2,827 research outputs found

    Tailoring correlations of the local density of states in disordered photonic materials

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    We present experimental evidence for the different mechanisms driving the fluctuations of the local density of states (LDOS) in disordered photonic systems. We establish a clear link between the microscopic structure of the material and the frequency correlation function of LDOS accessed by a near-field hyperspectral imaging technique. We show, in particular, that short- and long-range frequency correlations of LDOS are controlled by different physical processes (multiple or single scattering processes, respectively) that can be---to some extent---manipulated independently. We also demonstrate that the single scattering contribution to LDOS fluctuations is sensitive to subwavelength features of the material and, in particular, to the correlation length of its dielectric function. Our work paves a way towards a complete control of statistical properties of disordered photonic systems, allowing for designing materials with predefined correlations of LDOS.Comment: 5+9 pages, 5+6 figures. Fixed confusion of references between the main text and the supplemental material in version

    Characterising extant technology related barriers & enablers for streamlined delivery of BP@home in North Central London: Report for NCL LTC Clinical Network

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    Report objectives: This report summarises the key findings of a place-based evaluation to identify barriers and enablers to the streamlined use of digital tools to support successful implementation of BP@home in North Central London (NCL). Specifically, we characterised the IT landscape in NCL, investigated the views and experiences of HCPs regarding the use of place-based IT solutions and processes, and synthesised a list of evidence-based recommendations for the consideration of NCL leadership team. Methods: We used a mixed methods research approach and six phases of investigation to address these aims, including desktop research, personal interviews and focus groups, action research, data analysis, synthesis and reporting. Results: The evaluation showed that there was a lack of standardisation across IT systems, internal processes and templates in PCNs in NCL, leading to challenges in implementing and using digital tools to support BP@home. These challenges were not unique to NCL. AccurX and the locally created NCL template are the most widely used IT tools to support the program in NCL. Other digital platforms being tested in NCL include Suvera, each with unique strengths and weaknesses. Other digital tools, such as Omron Connect, could be considered to support management of hypertension and other chronic conditions. HCPs faced challenges with patient engagement, data quality, IT system integration and resource allocation, but generally felt that the current approach works. Basic requirements for the use and adoption of IT tools and systems include adequate resources, stakeholder engagement, user-friendly interfaces, and interoperability between different systems. We proposed 16 actionable insights and recommendations that could be implemented to help improve the delivery of BP@home in NCL. These include standardising IT systems, improving patient engagement, providing adequate training and support, and promoting the benefits of remote monitoring. Conclusion: On balance, we recommend that NCL continues to deliver BP@home using the current standard IT offer that facilitates asynchronous engagement with patients (i.e., AccurX). Embedding a quality improvement approach to identify mechanisms to continually improve the BP@home offer in NCL is recommended. Clinical leadership could also review the evaluation findings of alternative tools currently being tested locally (e.g., pilot using Suvera across one PCN) to drive evidence-based commissioning decision as the BP@home initiative becomes even more embedded in routine general practice

    Associations of body shape phenotypes with sex steroids and their binding proteins in the UK Biobank cohort

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    Associations of sex steroids and their binding proteins with body shape are unclear, because waist and hip circumference are correlated strongly with body size. We defined body shape using “a body shape index” (ABSI) and hip index (HI), which are independent of weight and height by design, and examined associations in multivariable generalised linear models for the UK Biobank cohort (179,902 men, 207,444 women). Total testosterone was associated inversely with ABSI, especially in men. Free testosterone was lowest for large-ABSI-large-HI (“wide”) and highest for small-ABSI-small-HI (“slim”) in men, but lowest for small-ABSI-large-HI (“pear”) and highest for large-ABSI-small-HI (“apple”) in women. Oestradiol was associated inversely with ABSI in obese pre-menopausal women but positively with HI in obese men and post-menopausal women not using hormone replacement therapy. Sex-hormone binding globulin (SHBG) was associated inversely with ABSI but positively with HI and was lowest for “apple” and highest for “pear” phenotype in both sexes. Albumin was associated inversely with HI in women, but matched the pattern of free testosterone in obese men (lowest for “wide”, highest for “slim” phenotype). In conclusion, sex steroids and their binding proteins are associated with body shape, including hip as well as waist size, independent of body size

    Interactions of platelets with obesity in relation to lung cancer risk in the UK Biobank cohort

