Dissertations / Theses on the topic 'Average treatment effect on the treated'

This thesis studies inference to the complier treatment effect denoted LATE. The standard approach is to base the inference on the two-stage least squares (2SLS) estimator and asymptotic Neyman inference, i.e., the t-test. The paper suggests a Fisher Randomization Test based on the t-test statistic as an alternative to the Neyman inference. Based on the setup with a randomized experiment with noncompliance, for which one can identify the LATE, I compare the two approaches in a Monte Carlo (MC) simulations. The results from the MC simulation is that the Fisher randomization test is not a valid alternative to the Neyman’s test as it has too low power.

Thesis (MSc (Radiography))--Cape Peninsula University of Technology, 2019
Introduction: Intracranial aneurysm coil embolization is a fluoroscopically guided interventional procedure that is often preferred over surgical clipping for the treatment of intracranial aneurysms. Fluoroscopically guided procedures are associated with high levels of radiation doses which have the potential to induce skin injuries; and this necessitates adherence to radiation protection measures, especially the optimization of radiation exposure during fluoroscopically guided procedures. Optimization of radiation exposure can be achieved by applying the as low as reasonably achievable (ALARA) principle and by implementing diagnostic reference levels (DRLs). Monitoring and documentation of radiation doses at the end of each procedure is also essential to identify patients that are at risk of developing radiation-induced injuries for possible follow-up. Aim: This research study aimed to determine the average radiation dose to patients' thyroid glands and skin during intracranial aneurysm coil embolization. The objectives were to establish preliminary DRLs for intracranial aneurysm coil embolization; to ascertain whether the anatomical location of the intracranial aneurysm had an effect on the radiation dose and to compare the measured thyroid gland and skin doses to the Monte Carlo calculated doses. Methods: A prospective quantitative research study was conducted on 34 participants who had intracranial aneurysms that required coil embolization during the study period. Radiation doses to the anterior neck of participants, over the thyroid gland region, were measured using lithium fluoride thermoluminescent dosimeters (TLDs). In addition, the air-kerma area product (KAP) values were used to determine the participants' skin dose and the DRLs. Considering that it is not possible to perform direct thyroid measurements on human beings, phantom-based simulation studies were performed to evaluate the difference between the dose measured on the anterior neck and the dose measured directly on the thyroid gland. Three different aneurysm coil embolization scenarios were simulated during the phantom-based simulation studies. TLDs were placed on the anterior neck and in the thyroid hole of the phantom, which represents the anatomical location of the thyroid gland, during each simulation. The thyroid and skin doses were also calculated using a Monte Carlo program. The measured thyroid gland and skin doses were compared to the doses obtained from Monte Carlo calculations. Results: The average percentage difference between the anterior neck doses and thyroid radiation doses was found to be 61%. This value was added to the radiation dose measured on the anterior neck of participants to obtain the thyroid absorbed doses during coil embolization procedures. The thyroid absorbed doses ranged between 3.2 and 20.95 mGy with a mean of 11.25 mGy. The KAP values ranged between 33 and 125 Gy.cm2. The DRL established during this study was 68 Gy.cm2, 616 image frames and 30 minutes of fluoroscopy time. There was no agreement between measured thyroid dose and calculated thyroid doses while there was strong positive correlation between measured and calculated skin doses. The results showed no statistically significant relationship between aneurysm location and the radiation dose. Conclusion: The skin doses in this research study were below the threshold doses suggested in the literature for deterministic effects of radiation. The study results therefore suggest that patients that undergo intracranial aneurysm coil embolization at the research site are not at risk of developing radiation-induced skin injuries. The established DRLs were also lower than internationally published DRLs for intracranial aneurysm coil embolization.

The study was aimed to investigate the effect of corn stalk pre-treatment duration on biogas production when cow dung and corn stalk was co-digested in an anaerobic digestion. Corn stalks were pre-treated in different durations: 2-days, 5-days, and 8-days before being added to cow dung into anaerobic co-digesters. The experiments were set up randomly by using triplicate batch anaerobic apparatus in 21 L containers that run in 60-days. The mixing ratio between a corn stalk and cow dung was 50%: 50% (based on the volatile solid value of each material), but corn stalk was cut into small pieces with around 10 cm length, while the cow dung was air dried. The results of the study indicated that all operation parameters such as temperature, pH, and alkalinity in the anaerobic batch were suitable for biogas production. The results showed that there was a significant improvement in total gas produced in the pre-treated 5-days treatment (206.4±8.4 L) compared to 2-days (153.4±9.6 L), and 8-days ones (174±11.1 L). The biogas yield of the pretreated 2-days, 5-days, and 8-days treatments were 392.7±9.8 L/kg VSfermented, 469.8±10.1 L/kg VSfermented and 497.1±13.3 L/kg VSfermented, respectively, that was not significantly different (5%). In all treatments, low concentration of methane in the beginning phase had been observed but increased and reached the optimum value for energy use after 10 days. The result of the study showed that it is preferable to have 5-days pre-treatment of corn stalk before the corn stalk is loaded to an anaerobic digester in combination with cow dung.
Nghiên cứu này nhằm đánh giá ảnh hưởng của thời gian xử lý thân cây bắp lên năng suất sinh khí khi ủ phối trộn phân bò và thân cây bắp trong điều kiện yếm khí. Ba mức thời gian xử lý thân cây bắp được chọn là 2 ngày, 5 ngày, và 8 ngày. Các thí nghiệm được bố trí ngẫu nhiên trong các bình ủ yếm khí theo mẻ 21 L, vận hành trong 60 ngày liên tiếp và có 3 lần lặp lại. Nguyên liệu ủ được phối trộn theo tỷ lệ 50% phân bò và 50% thân bắp, trong đó thân bắp được cắt nhỏ cỡ 10 cm. Kết quả thí nghiệm cho thấy tất cả các thông số pH, nhiệt độ, độ kiềm của mẻ ủ đều phù hợp để vận hành. Lượng khí sinh ra của các nghiệm thức xử lý ở 2 ngày, 5 ngày, 8 ngày được ghi nhận là 153,4±9,6 L, 206,4±8,4 L và 174±11,1 L; năng suất sinh khí của các nghiệm thức không khác biệt và đạt giá trị 392,7±9,8 L/kg VSphânhủy, 469,8±10,1 L/kg VSphânhủy và 497,1±13,3 L/kg VSphânhủy. Tất cả các nghiệm thức đều sản sinh lượng CH4 thấp ở giai đoạn đầu nhưng tăng dần theo thời gian ủ và đạt hiệu quả sử dụng sau 10 ngày ủ. Kết quả cho thấy có thể chọn mốc thời gian 5 ngày để xử lý thân cây bắp trước khi đưa vào hầm ủ biogas.

