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Background: Identifying factors that impair bone accrual during childhood is a critical step toward osteoporosis prevention. Exposure to per- and polyfluoroalkyl substances (PFASs) has been associated with lower bone mineral density, but data are limited, particularly in children. Methods: We studied 576 children in Project Viva, a Boston-area cohort of mother/child pairs recruited prenatally from 1999 to 2002. We quantified plasma concentrations of several PFASs and measured areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry (DXA) in midchildhood. We used linear regression to examine associations between plasma concentrations of individual PFASs and aBMD z-score. We used weighted quantile sum (WQS) regression to examine the association of the PFAS mixture with aBMD z-score. All models were adjusted for maternal age, education, annual household income, census tract median household income, and child age, sex, race/ethnicity, dairy intake, physical activity, and year of blood draw. Results: Children were [mean [+ or -] standard deviation (SD)] 7.9[+ or -]0.8 years of age. The highest PFAS plasma concentrations were of perfluorooctanesulfonic acid (PFOS) {median [interquartile range (IQR)]: 6.4 (5.6) ng/mL} and perfluorooctanoic acid (PFOA) [median (IQR): 4.4 (3.2) ng/mL]. Using linear regression, children with higher plasma concentrations of PFOA, PFOS, and perfluorodecanoate (PFDA) had lower aBMD z-scores [e.g., [beta]: -0.16; 95% confidence interval (CI): -0.25, -0.06 per doubling of PFOA]. The PFAS mixture was negatively associated with aBMD z-score ([beta]: -0.16; 95% CI: -0.28, -0.04 per IQR increment of the mixture index). Conclusions: PFAS exposure may impair bone accrual in childhood and peak bone mass, an important determinant of lifelong skeletal health. https://doi.org/10.1289/EHP4918, Introduction Osteoporosis affects over 200 million adults worldwide, and associated fractures are costly, with high morbidity and mortality and limited treatment options (Reginster and Burlet 2006). Because bone accrues during [...]

A genome-wide association study is conducted for the identification of the novel common variants that are associated with the circulating carotenoid levels and known lipid variants associated with [alpha]-tocopherol levels. The common variation taking place in the [beta]-carotene 15,15'-monooxygenase 1 gene is shown to affect the circulating levels of carotenoids.

This article evaluates the effectiveness of a Head Start program in which high risk children are provided with educational transition assistance. The authors, comparing children who were involved in the program from kindergarten until the third grade with children who did not receive the same services, maintain Head Start was successful in decreasing special education placement.

The authors examine the problem of identifying children with emotional, behavioral, and learning disabilities from Head Start program special education identification data gathered during the child's third grade of school.

Clowes illustrated how to select the optimal time-scaling factor for approximations of rational transfer functions using a series expansion of Laguerre functions. This paper extends this result to approximations for general, [L.sub.2] stable, linear systems. As a direct application of this extended result, we are able to obtain approximations for irrational transfer functions which minimize the frequency domain error in the [L.sub.2] sense. Also, we will give empirical solutions for the optimal time-scaling factor for approximations of first order plus delay systems which can then be applied to a larger class of overdamped systems.

This paper presents the development of a model for free radical initiated polypropylene degradation during reactive extrusion that combines a kinetic model of the polypropylene degradation reaction with a simplified model of the melting mechanism in the extruder. The free radical initiated degradation of polypropylene is characterized by a narrowing of the molecular weight distribution (MWD) and a decrease in the molecular weight averages. A high temperature SEC is used to determine MWD's for three different commercially available polypropylenes degraded at various initiator concentrations in a 1.5 inch single screw extruder (L/D = 24: 1). The predictions of the kinetic model alone and the combined kinetic-melting model are compared with the experimentally determined MWD's and molecular weight averages for the degraded polypropylenes. The predictions of a modified kinetic model that includes the possibility of termination by combination are also examined. The kinetic-melting model is found to provide significantly improved predictions of the experimentally determined MWD's and molecular weight averages in comparison to the original kinetic model. A viscosity-molecular weight relationship is also developed, which is then used to determine the gain of the degradation process as a function of the initiator concentration from the molecular weight averages predicted by the kinetic-melting model. Earlier work has shown such prior knowledge of the process gain can be used to significantly improve the performance of process control schemes for the degradation process.

This paper presents the design and analysis of a process control strategy for a reactive extrusion polypropylene degradation process. The primary control objective is to continuously produce polypropylene with desired properties (viscosity) despite variations in the properties of the feed material. The viscosity of the polypropylene, measured using an In-line Wedge Rheometer, is controlled by manipulating the feed concentration of the peroxide which acts as the initiator for the degradation reaction. An empirical model of the reactive degradation process is developed which describes the process dynamics and the characteristic process disturbances. Minimum variance (MW), constrained minimum variance (CMV), and pole placement (PP) controllers are first evaluated and compared in simulation. Then, a pole placement controller is implemented on the actual reactive extrusion process, with results being presented for the response of the controlled process to load disturbances due to feed material changes.

The hypothesis that tubulation is an inherent property of organelle membranes was tested using membranes of the Golgi complex and the trans-golgi netork. In vitro, the membranes formed tubules when incubated with brefeldin A, but tubulation was more extensive when the membranes were incubated with reduced adenosine triphosphate (ATP) levels. Incubation of cells with NaN3 and 2-deoxy-D-glucose to reduce ATP levels also resulted in tubulation in vivo. Tubulation was reversible and correated with the removal of the vesicle-associated protein beta-COP from the membranes.

A musical language is developed from extra-musical study of auditory perception, recorded sound and architectural acoustics. The listener's phenomenological experience of the acoustic potential of both the room and the instrumental or electronic forces are treated as the determinants of content, discrete and semantic pitch choices, rhythm, tempo and form of the musical composition, enabling it to emerge as a space similar to the multidimensional space of everyday listening habits.