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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.
271

Blood lead levels in First Grade South African children : A geographic & temporal analysis

Mathee, Angela 04 November 2008 (has links)
Lead is a toxic heavy metal that has been extensively used in modern society, causing widespread environmental contamination, even in isolated parts of the world. There is now overwhelming evidence associating lead exposure with wideranging health effects, including reductions in intelligence scores, hyperactivity, shortened concentration spans, poor school performance, violent/aggressive behaviour, hearing loss, delayed onset of puberty, anaemia, and in severe cases, coma and death. In recent years consensus has been reached in respect of the absence of a threshold of safety for key health effects associated with lead exposure, and the permanent and irreversible nature of many of the health and social consequences of exposure to lead. The public health problem of environmental lead exposure has been widely investigated in developed countries such as the United States of America where, since the 1970s, policies and interventions have been followed by significant reductions in blood lead levels amongst children. In developing countries, and in African countries in particular, there is a relative dearth of information on the sources, mechanisms of exposure and blood lead distributions in children, and little action has been taken to protect children against lead poisoning. This study was undertaken to determine the current distribution of blood lead concentrations, and associated risk factors, amongst selected groups of first grade school children in the South African urban settings of Cape Town, Johannesburg 7 and Kimberley, a lead mining town (Aggeneys) and two rural towns in the Northern Cape province. A further objective of the study was to compare blood lead distributions determined in the current study with the findings of similar studies undertaken prior to the introduction in 1996 of unleaded petrol in South Africa. The results show that over the past decade, blood lead concentrations amongst first grade school children have declined considerably, but that large proportions of children, especially those living or attending school in impoverished areas, continue to have intolerably high blood lead concentrations, within a range that puts them at risk of detrimental health and social outcomes. The major sources of exposure to lead in the samples studied were leaded petrol, lead-based paint used to decorate homes and schools, lead solder used in “cottage industries” and other home-based lead-related activities, as well as the transfer of lead particles from lead-related work settings into homes. Recommendations for policy and relevant interventions for the South African context are discussed.
272

Blood Lead Testing Guideline Development for a Public Health Department

Johnson Himes, Becky Sue 01 January 2019 (has links)
A lack of consistent, evidence-based practices for blood lead testing of children existed in a local public health department (LHD). No known blood lead level is safe, and toxicity can result in behavioral and cognitive impairments. The purpose of this project was to develop and analyze a clinical practice guideline to establish blood lead testing procedures in the LHD to improve testing procedures and enhance future testing within the jurisdiction. The RE-AIM framework was used to address the reach, effectiveness, adoption, implementation, and maintenance of the clinical practice guideline. Five experts evaluated the guideline using the Appraisal of Guidelines for Research and Evaluation instrument. The assessment results indicated 96.4% agreement across all domains. The experts agreed unanimously to recommend adoption of the clinical practice guideline. Implementation of the guideline might advance nursing practice and patient care in the LHD through incorporation of evidence-based practices. Implementation might also lead to early identification of lead-burdened children and may provide the opportunity for treatment to mitigate cognitive and behavioral deficits related to lead toxicity, thereby improving child health and decreasing related health care costs. Engagement of the clinical practice guideline will support positive social change through the empowerment of public health nurses to provide optimal care to a population of children at risk of deleterious and long-term side effects of lead exposure.
273

Marketing Automation – en studie om ett modernt marknadsföringsverktyg i en svensk kontext

