The Effect of Columnar Disorder on the Superconducting Transition of a Type-II Superconductor in Zero Applied Magnetic Field

We investigate the effect of random columnar disorder on the superconducting phase transition of a type-II superconductor in zero applied magnetic field using numerical simulations of three dimensional XY and vortex loop models. We consider both an unscreened model, in which the bare magnetic penetration length is approximated as infinite, and a strongly screened model, in which the magnetic penetration length is of order the vortex core radius. We consider both equilibrium and dynamic critical exponents. We show that, as in the disorder free case, the equilibrium transitions of the unscreened and strongly screened models lie in the same universality class, however scaling is now anisotropic. We find for the correlation length exponent $\nu=1.2\pm 0.1$, and for the anisotropy exponent $\zeta=1.3\pm 0.1$. We find different dynamic critical exponents for the unscreened and strongly screened models.Comment: 30 pages 12 ps figure

Consumption of freshwater fish: A variable but significant risk factor for PFOS exposure

PFOS, PFOA, PFNA and PFHxS are the PFAS substances that currently contribute most to human exposure, and in 2020 the European Food Safety Authority (EFSA) presented a draft opinion on a tolerable intake of 8 ng/kg/week for the sum of these four substances (equaling 0.42 mu g/kg if expressed as an annual dose). Diet is usually the dominating exposure pathway, and in particular the intake of PFOS has been shown to be strongly related to the consumption of fish and seafood. Those who eat freshwater fish may be especially at risk since freshwater and its biota typically display higher PFOS concentrations than marine systems. In this study, we estimated the range in PFOS intake among average Swedish "normal" and "high" consumers of freshwater fish. By average we mean persons of average weight who eat average-sized portions. The "normal consumers" were assumed to eat freshwater fish 3 times per year, and the "high consumers" once a week. Under these assumptions, the yearly tolerable intake for "normal" and "high" consumers is reached when the PFOS concentrations in fish equals 59 and 3.4 mu g per kg fish meat. For this study, PFOS concentrations in the muscle tissue of edible-sized perch, pike and pikeperch were retrieved from three different Swedish datasets, covering both rural and urban regions and a total of 78 different inland waters. Mean PFOS concentrations in fish from these sites varied from 0.3 to 750 mu g/kg. From the available data, the annual min-max dietary PFOS intake for male "normal consumers" was found to be in the range 0.0021-5.4 mu g/kg/yr for the evaluated scenarios, with median values of 0.02-0.16 mu g/kg/yr. For male "high consumers", the total intake range was estimated to be 0.04-93 mu g/kg/yr, with median values being 0.27-1.6 mu g/kg/yr. For women, the exposure estimates were slightly lower, about 79% of the exposure in men. Despite highly variable PFOS concentrations in fish from different sites, we conclude that the three most commonly consumed freshwater species in Sweden constitute an important source for the total annual intake even for people who eat this kind of fish only a few times per year. The analyses of PFOA, PFNA and PFHxS showed values which were all below detection limit, and their contribution to the total PFAS intake via freshwater fish consumption is negligible in comparison to PFOS

Vortex glass transition in a random pinning model

We study the vortex glass transition in disordered high temperature superconductors using Monte Carlo simulations. We use a random pinning model with strong point-correlated quenched disorder, a net applied magnetic field, longrange vortex interactions, and periodic boundary conditions. From a finite size scaling study of the helicity modulus, the RMS current, and the resistivity, we obtain critical exponents at the phase transition. The new exponents differ substantially from those of the gauge glass model, but are consistent with those of the pure three-dimensional XY model.Comment: 7 pages RevTeX, 4 eps figure

Perfluoroalkyl acids and their precursors in floor dust of children's bedrooms - Implications for indoor exposure

