No description available.

Multiple testing is playing an important role in analyzing data from modern scientific investigations. Some fundamentally important theoretical and methodological issues related to multiple testing still remain to be fully investigated. Often the correlation structure among test statistics involved in multiple testing is known a priori or it can be estimated from the data, yet this structure is not often properly taken into consideration while developing multiple testing procedures, even though not doing so might result in a less powerful method than one would like to have or lead to irrelevant or misleading conclusions. This dissertation focuses on research related to improving some of the commonly used multiple testing procedures by incorporating correlations into them. We propose several new results in this dissertation and present some ideas to carry out further research. / Statistics

A counter-current two-phase flow under an applied electric field has been studied theoretically using potential flow equations. A flooding correlation has been derived taking account of applied electric field on the interface for both adiabatic and condensing system. It is found that the electric field enhances flooding phenomena in case of adiabatic system. In the case with system involving condensation the electric field enhances flooding at low liquid flow rates and at high liquid flow rates the flooding point decreases under electric field depending on the rate of subcooling. / Thesis / Master of Engineering (ME)

No description available.

The ever-increasing complexity and size of current circuit designs have made testing and verification major bottlenecks in the design flow of VLSI (Very Large Scale Integrated) circuits. Statistics show that more than 70% of the design effort can be spent on functional verification and manufacturing testing. This percentage is expected to increase in the future if no significant strides in these areas are made. In this dissertation, we target three related problems in simulation-based Design Verification and Testing: Sequential ATPG (Automatic Test Pattern Generation), Unbounded Model Checking (UMC) of safety properties, and low power testing for full-scan sequential circuits. We model these three problems as simulation-based pattern generation problems and exploit novel ATPG algorithms to increase the effectiveness of sequential ATPGs. The main challenge for fault/error detection in sequential circuits is the large number of flip-flops (FFs) in modern designs. Due to the large number and variable length of test sequences required for such circuits, the existing deterministic ATPG algorithms fail to achieve high test coverages. Such algorithms typically work by first unrolling the sequential circuit and then performing frequent backtracking to generate test vectors for fault detection. For the hard-to-detect faults, these schemes either run out of memory or require a huge computational effort. We show that simulation-based ATPGs, on the other hand, scale very well for large circuits as they perform only forward simulation. A fundamental problem associated with simulation-based ATPGs is to avoid exhaustive circuit simulation, which is impractical for large designs in the real world, by choosing high quality test vectors that achieve a high test coverage within a low simulation time. We tackle this primary problem by exploiting different correlation-based heuristics. The intuition behind using correlation-based heuristics is to better guide the pattern generation engine such that the specific objective of either fault detection or property verification in UMC or minimizing power consumption during the testing, is achieved in an efficient manner without resorting to exhaustive simulation. In particular, we model and explore the following correlations: (1) temporal correlations, i.e. correlations on each primary input (PI) in different time frames, and (2) spatial correlations, i.e. correlations among different FFs in the same time frame. We employ temporal correlations in the context of pattern generation of a built-in-self-test (BIST) architecture and we explore spatial correlations to guide a logic-simulation-based sequential ATPG and low power scan test generation. Experimental results on ISCAS and ITC benchmark circuits have shown that those correlations can enhance the simulation to discover more faults or design errors in a significantly shorter time. / Ph. D.

