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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Different extraction efficiencies observed from synthetic cannabinoid analysis due to burning and matrix effects

Mowatt, Heather Gray January 2013 (has links)
Cannabinoids are compounds that are naturally present in Cannabis sativa L., which interact with cannabinoid receptors in the nervous system, known as CB1 and CB2 receptors. The most abundant and well-known cannabinoid that can be isolated from cannabis is 9-tetrahydrocannabinol (THC). The structure of this compound specifically allows interaction with the CB1 and CB2 receptors, known as cannabimimetic activity. Other compounds have since been produced, inspired by THC, which have been designed to elicit similar pharmacological responses, and therefore are beneficial as analgesics. These compounds are known as synthetic cannabinoids. Synthetic cannabinoids, while potentially useful as therapeutic treatments for pain, are currently also popular as recreational drugs. Herbal products that contain synthetic cannabinoids are sold as “legal highs,” as few of these compounds are illegal according to the Controlled Drugs and Substances Act. These products are prepared by combining synthetic cannabinoids and plant material, and are smoked similar to marijuana. As the legality of many synthetic cannabinoids is quickly decreasing, as evidenced by the March 2011 emergency scheduling of five such compounds, it is becoming increasingly likely that these products will soon become popular exhibits to be submitted to controlled substances laboratories for testing. If a previously smoked product is submitted, there could potentially be effects due to the burning, the presence of the plant or paper substrate, and other synthetic cannabinoids that could directly diminish the facility of analysis. The aim of this thesis was to investigate these effects using four synthetic cannabinoids (AM-2201, JWH-015, HU-211, and RCS-4) and four substrates (tobacco, rolling paper, mint, and rosemary). Results demonstrated diminished peak areas, which are likely due to the introduction of these variables, which include burning the drug of abuse, and spiking the drug of abuse onto various matrices. The trend of lower peak areas further suggests that burning, the presence of plant material, and other cannabinoids potentially all compromise the facility of analyzing synthetic cannabinoid products. The act of burning one synthetic cannabinoid in particular, AM-2201, appeared to greatly decrease the capability to detect the analyte, as did the application of AM-2201 to various substrates. Furthermore, the ability to detect AM-2201 appeared to vary greatly between results obtained from analyzing samples applied to different substrates. Analysis of cannabinoid mixtures demonstrated that GC/MS analysis of different cannabinoids gave various peak areas although the concentrations remained consistent. Peak area ratios of cannabinoid mixtures that were extracted from substrates were found to not differ significantly between the specific substrates studied. This research supports that all of these variables should therefore be considered in regards to analysis of herbal products containing synthetic cannabinoids.
2

Layers of techniques, cost variability, obsolescence, and marginal input-output coefficients : a case study of the U.S. chemical industry

Azid, Toseef January 1993 (has links)
No description available.
3

Studies in asymptotic robustness

Savalei, Victoria Viktorovna. January 2007 (has links)
Thesis (Ph. D.)--UCLA, 2007. / Vita. Includes bibliographical references (leaves 93-96).
4

An evaluation of hospital efficiency in Nigeria : a stochastic frontier approach

Ikenwilo, Divine January 2001 (has links)
Includes bibliographical references. / Some people have argued that there is no reason to expect economic efficiency in a government enterprise because the funds allocated to various ends have to be exhausted to meet targets. In a social and welfarist sense, this argument seems valid if in essence, such earmarked targets, to improve societal welfare, are met. However, in the face of rising hospital costs and insufficient government funds, the issue of effectively allocating government funds to alternative uses becomes paramount. The setting for this research paper is Nigeria. This research work aims at investigating how well financial resources are used in government hospitals in Nigeria. It not only explores the resources employed in hospitals, but also how well these hospitals use minimum resources to achieve maximum outpatient and inpatient output. Hospital cost and expenditure data are collected from 40 government cottage and general hospitals in South East Nigeria (Anambra and Enugu states specifically). The data is collected by means of open-ended questionnaires, which are filled in by relevant administrators in the hospitals visited and also by ministry of health personnel at the state levels. The main research question asked is whether hospitals in this part of the country (and indeed Nigeria as a whole) are allocatively inefficient. A second question as to whether hospitals in Anambra State are more efficient than Enugu State is also posed. The major component of the research involves using the cost and expenditure data to build cost functions for the entire hospitals studied. The main thrust of analysis is the stochastic frontier process, which also incorporates an efficiency effects model. The choice of this model, above all else, is because it provides numerical efficiency estimates and thus provides quantifiable proof of how well poorly Nigerian hospitals fare. It is found in the analysis of the data collected that the hospitals studied are generally inefficient, as 70 percent of them operate at costs above the average permissible cost frontier.
5

Asymptotic properties of general transformation models. / CUHK electronic theses & dissertations collection

