Long-term study of at-sea distribution of seabirds and marine mammals in the Scotia Sea,Antarctica     

Jos Luis Orgeira  Mariela del Carmen Alderete  Yohana Gisell Jimnez  Juan Cruz Gonzlez 《极地研究(英文版)》2015,(2)

The Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on ...  相似文献   

Introduced marine organisms as habitat modifiers     

Wallentinus I  Nyberg CD 《Marine pollution bulletin》2007,55(7-9):323-332

Introductions of non-indigenous species (NIS) are mostly discussed through their impact on biodiversity. However, NIS can also act as ecosystem engineers, influencing the habitat itself, positively or negatively, directly or indirectly, which should be included when making risk assessments. Special concern should be given to changes in ecological services provided by the ecosystem. Physically, NIS may affect the substrate itself, or alter habitat architecture, indirectly influencing water movements, sediment accumulation, and light conditions. Chemical changes brought upon by NIS occur both on small and large scales, some having positive effects on ecosystem services, others can perturb epibionts. Furthermore, NIS may negatively affect natural resources, aquaculture or create fouling communities, all resulting in a negative impact on economics. However, if removed, already established NIS can be used as bioremediators, having a positive effect on different ecosystems. Using NIS for habitat management may be economically profitable, but could affect the habitat adversely.  相似文献   

A Hubble Space Telescope/NICMOS view of the prototypical giant Hii region NGC604 in M33     

Rodolfo H. Barbá  Jesús Maíz Apellániz  Enrique Pérez  Mónica Rubio  Alberto Bolatto  Cecilia Fariña  Guillermo Bosch  Nolan R. Walborn 《Astrophysics and Space Science》2009,324(2-4):309-313

We present the first high-spatial-resolution near-infrared (NIR) imaging of NGC604, obtained with the NICMOS camera onboard the Hubble Space Telescope (HST). These NICMOS broad-band images reveal new NIR point sources, clusters, and diffuse structures. We find an excellent spatial correlation between the 8.4 GHz radio continuum and the 2.2 μm nebular emission. Moreover, massive young stellar object candidates appear aligned with these radio peaks, reinforcing the idea that those areas are star-forming regions. Three different scaled OB associations are recognized in the NICMOS images. The brightest NIR sources in our images have properties that suggest that they are red supergiant stars, of which one was previously known. This preliminary analysis of the NICMOS images shows the complexity of the stellar content of the NGC604 nebula.  相似文献   

A long-lived cyclone in Saturn’s atmosphere: Observations and models     

T. del Río-Gaztelurrutia  J. Legarreta  S. Pérez-Hoyos 《Icarus》2010,209(2):665-681

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Transmission electron microscopy applied to fluid inclusion investigations   总被引：8，自引：0，他引：8  

Cecilia Viti  Maria-Luce Frezzotti 《Lithos》2001,55(1-4):125-138

The transmission electron microscope (TEM) allows a detailed characterization of textural and chemical features of fluid inclusions (shape, inner compositions and inner textures), at a resolution higher than that attainable with an optical microscope (OM). TEM investigation indicates that most fluid inclusions appear as perfectly euhedral negative crystals, with variable shape (from prismatic to equant) and size (typically from <0.02 to 0.15 μm). Inner texture (fluid phase/melt distribution) and composition are variable as well. Different kinds of negative crystals may coexist in the same trail of inclusions, possibly indicating locally variable trapping conditions.

A critical feature, revealed by TEM, is that inclusions are often connected to structural defects (in particular, to dislocation arrays), which are undetected by optical microscopy. The identification of these hidden nanostructures should be taken into account for the correct petrological interpretation of microthermometric results, particularly when controversial data have been obtained. In fact, these nanostructures may represent a possible path for fluid phase leakage, thus modifying the original composition and/or density of the inclusions.  相似文献   

Acoustic emission during swelling and contraction tests     

V.G. Ruiz de Argandofia  L. Calleja  L.M. Surez del Rio 《Engineering Geology》1995,39(3-4):147-150

An expansive clayey rock belonging to the Asturias Carboniferous of NW Spain has been petrophysically characterized before, during and after swelling tests. The evolution of the microfissuring and the induced deterioration have been studied by acoustic emission during tests and by ultrasonic techniques before and after swelling/contraction cycles. A good correlation has been found between the AE curves and swelling strain. Damage due to the generation and growth of microfissures is most important during the first moments of each swelling/contraction cycle. Microfissures mainly develop in the direction of the foliation planes, as can be shown by linear crack density and measurements of the propagation velocity of longitudinal waves.  相似文献   

The free oscillations of the Ligurian Sea computed by the H-N method     

Lorenzo Papa 《Ocean Dynamics》1977,30(3):81-90

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Some experimental data on the precipitation and migration of manganese on the seafloor     

Dr. M. del Monte  Dr. E. Rabbi 《Meteorology and Atmospheric Physics》1979,28(2-3):293-299

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Grossformenschatz und junge Landhebung in Spitzbergen     

Prof. Dr. J. Büdel 《International Journal of Earth Sciences》1960,50(1):290-291

Ohne ZusammenfassungKurzreferat. Eine ausführlichere Darstellung folgt in einem der nächsten Bände dieser Zeitschrift.  相似文献   

Visualization of Volcanic Rock Geochemical Data and Classification with Artificial Neural Networks   总被引：1，自引：0，他引：1  

Juan Pablo Lacassie  Javier Ruiz del Solar  Barry Roser  Francisco Hervé 《Mathematical Geology》2006,38(6):697-710

An unsupervised neural network technique, Growing Cell Structures (GCS) was used to visualize geochemical differences between four different island arc volcanic rock types: basalts, andesites, dacites and rhyolites. The output of the method shows the cluster structure of the dataset clearly, and the relevant geochemical patterns and relationships between its variables. The data can be separated into four clusters, each associated with a specific volcanic rock type (basalt, andesite, dacite and rhyolite), according to a unique combination of major element concentrations. Following clustering, performance of the trained GCS network as a classifier of volcanic rock type was tested using two test datasets with major element concentration data for 312 and 496 island arc volcanic rock samples of known volcanic type. Preliminary classification results are promising. In the first test dataset 94% of basalts, 76% of andesites, 83% of dacites and 100% of the rhyolites were classified correctly. Successful classification rates in the second dataset were 100%, 80%, 77%, and 98% respectively. The success of the analysis suggests that neural networks analysis constitutes a useful analytical tool for identification of natural clusters and examination of the relationships between numeric variables in large datasets, and that can be used for automatic classification of new data.  相似文献