University of Exeter

About: University of Exeter is a education organization based out in Exeter, United Kingdom. It is known for research contribution in the topics: Population & Climate change. The organization has 15820 authors who have published 50650 publications receiving 1793046 citations. The organization is also known as: Exeter University & University of the South West of England.

Pan genome of the phytoplankton Emiliania underpins its global distribution

Abstract: Coccolithophores have influenced the global climate for over 200 million years(1). These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems(2). They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space(3). Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean(4). Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.

Electrochromism and Electrochromic Devices

Abstract: Electrochromic materials, both organic and inorganic, have widespread applications in light-attenuation, displays and analysis. Written in an accessible manner, this book provides a comprehensive treatment of all types of electrochromic systems and their many applications. Coverage develops from electrochromic scope and history to new searching presentations of optical quantification and theoretical mechanistic models. Non-electrode electrochromism and photo-electrochromism are summarised, with updated comprehensive reviews of electrochromic oxides (tungsten-trioxide particularly), metal co-ordination complexes and metal-cyanometallates, viologens and other organics; and more recent exotics such as fullerenes, hydrides, and conjugated electroactive polymers are also covered. The book concludes by examining device construction and durability. With an extensive bibliography, recent advances in the field, modern applications and a step-by-step development from simple examples to sophisticated theories, this book is ideal for researchers in materials science, polymer science, electrical engineering, physics, chemistry, bioscience and (applied) optoelectronics.

Update on mutations in glucokinase (GCK), which cause maturity-onset diabetes of the young, permanent neonatal diabetes, and hyperinsulinemic hypoglycemia.

Abstract: Glucokinase is a key regulatory enzyme in the pancreatic beta-cell. It plays a crucial role in the regulation of insulin secretion and has been termed the glucose sensor in pancreatic beta-cells. Given its central role in the regulation of insulin release it is understandable that mutations in the gene encoding glucokinase (GCK) can cause both hyper- and hypoglycemia. Heterozygous inactivating mutations in GCK cause maturity-onset diabetes of the young (MODY) subtype glucokinase (GCK), characterized by mild fasting hyperglycemia, which is present at birth but often only detected later in life during screening for other purposes. Homozygous inactivating GCK mutations result in a more severe phenotype presenting at birth as permanent neonatal diabetes mellitus (PNDM). A growing number of heterozygous activating GCK mutations that cause hypoglycemia have also been reported. A total of 620 mutations in the GCK gene have been described in a total of 1,441 families. There are no common mutations, and the mutations are distributed throughout the gene. The majority of activating mutations cluster in a discrete region of the protein termed the allosteric activator site. The identification of a GCK mutation in patients with both hyper- and hypoglycemia has implications for the clinical course and clinical management of their disorder.

Forty eclipsing binaries in the Small Magellanic Cloud: fundamental parameters and Cloud distance

Abstract: We have conducted a programme to determine the fundamental parameters of a substantial number of eclipsing binaries of spectral types O and B in the Small Magellanic Cloud (SMC). New spectroscopic data, obtained with the two- degree- field (2dF) multi- object spectrograph on the 3.9- m Anglo- Australian Telescope, have been used in conjunction with photometry from the Optical Gravitational Lens Experiment (OGLE- II) data base of SMC eclipsing binaries. Previously we reported results for 10 systems; in this second and concluding paper we present spectral types, masses, radii, temperatures, surface gravities and luminosities for the components of a further 40 binaries. The uncertainties are typically +/- 10 per cent on masses, +/- 4 per cent on radii and +/- 0.07 on log L. The full sample of 50 OB- type eclipsing systems is the largest single set of fundamental parameters determined for high- mass binaries in any galaxy. We find that 21 of the systems studied are in detached configurations, 28 are in semidetached post- mass- transfer states, and one is a contact binary.The overall properties of the detached systems are consistent with theoretical models for the evolution of single stars with SMC metal abundances (Z similar or equal to 0.004); in particular, observed and evolutionary masses are in excellent agreement. Although there are no directly applicable published models, the overall properties of the semidetached systems are consistent with them being in the slow phase of mass transfer in case A. About 40 per cent of these semidetached systems show photometric evidence of orbital- phase- dependent absorption by a gas stream falling from the inner Lagrangian point on the secondary star towards the primary star. This sample demonstrates that case- A mass transfer is a common occurrence amongst high- mass binaries with initial orbital periods P less than or similar to 5 d, and that this slow phase has a comparable duration to the detached phase preceding it.Each system provides a primary distance indicator. We find a mean distance modulus to the SMC of 18.91 +/- 0.03 +/- 0.1 (internal and external uncertainties; D = 60.6 +/- 1.0 +/- 2.8 kpc). This value represents one of the most precise available determinations of the distance to the SMC.