Browsing by Subject "Temperature"

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    Assessing the role of temperature and air pollution in exacerbating childhood asthma in Cape Town, South Africa
    (2022) Phakisi, Tshepo Kingsley; Rother, Hanna-Andrea; Godsmark, Christie Nicole; Weimann, Edda
    Childhood asthma is one of the most common chronic diseases worldwide, including in South Africa. There has been substantial evidence on the role of air pollution in asthma exacerbation but limited research on the role of climate change and how the interaction between climate change and air pollution is affecting childhood asthma, specifically in low and middle-income countries (LMICs). Temperature changes can be used as an effect of climate change to investigate the association between climate change, air pollution and childhood asthma. This study, therefore, used a case study approach aimed at examining the interaction between air pollution and temperature in exacerbating childhood asthma focusing on clinical data obtained from Red Cross War Memorial Children's Hospital, air quality data (City of Cape Town) and temperature data (South African Weather Services) for Cape Town, South Africa for three study years (2009, 2014 and 2019). The protocol (Part A) of the mini dissertation describes childhood asthma literature globally and in LMICs and specifically in South Africa. It also discusses the increasing incidences and prevalence of the disease and possible causes such as air pollution and climate change. Furthermore, it discusses the vulnerability of children to the exposure of interest, being air pollution (PM2.5, PM10, NO2 and O3) and climate change (i.e., temperature). Subsequently, the development of air quality standards is discussed, specifically concerning whether they consider the specific children's vulnerability to exposures. The protocol then describes the study population and methodologies for conducting this study. The journal ready article (Part B) presents the findings of the study. Spearman's correlation was used to measure the degree of association between temperature variables and air pollutants. The results indicated that diurnal temperature was associated with PM2.5 (r=0.579: p< 0.01) and PM10 (r=0.505: p< 0.01). A Poisson regression analysis was applied to evaluate the relationship between asthma exacerbation with air pollutants and temperature variables. In a univariate analysis there was a statistically significant relationship between asthma exacerbation and diurnal temperature for 2019, IRR=0.98 (95% CI,0.97 – 0.99) p< 0.05, maximum temperature 2014, IRR=0.99(95% CI, 0.98 - 1.00) p< 0.05 and for 2019, IRR=0.98(95% CI, 0.97 - 0.99) p< 0.01, average temperature 2014, IRR=0.99(95% CI, 0.98 - 1.00) p< 0.05 and for 2019, IRR=0.98(95% CI, 0.97 - 0.99) p< 0.01. Using a multivariate analysis there v of 110 was no significant relationship between childhood asthma exacerbation and air pollutants (PM10, NO2 and O3) except for PM2.5 IRR=0.12(95% CI, 0.01 - 0.81) p< 0.05. Diurnal temperature statistically significant childhood asthma predictor for 2009, IRR=1.02(95% CI, 1.00 - 1.05) p< 0.05 and for 2014, IRR=0.97(95% CI, 0.96 - 0.99) p< 0.01. Temperature increase, therefore, seems to be related to asthma exacerbation. More research is needed on the relationship between diurnal temperature, childhood asthma, and air pollutants to inform adaptation strategies. The findings of this study are important for the development of climate change and health adaptation and prevention strategies in South Africa, particularly in relation to heat adaptation. These findings are also relevant for the development of air quality guidelines and guidelines to address children, as the most vulnerable population to environmental health exposures. The appendices (Part C) present the analyses that were not included in the protocol (Part A) and article (Part B). These also include documents relating to the study such as ethics approval and permission to conduct research by different entities.
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    Can we determine when marine endotherms feed? A case study with seabirds
    (1992) WILSON, R; Cooper, J; Plötz, Joachim
    The International Society for Burns Injuries (ISBI) has published guidelines for the management of multiple or mass burns casualties, and recommends that 'each country has or should have a disaster planning system that addresses its own particular needs.' The need for a national burns disaster plan integrated with national and provincial disaster planning was discussed at the South African Burns Society Congress in 2009, but there was no real involvement in the disaster planning prior to the 2010 World Cup; the country would have been poorly prepared had there been a burns disaster during the event. This article identifies some of the lessons learnt and strategies derived from major burns disasters and burns disaster planning from other regions. Members of the South African Burns Society are undertaking an audit of burns care in South Africa to investigate the feasibility of a national burns disaster plan. This audit (which is still under way) also aims to identify weaknesses of burns care in South Africa and implement improvements where necessary.
