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1
Leblanc, Maryse. "Efficacy and economics of yellow nutsedge (Cyperus esculentus L.) management systems." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59571.
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Cropping systems were: corn + atrazine + EPTC/dichlormid; corn + atrazine + metolachlor; corn + atrazine + bentazon; corn + EPTC/dichlormid intercropped with red clover as green manure or managed as forage crop in the following year; alfalfa + EPTC; soybean + metalachlor + metribuzin; sorghum as green manure followed by winter wheat; and spring barley + diclofop-methyl + bromoxynil. Control treatments were yellow nutsedge growing in a pure stand and complete yellow nutsedge control. After two growing seasons in experiment #1, the tuber population had decreased in all cropping systems. Yellow nutsedge was reduced to 9% of the initial population under perfect control while it tripled in the pure stand. After the first growing season in the second experiment, only corn intercropped with red clover significantly reduced yellow nutsedge population by 17%. When the systems were not treated with herbicides, the yellow nutsedge population increased between 41 to 180% in all cropping systems. There was a significant relation between yellow nutsedge, broadleaf weed and grass densities and yellow nutsedge tuber production. Corn was the most profitable cropping system. The least economically advantageous cropping system was barley.
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Scarr, Lowell Martin. "Assessing the value of public investment into biological control research for invasive alien plants : the ARC PPRI Weeds Research Division." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1020604.
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This study investigates the economic impact of the ARC PPRI Weeds Research Division. The Division researches appropriate methods of biological control for invasive alien plants (IAPs). These plants pose an increasing threat to environmental integrity and ecosystem service provision impacting on economic potential. Since the work of the Division is considered a public good, a predominantly descriptive approach has been adopted for the valuation process. A combination of quantitative cost analysis and a qualitative study of the impacts of research and invasive alien plants is used to deal with the challenges associated with non-market valuation. The study found that investment into the Weeds Division is a valuable activity that supports the long-term growth potential of the South African economy. The role of a well-functioning environment is highlighted as an essential base for the creation of sustained growth opportunities in any society. It was determined that investment into the Division should be increased into the future to support efficient spending of scarce state funds. Biological control research was found to provide strategic future growth potential, creating opportunities for the development of a competitive advantage in the biotechnology and environmental management sectors. The study adds to the increasing move towards a more holistic view of economic valuation, taking factors other than pure finance and econometrics into consideration. This is an important shift in prevailing economic thought, as a realisation is reached that a single, or even triple, bottom line is an outdated and insufficient decision making basis.
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Hari, Krishnan Ramesh Kannan. "Invasion of Lantana into India: analyzing introduction, spread, human adaptations and management." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001756.
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Objectives and Research Questions 1. To reconstruct the history of invasion of Lantana in India from where, by who, and when was Lantana species introduced into India?, given its long history in the country, is it still spreading or has it become more or less stable? 2. To study the human adaptation to Lantana invasion: socioeconomic causes and consequences of the use of Lantana as an alternative source of livelihood for forest dependent communities in southern India; how have local communities adapted to the invasion?; what are the key determinants that may have driven communities to use Lantana?; what are the economic consequences of the use of Lantana by local communities? 3. To critically review local practices and forest policy for the management of Lantana in southern India.; how has the use of Lantana by local communities impacted its local regeneration?; does the use of Lantana in local context have implications for its management?; what has been the role of the Forest Department and its policies in managing Lantana?
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Morrish, Charles Harry. "Aspects of mechanical and other non-chemical weed management in forage maize (Zea mays L.)." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281684.
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Juraimi, Abdul Shukor. "Studies on some biological aspects, competitive ability and chemical control of Bermudagrass (Cynodon dactylon (L.) Pers.)." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363407.
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Henly, Sarah. "Aspects of the selectivity of isoproturon to Bromus sterilis, Bromus willdenowii and barley." Thesis, University of Bath, 1986. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370666.
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Bulmer, R. H. C. "Aspects of the agro-ecology and control of Bromus sterilis L." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376645.
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Hietasalo, P. (Pauliina). "Behavioral and economic aspects of caries control." Doctoral thesis, Oulun yliopisto, 2010. http://urn.fi/urn:isbn:9789514263453.
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Abstract The aim was to determine the association between baseline factors, such as oral health-related behavior, attitudes, knowledge and beliefs in relation to caries increment during a randomized clinical trial (RCT). A further aim was to evaluate treatment costs and health outcomes during and after the RCT. In Pori Finland, 11- to 12-year-old children with active initial caries lesion(s) participated in the RCT in 2001–05. The experimental group (n=250) received multiple measures for controlling caries. The control group (n=247) received standard dental care. In 2005–08, all received standard dental care. Regression analyses were used to study the associations between behavioral factors and caries increment. Cost-effectiveness analysis was conducted (trial period), and costs and health outcomes as well as dental service utilization were evaluated (post-trial period). In the experimental group, brushing teeth twice a day was indicative of developing no new caries lesions, whereas eating candy at least once a day, predicted new lesions. In the experimental and control groups, lack of concern about cavities and lack of knowledge about mother’s dental health predicted new caries lesions. The average incremental cost for averting one DMF surface was €34. The experimental regimen was more effective and more costly than the standard dental care. The total costs decreased year after year. The mean total cost per adolescent was lower and the clinical outcome was better among the former participants in the experimental group. The utilization of dental services was significantly more regular among the former participants in this group. It may be feasible to control caries more effectively by affecting toothbrushing, candy eating and oral health-related attitudes, as preventive procedures may be ineffective if those factors are not in order. It is important to discuss oral health-related topics in families, because this may improve the oral health-related behavior of children. Cost-effectiveness of regimen used for the experimental group may be improved by division of work or by selective reduction of preventive procedures. Well-timed caries control can decrease treatment cost and yield long-term improvement of dental healthTiivistelmä Tutkimuksen tarkoituksena oli selvittää satunnaistetun kliinisen kokeen alussa rekisteröityjen suunterveyteen liittyvien tapojen, tietojen, asenteiden, uskomusten ja karieskertymän välisiä yhteyksiä. Lisäksi arvioitiin hoitokustannuksia ja hoidollisia tuloksia sekä kokeen ajalta että kokeen jälkeiseltä ajalta. Ne 11–12-vuotiaat lapset, joilla oli ainakin yksi alkava aktiivinen kariesvaurio, osallistuivat kokeeseen Porissa vuosina 2001–05. Koeryhmän lapset (n=250) saivat tehostettua ehkäisevää hoitoa ja kontrolliryhmän lapset (n=247) tavanomaista hammashoitoa. Kaikki saivat tavanomaista hammashoitoa vuosina 2005–08. Käyttäytymisellisten tekijöiden ja karieskertymän välisiä yhteyksiä tutkittiin regressioanalyysien avulla. Kustannusvaikuttavuusanalyysi tehtiin kokeen ajalta. Hoitokustannuksia ja hoidollisia tuloksia sekä palveluiden käyttöä arvioitiin kokeen jälkeiseltä ajalta. Lapsilla, jotka harjasivat vähintään kaksi kertaa päivässä, oli yleensä ehjät hampaat, kun taas lapsilla, jotka söivät päivittäin makeisia, oli useasti reikiä. Huolettomuus reikiintymistä kohtaan ja tietämättömyys äidin hampaiden kunnosta näkyi lasten hampaiden reikiintymisenä. Yhden hammaspinnan säästyminen paikkaukselta maksoi keskimäärin 34 €. Koeryhmän saama hoito oli vaikuttavampaa, mutta kalliimpaa kuin kontrolliryhmän saama hoito. Kokonaiskustannukset laskivat vuosi vuodelta. Keskimääräiset hoitokustannukset olivat pienemmät ja hammasterveys parempi entisen koeryhmän jäsenillä kuin kontrolliryhmäläisillä. Myös palveluiden käyttö oli säännöllisempää koeryhmässä. Karieksen hallintaa voidaan todennäköisesti tehostaa vaikuttamalla hampaiden harjaukseen, makeisten syöntiin ja suunterveyteen liittyviin asenteisiin. On tärkeää varmistaa, että nämä asiat ovat kunnossa, koska ehkäisevät toimenpiteet saattavat muuten jäädä tehottomiksi. Suunterveyteen liittyvistä asioista olisi hyvä keskustella perheissä, koska asioiden esillä pitäminen voi vaikuttaa suotuisasti lasten terveystapoihin. Koeryhmän saaman hoito-ohjelman kustannusvaikuttavuutta voisi todennäköisesti parantaa muuttamalla suunterveydenhuollon henkilöstön työnjakoa tai karsimalla valikoiden ehkäisevien toimenpiteiden määrää. Oikea-aikainen karieksen hallinta voi vähentää hoitokustannuksia ja lisätä hammasterveyttä pitkällä aikavälillä
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Miltz, David. "Economic aspects of targeting environmental policy." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235914.
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This thesis is composed of two parts; the first addresses theoretical aspects of the economics of targeting pollution control policy, whilst the second is an illustrative case study designed to embellish the more abstract insights of the first section.
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Ndeffo, Mbah Martial Loth. "Optimizing epidemic control under economic constraints." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609007.
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Begna, Sultan Hussein. "Agronomic and physiological aspects of competition for light between corn hybrids differing in canopy architecture and weeds." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35572.
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The problems associated with short growing seasons has led to the development of leafy-reduced stature (LRS) corn hybrids. These hybrids have more leaf area above the ear, more rapid leaf area development, shorter stature, earlier maturity, and better responses to high plant populations and narrow spacings than conventional hybrids. Plants grown in a reduced light environment are limited in carbon assimilation and this, in turn, results in reductions in growth and development. A way to supplement the availability of photosynthate is injection of sucrose into plant stems. The objective of this thesis was to determine the ability of LRS corn plants to compete with weeds, and the reactions of weed species to the shade, including the relationships between weed growth (increase in biomass) and development (shape) under shaded conditions. Three years of field experiments (LRS and more conventional corn hybrids with both transplanted and naturally growing weeds) and two years of greenhouse work [weeds alone, C3 (lamb's quarters and velvetleaf) and C4 (redroot pigweed) in full sun or deep (75%) shade injected with 15% sucrose or not] were conducted. Yield reductions due to weed pressure were lower for LRS than other hybrids. Biomass production by both transplanted and naturally occurring weeds was up to 85% less under corn canopies than when grown without competition from corn. The biomass of C4 weeds was more reduced by competition with corn plants than that of C3 weeds. In spite of quick and early leaf development, leaves and other plant parts of LRS were not damaged excessively by mechanical (rotary hoeing) weed control. Both C3 and C4 weed plants produced more dry matter when injected with sucrose. Dry weights of sucrose injected shaded plants were not different from full sun uninjected plants. However, sucrose injection did not alter shading effects on development (distribution of biomass). Dry matter production and photosynthetic rates of C4 weeds were more reduced
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Jalbout, Fouad Noaman. "Bayesian economic cost model for a variable sampling plan for fraction defective and manufacturing process control." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184753.