In this thesis we develop methods for dealing with missing data in a univariate response variable when estimating regression parameters. Missing outcome data is a problem in a number of applications, one of which is follow-up studies. In follow-up studies data is collected at two (or more) occasions, and it is common that only some of the initial participants return at the second occasion. This is the case in Paper II, where we investigate predictors of decline in self reported health in older populations in Sweden, the Netherlands and Italy. In that study, around 50% of the study participants drop out. It is common that researchers rely on the assumption that the missingness is independent of the outcome given some observed covariates. This assumption is called data missing at random (MAR) or ignorable missingness mechanism. However, MAR cannot be tested from the data, and if it does not hold, the estimators based on this assumption are biased. In the study of Paper II, we suspect that some of the individuals drop out due to bad health. If this is the case the data is not MAR. One alternative to MAR, which we pursue, is to incorporate the uncertainty due to missing data into interval estimates instead of point estimates and uncertainty intervals instead of confidence intervals. An uncertainty interval is the analog of a confidence interval but wider due to a relaxation of assumptions on the missing data. These intervals can be used to visualize the consequences deviations from MAR have on the conclusions of the study. That is, they can be used to perform a sensitivity analysis of MAR. The thesis covers different types of linear regression. In Paper I and III we have a continuous outcome, in Paper II a binary outcome, and in Paper IV we allow for mixed effects with a continuous outcome. In Paper III we estimate the effect of a treatment, which can be seen as an example of missing outcome data.

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In this paper, we analyze the impact of hosting the Summer Olympics on macroeconomic aggregates such as GDP, consumption, government consumption and investments per capita. The data is in panel structure and includes the period of ten years before and ten years after the event containing the Olympic Summer Games between 1960 and 1996. The sample countries comprise only candidates to host the games. This sampling strategy allows us to estimate the average treatment effect consistently, because it is assumed that these countries are comparable to each other, including those that ultimately hosted the games. The impact of hosting the Olympic games is measured by Fixed Effect and First Difference regressions. Moreover, we do a structural break test developed by Andrews (1993) to identify if hosting the Olympic Games creates anticipation effects for demand changes that stimulate current GDP, consumption, government consumption and investments. The results indicate a positive effect of the Summer Olympics in all variables of interest. However, the distribution in time and anticipation of these effects is unclear in the tests, changing significantly depending on the model and the significance level used.
Neste artigo e analisado o impacto de sediar as Olimp adas de Ver~ao em agregados macroecon^omicos como PIB, consumo, gastos do governo e investimentos per capitas. Os dados utilizados est~ao em painel e cont^em o per odo entre dez anos antes e dez anos depois do evento contendo os Jogos Ol mpicos de Ver~ao entre 1960 e 1996. Os pa ses da amostra s~ao apenas os candidatos a sediar os jogos, essa estrat egia amostral permite estimar os efeitos m edios de tratamento de forma consistente, pois assume-se que esses pa ses s~ao compar aveis entre si. Para avaliar o impacto dos jogos e lan cado m~ao de t ecnicas em painel como o Efeito Fixo e a Primeira Diferen ca e, al em disso, faz-se um teste de quebra estrutural desenvolvido por Andrews (1993) entre os pa ses sede. Os resultados indicam um efeito positivo e robusto dos Jogos Ol mpicos de Ver~ao em todas as vari aveis de interesse. No entanto, a distribui c~ao no tempo e antecipa c~ao desses efeitos e amb gua nos testes mudando de forma signi cativa dependendo do modelo e n vel de signi c^ancia utilizados.

