38 research outputs found

    Phase- coherent comparison of two optical frequency standards over 146 km using a telecommunication fiber link

    Get PDF
    We have explored the performance of two "dark fibers" of a commercial telecommunication fiber link for a remote comparison of optical clocks. The two fibers, linking the Leibniz University of Hanover (LUH) with the Physi-kalisch-Technische Bundesanstalt (PTB) in Braunschweig, are connected in Hanover to form a total fiber length of 146 km. At PTB the performance of an optical frequency standard operating at 456 THz was imprinted to a cw trans-fer laser at 194 THz, and its frequency was transmitted over the fiber. In order to detect and compensate phase noise related to the optical fiber link we have built a low-noise optical fiber interferometer and investigated noise sources that affect the overall performance of the optical link. The frequency stability at the remote end has been measured using the clock laser of PTB's Yb+ frequency standard operating at 344 THz. We show that the frequency of a frequency-stabilized fiber laser can be transmitted over a total fiber length of 146 km with a relative frequency uncertainty below 1E-19, and short term frequency instability given by the fractional Allan deviation of sy(t)=3.3E-15/(t/s)

    Development and evaluation of a standardized registry for diabetes in pregnancy using data from the Northern, North West and East Anglia regional audits

    No full text
    Objectives: To develop and evaluate a standardized data set for measuring pregnancy outcomes in women with Type 1 and Type 2 diabetes and to compare recent outcomes with those of the 2002–2003 Confidential Enquiry into Maternal and Child Health. Methods: Existing regional, national and international data sets were compared for content, consistency and validity to develop a standardized data set for diabetes in pregnancy of 46 key clinical items. The data set was tested retrospectively using data from 2007–2008 pregnancies included in three regional audits (Northern, North West and East Anglia). Obstetric and neonatal outcomes of pregnancies resulting in a stillbirth or live birth were compared with those from the same regions during 2002–2003. Results: Details of 1381 pregnancies, 812 (58.9%) in women with Type 1 diabetes and 556 (40.3%) in women with Type 2 diabetes, were available to test the proposed standardized data set. Of the 46 data items proposed, only 16 (34.8%), predominantly the delivery and neonatal items, achieved ≥ 85% completeness. Ethnic group data were available for 746 (54.0%) pregnancies and BMI for 627 (46.5%) pregnancies. Glycaemic control data were most complete—available for 1217 pregnancies (88.1%), during the first trimester. Only 239 women (19.9%) had adequate pregnancy preparation, defined as pre‐conception folic acid and first trimester HbA1c≤ 7% (≤ 53 mmol/mol). Serious adverse outcome rates (major malformation and perinatal mortality) were 55/1000 and had not improved since 2002–2003. Conclusions: A standardized data set for diabetes in pregnancy may improve consistency of data collection and allow for more meaningful evaluation of pregnancy outcomes in women with pregestational diabetes

    Capturing lay perspectives in a randomized control trial of a health promotion intervention for people with osteoarthritis of the knee

    No full text
    Osteoarthritis (OA) is a common and often disabling condition that predominately affects older adults. It is the commonest cause of locomotor disability and forms a major element of the workload in primary care. Previous studies suggest that there are both deficits in the knowledge patients have about their disease and extensive 'unmet' information needs. This paper explores the patients' perspective on the meaning and significance of living with arthritis, identified through quantitative and qualitative approaches undertaken during a trial that evaluated the effectiveness of a primary care-based patient education programme. This paper draws on qualitative and quantitative data from: the baseline interview (knowledge of arthritis, satisfaction with services and support received in primary care); patient diaries (individual goals and reflections on treatment); and group teaching sessions (themes describing the patient's experience). The different data sources were interrogated for common and divergent themes. One hundred and ninety-four participants were identified and 170 completed baseline interviews. Participants were predominantly female (73%), with a mean age of 63 and arthritis of long-standing; 55% reported that they had had it for 5 years or more. Use of primary care services was high, with 41% consulting their GP in the 2 weeks before interview. Levels of information were low, with less than 25% receiving support/advice about the disease, pain management or its impact upon daily life. Set against negative perceptions of the quality of services, patients' personal priorities were for improved pain management and enhanced mobility/functional ability. The combined quantitative and qualitative data provide insight into the patients' perspective on the causes and impact of knee OA, individual goals desired from treatment and the quality of care. There is consistent evidence of unmet needs for information and support and the priority placed by patients on finding strategies to cope with OA and maintaining independence. Even within a tightly defined study sample participating in the intervention, a diversity of experience and goals were revealed, which highlights the importance of taking account of contextual factors and individual differences when evaluating complex interventions
    corecore