Geochemistry of H2- and CH4-enriched hydrothermal fluids of Socorro Island, Revillagigedo Archipelago, Mexico. Evidence for serpentinization and abiogenic methane

Socorro Island is the exposed part of an approx. 4000-m-high volcanic edifice rising from the oceanic floor to approx. 1000 m asl at the northern part of the Mathematician Ridge, Western Pacific. The volcano is active, with the most recent basaltic eruption in 1993. Moderate fumarolic activity and diffuse degassing with a total CO2 flux of approx. 20 total day)1 are concentrated in the summit region of the volcano composed of a group of rhy- olite domes. Low-temperature, boiling point, fumaroles discharge gas with high H2 (up to 20 mol% in dry gas) and CH4 (up to 4 mol%). Both carbon and He isotopic ratios and abundances correspond to those in MORB flu- ids (d13CCO2 )5&; 3He ⁄ 4He = 7.6 Ra, CO2 ⁄ 3He = (2–3) · 109, where Ra is the atmospheric ratio 3He ⁄ 4He of 1.4 · 10)6. Light hydrocarbons (CH4, C2H6, C3H8, and C4H10) are characterized by a high C1 ⁄C2+ ratio of approx. 1000. Methane is enriched in 13C (d13CCH4 from )15 to )20&) and 2H (d2H from )80 to )120&), and hydrocarbons show an inverse isotopic trend in both d13C and d2H (ethane is isotopically lighter than methane). These isotopic and concentration features of light hydrocarbons are similar to those recently discovered in fluids from ultramafic-hosted spreading ridge vents and may be related to the serpentinization processes: H2 generation and reduction of CO2 to CH4 within high-temperature zone of volcano-seawater hydrothermal system hosted in basaltic and ultramafic rocks beneath a volcano edifice. The thermodynamic analysis of this unusual composition of the Socorro fluids and the assessment of endmember compositions are complicated by the near-surface cool- ing, condensation and mixing with meteoric water

Willow on yellowstone's northern range: Evidence for a trophic cascade?

Reintroduction of wolves (Canis lupus) to Yellowstone National Park in 1995-1996 has been argued to promote a trophic cascade by altering elk (Cervus elaphus) density, habitat-selection patterns, and behavior that, in turn, could lead to changes within the plant communities used by elk. We sampled two species of willow (Salix boothii and S. geyeriana) on the northern winter range to determine whether (1) there was quantitative evidence of increased willow growth following wolf reintroduction, (2) browsing by elk affected willow growth, and (3) any increase in growth observed was greater than that expected by climatic and hydrological factors alone, thereby indicating a trophic cascade caused by wolves. Using stem sectioning techniques to quantify historical growth patterns we found an approximately twofold increase in stem growth-ring area following wolf reintroduction for both species of willow. This increase could not be explained by climate and hydrological factors alone; the presence of wolves on the landscape was a significant predictor of stem growth above and beyond these abiotic factors. Growth-ring area was positively correlated with the previous year's ring area and negatively correlated with the percentage of twigs browsed from the stem during the winter preceding growth, indicating that elk browse impeded stem growth. Our results are consistent with the hypothesis of a behaviorally mediated trophic cascade on Yellowstone's northern winter range following wolf reintroduction. We suggest that the community-altering effects of wolf restoration are an endorsement of ecological-process management in Yellowstone National Park

Detection of an atmosphere around the super-Earth 55 Cancri e

We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length and a very high scanning speed. We use our specialized pipeline to take into account systematics introduced by these observational parameters when coupled with the geometrical distortions of the instrument. We measure the transit depth per wavelength channel with an average relative uncertainty of 22 ppm per visit and find modulations that depart from a straight line model with a 6$\sigma$ confidence level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably hydrogen-rich. Our fully Bayesian spectral retrieval code, T-REx, has identified HCN to be the most likely molecular candidate able to explain the features at 1.42 and 1.54 $\mu$m. While additional spectroscopic observations in a broader wavelength range in the infrared will be needed to confirm the HCN detection, we discuss here the implications of such result. Our chemical model, developed with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic than previously thought.Comment: 10 pages, 10 figures, 4 tables, Accepted for publication in Ap

