943 research outputs found

    Search for new physics in semileptonic B-decays

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    Semileptonic decays provide an excellent environment for testing the Standard Model (SM). Violation of lepton universality would be a smoking gun for physics beyond the SM. Using semi-tauonic BB decays, LHCb finds a value of R(D∗)=B(Bˉ0→D∗+τ−Μˉτ)/B(Bˉ0→D∗+Ό−ΜˉΌ)=0.336±0.027(stat)±0.030(syst)\mathcal{R}(D^*) = \mathcal{B}(\bar{B}^0 \to D^{*+} \tau^{-} \bar{\nu}_{\tau})/\mathcal{B}(\bar{B}^0 \to D^{*+} \mu^{-} \bar{\nu}_{\mu}) = 0.336 \pm 0.027 \rm{(stat)} \pm 0.030 \rm{(syst)}, which is 2.1 standard deviations larger than the value expected from the SM. Moreover, the measurement of the CPCP asymmetry in mixing of Bs0B_s^0 mesons is highly sensitive to physics beyond the SM. This article presents the latest result on semileptonic asymmetries; using the full Run 1 dataset, it is found that asls=(0.39±0.26(stat)±0.20(syst))%a_{\rm{sl}}^s = (0.39 \pm 0.26 \rm{(stat)} \pm 0.20 \rm{(syst)})\%, which is consistent with the Standard Model.Comment: 6 pages, 8 figures, Contribution to the Proceedings of the 38th International Conference on High Energy Physics, ICHEP 2016, Chicago, IL, US

    Measuring Semileptonic Asymmetries in LHCb

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    The C ⁣PC\!P-violating flavour-specific asymmetry in neutral bb mesons provides a method for testing the Standard Model. The measurements from the D0 experiment yield values of this asymmetry that disagree with the Standard Model at a level of 3.6 σ\sigma. This contribution discusses the latest LHCb measurements in this sector both from B0B^0 mesons (aslda_{\mathrm{sl}}^d) and Bs0B^0_s mesons (aslsa_{\mathrm{sl}}^s). Using their 2011 dataset, corresponding to an integrated luminosity of 1.0 fb−1\mathrm{fb}^{-1} obtained in 2011, LHCb measured a value of asls=(−0.06±0.50stat±0.36syst)%a_{\mathrm{sl}}^s = (-0.06 \pm 0.50_{\text{stat}} \pm 0.36_{\text{syst}}) \%. Combining the 2011 and 2012 datasets, with an integrated luminosity of 3 fb−1\mathrm{fb}^{-1}, LHCb measured asld=(−0.02±0.19stat±0.30syst)%a_{\mathrm{sl}}^d = (-0.02 \pm 0.19_{\text{stat}} \pm 0.30_{\text{syst}}) \%. These are the most precise measurements of the parameters aslsa_{\mathrm{sl}}^s and aslda_{\mathrm{sl}}^d to date. Plans for an updated result for aslsa_{\mathrm{sl}}^s using the full 3 fb−1\mathrm{fb}^{-1} dataset are discussed. This will include new methods to determine detection asymmetries which are the dominating systematic uncertainty of the 2011 measurement.Comment: Proceedings of the workshop "Flavorful Ways to New Physics", 28-31 October 2014, Freudenstadt, German

    Impacts of radiative corrections on measurements of lepton flavour universality in B→DℓΜℓB \to D \ell \nu_{\ell} decays

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    Radiative corrections to B→DℓΜℓB \to D \ell \nu_{\ell} decays may have an impact on predictions and measurements of the lepton flavour universality observables R(D+)\mathcal{R}(D^+) and R(D0)\mathcal{R}(D^0). In this paper, a comparison between recent calculations of the effect of soft-photon corrections on R(D+)\mathcal{R}(D^+) and R(D0)\mathcal{R}(D^0), and corrections generated by the widely used package PHOTOS is given. The impact of long-distance Coulomb interactions, which are not simulated in PHOTOS, is discussed. Furthermore, the effect of high-energy photon emission is studied through pseudo-experiments in an LHCb-like environment. It is found that over- or underestimating these emissions can cause a bias on R(D)\mathcal{R}(D) as high as 7%. However, this bias depends on individual analyses, and future high precision measurements require an accurate evaluation of these QED corrections.Comment: 8 pages, 21 figures, published by EPJ

    Incidence and Risk Factors of Second Eye Involvement in Myopic Macular Neovascularization

