Public Health Commons^™

Human Development And Resources Use In The Coastal Zone: Influences On Human Health, Robert E. Bowen, Anamarija Frankic, Mary E. Davis

Environmental, Earth, and Ocean Sciences Faculty Publication Series

Coastal watersheds and nearshore marine areas are the most valuable and dynamic places on Earth. Human population growth is great in these regions, which are home to some of the most sensitive habitats in the world. Coastal areas provide more than half of the overall service value derived from the global environment (Costanza et al., 1997). Natural (e.g., hurricanes and tsunamis) and human pressures on this environment require it to constantly adjust. More than any other area, the global coast has defined the progress of human culture and continues to be a singular influence in how humans connect to the …

Analysis Of An Sirs Age-Structured Epidemic Model With Vaccination And Vertical Transmission Of Disease, Mohammed El-Doma

Applications and Applied Mathematics: An International Journal (AAM)

An SIRS age-structured epidemic model for a vertically as well as horizontally transmitted disease under vaccination is investigated when the fertility, mortality and removal rates depend on age and the force of infection of proportionate mixing assumption type, and vaccination wanes over time. We prove the existence and uniqueness of solution to the model equations, and show that solutions of the model equations depend continuously on the initial age-distributions. Furthermore, we determine the steady states and obtain an explicitly computable threshold condition, in terms of the demographic and epidemiological parameters of the model; we then study the stability of the …

Low Birth Weight, Very Low Birth Weight And Infant Mortality In San Bernardino County : A Secondary Analysis Of Maternal Factors, Rebecca D. Nanyonjo

Loma Linda University Electronic Theses, Dissertations & Projects

Purpose: National and state infant mortality rates have slowly declined over the last several years. Despite this reduction, San Bernardino County still has one of the highest infant mortality rates in California and racial disparities between Black and White infants not only persist but continue to widen. These disparities remain at the forefront of concern. Healthy People 2010 target objectives have yet to be reached, while national and state proposed plans have supported the statement that a community's largest health problem is initiated by its infant mortality. The purpose of this study was to investigate maternal factors through use of …

Semiparametric Latent Variable Regression Models For Spatio-Temporal Modeling Of Mobile Source Particles In The Greater Boston Area, Alexandros Gryparis, Brent A. Coull, Joel Schwartz, Helen H. Suh

Harvard University Biostatistics Working Paper Series

Traffic particle concentrations show considerable spatial variability within a metropolitan area. We consider latent variable semiparametric regression models for modeling the spatial and temporal variability of black carbon and elemental carbon concentrations in the greater Boston area. Measurements of these pollutants, which are markers of traffic particles, were obtained from several individual exposure studies conducted at specific household locations as well as 15 ambient monitoring sites in the city. The models allow for both flexible, nonlinear effects of covariates and for unexplained spatial and temporal variability in exposure. In addition, the different individual exposure studies recorded different surrogates of traffic …

Reliability, Effect Size, And Responsiveness And Intraclass Correlation Of Health Status Measures Used In Randomized And Cluster-Randomized Trials, Paula Diehr, Lu Chen, Donald L. Patrick, Ziding Feng, Yutaka Yasui

UW Biostatistics Working Paper Series

Background: New health status instruments are described by psychometric properties, such as Reliability, Effect Size, and Responsiveness. For cluster-randomized trials, another important statistic is the Intraclass Correlation for the instrument within clusters. Studies using better instruments can be performed with smaller sample sizes, but better instruments may be more expensive in terms of dollars, lost opportunities, or poorer data quality due to the response burden of longer instruments. Investigators often need to estimate the psychometric properties of a new instrument, or of an established instrument in a new setting. Optimal sample sizes for estimating these properties have not been studied …

Different Public Health Interventions Have Varying Effects, Paula Diehr, Anne B. Newman, Liming Cai, Ann Derleth

UW Biostatistics Working Paper Series

Objective: To compare performance of one-time health interventions to those that change the probability of transitioning from one health state to another. Study Design and Setting: We used multi-state life table methods to estimate the impact of eight types of interventions on several outcomes. Results: In a cohort beginning at age 65, curing all the sick persons at baseline would increase life expectancy by 0.23 years and increase years of healthy life by .54 years. An equal amount of improvement could be obtained with a 12% decrease in the probability of getting sick, a 16% increase in the probability of …

