Laboratory experimentation for the statistical derivation of equations for soil erosion modelling and soil conservation design.

Since Ellison (1947) described the process of erosion as comprising a) the detachment of soil particles from the soil mass by raindrop impact, b) detachment by runoff, c) the transport of the detached particles by raindrop impact, and d) transport by runoff, research has been directed into the mechanics of each of these four phases and how the phases might be linked together in the form of a soil erosion model, such as the Meyer-Wischmeier (1969) model. From a literature review, it became evident that in spite of this work, gaps in knowledge still exist and that i) most studies on soil erosion tend to lump the processes together; ii) whilst a considerable amount of investigation has been carried out on splash erosion, the other processes have received very little attention; iii) there is no explicit study on the effects of factor-interactions on the processes and the role of the laboratory as a place for studying interactions by controlling factors has not attracted much attention; iv) equipment and techniques for the separate evaluation of the detachment and transport of soil particles by overland flow are not available; and v) studies on the hydraulic characteristics of overland flow in relation to the detachment and transport of soil particles in such flows are scarce. This study was therefore specifically aimed at establishing a sounder research base for modelling the subprocesses and ultimate~ for soil conservation design b,y: i) evaluating separate~ each of the above subprocesses; ii) assessing the influence of the factors affecting the processes, particular~ their interactioDS; and iii) examining the hydraulics of soil particle detachment and transport by overland flow with and without rain. As a means to achieve these objectives, a factorial experiment vas set up in the laboratory to examine both the individual effects of rainfall intensity (50, 80, 110, 140 mm h- 1 ) , soil ~ (standard sand, ISIUld, clay loam and clay) and slope steep:1.8Ss (3.5, 7.0, 10.5 and 14.0 per cent) and their interactions on each of the above subprocesses. Additionally, the effects of four rates of runoff (1.0, 1.6, 2.2 and 2.8 ~min) on the hydraulic characteristics of flow such as velocity, depth, Reyuolds number, Froude number and friction factor were examined and used in characterizing the detachment and transport of soil particles in these flows. For each subprocess, these variables were replicated four times. Splash detachment and transport were determined by simulating rainfall from a nozzle simulator over a target soil placed in a rectangular soil tray (10 x 20 x 4 cm) which being set in the centre of a catching tray (90 x 80 x 30 cm) allows for the separate determination of ups lope and downslope splash. The separate measurement of the detachment and transport of soil particles by overland flow with and without rain was carried out b,y using a specially designed rainfall simulator - bed flume facility with runoff and sediment input and measuring devices. The results were analysed by analysis of variance to show the Significance of soil type, rainfall in tensi ty, flow rate t slope steepness and their first and second order interactions in influencing the processes studied. Multiple correlation techniques were used to search for the best associations between the erosion influencing variables and soil loss. RegreSSion analySis was used for establishing predictive equations for detachment and transport rates. Detachment of the test soils by splash can be placed in rank order of standard sand, sand, clay and clay loam with increasing resistance. For splash transport the order is standard sand ) clay > sand > clay loam. For each soil type there are significant increases in splash detachment and transport with increasing rain intensity and slope steepness. The most significant interactions influencing the two splash processes are soil x intensity and slope x intensity for detachment and transport respectivel,J. Significant interactions show that the factors are not independent of each other; the simple effects of a factor differ, and the magnitude of any simple effect varies according to the level of the other factors of the interaction term. The factors influencing detachment by flow without rain rank in ~ order of importance as soil type, slope steepness and discharge. The corresponding order for flow with rain is discharge, slope steepness and soil type. The order of soil detachability for both flow with and without rain is standard sand , sand ~ clay loam> clay. There are also significant increases in detachment rate as slope steepness and flow rate increase. It is further shown that the first and second order interactions of the above factors Significantly influence detachment by flow. On a relative basis, the second order interaction is small and the importance of the first order interactions can be placed in an increasing order of slope x soil, slope x discharge t and discharge x soil for flow without rain. For flow with rain, they rank as slope x soil, discharge x soil, and slope x discharge. The slope x soil interaction showed that as slope steepens the influence of each Boil on detachment rates increases with the proportionate increase being greater for sand and standard sand than for clay and clay loam. The slope x discharge interaction revealed significant increases in detachment rate for all slopes as discharge increased. The magnitude of the response is however greater at the lower than higher slopes. As slope steepness increases, detachment rates by flow with and without rain are also enhanced. The increase was proportionately more for the 1.0 and 1.6 J/min than 2.2 and 2.8 J/min flows. The Boil x discharge interactiC?n also indicated that, for flow without rain, detachability increases more for clay and clay loam than for the sand and standal'd sand as discharge increases. In the presence of rain however, the response of the soils did not differ much. Detachment by flow without rain is predominantly by rilling. In the presence of rain, detacbment rates by flow are increased about three fold and relatively even removal of soil particles from the eroding bed is characteristic. Raindrop impact thus appears to inhibit rill formation by overland flow especially on small slope steepnesses. There is a critical slope steepness at which both raindrop impact and overland flow contribute equally to total detachment. At slopes lower than the critical value, raindrop impact is the main detaching agent whilst flow predominates the detachment process at steeper slopes. The critical slope steepness is soil specific and decreases in the order of clay ~ clay loam ) sand ~ standard sand. The transport of soil particles by combined flow and rain is significantly influenced by soil type, slope steepness, flow rate and their first and second order interactions. Transport rates decreased in the order of sand > standard sand ) clay ) clay loam. Increases in discharge and slope steepness significantly increased transport capacity. For a discharge range of 1.0 - 2.8 l/min, transport capacity increased four fold. The most significant interaction that influences transport capacity is slope x soil. Where factors interact significantly, interpretation of results based solely on the main effects of the influencing factors m&1 result in loss of vital information and lead to wrong conclusions. For example, examination of the slope x soil interaction showed that at lower slopes (3.5 and 7.0 per cent) combined flow and rain has a greater transport capacity for the larger clay and clay loam aggregates than for the fine grains of sand and standard sand. This is obscured when effects are averaged over all the slopes as is the case when only main effects are considered