Hendén, Stefan, Dahlgren, Andreas January 2016 (has links)
I takt med att digitala medier har utvecklats under de senaste åren har köpresan för-ändrats till att kunder idag i ett mycket senare skede släpper in leverantörer i dialogen. Marketing Automation adresserar den problembilden och har växt fram som en brygga mellan sälj- och marknadsprocessen. Systemet ger möjlighet att effektivt och automatiserat utveckla leads (potentiell kund). Syftet med denna studie är att undersöka hur Marketing Automation påverkar sälj- och marknadsprocesserna. Vilka förutsättningar krävs för en implementation? Ökar lönsamheten? Vi har därför valt att i det teoretiska ramverket beskriva Marketing Automation och bland annat undersöka om ett införande av Marketing Automation medför att sälj- och marknadsorganisationerna slås samman till en organisatorisk enhet. I studien har vi dessutom kartlagt och beskrivit den moderna köpresan och det som ibland kallas intäktsorganisationen. Vi har funnit att Marketing Automation är relativt outforskat i en svensk kontext. För att utröna om teorin, som i stor utsträckning bygger på internationell litteratur och internationella undersökningar, går att överföra till en svensk kontext har vi valt att genomföra en kvalitativ studie i form av en fallstudie av leverantörer av produkter och tjänster inom området samt företag, med den gemensamma nämnaren att de re-presenterar ett kunskapsintensivt erbjudande och har implementerat lösningar för Marketing Automation. I vår analys finns en samsyn mellan leverantörer och kunder i förutsättningar för ett införande, men vi kan även se hur resultaten divergerar och pekar på implikationer, inte minst avseende måluppfyllnad och samverkan mellan sälj- och marknadsorgani-sationerna. Vår slutsats visar bland annat att Marketing Automation kan leda till uppfyllnad av mjuka värden i företaget men har inte bevisats leda till ökad lönsamhet per automatik. Vi ser lönsamhet och Return on Investment (ROI) som ett område som bör utforskas vidare. / Parallel to the evolution of digital media in recent years, the buyer’s journey has changed. B2B-customers today let suppliers in at the end of the process rather than from the beginning. Marketing Automation addresses that problem and has emerged as a bridge between the sales and marketing processes as it support efficient and au-tomated lead development. The purpose of this study is to examine how marketing automation affects the sales and marketing processes. What conditions are needed for an implementation? Will it increase profitability? We have therefore chosen to describe Marketing Automation, and in particular con-sider whether the introduction of marketing automation means that sales and market-ing organizations merges into one organizational unit? In the study, we have identi-fied and described the modern buyer’s journey and what sometimes is called the rev-enue department. We have found that Marketing Automation is relatively unexplored in a Swedish con-text. To explore if the theory, which is largely based on international literature and research, can be transferred to a Swedish context, we have chosen to conduct a quali-tative study and case study of suppliers of products and services in the area as well as companies, representing a knowledge based offering, which has implemented solu-tions for marketing automation. In our analysis, there is a general consensus between suppliers and customers of the conditions for implementation, but we can also see how the results diverge, not least regarding aspects such as increase of revenue, ROI and collaboration between sales and marketing organizations. Our conclusion shows that marketing automation can lead to fulfillment of the core values of the company but has not been proven to lead to increased profitability au-tomatically. We see profitability and ROI as potential areas of further exploration.
274

Studies On Advanced Lead-Acid Batteries

Martha, Surendra Kumar 12 1900 (has links) (PDF)
Subsequent to the studies on precursor lead-acid systems by Daniel, Grove and Sindesten, practical lead-acid batteries began with the research and inventions of Raymond Gaston Planté in France as early as in 1859, and, even to-day, lead-acid battery remains the most successful battery system ever developed, and no other battery is yet able to compete with lead-acid batteries on cost grounds, albeit batteries based on other chemistries are rapidly catching up. In the past, although lead-acid battery designs have been optimized in several different directions, there are still certain new challenges facing the lead-acid battery designers as additional failure modes become evident in various use modes. There are three types of lead-acid batteries in common use: (a) batteries with flooded or excess electrolyte, (b) low-maintenance lead-acid batteries with a large excess of electrolyte, and (c) batteries with immobilized electrolyte and a pressure-sensitive valve usually referred to as absorptive glass-microfibre (AGM) valve-regulated lead-acid (VRLA) batteries. The flooded-electrolyte lead-acid battery requires checking of specific gravity of electrolyte, periodic addition of water to maintain electrolyte level above the plates and recharge soon after discharge to prevent hard sulfation that causes loss of capacity. The emission of acid fumes corrodes metallic parts in the vicinity of the battery, and the seepage of acid on the top cover of the batteries leads to leakage current resulting in increased self-discharge and ground-shunt hazards. To overcome these problems, AGMVRLA batteries based on oxygen-recombination cycle have emerged. These batteries offer the freedom of battery placement, cyclability without the addition of water or checking the specific gravity, increased safety, and superior performance in some instances. Both flooded-electrolyte and AGM-VRLA batteries can suffer from acid stratification. But, AGM-VRLA batteries are especially susceptible to failures owing to the heat generated by oxygen recombination within the cells as well as due to cell-to-cell variations in electrolyte volumes. Indeed, partial heating of AGM-VRLA batteries could cause dry-out with grid corrosion and even lead to thermal runaway. Consequently, mitigating temperature variations in AGM-VRLA batteries becomes seminal to their commercial success. A dissipation of local heat within the AGM-VRLA batteries can be achieved by adequately filling the void volume in the battery with a thermally conducting gel, such as a gel formed from colloidal silica and sulfuric-acid electrolyte. Although, conventional lead-acid batteries are considered rather a matured technology, significant research and development efforts are currently under way to enhance their performance. Indeed, many improvements have been made in the lead-acid battery since its invention, and although the essential electrochemistry remains unchanged, the modern lead-acid batteries have little semblance to those produced 50 years ago. Over the years, seminal advances have been made in the lead-alloys used, in the materials and design of separators, in battery packaging and in their construction methods, which have led to lead-acid batteries with improved performance, lighter weight and lower cost. This thesis is an attempt to develop lightweight hybrid-VRLA batteries.
275

