554 research outputs found

    Imaging Pulsed Laser Deposition oxide growth by in-situ Atomic Force Microscopy

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    To visualize the topography of thin oxide films during growth, thereby enabling to study its growth behavior quasi real-time, we have designed and integrated an atomic force microscope (AFM) in a pulsed laser deposition (PLD) vacuum setup. The AFM scanner and PLD target are integrated in a single support frame, combined with a fast sample transfer method, such that in-situ microscopy can be utilized after subsequent deposition pulses. The in-situ microscope can be operated from room temperature (RT) up to 700^\circC and at (process) pressures ranging from the vacuum base pressure of 106^{-6} mbar up to 1 mbar, typical PLD conditions for the growth of oxide films. The performance of this instrument is demonstrated by resolving unit cell height surface steps and surface topography under typical oxide PLD growth conditions.Comment: 8 pages, 8 figure

    Biological Interactions in Grassland Soils and Productivity

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    This paper describes research on interactions between grassland plant species and soil microorganisms. Both parasitic and symbiotic microorganisms modify nutrient transfers between plants and soil. Experiments are described in which nematode infection of clover increased nitrogen transfer to companion ryegrass plants. Infection of clover enhanced activity of soil bacterial and fungal communities. Legume genotypes differing only in responses to symbionts (rhizobium and arbuscular mycorrhizal fungi) and pathogens are being developed for studies of gene expression during establishing and functional symbioses. Such plants can be used in experiments as defined perturbations that will provide information on the interactions and functions of symbiotic and pathogenic microorganisms. Such studies, related to field observations, may have value for defining biological attributes of sustainable grassland soil systems

    Silvopastoral Agroforestry in Upland and Lowland UK Grassland: Tree Growth and Animal Performance

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    Trees, individually protected from herbivore damage using plastic shelters, were planted at two densities (100 and 400 stems/ha) into sheepgrazed pasture in upland and lowland UK grassland sites in 1988. Tree and animal performance were compared with conventional forestry (no sheep) and pasture (no tree) systems. Effects on tree growth and survival are highly species and site dependent although some treatment effects did emerge. Tree shelters encouraged rapid early height growth compared to forestry controls although in some cases tree form was also adversely affected. Generally tree performance within agroforestry treatments was better at the higher planting density. Eight years after planting there has been no reduction in animal production despite interception of up to 10% of total photosynthetically active radiation by the developing tree canopy

    Ultraviolet writing of channel waveguides in proton-exchanged LiNbO<sub>3</sub>

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    We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 µm in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented

    Precision nanoscale domain engineering of lithium niobate via UV laser induced inhibition of poling

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    Continuous wave ultraviolet (UV) laser irradiation at lambda=244 nm on the +z face of undoped and MgO doped congruent lithium niobate single crystals has been observed to inhibit ferroelectric domain inversion. The inhibition occurs directly beneath the illuminated regions, in a depth greater than 100 nm during subsequent electric field poling of the crystal. Domain inhibition was confirmed by both differential domain etching and piezoresponse force microscopy. This effect allows the formation of arbitrarily shaped domains in lithium niobate and forms the basis of a high spatial resolution micro-structuring approach when followed by chemical etching

    Epitaxial growth of high quality ZnS films on sapphire and silicon by pulsed laser deposition

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    We report for the first time, epitaxial growth of high-quality ZnS films on sapphire and silicon substrates, using pulsed laser deposition. X-ray diffraction results show that at all growth temperatures from 200°C to 680°C, epitaxial wurtzite (002) ZnS films have been successfully grown on (1012) sapphire and (001) silicon substrates. X-ray diffraction data yield full width at half maximum 2theta values of 0.13° for as-grown samples, compared with 28 values or 0.09° and 0.08° for the bare sapphire and silicon substrates respectively

    Region 11 MELD Na Exception Prospective Study

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    Introduction. Hyponatremia complicates cirrhosis and predicts short term mortality, including adverse outcomes before and after liver transplantation. Material and methods. From April 1, 2008, through April 2, 2010, all adult candidates for primary liver transplantation with cirrhosis, listed in Region 11 with hyponatremia, were eligible for sodium (Na) exception. Results. Patients with serum sodium (SNa) less than 130 mg/dL, measured two weeks apart and within 30 days of Model for End Stage Liver Disease (MELD) exception request, were given preapproved Na exception. MELD Na was calculated [MELD + 1.59 (135-SNa/30 days)]. MELD Na was capped at 22, and subject to standard adult recertification schedule. On data end of follow-up, December 28, 2010, 15,285 potential U.S. liver recipients met the inclusion criteria of true MELD between 6 and 22. In Region 11, 1,198 of total eligible liver recipients were listed. Sixty-two (5.2%) patients were eligible for Na exception (MELD Na); 823 patients (68.7%) were listed with standard MELD (SMELD); and 313 patients (26.1%) received HCC MELD exception. Ninety percent of MELD Na patients and 97% of HCC MELD patients were transplanted at end of follow up, compared to 49% of Region 11 standard MELD and 40% of U.S.A. standard MELD (USA MELD) patients (p \u3c 0.001); with comparable dropout rates (6.5, 1.6, 6.9, 9% respectively; p = 0.2). MELD Na, HCC MELD, Region 11 SMELD, and USA MELD post-transplant six-month actual patient survivals were similar (92.9, 92.8, 92.2, and 93.9 %, respectively). Conclusion. The Region 11 MELD Na exception prospective trial improved hyponatremic cirrhotic patient access to transplant equitably, and without compromising transplant efficacy

    5\u3csup\u3eth\u3c/sup\u3e Generation vs 4\u3csup\u3eth\u3c/sup\u3e Generation Troponin T in Predicting Major Adverse Cardiovascular Events and All-Cause Mortality in Patients Hospitalized for Non-Cardiac Indications: A Cohort Study

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    OBJECTIVE: The frequency and implications of an elevated cardiac troponin (4th or 5th generation TnT) in patients outside of the emergency department or presenting with non-cardiac conditions is unclear. METHODS: Consecutive patients aged 18 years or older admitted for a primary non-cardiac condition who had the 4th generation TnT drawn had the 5th generation TnT run on the residual blood sample. Primary and secondary outcomes were all-cause mortality (ACM) and major adverse cardiovascular events (MACE) respectively at 1 year. RESULTS: 918 patients were included (mean age 59.8 years, 55% male) in the cohort. 69% had elevated 5th generation TnT while 46% had elevated 4th generation TnT. 5th generation TnT was more sensitive and less specific than 4th generation TnT in predicting both ACM and MACE. The sensitivities for the 5th generation TnT assay were 85% for ACM and 90% for MACE rates, compared to 65% and 70% respectively for the 4th generation assay. 5th generation TnT positive patients that were missed by 4th generation TnT had a higher risk of ACM (27.5%) than patients with both assays negative (27.5% vs 11.1%, p\u3c 0.001), but lower than patients who had both assay positive (42.1%). MACE rates were not better stratified using the 5th generation TnT assay. CONCLUSIONS: In patients admitted for a non-cardiac condition, 5th generation TnT is more sensitive although less specific in predicting MACE and ACM. 5th generation TnT identifies an intermediate risk group for ACM previously missed with the 4th generation assay
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