Physics

Particle precipitation involves the injection of energetic particles into the ionosphere which could increase the ionisation and conductivity of the upper atmosphere. The goal of this study was to examine the ionospheric response and changes due to particle precipitation in the region over South Africa, using a combination of groundbased and satellite instruments. Particle precipitation events were identified from satellite particle flux measurements of the Defence

1] The extreme ultraviolet (EUV) imager on the IMAGE satellite provided the first global images of the plasmasphere leading to enhanced understanding of plasmapause structure and dynamics. However, few studies have investigated the structure and dynamics of the inner plasmasphere (regions interior to the plasmapause), which previous in situ observations have shown to often be highly structured. This study is the first to systematically analyze global images of the density structure of the inner plasmasphere by using data from the EUV imager on the IMAGE satellite. We find that the inner plasmasphere exhibits both fine and meso-scale structure characterized by rapid density fluctuations and density enhancements of varying amplitudes (factors of 2-5) and spatial scales (from 10 s of minutes to 6 hours MLT) that occur regularly in the aftermath of geomagnetic storms. The level of variability within the azimuthal structure was found to increase with increasing geomagnetic activity. The observations suggest that some meso-scale azimuthal density structure observed in the inner plasmasphere is from "fossil" plasmapause features entrained inside the expanding and refilling plasmasphere. Citation: Sibanda, P., M. B. Moldwin, D. A. Galvan, B. R. Sandel, and T. Forrester (2012), Quantifying the azimuthal plasmaspheric density structure and dynamics inferred from IMAGE EUV,

Nano-size thin films comprising poly (3-hexylthiophene) (P3HT) and a fullerene derivative [6, 6] phenyl- C61-butyric acid methyl ester (PCBM) incorporating squarylium dye III (SQ3) are reported. The materials prepared were evaluated for their optical, electrical and photo-conversion efficiency. Active layer materials comprising a blend of P3HT:SQ3:PCBM were deposited by spin-coating to produce thin films measuring 100 nm and subsequently annealed at 140°C for 10 min. The films were characterized by UVVis- NIR spectroscopy for their optical properties, atomic force microscopy for surface morphology and film thickness, and electrical properties. Optical measurements for blends incorporating different amounts of dye showed increased photo-absorbance with increasing dye concentration. The combined contribution of SQ3 and thermal annealing resulted in increased power conversion efficiency (η) of pristine P3HT:PCBM solar cells from 1.9 to 3.9 %. The dye in the active layer improved photo-...

The initial development of pitayas may be limited by a few factors, among them, water deficit. Agricultural hydrogels can be used as an alternative to enhance the retention and availability of water and nutrients in the soil. Therefore, this study aimed to evaluate the influence of irrigation frequency and hydrogel doses on the development of white pitaya (Hylocereus undatus) seedlings to establish a time interval in days between irrigations that provides better seedling development and determine the hydrogel dose that provides a reduction of water consumption without damaging seedling development. The experimental design consisted of randomized blocks in a 4 x 4 factorial arrangement, in which the treatments corresponded to 4 hydrogel doses (0, 2, 4, and 6 g/plant of Biogel Hidro Plus) incorporated into the substrate and four irrigation frequencies (1, 3, 5, and 7 days of interval). The biometric characteristics, photosynthetic pigments, and organic and inorganic solutes of the pla...

The importance of the pattern of energy production, conversion and consumption in ensuring sustainable development necessitates stock taking of national energy supplies and demands so as to enable adequate policy formulation. In this paper, the state of energy resources, supply and demand in Zambia is described and analysed. Wood, the only non-commercial energy resource, constitutes 66% of the energy consumed in the country through its use as firewood in rural areas and as charcoal in urban areas. Hydropower with an existing installed capacity of 1670 MW supplies 94% of the country's electricity and meets 13% of the national energy demand. Shares of electrical energy consumed in mining, industry, household, government and agriculture sectors are 72%, 10%, 8%, 7% and 3%, respectively. With average annual output of about 470,000 tons and vast reserves of over 80 million tons, coal is also abundant and meets 9% of the national energy demand. Mining and industry have nearly equal share to account for over 90% of the domestic coal consumption. Petroleum contributes 12% of the energy demand and is fully imported. Its share in transportation, mining, industry, household, agriculture and services sectors is 49%, 27%, 14%, 4%, 3% and 3%, respectively. With annual average sum of solar radiation mounting to 7.1 GJm 2 for Zambia, solar energy potential is high but scantly exploited. The same is the ease with biomass. Wind potential is weak as the average wind speed is 2.5 ms 1. Photovoltalc power is being put to some practical applications. While hydropower will continue to remain the mainstay of Zambian electricity supplies, renewable energy sources need to be exploited for applications in remote areas.

