Coping with uncertainty in public health: the use of heuristics

The observation that experts and lay people use cognitive shortcuts or heuristics to arrive at judgements about complex problems is certainly not new. But what is new is the finding that a group of reasoning strategies, which have been maligned by philosophers and logicians alike, have demonstrable value in helping members of the public come to a judgement about public health problems. These problems, which span food safety crises, immunization scares and risks associated with exposure to environmental toxins, presuppose knowledge and expertise which falls outside of the epistemic and technical competence of most members of the public. Notwithstanding the complexity of these problems, they are not perceived by lay people to be wholly unintelligible or incomprehensible. This short communication reports on the findings of a questionnaire-based investigation into the use of these reasoning strategies by 879 members of the public. The results reveal a rational competence on the part of lay people which has been hitherto unexamined, and which may be usefully exploited in all aspects of public health work

Intergenerational equity and conservation

The issue of integenerational equity in the use of natural resources is discussed in the context of coal mining conversion. An attempt to determine if there is a clear-cut benefit to future generations in setting minimum coal extraction efficiency standards in mining is made. It is demonstrated that preserving fossil fuels beyond the economically efficient level is not necessarily beneficial to future generations even in terms of their own preferences. Setting fossil fuel conservation targets for intermediate products (i.e. energy) may increase the quantities of fossil fuels available to future generations and hence lower the costs, but there may be serious disadvantages to future generations as well. The use of relatively inexpensive fossil fuels in this generation may result in more infrastructure development and more knowledge production available to future generations. The value of fossil fuels versus these other endowments in the future depends on many factors which cannot possibly be evaluated at present. Since there is no idea of whether future generations are being helped or harmed, it is recommended that integenerational equity not be used as a factor in setting coal mine extraction efficiency standards, or in establishing requirements

Synergistic relationships among remote-sensing and geophysical media: Geological and hydrological applications

The synergistic relationships among LANDSAT imagery, Skylab photographs, and aerial photographs were useful for establishing areas of near surface bedrock. Lineaments were located on LANDSAT imagery and aerial photographs during 1978 and near surface water tables were to be located during 1980. Both of these subjects can be identified by remote sensing methods more reliably than individual outcrops, which are small and occur in a wide variety of environments with a wide range of responses. Bedrock outcrops themselves could not be resolved by any of the data sources used, nor did any combination of data sources specifically identify rock at the ground surface. The data sources could not simply be combined mathematically to produce a visual image of probable areas of near surface bedrock. Outcrops and near surface bedrock had to be verified visually at the site. Despite these drawbacks, a procedure for locating areas of near surface bedrock within which actual surface outcrops may occur was developed

Electromagnetic properties of ice coated surfaces

The electromagnetic scattering from ice coated structures is examined. The influence of ice is shown from a measurement standpoint and related to a simple analytical model. A hardware system for the realistic measurement of ice coated structures is also being developed to use in an existing NASA Lewis icing tunnel. Presently, initial measurements have been performed with a simulated tunnel to aid in the development

PCA of PCA: Principal Component Analysis of Partial Covering Absorption in NGC 1365

We analyse 400 ks of XMM-Newton data on the active galactic nucleus NGC 1365 using principal component analysis (PCA) to identify model independent spectral components. We find two significant components and demonstrate that they are qualitatively different from those found in MCG?6-30-15 using the same method. As the variability in NGC 1365 is known to be due to changes in the parameters of a partial covering neutral absorber, this shows that the same mechanism cannot be the driver of variability in MCG-6-30-15. By examining intervals where the spectrum shows relatively low absorption we separate the effects of intrinsic source variability, including signatures of relativistic reflection, from variations in the intervening absorption. We simulate the principal components produced by different physical variations, and show that PCA provides a clear distinction between absorption and reflection as the drivers of variability in AGN spectra. The simulations are shown to reproduce the PCA spectra of both NGC 1365 and MCG-6-30-15, and further demonstrate that the dominant cause of spectral variability in these two sources requires a qualitatively different mechanism.Comment: 8 pages, 10 figures. Accepted for publication in MNRA

The Ultra-Fast Outflow of WKK 4438: Suzaku and NuSTAR X-ray Spectral Analysis

Previous X-ray spectral analysis has revealed an increasing number of AGNs with high accretion rates where an outflow with a mildly relativistic velocity originates from the inner accretion disk. Here we report the detection of a new ultra-fast outflow (UFO) with a velocity of $v_{\rm out}=0.319^{+0.005}_{-0.008}c$ in addition to a relativistic disk reflection component in a poorly studied NLS1 WKK~4438, based on archival \nustar and \suzaku observations. The spectra of both \suzaku and \nustar observations show an Fe~\textsc{xxvi} absorption feature and the \suzaku data also show evidence for an Ar~\textsc{xviii} with the same blueshift. A super-solar argon abundance ($Z^{\prime}_{\rm Ar}>6Z_{\odot}$) and a slight iron over-abundance ($Z^{\prime}_{\rm Fe}=2.6^{+1.9}_{-2.0}Z_{\odot}$) are found in our spectral modelling. Based on Monte-Carlo simulations, the detection of the UFO is estimated to be around at 3$\sigma$ significance. The fast wind most likely arises from a radius of $\geq20r_g$ away from the central black hole. The disk is accreting at a high Eddington ratio ($L_{\rm bol}=0.4-0.7L_{\rm Edd}$). The mass outflow rate of the UFO is comparable with the disk mass inflow rate ($\dot M_{\rm out}>30\%\dot M_{\rm in}$), assuming a maximum covering factor. The kinetic power of the wind might not be high enough to have influence in AGN feedback ($\dot E_{\rm wind}/L_{\rm bol}\approx 3-5\%$) due to a relatively small column density ($12^{+9}_{-4}\times10^{22}$~cm$^{-2}$). However note that both the inferred velocity and the column density could be lower limits owing to the low viewing angle ($i=23^{+3}_{-2}$$^{\circ}$).Comment: 7 pages, 3 figures, accepted by MNRA