Aging and memory effects in beta-hydrochinone-clathrate

The out-of-equilibrium low-frequency complex susceptibility of the orientational glass methanol(73%)-beta-hydrochinone-clathrate is studied using temperature-stop protocols in aging experiments . Although the material does not have a sharp glass transition aging effects including rejuvenation and memory are found at low temperatures. However, they turn out to be much weaker, however, than in conventional magnetic spin glasses.Comment: 5 pages RevTeX, 6 eps-figures include

Maternal bisphenol and phthalate urine concentrations and weight gain during pregnancy

Background: Insufficient or excessive gestational weight gain are associated with increased risks of adverse birth and childhood outcomes. Increasing evidence suggests that exposure to bisphenols and phthalates may disrupt hormonal pathways and thereby influence gestational weight gain. Objective: To examine the associations of early and mid-pregnancy bisphenol and phthalate urine concentrations with gestational weight gain. Methods: In a population-based prospective cohort study among 1,213 pregnant women, we measured early and mid-pregnancy bisphenol and phthalate urine concentrations. Maternal anthropometrics before pregnancy were obtained by questionnaire and repeatedly measure

Individual and contextual determinants of perceived peer smoking prevalence among adolescents in six European cities

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Correlations in Cosmic String Networks

We investigate scaling and correlations of the energy and momentum in an evolving network of cosmic strings in Minkowski space. These quantities are of great interest, as they must be understood before accurate predictions for the power spectra of the perturbations in the matter and radiation in the early Universe can be made. We argue that Minkowski space provides a reasonable approximation to a Friedmann background for string dynamics and we use our results to construct a simple model of the network, in which it is considered to consist of randomly placed segments moving with random velocities. This model works well in accounting for features of the two-time correlation functions, and even better for the power spectra.Comment: 20pp Plain LaTeX, 11 EPS figures, uses epsf.st

Low serum vitamin D is associated with axial length and risk of myopia in young children

The aim of the study was to investigate the relationship between serum 25(OH)D levels and axial length (AL) and myopia in 6-year-old children. A total of 2666 children aged 6 years participating in the birth-cohort study Generation R underwent a stepwise eye examination. First, presenting visual acuity (VA) and AL were performed. Second, automated cycloplegic refraction was measured if LogMAR VA > 0.1. Serum 25-hydroxyvitamin D [25(OH)D] was determined from blood using liquid chromatography/tandem mass spectrometry. Vitamin D related SNPs were determined with a SNP array; outdoor exposure was assessed by questionnaire. The relationships between 25(OH)D and AL or myopia were investigated using linear and logistic regression analysis. Average 25(OH)D concentration was 68.8 nmol/L (SD ± 27.5; range 4–211); average AL 22.35 mm (SD ± 0.7; range 19.2–25.3); and prevalence of myopia 2.3 % (n = 62). After adjustment for covariates, 25(OH)D concentration (per 25 nmol/L) was inversely associated with AL (β −0.043; P < 0.01), and after additional adjusting for time spent outdoors (β −0.038; P < 0.01). Associations were not different between European and non-European children (β −0.037 and β −0.039 respectively). Risk of myopia (per 25 nmol/L) was OR 0.65 (95 % CI 0.46–0.92). None of the 25(OH)D related SNPs showed an association with AL or myopia. Lower 25(OH)D concentration in serum was associated with longer AL and a higher risk of myopia in these young children. This effect appeared independent of outdoor exposure and may suggest a more direct role for 25(OH)D in myopia pathogenesis

Magnetic fields in the early universe in the string approach to MHD

There is a reformulation of magnetohydrodynamics in which the fundamental dynamical quantities are the positions and velocities of the lines of magnetic flux in the plasma, which turn out to obey equations of motion very much like ideal strings. We use this approach to study the evolution of a primordial magnetic field generated during the radiation-dominated era in the early Universe. Causality dictates that the field lines form a tangled random network, and the string-like equations of motion, plus the assumption of perfect reconnection, inevitably lead to a self-similar solution for the magnetic field power spectrum. We present the predicted form of the power spectrum, and discuss insights gained from the string approximation, in particular the implications for the existence or not of an inverse cascade.Comment: 12 pages, 2 figure

Fetal phthalates and bisphenols and childhood lipid and glucose metabolism. A population-based prospective cohort study

Background and aims: Fetal exposure to endocrine disruptors such as phthalates and bisphenols may lead to developmental metabolic adaptations. We examined associations of maternal phthalate and bisphenol urine concentrations during pregnancy with lipids, insulin, and glucose concentrations at school age. Methods: In a population-based, prospective cohort study among 757 mother–child pairs, we measured maternal phthalate and bisphenol urine concentrations in first, second and third trimester of pregnancy. We measured non-fasting lipids, glucose and insulin blood concentrations of their children at a mean age of 9.7 (standard deviation 0.2) years. Analyses were performed for boys and girls separately. Results: An interquartile range (IQR) higher natural log transformed third trimester maternal urine phthalic acid concentration was associated with a 0.20 (95% confidence interval (CI) 0.07–0.34) standard deviation score (SDS) higher triglycerides concentration among boys. Maternal bisphenol urine concentrations were not associated with non-fasting lipid concentrations during childhood. An IQR higher natural log transformed second trimester maternal high molecular weight phthalates (HMWP) and di-2-ethylhexylphthalate (DEHP) urine concentration were associated with a 0.19 (95% CI 0.31–0.07) respectively 0.18 (95% CI 0.31–0.06) SDS lower glucose concentration among boys. An IQR higher natural log transfor

Associations of maternal phthalate and bisphenol urine concentrations during pregnancy with childhood blood pressure in a population-based prospective cohort study

Objectives: Fetal exposure to phthalates and bisphenols may lead to vascular developmental adaptations, which program later cardiovascular disease. We examined the associations of fetal exposure to phthalates and bisphenols with childhood blood pressure. Methods: In a population-based, prospective cohort study among 1,064 mother-child pairs, we measured maternal urine phthalate and bisphenol concentrations in first, second and third trimester of pregnancy. We measured childhood blood pressure at the mean age of 9.7 years (standard deviation 0.2 years) old. Analyses were performed for the total group, and for boys and girls separately. Results: Maternal urine phthalate concentrations were not associated with childhood blood pressure among boys. Higher third trimester maternal urine concentrations of high molecular weight phthalates (HMWP), di-2-ehtylhexylphthalate (DEHP) and di-n-octylphthalate (DNOP) were associated with lower systolic and diastolic blood pressure among girls (p-values < 0.01). Also, higher second trimester maternal urine total bisphenol and bisphenol A concentrations were associated with higher systolic blood pressure among boys (p values < 0.01), but tended to be associated with a lower diastolic blood pressure among girls. Conclusions: Our results suggest sex-dependent associations of maternal urine phthalate and bisphenol concentrations during pregnancy with childhood blood pressure. Further studies are needed to explore the underlying mechanisms and long term consequences

Heat treatment of cold extruded polycarbonate: Some implications for design engineers

Polycarbonate was subjected to various combinations of mechanical - thermal histories to investigate such effects on subsequent tensile mechanical properties. This was accomplished by "cold extruding" the material initially; nominal "reductions in area" of 18, 40 and 64% were used. Cold extruded bars were then heat treated at three temperature levels, all being less than Tg (150[deg]C) of polycarbonate. As compared with the material that was only cold extruded, it was found that in general, heat treating tends to raise the yield stress while lowering the tensile strength, elastic modulus and stress at fracture. The results suggest that a desired combination of properties may be obtainable by the use of a cold work - heat treating sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22085/1/0000509.pd