Identification of patients for clinical risk assessment by prediction of cardiovascular risk using default risk factor values

Abstract Background To identify high risk patients without cardiovascular disease requires assessment of risk factors. Primary care providers must therefore determine which patients without cardiovascular disease should be highest priority for cardiovascular risk assessment. One approach is to prioritise patients for assessment using a prior estimate of their cardiovascular risk. This prior estimate of cardiovascular risk is derived from risk factor data that are routinely held in electronic medical records, with unknown blood pressure and cholesterol levels replaced by default values derived from national survey data. This paper analyses the test characteristics of using such a strategy for identification of high risk patients. Methods Prior estimates of Framingham cardiovascular risk were derived in a population obtained from the Health Survey for England 2003. Receiver operating characteristics curves were constructed for using a prior estimate of cardiovascular risk to identify patients at greater than 20% ten-year cardiovascular risk. This was compared to strategies using age, or diabetic and antihypertensive treatment status to identify high risk patients. Results The area under the curve for a prior estimate of cardiovascular risk calculated using minimum data (0.933, 95% CI: 0.925 to 0.941) is significantly greater than for a selection strategy based on age (0.892, 95% CI: 0.882 to 0.902), or diabetic and hypertensive status (0.608, 95% CI: 0.584 to 0.632). Conclusion Using routine data held on primary care databases it is possible to identify a population at high risk of cardiovascular disease. Information technology to help primary care prioritise patients for cardiovascular disease prevention may improve the efficiency of cardiovascular risk assessment.</p

Radiative Properties of the Stueckelberg Mechanism

We examine the mechanism for generating a mass for a U(1) vector field introduced by Stueckelberg. First, it is shown that renormalization of the vector mass is identical to the renormalization of the vector field on account of gauge invariance. We then consider how the vector mass affects the effective potential in scalar quantum electrodynamics at one-loop order. The possibility of extending this mechanism to couple, in a gauge invariant way, a charged vector field to the photon is discussed.Comment: 8 pages, new Introduction, added Reference

Statistical Properties of Avalanches in Networks

We characterize the distributions of size and duration of avalanches propagating in complex networks. By an avalanche we mean the sequence of events initiated by the externally stimulated `excitation' of a network node, which may, with some probability, then stimulate subsequent firings of the nodes to which it is connected, resulting in a cascade of firings. This type of process is relevant to a wide variety of situations, including neuroscience, cascading failures on electrical power grids, and epidemology. We find that the statistics of avalanches can be characterized in terms of the largest eigenvalue and corresponding eigenvector of an appropriate adjacency matrix which encodes the structure of the network. By using mean-field analyses, previous studies of avalanches in networks have not considered the effect of network structure on the distribution of size and duration of avalanches. Our results apply to individual networks (rather than network ensembles) and provide expressions for the distributions of size and duration of avalanches starting at particular nodes in the network. These findings might find application in the analysis of branching processes in networks, such as cascading power grid failures and critical brain dynamics. In particular, our results show that some experimental signatures of critical brain dynamics (i.e., power-law distributions of size and duration of neuronal avalanches), are robust to complex underlying network topologies.Comment: 11 pages, 7 figure

Estimates on Green functions of second order differential operators with singular coefficients

We investigate the Green functions G(x,x^{\prime}) of some second order differential operators on R^{d+1} with singular coefficients depending only on one coordinate x_{0}. We express the Green functions by means of the Brownian motion. Applying probabilistic methods we prove that when x=(0,{\bf x}) and x^{\prime}=(0,{\bf x}^{\prime}) (here x_{0}=0) lie on the singular hyperplanes then G(0,{\bf x};0,{\bf x}^{\prime}) is more regular than the Green function of operators with regular coefficients.Comment: 16 page

A Linked Data Approach to Sharing Workflows and Workflow Results

A bioinformatics analysis pipeline is often highly elaborate, due to the inherent complexity of biological systems and the variety and size of datasets. A digital equivalent of the ‘Materials and Methods’ section in wet laboratory publications would be highly beneficial to bioinformatics, for evaluating evidence and examining data across related experiments, while introducing the potential to find associated resources and integrate them as data and services. We present initial steps towards preserving bioinformatics ‘materials and methods’ by exploiting the workflow paradigm for capturing the design of a data analysis pipeline, and RDF to link the workflow, its component services, run-time provenance, and a personalized biological interpretation of the results. An example shows the reproduction of the unique graph of an analysis procedure, its results, provenance, and personal interpretation of a text mining experiment. It links data from Taverna, myExperiment.org, BioCatalogue.org, and ConceptWiki.org. The approach is relatively ‘light-weight’ and unobtrusive to bioinformatics users

