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Internally ratiometric fluorescent sensors for evaluation of intracellular GTP levels and distribution
No full textCharacterizing the contribution of residential phthalate dust concentrations to internal phthalate dose in the US population: an updated systematic review & meta-analysis
No full textObjectives: Phthalates are prevalent chemical substances that have been linked to endocrine disruption, reproductive disorders, and other adverse health effects. Although exposure to phthalates is widespread, few studies provide information on the relative contributions of exposure sources and routes of exposure. The objective of this systematic review and meta-analysis is to quantify the contribution of phthalates and phthalate alternatives in residential dust to internal human dose in the US general population.
Methods: This review updates a pre-existing systematic review and meta-analysis published in 2015. It includes 12 studies published between January 2000 and April 2022 identified from Web of Science and PubMed using a predetermined search strategy. Pooled weighted median phthalate and phthalate alternative dust concentrations were determined from the studies included in our literature review. The phthalate and phthalate alternative dust concentrations were then used to calculate daily intake rates. Separately, using a reverse dosimetry model, the daily intake rate representing total phthalate and phthalate alternative internal dose was estimated from urinary phthalate metabolite concentrations measured in the 2017-2018 National Health and Nutrition Examination Survey (NHANES). The daily intake rates predicted from the indoor dust (systematic review/meta-analysis) and the urinary metabolites (NHANES) were then compared to drive the percent contribution of phthalates and phthalate alternatives measured in residential dust to internal dose. A summary showing the potential human health hazards associated with the measured chemical substances was compiled to provide context for risk.
Results: ATBC (phthalate alternative) had the highest dust concentrations (systematic review/meta-analysis) while DEHTP (phthalate alternative) had the highest internal exposure level in children and adults (NHANES). Dust had a greater contribution to the internal phthalate and phthalate alternative concentration levels of children than adults when all exposure pathways (i.e., dust ingestion (direct), inhalation (indirect), and dermal absorption from air (indirect)) were considered. It was also observed that the dust ingestion pathway contributed significantly to the overall dust intake rate for high-molecular weight (HMW) phthalates. Conversely, the inhalation and dermal absorption from air exposure pathways were more significant for low-molecular weight (LMW) phthalates. The relative contribution of dust to the overall intake of the chemical substances varied depending on the physio-chemical characteristics, with dust being a more important contributor for LMW phthalates such as DEP and BBP.
Conclusion: The relative contribution of dust to overall internal exposure of individuals is greater for LMW than HMW phthalates. This is linked to the increased likelihood of LMW phthalates partitioning from dust to indoor air, which makes the indirect contribution of dust to internal phthalate exposure greater than its direct contribution
Can Right-Sizing the Use of Virtual Care Improve Access to Equitable, Patient-Centered Care for Women Veterans?
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Contemporary percutaneous treatment of infrapopliteal arterial disease: a practical approach.
No full textC-2 neurectomy during atlantoaxial instrumented fusion in the elderly: patient satisfaction and surgical outcome.
No full textObjectiveThe originally described technique of atlantoaxial stabilization using C-1 lateral mass and C-2 pars screws includes a C-2 neurectomy to provide adequate hemostasis and visualization for screw placement, enable adequate joint decortication and arthrodesis, and prevent new-onset postoperative C-2 neuralgia. However, inclusion of a C-2 neurectomy for this procedure remains controversial, likely due in part to a lack of studies that have specifically addressed whether it affects patient outcome. The authors' objective was to assess the surgical and clinical impact of routine C-2 neurectomy performed with C1-2 segmental instrumented arthrodesis in a consecutive series of elderly patients with C1-2 instability.MethodsForty-four consecutive patients (mean age 71 years) underwent C1-2 instrumented fusion, including C-1 lateral mass screw insertion. Bilateral C-2 neurectomies were performed. Standardized clinical assessments were performed both pre- and postoperatively. Numbness or discomfort in a C-2 distribution was documented at follow-up. Fusion was assessed using the Lenke fusion grade.ResultsAmong all 44 patients, mean blood loss was 200 ml (range 100-350 ml) and mean operative time was 129 minutes (range 87-240 minutes). There were no intraoperative complications, and no patients reported new postoperative onset or worsening of C-2 neuralgia postoperatively. Outcomes for the 30 patients with a minimum 13-month follow-up (range 13-72 months) were assessed. At a mean follow-up of 36 months, Nurick grade and pain numeric rating scale scores improved from 3.7 to 1.0 (p ConclusionsIn this series of C1-2 instrumented arthrodesis in elderly patients, excellent fusion rates were achieved, and patient satisfaction was not negatively affected by C-2 neurectomy. In the authors' experience, C-2 neurectomy enhanced surgical exposure of the C1-2 joint, thereby facilitating hemostasis, placement of instrumentation, and decortication of the joint space for arthrodesis. Importantly, with C-2 neurectomy in the present series, no cases of new onset postoperative C-2 neuralgia occurred, in contrast to a growing number of reports in the literature documenting new-onset C-2 neuralgia without C-2 neurectomy. On the contrary, 80% of patients in the present series had preoperative occipital neuralgia and in all of these patients this neuralgia was relieved following C1-2 instrumented arthrodesis with C-2 neurectomy
Geometric Methods for Point Estimation