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    Purpose: To report the cumulative incidence and risk factors of second eye involvement after diagnosis of myopic macular neovascularization (MNV) in the first eye. Design: Retrospective analysis of longitudinal data from a tertiary hospital in the Netherlands. Participants:Patients with high myopia (spherical equivalent [SE] ≀ − 6 diopters [D]), of European ethnicity, who were diagnosed with active MNV lesion in 1 eye between 2005 and 2018. Fellow eyes were free of MNV or macular atrophy at baseline, and data were collected on the SE, axial length, and presence of diffuse or patchy chorioretinal atrophy and lacquer cracks.Methods:Incidence rate and 2-, 5-, and 10-year cumulative incidences were calculated; hazard ratios (HRs) of second eye involvement were analyzed for potential risk factors using Cox proportional hazard models. Main outcomes measures: Incidence of second eye involvement after onset of myopic MNV in the first eye. Results: We included 88 patients over a period of 13 years with a mean age of 58 ± 15 years, mean axial length of 30 ± 1.7 mm and SE −14 ± 4 D at baseline. Twenty-four fellow eyes (27%) developed a myopic MNV during follow-up. This resulted in an incidence rate of 4.6 (95% confidence interval [CI], 2.9–6.7) per 100 person-years and a cumulative incidence of 8%, 21%, and 38% at 2, 5, and 10 years, respectively. Mean time until MNV development in the fellow eye was 48 ± 37 months. Patients aged &lt; 40 years at the initial presentation had a 3.8 times higher risk of bilateral myopic MNV (HR, 3.8; 95% CI, 1.65–8.69; P = 0.002). The presence of lacquer cracks in the second eye seemed to increase risk, but this did not reach statistical significance (HR, 2.25; 95% CI, 0.94–5.39; P = 0.07). Conclusions: Our study of high myopes of European descent shows very similar incidence rates for second eye myopic MNV compared with Asian studies. Our findings substantiate the importance for clinicians to monitor closely and create awareness, especially in younger patients. Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussed in this article.</p

    A view from the clinic – Perspectives from Dutch patients and professionals on high myopia care

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    Purpose: To understand and compare perspectives of patients and professionals on current ophthalmologic care for high myopia, and to identify challenges and future opportunities. Methods: Self-reported data were collected through two online questionnaires. Patient perspective was obtained from highly myopic members of a patient organisation based in the Netherlands using a 17-item questionnaire consisting of open and multiple-choice questions regarding personal experience with myopia care. The ophthalmologist perspective was obtained from practising Dutch ophthalmologists with a 12-item questionnaire of multiple-choice questions on work-related demographics, myopia care in daily practice and need for improvement. The response rate for patients was 27% (n = 136/500) and for ophthalmologists, 24% (n = 169/716). Results: Patients were highly concerned about personal progressive loss of vision (69%) and feared their psychological well-being (82%) in case this would happen. The quality of performance of care provided by ophthalmologists was rated as excellent or satisfactory by 64% of the patients. These ratings for multidisciplinary care and insurance reimbursement were as low as 28% and 18% respectively. The mean concern among ophthalmologists about the rise in high myopia was 6.9 (SEM 0.1) on a 10-point scale. Sixty-nine per cent of the ophthalmologists reported that asymptomatic myopic patients should not be examined regularly at outpatient clinics. Ophthalmologists urged the development of clinical guidelines (74%), but did report (95%) that they informed patients about risk factors and complications. This contrasted with the view of patients, of whom 42% were discontent with information provided by ophthalmologists. Conclusions: These questionnaires demonstrated that the current clinical care delivered to highly myopic patients is in need of improvement. The expected higher demand for myopia care in the near future requires preferred practice patterns, professionals specifically trained to manage myopic pathology, accurate and comprehensive information exchange and collaboration of in- and out-of-hospital professionals across the full eye care chain.</p

    Differences in clinical presentation of primary open-angle glaucoma between African and European populations

