Deep phenotyping of cardiac function in heart transplant patients using cardiovascular system models

Heart transplant patients are followed with periodic right heart catheterizations (RHCs) to identify post‐transplant complications and guide treatment. Post‐transplant positive outcomes are associated with a steady reduction of right ventricular and pulmonary arterial pressures, toward normal levels of right‐side pressure (about 20 mmHg) measured by RHC. This study shows that more information about patient progression is obtained by combining standard RHC measures with mechanistic computational cardiovascular system models. The purpose of this study is twofold: to understand how cardiovascular system models can be used to represent a patient’s cardiovascular state, and to use these models to track post‐transplant recovery and outcome. To obtain reliable parameter estimates comparable within and across datasets, we use sensitivity analysis, parameter subset selection, and optimization to determine patient‐specific mechanistic parameters that can be reliably extracted from the RHC data. Patient‐specific models are identified for 10 patients from their first post‐transplant RHC, and longitudinal analysis is carried out for five patients. Results of the sensitivity analysis and subset selection show that we can reliably estimate seven non‐measurable quantities; namely, ventricular diastolic relaxation, systemic resistance, pulmonary venous elastance, pulmonary resistance, pulmonary arterial elastance, pulmonary valve resistance and systemic arterial elastance. Changes in parameters and predicted cardiovascular function post‐transplant are used to evaluate the cardiovascular state during recovery of five patients. Of these five patients, only one showed inconsistent trends during recovery in ventricular pressure–volume relationships and power output. At the four‐year post‐transplant time point this patient exhibited biventricular failure along with graft dysfunction while the remaining four exhibited no cardiovascular complications.Key pointsRight heart catheterization data from clinical records of heart transplant patients are used to identify patient‐specific models of the cardiovascular system.These patient‐specific cardiovascular models represent a snapshot of cardiovascular function at a given post‐transplant recovery time point.This approach is used to describe cardiac function in 10 heart transplant patients, five of which had multiple right heart catheterizations allowing an assessment of cardiac function over time.These patient‐specific models are used to predict cardiovascular function in the form of right and left ventricular pressure‐volume loops and ventricular power, an important metric in the clinical assessment of cardiac function.Outcomes for the longitudinally tracked patients show that our approach was able to identify the one patient from the group of five that exhibited post‐transplant cardiovascular complications.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156242/2/tjp14120.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156242/1/tjp14120_am.pd

Deep phenotyping of cardiac function in heart transplant patients using cardiovascular systems models

Heart transplant patients are followed with periodic right heart catheterizations (RHCs) to identify post-transplant complications and guide treatment. Post-transplant positive outcomes are associated with a steady reduction of right ventricular and pulmonary arterial pressures, toward normal levels of right-side pressure (about 20mmHg) measured by RHC. This study shows more information about patient progression is obtained by combining standard RHC measures with mechanistic computational cardiovascular systems models. This study shows: to understand how cardiovascular system models can be used to represent a patient's cardiovascular state, and to use these models to track post-transplant recovery and outcome. To obtain reliable parameter estimates comparable within and across datasets, we use sensitivity analysis, parameter subset selection, and optimization to determine patient specific mechanistic parameter that can be reliably extracted from the RHC data. Patient-specific models are identified for ten patients from their first post-transplant RHC and longitudinal analysis is done for five patients. Results of sensitivity analysis and subset selection show we can reliably estimate seven non-measurable quantities including ventricular diastolic relaxation, systemic resistance, pulmonary venous elastance, pulmonary resistance, pulmonary arterial elastance, pulmonary valve resistance and systemic arterial elastance. Changes in parameters and predicted cardiovascular function post-transplant are used to evaluate cardiovascular state during recovery in five patients. Of these five patients, only one patient showed inconsistent trends during recovery in ventricular pressure-volume relationships and power output. At a four-year recovery time point this patient exhibited biventricular failure along with graft dysfunction while the remaining four exhibited no cardiovascular complications.Comment: 53 Pages (including supplement), 9 figures in manuscript, 9 figures in supplemen

