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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Best Management Practice Use and Efficacy for the Virginia Nursery and Greenhouse Industry

Mack, Rachel E. 24 January 2017 (has links)
Best management practices (BMPs) are used in the nursery and greenhouse industry to increase production efficiency, and also serve to help meet clean water limitations on contaminants entering waters such as the Chesapeake Bay Watershed. Research is lacking on which BMPs are most widely used or most efficacious for Virginia nursery and greenhouse growers. Objectives of this work were to determine BMP use, barriers to adoption, and scientific efficacy. We conducted a survey of Virginia growers to find the 1) most widely used BMPs, 2) reasons behind BMP use, and 3) any barriers to BMP adoption. Sixty growers (17%) responded to the survey. The most widely used BMPs included irrigation scheduling, integrated pest management, optimized irrigation efficiency, plant need based watering, grouping plants by water needs, on-site water capture and collection, and use of controlled-release fertilizers (CRFs). Cost was a barrier to BMP adoption, and environmental concern was a commonly reported reason for BMP use. We documented the science supporting selected water-related BMPs (grass buffer strips, CRFs, and irrigation optimization BMPs). Providing the science supporting BMP use gives growers confidence in implementing BMPs to limit water contamination, and prevent waste. / Master of Science
212

Core outcome measures for interventions to prevent or slow the progress of dementia for people living with mild to moderate dementia: Systematic review and consensus recommendations

Chatters, R., Newbould, L., Sprange, K., Hind, D., Mountain, Gail, Shortland, K., Powell, L., Gossage-Worrall, R., Chater, T., Keetharuth, A., Lee, E., Woods, B. 20 February 2018 (has links)
Yes / Recruiting isolated older adults to clinical trials is complex, time-consuming and difficult. Previous studies have suggested querying existing databases to identify appropriate potential participants. We aim to compare recruitment techniques (general practitioner (GP) mail-outs, community engagement and clinician referrals) used in three randomised controlled trial (RCT) studies assessing the feasibility or effectiveness of two preventative interventions in isolated older adults (the Lifestyle Matters and Putting Life In Years interventions). Methods: During the three studies (the Lifestyle Matters feasibility study, the Lifestyle Matters RCT, the Putting Life In Years RCT) data were collected about how participants were recruited. The number of letters sent by GP surgeries for each study was recorded. In the Lifestyle Matters RCT, we qualitatively interviewed participants and intervention facilitators at 6 months post randomisation to seek their thoughts on the recruitment process. Results: Referrals were planned to be the main source of recruitment in the Lifestyle Matters feasibility study, but due to a lack of engagement from district nurses, community engagement was the main source of recruitment. District nurse referrals and community engagement were also utilised in the Lifestyle Matters and Putting Life In Years RCTs; both mechanisms yielded few participants. GP mail-outs were the main source of recruitment in both the RCTs, but of those contacted, recruiting yield was low (< 3%). Facilitators of the Lifestyle Matters intervention questioned whether the most appropriate individuals had been recruited. Participants recommended that direct contact with health professionals would be the most beneficial way to recruit. Conclusions: Recruitment to the Lifestyle Matters RCT did not mirror recruitment to the feasibility study of the same intervention. Direct district nurse referrals were not effective at recruiting participants. The majority of participants were recruited via GP mail-outs, which may have led to isolated individuals not being recruited to the trials. Further research is required into alternative recruitment techniques, including respondent-driven sampling plus mechanisms which will promote health care professionals to recruit vulnerable populations to research. / Medical Research Council (grant number G1001406); Sheffield Health and Social Research Consortium; National Institute for Health Research Public Health Research programme (project number 09/ 3004/01)
213