Biological control via "ecological" damping: An approach that attenuates non-target effects

In this work we develop and analyze a mathematical model of biological control to prevent or attenuate the explosive increase of an invasive species population in a three-species food chain. We allow for finite time blow-up in the model as a mathematical construct to mimic the explosive increase in population, enabling the species to reach "disastrous" levels, in a finite time. We next propose various controls to drive down the invasive population growth and, in certain cases, eliminate blow-up. The controls avoid chemical treatments and/or natural enemy introduction, thus eliminating various non-target effects associated with such classical methods. We refer to these new controls as "ecological damping", as their inclusion dampens the invasive species population growth. Further, we improve prior results on the regularity and Turing instability of the three-species model that were derived in earlier work. Lastly, we confirm the existence of spatio-temporal chaos

Traditional or Performance Assessment: What is the Right Way in Assessing Leaners?

Assessment is one of the critical components of classroom instruction. People within the educational community, which includes policymakers, educators, students, parents, administrators, have different ideas regarding the implementation of assessment strategies. While some believe traditional assessment methods are more effective, others are of the view that performance and portfolio assessment tools are superior. Alternative assessment started being used as a means for educational reform due to the increasing awareness of the influence of testing on curriculum and instruction. Currently, “traditional assessment, which is generally called testing, is challenged by alternative assessment approaches. Which form of the assessment procedure is appropriate in assessing learners? Traditional or alternative assessment procedures? This paper seeks to compare traditional assessment procedures (e.g., multiple choice and essay) with performance and portfolio assessments with the view of unearthing which assessment procedure should be adopted in this current generation. Keywords: Alternative assessment, performance assessment, multiple choice, portfolio assessmen

Land Tenure System: Women’s Access to Land in a Cosmopolitan Context

Land tenure is a concept that looks at how people gain access to land and how they make use of it. In various African societies, there are cases where women's land ownership is complicated by the gender ideology that women should not own property, particularly land and housing. Women who own property tend to be stereotyped as self-assertive and unruly, and therefore not marriage worthy. This study utilized primary data and combined quantitative and qualitative methods in analyzing the data collected. Focused group discussions (FGDs) were also organized as a source of qualitative information to support the quantitative data. Findings from the research are that there is an increase in net registration of titles to land by males over the period, compared to a reduction in females registering titles. There is a gender difference in the number of plots owned by males and females. Males owned more plots of land as compared to females. While the majority of male respondents directly negotiated for their land purchases, it was more usual for females to use male intermediaries in an effort to prevent being duped by predominantly male land sellers. Recommendation from the study is that equal inheritance rights to land should be guaranteed to both men and women