We analysed floor dust samples from 65 children's bedrooms in Finland collected in 2014/2015 for 62 different per- and polyfluoroalkyl substances (PFASs) with a simple and highly efficient method. Validation results from the analysis of standard reference material (SRM) 2585 were in good agreement with literature data, while 24 PFASs were quantified for the first time. In the dust samples from children's bedrooms, five perfluoroalkyl carboxylic acids (PFCAs) and perfluorooctane sulfonic acid (PFOS) were detected in more than half of the samples with the highest median concentration of 5.26 ng/g for perfluorooctanoic acid (PFOA). However, the dust samples were dominated by polyfluoroalkyl phosphoric acid esters (PAPs) and fluorotelomer alcohols (FTOHs) (highest medians: 53.9 ng/g for 6:2 diPAP and 45.7 ng/g for 8:2 FTOH). Several significant and strong correlations (up to p = 0.95) were found among different PFASs in dust as well as between PFASs in dust and air samples (previously published) from the same rooms. The logarithm of dust to air concentrations (log K-dust/air) plotted against the logarithm of the octanol-air partition coefficient (log K-oa) resulted in a significant linear regression line with R-2 > 0.88. Higher dust levels of PFOS were detected in rooms with plastic flooring material in comparison to wood (p <0.05). Total estimated daily intakes via dust (EDIdust) and air (EDIair) of perfluoroalkyl acids (PFAA), including biotransformation of precursors to PFAAs, were calculated for 10.5-year-old children. The total EDIdust, for PFOA and PFOS were estimated to be 0.007 ng/kg bw/day and 0.006 ng/kg bw/day, respectively, in an intermediate exposure scenario. The sum of the total EDIs for all PFAAs was slightly higher for dust than air (0.027 and 0.019 ng/kg bw/day). Precursor biotransformation was generally important for total PFOS intake, while for the PFCAs, FTOH biotransformation was estimated to be important for air, but not for dust exposure.Peer reviewe

Longitudinal trends of per- and polyfluoroalkyl substances in children's serum

Studies suggest negative health impacts from early life exposure to per- and polyfluoroalkyl substances (PFASs). However, information on longitudinal exposure to PFASs during childhood is scarce for background-exposed individuals. This study sought to fill this gap by investigating children's longitudinal exposure trends through measurement of PFAS serum concentrations and calculation of body burdens (mu g, total in body). Blood of 54 Finnish children was sampled 2005-2015 and analyzed for 20 PFASs at 1, 6 and 10.5 years of age. The body burden was calculated by multiplying the serum concentration by the volume of distribution and the bodyweight for each individual. Associations between serum concentrations or body burdens and parameters, such as sex, breastfeeding duration, body mass index as well as indoor dust and air PFAS concentrations, were evaluated. Serum concentrations of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) decreased significantly (p <0.001) with age. In contrast to serum concentrations, body burdens stayed unchanged or even increased significantly (p <0.05), except for PFOA in female children. Breastfeeding duration was positively correlated (p <0.001) with serum concentrations of PFHxS, PFOS, PFOA and PFNA at 1 year of age. Some associations were found at 10.5 years with sex and indoor PFAS concentrations. Observations of longitudinal decreasing trends of serum concentrations can be misleading for understanding exposure levels from external media during childhood, as the serum concentration is influenced by parallel temporal changes and growth dilution. Body burdens account for growth dilution and thus better reflect differences in early-life to adolescence exposure than serum concentrations.Peer reviewe

Perfluoroalkyl acids and their precursors in indoor air sampled in children's bedrooms

