139 research outputs found

    An extended Filon--Clenshaw--Curtis method for high-frequency wave scattering problems in two dimensions

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    We study the efficient approximation of integrals involving Hankel functions of the first kind which arise in wave scattering problems on straight or convex polygonal boundaries. Filon methods have proved to be an effective way to approximate many types of highly oscillatory integrals, however finding such methods for integrals that involve non-linear oscillators and frequency-dependent singularities is subject to a significant amount of ongoing research. In this work, we demonstrate how Filon methods can be constructed for a class of integrals involving a Hankel function of the first kind. These methods allow the numerical approximation of the integral at uniform cost even when the frequency ω\omega is large. In constructing these Filon methods we also provide a stable algorithm for computing the Chebyshev moments of the integral based on duality to spectral methods applied to a version of Bessel's equation. Our design for this algorithm has significant potential for further generalisations that would allow Filon methods to be constructed for a wide range of integrals involving special functions. These new extended Filon methods combine many favourable properties, including robustness in regard to the regularity of the integrand and fast approximation for large frequencies. As a consequence, they are of specific relevance to applications in wave scattering, and we show how they may be used in practice to assemble collocation matrices for wavelet-based collocation methods and for hybrid oscillatory approximation spaces in high-frequency wave scattering problems on convex polygonal shapes

    The growth of cubic CdS on InP(110) studied in situ by Raman spectroscopy

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    CdS was deposited onto clean cleaved InP(110) by molecular beam epitaxy (MBE) using a growth rate of 0.2 monolayers/min and a substrate temperature of 440 K (510 K). Raman spectra were taken in situ of the clean InP surface and after each evaporation step using an Ar+ ion laser as a light source. Due to this resonant excitation scattering signals originating from the CdS deposition are observed at coverages as low as 2 monolayers (ML). The number of phonon peaks observed and their selection rules reveal that the cubic modification is present. The spectra are dominated at all coverages by the longitudinal optical (LO) and 2LO phonon scattering intensities and the variation of the 2LO/LO intensity ratio with CdS deposition indicates changes in the electronic structure of the growing CdS. Another spectral feature in the Raman spectra is attributed to a chemically reacted layer at the interface most likely consisting of an In–S compound. The intensity of this feature is found to depend critically on the growth parameters, in particular the substrate temperature, but also on the operating time of the MBE cell. The amount of reaction at the interface also influences the critical CdS film thickness and the development of the 2LO/LO ratio. The results are discussed taking complementary photoluminescence, x‐ray diffraction, and photoemission data into account

    An interleukin-1 polymorphism additionally intensified by atopy as prognostic factor for aseptic non-mechanical complications in metal knee and hip arthroplasty

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    Background: In contrast to infection or mechanical issues joint replacement failure following inflammatory adverse reactions is poorly understood. Objective: To assess the association of IL-1β polymorphisms and history of allergy with aseptic non-mechanical complications following arthroplasty. Methods: In 102 patients with aseptic non-mechanically caused symptomatic knee or hip arthroplasty (SA) and 93 patients with asymptomatic arthroplasty (AA) questionnaire-based history, patch test with at least standard series, lymphocyte transformation test (LTT) with nickel, cobalt and chromium and interleukin-1 polymorphism analysis were done. Three polymorphisms of the IL1B gene [IL-1b -3954 (rs1143634), IL-1b -511 (rs16944) and IL-1b -31 (rs1143627)] and one polymorphism of the IL1RN gene [IL1RN intron 2, variable number of tandem repeats, VNTR (rs2234663)] were assessed by PCR and gel electrophoresis. Results: We found no significant difference in smoking history and atopy but 25% versus 10% of self-reported metal allergy in SA versus AA; the patch test (respective, LTT) for metal sensitivity was more often positive in SA patients. The allele 498 bp of the IL1RN polymorphism occurred significantly more often in the SA group (37% versus 11%; p < 0.0001). Upon additional presence of atopy, the difference was even greater (60% vs 10%) (p < 0.000001). There was no association of IL-1 polymorphisms with metal allergy. Conclusion: The IL1RN VNTR allele 498 bp was strongly associated with SA. In patients with a history of atopy, presence of the IL1RN VNTR allele 498 bp led to a four-fold higher SA prevalence compared to patients without this allele

