Solid-phase microextraction for bioconcentration studies according to OECD TG 305

An important aim of the European Community Regulation on chemicals and their safe use is the identification of (very) persistent, (very) bioaccumulative, and toxic substances. In other regulatory chemical safety assessments (pharmaceuticals, biocides, pesticides), the identification of such (very) persistent, (very) bioaccumulative, and toxic substances is of increasing importance. Solid-phase microextraction is especially capable of extracting total water concentrations as well as the freely dissolved fraction of analytes in the water phase, which is available for bioconcentration in fish. However, although already well established in environmental analyses to determine and quantify analytes mainly in aqueous matrices, solid-phase microextraction is still a rather unusual method in regulatory ecotoxicological research. Here, the potential benefits and drawbacks of solid-phase microextraction are discussed as an analytical routine approach for aquatic bioconcentration studies according to OECD TG 305, with a special focus on the testing of hydrophobic organic compounds characterized by log KOW > 5

Neither Shoreditch nor Manhattan: Post-politics, 'soft austerity urbanism' and real abstraction in Glasgow North

Speirs Locks is being re-constructed as a new cultural quarter in Glasgow North, with urban boosters envisioning the unlikely, rundown and de-populated light industrial estate as a key site in the city's ongoing cultural regeneration strategy. Yet this creative place-making initiative, I argue, masks a post-political conjuncture based on urban speculation, displacement and the foreclosure of dissent. Post-politics at Speirs Locks is characterised by what I term ‘soft austerity urbanism’: seemingly progressive, instrumental small-scale urban catalyst initiatives that in reality complement rather than counter punitive hard austerity urbanism. Relating such processes of soft austerity urbanism to a wider context of state-led gentrification, this study contributes to post-political debates in several ways. Firstly, it questions demands for participation as a proper politics when it has become practically compulsory in contemporary biopolitical capitalism. Secondly, it demonstrates how an extreme economy of austerity urbanism remains the hard underside of post-political, soft austerity urbanism approaches. Thirdly, it illustrates how these approaches relate to wider processes of ‘real abstraction’ – which is no mere flattery of the mind, but instead is rooted in actually existing processes of commodity exchange. Such abstraction, epitomised in the financialisation and privatisation of land and housing, buttresses the same ongoing property dynamics that were so integral to the global financial crisis and ensuing austerity policies in the first place. If we aim to generate a proper politics that creates a genuine rupture with the destructive play of capital in the built environment, the secret of real abstraction must be critically addressed

The Linearity of the Wesenheit function for the Large Magellanic Cloud Cepheids

There is strong evidence that the period-luminosity (PL) relation for the Large Magellanic Cloud (LMC) Cepheids shows a break at a period around 10 days. Since the LMC PL relation is extensively used in distance scale studies, the non-linearity of the LMC PL relation may affect the results based on this LMC calibrated relation. In this paper we show that this problem can be remedied by using the Wesenheit function in obtaining Cepheid distances. This is because the Wesenheit function is linear although recent data suggests that the PL and the period-colour (PC) relations that make up the Wesenheit function are not. We test the linearity of the Wesenheit function and find strong evidence that the LMC Wesenheit function is indeed linear. This is because the non-linearity of the PL and PC relations cancel out when the Wesenheit function is constructed. We discuss this result in the context of distance scale applications. We also compare the distance moduli obtained from mu_0=mu_V-R(mu_V-mu_I) (equivalent to Wesenheit functions) constructed with the linear and the broken LMC PL relations, and find that the typical difference in distance moduli is ~ +-0.03mag. Hence, the broken LMC PL relation does not seriously affect current distance scale applications. We also discuss the random error calculated with equation mu_0=mu_V-R(mu_V-mu_I), and show that there is a correlation term that exists from the calculation of the random error. The calculated random error will be larger if this correlation term is ignored.Comment: 8 pages, 3 figures and 5 tables, MNRAS accepte

Development and implementation of blood pressure screening and referral guidelines for German community pharmacists

