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21.
This paper describes a real-time spectrum analyser with on-line definition of the confidence levels built at Trieste Observatory for a research program on periodical components of unknown period in optical sources. The system is realized by a photon counting photometer on-line to a computer that elaborates in real-time the data from the photometer and displays the spectrum of the source measured. The spectrum is normalized to unity mean value and the display is calibrated by the confidence levels relative to the distribution of the spectrum displayed. Some experimental data show the performance of the machine that operates in real-time at full efficiency up to 160 Hz. Work supported by Consiglio Nazionale delle Ricerche, Gruppo Nazionale di Astronomia, Settore Tecnologie Astronomiche. Trieste Observatory — Instruments and Data Processing Group (1/76).  相似文献   
22.
The polarimetric survey of electrons in the K-corona initiated at Pic-du-Midi and Meudon Observatories in 1964 now covers a full solar cycle of activity. The measurements are photometrically calibrated in an absolute scale.In June 1967 a persistent coronal feature was fan-shaped as a lame coronale above quiescent prominences. We deduce an electron density of N 0 = 1.5 × 108 at 60 000 km above the photosphere, a total number of 14 × 1039 electrons, a hydrostatic temperature of 1.7 × 106 K, and a total thermal energy 3N eKT = 1.0 × 1031 ergs. When a center of activity appeared, a major localized condensation developed to replace the old elongated feature, with N 0 = 4.5 × 108, a total of 4.5 × 1039 electrons and the same temperature of 1.7 × 106 K.Also, a fan-shaped feature of exceptional intensity was analysed on 8 September 1966, with N 0 = 6 × 108 and a total of 24 × 1039 electrons.Fan-shaped features are frequent above quiescent prominences. They degenerate above a height of 2R into thinner isolated columns or blades with temperatures also around 1.7 × 106 K.  相似文献   
23.
The remaining core hydrogen burning lifetime after case B of mass transfer of the secondary (mass gaining) component in a medium mass close binary star is estimated, for mediummass binaries with primaries in the mass range 5M to 9M . From the comparison of this quantity with the helium burning time-scale of the remnant primary a critical mass ratioq c is derived such that for larger values ofq, mass transfer from the secondary towards the primary starts before the latter has evolved into a white dwarf. Consequences for the advanced stages of medium mass binaries are discussed.  相似文献   
24.
The Proterozoic basement of the Province of Zambezia (Mozambique) is located near the southern end of the so called Mozambique Belt. Rb-Sr data derived from the analyses of 66 whole rocks and a few mineral samples bear witness of a magmatic and metamorphic episode referable to the Kibaran (ca. 1000 Ma) and helped to model the late-Proterozoic evolution as follows. At 1100–1050 Ma a pre-orogenic, calc-alkaline magmatism was responsible for the emplacement of now deformed granite and granodiorite. This phase was accompanied by rhyolitic volcanism. A subsequent peak of deformation and metamorphism occurred at 1000-950 Ma and was associated with a second generation of substantially post-tectonic granites. A thermal event resulting in the emplacement of a final generation of granites and pegmatites can be dated to around 500-450 Ma.The metamorphic basement has not preserved its protolith age, probably as a result of extensive isotopic homogeneization of Sr in Kibaran times. Its maximum time of differentiation from the mantle should be around 1600 Ma.The very low values of initial Sr isotopic ratios suggest the absence of Archean crustal precursors and support the rather young, yet pre-Pan-African evolution of the southernmost Mozambique Belt.