No full textThe focus of this dissertation is on geometric aspects of point estimation problems. In the first half of this work, we examine the estimation of location parameters for non-Euclidean data that lies in a known manifold or metric space. Ideas from statistical decision theory motivate the construction of new estimators for location parameters. The second half of this work explores information geometric aspects of covariance matrix estimation. In a regular statistical model the Fisher information metric endows the parameter space with a Riemannian manifold structure. Parameter estimation can therefore also be viewed as problem in non-Euclidean data analysis. Chapter 2 introduces and formalizes the problem of estimating Frechet mean location parameters for metric space valued data. We highlight the importance of the isometry group of distance preserving transformations, and how this group interacts with Frechet means. Pitman's minimum risk equivariant estimator for location models in Euclidean space is generalized to manifold settings, where we discuss aspects of the performance and computation of this minimum risk equivariant estimator. Turning from equivariant estimation to shrinkage estimation, Chapter 3 introduces a shrinkage estimator for Frechet means that is inspired by Stein's estimator. This estimator utilizes metric space geodesics to shrink an estimate towards a pre-specified, shrinkage point. It is shown that the performance of this geodesic James-Stein estimator depends on the curvature of the underlying metric space, where shrinkage is especially beneficial in non-positively curved spaces.Chapter 4 discusses shrinkage estimation for covariance matrices that approximately have a Kronecker product structure. The idea of geodesic shrinkage can be applied with respect to alpha-geodesics that arise from the information geometry of a statistical model. These alpha-geodesics also lead to interpretable parameter space decompositions. In a Wishart model we propose an empirical Bayes procedure for estimating approximate Kronecker covariance matrices; a procedure which can be viewed as shrinkage along (-1)-geodesics.The last chapter of this work further discusses information geometric aspects of covariance estimation, with a view towards asymptotic efficiency. The asymptotic performance of the partial trace estimator for a Kronecker covariance is contrasted with the maximum likelihood estimator. A correction to the partial trace estimator is proposed which is both asymptotically efficient and simple to compute. </p
Determining Living Shoreline Distribution in North Carolina: A Mixed Methods Study
No full textCoastal landowners in North Carolina have traditionally deployed hardened structures like seawalls and bulkheads to protect coastal development from erosion and inundation. However, living shorelines have emerged in recent decades as a more ecologically integrated solution, incorporating natural and human-made components to address erosion. To date, few studies have used geospatial tools to understand the deterministic factors driving the distribution of living shorelines in North Carolina. We consider how the distribution of living shorelines varies with a community’s socioeconomic demographics, proximity to enabling institutions, and vulnerability to coastal inundation. We explore the barriers that homeowners face in acquiring a living shoreline and the perceptions that inform their decisions. Using a mixed methods approach, our study uses geospatial tools, decision-tree analysis, and semi-structured interviews with coastal landowners to distill the primary determinants governing the distribution of living shorelines across North Carolina’s coast. We find that among coastal census tracts in North Carolina, the distribution of living shorelines has a significant negative correlation with the percent of the population living in poverty, suggesting that income constrains implementation of these projects. In contrast, vulnerability to coastal inundation and proximity to enabling institutions are not predictive of living shoreline distribution. Interviews elucidate that access to information and relevant networks, capacity to navigate the installation process, and ability to pay informed many homeowners’ decisions to install a living shoreline. Taken together, our findings shed light on the need to consider equity and vulnerability in shoreline protection and coastal restoration
Advanced Topics in Introductory Statistics
No full textIt is now common practice in many scientific disciplines to collect large amounts of experimental or observational data in the course of a research study. The abundance of such data creates a circumstance in which even simply posed research questions may, or sometimes must, be answered using multivariate datasets with complex structure. Introductory-level statistical tools familiar to practitioners may be applied to these types of data, but inference will either be sub-optimal or invalid if properties of the data violate the assumptions made by these statistical procedures. In this thesis, we provide examples of how basic statistical procedures may be adapted to suit the complexity of modern datasets while preserving the simplicity of low-dimensional parametric models. In the context of genomics studies, we propose a frequentist-assisted-by-Bayes (FAB) method for conducting hypothesis tests for the means of normal models when auxiliary information about the means is available. If the auxiliary information accurately describes the means, then the proposed FAB hypothesis tests may be more powerful than the corresponding classical -tests. If the information is not accurate, then the FAB tests retain type-I error control. For multivariate financial and climatological data, we develop a semiparametric model in order to characterize the dependence between two sets of random variables. Our approach is inspired by a multivariate notion of the sample rank and extends classical concepts such as canonical correlation analysis (CCA) and the Gaussian copula model. The proposed model allows for the analysis of multivariate dependence between variable sets with arbitrary marginal distributions. Motivated by fluorescence spectroscopy data collected from sites along the Neuse River, we also propose a least squares estimator for quantifying the contribution of various land-use sources to the water quality of the river. The estimator can be computed quickly relative to estimators derived using parallel factor analysis (PARAFAC) and it performs favorably in two source apportionment tasks.</p