Statistically significant prediction of stock price changes requires security returns' correlation with, or dependence upon, some variable(s) across time. Since a security's past return is commonly employed in forecasting, and because the lack of lower-order correlation does not guarantee higher-order independence, nonlinear testing that focuses on higher-order moments of stock return distributions may reveal exploitable stock return dependencies. This dissertation fits AR models to TAQ data sampled at ten-minute intervals for 20 small-capitalization, 20 mid-capitalization, and 20 large-capitalization NYSE securities, for the years 1993, 1995, 1997, 1999 and 2001. The Hinich Patterson Bicovariance statistic (to reveal nonlinear and linear autocorrelation) is computed for each of the 1243 trading days for each of the 60 securities. This statistic is examined to see if it is more or less likely to occur in securities with differing market capitalization, at various calendar periods, in conjunction with trading volume, or instances of changing investor sentiment, as evidenced by the put-call ratio. There is a statistically significant difference in the level and incidence of nonlinear behavior for the different-sized portfolios. Large-cap stocks exhibit the highest level and greatest incidence of nonlinear behavior, followed by mid-cap stocks, and then small-cap stocks. These differences are most pronounced at the beginning of decade and remain significant throughout the decade. For all size portfolios, nonlinear correlation increases throughout the decade, while linear correlation decreases. Statistical significance between the nonlinear or the linear test statistics and trading volume occur on a year-by-year basis only for small-cap stocks. There is sporadic seasonality significance for all portfolios over the decade, but only the small-cap portfolio consistently exhibits a notable "December effect". The average nonlinear statistic for small-cap stocks is larger in December than for other months of the year. The fourth quarter of the year for small-cap stocks also exhibits significantly higher levels of nonlinearity. An OLS regression of the put/call ratio to proxy for investor sentiment against the H and C statistic was run from October 1995 through December 2001. There are instances of sporadic correlations among the different portfolios, indicating this relationship is more dynamic than previously imagined. / Ph. D.

This dissertation involved two experiments, (1) the study of realized heritabilities of correlated traits, and (2) the study of the inheritance of sexual dimorphism or body weight. The first experiment included data from four generations of double two-way selection for body weight and breast angle at eight weeks of age. Breast angle was considered a correlated trait in the weight subpopulation and body weight a correlated trait in the angle subpopulation. There was a significant divergence between lines for both selected traits. The response to direct selection for breast angle was asymmetrical with the response in the narrow direction being greater then that in the broad direction. The response of body weight to two-way selection was symmetrical through the F₄ generation. Divergence of body weight between the lines selected for breast angle was significant in the F₁, F₃, and F₄ generations. Divergence of breast angle between the lines selected for body weight was significant in the F₂ and subsequent generations. Heritabilities of the unselected traits were obtained by the cumulative difference between lines divided by the expected secondary selection differential and by the regression of the cumulative difference between lines on expected secondary selection differential. The correlated realized heritability of breast angle was greater in the weight lines than was the correlated realized heritability for body weight in the angle lines. Examination of the components of the correlated realized heritability showed that they were the ratio of the genetic to phenotypic covariances of the two traits. The second experiment involved the investigation of sex dimorphism for body weight at eight weeks of age. The heritability estimate for sex dimorphism of this trait was .02, and the genetic correlation of it in males and females was .98. The genetic variability (.02) in sex dimorphism was evidenced by a greater response in males to selection for eight-week body weight than in females. The biological reason for this was additive sex-linkage. / Ph. D.

Considerable attention has been devoted to the rank correlation coefficients of Spearman and Kendall, denoted by r_S and r_K respectively. These coefficients were first proposed as measures of association between two groupings, requiring no assumptions on the parent distribution of the observations. Later work considered the distributions of r_S and r_K when the parent distribution is the bivariate normal. This study is an investigation of the moments and related properties of Spearman's r_S and Kendall's r_K when the underlying distribution is the singly truncated bivariate normal. / Ph. D.

