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951.
Marco Landolfi 《Solar physics》1987,109(2):287-306
We present a diagnostic method for detecting magnetic field gradients and velocity gradients in sunspots through the analysis of Stokes parameters profiles in magnetoactive lines. On one hand, the method is based on the concept of response functions for the Stokes profiles introduced by Landi Degl'Innocenti and Landi Degl'Innocenti (1977); on the other hand, it takes advantage of the diagnostic content of the residuals between observed Stokes profiles and best-fit Unno-profiles. The analysis of synthesis profiles obtained for the line 6302.502 FeI forming in the Sunspot Sunspot Model (Avrett, 1981) suggests that the method could actually be promising, at least if the dependence of the magnetic field vector on optical depth is sufficiently simple. 相似文献
952.
Marco Missana 《Astrophysics and Space Science》1979,61(2):277-286
The analysis of the Skylab measurements on the ultraviolet limb spectra confirm the presence of a generalized Compton effect in the solar spectrum which can be explained by Thomson scattering theory. The present measurements on the Orion spectrum and interstellar line towards -Arae give a large generalized Compton effect which could be explained by a resonance scattering theory. These numerical results cannot be due to random errors in the measurements, as follows from the statistical discussion. The need for further measurements is pointed out. 相似文献
953.
954.
Toms Vega Fernndez Marco Milazzo Fabio Badalamenti Giovanni D'Anna 《Estuarine, Coastal and Shelf Science》2005,65(4):645-653
An extensive Posidonia oceanica meadow was partially destroyed by excavation, resulting in areas of seagrass habitat of equal complexity (shoot density) but different heterogeneity (degree of fragmentation). The fish assemblages associated with differently fragmented beds were compared from a landscape perspective. Differences in the fish assemblages were detected, with several species showing different patterns: (1) species that increased their abundance along with the degree of bed fragmentation, (2) species that were more abundant in fragmented beds, but did not show differences between more or less fragmented beds, and (3) species that were mostly abundant in large seagrass patches or in the continuous meadow. The fish assemblages were also affected by depth, but further research is needed to determine properly this effect. Some ecological mechanisms are suggested to operate in the interaction between P. oceanica and the held fish assemblage. 相似文献
955.
Near-infrared, adaptive optics observations of AGN achieve a spatial resolution comparable to that of the Hubble Space Telescope
at visible and ultraviolet wavelengths. Using the ESO adaptive optics system, we have mapped the nuclear region of NGC 1068
in the near-infrared at 2.2, 3.5 and 4.8 μm. These data show the presence of strong near-infrared emission within the central
100 pc around the nucleus. At the K, L and M bands, the dominant emission peak is unresolved at resolutions of 35 pc (K),
15 pc (L) and 23 pc (M). We find that the emission peaks at 2.2, 3.5 and 4.8 μm are offset by 0.3±0.1" south of the HST optical
continuum peak. The infrared peaks are coincident with the HST imaging polarimetry center thought to mark the hidden nucleus.
We conclude that the infrared emission peaks are also directly related with the hidden nucleus and that they outline the dusty
torus around the central engine, as expected from current AGN models. From our first estimate of the fluxes in L and M, we
derive a dust temperature of 750 K for the unresolved component.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
956.
OH-bearing planar defects in olivine produced by the breakdown of Ti-rich humite minerals from Dabie Shan (China) 总被引:2,自引:0,他引:2
Jörg Hermann John D. Fitz Gerald Nadia Malaspina Andrew J. Berry Marco Scambelluri 《Contributions to Mineralogy and Petrology》2007,153(4):417-428
The partial breakdown of Ti-chondrodite and Ti-clinohumite during exhumation from ultra-high pressure to amphibolite facies
conditions in garnet-pyroxenites from Dabie Shan (China) produces coronas of olivine coexisting with ilmenite blebs. Fourier
transform infrared (FTIR) spectra of this newly formed olivine exhibit absorption bands in the hydroxyl-stretching region.