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    Eclogite xenoliths from the Premier kimberlite, South Africa: Geochemical evidence for subduction origin
    (2006) Dludla, Siyanda; Le Roex, Anton P; Gurney, John J
    A suite of mantle eclogite hosted within the Premier kimberlite on the Kaapvaal craton can be classified on the basis of Na2O content in garnets as group I type, although textures are ambiguous. No accessory phases of note occur, but rutile and phlogopite are found in a few samples. Clinopyroxenes show variable light rare element (LREE) enrichment (La/Ybn = 2–48), and the garnets are strongly LREE depleted relative to chondrites (La/Ybn = <0.04). Four pyroxenite samples include both garnet clinopyroxenite and garnet orthopyroxenite; clinopyroxenes in these samples are strongly LREE enriched (La/Ybn = 57–65). Calculated equilibration temperatures of the eclogites range from 999 ± 32 to 1168 ± 14° C with an average temperature of 1102 ± 37° C, assuming a pressure of 50 kbar. Relative to a shield geotherm of 40mW/m2, these temperatures suggest a sampling depth of 135 to 165 km. A single, calcium-rich sample gives an equilibration temperature of 1296 ± 32° C at the same assumed pressure. Calculated equilibrium temperatures and pressures for the garnet pyroxenites are 887 to 987° C and 26 to 39 kbar (clinopyroxenite) and 1135 to 1156° C and 48 ± 2 kbar (orthopyroxenite). Reconstituted bulk rock compositions of the eclogites indicate the presence of low- and high-MgO groups. The MgO-poor eclogites (8 to10.5 weight % MgO) have jadeite-rich clinopyroxenes and except for lower silica contents are similar to mid-ocean ridge basalts in major element composition, with slight negative Euanomalies (Eu/Eu*=0.83 to 0.96), indicative of (low-P) plagioclase fractionation. The MgO-rich eclogites (13.6 to 18 weight % MgO) are similar in composition to oceanic gabbro. In combination the geochemical data suggest that the Premier eclogite suite represents a fragment of a once composite oceanic crustal section; the protolith to the low-MgO eclogites was recycled oceanic crustal layer two metabasalt, which experienced silicic melt loss during subduction; the protolith to the high-MgO suite was oceanic crustal layer three cumulate gabbro/pyroxenite.
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    H i kinematics, mass distribution and star formation threshold in NGC 6822, using the SKA pathfinder KAT-7
    (2017) Namumba, B; Carignan, C; Passmoor, S; de Blok, W J G
    We present high sensitivity H I observations of NGC 6822, obtained with the Karoo Array Telescope (KAT-7). We study the kinematics, the mass distribution and the star formation thresholds. The KAT-7 short baselines and low system temperature make it sensitive to large-scale, low surface brightness emission. The observations detected ∼ 23 per cent more flux than previous Australian Telescope Compact Array observations. We fit a tilted ring model to the H I velocity field to derive the rotation curve (RC). The KAT-7 observations allow the measurement of the rotation curve of NGC 6822 out to 5.8 kpc, ∼1 kpc further than existing measurements. NGC 6822 is seen to be dark matter dominated at all radii. The observationally motivated pseudo-isothermal dark matter (DM) halo model reproduces well the observed RC while the Navarro Frank-White DM model gives a poor fit to the data. We find the best-fitting mass-to-light ratio (M/L) of 0.12 ± 0.01 which is consistent with the literature. The modified Newtonian dynamics gives a poor fit to our data. We derive the star formation threshold in NGC 6822 using the H I and H α data. The critical gas densities were calculated for gravitational instabilities using the Toomre-Q criterion and the cloud-growth criterion. We found that in regions of star formation, the cloud-growth criterion explains star formation better than the Toomre-Q criterion. This shows that the local shear rate could be a key player in cloud formation for irregular galaxies such as NGC 6822.
