Impact of Temperature Variation on the Coefficient of Thermal Expansion of Selected Rocks from South African Platinum Mines in an Unconfined Conditions

This paper presents the results of the study on the impact of temperature variation on the coefficient of thermal expansion of selected rocks from the South African platinum mines. These mines are witnessing increasing temperatures with higher depth due to high-temperature gradient. The experiment on the rock samples was done using a special set up comprising a variac, oven, digital thermometer, digital video extensometer, etc. under varying temperatures (20 to 140°C). The results of the laboratory tests. It is observed that the coefficient of linear thermal expansion increases with increasing temperature for all the samples. However, in comparison with other samples, chromitite has the lowest expansion coefficient. This was attributed to its lower strength and weak bond within the grain boundaries. The tests also show that temperature has an influence on the failure of crack generation and extension, which caused expansion of rocks. It is an indication that as mining depth increases in platinum mines, there is a possibility of an increase in tensile failure, which is not only a product of increased in-situ stresses but temperature. The future design of deeper and hotter mines would also hugely benefit from the knowledge of rock’s response to thermal stresses derived from laboratory tests. Keywords: Temperature testing, thermal expansion, platinum mines DOI: 10.7176/ISDE/10-4-02 Publication date:May 31st 201

PID controller for microsatellite yaw-axis attitude control system using ITAE method

The need for effective design of satellite attitude control (SAC) subsystem for a microsatellite is imperative in order to guarantee both the quality and reliability of the data acquisition. A proportional-integral-derivative (PID) controller was proposed in this study because of its numerous advantages. The performance of PID controller can be greatly improved by adopting an integral time absolute error (ITAE) robust controller design approach. Since the system to be controlled is of the 4th order, it was approximated by its 2nd order version and then used for the controller design. Both the reduced and higher-order pre-filter transfer functions were designed and tested, in order to improve the system performance. As revealed by the results, three out of the four designed systems satisfy the design specifications; and the PD-controlled system without pre-filter transfer function was recommended out of the three systems due to its structural simplicity, which eventually enhances its digital implementation

The Relationship between Adolescents' Family Background, Perceived Self-Concept and Health Seeking Behaviour in an Urban City of South-Western Nigeria

Background and objectives: The understanding of adolescents about themselves affects their choices and actions when their health is concerned. This study assessed the relationship between family background, perceived self-concept and health seeking behaviour of adolescents. Methods: This was a prospective cross-sectional study involving three secondary schools in Ekiti State, South-western Nigeria. A total of 352 students were recruited through multistage random sampling technique. The Personal Self-Concept Questionnaire (PSC) was used to assess the adolescents' personal self-concept while the health seeking behaviour was adapted from the Botsha Bophelo Adolescent Health Study (BBAHS) adapted questionnaire. The family background was sought from the respondents. Demographic variables were described as means and standard deviations. Categorical variables were reported as frequency distribution and proportions with the Pearson correlation test used to assess the relationship of relevant variables with self-concept. Results: There was negative correlation between the adolescents' family social class and their autonomy self-concept (r = -0.117; p<0.029). Out of the 42% who had any form of ill-health, 29.6% had sought for medical attention, 8.5% were sexually exposed, 4% and 4.8% were screened for HIV and the use of contraception respectively. Having been hospitalized in the past six months related with their general self-concept (r = -0.124; p<0.02) and sense of fulfillment (r = -0.118; p<0.027). Use of cannabis negatively correlated with general self-concept (r = -0.132; p<0.013) and honesty self-concept (r = -0.127; p<0.017). Sexual exposure correlated negatively with emotional self-concept (r = -0.116; p<0.03). Conclusion: From this study, the socioeconomic class of the family of the adolescents affected their individuality. In addition, adolescents with high self-concept will not easily seek for appropriate medical attentio

Paediatric brought-in-dead at a tertiary health facility in South western Nigeria: Patterns and drivers

Background: ‘Brought- in-dead’ (BID) refers to the demise of an individual before presentation to a health facility. This study assessed the pattern of paediatric BID cases seen at a tertiary health facility in southwest Nigeria. Method: A cross-sectional, descriptive study was done at the Children Emergency Ward (CEW) of the hospital between January 2014 and December 2018. The patterns of BID cases and presumed causes of death were determined using a standardized checklist adapted from the WHO verbal autopsy instrument. Results: Ninety-eight BID cases were seen during the study, constituting 2.5% of total patients seen during the period. The median (IQR) age of cases was 24.0 (8.75 – 63.0) months and 72.4% were under-fives. Most had symptoms related to the haematologic (36.7%), respiratory (24.5%) or digestive (20.4%) systems. Severe anaemia 31(31.6%), gastroenteritis 19 (19.4) and aspiration 17 (17.3%) were the most common causes of death. The median (IQR) duration of illness before presentation was 3.0 (1.0 – 7.0) days but most presented from 4 – 7 days of illness. A significant relationship was found between the duration of illness and whether or not pre-hospital treatment was received (p &lt; 0.0001). Unprescribed drugs purchased over the counter were the most commonly used treatment in 79.1% of cases (p &lt; 0.0001). Conclusion: This study has highlighted the prevalence and pattern of paediatric BID in a tertiary health facility in southwest Nigeria and the factors that were associated with it. More efforts need to be geared towards community sensitization and pediatric health care to prevent factors drivingits menace

