Clustering and interrelationships of coronary heart disease risk factors in schoolchildren, ages 6-19

Clustering and interrelationships of common and easily identifiable risk factors in 951 children (ages 6-19) from the Cincinnati Lipid Research Clinic's Princeton School of District Study were assessed. Several patterns of partial correlation coeffieients appeared after multiple regression analysis with adjustment for age, sex, Quetelet index, and race. Systolic blood pressure (SBP) was positively correlated with plasma cholesterol and triglyceride, and with saturated fat intake. Plasma high density lipoprotein cholesterol (C-HDL) was positively associated with occupation of the head of the household and inversely associated with cigarette smoking and sucrose intake. Using multiple regression equations, from 29-41% of the variance for SBP and diastolic blood pressure (DBP) could be explained by the measured variables, with age, skinfold thickness, Quetelet, occupation, and education of the head of the household recurrently appearing in the regression equatons. Low density lipoprotein cholesterol (C-HDL) was the variable for which the lowest amount of variance could be explained in the four race-sex groups. Discriminant function analysis allowed an assessment of interrelationships of C-LDL-C-HDL aggregate groups to other risk factor mean residuals. The variables which contributed significantly to the discrimination between lipoprotein groups were Quetelet index, skinfold thickness, and DBP. Children in the highest C-LHL-lowest C-HDL quintile group had by far the highest residual Quetelet index and skinfold thickness, along with above average SBP, while those in The lowest C-LDL-highest C-HDL quintile group had the lowest residual Quetelet index, skinfold thickness, and SBP. Common risk and anti-risk factors for coronary heart disease (CHD) in children cluster, allowing identification of groups of children putatively at relatively high and low CHD risk as adults.     

The conundrum of unmeasured confounding: Comment on: "Can some of the detrimental neurodevelopmental effects attributed to lead be due to pesticides? by Brian Gulson"

The problem described by Dr. Brian Gulson - confounding by unmeasured exposures to pesticides - is only the most recent in a series of potential confounders cited to explain the observed effect of lead on children's intellectual abilities or behavioral problems. Despite the persistent problem of unmeasured confounders, there are several lines of evidence implicating lead as a toxicant at blood lead levels <10 microg/dL. First, in striking contrast with pesticides, there is considerable evidence from numerous studies linking low-level lead exposure with cognitive deficits and behavioral problems, even after controlling for a variety of potential confounders. Second, the consistency of evidence from diverse cohorts and distinct, if not always directly measured potential confounders - enhances our confidence that the lead effect observed at blood lead levels <10 microg/dL is not attributable to unmeasured confounders. Third, in our reanalysis of the Rochester Lead Study, the inclusion of parent-reported mouthing behaviors and breastfeeding status did not attenuate the effect of lead exposure on children's intellectual function. Finally, although we can never entirely dismiss unmeasured confounding in observational studies, we can rely on experimental studies of lead-exposed animals to confirm that lead is a toxicant. Thus, while we must remain vigilant for unmeasured or poorly measured confounders, it is crucial to balance the endless search for confounders with the evidence of toxicity and the need to take action to protect public health. The alternative, to perpetually permit children to be exposed to lead and other emerging toxicants, is both absurd and unacceptable.     

Binary phase-only filtering for turbulence compensation in fiber-coupled free-space laser communication systems

Binary wavefront control in the focal plane (i.e., binary phase-only filtering) for partial compensation of atmospheric turbulence in fiber-coupled free-space laser communication systems is investigated. Numerical results from wave-optics simulations show that in an air-to-air scenario, the combination of binary phase-only filtering and centroid tracking provides mean fiber coupling efficiency close to that resulting from ideal least-squares adaptive optics, but without the requirement for direct wavefront sensing. This result suggests a simpler and less computationally demanding turbulence mitigation system that is more readily applied to tactical applications.     

Spectrally variable two-beam coupling nonlinear deconvolution

In previous work, we introduced a dynamic range compression-based technique for image correction using nonlinear deconvolution; the impulse response of the distortion function and the distorted image are jointly transformed to pump a clean reference beam in a photorefractive two-beam coupling arrangement. The Fourier transform of the pumped reference beam contains the deconvolved image and its conjugate. Here we extend our work to spectrally variable dynamic range compression. This approach allows the retrieval of distorted signals embedded in a very high noise environment and does not require one to work with a very high beam ratio as in our previous work. Resolution recovery of blurred noisy images is demonstrated for several different types of image blur.     