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    The kinetics of ferrous-iron oxidation by Leptospirillum ferriphilum in continuous culture: the effect of temperature
    (Elsevier, 2009) Ojumu, T V; Hansford, G S; Petersen, J
    A typical bioleach heap is characterized by wide variation of temperature across the heap bed, leading to oxidation of target minerals occurring at different rates. Previous studies on the effect of temperature on the microbial oxidation of ferrous-iron were limited to a narrow range of temperatures (30–40 °C) near optimum conditions and mostly toAcidithiobacillus ferrooxidans. The kinetics of ferrous-iron oxidation by Leptospirillum ferriphilum were studied in continuous culture. In this paper we focus on the effect of temperature (18–45 °C) on these kinetics. The study was based on the assumption that the effect of temperature can be studied independently of other, equally important factors such as pH, dissolved salts, etc. and independent of the reactor context. The experimental data were correlated using both, a simplified ferric-iron inhibitory model and the Pirt Equation. The results showed that the maximum specific ferrous-iron oxidation rate, increased with increasing temperature to a maximum at 42 °C. This trend can be described adequately by the Arrhenius Equation with an activation energy, Ea of 34.46 kJ mol−1 and frequency factor,K0 of 1.05 × 107 mmol Fe2+(mmolC)−1 h−1. An increase in temperature slightly reduces the steady state carbon biomass in the reactor, while the apparent affinity constant, K′Fe2+ increases. The investigation further suggests that at low temperature (18 °C) and beyond the maximum temperature (42 °C), the culture cannot be sustained in a continuous mode. The maximum biomass yield followed a linear decline with increasing temperature, while cell maintenance on ferrous-iron followed a quadratic trend, although the small values indicates that it is not significant, as would be expected in continuous culture. The results indicate that L. ferriphilum is likely to perform optimally, at warm temperatures (25–42 °C) in heap bioleach operations before being taken over by thermophiles at higher temperatures.
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    Non-optimal apparent temperature and cardiovascular mortality: the association in Puducherry, India between 2011 and 2020
    (2023-02-08) Shrikhande, Shreya S; Pedder, Hugo; Röösli, Martin; Dalvie, Mohammad A; Lakshmanasamy, Ravivarman; Gasparrini, Antonio; Utzinger, Jürg; Cissé, Guéladio
    Background Cardiovascular diseases (CVDs), the leading cause of death worldwide, are sensitive to temperature. In light of the reported climate change trends, it is important to understand the burden of CVDs attributable to temperature, both hot and cold. The association between CVDs and temperature is region-specific, with relatively few studies focusing on low-and middle-income countries. This study investigates this association in Puducherry, a district in southern India lying on the Bay of Bengal, for the first time. Methods Using in-hospital CVD mortality data and climate data from the Indian Meteorological Department, we analyzed the association between apparent temperature (Tapp) and in-hospital CVD mortalities in Puducherry between 2011 and 2020. We used a case-crossover model with a binomial likelihood distribution combined with a distributed lag non-linear model to capture the delayed and non-linear trends over a 21-day lag period to identify the optimal temperature range for Puducherry. The results are expressed as the fraction of CVD mortalities attributable to heat and cold, defined relative to the optimal temperature. We also performed stratified analyses to explore the associations between Tapp and age-and-sex, grouped and considered together, and different types of CVDs. Sensitivity analyses were performed, including using a quasi-Poisson time-series approach. Results We found that the optimal temperature range for Puducherry is between 30°C and 36°C with respect to CVDs. Both cold and hot non-optimal Tapp were associated with an increased risk of overall in-hospital CVD mortalities, resulting in a U-shaped association curve. Cumulatively, up to 17% of the CVD deaths could be attributable to non-optimal temperatures, with a slightly higher burden attributable to heat (9.1%) than cold (8.3%). We also found that males were more vulnerable to colder temperature; females above 60 years were more vulnerable to heat while females below 60 years were affected by both heat and cold. Mortality with cerebrovascular accidents was associated more with heat compared to cold, while ischemic heart diseases did not seem to be affected by temperature. Conclusion Both heat and cold contribute to the burden of CVDs attributable to non-optimal temperatures in the tropical Puducherry. Our study also identified the age-and-sex and CVD type differences in temperature attributable CVD mortalities. Further studies from India could identify regional associations, inform our understanding of the health implications of climate change in India and enhance the development of regional and contextual climate-health action-plans.
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    Primary production in the Benguela ecosystem, 1999–2002
    (2009) Barlow, R; Lamont, T; Mitchell-Innes, B; Lucas, M; Thomalla, S
    Phytoplankton production was investigated throughout the whole Benguela ecosystem in winter 1999 and in summer 2002 during two four-week research cruises from Cape Town, South Africa, through Namibian waters to Namibe in southern Angola. Primary production ranged from 0.14–2.26 g C m−2 d−1 during June–July 1999 and from 0.39–8.83 g C m−2 d−1 during February–March 2002. Mean productivity values indicated that the Benguela ecosystem was twice as productive in summer than in winter. In 1999, most of the productivity occurred within a temperature range of 13.5–18 °C, whereas in 2002 elevated production was associated with temperatures of 14–22 °C. The relationship between primary production and chlorophyll a was good for winter 1999 but poor for summer 2002, suggesting that predicting primary production from chlorophyll a is not straightforward for the Benguela ecosystem.
