Medicine and Health Sciences Commons^™

Regressing Scalar Outcomes On Image Predictors Via Functional Principal Component Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Worldwide Variation In The Doubling Time Of Alzheimer's Disease Incidence Rates, Kathryn Ziegler-Graham, Ron Brookmeyer, Elizabeth Johnson, H. Michael Arrighi

Ron Brookmeyer

Background The doubling time is the number of chronological years for the age-specific incidence rate to double in magnitude. Doubling times describe the rate of increase of the risk of Alzheimer's disease (AD) with advancing age. Estimates of doubling times of AD assist in understanding disease etiology and forecasting future disease prevalence. The objective of this study was to investigate regional and gender differences in the doubling of AD age-specific incidence rates.

Methods We identified all studies in the peer review literature that reported age-specific incidence rates for AD. We modeled the logarithm of the incidence rate as a linear …

Simultaneous Confidence Bands For The Coefficient Function In Functional Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Inferring Group Differences In Brain Connectivity From Functional Magnetic Resonance Images, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Reliability Of Functional Connectivity Networks: How Can We Assess It?, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Bayesian Identification, Selection And Estimation Of Functions In High-Dimensional Additive Models, Anastasios Panagiotelis, Michael Smith

Michael Stanley Smith

In this paper we propose an approach to both estimate and select unknown smooth functions in an additive model with potentially many functions. Each function is written as a linear combination of basis terms, with coefficients regularized by a proper linearly constrained Gaussian prior. Given any potentially rank deficient prior precision matrix, we show how to derive linear constraints so that the corresponding effect is identified in the additive model. This allows for the use of a wide range of bases and precision matrices in priors for regularization. By introducing indicator variables, each constrained Gaussian prior is augmented with a …

The T-Mixture Model Approach For Detecting Differentially Expressed Genes In Microarrays, Shuo Jiao, Shunpu Zhang

Shuo Jiao

The finite mixture model approach has attracted much attention in analyzing microarray data due to its robustness to the excessive variability which is common in the microarray data. Pan (2003) proposed to use the normal mixture model method (MMM) to estimate the distribution of a test statistic and its null distribution. However, considering the fact that the test statistic is often of t-type, our studies find that the rejection region from MMM is often significantly larger than the correct rejection region, resulting an inflated type I error. This motivates us to propose the t-mixture model (TMM) approach. In this paper, …

Mapping As A Knowledge Translation Tool For Ontario Early Years Centres: Views From Data Analysts And Managers, Anita Kothari, S. Michelle Driedger, Julia Bickford, Jason Morrison, Michael Sawada, Ian D. Graham, Eric Crighton

Anita Kothari

Background: Local Ontario Early Years Centres (OEYCs) collect timely and relevant local data, but knowledge translation is needed for the data to be useful. Maps represent an ideal tool to interpret local data. While geographic information system (GIS) technology is available, it is less clear what users require from this technology for evidence-informed program planning. We highlight initial challenges and opportunities encountered in implementing a mapping innovation (software and managerial decision-support) as a knowledge translation strategy.

Methods: Using focus groups, individual interviews and interactive software development events, we taped and transcribed verbatim our interactions with nine OEYCs in Ontario, Canada. …

Multinomial Logistic Regression: An Application To Estimating Performance Of A Multiple Screening Test For Bowel Cancer When Negatives Are Unverified., Chris Lloyd, Don Frommer

Chris J. Lloyd

This paper describes a method of estimating the performance of a multiple screening test where those who test negative do not have their true disease status determined. The methodology is motivated by a dataset on 49,927 subjects who were given K=6 binary tests for bowel cancer. A complicating factor is that individuals may have polyps present in the bowel, a condition that the screening test is not designed to detect but which may be worth diagnosing. The methodology is based on a multinomial logit model for Pr(S|R_6), the probability distribution of patient status S (healthy, polyps or diseased) conditional on …

A New Exact And More Powerful Unconditional Test Of No Treatment Effect From Binary Matched Pairs, Chris Lloyd

Chris J. Lloyd

We consider the problem of testing for a difference in the probability of success from matched binary pairs. Starting with three standard inexact tests, the nuisance parameter is first estimated and then the residual dependence is eliminated by maximisation, producing what I call an E+M P-value. The E+M P-value based on McNemar's statistic is shown numerically to dominate previous suggestions, including partially maximised P-values as described in Berger and Sidik (2003). The latter method however may have computational advantages for large samples.

Dosimetric Evaluation Of Helical Tomotherapy Treatment Planning For Non-Small Cell Lung Cancer, Karen Chu, George Rodrigues, Slav Yartsev, A. Rashid Dar, Edward Yu, Robert Ash, Brian Yaremko, Marc Mackenzie, Harvey Quon, Glenn Bauman, Wilson Roa

Edward Yu

Helical tomotherapy (HT) is a novel technique to deliver intensity modulated radiation therapy guided by 3D megavoltage CT imaging. The purpose of our study is to assess the dosimetric parameters related to HT and 3DCRT in advanced non-small cell lung cancer (NSCLC). Eleven patients from the London Regional Cancer Centre and the Cross Cancer Institute with NSCLC underwent individualized treatment planning on both HT and 3DCRT. Corresponding HT and 3DCRT plans for each patient were analyzed using dose-volume histograms for GTV, PTV (median dose 60Gy/30 fractions), and critical structures (lung V5-30, esophageal V50-60, and spinal cord D1). Observed differences in …

Cascading Infrastructure Failures: Avoidance And Response, George H. Baker, Cheryl J. Elliott

George H Baker

No critical infrastructure is self-sufficient. The complexity inherent in the interdependent nature of infrastructure systems complicates planning and preparedness for system failures. Recent wide-scale disruption of infrastructure on the Gulf Coast due to weather, and in the Northeast due to electric power network failures, dramatically illustrate the problems associated with mitigating cascading effects and responding to cascading infrastructure failures once they have occurred.

The major challenge associated with preparedness for cascading failures is that they transcend system, corporate, and political boundaries and necessitate coordination among multiple, disparate experts and authorities. This symposium brought together concerned communities including government and industry …

Long-Term Consequences Of The Delay Between Virologic Failure Of Highly Active Antiretroviral Therapy And Regimen Modification, Maya L. Petersen, Mark J. Van Der Laan, Napravnik Sonia, Joseph J. Eron, Richard G. Moore, Steven G. Deeks

Maya Petersen

Objectives: Current treatment guidelines recommend immediate modification of antiretroviral therapy in HIV-infected individuals with incomplete viral suppression. These recommendations have not been tested in observational studies or large randomized trials. We evaluated the consequences of delayed modification following virologic failure. Design/methods: We used prospective data from two clinical cohorts to estimate the effect of time until regimen modification following first regimen failure on all-cause mortality. The impact of regimen type was also assessed. As the effect of delayed switching can be confounded if patients with a poor prognosis modify therapy earlier than those with a good prognosis, we used a …

Functional Generalized Linear Models With Applications To Neuroimaging, Philip T. Reiss, R. Todd Ogden

Philip T. Reiss

No abstract provided.