Unification of Foreign Exchange Markets and Economic Growth

This research study delves into the intricate relationship between exchange rate unification and its implications for economic stability, with a specific focus on the Nigerian context. Exchange rate unification, the process of transitioning from multiple exchange rate systems to a single unified rate, holds the potential to reshape an economy's dynamics, affecting investor confidence, trade balances, and overall macroeconomic stability. Through a comprehensive examination of pre-unification and post-unification exchange rate data and gross domestic product data, this research uncovers patterns in currency valuation, volatility, and investor sentiment. The study employed secondary data gotten from the Central Bank of Nigeria statistical bulletin. The study explores the changes in the mean and variability of exchange rates, highlighting shifts in currency dynamics after the unification process. The study found that there are variations in the pre and post-unification era which has economic effect potentials. Also, the study evaluated the quarterly trend of GDP from the first quarter of 2022 to the first quarter of 2023. The result exhibits a mixed trend across various sectors, with the influence of the exchange rate unification potentially being a key driver in shaping these trends in 2023. The impact of unification on currency stabilization, international trade, and investor confidence may have contributed to the overall growth trend. The study recommends renewed exchange rate management strategies, investor communication approaches, export diversification tactics, fiscal resilience planning, and risk management techniques for businesses

Unification of Foreign Exchange Markets and Economic Growth

This research study delves into the intricate relationship between exchange rate unification and its implications for economic stability, with a specific focus on the Nigerian context. Exchange rate unification, the process of transitioning from multiple exchange rate systems to a single unified rate, holds the potential to reshape an economy's dynamics, affecting investor confidence, trade balances, and overall macroeconomic stability. Through a comprehensive examination of pre-unification and post-unification exchange rate data and gross domestic product data, this research uncovers patterns in currency valuation, volatility, and investor sentiment. The study employed secondary data gotten from the Central Bank of Nigeria statistical bulletin. The study explores the changes in the mean and variability of exchange rates, highlighting shifts in currency dynamics after the unification process. The study found that there are variations in the pre and post-unification era which has economic effect potentials. Also, the study evaluated the quarterly trend of GDP from the first quarter of 2022 to the first quarter of 2023. The result exhibits a mixed trend across various sectors, with the influence of the exchange rate unification potentially being a key driver in shaping these trends in 2023. The impact of unification on currency stabilization, international trade, and investor confidence may have contributed to the overall growth trend. The study recommends renewed exchange rate management strategies, investor communication approaches, export diversification tactics, fiscal resilience planning, and risk management techniques for businesses

Evaluation of the frequency scaling prediction techniques using experimental data

Long-term statistics of measured slant-path attenuation above Ku-band are severely scarce in the tropical climate; due to the huge capital costs involved in the experimental setup and receiver margin required, which is very difficult to obtain by using a spectrum analyzer. The received signal becomes masked at heavy rain rates owing to the high noise level therefore the signal level could not be monitored. Therefore the frequency scaling technique is a useful and powerful tool for estimating the attenuation at a desired frequency when the measurement data are available at a particular, usually lower, frequency. The results of measured rain attenuation from a tropical climate in Malaysia were used to investigate the performance of a few frequency scaling techniques. The experimental results were obtained from the four experimental microwave links (15, 22, 26, and 38 GHz at a separation distance of 300 m) installed at UTM campus, Johor Bahru, Malaysia. The results of the statistical analysis show that the ITU-R model is the most suitable for the lower frequency (26 GHz), while the Drufuca model is most suitable one for the higher frequency (38 GHz)

Validating a Proteomic Signature of Severe COVID-19

OBJECTIVES:. COVID-19 is a heterogenous disease. Biomarker-based approaches may identify patients at risk for severe disease, who may be more likely to benefit from specific therapies. Our objective was to identify and validate a plasma protein signature for severe COVID-19. DESIGN:. Prospective observational cohort study. SETTING:. Two hospitals in the United States. PATIENTS:. One hundred sixty-seven hospitalized adults with COVID-19. INTERVENTION:. None. MEASUREMENTS AND MAIN RESULTS:. We measured 713 plasma proteins in 167 hospitalized patients with COVID-19 using a high-throughput platform. We classified patients as nonsevere versus severe COVID-19, defined as the need for high-flow nasal cannula, mechanical ventilation, extracorporeal membrane oxygenation, or death, at study entry and in 7-day intervals thereafter. We compared proteins measured at baseline between these two groups by logistic regression adjusting for age, sex, symptom duration, and comorbidities. We used lead proteins from dysregulated pathways as inputs for elastic net logistic regression to identify a parsimonious signature of severe disease and validated this signature in an external COVID-19 dataset. We tested whether the association between corticosteroid use and mortality varied by protein signature. One hundred ninety-four proteins were associated with severe COVID-19 at the time of hospital admission. Pathway analysis identified multiple pathways associated with inflammatory response and tissue repair programs. Elastic net logistic regression yielded a 14-protein signature that discriminated 90-day mortality in an external cohort with an area under the receiver-operator characteristic curve of 0.92 (95% CI, 0.88–0.95). Classifying patients based on the predicted risk from the signature identified a heterogeneous response to treatment with corticosteroids (p = 0.006). CONCLUSIONS:. Inpatients with COVID-19 express heterogeneous patterns of plasma proteins. We propose a 14-protein signature of disease severity that may have value in developing precision medicine approaches for COVID-19 pneumonia