The ILR School at Fifty: Voices of the Faculty, Alumni & Friends (Full Text)

A collection of reflections on the first fifty years of the School of Industrial and Labor Relations at Cornell University. Compiled by Robert B. McKersie, J. Gormly Miller, Robert L. Aronson, and Robert R. Julian. Edited by Elaine Gruenfeld Goldberg. It was the hope of the compilers that the reflections contained in this book would both kindle memories of the school and stimulate interest on the part of future generations of ILRies who have not yet shared in its special history. Dedicated to the Memory of J. Gormly Miller, 1914-1995. Copyright 1996 by Cornell University. All rights reserved

Differences in Blood Pressure Levels Among Children by Sociodemographic Status

INTRODUCTION: The American Academy of Pediatrics (AAP) updated its blood pressure (BP) screening guidelines in 2017 to emphasize body weight as a risk factor. We provide contemporary, nationally representative estimates of prevalence of elevated and hypertensive BP among US children and examine sociodemographic prevalence differences, accounting for the influence of weight. METHODS: We used cross-sectional data from children aged 8 to 17 years (N = 5,971; weighted N = 36,612,323) collected from 2011 through 2018 in 4 biennial cycles of the National Health and Nutrition Examination Survey (NHANES). Children\u27s BP was categorized as normal, elevated, or hypertensive. Sociodemographic characteristics included were sex, age, race/ethnicity, family income, and education. Log binomial regression, with and without adjustment for weight (dichotomized at the 85th body mass index percentile), determined prevalence estimates and differences for elevated and hypertensive BPs with 95% CIs. RESULTS: In NHANES data collected from 2011 through 2018, 7.2% (95% CI, 6.3%-8.3%) of US children had elevated BP, and 3.8% (95% CI, 3.3%-4.5%) had hypertensive BP according to 2017 AAP guidelines. Differences in prevalence of weight-adjusted elevated BP indicated higher prevalence among children aged 16 to 17 years compared with children aged 8 to 9 years (prevalence difference, +6.3%; 95% CI, 3.2%-9.4%), among males compared with females (+4.6%; 95% CI, 2.7%-6.4%), and among non-Latino Black children compared with non-Latino White children (+4.0%; 95% CI, 2.2%-5.8%). Crude hypertensive BP prevalence was highest among children aged 8 to 9 years, male children, and Mexican American children. The only difference remaining after weight adjustment was among children aged 8 to 9 years and 13 to 15 years. CONCLUSION: Elevated BP was most prevalent among US children who were older, male, or non-Latino Black. Factors beyond inequalities in body weight may contribute to disparities in elevated BP

Impact of multimorbidity on clinical outcomes in older adults with cardiovascular disease

Objective: To synthesize the current literature on the magnitude and impact of multiple chronic conditions on clinical outcomes, including total in-hospital and post discharge mortality and hospitalizations, in older patients with cardiovascular disease (CVD). Methods: A systematic review was conducted. Four electronic databases and article bibliographies were searched for publications from 2005 to 2015 which assessed the impact of multimorbidity on clinical outcomes in the elderly with CVD. Identified studies were screened using pre-defined criteria for eligibility. Results: Fifteen studies met our inclusion criteria. Multimorbidity was assessed by simple counting of morbidities and by the Charlson and Elixhauser indices. Case-fatality rates ranged from between 13% and 21% for patients with a myocardial infarction. Long-term mortality ranged from 28% to 73% among patients with heart failure, and 24% of patients with heart failure and presenting multimorbidities had at least one readmission during a follow-up period of 17 months. Most of the studies reported a significant association between number of multimorbidities or particular morbidities and the risk of dying, the most frequent morbidities examined were diabetes, chronic kidney disease, anemia, chronic pulmonary disease and dementia/cognitive impairment Conclusions: There are limited data on the magnitude and impact of multimorbidities on clinical outcomes, and even less data on patient centered outcomes among elderly patients with CVD. There are also inconsistencies in the manner by which multimorbidities are assessed; very few studies have approached the “real” complexity of patients with CVD and multimorbidities and how best to manage these high risk patients

Modeling of Damage Initiation and Progression in a SiC/SiC Woven Ceramic Matrix Composite

The goal of an ongoing project at NASA Glenn is to investigate the effects of the complex microstructure of a woven ceramic matrix composite and its variability on the effective properties and the durability of the material. Detailed analysis of these complex microstructures may provide clues for the material scientists who `design the material? or to structural analysts and designers who `design with the material? regarding damage initiation and damage propagation. A model material system, specifically a five-harness satin weave architecture CVI SiC/SiC composite composed of Sylramic-iBN fibers and a SiC matrix, has been analyzed. Specimens of the material were serially sectioned and polished to capture the detailed images of fiber tows, matrix and porosity. Open source analysis tools were used to isolate various constituents and finite elements models were then generated from simplified models of those images. Detailed finite element analyses were performed that examine how the variability in the local microstructure affected the macroscopic behavior as well as the local damage initiation and progression. Results indicate that the locations where damage initiated and propagated is linked to specific microstructural features

Age and sex differences in long-term outcomes following implantable cardioverter-defibrillator placement in contemporary clinical practice: findings from the Cardiovascular Research Network

