Matrix Wiener-Hopf factorisation

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Quarterly Journal of Mechanics and Applied Mathematics following peer review. The definitive publisher-authenticated version can be obtained from the links below.A direct method is described for effecting the Wiener-Hopf factorisation of a particular class of matrices. It is shown that the factorisation problem can, for this class of matrix, be transformed to one of solving two independent Hilbert problems on a half-line

Problems, deficiencies and opportunities of the planning system in the Transvaal

Deficiencies in the current planning framework not only give rise to unnecessary cumbersome and time-consuming practices, but also prevent effective and thorough planning action taking place in time. The proposed behavioral sketches outlined in this article will hopefully help to alleviate the situation, and increase the efficiency of the planning process and the associated parts for the community

On the use of radon for quantifying the effects of atmospheric stability on urban emissions

Radon is increasingly being used as a tool for quantifying stability influences on urban pollutant concentrations. Bulk radon gradients are ideal for this purpose, since the vertical differencing substantially removes contributions from processes on timescales greater than diurnal and (assuming a constant radon source) gradients are directly related to the intensity of nocturnal mixing. More commonly, however, radon measurements are available only at a single height. In this study we argue that single-height radon observations should not be used quantitatively as an indicator of atmospheric stability without prior conditioning of the time series to remove contributions from larger-scale "non-local" processes. We outline a simple technique to obtain an approximation of the diurnal radon gradient signal from a single-height measurement time series, and use it to derive a four category classification scheme for atmospheric stability on a "whole night" basis. A selection of climatological and pollution observations in the Sydney region are then subdivided according to the radon-based scheme on an annual and seasonal basis. We compare the radon-based scheme against a commonly used Pasquill–Gifford (P–G) type stability classification and reveal that the most stable category in the P–G scheme is less selective of the strongly stable nights than the radon-based scheme; this lead to significant underestimation of pollutant concentrations on the most stable nights by the P–G scheme. Lastly, we applied the radon-based classification scheme to mixing height estimates calculated from the diurnal radon accumulation time series, which provided insight to the range of nocturnal mixing depths expected at the site for each of the stability classes. © 2015, Author(s)

Defects in Mitochondrial ATP Synthesis in Dystrophin-Deficient Mdx Skeletal Muscles May Be Caused by Complex I Insufficiency

Duchenne Muscular Dystrophy is a chronic, progressive and ultimately fatal skeletal muscle wasting disease characterised by sarcolemmal fragility and intracellular Ca2+ dysregulation secondary to the absence of dystrophin. Mounting literature also suggests that the dysfunction of key energy systems within the muscle may contribute to pathological muscle wasting by reducing ATP availability to Ca2+ regulation and fibre regeneration. No study to date has biochemically quantified and contrasted mitochondrial ATP production capacity by dystrophic mitochondria isolated from their pathophysiological environment such to determine whether mitochondria are indeed capable of meeting this heightened cellular ATP demand, or examined the effects of an increasing extramitochondrial Ca2+ environment. Using isolated mitochondria from the diaphragm and tibialis anterior of 12 week-old dystrophin-deficient mdx and healthy control mice (C57BL10/ScSn) we have demonstrated severely depressed Complex I-mediated mitochondrial ATP production rate in mdx mitochondria that occurs irrespective of the macronutrient-derivative substrate combination fed into the Kreb's cycle, and, which is partially, but significantly, ameliorated by inhibition of Complex I with rotenone and stimulation of Complex II-mediated ATP-production with succinate. There was no difference in the MAPR response of mdx mitochondria to increasing extramitochondrial Ca2+ load in comparison to controls, and 400 nM extramitochondrial Ca2+ was generally shown to be inhibitory to MAPR in both groups. Our data suggests that DMD pathology is exacerbated by a Complex I deficiency, which may contribute in part to the severe reductions in ATP production previously observed in dystrophic skeletal muscle

The effects of weight and physical activity change over 20 years on later-life objective and self-reported disability.

Weight and health behaviours are known to affect physical disability; however the evidence exploring the impact of changes to these lifestyle factors over the life course on disability is inconsistent. We aimed to explore the roles of weight and activity change between mid and later life on physical disability

The ecology of seamounts: structure, function, and human impacts.

In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research

Lipid lowering and Alzheimer's disease risk: a Mendelian randomization study

Objective: To examine whether genetic variation affecting the expression or function of lipid-lowering drug targets isassociated with Alzheimer disease (AD) risk, to evaluate the potential impact of long-term exposure to correspondingtherapeutics.Methods: We conducted Mendelian randomization analyses using variants in genes that encode the protein targets ofseveral approved lipid-lowering drug classes: HMGCR (encoding the target for statins), PCSK9 (encoding the target forPCSK9 inhibitors, eg, evolocumab and alirocumab), NPC1L1 (encoding the target for ezetimibe), and APOB (encodingthe target of mipomersen). Variants were weighted by associations with low-density lipoprotein cholesterol (LDL-C)using data from lipid genetics consortia (n up to 295,826). We meta-analyzed Mendelian randomization estimates forregional variants weighted by LDL-C on AD risk from 2 large samples (total n = 24,718 cases, 56,685 controls).Results: Models for HMGCR, APOB, and NPC1L1 did not suggest that the use of related lipid-lowering drug classeswould affect AD risk. In contrast, genetically instrumented exposure to PCSK9 inhibitors was predicted to increase ADrisk in both of the AD samples (combined odds ratio per standard deviation lower LDL-C inducible by the drug tar-get = 1.45, 95% confidence interval = 1.23–1.69). This risk increase was opposite to, although more modest than, thedegree of protection from coronary artery disease predicted by these same methods for PCSK9 inhibition.Interpretation: We did not identify genetic support for the repurposing of statins, ezetimibe, or mipomersen for ADprevention. Notwithstanding caveats to this genetic evidence, pharmacovigilance for AD risk among users of PCSK9inhibitors may be warranted

Improved mixing height monitoring through a combination of lidar and radon measurements

Surface-based radon (222Rn) measurements can be combined with lidar backscatter to obtain a higher quality time series of mixing height within the planetary boundary layer (PBL) than is possible from lidar alone, and a more quantitative measure of mixing height than is possible from only radon. The reason why lidar measurements are improved is that there are times when lidar signals are ambiguous, and reliably attributing the mixing height to the correct aerosol layer presents a challenge. By combining lidar with a mixing length scale derived from a time series of radon concentration, automated and robust attribution is possible during the morning transition. Radon measurements provide mixing information during the night, but concentrations also depend on the strength of surface emissions. After processing radon in combination with lidar, we obtain nightly measurements of radon emissions and are able to normalise the mixing length scale for changing emissions. After calibration with lidar, the radonderived equivalent mixing height agrees with other measures of mixing on daily and hourly timescales and is a potential method for studying intermittent mixing in nocturnal boundary layers.© 2013, Copernicus Publications

Characterising terrestrial influences on Antarctic air masses using Radon-222 measurements at King George Island

We report on one year of high-precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m−3 in late-summer to 44 mBq m−3 in late winter and early spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m−3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47–53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8–4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised. © Author(s) 201