1,488 research outputs found

    Reaction cross-section predictions for nucleon induced reactions

    Full text link
    A microscopic calculation of the optical potential for nucleon-nucleus scattering has been performed by explicitly coupling the elastic channel to all the particle-hole (p-h) excitation states in the target and to all relevant pickup channels. These p-h states may be regarded as doorway states through which the flux flows to more complicated configurations, and to long-lived compound nucleus resonances. We calculated the reaction cross sections for the nucleon induced reactions on the targets 40,48^{40,48}Ca, 58^{58}Ni, 90^{90}Zr and 144^{144}Sm using the QRPA description of target excitations, coupling to all inelastic open channels, and coupling to all transfer channels corresponding to the formation of a deuteron. The results of such calculations were compared to predictions of a well-established optical potential and with experimental data, reaching very good agreement. The inclusion of couplings to pickup channels were an important contribution to the absorption. For the first time, calculations of excitations account for all of the observed reaction cross-sections, at least for incident energies above 10 MeV.Comment: 6 pages, 6 figures. Submitted to INPC 2010 Conference Proceeding

    A study on elasto-plastic impact friction

    Get PDF
    A purpose-built pendulum machine was used to study the oblique impact and the behaviour of the surface layers of a normalized low alloy steel subjected to the impact of hard [alpha]-alumina balls. The effect of relative tangential velocity on impulses, restitution coefficient and impact energy loss, was analysed. The morphology of the impact indentations was characterized and related to the impulses obtained. There was lip formation in the target material with ejection of a small fragile oxidized chip, at a certain critical sliding speed. The impact duration and the impulse ratio have maximum values. These values seem to be related to the critical angle of attack, common in abrasive and erosive ductile processes. The experimental results were compared with some impact models and theories.http://www.sciencedirect.com/science/article/B6V5B-3WRC3G0-4/1/41e4c5269f22928dae6bfa3fb640fd0

    Statics and dynamics of an Ashkin-Teller neural network with low loading

    Full text link
    An Ashkin-Teller neural network, allowing for two types of neurons is considered in the case of low loading as a function of the strength of the respective couplings between these neurons. The storage and retrieval of embedded patterns built from the two types of neurons, with different degrees of (in)dependence is studied. In particular, thermodynamic properties including the existence and stability of Mattis states are discussed. Furthermore, the dynamic behaviour is examined by deriving flow equations for the macroscopic overlap. It is found that for linked patterns the model shows better retrieval properties than a corresponding Hopfield model.Comment: 20 pages, 6 figures, Latex with postscript figures in one tar.gz fil

    On the width of the last scattering surface

    Full text link
    We discuss the physical effects of some accelerated world models on the width of the last scattering surface (LSS) of the cosmic microwave background radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and a Chaplygin type gas. The redshift of the LSS does not depend on the kind of dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of the LSS is also only weakly dependent on the kind of scenario (if we have dark energy plus cold dark matter or the unified picture).Comment: 10 pages, 1 figure, 2 tables, accepted to IJMP

    Enhancement of the ferromagnetic order of graphite after sulphuric acid treatment

    Full text link
    We have studied the changes in the ferromagnetic behavior of graphite powder and graphite flakes after treatment with diluted sulphuric acid. We show that this kind of acid treatment enhances substantially the ferromagnetic magnetization of virgin graphite micrometer size powder as well as in graphite flakes. The anisotropic magnetoresistance (AMR) amplitude at 300 K measured in a micrometer size thin graphite flake after acid treatment reaches values comparable to polycrystalline cobalt.Comment: 3.2 pages, 4 figure