Real-time single-molecule imaging of oxidation catalysis at a liquid-solid interface

Many chemical reactions are catalysed by metal complexes, and insight into their mechanisms is essential for the design of future catalysts. A variety of conventional spectroscopic techniques are available for the study of reaction mechanisms at the ensemble level, and, only recently, fluorescence microscopy techniques have been applied to monitor single chemical reactions carried out on crystal faces and by enzymes. With scanning tunnelling microscopy (STM) it has become possible to obtain, during chemical reactions, spatial information at the atomic level. The majority of these STM studies have been carried out under ultrahigh vacuum, far removed from conditions encountered in laboratory processes. Here we report the single-molecule imaging of oxidation catalysis by monitoring, with STM, individual manganese porphyrin catalysts, in real time, at a liquid-solid interface. It is found that the oxygen atoms from an O2 molecule are bound to adjacent porphyrin catalysts on the surface before their incorporation into an alkene substrate.     

Experimental Validation of the Multiple Absorption Coefficient Zonal Method (MACZM) in a Dynamic Modeling of a Steel Reheating Furnace

In this work, the multiple absorption coefficient zonal method (MACZM) is being implemented and validated numerically. The method is demonstrated to be highly suitable for the analysis of radiative heat transfer in multidimensional inhomogeneous non-grey media. A uniform rectangular fine grid is considered and small CPU time is achieved. This makes the method of great interest for transient applications. The validity of the method is demonstrated in two steps. First, cases with simple geometry are considered and results are compared to results generated by direct numerical integration. Results are also generated by MODRAY, which is a source project based on an original method called the flux-planes approximation, and are shown to be equally accurate. Second, the case of a steel reheating furnace is considered. In a previous work, the furnace heat balance and temperature profiles were simulated using a finite difference computation approach and radiative exchange factors generated by MODRAY. Experiments were performed and results generated by the model were found to be in good agreement with experimental data. The radiative exchange factors are now recalculated with MACZM. They are shown to be very close to those generated by MODRAY. The comparison of the two methods clearly shows that MACZM is much faster for the calculation of the volume-volume radiative exchange factors on a uniform rectangular grid.     

Left ventricular geometry and severe left ventricular hypertrophy in children and adolescents with essential hypertension

BACKGROUND: Left ventricular (LV) hypertrophy has been established as an independent risk factor for cardiovascular disease in adults. Recent research has refined this relationship by determining a cutpoint of 51 g/m(2.7) for LV mass index indicative of increased risk and defining LV geometric patterns that are associated with increased risk. The purpose of this study was to evaluate severe LV hypertrophy and LV geometry in children and adolescents with essential hypertension. METHODS AND RESULTS: A cross-sectional study of young patients (n=130) with persistent blood pressure elevation above the 90th percentile was conducted. Nineteen patients (14%) had LV mass greater than the 99th percentile; 11 of these were also above the adult cutpoint of 51 g/m(2.7). Males, subjects with greater body mass index, and those who had lower heart rate at maximum exercise were at significantly (P<.05) higher risk of severe LV hypertrophy. In addition, 22 patients (17%) had concentric LV hypertrophy, a geometric pattern that is associated with increased risk of cardiovascular disease in adults. Seven patients had LV mass index above the cutpoint and concentric hypertrophy. No consistent significant determinants of LV geometry were identified in these children and adolescents with hypertension. CONCLUSIONS: Severe LV hypertrophy and abnormal LV geometry are relatively prevalent in young patients with essential hypertension. These findings suggest that these patients may be at risk for future cardiovascular disease and underscore the importance of recognition and treatment of blood pressure elevation in children and adolescents. Weight loss is an important component of therapy in young patients with essential hypertension who are overweight.     

A microscale evaluation of pavement roughness effects for asset management

In this paper, the authors present a method to automate data collection and mapping of pavement roughness on various functional classification roadways and to quantify fuel consumption for enhanced benefit-to-cost analysis, asset management and infrastructure investment strategies. A new low-cost and efficient technology is presented to measure and contrast vehicles' vertical accelerations over smooth and rough pavement sections. Fuel consumption is then correlated with the vehicle's vertical acceleration over both pavement conditions. The results of the study validate the relationship between acceleration/road roughness and fuel consumption. Finally, using the described technology, a pothole detection algorithm is devised to automatically map road roughness, a step towards a better asset management system.     

Sampled-data and continuous-time squarers in MOS technology

Two MOS squarer circuits are presented. One implementation operates on sampled-data signals, while the second uses continuous-time operation. Both squarers achieve the square-law function with MOS transistors operating in the nonsaturation region biased with zero drain-to-source voltage. Benefits of nonsaturated operation are discussed. The sampled-data squarer is practically independent of component mismatches and clock pulse-width mismatches