    Spinal cord from body donors is suitable for multicolor immunofluorescence

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    Immunohistochemistry is a powerful tool for studying neuronal tissue from humans at the molecular level. Obtaining fresh neuronal tissue from human organ donors is difficult and sometimes impossible. In anatomical body donations, neuronal tissue is dedicated to research purposes and because of its easier availability, it may be an alternative source for research. In this study, we harvested spinal cord from a single organ donor 2 h (h) postmortem and spinal cord from body donors 24, 48, and 72 h postmortem and tested how long after death, valid multi-color immunofluorescence or horseradish peroxidase (HRP) immunohistochemistry is possible. We used general and specific neuronal markers and glial markers for immunolabeling experiments. Here we showed that it is possible to visualize molecularly different neuronal elements with high precision in the body donor spinal cord 24 h postmortem and the quality of the image data was comparable to those from the fresh organ donor spinal cord. High-contrast multicolor images of the 24-h spinal cords allowed accurate automated quantification of different neuronal elements in the same sample. Although there was antibody-specific signal reduction over postmortem intervals, the signal quality for most antibodies was acceptable at 48 h but no longer at 72 h postmortem. In conclusion, our study has defined a postmortem time window of more than 24 h during which valid immunohistochemical information can be obtained from the body donor spinal cord. Due to the easier availability, neuronal tissue from body donors is an alternative source for basic and clinical research

    Practical implications of GPR investigation using 3D data reconstruction and transmission tomography

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    Non-destructive investigation using ground penetrating radar is becoming more popular in the inspection of civil structures. Currently, traditional 2D imaging is used as a preliminary tool to fi nd possible areas of interest for more detailed inspection, which can be accomplished by more advanced techniques like 3D image reconstruction or tomography. In this paper, a general overview of the work done at University of Minho regarding these techniques is presented, together with their limitations and advantages over typical radargrams, with implications for civil engineering applications. For this purpose, data acquisition on two large masonry walls and one large concrete specimen have been carried out, using refl ection mode, 3D reconstruction and transmission tomography. The specimens have been specially built for non-destructive inspection techniques testing, incorporating different materials and internal voids. Radar tomography and 3D image reconstruction techniques provided much more detailed information about structural integrity and shapes and location of the voids, when compared to 2D imaging originally used for potential target identification.Fundação para a Ciência e a Tecnologia (FCT) - POCTI SFRH/BD/6409/2001"Sustainable Bridges" European project - FP6-PLT-0165

    Prevalence and features of ICF-disability in Spain as captured by the 2008 National Disability Survey

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    <p>Abstract</p> <p>Background</p> <p>Since 1986, the study of disability in Spain has been mainly addressed by National Disability Surveys (NDSs). While international attempts to frame NDS designs within the International Classification of Functioning, Disability and Health (ICF) have progressed, in general, the ICF has hardly been used in either the NDS or epidemiological studies. This study sought to identify ICF Activity- and Participation-related content in the most recent Spanish NDS, the 2008 Survey on Disabilities, Independence and Dependency Situations (<it>Encuesta sobre discapacidades, autonomía personal y situaciones de Dependencia </it>- <it>EDAD 2008</it>), and estimate the prevalence of such ICF-framed disability.</p> <p>Methods</p> <p><it>EDAD 2008 </it>methods and questions were perused. Of the 51 EDAD items analysed, 29 were backcoded to specific d2-d7 domains of the ICF Checklist and, by rating the recorded difficulty to perform specific tasks with or without help, these were then taken as performance and capacity respectively. A global ICF score was also derived, albeit lacking data for d1, "Learning and applying knowledge", d8, "Major Life Areas" and d9, "Community, Social and Civic Life". Data were grouped by sex, age, residence and initial positive screening, and prevalence figures were calculated by disability level both for the general population, using the originally designed weights, and for the population that had screened positive to disability. Data for institutionalised persons were processed separately.</p> <p>Results</p> <p>Crude prevalence of ICF severe/complete and moderate disability among the community-dwelling population aged ≥6 years was 0.9%-2.2% respectively, and that of severe/complete disability among persons living in sheltered accommodation was 0.3%.</p> <p>Prevalence of severe/complete disability was: higher in women than in men, 0.8% vs. 0.4%; increased with age; and was particularly high in domains such as "Domestic Life", 3.4%, "Mobility", 1.8%, and "Self-care", 1.9%, in which prevalence decreased when measured by reference to performance. Moreover, global scores indicated that severe/complete disability in these same domains was frequent among the moderately disabled group.</p> <p>Conclusions</p> <p>The <it>EDAD 2008 </it>affords an insufficient data set to be ICF-framed when it comes to the Activity and Participation domains. Notwithstanding their unknown validity, ratings for available ICF domains may, however, be suitable for consideration under the ADL model of functional dependency, suggesting that there are approximately 500,000 persons suffering from severe/complete disability and 1,000,000 suffering from moderate disability, with half the latter being severely disabled in domains capable of benefiting from technical or personal aid. Application of EDAD data to the planning of services for regions and other subpopulations means that need for personal help must be assessed, unmet needs ascertained, and knowledge of social participation and support, particularly for the mentally ill, improved. International, WHO-supported co-operation in ICF planning and use of NDSs in Spain and other countries is needed.</p