Dynamics of a map with power-law tail

We analyze a one-dimensional piecewise continuous discrete model proposed originally in studies on population ecology. The map is composed of a linear part and a power-law decreasing piece, and has three parameters. The system presents both regular and chaotic behavior. We study numerically and, in part, analytically different bifurcation structures. Particularly interesting is the description of the abrupt transition order-to-chaos mediated by an attractor made of an infinite number of limit cycles with only a finite number of different periods. It is shown that the power-law piece in the map is at the origin of this type of bifurcation. The system exhibits interior crises and crisis-induced intermittency.Comment: 28 pages, 17 figure

Self-Administered Computer Therapy for Apraxia of Speech

Background and Purpose There is currently little evidence on effective interventions for poststroke apraxia of speech. We report outcomes of a trial of self-administered computer therapy for apraxia of speech. Methods Effects of speech intervention on naming and repetition of treated and untreated words were compared with those of a visuospatial sham program. The study used a parallel-group, 2-period, crossover design, with participants receiving 2 interventions. Fifty participants with chronic and stable apraxia of speech were randomly allocated to 1 of 2 order conditions: speech-first condition versus sham-first condition. Period 1 design was equivalent to a randomized controlled trial. We report results for this period and profile the effect of the period 2 crossover. Results Period 1 results revealed significant improvement in naming and repetition only in the speech-first group. The sham-first group displayed improvement in speech production after speech intervention in period 2. Significant improvement of treated words was found in both naming and repetition, with little generalization to structurally similar and dissimilar untreated words. Speech gains were largely maintained after withdrawal of intervention. There was a significant relationship between treatment dose and response. However, average self-administered dose was modest for both groups. Future software design would benefit from incorporation of social and gaming components to boost motivation. Conclusions Single-word production can be improved in chronic apraxia of speech with behavioral intervention. Self-administered computerized therapy is a promising method for delivering high-intensity speech/language rehabilitation

Revisiting the need for a literature search narrative: A brief methodological note

This is the author accepted manuscript. The final version is available from Wiley via the DOI inthis recordIn this method note, we question if the primary search strategy in a systematic review should be accompanied by a search narrative. A search narrative could offer a conceptual and contextual report on the search strategy, which we suggest might benefit the peer review of literature searches and increase engagement with, and discussion of, the literature search strategy from review stakeholders, topic experts, and lay users of research. Search narratives would also increase the transparency of decision-making in literature searching.Centre for Outcomes Research and Effectiveness (CORE)National Institute for Health Research (NIHR)Cochrane Common Mental Disorders (CCMD) Grou

Highly consistent genetic alterations in childhood adrenocortical tumours detected by comparative genomic hybridization

We have examined 11 cases of childhood adrenocortical tumours for copy number changes using comparative genomic hybridization (CGH). The changes seen are highly consistent between cases, and are independent of tumour type (carcinoma versus adenoma) or the presence of a germline TP53 mutation. The regions of chromosomal gain and loss identified in this study indicate the location of genes that are potentially important in the development and progression of childhood adrenocortical tumours. Finally, the copy number changes identified in childhood tumours are distinctly different to those seen in adult cases (Kjellman et al (1996) Cancer Res56: 4219–4223), and we propose that this indicates that childhood tumours are of embryonal origin. © 1999 Cancer Research Campaig

``Good Propagation'' Constraints on Dual Invariant Actions in Electrodynamics and on Massless Fields

We present some consequences of non-anomalous propagation requirements on various massless fields. Among the models of nonlinear electrodynamics we show that only Maxwell and Born-Infeld also obey duality invariance. Separately we show that, for actions depending only on the F_\mn^2 invariant, the permitted models have $L \sim \sqrt{1 + F^2}$. We also characterize acceptable vector-scalar systems. Finally we find that wide classes of gravity models share with Einstein the null nature of their characteristic surfaces.Comment: 11 pages, LaTeX, no figure

