Inorganic elements in the livers of Eurasian otters, Lutra lutra, from England and Wales in 2007 & 2008: a Predatory Bird Monitoring Scheme (PBMS) report

This is a report on the initial findings of a collaborative study between the Predatory Bird Monitoring Scheme (PBMS) and the Cardiff University Otter Project (CUOP). The study analysed the concentrations of 16 metals and semi-metals in the livers of 107 Eurasian otters (Lutra lutra) that had been found dead in 2007 and 2008 and collected by the CUOP. This aim of this work was to determine the current concentrations of inorganic elements accumulated by otters and whether exposure to heavy metals (lead, mercury, cadmium) in particular is likely to be associated with adverse effects. This is the first study of inorganic elements in otter livers from Europe for nearly 10 years. The otters that were analysed were from England and Wales and included adult and subadult males and females. Liver tissue was analysed using Inductively Coupled Plasma mass spectrometry (ICP-MS) techniques. The concentrations of inorganic elements measured in the present study were within the range previously reported for Eurasian otters in Britain and elsewhere in Europe. Concentrations varied with age and/or sex for some elements. For the heavy metals mercury and cadmium, liver concentrations generally increased with age whereas for lead, juveniles generally had higher liver lead concentrations than adults although for lead these difference were not statistically significant. Aluminium and chromium were the only elements that varied significantly in concentrations between years. It is unclear whether the inter-year variation in aluminium and chromium represent significant inter-year changes in exposure and/or accumulation or may simply reflect local-scale variation in the provenance of otters and their associated exposure. The liver concentrations of heavy metals (mercury, cadmium and lead) in all the otters analysed were below those associated with toxic effects in mammals, although liver lead concentrations in a small number of otters were close to the level of concern

The accuracy of diagnostic ultrasound imaging for musculoskeletal soft tissue pathology of the extremities: A comprehensive review of the literature

Musculoskeletal diagnostic ultrasound imaging (MSK-DUSI) has been growing outside the traditional radiology speciality. Increased use of this technology has been reported in several healthcare settings, however an apparent gap in the knowledge of the accuracy of this diagnostic technology indicated a review was warranted. We undertook a structured review of the literature to assess the accuracy of MSK-DUSI for the diagnosis of musculoskeletal soft tissue pathology of the extremities. An electronic search of the National Library of Medicine’s PubMed database (1972 to mid-2014) was conducted. All relevant systematic reviews of diagnostic studies, all diagnostic studies published after the date of the latest systematic reviews and relevant diagnostic studies outside the scope the systematic reviews that directly compared the accuracy of MSK-DUSI (the index test) to an appropriate reference standard for the target condition were included. A fundamental appraisal of the methodological quality of studies was completed. The individual sensitivity, specificity and likelihood ratio data were extracted and entered into diagnostic accuracy tables. A total of 207 individual studies were included. The results show that MSK-DUSI has acceptable diagnostic accuracy for a wide spectrum of musculoskeletal conditions of the extremities. However, there is a lack of high quality prospective experimental studies in this area and as such clinicians should interpret the results with some caution due to the potential for overestimation of diagnostic accuracy

Liver concentrations of flame retardants in Eurasian otters (Lutra lutra) collected from Scotland between 2013 and 2015: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability contaminant monitoring and surveillance work on avian predators. By monitoring sentinel vertebrate species, the PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. The current study presents the results of a study in which the concentrations of polybrominated diphenyl ethers (PBDEs) were determined in the livers of a small sample of Eurasian otters (Lutra lutra) that died in Scotland between 2013 and 2015. The principle aim of this work was to determine the current concentrations of PBDEs that are accumulated by otters in Scotland and whether these concentrations are likely to cause adverse effects in those individuals analysed. The otters that were analysed included adult and sub-adult, males and females although there were insufficient sample numbers to test for differences among these demographic groups. Liver tissue was analysed using Gas Chromatograph – Mass Spectrometry (GC-MS). PBDEs were detected in all otter livers analysed, with congeners BDE47, BDE153 and BDE100 dominant in the congener profile. The toxicological consequences of exposure to PBDEs in otters are uncertain given the lack of established links between liver PBDE concentrations and health effects in this species but concentrations were lower than those associated with adverse effects in mink. The general low levels of PBDEs suggests that there is little evidence to date of toxicologically significant contamination of Scottish otters with these compounds. There is clear evidence that Scottish otters have significantly lower residues of the less-brominated PBDEs than those previously measured in otters from England and Wales. However, these results may not be representative of otters from throughout Scotland as the present sample came predominantly from the Inner Hebrides

Effect of diffusive boundaries on surface superconductivity in unconventional superconductors