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Acceptance sampling plans by variables are a basic quality control technique. These plans provide economical procedures to determine the acceptability of batches of product. Most of these plans are based on a single quality characteristic and are of the classical type. This work concentrates on Bayesian variable acceptance sampling plans for fraction defective. Both destructive and non-destructive sampling procedures are considered. A set of decision points are estimated and employed to make decisions about the inspected lots. Techniques to dispose of the rejected lots are provided. Components of the expected total cost relative to various decisions are estimated. The sample size required to obtain the expected optimum cost is found. An untrue assumption implicit in the measurement of the quality characteristic of items sampled is that the observed dimensions are error free. The distributions, means, and variances of a set of parameters for error free and error prone sampling is listed. Computer programs written in FORTRAN 77 are developed to compute the decision points and the costs for both destructive and nondestructive testing. Precise Bays estimate of the costs and other economic parameters involve the moments of the fraction defective p raised to the kᵗʰ power. Mathematical expressions for the conditional expectations of p|x and p|ẋ are derived and a computer program to estimate these moments is provided. Producing quality items with minimum cost requires keeping a production process under control. The quality characteristic X of each item produced is determined and the sample means are plotted on an Ẋ-control chart. A production process is assumed to start in control at time t = 0 with specific values of the mean and standard deviation. The occurrence of a single or multiple cause-failures shift the process mean outside the control limits. During the search for the causes of failure, the process is either allowed to continue in operation or shut down until the assignable cause or causes are discovered. The expected duration of time during which the process is shut down and the additional time to be taken to repair the process are considered. Computer programs are provided to estimate the optimal sample size, the interval between successive samples, the control limits, the probability of type I error, the power of the chart, and the average time the process operates in the presence of an assignable cause. The parameters estimated are employed to estimate the optimal loss-cost. The economic design of Ẋ -charts assumes one quality characteristic of interest. However a product quality in most industrial products and processes is characterized by more than one quality characteristic where the application of a Ẋ -control chart for each variable is inappropriate. In this work a Hotellings T² control chart is employed to handle cases of where products are tested relative to several quality characteristics.
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Poon, Yuen-fong, and 潘源舫. "Impact of family planning on economic development in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31974880.
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Ghebretensae, Manna Zerai. "A unified approach to the economic aspects of statistical quality control and improvement." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49865.
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Assignment (MSc)--Stellenbosch University, 2004.ENGLISH ABSTRACT: The design of control charts refers to the selection of the parameters implied, including the sample size n, control limit width parameter k, and the sampling interval h. The design of the X -control chart that is based on economic as well as statistical considerations is presently one of the more popular subjects of research. Two assumptions are considered in the development and use of the economic or economic statistical models. These assumptions are potentially critical. It is assumed that the time between process shifts can be modelled by means of the exponential distribution. It is further assumed that there is only one assignable cause. Based on these assumptions, economic or economic statistical models are derived using a total cost function per unit time as proposed by a unified approach of the Lorenzen and Vance model (1986). In this approach the relationship between the three control chart parameters as well as the three types of costs are expressed in the total cost function. The optimal parameters are usually obtained by the minimization of the expected total cost per unit time. Nevertheless, few practitioners have tried to optimize the design of their X -control charts. One reason for this is that the cost models and their associated optimization techniques are often too complex and difficult for practitioners to understand and apply. However, a user-friendly Excel program has been developed in this paper and the numerical examples illustrated are executed on this program. The optimization procedure is easy-to-use, easy-to-understand, and easy-to-access. Moreover, the proposed procedure also obtains exact optimal design values in contrast to the approximate designs developed by Duncan (1956) and other subsequent researchers. Numerical examples are presented of both the economic and the economic statistical designs of the X -control chart in order to illustrate the working of the proposed Excel optimal procedure. Based on the Excel optimization procedure, the results of the economic statistical design are compared to those of a pure economic model. It is shown that the economic statistical designs lead to wider control limits and smaller sampling intervals than the economic designs. Furthermore, even if they are more costly than the economic design they do guarantee output of better quality, while keeping the number of false alarm searches at a minimum. It also leads to low process variability. These properties are the direct result of the requirement that the economic statistical design must assure a satisfactory statistical performance. Additionally, extensive sensitivity studies are performed on the economic and economic statistical designs to investigate the effect of the input parameters and the effects of varying the bounds on, a, 1-f3 , the average time-to-signal, ATS as well as the expected shift size t5 on the minimum expected cost loss as well as the three control chart decision variables. The analyses show that cost is relatively insensitive to improvement in the type I and type II error rates, but highly sensitive to changes in smaller bounds on ATS as well as extremely sensitive for smaller shift levels, t5 . Note: expressions like economic design, economic statistical design, loss cost and assignable cause may seen linguistically and syntactically strange, but are borrowed from and used according the known literature on the subject.
AFRIKAANSE OPSOMMING: Die ontwerp van kontrolekaarte verwys na die seleksie van die parameters geïmpliseer, insluitende die steekproefgrootte n , kontrole limiete interval parameter k , en die steekproefmterval h. Die ontwerp van die X -kontrolekaart, gebaseer op ekonomiese sowel as statistiese oorwegings, is tans een van die meer populêre onderwerpe van navorsing. Twee aannames word in ag geneem in die ontwikkeling en gebruik van die ekonomiese en ekonomies statistiese modelle. Hierdie aannames is potensieel krities. Dit word aanvaar dat die tyd tussen prosesverskuiwings deur die eksponensiaalverdeling gemodelleer kan word. Daar word ook verder aangeneem dat daar slegs een oorsaak kan wees vir 'n verskuiwing, of te wel 'n aanwysbare oorsaak (assignable cause). Gebaseer op hierdie aannames word ekonomies en ekonomies statistiese modelle afgelei deur gebruik te maak van 'n totale kostefunksie per tydseenheid soos voorgestel deur deur 'n verenigende (unified) benadering van die Lorenzen en Vance-model (1986). In hierdie benadering word die verband tussen die drie kontrole parameters sowel as die drie tipes koste in die totale kostefunksie uiteengesit. Die optimale parameters word gewoonlik gevind deur die minirnering van die verwagte totale koste per tydseenheid. Desnieteenstaande het slegs 'n minderheid van praktisyns tot nou toe probeer om die ontwerp van hulle X -kontrolekaarte te optimeer. Een rede hiervoor is dat die kosternodelle en hulle geassosieerde optimeringstegnieke té kompleks en moeilik is vir die praktisyns om te verstaan en toe te pas. 'n Gebruikersvriendelike Excelprogram is egter hier ontwikkel en die numeriese voorbeelde wat vir illustrasie doeleindes getoon word, is op hierdie program uitgevoer. Die optimeringsprosedure is maklik om te gebruik, maklik om te verstaan en die sagteware is geredelik beskikbaar. Wat meer is, is dat die voorgestelde prosedure eksakte optimale ontwerp waardes bereken in teenstelling tot die benaderde ontwerpe van Duncan (1956) en navorsers na hom. Numeriese voorbeelde word verskaf van beide die ekonomiese en ekonomies statistiese ontwerpe vir die X -kontrolekaart om die werking van die voorgestelde Excel optimale prosedure te illustreer. Die resultate van die ekonomies statistiese ontwerp word vergelyk met dié van die suiwer ekomomiese model met behulp van die Excel optimerings-prosedure. Daar word aangetoon dat die ekonomiese statistiese ontwerpe tot wyer kontrole limiete en kleiner steekproefmtervalle lei as die ekonomiese ontwerpe. Al lei die ekonomies statistiese ontwerp tot ietwat hoër koste as die ekonomiese ontwerpe se oplossings, waarborg dit beter kwaliteit terwyl dit die aantal vals seine tot 'n minimum beperk. Hierbenewens lei dit ook tot kleiner prosesvartasie. Hierdie eienskappe is die direkte resultaat van die vereiste dat die ekonomies statistiese ontwerp aan sekere statistiese vereistes moet voldoen. Verder is uitgebreide sensitiwiteitsondersoeke op die ekonomies en ekonomies statistiese ontwerpe gedoen om die effek van die inset parameters sowel as van variërende grense op a, 1- f3 , die gemiddelde tyd-tot-sein, ATS sowel as die verskuiwingsgrootte 8 op die minimum verwagte kosteverlies sowel as die drie kontrolekaart besluitnemingsveranderlikes te bepaal. Die analises toon dat die totale koste relatief onsensitief is tot verbeterings in die tipe I en die tipe II fout koerse, maar dat dit hoogs sensitief is vir wysigings in die onderste grens op ATS sowel as besonder sensitief vir klein verskuiwingsvlakke, 8. Let op: Die uitdrukkings ekonomiese ontwerp (economic design), ekonomies statistiese ontwerp (economic statistical design), verlies kostefunksie (loss cost function) en aanwysbare oorsaak (assignable cause) mag taalkundig en sintakties vreemd voordoen, maar is geleen uit, en word so gebruik in die bekende literatuur oor hierdie onderwerp.
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Clarke, Damian. "Essays on fertility and family size." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:94016283-a3dd-4b6a-8427-373b49a491be.
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In these papers I discuss the causal estimation of the effects of fertility and fertility planning developments on mother and child outcomes. A number of concerns are raised with existing identification techniques, and alternative methodologies to consistently estimate the effect of interest are proposed. These concerns and new techniques are illustrated using microdata on slightly more than 43,000,000 births ocurring between 1972 and 2013. In the first substantive chapter (written with Sonia Bhalotra), we discuss the validity of the use of twin births in fertility research. We demonstrate that twin births are not random. Successfully taking twins to term depends upon positive maternal health behaviours and investments in the periods preceding birth. We show that this is of considerable concern for estimation techniques which rely on twin births being (conditionally) randomly assigned to identify causal effects. To illustrate, we consider the estimation of the child quantity-quality (QQ) trade-off, and show that existing instrumental variable estimates are inconsistent in the contexts examined. Upon partially correcting for the fact that twin births are not random, a statistically significant QQ trade-off begins to emerge. We close by examining a number of partial identification techniques to bound the true effect of fertility on child outcomes. In the second substantive chapter, I examine the effect of fertility control policies on the fertility decisions and outcomes of women. I consider the case of the emergency contraceptive pill in Chile. The staggered arrival of this technology to Chile over the last decade has resulted in the availability of the first safe and legal post-coital birth control policies. In a context of high teenage pregnancy rates, difference-in-difference (DD) style estimates suggest that this policy has accounted for reductions in short-term teen childbearing by as much as 7%, an effect similar to the arrival of abortion in the USA. This policy is also shown to reduce fetal deaths reported in early gestation with no similar reduction in late gestation: suggestive evidence that an alternative fertility control policy may reduce costly and dangerous illegal abortions. Finally, I turn to the use of DD estimators as a policy-analysis tool. I discuss how such estimators perform in the case of reforms which may not be sharply demarcated to treatment and control clusters, but rather subject to local spillovers or externalities. I propose an extension of the typical DD estimator: a spillover-robust DD estimator. This methodology is applied to estimate the effect of two localised fertility control reforms in Mexico and Chile, where women close to treatment clusters who were not themselves subject to the reform may nonetheless travel to access treatment.
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Kumar, Arun. "Ground control ramifications and economic impact of retreat mining on room and pillar coal mines." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49815.
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As the coal reserves at shallow depths become exhausted companies have to develop deeper deposits and increase percentage extraction to maintain production levels. Total extraction for room and pillar mines can only be achieved by pillar extraction. The unsupported roof increases during pillar extraction and hence the cost of ground control also increases. Nevertheless, pillar extraction where possible has many potential advantages such as decreased operating cost, increased utilization of reserves, and extended life of the mine. There are several variables such as depth, mining height, rock strength, mining geometry, roof and floor conditions, and retreat mining methods, which affect pillar extraction cost. Cost components of pillar extraction are classified as direct, indirect, fixed, and subsidence compensation costs. A discounted cash flow pillar extraction cost simulator has been developed and used to compute total pillar extraction cost for a variety of conditions and to explore the possibilities of optimizing ground control and retreat mining techniques to maximize extraction ratio. The computer program computes the safe and optimum pillar dimensions and determines the suitable pillar extraction method for the computed pillar width. Pillar extraction cost components are generated and totalled using the net present value method by the simulator. The total extraction cost simulator evaluates the potential advantages of pillar extraction and tests individual variables for sensitivity to changes in other variables attributable to ground control and pillar extraction techniques. Cost of pillar extraction per ton of coal versus depth is presented in the form of a simple nomogram by the simulator. The simulator can be used to determine the economic feasibility of pillar extraction at a particular depth, geologic and mining environment when the market price of mined coal is known.Ph. D.
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Keller, Martina [Verfasser], and Roland [Akademischer Betreuer] Gerhards. "Effects of weeds on yield and determination of economic thresholds for site-specific weed control using sensor technology / Martina Keller. Betreuer: Roland Gerhards." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2014. http://d-nb.info/1061069257/34.
