18,085 research outputs found

    LIMO EEG: A Toolbox for hierarchical LInear MOdeling of ElectroEncephaloGraphic data

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    Magnetic- and electric-evoked brain responses have traditionally been analyzed by comparing the peaks or mean amplitudes of signals from selected channels and averaged across trials. More recently, tools have been developed to investigate single trial response variability (e.g., EEGLAB) and to test differences between averaged evoked responses over the entire scalp and time dimensions (e.g., SPM, Fieldtrip). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data. In addition, LIMO EEG provides robust parametric tests, therefore providing a new and complementary tool in the analysis of neural evoked responses

    Climate Change in the High Andes:implications and adaptation strategies for small-scale farmers

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    Abstract: Global climate change represents a major threat to sustainable farming in the Andes. Farmers have used local ecological knowledge and intricate production systems to cope, adapt and reorganize to meet climate uncertainty and risk, which have always been a fact of life. Those traditional systems are generally highly resilient, but the predicted effects, rates and variability of climate change may push them beyond their range of adaptability. This article examines the extent of actual and potential impacts of climate variability and change on small-scale farmers in the highland Andes of Bolivia, Ecuador and Peru. It describes how climate change impacts agriculture through deglaciation, changes in hydrology, soil and pest and disease populations. The article highlights some promising adaptive strategies currently in use by or possible for producers, rural communities and local institutions to mitigate climate change effects while preserving the livelihoods and environmental and social sustainability of the regio

    The role of tidal interactions in driving galaxy evolution

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    We carry out a statistical analysis of galaxy pairs selected from chemical hydrodynamical simulations with the aim at assessing the capability of hierarchical scenarios to reproduce recent observational results for galaxies in pairs. Particularly, we analyse the effects of mergers and interactions on the star formation (SF) activity, the global mean chemical properties and the colour distribution of interacting galaxies. We also assess the effects of spurious pairs.Comment: to appear in "Groups of galaxies in the nearby Universe" ESO Workshop, (Dec 2005) Santiago, Chil

    Energy Spectrum of Anyons in a Magnetic Field

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    For the many-anyon system in external magnetic field, we derive the energy spectrum as an exact solution of the quantum eigenvalue problem with particular topological constraints. Our results agree with the numerical spectra recently obtained for the 3- and the 4-anyon systems.Comment: 11 pages in Plain LaTeX (plus 4 figures available on request), DFPD 92/TH/4

    Vapor swellable colloidal photonic crystals with pressure tunability

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    Polyferrocenylsilane gel photonic crystals have been reversibly swollen using solvent vapors, and exhibit precise pressure tunability over a wavelength range of greater than 100 nmGeneralitat Valenciana CTDIA/2002/2

    Gell-Mann and Low formula for degenerate unperturbed states

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    The Gell-Mann and Low switching allows to transform eigenstates of an unperturbed Hamiltonian H0H_0 into eigenstates of the modified Hamiltonian H0+VH_0 + V. This switching can be performed when the initial eigenstate is not degenerate, under some gap conditions with the remainder of the spectrum. We show here how to extend this approach to the case when the ground state of the unperturbed Hamiltonian is degenerate. More precisely, we prove that the switching procedure can still be performed when the initial states are eigenstates of the finite rank self-adjoint operator \cP_0 V \cP_0, where \cP_0 is the projection onto a degenerate eigenspace of H0H_0

    Molecular diversity of arbuscular mycorrhizal fungi in onion roots from organic and conventional farming systems in the Netherlands

