424 research outputs found

    OBSERVATIONS ON NAVICULA THALLODES (BACILLARIOPHYCEAE), A BLADE-FORMING DIATOM FROM THE BERING SEA 1

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    A thallus-forming diatom, Navicula thallodes Proschkina-Lavrenko, previously known only from the original collection at Bering Island (U.S.S.R.), has been found at Amchitka Island in the Aleutians, Alaska. The most remarkable observation of the present report is that N. thallodes may form blades up to 50 cm long, which to our knowledge is the greatest length reported for a colonial diatom. SEM observations of this diatom are presented for the first time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65176/1/j.1529-8817.1988.tb04487.x.pd

    Probing the face-on disc-corona system of the bare AGN Mrk 110 from UV to hard X-rays: A moderate changing-state AGN?

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    Context. The X-ray broadband spectra of the bare active galactic nucleus (AGN) Mrk 110, obtained by simultaneous XMM-Newton and NuSTAR observations performed in November 2019 and April 2020, are characterised by the presence of a prominent and absorption-free smooth soft X-ray excess, moderately broad O VII and Fe Kα emission lines, and a lack of a strong Compton hump. The disc-corona system is almost viewed face-on as inferred from the O VII accretion disc lines. While relativistic reflection as the sole emission is ruled out, a simplified combination of soft and hard Comptonisation (using COMPTT) from a warm and a hot corona, plus mild relativistic disc reflection (occuring at a few 10 s Rg) reproduces the data very well.Aims. We aim to confirm the physical origin of the soft X-ray excess of Mrk 110 and to determine its disc-corona system properties from its energetics using two new sophisticated models: REXCOR and RELAGN, respectively.Methods. We applied these models to the 0.3–79 keV X-ray broadband spectra and to the spectral energy distribution (SED) from UV to hard X-rays, respectively.Results. At both epochs, the inferred high values of the warm-corona heating from the X-ray broadband spectral analysis using REXCOR confirm that the soft X-ray excess of Mrk 110 mainly originates from a warm corona rather than relativistic reflection. The intrinsic best-fit SED determined at both epochs using RELAGN show a high X-ray contribution relative to the UV and are very well reproduced by a warm and hot corona plus mild relativistic reflection. The outer radii of the hot and warm corona are located at a few 10 s and ∌100 Rg, respectively. Moreover, combining the inferred low Eddington ratio (approximatively a few percent) from this work, and previous multi-wavelength spectral and timing studies suggest that Mrk 110 could be classified as a moderate changing-state AGN.Conclusions. Our analysis confirms the existence of a warm corona as a significant contribution to the soft X-ray excess and UV emission in Mrk 110, adding to growing evidence that AGN accretion deviates from standard disc theory. This strengthens the importance of long-term multi-wavelength monitoring on both single targets and large AGN surveys to reveal the real nature of the disc-corona system in AGNs

    Pressure-induced phase transformations in ice at low temperature

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    The Hot and Energetic Universe: Astrophysics of feedback in local AGN

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    Understanding the astrophysics of feedback in active galactic nuclei (AGN) is key to understanding the growth and co-evolution of supermassive black holes and galaxies. AGN-driven winds/outflows are potentially the most effective way of transporting energy and momentum from the nuclear scales to the host galaxy, quenching star formation by sweeping away the gas reservoir. Key questions in this field are: 1) how do accretion disks around black holes launch winds/outflows, and how much energy do these carry? 2) How are the energy and metals accelerated in winds/outflows transferred and deposited into the circumgalactic medium? X-ray observations are a unique way to address these questions because they probe the phase of the outflows which carries most of the kinetic energy. We show how a high throughput, high spectral resolution instrument like the X-ray Integral Field Unit (X-IFU) on Athena+ will allow us to address these questions by determining the physical parameters (ionization state, density, temperature, abundances, velocities, geometry, etc.) of the outflows on a dynamical time-scale, in a broad sample of nearby bright AGN. The X-IFU will also allow direct spectral imaging of the impact of these winds on the host galaxy for local AGN, forming a template for understanding AGN at higher redshifts where wind shocks cannot be resolved.Comment: Supporting paper for the science theme "The Hot and Energetic Universe" to be implemented by the Athena+ X-ray observatory (http://www.the-athena-x-ray-observatory.eu). 10 pages, 6 figure

