Testing a series of causal propositions relating time in child care to children’s externalizing behavior.

[Correction Notice: An erratum for this article was reported in Vol 46(2) of Developmental Psychology (see record 2010-03975-013). On the first page of the article “Testing a Series of Causal Propositions Relating Time in Child Care to Children’s Externalizing Behavior,” by Kathleen McCartney, Margaret Burchinal, Alison Clarke- Stewart, Kristen L. Bub, Margaret T. Owen, Jay Belsky, and the NICHD Early Child Care Research Network (Developmental Psychology, 2010, Vol. 46, No. 1, pp. 1–17), author Alison Clarke- Stewart’s name was misspelled as Aliso Clarke-Stewart. In addition, the e-mail address listed for the corresponding author Kathleen McCartney is incorrect. The correct e-mail address is: kathleen_mccartney@gse.harvard.edu. The online versions of this article have been corrected.] Prior research has documented associations between hours in child care and children’s externalizing behavior. A series of longitudinal analyses were conducted to address 5 propositions, each testing the hypothesis that child care hours causes externalizing behavior. Data from the National Institute of Child Health and Human Development Early Child Care Research Network (NICHD) Study of Early Child Care and Youth Development were used in this investigation because they include repeated measures of child care experiences, externalizing behavior, and family characteristics. There were 3 main findings. First, the evidence linking child care hours with externalizing behavior was equivocal in that results varied across model specifications. Second, the association between child care hours and externalizing behavior was not due to a child effect. Third, child care quality and proportion of time spent with a large group of peers moderated the effects of child care hours on externalizing behavior. The number of hours spent in child care was more strongly related to externalizing behavior when children were in low-quality child care and when children spent a greater proportion of time with a large group of peers. The magnitude of associations between child care hours and externalizing behavior was modest. Implications are that parents and policymakers must take into account that externalizing behavior is predicted from a constellation of variables in multiple contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Index 1947-78

In 1985 a team of fifty students and two staff members at the Auckland University School of Architecture executed a group consensus design alternative for that city's main concert auditorium. The project received wide media coverage, and generated enormous controversy. This paper outlines the social and political repercussions of their work.     

CONTINUOUS PROCESS IMPROVEMENT

Abstract

Even in corporations that have made great strides in implementing total quality management, IS departments have not always kept pace. This column, the first in a series to address issues of quality management in the IS department, discusses how the principles of TQM can be modified and successfully applied to information systems.     

A stochastic analysis of distance estimation approaches in single molecule microscopy: quantifying the resolution limits of photon-limited imaging systems

Optical microscopy is an invaluable tool to visualize biological processes at the cellular scale. In the recent past, there has been significant interest in studying these processes at the single molecule level. An important question that arises in single molecule experiments concerns the estimation of the distance of separation between two closely spaced molecules. Presently, there exists different experimental approaches to estimate the distance between two single molecules. However, it is not clear as to which of these approaches provides the best accuracy for estimating the distance. Here, we address this problem rigorously by using tools of statistical estimation theory. We derive formulations of the Fisher information matrix for the underlying estimation problem of determining the distance of separation from the acquired data for the different approaches. Through the Cramer-Rao inequality, we derive a lower bound to the accuracy with which the distance of separation can be estimated. We show through Monte-Carlo simulations that the bound can be attained by the maximum likelihood estimator. Our analysis shows that the distance estimation problem is in fact related to the localization accuracy problem, the latter being a distinct problem that deals with how accurately the location of an object can be determined. We have carried out a detailed investigation of the relationship between the Fisher information matrices of the two problems for the different experimental approaches considered here. The paper also addresses the issue of a singular Fisher information matrix, which presents a significant complication when calculating the Cramer-Rao lower bound. Here, we show how experimental design can overcome the singularity. Throughout the paper, we illustrate our results by considering a specific image profile that describe the image of a single molecule.     

A Correlation of Bulk Moduli and P-V-T Data for Silicone Fluids at Pressures up to 500,000 psig

The increased sophistication of hydraulic systems along with the advancement of elastohydrodynamics and high pressure metal forming techniques has created a need for more complete bulk moduli and P-V-T data. By correlation of the available data on silicones, a generalized relationship for this class of fluids is determined for bulk modulus as a function of pressure, temperature, and density of the fluid at atmospheric pressure and 77F. Thus, density and bulk modulus for most silicone fluids may be predicted at temperatures from 32F to 400F and pressures up to 500,000 psig. For most silicone fluids only the density at atmospheric pressure and 77F is needed beforehand. A few exceptions are listed for which the correlation is applicable with minor modifications. The average deviation of the predicted values of bulk moduli from the experimental data is 1%.     

Positron annihilation lifetime spectroscopy and diffusion studies of large molecule penetrants into a polyester

Positron annihilation lifetime spectroscopy measurements are reported for a polyester and free volume characteristics determined as a function of temperature. The glass‐rubber transition was determined using DMTA. The diffusion behaviour of a series of large molecules; dioctyl phthalate, 2‐ethyl hexylbenzyl phthalate, nonyl phenol ethoxylate, isopropyl myristate, and oleic acid into the polyester were investigated using gravimetric measurements. The permeation does not follow simple Fickian type behaviour and the rate of diffusion of 2‐ethyl hexylbenzyl phthalate is surprisingly high in comparison to the other systems studied. At or above the T_g, the diffusion rates for all the systems studied increase substantially. The sizes of the permeant molecules in their lowest energy conformation were calculated theoretically. Comparison of the size of the molecules and that of the void size measured by positron annihilation lifetime spectroscopy measurements divides the molecules into two groups. Isopropylmyristate and oleic acid exhibits cross sections which would allow the molecules to slither into cavities. The remaining molecules have cross sections which are larger than the available void size and must swell the matrix before diffusion can occur. The permeation behaviour is influenced by the available free volume but dominated by the solubility characteristics of the permeants. POLYM. ENG. SCI., 52:1978–1984, 2012. © 2012 Society of Plastics Engineers     

Patient-specific computational analysis of the influence of a stent on the unsteady flow in cerebral aneurysms

We present a patient-specific computational analysis of the influence of a stent on the unsteady flow in cerebral aneurysms. The analysis is based on four different arterial models extracted form medical images, and the stent is placed across the neck of the aneurysm to reduce the flow circulation in the aneurysm. The core computational technique used in the analysis is the space–time (ST) version of the variational multiscale (VMS) method and is called “DSD/SST-VMST”. The special techniques developed for this class of cardiovascular fluid mechanics computations are used in conjunction with the DSD/SST-VMST technique. The special techniques include NURBS representation of the surface over which the stent model and mesh are built, mesh generation with a reasonable resolution across the width of the stent wire and with refined layers of mesh near the arterial and stent surfaces, modeling the double-stent case, and quantitative assessment of the flow circulation in the aneurysm. We provide a brief overview of the special techniques, compute the unsteady flow patterns in the aneurysm for the four arterial models, and investigate in each case how those patterns are influenced by the presence of single and double stents.