THE RELATIONSHIPS AMONG MENTAL HEALTH, MEDICINAL DRUGS, DRINKING AND DRIVING AND ROAD RAGE AND MOTOR VEHICLE COLLISIONS ON A REPRESENTATIVE SAMPLE OF ONTARIO ADULTS

Studies have demonstrated the relationships between motor vehicle collisions and anxiety and/or mood disorders, antidepressant and anxiolytic medication use, drinking and driving, and road rage. It is unclear if symptoms of anxiety and/or mood disorders are directly associated with motor vehicle collisions or if other factors mediate the effect. This thesis examines the effects of psychiatric distress, medication use, drinking and driving, and road rage on motor vehicle collisions. Cross-sectional data from the Centre for Addiction and Mental Health Monitor were used in a hierarchical logistic regression analysis. Demographic predictors, psychiatric distress, and mediating variables were entered in blocks into five models. Findings indicated the relationship between psychiatric distress and motor vehicle collisions was not mediated by antidepressant and/or anxiolytics; however, it was mediated by drinking driving and road rage. The cross-sectional data make the causal nature of these relationships unclear and further research is needed

Bypassing proximal health care facilities for acute care: a survey of patients in a Ghanaian Accident and Emergency Centre

Objective  To characterise the population that presents to the Accident and Emergency Centre (AEC) at Komfo Anokye Teaching Hospital (KATH) and to identify risk factors associated with bypassing proximal care facilities. Methods  A structured questionnaire was verbally administered to patients presenting to the AEC over 2 weeks. The questionnaire focused on the use of health care resources and characteristics of current illness or injury. Measures recorded include demographics, socioeconomic status, chief complaint, transportation and mobility, reasons for choosing KATH and health care service utilisation and cost. Results  The total rate of bypassing proximal care was 33.9%. On multivariate analysis, factors positively associated with bypassing included age older than 38 years (OR: 2.18, P 0.04) and prior visits to facility (OR 2.88, P 0.01). Bypassers were less likely to be insured (OR 0.31, P 0.01), to be seeking care due to injury (OR 0.42, P 0.03) and to have previously sought care for the problem (OR 0.10, P  <   0.001). Conclusions  Patients who bypass facilities near them to seek care at an urban AEC in Ghana do so for a combination of reasons including familiarity with the facility, chief complaint and insurance status. Understanding bypassing behaviour is important for guiding health care utilisation policy decisions and streamlining cost‐effective, appropriate access to care for all patients. Objectif:  Caractériser la population se présentant au Centre des Accidents et des Urgences à l’Hôpital Universitaire Komfo Anokye, et identifier les facteurs de risque associés au contournement des services de soins proximaux. Méthodes:  Un questionnaire structuré a été administréà des patients se présentant au Centre des Accidents et des Urgences durant deux semaines. Le questionnaire portait sur l’utilisation des ressources de soins de santé et les caractéristiques de la maladie ou la blessure en cours. Les mesures enregistrées comprenaient la démographie, le statut socioéconomique, la plainte principale, le transport et la mobilité, les raisons de choisir l’Hôpital Universitaire Komfo Anokye, l’utilisation et les coûts des services de soins de santé. Résultats:  La proportion totale des contournements des soins proximaux était de 33,9%. En analyse multivariée, les facteurs positivement associés au contournement comprenaient l’âge de plus de 38 ans (OR: 2,18; P = 0,04) et des visites préalables au service (OR: 2,88; P = 0,01). Les patients contournant étaient: moins susceptibles d’être assurés (OR: 0,31, P = 0,01), à la recherche de soins pour des blessures (OR: 0,42; P = 0,03) et d’avoir recherché des soins précédemment pour le même problème (OR: 0,10; P < 0,001). Conclusions:  Les patients qui contournent les services près d’eux pour rechercher des soins dans un centre urbain des accidents et des urgences au Ghana, le font pour une combinaison de raisons, y compris la familiarisation avec le service, la plainte principale et le statut d’assurance. Comprendre le comportement de contournement est important pour guider les décisions de la politique d’utilisation des soins de santé et la rationalisation du coût‐efficacité, pour l’accès approprié aux soins pour tous les patients. Objetivo:  Caracterizar la población que se presenta en el Centro para Accidentes y Emergencias del Hospital Universitario de Komfo Anokye, e identificar los factores de riesgo asociados con el pasar por alto los cuidados ofrecidos en centros cercanos. Métodos:  Se administró verbalmente, a lo largo de dos semanas, un cuestionario estructurado a los pacientes que se presentaron en el Centro para Accidentes y Emergencias. El cuestionario estaba enfocado al uso de recursos sanitarios y a las características de la enfermedad o lesión actual. Las medidas registradas incluían datos demográficos, estatus socioeconómico, principal motivo de consulta, transporte y movilidad, las razones para escoger el Hospital Universitario Komfo Anokye, y el uso de los servicios sanitarios y su coste. Resultado:  La tasa total de haber evitado los centros cercanos fue del 33.9%. En un análisis multivariado, los factores asociados de forma positiva con el haber pasado de utilizar un centro cercano incluían tener una edad mayor de 38 años (OR: 2.18, P 0.04) y haber realizado visitas anteriores al centro sanitario (OR 2.88, P 0.01). Los pacientes que evitaban un centro cercano tenían una mayor probabilidad de no estar asegurados (OR 0.31, P 0.01), de buscar ayuda por una lesión (OR 0.42, P 0.03), y de previamente haber buscado ayuda sanitaria para el problema (OR 0.10, P  <   0.001). Conclusiones:  Los pacientes que pasaban de utilizar centros cercanos y buscan ayuda en un centro urbano para accidentes y emergencias en Ghana lo hacen por una combinación de razones que incluyen el estar familiarizados con el centro, la causa por la que consultan, y el estar o no asegurados. Entender el comportamiento de pasar de un centro cercano es importante para tener en cuenta a la hora de realizar políticas sanitarias y ofrecer acceso a cuidados apropiados y coste‐efectivos para todos los pacientes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92092/1/j.1365-3156.2012.02984.x.pd

