555 research outputs found

    Multidimensional cut-off technique, odd-dimensional Epstein zeta functions and Casimir energy of massless scalar fields

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    Quantum fluctuations of massless scalar fields represented by quantum fluctuations of the quasiparticle vacuum in a zero-temperature dilute Bose-Einstein condensate may well provide the first experimental arena for measuring the Casimir force of a field other than the electromagnetic field. This would constitute a real Casimir force measurement - due to quantum fluctuations - in contrast to thermal fluctuation effects. We develop a multidimensional cut-off technique for calculating the Casimir energy of massless scalar fields in dd-dimensional rectangular spaces with qq large dimensions and dqd-q dimensions of length LL and generalize the technique to arbitrary lengths. We explicitly evaluate the multidimensional remainder and express it in a form that converges exponentially fast. Together with the compact analytical formulas we derive, the numerical results are exact and easy to obtain. Most importantly, we show that the division between analytical and remainder is not arbitrary but has a natural physical interpretation. The analytical part can be viewed as the sum of individual parallel plate energies and the remainder as an interaction energy. In a separate procedure, via results from number theory, we express some odd-dimensional homogeneous Epstein zeta functions as products of one-dimensional sums plus a tiny remainder and calculate from them the Casimir energy via zeta function regularization.Comment: 42 pages, 3 figures. v.2: typos corrected to match published versio

    Pseudo-single crystal electrochemistry on polycrystalline electrodes : visualizing activity at grains and grain boundaries on platinum for the Fe2+/Fe3+ redox reaction

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    The influence of electrode surface structure on electrochemical reaction rates and mechanisms is a major theme in electrochemical research, especially as electrodes with inherent structural heterogeneities are used ubiquitously. Yet, probing local electrochemistry and surface structure at complex surfaces is challenging. In this paper, high spatial resolution scanning electrochemical cell microscopy (SECCM) complemented with electron backscatter diffraction (EBSD) is demonstrated as a means of performing ‘pseudo-single-crystal’ electrochemical measurements at individual grains of a polycrystalline platinum electrode, while also allowing grain boundaries to be probed. Using the Fe2+/3+ couple as an illustrative case, a strong correlation is found between local surface structure and electrochemical activity. Variations in electrochemical activity for individual high index grains, visualized in a weakly adsorbing perchlorate medium, show that there is higher activity on grains with a significant (101) orientation contribution, compared to those with (001) and (111) contribution, consistent with findings on single-crystal electrodes. Interestingly, for Fe2+ oxidation in a sulfate medium a different pattern of activity emerges. Here, SECCM reveals only minor variations in activity between individual grains, again consistent with single-crystal studies, with a greatly enhanced activity at grain boundaries. This suggests that these sites may contribute significantly to the overall electrochemical behavior measured on the macroscale

    Population health management in diabetes care: combining clinical audit, risk stratification, and multidisciplinary virtual clinics in a community setting to improve diabetes care in a geographically defined population. An integrated diabetes care pilot in the North East Locality, Oxfordshire, UK

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    Background: Disparities in diabetes care are prevalent, with significant inequalities observed in access to, and outcomes of, healthcare. A population health approach offers a solution to improve the quality of care for all with systematic ways of assessing whole population requirements and treating and monitoring sub-groups in need of additional attention. Description of the care practice: Collaborative working between primary, secondary and community care was introduced in seven primary care practices in one locality in England, UK, caring for 3560 patients with diabetes and sharing the same community and secondary specialist diabetes care providers. Three elements of the intervention included 1) clinical audit, 2) risk stratification, and 3) the multi-disciplinary virtual clinics in the community. Methods: This paper evaluates the acceptability, feasibility and short-term impact on primary care of implementing a population approach intervention using direct observations of the clinics and surveys of participating clinicians. Results and discussion: Eighteen virtual clinics across seven teams took place over six months between March and July 2017 with organisation, resources, policies, education and approximately 150 individuals discussed. The feedback from primary care was positive with growing knowledge and confidence managing people with complex diabetes in primary care. Conclusion: Taking a population health approach helped to identify groups of people in need of additional diabetes care and deliver a collaborative health intervention across traditional organisational boundaries

    Care needs of people with dementia in the peri-operative environment: a systematic review

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    The care of people with dementia within the hospital setting is challenging for healthcare professionals. Hospital design and services are not optimized for people with dementia, owing to the lack of preparation of healthcare professionals and the busy environment of the acute hospital. The peri-operative environment may present particular difficulties but little is known about the experience and care of people with dementia in this setting. The aim of this review was to examine the care of surgical patients who have dementia and their family members in peri-operative environments and describe strategies adopted by healthcare professionals. A systematic search of the following databases was completed: BNI, CINAHL, PubMED and PsychINFO in accordance with PRISMA guidelines. Data were extracted and analysed within a thematic analysis framework as described by Braun and Clarke . Ten papers based on eight studies were included, five (n = 355,010 participants) containing quantitative data and five reporting qualitative data (n = 395 participants). People with dementia who go undergo surgery experienced higher adverse post-operative outcomes such as respiratory problems or urinary tract infections. The key elements in surgical care for people with dementia included: health assessment throughout the surgical trajectory (pre-, intra- and post-operative) and the resources used by healthcare professionals in the peri-operative care. Healthcare professionals reported difficulties in the completion of health assessments due to the cognitive status of people with dementia and a lack of skills in dementia management. The use of restraints was still a common practice and a source of conflict. Dementia-specific training and guidelines focused on the care of surgical patients who have dementia in peri-operative environments are required to improve care and post-operative outcomes. More research is required to develop effective interventions to improve care and decrease the risk of complications for people with dementia in the peri-operative care environment

