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 & Context (language use). 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.

Global carbon budget 2014

Abstract: Accurate assessment of anthropogenic carbon dioxide (CO 2 ) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO 2 emissions from fossil fuel combustion and cement production (E FF ) are based on energy statistics and cement production data, respectively, while emissions from land-use change (E LUC ), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO 2 concentration is measured directly and its rate of growth (G ATM ) is computed from the annual changes in concentration. The mean ocean CO 2 sink (S OCEAN ) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in S OCEAN is evaluated with data products based on surveys of ocean CO 2 measurements. The global residual terrestrial CO 2 sink (S LAND ) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO 2 , and land-cover-change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2004–2013), E FF was 8.9 ± 0.4 GtC yr −1 , E LUC 0.9 ± 0.5 GtC yr −1 , G ATM 4.3 ± 0.1 GtC yr −1 , S OCEAN 2.6 ± 0.5 GtC yr −1 , and S LAND 2.9 ± 0.8 GtC yr −1 . For year 2013 alone, E FF grew to 9.9 ± 0.5 GtC yr −1 , 2.3% above 2012, continuing the growth trend in these emissions, E LUC was 0.9 ± 0.5 GtC yr −1 , G ATM was 5.4 ± 0.2 GtC yr −1 , S OCEAN was 2.9 ± 0.5 GtC yr −1 and S LAND was 2.5 ± 0.9 GtC yr −1 . G ATM was high in 2013, reflecting a steady increase in E FF and smaller and opposite changes between S OCEAN and S LAND compared to the past decade (2004–2013). The global atmospheric CO 2 concentration reached 395.31 ± 0.10 ppm averaged over 2013. We estimate that E FF will increase by 2.5% (1.3–3.5%) to 10.1 ± 0.6 GtC in 2014 (37.0 ± 2.2 GtCO 2 yr −1 ), 65% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the global economy. From this projection of E FF and assumed constant E LUC for 2014, cumulative emissions of CO 2 will reach about 545 ± 55 GtC (2000 ± 200 GtCO 2 ) for 1870–2014, about 75% from EF FF and 25% from E LUC . This paper documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this living data set (Le Quere et al., 2013, 2014). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2014).

Cognitive decline in Parkinson disease

Abstract: Dementia is a frequent problem encountered in advanced stages of Parkinson disease (PD). In recent years, research has focused on the pre-dementia stages of cognitive impairment in PD, including mild cognitive impairment (MCI). Several longitudinal studies have shown that MCI is a harbinger of dementia in PD, although the course is variable, and stabilization of cognition - or even reversal to normal cognition - is not uncommon. In addition to limbic and cortical spread of Lewy pathology, several other mechanisms are likely to contribute to cognitive decline in PD, and a variety of biomarker studies, some using novel structural and functional imaging techniques, have documented in vivo brain changes associated with cognitive impairment. The evidence consistently suggests that low cerebrospinal fluid levels of amyloid-β42, a marker of comorbid Alzheimer disease (AD), predict future cognitive decline and dementia in PD. Emerging genetic evidence indicates that in addition to the APOE*e4 allele (an established risk factor for AD), GBA mutations and SCNA mutations and triplications are associated with cognitive decline in PD, whereas the findings are mixed for MAPT polymorphisms. Cognitive enhancing medications have some effect in PD dementia, but no convincing evidence that progression from MCI to dementia can be delayed or prevented is available, although cognitive training has shown promising results.

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

Abstract: Major insights into the phylogenetic distribution, biochemistry, and evolutionary significance of organelles involved in ATP synthesis (energy metabolism) in eukaryotes that thrive in anaerobic environments for all or part of their life cycles have accrued in recent years. All known eukaryotic groups possess an organelle of mitochondrial origin, mapping the origin of mitochondria to the eukaryotic common ancestor, and genome sequence data are rapidly accumulating for eukaryotes that possess anaerobic mitochondria, hydrogenosomes, or mitosomes. Here we review the available biochemical data on the enzymes and pathways that eukaryotes use in anaerobic energy metabolism and summarize the metabolic end products that they generate in their anaerobic habitats, focusing on the biochemical roles that their mitochondria play in anaerobic ATP synthesis. We present metabolic maps of compartmentalized energy metabolism for 16 well-studied species. There are currently no enzymes of core anaerobic energy metabolism that are specific to any of the six eukaryotic supergroup lineages; genes present in one supergroup are also found in at least one other supergroup. The gene distribution across lineages thus reflects the presence of anaerobic energy metabolism in the eukaryote common ancestor and differential loss during the specialization of some lineages to oxic niches, just as oxphos capabilities have been differentially lost in specialization to anoxic niches and the parasitic life-style. Some facultative anaerobes have retained both aerobic and anaerobic pathways. Diversified eukaryotic lineages have retained the same enzymes of anaerobic ATP synthesis, in line with geochemical data indicating low environmental oxygen levels while eukaryotes arose and diversified.