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Turner, Peter J. "The impacts of the environmental weed Asparagus Asparagoides and the ecological barriers to restoring invaded sites following biological control." University of Western Australia. School of Animal Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0136.
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[Truncated abstract] Weeds which invade native communities can have major impacts on biodiversity and ecosystem processes. However, these impacts are rarely quantified, and the mechanisms behind these impacts are rarely investigated. Asparagus asparagoides (L.) Druce (Asparagaceae; common name: bridal creeper), a plant native to southern Africa, is a significant environmental weed in southern Australia. Bridal creeper can invade both disturbed and undisturbed native ecosystems and then dominate native communities. As is the case for many environmental weeds, there has been little work conducted on the impacts of this plant. This lack of knowledge has hampered restoration efforts of invaded areas because very little is known about the potential for invaded communities to recover prior to undertaking weed management. There is a need to improve our understanding of how to manage ecosystem recovery during and after weed control. This can be achieved by (i) determining the impacts caused by the weed; (ii) assessing the condition of invaded communities; and (iii) predicting the impacts that weed management itself will have on the native communities. These three prerequisites to environmental weed control have been determined across sites invaded by bridal creeper in southern Australia. The impacts of this invasive geophyte have been determined through multi-site comparisons, weed removal experiments and controlled glasshouse and laboratory experiments. ... Without additional restoration, we will see those species that readily germinate and those that respond positively to increased soil fertility, replacing bridal creeper after control. This will be dominated by other weeds as the invaded sites have large exotic seed banks that will readily germinate. The tuberous mats of older bridal creeper plants will also leave a legacy as they will remain many years after control and still impact on vegetation, even if control has killed the plant. These impacts will be highest at sites where bridal creeper has dominated over the longer term. Environmental weeds, such as bridal creeper, that are capable of altering ecosystem functions can lead to substantial declines in biodiversity. Therefore, it was fortunate that bridal creeper became a target for biocontrol in Australia even though the impacts of the weed were not quantified when this decision was made. There are areas in southern Australia that are still free of bridal creeper or have sparse populations, and it is highly likely that this biological control programme has lead to the protection of these areas. This protection would not have been possible if other control measures were chosen over biological control, given that biocontrol agents can self-disperse and are able to give continuous control. This means that biological control of weeds in conservation areas can be very effective and is the only economically viable option for the control of widespread environmental weeds such as bridal creeper.
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Law, Matthew Charles. "Willingness to pay for the control of water hyacinth in an urban environment of South Africa." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1002731.
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Water hyacinth is recognised as one of the most problematic invasive aquatic plant species in Africa. For this reason considerable funds are spent each year on itscontrol. As a consequence of the amount of money being spent on problems such as the invasion of water hyacinth, and because of the recognition of the ongoing and accelerated efforts that are required in the future, recent research has focused on accurately quantifying the costs and benefits of control of invasive species to aid policy decisions.A comprehensive cost-benefit analysis would be able to identify if the funds are justified and are being spent effectively. This thesis provides an example of a cost-benefit analysis of funds spent on the control of water hyacinth in an urban environment in South Africa. In order to develop a comprehensive assessment of the total economic value of the control of water hyacinth to an urban population, the Nahoon River in East London was selected as the study site to calculate the benefits of control. In addition to valuing the direct services provided by the resources that are traded in the market (in this case water provision), a contingent valuation study was undertaken in Abbottsford and Dorchester Heights (two suburbs in East London banking the Nahoon River). These were done in order to assess any non-use value a sample of 132 households of the population has for the control of water hyacinth, and any use values that are not traded in the market, for example recreational value. When the benefits of control of water hyacinth were compared to the costs of one of the least cost effective methods of control (herbicidal control), the benefits outweighed the costs by a ratio of more than 4:1, and for the most cost effective method of control the ratio was almost 6:1. These results provide a justification for the funds that are devoted to the control of water hyacinth, providing an argument for the continued expenditure for its control, and for further research into more cost effective methods of control, such as biological control.
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Jordan, Matthew. "Procuring industrial pollution control : the South Australian case, 1836-1975." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phj816.pdf.
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Willis, Eileen. "Accelerating control : an ethnographic account of the impact of micro-economic reform on the work of health professionals /." Title page, table of contents and abstract only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phw7341.pdf.
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Napit, Krishna Bahadur. "Economic impacts of extension integrated pest management programs in the United States." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/74524.
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Integrated pest management (IPM) is an approach to pest control which emphasizes the Integration of biological, cultural, and chemical control methods for optimal pest management. The purpose of this thesis is to empirically examine the level and distribution of net economic benefits of Extension IPM, and to assess the relative importance of socioeconomic factors in affecting the adoption of IPM in the states of Indiana, Virginia, Georgia, New York, North Carolina, Texas, Massachusetts, Mississippi and the Northwest region.
Budgeting and hypothesis testing procedures are used to conduct a net returns analysis. Consumer-producer surplus analysis is used to assess IPM benefits to producers and consumers. Finally, a polychotomous logit model is used to assess the importance of socioeconomic factors affecting IPM adoption.
The results of these analyses show significantly higher returns and less variability of returns per acre for users of IPM as compared to non-users. Moreover, consumers receive significant positive economic gains. However, pesticide cost and the variance of pesticide cost per acre increase with increasing levels of IPM use in several states but decrease in a few others. Gross farm income, percent family income from farming, frequency of contacts with Extension agents, and the education level of respondents are the most important factors related to adoption of IPM. A typical user of IPM is white, male, with at least some college education, has frequent contacts with Extension agents, has a relatively large farm, higher gross farm income, and a higher percent family income from farming.Master of Science
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Wable, Olivier. "Design and operation of a tubular photobioreactor for microalgea production." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/10126.
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Khajehei, Sepideh. "From Probabilistic Socio-Economic Vulnerability to an Integrated Framework for Flash Flood Prediction." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4666.
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Flash flood is among the most hazardous natural disasters, and it can cause severe damages to the environment and human life. Flash floods are mainly caused by intense rainfall and due to their rapid onset (within six hours of rainfall), very limited opportunity can be left for effective response. Understanding the socio-economic characteristics involving natural hazards potential, vulnerability, and resilience is necessary to address the damages to economy and casualties from extreme natural hazards. The vulnerability to flash floods is dependent on both biophysical and socio-economic factors. This study provides a comprehensive assessment of socio-economic vulnerability to flash flood alongside a novel framework for flash flood early warning system. A socio-economic vulnerability index was developed for each state and county in the Contiguous United States (CONUS). For this purpose, extensive ensembles of social and economic variables from US Census and the Bureau of Economic Analysis were assessed. The coincidence of socio-economic vulnerability and flash flood events were investigated to diagnose the critical and non-critical regions. In addition, a data-analytic approach is developed to assess the interaction between flash flood characteristics and the hydroclimatic variables, which is then applied as the foundation of the flash flood warning system. A novel framework based on the D-vine copula quantile regression algorithm is developed to detect the most significant hydroclimatic variables that describe the flash flood magnitude and duration as response variables and estimate the conditional quantiles of the flash flood characteristics. This study can help mitigate flash flood risks and improve recovery planning, and it can be useful for reducing flash flood impacts on vulnerable regions and population.
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Rini, Lulama Angela. "Modifying an artificial diet for mass rearing mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), using locally available maize meal." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53500.
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Thesis (MSc)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: The Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is well-known as a destructive pest of fruit worldwide. Various control methods have been used against this insect. The sterile insect technique (SIT) is used as an important and successful technological method for controlling or eradicating this pest in many countries. A key factor to successfully apply SIT is dependent on the availability of efficient and economical rearing methods. Artificial insect diets with low cost bulking agents have been of interest to many researchers. The present study investigated the use of locally available maize meal as a bulking agent in such diets. Maize meal is used for human consumption (in South Africa) and contains small amounts of protein. This makes the reduction of imported torula yeast as an ingredient of the diet and source of protein possible, thereby reducing the cost of the diet. The larval development of the Medfly reared on artificial diets was studied in small and large-scale tests. The effect of the diets on larval production was evaluated using pupal recovery, pupal weight, flight ability, sex ratio, fecundity and egg fertility. The results of the small-scale tests showed that the diet containing maize meal could be used to produce Medfly more economically than the standard Krige diet used by the ARC Infruitec-Nietvoorbij Research Institute at Stellenbosch. However, in large-scale tests the ingredients quantities of the diets used were not the same as those of small scale-tests. The cost of the modified larval diet was not reduced in large-scale tests. This was ascribed to the number of eggs used in the tests to produce one million of fruit flies. The maize meal with reduced number of eggs require more diet to produce one million flies therefore, making it more expensive and less viable. When similar amounts of eggs were used, the diet appears to be a suitable alternative as the result obtained was almost similar to those of the Krige diet.
AFRIKAANSE OPSOMMING: Die Mediterreens vrugtevlieg ("Medfly"), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is wêreldwyd 'n skadelike plaag. Die steriele insek tegniek (SIT) het in baie lande 'n belangrike en suksesvolle manier geword om die plaag te beheer en uit te roei. Die belangrikste voorvereiste vir die suksesvolle toepassing van SIT is die beskikbaarheid van doeltreffende en ekonomiese teelmetodes. Meeste navorsers is geïntereseerd in kunsmatige diëte met 'n goedkoop vulstof. Hierdie studie is ontwerp om die gebruik van plaaslik beskikbare mieliemeel as vulstof te ondersoek. In Suid-Afrika word dit vir menslike gebruik aangewend en bevat klein hoeveelhede proteïene wat 'n vermindering van die ingevoerde torula gis moontlik kan maak, en sodoende die koste van die dieët kan verminder. Die ontwikkeling van Medfly larwes op kunsmatige diëte is bestudeer In kleinskaalse en grootskaalse eksperimente. Die invloed van die diëte op larwale produksie is evalueer deur gebruik te maak van van papie-ontwikkeling, papie-gewig, vliegvermoë, geslagsverhouding, volwasse voortplantingsvermoë en eiervrugbaarheid. Die resultate van die kleinskaalse toetse het aangetoon dat die mieliemeel dieët gebruik kan word om Medfly meer ekonomies as met die standaard Krige dieët, wat in die ARC Infruitec-Nietvoorbij navorsings instituut by Stellenbosch gebruik word, te teel. By die grootskaalse toetse was die koste nie laer nie. Dit word toegeskryf aan die aantal eiers wat gebruik is om 'n miljoen vlieë te produseer. Die mieliemeel dieët met 'n verminderde aantal eiers benodig meer dieët om 'n miljoen vlieë te produseer, wat dit duurder en minder lewensvatbaar maak. Wanneer soortgelyke hoeveelhede eiers gebruik was, het dit geblyk dat die dieët 'n opsie is, want die resultaat was soortgelyk aan dié van die Krige dieët.
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Cheng, Sau-kong, and 鄭守崗. "Diabetic end-stage renal disease (ESRD): can health care costs be saved through blood pressure control?" Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B39723951.
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Akpabey, Felix Jerry. "Quantification of the cross-sectoral impacts of waterweeds and their control in Ghana." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1005435.
