Risk, precaution and science: towards a more constructive policy debate. Talking point on the precautionary principle

Few issues in contemporary risk policy are as momentous or contentious as the precautionary principle. Since it first emerged in German environmental policy, it has been championed by environmentalists and consumer protection groups, and resisted by the industries they oppose (Raffensperger & Tickner, 1999). Various versions of the principle now proliferate across different national and international jurisdictions and policy areas (Fisher, 2002). From a guiding theme in European Commission (EC) environmental policy, it has become a general principle of EC law (CEC, 2000; Vos & Wendler, 2006). Its influence has extended from the regulation of environmental, technological and health risks to the wider governance of science, innovation and trade (O'Riordan & Cameron, 1994)

The point of maximum curvature as a marker for physiological time series

We present a geometric analysis of the model of Stirling. In particular we analyze the curvature of a heart rate time series in response to a step like increment in the exercise intensity. We present solutions for the point of maximum curvature which can be used as a marker of physiological interest. This marker defines the point after which the heart rate no longer continues to rapidly rise and instead follows either a steady state or slow rise. These methods are then applied to find analytic solutions for a mono exponential model which is commonly used in the literature to model the response to a moderate exercise intensity. Numerical solutions are then found for the full model and parameter values presented in Stirling

Anomalous quartic WWgamma gamma, ZZgamma gamma, and trilinear WWgamma couplings in two-photon processes at high luminosity at the LHC

We study the W/Z pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and W/Z bosons for an integrated luminosity of 30 and 200 fb^{-1}. For simplicity and to obtain lower backgrounds, only the leptonic decays of the electroweak bosons are considered.Comment: 22 pages, 17 figures, sumitted to Phys. Rev.

The inner radio jet region and the complex environment of SS433

We present multi-frequency VLBA+VLA observations of SS433 at 1.6, 5 and 15 GHz. These observations provide the highest angular resolution radio spectral index maps ever made for this object. Motion of the components of SS433 during the observation is detected. In addition to the usual VLBI jet structure, we detect two radio components in the system at an anomalous position angle. These newly discovered radio emitting regions might be related to a wind-like equatorial outflow or to an extension of the accretion disk. We show that the radio core component is bifurcated with a clear gap between the eastern and western wings of emission. Modelfitting of the precessing jets and the moving knots of SS433 shows that the kinematic centre -- i.e. the binary -- is in the gap between the western and eastern radio core components. Spectral properties and observed core position shifts suggest that we see a combined effect of synchrotron self-absorption and external free-free absorption in the innermost AU-scale region of the source. The spatial distribution of the ionized matter is probably not spherically symmetric around the binary, but could be disk-like.Comment: Accepted for publication by Astronomy and Astrophysic

Epistemic decision theory applied to multiple-target tracking

A decision philosophy that seeks the avoidance of error by trading off belief of truth and value of information is applied to the problem of recognizing tracks from multiple targets (MTT). A successful MTT methodology should be robust in that its performance degrades gracefully as the conditions of the collection become less favorable to optimal operation. By stressing the avoidance, rather than the explicit minimization, of error, the authors obtain a decision rule for trajectory-data association that does not require the resolution of all conflicting hypotheses when the database does not contain sufficient information to do so reliably. This rule, coupled with a set-valued Kalman filter for trajectory estimation, results in a methodology that does not attempt to extract more information from the database than it contains

A transient relativistic radio jet from Cygnus X-1

We report the first observation of a transient relativistic jet from the canonical black hole candidate, Cygnus X-1, obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN). The jet was observed in only one of six epochs of MERLIN imaging of the source during a phase of repeated X-ray spectral transitions in 2004 Jan--Feb, and this epoch corresponded to the softest 1.5-12 keV X-ray spectrum. With only a single epoch revealing the jet, we cannot formally constrain its velocity. Nevertheless, several lines of reasoning suggest that the jet was probably launched 0.5-4.0 days before this brightening, corresponding to projected velocities of 0.2c < v_app < 1.6c, and an intrinsic velocity of > 0.3c. We also report the occurrence of a major radio flare from Cyg X-1, reaching a flux density of ~120 mJy at 15 GHz, and yet not associated with any resolvable radio emission, despite a concerted effort with MERLIN. We discuss the resolved jet in terms of the recently proposed 'unified model' for the disc-jet coupling in black hole X-ray binaries, and tentatively identify the 'jet line' for Cyg X-1. The source is consistent with the model in the sense that a steady jet appears to persist initially when the X-ray spectrum starts softening, and that once the spectral softening is complete the core radio emission is suppressed and transient ejecta / shock observed. However, there are some anomalies, and Cyg X-1 clearly does not behave like a normal black hole transient in progressing to the canonical soft / thermal state once the ejection event has happened.Comment: Accepted for publication in MNRA

What Can the Accretion Induced Collapse of White Dwarfs Really Explain?

The accretion induced collapse (AIC) of a white dwarf into a neutron star has been invoked to explain gamma-ray bursts, Type Ia supernovae, and a number of problematic neutron star populations and specific binary systems. The ejecta from this collapse has also been claimed as a source of r-process nucleosynthesis. So far, most AIC studies have focussed on determining the event rates from binary evolution models and less attention has been directed toward understanding the collapse itself. However, the collapse of a white dwarf into a neutron star is followed by the ejection of rare neutron-rich isotopes. The observed abundance of these chemical elements may set a more reliable limit on the rate at which AICs have taken place over the history of the galaxy. In this paper, we present a thorough study of the collapse of a massive white dwarf in 1- and 2-dimensions and determine the amount and composition of the ejected material. We discuss the importance of the input physics (equation of state, neutrino transport, rotation) in determining these quantities. These simulations affirm that AICs are too baryon rich to produce gamm-ray bursts and do not eject enough nickel to explain Type Ia supernovae (with the possible exception of a small subclass of extremely low-luminosity Type Ias). Although nucleosynthesis constraints limit the number of neutron stars formed via AICs to <0.1% of the total galactic neutron star population, AICs remain a viable scenario for forming systems of neutron stars which are difficult to explain with Type II core-collapse supernovae.Comment: Latex File, aaspp4 style, 18 pages total (5 figures), accepted by Ap