Gpnn: Power Studies And Applications Of A Neural Network Method For Detecting Gene-Gene Interactions In Studies Of Human Disease, Alison A. Motsinger, Stephen L. Lee, George Mellick, Marylyn D. Ritchie

Dartmouth Scholarship

The identification and characterization of genes that influence the risk of common, complex multifactorial disease primarily through interactions with other genes and environmental factors remains a statistical and computational challenge in genetic epidemiology. We have previously introduced a genetic programming optimized neural network (GPNN) as a method for optimizing the architecture of a neural network to improve the identification of gene combinations associated with disease risk. The goal of this study was to evaluate the power of GPNN for identifying high-order gene-gene interactions. We were also interested in applying GPNN to a real data analysis in Parkinson's disease.

Cyclosporin Versus Tacrolimus For Liver Transplanted Patients, Elizabeth Haddad, Vivian Mcalister, Elizabeth Renouf, Richard Malthaner, Mette S. Kjaer, Lise Lotte Gluud

Surgery Publications

A systematic review of randomized clinical trials (RCT) was undertaken to evaluate the beneficial and harmful effects of immunosuppression with cyclosporin versus tacrolimus for liver transplanted patients. MEDLINE, EMBASE, Cochrane Central and Hepato-Biliary Group Controlled Trials Registers were searched. Using fixed and random effects model, relative risk (RR), values <1 favoring>tacrolimus, with 95% confidence intervals (CI) were calculated. Of 717 potentially relevant references, 16 RCTs were eligible for inclusion. Mortality and graft loss at 1 year were significantly reduced in tacrolimus-treated recipients (Death: RR 0.85, 95% CI 0.73-0.99; graft loss: RR 0.73, 95% CI 0.61-0.86). Tacrolimus reduced the number of recipients …

Science-Based Organic Farming 2006: Toward Local And Secure Food Systems, Charles A. Francis, Katja Koehler-Cole, Twyla Hansen, Peter Skelton

Publications from the Center for Applied Rural Innovation (CARI)

Organic farming includes growing food and fiber—animals, agronomic crops, horticultural fruits and vegetables, related products—as one dynamic and rapidly evolving component of our complex U.S. food system. Even as more farmers are moving toward organic certification and participation in an environmentally sound and economically lucrative market, questions arise about the long-term social impacts and sustainability of a set of practices that has gone from a movement to an industry. Consolidations in the organic trade have brought multinational corporations to the table, as they have observed a grassroots activity that has grown by 20% per year for the past two decades, …

Importing Extended Producer Responsibility For Electronic Equipment Into The United States, Chad Raphael, Ted Smith

Communication

Extended Producer Responsibility (EPR) is a policy approach that holds manufacturers accountable for the full costs of their products at every stage in their life cycle. EPR typically involves requiring that producers take back their products at the end of their useful lives, or pay a recycling contractor to do so, thereby internalizing the costs of recycling or disposal in a manufacturer’s bottom line. When companies know that they will bear the costs of product return and recycling, they are more likely to redesign their products for easier and safer handling at each step in the life cycle. This approach …

Horizontal Subsurface Flow Constructed Wetlands For On-Site Wastewater Treatment, Boyd C. Hoddinott

Master of Public Health Program Student Publications

Horizontal subsurface flow constructed wetlands (SSFCWs) are being used worldwide to treat wastewater from a variety of sources. An extensive literature review was conducted to update the current state of scientific knowledge on the performance of SSFCWs for domestic wastewater treatment. This review documented good treatment efficiency for the five commonly measured parameters (TSS, BOD, nitrogen, phosphorus, and fecal coliforms).

An attempt at a Meta analysis turned up a myriad of problems preventing a proper statistical review. These include lack of adherence to standard methods for effluent analysis, varying metrics for reporting treatment efficiency, variability in the nitrogen species which …

Development Of Dose Coefficients For Radionuclides Produced In Spallation Targets, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

Dose coefficients permit simple determination of radiation dose associated with various exposure scenarios, and ultimately permit radiation safety personnel to assess the health risks to workers in a nuclear facility. Specifically, radiation safety personnel use dose coefficients to determine the radiation dose incurred to a tissue or organ system from a given exposure. These parameters are often expressed in terms of Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs).

