Quantifying brine assimilation by submarine magmas: Examples from the Galápagos Spreading Centre and Lau Basin

Volatiles are critically important in controlling the chemical and physical properties of the mantle. However, determining mantle volatile abundances via the preferred proxy of submarine volcanic glass can be hampered by seawater assimilation. This study shows how combined Cl, Br, I, K and H2O abundances can be used to unambiguously constrain the dominant mechanism by which melts assimilate seawater-derived components, and provide an improved method for determining mantle H2O and Cl abundances. We demonstrate that melts from the northwest part of the Lau Basin, the Galápagos Spreading Centre and melts from other locations previously shown to have anomalously high Cl contents, all assimilated excess Cl and H2O from ultra-saline brines with estimated salinities of 55±15wt.% salts. Assimilation probably occurs at depths of ~3-6km in the crust when seawater-derived fluids come into direct contact with deep magmas. In addition to their ultra-high salinity, the brines are characterised by K/Cl of <0.2, I/Cl of close to the seawater value (~3×10-6) and distinctive Br/Cl ratios of 3.7-3.9×10-3, that are higher than both the seawater value of 3.5×10-3 and the range of Br/Cl in 43 pristine E-MORB and OIB glasses that are considered representative of diverse mantle reservoirs [Br/Clmantle=(2.8±0.6)×10-3 and I/Clmantle=(60±30)×10-6 (2σ)]. The ultra-saline brines, with characteristically elevated Br/Cl ratios, are produced by a combination of fluid-rock reactions during crustal hydration and hydrothermal boiling. The relative importance of these processes is unknown; however, it is envisaged that a vapour phase will be boiled off when crustal fluids are heated to magmatic temperatures during assimilation. Furthermore, the ultra-high salinity of the residual brine that is assimilated may be partly determined by the relative solubilities of H2O and Cl in basaltic melts. The most contaminated glasses from the Galápagos Spreading Centre and Lau Basin have assimilated ~95% of their total Cl and up to 35-40% of their total H2O, equivalent to the melts assimilating 1000-2000ppm brine at an early stage of their evolution. Dacite glasses from Galapagos contain even higher concentrations of brine components (e.g. 12,000ppm), but the H2O and Cl in these melts was probably concentrated by fractional crystallisation after assimilation. The Cl, Br, I and K data presented here confirm the proportion of seawater-derived volatiles assimilated by submarine magmas can vary from zero to nearly 100%, and that assimilation is closely related to hydrothermal activity. Assimilation of seawater components has previously been recognised as a possible source of atmospheric noble gases in basalt glasses. However, hydrothermal brines have metal and helium concentrations up to hundreds of times greater than seawater, and brine assimilation could also influence the helium isotope systematics of some submarine glasse

Rare and Endangered Vetebrates of Ohio

Author Institution: U.S. Soil Conservation Service; Introductory Biology Program, The Ohio State University; School of Natural Resources, The Ohio State University; and Division of Wildlife, Ohio Department of Natural ResourcesThis paper, an annotated list of Ohio's rare and endangered vertebrate species, was compiled to supplement a similar national list and includes 10 mammals, 62 birds, 10 reptiles, 4 amphibians, and 33 fishes. Where possible, suggestions are made both as to causes of the rare or endangered status of these species and as to means of halting the trend. Ratings of endangered, rare, peripheral, or undetermined, as defined for the national classification, are given for each species

Kelvin-Helmholtz Instability of the Magnetopause of Disc-Accreting Stars

This work investigates the short wavelength stability of the magnetopause between a rapidly-rotating, supersonic, dense accretion disc and a slowly-rotating low-density magnetosphere of a magnetized star. The magnetopause is a strong shear layer with rapid changes in the azimuthal velocity, the density, and the magnetic field over a short radial distance and thus the Kelvin-Helmholtz (KH) instability may be important. The plasma dynamics is treated using non-relativistic, compressible (isentropic) magnetohydrodynamics. It is necessary to include the displacement current in order that plasma wave velocities remain less than the speed of light. We focus mainly on the case of a star with an aligned dipole magnetic field so that the magnetic field is axial in the disc midplane and perpendicular to the disc flow velocity. However, we also give results for cases where the magnetic field is at an arbitrary angle to the flow velocity. For the aligned dipole case the magnetopause is most unstable for KH waves propagating in the azimuthal direction perpendicular to the magnetic field which tends to stabilize waves propagating parallel to it. The wave phase velocity is that of the disc matter. A quasi-linear theory of the saturation of the instability leads to a wavenumber ($k$) power spectrum $\propto k^{-1}$ of the density and temperature fluctuations of the magnetopause, and it gives the mass accretion and angular momentum inflow rates across the magnetopause. For self-consistent conditions this mass accretion rate will be equal to the disc accretion rate at large distances from the magnetopause.Comment: 8 pages, 7 figure

Understanding the threats posed by non-native species: public vs. conservation managers.

Public perception is a key factor influencing current conservation policy. Therefore, it is important to determine the influence of the public, end-users and scientists on the prioritisation of conservation issues and the direct implications for policy makers. Here, we assessed public attitudes and the perception of conservation managers to five non-native species in the UK, with these supplemented by those of an ecosystem user, freshwater anglers. We found that threat perception was not influenced by the volume of scientific research or by the actual threats posed by the specific non-native species. Media interest also reflected public perception and vice versa. Anglers were most concerned with perceived threats to their recreational activities but their concerns did not correspond to the greatest demonstrated ecological threat. The perception of conservation managers was an amalgamation of public and angler opinions but was mismatched to quantified ecological risks of the species. As this suggests that invasive species management in the UK is vulnerable to a knowledge gap, researchers must consider the intrinsic characteristics of their study species to determine whether raising public perception will be effective. The case study of the topmouth gudgeon Pseudorasbora parva reveals that media pressure and political debate has greater capacity to ignite policy changes and impact studies on non-native species than scientific evidence alone