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The Akosombo Dam on the Volta River in Ghana was built in 1963 to provide cheap energy to fuel industry and to accelerate the economic growth of the country. It provides hydroelectric power, enhanced fishing and water transportation upstream, and improved opportunities for irrigated farming, especially in the lower reaches, and their attendant economic multiplier effects. A few years after the construction of this major dam, a rapid expansion of industrialization took place in Ghana. This brought about an exponential increase in demand for more electrical power. This led to the construction of a smaller dam at Akuse, downstream of the Akosomho Dam in 1981 and the formation of a headpond at Kpong. The impoundment of the river at the two sites (Akosombo and Kpong) caused an alteration in the existing ecological and biophysical processes in the river basin, including a slowing of the flow of the river, upstream and downstream. Changes in the natural processes, such as a reduction in the flow of the river and an increase in nutrient status of the water, resulted in an invasion of aquatic weeds, increasing the density of aquatic snails (intermediate hosts of schistosomiasis), silting and closure of the estuary, as well as other more subtle effects. The invasion of the river's main course and the dams by aquatic plants led to a corresponding reduction of navigable water both upstream and downstream. The aim of this thesis was to quantify the impact and control of waterweeds, especially water hyacinth, Eichhornia crassipes (Mart) Solms-Laubach (Pontederiaceae), in Ghana. A floral survey on the Kpong Headpond recorded 49 emergent, 12 free floating and I submerged aquatic plant species, many of which were indigenous, but the exotic or introduced water hyacinth was recorded at most of the sampling sites, and was the most abundant and had the biggest impact on the utilization of the water resource. Mats of water hyacinth served as substrates for other, indigenous species to grow out into the main channel of the headpond, including the intake point of the Kpong head works of the Ghana Water Company Limited (GWCL) and landing sites for boats. These mats resulted in a reduction of the fish (fin and shell) harvest, reducing the annual production to far below demand. Water hyacinth was also shown to have severe health implications. A survey of the Ministry of Health records showed that the prevalence of both urinary and intestinal schistosomiasis had risen significantly over time as the abundance of waterweeds, most notably water hyacinth, increased, and ranged between 70% and 75% but up to 100% in some lakeside communities. Based on the work done by an NGO on board the medical boat ("Onipa Nua "), losses in terms of money due to the effect on health of the aquatic weed infestations on the Volta River in 2006 amounted to US$ 620,000. Economic losses due to invasive alien aquatic weeds were also calculated on the Oti River Arm of Lake Volta. It was estimated that about US$2.3 million per annum would be lost to the Volta Lake Transport Company and individual boat transport operators if this section of the river were 100% covered by aquatic weeds (water hyacinth and Salvinia molesta D.S. Mitchell (Salviniaceae)). It was also estimated that US$327,038 was spent annually in monitoring and managing the weeds in the Oti River. Control interventions for aquatic weeds have been implemented in river systems in Ghana. The biological control agents Neochetina bruchi Hustache (Coleoptera, Curculionidae) and Neochetina eichhorniae Warner (Coleoptera, Curculionidae) have been used on water hyacinth infestations in the Oti River Arm of Lake Volta, the Tano River and the Lagoon complex in the south-western part of the country. Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae) has been used to control salvinia, and Neohydronomous affinis Hustache (Coleoptera: Curculionidae) to control water lettuce, Pistia stratiotes Lilmaeus (Araceae) in the Tano River and Lagoon complex. Although these projects have been regarded as successful, they have relied on research from elsewhere in the world and no postrelease quantification has been conducted. In evaluating the impact of the biological control agents Neochetina bruchi and Neochetina eichhorniae weevils on water hyacinth infestations in the Tano River, fresh adult feeding scars were recorded as well as the numbers of adult weevils on each water hyacinth plant sampled at six sites. Despite being released in 1994, weevil numbers and resultant damage to plants in the Tano Lagoon was low in comparison to other regions of the world where these agents have been used. The main reason for this is that this lagoon floods seasonally, washing weevil-infested plants out to sea. Water hyacinth then re-infests the lagoon from seed and the weevil populations are low. To resolve this situation, two courses of action are proposed. The first is to mass rear the weevils along the shore of the lagoon and release them when the first seedlings recruit. The second proposal is that additional agents that have shorter lifecycies and are more mobile than the weevils should be released. To this end, the water hyacinth mirid, Eccritotarsus catarinensis (Carvalho) (Hemiptera: Miridae) was imported from South Africa and released onto the Tano Lagoon in 2009. Retrospective laboratory host specificity trials were conducted on Neachetina eichharniae and Neachetina bruchi weevils 15 years after their release into Ghana to see if any variation in their host ranges had occurred. Considerable damage was inflicted on the E. crassipes leaves by the Neachetina weevils, while little feeding damage was recorded on both Heteranthera callifalia Kunth. (Pontederiaceae) and Eichharnia natans (P.Beauv.) Solms (Pontederiaceae). All the weevils introduced on H callifalia and E. natans died after the first week. This study served to confirm the host specificity and thereby the safety of these agents. Invasive alien aquatic macrophytes have negative impacts on the environment and economy of Ghana. The control of these weeds is essential to socioeconomic development and improved human health standards in riparian communities. Biological control offers a safe and sustainable control option, but requires diligent implementation. However, aquatic weed invasion is more typically a result of the anthropogenically induced eutrophication of water bodies, and this is the main issue that has to be addressed.
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Rahman, Baishali. "Estimating the Economic Benefits of Automatic Section Control in the North Dakota Prairie Pothole Region." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/28870.
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The impact of Automatic Section Control (ASC) as a tool of Precision Agricultural Technology as considered in the more efficient application of inputs to produce the four major crops, corn, soybean, HRSW, and canola in the North Dakota Prairie Pothole Region. Reduction in machinery overlap in the sample 105 fields was calculated by simulating the routing paths of a 60-feet wide planter with 24 sections controlled and a 120-feet wide boom sprayer with individual nozzle control. The dollar and percentage seed and chemical costs that a farm can save by reducing overlapping area were calculated. Impact of field parameters on net savings were estimated by developing and estimating an econometric model. Results show that ASC can save substantial cost in the sample fields while field shape had the highest significant impact on net cost savings.North Dakota State University. Department of Agribusiness and Applied Economics
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Amrouk, El Mamoun. "The economic implications of combining fibre flax contracting along with futures and options to control for farm revenue instability in Quebec /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31182.
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Due to a rising interest in natural fibres for textiles as well as environmental concerns, the demand for fibre flax has increased in recent decades. It was, therefore, with great enthusiasm that Canadian farmers welcomed, in 1997, the opening of a flaxprocessing unit in the region of Salaberry-de-Valleyfield, Quebec. The purpose of this study was to investigate the economic viability of fibre flax contracting as an alternative activity for field-crop producers in Quebec. A risk-programming model called minimization of total absolute deviation (MOTAD) was developed to better approach this issue. The MOTAD takes into account the variability in income that stems from uncertainty in commodity-market prices and yields. In addition, five different marketing strategies for pricing grain corn and soybeans were included in the model. These pricing techniques combined the use of futures and options markets.In a global agricultural system, where international commitments force governments to cut subsidies, reducing income variability for risk-averse farmers becomes a critical challenge. This study offered to assess the contribution of both contracting and futures markets as alternative market instruments for risk management. Five portfolio farm plans were identified for 200- and 300-hectare farm sizes. The results showed that gains through fibre flax contracting, in terms of risk reduction, exist only for the farm plans with lower levels of income and risk. Moreover, simulations demonstrated that the use of futures and options markets can help maximize overall net farm return.
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Beyers, Hendrik Philippus. "The effect of haloxyfop-R-methyl ester and imazamox herbicides, tine or no tillage and nine different medic cultivars on the seed and dry matter production as well as the quality of medic pastures." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52517.
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Thesis (MScAgric)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: The aim of this study was to determine the effect of a grass herbicide, a broadleaf herbicide with some grass control capabilities, method of tillage (tine and no-tillage) at planting of wheat as well as different medic cultivars on the regeneration, dry matter (OM) production and quality of a medic pasture. The trial was conducted at Langgewens experimental farm in the Swartland wheat producing area. Nine medic cultivars of three different species were evaluated after being sprayed with either haloxyfop-R-methyl (HAL) ester or imazamox (IMI) and subjected to either a tine tillage or a no tillage treatment at planting of wheat. Soil samples were taken during January 2000 to determine the size of the medic and weed seedbank as well as the degree of dormancy in the medic seeds, while OM samples were taken throughout the growing season to determine the OM production of the different medic cultivars and weed species. OM samples taken during October 1998 on the same pasture, were used to determine the crude protein (CP) and neutral detergent fibre (NOF) content of the pasture. The samples were subjected to in vitro digestion and the digestibility of pasture CP (OCP), NOF(ONOF) and DM (DOM)were determined. Results showed that seedling establishment differed between cultivars used, herbicide treatments applied as well as the crop stage in the rotation. The cultivars produced more seedlings where IMI was applied compared to HAL as well as where the area consisted of two year pasture compared to one year pasture (1998) and one year wheat (1999). After a year of pasture and a year of wheat, cultivars Sephi and Paraggio produced the most seedlings, while Caliph and Orion produced the least. Caliph however, showed a very high degree of seed dormancy while Orion's low seedling establishment was due to its sensitivity to the IMI herbicide used. Little difference was found between the nine cultivars early in the season (July - August) with regard to cumulative OM production, except for Orion, whose growth was severely damaged by the IMI treatment. At the end of the growing season (October), the cultivar Caliph's cumulative OM production (2010.1 kg/ha) was significantly higher than all the other cultivars, except for Parabinga (1053. 4 kg/ha). Oifferent pasture samples, of which the botanical composition was known, was analysed for CP, NOF, OOM, OCP and ONOF. There was no significant difference in pasture composition during 1998 but variation in the pasture composition did however cause the IMI treatment, compared to the HAL treatment, to have a lower ONOFand OOMcontent. A modelling procedure was used to predict the pasture quality parameters (CP, NOF, OOM,OCP and ONOF) from the pasture composition (medic hay, medic pods, grassy and broadleaf weeds). This prediction of CP, NOF, OOM, ONOF and OCP from the pasture components had a relative low accuracy (49 -74.1 %) and a further refinement of this model for possible use on farms in order to improve grazing management and animal production is advised. In conclusion it could be said that broadleaf weed control caused a definite increase in medic seed and OMproduction, but Orion should not be used with an IMI herbicide. All the cultivars, except for Orion, produced enough seedlings up to the second year to ensure sustainability of the medic pasture. All the cultivars, except for Orion, produced a sufficient amount of OM early in the growing season. Caliph however, produced by far the most OM later in the growing season. A reduction of broadleaf weeds and medic pods will increase the digestibility of NOFand OMand therefore increase the quality of the pasture. Pods however are an important part of summer forage and the aim should therefore rather be to reduce the number of broadleaf weeds in the pasture.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van 'n gras en breëblaar onkruiddoder (wat sekere grasse beheer), metode van bewerking tydens die saai van koring asook nege verskillende medic kultivars op die regenerasie, droë materiaal produksie en kwaliteit van medic weidings te bepaal. Die proef is gedoen op Langgewens proefplaas wat geleë is in die Swartland koring produserende gebied. Nege medic kultivars is geëvalueer nadat die weiding met of haloxyfop-R-metiel ester (HAL) of imazamox (IMI) onkruiddoders gespuit is en onderwerp is aan of 'n vlak tand of geen bewerking tydens die saai van koring. Grondmonsters is geneem in Januarie 2000 om die grootte van die medic en onkruid saadbank asook om die graad van dormansie in die verskillende medic kultivars se sade te bepaal. Droë materiaal monsters is gedurende die 2000 groeiseisoen geneem om die droë materiaal produksie van die verskillende medic kultivars asook onkruid spesies te bepaal. Droë materiaal monsters is gedurende Oktober 1998 geneem en gebruik om die ruproteïn (CP) en neutraaloplosbare vesel (NDF) inhoud van die weiding te bepaal. Die monsters is in vitro verteer en die verteerbaarheid van CP (OCP), NDF (ONOF) en droë materiaal (DOM) is bepaal. Resultate wys dat saailing vestiging verskil tussen die verskillende kultivars wat gebruik is, verskillende onkruiddoder behandelings asook die stadium van die weidings/koring. Die kultivars het meer geproduseer waar die weiding met IMI behandel is in vergelyking met waar HAL toegedien is, asook waar koring nog nie gesaai is nie. Na 'n jaar van weiding en 'n jaar van koring, het die kultivars Sephi en Paraggio die meeste saailinge, en Caliph en Orion die minste saailinge gehad. Caliph het egter 'n hoë graad van dormansie in sy saad getoon, terwyl die swak vestiging van Orion die gevolg is van die kultivar se hoë sensitiwiteit teenoor IMI. Min verskil is gevind tussen die nege kultivars, vroeg in die groei seisoen (Julie - Augustus), wat kumulatiewe droë materiaal produksie betref, behalwe vir Orion wat erg beskadig is deur die IMI behandeling. Aan die einde van die groeiseisoen (Oktober 2000) was die kumulatiewe droë materiaal produksie van die kultivar Caliph (2010.1 kg/ha) betekenisvol hoër as al die ander kultivars behalwe vir Parabinga (1053.4 kg/ha). Weidingsmonsters, waarvan die botaniese samestelling bekend was, is ontleed vir CP, NDF, DDM, DCP en DNDF. Daar is geen betekenisvolle verskille gevind in die botaniese samestelling van die weidingmonsters geneem in 1998 nie,maar die variasie in botaniese samestelling het veroorsaak dat IMI in vergelyking met HAL 'n laer DNDF and DDM inhoud het. 'n Model is opgestel wat die weidingskomponente (medic hooi, medic peule, gras en breëblaar onkruide) gebruik om die kwaliteits parameters (CP, NDF, DDM, DCP en DNDF) van die weiding te skat. Hierdie skatting van CP, NDF, DDM, DCP en DNDF deur van die weidingskomponente gebruik te maak het 'n relatiewe lae akuraatheid gehad (49 -74.1 %) en verdere verfyning van hierdie model vir moontlike gebruik op plase, ten einde weidings bestuur en diere produksie te verbeter, word voorgestel. Die gevolgtrekking kan gemaak word dat breëblaar onkruidbeheer 'n definitiewe verbetering in die medic saailing en droë materiaal produksie van die medies te weeg gebring het, maar die kultivar Orion behoort nie saam met 'n IMI gebruik te word nie. AI die getoetste kultivars, behalwe Orion, het voldoende saad oorlewing vertoon tot en met die tweede jaar van die rotasie om lewensvatbaarheid van die sisteem te verseker en alle kultivars, behalwe Orion, het voldoende droë materiaal produseer vroeg in die groeiseisoen. Caliph het egter laat in die groeiseisoen by verre die meeste droë materiaal geproduseer. 'n Vermindering in die hoeveelheid breëblaar onkruide en peule in die weiding sal tot 'n verhoging in die verteerbaarheid van NDF en DM lei en dus 'n verhoging in die kwaliteit van die weiding tot gevolg hê. Peule is egter 'n belangrike bron van voedsel aan weidende diere gedurende droë somermaande en die verbetering van weidings moet eerder gedoen word deur te poog om breëblaar onkruide te beheer.