A Cross National Study of Golf Tourists’ Satisfaction

The purpose of this study was two-fold: firstly, it was to examine the determinants satisfaction levels of golf tourists and secondly to investigate if these vary across golf tourists’ country of residence. Using data collected through a survey of golf tourists visiting Lisbon (Portugal), attributes directly related to playing golf as well as more generic destination attributes were examined as potential determinants of golf tourists’ satisfaction. The data was analysed in two stages by the means of logistic regression. In stage one, the analysis was based on a representative sample of golf tourists to the region. In the second stage, two separate analyses were undertaken, one examining the satisfaction of Nordic golf tourists and another of British golf tourists (the two main markets for Lisbon). The results indicate that the satisfaction level of golf tourists is influenced by several factors, including those related to perceived quality and value. In addition, the results suggest that satisfaction is influenced by cross-cultural differences. While some determinants were important influences for both the British and the Nordic golfers, other determinants were specific to each country of origin. lytoinvestigateifthesevaryacrossgolftourists’countryofresidence.Using data collectedthroughasurveyofgolftouristsvisitingLisbon(Portugal),attributesdirectlyrelatedto playinggolfaswellasmoregenericdestinationattributeswereexaminedaspotentialdeterminantsof golf tourists’satisfaction.Thedatawasanalysedintwostagesbythemeansoflogisticregression.In stage one,theanalysiswasbasedonarepresentativesampleofgolftouriststotheregion.Inthesecond stage, twoseparateanalyseswereundertaken,oneexaminingthesatisfactionofNordicgolftourists and anotherofBritishgolftourists(thetwomainmarketsforLisbon).Theresultsindicatethatthe satisfactionlevelofgolftouristsisinfluencedbyseveralfactors,includingthoserelatedtoperceived qualityandvalue.Inaddition,theresultssuggestthatsatisfactionisinfluencedbycross-cultural differences.WhilesomedeterminantswereimportantinfluencesforboththeBritishandtheNordic golfers,otherdeterminantswerespecifictoeachcountryoforigin

General Structural Results for Potts Model Partition Functions on Lattice Strips

We present a set of general results on structural features of the $q$-state Potts model partition function $Z(G,q,v)$ for arbitrary $q$ and temperature Boltzmann variable $v$ for various lattice strips of arbitrarily great width $L_y$ vertices and length $L_x$ vertices, including (i) cyclic and M\"obius strips of the square and triangular lattice, and (ii) self-dual cyclic strips of the square lattice. We also present an exact solution for the chromatic polynomial for the cyclic and M\"obius strips of the square lattice with width $L_y=5$ (the greatest width for which an exact solution has been obtained so far for these families). In the $L_x \to \infty$ limit, we calculate the ground-state degeneracy per site, $W(q)$ and determine the boundary ${\cal B}$ across which $W(q)$ is singular in the complex $q$ plane.Comment: 49 pages, latex, four postscript figure

Monitoring General Linear Profiles When Random Errors Have Contaminated Normal Distributions

[[abstract]]We consider the quality of a process which can be characterized by a general linear profile where the random error has a contaminated normal distribution. On the basis of trimmed least squares estimation, new control charts for monitoring the coefficient parameters and/or the error variance of the profile are proposed. Simulation studies show that the proposed control charts outperform the existing competitors under such a profile. An example from manufacturing facility is used to illustrate the applicability of the proposed charts.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]電子

Current Trends in the Epidemiological and Pathological Characteristics of Gastrointestinal Stromal Tumors in Korea, 2003-2004

Despite remarkable progress in understanding and treating gastrointestinal stromal tumors (GISTs) during the past two decades, the pathological characteristics of GISTs have not been made clear yet. Furthermore, concrete diagnostic criteria of malignant GISTs are still uncertain. We collected pathology reports of 1,227 GISTs from 38 hospitals in Korea between 2003 and 2004 and evaluated the efficacy of the NIH and AFIP classification schemes as well as the prognostic factors among pathologic findings. The incidence of GISTs in Korea is about 1.6 to 2.2 patients per 100,000. Extra-gastrointestinal GISTs (10.1%) are more common in Korea than in Western countries. In univariate analysis, gender, age, tumor location, size, mitosis, tumor necrosis, vascular and mucosal invasions, histologic type, CD34 and s-100 protein expression, and classifications by the NIH and AFIP criteria were found to be significantly correlated with patient's survival. However, the primary tumor location, stage and classification of the AFIP criteria were prognostically significant in predicting patient's survival in multivariate analysis. The GIST classification based on original tumor location, size, and mitosis is more efficient than the NIH criteria in predicting patient's survival, but the mechanism still needs to be clarified through future studies