The history of the Homestake Opera House, 1912-1937

Dyke, Daniel Lee, 1959- January 1989 (has links)
Beginning in the mid 19th Century, intercontinental railroad service made it possible for theatrical road companies to move more freely across America and perform in the smaller community opera houses. This thesis is about one of these opera houses, the Homestake Opera House in Lead, South Dakota. This thesis chronicles the events from the conception of the opera house by Pheobe Hearst and Thomas Grier, to the construction of the structure, 1911 through 1914, and finally through some of the events that took place in the opera house from the opening in August, 1914 to late November, 1936, at which time the opera house was converted into a movie house. Focus is given to the road companies that performed in the opera house within the time period specified. Such performances are chronicled by date, company name, title and type of performance, and names of the author(s).
276

Structural chemistry of lead-antimony and lead-bismuth sulphides.

Skowron, Aniceta. Brown, I.D. Unknown Date (has links)
Thesis (Ph.D.)--McMaster University (Canada), 1991. / Source: Dissertation Abstracts International, Volume: 53-01, Section: B, page: 0503. Supervisor: I. D. Brown.
277

Alley cropping with Leucaena in semi-arid conditions

Botha, Christelle Charle 17 August 2006 (has links)
Please read the abstract in the dissertation / Dissertation (MSc (Agric))--University of Pretoria, 2001. / Plant Production and Soil Science / unrestricted
278

Lead Concentrations in Indoor Dust : Differences Between Indoor Shooting Ranges and Assumed Non-Lead Contaminated Sites / Koncentrationer av bly i inomhusdamm: Skillnader mellan skjuthallar och presumerade blyfria lokaler

Brolin, Lena January 2023 (has links)
A projectile which missed its target and falls into the bullet trap at the end of the shooting range might not be viewed as dangerous. Yet, hazardous fumes and fine metal fragments from the bullet might contaminate the users of the shooting range. The aim of this study was to investigate if there were elevated concentrations of lead and other metals in dust found at indoor shooting ranges in relation to common household dust. My hypothesis stated that, at least lead concentrations were elevated in the dust from indoor shooting ranges, given the common use of lead in ammunition. Results from the collected dust samples proved that shooting ranges had an approximately 330 times higher mean concentration (20 354 mg/kg) compared to the reference sites (62 mg/kg). Except for iron, shooting ranges had higher concentrations for all investigated metals (lead, iron, zinc and copper). The concentrations of lead, iron, zinc, and copper at the shooting ranges likely originated from the use of different types of ammunition, and their various ways to disintegrate. Previous studies have proved a relationship between elevated lead levels in blood and lower IQ, and with the fact that shooting ranges had elevated lead concentrations it seems of high relevance to continue monitoring how lead accumulates in indoor dust in order to avoid potential effects on the human health.
279

Replacement of Lead in a Norma Precision AB Hunting Bullet

Petersson, Christopher, Klara, Trydell January 2017 (has links)
No description available.
280