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Alarcón, Pablo López. "Optimizing post-weaning multi-systemic wasting syndrome control taking into account economics aspects and management of information in decision making by farmers." Thesis, Royal Veterinary College (University of London), 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.572446.
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Shifidi, Victoria Tuwilika. "Socio-economic assessment of the consequences of flooding in Northern Namibia." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96066.
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Thesis (MA)--Stellenbosch University, 2014.ENGLISH ABSTRACT: This study was conducted in the Cuvelai Basin in Northern Namibia to assess vulnerability and socio-economic impacts of flooding on local residents, and to suggest ways to counteract the consequences of flooding in rural areas of the Basin. This followed severe flooding in 2009, 2011 and 2012. These combined flooding episodes had a substantial impact on local residents and the Namibian economy, with estimated losses of approximately US$136.4 million (NAD1364 million) in direct damage and US$78.2 million (NAD780 million) in indirect losses. The consequences of flooding amounted to ~1% of the country’s 2009 Gross Domestic Product (GDP). Rural residents in the Cuvelai Basin live predominantly on small farm holdings (‘ekove’) allocated by local village leadership, and depend heavily on subsistence farming for their livelihoods. Since higher-lying ground with soil best suited for crop production becomes scarcer, residents are allocated land in low-lying areas which are smaller and more susceptible to floods. The destruction of crops, farm and grazing land, trees and livestock, by floods and similar disasters is of a huge concern. The study sought to assess the impacts of flooding, geographical or physical circumstances that place residents at risk, and socio-economic conditions that lead to vulnerability. The study also attempted to assess whether traditional leaders (headmen) and village residents can use flood risk maps to create plans to reduce flood vulnerability. Over the past flood years, initiatives by the government to cope with floods have been response (relief), short-term and heavily donor dependent. To cope with floods and agro-climatic changes in their basin, rural residents have evolved their practices, some of which are traditional, to help lessen the impacts of floods on their livelihoods. Unfortunately such knowledge is not fully acknowledged by policy, decision makers and disaster risk managers. As a result of this knowledge gap, the study’s objective of compiling these practices, serves as a means to document localized traditional flood response, mitigation and adaptive measures. Moreover, the study will suggest contemporary adaptive measures as recommended by the local rural residents. Residents in 314 households were interviewed during August to November 2012. The households were selected following recommendations by village headmen, and consisted of 273 flooded homes, 42 village leaders, and 35 homes that were not flooded from 45 randomly selected villages. The qualitative data was captured, pre-coded, processed and analysed in Microsoft Excel, SPSS and STATISTICA to derive descriptive and inferential statistics. Following consultations with village headmen and residents, recommendations were made on practical adaptive strategies to flooding. The study found that there is a need to foster community level participation, buy-in and involvement in disaster risk management strategies in order to reduce the gap between technical early warning mechanisms and indigenous knowledge. Results revealed that households with coinciding socio-economic and geographic vulnerability are heavily impacted by flood disasters. However, these two vulnerabilities are not directly proportional to each other. Other vulnerable groups in society were outlined and structural and non-structural mitigation and preparedness measures at household level were recommended by the residents. It is the study’s intention that this will assist in strengthening local residents adaptive capabilities during events of flooding, thereby mitigating their impacts. The project’s intention of documenting this technical and indigenous knowledge, will serve as a knowledge base that can be compiled and integrated into an effective village friendly flood early warning system. It is further hoped that this initiative will garner support at the policy level and contribute to the prioritization of flood response to pending disasters being placed at the centre of development planning and execution.
AFRIKAANSE OPSOMMING: Hierdie studie is uitgevoer in die Cuvelai-opvangsgebied om die kwesbaarheid en sosio-ekonomiese impak van vloede op die plaaslike inwoners te bepaal ten einde maniere te vind om die gevolge van oorstromings in die landelike gebiede van die Cuvelai teen te werk. Ernstige oorstromings in 2009, 2011 en 2012 het 'n aansienlike impak op die Namibiese ekonomie gehad met geraamde verliese van ongeveer US$136.4 million (NAD1364 million) in direkte skade en US$78.2million (NAD780 million) in indirekte verliese vir die land. Ongeveer een persent (1%) van die land se 2009 bruto binnelandse produk (BBP) is benut om die gevolge van hierdie oorstromings aan te spreek. Landelike inwoners in die Cuvelai-opvangsgebied woon op kleinhoewes, plaaslik bekend as ekove, wat toegeken word deur plaaslike gemeenskapsleierskap. Hulle is hoofsaaklik afhanklik van bestaansboerdery. Aangesien hoër-liggende gebiede met goeie landboupotensiaal toenemend skaarser word, word nuwe kleinhoewes toegeken in laer-liggende gebiede, waar die negatiewe gevolge van oorstromings op inwoners erger kan wees. Skade aan gewasse, landbougrond en weiding, boorde en vee deur oorstromings en soortgelyke rampe is dus kommerwekkend. Die doelstelling van die studie was dus om die impak van oorstromings te bepaal, die geografiese of fisiese omstandighede wat plaaslike inwoners in gevaar stel te evalueer, en sosio–ekonomiese toestande wat lei tot kwesbaarheid te bepaal. Verdere doelwitte was om vas te stel of gemeenskapleiers en plaaslike inwoners vloedrisikokaarte kan gebruik om vloedkwesbaarheid te bepaal, in oorleg met plaaslike owerhede en inwoners alternatiewe praktiese aangepaste strategieë vir oorstromings vas te stel en aanbevelings aan die nasionale rampsbestuursbeleid en praktyk waar toepaslik te maak. Tydens die afgelope oorstromings was regeringsinisiatiewe om oorstromings te hanteer korttermyn vloedverligting, grootliks afhanlik van skenker. Om vloede en landbou-klimaatsveranderinge the hanteer, het landelike inwoners nuwe praktyke ontwikkel, sommige van tradisionele aard, om die impak van oorstomings op hulle lewensbestaan the verminder. Ongelukkig word sodanige kennis nie ten volle erken deur beleid, besluitnemers en ramprisikobestuurders nie. As gevolg van hierdie kennisgaping, dien die studiedoelwit om hierdie praktyke saam te stel die doel om gelokaliseerde tradisionele maatreëls aangaande vloedreaksie, versagting en aapasbaarheid te dokumenteer. Verder sal die studie onlangse maatreëls voorstel soos aanbeveel deur die plaaslike landelike inwoners. Ten einde kwalitatiewe data van die gemeenskappe wat in die Cuvelai woon te bekom is daar vir vier maande (Augustus tot November 2012) opnames gedoen by 314 huishoudings, gekies op aanbeveling van die plaaslike owerhede wat insluit 273 vloedslagoffers, 42 gemeenskapsleiers, en 35 huishoudings wat nie deur vloede beïnvloed is nie, vanuit 45 verskillende gemeenskappe. Die kwalitatiewe data is opgeneem, vooraf-gekodeer, verwerk en ontleed in Microsoft Excel, SPSS en STATISTICA om beskrywende en inferensiële statistieke te bekom. Die studie het bevind dat daar 'n behoefte is om die vlak van gemeenskapsdeelname te bevorder, inkoop en betrokkenheid by die ramp risikobestuurstrategieë te verkry ten einde die tegniese gaping tussen vroeë waarskuwingsmeganismes en inheemse kennis te verminder. Die studie het ook getoon dat huishoudings met ‘n gekombineerde sosio-ekonomiese en geografiese kwesbaarheid groter newe-effekte ondervind van vloedrampe. Die twee kwesbaarhede is egter nie direk eweredig aanmekaar nie. Ander kwesbare groepe in die samelewing is uitgewys, en strukturele en nie-strukturele versagting en paraatheidsmaatreëls op huishoudelike vlak is deur die inwoners aanbeveel. Die studie se doelwit is om die aanpasbaarheid van die plaaslike inwoners tydens oorstromings te bevorder, en sodoende die impak te verminder. Dokumentasie van hierdie tegniese en inheemse kennis sal dien as 'n kennisbasis wat saamgestel en geïntegreer kan word in 'n effektiewe gemeenskapsvriendelike vroeë vloedwaarskuwingstelsel. Indien hierdie inisiatief ondersteuning vind op beleidsvlak, kan dit bydra tot die prioritisering van vloed- en rampreaksie in ontwikkelingbeplanning en uitvoering.
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Simpson, Katherine Hannah. "Public choice for flood defence." Thesis, University of Stirling, 2015. http://hdl.handle.net/1893/22596.