Recruitment of older adults to three preventative lifestyle improvement studies

Chatters, R., Newbould, L., Sprange, K., Hind, D., Mountain, Gail, Shortland, K., Powell, L., Gossage-Worrall, R., Chater, T., Keetharuth, A., Lee, E., Woods, B. 20 February 2018 (has links)
Yes / Recruiting isolated older adults to clinical trials is complex, time-consuming and difficult. Previous studies have suggested querying existing databases to identify appropriate potential participants. We aim to compare recruitment techniques (general practitioner (GP) mail-outs, community engagement and clinician referrals) used in three randomised controlled trial (RCT) studies assessing the feasibility or effectiveness of two preventative interventions in isolated older adults (the Lifestyle Matters and Putting Life In Years interventions). Methods: During the three studies (the Lifestyle Matters feasibility study, the Lifestyle Matters RCT, the Putting Life In Years RCT) data were collected about how participants were recruited. The number of letters sent by GP surgeries for each study was recorded. In the Lifestyle Matters RCT, we qualitatively interviewed participants and intervention facilitators at 6 months post randomisation to seek their thoughts on the recruitment process. Results: Referrals were planned to be the main source of recruitment in the Lifestyle Matters feasibility study, but due to a lack of engagement from district nurses, community engagement was the main source of recruitment. District nurse referrals and community engagement were also utilised in the Lifestyle Matters and Putting Life In Years RCTs; both mechanisms yielded few participants. GP mail-outs were the main source of recruitment in both the RCTs, but of those contacted, recruiting yield was low (< 3%). Facilitators of the Lifestyle Matters intervention questioned whether the most appropriate individuals had been recruited. Participants recommended that direct contact with health professionals would be the most beneficial way to recruit. Conclusions: Recruitment to the Lifestyle Matters RCT did not mirror recruitment to the feasibility study of the same intervention. Direct district nurse referrals were not effective at recruiting participants. The majority of participants were recruited via GP mail-outs, which may have led to isolated individuals not being recruited to the trials. Further research is required into alternative recruitment techniques, including respondent-driven sampling plus mechanisms which will promote health care professionals to recruit vulnerable populations to research. / The Lifestyle Matters RCT was funded by the Medical Research Council (grant number G1001406); Sheffield Health and Social Research Consortium; National Institute for Health Research Public Health Research programme (project number 09/ 3004/01)
214

Opportunities for Standardization in Monitoring of Best Management Practices in the Southeastern United States

Yonce, Mary Elizabeth 17 March 2005 (has links)
Silvicultural activities, particularly forest harvesting operations, have the potential to negatively impact water quality. In order to lessen the probability that water quality degradation will occur, a suite of best management practices has been developed and adopted by southeastern states. The Clean Water Act exempts silvicultural activities from the permitting process of Section 404 as long as federally accepted best management practices are implemented to control nonpoint source pollutants. To demonstrate that these practices are being implemented, states are now inspecting and reporting on best management practice usage on a state wide basis. The Environmental Protection Agency is responsible for executing the Clean Water Act and would like to use the information provided by the individual states to guide water quality protection programs at a regional scale since states have developed their own unique methods or reporting. Currently there it is difficult to compare the information provided by states, and this impedes further development of water quality protection programs. To address this issue, a state of the art review of current inspection and monitoring methods in the southeast was conducted. Forestry professionals were then surveyed to identify opportunities for standardization in the inspection and reporting methodologies employed by states. Using the information resulting from the review and survey, recommendations for standardization were made in the following areas: site selection criteria, field execution method, form design, best management practices evaluated and water quality threat assessment. A standardized form was also developed and tested across three physiographic regions. This information is helpful for future planning and modifications that state agencies can use to standardize their BMP implementation monitoring methods. / Master of Science
215

Skid Trail Stream Crossing Closure Techniques for Protecting Water Quality

Wear, Laura 22 May 2012 (has links)
The impact of forest roads and skid trails on stream health is being increasingly scrutinized. Forest roads and skid trails have repeatedly been identified as forest operations having the greatest potential to produce sediment by way of non-point source pollution. The stream crossing portion of a skid trail is where sediment delivery is most likely to occur. Forestry Best Management Practices (BMPs) have been developed by most states to reduce both erosion and sedimentation. In general, BMPs have been proven to be effective. Few studies have quantified the impact of various levels of BMPs on sedimentation. In this study, three replications of three skid trail stream crossing BMP treatments were monitored following skidder bridge removal to determine their efficacy in reducing sedimentation: slash, mulch, and mulch plus silt fence. Water samples were collected upstream and downstream of each crossing daily for one year following timber harvesting. Samples were evaluated for total suspended solids. Results indicate that both slash and mulch treatments applied to the stream crossing approach after skidder bridge removal are effective at reducing stream sedimentation after harvest. The mulch plus silt fence treatment allowed the most sediment to enter the stream at the approach, perhaps due to silt fence installation disturbances. We do not recommend using silt fences directly adjacent to a stream bank, if other alternatives exist. / Master of Science
216