    Integrated system for macroalgae production and conversion into biogas

    Get PDF
    Recently research on energy from macroalgae is being reconsidered driven by the following factors: fuel price increase, CO2 mitigation policies and interest on renewable energy sources after the Kyoto protocol, and need for energy crops not competing with land for food production. However, the commercial expansion of this energy source is limited by its economic feasibility. In this presentation we analyse the development of integrated systems that promote synergies between macroalgae/biogas production and activities such as aquaculture and urban wastewater treatment. The recycling of nutrients and CO2 by macroalgae can be an opportunity to reduce the biomass-biogas production cost. Other advantage is the proximity between biomass production, conversion into energy and its consumption, thus avoiding energy losses and pollution in transportation. Experimental work is underway and includes batch tests to evaluate biodegradability of Ulva spp. and Gracilaria sp. and co-digestion of these macroalgae with sewage sludge from Beirolas wastewater treatment plant (WWTP). Furthermore, continuous co-digestion experiments are planned to be carried out in a 30 L experimental reactor to be placed in the same WWTP. The objectives are to reproduce sludge digestion in Beirolas WWTP and evaluate algae/sludge co-digestion performance. Preliminary results indicate methane yields in accordance with similar batch experiments, whereby our CH4 yields per volatile solids added range between 0.14-0.20 m3 CH4 kg-1 VSadded against 0.16-0.27 m3 CH4 kg-1 VSadded [1,2] depending on the algae species and pretreatment. Overall, Ulva sp. shows a better performance over Gracilaria sp. as also confirmed in other experiments [1]

    Disfagia e Disartria. Forma Invulgar de Apresentação da Miastenia Gravis

    Get PDF
    Myasthenia Gravis is an autoimmune disorder that generally presents with ocular symptoms, specially diplopia and ptosis. Dysphagia may be a manifestation of the generalised type of the disease, but rarely is its presenting feature. The authors describe a case of Myasthenia Gravis in an old patient complaining of dysphagia and dysarthria. Because Myasthenia Gravis is a potentially serious but treatable disease, we emphasize the need to consider it in the differential diagnosis of dysphagia, namely in the elderly. In fact, the disorder is probably underdiagnosed in this population group, because clinicians tend to accept other more frequent diagnosis to explain these symptoms

    Influence of body odors and gender on perceived genital arousal

    Get PDF
    Olfaction is often linked to mating behavior in nonhumans. Additionally, studies in mating behavior have shown that women seem to be more affected by odor cues than men. However, the relationship between odor cues and sexual response—specifically, sexual arousal—has not been studied yet. The aim of this study was to evaluate the impact of the exposure to human body odors (from individuals of the opposite gender) on perceived genital arousal, while these were presented concomitantly to sexually explicit video clips. Eighty university students (40 women) rated their perceived genital arousal (perceived degree of erection/genital lubrication) in response to an audiovisual sexual stimulus, while simultaneously exposed to a body odor from an opposite-gender donor or no odor. Participants also rated each odor sample’s (body odor and no odor) perceived pleasantness, intensity, and familiarity. Findings indicated that odor condition had an effect on women’s (but not men’s) perceived genital arousal, with women showing higher levels of perceived genital arousal in the no odor condition. Also, results showed that women rated body odors as less pleasant than no odor. Notwithstanding, the odor ratings do not seem to explain the association between body odor and perceived genital arousal. The current results support the hypothesis that women, rather than men, are sensitive to odors in the context of sexual response. The findings of this study have relevance for the understanding of human sexuality with respect to chemosensory communicationinfo:eu-repo/semantics/acceptedVersio

    Exploring the relationship between ethical and sustainable consumption in short supply chains: A literature review

    Get PDF
    Sustainable development, sustainable consumption and short supply chains are nowadays acquiring increasing relevance in the literature. On the other hand, from the consumer's attitudinal statement, ethical consumption is also requiring more attention from marketing sciences. Besides that, the integration of the last concept on sustainability remains in a complete lack of systematic and integrative conceptualization. This paper tries to promote a potential integration of all the dimensions of sustainable consumption and to understand the potential linkage and interaction among them, in order to promote the Sustainable Development Goal 15 from the United Nations. The methodology follows a systematic literature review and preliminary information comes from a case study of the approved project SDGsConsum. The results confirm that, besides a huge development in sustainable development and sustainable consumption in the literature, the focus on shortly supply chains of production is yet modest. Moreover, the motivations and constraints that drive and restrain, respectively, consumers toward ethical and sustainable consumption presents several incongruences.info:eu-repo/semantics/acceptedVersio
    • …
    corecore