701 research outputs found

    Mercury (Hg) concentrations and stable isotope signatures in golden eagle eggs 2009-2013: a Predatory Bird Monitoring Scheme (PBMS) report

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    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 activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Mercury (Hg) is a neurotoxin and there has been global concern over its impact on humans and wildlife. It has been predicted that global Hg emissions may rise in the future because of increased coal-fired power generation, but, in 2013, the United Nations Environment Programme (UNEP) agreed The Minamata Convention on Mercury, a global treaty to protect human health and the environment from the adverse effects of mercury. An overarching aim of the convention is to control the anthropogenic releases of Hg to the environment. Therefore, long-term trends in environmental Hg concentrations are uncertain. One cost-effective means of assessing such trends is to monitor exposure in sentinel wildlife species. Golden eagles Aquila chrysaetos breed and forage in the Scottish uplands and could prove a sentinel for changing Hg deposition in upland terrestrial areas and associated wildlife exposure. We measured Hg residues in failed golden eagle eggs with the aim of providing baseline data on current levels of exposure. Specifically, we measured Hg concentrations in failed eggs laid between 2009 and 2013 in inland (> 3km from the coast) and coastal (<3 km from the coast) nests. We distinguished nests in this way because coastal nesting birds can feed on seabirds that can accumulate high levels of Hg themselves. Marine dietary Hg inputs could potentially obscure any changes in Hg accumulation associated with altered upland terrestrial Hg deposition, and so we hypothesized that only eggs from inland nests may be useful sentinels. In conjunction with Hg measurements, we examined stable isotope (SI) signatures (carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S)) to determine if they differed between eggs from inland and coastal nests in a manner consistent with feeding primarily on terrestrial and marine prey, respectively. We also examined Hg concentrations and SI signatures of failed white-tailed sea eagle (Haliaeetus albicilla) eggs from nests on the west coast of Scotland. We used these measurements as a comparator against which to assess the extent to which SI and Hg measurements in eggs from coastal golden eagle nests might be indicative of feeding on marine prey and scavenge. We found that SI signatures (particularly δ34S isotopic ratios) and Hg concentrations were similar in golden eagle eggs from coastal nests and white tailed sea eagle eggs. SIs and Hg concentrations in eggs from inland nests were much more variable, and a third had SI signatures that were the same as those of eggs from coastal nests, suggesting that they too were laid by females feeding on a coastal diet. A cluster of seven eggs from inland nests had distinctive δ34S and δ15N values (below 11.0 ‰ and 5.7 ‰ respectively) and it was inferred that these were most likely laid by females feeding terrestrially. Hg concentrations were non-detectable in these seven eggs whereas the median concentration in golden eagle eggs associated with coastal feeding was 0.412 µg/g dry weight, similar to that (0.569 µg/g dry weight) in white tailed sea eagle eggs. Hg concentrations in all eggs were below those thought to be associated with embryotoxic effects. The lack of detectable Hg concentrations in GE eggs associated with upland terrestrial feeding is problematic if these eggs are to be used as sentinels of change in upland Hg concentrations. Re-analysis of a set of eggs using a more sensitive analytical technique may resolve this issue and should be explored, otherwise other sentinels may need to be investigated

    Description of superdeformed nuclei in the interacting boson model

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    The interacting boson model is extended to describe the spectroscopy of superdeformed bands. Microscopic structure of the model in the second minimum is discussed and superdeformed bosons are introduced as the new building blocks. Solutions of a quadrupole Hamiltonian are implemented through the 1/N1/N expansion method. Effects of the quadrupole parameters on dynamic moment of inertia and electric quadrupole transition rates are discussed and the results are used in a description of superdeformed bands in the Hg-Pb and Gd-Dy regions.Comment: 18 pages revtex, 9 figures available upon reques

    A Geometric Picture of Entanglement and Bell Inequalities

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    We work in the real Hilbert space H_s of hermitian Hilbert-Schmid operators and show that the entanglement witness which shows the maximal violation of a generalized Bell inequality (GBI) is a tangent functional to the convex set S subset H_s of separable states. This violation equals the euclidean distance in H_s of the entangled state to S and thus entanglement, GBI and tangent functional are only different aspects of the same geometric picture. This is explicitly illustrated in the example of two spins, where also a comparison with familiar Bell inequalities is presented.Comment: 17 pages, 5 figures, 4 references adde

    ‘What are you going to do, confiscate their passports?’ Professional perspectives on cross-border reproductive travel

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    Objective: This article reports findings from a UK-based study which explored the phenomenon of overseas travel for fertility treatment. The first phase of this project aimed to explore how infertility clinicians and others professionally involved in fertility treatment understand the nature and consequences of cross-border reproductive travel. Background: There are indications that, for a variety of reasons, people from the UK are increasingly travelling across national borders to access assisted reproductive technologies. While research with patients is growing, little is known about how ‘fertility tourism’ is perceived by health professionals and others with a close association with infertility patients. Methods: Using an interpretivist approach, this exploratory research included focussed discussions with 20 people professionally knowledgeable about patients who had either been abroad or were considering having treatment outside the UK. Semi-structured interviews were recorded, transcribed verbatim and subjected to a thematic analysis. Results: Three conceptual categories are developed from the data: ‘the autonomous patient’; ‘cross-border travel as risk’, and ‘professional responsibilities in harm minimisation’. Professionals construct nuanced, complex and sometimes contradictory narratives of the ‘fertility traveller’, as vulnerable and knowledgeable; as engaged in risky behaviour and in its active minimisation. Conclusions: There is little support for the suggestion that states should seek to prevent cross-border treatment. Rather, an argument is made for less direct strategies to safeguard patient interests. Further research is required to assess the impact of professional views and actions on patient choices and patient experiences of treatment, before, during and after travelling abroad

