High resolution satellite observations give new view of UK air quality

New state‐of‐the‐art satellite measurements of tropospheric column NO2 from the TROPOMI instrument on‐board Sentinel‐5 Precursor (S5P), launched in October 2017, allow for an unprecedented high resolution (sub‐10km) assessment of UK air quality (AQ) from space. We present the first results from TROPOMI and compare them with its predecessor, the Ozone Monitoring Instrument (OMI), to quantify previously unresolved UK pollution hotspots (e.g. Bristol, Southampton and Liverpool). The TROPOMI tropospheric column NO2 data represents a powerful new tool to quantify UK AQ, evaluate atmospheric composition models and potentially derive new emission inventories from space

High resolution satellite observations give new view of UK air quality

New state‐of‐the‐art satellite measurements of tropospheric column NO2 from the TROPOMI instrument on‐board Sentinel‐5 Precursor (S5P), launched in October 2017, allow for an unprecedented high resolution (sub‐10km) assessment of UK air quality (AQ) from space. We present the first results from TROPOMI and compare them with its predecessor, the Ozone Monitoring Instrument (OMI), to quantify previously unresolved UK pollution hotspots (e.g. Bristol, Southampton and Liverpool). The TROPOMI tropospheric column NO2 data represents a powerful new tool to quantify UK AQ, evaluate atmospheric composition models and potentially derive new emission inventories from space

Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands

This is the final version of the article. Available from Elsevier via the DOI in this record.Beavers are the archetypal keystone species, which can profoundly alter ecosystem structure and function through their ecosystem engineering activity, most notably the building of dams. This can have a major impact upon water resource management, flow regimes and water quality. Previous research has predominantly focused on the activities of North American beaver (Castor canadensis) located in very different environments, to the intensive lowland agricultural landscapes of the United Kingdom and elsewhere in Europe. Two Eurasian beavers (Castor fiber) were introduced to a wooded site, situated on a first order tributary, draining from intensively managed grassland. The site was monitored to understand impacts upon water storage, flow regimes and water quality. Results indicated that beaver activity, primarily via the creation of 13 dams, has increased water storage within the site (holding ca. 1000m(3) in beaver ponds) and beavers were likely to have had a significant flow attenuation impact, as determined from peak discharges (mean 30±19% reduction), total discharges (mean 34±9% reduction) and peak rainfall to peak discharge lag times (mean 29±21% increase) during storm events. Event monitoring of water entering and leaving the site showed lower concentrations of suspended sediment, nitrogen and phosphate leaving the site (e.g. for suspended sediment; average entering site: 112±72mgl(-1), average leaving site: 39±37mgl(-1)). Combined with attenuated flows, this resulted in lower diffuse pollutant loads in water downstream. Conversely, dissolved organic carbon concentrations and loads downstream were higher. These observed changes are argued to be directly attributable to beaver activity at the site which has created a diverse wetland environment, reducing downstream hydrological connectivity. Results have important implications for beaver reintroduction programs which may provide nature based solutions to the catchment-scale water resource management issues that are faced in agricultural landscapes.The Devon Beaver Project is led by Devon Wildlife Trust, monitored by the University of Exeter, and funded by Devon Wildlife Trust and Westland Countryside Stewards

Quantifying the transboundary contribution of nitrogen oxides to UK air quality

Nitrogen dioxide (NO2) pollution is an important contributor to poor air quality (AQ) and a significant cause of premature deaths in the UK. Although transboundary (i.e., international) transport of pollution to the UK is believed to have an impact on UK pollutant concentrations, large uncertainties remain in these estimates. Therefore, the extent to which emission reductions in neighbouring countries would benefit UK AQ relative to local emission reductions also remains unknown. We have used a back‐trajectory model in conjunction with synoptic scale classifications of UK circulation patterns (Lamb Weather Types [LWT]), to quantify the accumulation of nitrogen oxide (NO x = NO2 + NO) emissions in air masses en‐route to the UK. This novel method presents a computationally inexpensive and useful method of quantifying the accumulation of pollutants under different circulation patterns. We find the highest accumulated NO x totals occur under south‐easterly and southerly flows (>15 μg⋅m−2), with a substantial contribution from outwith the UK (>25%). In contrast, the total accumulated NO x under northerly and westerly flows is lower (∼10 μg⋅m−2), and dominated by UK emissions (>95%). This indicates that European emissions can contribute substantially to UK local‐scale pollution in urban areas under south‐easterly and southerly flows. The sensitivity of integrated NO x emission totals under different air masses is investigated by modelling future European emission contributions based on emission reduction targets. Under targets set by the European Union, there would be a decrease in accumulated NO x emissions in London under most wind directions except for north‐westerly, westerly and northerly flow. The largest benefits to UK AQ from transboundary contributions occur with emission reductions in the Benelux region, due to its close proximity and high NO x emission rates, emphasising the importance of international cooperation in improving local AQ