The research consortium comprised of representatives from several universities and national laboratories has successfully generated internal and external dose conversion coefficients for twenty radionuclides produced in spallation neutron sources. …

Spatial Autocorrelation Of Deer-Vehicle Accidents In Vigo County, J. Scott Horn

All-Inclusive List of Electronic Theses and Dissertations

Deer-vehicle accidents (DV As) are a problem in many areas. They cause millions of dollars in property damage, personal injury, and loss of life each year. This thesis examines whether DVAs in Vigo County, Indiana during the year 2000 were spatially autocorrelated; and whether DV As selected by deer habitat were spatially autocorrelated. Specifically using Moran's I to test for spatial autocorrelation this study determined if and to what degree spatial autocorrelation existed among these DVAs. A Moran's I value of .0023 shows that the accidents occurred randomly. These DV A data were then used to plot a map which …

Chaotic Desynchronization Of Multistrain Diseases, Ira Schwartz, Leah Shaw, Derek Cummings, Lora Billings, Marie Mccrary, Donald Burke

Department of Mathematics Faculty Scholarship and Creative Works

Multistrain diseases are diseases that consist of several strains, or serotypes. The serotypes may interact by antibody-dependent enhancement rADE, in which infection with a single serotype is asymptomatic, but infection with a second serotype leads to serious illness accompanied by greater infectivity. It has been observed from serotype data of dengue hemorrhagic fever that outbreaks of the four serotypes occur asynchronously. Both autonomous and seasonally driven outbreaks were studied in a model containing ADE. For sufficiently small ADE, the number of infectives of each serotype synchronizes, with outbreaks occurring in phase. When the ADE increases past a threshold, the system …

Population Intervention Models In Causal Inference, Alan E. Hubbard, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Marginal structural models (MSM) provide a powerful tool for estimating the causal effect of a] treatment variable or risk variable on the distribution of a disease in a population. These models, as originally introduced by Robins (e.g., Robins (2000a), Robins (2000b), van der Laan and Robins (2002)), model the marginal distributions of treatment-specific counterfactual outcomes, possibly conditional on a subset of the baseline covariates, and its dependence on treatment. Marginal structural models are particularly useful in the context of longitudinal data structures, in which each subject's treatment and covariate history are measured over time, and an outcome is recorded at …

Gauss-Seidel Estimation Of Generalized Linear Mixed Models With Application To Poisson Modeling Of Spatially Varying Disease Rates, Subharup Guha, Louise Ryan

Harvard University Biostatistics Working Paper Series

Generalized linear mixed models (GLMMs) provide an elegant framework for the analysis of correlated data. Due to the non-closed form of the likelihood, GLMMs are often fit by computational procedures like penalized quasi-likelihood (PQL). Special cases of these models are generalized linear models (GLMs), which are often fit using algorithms like iterative weighted least squares (IWLS). High computational costs and memory space constraints often make it difficult to apply these iterative procedures to data sets with very large number of cases.

This paper proposes a computationally efficient strategy based on the Gauss-Seidel algorithm that iteratively fits sub-models of the GLMM …

Computational Techniques For Spatial Logistic Regression With Large Datasets, Christopher J. Paciorek, Louise Ryan

Harvard University Biostatistics Working Paper Series

In epidemiological work, outcomes are frequently non-normal, sample sizes may be large, and effects are often small. To relate health outcomes to geographic risk factors, fast and powerful methods for fitting spatial models, particularly for non-normal data, are required. We focus on binary outcomes, with the risk surface a smooth function of space. We compare penalized likelihood models, including the penalized quasi-likelihood (PQL) approach, and Bayesian models based on fit, speed, and ease of implementation.

A Bayesian model using a spectral basis representation of the spatial surface provides the best tradeoff of sensitivity and specificity in simulations, detecting real spatial …

Is The Number Of Sick Persons In A Cohort Constant Over Time?, Paula Diehr, Ann Derleth, Anne Newman, Liming Cai

UW Biostatistics Working Paper Series

Objectives: To estimate the number of persons in a cohort who are sick, over time.