Lead (Pb) Contamination of Potable Water: Public Health Impacts, Galvanic Corrosion and Quantification Considerations

Triantafyllidou, Simoni 26 September 2011 (has links)
The issue of lead exposure through drinking water was re-examined in light of modern public health goals, recent high-profile cases of elevated lead in water, and emerging concerns regarding the efficacy of legally mandated remedial strategies. A critical literature review revealed that serious lead-in-water hazards are present at many US schools and homes, and that the threat to individuals is not eliminated by existing regulations. Health studies have provided strong links between lead in water and lead in blood of exposed populations, even at relatively low levels of exposure compared to reported lead occurrence in US tap water samples. As efforts shift from addressing pervasive lead sources that once elevated the blood lead of large percentages of the population, to more isolated individual cases requiring exceptional attention, the importance of carefully considering lead in water as a potential source for elevated blood lead increases. Consistent with decades of prior research linking elevated water lead to elevated blood lead (EBL), lead-contaminated water in the high-profile case of Washington DC markedly increased the incidence of EBL for very young children. Specifically, incidence of EBL for children aged ≤ 1.3 years increased more than 4 times during 2001-2003 when lead in water was high, compared to 2000 when lead in water was low. The incidence of EBL for children aged ≤ 1.3 years was highly correlated (R² = 0.81) to 90th percentile lead-in-water levels from 2000-2007, and the risk of exposure to high water lead levels varied markedly in different neighborhoods of the city. Analysis conducted herein focused on identifying "worst-case" neighborhoods and populations. Specifically, this was the first study of the Washington DC case to focus on infants who are most vulnerable to harm from lead in water, and to perform smaller area analysis at the neighborhood (i.e., zip code) level in order to capture pockets of high risk among local communities. Prior biokinetic modeling efforts, examining the potential adverse impacts of lead-in-water exposure, were re-examined to explicitly consider new public health goals. This included impacts on the most sensitive population groups (e.g., young children and particularly formula-fed infants), the potential variability in blood lead levels (BLLs) amongst exposed individuals within those groups (e.g., most sensitive children at the upper tail of the BLL distribution), more conservative BLL thresholds reflecting low-level adverse effects (e.g., 5, 2 and 1 µg/dL versus 10 µg/dL), and the possibility of acute health impacts. This re-evaluation creates a paradigm shift, in that levels of lead in water that were previously considered inconsequential are demonstrated to be of concern in specific circumstances. The replacement of lead service lines in front of consumers' homes is a costly, federally mandated remedial action if a water utility exceeds the US EPA lead action level. Because utilities do not own the entire lead service line, they often only replace the portion of the service line up to the property line, typically with copper pipe. Experiences in Washington DC, as revealed by Freedom of Information Act requests, indicated that partial pipe replacements were not decreasing lead in water, and were actually associated with relatively high incidence of childhood lead poisoning. This prompted the first comprehensive investigation of potential long-term problems arising from galvanic corrosion between the remaining lead pipe and the newly installed copper pipe. Bench-scale experiments demonstrated that galvanic connections between lead pipe (new or aged) and copper pipe increased lead release into the water by 1.1-16 times, when compared to a full length of lead pipe alone. The small area of lead pipe adjacent to the copper joint (<0.5 ft) was gravely affected by galvanic corrosion, and accumulated a thick lead-rust layer (1 inch wide) that constituted a reservoir for semi-random particulate lead detachment into the water. The work on simulated partial pipe replacements revealed that under worst-case scenarios of highly contaminated water samples, most of the lead was not quantified if water samples were not mixed thoroughly after standard preservation (i.e., after addition of 0.15% v/v HNO₃), or if water samples were transferred from one bottle to another prior to preservation. While there is no reason to believe that sample handling and pre-treatment dramatically skew regulatory compliance with the US EPA lead action level, slight variations from one approved protocol to another may cause lead-in-water health risks to be dramatically underestimated. This is of special concern in unusual situations of "worst-case" individual exposures to highly contaminated water, associated with childhood lead poisoning. This work provides the water industry and health agencies with important new insights and perspectives on an old problem. Results can improve strategies to detect and mitigate lead-in-water hazards for individuals or populations, and inform future revisions to the US EPA Lead and Copper Rule. / Ph. D.

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