Pioneers in CNS inhibition: 2. Charles Sherrington and John Eccles on inhibition in spinal and supraspinal structures

This article reviews the contributions of the English neurophysiologist, Charles Scott Sherrington [1857–1952], and his Australian PhD trainee and collaborator, John Carew Eccles [1903–1997], to the concept of central inhibition in the spinal cord and brain. Both were awarded Nobel Prizes; Sherrington in 1932 for “discoveries regarding the function of neurons,” and Eccles in 1963 for “discoveries concerning the ionic mechanisms involved in excitation and inhibition in central portions of the nerve cell membrane.” Both spoke about central inhibition at their Nobel Prize Award Ceremonies. The subsequent publications of their talks were entitled “Inhibition as a coordinative factor” and “The ionic mechanism of postsynaptic inhibition”, respectively. Sherrington's work on central inhibition spanned 41 years (1893–1934), and for Eccles 49 years (1928–1977). Sherrington first studied central inhibition by observing hind limb muscle responses to electrical (peripheral nerve) and mechanical (muscle) stimulation. He used muscle length and force measurements until the early 1900s and electromyography in the late 1920s. Eccles used these techniques while working with Sherrington, but later employed extracellular microelectrode recording in the spinal cord followed in 1951 by intracellular recording from spinal motoneurons. This considerably advanced our understanding of central inhibition. Sherrington's health was poor during his retirement years but he nonetheless made a small number of largely humanities contributions up to 1951, one year before his death at the age of 94. In contrast, Eccles retained his health and vigor until 3 years before his death and published prolifically on many subjects during his 22 years of official retirement. His last neuroscience article appeared in 1994 when he was 91. Despite poor health he continued thinking about his life-long interest, the mind-brain problem, and was attempting to complete his autobiography in the last years of his life

Scheduling MapReduce Jobs under Multi-Round Precedences

We consider non-preemptive scheduling of MapReduce jobs with multiple tasks in the practical scenario where each job requires several map-reduce rounds. We seek to minimize the average weighted completion time and consider scheduling on identical and unrelated parallel processors. For identical processors, we present LP-based O(1)-approximation algorithms. For unrelated processors, the approximation ratio naturally depends on the maximum number of rounds of any job. Since the number of rounds per job in typical MapReduce algorithms is a small constant, our scheduling algorithms achieve a small approximation ratio in practice. For the single-round case, we substantially improve on previously best known approximation guarantees for both identical and unrelated processors. Moreover, we conduct an experimental analysis and compare the performance of our algorithms against a fast heuristic and a lower bound on the optimal solution, thus demonstrating their promising practical performance

Simple and Nearly Optimal Polynomial Root-finding by Means of Root Radii Approximation

We propose a new simple but nearly optimal algorithm for the approximation of all sufficiently well isolated complex roots and root clusters of a univariate polynomial. Quite typically the known root-finders at first compute some crude but reasonably good approximations to well-conditioned roots (that is, those isolated from the other roots) and then refine the approximations very fast, by using Boolean time which is nearly optimal, up to a polylogarithmic factor. By combining and extending some old root-finding techniques, the geometry of the complex plane, and randomized parametrization, we accelerate the initial stage of obtaining crude to all well-conditioned simple and multiple roots as well as isolated root clusters. Our algorithm performs this stage at a Boolean cost dominated by the nearly optimal cost of subsequent refinement of these approximations, which we can perform concurrently, with minimum processor communication and synchronization. Our techniques are quite simple and elementary; their power and application range may increase in their combination with the known efficient root-finding methods.Comment: 12 pages, 1 figur

How dynamic are ice-stream beds?