Methods: We calculated the number of sick persons in the Cardiovascular Health Study (CHS), a cohort study of older adults followed up to 14 years, using eight definitions of “healthy” and “sick”. We projected the number in each health state over time for a birth cohort.

Results: The number of sick persons in CHS was approximately constant for 14 years, for all definitions of “sick”. The estimated number of sick persons in the birth cohort was approximately constant from ages 55-75, after which it decreased. …

A Nonstationary Negative Binomial Time Series With Time-Dependent Covariates: Enterococcus Counts In Boston Harbor, E. Andres Houseman, Brent Coull, James P. Shine

Harvard University Biostatistics Working Paper Series

Boston Harbor has had a history of poor water quality, including contamination by enteric pathogens. We conduct a statistical analysis of data collected by the Massachusetts Water Resources Authority (MWRA) between 1996 and 2002 to evaluate the effects of court-mandated improvements in sewage treatment. Motivated by the ineffectiveness of standard Poisson mixture models and their zero-inflated counterparts, we propose a new negative binomial model for time series of Enterococcus counts in Boston Harbor, where nonstationarity and autocorrelation are modeled using a nonparametric smooth function of time in the predictor. Without further restrictions, this function is not identifiable in the presence …

Direct Effect Models, Mark J. Van Der Laan, Maya L. Petersen

U.C. Berkeley Division of Biostatistics Working Paper Series

The causal effect of a treatment on an outcome is generally mediated by several intermediate variables. Estimation of the component of the causal effect of a treatment that is mediated by a given intermediate variable (the indirect effect of the treatment), and the component that is not mediated by that intermediate variable (the direct effect of the treatment) is often relevant to mechanistic understanding and to the design of clinical and public health interventions. Under the assumption of no-unmeasured confounders for treatment and the intermediate variable, Robins & Greenland (1992) define an individual direct effect as the counterfactual effect of …

Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources Quarterly Progress Report 4/01/05 – 6/30/05, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

The research consortium comprised of representatives from several universities and national laboratories has successfully generated internal and external dose conversion coefficients for twenty radionuclides produced in spallation neutron sources. These dose coefficients fill data gaps exist in Federal Guide Report No. 11 and in Publications 68 and 72 of the International Commission on Radiological Protection (ICRP), and two articles containing the data have been accepted for publication in the Journal of Health Physics. Currently, more nuclear data is needed for the rare radionuclides produced from a mercury target. While attempting to develop a workable plan to acquire this missing data, …

Attributable Risk Function In The Proportional Hazards Model, Ying Qing Chen, Chengcheng Hu, Yan Wang

UW Biostatistics Working Paper Series

As an epidemiological parameter, the population attributable fraction is an important measure to quantify the public health attributable risk of an exposure to morbidity and mortality. In this article, we extend this parameter to the attributable fraction function in survival analysis of time-to-event outcomes, and further establish its estimation and inference procedures based on the widely used proportional hazards models. Numerical examples and simulations studies are presented to validate and demonstrate the proposed methods.

Exposure Assessment Of Mercury In Fish From Kentucky Surface Waters, Najla Gubari

Masters Theses & Specialist Projects

Consumption of fish contaminated with mercury is the primary exposure pathway by which humans are exposed to mercury. Mercury is known to be a neurological toxin that can cause attention and language deficits, impaired memory, and impaired visual and motor function, especially in children under the age of six. In addition, mercury exposure can lead to other health problems in adults, such as damage to the kidney and increased risk of coronary heart disease. This study assesses the exposure to mercury through consumption of fish from Kentucky surface waters. The exposure assessment is based on data collected by the Kentucky …

Relationships Between Environmental Factors And Fungi On Occupants' Perceptions Of Indoor Air Quality, Monica Rodriguez

Masters Theses & Specialist Projects

In recent decades, concerns about potential health effects resulting from exposure to contaminants that cause indoor air pollution have dramatically increased. The purpose of this study was to assess the indoor air quality of three buildings at Western Kentucky University and to examine and characterize indoor levels of basic comfort parameters, carbon dioxide, and fungi as well as occupants' perceptions of poor indoor air quality and the role of fungi on reported health symptoms. The three buildings included in the study were: Tate Page Hall (TPH), Jones Jagger Hall (JJH) and Science and Technology Hall (STH). Fifty-three questionnaires were completed …