Zusammenfassung Das proterozoische Grundgebirge der Provinz Zambesi (Mosambique) befindet sich in der Nähe des südlichen Endes des sogenannten Mozambique Belt. Rb/Sr Daten aus 66 Ganzgesteins- und einigen Mineralanalysen zeugen von einer magmatischen und metamorphen Episode die sich dem Kibaran (ca. 1000 Ma) zuordnen läßt, und wie sich im folgenden zeigt, hilfreich bei der Modellisierung der spätproterozoischen Entwicklung ist. Um 1100 bis 1050 Ma erfolgte ein präorogener kalkalkalischer Magmatismus, bestehend aus Graniten und Granodioriten, die heute deformiert vorliegen. Diese Phase wurde von rhyolithischem Vulkanismus begleitet. Von 1000 bis 950 Ma folgte der Höhepunkt der Deformation und Metamorphose, begleitet von einer bedeutenden 2. Generation posttektonischer Granite. Bedingt durch ein weiteres thermales Ereignis intrudierte die letzte Granit- und Pegmatitgeneration vor 500 bis 450 Ma.Im metamorphen Grundgebirge ist das Eduktalter vermutlich aufgrund der starken isotopischen Homogenisierung von Sr während der Kibara-Zeit nicht erhalten. Seine maximale Differentiationszeit vom Mantel muß vor 1600 Ma gewesen sein.Die sehr niedrigen Gehalte der initialen Sr-Isotopenverhältnisse lassen die Abwesenheit von archaischen Krustenvorläufern vermuten, und unterstützen die sehr junge, bis jetzt Prä-Pan-Afrikanische Entwicklung des südlichsten Mozambique Belts.

Résumé Le socle protérozoïque de la province du Zambèze, au Mozambique, se trouve à proximité de l'extrémité sud du «Mozambique Belt». Des mesures Rb/Sr effectuées sur 66 roches totales et sur quelques minéraux témoignent d'un épisode magmatique et métamorphique attribuable au Kibarien (environ 1.000 Ma), ce qui permet de se représenter comme suit l'histoire de cette région au Protérozoïque supérieur. Il y a 1.100 à 1.050 Ma, la région a connu une phase de magmatisme calco-alcalin qui s'est traduite par la mise en place de granites et granodiorites, aujord'hui déformés. Cette phase s'est accompagnée d'un volcanisme rhyolitique. Elle a été suivie, entre 1.000 et 950 Ma, d'une activité tectono-métamorphique majeure, à laquelle est associée une deuxième et importante génération de granites, post-tectoniques. Ultérieurement, la région a connu encore un épisode thermique, daté à 500-450 Ma, responsable de la mise en place d'une dernière génération de granite et de pegmatite.Le socle métamorphique n'a pas gardé de témoins de l'âge de son protolithe, en raison probablement de la forte homogénisation isotopique du Sr à l'époque kibarienne. Lâge maximal de sa différenciation à partir du manteau doit se situer autour de 1.600 Ma.La valeur très basse des rapports isotopiques initiaux du Sr suggère l'absence de précurseurs crustaux archéens et incite à admettre une évolution relativement jeune — bien que pré-panafricaine — du «Mozambique Belt» méridional.

() .. . , Rb/Sr 66 , , Kibara, 1000 , , , . 1100 1050 - - , , . . 1000 950 , - . , 500 450 . , , , Kibara. , , 1600 my . - .
  相似文献   
25.
The results of evolutionary computations for massive binary systems (initial masses of the primary 10M ) with mass ratios between 0.3 and 0.8 are summarized and compared with observations in order to verify how far one can go with the conservative assumption of mass exchange. It is found that conservative mass exchange leads to acceptable first-order models of W-R and massive X-ray binaries. However, the comparison between this theory and observation reveals that for the observed systems (W-R and X-ray binaries) a preference exists for low intial mass ratios; moreover, the X-ray luminosities of the theoretical models are systematically too low, though this may be due to the adopted wind model. In addition, the influences of several parameters (distance between the components, chemical composition, primary mass, mass ratio and atmosphere) are examined. These parameters influence the remnant mass and any further evolution only marginally. Attention is also given to the effect on the system parameters of a supernova explosion of the remnant of the mass-losing component. For a large range of systems a disruption probability smaller than 25% is found.  相似文献   
26.
Careful measurements of rest potentials of platinum electrodes (Eh) in the H2S-H2O system were made together with measurements of the pH and the potentials of Ag-Ag2S electrodes (Es2?). The potentials of the platinum electrode are characteristic of H2S chemisorption followed by H2S discharge on the platinum. The relations between Eh, Es2? and pH are characteristic of the H2S-H2O system and of the hydrogen sulfide concentration. Thus these parameters can be employed to distinguish H2S-H2O systems from H2S-S8-H2O systems. Field measurements on hot sulfurous springs are in agreement with laboratory data.  相似文献   
27.