January 2005 (has links)
For discretization method, which provides an effective way to handle the problem, we focus on constructing a discretized version of continuous failure times. The major observation is that discrete failure times with finite values will attain their exact values although only ranks are given, as long as sample size is large enough. The score function can be asymptotically approximated by a sum of independent random variables. Consistency, asymptotic normality and efficiency of estimator can be obtained by using standard results for estimating equations, given some milder and more feasible conditions than those of martingale method. / In this thesis, some finite sample properties of marginal likelihood will be established. We prove under some regular conditions the score function of the marginal likelihood is a martingale, and prove the marginal likelihood satisfies some properties enjoyed by the standard likelihood method, although only use the relative ranks to make inference of the parameter instead of the full information. / In this thesis, the author studies some asymptotic properties of the marginal maximum likelihood estimate (marginal MLE) for general transformation models. The general transformation model is an important class of models for survival times and is nontrivially more general model than the linear transformation model (Gu, Sun and Zuo, 2005). By using marginal likelihood, we obtain estimator of regression parameter which does not depend on its baseline survival function, a property enjoyed by the Cox regression model. The major obstacle for the general transformation models is the resulting estimation function is complicated and usually has no closed analytic expression. Gu etc. (2005) proposed Markov chain Monte Carlo (MCMC) stochastic approximation algorithm to solve the marginal MLE. / Moreover, a discussion is given for the question of asymptotic properties for the proposed marginal MLE based on two different methods: martingale method and discretization method. For martingale method, emphasis is given to the role of martingale limit theory and results presented are primarily theoretical. / We also demonstrate some important transformation models do satisfy our conditions and thus show their consistency, asymptotic normality and efficiency for the first time. / Huang Bin. / "Dec 2005." / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6484. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 63-69). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
6

Maximum likelihood estimation of phylogenetic tree with evolutionary parameters

Wang, Qiang, January 2004 (has links)
Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xi, 167 p.; also includes graphics Includes bibliographical references (p. 157-167). Available online via OhioLINK's ETD Center
7

A multi-scale study of the star formation law in nearby galaxies

Isaacs, Narusha January 2020 (has links)
>Magister Scientiae - MSc / This research aimed to evaluate the effects of changing length-scales on the star formation laws and star formation efficiencies for our selected sample of galaxies. We have combined high-resolution Hi data from The Hi Nearby Galaxy Survey, CO data from HERA CO–Line Extragalactic Survey and the Nobeyama CO Atlas of Nearby Spiral Galaxies and 12 𝜇m data from the Wide-field Infrared Survey Explorer of a sample of five nearby galaxies to study the relationship between star formation rate surface density, ΣSFR, and gas surface density, Σgas, at various length-scales. In order to probe the star formation law of each galaxy, all image sets were placed on common astrometric grids and evaluated on a pixel-by-pixel basis over a range of sub-kpc length-scales. We investigated whether the star formation law changes with length-scales and found that as resolution becomes coarser, the Kennicutt Schmidt power-law index decreases for the correlation between ΣSFR and ΣH2 . Our results show that the index values are close to unity but are not consistent with it.
8

The impact of farm input subsidies on economic efficiency of maize production in Malawi

Chiromo, John 31 August 2018 (has links)
The study analyzed the impact of the farm input subsidy programme (FISP) on the technical, allocative and economic efficiency and determining factors associated with these efficiencies of 12, 271 smallholder maize farmers from 2010 IHS3 dataset in Malawi. Descriptive statistics, stochastic frontier approach as and a Cobb-Douglas production function were applied. Yield responsiveness to production inputs was estimated by computing input elasticities. The findings indicate that technical efficiency of smallholder maize farmers ranged from 15.7 to 78.9 with a mean of 61.3 percent reflecting a substantial level of inefficiency. The allocative efficiency scores were between 23.5 and 86.2 with a mean of 66.9 percent reflecting a substantial level of allocative inefficiency. The economic efficiency scores were between 14.1 and 74.6 with amean of 59.2 percent reflecting a substantial economical inefficiency. An estimated return to scale was 0.87 indicating that during the period under review, smallholder maize farming decreased by about 13 percent. The results of second stage Tobit regression estimations indicates that the FISP programme improved the efficiencies of maize farmers in Malawi. In addition, t farmers’ age, farming experience, education years, having an income generating activity and receiving remittance were also identified as significant drivers of production capacity of smallholder farmers maize. However, farmers’ marital status, family size and distance to the market had a negative impact on smallholder farmers’ capacity in maize production. Smallholder farmers in Malawi were experiencing a decreased return to scale meaning that they were technical, allocative and economically inefficient in maize production. From the findings, among other issues to be considered for the improvement of technical, allocative and economic efficiencies of maize production among smallholders farmers, the government should support only energetic farmers, make farm inputs available and accessible to farmers, continued advocacy on v adoption of family planning to reduce population growth to carter for scarcity of resources, increase and enhance extension services to help in educating these smallholder farmers in handling new technologies associated with modern agriculture, encourage them to engage in IGAs to complement FISP in purchasing farm inputs, increased and extended cash transfer program to economically empower these smallholder farmers.
9