Study design is among the most fundamental factors influencing collection and interpretation of data. The purpose of this study is to understand the effect of design choices by evaluating gait mechanics in healthy control participants using three primary objectives: 1) determine the repeatability of marker placement, 2) determine the effect of set versus self-selected walking speed, and 3) examine the correlation between gait asymmetry and motor variability. Ten and fifty-one healthy control participants were recruited for aim 1 and aims 2/3, respectively. Reflective markers were placed on lower-extremity bony landmarks and participants walked on an instrumented treadmill while 3D motion capture data was collected. For aim 1, this procedure was repeated at two time points 30 minutes apart. For aims 2 and 3, participants completed set and self-selected speed trials. JMP Pro 13 was used to compare joint kinetics and gait kinematics for all aims. Marker placement was repeatable between time points. Participants walked slower in the self-selected walking speed trial, which resulted in both kinematic and kinetic gait mechanics alterations. Gait asymmetry was significantly correlated with motor variability for both spatial and temporal measures. Current study findings reiterated the importance of walking speed when evaluating gait symmetry, joint kinetics, and kinematics. The decision regarding whether to utilize a set or self-selected speed condition within a study design should be made based on whether the measures of interest are independent of walking speed. Gait asymmetry and motor variability are related and should not be treated as independent components of gait. / Master of Science / This study aims to evaluate gait mechanics in healthy young adults by evaluating the impact of multiple study design choices and relationships between different aspects of gait (walking). Loading and movement walking data was collected from a total of sixty-one participants. This data was then used to calculate several measures of gait including symmetry between limbs, joint ranges of motion, and variability of movement. The potential impact of study design choices including setting walking speed for all participants and evaluating loading asymmetry and movement variability independently are discussed based on the findings of the current study.

Tendinopathy is a common pathology of tendons characterized by pain and a decrease in function resulting from changes in the tissue's structure and/or composition due to injury. Diagnosis of tendinopathy is determined by the qualitative analysis of a trained physician usually with assistance from an imaging modality. Although physicians can often identify tendinopathy, there are no quantitative metrics to evaluate tendon fatigue, damage, or healing. Physical therapy (PT) is a common treatment for patients with tendinopathy, and recent studies have investigated Focused Ultrasound (FUS) for its treatment of tendons. Developments in the use of FUS as a therapeutic have led to studies of the underlying mechanisms by which it operates. Digital Image Correlation (DIC) is a non-contact method of quantifying tissue displacements and strains of a deforming material using high resolution imaging DIC programs can evaluate and interpolate strain data by applying statistical image processing algorithms and solid continuum mechanics principles using a set of sequential image frames capturing the mechanical deformation of the specimen during testing. The studies presented in this thesis investigate methodologies for using DIC with ultrasound imaging of mouse Achilles tendons to characterize strains resulting from FUS therapies. The first method is based upon an orthogonal configuration of therapy and imaging transducers while the second investigates a coaxial experimental configuration. This work explores DIC as a viable means of quantifying the mechanical stimulation caused by FUS therapies on tendon tissue through ultrasound imaging to better understand the underlying mechanisms of FUS therapy. / Master of Science / Tendinopathy is a common injury that many people will experience in their lifetime. Pain and swelling are common symptoms and can make daily actions uncomfortable to perform. Physical therapy (PT) is one of the most common ways to help relieve the symptoms of this condition. A therapy being investigated to help treat tendinopathy utilizes Focused Ultrasound (FUS) technology to help the healing process. PT can be difficult and painful for those experiencing tendinopathy, but if a therapeutic like FUS could mimic the effects of PT, then some patients would not need to perform these physically demanding tasks. To understand if this treatment is viable, we need to better understand the underlying mechanisms by which it operates. Therefore, we are investigating the mechanical stimulation that FUS imparts on tendons because it is believed that the mechanical stimulations from exercise are a primary contributor to healing. Specifically, we want to evaluate the kind of strains applied by FUS therapies to inform decisions about dosage. One method uses Digital Image Correlation (DIC). DIC is a method of evaluating displacements and strains using non-contact high resolution imaging. DIC works using statistically motivated algorithms to calculate the deformation between subsequent video frames in a given material undergoing a state of stress. Using this technology along with ultrasound imaging, this work gives a preliminary exploration of using DIC as a means of quantifying strain to better understand the underlying mechanisms of the mechanical stimulations caused by FUS therapy.