Projections of sea-level rise contributions from West Antarctica's dynamically thinning ice streams contain high uncertainty because some of the key processes involved are extremely challenging to observe. An especially poorly observed parameter is sub-decadal stability of ice-stream beds, which may be important for subglacial traction, till continuity and landform development. Only two previous studies have made repeated geophysical measurements of ice-stream beds at the same locations in different years, but both studies were limited in spatial extent. Here, we present the results from repeat radar measurements of the bed of Pine Island Glacier, West Antarctica, conducted 3–6 years apart, along a cumulative ∼ 60 km of profiles. Analysis of the correlation of bed picks between repeat surveys shows that 90 % of the bed displays no significant change despite the glacier increasing in speed by up to 40 % over the last decade. We attribute the negligible detection of morphological change at the bed of Pine Island Glacier to the ubiquitous presence of a deforming till layer, wherein sediment transport is in steady state, such that sediment is transported along the basal interface without inducing morphological change to the radar-sounded basal interface. Given the precision of our measurements, the upper limit of subglacial erosion observed here is 500 mm a‾¹, far exceeding erosion rates reported for glacial settings from proglacial sediment yields, but substantially below subglacial erosion rates of 1.0 m a‾¹ previously reported from repeat geophysical surveys in West Antarctica

Cuts and flows of cell complexes

We study the vector spaces and integer lattices of cuts and flows associated with an arbitrary finite CW complex, and their relationships to group invariants including the critical group of a complex. Our results extend to higher dimension the theory of cuts and flows in graphs, most notably the work of Bacher, de la Harpe and Nagnibeda. We construct explicit bases for the cut and flow spaces, interpret their coefficients topologically, and give sufficient conditions for them to be integral bases of the cut and flow lattices. Second, we determine the precise relationships between the discriminant groups of the cut and flow lattices and the higher critical and cocritical groups with error terms corresponding to torsion (co)homology. As an application, we generalize a result of Kotani and Sunada to give bounds for the complexity, girth, and connectivity of a complex in terms of Hermite's constant.Comment: 30 pages. Final version, to appear in Journal of Algebraic Combinatoric

What factors are associated with reporting lacking interest in sex and how do these vary by gender? Findings from the third British national survey of sexual attitudes and lifestyles

OBJECTIVES: To investigate factors associated with reporting lacking interest in sex and how these vary by gender. SETTING: British general population. DESIGN: Complex survey analyses of data collected for a cross-sectional probability sample survey, undertaken 2010-2012, specifically logistic regression to calculate age-adjusted OR (AOR) to identify associated factors. PARTICIPANTS: 4839 men and 6669 women aged 16-74 years who reported ≥1 sexual partner (opposite-sex or same-sex) in the past year for the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3). MAIN OUTCOME MEASURE: Lacking interest in sex for ≥3 months in the past year. RESULTS: Overall, 15.0% (13.9-16.2) of men and 34.2% (32.8-35.5) of women reported lacking interest in sex. This was associated with age and physical and mental health for both men and women, including self-reported general health and current depression. Lacking interest in sex was more prevalent among men and women reporting sexually transmitted infection diagnoses (ever), non-volitional sex (ever) and holding sexual attitudes related to normative expectations about sex. Some gender similarities in associated relationship and family-related factors were evident, including partner having had sexual difficulties in the last year (men: AOR 1.41 (1.07-1.86); women: AOR 1.60 (1.32-1.94)), not feeling emotionally close to partner during sex (men: 3.74 (1.76-7.93); women: 4.80 (2.99-7.69) and ease of talking about sex (men: 1.53 (1.23-1.90);women: 2.06 (1.77-2.39)). Among women only, lack of interest in sex was higher among those in a relationship of >1 year in duration and those not sharing the same level of interest (4.57 (3.87-5.38)) or preferences (2.91 (2.22-3.83)) with a partner. CONCLUSIONS: Both gender similarities and differences were found in factors associated with lacking interest in sex, with the most marked differences in relation to some relationship variables. Findings highlight the need to assess, and if appropriate, treat lacking interest in sex in a holistic and relationship-specific way