An Investigation of Students\u27 Use and Understanding of Evaluation Strategies

One expected outcome of physics instruction is that students develop quantitative reasoning skills, including evaluation of problem solutions. To investigate students’ use of evaluation strategies, we developed and administered tasks prompting students to check the validity of a given expression. We collected written (N\u3e673) and interview (N=31) data at the introductory, sophomore, and junior levels. Tasks were administered in three different physics contexts: the velocity of a block at the bottom of an incline with friction, the electric field due to three point charges of equal magnitude, and the final velocities of two masses in an elastic collision. Responses were analyzed using modified grounded theory and phenomenology. In these three contexts, we explored different facets of students’ use and understanding of evaluation strategies. First, we document and analyze the various evaluation strategies students use when prompted, comparing to canonical strategies. Second, we describe how the identified strategies relate to prior work, with particular emphasis on how a strategy we describe as grouping relates to the phenomenon of chunking as described in cognitive science. Finally, we examine how the prevalence of these strategies varies across different levels of the physics curriculum. From our quantitative data, we found that while all the surveyed student populations drew from the same set of evaluation strategies, the percentage of students who used sophisticated evaluation strategies was higher in the sophomore and junior/senior student populations than in the first-year population. From our case studies of two pair interviews (one pair of first years, and one pair of juniors), we found that that while evaluating an expression, both juniors and first-years performed similar actions. However, while the first-year students focused on computation and checked for arithmetic consistency with the laws of physics, juniors checked for computational correctness and probed whether the equation accurately described the physical world and obeyed the laws of physics. Our case studies suggest that a key difference between expert and novice evaluation is that experts extract physical meaning from their result and make sense of them by comparing them to other representations of laws of physics, and real-life experience. We conclude with remarks including implications for classroom instruction as well as suggestions for future work

SWOT Analysis of Information Security Management System ISO 27001

Information security is a main concern for many organisations with no signs of decreasing urgency in the coming years. To address this a structured approach is required, with the ISO 27000 series being one of the most popular practices for managing Information Security. In this work, we used a combination of qualitative research methods to conduct a SWOT analysis on the ISMS. The findings from the SWOT were then validated using a survey instrument. Finally, the results were validated and analysed using statistical methods. Our findings show that there was a generally positive view on the 'Strengths' and 'Opportunities' compared to that of 'Weaknesses' and 'Threats'. We identified statistically significant differences in the perception of 'Strengths' and 'Opportunities' across groups but also found that there is no significant variance in the perception of 'Threats'. The SWOT produced will help practitioners and researchers tailor ways to enhance ISMS using existing techniques such as TOWS matrix

Physicochemical Characterization of Limestone Deposits at Ewekoro, Ogun State, South-West of Nigeria and the Environment Impact

Limestone is the primary constituent raw material for cement manufacture. While most limestone deposits are suitable for cement making, there are some characteristics of limestone which need to be defined in order to establish a usable raw material supply.  These relate to compositional requirements and also the consistency of the deposit in chemical and physical terms. Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. The density and porosity of samples from the various locations vary from 2.61g/cm3 to 2.72g/cm3 and 2.70% to 3.80%. The Schmidt hammer rebound number of samples from Ewekoro quarry varies from 32.1 to 33.6. The uniaxial compressive strength of samples from Ewekoro quarry varies from 60.5 MPa to 63.5 MPa thereby classifying the rock as moderate to high strength. The point load strength index is obtained from the LAFARGE laboratory results and varies from 1.239 MPa to 2.185 MPa. The strength classifications fall within the range of moderate to high strength class. Also, the tensile strength, obtained from point load strength ranges from 1.862 MPa to 3.086 MPa. The staining process induces a reaction on the surface of a particular mineral species which results in coloured precipitate characteristic of that mineral. Alizarin red S in NaOH stained the samples purple indicating the presence of magnesium in the carbonate while Alizarin red S in HCL stained the samples red. Physical observation of Ewekoro limestone deposit reveal the rock is highly fossiliferous with the identified fossils indicating deposition in an open shelf environment. Moreover, the limestone deposit was equally observed to be principally mud supported which is indicative of rocks deposited in quiet water and a low energy environment. Keywords: Limestone, Solubility, Ewekoro, Physical and Chemical

Archetypes of remnant West African forest patches, their main characteristics and geographical distribution

