979 resultados para 43-387


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There is, in nature, as well as in the aquarium, a parasitic disease known as 'mousse' and which attacks predominantly fish. It is caused by Phycomycete fungi, genus Saprolegnia. The fungus causes external lesions and covers the fish with a thick white layer from whence comes the name 'mousse', commonly attributed to the disease, for which the scientific name is Saprolegnia. This article provides an overview of Saprolegnia infections on fish in nature and aquaria and then discusses symptomology of Saprolegnia in the mirror caro and t roach in more detail.

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With the aid of the German Research Association in the central programme 'Sand movements in the German coastal region', an investigation into the current conditions in the shallow water areas of the coasts of the south-eastern North Sea between Sylt and the Weser estuary was carried out by the author. Foundations of the work are 19 continuous current recordings in five profiles normal to the coast from years 1971 to 1973. Off the coasts of the south-eastern North Sea varying tidal currents impinge; they are currents whose directions may vary periodically through all points of the compass. They are caused by the circulating tides in the North Sea (Amphidromien). The turning flow movement experiences a deformation in the very shallow coastal waters, and as it happens the flow turning movement in the case of high tide continues right up onto the outer flats, while here and in the fore-lying shallow water areas around the time of low water (on account of the small depths of waters), there prevails a more variable current. A result of this hydrodynamical procedure is the development of counter currents. This partial translation of the original paper provides the summary of this study of of the mudflat areas between the Elbe and Weser.

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The 1.7- and 2.43-MeV levels in 9Be were populated with the reaction 11B(d, α)9Be* by bombarding thin boron on carbon foils with 1.7-MeV deuterons. The alpha particles were analyzed in energy with a surface-barrier counter set at the unique kinematically determined angle and the recoiling 9Be nuclei at 90o were analyzed in rigidity with a magnetic spectrometer, in energy by a surface-barrier counter at the spectrometer focus, and in velocity by the time delay between an alpha and a 9Be count. When a pulse from the spectrometer counter was in the appropriate delayed coincidence with a pulse from the alpha counter, the two pulses were recorded in a two-dimensional pulse height analyzer. Most of the 9Be* decay by particle breakup. Only those that gamma decay are detected by the spectrometer counter. Thus the experiment provides a direct measurement of Γrad/Γ. Analysis of 384 observed events gives Γrad/Γ = (1.16 ± 0.14) X 10-4 for the 2.43-MeV level. Combining this ratio with the value of Γrad = 0.122 ± 0.015 eV found from inelastic electron scattering gives Γ = (1.05 ± 0.18) keV. For the 1.7-MeV level, an upper limit, Γrad/Γ ≤ 2.4 = 10-5, was determined.

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Since 1974 we have been collecting statistics on the main fishing gears in the ivorian lagoons. In order to get good estimation of the catches, it is often more convenient to measure the fishes and to convert this data into weights through a length-weight relationship. In this work we computed this relation for 43 species found in the Aby and Ebrié lagoons.

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South Africa- Shifting livelihoods, Viet Nam-Strengthening livelihoods, Chile - gains and challenges, Uganda- making changes possible, Maritza Mena from Costa Rica, Ground-breaking gender indicators, You tube resources

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The damage removal and strain relaxation in the As+-implanted Si0.57Ge0.43 epilayers were studied by double-crystal x-ray diffractometry and transmission electron microscopy. The results presented in this paper indicate that rapid thermal annealing at temperatures higher than 950 degrees C results in complete removal of irradiation damage accompained by the formation of GeAs precipitates which enhance the removal process of dislocations.

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中、低纬度地区山地冰川有机酸记录的研究是目前国际冰芯地球化学研究的前沿之一。中国天山乌鲁木齐河源一号冰川为一中纬度山地冰川。对其冰芯的草酸根含量的分析显示,其冰芯所记录的过去43年草酸根变化的总体特征是在一个背景值基础上存在着含量的突变峰值。草酸根的背景值含量在1ng/g左右,在部分冰芯段,其含量甚至低于测试分析的检测限;而大多数草酸根峰值的含量都达到或超过了10ng/g。草酸根的平均含量为3.6±9.2ng/g(x^-±1σ,N=534),其中70%以上由峰值构成。50年代后期是草酸根的一个低值期,平均含量略高于本底值;至60-70年代达到最高值,平均含量为5.0ng/g;80年代草酸根平均含量又下降到接近50年代后期的水平;至90年代回落到本底值附近。草酸根的主要来源是人类活动对大气所造成的污染。其过去43年平均含量的变化大致与中国西部工业和环境保护事业的发展历程相一致,是西部区域大气污染变化的一种反应。