Spectral Formation in Accreting X-Ray Pulsars: Bimodal Variation of the Cyclotron Energy with Luminosity

Accretion-powered X-ray pulsars exhibit significant variability of the Cyclotron Resonance Scattering Feature (CRSF) centroid energy on pulse-to-pulse timescales, and also on much longer timescales. Two types of spectral variability are observed. For sources in group 1, the CRSF energy is negatively correlated with the variable source luminosity, and for sources in group 2, the opposite behavior is observed. The physical basis for this bimodal behavior is currently not understood. We explore the hypothesis that the accretion dynamics in the group 1 sources is dominated by radiation pressure near the stellar surface, and that Coulomb interactions decelerate the gas to rest in the group 2 sources. We derive a new expression for the critical luminosity such that radiation pressure decelerates the matter to rest in the supercritical sources. The formula for the critical luminosity is evaluated for 5 sources, using the maximum value of the CRSF centroid energy to estimate the surface magnetic field strength. The results confirm that the group 1 sources are supercritical and the group 2 sources are subcritical, although the situation is less clear for those highly variable sources that cross over the critical line. We also explain the variation of the CRSF energy with luminosity as a consequence of the variation of the characteristic emission height. The sign of the height variation is opposite in the supercritical and subcritical cases, hence creating the observed bimodal behavior.Comment: Accepted for publication in Astronomy & Astrophysic

Molecular evidence of Chlamydia pecorum and arthropod-associated Chlamydiae in an expanded range of marsupials

© 2017 The Author(s). The order Chlamydiales are biphasic intracellular bacterial pathogens infecting humans and domesticated animals. Wildlife infections have also been reported, with the most studied example being Chlamydia pecorum infections in the koala, an iconic Australian marsupial. In koalas, molecular evidence suggests that spill-over from C. pecorum infected livestock imported into Australia may have had a historical or contemporary role. Despite preliminary evidence that other native Australian marsupials also carry C. pecorum, their potential as reservoirs of this pathogen and other Chlamydia-related bacteria (CRBs) has been understudied. Mucosal epithelial samples collected from over 200 native Australian marsupials of different species and geographic regions across Australia were PCR screened for Chlamydiales. Previously described and genetically distinct C. pecorum genotypes and a range of 16S rRNA genotypes sharing similarity to different CRBs in the broader Chlamydiales order were present. One 16S rRNA Chlamydiales genotype recently described in Australian ticks that parasitise native Australian marsupials was also identified. This study provides further evidence that chlamydial infections are widespread in native fauna and that detailed investigations are required to understand the influence these infections have on host species conservation, but also whether infection spill-over plays a role in their epidemiology

Gas emissions and active tectonics within the submerged section of the North Anatolian Fault zone in the Sea of Marmara

The submerged section of the North Anatolian fault within the Marmara Sea was investigated using acoustic techniques and submersible dives. Most gas emissions in the water column were found near the surface expression of known active faults. Gas emissions are unevenly distributed. The linear fault segment crossing the Central High and forming a seismic gap – as it has not ruptured since 1766, based on historical seismicity, exhibits relatively less gas emissions than the adjacent segments. In the eastern Sea of Marmara, active gas emissions are also found above a buried transtensional fault zone, which displayed micro-seismic activity after the 1999 events. Remarkably, this zone of gas emission extends westward all along the southern edge of Cinarcik basin, well beyond the zone where 1999 aftershocks were observed. The long term monitoring of gas seeps could hence be highly valuable for the understanding of the evolution of the fluid-fault coupling processes during the earthquake cycle within the Marmara Sea

'A hidden disorder until the pieces fall into place' - a qualitative study of vaginal prolapse

<p>Abstract</p> <p>Background</p> <p>Vaginal prolapse affects quality of life negatively and is associated with urinary, bowel, and sexual symptoms. Few qualitative studies have explored women's experiences of vaginal prolapse. The objective of the study was to elucidate the experiences of living with prolapse and its impact on daily life, prior to surgical intervention.</p> <p>Methods</p> <p>In-depth interviews were conducted with 14 women with vaginal prolapse, prior to surgical treatment. Recruitment of the informants was according to 'purposive sampling'. An interview guide was developed, including open-ended questions addressing different themes, which was processed and revised during the data collection and constituted part of a study-emergent design. Data were collected until 'saturation' was achieved, that is, when no significant new information was obtained by conducting further interviews. Interviews were audiotaped, transcribed verbatim, and analyzed according to manifest and latent content analysis.</p> <p>Results</p> <p>The theme defining the process of living with prolapse and women's experiences was labelled 'process of comprehension and action'. The findings constitute two categories: obstacles and facilitators to seeking health care. The category <it>obstacles </it>comprises six subcategories that define the factors restraining women from seeking health care: absence of information, blaming oneself, feeling ignored by the doctor, having a covert condition, adapting to successive impairment, and trivializing the symptoms and de-prioritizing own health. The category <it>facilitators </it>include five subcategories that define the factors promoting the seeking of health care: confirmation and support by others, difficulty in accepting an ageing body, feeling sexually unattractive, having an unnatural body, and reaching the point of action.</p> <p>Conclusion</p> <p>The main theme identified was the 'process of comprehension and action'. This process consisted of factors functioning as either obstacles or facilitators to seeking health care. The main obstacles described by the participants were lack of information and confirmation. The main facilitators constituted feeling sexually unattractive and impaired physical ability due to prolapse. Information on prolapse should be easily accessible, to improve the possibility for women to gain knowledge about the condition and overcome obstacles to seeking health care. Health care professionals have a significant role in facilitating the process by confirming and informing women about available treatment.</p