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Why do we want to value the environment? Environmental assets provide a flow of goods and services over time which benefit mankind. Valuing these services contributes towards their protection and enhancement, however many of these benefits cannot be valued in traditional markets and as such rely on non-market valuation techniques. One of these is contingent valuation (CV) which directly asks respondents whether they are willing to pay for an improvement in the good or service. This thesis seeks to explore methodological issues associated with this method by undertaking a CV survey to elicit willingness to pay (WTP) for a new type of flood defence (managed realignment) on the Tay Estuary, Scotland. One challenge for survey designers is to provide high quality, readily understandable information to mitigate bias in WTP estimates. This thesis contributes to the information provision literature by examining whether prior knowledge or new information has a greater effect on the WTP estimate when controlling for respondent experience and familiarity with the good. A field experiment was designed to test for respondent’s prior knowledge; allow for varying levels of information to be presented to respondents and identify information acquisition for each respondent. Specifically tested was the notion that respondents who learn the most about the good during the survey process will have a more robust WTP estimate. Results were mixed: a causal relationship between information provision and learning was established with respondents in the higher treatment groups scoring higher in the second quiz. However, there was no relationship identified between prior knowledge, information provision and WTP. Personal motivations were the strongest predictors of WTP: those who were most concerned about flood risk and who lived closest to the proposed flood defence were willing to pay the most. A second issue in CV is consequentiality. Carson and Groves (2007) argue that for a survey to produce meaningful information about respondent’s preferences the respondent must view their responses as potentially influencing the supply of the public good. This thesis seeks add to this relatively new literature by exploring the observable factors which may influence respondents perceived consequentiality; specifically the effects of familiarity and information. Respondents were asked to state how confident they were that the results of the survey would be used by policy makers on a Likert scale ranging from “very unconfident” through to “very confident”. Results conformed to the Carson and Groves knife edge result: consequential respondents had significantly different WTP distributions compared to inconsequential and unsure respondents and were willing to pay significantly more towards the scheme. Consequential respondents also conformed the theoretical considerations of construct validity whilst inconsequential respondents did not. Respondents with more prior knowledge also appeared to be more likely to perceive the survey as consequential, although this was not consistent across all treatment groups. There is a concern that WTP and consequentiality are endogenous: respondents who want the policy to go ahead may be more likely to state the survey is consequential and state a high WTP in the hope these responses combined contribute to the policy maker’s decision. From a policy perspective the high level of support for the new scheme was encouraging and in contrast to previous findings on preferences for managed realignment. From a flood risk management perspective a “miss-match” between actual and perceived flood risk was highlighted, with many respondents stating they were not at risk from flooding when they in fact were. This is potentially concerning as respondents may not be taking adequate steps to protect their home from future flood risks. Overall it is recognised that values derived from the CV survey form one small part of the planning process and while informative, the decision for a scheme to take place should not be based on these values alone.
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陳亦朗 and Yik-long Pearl Chan. "The relationship between rent control and the emergence of cage housesin Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31256715.
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Nqobizitha, Dube. "Economic evaluation of possible loss of Prosopis pods as a result of biological control in the Northern Cape Province, South Africa." Thesis, University of Fort Hare, 2009. http://hdl.handle.net/10353/394.
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Species of Prosopis (Mimosaceae), or mesquite, are native to the Americas and introduced in South Africa as agro forestry trees to provide wood, fodder and shade in the late 1800s. In the Northern Cape Province, these trees have been particularly used for their pods by local farmers and local industry. However due to Prosopis’ ability to spread rapidly there has been increasing pressure to step up control of the tree. Due to the costs associated with most control methods biological control has been singled out as the most viable control method worth pursuing. This thesis attempts to explain and shed light on the effects that increased biological control of Prosopis would have on the farming community and Prosopis based businesses in the area. Two hypothetical scenarios were used, the first being a possible 50% reduction in available pods and the other a possible 100% reduction. In an effort to explain these effects data was collected from a series of collection activities in the form of a pilot study and two unique questionnaire surveys. Twenty-seven farmers and one Prosopis based business were interviewed at random with the data analysed and documented. Results showed that the business community is the main user of pods incurring crippling losses in the event of a 50% or 100% decrease in available pods. Using control costs from working for water De Aar long term costs of the presence of Prosopis were estimated and compared to the estimated provincial cost of losing pods giving a cost comparison ratio of (α)270 million : Y(N(15.7million)). Only 48% of the respondents valued pods and 11% had traded in pods, the top concern resulting from the invasion was the loss of underground water. With a 50% decline in available pods, all respondents indicated unchanged effects. However empirical results showed that with a 100% decline in pods estimate losses of R 5 818 per farm are expected. The cost comparison ratio showing the losses farmers bore with Prosopis in the area and the losses they would suffer with a 100% decline in pods was R11 389 + (K): R5 818. In light of the empirical results, policy recommendations that support the introduction of more effective biological control agents have been made with areas for further research identified and discussed.
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Mugisha, Anthony. "Socio-economic and gender aspects of control of vector-borne diseases : a study of intra-household dynamics and decision-making in the pastoralist system of southwestern Uganda." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402599.
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Borger, Catherine. "The biology and ecology of Salsola australis R.Br. (Chenopodiaceae) in southwest Australian cropping systems." University of Western Australia. School of Plant Biology, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0062.
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Salsola australis is an introduced weed of crop and pasture systems in the Western Australian broad acre cropping and pasture region (wheat-belt). This thesis investigated the classification, biology and ecology of the genus Salsola in southwest Australia, as well as modelling the effectiveness of possible weed control practices. Prior to this research, S. tragus was the only recognised species of the Salsola genus within Australia. However, genetic analysis revealed that four genetically distinct putative taxa of the genus Salsola were found in southwest Australia, none of which were S. tragus. The taxa that is the most prevalent agricultural weed was classified as S. australis, but the other three putative taxa could not be matched to recognised species. All four taxa were diploid (2n = 18), as opposed to tetraploid (2n = 36) S. tragus. Within the agricultural system of southwest Australia, S. australis plants established throughout the year, although the majority of seed production occurred in late summer and autumn. Total seed production (138-7734 seeds per plant) and seed viability (7.6-62.8%) of S. australis were lower than that reported for other agricultural weed species of the Salsola genus. Seed dispersal occurred when the senesced plants broke free of their root system to become mobile. Wind driven plants travelled and shed seed over distances of 1.6 to 1247.2 m. Movement of approximately half the plants was restricted to less than 100 m by entanglement with other S. australis plants within the stand. Some seed was retained on the senesced plants, but the germinability of this seed fell to less than 2% in the two month period following plant senescence (i.e. a decline of 79%). Once seed shed into the soil seed bank, anywhere from 32.3 to 80.7% of the viable seeds germinated in the year following seed production, with the rest remaining dormant or degrading. A model of the life cycle of S. australis based on the population ecology data indicated that the dormant seed bank had very little effect on annual seedling recruitment, but seed dispersal from neighbouring populations had a large impact on population growth rate. Therefore, the most successful weed control measures were those that restricted seed dispersal from neighbouring populations, or those that were applied to all populations in the region rather than to a single population. Weed control techniques applied to a single population, without reducing seed dispersal, could not reduce population size.
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Harrington, Robert P. "Forecasting corporate performance." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54515.
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For the past twenty years, the usefulness of accounting information has been emphasized. In 1966 the American Accounting Association in its State of Basic Accounting Theory asserted that usefulness is the primary purpose of external financial reports. In 1978 the State of Financial Accounting Concepts, No. 1 affirmed the usefulness criterion. "Financial reporting should provide information that is useful to present and potential investors and creditors and other users..."
Information is useful if it facilitates decision making. Moreover, all decisions are future-oriented; they are based on a prognosis of future events. The objective of this research, therefore, is to examine some factors that affect the decision maker's ability to use financial information to make good predictions and thereby good decisions.
There are two major purposes of the study. The first is to gain insight into the amount of increase in prediction accuracy that is expected to be achieved when a model replaces the human decision-maker in the selection of cues. The second major purpose is to examine the information overload phenomenon to provide research evidence to determine the point at which additional information may contaminate prediction accuracy.
The research methodology is based on the lens model developed by Eyon Brunswick in 1952. Multiple linear regression equations are used to capture the participants’ models, and correlation statistics are used to measure prediction accuracy.Ph. D.
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Graham, Tennille. "Economics of protecting road infrastructure from dryland salinity in Western Australia." University of Western Australia. School of Agricultural and Resource Economics, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0207.
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[Truncated abstract] The salinisation of agricultural land, urban infrastructure and natural habitat is a serious and increasing problem in southern Australia. Government funding has been allocated to the problem to attempt to reduce substantial costs associated with degradation of agricultural and non-agricultural assets. Nevertheless, Government funding has been small relative to the size of the problem and therefore expenditure needs to be carefully targeted to interventions that will achieve the greatest net benefits. For intervention to be justified, the level of salinity resulting from private landholder decisions must exceed the level that is optimal from the point of view of society as a whole, and the costs of government intervention must be less than the benefits gained by society. This study aims to identify situations when government intervention is justified to manage dryland salinity that threatens to affect road infrastructure (a public asset). A key gap in the environmental economics literature is research that considers dryland salinity as a pollution that has off-site impacts on public assets. This research developed two hydrological/economic models to achieve this objective. The first was a simple economic model representing external costs from dryland salinity. This model was used to identify those variables that have the biggest impact on the net-benefits possible from government intervention. The second model was a combined hydro/economic model that represents the external costs from dryland salinity on road infrastructure. The hydrological component of the model applied the method of metamodelling to simplify a complex, simulation model to equations that could be easily included in the economic model. The key variables that have the biggest impact on net-benefits of dryland salinity mitigation were the value of the off-site asset and the time lag before the onset of dryland salinity in the absence of intervention. ... In the case study of dryland salinity management in the Date Creek subcatchment of Western Australia, the economics of vegetation-based and engineering strategies were investigated for road infrastructure. In general, the engineering strategies were more economically beneficial than vegetation-based strategies. In the case-study catchment, the cost of dryland salinity affecting roads was low relative to the cost to agricultural land. Nevertheless, some additional change in land management to reduce impacts on roads (beyond the changes justified by agricultural land alone) was found to be optimal in some cases. Reinforcing the results from the simple model, a key factor influencing the economics of dryland salinity management was the urgency of the problem. If costs from dryland salinity were not expected to occur until 30 years or more, the optimal response in the short-term was to do nothing. Overall, the study highlights the need for governments to undertake comprehensive and case-specific analysis before committing resources to the management of dryland salinity affecting roads. There were many scenarios in the modelling analysis where the benefits of interventions would not be sufficient to justify action.
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Panidi, Ksenia. "Essays to the application of behavioral economic concepts to the analysis of health behavior." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209674.
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In this thesis I apply the concepts of Behavioral Economics to the analysis of the individual health care behavior. In the first chapter I provide a theoretical explanation of the link between loss aversion and health anxiety leading to infrequent preventive testing. In the second chapter I analyze this link empirically based on the general population questionnaire study. In the third chapter I theoretically explore the effects of motivational crowding-in and crowding-out induced by external or self-rewards for the self-control involving tasks such as weight loss or smoking cessation.Understanding psychological factors behind the reluctance to use preventive testing is a significant step towards a more efficient health care policy. Some people visit doctors very rarely because of a fear to receive negative results of medical inspection, others prefer to resort to medical services in order to prevent any diseases. Recent research in the field of Behavioral Economics suggests that human's preferences may be significantly influenced by the choice of a reference point. In the first chapter I study the link between loss aversion and the frequently observed tendency to avoid useful but negative information (the ostrich effect) in the context of preventive health care choices. I consider a model with reference-dependent utility that allows to characterize how people choose their health care strategy, namely, the frequency of preventive checkups. In this model an individual lives for two periods and faces a trade-off. She makes a choice between delaying testing until the second period with the risk of a more costly treatment in the future, or learning a possibly unpleasant diagnosis today, that implies an emotional loss but prevents an illness from further development. The model shows that high loss aversion decreases the frequency of preventive testing due to the fear of a bad diagnosis. Moreover, I show that under certain conditions increasing risk of illness discourages testing.
