Sensitivity analysis of EUROSEM using Monte Carlo simulation II::the effect of rills and rock fragments

A sensitivity analysis of the surface and catchment characteristics in the European soil erosion model (EUROSEM) was carried out with special emphasis on rills and rock fragment cover. The analysis focused on the use of Monte Carlo simulation but was supplemented by a simple sensitivity analysis where input variables were increased and decreased by 10%. The study showed that rock fragments have a significant effect upon the static output parameters of total runoff, peak flow rate, total soil loss and peak sediment discharge, but with a high coefficient of variation. The same applied to the average hydrographs and sedigraphs although the peak of the graphs was associated with a low coefficient of variation. On average, however, the model was able to simulate the effect of rock fragment cover quite well. The sensitivity analysis through the Monte Carlo simulation showed that the model is particularly sensitive to changes in parameters describing rills and the length of the plane when no rock fragments are simulated but that the model also is sensitive to changes in the fraction of non-erodible material and interrill slope when rock fragments were embedded in the topsoil. For rock fragments resting on the surface, changes in parameter values did not affect model output significantly. The simple sensitivity analysis supported the findings from the Monte Carlo simulation and illustrates the importance when choosing input parameters to describe both rills and rock fragment cover when modelling with EUROSEM

Applying Stage-Based Theory to engage female students in university sport

Purpose: University sport is recognized by many as a key area of university business and one of increasing importance, as seen by universities prioritizing sport within their university strategic plans as well as national funding bodies investing in university sport. Whilst sport is rising on the agenda, engaging all students in sport is a key challenge for universities. This paper examines the factors that enable and inhibit female students’ participation in university sport and active recreation using an interpretivist qualitative design. The paper also identified specific behaviour change techniques that could be used within interventions to increase participation rates. Method: Six focus groups were carried out. Data were analysed verbatim using a constant comparative process of analysis. Results: Findings revealed several emergent themes to help inform theory-based interventions to engage more female students in sport. Conclusion: University sport is an important behaviour for students to undertake. The paper identified a number of avenues for universities to pursue in order to achieve this aim

Separation of Oil From a Brackish Water Stream

In the past 40 years, a variety of enhanced oil recovery (EOR) methods have been developed and applied to mature and mostly depleted oil reservoirs. Chemical and sonic stimulation are two enhanced oil recovery methods in which emulsions are created either as a primary or secondary effect. The resulting emulsion viscosity is considerably lower than that of dry crude thus increasing permeability of and recovery from pay zones. During Chemical enhanced oil recovery, caustic or preformed surfactants are injected into oil reservoirs, which results in flooding and periodic breakthrough of stable oil-water emulsions. The emulsions from chemical enhanced oil recovery floods can be very stable, and as such, traditional demulsifiers are often not effective on these emulsions. When considering alternatives for oil-in-water demulsification, there are various options that can be considered. The use of pH manipulation was investigated, however the addition of harsh chemicals is not ideal and only mildly effective. Multiple effect evaporation will produce potable water; however, the energy and capital costs are high. Another option is to use centrifugal separation, which is capable of achieving high degrees of separation but it is energy and capital intensive. Coalescence, which was investigated, is particularly attractive because of its simplicity and efficacy. Ultrafiltration, also investigated, is highly effective at producing oil free brackish water but cannot produce a pure oil stream. Due to the low concentration (~ 200 ppm) of oil in the feed, ultrafiltration was paired with coalescence to produce a brine free of dispersed phase oil and a marketable oil stream. The WERC task statement specifies a high degree of removal of oil from the brackish water stream. The full-scale process will be robust, remove all of the dispersed oil from a 100 gpm feed stream, and produce oil with low water content, preferably marketable. Laboratory work produced brackish water filtrate free of any dispersed oil and produced an oil phase substantially free of water, deemed marketable. Additionally sonication was used very successfully to produce an oil in water emulsion with an average droplet size \u3c 6.0 microns. The full-scale UF/Coalescence process was designed to be highly mobile to satisfy the transient nature of the fraccing industry. The capital cost for this process to separate all the entrained oil from the oil in water dispersion is $250,000 and the operating costs are less than$20,000/year, excluding any additional operating labor. At 8,000 hrs/year of operation, 4 operators will be required, incurring an added annual operating cost of $200,000 to$250,000

Effects of Freezing on Soil Temperature, Freezing Front Propagation and Moisture Redistribution in Peat: Laboratory Investigations

There are not many studies that report water movement in freezing peat. Soil column studies under controlled laboratory settings can help isolate and understand the effects of different factors controlling freezing of the active layer in organic covered permafrost terrain. In this study, four peat Mesocosms were subjected to temperature gradients by bringing the Mesocosm tops in contact with subzero air temperature while maintaining a continuously frozen layer at the bottom (proxy permafrost). Soil water movement towards the freezing front (from warmer to colder regions) was inferred from soil freezing curves, liquid water content time series and from the total water content of frozen core samples collected at the end of freezing cycle. A substantial amount of water, enough to raise the upper surface of frozen saturated soil within 15 cm of the soil surface at the end of freezing period appeared to have moved upwards during freezing. Diffusion under moisture gradients and effects of temperature on soil matric potential, at least in the initial period, appear to drive such movement as seen from analysis of freezing curves. Freezing front (separation front between soil zones containing and free of ice) propagation is controlled by latent heat for a long time during freezing. A simple conceptual model describing freezing of an organic active layer initially resembling a variable moisture landscape is proposed based upon the results of this study. The results of this study will help in understanding, and ultimately forecasting, the hydrologic response of wetland-dominated terrain underlain by discontinuous permafrost

The effects of minimal tillage, contour cultivation and in-field vegetative barriers on soil erosion and phosphorus loss.

