Selective migration from deprived areas in Northern Ireland and the spatial distribution of inequalities: implications for monitoring health and inequalities in health

Much of the evidence suggesting that inequalities in health have been increasing over the last two decades has come from studies that compared the changes in relative health status of areas over time. Such studies ignore the movement of people between areas. This paper examines the population movement between small areas in Northern Ireland in the year prior to the 1991 census as well as the geographical distribution of migrants to Northern Ireland over the same period. It shows that deprived areas tended to become depopulated and that those who left these areas were the more affluent residents. While immigrants differed a little from the indigenous population, the overall effect of their distribution would be to maintain the geographical socio-economic status quo. The selective movement of people between areas would result in the distribution of health and ill-health becoming more polarized, i.e. produce a picture of widening inequalities between areas even though the distribution between individuals is unchanged. These processes suggest potential significant problems with the area-based approaches to monitoring health and inequalities in health.

The effects of dispersal mode on the spatial distribution patterns of intertidal molluscs.

1. As many species of marine benthic invertebrates have a limited capacity for movement as adults, dispersal mode is often considered as a determinant of geographical ranges, genetic structure and evolutionary history. Species that reproduce without a larval stage can only disperse by floating or rafting. It is proposed that the colonization processes associated with such direct developing species result in spatial distributions that show relatively greater fine scale patchiness than the distributions of species with a larval dispersal stage. This hypothesis was tested by collecting molluscs at different spatial scales in the Isle of Man. 2. Spatial distribution patterns supported the predictions based on dispersal mode. Estimated variance components for species with larval dispersal suggested that the majority of the spatial variation was associated with variation between shores. In comparison, there was relatively more variability within shores for abundance counts of species with direct development. 3. Multivariate analyses reflected the univariate results. An assemblage of direct developers provided a better discrimination between sites (100 m separation) but the group of species with larval dispersal gave a clearer separation of shores (separated by several km). 4. The fine scale spatial structure of direct developing species was reflected in higher average species diversity within quadrats. Species richness also reflected dispersal mode, with a higher fraction of the regional species pool present for direct developers in comparison to species with larval dispersal. This may reflect the improved local persistence of taxa that avoid the larval dispersal stage.

Using choice experiments to explore the spatial distribution of willingness to pay for rural landscape improvements

We report findings from a choice experiment survey designed to estimate the economic benefits of policy measures to improve the rural landscape in the Republic of Ireland. Using a panel mixed logit specification to account for unobserved taste heterogeneity we derived individual-specific willingness-to-pay (WTP) estimates for each respondent in the sample. We subsequently investigated the spatial dependence of these estimates. Results suggest the existence of positive spatial autocorrelation for all rural landscape attributes. As a means of benefit transfer, kriging methods were employed to interpolate WTP estimates across the whole of the Republic of Ireland. The kriged WTP surfaces confirm the existence of spatial dependence and illustrate the implied spatial variation and regional disparities in WTP for all the rural landscape improvements investigated.

The spatial distribution of Holocene cryptotephras in north-west Europe since 7 ka: implications for understanding ash fall events from Icelandic eruptions

We present distribution maps for all cryptotephras (distal volcanic ash layers) younger than 7 ka that have been reported from three or more lakes or peatlands in north-west Europe. All but one of the tephras originates from Iceland; the exception has been attributed to Jan Mayen. We find strong spatial patterning in tephra occurrence at the landscape scale; most, but not all of the tephra occurrences are significantly spatially clustered, which likely reflects atmospheric and weather patterns at the time of the eruptions. Contrary to expectations based on atmospheric modelling studies, tephras appear to be at least as abundant in Ireland and northern Scotland as in Scandinavia. Rhyolitic and other felsic tephras occur in lakes and peatlands throughout the study region, but andesitic and basaltic tephras are largely restricted to lake sites in the Faroe Islands and Ireland. Explanations of some of these patterns will require further research on the effects of different methodologies for locating and characterizing cryptotephras. These new maps will help to guide future investigations in tephrochronology and volcanic hazard analysis.

Heritability of the spatial distribution and peak density of macular pigment:a classical twin study

Purpose: To elucidate the heritability of peak density and spatial width of macular pigment (MP) using a Classical Twin Study.

Methods: Fundus autofluorescence images were obtained at 488?nm from 86 subjects or 43 twin pairs (21 monozygotic (MZ) and 22 dizygotic (DZ)) (27 male, 59 female) aged from 55 to 76 years (mean 62.2±5.3 years). The relative topographic distribution of MP was measured using a grey scale of intensity (0-255 units) in a 7° eccentricity around the fovea. Relative peak MP density (rPMPD) and relative spatial distribution of MP (rSDMP) were used as the main outcome measure in the statistical analysis.