In the second chapter I provide empirical support for the model predictions. I use a questionnaire study of a representative sample of the Dutch population to measure variables such as loss aversion, testing frequency and subjective risk. I consider the undiagnosed non-symptomatic population and concentrate on medical tests for four illnesses that include hypertension, diabetes, chronic lung disease and cancer. To measure loss aversion I employ a sequence of lottery questions formulated in terms of gains and losses of life years with respect to the current subjective life expectancy. To relate this measure of loss aversion to the testing frequency I use a two-part modeling approach. This approach distinguishes between the likelihood of participation in testing and the frequency of tests for those who decided to participate. The main findings confirm that loss aversion, as measured by lottery choices in terms of life expectancy, is significantly and negatively associated with the decision to participate in preventive testing for hypertension, diabetes and lung disease. Higher loss aversion also leads to lower frequency of self-tests for cancer among women. The effect is more pronounced in magnitude for people with higher subjective risk of illness.
In the third chapter I explore the phenomena of crowding-out and crowding-in of motivation to exercise self-control. Various health care choices, such as keeping a diet, reducing sugar consumption (e.g. in case of diabetes) or abstaining from smoking, require costly self-control efforts. I study the long-run and short-run influence of external and self-rewards offered to stimulate self-control. In particular, I develop a theoretical model based on the combination of the dual-self approach to the analysis of the time-inconsistency problem with the principal-agent framework. I show that the psychological property of disappointment aversion (represented as loss aversion with respect to the expected outcome) helps to explain the differences in the effects of rewards when a person does not perfectly know her self-control costs. The model is based on two main assumptions. First, a person learns her abstention costs only if she exerts effort. Second, observing high abstention costs brings disutility due to disappointment (loss) aversion. The model shows that in the absence of external reward an individual will exercise self-control only when her confidence in successful abstention is high enough. However, observing high abstention costs will discourage the individual from exerting effort in the second period, i.e. will lead to the crowding-out of motivation. On the contrary, choosing zero effort in period 1 does not reveal the self-control costs. Hence, this preserves the person's self-confidence helping her to abstain in the second period. Such crowding-in of motivation is observed for the intermediate level of self-confidence. I compare this situation to the case when an external reward is offered in the first period. The model shows that given a sufficiently low self-confidence external reward may lead to abstention in both periods. At the same time, without it a person would not abstain in any period. However, for an intermediate self-confidence, external reward may lead to the crowding-out of motivation. For the same level of self-confidence, the absence of such reward may cause crowding-in. Overall, the model generates testable predictions and helps to explain contradictory empirical findings on the motivational effects of different types of rewards.
Doctorat en Sciences économiques et de gestion
info:eu-repo/semantics/nonPublished
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Michaud, Odile. "The establishment of economic thresholds for the green apple bug, Lygocoris communis (Knight), and tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), (Hemiptera: miridae) in apple orchards in Southwestern Quebec /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66179.
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Du, Plessis J. S. "Addressing diminishing profit margins within the Dutoit Group : a value chain analysis." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/97273.
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Thesis (MBA)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Rapid urbanisation, coupled with growing per capita incomes and a rapid rising middle class, is triggering rapid growth in urban food markets. Despite these opportunities, agriculture in South Africa is confronted with diminishing profit margins due to direct production cost increasing at rates above the revenue generated from agricultural products. This research assignment has aimed to define the attributes of an effective agricultural value chain in South Africa, given the challenges faced. To achieve this goal, the research focus was on the results of an in-depth analysis of the Dutoit Group’s deciduous fruit value chain. To be able to perform a value chain analysis it is of utmost importance to first understand the meaning of the concepts as well as their origin and the evolution of their application. This is achieved through a comprehensive study of literature. Three value chain analysis tools were used for the research. These tools were an industry analysis, value chain maps and benchmarking. Through the literature review the importance and relevance of these three tools were also explored and reasons provided why they can be regarded to be adequate for a proper in-depth analysis. An overview of the Dutoit Group’s history, focusing on the specific key events influencing the evolution of their value chains, is also discussed together with their business philosophy, business model and main accomplishments. This is done to provide context to the environment in which the value chain analysis process was performed. The main focus of the fourth chapter is the application of the three value chain analysis tools on the Dutoit Group’s deciduous fruit value chain, utilising primary and secondary data collected through interviews with specific value chain actors, observations, management information and literature obtained from the public domain. Through the application of the three value chain analysis tools the effectiveness of the Dutoit Group’s deciduous fruit value chain was evaluated, and strengths and weaknesses identified. The research results showed that the Dutoit Group’s internal deciduous fruit value chain has been effective in addressing the risk of diminishing profit margins. In addition the results showed that the key attributes of an effective value chain which are able to address the current challenges are defined as effective integration, strong relationships between value chain actors, high levels of productivity and strong leadership.
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Sounness, Marcus Neil. "Alternative grazing systems and pasture types for the South West of Western Australia : a bio-economic analysis." University of Western Australia. School of Agricultural and Resource Economics, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0054.
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Alternative grazing systems and pasture types for wool production in the south west of Western Australia were analysed using bio-economic modelling techniques in order to determine their relative productivity and profitability. After reviewing the experimental and modelling literature on perennial pastures and grazing systems, seven case studies of farmers were conducted in order to investigate the practical application of innovative grazing systems and use of perennial pastures. Together these case studies provided information for identifying relevant variables and for calibrating the modelling work which followed. The core of the work lies in a bio-economic model for investigating the comparative value of the three grazing systems and two pasture families mentioned above. A baseline scenario using currently available and reliable scientific data provides baseline results, after which a number of sensitivity analyses provide further insights using variations of four key parameters: persistence, heterogeneity, water soluble carbohydrates, and increased losses. Results show that perennial pastures are in the studied region more profitable than annual pastures. Under current baseline conditions, continuous grazing with perennial pastures is the most profitable enterprise, but this superiority is not robust under parameter variations defined by other scenarios. The more robust solution in terms of enterprise profitability is cell grazing with perennial pastures. The results indicate that intensive grazing systems such as cell grazing have the potential to substantially increase the profitability of grazing operations on perennial pasture. This result is an encouraging one in light of its implications for water uptake and salinity control. It means that economics and land care can go hand in hand, rather than be competitive. It is to be noted that it is the choice of the grazing system in combination with the pasture species, rather then the pasture species itself, that allows for such complementarity between economics and sustainable land use. This research shows that if farmers adopt practices such as cell grazing they may be able to increase the area that they can profitably plant to perennial pasture thus reducing the impacts of dryland salinity. This finding is consistent with the findings of the case studies where the farmers perceived that, provided grazing was planned, increasing the intensity of their grazing management and the perenniallity of their pastures would result in an increase in the profitability of their grazing operation. As a result this research helps to bridge a gap which has existed in this area of research, between the results of scientific research and those reported in practice.
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Yeung, Sze-ying, and 楊思瑩. "A case control study of the referral pattern and patient non-attendance in medical and surgical specialist outpatient clinics inHong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B39724293.
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Cruz, German Tadeo. "Getting there : a study to define and offer conceptual solutions for the control of sprawl, rural land preservation, neighborhood connectivity, and community image development in northwest Muncie." Virtual Press, 1999. http://liblink.bsu.edu/uhtbin/catkey/1136702.
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This study covers several areas of long held interest and urgent relevance: the development of lasting and meaningful community identity, the design of dynamic communities well aware of their current and future potential, the preservation of rural lands, and the control of unplanned growth.Working on two tracks, the study researches through focused interviews the conceptual image of the community held by representative members and then seeks to apply principles derived from the work of Randall Arendt, Robert Yaro and others to the articulation of land planning and site design measures that can be implemented in the Northwest sector of Muncie.Based on both the research and the derivation of principles, the study offers a large number of ideas supported with illustrations toward the improvement of the conditions and the creation of a long range strategy for land development and conservation.Department of Landscape Architecture
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Bragagnolo, Cassiano. "Análise do armazenamento de arroz no Brasil sob condições de incerteza através de um modelo dinâmico de expectativas racionais." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/11/11132/tde-21082006-163407/.
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O objetivo deste trabalho foi analisar o armazenamento do arroz no Brasil, propondo modelos para tomada de decisão quanto à formação de estoques. Uma vez conhecidos estes modelos é possível analisar previamente as intervenções pretendidas pelo governo. Para tanto se partiu da hipótese de que é possível representar o mercado de arroz no Brasil através de um modelo dinâmico de expectativas racionais capaz de captar o efeito da importação do produto e de algumas políticas de sustentação de preço ao produtor adotadas pelo governo brasileiro. A proposta metodológica para a estimação do modelo segue a abordagem de programação dinâmica. Foram desenvolvidos algoritmos que representam o mercado de arroz no Brasil em uma situação de mercado fechado sem intervenção do governo, mercado aberto sem intervenção do governo, mercado fechado com intervenção do governo via Prêmio de Escoamento do Produto - PEP, mercado fechado com intervenção do governo via Aquisição do Governo Federal - AGF mercado aberto com intervenção do governo via PEP, mercado aberto com intervenção do governo via AGF. Os métodos utilizados para solução exigem que sejam conhecidos as funções de demanda e oferta de área, o custo unitário de armazenamento, a taxa anual de juros, a distribuição de probabilidades das variáveis aleatórias (produtividade e choques de demanda) e os preços de importação e mínimos (quando for o caso). Os preços esperados de mercado na situação de mercado aberto com intervenção via PEP foram ligeiramente inferiores ao preço de mercado sem intervenção, porém o preço recebido pelo agricultor foi ligeiramente maior. Isto significa que parte dos recursos da PEP é apropriada pelo produtor e parte pela indústria. Os resultados do modelo aberto com AGF demonstram que os preços para o comprador ficam acima do encontrado para o modelo sem intervenção do governo. Outro resultado encontrado foi que o nível de preços mínimos praticado nos últimos anos não tem sido suficientemente elevado a ponto de promover mudanças significativas no equilíbrio de mercado interno.The aim of this study was to analyze rice storage in Brazil, proposing a model for decision taking regarding stock formation. Once these models are known it is possible to previously analyze the government interventions. Thus, the study was based on the hypothesis that it is possible to represent the rice market in Brazil through a dynamic model of rational expectations able to analyze the product importation effect and some policies of price support to the producer adopted by the Brazilian government. The methodological proposal for estimating the model follows the dynamic programming approach. It was developed algorithms which represent the rice market in Brazil in a situation of closed market without the government intervention, open market without government intervention, closed market with the government intervention through PEP (Prêmio de Escoamento do Produto Prize for Product Outletting), closed market with the government intervention through AGF (Aquisição do Governo Federal Federal Government Acquisition), open market with the government intervention through PEP, open market with government intervention through AGF. The methods used for the solution require that it be known the demand and supply functions for the area, the unit storage cost, the annual interest rate, the distribution of probabilities of random variables (productivity and demand shocks), importation and minimum (whenever is the case) prices. The expected market prices in the situation of open market with intervention through PEP were slightly lower than to the market price without intervention, however the price received by the grower was a little higher. It means that part of the PEP resources is allotted by the grower and part by the industry. The results of the open model with AGF show that the prices for the buyer are higher than those found in the model without government intervention. Another result was that the level of minimum prices practiced over the last years has not been adjusted to the point to promote significant changes in the balance of the domestic market.
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Lehrke, Linda. "Determining and Evaluating Cost-Effective Food Safety Risk Reduction Strategies at Retail Meat Facilities." Thesis, North Dakota State University, 2006. https://hdl.handle.net/10365/29906.