This study concerns a core collected in Brejo do Espinho's lagoon from Cabo Frio littoral (Brazil) submitted to dry influence of local upwelling controlled by north-east trade winds from the South Atlantic and particularly strengthened during El Niño events. Diatoms study supported by sedimentological and isotopic analyses shows dry phases infrequent before 4000 yr, a highly variable climatic phase between 3600 and 2900 yr and from 2400 yr onward a dryness enhancement. To cite this article: B. Laslandes et al., C. R. Geoscience 338 (2006).  相似文献   
28.
The implementation of the Water Framework Directive (EU 2000) requires a groundwater quality monitoring. It is used for characterisation of the ‘good’ chemical status of each groundwater body and for the restoration or protection purposes of those bodies already at ‘good’ status. Interpretative aspects are lying in the design of monitoring network and in the way of building global indicators. Attention is given here to the global chemical status of the groundwater bodies and to the role of diffuse pollution, much of which is brought via groundwater to surface water. Monitoring ‘local’ pollution associated with individual sites is not addressed. Groundwater bodies with different contrasted hydrogeology conditions, land use and topography have been considered to establish an approach for choosing an optimised monitoring network. Then, a quality assessment system has been developed and applied for qualifying the general status of each groundwater body. The use of non-dimensional indexes allows us to process with all kinds of chemical parameters in a normalised way and, by means of adequate aggregation rules, to qualify the general quality status of a groundwater body. The obtained diagnostic, even if not fully validated, is closely linked to the pragmatic objectives contained in the EU Water Directive.  相似文献   
29.
CO2 inclusions with density up to 1,197 kg m−3 occur in quartz–stibnite veins hosted in the low-grade Palaeozoic basement of the Gemericum tectonic unit in the Western Carpathians. Raman microanalysis corroborated CO2 as dominant gas species accompanied by small amounts of nitrogen (<7.3 mol%) and methane (<2.5 mol%). The superdense CO2 phase exsolved from an aqueous bulk fluid at temperatures of 183–237°C and pressures between 1.6 and 3.5 kbar, possibly up to 4.5 kbar. Low thermal gradients (∼12–13°C km−1) and the CO2–CH4–N2 fluid composition rule out a genetic link with the subjacent Permian granites and indicate an external, either metamorphogenic (oxidation of siderite, dedolomitization) or lower crustal/mantle, source of the ore-forming fluids.According to microprobe U–Pb–Th dating of monazite, the stibnite-bearing veins formed during early Cretaceous thrusting of the Gemeric basement over the adjacent Veporic unit. The 15- to 18-km depth of burial estimated from the fluid inclusion trapping PT parameters indicates a 8- to 11-km-thick Upper Palaeozoic–Jurassic accretionary complex overlying the Gemeric basement and its Permo-Triassic autochthonous cover.  相似文献   
30.
A multicriteria approach in studying hydrodynamics of a multilayer aquifer system has been used in the Lomellina region (Northern Italy). It involves the reconstruction of the hydrogeological framework coupled to the definition of the hydrochemical and isotopic features of the aquifers. A shallow phreatic aquifer, reaching depths of about 60–80 m from the surface, and deeper aquifers containing confined groundwater, were distinguished. Groundwater generally shows mineralisation decreasing with depth; dissolved ions depict calcium-bicarbonate hydrochemical facies and stable isotopes define the recharge mechanisms, the origin of groundwater, and the hydraulic confinement of deep aquifers. The phreatic aquifer is fed by local infiltration and by streams and irrigation channels. Tritium and Carbon-14 groundwater dating indicate long residence times (on the order of thousands of years) for confined aquifers. The confined aquifers show essentially passive hydrodynamic conditions and maintain a higher piezometric level than the phreatic aquifer. This inhibits the possibility of recent water penetrating far below the surface. The hydrogeological setting of the Lomellina region displays features which are common to other sectors of the Po plain. As a consequence, the results of this study, although conducted on a restricted area, are highly illustrative of groundwater hydrodynamics in large sedimentary aquifers.  相似文献   
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