1,977 research outputs found

    Bremsstrahlung Pair Production In Relativistic Heavy Ion Collision

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    We calculate production of electron- and muon-pairs by the bremsstrahlung process in hadron collisions and compare it with the dominant two-photon process. Results for the total cross section are given for proton-proton and heavy-ion collisions at energies of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).Comment: 6 pages, Latex, 9 figures using epsf-style. Accepted for publication in Z. Phys.

    Mechanisms for Direct Breakup Reactions

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    We review some simple mechanisms of breakup in nuclear reactions. We mention the spectator breakup, which is described in the post-form DWBA. The relation to other formulations is also indicated. An especially important mechanism is Coulomb dissociation. It is a distinct advantage that the perturbation due to the electric field of the nucleus is exactly known. Therefore firm conclusions can be drawn from such measurements. Some new applications of Coulomb dissociation for nuclear astrophysics are discussed.Comment: 17 pages, 5 figures, to appear in the proceedings of the RCNP-TMU Symposium on Spins in Nuclear and Hadronic Reactions, October 16-18 199

    Electromagnetic Dissociation as a Tool for Nuclear Structure and Astrophysics

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    Coulomb dissociation is an especially simple and important reaction mechanism. Since the perturbation due to the electric field of the nucleus is exactly known, firm conclusions can be drawn from such measurements. Electromagnetic matrix elements and astrophysical S-factors for radiative capture processes can be extracted from experiments. We describe the basic theory, new results concerning higher order effects in the dissociation of neutron halo nuclei, and briefly review the experimental results obtained up to now. Some new applications of Coulomb dissociation for nuclear astrophysics and nuclear structure physics are discussed.Comment: 10 pages, 1 figure, to appear in Proceedings of the International School on Nuclear Physics; 22nd Course: ``Radioactive Beams for Nuclear and Astro Physics'', Erice/Sicily/Italy, September 16 - 24, 200

    Control of the woolly apple aphid (Erisoma lanigerum Hausm.) by releasing earwigs (Forficula auricularia L.) and support oil applications - an interim report of first year results

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    The woolly apple aphid (Erisoma lanigerum Hausm.) has been recognised for some years as a serious pest in organic fruit growing where they may cause severe economic damage due to a lack of control strategies. Based on preliminary results a new project has been started in 2007 testing combinations of releasing earwigs and oil applications in order to develop an onfarm control strategy. In this paper we present preliminary results of the first year of the project´s field trials. They showed good efficacies for applying oil preparations by brush. The efficacy of releasing earwigs depended on the infestation intensity

    Work Roll Cooling System Design Optimisation in Presence of Uncertainty

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    Organised by: Cranfield UniversityThe paper presents a framework to optimise the design of work roll based on the cooling performance. The framework develops Meta models from a set of Finite Element Analysis (FEA) of the roll cooling. A design of experiment technique is used to identify the FEA runs. The research also identifies sources of uncertainties in the design process. A robust evolutionary multi-objective algorithm is applied to the design optimisation I order to identify a set of good solutions in the presence of uncertainties both in the decision and objective spaces.Mori Seiki – The Machine Tool Compan

    Características citológicas del lavado bronqueoalveolar y respuesta inmune humoral frente a Aspergillus fumigatus en caballos Chilotes con obstrucción recurrente de las vías aéreas