Boundary conditions for a superconducting order parameter at a diffusive scattering boundary are derived from microscopic theory. The results indicate that for all but isotropic gap functions the diffusive boundary almost completely suppresses surface superconductivity in the Ginzburg-Landau regime. This indicates that in anisotropic superconductors surface superconductivity can only be observed for surface normals along high symmetry directions where atomically clean surfaces can be cleaved.Comment: Latex File, 12 pages, 2 Postscript figures, to appear in Phys. Rev. B (June 1 1996

Evaluation of methods for detecting human reads in microbial sequencing datasets

Sequencing data from host-associated microbes can often be contaminated by the body of the investigator or research subject. Human DNA is typically removed from microbial reads either by subtractive alignment (dropping all reads that map to the human genome) or by using a read classification tool to predict those of human origin, and then discarding them. To inform best practice guidelines, we benchmarked eight alignment-based and two classification-based methods of human read detection using simulated data from 10 clinically prevalent bacteria and three viruses, into which contaminating human reads had been added. While the majority of methods successfully detected >99 % of the human reads, they were distinguishable by variance. The most precise methods, with negligible variance, were Bowtie2 and SNAP, both of which misidentified few, if any, bacterial reads (and no viral reads) as human. While correctly detecting a similar number of human reads, methods based on taxonomic classification, such as Kraken2 and Centrifuge, could misclassify bacterial reads as human, although the extent of this was species-specific. Among the most sensitive methods of human read detection was BWA, although this also made the greatest number of false positive classifications. Across all methods, the set of human reads not identified as such, although often representing 300 bp) bacterial reads, the highest performing approaches were classification-based, using Kraken2 or Centrifuge. For shorter (c. 150 bp) bacterial reads, combining multiple methods of human read detection maximized the recovery of human reads from contaminated short read datasets without being compromised by false positives. A particularly high-performance approach with shorter bacterial reads was a two-stage classification using Bowtie2 followed by SNAP. Using this approach, we re-examined 11 577 publicly archived bacterial read sets for hitherto undetected human contamination. We were able to extract a sufficient number of reads to call known human SNPs, including those with clinical significance, in 6 % of the samples. These results show that phenotypically distinct human sequence is detectable in publicly archived microbial read datasets

The effect of a barnacle-shaped excrescence on the hydrodynamic performance of a tidal turbine blade section

Efficient tidal turbine designs rely upon the hydrodynamic performance of the turbine blade sections. A significant consideration for the likely power generation capacity of a tidal turbine is the effect of biofouling on the blade performance. A turbine blade surface is susceptible to large scale macrofouling, mainly from encrusters, such as barnacles and molluscs, colonising the developing surface. This paper considers the case of when a barnacle attaches to the upper (suction) surface of the blade section. Results of experiments to investigate the unsteady flow characteristics of the blade section are presented, and the modification of the hydrodynamic performance coefficients due to the presence of a barnacle is evaluated. The barnacle has no significant effect upon the lift in steady flow and unsteady flow, but there is a very large increase in the drag. Dependent upon the degree of barnacle encrustation, the effect on a turbine blade drag may be significant and lead to a degradation of a turbine predicted performance

Anticoagulant rodenticides in red kites (Milvus milvus) in Britain in 2017 and 2018