    Methodological challenges in online trials: an update and insights from the REACT trial

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    There has been a growth in the number of web-based trials of web-based interventions, adding to an increasing evidence base for their feasibility and effectiveness. However, there are challenges associated with such trials, which researchers must address. This discussion paper follows the structure of the Down Your Drink trial methodology paper, providing an update from the literature for each key trial parameter (recruitment, registration eligibility checks, consent and participant withdrawal, randomization, engagement with a web-based intervention, retention, data quality and analysis, spamming, cybersquatting, patient and public involvement, and risk management and adverse events), along with our own recommendations based on designing the Relatives Education and Coping Toolkit randomized controlled trial for relatives of people with psychosis or bipolar disorder. The key recommendations outlined here are relevant for future web-based and hybrid trials and studies using iterative development and test models such as the Accelerated Creation-to-Sustainment model, both within general health research and specifically within mental health research for relatives. Researchers should continue to share lessons learned from conducting web-based trials of web-based interventions to benefit future studies

    Ice XII in its second regime of metastability

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    We present neutron powder diffraction results which give unambiguous evidence for the formation of the recently identified new crystalline ice phase[Lobban et al.,Nature, 391, 268, (1998)], labeled ice XII, at completely different conditions. Ice XII is produced here by compressing hexagonal ice I_h at T = 77, 100, 140 and 160 K up to 1.8 GPa. It can be maintained at ambient pressure in the temperature range 1.5 < T < 135 K. High resolution diffraction is carried out at T = 1.5 K and ambient pressure on ice XII and accurate structural properties are obtained from Rietveld refinement. At T = 140 and 160 K additionally ice III/IX is formed. The increasing amount of ice III/IX with increasing temperature gives an upper limit of T ~ 150 K for the successful formation of ice XII with the presented procedure.Comment: 3 Pages of RevTeX, 3 tables, 3 figures (submitted to Physical Review Letters

    Observations of Outflowing UV Absorbers in NGC 4051 with the Cosmic Origins Spectrograph

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    We present new Hubble Space Telescope (HST)/Cosmic Origins Spectrograph observations of the Narrow-Line Seyfert 1 galaxy NGC 4051. These data were obtained as part of a coordinated observing program including X-ray observations with the Chandra/High Energy Transmission Grating (HETG) Spectrometer and Suzaku. We detected nine kinematic components of UV absorption, which were previously identified using the HST/Space Telescope Imaging Spectrograph. None of the absorption components showed evidence for changes in column density or profile within the \sim 10 yr between the STIS and COS observations, which we interpret as evidence of 1) saturation, for the stronger components, or 2) very low densities, i.e., n_H < 1 cm^-3, for the weaker components. After applying a +200 km s^-1 offset to the HETG spectrum, we found that the radial velocities of the UV absorbers lay within the O VII profile. Based on photoionization models, we suggest that, while UV components 2, 5 and 7 produce significant O VII absorption, the bulk of the X-ray absorption detected in the HETG analysis occurs in more highly ionized gas. Moreover, the mass loss rate is dominated by high ionization gas which lacks a significant UV footprint.Comment: 41 pages, 10 Figures; accepted for publication in the Astrophysical Journa

    Exact Bayesian curve fitting and signal segmentation.

