Health profiles of Hamilton: Spatial characterisation of neighbourhoods for health investigations     

Isaac Luginaah  Michael Jerrett  Susan Elliott  John Eyles  Kate Parizeau  Stephen Birch  Tom Abernathy  Gerry Veenstra  Brian Hutchinson  Chris Giovis 《GeoJournal》2001,53(2):135-147

This paper is part of a larger research program which employs a mixed-methods approach to study the determinants of health at the local level using specific neighborhoods in Hamilton, Ontario, Canada. In this paper, multivariate, spatial statistical techniques and geographic information systems are used to address questions about the characterization of neighbourhoods, based on socioeconomic determinants of health and risk factors such as smoking. While neighbourhood characterization has been a component of public health surveillance for some time, geostatistical techniques can now be used to derive more accurate representation of neighbourhoods for use in subsequent analysis. We utilize principal components analysis to reduce the data and extract the components that represent the underlying local processes. Principal components are also overlayed on comparative mortality figures to visualize where the socio-demographic determinants of health correspond spatially with mortality patterns. Predicted values from the components are then analysed for spatial clustering using local indicators of spatial association. The findings reveal a pattern of distinct neighbourhoods that will be used in subsequent quantitative and qualitative stages in the larger research programme. The results can also be used to inform public health policy and to target public health interventions.  相似文献   

Bone isotope ratios and their bearing on elite privilege among the Classic Maya     

John P. Gerry 《Geoarchaeology》1997,12(1):41-69

This article discusses dietary patterns among the Classic Maya as they are revealed by stable carbon and nitrogen isotope ratios preserved in human bone. Skeletal samples are drawn from seven sites: Uaxactun, Holmul, Baking Pot, Barton Ramie, Siebal, Altar de Sacrificios, and Copán. The isotopic results indicate that Maya nutrition was not so much socially dictated as it was spatially determined; i.e., neither class nor gender nor chronological context are significant factors of isotopic variation when compared to geographic location. These data specifically challenge the notion that Maya elites had quantitative dietary privileges; they do, however, allow for the existence of qualitative privileges. Micro-environmental factors might account for the regional groupings defined, but ultimately, settlement density is considered a more significant variable. © 1997 John Wiley & Sons, Inc.  相似文献   

Formation Flying for a Fresnel Lens Observatory Mission     

John Krizmanic  Gerry Skinner  Neil Gehrels 《Experimental Astronomy》2005,20(1-3):497-503

The employment of a large area Phase Fresnel Lens (PFL) in a gamma-ray telescope offers the potential to image astrophysical phenomena with micro-arcsecond (μ^′′) angular resolution [1]. In order to assess the feasibility of this concept, two detailed studies have been conducted of formation flying missions in which a Fresnel lens capable of focussing gamma-rays and the associated detector are carried on two spacecraft separated by up to 10⁶ km. These studies were performed at the NASA Goddard Space Flight Center Integrated Mission Design Center (IMDC) which developed spacecraft, orbital dynamics, and mission profiles. The results of the studies indicated that the missions are challenging but could be accomplished with technologies available currently or in the near term. The findings of the original studies have been updated taking account of recent advances in ion thruster propulsion technology.  相似文献   

On detecting terrestrial planets with timing of giant planet transits     

Eric Agol  Jason Steffen  Re'em Sari  Will Clarkson 《Monthly notices of the Royal Astronomical Society》2005,359(2):567-579

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Thermal response of Saturn's ring particles during and after eclipse     

Lucien Froidevaux  Keith Matthews  Gerry Neugebauer 《Icarus》1981,46(1):18-26

We present infrared (20 μm) observations of Saturn's rings for a solar elevation angle of 10° and phase angle of 6°. Scans across the rings yield information about the cooling of particles during eclipse and the subsequent heating along their orbits. All three rings exhibit significant cooling during eclipse, as well as a 20-μm brightness asymmetry between east and west ansae, the largest asymmetry occuring in the C ring (the brightest ring). The eclipse cooling is a simple and adequate explanation for 20-μm brightness asymmetries between the ansae of Saturn's rings. The relatively large C ring asymmetry is thought to be primarily due to the short travel time of the particles in that ring from eclipse exit to east ansa. We compare the B ring data to the theoretical models of H.H. Aumann and H.H. Kieffer (1973, Astrophys. J.186, 305–311) in order to set constraints on the average particle size and thermal inertia. The rather rapid heating after exit from eclipse points to low-conductivity-particle surfaces, similar to the water frost surfaces of Galilean satellites. If the surface conductivity is indeed low, one cannot determine an upper limit for the particle size through such infrared observations, since only the uppermost millimeters experience a thermal response during eclipse. However, based on these infrared data alone, it is clear that particles of radius equal to a few millimeters or less cannot occupy a significant fraction of the ring surface area, because-regardless of thermal inertia-their thermal response is much faster than observed.  相似文献   

