665 research outputs found

    Raman scattering in C_{60} and C_{48}N_{12} aza-fullerene: First-principles study

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    We carry out large scale {\sl ab initio} calculations of Raman scattering activities and Raman-active frequencies (RAFs) in C48N12{\rm C}_{48}{\rm N}_{12} aza-fullerene. The results are compared with those of C60{\rm C}_{60}. Twenty-nine non-degenerate polarized and 29 doubly-degenerate unpolarized RAFs are predicted for C48N12{\rm C}_{48}{\rm N}_{12}. The RAF of the strongest Raman signal in the low- and high-frequency regions and the lowest and highest RAFs for C48N12{\rm C}_{48}{\rm N}_{12} are almost the same as those of C60{\rm C}_{60}. The study of C60{\rm C}_{60} reveals the importance of electron correlations and the choice of basis sets in the {\sl ab initio} calculations. Our best calculated results for C60{\rm C}_{60} with the B3LYP hybrid density functional theory are in excellent agreement with experiment and demonstrate the desirable efficiency and accuracy of this theory for obtaining quantitative information on the vibrational properties of these molecules.Comment: submitted to Phys.Rev.

    Systematically reviewing and synthesizing evidence from conversation analytic and related discursive research to inform healthcare communication practice and policy: an illustrated guide

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    Background Healthcare delivery is largely accomplished in and through conversations between people, and healthcare quality and effectiveness depend enormously upon the communication practices employed within these conversations. An important body of evidence about these practices has been generated by conversation analysis and related discourse analytic approaches, but there has been very little systematic reviewing of this evidence. Methods We developed an approach to reviewing evidence from conversation analytic and related discursive research through the following procedures: • reviewing existing systematic review methods and our own prior experience of applying these • clarifying distinctive features of conversation analytic and related discursive work which must be taken into account when reviewing • holding discussions within a review advisory team that included members with expertise in healthcare research, conversation analytic research, and systematic reviewing • attempting and then refining procedures through conducting an actual review which examined evidence about how people talk about difficult future issues including illness progression and dying Results We produced a step-by-step guide which we describe here in terms of eight stages, and which we illustrate from our ‘Review of Future Talk’. The guide incorporates both established procedures for systematic reviewing, and new techniques designed for working with conversation analytic evidence. Conclusions The guide is designed to inform systematic reviews of conversation analytic and related discursive evidence on specific domains and topics. Whilst we designed it for reviews that aim at informing healthcare practice and policy, it is flexible and could be used for reviews with other aims, for instance those aiming to underpin research programmes and projects. We advocate systematically reviewing conversation analytic and related discursive findings using this approach in order to translate them into a form that is credible and useful to healthcare practitioners, educators and policy-makers

    Molybdenum nitride catalysts : I. Influence of the synthesis factors on structural properties

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    Effects of the synthesis parameters on the structural properties of molybdenum nitride catalysts, prepared by the temperature-programmed reaction of MoO3 with NH3, have been examined. Molybdenum trioxide was heated in flowing NH3 through two linear heating segments (623 to 723 K then 723 to 973 K) with different space velocities in a 23 factorial design. The temperature limits for these heating segments were defined based on the results of in situ X-ray diffraction analysis of the gas-solid reaction. The resulting catalysts were characterized using BET surface area analysis, environmental scanning electron microscopy, ex situ X-ray diffraction, and oxygen chemisorption. The primary bulk phase present was [gamma]-Mo2N. Some of the lower surface area catalysts also contained MoO2 and Mo, but there was no evidence of nitrides other than [gamma]-Mo2N. The catalysts consisted of micrometersized, plate-like aggregates of nanometer-sized crystallites, and possessed surface areas ranging up to [approximate]140 m2/g depending on the synthesis and reduction conditions employed. Statistical analysis of the results revealed that the space velocity individually and the heating rates combined had the most significant effects on the structural properties. The production of catalysts with surface areas in excess of 50 m2/g required the use of slow heating rates during the first segment and high space velocities. We concluded that the key to producing the highest surface area Mo nitrides was channeling the reaction through HxMoO3 (x 2OyN1-y intermediates. Passivation of the materials immediately following synthesis appeared to produce an oxynitride at the surface. Reduction of the passivated materials in H2 at temperatures up to 673 K caused a significant increase in the surface area and O2 uptake. The O2 uptake for the low and medium surface area catalysts varied linearly with the BET surface area and corresponded to an O:Mo stoichiometry of approximately 1:5. The oxygen site density for the highest surface area nitride was lower than those for the lower surface area catalysts, presumably due to differing surface structures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31907/1/0000860.pd

    Narcissism and the strategic pursuit of short-term mating : universal links across 11 world regions of the International Sexuality Description Project-2.

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    Previous studies have documented links between sub-clinical narcissism and the active pursuit of short-term mating strategies (e.g., unrestricted sociosexuality, marital infidelity, mate poaching). Nearly all of these investigations have relied solely on samples from Western cultures. In the current study, responses from a cross-cultural survey of 30,470 people across 53 nations spanning 11 world regions (North America, Central/South America, Northern Europe, Western Europe, Eastern Europe, Southern Europe, Middle East, Africa, Oceania, Southeast Asia, and East Asia) were used to evaluate whether narcissism (as measured by the Narcissistic Personality Inventory; NPI) was universally associated with short-term mating. Results revealed narcissism scores (including two broad factors and seven traditional facets as measured by the NPI) were functionally equivalent across cultures, reliably associating with key sexual outcomes (e.g., more active pursuit of short-term mating, intimate partner violence, and sexual aggression) and sex-related personality traits (e.g., higher extraversion and openness to experience). Whereas some features of personality (e.g., subjective well-being) were universally associated with socially adaptive facets of Narcissism (e.g., self-sufficiency), most indicators of short-term mating (e.g., unrestricted sociosexuality and marital infidelity) were universally associated with the socially maladaptive facets of narcissism (e.g., exploitativeness). Discussion addresses limitations of these cross-culturally universal findings and presents suggestions for future research into revealing the precise psychological features of narcissism that facilitate the strategic pursuit of short-term mating

