1,465 research outputs found

    Changes in soil characteristics under different aged plantations of Corsican pine (pinus nigra) at Chopwell Woodland Park, Gateshead, UK

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    This study examines the pedogenic processes and temporal changes occurring in soils across six different aged plantations of Corsican pine (Pinus nigra), which were otherwise similar in their environmental characteristics, including geology, slope angle and aspect, altitude and land use history. A representative soil profile was sampled, on a horizon basis, and a further 10 topsoil samples were collected, on a grid basis, from each plantation. Properties determined in the laboratory included pH, organic carbon content, particle size distribution, exchangeable base content (Ca, Mg, K, Na), total free and organically-bound iron content, and lead and zinc concentrations. Morphological and chemical changes within the soil profiles were examined to shed light on the processes and pathways of soil formation, and one-way analysis of variance (ANOVA) was used to compare topsoil characteristics between the different plantations. Morphological and chemical changes within the soil profiles indicated that organic matter accumulation and mor humus formation, acidification, clay translocation (lessivage) and incipient podzolisation were the dominant pedogenic processes. There are very few systematic age-related changes in soil morphological or physical and chemical characteristics, possibly due to a combination of young stand ages, high topsoil variability, soil mixing due to drainage operations and silvicultural practices. There are, however, a number of statistically significant but non-systematic differences in soil properties between the different aged plantation blocks. Possible associations between these differences and age-related litter production and root growth, and silvicultural operations such as understory control, plantation thinning and selective harvesting are explored

    A common neural substrate for language production and verbal working memory

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    Verbal working memory (VWM), the ability to maintain and manipulate representations of speech sounds over short periods, is held by some influential models to be independent from the systems responsible for language production and comprehension [e.g., Baddeley, A. D. Working memory, thought, and action. New York, NY: Oxford University Press, 2007]. We explore the alternative hypothesis that maintenance in VWM is subserved by temporary activation of the language production system [Acheson, D. J., & MacDonald, M. C. Verbal working memory and language production: Common approaches to the serial ordering of verbal information. Psychological Bulletin, 135, 50–68, 2009b]. Specifically, we hypothesized that for stimuli lacking a semantic representation (e.g., nonwords such as mun), maintenance in VWM can be achieved by cycling information back and forth between the stages of phonological encoding and articulatory planning. First, fMRI was used to identify regions associated with two different stages of language production planning: the posterior superior temporal gyrus (pSTG) for phonological encoding (critical for VWM of nonwords) and the middle temporal gyrus (MTG) for lexical–semantic retrieval (not critical for VWM of nonwords). Next, in the same subjects, these regions were targeted with repetitive transcranial magnetic stimulation (rTMS) during language production and VWM task performance. Results showed that rTMS to the pSTG, but not the MTG, increased error rates on paced reading (a language production task) and on delayed serial recall of nonwords (a test of VWM). Performance on a lexical–semantic retrieval task (picture naming), in contrast, was significantly sensitive to rTMS of the MTG. Because rTMS was guided by language production-related activity, these results provide the first causal evidence that maintenance in VWM directly depends on the long-term representations and processes used in speech production

    Small Fishing Ports in Southern New England, Report to the National Science Foundation, Volume Ib

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    Social and cultural aspects of fisheries management were examined to establish basic data on the fishing communities and fisheries of southern New England. Five small ports were selected for study--Newport, Chatham, and Westport, Massachusetts; Newport, Rhode Island; and Stonington, Connecticut. These ports differ in terms of local, social, and geographical conditions, fishing styles, and emphases. Results of the study show that these ports act as a backup for the industry as a whole by (1) providing sources of fish for local markets; (2) using low energy models which reduce energy costs; (3) allowing individual fishermen a greater opportunity to find 0 port to suit their life-style; and (4) complementing tourist activities by supplying fresh seafood products. However, a conflict was found to exist between the commercial fisheries and businesses operating largely on the summer tourist trade. More money has been added to the local economy from the latter, resulting in restricted development of commercial fishing

    Retinal nerve fibre layer thinning is associated with drug resistance in epilepsy.

