Projections for future radiocarbon content in dissolved inorganic carbon in hardwater lakes: a retrospective approach

Inland water bodies contain significant amounts of carbon in the form of dissolved inorganic carbon (DIC) derived from a mixture of modern atmospheric and pre-aged sources, which needs to be considered in radiocarbon-based dating and natural isotope tracer studies. While reservoir effects in hardwater lakes are generally considered to be constant through time, a comparison of recent and historical DI14C data from 2013 and 1969 for Lake Constance reveals that this is not a valid assumption. We hypothesize that changes in atmospheric carbon contributions to lake water DIC have taken place due to anthropogenically forced eutrophication in the 20th century. A return to more oligotrophic conditions in the lake led to reoxygenation and enhanced terrigenous organic matter remineralization, contributing to lake water DIC. Such comparisons using DI14C measurements from different points in time enable nonlinear changes in lake water DIC source and signature to be disentangled from concurrent anthropogenically induced changes in atmospheric 14C. In the future, coeval changes in lake dynamics due to climate change are expected to further perturb these balances. Depending on the scenario, Lake Constance DI14C is projected to decrease from the 2013 measured value of 0.856 Fm to 0.54–0.62 Fm by the end of the century

Personal development planning in the first year

The approach to quality and standards in higher education (HE) in Scotland is enhancement led and learner centred. It was developed through a partnership of the Scottish Funding Council (SFC), Universities Scotland, the National Union of Students in Scotland (NUS Scotland) and the Quality Assurance Agency for Higher Education (QAA) Scotland. The Higher Education Academy has also joined that partnership. The Enhancement Themes are a key element of a five-part framework, which has been designed to provide an integrated approach to quality assurance and enhancement. The Enhancement Themes support learners and staff at all levels in further improving higher education in Scotland; they draw on developing innovative practice within the UK and internationally The five elements of the framework are: z a comprehensive programme of subject-level reviews undertaken by higher education institutions (HEIs) themselves; guidance is published by the SFC (www.sfc.ac.uk) z enhancement-led institutional review (ELIR), run by QAA Scotland (www.qaa.ac.uk/reviews/ELIR) z improved forms of public information about quality; guidance is provided by the SFC (www.sfc.ac.uk) z a greater voice for students in institutional quality systems, supported by a national development service - student participation in quality scotland (sparqs) (www.sparqs.org.uk) z a national programme of Enhancement Themes aimed at developing and sharing good practice to enhance the student learning experience, facilitated by QAA Scotland (www.enhancementthemes.ac.uk). The topics for the Enhancement Themes are identified through consultation with the sector and implemented by steering committees whose members are drawn from the sector and the student body. The steering committees have the task of establishing a programme of development activities, which draw on national and international good practice. Publications emerging from each Theme are intended to provide important reference points for HEIs in the ongoing strategic enhancement of their teaching and learning provision. Full details of each Theme, its steering committee, the range of research and development activities as well as the outcomes are published on the Enhancement Themes website (www.enhancementthemes.ac.uk). To further support the implementation and embedding of a quality enhancement culture within the sector - including taking forward the outcomes of the Enhancement Themes - an overarching committee, the Scottish Higher Education Enhancement Committee (SHEEC), chaired by Professor Kenneth Miller, Vice-Principal, University of Strathclyde, has the important dual role of supporting the overall approach of the Enhancement Themes, including the five-year rolling plan, as well as institutional enhancement strategies and management of quality. SHEEC, working with the individual topic-based Enhancement Themes' steering committees, will continue to provide a powerful vehicle for progressing the enhancement-led approach to quality and standards in Scottish higher education

Confinement of the Sun's interior magnetic field: some exact boundary-layer solutions