Impact of Substrate on Nutrient Removal in In-Ditch Bioreactors

Dubner, Anne Noe 04 August 2022 (has links)
Drainage ditches, or grassed waterways, collect nutrient-laden runoff from agricultural fields and transport it to nearby waterbodies. The high nitrogen and phosphorus content in this water leads to negative effects, such as eutrophication in the receiving waters. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors are intended to reduce flow rate and stimulate denitrification and sedimentation. Using experimental ditch segments and simulated runoff, this study evaluated nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors and 3) vegetated ditches with combination woodchip and biochar bioreactors. Biochar was added in an effort to increase phosphorus removal. Inlet and outlet concentrations of nitrate, ammonium and phosphate were measured for each of the three treatments in triplicate. There were no statistically significant differences between treatments on load removed for any of the three nutrients of interest. Issues in measuring outlet flow rate made drawing definitive conclusions on nutrient load reductions difficult. Further experimentation using adjusted outlet flow measuring methods and bioreactor design would help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology in agricultural grassed waterways. / Master of Science / Drainage ditches, or grassed waterways, are located at the edge of agricultural fields where runoff migrates naturally. These ditches help to direct runoff from the field to receiving waterbodies while reducing erosion. Agricultural runoff often contains high levels of nitrogen and phosphorus from fertilizer added to promote crop growth. When runoff with a high nutrient content reaches a waterbody, it reduces the quality of the water for the plants and animals that live in it and for human recreation or consumption. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors have the potential to remove nitrogen from the water by creating optimal conditions for the microorganisms that transform nitrogen in the water to nitrogen in the air. Phosphorus removal has the potential to be enhanced by in-ditch bioreactors that reduce flow and allow for phosphorus to settle out of the water. In addition, settling of phosphorus may be increased by adding a material, such as biochar, that phosphorus can attach to. Using experimental ditch segments and simulated runoff, this study looked at nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors installed and 3) a vegetated ditch with combination woodchip and biochar bioreactors installed. Concentrations of two nitrogen compounds and one phosphorus compound were measured before and after passing through each ditch. There were no significant differences between any of the three ditch types on how much of each compound they could remove. These results are inconclusive due to inaccuracies in measuring flow rate at the outlet of the ditches. Further experimentation using improved flow measuring techniques and bioreactor designs would likely help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology.
217

Simulation of Runoff and Pollutant Loss in Urbanizing Watersheds

Zeckoski, Rebecca Winfrey 31 July 2002 (has links)
The effect of urbanization on previously agricultural watersheds is an increasingly important issue for watershed planners. Urbanization increases runoff and pollutant loadings to the watershed outlet. Watershed planners in areas that previously had little impervious cover must now consider the effects of new roads and buildings on hydrologic processes. The ANSWERS-2000 watershed model was modified to simulate watersheds with mixtures of agricultural and urban areas. In addition, components were added to simulate atmospheric deposition and urban management practices, including wet ponds, dry ponds, and infiltration trenches. The modified model was evaluated on two watersheds in Blacksburg, Virginia, including a subwatershed of Stroubles Creek and a large parking lot on the Virginia Tech campus with a dry pond at its outlet. The model predicted the hydrology and pollutant losses for the year 1999 from the Stroubles Creek watershed within 50% of the observed values after calibration. Prediction errors were much higher for the parking lot and dry pond simulation of the period of time from August 1995 to February 1996. For the parking lot inflow to the dry pond, errors ranged from 0 to 100%. For the dry pond effluent, errors for runoff and sediment losses were -11.5 and 60.1%, respectively, and nutrient losses were poorly predicted (greater than 100% error). There was considerable uncertainty as to the quality of the observed data and this may account for some of the predicted sediment and nutrient loss errors. The modified model was applied to the Battlefield Green Watershed in Hanover County, Virginia to demonstrate the watershed response to development in that watershed. As simulated, sediment and nutrient losses were 30 to 50 times higher after development. The model is intended for use on watersheds with an impervious cover of 30% or less, due to the increased difficulty in accurately quantifying the hydrology of highly urbanized watersheds and because of uncertainty in atmospheric deposition rates on such watersheds. The pond subroutines are very simplified, and limit simulation to ponds with simple geometries. / Master of Science
218

