2,147 research outputs found

    Ultra-strong Adhesion of Graphene Membranes

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    As mechanical structures enter the nanoscale regime, the influence of van der Waals forces increases. Graphene is attractive for nanomechanical systems because its Young's modulus and strength are both intrinsically high, but the mechanical behavior of graphene is also strongly influenced by the van der Waals force. For example, this force clamps graphene samples to substrates, and also holds together the individual graphene sheets in multilayer samples. Here we use a pressurized blister test to directly measure the adhesion energy of graphene sheets with a silicon oxide substrate. We find an adhesion energy of 0.45 \pm 0.02 J/m2 for monolayer graphene and 0.31 \pm 0.03 J/m2 for samples containing 2-5 graphene sheets. These values are larger than the adhesion energies measured in typical micromechanical structures and are comparable to solid/liquid adhesion energies. We attribute this to the extreme flexibility of graphene, which allows it to conform to the topography of even the smoothest substrates, thus making its interaction with the substrate more liquid-like than solid-like.Comment: to appear in Nature Nanotechnolog

    The prevalence of axial spondyloarthritis in the UK: a cross-sectional cohort study

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    Background: Accurate prevalence data are important when interpreting diagnostic tests and planning for the health needs of a population, yet no such data exist for axial spondyloarthritis (axSpA) in the UK. In this cross-sectional cohort study we aimed to estimate the prevalence of axSpA in a UK primary care population. Methods: A validated self-completed questionnaire was used to screen primary care patients with low back pain for inflammatory back pain (IBP). Patients with a verifiable pre-existing diagnosis of axSpA were included as positive cases. All other patients meeting the Assessment of SpondyloArthritis international Society (ASAS) IBP criteria were invited to undergo further assessment including MRI scanning, allowing classification according to the European Spondyloarthropathy Study Group (ESSG) and ASAS axSpA criteria, and the modified New York (mNY) criteria for ankylosing spondylitis (AS). Results: Of 978 questionnaires sent to potential participants 505 were returned (response rate 51.6 %). Six subjects had a prior diagnosis of axSpA, 4 of whom met mNY criteria. Thirty eight of 75 subjects meeting ASAS IBP criteria attended review (mean age 53.5 years, 37 % male). The number of subjects satisfying classification criteria was 23 for ESSG, 3 for ASAS (2 clinical, 1 radiological) and 1 for mNY criteria. This equates to a prevalence of 5.3 % (95 % CI 4.0, 6.8) using ESSG, 1.3 % (95 % CI 0.8, 2.3) using ASAS, 0.66 % (95 % CI 0.28, 1.3) using mNY criteria in chronic back pain patients, and 1.2 % (95 % CI 0.9, 1.4) using ESSG, 0.3 % (95 % CI 0.13, 0.48) using ASAS, 0.15 % (95 % CI 0.02, 0.27) using mNY criteria in the general adult primary care population. Conclusions: These are the first prevalence estimates for axSpA in the UK, and will be of importance in planning for the future healthcare needs of this population. Trial registration: Current Controlled Trials ISRCTN7687321

    Thermal, structural and optical properties of {CdS}-Na(86)X composites

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    Thermal, structural and optical properties of CdS superclusters grown in zeolite Na(86)X are reported. The interest in this work arose in the need to study CdS prepared in the zeolite host, at high concentrations (>19%), in order to observe porosyte behaviour and CdS aggregate properties. The semiconductor-zeolite composite was studied using X-ray diffraction analysis and photoacoustic technique (PAS). The properties of semiconductor CdS embedded in a zeolite matrix were analysed as a function of the CdS concentration by monitoring Cd concentration (atom%) by chemical analysis. The results show that as the concentration of CdS increases, the thermal diffusivity, capacity, conductivity and the band-gap increase up to a point where the zeolite lattice collapses. From this point on, all these thermal properties diminish and the band-gap is the same as for bulk CdS.92142651265

    Ethical problems experienced by oncology nurses

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    Objective: to know the ethical problems experienced by oncology nurses. Method: descriptive and exploratory study with a qualitative approach, performed in inpatient units and in chemotherapy out-patients units that provide assistance to oncological patients in two capitals in the South region of Brazil. Eighteen nurses participated in this study, selected by snowball sampling type. For data collection, semi-structured interviews were carried out, which were recorded and transcribed, and then analyzed by thematic analysis. Results: two categories were established: when informing or not becomes a dilemma - showing the main difficulties related to oncological treatment information regarding health staff, health system, and infrastructure; to invest or not - dilemmas related to finitude - showing situations of dilemmas related to pain and confrontation with finitude. Conclusion: for the effective confrontation of the ethical problems experienced by oncology nurses to occur, it is important to invest in the training of these professionals, preparing them in an ethical and human way to act as lawyers of the patient with cancer, in a context of dilemmas related mainly to the possibility of finitude

    Participatory planning and quality assessment: contributions of a nursing management technology

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    Objective: to analyze the outcomes of participatory planning and quality assessment of the nursing care provided in a hospital ward using a nursing management technology. Method: Convergent care research focuses on research and practice intervention, developed in a hospital in southern Brazil from April to August 2016. Participatory planning and quality evaluation was performed using the PRAXIS® technology. Results: In the participatory planning, a survey of needs/problems was carried out by 33 professionals followed by 5 workshops, where mission, guiding principles, 4 priority problems, expected results, objectives and plans of activities were defined. For quality evaluation, two indicators were used: satisfaction and notification of adverse events. The evaluation was carried out with 101 patients and /or relatives, predominating “great or good”. Adverse events, 28 records, predominating medication errors. Conclusion: Participatory planning and quality assessment are essential to improve nursing care management and the PRAXIS® technological innovation has been a useful resource.info:eu-repo/semantics/publishedVersio

