2,138 research outputs found

    Effects of carbon fibers on consumer products

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    The potential effects of carbon fibers on consumer products such as dishwashers, microwave ovens, and smoke detectors were investigated. The investigation was divided into two categories to determine the potential faults and hazards that could occur if fibers should enter the electrical circuits of the selected appliances. The categories were a fault analysis and a hazard analysis. Hazards considered were fire, flood, physical harm, explosion, and electrical shock. Electrical shock was found to be a possible occurrence related to carbon fibers. Faults were considered to be any effect on the performance of an appliance which would result in complaint or require service action

    Solving the brachistochrone and other variational problems with soap films

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    We show a method to solve the problem of the brachistochrone as well as other variational problems with the help of the soap films that are formed between two suitable surfaces. We also show the interesting connection between some variational problems of dynamics, statics, optics, and elasticity.Comment: 16 pages, 11 figures. This article, except for a small correction, has been submitted to the American Journal of Physic

    Polarization--universal rejection filtering by ambichiral structures made of indefinite dielectric--magnetic materials

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    An ambichiral structure comprising sheets of an anisotropic dielectric material rejects normally incident plane waves of one circular polarization (CP) state but not of the other CP state, in its fundamental Bragg regime. However, if the same structure is made of an dielectric--magnetic material with indefinite permittivity and permeability dyadics, it may function as a polarization--universal rejection filter because two of the four planewave components of the electromagnetic field phasors in each sheet are of the positive--phase--velocity type and two are of the negative--phase--velocity type.Comment: Cleaned citations in the tex

    Equilibrium fluctuation theorems compatible with anomalous response

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    Previously, we have derived a generalization of the canonical fluctuation relation between heat capacity and energy fluctuations C=β2<δU2>C=\beta^{2}<\delta U^{2}>, which is able to describe the existence of macrostates with negative heat capacities C<0C<0. In this work, we extend our previous results for an equilibrium situation with several control parameters to account for the existence of states with anomalous values in other response functions. Our analysis leads to the derivation of three different equilibrium fluctuation theorems: the \textit{fundamental and the complementary fluctuation theorems}, which represent the generalization of two fluctuation identities already obtained in previous works, and the \textit{associated fluctuation theorem}, a result that has no counterpart in the framework of Boltzmann-Gibbs distributions. These results are applied to study the anomalous susceptibility of a ferromagnetic system, in particular, the case of 2D Ising model.Comment: Extended version of the paper published in JSTA

    The Structure of the Vortex Liquid at the Surface of a Layered Superconductor

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    A density-functional approach is used to calculate the inhomogeneous vortex density distribution in the flux liquid phase at the planar surface of a layered superconductor, where the external magnetic field is perpendicular to the superconducting layers and parallel to the surface. The interactions with image vortices are treated within a mean field approximation as a functional of the vortex density. Near the freezing transition strong vortex density fluctuations are found to persist far into the bulk liquid. We also calculate the height of the Bean-Livingston surface barrier.Comment: 8 pages, RevTeX, 2 figure

    Internet of Things of Trees - Conversational objects via SMS protocols

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    The paper describes a ‘work in progress’ to develop a system to enable users to engage with the historical and environmental story behind veteran trees in Hampstead Heath in the spirit of the Internet of Things. Unlike other ‘Internet of Trees’ projects, this study focuses on story telling rather than sensor networks. Building on previous work, conversational agents (‘chatbots’) are used as proxies for the trees to enable a two-way narrative exchange between the user and the ‘tree’. Two interaction pathways are proposed (direct SMS and web-based geofencing) and the technical development of both approaches is described, as well as ethnographic studies undertaken on Hampstead Heath to elicit engaging content for the chatbot. An initial deployment of the SMS-based interaction at Tate Exchange, a project space within Tate Modern, London is discussed and a preliminary evaluation presented

    PPAR Alpha Regulation of the Immune Response and Autoimmune Encephalomyelitis

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    PPARs are members of the steroid hormone nuclear receptor superfamily and play an important role in the regulation of lipid metabolism, energy balance, artherosclerosis and glucose control. Recent studies suggest that they play an important role in regulating inflammation. This review will focus on PPAR-α regulation of the immune response. We describe how PPAR-α regulates differentiation of T cells by transactivation and/or interaction with other transcription factors. Moreover, PPAR-α agonists have been shown to ameliorate experimental autoimmune encephalomyelitis (EAE) in mice, suggesting that they could provide a therapy for human autoimmune diseases such as multiple sclerosis

    Supercooled vortex liquid and quantitative theory of melting of the flux line lattice in type II superconductors

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    A metastable homogeneous state exists down to zero temperature in systems of repelling objects. Zero ''fluctuation temperature'' liquid state therefore serves as a (pseudo) ''fixed point'' controlling the properties of vortex liquid below and even around melting point. There exists Madelung constant for the liquid in the limit of zero temperature which is higher than that of the solid by an amount approximately equal to the latent heat of melting. This picture is supported by an exactly solvable large NN Ginzburg - Landau model in magnetic field. Based on this understanding we apply Borel - Pade resummation technique to develop a theory of the vortex liquid in type II superconductors. Applicability of the effective lowest Landau level model is discussed and corrections due to higher levels is calculated. Combined with previous quantitative description of the vortex solid the melting line is located. Magnetization, entropy and specific heat jumps along it are calculated. The magnetization of liquid is larger than that of solid by 1.8% 1.8% irrespective of the melting temperature. We compare the result with experiments on high TcT_{c} cuprates YBa2Cu3O7YBa_{2}Cu_{3}O_{7}, DyBCODyBCO, low Tc% T_{c} material (K,Ba)BiO3(K,Ba)BiO_{3} and with Monte Carlo simulations.Comment: 28 pages and 4 figures. Enlarged version of paper cond-mat/0107281 with many new content

    Public opinion on energy crops in the landscape: considerations for the expansion of renewable energy from biomass

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    Public attitudes were assessed towards two dedicated biomass crops – Miscanthus and Short Rotation Coppice (SRC), particularly regarding their visual impacts in the landscape. Results are based on responses to photographic and computer-generated images as the crops are still relatively scarce in the landscape. A questionnaire survey indicated little public concern about potential landscape aesthetics but more concern about attendant built infrastructure. Focus group meetings and interviews indicated support for biomass end uses that bring direct benefits to local communities. Questions arise as to how well the imagery used was able to portray the true nature of these tall, dense, perennial plants but based on the responses obtained and given the caveat that there was limited personal experience of the crops, it appears unlikely that wide-scale planting of biomass crops will give rise to substantial public concern in relation to their visual impact in the landscape
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