O objetivo deste trabalho é analisar como o nível de recursos escolares e a sua distribuição entre os estudantes afetam o desempenho acadêmico dos alunos brasileiros da rede pública de ensino. Para atingir tal objetivo, utilizou-se duas óticas de análise: uma análise descritiva e uma análise econométrica, ambas com base em dados do Censo Escolar e da Prova Brasil de 2013. Sob a ótica descritiva, parte-se da constatação de que as escolas públicas de Ensino Fundamental apresentam desigualdades nos patamares de recursos escolares conforme a região em que a escola se localiza. Em especial, as crianças de regiões mais empobrecidas tendem a enfrentar restrições de oferta de escolas públicas com maiores dotações de equipamentos pedagógicos, de instalações e de qualificação docente. A fim de avaliar apropriadamente a relação entre os recursos escolares e os resultados acadêmicos dos alunos no contexto brasileiro, tal distribuição não aleatória de recursos escolares entre os alunos foi considerada na análise econométrica. Nesta ótica de análise, por sua vez, foi estimado um modelo de correção em dois estágios que identificou os efeitos dos recursos escolares nas notas de Português e de Matemática dos alunos de 5º ano/4ª série do Ensino Fundamental das escolas públicas brasileiras, considerando a restrição de oferta de escolas com maior nível de recursos por meio do emprego de variável instrumental. Os resultados encontrados apontaram para a existência do efeito positivo que escolas mais bem equipadas em termos de recursos escolares têm sobre o desempenho escolar dos alunos, sendo esse efeito maior para as notas de Matemática e para a subpopulação de alunos oriundos de municípios com maior restrição de oferta de escola de alto nível de recursos.
The aim of this study is to analyze how the level of school resources and its distribution among the students affect the academic performance of Brazilian students from public schools. To achieve this goal, we used two analytical forms: a descriptive and an econometric analysis, both based in the Brazilian School Census and Prova Brasil data of 2013. Under the descriptive point of view, it is observed that public schools of Ensino Fundamental have inequalities in school resource levels depending on the region where the school is located. In particular, children from the poorest regions tend to face supply constraints of public schools with larger endowments of teaching equipment, facilities and teaching qualification. In order to properly evaluate the relationship between school resources and academic achievement of students in the Brazilian context, such non-random distribution of school resources among students was considered in the econometric analysis. In this analytical form, in its turn, a two-step correction model was estimated which identified the effects of school resources in the results of test scores in Portuguese and Math of 5th year/4th grade students of Ensino Fundamental education in Brazilian public schools, accounting for the supply restriction of schools with high level of resources using an instrumental variable. The findings pointed to the existence of the positive effect that the best equipped schools in terms of school resources have on school performance of students. This effect is particularly greater in Math scores and for the subpopulation of students from municipalities with the highest supply restriction of high quality schools.

This paper is dedicated to the empirical analysis of the pilot trainee project Stáže ve firmách, which is considered as treatment in this analysis. The main objective of the empirical analysis is estimation of average treatment effect(ATE) and average treatment effect on treated(ATET) for characteristics like socioeconomic status and wage. Counterfactual methods for policy impact evaluation like Difference in Differences Estimator(DiD), First Differences Estimator(FD) and Propensity Score Matching(PSM) are used to estimation mentioned effects. This paper contains extension of Assignment Problem that is used for people matching purposes as alternative for PSM. This way of matching provides better control over creation of couples. Resulting pairs are more similar in selected characteristics due to better control during couples creation process.

Mestrado em Economia
Esta dissertação estuda os principais efeitos do sistema de crédito garantido (PME Investe) adotado em Portugal para as micro, pequenas e médias empresas (PMEs). O presente estudo baseia-se em três bases de dados, com informação individual para todas as empresas e bancos em Portugal, avaliado o impacto do programa sobre o mercado de crédito e a performance económica das empresas participantes. Ao combinar uma abordagem de "matching" com o estimador diferença em diferenças, os resultados demonstram que o programa ajudou as empresas participantes a melhorar o acesso ao mercado de crédito, a aumentar o volume agregado de crédito disponível, a proporção de crédito de longo prazo e a reduzir as despesas com juros. Adicionalmente, existe também evidência estatística de efeitos económicos de segunda ordem, como a criação de emprego e aumento do volume de exportações. O sistema adotado teve também efeitos positivos sobre o sistema bancário em Portugal ao reduzir a sua exposição ao risco, permitindo a melhoria dos seus rácios de capital definidos pelo Acordo de Basileia. No entanto, os resultados demonstram que ainda existe espaço para a melhoria das características intrínsecas ao sistema de crédito garantido em Portugal, em particular para as linhas de crédito direcionadas às empresas exportadoras ou de média dimensão.
This dissertation examines the main effects of the credit guarantee scheme (CGS) for Portuguese micro-, small- and medium-sized enterprises (SMEs) initially adopted in 2009. The study relies on three large-scale data sources, with individual information for all Portuguese non-financial corporations and banks, to assess the impact over credit additionality and the ex-post performance of participating firms. By applying a difference-in-difference matching approach, the results have shown that the program helped participants to improve their access to the credit market, increasing the overall amount of loans granted, the proportion of long-term debt and reducing their interest expenses and the probability of default. Moreover, there is also statistical evidence of economic spillovers, such as employment growth and exports volume. The scheme also helped the Portuguese banking system to reduce their risk exposures, improving their capital ratios under the Basel Accord. Nevertheless, the results show that there is room for improvement in the scheme design and features, in particular for credit lines targeting medium-sized or exporters firms.
info:eu-repo/semantics/publishedVersion