BACKGROUND: Patient sex and age may influence rates of death after receiving an implantable cardioverter-defibrillator for primary prevention. Differences in outcomes other than mortality and whether these differences vary by heart failure symptoms, etiology, and left ventricular ejection fraction are not well characterized. METHODS AND RESULTS: We studied 2954 patients with left ventricular ejection fraction \u3c /=0.35 undergoing first-time implantable cardioverter-defibrillator for primary prevention within the Cardiovascular Research Network; 769 patients (26%) were women, and 2827 (62%) were aged \u3e 65 years. In a median follow-up of 2.4 years, outcome rates per 1000 patient-years were 109 for death, 438 for hospitalization, and 111 for heart failure hospitalizations. Procedure-related complications occurred in 8.36%. In multivariable models, women had significantly lower risks of death (hazard ratio 0.67, 95% CI 0.56 to 0.80) and heart failure hospitalization (hazard ratio 0.82, 95% CI 0.68 to 0.98) and higher risks for complications (hazard ratio 1.38, 95% CI 1.01 to 1.90) than men; patients aged \u3e 65 years had higher risks of death (hazard ratio 1.55, 95% CI 1.30 to 1.86) and heart failure hospitalization (hazard ratio 1.25, 95% CI 1.05 to 1.49) than younger patients. Age and sex differences were generally consistent in strata according to symptoms, etiology, and severity of left ventricular systolic dysfunction, except the higher risk of complications in women, which differed by New York Heart Association classification (P=0.03 for sex-New York Heart Association interaction), and the risk of heart failure hospitalization in older patients, which differed by etiology of heart failure (P=0.05 for age-etiology interaction). CONCLUSIONS: The burden of adverse outcomes after receipt of an implantable cardioverter-defibrillator for primary prevention is substantial and varies according to patient age and sex. These differences in outcome generally do not vary according to baseline heart failure characteristics

Studies of multiple stellar systems - IV. The triple-lined spectroscopic system Gliese 644

We present a radial-velocity study of the triple-lined system Gliese 644 and derive spectroscopic elements for the inner and outer orbits with periods of 2.9655 and 627 days. We also utilize old visual data, as well as modern speckle and adaptive optics observations, to derive a new astrometric solution for the outer orbit. These two orbits together allow us to derive masses for each of the three components in the system: M_A = 0.410 +/- 0.028 (6.9%), M_Ba = 0.336 +/- 0.016 (4.7%), and $M_Bb = 0.304 +/- 0.014 (4.7%) M_solar. We suggest that the relative inclination of the two orbits is very small. Our individual masses and spectroscopic light ratios for the three M stars in the Gliese 644 system provide three points for the mass-luminosity relation near the bottom of the Main Sequence, where the relation is poorly determined. These three points agree well with theoretical models for solar metallicity and an age of 5 Gyr. Our radial velocities for Gliese 643 and vB 8, two common-proper-motion companions of Gliese 644, support the interpretation that all five M stars are moving together in a physically bound group. We discuss possible scenarios for the formation and evolution of this configuration, such as the formation of all five stars in a sequence of fragmentation events leading directly to the hierarchical configuration now observed, versus formation in a small N cluster with subsequent dynamical evolution into the present hierarchical configuration.Comment: 17 pages, 9 figures, Accepted for publication in MNRA

Investigation of Effects of Material Architecture on the Elastic Response of a Woven Ceramic Matrix Composite

To develop methods for quantifying the effects of the microstructural variations of woven ceramic matrix composites on the effective properties and response of the material, a research program has been undertaken which is described in this paper. In order to characterize and quantify the variations in the microstructure of a five harness satin weave, CVI SiC/SiC, composite material, specimens were serially sectioned and polished to capture images that detailed the fiber tows, matrix, and porosity. Open source quantitative image analysis tools were then used to isolate the constituents and collect relevant statistics such as within ply tow spacing. This information was then used to build two dimensional finite element models that approximated the observed section geometry. With the aid of geometrical models generated by the microstructural characterization process, finite element models were generated and analyses were performed to quantify the effects of the microstructure and its variation on the effective stiffness and areas of stress concentration of the material. The results indicated that the geometry and distribution of the porosity appear to have significant effects on the through-thickness modulus. Similarly, stress concentrations on the outer surface of the composite appear to correlate to regions where the transverse tows are separated by a critical amount

Macro Scale Independently Homogenized Subcells for Modeling Braided Composites

An analytical method has been developed to analyze the impact response of triaxially braided carbon fiber composites, including the penetration velocity and impact damage patterns. In the analytical model, the triaxial braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. Currently, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. To determine the stiffness and strength properties required for the constitutive model, a top-down approach for determining the strength properties is merged with a bottom-up approach for determining the stiffness properties. The top-down portion uses global strengths obtained from macro-scale coupon level testing to characterize the material strengths for each subcell. The bottom-up portion uses micro-scale fiber and matrix stiffness properties to characterize the material stiffness for each subcell. Simulations of quasi-static coupon level tests for several representative composites are conducted along with impact simulations

Modification of a Macromechanical Finite-Element Based Model for Impact Analysis of Triaxially-Braided Composites

A macro level finite element-based model has been developed to simulate the mechanical and impact response of triaxially-braided polymer matrix composites. In the analytical model, the triaxial braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. For the current analytical approach, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The constitutive model requires stiffness and strength properties of an equivalent unidirectional composite. Simplified micromechanics methods are used to determine the equivalent stiffness properties, and results from coupon level tests on the braided composite are utilized to back out the required strength properties. Simulations of quasi-static coupon tests of several representative braided composites are conducted to demonstrate the correlation of the model. Impact simulations of a represented braided composites are conducted to demonstrate the capability of the model to predict the penetration velocity and damage patterns obtained experimentally