10,990 research outputs found
Charge exchange contribution to the decay of the ring current, measured by energetic neutral atoms (ENAs)
In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases
Low-Altitude Reconnection Inflow-Outflow Observations during a 2010 November 3 Solar Eruption
For a solar flare occurring on 2010 November 3, we present observations using
several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope
followed by inflows sweeping into a current sheet region. The inflows are soon
followed by outflows appearing to originate from near the termination point of
the inflowing motion - an observation in line with standard magnetic
reconnection models. We measure average inflow plane-of-sky speeds to range
from ~150-690 km/s with the initial, high-temperature inflows being the
fastest. Using the inflow speeds and a range of Alfven speeds, we estimate the
Alfvenic Mach number which appears to decrease with time. We also provide
inflow and outflow times with respect to RHESSI count rates and find that the
fast, high-temperature inflows occur simultaneously with a peak in the RHESSI
thermal lightcurve. Five candidate inflow-outflow pairs are identified with no
more than a minute delay between detections. The inflow speeds of these pairs
are measured to be 10^2 km/s with outflow speeds ranging from 10^2-10^3 km/s -
indicating acceleration during the reconnection process. The fastest of these
outflows are in the form of apparently traveling density enhancements along the
legs of the loops rather than the loop apexes themselves. These flows could
either be accelerated plasma, shocks, or waves prompted by reconnection. The
measurements presented here show an order of magnitude difference between the
retraction speeds of the loops and the speed of the density enhancements within
the loops - presumably exiting the reconnection site.Comment: 31 pages, 13 figures, 1 table, Accepted to ApJ (expected publication
~July 2012
Effect of Financial Incentives on Incentivised and Non-Incentivised Clinical Activities: Utilising Primary Care Databases to answer clinical, policy and methodological questions
Are we there yet? Understanding the implementation of re-municipalization decisions and their duration
Studies of the drivers of the decision to re-municipalize have increased recently, but research on its implementation is very scarce. We analyse how service characteristics and institutional factors influence the implementation of re-municipalization. For that purpose, we use an extensive database on re-municipalization decisions, and analyse the available data by means of logistic and negative binomial regressions. Strong network characteristics are associated with lower probabilities of implementation and longer implementation processes. Re-municipalization of personal services is more likely to be fully implemented and is finalized faster. Interestingly, after the great recession the probability of implementing reforms increased
Why we need interprofessional education to improve the delivery of safe and effective care
Interprofessional education (IPE) is an activity that involves two or more professions who learn interactively together to improve collaboration and the quality of care. Research has continually revealed that health and social care professionals encounter a range of problems with interprofessional coordination and collaboration which impact on the quality and safety of care. This empirical work resulted in policymakers across health care education and practice to invest in IPE to help resolve this collaborative failures. It is anticipated that IPE will provide health and social care professionals with the abilities required to work together effectively in providing safe high quality care to patients. Through a discussion of a range of key professional, educational and organization issues related to IPE, this paper argues that this form of education is an important strategy to improve the delivery of safe and effective care
Can analyses of electronic patient records be independently and externally validated? The effect of statins on the mortality of patients with ischaemic heart disease: a cohort study with nested case-control analysis
Objective To conduct a fully independent and external validation of a research study based on one electronic health record database, using a different electronic database sampling the same population.
Design Using the Clinical Practice Research Datalink (CPRD), we replicated a published investigation into the effects of statins in patients with ischaemic heart disease (IHD) by a different research team using QResearch. We replicated the original methods and analysed all-cause mortality using: (1) a cohort analysis and (2) a case-control analysis nested within the full cohort.
Setting Electronic health record databases containing longitudinal patient consultation data from large numbers of general practices distributed throughout the UK.
Participants CPRD data for 34 925 patients with IHD from 224 general practices, compared to previously published results from QResearch for 13 029 patients from 89 general practices. The study period was from January 1996 to December 2003.
Results We successfully replicated the methods of the original study very closely. In a cohort analysis, risk of death was lower by 55% for patients on statins, compared with 53% for QResearch (adjusted HR 0.45, 95% CI 0.40 to 0.50; vs 0.47, 95% CI 0.41 to 0.53). In case-control analyses, patients on statins had a 31% lower odds of death, compared with 39% for QResearch (adjusted OR 0.69, 95% CI 0.63 to 0.75; vs OR 0.61, 95% CI 0.52 to 0.72). Results were also close for individual statins.
Conclusions Database differences in population characteristics and in data definitions, recording, quality and completeness had a minimal impact on key statistical outputs. The results uphold the validity of research using CPRD and QResearch by providing independent evidence that both datasets produce very similar estimates of treatment effect, leading to the same clinical and policy decisions. Together with other non-independent replication studies, there is a nascent body of evidence for wider validity
How to identify when a performance indicator has run its course
The official published version can be found at the link below.Increasing numbers of countries are using indicators to evaluate the quality of clinical care, with some linking payment to achievement. For performance frameworks to remain effective the indicators need to be regularly reviewed. The frameworks cannot cover all clinical areas, and achievement on chosen indicators will eventually reach a ceiling beyond which further improvement is not feasible. However, there has been little work on how to select indictors for replacement. The Department of Health decided in 2008 that it would regularly replace indicators in the national primary care pay for performance scheme, the Quality and Outcomes Framework, making a rigorous approach to removal a priority. We draw on our previous work on pay for performance and our current work advising the National Institute for Health and Clinical Excellence (NICE) on the Quality and Outcomes Framework to suggest what should be considered when planning to remove indicators from a clinical performance framework
Global energetic neutral atom (ENA) measurements and their association with the Dst index
We present a new global magnetospheric index that measures the intensity of the Earth\u27s ring current through energetic neutral atoms (ENAs). We have named it the Global Energetic Neutral Index (GENI), and it is derived from ENA measurements obtained by the Imaging Proton Spectrometer (IPS), part of the Comprehensive Energetic Particle and Pitch Angle Distribution (CEPPAD) experiment on the POLAR satellite. GENI provides a simple orbit-independent global sum of ENAs measured with IPS. Actual ENA measurements for the same magnetospheric state look different when seen from different points in the POLAR orbit. In addition, the instrument is sensitive to weak ion populations in the polar cap, as well as cosmic rays. We have devised a method for removing the effects of cosmic rays and weak ion fluxes, in order to produce an image of “pure” ENA counts. We then devised a method of normalizing the ENA measurements to remove the orbital bias effect. The normalized data were then used to produce the GENI. We show, both experimentally and theoretically the approximate proportionality between the GENI and the Dst index. In addition we discuss possible implications of this relation. Owing to the high sensitivity of IPS to ENAs, we can use these data to explore the ENA/Dst relationship not only during all phases of moderate geomagnetic storms, but also during quiescent ring current periods
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