Le pemphigus est une maladie auto-immune spécifique de la peau et des muqueuses provoqué par des auto-anticorps (Ac) spécifiques des desmogléines (Dsg) 1 ou 3. Ces Ac pathogéniques inhibent l'adhésion cellulaire des kératinocytes. Le pemphigus se déclenche par la conjonction d’événements rares impliquant l’émergence puis la coopération de lymphocytes B (LB) et de lymphocytes LT auto-réactifs dans un contexte génétique et environnemental particulier. Jusqu’à présent, la première ligne de traitement du pemphigus était constituée de fortes doses de corticoïdes, qui sont de puissants immunosupresseurs systèmiques. Le Rituximab (RTX), un Ac monoclonal chimérique anti-CD20, constitue une thérapeutique innovante aboutissant à l’élimination des LB. L’étude clinique RITUX 3 a été conçue pour évaluer l’efficacité et l’innocuité du traitement utilisant le RTX associé à une courte corticothérapie dans le traitement de première intention du pemphigus par rapport au traitement de référence par la corticothérapie standard (CS). Dans un premier temps, notre analyse clinico-biologique des patients après 24 mois a démontré que l’utilisation du RTX associé à de la prednisone à court terme en traitement de première intention chez les patients atteints de pemphigus foliacé et vulgaire modéré à sévère est à la fois plus efficace et mieux toléré que le traitement de référence par la prednisone seule (89% de patients versus 34%). Cette efficacité a été confortée à plus long terme après la reconstitution du répertoire lymphocytaire B avec un risque de rechute de 2% à 36 mois. La présence d’une forme sévère de pemphigus au diagnostic (PDAI ≥ 45) et d’un taux d’Ac anti-Dsg à 3 mois supérieur aux valeurs seuils (anti-Dsg1 ≥ 20 ou anti-Dsg3 ≥ 120) sont associés à un risque de rechute précoce de 50%. Ces deux facteurs prédictifs permettent d'identifier un sous-groupe de patients présentant un risque élevé de rechute nécessitant une perfusion d'entretien de RTX au 6ème mois. Dans un deuxième temps, nous avons étudié l’impact des traitements par RTX et par CS chez les patients atteints de pemphigus afin de mieux appréhender la réponse auto-immune. La caractérisation phénotypique des LB auto-réactifs et l’analyse de la fréquence des LB capables de sécréter des immunoglobulines (Ig)G anti-Dsg par une approche ELISPOT a permis d’établir que l’efficacité du traitement par RTX dans le pemphigus semble liée à l’élimination des LB mémoires CD27+IgG+ spécifiques des Dsg. Des LB auto-réactifs Dsg restent détectables après RTX suite à la reconstitution lymphocytaire B, mais ces LB ont un phénotype naïf et non commuté (IgM) et ne secrètent plus d’IgG. En revanche, la persistance des LB auto-réactifs capables de sécréter des IgG anti-Dsg après traitement par CS est certainement à l’origine des rechutes fréquentes. L’analyse de l’expression génique ciblée à l’échelle unicellulaire a démontré qu’initialement, les LB spécifiques des Dsg ont un profil pro-inflammatoire avec l’expression de trois gènes codant pour les interleukines (IL)-1β, IL-12p35 et IL-23p19 et pour le gène de l’IRF5 (Interferon regulatory factor 5) par rapport aux LB non auto-réactifs. Le RTX et la CS ont des effets différents sur l'expression de ces gènes mais les deux réduisent l’expression génique d’IL-1β qui semble jouer un rôle important dans la physiopathologie du pemphigus. Parallèlement, l’analyse transcriptomique puis protéique des LB isolés des patients en rémission complète ou incomplète 6 ans après l’étude RITUX 1 a mis en évidence une augmentation d'expression de KCNN4 (Potassium calcium-activated channel subfamily N member 4) à la surface des LB chez les patients atteints de pemphigus en rémission complète pouvant influencer la maturation des LB
Pemphigus is an autoimmune disease of the skin and mucous membranes caused by autoantibodies (Ab) specific to desmoglein (Dsg) 1 or 3. These pathogenic Ab inhibit cell adhesion of keratinocytes. The development of pemphigus is associated with the conjunction of many uncommon events involving the emergence and then the cooperation of auto-reactive B cells and T cells link to genetic and environmental factors. Until now, the first line of treatment consisted of high doses of corticosteroids. Rituximab (RTX), an anti-CD20 chimeric monoclonal antibody, is an innovative therapy that results in B cells depletion. The RITUX 3 clinical trial was designed to evaluate the efficacy and safety of RTX combined with a short-course glucocorticoid therapy as a first-line treatment of pemphigus versus the standard treatment with standard corticosteroids (CS). As a first step, our clinico-biological analysis of patients after 24 months has shown that the use of RTX combined with short-term prednisone as a first-line treatment in patients with moderate to severe pemphigus is both more effective and better tolerated than the reference treatment with prednisone alone. Respectively, 89% of patients versus 34% in each group and both pemphigus foliaceus and pemphigus vulgaris patients responded. This efficacy was confirmed in the longer term after reconstitution of the B lymphocyte repertoire with a risk of relapse of only 2% at 36 months. The presence of a severe form of pemphigus at diagnosis (PDAI ≥ 45) and an anti-Dsg Ab level at 3 months above threshold values (anti-DSG1 ≥ 20 or anti-DSG3 ≥ 120) are associated with 50% risk of early relapse. These two predictive factors make it possible to identify a subgroup of patients at high risk of relapse requiring a maintenance infusion of RTX at the 6th month. In a second step, we studied the impact of RTX and CS treatments in patients with pemphigus in order to better understand the autoimmune response. The phenotypic characterization of auto-reactive B cells and the analysis of the frequency of B cells able of secreting anti-Dsg immunoglobulin (Ig) G by an ELISPOT approach demonstrated that the efficacy of RTX treatment in pemphigus seems related to the elimination of IgG-switched Dsg memory B-cells. Dsg specific B cells remain detectable after RTX when B cells return, but these B cells have a naïve and non-switched (IgM) phenotype and no longer secrete IgG. On the other hand, the persistence of self-reactive Dsg B cells capable of secreting IgG anti-Dsg after treatment with CS is certainly at the origin of the frequency of relapses. The unicellular targeted gene expression analysis demonstrated that initially, Dsg-specific B cells have a pro-inflammatory profile with the overexpression of three genes encoding Interleukin (IL) -1β, IL-12p35 and IL-23p19 and for the IRF5 gene (Interferon regulatory factor 5) compared to non-self-reactive B cells. RTX and CS have different effects on the expression of these genes, but both reduce the gene expression of IL-1β, which seems to play an important role in the pathophysiology of pemphigus