Remnant West African forest patches provide crucial ecosystem functions and services while contributing to sustaining the livelihoods of vast numbers of people. The vast majority lie outside of protected areas, although relatively few are managed as sacred forests, which limits their access and use. This lack of protection, together with a growing demand for arable land and forest resources, have accentuated their fragmentation, degradation, and deforestation. There is therefore an urgent need to generate knowledge on their social-ecological characteristics and change pressures to support their conservation. This study investigates what are i) the main biophysical and social-ecological characteristics of remnant forest patches, and ii) the potential change pressures and drivers. Within this scope, we apply archetype analysis to discern processes affecting remnant forest patches. Biophysical and socio-ecological indicators were selected from a published dataset via expert consultation, and nine archetypes were developed by applying a cluster analysis. Evaluating the results in relation to ecoregions and landscape features using high resolution imagery, we identify common underlying social-ecological change pressures and characteristics. The most common archetype (2) is characterized by being close to protected areas and having a low average annual precipitation and cluster along the northern fringe of the study area. The second most common archetype (5) is characterized by lying in highly disturbed landscapes, having undergone biomass losses, and widely distributed throughout central and western Nigeria. Patches of archetype 8 found predominantly in mangrove and swamp forests, exhibit positive above-ground biomass changes and greening trends; we propose that these vegetation changes could benefit conservation measures and carbon sequestration programs. In contrast, archetype 10 patches show both forest and biomass losses and gains and are often encompass fragmented forests in urban/arable landscapes. Identifying such common patterns of anthropogenic and ecological change provides a means of prioritizing regionalized strategies for their conservation and sustainable use

Advances in Perovskite-Based Solar Cells

The increase in energy demand due to increase in population and reduction of fossil fuels has led to the search of alternative energy sources. Solar energy, which is an alternative source of energy, has been in the fore front of this research. Various methods of converting solar energy into electricity has been attained by silicon solar cells, thin film solar cells, dye sensitized solar cells and perovskite solar cells. Unlike dye sensitized solar cells, perovskite solar cells based on lead halide perovskite or organic-inorganic halide perovskite have had a significant impact on photovoltaic devices. A power conversion efficiency of approximately 20.1% has been attained by perovskite solar cells compared to organic solar cells. Also, several fabrication techniques, hole and electron transport materials have been developed for high performance. Although, some issues need to be addressed before commercialization is possible. Issues like stability of the cells under moisture and temperature. In this review, fundamental aspects of the perovskite device and recent breakthroughs are illustrate

A Remote Sensing-Based Inventory of West Africa Tropical Forest Patches: A Basis for Enhancing Their Conservation and Sustainable Use

The rate of tropical deforestation is increasing globally, and the fragmentation of remaining forests is particularly high in arable landscapes of West Africa. As such, there is an urgent need to map and monitor these remnant forest patches/fragments and so identify their multiple benefits and values. Indeed, recognizing their existence will help ensure their continued provision of ecosystem services while facilitating their conservation and sustainable use. The aim of this study is therefore to inventory and characterise the current extent and change of remnant forest patches of West Africa, using multi-source remote sensing products, time-series analyses, and ancillary datasets. Specifically, we collate and analyse descriptive and change metrics to provide estimates of fragment size, age, biophysical conditions, and relation to social-ecological change drivers, which together provide novel insights into forest fragment change dynamics for over four decades. We map forests patches outside protected areas with a tree cover ≥30%, a tree height of ≥5 m, an area ≥1 km2 and ≤10 km2. Appended to each patch are descriptive and change dynamics attributes. We find that most fragments are small, secondary forest patches and these cumulatively underwent the most forest loss. However, on average, larger patches experience more loss than smaller ones, suggesting that small patches persist in the landscape. Primary forest patches are scarce and underwent fewer losses, as they may be less accessible. In 1975 most patches were mapped as secondary, degraded forests, savanna, woodland, and mangrove, and relatively few comprised cropland, settlements, and agriculture, suggesting that new forest patches rarely emerged from arable land over the past 45 years (1975–2020), but rather are remnants of previously forested landscapes. Greening is widespread in larger secondary fragments possibly due to regrowth from land abandonment and migration to urban areas. Forest loss and gain are greater across fragments lying in more modified landscapes of secondary forests, while forest loss increases with distance to roads. Finally, larger forest patches harbour a denser tree cover and higher trees as they may be less impacted by human pressures. The number and extent of West African forest patches are expected to further decline, with a concurrent heightening of forest fragmentation and accompanying edge effects. Lacking any conservation status, and subject to increasing extractive demands, their protection and sustainable use is imperative

Non-Communicable Neurological Disorders and Neuroinflammation

Copyright \ua9 2022 Ballerini, Njamnshi, Juliano, Kalaria, Furlan and Akinyemi. Traumatic brain injury, stroke, and neurodegenerative diseases represent a major cause of morbidity and mortality in Africa, as in the rest of the world. Traumatic brain and spinal cord injuries specifically represent a leading cause of disability in the younger population. Stroke and neurodegenerative disorders predominantly target the elderly and are a major concern in Africa, since their rate of increase among the ageing is the fastest in the world. Neuroimmunology is usually not associated with non-communicable neurological disorders, as the role of neuroinflammation is not often considered when evaluating their cause and pathogenesis. However, substantial evidence indicates that neuroinflammation is extremely relevant in determining the consequences of non-communicable neurological disorders, both for its protective abilities as well as for its destructive capacity. We review here current knowledge on the contribution of neuroinflammation and neuroimmunology to the pathogenesis of traumatic injuries, stroke and neurodegenerative diseases, with a particular focus on problems that are already a major issue in Africa, like traumatic brain injury, and on emerging disorders such as dementias