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    Recent trends in the climate of Namaqualand, a megadiverse arid region of South Africa
    (2016) Davis, Claire L; Hoffman, M Timm; Roberts, Wesley
    Abstract Namaqualand is especially vulnerable to future climate change impacts. Using a high-resolution (0.5°x0.5°) gridded data set (CRU TS 3.1) and individual weather station data, we demonstrated that temperatures as well as frequency of hot extremes have increased across this region. Specifically, minimum temperatures have increased by 1.4 °C and maximum temperatures by 1.1 °C over the last century. Of the five weather stations analysed, two showed evidence of a significant increase in the duration of warm spells of up to 5 days per decade and a reduction in the number of cool days (TX10P) by up to 3 days per decade. In terms of rainfall, we found no clear evidence for a significant change in annual totals or the frequency or intensity of rainfall events. Seasonal trends in rainfall did, however, demonstrate some spatial variability across the region. Spatial trends in evapotranspiration obtained from the 8-day MOD16 ET product were characterised by a steepening inland-coastal gradient where areas along the coastline showed a significant increase in evapotranspiration of up to 30 mm per decade, most notably in spring and summer. The increase in temperature linked with the increases in evapotranspiration pose significant challenges for water availability in the region, but further research into changes in coastal fog is required in order for a more reliable assessment to be made. Overall, the results presented in this study provide evidence-based information for the management of climate change impacts as well as the development of appropriate adaptation responses at a local scale.
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    Seasonality in diabetes in Yaounde, Cameroon: a relation with precipitation and temperature
    (2016) Lontchi-Yimagou, Eric; Tsalefac, Maurice; Tapinmene, Leonelle Monique Teuwa; Noubiap, Jean Jacques N; Balti, Eric Vounsia; Nguewa, Jean-Louis; Dehayem, Mesmin; Sobngwi, Eugène
    Abstract Background Diabetes is a growing health concern in developing countries, with Cameroon population having an estimated 6% affected. Of note, hospital attendees appear to be increasing all over the country, with fluctuating numbers throughout the annual calendar. The aim of the study was to investigate the relationship between diabete hospitalization admission rates and climate variations in Yaounde. Methods A retrospectively designed study was conducted in four health facilities of Yaounde (Central Hospital, University teaching hospital, Biyem-Assi and Djoungolo District Hospitals), using medical records from 2000 to 2008. A relationship between diabetes (newly diagnosed diabetes patients or decompensated diabetics) hospitalization admissions and climate variations was determined using the “2000–2008” national meteorological database (precipitation and temperature). Results The monthly medians of precipitation and temperature were 154mm and 25 °C, respectively. The month of October received 239mm of precipitation. The monthly medians of diabetic admissions rates (newly diagnosed or decompensated diabetes patients) were 262 and 72 respectively. October received 366 newly diagnosed diabetics and 99 decompensated diabetics. Interestingly, diabetic hospitalization admissions rates were higher during the rainy (51 %, 1633/3232) than the dry season, though the difference was non-significant. The wettest month (October) reported the highest cases (10 %, 336/3232) corresponding to the month with the highest precipitation level (239mm). Diabetes hospitalization admissions rates varied across health facilities [from 6 % (189/3232) in 2000 to 15 % (474/3232) in 2008]. Conclusion Diabetes is an important epidemiological disease in the city of Yaounde. The variation in the prevalence of diabetes is almost superimposed to that of precipitation; and the prevalence seems increasing during raining seasons in Yaoundé.
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    Sensitivity of the atmospheric response to sea-surface temperature forcing in the South West Indian Ocean: A regional climate modelling study
    (2006) Hansingo, K; Reason, C J C
    The MM5 regional climate model has been used to investigate the sensitivity of the atmospheric response to sea-surface temperature (SST) forcing in the South West Indian Ocean. Two model runs were analysed and compared against each other; namely, one in which the model was forced by an observed warm SST anomaly during a summer season with above-average rainfall over southern Africa, and the other in which the model was forced with a smoothed representation of this anomaly but with the centre shifted closer to the east coast of South Africa. The latter experiment was motivated by correlation analyses between rainfall and SST and by previous experiments with coarser-resolution global circulation models, which suggest that the model response over the land is larger if the SST forcing is shifted closer to it. Analysis of the differences in the model response between the two runs suggests that, consistent with the global models, the MM5 response is indeed larger over southern Africa and more conducive to above-average rainfall in the experiment with the smoothed and westward shifted SST forcing. Increased evaporation over the South West Indian Ocean, local uplift and enhanced moisture flux westwards into southern Africa (as well as southwards over the land from the equatorial region) all play a role in enhancing the regional atmospheric conditions favourable for rainfall over a large area of southern Africa during the season simulated