Malgré les nombreuses études menées et les recommandations consensuelles au niveau international, la prescription des inhibiteurs de la neuraminidase (INA) en cas de syndrome grippal reste controversée. Cette thèse avait pour objectif de mieux comprendre la place qui devrait leur être réservée dans le traitement de la grippe saisonnière et pandémique. Afin de répondre à cette question, plusieurs travaux ont été menés et ont montré :-la moindre efficacité de l’association oseltamivir + zanamivir par rapport à l’oseltamivir seul dans le traitement des patients grippés pour réduire la durée de la maladie et le portage viral naso-pharyngé, alors qu’un effet inverse a été observé sur la transmission de la grippe lorsque la bithérapie était administrée dans les 24 heures suivant l'apparition des symptômes ;-l’association de facteurs liés aux caractéristiques du patient et de l'infection virale avec la réponse clinique et virologique lors d’un traitement par oseltamivir ou zanamivir, avec en particulier une possible efficacité de l’oseltamivir diminuée chez la femme ;-les hésitations des médecins à appliquer systématiquement les recommandations concernant la prescription des INA en cas de syndrome grippal chez les patients à risque de grippe compliquée, en particulier lors des épidémies saisonnières. Au vu de ces résultats et dans l’attente de nouveaux traitements en cours d’évaluation, il apparait particulièrement important de continuer le travail entrepris, afin de mieux comprendre les freins à la prescription des INA et d’améliorer leur utilisation dans les années à venir
Despite numerous studies carried out and the consensus recommendations at international level, the prescription of neuraminidase inhibitors (NIs) in case of flu syndrome remains controversial. This thesis aimed to better understand the place that NIs should have for the treatment of seasonal and pandemic influenza.To answer this question, several studies have been conducted and have shown:-A lower efficacy of a combination of oseltamivir + zanamivir than oseltamivir alone in the treatment of influenza patients to reduce the duration of illness and viral nasopharyngeal carriage, while an opposite effect was observed on transmission of influenza when the combination therapy was administered within 24 hours of onset of symptoms;-Several factors related to the characteristics of the patient and the virus infection with clinical and virological response during treatment with oseltamivir or zanamivir, especially with a possible efficacy of oseltamivir lower in women;-The reluctance of physicians to systematically implement the recommendations concerning the prescription of NIs in case of influenza syndrome in patients at risk for complicated influenza, in particular during seasonal epidemics.It appears particularly important to better understand the barriers associated with the prescription of NIs and improve the use of these treatments in the years to come

An awareness of the effect of agricultural production on the environment has led to the development of policies to mitigate its adverse effects. This dissertation provides analyses of agri-environmental policies designed to protect environmental assets, as well as analytical decision-making tools useful for conducting policy evaluations. The first essay employs propensity score matching techniques to estimate the additionality of federal agricultural conservation programs for six conservation practices for farmers in Ohio. Additionality is an important measure of the effectiveness of conservation programs in inducing an increase in the conservation effort of farmers. Results suggest that additionality is positive and statistically significant for all six conservation practices. However, while programs achieve positive additionality for all practice types, a comparison between conservation practices reveals that certain practice types achieve higher percent additionality than others. Such results, coupled with information on the environmental benefits obtained per practice, could prove useful to program managers for improving the effectiveness of conservation programs. The second essay develops a new methodology to decompose the additionality measure into the two effects induced by conservation programs: expansion versus the new adoption of conservation practices. To do so, the relative contributions of two types of farmers, prior-adopters and new-adopters, are estimated. Results of the decomposition reveal that the additionality for prior-adopters is not significant for all practice types. Instead, additional conservation effort comes from new-adopters adopting new practices. Second, decomposition estimates suggest that practice types with a greater fraction of enrolled farmers that are new-adopters achieve greater percent additionality than those with greater proportions of prior-adopters. This suggests that a farmers? history in conservation adoption has a significant influence on additionality levels. The final essay analyzes the effect of recent instream flow diversion-guidelines on agricultural water security and streamflows within a decentralized water management regime. Spatially-explicit economic and hydrologic models are integrated to evaluate the tradeoffs between salmon bypass-flows and agricultural water security for three different diversion-guidelines within a northern-California watershed. Results indicate that the most restrictive diversion-guideline provides the greatest protection of bypass-flow days within smaller watersheds; however, within larger watersheds protection is not as significant. Water security, however, decreases sharply under the strict and moderate diversion-guidelines, especially during dry years. Overall, results indicate that greater focus should be given to protecting streamflows in the smallest watersheds, and meeting human water needs during dry years, when agricultural water security is impacted the most.

