Robust and Semiparametric Statistical Modeling for Cancer Research.

In the application of biostatistical methodology to cancer studies, there is a desire to use methods with fewer or less restrictive assumptions, which often lead to more easily generalizable conclusions. The first chapter deals with robust modeling of binary responses with the goal of improving classification at an arbitrary probability threshold dictated by the particular application. Specifically, for the linear logistic model, we solve a set of locally weighted score equations, using a kernel-like weight function centered at the threshold. This work has much in common with robust estimation, but differs from previous approaches in this area in its focus on prediction, specifically classification into high- and low-risk groups. Analysis of a melanoma data set is presented to illustrate the use of the method in practice. The second chapter addresses the difficulties inherent in investigating time to cancer onset when only time to diagnosis can be observed. To address this problem, we propose a joint model for the unobserved time to the latent and terminal events, with the two events linked by the baseline hazard. We propose an EM algorithm for estimation of the baseline hazard, which allows for closed-form Breslow-type estimators at each iteration, reducing computational time compared with maximizing the marginal likelihood directly. We demonstrate use of the method with analysis of a prostate cancer data set from SEER. In the third chapter, we apply methodology originally used in survival analysis to model semicontinuous data. Continuous outcome data with a proportion of observations equal to zero arises frequently in biomedical studies. We propose a semiparametric model based on a biological system with competing damage manifestation and resistance processes. This allows us to derive a partial likelihood based on the retro-hazard function, leading to a flexible procedure for modeling continuous data with a point mass at zero. We apply the method to a data set consisting of pulmonary capillary hemorrhage area in lab rats subjected to diagnostic ultrasound.PhDBiostatisticsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113285/1/jdrice_1.pd

COLONIZATION OF NORTHERN LOUISIANA BY THE MEDITERRANEAN GECKO, HEMIDACTYLUS TURCICUS

The Mediterranean Gecko, Hemidactylus turcicus, is known to have colonized nearly every state in the southern United States. In Louisiana, the Mediterranean Gecko has been documented in many of the southern parishes, but records for the northern portion of the state are limited. We sampled northern Louisiana parishes to document the presence of the Mediterranean Gecko. We sampled a total of 21 parishes in northern Louisiana and found geckos in 17 of those parishes, 16 of which represent new distribution records for the species. This indicates a significant range expansion of this introduced species throughout northern Louisiana. Geckos were found across a temperature range of 14.0–28.0°C and had a strong association with buildings. The species’ affinity for anthropogenic association and the continual nature of anthropogenic expansion facilitate the high vagility of this species. The result is a successful colonization throughout much of Louisiana and likely continued range expansion throughout the southern United States

Semiparametric profile likelihood estimation for continuous outcomes with excess zeros in a random‐threshold damage‐resistance model

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136688/1/sim7237.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136688/2/sim7237_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136688/3/sim7237-0001-supplementary.pd

Revisiting an integrated approach to bean leaf beetle and bean pod mottle virus management

This article originally appeared in the 2005 ICM newsletter. However, the significance of the bean leaf beetle and bean pod mottle virus has not diminished in recent years. There is still the potential of economic damage from either or both pests. We have recently completed a three-year study that examines the complex issues of managing these two pests, but the data are still being analyzed. We also have identified potential field tolerance to virus disease. Growers are encouraged to query seed dealers regarding tolerance of varieties to virus disease. Ultimately, this will likely be the best management tool for disease control. In the meantime, we give you our best recommendations as we understand the situation in Iowa

Timing is everything: Drivers of interannual variability in blue whale migration.

Blue whales need to time their migration from their breeding grounds to their feeding grounds to avoid missing peak prey abundances, but the cues they use for this are unknown. We examine migration timing (inferred from the local onset and cessation of blue whale calls recorded on seafloor-mounted hydrophones), environmental conditions (e.g., sea surface temperature anomalies and chlorophyll a), and prey (spring krill biomass from annual net tow surveys) during a 10 year period (2008-2017) in waters of the Southern California Region where blue whales feed in the summer. Colder sea surface temperature anomalies the previous season were correlated with greater krill biomass the following year, and earlier arrival by blue whales. Our results demonstrate a plastic response of blue whales to interannual variability and the importance of krill as a driving force behind migration timing. A decadal-scale increase in temperature due to climate change has led to blue whales extending their overall time in Southern California. By the end of our 10-year study, whales were arriving at the feeding grounds more than one month earlier, while their departure date did not change. Conservation strategies will need to account for increased anthropogenic threats resulting from longer times at the feeding grounds

Seed treatments in soybean: Managing bean leaf beetles

To date, our recommendation for the chemical control of bean leaf beetles and bean pod mottle virus has been for an early and a mid-season application of a pyrethroid insecticide (e.g., Asana®, Mustang®, or Warrior®). These insecticide applications should be timed such that fields are treated as soon as bean leaf beetles are first detected in the field (the early-season application) and again when the first generation emerges in early July (the mid-season application). These applications have been shown to improve yield and seed quality under high disease and beetle pressure