    Alexitimia y depresión en mayores que practican actividad física dirigida

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    Associations between alexithymia and depression and sociodemographic factors have been investigated in elderly population. Whether exercise plays a role as a protective factor against these conditions has yet to be determined. Thus, the aim of this study was to investigate alexithymia and depression and its association with physical activity in elderly people. Twenty-seven participants, 9 men and 18 women (aged 64 ± 5.1). Subjects were assigned to either a sedentary group or a physically active group. All participants filled in Yesavage Scale, Toronto Alexithymia Scale (TAS)-20 and SF-12. Data were analyzed using Student’s t-test andmultiple linear regression analyses. Results showed that physically active elderly people scored lower for alexithymia and depression than sedentary subjects. These findings suggest that physical activity may have a role in benefiting mental disorders.La relación entre la alexitimia y la depresión y los factores sociodemográficos ha sido estudiada en personas mayores. Sin embargo, el papel atenuador del ejercicio en estas afecciones aún debe ser determinado. En el presente estudio se mide el grado de alexitimia y depresión en adultos mayores, comparando una muestra sedentaria con una de practicantes de actividad física. Se utilizó un diseño descriptivo transversal con una muestra compuesta por 27 participantes, 9 hombres y 18 mujeres de más de 60 años (64±5.1 años), con objeto de medir el grado de alexitimia y depresión que presentaban en el momento de la recogida de datos. Los instrumentos utilizados fueron la escala de depresión de Yesavage, la Escala de Alexitimia de Toronto (TAS-20) y el Cuestionario de Salud SF-12. Los resultados mostraron que los practicantes de actividad física presentaban puntuaciones más bajas en alexitimia y depresión que los sujetos sedentarios, sin que éstas variables estuvieran relacionadas en función del género y la edad. A tenor de los resultados, el ejercicio pudiera jugar algún papel en la modulación de las alteraciones psicológicas.

    A mathematical and computational review of Hartree-Fock SCF methods in Quantum Chemistry

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    We present here a review of the fundamental topics of Hartree-Fock theory in Quantum Chemistry. From the molecular Hamiltonian, using and discussing the Born-Oppenheimer approximation, we arrive to the Hartree and Hartree-Fock equations for the electronic problem. Special emphasis is placed in the most relevant mathematical aspects of the theoretical derivation of the final equations, as well as in the results regarding the existence and uniqueness of their solutions. All Hartree-Fock versions with different spin restrictions are systematically extracted from the general case, thus providing a unifying framework. Then, the discretization of the one-electron orbitals space is reviewed and the Roothaan-Hall formalism introduced. This leads to a exposition of the basic underlying concepts related to the construction and selection of Gaussian basis sets, focusing in algorithmic efficiency issues. Finally, we close the review with a section in which the most relevant modern developments (specially those related to the design of linear-scaling methods) are commented and linked to the issues discussed. The whole work is intentionally introductory and rather self-contained, so that it may be useful for non experts that aim to use quantum chemical methods in interdisciplinary applications. Moreover, much material that is found scattered in the literature has been put together here to facilitate comprehension and to serve as a handy reference.Comment: 64 pages, 3 figures, tMPH2e.cls style file, doublesp, mathbbol and subeqn package

    A equipe de enfermagem e a comunicação com o paciente traqueostomizado

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    OBJETIVO: identificar as percepções da equipe de enfermagem acerca da importância da comunicação no cuidado ao paciente traqueostomizado, de modo a auxiliá-lo na sua recuperação. MÉTODOS: estudo de abordagem quantitativa e qualitativa. A amostra do estudo foi constituída por 51 integrantes da equipe de enfermagem (auxiliares de enfermagem, técnicos e enfermeiros), das Clínicas Médica Feminina e Masculina, Centro de Terapia Semi-Intensiva e Intensiva Adulto, e Neurocirurgia, de um hospital de ensino em Curitiba/PR. As informações foram coletadas por meio de questionário com questões fechadas e abertas. Na associação entre variáveis quantitativas foram considerados o teste Qui-Quadrado, valores de p < 0,05 indicaram significância estatística, os dados qualitativos foram submetidos à proposta de análise de conteúdo. RESULTADOS: os dados mostram que os participantes têm vivências variadas em sua área de atuação e constatam na sua prática cotidiana a necessidade e a importância da interação com o paciente traqueostomizado para sua recuperação. Os resultados apontam que os Auxiliares e Técnicos, desenvolvem mais orientações do que o enfermeiro (p=0,028). CONCLUSÃO: evidenciou-se no estudo que na impossibilidade de comunicação verbal pelo paciente, os participantes do estudo se utilizam de estratégias diferenciadas de comunicação, como gestos, sinalização e comunicação escrita

    Adaptive and Innate Immune Responses in Autism: Rationale for Therapeutic Use of Intravenous Immunoglobulin

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    Autism is a complex polygenic neurodevelopmental disorder characterized by deficits in communication and social interactions as well as specific stereotypical behaviors. Both genetic and environmental factors appear to contribute to the pathogenesis of autism. Accumulating data including changes in immune responses, linkage to major histocompatibility complex antigens, and the presence of autoantibodies to neural tissues/antigens suggest that the immune system plays an important role in its pathogenesis. In this brief review, we discuss the data regarding changes in both innate and adaptive immunity in autism and the evidence in favor of the role of the immune system, especially of maternal autoantibodies in the pathogenesis of a subset of patients with autism. The rationale for possible therapeutic use of intravenous immunoglobulin is also discussed
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