21,615 research outputs found

    Brown-Tail Moth, \u3ci\u3eEuproctis Chrysorrhoea,\u3c/i\u3e an Indigenous Pest of Parks and Public in the Benelux Countries (Lepidoptera: Lymantriidae)

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    Euproctis chrysorrhoea is a pest of park and shade trees and of the public in the Benelux countries as well as in the northeastern United States and Canada. In the Benelux countries the brown-tail moth is present every year in the dune regions, where it mainly feeds on Hippophae rhamnoides. Hairs from the larvae are irritating to the human skin producing a papular urticaria. An outbreak of the caterpillars produced widespread discomfort at a beach in the Netherlands in 1982 following defoliation of food plants and migration of the larvae seeking food, with resulting human contact, as well as wind dispersal of the hairs

    Dependence of field-aligned electron precipitation on season, altitude and pitch angle

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    The occurrence of field-aligned 2.3 keV electron precipitation was examined by using data from more than 7500 orbits of the polar-orbiting satellite, OGO-4. The frequency of occurrence of field aligned precipitation was highest at actual pitch angles between 7 and 10 deg, being highest in the winter months, at highest satellite altitudes. Acceleration by a localized parallel electric field established by electrostatic charge layers is proposed to explain particle observations

    The aerospace technology laboratory (a perspective, then and now)

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    The physical changes that have taken place in aerospace facilities since the Wright brothers' accomplishment 78 years ago are highlighted. For illustrative purposes some of the technical facilities and operations of the NASA Lewis Research Center are described. These simulation facilities were designed to support research and technology studies in aerospace propulsion

    Tunable cavity resonator with ramp shaped supports

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    A cavity for a hydrogen maser is described consisting of three parts which provide highly stable mechanical and thermal expansion characteristics for the cavity and ease of tuning. The three parts which are made of a glass ceramic material having a very small thermal expansion coefficient (1) a top plate, (2) a cylinder with three interrupted helical ramps at its bottom, and (3) a base which includes a bottom plate and three ramp lugs on which the helical ramps of the cylinder rest when the cylinder is placed on the base with the bottom plate in the cylinder. Cavity tuning is achieved by rotating the cylinder and thereby raising or lowering it on the base, which results in changing the cylinder volume by changing the distance between the bottom and top plates

    Analysis of plasma-nitrided steels

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    The analysis of plasma nitrided steels can be divided to two main categories - structural and chemical. Structural analysis can provide information not only on the hardening mechanisms but also on the fundamental processes involved. Chemical analysis can be used to study the kinetics for the nitriding process and its mechanisms. In this paper preliminary results obtained by several techniques of both categories are presented and the applicability of those techniques to the analysis of plasma-nitrided steels is discussed

    Sterilization of liquids by filtration and certification of probability

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    Sterilization of liquids by hydrosol filtratio

    Yield of Different Green Forage Crops, in Pure Stand and in Mixtures Part 1.: Spring (two roweed) Barley (Hordeum vulgare L.), Pea (Pisum sativum L.) and Vetch (Vicia sp. L.)

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    Green fodder crops in pure stand and in mixtures have a great potential and will have a great role in the nutrition for ruminants in Hungary. Therefore experiment was carried out to measure the born of green fodder crop production in the present situation of cattle husbandry. The experimental area was situated on the farm of the Department of Botany and Plant Production at the University of Kaposvár, Faculty of Animal Science. The type of the soil was brown forest soil with clay illuvitation. The small plot trials were carried out in four repetitions using conventional random adjustment. After the harvesting the yield of the plots were weighted and the dry matter content, crude protein yield crude fibber was determined by Weendei analysis. The chemical components of the variations were determined in two repetitions. The following species was used in the small plot trial: spring barley, pea and vetch. The highest green and dry matter yield was measured at the barley varieties in pure stand. Between the barley varieties Annabell gave the highest green, DM and crude protein yield. Spring Barley Annabell and pea Rubin in mixture gave the highest yield of crude protein

    The Production of Ti44 and Co60 in Supernova

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    The production of the radioactive isotopes 44^{44}Ti and 60^{60}Co in all types of supernovae is examined and compared to observational constraints including Galactic γ\gamma--ray surveys, measurements of the diffuse 511 keV radiation, γ\gamma--ray observations of Cas A, the late time light curve of SN 1987A, and isotopic anomalies found in silicon carbide grains in meteorites. The (revised) line flux from 44^{44}Ti decay in the Cas A supernova remnant reported by COMPTEL on the Compton Gamma-Ray Observatory is near the upper bound expected from our models. The necessary concurrent ejection of 56^{56}Ni would also imply that Cas A was a brighter supernova than previously thought unless extinction in the intervening matter was very large. Thus, if confirmed, the reported amount of 44^{44}Ti in Cas A provides very interesting constraints on both the supernova environment and its mechanism. The abundances of 44^{44}Ti and 60^{60}Co ejected by Type II supernovae are such that gamma-radiation from 44^{44}Ti decay SN 1987A could be detected by a future generation of gamma-ray telescopes and that the decay of 60^{60}Co might provide an interesting contribution to the late time light curve of SN 1987A and other Type II supernovae. To produce the solar 44^{44}Ca abundance and satisfy all the observational constraints, nature may prefer at least the occasional explosion of sub-Chandrasekhar mass white dwarfs as Type Ia supernovae. Depending on the escape fraction of positrons due to 56^{56}Co made in all kinds of Type Ia supernovae, a significant fraction of the steady state diffuse 511 keV emission may arise from the annihilation of positrons produced during the decay of 44^{44}Ti to 44^{44}Ca. The Ca and Ti isotopic anomalies in pre-solar grains confirm the production of 44^{44}Ti in supernovae and thatComment: 27 pages including 7 figures. uuencoded, compressed, postscript. in press Ap
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