Two intense peaks were observed at 3,564 and 3,394 cm−1, identical in energy to peaks in Ti-clinohumite. Transmission electron microscopy (TEM) of the same olivine domains revealed
the presence of a complex (001) planar intergrowth. These interlayers have a 1.35 nm repeat distance, which is characteristic
of clinohumite. Such interlayers are also enriched in Ti with respect to the adjacent olivine as shown by energy dispersive
spectrometry. The combined evidence from FTIR spectroscopy and TEM indicates that OH is incorporated along Ti-clinohumite
planar defects. This study provides evidence that the nominally anhydrous phase olivine may contain OH as a humite-type defect
beyond the breakdown of the hydrous humite minerals and confirms earlier suggestions that Ti plays a key role in OH incorporation
in mantle olivine. We suggest that olivine containing Ti-clinohumite defects is an important phase for water transport in
subduction zones and for the storage of water in cold subcontinental mantle. However, these defects are unlikely to be stable
in hotter parts of the oceanic mantle such as where basaltic magmas are generated. 相似文献
957.
Marco Grasso 《Climatic change》2007,81(3-4):223-246
The article spells out four domains of international distributive justice and the consequent criteria of equity, the purpose
being to identify a pluralistic normative ethical framework for climate mitigation and adaptation strategies. Justice and
equity should play a major role in favouring collective action against climate change, because the more the various dimensions
of such action are just, the more any international climate initiative is feasible in principle. As far as mitigation is concerned,
the definition of a just initial allocation of endowments focuses on the criterion of differentiated equality, taking account
of undeserved inequalities as suggested by Rawls’ theory of justice as fairness. With regard to the subsequent exchange of
endowments, the Pareto principle, supplemented by the envy-freeness one, is a viable option. Possibly a sound reference for
the just financing of adaptation activities is the criterion of differentiated historical responsibility, backed by Rawls’
theory of justice as fairness. As regards the allocation of adaptation resources, the criterion of lack of human security,
as substantiated in Sen’s capability approach, seems promising. 相似文献
958.
Underground Measurements of Electromagnetic Radiation Related to Stress-induced Fractures in the Odenwald Mountains (Germany) 总被引:1,自引:0,他引:1
Marco Lichtenberger 《Pure and Applied Geophysics》2006,163(8):1661-1677
The regional stress field at Wald-Michelbach (Odenwald Mountains, Germany) induces a secondary stress field around the space
of the local railway tunnel. Resulting maximum shear stresses produce microfractures, which emit electromagnetic radiation
(EMR). From EMR measured along the cross section and the long axis of the tunnel, the regional stress field is determined
by a correlation of detected impulses per time with stresses calculated from the orientation of the tunnel, its diameter,
and topographic load. The major horizontal principal stress has an azimuth of 103°. At times, strongly alternating EMR values
are observed, which indicate electromagnetic disturbances of unknown origin. Such disturbances are identified by repeated
measurements and are not evaluated. The repeated measurements, which are not disturbed, differ with median 112 impulses per
100 ms. This difference corresponds to 0.037 MPa and indicates a good reproducibility of the results. Regional stress magnitudes
and the WNW-ESE orientation of the major horizontal principal stress indicate a minor N – S directed tensional force at the
western shoulder of the Upper Rhine Graben. 相似文献
959.
960.
Marco Conedera Larissa Peter Peter Marxer Felix Forster Dieter Rickenmann Lorenza Re 《地球表面变化过程与地形》2003,28(2):117-129
The debris flow of 28 August 1997 which occurred in the Riale Buffaga, a torrent channel in the territory of the village of Ronco s./Ascona (Ticino, Switzerland), has been simulated with a good degree of reliability due to the existence of morphologic surveys of the torrent channel preceding the flood event and the presence of a rain gauge that registered the rainfall event at a resolution of 10 minutes. With these data it is possible to conduct a quantitative analysis of the effect of a forest fire on the hydrogeological response of a given catchment. In the case at hand, a 10‐year rainfall event caused a 100‐ to 200‐year flood event. This result clearly quantifies the possible consequences of a forest fire in terms of territorial safety. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献