Confidence Interval Estimation of Cumulative Incidence for Clustered Competing Risks

In a cluster randomized trial studying a primary outcome patients are sometimes exposed to competing events. These are risks that alter the probability of the primary outcome occurring. Traditional methods of estimating the cumulative incidence for an outcome and its associated confidence interval under competing risks do not account for the effect of clustering. This may cause incorrect estimation of confidence intervals because outcomes among patients from the same center are correlated. This thesis compared six nonparametric methods of confidence interval construction for cumulative incidence, four of which account for clustering effect, under competing risks via simulation study. Over the range of examined scenarios, if the clustering effect is mild (i.e. ICC = 0.01), estimators not accounting for clustering never have worse coverage than those that do. However, in cases with a large clustering effect (i.e. ICC = 0.05), using confidence interval estimators accounting for clustering should be considered

Industrial applications of principles of green chemistry

Cross-linked polyethylene has higher upper use temperature than normal polyethylene and is used as an insulating material for electricity carrying cables and hot water pipes. The most common method of inducing crosslinks is by reaction with silanes. After incorporation of silanes into polyethylene and upon hydrolysis with ambient moisture or with hot water, Si-O-Si crosslinks are formed between the various linear polyethylene chains. Industrially, this reaction is performed routinely. However, the efficiency of this reaction with respect to the silane is low and control of product distribution is difficult. A precise fundamental understanding is necessary to be able to manipulate the reactions and thus, allow for the facile processing of the polymers. Hydrocarbon models of polymers - heptane, dodecane - are being used to study this reaction in the laboratory. For the reaction, vinyltrimethoxysilane is used as the grafting agent along with di-tert-butyl peroxide as the radical initiator. MALDI, a mass spectrometric technique is used for the analysis of the product distribution after work-up. Advanced NMR techniques (COSY, HSQC, DEPT, APT, HMBC) are being conducted on the grafted hydrocarbon compounds to gain an in-depth understanding of the mechanism and regiochemistry of the grafting reaction. Scalable and cost effective methods to capture CO2 are important to counterbalance some of the global impact of the combustion of fossil fuels on climate change. The main options available now include absorption, adsorption and membrane technology. Amines, especially monoethanolamine, have been the most commercialized technology. However, it is not without disadvantages. House et al have investigated the energy penalty involved in the post-combustion CO2 capture and storage from coal-fired power plants and found that 15-20% reduction in the overall electricity usage is necessary to offset the penalty from capturing and storing 80% of United States coal fleet's CO2 emssions1. Novel non-aqueous amine solvents, developed by the Eckert Liotta group, react with CO2 to form ionic liquids. The ionic liquids readily desorb CO2 upon heating, regenerating the reactive amines and this cycle can be carried out multiple times. An iterative procedure is being adopted to develop amine solvents for CO2 capture. Thermodynamic information like reversal temperature and boiling point of the solvents are collected; they are then used to formulate structure property relationships which allow for new molecules to be engineered. On reaction with CO2, there is a sharp increase in viscosity which is unfavorable from a processing standpoint. Many approaches to mitigate and control viscosity are being studied as well. 1House et al, Energy Environ Sci, 2009, 2, 193-205MSCommittee Chair: Dr Charles Eckert; Committee Co-Chair: Dr Charles Liotta; Committee Member: Dr Amyn Tej

Recurrent Painful Cranial Neuropathy in a Child Involving Multiple Cranial Nerves

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147093/1/head13430_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147093/2/head13430.pd