Joanne C. Demmler

Age trends in tree ring growth and isotopic archives: A case study of Pinus sylvestris L. from northwestern Norway

Measurements of tree ring width and relative density have contributed significantly to many of the large-scale reconstructions of past climatic change, but to extract the climate signal it is first ...

Changes in atmospheric circulation and the Arctic Oscillation preserved within a millennial length reconstruction of summer cloud cover from northern Fennoscandia

Cloud cover currently represents the single greatest source of uncertainty in General Circulation Models. Stable carbon isotope ratios (δ13C) from tree-rings, in areas of low moisture stress, are likely to be primarily controlled by photosynthetically active radiation (PAR), and therefore should provide a proxy record for cloud cover or sunshine; indeed this association has previously been demonstrated experimentally for Scots pine in Fennoscandia, with sunlight explaining ca 90% of the variance in photosynthesis and temperature only ca 4%. We present a statistically verifiable 1011-year reconstruction of cloud cover from a well replicated, annually-resolved δ13C record from Forfjord in coastal northwestern Norway. This reconstruction exhibits considerable variability in cloud cover over the past millennium, including extended sunny periods during the cool seventeenth and eighteenth centuries and warm cloudy periods during the eleventh, early fifteenth and twentieth centuries. We find that while a generally positive relationship persists between sunshine and temperature at high-frequency, at lower (multi-decadal) frequencies the relationship is more often a negative one, with cool periods being sunny (most notably the Little Ice Age period from 1600 to 1750 CE) and warm periods more cloudy (e.g. the mediaeval and the twentieth century). We conclude that these long-term changes may be caused by changes in the dominant circulation mode, likely to be associated with the Arctic Oscillation. There is also strong circumstantial evidence that prolonged periods of high summer cloud cover, with low PAR and probably high precipitation, may be in part responsible for major European famines caused by crop failures.

Gestational Age, Birth Weight, and Risk of Respiratory Hospital Admission in Childhood

OBJECTIVE: To investigate the risk of emergency respiratory hospital admission during childhood associated with gestational age at birth and growth restriction in utero. METHODS: The study included a total population electronic birth cohort with anonymized record-linkage of multiple health and administrative data sets. Participants were 318 613 children born in Wales, United Kingdom, between May 1, 1998, and December 31, 2008. The main outcome measure was emergency respiratory hospital admissions. RESULTS: The rate of admission in the first year of life ranged from 41.5 per 100 child-years for infants born before 33 weeks’ gestation to 9.8 per 100 child-years for infants born at 40 to 42 weeks’ gestation. The risk of any emergency respiratory admission up to age 5 years increased as gestational age decreased to <40 weeks. Even at 39 weeks’ gestation, there was an increased risk of emergency hospital admissions for respiratory conditions compared with infants born at 40 to 42 weeks (adjusted hazard ratio 1.10; 95% confidence interval 1.08–1.13). Small for gestational age (<10th centile for gestation and gender-specific birth weight) was independently associated with an increased risk of any emergency respiratory admission to hospital (adjusted hazard ratio 1.07; 95% confidence interval 1.04–1.10). CONCLUSIONS: The risk of emergency respiratory admission up to age 5 years decreased with each successive week in gestation up to 40 to 42 weeks. Although the magnitude of increased risk associated with moderate and late preterm births is small, the number of infants affected is large and therefore presents a significant impact on health care services.

Protecting health data privacy while using residence-based environment and demographic data.

Spatial analyses of environment and health data are often made using point address data, despite the risk of identity disclosure. We describe how geospatial environment and non-spatial health data can be linked anonymously, thereby maintaining geoprivacy. High resolution environment data and population density were calculated specific to each residence. Population density and environment data were anonymously linked to individual-level demographic data using a split file method and residential anonymous linking fields. Access to the nearest park or playground was calculated for each residence; children in deprived areas have increased access compared to those in affluent areas. This method has the potential to be used to evaluate natural experiments and complex environmental health interventions.

