478 research outputs found

    Timing Measurements of the Relativistic Binary Pulsar PSR B1913+16

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    We present results of more than three decades of timing measurements of the first known binary pulsar, PSR B1913+16. Like most other pulsars, its rotational behavior over such long time scales is significantly affected by small-scale irregularities not explicitly accounted for in a deterministic model. Nevertheless, the physically important astrometric, spin, and orbital parameters are well determined and well decoupled from the timing noise. We have determined a significant result for proper motion, μα=−1.43±0.13\mu_{\alpha} = -1.43\pm0.13, μδ=−0.70±0.13\mu_{\delta}=-0.70\pm0.13 mas yr−1^{-1}. The pulsar exhibited a small timing glitch in May 2003, with Δf/f=3.7×10−11{\Delta f}/f=3.7\times10^{-11}, and a smaller timing peculiarity in mid-1992. A relativistic solution for orbital parameters yields improved mass estimates for the pulsar and its companion, m_1=1.4398\pm0.0002 \ M_{\sun} and m_2=1.3886\pm0.0002 \ M_{\sun}. The system's orbital period has been decreasing at a rate 0.997±0.0020.997\pm0.002 times that predicted as a result of gravitational radiation damping in general relativity. As we have shown before, this result provides conclusive evidence for the existence of gravitational radiation as predicted by Einstein's theory.Comment: Published in APJ, 722, 1030 (2010

    Two High-Sensitivity Pulsar Searches

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    We have undertaken a program of two searches at radio wavelengths for pulsars using the Arecibo Observatory. One search covered 70 square degrees of sky along the Galactic plane with sensitivity to pulsars with periods as short as 1 ms. The second search covered 170 square degrees between Galactic latitudes -50° and -30° with sensitivity to pulsars with periods of 0.5 ms or more. The sensitivity to long-period pulsars in both surveys was of order 1 mJy, with reduced sensitivity at the shortest periods. Twenty-five pulsars were detected between the two surveys. Ten of these had previously been discovered. Of the remaining fifteen new pulsars, thirteen are relatively young, slow pulsars, with periods between 0.212 s and 5.094 s. The latter period is the longest of any known radio pulsar; this pulsar also has an extraordinarily short duty cycle of 0.4%. Two millisecond pulsars were found. PSR J2019+2425 has a period of 3.934 ms and is at a distance of 1 kpc. It is in a 76.5-day binary orbit with a 0.3 M companion. Its orbital eccentricity is 1.1 x 10^-4. The spin-down rate of this pulsar is extremely small, and its evolutionary timescale of 9 x 10^9 yr is the longest of any known pulsar. Both the low eccentricity and the long evolutionary timescale put limits on violations of the strong equivalence principle which are competitive with the best previous limits. The second newly found millisecond pulsar, PSR J2322+2057, has a period of 4.808 ms and a distance of 0.8 kpc. It is the second isolated millisecond pulsar found outside of globular clusters. Its distance of nearly 0.5 kpc from the Galactic plane suggests that millisecond pulsars have a large scale height

    An evaluation of a multi-site community pharmacy based chronic obstructive pulmonary disease support service

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    Background Chronic obstructive pulmonary disease (COPD) is a progressive chronic condition which can be effectively managed by smoking cessation, optimising prescribed therapy and providing treatment to prevent chest infections from causing hospitalisation. The government agenda in the UK is for community pharmacists to become involved in chronic disease management and COPD is one area where they are ideally located to provide a comprehensive service. Objective To evaluate the effect of a community pharmacy based COPD service on patient outcomes. Method Patients in one UK location were recruited over a 3 month period to receive a community pharmacy based COPD support service consisting of signposting to or provision of smoking cessation service, therapy optimisation, and recommendation to obtain a rescue pack containing steroid and antibiotic to prevent hospitalisation as a result of chest infection. Data was collected over a six month period for all recruited patients. Appropriate clinical outcomes, patient reported medication adherence, quality of life and NHS resource utilisation were measured. Key findings 306 patients accessed the service and full data to enable comparison before and after was available for 137. Significant improvements in patient reported adherence, utilisation of rescue packs, quality of life and a reduction in routine GP visits were identified. The intervention cost was estimated to be off-set by reductions in the use of other NHS services (GP and A&E visits and hospital admissions). Conclusion Results suggest that the service improved patient medicine taking behaviours and that it was cost-effective

    The four or more medicines (FOMM) support service:results from an evaluation of a new community pharmacy service aimed at over-65s

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    Background: 57% of all prescriptions dispensed in the UK in 2003 were for people aged ≥60, where ≥20% of them were prescribed ≥ five medicines. Inappropriate prescribing and non-adherence have a significant impact on hospital admissions and patient quality of life. The English government has identified that community pharmacy could make a significant contribution to reducing non-adherence and improving the quality of prescribing, reducing both hospital admissions and medicines wastage. Objective: To evaluate a community pharmacy service aimed at patients over the age of 65 years prescribed four or more medicines. Method: Patients were invited to participate in the service by the community pharmacy team. The pharmacist held regular consultations with the patient and discussed risk of falls, pain management, adherence and general health. They also reviewed the patient’s medication using STOPP/START criteria. Data wereas analysed for the first six months of participation in the service. Key findings: 620 patients were recruited with 441 (71.1%) completing the six month study period. Pharmacists made 142 recommendations to prescribers in 110 patients largely centred on potentially inappropriate prescribing of NSAIDs, PPIs or duplication of therapy. At follow-up there was a significant decrease in the total number of falls (mean -0.116 (-0.217 - -0.014)) experienced and a significant increase in medicines adherence (mean difference in MMAS-8: 0.513 (0.337 – 0.689)) and quality of life. Cost per QALY estimates ranged from £11,885 to £32,466 depending on the assumptions made. Conclusion: By focussing on patients over the age of 65 years with four or more medicines, community pharmacists can improve medicines adherence and patient quality of life
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