Comparison of the fish assemblages associated with Posidonia oceanica after the partial loss and consequent fragmentation of the meadow     

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   

The Elusive Dust Torus of NGC 1068 Unveiled by Adaptive Optics Observations from 2.2 µm TO 4.8 µm     

D. Alloin  O. Marco 《Astrophysics and Space Science》1997,248(1-2):237-244

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   

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   

A normative ethical framework in climate change     

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   

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   

Scientific Errors in the Fearnside Comments on Greenhouse Gas Emissions (GHG) from Hydroelectric Dams and Response to His Political Claiming   总被引：1，自引：0，他引：1  

Luiz Pinguelli Rosa  Marco Aurélio Dos Santos  Bohdan Matvienko  Elizabeth Sikar  Ednaldo Oliveira Dos Santos 《Climatic change》2006,75(1-2):91-102

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Consequences of forest fires on the hydrogeological response of mountain catchments: a case study of the Riale Buffaga,Ticino, Switzerland     

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   

The Palaeocene–Middle Eocene deposits of Sardinia (Italy) and their palaeoclimatic significance     

Marco Murru  Concetta Ferrara  Stefania Da Pelo  Angelo Ibba 《Comptes Rendus Geoscience》2003,335(2):227-238

The Palaeocene of southern Sardinia includes a continental ferruginous sedimentation, with a high content of Al and Fe, indicative of a subhumid tropical climate. The subsequent microcodium carbonated detrital microcodium levels, containing an abundant quartzose fraction, rather suggest semiarid conditions. In SW Sardinia, the marine deposits, referred to Late Thanetian–Lower Ypresian (=Ilerdian) times, are limestones including larger foraminifers and contain significant amounts of quartz. A lower content of detrital kaolinite points a sediment source from the surrounding areas with a semiarid climate. The occurrence, at the top of this unit, of small trochospiral rotaliids and larger amount of detrital kaolinite suggests a transition to a rainy tropical climate in the adjacent areas. These limestones pass gradually to carbonate sediments characterized by large amounts of detrital kaolinite and intercalated coal layers, with pollen of tropical palms, attributed to the Late Ypresian (=Cuisian)–Early Lutetian and referred to a humid-subhumid tropical climate.  相似文献   

Multiwavelength monitoring of GRS 1915+105     

Bandyopadhyay  Martini  Gerard  Charles  Wagner  Shrader  Shahbaz  & Mirabel 《Monthly notices of the Royal Astronomical Society》1998,295(3):623-631

Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here first results from a multiwavelength campaign undertaken from 1996 July to September. This study includes X-ray data from the RXTE All Sky Monitor and BATSE , two-frequency data from the Nançay radio telescope, and infrared photometry from the 1.8-m Perkins telescope at Lowell Observatory. The first long-term, well-sampled infrared light curve of GRS 1915+105 is presented herein; it is consistent with the interpretation of this source as a long-period binary. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities.  相似文献   

Jadeite with the Ca-Eskola molecule from an ultra-high pressure metagranodiorite, Dora-Maira Massif, Western Alps     

Marco Bruno  Roberto Compagnoni  Takao Hirajima  Marco Rubbo 《Contributions to Mineralogy and Petrology》2002,142(5):515-519

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