Environmental Factors In Autoimmunity: Assessment Of Immunotoxicity Of Phthalates In The Induction Of Lupus-Type Anti-Dna Antibodies, So-Yon Lim

All-Inclusive List of Electronic Theses and Dissertations

Objectives: Little is known of the role of specific environmental factors in promoting autoimmune disorders such as systemic lupus erythematosus (SLE). The broad objective of this study was to address how exposure to phthalates, common environmental factors m foods, and biomedical devices could affect the immune functions of resistant and autoimmune-prone mice. Methods: The environmental chemical model used in this study is phthalates, which are widely used in various forms and readily occur during day-to-day human contacts. Groups of nonautoimmune-prone (BALB/c, DBA/2 and C57BL/6) and susceptible (NZB, NZB/W Fl) mice were immunized with phthalates ( ortho, meta and para) conjugated …

Causal Inference In Longitudinal Studies With History-Restricted Marginal Structural Models, Romain Neugebauer, Mark J. Van Der Laan, Ira B. Tager

U.C. Berkeley Division of Biostatistics Working Paper Series

Causal Inference based on Marginal Structural Models (MSMs) is particularly attractive to subject-matter investigators because MSM parameters provide explicit representations of causal effects. We introduce History-Restricted Marginal Structural Models (HRMSMs) for longitudinal data for the purpose of defining causal parameters which may often be better suited for Public Health research. This new class of MSMs allows investigators to analyze the causal effect of a treatment on an outcome based on a fixed, shorter and user-specified history of exposure compared to MSMs. By default, the latter represents the treatment causal effect of interest based on a treatment history defined by the …

Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources Quarterly Progress Report 1/1/05 – 3/31/05, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

The research consortium comprised of representatives from several universities and national laboratories has successfully generated internal and external dose conversion coefficients for twenty radionuclides produced in spallation neutron sources. In addition, the group has identified twenty radionuclide that are missing electron capture files and eighteen additional radionuclides missing substantial physical data. The goal for the current year is to develop a methodology that will allow for producing the dose coefficients for these radionuclides with missing data. Methods to obtain these data are being investigated.

Insights Into Latent Class Analysis, Margaret S. Pepe, Holly Janes

UW Biostatistics Working Paper Series

Latent class analysis is a popular statistical technique for estimating disease prevalence and test sensitivity and specificity. It is used when a gold standard assessment of disease is not available but results of multiple imperfect tests are. We derive analytic expressions for the parameter estimates in terms of the raw data, under the conditional independence assumption. These expressions indicate explicitly how observed two- and three-way associations between test results are used to infer disease prevalence and test operating characteristics. Although reasonable if the conditional independence model holds, the estimators have no basis when it fails. We therefore caution against using …

Standardizing Markers To Evaluate And Compare Their Performances, Margaret S. Pepe, Gary M. Longton

UW Biostatistics Working Paper Series

Introduction: Markers that purport to distinguish subjects with a condition from those without a condition must be evaluated rigorously for their classification accuracy. A single approach to statistically evaluating and comparing markers is not yet established.

Methods: We suggest a standardization that uses the marker distribution in unaffected subjects as a reference. For an affected subject with marker value Y, the standardized placement value is the proportion of unaffected subjects with marker values that exceed Y.

Results: We apply the standardization to two illustrative datasets. In patients with pancreatic cancer placement values calculated for the CA 19-9 marker are smaller …

Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang, Gary M. Longton

UW Biostatistics Working Paper Series

No single biomarker for cancer is considered adequately sensitive and specific for cancer screening. It is expected that the results of multiple markers will need to be combined in order to yield adequately accurate classification. Typically the objective function that is optimized for combining markers is the likelihood function. In this paper we consider an alternative objective function -- the area under the empirical receiver operating characteristic curve (AUC). We note that it yields consistent estimates of parameters in a generalized linear model for the risk score but does not require specifying the link function. Like logistic regression it yields …