碩士
國立臺灣大學
口腔生物科學研究所
107
Oral cancer was ranked fifth among the top 10 cancer deaths in Taiwan in 106 years, threats to people''s lives. Surgical resection is the mainly treatment nowadays, but it may cause a wide range of facial defects and loss of oral function, which will also cause psychological stress to patients. To avoid the negative effects of traditional treatment and find a better way, researchers get into emerging treatment in recent years, including photodynamic therapy (PDT), cryotherapy, etc. 5-Aminolevulinic acid (ALA) is a commonly used drug for PDT. Through a series of metabolic pathways, it forms a protoporphyrin (PpIX)--the photosensitizer in ALA-PDT. PpIX is excited by light, produces singlet oxygen and free radicals to kill cancer cells. Clinically, ALA-PDT has been used to treat oral cancer and oral potential malignant disorder without obvious wound after treatment. The treatment effect is good and causes little effect on the normal tissue. However, PDT treatment takes times for repeating irradiation, and the price of ALA is high. Previous studies have also pointed out that different tumor size, location, depth and other factors may affect the efficacy of ALA-PDT. In addition, rapid tumor growth and PDT-mediated tumor vascular abnormalities may lead to hypoxia--which may cause insufficient oxygen content in the PDT process, and affect the therapeutic effect. Under hypoxic condition, a transcription factor called “hypoxia-inducible factor 1α (HIF1α)” is activated to protect cell. HIF1α binds to Hypoxia-Response Element (HRE) to cause signal transduction, and activates downstream genes causeing angiogenesis, invasiveness, apoptosis, metastasis, chemotherapy and radiotherapy resistance in cancer cells. Many studies have pointed out that HIF1α also promotes the increase of ATP-binding cassette sub-family G member 2 (ABCG2) and Heme oxygenase 1 (HO1) expression, which may reduce the accumulation of PpIX in cells, resulting in low PDT effectiveness. This study focused on how HIF1α affects PDT in oral cancer cells, and used inhibitors or natural drugs to reduces the effects. Aim to improve treatment efficiency and shorten treatment time and cost with combination therapy. Results of the study show that in addition to the hypoxic environment, photodynamic therapy itself also triggered the activation of HIF1α in cells. Cobalt chloride (CoCl2) was used to simulate HIF1α expression in hypoxic cells. We observed that PDT effect and the cumulative amount of PpIX decreased, and the expression levels of p-ERK, p-AKT, ABCG2, Nrf2, and HO1 were increased when we add CoCl2. There was a significant decrease in the expression of the above-mentioned proteins after inhibiting HIF1α by inhibitor YC-1. It is speculated that HIF1α may regulate Nrf2 through p-ERK and p-AKT signal transduction pathway, promote ABCG2 and HO1 transcription. These changes reduce intracellular PpIX accumulation, and affect the efficiency of PDT treatment. After combination treatment with different inhibitors and natural drugs, curcumin and PD98059 were found to increase PpIX accumulation and PDT best except YC-1. Also, curcumin reduced the expression of ABCG2, Nrf2, and HO1. From the results of this study, cells in hypoxia or high HIF1α expression were treated with low toxicity inhibitors before PDT, which significantly increased the production of PpIX, thereby reducing the cell survival rate after ALA-PDT and improving treatment effect.

by Cheung Wai-ting.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1999.
Includes bibliographical references (leaves 131-142).
Abstracts in English and Chinese.
Chapter Chapter 1 --- The Research Problem --- p.1
Chapter Chapter 2 --- Literature Review
Chapter 2.1 --- Prohibitionist Approach --- p.7
Chapter 2.2 --- Medical-Treatment Approach --- p.8
Chapter 2.3 --- How Should We Understand Post-Treatment Drug Use Behavior ？ --- p.14
Chapter Chapter 3 --- Analytical Framework
Chapter 3.1 --- Social Capital Theory --- p.24
Chapter 3.2 --- Differential Association Theory and Social Capital --- p.26
Chapter 3.3 --- Control Theory and Social Capital --- p.31
Chapter 3.4 --- Labeling Theory --- p.39
Chapter 3.5 --- Self-Efficacy Theory --- p.44
Chapter 3.6 --- The Hypotheses --- p.48
Chapter Chapter 4 --- Methodology
Chapter 4.1 --- Data and Sample --- p.52
Chapter 4.2 --- General Profile of Respondents --- p.54
Chapter 4.3 --- Conceptualization and Operationalization of Variables --- p.57
Chapter 4.4 --- Method of Data Analysis --- p.66
Chapter Chapter 5 --- Results
Chapter 5.1 --- Quantitative Analysis --- p.68
Chapter 5.1.1 --- Bivariate Analysis
Chapter 5.1.2 --- Path Analysis
Chapter 5.1.3 --- Verification of Hypotheses
Chapter 5.2 --- Qualitative Analysis --- p.86
Chapter Chapter 6 --- Summary and Discussion
Chapter 6.1 --- The Study --- p.112
Chapter 6.2 --- Summary of Findings --- p.113
Chapter 6.3 --- Theoretical Implications --- p.117
Chapter 6.4 --- Practical Implications --- p.120
Chapter 6.5 --- Limitations and Suggestions for Future Research --- p.122
Appendix I Interview Schedule --- p.125
Appendix II Socio-demographic Profile of the Ten Informants --- p.127
Bibliography --- p.130