Full textAbstract:
In spite of the documented success of Pathogen Reduction and Hazard Analysis and Critical Control Points (PR/HACCP) at the processing level, farm-level and retail-level application is optional. Several factors impact the gap of food safety regulations from farm to fork. This thesis focuses on the retail level. At the retail level, pathogen survival and the associated ability to cause further disease to humans even after being subjected to certain processing and packaging conditions have varying implications on the probability of sickness or death. This issue also arises over the fact that, sometimes, appropriate handling and processing instructions are not properly followed by consumers. The primary goals of the project are to develop an optimal food safety intervention strategy that incorporates risk, cost, and the value of pathogen reduction with alternative control mechanism. We wish to evaluate incentives for PR/HACCP-like planning and adherence to best management practices that promote safe food production. These incentives will be evaluated for the retail level. In addition, we will develop optimal intervention strategies for ready-to-eat meats and poultry products that incorporate risk assessment, cost of intervention, and the value of risk reduction of alternative strategies for the farm-to-table continuum. The model adopted in this study is an expansion of the stochastic optimization model developed by Nganje, Kaitibie, and Sorin (2005) to include the optimal intervention strategy at the retail ( consumer) level. These components are simulated with firm-level microbial data at the processing and retail level using stochastic optimizer software. Stochastic dominance was also used to compare across the optimal strategies and determine if there is one clear choice that is preferred. This allowed us incorporate risk preferences of firms. The scenario method was used to determine what factors would likely affect the adoption of PR/HACCP at the retail level. Finally, this thesis provides firms and policymakers a direction for future options concerning risk mitigation strategies.
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Lambrechts, Derica. "The impact of organised crime on social control by the state : a study of Manenberg in Cape Town, South Africa." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80057.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: This study set out to research the influence of a local non-state actor on the role and authority of the state, in the domestic environment. Accordingly, the research problem focused on the impact of a domestic actor on the association between the state and the society. This study only focused on the state at the level of local government and the impact of one specific actor, organised criminal groups, on social control by the state. Thus, state-society relations were discussed in this context. In order to guide this study, the main and two supportive research questions were stated as follows: What is the impact of organised crime on the social control by the state? What are the power dynamics between local governance, criminal agents and society? Has the state become criminalised at the level of local government, as a result of the activities of organised crime, and if so, to what extent? The state thus functioned as the dependent variable and organised criminal groups as the independent variable. The theoretical foundation of this study was located in state-society relations, and specific reference was given to the work of Migdal (1988) and his analysis of state social control, pyramidal and weblike societies. Furthermore, a neo-pluralist view of the state was followed. A conceptualisation of the criminalisation of the state was provided, as the criminalisation of the state was regarded as one possible impact of organised crime on the state. In order to analyse the criminalisation of the state, a framework was constructed from four main avenues of empirical observation. In order to answer the research questions, a case study research design and a predominantly qualitative methodology was selected. As a case, the City of Cape Town was selected and Manenberg, located on the Cape Flats, as the site for the research. A case study research design created the opportunity to describe the context in detail and to connect the micro level of analysis to the macro level; thus, it provided insight on the research topic that enabled the researcher to expand/build theory. The field research process occurred over a period of three months using a triangulation of methods: Key informant interview, small group discussions and observation with three categories of respondents. These three categories included: Community members of Manenberg, organised criminal groups and agents of local government and local governance. In order to set the stage for the empirical analysis, a contextualisation of the dependent and independent variables were provided. It was stated that there is a lack of a universally agreed upon definition of organised crime, and as a result, a conceptualisation of organised crime was generated for this study. It was further argued that the majority of literature treats organised criminal groups and organised criminal gangs as two separate concepts, despite the fact that there are more similarities than differences. Thus, for the purpose of this study, a conclusion was reached that the difference is inconsequential. The development of organised crime in South Africa and an examination of the historical development of the gangs on the Cape Flats were described. With regards to the dependent variable, the context was provided for an analysis of local government in South Africa. The demographical and operational features of the municipal area of the City of Cape Town were explained, with specific reference to safety and security elements. The primary data collected was analysed according to the indicators of social control (compliance, participation and legitimacy), as identified by Migdal (1988). In addition, the framework to analyse the criminalisation of the state at the level of local government was applied on the case study. Based on the analysis, a different system, to what was described by Migdal (1988) in his narrative of a triangle of accommodation was found to be in operation in Manenberg on the Cape Flats. It was confirmed that there is the presence of a weakened state and accordingly, a weblike society, where social control is fragmented between local government and the criminal community. However, in this weblike society a system of local power dynamics exists between the criminal community, social community and local agents of governance, where dyadic collaboration occurs between all three the actors. However, despite the collaboration, the criminalisation of the state does not occur, but rather the statification of the organised criminal community, as it provides goods and service to the social community. The main findings can be summarised as: If a state lacks extensive social control and a rival authority has claimed a level of social control, this will not necessarily lead to the further weakening of the state, as a result of a system of power dynamics in place, where collaboration between the social community, the criminal community and local agents of governance occurs. This system is kept in place by: On-going efforts by the state to maintain (or regain) compliance, participation and legitimacy; corrupt agents of the state (specifically in the security sector); a level of operational ease that exists for the criminal community (and the interweaving of the criminal community in the social community) and a relatively strong society that acknowledges the benefits of criminal activities for the social community, but also recognises the authority and control of the state.
AFRIKAANSE OPSOMMING: Hierdie studie het ten doel om die uitwerking van 'n plaaslike nie-staatsrolspeler op die rol en gesag van die staat in die plaaslike omgewing te ondersoek. Vervolgens fokus die navorsingsvraag op die impak van 'n plaaslike rolspeler op die verhouding tussen die staat en die samelewing. Die studie fokus op die staat op plaaslike regeringsvlak en op die impak van een spesifieke rolspeler, georganiseerde misdaadgroepe. Staat-samelewing-verhoudinge is dus teen hierdie agtergrond bespreek. Om die studie te rig, is die hoof- en twee ondersteunende navorsingsvrae soos volg gestel: Wat is die impak van georganiseerde misdaad op die sosiale beheer van die staat? Wat is die magsdinamiek tussen die plaaslike regeringsvlak, kriminele agente en die samelewing? Is die staat gekriminaliseer op plaaslike regeringsvlak as gevolg van die resultate van georganiseerde misdaadbedrywighede en, indien wel, in hoe 'n mate? Die staat vorm dus die afhanklike veranderlike en georganiseerde misdaadgroepe die onafhanklike veranderlike. Die teoretiese begronding vir hierdie studie is gevind in staat-samelewing-verhoudinge en die werk van Migdal (1988), spesifiek sy analise van staat-sosiale beheer en piramiede- en webvormige samelewings, word genoem. Verder is 'n neo-pluralistiese beskouing van die staat ingeneem. 'n Konseptualisering van die kriminalisering van die staat word verskaf, aangesien dit voorsien is as een moontlike impak van georganiseerde misdaad op die staat. Ten einde die kriminalisering van die staat te ontleed, is 'n raamwerk opgebou uit vier hoofrigtings van empiriese observasie. 'n Gevallestudie is as navorsingsontwerp gebruik om die navorsingsvrae te beantwoord, met hoofsaaklik 'n kwalitatiewe metodologie. As 'n geval is die Stad Kaapstad gekies, met Manenberg op die Kaapse Vlakte as die terrein vir die navorsing. Die gevallestudie-navorsingsontwerp het die geleentheid geskep om die konteks in detail te beskryf en die mikrovlak-analise met die makrovlak-analise te verbind; derhalwe het dit insig verskaf wat die navorser in staat gestel het om teorie (uit) te bou. Die veldwerkproses het oor 'n tydperk van drie maande deur drie metodes plaasgevind: onderhoude met sleutelinformante, kleingroepbesprekings, en observasies met drie kategorieë respondente. Hierdie drie kategorieë is gemeenskapslede van Manenberg, georganiseerde misdaadgroepe, en agente van plaaslike regering en bestuur. Ten einde die empiriese navorsing op te stel, is 'n kontekstualisering van die afhanklike en onafhanklike veranderlikes verskaf. Dit is gestel dat daar 'n gebrek is aan 'n universeel-aanvaarde definisie van georganiseerde misdaad, en as gevolg hiervan is 'n konseptualisering vir hierdie studie gevorm. Daar is verder geargumenteer dat die meerderheid literatuur georganiseerde misdaadgroepe en georganiseerde misdaadbendes as twee aparte konsepte hanteer, ten spyte daarvan dat hierdie groeperinge veel meer ooreenstem as verskil. Vervolgens is die gevolgtrekking gemaak dat die verskil nie betekenisvol is nie. Die ontwikkeling van georganiseerde misdaad in Suid-Afrika en 'n ontleding van die historiese ontwikkeling van bendes op die Kaapse Vlakte is beskryf. Rakende die afhanklike veranderlike, is die konteks verskaf vir 'n analise van plaaslike regering in Suid-Afrika. Die demografiese en operasionele kenmerke van die munisipale area van die Stad Kaapstad is uiteengesit, met spesifieke verwysing na veiligheid- en sekuriteitselemente. Die primêre ingesamelde data is ontleed aan die hand van die indikatore van sosiale beheer (nakoming, deelname en legitimiteit) soos deur Migdal (1988) gedefinieer. Verder is die raamwerk om die kriminalisering van die staat op plaaslike regeringsvlak te ontleed, op die gevallestudie toegepas. Op grond van die analise is daar bevind dat 'n ander stelsel as wat Migdal (1988) in sy narratief van ‟n driehoek van akkommodasie beskryf het, in Manenberg op die Kaapse Vlakte voorkom. Dit is bevestig dat daar 'n verswakte staat voorkom en, vervolgens, 'n webvormige samelewing, waar sosiale beheer gefragmenteer is tussen die plaaslike regering en die kriminele gemeenskap. In hierdie webvormige samelewing bestaan egter 'n stelsel van plaaslike magsdinamiek tussen die kriminele gemeenskap, die sosiale gemeenskap en plaaslike regeringsagente, waar diadiese medewerking tussen al drie die akteurs voorkom. Ten spyte van hierdie samewerking, kom die kriminalisering van die staat egter nie voor nie, maar eerder 'n verstaatliking van die georganiseerde misdaadgemeenskap, aangesien dit goedere en dienste aan die sosiale gemeenskap verskaf. Die hoofbevindinge kan soos volg saamgevat word: As 'n staat nie uitgebreide sosiale beheer het nie en 'n mededingende gesag het 'n vlak van sosiale beheer opgeëis, sal dit nie noodwendig lei tot die verdere verswakking van die staat nie, as gevolg van 'n stelsel van magsdinamiek wat in plek is waar medewerking tussen die sosiale gemeenskap, die kriminele gemeenskap en plaaslike agente van bestuur voorkom. Hierdie stelsel word in plek gehou deur aaneenlopende pogings deur die staat om nakoming, deelname en legitimiteit te verkry (of terug te kry), korrupte staatsagente (spesifiek in die sekuriteitsektor), 'n vlak van operasionele gemak wat vir die kriminele gemeenskap bestaan (en die vervlegting van kriminele gemeenskap en die sosiale gemeenskap), en 'n relatiewe sterk samelewing wat die voordele van kriminele aktiwiteit vir die sosiale gemeenskap erken, maar so ook die gesag en beheer van die staat.
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Gumede, Halalisani. "The development of a putative microbial product for use in crop production." Thesis, Rhodes University, 2008. http://eprints.ru.ac.za/1352/.
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Xu, Li. "Financial and computational models in electricity markets." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51849.
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This dissertation is dedicated to study the design and utilization of financial contracts and pricing mechanisms for managing the demand/price risks in electricity markets and the price risks in carbon emission markets from different perspectives. We address the issues pertaining to the efficient computational algorithms for pricing complex financial options which include many structured energy financial contracts and the design of economic mechanisms for managing the risks associated with increasing penetration of renewable energy resources and with trading emission allowance permits in the restructured electric power industry. To address the computational challenges arising from pricing exotic energy derivatives designed for various hedging purposes in electricity markets, we develop a generic computational framework based on a fast transform method, which attains asymptotically optimal computational complexity and exponential convergence. For the purpose of absorbing the variability and uncertainties of renewable energy resources in a smart grid, we propose an incentive-based contract design for thermostatically controlled loads (TCLs) to encourage end users' participation as a source of DR. Finally, we propose a market-based approach to mitigate the emission permit price risks faced by generation companies in a cap-and-trade system. Through a stylized economic model, we illustrate that the trading of properly designed financial options on emission permits reduces permit price volatility and the total emission reduction cost.