2,384 research outputs found

    Migration potential as a new predictor of long-distance dispersal rate for plants

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    How biotic and abiotic factors interact to shape the overall pattern of dispersal of propagules is critical in understanding the evolution of dispersal mechanisms as well as predicting dispersal rates between patchily-distributed habitats. But which plant traits, demographic and/or habitat factors best predict the capacity for dispersal? We introduce the concept of migration potential (v), a readily interpretable parameter that combines recruitment efficiency (recruits per adult / seeds per adult per dispersal cycle) with level of habitat occupancy for predicting effective long-distance dispersal (LDD) of seeds. Using our empirical (genotype assignment) estimates of LDD and statistics on life-history traits and demographic features for contrasting co-occurring shrub species as a test case, and comparing alternative plant traits, we demonstrate that rate of LDD is best described as a simple function of v. As the direct consequence of life-history and demographic traits in a specific environmental context, v has the potential to predict LDD rates in both stable and changing ecosystems

    Silicone encapsulation of thin-film SiOₓ, SiOₓNy and SiC for modern electronic medical implants: a comparative long-term ageing study

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    Objective. Ensuring the longevity of implantable devices is critical for their clinical usefulness. This is commonly achieved by hermetically sealing the sensitive electronics in a water impermeable housing, however, this method limits miniaturisation. Alternatively, silicone encapsulation has demonstrated long-term protection of implanted thick-film electronic devices. However, much of the current conformal packaging research is focused on more rigid coatings, such as parylene, liquid crystal polymers and novel inorganic layers. Here, we consider the potential of silicone to protect implants using thin-film technology with features 33 times smaller than thick-film counterparts. Approach. Aluminium interdigitated comb structures under plasma-enhanced chemical vapour deposited passivation (SiOx, SiOxNy, SiOxNy + SiC) were encapsulated in medical grade silicones, with a total of six passivation/silicone combinations. Samples were aged in phosphate-buffered saline at 67‰ for up to 694 days under a continuous ±5 V biphasic waveform. Periodic electrochemical impedance spectroscopy measurements monitored for leakage currents and degradation of the metal traces. Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, focused-ion-beam and scanning-electron- microscopy were employed to determine any encapsulation material changes. Main results. No silicone delamination, passivation dissolution, or metal corrosion was observed during ageing. Impedances greater than 100 G were maintained between the aluminium tracks for silicone encapsulation over SiOxNy and SiC passivations. For these samples the only observed failure mode was open-circuit wire bonds. In contrast, progressive hydration of the SiOx caused its resistance to decrease by an order of magnitude. Significance. These results demonstrate silicone encapsulation offers excellent protection to thin-film conducting tracks when combined with appropriate inorganic thin films. This conclusion corresponds to previous reliability studies of silicone encapsulation in aqueous environments, but with a larger sample size. Therefore, we believe silicone encapsulation to be a realistic means of providing long-term protection for the circuits of implanted electronic medical devices

    Factors That Impact the Success of Interorganizational Health Promotion Collaborations: A Scoping Review

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    © 2017, © The Author(s) 2017. Objective: To explore published empirical literature in order to identify factors that facilitate or inhibit collaborative approaches for health promotion using a scoping review methodology. Data Source: A comprehensive search of MEDLINE, CINAHL, ScienceDirect, PsycINFO, and Academic Search Complete for articles published between January 2001 and October 2015 was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Study Inclusion and Exclusion Criteria: To be included studies had to: be an original research article, published in English, involve at least 2 organizations in a health promotion partnership, and identify factors contributing to or constraining the success of an established (or prior) partnership. Studies were excluded if they focused on primary care collaboration or organizations jointly lobbying for a cause. Data Extraction: Data extraction was completed by 2 members of the author team using a summary chart to extract information relevant to the factors that facilitated or constrained collaboration success. Data Synthesis: NVivo 10 was used to code article content into the thematic categories identified in the data extraction. Results: Twenty-five studies across 8 countries were identified. Several key factors contributed to collaborative effectiveness, including a shared vision, leadership, member characteristics, organizational commitment, available resources, clear roles/responsibilities, trust/clear communication, and engagement of the target population. Conclusion: In general, the findings were consistent with previous reviews; however, additional novel themes did emerge

    Apparatus to investigate the insulation impedance and accelerated life-testing of neural interfaces