Oxygen stable isotope ratios from British oak tree-rings provide a strong and consistent record of past changes in summer rainfall

AbstractUnited Kingdom (UK) summers dominated by anti-cyclonic circulation patterns are characterised by clear skies, warm temperatures, low precipitation totals, low air humidity and more enriched oxygen isotope ratios (δ18O) in precipitation. Such conditions usually result in relatively more positive (enriched) oxygen isotope ratios in tree leaf sugars and ultimately in the tree-ring cellulose formed in that year, the converse being true in cooler, wet summers dominated by westerly air flow and cyclonic conditions. There should therefore be a strong link between tree-ring δ18O and the amount of summer precipitation. Stable oxygen isotope ratios from the latewood cellulose of 40 oak trees sampled at eight locations across Great Britain produce a mean δ18O chronology that correlates strongly and significantly with summer indices of total shear vorticity, surface air pressure, and the amount of summer precipitation across the England and Wales region of the United Kingdom. The isotope-based rainfall signal is stronger and much more stable over time than reconstructions based upon oak ring widths. Using recently developed methods that are precise, efficient and highly cost-effective it is possible to measure both carbon (δ13C) and oxygen (δ18O) isotope ratios simultaneously from the same tree-ring cellulose. In our study region, these two measurements from multiple trees can be used to reconstruct summer temperature (δ13C) and summer precipitation (δ18O) with sufficient independence to allow the evolution of these climate parameters to be reconstructed with high levels of confidence. The existence of long, well-replicated oak tree-ring chronologies across the British Isles mean that it should now be possible to reconstruct both summer temperature and precipitation over many centuries and potentially millennia.

Do Children Who Move Home and School Frequently Have Poorer Educational Outcomes in Their Early Years at School? An Anonymised Cohort Study

Frequent mobility has been linked to poorer educational attainment. We investigated the association between moving home and moving school frequently and the early childhood formal educational achievement. We carried out a cohort analysis of 121,422 children with anonymised linked records. Our exposure measures were: 1) the number of residential moves registered with a health care provider, and 2) number of school moves. Our outcome was the formal educational assessment at age 6–7. Binary regression modeling was used to examine residential moves within the three time periods: 0 – <1 year; 1 – <4 years and 4 – <6 years. School moves were examined from age 4 to age 6. We adjusted for demographics, residential moves at different times, school moves and birth related variables. Children who moved home frequently were more likely not to achieve in formal assessments compared with children not moving. Adjusted odds ratios were significant for 3 or more moves within the time period 1 –<4 years and for any number of residential moves within the time period 4–<6 years. There was a dose response relationship, with increased odds ratios with increased frequency of residential moves (2 or more moves at 4–<6 years, adjusted odds ratio 1.16 (1.03, 1.29). The most marked effect was seen with frequent school moves where 2 or more moves resulted in an adjusted odds ratio of 2.33 (1.82, 2.98). This is the first study to examine the relationship between residential and school moves in early childhood and the effect on educational attainment. Children experiencing frequent mobility may be disadvantaged and should be closely monitored. Additional educational support services should be afforded to children, particularly those who frequently change school, in order to help them achieve the expected educational standards.

Epilepsy and deprivation, a data linkage study

To investigate whether the link between epilepsy and deprivation is due to factors associated with deprivation (social causation) or factors associated with a diagnosis of epilepsy (social drift).

The association between hospitalisation for childhood head injury and academic performance: evidence from a population e-cohort study

Background Childhood head injury has the potential for lifelong disability and burden. This study aimed to establish the association between admission to hospital for childhood head injury and early academic performance. Methods The Wales Electronic Cohort for Children (WECC) study is comprised of record-linked routinely collected data, on all children born or residing in Wales. Anonymous linking fields are used to link child and maternal health, environment and education records. Data from WECC were extracted for children born between September 1998 and August 2001. A Generalised Estimating Equation model, adjusted for clustering based on the maternal identifier as well as other key confounders, was used to establish the association between childhood head injury and performance on the Key Stage 1 (KS1) National Curriculum assessment administered to children aged 5–7 years. Head injury was defined as an emergency admission for >24 h for concussion, skull fracture or intracranial injury prior to KS1 assessment. Results Of the 101 892 eligible children, KS1 results were available for 90 661 (89%), and 290 had sustained a head injury. Children who sustained an intracranial injury demonstrated significantly lower adjusted odds of achieving a satisfactory KS1 result than children who had not been admitted to hospital for head injury (adjusted OR 0.46, 95% CI 0.30 to 0.72). Conclusions The findings of this population e-cohort study quantify the impact of head injury on academic performance, highlighting the need for enhanced head injury prevention strategies. The results have implications for the care and rehabilitation of children admitted to hospital with head injury.