Essays on the cost effects of airline mergers and alliances

Le, Huubinh B. January 1900 (has links)
Doctor of Philosophy / Department of Economics / Philip G. Gayle / My dissertation is comprised of two essays in the field of industrial organization with an emphasis on the airline industry. In particular, I investigate how airline mergers and alliances affect the components of total cost. By using a methodology that does not require the researcher to have cost data, I am able to infer marginal costs, fixed costs and sunk costs changes associated with mergers and alliances. My first essay examines two recent airline mergers—Delta/Northwest and United/Continental. Most post-merger analysis in airlines disproportionately focuses on assessing price rather than cost changes. Perhaps one reason is that reliable price data are more readily available. Despite the difficulty of obtaining cost data, researchers have sought to empirically assess whether cost efficiency gains associated with a merger outweigh the increased market power of the merged firm. The results from my analysis suggest that both mergers are associated with marginal and fixed costs savings, but higher market entry costs. The magnitude of the cost effects differed across the mergers. Moreover, I find that the market power effects of these mergers were negligible. My second essay investigates the cost effects of the codesharing alliance between Delta, Northwest and Continental Airlines. Codesharing is one of the most popular forms of airline cooperation that allows an airline to market and sell seats on its partners’ flights as though it owns those flights. Studies have found that airline alliances have very little to no effect on total cost. Rather than analyzing cost as a whole, I study whether a disaggregate analysis on cost is more appropriate. I find evidence that forming an alliance helps generate more passenger traffic for the alliance partners thereby reducing the partner carriers' marginal cost. Even though the literature has found that the total cost effects to be small, an alliance can have a considerable impact on some components of cost.
10

Koncentracijų vertinimo skirtumai pagal ES, Lietuvos ir JAV konkurencijos teisę / Concentrations Assessment Differences under the EU, Lithuanian and the US Competition Law

Leonavičiūtė, Eglė 24 January 2011 (has links)
Koncentracijų vertinimui ES, Lietuvoje ir JAV pasitelkiamos skirtingos koncentracijų vertinimo – „žymaus veiksmingos konkurencijos apribojimo“, „dominavimo“ ir „reikšmingo konkurencijos sumažinimo“ – taisyklės. Lietuvoje taikoma „dominavimo“ taisyklė neapima konkurencijos teisės draudimų taikymo oligopolinėse rinkose sukuriamam, vienašaliam neigiamam poveikiui rinkoje, kuris nelemia dominuojančios padėties sukūrimo ar sustiprinimo. Taip pat šios taisyklės pagrindu nepakankamas dėmesys skiriamas koncentracijų sukuriamo efektyvumo vertinimui. Nors ES ir JAV taikomų koncentracijų vertinimo taisyklių turinys yra tapatus – praktinis taisyklių taikymas nagrinėjamose jurisdikcijose yra skirtingas. Atliktas koncentracijų kontrolės tikslų, koncentracijos sąvokos, koncentracijos sudarymo būdų, ūkio subjekto sąvokos tyrimas, koncentracijų sukuriamų neigiamų bei teigiamų padarinių lyginamasis vertinimas parodė, kad pastarieji nagrinėjamos jurisdikcijose suprantami tapačiai. Buvo nustatyta, kad esminiai skirtumai pasireiškia koncentracijų kontrolės institucijoms nustatinėjant priežastinį ryšį tarp veikos (vykdomos koncentracijos) bei jos sukuriamų padarinių rinkoje. Vertinant horizontalias koncentracijas ir ES, ir JAV atsižvelgiama į tuos pačius, žymų, reikšmingą konkurencijos apribojimą lemiančius veiksnius, tačiau ES didesnis dėmesys skiriamas struktūrinių pasikeitimų rinkoje vertinimui, JAV – konkurencinių ryšių tarp koncentraciją vykdančių subjektų pasikeitimui. Nehorizontalių... [toliau žr. visą tekstą] / Concentrations in the EU, Lithuania and the US are assessed under different – “significant impediment of competition”, “dominance” and “substantial lessening of competition” – rules. Lithuanian “dominance” rule is not applicable to merger’s created unilateral effect in oligopolistic market if such merger doesn’t create or strengthen its dominant position. Furthermore, less attention is paid for efficiencies, created by mergers under this rule. While the content of the EU and the US concentrations assessment rules might seem alike – practical assessment of mergers proves the opposite. Moreover, comparative analysis of merger control goals, concepts of concentration and undertaking, ways of concentration and positive, negative effects of concentration showed that these are interpreted in the same way in all jurisdictions. It was also noticed that the main differences occur while identifying causality between concentration and its effects in the market. The same attention is paid to certain factors that might lessen competition substantialy during the horizontal mergers assessment process in the EU and the US. However, analysis applied in the EU are more of structural nature and the US concentration’s control institutions put focus on the assessment of competitive relationships between merged undertaking before and after the merger. The US is also more cautious about assessment of non-horizontal mergers. Competition authorities practically presume efficiencies created by the... [to full text]

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