Results: A significantly higher correlation was found within MZ pairs as compared with that within DZ pairs for rPMPD, (r=0.99, 95% confidence interval (95% CI) 0.93 to 1.00) and 0.22, 95% CI -0.34 to 0.71), respectively, suggesting strong heritability of this trait. When rSDMP was compared, there was no significant difference between the correlations within MZ pairs (r=0.48, 95% CI -0.02 to 0.83) and DZ pairs (r=0.63, 95% CI 0.32 to 0.83), thus rSDMP is unlikely to have a considerable heritable component. In addition, there was no difference between any MP parameter when normal maculae were compared with early age-related macular degeneration (AMD) (rPMPD 0.36 vs 0.34, t=1.18 P=0.243, rSDMP 1.75 vs 1.75, t=0.028 P=0.977).ConclusionsrPMPD is a strongly heritable trait whereas rSDMP has minimal genetic influence and a greater influence by environmental factors. The presence of macular changes associated with early AMD did not appear to influence any of these pigment parameters. © 2012 Macmillan Publishers Limited All rights reserved 0950-222X/12

Spatial distribution of arsenic and temporal variation of its concentration in rice

P>In order to gain insights into the transport and distribution of arsenic (As) in intact rice (Oryza sativa) plants and its unloading into the rice grain, we investigated the spatial distribution of As and the temporal variation of As concentration in whole rice plants at different growth stages. To the best of our knowledge, this is the first time that such a study has been performed.

Inductively coupled plasma mass spectroscopy (ICP-MS) and high-performance liquid chromatography (HPLC)-ICP-MS were used to analyze total As concentration and speciation. Moreover, synchrotron-based X-ray fluorescence (SXRF) was used to investigate in situ As distribution in the leaf, internode, node and grain.

Total As concentrations of vegetative tissues increased during the 2 wk after flowering. The concentration of dimethylarsinic acid (DMA) in the caryopsis decreased progressively with its development, whereas inorganic As concentration remained stable. The ratios of As content between neighboring leaves or between neighboring internodes were c. 0.6. SXRF revealed As accumulation in the center of the caryopsis during its early development and then in the ovular vascular trace.

These results indicate that there are different controls on the unloading of inorganic As and DMA; the latter accumulated mainly in the caryopsis before flowering, whereas inorganic As was mainly transported into the caryopsis during grain filling. Moreover, nodes appeared to serve as a check-point in As distribution in rice shoots.

PREDICTING THE SPATIAL-DISTRIBUTION OF CLIMATE - TEMPERATURE IN GREAT-BRITAIN

1. The prediction and mapping of climate in areas between climate stations is of increasing importance in ecology.

2. Four categories of model, simple interpolation, thin plate splines, multiple linear regression and mixed spline-regression, were tested for their ability to predict the spatial distribution of temperature on the British mainland. The models were tested by external cross-verification.

3. The British distribution of mean daily temperature was predicted with the greatest accuracy by using a mixed model: a thin plate spline fitted to the surface of the country, after correction of the data by a selection from 16 independent topographical variables (such as altitude, distance from the sea, slope and topographic roughness), chosen by multiple regression from a digital terrain model (DTM) of the country.

4. The next most accurate method was a pure multiple regression model using the DTM. Both regression and thin plate spline models based on a few variables (latitude, longitude and altitude) only were comparatively unsatisfactory, but some rather simple methods of surface interpolation (such as bilinear interpolation after correction to sea level) gave moderately satisfactory results. Differences between the methods seemed to be dependent largely on their ability to model the effect of the sea on land temperatures.

5. Prediction of temperature by the best methods was greater than 95% accurate in all months of the year, as shown by the correlation between the predicted and actual values. The predicted temperatures were calculated at real altitudes, not subject to sea-level correction.

6. A minimum of just over 30 temperature recording stations would generate a satisfactory surface, provided the stations were well spaced.

7. Maps of mean daily temperature, using the best overall methods are provided; further important variables, such as continentality and length of growing season, were also mapped. Many of these are believed to be the first detailed representations at real altitude.

8. The interpolated monthly temperature surfaces are available on disk.

Spatial Distribution of Soil Geochemistry in Geoforensics

Two common scenarios in Geoforensics (definition in text) are considered: the provenance, or localization of unknown samples and the question of sample variability at scenes of crime/alibi locations. Both have been discussed in forensic and soil science publications, but mostly within a theoretical or non-forensic context. These previous publications provide context for the two case study scenarios (one actual, one based on a range of criminal casework) that consider provenance and variability. A challenging scientific question in geoforensics is the provenance question: ‘where may this sample have come from?’ A question the Tellus data can assist in answering. The question of variation between samples maybe less of a challenge, yet variation between a suspect sample within a scene of crime requires detailed sampling. Variation on a larger (tens to hundreds of kilometres) scale may provide useful intelligence on where a sample came from. To summarise, databases such as Tellus and TellusBorder may be used as effective tools to assist in the search for the origin of displaced soil and sediment