    Non-classical forms of pemphigus: pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus and IgG/IgA pemphigus

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    The pemphigus group comprises the autoimmune intraepidermal blistering diseases classically divided into two major types: pemphigus vulgaris and pemphigus foliaceous. Pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus and IgG/IgA pemphigus are rarer forms that present some clinical, histological and immunopathological characteristics that are different from the classical types. These are reviewed in this article. Future research may help definitively to locate the position of these forms in the pemphigus group, especially with regard to pemphigus herpetiformis and the IgG/ IgA pemphigus.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Dermatology DepartmentUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Dermatology and Pathology DepartmentsUNIFESP, EPM, Dermatology DepartmentUNIFESP, EPM, Dermatology and Pathology DepartmentsSciEL

    Insight into the Leukemia Microenvironment and Cell-cell Interactions Using Flow Cytometry

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    Cancer cells, including leukemia cells, reside in a complex microenvironment, which influences biology and activity of the cells. The protective role of bone marrow stromal cells is already commonly recognized. Remodeling of stroma cell functions by leukemia cells is also well documented. In this respect, different routes of interactions were defined, such as direct cell-cell interactions or indirect cross talk, by release of soluble factors or vesicular particles containing proteins, RNAs and other molecules. Since intercellular communication seems to play a role in various biological processes, it might be important to conduct studies in co-culture systems, which at least mimic partially more physiological conditions, and enables this intercellular exchange to occur. Thus, it is crucial to improve analytical methods of investigation of co-cultured cells, to study their interactions and so to understand biology of leukemia in order to understand molecular mechanisms and offer novel therapeutic strategies. The present chapter outlines the importance of modern, multiparameter flow cytometry methods, which allow to analyze interactions between different types of cells within the leukemia microenvironment. Importantly, the proposed experimental setups can be easily transformed to study different cell types and different biological systems

    Obtención de shortenings cero-trans con alta estabilidad termo-oxidativa por transesterificación enzimática

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    Novel zero-trans frying shortenings were formed by enzymatic transesterification by exploring a palm stearin and canola oil mixture and stearic acid as substrates. Both immobilized (Novozym 435, Lipase PS “Amano” IM) and non-immobilized (Lipomod TM 34P) enzymes were applied as biocatalysts. Palmitic acid, the fatty acid which defines the proper type of crystal formation, was present at the 15% level in the reaction mixtures. The novel structured lipids had comparable physical properties and offered similar frying performance to those of commercial shortening. Needle-shaped crystals were predominant both in the transesterification products and the commercial frying shortening. Furthermore, solid fat content profiles of the zero-trans structured lipids produced by Novozym 435 and Lipase PS “Amano” IM were close to those of the commercial shortening.Los innovadores shortenings cero-trans para frituras se obtenían por transesterificación enzimática utilizando como sustratos una mezcla de estearina de palma con aceite de cánola y ácido esteárico. Tanto las enzimas inmovilizadas (Novozym 435, Lipase PS “Amano” IM) como las no inmovilizadas (Lipomod TM 34P) fueron aplicadas como biocatalizadores. El contenido de ácido palmítico, el ácido graso que define el tipo adecuado de formación cristalina, fue del 15% en las mezclas de reacción. Los lípidos estructurados innovadores tenían propiedades físicas comparables a los shortenings comerciales y estabilidad de oxidación térmica similar en proceso de fritura. Los cristales en forma de aguja predominaban tanto en los productos de transesterificación como en los shortenings para frituras disponible en el mercado. Además, los perfiles de contenido de grasa sólida de los lípidos estructurados cero trans producidos por Novozym 435 y Lipase PS “Amano” IM eran similares a los perfiles de los shortenings comerciales

    Pseudo‐ Para ‐Substituted [2.2]Paracyclophanes for Hole Transport in Perovskite Solar Cells

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    2,2′,7,7′-Tetrakis(N,N-di-p-methoxyphenylamine)−9,9′-spirobifluorene (spiro-OMeTAD) is the prevalent hole transport layer in perovskite solar cells (PSCs) with regular device architecture. Yet, its spirobifluorene core and multistep synthesis make it rather expensive. For the further technological success of PSCs, novel scalable and inexpensive alternative hole transport layers are needed. Herein, a study of the structure-property relations of pseudo-para-substituted [2.2]paracyclophanes is presented. Eight different hole transport materials are synthesized via double CH activation, eliminating metal-containing substituents for cross-coupling reactions. The ionization potentials (IPs) of the disubstituted paracyclophanes (DiPCPs) are examined by photoelectron spectroscopy in air, cyclic voltammetry and theoretical calculations. Through variation of donor groups and π-linkers, IPs that span a range from 5.14 to 5.86 eV are achieved, demonstrating high customizability. From the eight novel materials, five showed good solubility and are implemented into PSCs. The solar cells with a hole transport layer of undoped 4,16-di(4-(2-thienyl)-N,N-bis(4-methoxyphenyl)aniline)[2.2]paracyclophane (DiPCP-2) exhibit a power conversion efficiency of 12.7% ± 0.4%. The facile synthesis of DiPCP-2 enables an estimated cost reduction by two thirds compared to spiro-OMeTAD
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