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    Retinal nerve fibre layer (RNFL) thickness is related to the axonal anterior visual pathway and is considered a marker of overall white matter 'integrity'. We hypothesised that RNFL changes would occur in people with epilepsy, independently of vigabatrin exposure, and be related to clinical characteristics of epilepsy

    Active surveillance of choroidal neovascularisation in children: incidence, aetiology and management findings from a national study in the UK

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    BACKGROUND/AIMS: To determine the UK incidence, demographics, aetiology, management and visual outcome for children developing choroidal neovascularisation (CNV). METHODS: A prospective population-based observational study of routine practice via the British Ophthalmological Surveillance Unit between January 2012 and December 2013 with subsequent 1-year follow-up in children under 16 years old with newly diagnosed CNV. RESULTS: Twenty-seven children with CNV were reported. The UK estimated annual incidence for those aged 16 and under was 0.21 per 100 000 (95% CI 0.133 to 0.299). The mean age was 11.1 years (SD 3.9, range 4-16). Fourteen were female. Seventy-seven per cent (22 patients) were Caucasian British. Twenty-three children (85%) had unilateral disease. The most common aetiology included inflammatory retinochoroidopathy (n=9), optic disc abnormalities (n=9) and idiopathic (n=5). Optical coherence tomography was performed in all cases and fundus fluorescein angiography in 61%. Management included observation only (n=10), anti-vascular endothelial growth factor (anti-VEGF) injection of bevacizumab (n=14) or ranibizumab (n=2), or both (n=1), and additional use of oral (n=1) and local (periocular n=2 and intravitreal n=2) steroids in five children with inflammatory retinochoroidopathy. The mean number of anti-VEGF injections was 2±1, with eight patients receiving only one injection. The mean (SD) best corrected visual acuity in LogMAR was 0.91 (0.53) at presentation and 0.74 (0.53) at 1-year follow-up (p=0.09). CONCLUSION: This is the first population-based prospective study of CNV in children. This is a rare disorder with a poor visual prognosis irrespective of CNV location and the use of anti-VEGF therapy

    Hydrodynamic and magnetohydrodynamic computations inside a rotating sphere

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    Numerical solutions of the incompressible magnetohydrodynamic (MHD) equations are reported for the interior of a rotating, perfectly-conducting, rigid spherical shell that is insulator-coated on the inside. A previously-reported spectral method is used which relies on a Galerkin expansion in Chandrasekhar-Kendall vector eigenfunctions of the curl. The new ingredient in this set of computations is the rigid rotation of the sphere. After a few purely hydrodynamic examples are sampled (spin down, Ekman pumping, inertial waves), attention is focused on selective decay and the MHD dynamo problem. In dynamo runs, prescribed mechanical forcing excites a persistent velocity field, usually turbulent at modest Reynolds numbers, which in turn amplifies a small seed magnetic field that is introduced. A wide variety of dynamo activity is observed, all at unit magnetic Prandtl number. The code lacks the resolution to probe high Reynolds numbers, but nevertheless interesting dynamo regimes turn out to be plentiful in those parts of parameter space in which the code is accurate. The key control parameters seem to be mechanical and magnetic Reynolds numbers, the Rossby and Ekman numbers (which in our computations are varied mostly by varying the rate of rotation of the sphere) and the amount of mechanical helicity injected. Magnetic energy levels and magnetic dipole behavior are exhibited which fluctuate strongly on a time scale of a few eddy turnover times. These seem to stabilize as the rotation rate is increased until the limit of the code resolution is reached.Comment: 26 pages, 17 figures, submitted to New Journal of Physic

    Obesity: A Biobehavioral Point of View

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    Excerpt: If you ask an overweight person, “Why are you fat?’, you will, almost invariably, get the answer, “Because 1 eat too much.” You will get this answer in spite of the fact that of thirteen studies, six find no significant differences in the caloric intake of obese versus nonobese subjects, five report that the obese eat significantly less than the nonobese, and only two report that they eat significantly more

    Reflection and Ducting of Gravity Waves Inside the Sun

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    Internal gravity waves excited by overshoot at the bottom of the convection zone can be influenced by rotation and by the strong toroidal magnetic field that is likely to be present in the solar tachocline. Using a simple Cartesian model, we show how waves with a vertical component of propagation can be reflected when traveling through a layer containing a horizontal magnetic field with a strength that varies with depth. This interaction can prevent a portion of the downward-traveling wave energy flux from reaching the deep solar interior. If a highly reflecting magnetized layer is located some distance below the convection zone base, a duct or wave guide can be set up, wherein vertical propagation is restricted by successive reflections at the upper and lower boundaries. The presence of both upward- and downward-traveling disturbances inside the duct leads to the existence of a set of horizontally propagating modes that have significantly enhanced amplitudes. We point out that the helical structure of these waves makes them capable of generating an alpha-effect, and briefly consider the possibility that propagation in a shear of sufficient strength could lead to instability, the result of wave growth due to over-reflection.Comment: 23 pages, 5 figures. Accepted for publication in Solar Physic
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