Commentary : controversies in NICE guidance on lipid modification for the prevention of cardiovascular disease

The new guidelines from the National Institute for Health and Clinical Excellence (NICE) on lipid modification for the prevention of cardiovascular disease will guide the way we assess cardiovascular risk and treat lipids, both in primary and in secondary care. What are the new aspects, and what is it that might spark controversy in this new publication

Salt and cardiovascular disease

Blood pressure is the most powerful predictor of stroke and other cardiovascular events. The importance of salt (sodium chloride) intake in determining blood pressure and the incidence of hypertension is well established. Furthermore, randomised controlled clinical trials of moderate reductions in salt intake show a dose dependent cause-effect relation and lack of a threshold effect within usual levels of salt intake in populations worldwide. The effect is independent of age, sex, ethnic origin, baseline blood pressure, and body mass. Prospective studies,2 3 4 5 with one exception,6 also indicate that higher salt intake predicts the incidence of cardiovascular events. While widespread support exists for reducing salt intake to prevent cardiovascular disease, the lack of large and long randomised trials on the effects of salt reduction on clinical outcomes has encouraged some people to argue against a policy of salt reduction in populations

Analysis of Autoguiding for Exoplanet Transit Research at the UNH Observatory

This paper will discuss the proper calibration technique for an autoguider of a CCD camera and the results that follow from successful exoplanet transit observations. A brief background on exoplanets, the transit method, and the analysis of their parent stars through photometry will be examined. The results will be presented in a before and after framework that will visually represent the data improvements from autoguiding as graphical Light Curves (LC). The addition of being able to autoguide at the UNH observatory will work towards providing future students with the possibility of performing follow-up ground-based observations and archiving their work online to aid the entire astronomy community

X-ray propagation through hollow channel: PolyCAD - a ray tracing code (1)

A new CAD program, PolyCAD, designed for X-ray photon tracing in polycapillary optics is described. To understand the PolyCAD code and its results, the theoretical basis of X-ray transmission by a single cylindrical channel (monocapillary) is discussed first. Then the simplest cases of cylindrically and conically shaped polycapillary optics are examined. PolyCAD allows any type of X-ray source to be used: an X-ray tube of finite beam dimensions or an astrophysical object can be simulated in combination with the polycapillary optics. The radiation distribution images formed on a screen located at various focal distances are discussed. The good agreement of some of the PolyCAD results with those reported in earlier papers validate the code. This is the first paper of a series dedicated to the development of an exhaustive CAD program, work is in progress to develop the code to include other polycapillary-optics shapes, such as semi-lenses and full-lenses.Comment: Submitted to Applied Optic

Safety and the flying doctor

Interest, curiosity, or dismay—which feeling predominates when we learn from BBC Newsnight that our NHS employs doctors who commute from Poland to cover the out of hours duties that local GPs are unable to work because they are too tired at night? Is it interest in an innovative solution for modern pan-European healthcare provision, curiosity in discovering huge variations in the standard of living across the medical profession in an open Europe, or dismay that the government’s emphasis, that healthcare practice should be based on the best scientific evidence, is little more than lip service? Working continuously for a long time, particularly at night, increases the risk of making errors and causing injury, which is why many professions limit the number of hours of continuous duty. These risks also apply to the medical profession: tired doctors make mistakes that harm patients (N Engl J Med 2004;351:1838-48) and themselve

Asymptotic null distributions of stationarity and nonstationarity

The purpose of this paper is to investigate the asymptotic null distribution of stationarity and nonstationarity tests when the distribution of the error term belongs to the normal domain of attraction of a stable law in any finite sample but the error term is an i.i.d. process with finite variance as T " 1. This local-to-finite variance setup is helpful to highlight the behavior of test statistics under the null hypothesis in the borderline or near borderline cases between finite and infinite variance and to assess the robustness of these test statistics to small departures from the standard finite variance context. From an empirical point of view, our analysis can be useful in settings where the (non)-existence of the (second) moments is not clear-cut, such as, for example, in the analysis of financial time series. A Monte Carlo simulation study is performed to improve our understanding of the practical implications of the limi theory we develop. The main purpose of the simulation experiment is to assess the size distortion of the unit root and stationarity tests under investigation.Stable distributions, unit root tests, stationarity tests, asymptotic distributions,local-to-finite variance, size distortion

The Fragility of the KPSS Stationarity Test

Stationarity tests exhibit extreme size distortions if the observable process is stationary yet highly persistent. In this paper we provide a theoretical explanation for the size distortion of the KPSS test for DGPs with a broad range of first order autocorrelation coefficient. Considering a near-integrated, nearly stationary process we show that the asymptotic distribution of the test contains an additional term, which can potentially explain the amount of size distortion documented in previous simulation studies.KPSS stationarity test, size distortion, nearly white noise nearly integrated model

The power of unit root tests under local-to-finite variance errors

We study the power of four popular unit root tests in the presence of a local-to-finite variance DGP. We characterize the asymptotic distribution of these tests under a sequence of local alternatives, considering both stationary and explosive ones . We supplement the theoretical analysis with a small simulation study to assess the finite sample power of the tests. Our results suggest that the finite sample power is affected by the $alpha$-stable component for low values of $alpha$ and that, in the presence of this component, the DW test has the highest power under stationary alternatives. We also document a strange behavior of the $DW$ test which, under the explosive alternative, suddenly falls from 1 to zero for very small changes in the autoregressive parameter suggesting a discontinuity in the power function of the $DW$ test

Pointing as an Instrumental Gesture : Gaze Representation Through Indication

The research of the first author was supported by a Fulbright Visiting Scholar Fellowship and developed in 2012 during a period of research visit at the University of Memphis.Peer reviewedPublisher PD