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    We consider regression models where the underlying functional relationship between the response and the explanatory variable is modeled as independent linear regressions on disjoint segments. We present an algorithm for perfect simulation from the posterior distribution of such a model, even allowing for an unknown number of segments and an unknown model order for the linear regressions within each segment. The algorithm is simple, can scale well to large data sets, and avoids the problem of diagnosing convergence that is present with Monte Carlo Markov Chain (MCMC) approaches to this problem. We demonstrate our algorithm on standard denoising problems, on a piecewise constant AR model, and on a speech segmentation problem

    An online supported self-management toolkit for relatives of people with psychosis or bipolar experiences: the IMPART multiple case study

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    Background Digital health interventions have the potential to improve the delivery of psychoeducation to people with mental health problems and their relatives. Despite substantial investment in the development of digital health interventions, successful implementation into routine clinical practice is rare. Objectives Use the implementation of the Relatives’ Education And Coping Toolkit (REACT) for psychosis/bipolar disorder to identify critical factors affecting uptake and use, and develop an implementation plan to support the delivery of REACT. Design This was an implementation study using a mixed-methods, theory-driven, multiple case study approach. A study-specific implementation theory for REACT based on normalisation process theory was developed and tested, and iterations of an implementation plan to address the key factors affecting implementation were developed. Setting Early-intervention teams in six NHS mental health trusts in England (three in the north and three in the south). Participants In total, 281 staff accounts and 159 relatives’ accounts were created, 129 staff and 23 relatives took part in qualitative interviews about their experiences, and 132 relatives provided demographic data, 56 provided baseline data, 21 provided data at 12 weeks’ follow-up and 20 provided data at 24 weeks’ follow-up. Interventions REACT is an online supported self-management toolkit, offering 12 evidence-based psychoeducation modules and support via a forum, and a confidential direct messaging service for relatives of people with psychosis or bipolar disorder. The implementation intervention was developed with staff and iteratively adapted to address identified barriers. Adaptations included modifications to the toolkit and how it was delivered by teams. Main outcome measures The main outcome was factors affecting implementation of REACT, assessed primarily through in-depth interviews with staff and relatives. We also assessed quantitative measures of delivery (staff accounts and relatives’ invitations), use of REACT (relatives’ logins and time spent on the website) and the impact of REACT [relatives’ distress (General Health Questionnaire-28), and carer well-being and support (Carer Well-being and Support Scale questionnaire)]. Results Staff and relatives were generally positive about the content of REACT, seeing it as a valuable resource that could help services improve support and meet clinical targets, but only within a comprehensive service that included face-to-face support, and with some additional content. Barriers to implementation included high staff caseloads and difficulties with prioritising supporting relatives; technical difficulties of using REACT; poor interoperability with trust information technology systems and care pathways; lack of access to mobile technology and information technology training; restricted forum populations leading to low levels of use; staff fears of managing risk, online trolling, or replacement by technology; and uncertainty around REACT’s long-term availability. There was no evidence that REACT would reduce staff time supporting relatives (which was already very low), and might increase it by facilitating communication. In all, 281 staff accounts were created, but only 57 staff sent relatives invitations. In total, 355 relatives’ invitations were sent to 310 unique relatives, leading to the creation of 159 relatives’ accounts. The mean number of logins for relatives was 3.78 (standard deviation 4.43), but with wide variation from 0 to 31 (median 2, interquartile range 1–8). The mean total time spent on the website was 40.6 minutes (standard deviation 54.54 minutes), with a range of 0–298 minutes (median 20.1 minutes, interquartile range 4.9–57.5 minutes). There was a pattern of declining mean scores for distress, social dysfunction, depression, anxiety and insomnia, and increases in relatives’ well-being and eHealth literacy, but no changes were statistically significant. Conclusions Digital health interventions, such as REACT, should be iteratively developed, evaluated, adapted and implemented, with staff and service user input, as part of a long-term strategy to develop integrated technology-enabled services. Implementation strategies must instil a sense of ownership for staff and ensure that they have adequate training, risk protocols and resources to deliver the technology. Cost-effectiveness and impact on workload and inequalities in accessing health care need further testing, along with the generalisability of our findings to other digital health interventions. Limitations REACT was offered by the same team running the IMPlementation of A Relatives’ Toolkit (IMPART) study, and was perceived by staff and relatives as a time-limited research study rather than ongoing clinical service, which affected engagement. Access to observational data was limited. Trial registration Current Controlled Trials ISRCTN16267685. Funding This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 37. See the NIHR Journals Library website for further project information
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