Development and use of a privacy-protecting total population record linkage system to support observational, interventional, and policy relevant research

Abstract Background The 2006 Cooksey review of UK health research identified the NHS cradle-to-grave records of the 60 million UK residents as having the greatest potential to reinvigorate the UK research environment. Subsequently, national and regional e-health research units were set up across the UK, including in Wales, the Secure Anonymised Information Linkage (SAIL) system. We aim to draw attention to the uses, findings, and research potential of the SAIL system. Methods The SAIL system is a suite of privacy-protecting technologies, including multistage encryption in which unique anonymised numbers replace individual, household, and organisational identities (appendix). There is strong input from patient and public representatives and an independent panel that scrutinised proposals. Many different health, educational attainment, and housing datasets are included in SAIL, which now supports various research designs including pure population-based electronic cohorts, traditional cohorts, embedded individual and cluster randomised trials, and assessments of natural experiments. Examples from more than 50 studies supported so far include the Wales Electronic Cohort for Children (WECC), NIHR-funded evaluations of natural experiments (housing improvement and changes in alcohol outlet density), cluster randomised trials of prehospital care, and an assessment of the Welsh Government Flying Start childhood initiative. We will focus on some of the results from WECC. Findings WECC contains anonymised records of the 804 290 children living in Wales between 1990 and 2008 compiled from nine datasets (linkage rate >97% for three population registers: births, NHS registrations, and community child dataset). 590 042 children were born in Wales, and electronic education records were available for 122 817 born after 1994. This analysis will focus on the effect of pregnancy, birth, and childhood factors on health status and educational attainment to key stage 1 (age 7 years). For example, very low birthweight (hazard ratio [HR] 2·4, 95% CI 1·9–2·9), prematurity (3·07, 2·76–3·41, for Interpretation The SAIL system provides a research efficient e-cohort platform on which it is possible to embed intervention trials and assess the effect of natural experiments and multisectoral policy initiatives on health, educational, and other population outcomes. Funding The Health Information Research Unit at Swansea University receives funding for operation of SAIL from the National Institute of Social Care and Health Research. Two multifinder initiatives, DECIPHer and CIPHER, contributed to studies included in the abstract. Additional funders were Arthritis Research UK, the British Heart Foundation, Cancer Research UK, the Chief Scientist Office (Scottish Government), the Economic and Social Research Council, the Engineering and Physical Sciences Research Council, the Medical Research Council, NIHR, and the Wellcome Trust.

SVM with entropy regularization and particle swarm optimization for identifying children's health and socioeconomic determinants of education attainments using linked datasets

Linking large disparate database systems at individual person based level for medical informatics and e-health research is a challenging task. In the interests of identifying influential determinants of effects of childrens health and socioeconomic status on educational attainment, this paper links child health data records including birth records, school key stage attainment records, deprivation index scores etc. from multiple sources via an e-health infrastructure SAIL databank. Furthermore, a novel scheme of automatically identifying influential attributes from high dimensional data is presented. The proposed scheme applies the entropy regularisation and particle swarm optimisation (PSO) techniques to the construction of an optimal support vector machine (SVM) model. The novelty of the proposed scheme lies in that during learning process the importance of less influential attributes automatically approaches to zero, whilst the importance of the most important attributes turns to one, so that only the most influential attributes turn up in the final SVM model. Whats more, the model selection, feature identification and dimensionality reduction are performed simultaneously in an integrated manner in one model structure. The experimental results have shown that the proposed method is efficient in performing dimensionality reduction and identifying the important determinants of the effects of childrens health and socioeconomic status on educational attainment.