Optimization Design and Characterization of Helmholtz Coils

Earth’s magnetic field data from ground-based magnetometer observatories are important for studies related to geomagnetic storm. The absence of earth’s magnetic field data observatories results in a complex mysterious phenomena of the geomagnetic storm and remains as unexplained one. Magnetometer is used to monitor and record the earth’s magnetic field data at the geomagnetic observatory. It is also used to measure the three components of the field such as the horizontal component (H), the declination component (D), and the downward component (Z). Fluxgate magnetometer is contributing to the ongoing extensive research work dedicated to explanation of some of the complex phenomena related to the geomagnetic storm and solar terrestrial system. In order to examine the magnetic field sensing of a fluxgate sensor, a large area with uniform magnetic field is required. The advantage of having a large area is that it will allow easy access of the sensor during measurement. A laboratory design and characterization of Helmholtz coils is a better choice when Helmholtz coil with larger areas that are available in the market are very expensive. This paper presents the optimization design of Helmholtz coils to create magnetic fields, which could be used to null the earth’s magnetic field, calibrate magnetic sensors, and used for other experiments in which a controllable amount of uniform magnetic field is required. DOI: 10.7176/JIEA/9-4-05 Publication date:June 30th 201

Application of Firefly Optimization Algorithm to the Design and Characterization of Helmholtz Coils for Magnetic Field Sensor Calibration

This paper presents the application of Firefly Optimization Algorithm (FOA) to the design and characterization of Helmholtz coils to create homogenous magnetic field needed for calibrating magnetic field sensors and used for other experiments. Magnetometer is used to monitor and record the earth’s magnetic field data at the geomagnetic observatory. Earth’s magnetic field data from ground-based magnetometer observatories are important for studying geomagnetic storm. The absence of earth’s magnetic field data observatories results in a complex mysterious phenomenon of geomagnetic storm and remains as unexplained one. Fluxgate magnetometer is contributing to the ongoing extensive research work dedicated to the explanation of some of the complex phenomena related to geomagnetic storm and solar terrestrial system. In order to examine magnetic field sensing of a fluxgate sensor, a large area with uniform magnetic field is required. The advantage of having a large area is to allow easy access of the sensor during magnetic field measurements. A laboratory design and characterization of high quality Helmholtz coils is a better choice when Helmholtz coil with larger areas that are available in the market are very expensiv

Optimization Design and Development of Sensing Coil and Analog Signal Conditioning Electronics for Fluxgate Magnetometer Sensor

The design of fluxgate magnetometers is typically a nonlinear multi-objective optimization problem. Different objectives often conflict with each other, and sometimes an optimal Fluxgate Magnetometer Sensor (FMS) performance is difficult to achieve. The sensitivity of the sensor decreases with an increase of noise level while trying to reduce the sensor dimension. Hence, there is need for a systematic optimization approach for FMS design to find its optimum performance. The combined modified multi-objective Firefly Optimization Algorithm (FOA) and systematic optimization approach is suggested to improve FMS’s design in this research by simultaneously optimizing the sensitivity and noise of a FMS while the sensor core, pick-up coil, and detection circuit are minimized. The developed model allowed improved sensitivity of 86.65%, reduction of noise level by 59.97% while still keeping the sensor size small by 14.29%. Keywords: Fluxgate magnetometer sensor, noise, sensitivity, firefly optimization algorithm. DOI: 10.7176/ISDE/10-4-03 Publication date:May 31st 201

Haemodialysis practice in a resource–limited setting in the tropics

Background: Objective: To provide information on the challenges of haemodialysis in a resource limited setting in South-Western Nigeria.Methods: This is a 5 year audit of all haemodialysis sessions carried out at the renal unit of the Ladoke Akintola University Teaching Hospital  (LAUTECH), Osogbo, Nigeria.Results: A total of 225 patients were offered haemodialysis (HD) during this period with age range of 10 to 85 years (mean age of 49  years±16.25). There were 155 males and 70 females (male to female  ratio of 2.2:1). Chronic kidney failure accounted for 180 (80%) of the cases while acute kidney injury (AKI) constituted 45 (20%) of the cases offered haemodialysis. The sessions of HD in both cases ranged from 1 to 27 with an average of 3 sessions. Hypotension is still the commonest intradialytic complication at our setting while diabetic nephropathy is rapidly emerging as a major cause of end stage renal disease at our setting  requiring HD. As seen in other parts of the tropics sepsis, nephrotoxinsand pregnancy related cases still accounted for a large percentage of AKI cases requiring haemodialysis. Only three patients were able to afford haemodialysis support for more than three months.Conclusion: Haemodialysis still remains a veritable option in renal  replacement therapy. Problems encountered were similar to many other settings in the tropics. Intensive efforts should still be geared at preventing the risk factors for both acute kidney injury and chronickidney disease in our environment.Keywords: Haemodialysis, practice, tropics, Resource limite

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

Background: The EMPA KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population. Methods: EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110. Findings: Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5–2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62–0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16–1·59), representing a 50% (42–58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1). Interpretation: In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease. Funding: Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council