875 research outputs found

    Phosphoinositide hydrolysis mediated by H1 receptors in autoimmune myocarditis mice

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    Stimulation of phosphoinositide hydrolysis in myocardium from autoimmune myocarditis mice by ThEA and histamine was assayed. Myocardium from autoimmune heart, but not the normal forms, specifically increased phosphoinositide turnover in the presence of histaminergic agonists. This increment was blocked by a specific H1 antagonist mepyramine and to the same extent by the phospholipase C inhibitor NCDC. By using a binding assay H1 histaminergic receptors were detected in autoimmune heart membrane preparations, but this was not observed in normal heart. These data suggest that autoimmune myocardium expressed a functional H1 receptor that could involve a distinctive mechanism operating in the disease

    Museum Websites of the First Wave: The rise of the virtual museum

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    In this paper, we analyse trends of the first wave of museum websites (from the 1990s to the early 2000s) to understand how the characteristics of the Internet (specifically the World Wide Web), of museum staff, and museum audiences shaped the adoption of technology and new forms of participation and what they can tell us about engagement for museums of the future. The early development of online museum resources parallels the development of the EVA conference, which was establishing itself at a similar time

    Early virtual science museums: when the technology is not mature

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    This paper discusses three case studies of early science museum-related websites in the 1990s and early 2000s, when web technology was still relatively new and evolving. The Virtual Museum of Computing (VMoC) was a completely virtual museum, originally produced in 1995 as part of the Virtual Library museums pages (VLmp), an international online museum directory within the WWW Virtual Library, adopted by the International Council of Museums (ICOM). The Science Museum in London was one of the first museums in the United Kingdom to have its own web server. The museum hosted an early meeting on web service provision by and for museums, concurrently with an exhibition on the Information Superhighway at the museum in 1995. Exhiblets were launched online in 1998. Ingenious was a multi-site digital collections transformation project, launched as a website in 2003. Virtual Leonardo and Leonardo’s Ideal City were two experiments conducted by the digital team of the Science and Technology Museum of Milan, between 1999 and 2001. The experiment consisted of the creation of a shared online 3D world, namely a reconstruction of the real museum in the first case and a completely imaginary world in the second case. This paper describes the above three case studies from the early World Wide Web and then draws some conclusions, from first-hand experience of developments at the time. We cover both the advantages and the challenges encountered by the various projects and illustrate why they did not necessarily become established, despite promising early results

    Cholinoceptor Activation Subserving the Effects of Interferon Gamma on the Contractility of Rat Ileum

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    Recombinant rat interferon γ stimulated the contractility of isolated rat ileum at doses of 4–12 units/ml. Muscarinic cholinoceptors were involved, as treatment of the tissue with atropine prevented the contractile response of the ileum. Furthermore, interferon γ increased the affinity of carbachol for the cholinoceptors and did not change its maximum effect. Neurogenic pathways were also involved since pretreatment of ileum with hexamethonium, hemicholinium or tetrodotoxin impaired the contractile effect of interferon γ. In contrast to the action of exogenous carbachol, the effects of interferon γ are indirect. They appear to involve a G protein regulating phosphoinositide turnover and cytoskeletal structures since they could not be induced in ileum strips that were pretreated with pertussis toxin, phospholipase C inhibitors (2-nitro-carboxyphenyl, NN-diphenyl carbamate and neomycin), cytochalasine B or colchicine

    Homogeneous and Narrow Bandwidth of Spike Initiation in Rat L1 Cortical Interneurons

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    The cortical layer 1 (L1) contains a population of GABAergic interneurons, considered a key component of information integration, processing, and relaying in neocortical networks. In fact, L1 interneurons combine top\u2013down information with feed-forward sensory inputs in layer 2/3 and 5 pyramidal cells (PCs), while filtering their incoming signals. Despite the importance of L1 for network emerging phenomena, little is known on the dynamics of the spike initiation and the encoding properties of its neurons. Using acute brain tissue slices from the rat neocortex, combined with the analysis of an existing database of model neurons, we investigated the dynamical transfer properties of these cells by sampling an entire population of known \u201celectrical classes\u201d and comparing experiments and model predictions. We found the bandwidth of spike initiation to be significantly narrower than in L2/3 and 5 PCs, with values below 100 cycle/s, but without significant heterogeneity in the cell response properties across distinct electrical types. The upper limit of the neuronal bandwidth was significantly correlated to the mean firing rate, as anticipated from theoretical studies but not reported for PCs. At high spectral frequencies, the magnitude of the neuronal response attenuated as a power-law, with an exponent significantly smaller than what was reported for pyramidal neurons and reminiscent of the dynamics of a \u201cleaky\u201d integrate-and-fire model of spike initiation. Finally, most of our in vitro results matched quantitatively the numerical simulations of the models as a further contribution to independently validate the models against novel experimental data

