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11.
12.
Kjell Henriksen 《Planetary and Space Science》1973,21(5):863-871
The part that the energy transfer reaction plays in the excitation of the auroral green line has been investigated. The contribution is estimated to be 40 per cent in this case, containing pulsating aurora in class IBC 1. Due to greater quenching of the A3∑u+ state, the centroid of the VK emission is displaced 10 km upwards of the green line height, which is centred at 110 km. 相似文献
13.
Is pure groundwater safe to drink?: natural "contamination' of groundwater in Norway 总被引:1,自引:0,他引:1
David Banks Aase Kjersti Midtgrd Geir Morland Clemens Reimann Terje Strand Kjell Bjorvatn & Ulrich Siewers 《Geology Today》1998,14(3):104-113
The title of this article is designed to provoke. Naturally occurring parameters are, by definition, not contamination. Nevertheless, nature is not necessarily nice, and naturally occurring trace toxins can be every bit as undesirable as their counterparts derived from human pollution. 相似文献
14.
A new model for gamma-ray pulsars presented by Higgins & Henriksen is applied to the cases of the seven known gamma-ray pulsars. Those pulsars that are not presently observed in gamma-rays, but are candidates for observation by the next generation of gamma-ray telescopes, are discussed. The case of millisecond pulsars is discussed, and it is shown that these objects should radiate at detectable levels, in opposition to the predictions of other gamma-ray pulsar models. 相似文献
15.
Rudolf H. Steiger Gorica Harnik-Šoptrajanova Emil Zimmermann Niels Henriksen 《Contributions to Mineralogy and Petrology》1976,57(1):1-24
Along the northern part of the East Greenland coast the Caledonian structures are superimposed on an older fold system called the Carolinidian. Traces of this Carolinidian belt are preserved in a few isolated fragments within the Caledonian fold belt. According to Haller (1970) one of these fragments exhibiting the typical Carolinidian NNW to NW-trending infrastructural folds is the peninsula of Germania Land which is accessible near the Danish weather station Danmarkshavn. The rock sampled there is a banded gneiss of granodioritic composition with steeply inclined, NNW-trending layers. Isotopic age determinations yielded essentially two groups of ages: 1) 3,000±150 m.y. (zircon suite and Rb/Sr whole rock analyses of layers) and 2) 320–380 m.y. (Rb/Sr mineral isochrons, U-Th-Pb on sphene, K/Ar on hornblende and biotite). The egg-shaped zircons support a sedimentary origin of the banded gneiss and in conjunction with the Rb/Sr whole rock ages determine the age of formation of the banded gneiss (or its last high grade metamorphism) some 3,000 m.y. ago. No other Precambrian metamorphism or orogeny is recorded in the rock. The ages between 320–380 m.y. date a thermal event of lower amphibolite facies grade related to a late Caledonian spasm.The new isotopic data reveal the existence of very old rocks in the hinterland — away from the direction of thrusting—of the East Greenland Caledonian belt. With respect to the age of the Carolinidian fold system three geological interpretations are compatible with the results of this study:
相似文献
1. | the Carolinidian fold system formed approximately 3,000 m.y. ago; |
2. | the banded gneiss represents part of an old basement: the Carolinidian orogeny is younger than 3,000 m.y. Its marked structural imprint on the Danmarkshavn area was accompanied by very low grade metamorphism not recognised in the isotopic record; |
3. | the fold structures observed in the Danmarkshavn area are not of Carolinidian age but belong to an earlier fold system preserved in the basement. |
16.
Roberto Bugiolacchi Urs Mall Susan McKenna-Lawlor Kjell Brønstad Finn Søraas Rolf B. Pedersen 《Icarus》2011,213(1):43-63
Newly acquired, sequentially spaced, high-resolution near-infrared spectra across the central section of crater Copernicus’ interior have been analyzed using a range of complementary techniques and indexes.We have developed a new interpretative method based on a multiple stage normalization process that appears to both confirm and expand on previous mineralogical estimations and mapping. In broad terms, the interpreted distribution of the principle mafic species suggests an overall composition of surface materials dominated by calcium-poor pyroxenes and minor olivine but with notable exceptions: the southern rim displays strong ca-rich pyroxene absorption features and five other locations, the uppermost northern crater wall, opposite rim sections facing the crater floor, and the central peak Pk1 and at the foot of Pk3, show instead strong olivine signatures.We also propose impact glass an alternative interpretation to the source of the weak but widespread olivine-like spectral signature found in low-reflectance samples, since it probably represents a major regolith constituent and component in large craters such as Copernicus.The high quality and performance of the SIR-2 data allows for the detection of diagnostic key mineral species even when investigating spectral samples with very subdued absorption features, confirming the intrinsic high-quality value of the returned data. 相似文献
17.
18.
Relation Between Topography and Well Yield in Boreholes in Crystalline Rocks, Sogn og Fjordane, Norway 总被引:2,自引:0,他引:2
Helge Henriksen 《Ground water》1995,33(4):635-643
19.
An exact solution of the transport equation in radiative transfer for an axially symmetric Rayleigh scattering problem in semi-infinite planetary atmosphere both for emergent intensity and intensity at any optical depth has been derived with the help of the Laplace transform and the Wiener-Hopf technique, and by use of the constancy of net flux. Chandrasekhar's results for emergent intensity have been verified. New expressions for theH
l
andH
r
functions have been obtained. 相似文献
20.
Kjell Rönnmark 《Planetary and Space Science》1975,23(9):1337-1339
Pitch-angle diffusion of ring current protons is investigated, assuming that the scattering is caused by resonant interaction with electrostatic ion loss-cone waves. Bounce averaged diffusion coefficients are presented for different wave energy distributions. It is found that wave amplitudes about 1 mV/m are required to give strong diffusion of protons with average energy. 相似文献