An Assessment of the Quality of Agricultural Best Management Practices in the James River Basin of Virginia

Cunningham, Janelle Hope 03 October 2003 (has links)
Assessment tools were developed to address the need for a low cost, rapid method of quantifying the quality of agricultural best management practices (BMPs). Best management practices are either cost-shared, where some or all of the capital costs of the practice were subsidized with federal, state, or local funds, or non cost-shared, where the cost of the practice and its upkeep is paid for by the landowner or farm operator. Cost-share practices are required to comply with state standards, while non cost-share practices are not subject to any standards. For this study, BMP quality is defined as the adherence to design, site selection, implementation, and maintenance criteria relating to water quality as specified by state and federal agencies promoting BMP implementation. The two objectives of this research were: 1. develop a set of assessment tools to quantify the quality of agricultural best management practices in a rapid low-cost manner, and 2. test the tools and determine if differences in quality exist between cost-share and non cost-share BMPs in the James River Basin of Virginia. Assessment tools were developed for sixteen practices: alternative water systems, stream fencing, streambank stabilization, grass filter strips, wooded buffers, permanent vegetative cover on critically eroding areas, permanent vegetative cover on erodible cropland, reforestation of erodible crop and pasture land, animal waste storage facilities, grazing land protection systems, loafing lot management systems, late winter split application of nitrogen on small grains, protective cover for specialty crops, sidedress application of nitrogen on corn, small grain cover crops-fertilized and harvested, and small grain cover crops for nutrient management. Assessment tools were developed using both Virginia BMP standards and expert knowledge. Virginia Department of Recreation and Conservation (DCR) and Virginia and national Natural Resource Conservation Service (NRCS) BMP standards were collected and sorted into the four quality component categories; design, site selection, implementation, and maintenance. Standards that pertained directly to a BMPs' potential to protect water quality were translated into question format. Multiple-choice or yes/no questions were used as often as possible to avoid potential bias and for ease of processing. Assessment tool development involved an iterative process that included input from a research team (university-based researchers) and an expert team (public and private sector professionals and practitioners responsible for BMP design and assessment). One hundred and fifty-five cost-shared BMPs and 150 non cost-shared BMPs were assessed on 128 independent farms in the James River Basin of Virginia over a period of four months. The assessment tools were loaded onto a personal digital assistant (PDA), which facilitated data collection and eliminated the need for data transcription. Data collected on the PDA were uploaded periodically to a computer database. A digital camera was used to develop a photographic record of the assessed BMPs. Best management practice quality scores were based on five-point scale, with one being the lowest quality score and five as the highest. Statistical analyses conducted on both the overall quality scores and the quality component scores, indicate that there is not a strong significant difference (p = 0.05) in quality between the cost-shared and non cost-shared BMPs assessed for this study. Statistically significant differences between cost-share and non cost-share practices did, however, exist. For the filter/buffer strips practices (grass filter strips and wooded buffers), the implementation quality component cost-share mean (3.35) and the non cost-share mean (3.88) were statistically different at the 0.05 level (p-value = 0.026). One other statistically significant difference was found. For stream fencing, the overall quality cost-share mean was 4.68 while the non cost-share mean was 4.20; the means are statistically different at the 0.05 level (p-value = 0.043). Statistical analyses were performed to determine if age of practice, farm size, or Soil and Water Conservation District (SWCD) had effects on the BMP quality. No statistically significant differences (p = 0.05) were found relating to the age of an assessed BMP or farm size. One SWCD, the Robert E. Lee district, had a statistically significant difference in the design quality component means; cost-share mean = 4.21, non cost-share mean = 2.94 with a p-value of 0.048. The statistically significant differences that were detected do not establish a clear trend; it appears that for the BMPs assessed here the qualities of cost-share and non cost-share practices are roughly equal. The fact that cost-share practices and non cost-share practices do appear to be roughly equal may be the result of education and outreach programs sponsored by Virginia's SWCDs and Virginia Cooperative Extension. Non cost-share practices may be of equal quality to cost-share practices because those implementing BMPs without the benefit of cost-share may have a greater stake (both financial and personal) in those practices performing well. If no statistically significant difference in quality exists between cost-share and non cost-share practices, then non cost-share practices should be treated equally when accounting for BMPs in NPS pollution in watershed management and computer modeling. Currently, only cost-share practices are included in computer models, in part because these are the only practices tracked by the existing BMP establishment infrastructure. Estimating the numbers and distribution of non cost-share practices and incorporating them into NPS water quality modeling efforts will more accurately reflect the steps agricultural producers have and are taking to decrease the amount of NPS pollution reaching water bodies. Additionally, policy regarding NPS pollution and BMPs should reflect the apparent equal qualities of cost-share and non cost-share practices. The assessment tools developed as a part of this study can potentially be applied to determine the quality of BMPs on basin or state-wide scales to give policy makers a better understanding of the practices and populations that the policies are created for. Moreover, BMP quality scores have the potential to be used as a surrogate measure for BMP performance. Further research recommendations include correlating BMP quality scores with BMP performance, wider scale testing of the tools, continued revision of the tools, and using the assessment tool scores to diagnose BMP quality problems. / Master of Science
219