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    PURPOSE: Primary open‐angle glaucoma (POAG) has been reported to occur more frequently in Africans, and to follow a more severe course compared to Europeans. We aimed to describe characteristics of POAG presentation and treatment across three ethnic groups from Africa and one from Europe. METHODS: We ascertained 151 POAG patients from South African Coloured (SAC) and 94 South African Black (SAB) ethnicity from a university hospital in South Africa. In Tanzania, 310 patients were recruited from a university hospital and a referral hospital. In the Netherlands, 241 patients of European ancestry were included. All patients were over 35 years old and had undergone an extensive ophthalmic examination. Patients were diagnosed according to the ISGEO criteria. A biogeographic ancestry analysis was performed to estimate the proportion of genetic African ancestry (GAA). RESULTS: The biogeographic ancestry analysis showed that the median proportion of GAA was 97.6% in Tanzanian, 100% in SAB, 34.2% in SAC and 1.5% in Dutch participants. Clinical characteristics at presentation for Tanzanians, SAB, SAC and Dutch participants, respectively: mean age: 63, 57, 66, 70 years (p < 0.001); visual acuity in the worse eye: 1.78, 1.78, 0.3, 0.3 LogMAR (p < 0.001); maximum intraocular pressure of both eyes: 36, 34, 29, 29 mmHg (p (anova)  < 0.001); maximum vertical cup to disc ratio (VCDR) of both eyes: 0.90, 0.90, 0.84, 0.83 (p < 0.001); mean central corneal thickness: 506, 487, 511, 528 Όm (p < 0.001). Fourteen percent of Tanzanian patients presented with blindness (<3/60 Snellen) in the better eye in contrast to only 1% in the Dutch. CONCLUSION: In this multi‐ethnic comparative study, Sub‐Saharan Africans present at a younger age with lower visual acuity, higher IOP, larger VCDR, than SAC and Dutch participants. This indicates the more progressive and destructive course in Sub‐Saharan Africans

    LONGITUDINAL STUDY OF RPE65-ASSOCIATED INHERITED RETINAL DEGENERATIONS

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    PURPOSE: To study the disease course of RPE65-associated inherited retinal degenerations (IRDs) as a function of the genotype, define a critical age for blindness, and identify potential modifiers. METHODS: Forty-five patients with IRD from 33 families with biallelic RPE65 mutations, 28 stemming from a genetic isolate. We collected retrospective data from medical charts. Coexisting variants in 108 IRD-associated genes were identified with Molecular Inversion Probe analysis. RESULTS: Most patients were diagnosed within the first years of life. Daytime visual function ranged from near-normal to blindness in the first four decades and met WHO criteria for blindness for visual acuity and visual field in the fifth decade. p.(Thr368His) was the most common variant (54%). Intrafamilial variability and interfamilial variability in disease severity and progression were observed. Molecular Inversion Probe analysis confirmed all RPE65 variants and identified one additional variant in LRAT and one in EYS in two separate patients. CONCLUSION: All patients with RPE65-associated IRDs developed symptoms within the first year of life. Visual function in childhood and adolescence varied but deteriorated inevitably toward blindness after age 40. In this study, genotype was not predictive of clinical course. The variance in severity of disease could not be explained by double hits in other IRD genes

    A view from the clinic – Perspectives from Dutch patients and professionals on high myopia care

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    Purpose: To understand and compare perspectives of patients and professionals on current ophthalmologic care for high myopia, and to identify challenges and future opportunities. Methods: Self-reported data were collected through two online questionnaires. Patient perspective was obtained from highly myopic members of a patient organisation based in the Netherlands using a 17-item questionnaire consisting of open and multiple-choice questions regarding personal experience with myopia care. The ophthalmologist perspective was obtained from practising Dutch ophthalmologists with a 12-item questionnaire of multiple-choice questions on work-related demographics, myopia care in daily practice and need for improvement. The response rate for patients was 27% (n = 136/500) and for ophthalmologists, 24% (n = 169/716). Results: Patients were highly concerned about personal progressive loss of vision (69%) and feared their psychological well-being (82%) in case this would happen. The quality of performance of care provided by ophthalmologists was rated as excellent or satisfactory by 64% of the patients. These ratings for multidisciplinary care and insurance reimbursement were as low as 28% and 18% respectively. The mean concern among ophthalmologists about the rise in high myopia was 6.9 (SEM 0.1) on a 10-point scale. Sixty-nine per cent of the ophthalmologists reported that asymptomatic myopic patients should not be examined regularly at outpatient clinics. Ophthalmologists urged the development of clinical guidelines (74%), but did report (95%) that they informed patients about risk factors and complications. This contrasted with the view of patients, of whom 42% were discontent with information provided by ophthalmologists. Conclusions: These questionnaires demonstrated that the current clinical care delivered to highly myopic patients is in need of improvement. The expected higher demand for myopia care in the near future requires preferred practice patterns, professionals specifically trained to manage myopic pathology, accurate and comprehensive information exchange and collaboration of in- and out-of-hospital professionals across the full eye care chain
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