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    Background: Platelet count (PLT) is associated positively with lung cancer risk but has a more complex association with body mass index (BMI), positive only in women (mainly never smokers) and inverse in men (mainly ever smokers), raising the question whether platelets interact with obesity in relation to lung cancer risk. Prospective associations of platelet size (an index of platelet maturity and activity) with lung cancer risk are unclear. Methods: We examined the associations of PLT, mean platelet volume (MPV), and platelet distribution width (PDW) (each individually, per one standard deviation increase) with lung cancer risk in UK Biobank men and women using multivariable Cox proportional hazards models adjusted for BMI and covariates. We calculated Relative Excess Risk from Interaction (RERI) with obese (BMI ≄30 kg/m2), dichotomising platelet parameters at ≄median (sex-specific), and multiplicative interactions with BMI (continuous scale). We examined heterogeneity according to smoking status (never, former, current smoker) and antiaggregant/anticoagulant use (no/yes). Results: During a mean follow-up of 10.4 years, 1620 lung cancers were ascertained in 192,355 men and 1495 lung cancers in 218,761 women. PLT was associated positively with lung cancer risk in men (hazard ratio HR=1.14; 95% confidence interval (CI): 1.09–1.20) and women (HR=1.09; 95%CI: 1.03–1.15) but interacted inversely with BMI only in men (RERI=-0.53; 95%CI: -0.80 to -0.26 for high-PLT-obese; HR=0.92; 95%CI=0.88–0.96 for PLTBMI). Only in men, MPV was associated inversely with lung cancer risk (HR=0.95; 95%CI: 0.90–0.99) and interacted positively with BMI (RERI=0.27; 95%CI=0.09–0.45 for high-MPV-obese; HR=1.08; 95%CI=1.04–1.13 for MPVBMI), while PDW was associated positively (HR=1.05; 95%CI: 1.00–1.10), with no evidence for interactions. The associations with PLT were consistent by smoking status, but MPV was associated inversely only in current smokers and PDW positively only in never/former smokers. The interactions with BMI were retained for at least eight years of follow-up and were consistent by smoking status but were attenuated in antiaggregant/anticoagulant users. Conclusions: In men, PLT was associated positively and MPV inversely with lung cancer risk and these associations appeared hindered by obesity. In women, only PLT was associated positively, with little evidence for interaction with obesity

    Sex differences in the associations of body size and body shape with platelets in the UK Biobank cohort

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    Background: Obesity is accompanied with low-grade inflammation and leucocytosis and increases the risk of venous thromboembolism. Associations with platelet count, however, are unclear because several studies have reported positive associations only in women. Associations with body shape are also unclear, because waist and hip circumferences reflect overall body size, as well as body shape, and are correlated strongly positively with body mass index (BMI). Methods: We evaluated body shape with the allometric body shape index (ABSI) and hip index (HI), which reflect waist and hip size among individuals with the same weight and height and are uncorrelated with BMI. We examined the associations of BMI, ABSI, and HI with platelet count, mean platelet volume (MPV), and platelet distribution width (PDW) in multivariable linear regression models for 125,435 UK Biobank women and 114,760 men. We compared men with women, post-menopausal with pre-menopausal women, and older (≄52 years) with younger (<52 years) men. Results: BMI was associated positively with platelet count in women, more strongly in pre-menopausal than in post-menopausal, and weakly positively in younger men but strongly inversely in older men. Associations of BMI with platelet count were shifted towards the inverse direction for daily alcohol consumption and current smoking, resulting in weaker positive associations in women and stronger inverse associations in men, compared to alcohol≀3 times/month and never smoking. BMI was associated inversely with MPV and PDW in pre-menopausal women but positively in post-menopausal women and in men. ABSI was associated positively with platelet count, similarly in women and men, while HI was associated weakly inversely only in women. ABSI was associated inversely and HI positively with MPV but not with PDW and only in women. Platelet count was correlated inversely with platelet size and positively with leucocyte counts, most strongly with neutrophils. Conclusions: Competing factors determine the associations of BMI with platelet count. Factors with sexually-dimorphic action (likely thrombopoietin, inflammatory cytokines, or cortisol), contribute to a positive association, more prominently in women than in men, while age-dependent factors (likely related to liver damage and fibrosis), contribute to an inverse association, more prominently in men than in women