Runoff, sediment, total phosphorus and total dissolved phosphorus losses in overland flow were measured for two years on unbounded plots cropped with wheat and oats. Half of the field was cultivated with minimum tillage (shallow tillage with a tine cultivator) and half was conventionally ploughed. Within each cultivation treatment there were different treatment areas (TA). In the first year of the experiment, one TA was cultivated up and down the slope, one TA was cultivated on the contour, with a beetle bank acting as a vegetative barrier partway up the slope, and one had a mixed direction cultivation treatment, with cultivation and drilling conducted up and down the slope and all subsequent operations conducted on the contour. In the second year, this mixed treatment was replaced with contour cultivation. Results showed no significant reduction in runoff, sediment losses or total phosphorus losses from minimum tillage when compared to the conventional plough treatment, but there were increased losses of total dissolved phosphorus with minimum tillage. The mixed direction cultivation treatment increased surface runoff and losses of sediment and phosphorus. Increasing surface roughness with contour cultivation reduced surface runoff compared to up and down slope cultivation in both the plough and minimum tillage treatment areas, but this trend was not significant. Sediment and phosphorus losses in the contour cultivation treatment followed a very similar pattern to runoff. Combining contour cultivation with a vegetative barrier in the form of a beetle bank to reduce slope length resulted in a non-significant reduction in surface runoff, sediment and total phosphorus when compared to up and down-slope cultivation, but there was a clear trend towards reduced losses. However, the addition of a beetle bank did not provide a significant reduction in runoff, sediment losses or total phosphorus losses when compared to contour cultivation, suggesting only a marginal additional benefit. The economic implications for farmers of the different treatment options are investigated in order to assess their suitability for implementation at a field scale

Improved synchronous production of Plasmodium falciparum gametocytes in vitro.

The sexual stages of the Plasmodium falciparum life cycle are attractive targets for vaccines and transmission blocking drugs. Difficulties in culturing and obtaining large amounts of sexual stage P. falciparum parasites, particularly early stages, have often limited research progress in this area. We present a new protocol which simplifies the process of stimulating gametocytogenesis leading to improved synchronous gametocyte production. This new method can be adapted to enrich for early stage gametocytes (I and II) with a higher degree of purity than has previously been achieved, using MACS magnetic affinity columns. The protocol described lends itself to large scale culturing and harvesting of synchronous parasites suitable for biochemical assays, northern blots, flow cytometry, microarrays and proteomic analysis

The Depression, Anxiety, and Stress of Student-Athletes from a Pre- to Post-COVID-19 World

This study explored differences in student-athletes’ symptoms of depression, anxiety, and stress pre- to post-COVID-19-pandemic. The WHO reported a 25% increase in depression and anxiety rates worldwide, with young people disproportionately affected. Student-athletes face many stressors related to their sporting and academic feats, but what is not known is how the COVID-19 pandemic affected their experiences of symptoms of mental illness. A multiple-cohort cross-sectional study design was employed, and data collected using physical and online surveys. Participants (cohort 1 M age = 20.18 years, SD = 1.52; cohort 2 M age = 19.75 years, SD = 1.45) were recruited from UK universities (N = 807; 427 pre-pandemic cohort, 380 post-pandemic cohort). Results revealed statistically significant differences in mean depression (F (1, 805) = 23.92, p < 0.001), anxiety (F (1, 806) = 20.15, p < 0.001), and stress symptoms (F (1, 805) = 5.24, p = 0.022) scores between cohorts. Scores for the post-pandemic cohort were significantly higher than pre-pandemic, suggesting a worsening of symptom severity. Distributions of student-athletes across categories of symptom severity also worsened for depressive and anxiety symptoms post-pandemic and were skewed towards more severe categories. Symptoms of depression, anxiety, and stress were a concern pre-pandemic. Rates are higher in the post-pandemic cohort, suggesting a worsening of symptoms. These data add to evidence on student-athletes’ symptoms of mental illness by exploring a UK sample and comparing scores pre- and post-pandemic

Adding value to numerical weather predictions for the aviation industry in South Africa.

The main objective of this study is to determine whether human forecasters at the main airports of South Africa add value to the raw numerical weather prediction model output when they provide forecast services to the aviation industry. Dataset pairs of weather observations made at these airports and terminal aerodrome forecasts are constructed for three forecast systems: the human forecasters, persistence forecast and the raw output from the 12 km resolution Unified Model administered by the South African Weather Service. These three dataset pairs are independently evaluated by a forecast verification system developed at the South African Weather Service. A Monte Carlo method is used to determine the significance of the verification results obtained from calculating the proportion correct, hit rate, false alarm ratio, critical success index, Heidke skill score and the Pierce skill score of the various forecasts. In general, it is found that the forecaster-adapted forecasts are superior to the raw model output, thus providing evidence that the aviation industry may benefit most from forecasts routinely issued by South African Weather Service forecasters