Second generation anticoagulant rodenticides (SGARs) can be toxic to all mammals and birds. Various studies have shown that, in Britain, there is widespread exposure to SGARs in a diverse range of predatory mammals and birds, including red kites (Milvus milvus) which scavenge dead rats, a target species for rodent control. The Wildlife Incident Monitoring Scheme (WIIS) and the Predatory Bird Monitoring Scheme (PBMS) have shown that some mortalities result from this secondary exposure. In the present study, we analysed liver SGAR residues in 77 red kites that had been found dead in Britain in either 2017 or 2018. The carcasses were submitted to and necropsied by the Disease Risk Analysis and Health Surveillance (DRAHS) programme, the PBMS, the WIIS for England & Wales, the WIIS for Scotland and the Raptor Health Scotland study; the livers from the kites were subsequently analysed for SGAR residues. All the organisations are partners in the WILDCOMS network that promotes collaboration among surveillance schemes that monitor disease and contaminants in vertebrate wildlife. All of the 66 kites from England & Wales and 10 of the 11 red kites from Scotland had detectable liver residues of at least one SGAR. When considering the sample of kites as a whole, brodifacoum, difenacoum and bromadiolone were each detected in 73, 71 and 60 kites, respectively. Difethialone was found in 11 individuals while flocoumafen was detected in only one bird. Sum liver SGAR concentrations ranged between non-detected and 1218 ng/g wet wt. (arithmetic mean: 246 ng/g, median 154 ng/g). Post-mortem examinations indicated that 13 (16.8%) of red kites examined had internal haemorrhaging that was not associated with detectable trauma and had detectable liver SGAR concentrations. These birds had sum SGAR liver concentrations that ranged from 135 ng/g wet weight to 1218 ng/g wet weight. SGARs were considered a contributory cause of death in these cases. The stewardship scheme for anticoagulant rodenticides came fully into force in mid-2016 as re-registration of products for use in the UK was completed. A key aim is to reduce exposure of non-target wildlife to anticoagulant rodenticides but stewardship also aims to maintain efficacious rat control and so the number and density of AR-contaminated rats may remain unchanged. However, diligent searching, removal and safe disposal of poisoned rats, as promoted by stewardship, might be expected to reduce the availability of poisoned dead rats to red kites [and other scavengers] and thereby reduce the proportion of birds that are exposed and/or the magnitude of exposure. Concomitant with stewardship was a relaxation of the indoor use only restriction previously applied to brodifacoum, flocoumafen and difethialone, the three most acutely toxic SGARs. Any consequent increase in outdoor use of these three SGARs could increase the risk of secondary exposure in red kites. We therefore compared the data in the current report with that collected in 2015 and 2016 to determine if there was any evidence of a change in pattern or magnitude of exposure in red kites that might be connected to stewardship and/or change in usage restriction. The proportion of red kites exposed to SGARs in 2015 (90.6%), 2016 (89.6%) 2017 (96,4%) and 2018 (100%) was always 90% or more; the higher percentages in 2017 and 2018 were principally due to a greater proportion of birds from Scotland containing residues. Brodifacoum and difenacoum were the most prevalent compounds (89% of red kites across the four years for each compound) along with bromadiolone (75%). On average, there were residues of three different SGARs in each kite liver. There was no significant difference between years in liver sum (Σ) SGAR concentrations. We investigated if there was a change between years in the exposure of red kites to brodifacoum, flocoumafen and difethialone, the compounds for which indoor only usage restrictions were relaxed in 2016. To enable statistical analysis of data on residue prevalence, it was necessary to pool the data into two-year blocks. Data on presence/absence of detectable brodifacoum, flocoumafen or difethialone residues were therefore compared for 2015/16 (pre and year of implementation of change in usage restriction) and 2017/18 (post-change in usage restriction). The proportion of red kites with detectable residues was 82% (50 out of 61 red kites) in 2015/16 but significantly higher (95%; 73 out of 77 red kites) in 2017/18. However, there was also an increase [albeit not statistically significant] in the proportion of red kites with detectable liver difenacoum or bromadiolone residues (90% in 2015/16 vs. 97% in 2017/18). Therefore, these data may simply reflect an increase in the prevalence of exposure to SGARs generally rather than any effect of change in usage restriction. There was no difference between the four years in the summed magnitude of liver brodifacoum, difethialone and flocoumafen concentrations. The percentage of red kites examined that were diagnosed as birds in which SGARs were implicated as a contributory cause of death did not differ significantly between individual years nor show a significant trend across the years; the overall average across the four years was 22%. However, if data were pooled by pairs of years (2017/8 vs 2015/16), the proportion of red kites for which SGARs were implicated as a contributory cause of death was lower (18%) in 2017/18 than in 2015/16 (33%) for red kites from England & Wales. Our findings do not indicate that there has been any reduction in exposure in red kites to SGARs following implementation of stewardship, in terms of either the proportion of individuals exposed or the magnitude of residues detected. There is some evidence (depending upon the statistical approach used) that the proportion of red kites in which SGARs were implicated as a contributory mortality factor has decreased in more recent years. There was no clear evidence that relaxation of usage restrictions on brodifacoum, difethialone and flocoumafen has altered the pattern of residue accumulation in red kites to date

Stable propagation of an ordered array of cracks during directional drying

We study the appearance and evolution of an array of parallel cracks in a thin slab of material that is directionally dried, and show that the cracks penetrate the material uniformly if the drying front is sufficiently sharp. We also show that cracks have a tendency to become evenly spaced during the penetration. The typical distance between cracks is mainly governed by the typical distance of the pattern at the surface, and it is not modified during the penetration. Our results agree with recent experimental work, and can be extended to three dimensions to describe the properties of columnar polygonal patterns observed in some geological formations.Comment: 8 pages, 4 figures, to appear in PR

Finite temperature effects in Coulomb blockade quantum dots and signatures of spectral scrambling

The conductance in Coulomb blockade quantum dots exhibits sharp peaks whose spacings fluctuate with the number of electrons. We derive the temperature-dependence of these fluctuations in the statistical regime and compare with recent experimental results. The scrambling due to Coulomb interactions of the single-particle spectrum with the addition of an electron to the dot is shown to affect the temperature-dependence of the peak spacing fluctuations. Spectral scrambling also leads to saturation in the temperature dependence of the peak-to-peak correlator, in agreement with recent experimental results. The signatures of scrambling are derived using discrete Gaussian processes, which generalize the Gaussian ensembles of random matrices to systems that depend on a discrete parameter -- in this case, the number of electrons in the dot.Comment: 14 pages, 4 eps figures included, RevTe