The contamination levels and patterns of perfluoroallcyl acids (PFAAs) and their precursors in indoor air of children's bedrooms in Finland, Northern Europe, were investigated. Our study is among the most comprehensive indoor air monitoring studies (n = 57) and to our knowledge the first one to analyse air in children's bedrooms for PFASs (17 PFAAs and 9 precursors, including two acrylates, 6:2 FTAC and 6:2 FTMAC). The most frequently detected compound was 8:2 fluorotelomer alcohol (8:2 FTOH) with the highest median concentration (3570 pg/m(3)). FTOH concentrations were generally similar to previous studies, indicating that in 2014/2015 the impact of the industrial transition had been minor on FTOH levels in indoor air. However, in contrast to earlier studies (with one exception), median concentrations of 6:2 FTOH were higher than 10:2 FTOH. The C8 PFAAs are still the most abundant acids, even though they have now been phased out by major manufacturers. The mean concentrations of FOSE/As, especially MeFOSE (89.9 pg/m(3)), were at least an order of magnitude lower compared to previous studies. Collectively the comparison of FTOHs, PFAAs and FOSE/FOSAs with previous studies indicates that indoor air levels of PFASs display a time lag to changes in production of several years. This is the first indoor air study investigating 6:2 FTMAC, which was frequently detected (58%) and displayed some of the highest maximum concentrations (13 000 pg/m(3)). There were several statistically significant correlations between particular house and room characteristics and PFAS concentrations, most interestingly higher EtFOSE air concentrations in rooms with plastic floors compared to wood or laminate. (C) 2016 Published by Elsevier Ltd.Peer reviewe

Nature of the vortex-glass order in strongly type-II superconductors

The stability and the critical properties of the three-dimensional vortex-glass order in random type-II superconductors with point disorder is investigated in the unscreened limit based on a lattice {\it XY} model with a uniform field. By performing equilibrium Monte Carlo simulations for the system with periodic boundary conditions, the existence of a stable vortex-glass order is established in the unscreened limit. Estimated critical exponents are compared with those of the gauge-glass model.Comment: Error in the reported value of the exponent eta is correcte

Domain Wall Renormalization Group Study of XY Model with Quenched Random Phase Shifts

The XY model with quenched random disorder is studied by a zero temperature domain wall renormalization group method in 2D and 3D. Instead of the usual phase representation we use the charge (vortex) representation to compute the domain wall, or defect, energy. For the gauge glass corresponding to the maximum disorder we reconfirm earlier predictions that there is no ordered phase in 2D but an ordered phase can exist in 3D at low temperature. However, our simulations yield spin stiffness exponents $\theta_{s} \approx -0.36$ in 2D and $\theta_{s} \approx +0.31$ in 3D, which are considerably larger than previous estimates and strongly suggest that the lower critical dimension is less than three. For the $\pm J$ XY spin glass in 3D, we obtain a spin stiffness exponent $\theta_{s} \approx +0.10$ which supports the existence of spin glass order at finite temperature in contrast with previous estimates which obtain $\theta_{s}< 0$. Our method also allows us to study renormalization group flows of both the coupling constant and the disorder strength with length scale $L$. Our results are consistent with recent analytic and numerical studies suggesting the absence of a re-entrant transition in 2D at low temperature. Some possible consequences and connections with real vortex systems are discussed.Comment: 14 pages, 9 figures, revtex

Biokinetics and dosimetry of commonly used radiopharmaceuticals in diagnostic nuclear medicine – a review

Purpose The impact on patients’ health of radiopharmaceuticals in nuclear medicine diagnostics has not until now been evaluated systematically in a European context. Therefore, as part of the EU-funded Project PEDDOSE. NET (www.peddose.net), we review and summarize the current knowledge on biokinetics and dosimetry of commonly used diagnostic radiopharmaceuticals. Methods A detailed literature search on published biokinetic and dosimetric data was performed mostly via PubMed (www.ncbi.nlm.nih.gov/pubmed). In principle the criteria for inclusion of data followed the EANM Dosimetry Committee guidance document on good clinical reporting. Results Data on dosimetry and biokinetics can be difficult to find, are scattered in various journals and, especially in paediatric nuclear medicine, are very scarce. The data collection and calculation methods vary with respect to the time-points, bladder voiding, dose assessment after the last data point and the way the effective dose was calculated. In many studies the number of subjects included for obtaining biokinetic and dosimetry data was fewer than ten, and some of the biokinetic data were acquired more than 20 years ago. Conclusion It would be of interest to generate new data on biokinetics and dosimetry in diagnostic nuclear medicine using state-of-the-art equipment and more uniform dosimetry protocols. For easier public access to dosimetry data for diagnostic radiopharmaceuticals, a database containing these data should be created and maintained