Discovery of a Second Millisecond Accreting Pulsar: XTE J1751-305

We report the discovery by the RXTE PCA of a second transient accreting millisecond pulsar, XTE J1751-305, during regular monitoring observations of the galactic bulge region. The pulsar has a spin frequency of 435 Hz, making it one of the fastest pulsars. The pulsations contain the signature of orbital Doppler modulation, which implies an orbital period of 42 minutes, the shortest orbital period of any known radio or X-ray millisecond pulsar. The mass function, f_x = (1.278 +/- 0.003) x 10^{-6} M_sun, yields a minimum mass for the companion of between 0.013 and 0.017 M_sun, depending on the mass of the neutron star. No eclipses were detected. A previous X-ray outburst in June, 1998, was discovered in archival All-Sky Monitor data. Assuming mass transfer in this binary system is driven by gravitational radiation, we constrain the orbital inclination to be in the range 30-85 deg, and the companion mass to be 0.013-0.035 M_sun. The companion is most likely a heated helium dwarf. We also present results from the Chandra HRC-S observations which provide the best known position of XTE J1751-305.Comment: Astrophysical Journal Letters, Accepted, (AASTeX

A Role for the Kolliker-Fuse Nucleus in Cholinergic Modulation of Breathing at Night During Wakefulness and NREM Sleep

For many years, acetylcholine has been known to contribute to the control of breathing and sleep. To probe further the contributions of cholinergic rostral pontine systems in control of breathing, we designed this study to test the hypothesis that microdialysis (MD) of the muscarinic receptor antagonist atropine into the pontine respiratory group (PRG) would decrease breathing more in animals while awake than while in NREM sleep. In 16 goats, cannulas were bilaterally implanted into rostral pontine tegmental nuclei (n = 3), the lateral (n = 3) or medial (n = 4) parabrachial nuclei, or the Kölliker-Fuse nucleus (KFN; n = 6). After \u3e2 wk of recovery from surgery, the goats were studied during a 45-min period of MD with mock cerebrospinal fluid (mCSF), followed by at least 30 min of recovery and a second 45-min period of MD with atropine. Unilateral and bilateral MD studies were completed during the day and at night. MD of atropine into the KFN at night decreased pulmonary ventilation and breathing frequency and increased inspiratory and expiratory time by 12–14% during both wakefulness and NREM sleep. However, during daytime studies, MD of atropine into the KFN had no effect on these variables. Unilateral and bilateral nighttime MD of atropine into the KFN increased levels of NREM sleep by 63 and 365%, respectively. MD during the day or at night into the other three pontine sites had minimal effects on any variable studied. Finally, compared with MD of mCSF, bilateral MD of atropine decreased levels of acetylcholine and choline in the effluent dialysis fluid. Our data support the concept that the KFN is a significant contributor to cholinergically modulated control of breathing and sleep

Andreev Probe of Persistent Current States in Superconducting Quantum Circuits

Using the extraordinary sensitivity of Andreev interferometers to the superconducting phase difference associated with currents, we measure the persistent current quantum states in superconducting loops interrupted by Josephson junctions. Straightforward electrical resistance measurements of the interferometers give continuous read-out of the states, allowing us to construct the energy spectrum of the quantum circuit. The probe is estimated to be more precise and faster than previous methods, and can measure the local phase difference in a wide range of superconducting circuits.Comment: Changes made in light of referees comments; to appear in PR

Performance, Politics and Media: How the 2010 British General Election leadership debates generated ‘talk’ amongst the electorate.

During the British General Election 2010 a major innovation was introduced in part to improve engagement: a series of three live televised leadership debates took place where the leader of each of the three main parties, Labour, Liberal Democrat and Conservative, answered questions posed by members of the public and subsequently debated issues pertinent to the questions. In this study we consider these potentially ground breaking debates as the kind of event that was likely to generate discussion. We investigate various aspects of the ‘talk’ that emerged as a result of watching the debates. As an exploratory study concerned with situated accounts of the participants experiences we take an interpretive perspective. In this paper we outline the meta-narratives (of talk) associated with the viewing of the leadership debates that were identified, concluding our analysis by suggesting that putting a live debate on television and promoting and positioning it as a major innovation is likely to mean that is how the audience will make sense of it – as a media event

Influence of bottom topography on integral constraints in zonal flows with parameterized potential vorticity fluxes

An integral constraint for eddy fluxes of potential vorticity (PV), corresponding to global momentum conservation, is applied to two-layer zonal quasi-geostrophic channel flow. This constraint must be satisfied for any type of parameterization of eddy PV fluxes. Bottom topography strongly influence the integral constraint compared to a flat bottom channel. An analytical solution for the mean flow solution has been found by using asymptotic expansion in a small parameter which is the ratio of the Rossby radius to the meridional extent of the channel. Applying the integral constraint to this solution, one can find restrictions for eddy PV transfer coefficients which relate the eddy fluxes of PV to the mean flow. These restrictions strongly deviate from restrictions for the channel with flat bottom topography