Pre-pregnancy obesity, pre-existing diabetes, and the risks of serious adverse fetal outcomes

PhD ThesisThe epidemics of obesity and diabetes are two of the leading threats to health in the 21st century. Maternal obesity complicates a large and increasing minority of pregnancies, and pre-existing diabetes is one of the most common maternal chronic health complications of pregnancy. This Doctoral Statement presents a portfolio of six published articles that draw on the North of England’s long-standing population-based registries of maternal and perinatal health to investigate the effects of pre-pregnancy obesity and diabetes on a range of serious adverse pregnancy outcomes. The first two articles examined a cohort of pregnant women who delivered in five of the region’s hospitals during 2003-2005 to explore the associations between maternal body mass index and the risks of, 1) congenital anomaly and 2) fetal and infant death. The next three examined a cohort of pregnant women with pre-existing diabetes who delivered during 1996-2008 to explore the effects of the condition on, 1) congenital anomaly, 2) birth weight, and 3) fetal and infant death. The final article examined women with pre-existing diabetes who had delivered two successive pregnancies to explore the influences of recurrent adverse pregnancy outcome. Maternal pre-pregnancy obesity and diabetes were both associated with increased risks of congenital anomaly, stillbirth, and infant death, with stronger effects for diabetes than obesity. In diabetes, peri-conception glycaemic control was strongly associated with birthweight and the risks of congenital anomaly, stillbirth, and infant death, and previous adverse outcome was associated with a doubled risk in the second pregnancy. For each article I provide a contemporary analysis of its contribution to the literature and critique of the methodology. The wider relevance of the research is also considered by discussing the evidence for causality, potential mechanisms, and implications for public health. Finally, I reflect on my individual contributions and my development towards an independent epidemiologist.the Newlife Foundation, NHS North of Tyne, Diabetes UK, and the South Tees Hospitals NHS Foundation Trust

LWIR HgCdTe: Innovative detectors in an incumbent technology

HgCdTe is the current material of choice for high performance imagers operating at relatively high temperatures. Its lack of technological maturity compared with silicon and wide-band gap III-V compounds is more than offset by its outstanding IR sensitivity and by the relatively benign effect of its materials defects. This latter property has allowed non-equilibrium growth techniques, metal oxide chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE), to produce device quality long wavelength infrared (LWIR) HgCdTe even on common substrates like GaAs and GaAs/Si. Detector performance in these exotic materials structures is comparable in many ways with devices in equilibrium-grown material. Lifetimes are similar. RoA values at 77K as high as several hundred have been seen in HgCdTe/GaAs/Si with 9.5 micron cut-off wavelength. HgCdTe/GaAs layers with approx. 15 micron cut-off wavelengths have given average 77K RoAs of greater than 2. Hybrid focal plane arrays have been evaluated with excellent operability

Estimating Increased Transient Water Storage With Increases in Beaver Dam Activity

Dam building by beaver (Castor spp.) slows water movement through montane valleys, increasing transient water storage and the diversity of residence times. In some cases, water storage created by beaver dam construction is correlated to changes in streamflow magnitude and timing. However, the total amount of additional surface and groundwater storage that beaver dams may create (and, thus, their maximum potential impact on streamflow) has not been contextualized in the water balance of larger river basins. We estimate the potential transient water storage increases that could be created at 5, 25, 50, and 100% of maximum modeled beaver dam capacity in the Bear River basin, USA, by adapting the height above nearest drainage (HAND) algorithm to spatially estimate surface water storage. Surface water storage estimates were combined with the MODFLOW groundwater model to estimate potential increases in groundwater storage throughout the basin. We tested four scenarios to estimate potential transient water storage increases resulting from the construction of 1179 to 34,897 beaver dams, and estimated surface water storage to range from 57.5 to 72.8 m3 per dam and groundwater storage to range from 182.2 to 313.3 m3 per dam. Overall, we estimate that beaver dam construction could increase transient water storage by up to 10.38 million m3 in the Bear River basin. We further contextualize beaver dam-related water storage increases with streamflow, reservoir, and snowpack volumes