Indiana University-Purdue University Indianapolis (IUPUI)
Observational data are frequently used for causal inference of treatment effects on prespecified outcomes. Several widely used causal inference methods have adopted the method of inverse propensity score weighting (IPW) to alleviate the in uence of confounding. However, the IPW-type methods, including the doubly robust methods, are prone to large variation in the estimation of causal e ects due to possible extreme weights. In this research, we developed an ordinary least-squares (OLS)-based causal inference method, which does not involve the inverse weighting of the individual propensity scores. We first considered the scenario of homogeneous treatment effect. We proposed a two-stage estimation procedure, which leads to a model-free estimator of average treatment effect (ATE). At the first stage, two summary scores, the propensity and mean scores, are estimated nonparametrically using regression splines. The targeted ATE is obtained as a plug-in estimator that has a closed form expression. Our simulation studies showed that this model-free estimator of ATE is consistent, asymptotically normal and has superior operational characteristics in comparison to the widely used IPW-type methods. We then extended our method to the scenario of heterogeneous treatment effects, by adding in an additional stage of modeling the covariate-specific treatment effect function nonparametrically while maintaining the model-free feature, and the simplicity of OLS-based estimation. The estimated covariate-specific function serves as an intermediate step in the estimation of ATE and thus can be utilized to study the treatment effect heterogeneity. We discussed ways of using advanced machine learning techniques in the proposed method to accommodate high dimensional covariates. We applied the proposed method to a case study evaluating the effect of early combination of biologic & non-biologic disease-modifying antirheumatic drugs (DMARDs) compared to step-up treatment plan in children with newly onset of juvenile idiopathic arthritis disease (JIA). The proposed method gives strong evidence of significant effect of early combination at 0:05 level. On average early aggressive use of biologic DMARDs leads to around 1:2 to 1:7 more reduction in clinical juvenile disease activity score at 6-month than the step-up plan for treating JIA.

The microbial aggregates (flocs) formed during secondary biological treatment of wastewater shield microbes from exposure to ultraviolet (UV) light, and decrease the efficiency of disinfection, causing the tailing phenomena. This thesis investigates whether the formation of compact cores within flocs induces higher levels of UV resistance. Moreover, it investigates the effect of secondary treatment conditions on the physicochemical properties of flocs’, effluent quality, and UV disinfection performance. Compact cores were isolated from the flocs using hydrodynamic shearing. The UV dose response curves (DRC) were constructed for flocs and cores, and the 53-63 μm cores showed 0.5 log less disinfectability, compared to flocs of similar size. Based on a structural model developed for the UV disinfection of flocs, floc disinfection kinetics was sensitive to the core’s relative volume, their density, and viability. The UV disinfection and floc properties of a conventional activated sludge (CAS) system, and a biological nutrient removal (BNR-UCT) system, including both biological nitrogen and phosphorus removal, was compared. The 32-53 μm flocs and the final effluent from the BNR-UCT reactor showed 0.5 log and 1 log improvement in UV disinfectability, respectively, compared to those from the CAS reactor. The BNR-UCT flocs were more irregular in structure, and accumulated polyphosphates through enhanced biological phosphorus removal. Polyphosphates were found to be capable of producing hydroxyl radicals under UV irradiation, causing the photoreactive disinfection of microorganisms embedded within the BNR-UCT flocs, accelerating their UV disinfection. Comparing the UV disinfection performance and floc properties at various operating conditions showed that increasing the operating temperature from 12 ºC to 22 ºC, improved the UV disinfection of effluent by 0.5 log. P-Starved condition, i.e. COD:N:P of 100:10:0.03, decreased the average floc size and sphericity, both by 50%. Despite the higher effluent turbidity of the P-Starved reactor, the final effluent’s UV disinfection improved by at least 1 log compared to the P-Normal and P-Limited conditions. The improvement in the floc and effluent disinfectability were accompanied by a decrease in floc sphericity and a decrease in the number of larger flocs in the effluent, respectively.