Modelling CO formation in the turbulent interstellar medium

We present results from high-resolution three-dimensional simulations of turbulent interstellar gas that self-consistently follow its coupled thermal, chemical and dynamical evolution, with a particular focus on the formation and destruction of H2 and CO. We quantify the formation timescales for H2 and CO in physical conditions corresponding to those found in nearby giant molecular clouds, and show that both species form rapidly, with chemical timescales that are comparable to the dynamical timescale of the gas. We also investigate the spatial distributions of H2 and CO, and how they relate to the underlying gas distribution. We show that H2 is a good tracer of the gas distribution, but that the relationship between CO abundance and gas density is more complex. The CO abundance is not well-correlated with either the gas number density n or the visual extinction A_V: both have a large influence on the CO abundance, but the inhomogeneous nature of the density field produced by the turbulence means that n and A_V are only poorly correlated. There is a large scatter in A_V, and hence CO abundance, for gas with any particular density, and similarly a large scatter in density and CO abundance for gas with any particular visual extinction. This will have important consequences for the interpretation of the CO emission observed from real molecular clouds. Finally, we also examine the temperature structure of the simulated gas. We show that the molecular gas is not isothermal. Most of it has a temperature in the range of 10--20 K, but there is also a significant fraction of warmer gas, located in low-extinction regions where photoelectric heating remains effective.Comment: 37 pages, 15 figures; minor revisions, matches version accepted by MNRA

Transfer Matrices and Partition-Function Zeros for Antiferromagnetic Potts Models. V. Further Results for the Square-Lattice Chromatic Polynomial

We derive some new structural results for the transfer matrix of square-lattice Potts models with free and cylindrical boundary conditions. In particular, we obtain explicit closed-form expressions for the dominant (at large |q|) diagonal entry in the transfer matrix, for arbitrary widths m, as the solution of a special one-dimensional polymer model. We also obtain the large-q expansion of the bulk and surface (resp. corner) free energies for the zero-temperature antiferromagnet (= chromatic polynomial) through order q^{-47} (resp. q^{-46}). Finally, we compute chromatic roots for strips of widths 9 <= m <= 12 with free boundary conditions and locate roughly the limiting curves.Comment: 111 pages (LaTeX2e). Includes tex file, three sty files, and 19 Postscript figures. Also included are Mathematica files data_CYL.m and data_FREE.m. Many changes from version 1: new material on series expansions and their analysis, and several proofs of previously conjectured results. Final version to be published in J. Stat. Phy

Using funnel plots in public health surveillance

<p>Abstract</p> <p>Background</p> <p>Public health surveillance is often concerned with the analysis of health outcomes over small areas. Funnel plots have been proposed as a useful tool for assessing and visualizing surveillance data, but their full utility has not been appreciated (for example, in the incorporation and interpretation of risk factors).</p> <p>Methods</p> <p>We investigate a way to simultaneously focus funnel plot analyses on direct policy implications while visually incorporating model fit and the effects of risk factors. Health survey data representing modifiable and nonmodifiable risk factors are used in an analysis of 2007 small area motor vehicle mortality rates in Alberta, Canada.</p> <p>Results</p> <p>Small area variations in motor vehicle mortality in Alberta were well explained by the suite of modifiable and nonmodifiable risk factors. Funnel plots of raw rates and of risk adjusted rates lead to different conclusions; the analysis process highlights opportunities for intervention as risk factors are incorporated into the model. Maps based on funnel plot methods identify areas worthy of further investigation.</p> <p>Conclusions</p> <p>Funnel plots provide a useful tool to explore small area data and to routinely incorporate covariate relationships in surveillance analyses. The exploratory process has at each step a direct and useful policy-related result. Dealing thoughtfully with statistical overdispersion is a cornerstone to fully understanding funnel plots.</p

From Profile to Surface Monitoring: SPC for Cylindrical Surfaces Via Gaussian Processes

Quality of machined products is often related to the shapes of surfaces that are constrained by geometric tolerances. In this case, statistical quality monitoring should be used to quickly detect unwanted deviations from the nominal pattern. The majority of the literature has focused on statistical profile monitoring, while there is little research on surface monitoring. This paper faces the challenging task of moving from profile to surface monitoring. To this aim, different parametric approaches and control-charting procedures are presented and compared with reference to a real case study dealing with cylindrical surfaces obtained by lathe turning. In particular, a novel method presented in this paper consists of modeling the manufactured surface via Gaussian processes models and monitoring the deviations of the actual surface from the target pattern estimated in phase I. Regardless of the specific case study in this paper, the proposed approach is general and can be extended to deal with different kinds of surfaces or profiles