High-latitude laminar confinement of the Sun's interior magnetic field is shown to be possible, as originally proposed by Gough and McIntyre (1998) but contrary to a recent claim by Brun and Zahn (A&A 2006). Mean downwelling as weak as 2x10^-6cm/s -- gyroscopically pumped by turbulent stresses in the overlying convection zone and/or tachocline -- can hold the field in advective-diffusive balance within a confinement layer of thickness scale ~ 1.5Mm ~ 0.002 x (solar radius) while transmitting a retrograde torque to the Ferraro-constrained interior. The confinement layer sits at the base of the high-latitude tachocline, near the top of the radiative envelope and just above the `tachopause' marking the top of the helium settling layer. A family of exact, laminar, frictionless, axisymmetric confinement-layer solutions is obtained for uniform downwelling in the limit of strong rotation and stratification. A scale analysis shows that the flow is dynamically stable and the assumption of laminar flow realistic. The solution remains valid for downwelling values of the order of 10^-5cm/s but not much larger. This suggests that the confinement layer may be unable to accept a much larger mass throughput. Such a restriction would imply an upper limit on possible internal field strengths, perhaps of the order of hundreds of gauss, and would have implications also for ventilation and lithium burning. The solutions have interesting chirality properties not mentioned in the paper owing to space restrictions, but described at http://www.atmos-dynamics.damtp.cam.ac.uk/people/mem/papers/SQBO/solarfigure.htmlComment: 6 pages, 3 figures, to appear in conference proceedings: Unsolved Problems in Stellar Physic

Nitric Oxide and Superoxide in Genetic Hypertension: Effects of Age and Gender

Nitric oxide (NO) is now recognised as an important regulatory molecule in the cardiovascular system. NO is synthesised from the amino acid L-arginine by a family of three isoenzymes, the nitric oxide synthases (NOS). NOS III is the isoform constitutively expressed in the endothelium, but its expression can be regulated by shear stress and oestrogens among other factors. Endothelium derived NO seems to play a role in preventing atherosclerosis, but its role in hypertension is less clear. Some animal and human studies favour an important role, whereas others do not. Gender differences in cardiovascular disease, endothelial function and NO are well recognised, but the underlying mechanism remains unclear. There are theoretical reasons, and indeed experimental evidence, to implicate oestrogens, although again there is some debate about possible mechanism(s). The process of ageing is thought to be related to oxidative stress and hypertension has been described as an accelerated form of ageing, but the role of superoxide anion (O2 ) and superoxide dismutase (SOD) in hypertension and ageing is only now becoming clearer. To determine blood pressure and gender differences in NO availability, rings of thoracic aorta from 16 week old males and females, normotensive Wistar-Kyoto rats (WKY) and stroke prone spontaneously hypertensive rats (SHRSP) were studied in classic organ bath experiments. Stimulated NO availability was assessed by carbachol relaxation (10e8 - 10e5 mol/L) and basal NO availability was assessed by contraction to the NOS inhibitor NG-nitro- L-arginine methyl ester (L-NAME, 100mumol/L). The contribution of the 02/S0D system was assessed in the organ bath by examining the effects of inhibiting endogenous SOD with diethyldithiocarbamate (DETCA, 10 mmol/L) and adding exogenous SOD (45U/mL). In vitro NOS III activity was assessed in the 4 groups using the L-arginine/L-citrulline assay. Endothelial NOS gene (Nos3) expression was measured by reverse transcription-polymerase chain reaction. Expression of intracellular copper zinc SOD (Sodl) and mitochondrial manganese SOD (Sod2) mRNA was measured by northern blotting and expressed as a ratio to glyceraldehyde phosphate dehydrogenase (GAPDH) mRNA. The effect of age on endothelial function was assessed by measuring the response to L-NAME (100mumol/L) in aortic rings from the same 4 groups of rats at 4, 6 and 12 months of age. The effect of oestrogen was assessed by administering 17beta-oestradiol (20mug per day, intraperitoneally, for 2 weeks) to a group of 1 year old WKY females and comparing basal and stimulated NO availability and Nos3 gene expression, as above, with a group of controls. In the organ bath, maximum relaxation to carbachol (Emax) was significantly greater in aortic rings from WKY compared to rings from SHRSP (p=0.015). Within the SHRSP strain the carbachol concentration causing 50% relaxation (EC50) was significantly less in females compared to males (p=0.003). There were no other significant gender differences in carbachol Emax or EC50. These data suggest that stimulated NO availability may be greater in WKY compared to SHRSP and perhaps SHRSP females compared to SHRSP males. The contraction of aortic rings to L-NAME was significantly greater in WKY compared to SHRSP (p=0.015). Further, this contraction in rings from WKY females was significantly greater than WKY males (p=0.00004). Similarly, the contraction in rings from SHRSP females was significantly greater than SHRSP males (p=0.0006). These data suggest that basal NO availability is greater in WKY compared to SHRSP and in females compared to males in both strains. The SOD inhibitor DETCA attenuated the relaxation to carbachol of SHRSP significantly more than WKY (p=0.0008). There were no strain or gender differences in the effect of adding exogenous SOD to the water bath. These data suggest that in aortas of SHRSP, SOD is more active, or O2 accumulates faster, or a combination of both. NOS III activity was significantly greater in the aortas from SHRSP compared to WKY (p=0.016). In both strains NOS III activity tended to be higher in males compared to females, but the differences did not reach statistical significance. Nos3 mRNA expression was greater in SHRSP compared to WKY, although the difference just failed to reach statistical significance when corrected for triple comparisons (p=0.02). Again there was a tendency for Nos3 expression to be greater in males compared to females in both strains. These data combined suggest that the reduced NO availability in SHRSP is not due to reduced NO production