    Analysis of landrace cultivation in Europe: A means to support in situ conservation of crop diversity

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    During the last century, the progressive substitution of landraces with modern, high yielding varieties, led to a dramatic reduction of in situ conserved crop diversity in Europe. Nowadays there is limited and scattered information on where landraces are cultivated. To fill this gap and lay the groundwork for a regional landrace in situ conservation strategy, information on more than 19,335 geo-referenced landrace cultivation sites were collated from 14 European countries. According to collected data, landraces of 141 herbaceous and 48 tree species are cultivated across Europe: Italy (107 species), Greece (93), Portugal (45) and Spain (44) hold the highest numbers. Common bean, onion, tomato, potato and apple are the species of main interest in the covered countries. As from collected data, about 19.8% of landrace cultivation sites are in protected areas of the Natura 2000 network. We also got evidence that 16.7% and 19.3% of conservation varieties of agricultural species and vegetables are currently cultivated, respectively. Results of the GIS analysis allowed the identification of 1261 cells (25 km × 25 km) including all the cultivation sites, distributed across all European biogeographical regions. Data of this study constitute the largest ever produced database of in situ-maintained landraces and the first attempt to create an inventory for the entire Europe. The availability of such resource will serve for better planning of actions and development of policies to protect landraces and foster their use

    Disability, support and long-term social care of an elderly Spanish population, 2008-2009: an epidemiologic analysis

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    BACKGROUND: Though poorly known, relationships between disability, need of help (dependency) and use of social services are crucial aspects of public health. The objective of this study was to describe the links between disability, officially assessed dependency, and social service use by an industrial population, and identify areas of inequity. METHODS: We took advantage of a door-to-door survey conducted in the Cinco Villas district, Spain, in 2008–2009, which provided data on disability, morbidity, and service use among 1216 residents aged ≥50 years, and officially assessed dependency under the 2006 Dependency Act (OAD). Using logistic regression, we combined data collected at homes/residences on 625 disability screened-positive participants, and administrative information on degree of OAD and benefits at date of visit. RESULTS: Based on 163 disabled persons, the prevalence of residential/community-care users was 13.4% overall, with 6.0% being market-provided, 2.5% supported by the 2006 Act, and 4.9% supported by other public funds. Of 111 OAD applicants, 30 had been assigned an OAD degree; in 29 cases this was the highest OAD degree, with 12 receiving direct support for residential care and 17 receiving home care. Compared to unassessed dependency, the highest OAD degree was linked to residential care (OR and 95% CI) 12.13 (3.86–38.16), declared non-professional care 10.99 (1.28–94.53), and publicly-funded, non-professional care 26.30 (3.36–205.88). In contrast, 43 persons, 58% of the severely/extremely disabled, community-dwelling sample population, 81% of whom were homebound, including 10 persons with OAD but no implemented service plan, made no use of any service, and of these, 40% lacked a non-professional carer. CONCLUSIONS: Formal service use in the Cinco Villas district attained ratios observed for established welfare systems but the publicly-funded proportion was lower. The 2006 Act had a modest, albeit significant, impact on support for non-professional carers and residential care, coexisting with a high prevalence of non-use of social services by severely disabled persons

    Epigenetic clock for skin and blood cells applied to Hutchinson Gilford Progeria Syndrome and ex vivo studies

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    DNA methylation (DNAm)-based biomarkers of aging have been developed for many tissues and organs. However, these biomarkers have sub-optimal accuracy in fibroblasts and other cell types used in ex vivo studies. To address this challenge, we developed a novel and highly robust DNAm age estimator (based on 391 CpGs) for human fibroblasts, keratinocytes, buccal cells, endothelial cells, lymphoblastoid cells, skin, blood, and saliva samples. High age correlations can also be observed in sorted neurons, glia, brain, liver, and even bone samples. Gestational age correlates with DNAm age in cord blood. When used on fibroblasts from Hutchinson Gilford Progeria Syndrome patients, this age estimator (referred to as the skin & blood clock) uncovered an epigenetic age acceleration with a magnitude that is below the sensitivity levels of other DNAm-based biomarkers. Furthermore, this highly sensitive age estimator accurately tracked the dynamic aging of cells cultured ex vivo and revealed that their proliferation is accompanied by a steady increase in epigenetic age. The skin & blood clock predicts lifespan and it relates to many age-related conditions. Overall, this biomarker is expected to become useful for forensic applications (e.g. blood or buccal swabs) and for a quantitative ex vivo human cell aging assay
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