    A Body Shape Index (ABSI), hip index and risk of cancer in the UK Biobank cohort

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    Abdominal size is associated positively with the risk of some cancers but the influence of body mass index (BMI) and gluteofemoral size is unclear because waist and hip circumference are strongly correlated with BMI. We examined associations of 33 cancers with A Body Shape Index (ABSI) and hip index (HI), which are independent of BMI by design, and compared these with waist and hip circumference, using multivariable Cox proportional hazards models in UK Biobank. During a mean follow up of seven years, 14,682 incident cancers were ascertained in 200,289 men and 12,965 cancers in 230,326 women. In men, ABSI was associated positively with cancers of the head and neck (hazard ratio HR=1.14; 95% confidence interval 1.03-1.26 per one standard deviation increment), oesophagus (adenocarcinoma, HR=1.27; 1.12-1.44), gastric cardia (HR=1.31; 1.07-1.61), colon (HR=1.18; 1.10-1.26), rectum (HR=1.13; 1.04-1.22), lung (adenocarcinoma, HR=1.16; 1.03-1.30; squamous-cell carcinoma (SCC), HR=1.33; 1.17-1.52), and bladder (HR=1.15; 1.04-1.27), while HI was associated inversely with cancers of the oesophagus (adenocarcinoma, HR=0.89; 0.79-1.00), gastric cardia (HR=0.79; 0.65-0.96), colon (HR=0.92; 0.86-0.98), liver (HR=0.86; 0.75-0.98), and multiple myeloma (HR=0.86; 0.75-1.00). In women, ABSI was associated positively with cancers of the head and neck (HR=1.27; 1.10-1.48), oesophagus (SCC, HR=1.37; 1.07-1.76), colon (HR=1.08; 1.01-1.16), lung (adenocarcinoma, HR=1.17; 1.06-1.29; SCC, HR=1.40; 1.20-1.63; small-cell, HR=1.39; 1.14-1.69), kidney (clear-cell, HR=1.25; 1.03-1.50), and post-menopausal endometrium (HR=1.11; 1.02-1.20), while HI was associated inversely with skin SCC (HR=0.91; 0.83-0.99), post-menopausal kidney cancer (HR=0.77; 0.67-0.88) and post-menopausal melanoma (HR=0.90; 0.83-0.98). Unusually, ABSI was associated inversely with melanoma in men (HR=0.89; 0.82-0.96) and pre-menopausal women (HR=0.77; 0.65-0.91). Waist and hip circumference reflected associations with BMI, when examined individually, and provided biased risk estimates, when combined with BMI. In conclusion, preferential positive associations of ABSI or inverse of HI with several major cancers indicate an important role of factors determining body shape in cancer development

    Photon recycling in Fabry-Perot micro-cavities based on Si3_3N4_4 waveguides

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    We present a numerical analysis and preliminary experimental results on one-dimensional Fabry-Perot micro-cavities in Si3_3N4_4 waveguides. The Fabry-Perot micro-cavities are formed by two distributed Bragg reflectors separated by a straight portion of waveguide. The Bragg reflectors are composed by a few air slits produced within the Si3_3N4_4 waveguides. In order to increase the quality factor of the micro-cavities, we have minimized, with a multiparametric optimization tool, the insertion loss of the reflectors by varying the length of their first periods (those facing the cavity). To explain the simulation results the coupling of the fundamental waveguide mode with radiative modes in the Fabry-Perot micro-cavities is needed. This effect is described as a recycling of radiative modes in the waveguide. To support the modelling, preliminary experimental results of micro-cavities in Si3_3N4_4 waveguides realized with Focused Ion Beam technique are reported.Comment: 5 pages, 5 figure

    Associations of body shape index (ABSI) and hip index with liver, metabolic, and inflammatory biomarkers in the UK Biobank cohort

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    Associations of liver, metabolic, and inflammatory biomarkers in blood with body shape are unclear, because waist circumference (WC) and hip circumference (HC) are dependent on overall body size, resulting in bias. We have used the allometric “a body shape index” (ABSI = WC(mm)∗Weight(kg)-2/3∗Height(m)5/6) and hip index (HIwomen = HC(cm)∗Weight(kg)-0.482∗Height(cm)0.310, HImen = HC(cm)∗Weight(kg)-2/5∗Height(cm)1/5), which are independent of body mass index (BMI) by design, in multivariable linear regression models for 121,879 UK Biobank men and 135,559 women. Glucose, glycated haemoglobin (HbA1c), triglycerides, low-density-lipoprotein cholesterol, apolipoprotein-B, alanine aminotransferase (ALT), gamma-glutamyltransferase, and lymphocytes were associated positively with BMI and ABSI but inversely with HI. High-density-lipoprotein cholesterol and apolipoprotein-A1 were associated inversely with BMI and ABSI but positively with HI. Lipid-related biomarkers and ALT were associated only with HI in obese men. C-reactive protein, neutrophils, monocytes, and alkaline phosphatase were associated positively, while bilirubin was associated inversely, with BMI and ABSI but not with HI. Associations were consistent within the clinical reference ranges but were lost or changed direction for low or high biomarker levels. Our study confirms associations with waist and hip size, independent of BMI, for metabolic biomarkers but only with waist size for inflammatory biomarkers, suggesting different contribution of the mechanistic pathways related to body shape
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