The importance of the pattern of energy production, conversion and consumption in ensuring sustainable development necessitates stock taking of national energy supplies and demands so as to enable adequate policy formulation. In this paper, the state of energy resources, supply and demand in Zambia is described and analysed. Wood, the only non-commercial energy resource, constitutes 66% of the energy consumed in the country through its use as firewood in rural areas and as charcoal in urban areas. Hydropower with an existing installed capacity of 1670 MW supplies 94% of the country's electricity and meets 13% of the national energy demand. Shares of electrical energy consumed in mining, industry, household, government and agriculture sectors are 72%, 10%, 8%, 7% and 3%, respectively. With average annual output of about 470,000 tons and vast reserves of over 80 million tons, coal is also abundant and meets 9% of the national energy demand. Mining and industry have nearly equal share to account for over 90% of the domestic coal consumption. Petroleum contributes 12% of the energy demand and is fully imported. Its share in transportation, mining, industry, household, agriculture and services sectors is 49%, 27%, 14%, 4%, 3% and 3%, respectively. With annual average sum of solar radiation mounting to 7.1 GJm 2 for Zambia, solar energy potential is high but scantly exploited. The same is the ease with biomass. Wind potential is weak as the average wind speed is 2.5 ms 1. Photovoltalc power is being put to some practical applications. While hydropower will continue to remain the mainstay of Zambian electricity supplies, renewable energy sources need to be exploited for applications in remote areas.

Recently, we have shown how the interpretation of quantum mechanics due to Lande' can be used to derive from first principles generalized formulas for the operators and some eigenvectors for spin 1/2 Though we gave the operators for all the components of the spin, we did not give the eigenvectors of the operators for the x and y components of the spin. We now give these vectors. In addition, we present a new and simple method of deriving the operators for the x and y components of the spin as well as their vectors from those for the z component. We give a general proof that the operator for the square of the spin is the unit matrix multiplied by the value of the square of the spin.

A simpli®ed one dimensional analytical model to describe the altitude variation of aerosol number densities in the atmospheric boundary layer during clear sky and calm/moderate wind conditions, over a plane terrain on the tropical seacoast, is developed. The analytical model is mainly de®ned by two parameters, the aerosol mixing height and the exponential rate of decrease above the mixing height. The eect of surface impaction is also taken into account in this model. It is seen that this parameter varies with season. By matching the analytical pro®le with the observed mean pro®le in each month, the surface source strength has been estimated. The seasonal and inter-annual variations of this parameter are studied.

The study focused on assessing Physics students' perceptions towards E-learning amidst COVID-19 pandemic. Materials and Methods: This study used a Cross-Sectional design through an online survey and was conducted at the Lusaka Apex Medical University. A sample size of 210 students was purposively sampled and a questionnaire was used to collect data. Microsoft Excel 2013 was used to analyze the data and descriptive statistics was used to report frequencies and proportions of responses on the level of knowledge of learners towards E-learning, E-learning experiences of the students and pros and cons of E-learning. Results: The study reported that 97.9% of the students were aware of E-learning and only 2.1% did not have an idea about it. Most of the students had a positive E-learning perception with few barriers such as gender, internet access and domestic activities. The students perceived E-learning to be convenient for lessons, ease submission of assignments and readily available online learning resources. On the other hand, students were not in favor of online laboratory and tutorial lessons. Additionally, social isolation and financial constraints during the pandemic had a negative impact on students' E-learning experience. Conclusion: The study concluded that E-learning is possible provided that investment in internet infrastructure and training of instructors and students on its usage is done robustly. Future research is required to ascertain the actual factors that make gender a disadvantage when it comes to E-learning experiences as suggested by the minority of the students. In addition, similar studies can be conducted in other disciplines and Universities to validate the findings of this study.