Is Landscape Context Important for Riparian Conservation? Birds in Grassy Woodland

An important challenge for riparian management is to determine the extent to which landscape context influences the faunal assemblages of riparian habitats. We examined this challenge in the variegated landscapes of southeastern Queensland, Australia where riparian vegetation is surrounded by both extensive grazing and intensive cropping. We investigated whether riparian habitats adjacent to different landuses support similar bird assemblages. Three types of riparian habitat condition were sampled (uncleared ungrazed; uncleared grazed; cleared grazed) in four different land-use contexts (ungrazed woodland; grazed woodland; native pasture; crop) although only six of the twelve possible treatment combinations were available. Eighty percent of bird species responded significantly to changes in both riparian habitat condition and landscape context, while fewer than 50% of species were significantly influenced by landscape context alone. The influence of landscape context on the bird assemblage increased as the surrounding land use became more intensive (e.g. woodland to native pasture to crop). Riparian zones have been shown to have consistently high biodiversity values relative to their extent. These findings suggest it is not enough to conserve riparian habitats alone, conservation and restoration plans must also take into consideration landscape context, particularly when that context is intensively used land

Petrogenic organic carbon retention in terrestrial basins: a case study from perialpine Lake Constance

Inland waters play a major role in the global carbon cycle, with particulate organic carbon (POC) burial in terrestrial wetlands surpassing that in ocean sediments. Lake Constance, the second largest lake at the periphery of the European Alps, receives POC sourced from both aquatic and terrestrial productivity as well as petrogenic OC (OCpetro) from bedrock erosion. Distinguishing POC inputs to lake sediments is key to assessing carbon flux and fate as reworked OCpetro represents neither a net sink of atmospheric CO2 nor source of O2. New stable and radiocarbon isotopic data indicate that 11 (9–12) Gg/yr of OCpetro is buried in Lake Constance with underlying sediments on average containing 0.3 (0.25–0.33) wt% OCpetro. Extrapolation of these results suggests that 27 TgOCpetro/yr (12–54 TgOC/yr) could be subject to temporary geological storage in lakes globally, which is comparable to estimates of 43−25+61 TgOCpetro/yr delivered to the ocean by rivers (Galy et al., 2015). More studies are needed to quantify OCpetro burial in inland sedimentary reservoirs in order to accurately account for atmospheric carbon sequestration in terrestrial basins

Computational aspects of N-mixture models

The N-mixture model is widely used to estimate the abundance of a population in the presence of unknown detection probability from only a set of counts subject to spatial and temporal replication (Royle, 2004, Biometrics 60,105–115). We explain and exploit the equivalence of N-mixture and multivariate Poisson and negative-binomial models, which provides powerful new approaches for fitting these models. We show that particularly when detection probability and the number of sampling occasions are small, infinite estimates of abundance can arise. We propose a sample covariance as a diagnostic for this event, and demonstrate its good performance in the Poisson case. Infinite estimates may be missed in practice, due to numerical optimization procedures terminating at arbitrarily large values. It is shown that the use of a bound, K, for an infinite summation in the N-mixture likelihood can result in underestimation of abundance, so that default values of K in computer packages should be avoided. Instead we propose a simple automatic way to choose K. The methods are illustrated by analysis of data on Hermann’s tortoise Testudo hermanni

Predicting the impact of livestock grazing on birds using foraging height data

1. Habitat structure is a major determinant of bird species diversity. One process by which habitat structure is altered is livestock grazing, the most extensive land use across most continents. While the impacts of grazing on vegetation have received much attention, the effects on avifauna are less well known