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Power generation from fossil fuels is the biggest challenge in the next half of the century. Alternative power generation techniques such as solar photovoltaic (PV) show potential to act as a future fuel with a challenge to efficiently convert the harvested solar energy into electrical power. This investigation conclusively focused on setting a 2.160-kW solar PV system capable of working at a higher efficiency by developing a mechanical structure that optimizes power production and minimizes energy losses. In addition to that, solar PV system efficiencies at various tracking positions, performance coefficients during rainy and sunny days, and system degradation rates have also been investigated. The PVsyst v6.8 simulation tool was used to obtain the simulated results, which were compared with the actual experimental results. The parameters considered for the investigations include ambient temperature, irradiance, solar PV module surface temperature, solar PV voltage and current, wind velocity, and atmospheric turbidity. The solar PV system was evaluated based on two modes, namely, M1 (no tracking/fixed type) and M2 (manual tracking by changing the position of the solar PV system every hour). The predictive results obtained using PVsyst v6.8 concluded that total energy production from the installed system was 3,242 kWh/yr and 3,984 kWh/yr for M1 and M2, respectively. The performance ratio (PR), obtained from simulation, was 72% and 78% for M1 and M2, respectively, which was consistent with the experimental results, i.e., 70% and 72% for M1 and M2, respectively. Similarly, the power conversion efficiencies under standard temperature and conditions for both modes, simulated and experimental, were found to be 16.50% and 12.75%, respectively. The estimated degradation rate was observed in the range of -0.6% to -5.0%. [ABSTRACT FROM AUTHOR]

This research investigated the best economically viable power source with the least environmental impact and socially acceptable for the maize crop. Maize is one of the key economic crops in Pakistan. Solar-, electric-, and diesel-powered drip irrigation systems (DIS) were considered for comparative study. We selected 45 sites of maize crop to collect the data, with an area of 1–3 ha, from three divisions. For economic viability, the benefit:cost ratio, life cycle cost, and payback period were calculated, and CO2 emissions were calculated to assess the environmental impact. The SPSS model was used for one-way ANOVA followed by post hoc and chi-squared tests to check the significance level between all power sources. It was found that the B-C of electric power, solar, and diesel drip irrigation systems was 1.65, 1.52, and 1.44, respectively. Solar, diesel, and electricity power DIS have CO2 emissions of 0.02, 0.730, and 1.106 tons/ha, respectively. The research concludes that solar power and electric power are the best sources for the environment and economically, respectively. It is recommended that solar power DIS be subsidized, which will help to lower CO2 emissions and reduce the electricity shortfall in Pakistan. [ABSTRACT FROM AUTHOR]

Objective: To compare the sensitivity, specificity and Positive Predictive Value (PPV) of histology, Campylobacter-Like Organism (CLO) test, culture and 13C-Urea Breath Test (UBT) for the diagnosis of Helicobacter pylori infection., Design: Descriptive study., Place and Duration of Study: District Headquarter Hospital, Rawalpindi, Military Hospital, Rawalpindi and Pakistan Institute of Science and Technology (PINSTECH), Nilore, Islamabad from June 2002 to 2003., Patients and Methods: Three mucosal biopsy specimens were obtained during endoscopy of 90 symptomatic patients. Histology, CLO test and culture were performed on these specimens. Breath samples for 13C-UBT were collected and sent to RIAD, PINSTECH on the same day for isotope ratio mass spectrometry. For analysis purpose, each of the tests was fixed as the gold standard in turn and the others were then compared against it. In addition, any two as well as any three positive tests were then set as the gold standard and the other tests compared against them to calculate the sensitivity, specificity, accuracy and PPV of other tests., Results: Urea breath test had the highest sensitivity, ranging from 95 to 100%, against all the gold standards with specificity ranging from 55 to 100%, whereas the sensitivity of histological examination was around 98% but it had comparatively lower specificity (49-89%). The CLO test had a sensitivity range of 86-100% and specificity of 67-100%. Culture had the minimum sensitivity (59-70%) but had highest specificity (96-100%) against all the gold standards. Age and gender had no effect on p-value of each test or in combination., Conclusion: The urea breath test has shown the highest ability to detect the organism with 95-100% sensitivity in symptomatic individuals and specificity, which is comparable to other tests.