of the isolated diterpenoids have been previously reported from Juniperus oblonga, and five compounds are here reported from the genus Juniperus for the first time
What Is the Minimum Volume of Sample to Find Small Microplastics: Laboratory Experiments and Sampling of Aveiro Lagoon and Vouga River, Portugal
Small microplastics (<1 mm) comprise a great fraction of microplastics (<5 mm) found in the environment and are often overlooked due to the constrains of transporting and filtering large volumes of water in grab samplings. The objective of this work was to determine the minimum volume for reliable quantification of small microplastics in the environment. Different volumes (0.1, 0.25, 0.5, 1, 2.5 L) of laboratory spikes (fresh and saltwater) and environmental samples were filtered. Sampling volumes of 0.5 L or 1 L are a good compromise between drawbacks, such as effort, time, organic and mineral matter, potential contamination, and reliability of results, evaluated by interquartile range, accuracy, coefficient of variation, and recovery rates. Moreover, the observation of Nile Red-stained environmental samples under 470 nm produced six-times higher concentrations than samples under 254 nm, namely, 18 microplastics L−1 and 3 microplastics L−1 for the Aveiro Lagoon and 1 microplastics L−1 and 0 microplastics L−1 for the Vouga River, Portugal. This work also raises concerns about the underreporting of environmental concentrations of microplastics