    Active region formation through the negative effective magnetic pressure instability

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    The negative effective magnetic pressure instability operates on scales encompassing many turbulent eddies and is here discussed in connection with the formation of active regions near the surface layers of the Sun. This instability is related to the negative contribution of turbulence to the mean magnetic pressure that causes the formation of large-scale magnetic structures. For an isothermal layer, direct numerical simulations and mean-field simulations of this phenomenon are shown to agree in many details in that their onset occurs at the same depth. This depth increases with increasing field strength, such that the maximum growth rate of this instability is independent of the field strength, provided the magnetic structures are fully contained within the domain. A linear stability analysis is shown to support this finding. The instability also leads to a redistribution of turbulent intensity and gas pressure that could provide direct observational signatures.Comment: 19 pages, 10 figures, submitted to Solar Physic

    The Muonium Atom as a Probe of Physics beyond the Standard Model

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    The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium (M=μ+eM = \mu^+ e^-) can be used as an ideal probe of quantum electrodynamics and weak interaction and also for a search for additional interactions between leptons. Of special interest is the lepton number violating process of sponteanous conversion of muonium to antimuonium.Comment: 15 pages,6 figure

    Variation in Population Attributable Fraction of Dementia Associated with Potentially Modifiable Risk Factors by Race and Ethnicity in the US

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    Importance: Identifying modifiable risk factors that are associated with dementia burden across racial and ethnic groups in the population can yield insights into the potential effectiveness of interventions in preventing dementia and reducing disparities. Objective: To calculate the population attributable fraction (PAF) of dementia associated with 12 established modifiable risk factors for all US adults, as well as separately by race and ethnicity. Design, Setting, and Participants: This cross-sectional study used survey data from nationally representative samples of US adults. PAFs were calculated using relative risks and prevalence estimates for 12 risk factors. Relative risks were taken from meta-analyses, as reported in a 2020 systematic review. Prevalence estimates for risk factors were derived from nationally representative cross-sectional survey data collected between 2011 and 2018. Combined PAFs were adjusted for risk factor communality using weights derived from the Atherosclerosis Risk in Communities (ARIC) study (1987-2018). Analyses were conducted May through October 2021. Exposures: Low education, hearing loss, traumatic brain injury, hypertension, excessive alcohol consumption, obesity, smoking, depression, social isolation, physical inactivity, diabetes, and air pollution. Main Outcomes and Measures: PAF for each dementia risk factor, a combined PAF, and the decrease in the number of prevalent dementia cases in 2020 that would be expected given a 15% proportional decrease in each exposure. Results: Among all US adults, an estimated 41.0% (95% CI, 22.7%-55.9%) of dementia cases were attributable to 12 risk factors. A 15% proportional decrease in each risk factor would reduce dementia prevalence in the population by an estimated 7.3% (95% CI, 3.7%-10.9%). The estimated PAF was greater for Black and Hispanic than it was for White and Asian individuals. The greatest attributable fraction of dementia cases was observed for hypertension (PAF, 20.2%; 95% CI, 6.3%-34.4%), obesity (PAF, 20.9%; 95% CI, 13.0%-28.8%), and physical inactivity (PAF, 20.1%; 95% CI, 9.1%-29.6%). These factors were also highest within each racial and ethnic group, although the proportions varied. Conclusions and Relevance: A large fraction of dementia cases in the US were associated with potentially modifiable risk factors, especially for Black and Hispanic individuals. Targeting and reducing these risk factors may curb the projected rise in dementia cases over the next several decades

    An analysis of the FIR/RADIO Continuum Correlation in the Small Magellanic Cloud

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    The local correlation between far-infrared (FIR) emission and radio-continuum (RC) emission for the Small Magellanic Cloud (SMC) is investigated over scales from 3 kpc to 0.01 kpc. Here, we report good FIR/RC correlation down to ~15 pc. The reciprocal slope of the FIR/RC emission correlation (RC/FIR) in the SMC is shown to be greatest in the most active star forming regions with a power law slope of ~1.14 indicating that the RC emission increases faster than the FIR emission. The slope of the other regions and the SMC are much flatter and in the range of 0.63-0.85. The slopes tend to follow the thermal fractions of the regions which range from 0.5 to 0.95. The thermal fraction of the RC emission alone can provide the expected FIR/RC correlation. The results are consistent with a common source for ultraviolet (UV) photons heating dust and Cosmic Ray electrons (CRe-s) diffusing away from the star forming regions. Since the CRe-s appear to escape the SMC so readily, the results here may not provide support for coupling between the local gas density and the magnetic field intensity.Comment: 19 pages, 7 Figure

    Academic freedom: in justification of a universal ideal

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    This paper examines the justification for, and benefits of, academic freedom to academics, students, universities and the world at large. The paper surveys the development of the concept of academic freedom within Europe, more especially the impact of the reforms at the University of Berlin instigated by Wilhelm von Humboldt. Following from this, the paper examines the reasons why the various facets of academic freedom are important and why the principle should continue to be supported
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