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    In this study, the presence and characteristics of the recurrent airway obstruction (RAO), in Chilote horses were investigated. The Chilote horse is a breed of small and very rustic horses, descendent from, the horses that were brought by the Spaniards during the colony and remained isolated in. the Chiloe island, south of Chile, for a long time. Twenty two animals, all from the same farm and living under similar conditions, were physically examined. In all cases broncheoalveolar lavage (BALF) was performed and the recovered resident cells from the respiratory tract were studied in smears stained with May Grewald - Giemsa; the level of antibodies against Aspergillus fumigatus was determined by ELISA. The results indicate that out of the total population of animals under investigation, 13 showed clinical signs compatible with RAO and 9 were normal. In all cases, the animals that were considered RAO positive showed a higher percentage of polymorphonuclear neutrophils in the BALF: furthermore, a clear positive correlation between the relative amount of neutrophilic cells present in the airways and the severity of the signs observed during the physical examination exists. All of the animals, healthy and RAO positive horses, showed high titres of antibodies against A. fumigatus, a well known allergen, commonly distributed in. the region and present in the hay/straw. Our results show that Chilote horses, even though they are a rustic bread, are very susceptible to become RAO positive with similar characteristics to those described in other breeds, moreover, all animals were sensitized to A. fumigatus antigens showing the immunogenicity and the important distribution of this fungal allergen.El objetivo de este estudio fue analizar las características citológicas del lavado bronquealveolar (LBA) y la respuesta inmune humoral en caballos Chilote con obstrucción recurrente de las vías aéreas (ORVA) contra Aspergillus fumigatus y su rol en la inducción de este cuadro alérgico. Para esto, se utilizaron 22 caballos Chilote, de los cuales 13 presentaban ORVA y 9 estaban clínicamente sanos, los cuales fueron utilizados como controles. A todos los animales se les realizó un examen físico, se les evaluó la citología pulmonar mediante un lavado bronqueoalveolar (LBA) y se les extrajo suero sanguíneo, con el propósito de determinar anticuerpos específicos contra Aspergillus fumigatus a través de un ELISA indirecto. Los resultados obtenidos de los extendidos celulares hechos a partir del LBA muestran que el porcentaje relativo de neutrófilos encontrados en los caballos con ORVA era concordante con los hallazgos obtenidos en el examen clínico. Con respecto a la prueba de ELISA se determinó que todos los animales, incluidos los controles, tenían niveles similares de anticuerpos específicos contra Aspergillus fumigatus no existiendo diferencias entre los individuos con ORVA y el grupo de animales sanos (P > 0,05). Se puede concluir que los caballos Chilote, al igual que las otras razas de caballo, tienen la predisposición de hacer ORVA al estar sensibilizados con los alérgenos inductores de este cuadro alérgico pulmonar y que existe concordancia entre el porcentaje de neutrófilos encontrados en el LBA y la gravedad de los síntomas clínicos de estos animales. Además, los antígenos de Aspergillus fumigatus tienen un rol importante en la inducción de ORVA en esta específica raza de caballo

    Electrical conduction of ion tracks in tetrahedral amorphous carbon: temperature, field and doping dependence and comparison with matrix data

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    This paper gives an extended overview of the electrical properties of ion tracks in hydrogen-free tetrahedral amorphous carbon (ta-C) with a sp(3) bond fraction of about 80%. The films were grown by mass selected ion beam deposition of 100 eV C-12(+) ions. The ion tracks are generated by irradiation of ta-C films with uranium ions of 1 GeV kinetic energy. Along the ion path a conversion from diamondlike (sp(3)) carbon to graphite-like (sp(2)) carbon takes place. Topography and current measurements of individual ion tracks were performed by atomic force microscopy at ambient temperature. The temperature dependence of the electric conductivity was studied between 15 and 390 K by means of 0.28 mm(2) large contact pads averaging over about 10 7 tracks. For each sample and at each temperature the conductivity as a function of the applied electrical field (non-ohmic behaviour) was measured separately and the data were extrapolated to field zero. In this way, the zero-field conductivity was determined independent from the field dependence. In spite of large differences in the absolute values, the temperature dependence of the zero-field conductivities is found to be very similar in shape for all samples. The conductivities follow a T-1/4 law up to temperatures slightly below room temperature. At higher temperatures a transport mechanism based on over-barrier hopping dominates with an activation energy of about 220 meV for tracks and 260 meV for the ta-C matrix. The field dependence measurements show that the deviation of the I-V characteristics from ohmic behaviour decreases with increasing zero-field conductivity. We also tested Cu-doped ta-C samples and found that they conduct significantly better than pure ta-C. However, the doping also increases the zero-field conductivity resulting in a weaker contrast between the track and matrix. The data are interpreted within the so-called 'barrier model' where the electrons are assumed to move fairly freely in well-conducting sp(2) regions but encounter barriers in track sections consisting of more sp(3)-like bonds
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