    A renormalization-group analysis of the interacting resonant level model at finite bias: Generic analytic study of static properties and quench dynamics

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    Using a real-time renormalization group method we study the minimal model of a quantum dot dominated by charge fluctuations, the two-lead interacting resonant level model, at finite bias voltage. We develop a set of RG equations to treat the case of weak and strong charge fluctuations, together with the determination of power-law exponents up to second order in the Coulomb interaction. We derive analytic expressions for the charge susceptibility, the steady-state current and the conductance in the situation of arbitrary system parameters, in particular away from the particle-hole symmetric point and for asymmetric Coulomb interactions. In the generic asymmetric situation we find that power laws can be observed for the current only as function of the level position (gate voltage) but not as function of the voltage. Furthermore, we study the quench dynamics after a sudden switch-on of the level-lead couplings. The time evolution of the dot occupation and current is governed by exponential relaxation accompanied by voltage-dependent oscillations and characteristic algebraic decay.Comment: 24 pages, 13 figures; revised versio

    Assisted hopping and interaction effects in impurity models

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    We study, using Numerical Renormalization Group methods, the generalization of the Anderson impurity model where the hopping depends on the filling of the impurity. We show that the model, for sufficiently large values of the assisted hopping term, shows a regime where local pairing correlations are enhanced. These correlations involve pairs fluctuating between on site and nearest neighbor positions

    Forest fire management using machine learning techniques

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    As per the latest survey produced by the Forest Survey, the forest cover is 19.27% of the geographic area. According to this report every country can meet the human needs of 16% of the world’s population from the 1% of the world’s forest resource. The Forest Survey said that 90% of the forest fires created by humans. They pose a threat not only to the forest wealth but also this leads to the main threat to biodiversity, a change in the ecosystem. The environment gets dry and twinges, which leads to produce flames in the forest. There are two types of forest fire i) Surface Fire and ii) Crown Fire iii) Ground Fire. Surface Fire: The forest fire starts its flame primarily as a surface fire, spreading along the ground with the help of dry grasses and so on. Crown Fire: It starts flame on the crown of the shrubs, bushes and trees and sustained on the surface. This type of fire is very dangerous because resinous material given off burning logs burn furiously. If there is a slope with fire then the fire spread from the top of the slope to the down. Ground fire occurs in the humus and peaty layers beneath the litter of under composed portion of forest floor with intense heat but practically no flame. Such fires are relatively rare and have been recorded occasionally at high altitudes in Himalayan fir and spruce forests. In Remote sensing field, the knowledge of surface temperature plays a vital role. By using brightness and emissivity feature, temperature mapping and analysis can be done. The surface temperature values are measured to detect the forest fire from the ASTER image. ASTER stands for Advanced Space borne Thermal Emission and Reflection Radiometer. ASTER image contains 5 thermal bands (wave length ranges from 8.125 μm to 11.65 μm) and these are used in comparison. To convert digital numbers to exoatmospheric radiance, ASTER thermal bands are used. The converted exoatmospheric radiance is then mapped into surface radiance using the Emissivity Normalization method

    Kondo quantum dot coupled to ferromagnetic leads: Numerical renormalization group study

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    We systematically study the influence of ferromagnetic leads on the Kondo resonance in a quantum dot tuned to the local moment regime. We employ Wilson's numerical renormalization group method, extended to handle leads with a spin asymmetric density of states, to identify the effects of (i) a finite spin polarization in the leads (at the Fermi-surface), (ii) a Stoner splitting in the bands (governed by the band edges) and (iii) an arbitrary shape of the leads density of states. For a generic lead density of states the quantum dot favors being occupied by a particular spin-species due to exchange interaction with ferromagnetic leads leading to a suppression and splitting of the Kondo resonance. The application of a magnetic field can compensate this asymmetry restoring the Kondo effect. We study both the gate-voltage dependence (for a fixed band structure in the leads) and the spin polarization dependence (for fixed gate voltage) of this compensation field for various types of bands. Interestingly, we find that the full recovery of the Kondo resonance of a quantum dot in presence of leads with an energy dependent density of states is not only possible by an appropriately tuned external magnetic field but also via an appropriately tuned gate voltage. For flat bands simple formulas for the splitting of the local level as a function of the spin polarization and gate voltage are given.Comment: 18 pages, 18 figures, accepted for publication in PR
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