454 research outputs found

    Use of the South African Food Composition Database System (SAFOODS) and its products in assessing dietary intake data: Part II

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    A number of dietary research methodologies are available for the collection of quantitative dietary intake data. The methods most often used in South Africa include the 24-hour dietary recall, the quantitative food frequency questionnaire, and the dietary intake record. To quantify dietary intake, the information typically required includes the energy and nutrient composition of foods commonly consumed in South Africa. The South African Food Composition Database System (SAFOODS) and its products, e.g. the printed tables and software program FoodFinder3, provide the researcher with the tools to convert food intake data into energy and nutrient(s) intake. FoodFinder3 can be used for the nutrient analysis of the data. It also enables the user to export the data to MS Excel for further analysis and for importing the data into other statistical packages. Coding for the type and quantity of food consumed is required however before the data can be electronically analysed. The Food Quantities Manual of the Medical Research Council provides the necessary information for the conversion of food intake data recorded in household measures into grams of food. To ensure that the quality of the dataset is high, several steps have to be undertaken before statistical analysis and reporting of the data can take place. Appropriate statistical methods are required for the analysis of the data as nutrient intake data are often skewed. Using a standardised protocol, validated questionnaires and the South African Food Composition Database (SAFOOD) for the analysis of dietary intake data could make the pooling of data from small scale or regional studies possible. This may impart an impression of energy and nutrient intake at the national level, and could, at least in part, compensate for the absence of regular national surveys

    Prospects of N Fertilization in Medicinal Plants Cultivation

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    High global demand for plant-derived medicines is threatening the existence of many wild indigenous plant species. However, the high demand of medicinal plants has also created huge business opportunities in commercial farming of medicinal plants. Large-scale production of secondary metabolites by plants and medicinal materials will be crucial in the medicinal plant industry. As commercial cultivation of medicinal plants gains traction among farmers, N fertilizers will be increasingly used to enhance plant growth and yield. Therefore, the implementation of better nitrogen use efficiency is critically important. Excessive use of N can lead to many problems; it is costly, it can cause environmental pollution and its high levels in plant tissues can be toxic to plants, herbivores and humans. This chapter discusses the potential risks, opportunities and setbacks associated with the use of N in cultivation of medicinal plants

    Apparent Kondo effect in Moir\'e TMD bilayers: Heavy fermions or disorder?

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    A recent work by Zhao et al. [1] reports the realization of a synthetic Kondo lattice in a gate-tunable Moir\'e TMD bilayer system. The observation of a Kondo lattice is supported by a plateau (or dip, depending on filling) in the temperature dependence of the resistivity ρ(T)\rho(T) around T40 T^*\sim 40~K, which is interpreted as the Kondo temperature scale, and an apparent enhancement of carrier mass extracted from the low-temperature resistivity data, indicating the emergence of `heavy fermions'. The latter observation is crucially based on the assumption that the primary resistive scattering mechanism is Umklapp electron-electron scattering in the underlying Fermi liquid. In this work, we analyze the experimental data under the assumption that the primary resistive scattering mechanism is not electron-electron scattering, but Coulomb scattering by random quenched charged impurities and phonon scattering. We show that a combination of impurity and phonon scattering is a plausible alternative explanation for the observed resistivity that can describe the key features of the experimental data, even if no Kondo lattice has formed, indicating that further theoretical and experimental work is needed to conclusively verify the formation of a Kondo lattice in Ref. [1]. [1] W. Zhao, B. Shen, Z. Tao, Z. Han, K. Kang, K. Watanabe, T. Taniguchi, K. F. Mak, and J. Shan, arXiv:2211.00263 (2022).Comment: 7 pages, 4 figure

    Evaluation of savings from an underground fan replacement project

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    Abstract: The savings calculation methodology from a fan replacement project is presented in this paper. The fans replaced are part of the underground ventilation system in a platinum mine. Initially, 290 axial flow fans rated at 45kW were to be replaced with carbon fibre composite fans. According to the manufacturer, the carbon fibre construction allowed for an optimum blade shape which results in the carbon fibre fan being more energy efficient. However, after the first few fans were replaced, it was discovered that the mine’s blasting activities caused the carbon fibre fans to crack and eventually fail. Fortunately, the manufacturer was able to produce a steel fan with similar performance to that of the carbon composite fans and continue replacing old fans in the mine. The savings were independently verified according to the International Performance Measurement & Verification Protocol (IPMVP). This involved testing old and new fans in a BS848 test duct and comparing the old and new fans at various operating points on their fan curves and making adjustments for operating conditions such as air density underground vs at the test duct. It was found that the new fans saved 5kW on average, across a range of operating points