Involvement of community pharmacists in the detection and control of hypertension improves patient care. However, current European or North‐American guidelines do not provide specific guidance how to implement collaboration between pharmacists and physicians, especially when and how to refer patients with undetected or uncontrolled hypertension to a physician. The German Society of Cardiology and the ABDA – Federal Union of German Associations of Pharmacists developed and tested referral recommendations for community pharmacists, embedded in two guideline worksheets. The project included a guideline‐directed blood pressure (BP) measurement and recommendations when patients should be referred to their physician. A “red flag” referral within 4 weeks was recommended when SBP was >140 mm Hg or DBP >90 mm Hg (for subjects 160 mm Hg or >90 mm Hg (≥80 years) in undetected individuals, or >130 mm Hg or >80 mm Hg (140 mm Hg or >80 mm Hg (≥65 years) in treated patients. BP was measured in 187 individuals (86 with known hypertension, mean [±SD] age 62 ± 15 years, 64% female, and 101 without known hypertension, 47 ± 16 years, 75% female) from 17 community pharmacies. In patients with hypertension, poorly controlled BP was detected in 55% (n = 47) and were referred. A total of 16/101 subjects without a history of hypertension were referred to their physician because of uncontrolled BP. Structured BP testing in pharmacies identified a significant number of subjects with undetected/undiagnosed hypertension and patients with poorly controlled BP. Community pharmacists could play a significant role in collaboration with physicians to improve the management of hypertension

Late stages of the evolution of A-type stars on the main sequence: comparison between observed chemical abundances and diffusion models for 8 Am stars of the Praesepe cluster

Aims. We aim to provide observational constraints on diffusion models that predict peculiar chemical abundances in the atmospheres of Am stars. We also intend to check if chemical peculiarities and slow rotation can be explained by the presence of a weak magnetic field. Methods. We have obtained high resolution, high signal-to-noise ratio spectra of eight previously-classified Am stars, two normal A-type stars and one Blue Straggler, considered to be members of the Praesepe cluster. For all of these stars we have determined fundamental parameters and photospheric abundances for a large number of chemical elements, with a higher precision than was ever obtained before for this cluster. For seven of these stars we also obtained spectra in circular polarization and applied the LSD technique to constrain the longitudinal magnetic field. Results. No magnetic field was detected in any of the analysed stars. HD 73666, a Blue Straggler previously considered as an Ap (Si) star, turns out to have the abundances of a normal A-type star. Am classification is not confirmed for HD 72942. For HD 73709 we have also calculated synthetic Delta-a photometry that is in good agreement with the observations. There is a generally good agreement between abundance predictions of diffusion models and values that we have obtained for the remaining Am stars. However, the observed Na and S abundances deviate from the predictions by 0.6 dex and >0.25 dex respectively. Li appears to be overabundant in three stars of our sample.Comment: Accepted for publication on A&

Field Blue Stragglers and Related Mass Transfer Issues

This chapter contains my impressions and perspectives about the current state of knowledge about field blue stragglers (FBS) stars, drawn from an extensive literature that I searched. I conclude my review of issues that attend FBS and mass transfer, by a brief enumeration of a few mildly disquieting observational facts.Comment: Chapter 4, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

Varying driver velocity fields in photospheric MHD wave simulations

Torsional motions are ubiquitous in the solar atmosphere. In this work, we perform 3D numerical simulations which mimic a vortex-type photospheric driver with a Gaussian spatial profile. This driver is implemented to excite MHD waves in an axially symmetric, 3D magnetic flux tube embedded in a realistic solar atmosphere. The Gaussian width of the driver is varied and the resulting perturbations are compared. Velocity vectors were decomposed into parallel, perpendicular and azimuthal components with respect to pre-defined magnetic flux surfaces. These components correspond broadly to the fast, slow and Alfvén modes, respectively. From these velocities the corresponding wave energy fluxes are calculated, allowing us to estimate the contribution of each mode to the energy flux. For the narrowest driver (0.15 Mm) the parallel component accounts for ∼55 − 65% of the flux. This contribution increases smoothly with driver width up to nearly 90% for the widest driver (0.35 Mm). The relative importance of the perpendicular and azimuthal components decrease at similar rates. The azimuthal energy flux varied between ∼35% for the narrowest driver and <10% for the widest one. Similarly, the perpendicular flux was ∼25 − 10%. We also demonstrate that the fast mode corresponds to the sausage wave in our simulations. Our results therefore show that the fast sausage wave is easily excited by this driver and that it carries the majority of the energy transported. For this vortex-type driver the Alfvén wave does not contribute a significant amount of energy