Corporate compliance with non-mandatory statements of best practice: the case of the ASB statement on interim reports.

Mangena, Musa, Tauringana, V. January 2007 (has links)
No / This paper contributes to our understanding of compliance with non-mandatory statements of best practice. Specifically, we examine the efficacy of agency-related mechanisms on the degree of disclosure compliance with the ASB Statement on interim reports. Using data drawn from a sample of 259 UK companies listed on the London Stock Exchange, we show that although overall disclosure compliance is high (74.5% of the items of information being disclosed), companies do not fully comply with the ASB Statement on interim reports. We employ an ordinary least square (OLS) regression model to establish whether selected company-specific and corporate governance characteristics (proxying for agency-related mechanisms) are related to the degree of disclosure compliance. Our results indicate that multiple listing, company size, interim dividend and new share issuance are positively associated with the degree of compliance. We also find that the degree of disclosure compliance is positively associated with auditor involvement, audit committee independence and audit committee financial expertise. These results have important implications for policy because they suggest that whilst agency-related mechanisms may motivate compliance with best practice non-mandatory statements, full compliance may be unattainable without regulations.
220

The curse of dimensionality of decision-making units: A simple approach to increase the discriminatory power of data envelopment analysis

Vincent, Charles, Aparicio, J., Zhu, J. 14 December 2019 (has links)
Yes / Data envelopment analysis (DEA) is a technique for identifying the best practices of a given set of decision-making units (DMUs) whose performance is categorized by multiple performance metrics that are classified as inputs and outputs. Although DEA is regarded as non-parametric, the sample size can be an issue of great importance in determining the efficiency scores for the evaluated units, empirically, when the use of too many inputs and outputs may result in a significant number of DMUs being rated as efficient. In the DEA literature, empirical rules have been established to avoid too many DMUs being rated as efficient. These empirical thresholds relate the number of variables with the number of observations. When the number of DMUs is below the empirical threshold levels, the discriminatory power among the DMUs may weaken, which leads to the data set not being suitable to apply traditional DEA models. In the literature, the lack of discrimination is often referred to as the “curse of dimensionality”. To overcome this drawback, we provide a simple approach to increase the discriminatory power between efficient and inefficient DMUs using the well-known pure DEA model, which considers either inputs only or outputs only. Three real cases, namely printed circuit boards, Greek banks, and quality of life in Fortune’s best cities, have been discussed to illustrate the proposed approach. / panish Ministry of Economy, Industry and Competitiveness (Ministerio de Economía, Industria y Competitividad), the State Research Agency (Agencia Estatal de Investigación) and the European Regional Development Fund (Fondo Europeo de Desarrollo Regional) under grant MTM2016-79765-P (AEI/FEDER, UE).

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