Dans cette thèse, je me suis interessé à l’identification partielle des effets de traitements dans différents modèles de choix discrets avec traitements endogènes. Les modèles d’effets de traitement ont pour but de mesurer l’impact de certaines interventions sur certaines variables d’intérêt. Le type de traitement et la variable d’intérêt peuvent être défini de manière générale afin de pouvoir être appliqué à plusieurs différents contextes. Il y a plusieurs exemples de traitement en économie du travail, de la santé, de l’éducation, ou en organisation industrielle telle que les programmes de formation à l’emploi, les techniques médicales, l’investissement en recherche et développement, ou l’appartenance à un syndicat. La décision d’être traité ou pas n’est généralement pas aléatoire mais est basée sur des choix et des préférences individuelles. Dans un tel contexte, mesurer l’effet du traitement devient problématique car il faut tenir compte du biais de sélection. Plusieurs versions paramétriques de ces modèles ont été largement étudiées dans la littérature, cependant dans les modèles à variation discrète, la paramétrisation est une source importante d’identification. Dans un tel contexte, il est donc difficile de savoir si les résultats empiriques obtenus sont guidés par les données ou par la paramétrisation imposée au modèle. Etant donné, que les formes paramétriques proposées pour ces types de modèles n’ont généralement pas de fondement économique, je propose dans cette thèse de regarder la version nonparamétrique de ces modèles. Ceci permettra donc de proposer des politiques économiques plus robustes. La principale difficulté dans l’identification nonparamétrique de fonctions structurelles, est le fait que la structure suggérée ne permet pas d’identifier un unique processus générateur des données et ceci peut être du soit à la présence d’équilibres multiples ou soit à des contraintes sur les observables. Dans de telles situations, les méthodes d’identifications traditionnelles deviennent inapplicable d’où le récent développement de la littérature sur l’identification dans les modèles incomplets. Cette littérature porte une attention particuliere à l’identification de l’ensemble des fonctions structurelles d’intérêt qui sont compatibles avec la vraie distribution des données, cet ensemble est appelé : l’ensemble identifié. Par conséquent, dans le premier chapitre de la thèse, je caractérise l’ensemble identifié pour les effets de traitements dans le modèle triangulaire binaire. Dans le second chapitre, je considère le modèle de Roy discret. Je caractérise l’ensemble identifié pour les effets de traitements dans un modèle de choix de secteur lorsque la variable d’intérêt est discrète. Les hypothèses de sélection du secteur comprennent le choix de sélection simple, étendu et généralisé de Roy. Dans le dernier chapitre, je considère un modèle à variable dépendante binaire avec plusieurs dimensions d’hétérogéneité, tels que les jeux d’entrées ou de participation. je caractérise l’ensemble identifié pour les fonctions de profits des firmes dans un jeux avec deux firmes et à information complète. Dans tout les chapitres, l’ensemble identifié des fonctions d’intérêt sont écrites sous formes de bornes et assez simple pour être estimées à partir des méthodes d’inférence existantes.
In this thesis, I have been interested in the nonparametric (partial) identification of structural potential outcome functions and Average Treatment Effect (ATE) in various discrete models with endogenous selection and treatment. This topic of treatment effect concerns measuring the impact of an intervention on an outcome of interest. The type of treatments and outcomes may be broadly defined in order to be applied in many different contexts. There are many examples of treatment in economics (Labor, health, education, trade, industrial organization) such that Job training programs, surgical procedures, higher education level, research and development investment, being a member of a trade union etc. The decision to be treated or not, is usually not random but is based on individual choices or preferences. In such a context, determining the impact of the treatment becomes an important issue since we have to take into account the selectivity bias. The parametric version of such models has been widely studied in the literature, however in models with discrete variation, the parametrization is a strong source of identification. Then, we don’t know if the empirical results we obtain, are driven by the data or by the parametrization imposed on the model. I propose to look at a fully nonparametric version of those models, in order, to have more robust policy recommendations. The central challenge in this nonparametric structural identification is that the hypothesized structure fails to identify a single generating process for the data, either because of multiple equilibria or data observability constraints. In such cases, many traditional identification techniques become inapplicable and a framework for identification in incomplete models is developing, with an initial focus on identification of the set of structural functions of interest compatible with the true data distribution (hereafter identified set). Therefore, in the first chapter, I provide a full characterization of the identified set for the ATE in a binary triangular system. In the second chapter, I consider a model with sector specific unobserved heterogeneity. I provide the full characterization of the identified set for the structural potential outcome functions of an instrumental variables model of sectoral choice with discrete outcomes. Assumptions on selection include the simple, extended and generalized Roy models. In the last chapter, I consider a binary model with several unobserved heterogeneity dimensions, such as entry and participation games. I provide the full characterization of the identified set for the payoffs in 2 2 games with perfect information, including duopoly entry and coordination games. In all chapters, the identified set of the functions of interest are nonparametric intersection bounds and are simple enough to lend themselves to existing inference methods.

The utilization of in vitro tests with a tiered testing strategy for detection of mild ocular irritants can reduce the use of animals for testing, provide mechanistic data on toxic effects, and reduce the uncertainty associated with dose selection for clinical trials. The first section of this thesis describes how in vitro methods can be used to improve the prediction of the toxicity of chemicals and ophthalmic products. The proper utilization of in vitro methods can accurately predict toxic threshold levels and reduce animal use in product development. Sections two, three and four describe the development of new sensitive in vitro methods for predicting ocular toxicity. Maintaining the barrier function of the cornea is critical for the prevention of the penetration of infections microorganisms and irritating chemicals into the eye. Chapter 2 describes the development of a method for assessing the effects of chemicals on tight junctions using a human corneal epithelial and canine kidney epithelial cell line. In Chapter 3 a method that uses a primary organ culture for assessing single instillation and multiple instillation toxic effects is described. The ScanTox system was shown to be an ideal system to monitor the toxic effects over time as multiple readings can be taken of treated bovine lenses using the nondestructive method of assessing for the lens optical quality. Confirmations of toxic effects were made with the utilization of the viability dye alamarBlue. Chapter 4 describes the development of sensitive in vitro assays for detecting ocular toxicity by measuring the effects of chemicals on the mitochondrial integrity of bovine cornea, bovine lens epithelium and corneal epithelial cells, using fluorescent dyes. The goal of this research was to develop an in vitro test battery that can be used to accurately predict the ocular toxicity of new chemicals and ophthalmic formulations. By comparing the toxicity seen in vivo animals and humans with the toxicity response in these new in vitro methods, it was demonstrated that these in vitro methods can be utilized in a tiered testing strategy in the development of new chemicals and ophthalmic formulations.