The evolution of runaway stellar collision products

In the cores of young dense star clusters repeated stellar collisions involving the same object can occur, which has been suggested to lead to the formation of an intermediate-mass black hole. In order to verify this scenario we compute the detailed evolution of the merger remnant of three sequences. We follow the evolution until the onset of carbon burning and estimate the final remnant mass to determine the ultimate fate of a runaway merger sequence. We use a detailed stellar evolution code to follow the evolution of the collision product. At each collision, we mix the two colliding stars, taking account of mass loss during the collision. During the stellar evolution we apply mass loss rates from the literature, as appropriate for the evolutionary stage of the merger remnant. We compute models for high ($Z=0.02$) and low ($Z=0.001$) metallicity to quantify metallicity effects. We find that the merger remnant becomes a Wolf-Rayet star before the end of core hydrogen burning. Mass loss from stellar winds dominates over the mass increase due to repeated mergers for all three merger sequences that we consider. In none of our high metallicity models an intermediate-mass black hole is formed, instead our models have a mass of 10--14 \Msun{} at the onset of carbon burning. For low metallicity we expect the final remnant of the merger sequence to explode as a pair creation supernova. We find that our metal-rich models become inflated as a result of developing an extended low-density envelope. This may increase the probability of further collisions, but self-consistent $N$-body calculations with detailed evolution of runaway mergers are required to verify this.Comment: 10 pages, 6 figures, accepted for publication in A&A Updated with accepted versio

Structural diversity of ABC transporters

ATP-binding cassette (ABC) transporters form a large superfamily of ATP-dependent protein complexes that mediate transport of a vast array of substrates across membranes. The 14 currently available structures of ABC transporters have greatly advanced insight into the transport mechanism and revealed a tremendous structural diversity. Whereas the domains that hydrolyze ATP are structurally related in all ABC transporters, the membrane-embedded domains, where the substrates are translocated, adopt four different unrelated folds. Here, we review the structural characteristics of ABC transporters and discuss the implications of this structural diversity for mechanistic diversity.</p

First stars VII. Lithium in extremely metal poor dwarfs

Aims. This study aims to determine the level and constancy of the Spite plateau as definitively as possible from homogeneous high-quality VLT-UVES spectra of 19 of the most metal-poor dwarf stars known. Methods. Our high-resolution (R ~ 43000), high S/N spectra are analysed with OSMARCS 1D LTE model atmospheres and turbospectrum synthetic spectra to determine effective temperatures, surface gravities, and metallicities, as well as Li abundances for our stars. Results. Eliminating a cool subgiant and a spectroscopic binary, we find 8 stars to have -3.5 < [Fe/H] < -3.0 and 9 stars with -3.0 < [Fe/H] < -2.5. Our best value for the mean level of the plateau is A(Li) =2.10 +- 0.09. The scatter around the mean is entirely explained by our estimate of the observational error and does not allow for any intrinsic scatter in the Li abundances. In addition, we conclude that a systematic error of the order of 200 K in any of the current temperature scales remains possible. The iron excitation equilibria in our stars support our adopted temperature scale, which is based on a fit to wings of the Halpha line, and disfavour hotter scales, which would lead to a higher Li abundance, but fail to achieve excitation equilibrium for iron. Conclusions. We confirm the previously noted discrepancy between the Li abundance measured in extremely metal-poor turnoff stars and the primordial Li abundance predicted by standard Big-Bang nucleosynthesis models adopting the baryonic density inferred from WMAP. We discuss recent work explaining the discrepancy in terms of diffusion and find that uncertain temperature scales remain a major question. (abridged)Comment: Figure 3 replaced, it was wrong in version 1. Minor corrections to the text following indications of A&A Language Edito