Low-dose computed tomography for lung cancer screening in high risk populations: a systematic review and economic evaluation

This is the final version. Available from NIHR Journals Library via the DOI in this record.The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.564Background Diagnosis of lung cancer frequently occurs in its later stages. Low-dose computed tomography (LDCT) could detect lung cancer early. Objectives To estimate the effectiveness and cost-effectiveness of LDCT lung cancer screening in high risk populations. Methods Clinical effectiveness A systematic review of randomised controlled trials (RCTs) comparing LDCT screening programmes with usual care (no screening) or other imaging screening programme (such as chest X-ray (CXR)) was conducted. Bibliographic sources included MEDLINE, Embase, Web of Science and the Cochrane Library. Meta-analyses, including network meta-analyses, were performed. Cost-effectiveness An independent economic model employing discrete event simulation and using a natural history model calibrated to results from a large RCT was developed. There were twelve different population eligibility criteria and four intervention frequencies (single screen, triple screen, annual screening and biennial screening) and a no screening control arm. Results Clinical effectiveness Twelve RCTs were included, four of which currently contribute evidence on mortality. Meta-analysis of these demonstrated that LDCT with up to 9.80 years of follow-up was associated with a non-statistically significant decrease in lung cancer mortality (pooled RR 0.94, 95% CI 0.74 to 1.19). The findings also showed that LDCT screening demonstrated a non-statistically significant increasein all-cause mortality. Given the considerable heterogeneity detected between studies for both outcomes, the results should be treated with caution. Network meta-analysis including six RCTs was performed to assess the relative effectiveness of LDCT, CXR and usual care. The results showed that LDCT was ranked as the best screening strategy in terms of lung cancer mortality reduction. CXR had a 99.7% probability of being the worst intervention with usual care intermediate. Cost-effectiveness Screening programmes are predicted to be more effective than no screening, reduce lung cancer mortality and result in more lung cancer diagnoses. Screening programmes also increase costs. Screening for lung cancer is unlikely to be cost-effective at a threshold of £20,000/QALY, but may be cost-effective at a threshold of £30,000/QALY. The incremental cost-effectiveness ratio for a single screen in smokers aged 60–75 years with at least a 3% risk of lung cancer is £28,169 per QALY. Sensitivity and scenario analyses were conducted. Screening was only cost-effective at a threshold of £20,000/QALY in a minority of analyses. Limitations Clinical effectiveness The largest of the included RCTs compared LDCT with CXR screening rather than no screening. Cost-effectiveness A representative cost to the NHS of lung cancer has not been recently estimated according to key variables such as stage at diagnosis. Certain costs associated with running a screening programme have not been included. Conclusions LDCT screening may be clinically effective in reducing lung cancer mortality but there is considerable uncertainty. There is evidence that a single round of screening could be considered cost-effective at conventional thresholds, but there is significant uncertainty about the effect on costs and the magnitude of benefits. Future work Effectiveness and cost-effectiveness estimates should be updated with the anticipated results from several ongoing RCTs (particularly NELSON).This report was commissioned by the NIHR Health Technology Assessment Programme as project number 14/151/0

EChOSim: The Exoplanet Characterisation Observatory software simulator

EChOSim is the end-to-end time-domain simulator of the Exoplanet Characterisation Observatory (EChO) space mission. EChOSim has been developed to assess the capability EChO has to detect and characterize the atmospheres of transiting exoplanets, and through this revolutionize the knowledge we have of the Milky Way and of our place in the Galaxy. Here we discuss the details of the EChOSim implementation and describe the models used to represent the instrument and to simulate the detection. Software simulators have assumed a central role in the design of new instrumentation and in assessing the level of systematics affecting the measurements of existing experiments. Thanks to its high modularity, EChOSim can simulate basic aspects of several existing and proposed spectrometers for exoplanet transits, including instruments on the Hubble Space Telescope and Spitzer, or ground-based and balloon borne experiments. A discussion of different uses of EChOSim is given, including examples of simulations performed to assess the EChO mission