Gestational Diabetes and Metabolic Outcomes

Women with gestational diabetes mellitus (GDM) have increased weight and higher glucose levels during pregnancy and in the postpartum period compared to women without GDM. It is therefore recommended to prevent excess gestational weight gain (GWG) and also return to pre-pregnancy weight at 1-year postpartum. This is essential as higher postpartum weight retention (PPWR) at 1-year postpartum is a significant risk factor for long-term weight gain and the most important predictor of future diabetes in women with GDM. To tackle weight and subsequent metabolic health problems such as weight and glucose control in these women, there is a need to comprehend their risk and to investigate different lifestyle approaches. This thesis provides a better understanding of the novel concept of intuitive eating during and after pregnancy and its associations with metabolic health. It also investigates the predictors and consequences of PPWR in a cohort of women with GDM. This thesis utilized data from the Lausanne University Hospital (CHUV) GDM longitudinal cohort. We assessed the cross-sectional and longitudinal associations between intuitive eating and metabolic health outcomes during pregnancy and in the postpartum period in women with GDM. We also investigated the predictors and consequences of weight retention in this cohort. The cross-sectional analysis showed that intuitive eating during and after pregnancy was significantly associated with metabolic health outcomes, both with weight and with glucose control. The longitudinal analyses revealed that intuitive eating during pregnancy was also related to later metabolic health outcomes, at the end of pregnancy, but also in the early (6-8 weeks) and late (1-year) postpartum period. Regarding the predictors and consequences of PPWR, GWG predicted higher PPWR, both in the early and late postpartum period. Women with PPWR had worsened glucose control at 1 year postpartum that was not observed in the early postpartum period. These results suggest that intuitive eating could represent a novel approach to weight and glucose management in women with GDM. Our data regarding the consequences of PPWR also suggest that clinical care with a strong focus on lifestyle interventions in order to improve weight and glucose control should be essential up to the late postpartum