    Effects of pH and Phosphorus Concentrations on the Chlorophyll Responses of Salvia chamelaeagnea (Lamiaceae) Grown in Hydroponics

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    Salvia chamelaeagnea (Lamiaceae) is a slow growing water‐wise evergreen shrub originating from the western province of South Africa. It is an attractive landscape, and S. chamelaeagnea is a medicinal plant. It is important to develop enhanced cultivation protocols that could result in high yield and high‐quality medicinal materials. Chlorophyll is a fundamental part of the light‐dependent reactions of the photosynthesis process. This chapter investigates the effects of four phosphorus concentrations and three pH levels of supplied irrigated water on the production of chlorophyll A, chlorophyll B, total chlorophyll, leaf colour and the nutrient uptake of S. chamelaeagnea grown in hydroponics over an 8‐week period at the Cape Peninsula University of Technology. The treatments of pH 4, pH 6 and pH 8 at 31, 90, 150 and 210 ppm of phosphorus were received by 12 groups of plants and were replicated 10 times. The results indicated that at pH 4, P fertilization significantly (P < 0.05) induced a higher chlorophyll production of S. chamelaeagnea grown in hydroponics compared to other pH treatments (pH 8 and pH 6)

    Tracking mortality in near to real time provides essential information about the impact of the COVID-19 pandemic in South Africa in 2020

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    Background. Producing timely and accurate estimates of the impact of COVID-19 on mortality is challenging for most countries, but impossible for South Africa (SA) from cause-of-death statistics. Objectives. To quantify the excess deaths and likely magnitude of COVID-19 in SA in 2020 and draw conclusions on monitoring the epidemic in 2021. Methods. Basic details of deaths registered on the National Population Register by the Department of Home Affairs (DoHA) are provided to the South African Medical Research Council weekly. Adjustments are made to the numbers of weekly deaths to account for non-registration on the population register, as well as late registration of death with the DoHA. The weekly number of deaths is compared with the number predicted based on the Holt-Winters time-series analysis of past deaths for provinces and metropolitan areas. Excess deaths were calculated for all-causes deaths and natural deaths, using the predicted deaths as a baseline. In addition, an adjustment was made to the baseline for natural deaths to account for the drop in natural deaths due to lockdown. Results. We estimated that just over 550 000 deaths occurred among persons aged ≥1 year during 2020, 13% higher than the 485 000 predicted before the pandemic. A pronounced increase in weekly deaths from natural causes peaked in the middle of July across all ages except &lt;20 years, and across all provinces with slightly different timing. During December, it became clear that SA was experiencing a second wave of COVID-19 that would exceed the death toll of the first wave. In 2020, there were 70 000 - 76 000 excess deaths from natural causes, depending on the base. Using the adjusted base, the excess death rate from natural causes was 122 per 100 000 population, with a male-to-female ratio of 0.78. Deaths from unnatural causes halved for both males and females during the stringent lockdown level 5. The numbers reverted towards the predicted number with some fluctuations as lockdown restrictions varied. Just under 5 000 unnatural deaths were averted. Conclusions. Tracking the weekly numbers of deaths in near to real time has provided important information about the spatiotemporal impact of the pandemic and highlights that the ~28 000 reported COVID-19 deaths during 2020 substantially understate the death toll from COVID-19. There is an urgent need to re-engineer the system of collecting and processing cause-of-death information so that it can be accessed in a timely way to inform public health actions

    High resolution cw laser beam preamplified in a multipass cavity pumped by a CuHBr (HyBrID) laser

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    International audienceThe amplification of a cw high resolution (1 MHz) single-mode dye laser in a single-stage, multipass preamplifier based on a free flowing dye jet as amplifying medium is reported. The device is pumped by a homemade CuHBr laser (HyBrID laser) (18 kHz repetition rate, 30 ns pulse duration at half-maximum and 80 ns at its base) and yields pulses of duration of 10 ns (at half-maximum). In the studied pump energy domain, the gain is a linear function of pump energy and the maximum value obtained so far with pump energy of 400 μJ is 25 μJ per pulse for an input beam power of 30 mW. The corresponding gain is of the order of 10 4. We assume that a higher gain can be reached using better quality elements. The output beam is a high quality TM 00 mode. The pulse shapes of the pump beam and the output beam are compared and a phenomenological model ("switched photon lifetime") is introduced that reproduces our observations with a good agreement
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