Ordovician faunas in mass-flow deposits, Southern Scotland     

Euan N.K. Clarkson  David A.T. Harper  Alan W. Owen  Cecilia M. Taylor 《地学学报》1992,4(2):245-253

In the Ordovician Northern Belt of the Southern Uplands, basal volcanics (Arenig) are followed by cherts (Llanvirn-?Llandeilo), then by graptolite shales (Llandelio-Lower Caradoc), and finally by Caradoc greywackes. Within the greywackes (Kirkcolm Formation) are a number of occurrences of fossiliferous conglomerate and overlying mudstone; these can be traced along-strike for some 30 km. The conglomerates, and especially the mudstones, yield rich mid- Caradoc shelly assemblages; brachiopods (20 spp.)/ trilobites (14 spp.), gastropods, bivalves, bryozoans, and the first known Palaeozoic scleractiniamorph coral. These occurrences are interpreted as mass-flow deposits derived by downslope movement from a now-vanished shelf to the North, and may belong either to a single gigantic debris flow event, or to a series of smaller, but roughly contemporaneous flows. Strong faunal similarities to faunas at Girvan (western Scotland), and Tyrone (Northern Ireland), lying North of the Southern Upland Fault may suggest sinistral strike-slip movement of no more than a few hundred kilometres.  相似文献   

A fast hybrid algorithm for exoplanetary transit searches     

A. Collier Cameron  D. Pollacco  R. A. Street  T. A. Lister  R. G. West  D. M. Wilson  F. Pont  D. J. Christian  W. I. Clarkson  B. Enoch  A. Evans  A. Fitzsimmons  C. A. Haswell  C. Hellier  S. T. Hodgkin  K. Horne  J. Irwin  S. R. Kane  F. P. Keenan  A. J. Norton  N. R. Parley  J. Osborne  R. Ryans  I. Skillen  P. J. Wheatley 《Monthly notices of the Royal Astronomical Society》2006,373(2):799-810

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Observational properties of accretion discs: Precessing and warped?     

Phil Charles  Will Clarkson  Remon Cornelisse  Chun Shih I 《New Astronomy Reviews》2008,51(10-12):768

Over the last 40 years, X-ray astronomy missions have revealed long-term, superorbital periods in a variety of X-ray binaries. These modulations can provide significant constraints on the physical properties of accretion discs. Some of these modulations are Her X-1-like and are interpreted as irradiation-driven, tilted, precessing accretion discs. Others show more complex light curves, with the period changing on timescales >1000 d, and are interpreted in terms of the Ogilvie and Dubus [Ogilvie, G.I., Dubus, G., 2001, MNRAS 320, 485 (OD01)] disc stability criteria. We suggest a categorisation of superorbital periods into six different types, based on their observed characteristics.  相似文献   

Determination of dead-time in photon counting photometers by a polarimetric method     

David Clarke  Gerry Deighan  Gillian Fry  Susan Goodsir  Donald Macleod 《Astrophysics and Space Science》1996,239(2):229-235

Experiments are described which demonstrate that the dead-time constant associated with a photon counting stellar photometer/polarimeter is readily determinable by the application of the Malus law. It is also proposed that corrections for dead-time losses should be applied by an iteration technique to the exact equation rather than using the available approximation formulae.  相似文献   

A pollution history of Chesapeake Bay     

Edward D. Goldberg  Vern Hodge  Minoru Koide  John Griffin  Eric Gamble  Owen P. Bricker  Gerry Matisoff  George R. Holdren  Ruth Braun 《Geochimica et cosmochimica acta》1978,42(9):1413-1425

Present day anthropogenic fluxes of some heavy metals to central Chesapeake Bay appear to be intermediate to those of the southern California coastal region and those of Narragansett Bay. The natural fluxes, however, are in general higher. On the bases of Pb-210 and Pu-239 + 240 geochronologies and of the time changes in interstitial water compositions, there is a mixing of the upper 30 or so centimeters of the sediments in the mid-Chesapeake Bay area through bioturbation by burrowing mollusks and polychaetes. Coal, coke and charcoal levels reach one percent or more by dry weight in the deposits, primarily as a consequence of coal mining operations.  相似文献