    Deleterious Effects of Intermittent Recombinant Parathyroid Hormone on Cartilage Formation in a Rabbit Microfracture Model: a Preliminary Study

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    Intermittent parathyroid hormone administration can enhance fracture healing in an animal model. Despite the success of exogenous parathyroid hormone on fracture healing and spine fusion, few studies have examined the role of parathyroid hormone on cartilage formation. We determined the effects of intermittent parathyroid hormone on cartilage formation in a rabbit microfracture model of cartilage regeneration. Twelve rabbits were divided into three equal groups: (1) microfracture alone, (2) microfracture + parathyroid hormone daily for 7 days, and (3) microfracture + parathyroid hormone for 28 days. Nonoperated contralateral knees were used as controls. The animals were sacrificed at 3 months and gross and histologic analysis was performed. The microfracture alone group demonstrated the most healing on gross and histologic analysis. Treatment with either 1 or 4 weeks of parathyroid hormone inhibited cartilage formation. Although discouraging from a cartilage repair point of view, this study suggests that the role parathyroid hormone administration has in clinical fracture healing must be examined carefully. Although parathyroid hormone is beneficial to promote healing in spine fusion and midshaft fractures, its deleterious effects on cartilage formation suggests that it may have adverse effects on the outcomes of periarticular fractures such as tibial plateau injuries that require cartilage healing for a successful clinical outcome

    Bright Field Microscopy as an Alternative to Whole Cell Fluorescence in Automated Analysis of Macrophage Images

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    Fluorescence microscopy is the standard tool for detection and analysis of cellular phenomena. This technique, however, has a number of drawbacks such as the limited number of available fluorescent channels in microscopes, overlapping excitation and emission spectra of the stains, and phototoxicity.We here present and validate a method to automatically detect cell population outlines directly from bright field images. By imaging samples with several focus levels forming a bright field -stack, and by measuring the intensity variations of this stack over the -dimension, we construct a new two dimensional projection image of increased contrast. With additional information for locations of each cell, such as stained nuclei, this bright field projection image can be used instead of whole cell fluorescence to locate borders of individual cells, separating touching cells, and enabling single cell analysis. Using the popular CellProfiler freeware cell image analysis software mainly targeted for fluorescence microscopy, we validate our method by automatically segmenting low contrast and rather complex shaped murine macrophage cells.The proposed approach frees up a fluorescence channel, which can be used for subcellular studies. It also facilitates cell shape measurement in experiments where whole cell fluorescent staining is either not available, or is dependent on a particular experimental condition. We show that whole cell area detection results using our projected bright field images match closely to the standard approach where cell areas are localized using fluorescence, and conclude that the high contrast bright field projection image can directly replace one fluorescent channel in whole cell quantification. Matlab code for calculating the projections can be downloaded from the supplementary site: http://sites.google.com/site/brightfieldorstaining

    Combined autologous chondrocyte implantation (ACI) with supra-condylar femoral varus osteotomy, following lateral growth-plate damage in an adolescent knee: 8-year follow-up

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    We report the 8-year clinical and radiographic outcome of an adolescent patient with a large osteochondral defect of the lateral femoral condyle, and ipsilateral genu valgum secondary to an epiphyseal injury, managed with autologous chondrocyte implantation (ACI) and supracondylar re-alignment femoral osteotomy. Long-term clinical success was achieved using this method, illustrating the effective use of re-alignment osteotomy in correcting mal-alignment of the knee, protecting the ACI graft site and providing the optimum environment for cartilage repair and regeneration. This is the first report of the combined use of ACI and femoral osteotomy for such a case

    Geographical Perspectives on Transport and Ageing

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    In terms of ageing, we are living in unprecedented times. People across the globe are living longer than ever before and societies are ageing at increasing rates. In low to middle income countries reductions in mortality at young ages have fuelled this growth. A person born today in Brazil, for example, can expect to live 20 years longer than someone born 50 years ago (WHO, 2015). For the first time life expectancy across the globe is over 60 years of age. In high Income countries, someone born now can expect to live up to around 80 years of age on average (ONS, 2015). There are not simply a growing number of older people, but also a growing number of older people as a total percentage of the population due to people living longer and declining birth rates in many countries. Across Europe, for example, people aged over 65 years will account for 29.5% of the population in 2060 compared to around 19% now (EUROSTAT, 2017). The share of those aged 80 years or above across Europe will almost triple by 2060 (EUROSTAT, 2017)The macro level demographics and associated trends mask big differences within the ageing populations. There can be as much as 10 years difference in life expectancy within high income countries, for example in the UK someone born a baby boy born in Kensington and Chelsea has a life expectancy of 83.3 years, compared with a boy born in Glasgow who has a life expectancy of 10 years lower (73.0 years) (ONS, 2015). For newborn baby girls, life expectancy is highest in Chiltern at 86.7 years and 8 years lower Glasgow at 78.5 years (ONS, 2015; NRS, 2016). There is also considerable variation within cities, spatially and socially.This volume brings together contributions from a broad range of human geographers, with different disciplinary perspectives of transport and ageing. This chapter outlines some of the key contemporary issues for an ageing society in terms of transport and mobility, highlights the importance of considering transport and mobility for ageing populations and outlines the contribution that a geographical approach can offer to studies of transport and ageing

    MR imaging of osteochondral grafts and autologous chondrocyte implantation

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    Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible
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