Chemical Partitioning and Mobility of Trace Elements in Dry Disposed Weathered Ash Conditioned with High-Saline Effluents

Weinvestigated the mobility of inorganic elements in the ash dump due to chemical interaction of weathered dry disposed ash conditioned with high-saline effluents and ingressed CO2 from atmosphere and percolating rainwater. Drilled ash core samples collected from dry disposed ash dump at a South African coal-burning power station were characterized using X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses. A modified sequential extraction procedure was selected to determine the mineralogical association of the investigated elements in the 1-year-old drilled ash cores. Major mineral phases are quartz and mullite and other minor phases included hematite, lime, calcite, anorthite, mica, and enstatite. Mica and calcite in the ash cores is attributed to carbonation process, which led to long-term reduction in pore water pH. The 2-week-old ash cores are sialic but the 1-year-old ash cores were both sialic and ferrocalsialic in chemical composition. The ferrocalsialic nature of 1-year-old ash cores could be attributed to drastic changes in feed coal in the power station. The chemical index of alteration (CIA) and chemical index of weathering (CIW) values suggest a relatively high degree of weathering. The changes in CIA and CIW values in the ash cores depend on the pore water pH, leaching rate, carbonation process, and possibly the conversion of the alkali and alkali earth metals into carbonates. Multivariate analysis results suggest that the major oxides and carbon percent show differences and have a greater contribution to the differentiation in the 1-year-old ash cores. Trace elements such as Mo, Cr, and Se show high mobility but As, B, and Pb exhibit fairly low mobility in the water-soluble fraction. Aconsiderable mobility of trace elements in the exchangeable and carbonate fractions is attributed to the alkaline nature and pore water pH. A decreasing response of As, Mo, Cr, and Pb in the reducible fraction with depth suggests immobility attributed to coprecipitation with the Fe- and Mn-oxide phases. On the contrary, the increasing response of Pb, Mo, and B in the carbonate fraction with depth implies mobility due to dissolution and flushing of soluble major chemical phases, as evident in the pore water pH. A considerable amount of B and Pb are concentrated in the residual fraction of 1-year-old ash cores. This suggests that, under natural settings, these elements will not be released in solution over a long time; therefore, they are not considered to be an environmental risk

A Geochemical Analytical Scheme for the Appraisal of Partitioning and Mobility of Major elements in Weathered Dry Disposed Coal Fly Ash

South Africa is endowed with significant deposits of coal which is utilized in electricity generation to meet the nation’s energy demand. A large volume of waste solid residue from the combustion of pulverized feed coal in power stations is dry disposed in stock piles or dumps. Chemical interactions of dry disposed fly ash with ingressed CO2 from the atmosphere and infiltrating rain water would cause dissolution of the soluble components in the fly ash matrix. Chemical partitioning and mobility of major elements in samples from cores drilled into serially stacked weathered dry disposed fly ash were investigated using a modified five steps sequential extraction scheme. A total acid digestion was carried out on the original ash core samples prior to extraction to validate the extraction procedure. The geochemical distribution of the investigated major elements in 59 drilled core samples was determined by x-ray fluorescence and inductively coupled plasma mass spectrometry. The relationship between SiO2 and chemical index of alteration (CIA) showed 8 year and 20-year-old core samples have a moderate to high degree of weathering. Conversely, 1-year-old cores samples showed characteristics between low and moderate-high degrees of weathering. A cluster and discriminant analysis of the major elements was also able to reveal the subtle chemical alteration differences of the core samples. Functional analysis revealed the disparities in the dissolution patterns of major soluble components in the matrix of the drilled core samples. Modified sequential extractions revealed high concentration of the major species in the leachates for every mineralogical fraction; although the bulk of the major elements are locked up in the insoluble phase of the core samples (i.e. residual fraction) which would not be released under normal environmental conditions. It is noteworthy that the concentration of major elements in the labile fractions (water soluble + exchangeable + carbonate) was high and this has implications for the long-term durability of residual mineral phases. Relative enrichment and depletion trends of major elements are promoted by heterogeneity in the ash dump (i.e. moisture content), gradual reduction of pore water pH and continuous brine and water irrigation.Key words: Coal fly ash; Weathering; Sequential extraction scheme; Cluster analysis; Factor Analysis