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    Diversity and colonization levels of naturally occurring arbuscular mycorrhizal fungi (AMF) in onion roots were studied to compare organic and conventional farming systems in the Netherlands. In 2004, 20 onion fields were sampled in a balanced survey between farming systems and between two regions, namely, Zeeland and Flevoland. In 2005, nine conventional and ten organic fields were additionally surveyed in Flevoland. AMF phylotypes were identified by rDNA sequencing. All plants were colonized, with 60% for arbuscular colonization and 84% for hyphal colonization as grand means. In Zeeland, onion roots from organic fields had higher fractional colonization levels than those from conventional fields. Onion yields in conventional farming were positively correlated with colonization level. Overall, 14 AMF phylotypes were identified. The number of phylotypes per field ranged from one to six. Two phylotypes associated with the Glomus mosseae-coronatum and the G. caledonium-geosporum species complexes were the most abundant, whereas other phylotypes were infrequently found. Organic and conventional farming systems had similar number of phylotypes per field and Shannon diversity indices. A few organic and conventional fields had larger number of phylotypes, including phylotypes associated with the genera Glomus-B, Archaeospora, and Paraglomus. This suggests that farming systems as such did not influence AMF diversity, but rather specific environmental conditions or agricultural practice

    The relationship between adiposity, bone density and microarchitecture is maintained in young women irrespective of diabetes status

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    Background: The relationship between bone health and adiposity and how it may be affected in people with chronic metabolic conditions is complex. Methods: 17 women with Type 1 diabetes mellitus (T1DM) and 9 age-matched healthy women with a median age of 22.6 yrs (range, 17.4, 23.8) were studied by 3T-MRI and MR spectroscopy to assess abdominal adiposity, tibial bone microarchitecture and vertebral bone marrow adiposity. Additional measures included DXA-based assessments of total body (TB), femoral neck (FN) and lumbar spine (LS) bone mineral density (BMD) and fat mass (FM). Results: Although women with T1DM had similar BMI and bone marrow adiposity to the controls, they had higher visceral and subcutaneous adiposity on MRI (p<0.05) and total body FM by DXA (p=0.03). Overall, in the whole cohort, a clear inverse association was evident between bone marrow adiposity and BMD at all sites (p<0.05). These associations remained significant after adjusting for age, BMI, FM, and abdominal adiposity. In addition, visceral adiposity, but not subcutaneous adiposity, showed a positive association with bone marrow adiposity (r,0.4, p=0.03), and a negative association with total body BMD (r,0.5, p=0.02). Apparent trabecular separation as assessed by MRI showed an inverse association to total body BMD by DXA (r,–0.4, p=0.04). Conclusion: Irrespective of the presence of an underlying metabolic condition, young women display a negative relationship between MRI-measured bone marrow adiposity and DXA-based assessment of bone mineral density. Furthermore, an association between bone marrow adiposity and visceral adiposity supports the notion of a common origin of these two fat depots

    Laser sintered body armour – establishing single layer stab protection

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    Purpose The purpose of this research was to establish the minimum thickness required to provide stab protection in accordance with the United Kingdom Home Office Scientific Development Branch (HOSDB) standards while testing a series of Laser Sintered (LS) planar specimens using instrumented test apparatus. Design/methodology/approach Planar test specimens were Laser Sintered in single layer thicknesses ranging from 1.00 to 15.00 mm in four material powder categories – Duraform® virgin; Duraform® 50/50 mix, Duraform EX® virgin; and Duraform EX® 50/50 mix. All specimens were tested using instrumented drop test apparatus and were impacted with established Stanley Tools 1992 trimming blades to the UK HOSDB KR1-E1 stab impact energy. Findings The research demonstrated that a minimum single planar specimen thickness of 11.00 mm, manufactured from Duraform EX® 50/50 mix powder, was required to provide protection against the HOSDB KR1-E1 level of stab impact energy. The alternative powder mixes tested within this experiment demonstrated poor levels of stab protection – with virgin powder specimens demonstrating no protection up to 15.00 mm, while Duraform® 50/50 mix specimens demonstrating inconsistent performances. Originality/value This paper enhances on existing literature surrounding the manufacturing and testing of AM stab resistant armour by adding further rigor to the testing of AM body armour specimens. In addition this research establishes key foundation characteristics which could be utilised for the future development of bespoke AM body armour garments
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