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    OBJECTIVE: Neural interfaces and other implantable micro-devices that use polymer-encapsulated integrated circuits will only be allowed in medical devices when their lifetimes can be estimated from experimental data. An apparatus has been developed and tested that allows hundreds of insulation samples (interdigitated combs) to be aged under accelerated conditions of high temperature and voltage stress. Occasionally, aging is interrupted while the sample's impedance is measured; the impedance spectrogram shows degradation as it progresses before failure.
 Approach. The design was based on practical considerations which are reviewed. A Solartron Modulab provides the frequency response analyser and the femtoammeter. The apparatus can accommodate batches of samples at several temperatures and with different aging voltage waveforms. It is important to understand features of the spectra that are not due to comb-comb leakage; these have been observed and investigated using SPICE.
 Main results. The design is described in detail and tests show that it is capable of making measurements over long periods, at least up to 67°C. Despite the size of the apparatus, background capacitance is about 1 pF and comb-comb capacitances of about 30 pF can be measured down to 10 mHz. an impedance of about 100GΩ. An important discovery was the advantage of grounding the bathing solution, mainly because it raises the measurement ceiling. Observation and SPICE simulation show that leakage from the substrate to the bathing solution can give phase lags >90°, in contrast to comb-comb leakage which reduces phase lag to <90°.
 Significance. We think that the value of this paper is that it will facilitate research into the endurance of small implanted devices because, given a description of proven apparatus, researchers can start building their own apparatus relatively quickly and with confidence.&#13

    Baryon Junction Loops in HIJING/B\=Bv2.0 and the Baryon/Meson Anomaly at RHIC

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    A new version, v2.0, of the HIJING/B\=B Monte Carlo nuclear collision event generator is introduced in order to explore further the possible role of baryon junctions loops in the baryon/meson anomaly (2 <pT<< p_{T} < 5 GeV/c) observed in 200A GeV Au+Au reactions at RHIC. We show that junction loops with an enhanced intrinsic kT1k_T\approx 1 GeV/c transverse momentum kick may provide a partial explanation of the anomaly as well as other important baryon stopping observables.Comment: 27 pages, Latex(revtex), 8 figure

    Jets as a Probe of Dense Matter at RHIC

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    Jet quenching in the matter created in high energy nucleus-nucleus collisions provides a tomographic tool to probe the medium properties. Recent experimental results on jet production at the Relativistic Heavy-Ion Collider (RHIC) are reviewed. Jet properties in p+p and d+Au collisions have been measured, establishing the baseline for studying jet modification in heavy-ion collisions. Current progress on detailed studies of high transverse momentum production in Au+Au collisions is discussed, with an emphasis on dihadron correlation measurements.Comment: 8 pages, 9 figures. Plenary talk given at 17th International Conference on Ultra Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California, 11-17 Jan 2004. Submitted to J.Phys.

    Core outcomes in periodontal trials:study protocol for core outcome set development

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    Abstract Background There are a large number of clinical outcome measures used to assess the effectiveness of prevention and management strategies of periodontal diseases. This heterogeneity causes difficulties when trying to synthesise data for systematic reviews or clinical guidelines, reducing their impact. Core outcome sets are an agreed, standardised list of outcomes that should be measured and reported in all trials in specific clinical areas. We aim to develop a core outcome set for effectiveness trials investigating the prevention and management of periodontal disease in primary or secondary care. Methods To identify existing outcomes we screened the Cochrane systematic reviews and their included studies on the prevention and management of periodontal diseases. The core outcome set will be defined by consensus of key stakeholders using an online e-Delphi process and face-to-face meeting. Key stakeholders involved in the development will include: patients, dentists, hygienists/therapists, specialists, clinical researchers and policy-makers. Stakeholders will be asked to prioritise outcomes and feedback will be provided in the next round(s). Stakeholders will have an opportunity to add outcomes found in the Cochrane review screening process at the end of the first round. If consensus is not reached after the second round we will provide feedback prior to a third round. Remaining outcomes will be discussed at a face-to-face meeting and agreement will be measured via defined consensus rules of outcome inclusion. Discussion The inclusive consensus process should provide a core outcome set that is relevant to all key stakeholders. We will actively disseminate our findings to help improve clinical trials, systematic reviews and clinical guidelines with the ultimate aim of improving the prevention and management of periodontal diseases. Trial registration COMET ( http://www.comet-initiative.org/studies/details/265?result=true ). Registered on August 2012

    Beam Commissioning of the SPS-to-LHC Transfer Line TI 2

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    The transfer line for the LHC Ring 1 was successfully commissioned with beam in the autumn of 2007. After extraction from the SPS accelerator and about 2.7 km of new transfer line, the beam arrived at the temporarily installed beam dump, about 50 m before the start of the LHC tunnel, without the need of any beam threading. This paper gives an overview of the hardware commissioning period and the actual beam tests carried out. It summarises the results of the beam test optics measurements and the performance of the installed hardware

    Biological survey of the Prince Edward Islands, December 2008

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    A biological survey of the Prince Edward Islands took place in December 2008. The survey repeated an earlier survey of the populations of surface-nesting seabirds on both islands and of fur seals (Arctocephalus spp.) and alien plants on Prince Edward Island in December 2001. Observations on burrowing seabirds, macro-invertebrates and plant communities on Prince Edward Island and an oceanographic survey of surrounding waters were also included. The survey confirmed many of the observations made on the earlier survey and permitted an assessment of trends in the abundance and distribution of biota since 2001
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