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Sediment toxicity assessments using caged organisms present advantages over using laboratory and native community studies. The use of caged Arenicola marina in sediment toxicity assessments was evaluated. Lugworms were exposed in situ to sediments from coastal and port areas in Spain for seven days, and the activities of the biotransformation enzymes ethoxyresorufin O-deethylase, dibenzylfluorescein dealkylase and glutathione S-transferase, the activities of the antioxidant enzymes glutathione reductase and glutathione peroxidase and lipid peroxidation were then analyzed as biomarkers. Biomarker results and sediment physicochemical data were integrated. Cádiz Bay (SW Spain) sediments presented metal contamination that was not linked to a biochemical response. In LPGC Port (SW Spain), Pb contamination exhibited a moderate toxic potential, while PAHs, and presumably pharmaceuticals, provoked biochemical responses that efficiently prevented lipid peroxidation. In Santander Bay (N Spain), exposure to PAHs and, presumably, pharmaceuticals induced biomarker responses, but lipid peroxidation occurred nevertheless. These results indicated that caged A. marina were effective for the assessment of sediment quality and that the selected biomarkers were sufficiently sensitive to identify chemical exposure and toxicity.  相似文献   
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Traditional astrometric methods are limited in accuracy by the atmosphere in a way that does not show much improvement with increased telescope aperture. However, there is the potential for very high accuracy with large telescopes if advantage can be taken of these factors: First, the differential atmospheric distortion of images of closely adjacent stars is less with larger aperture; second, the diffraction limit is sharper, and third, photon statistics are improved. In this paper we analyze and give experimental tests of techniques that could be applied to the detection of planets with the mass of Jupiter or Uranus, if they are present in nearby binary star systems.The atmospheric perturbation of the relative position of the energy centroids measured in short exposure images of binary stars depends on the effective height of the turbulent distortion. For a 4-meter telescope, the error in centroid determination of a 4-arcsec binary can be as small as 20 milliarcsec (mas) in a single 20-millisecond (msec) exposure. The relative position measured by cross-correlation of short exposure speckle images, as suggested by McAlister (1977b), may give even higher accuracy. In this case, Roddier (Roddieret al., 1980) has shown that the atmospheric error depends on the thickness rather than the height of the layers that make the dominant contribution to the turbulence. Through Monte Carlo analysis we show that on occasions when the turbulence arises largely in a thin layer, a single 20-msec exposure of a 4-arcsec binary taken with a 4-m aperture can yield an astrometric accuracy of order 0.5 mas.We report on experiments made at the Steward Observatory 2.3-m telescope which achieved accuracies corresponding to 1.7 mas in a 2.24-arcsec binary and 16.1 mas in a 6.0-arcsec binary with only 15 and 18 specklegram pairs respectively. We plan to use the 6.5-m converted MMT to obtain much higher performance, between 4.0 mas and 0.40 masper independent specklegram pair, depending upon atmospheric conditions, for binaries of 4-arcsec separation. By cycling rapidly through perhaps 100 binaries, thus calibrating systematic errors through the average change in binary separation, Jupiter-mass planets may be detectable with small but regular access to the telescope.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A.  相似文献   
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Angel Paniagua 《GeoJournal》2018,83(5):993-1004
The aim of this study is to place the current geographical debate on nature in the context of protected natural areas severely affected by depopulation processes, in which the daily lives of the inhabitants have been altered by changes in the traditional balance between human and non-human populations. A significantly humanized area within the Sierra Norte de Guadalajara National Park in central Spain is considered as an example. The qualitative methodology followed is based on documentary analysis and interviews with key inhabitants in the area, revealing narratives with a productive or consumer view of the nature. The national park appears as a container of a cultural nature, initially created by the traditional inhabitants, which generates an artificial, excessive nature and accelerates regressive sociodemographic dynamics.  相似文献   
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A daylight bolide was observed over Galicia (NW Spain) and Minho (N. Portugal) on March 1, 2005 at 15 h10 min ± 3 min UTC. We interviewed 23 eyewitnesses of the event in order to obtain the azimuth, altitude, and slope of the fireball’s trajectory. Reports suggest an atmospheric ending height below 20 km, indicating that meteorite survival was likely. From the reconstructed trajectory and the fireball’s duration, we obtained the approximate heliocentric orbits for the meteoroid. Assuming an entry velocity higher than 20 km s−1 which is consistent with its estimated duration, the meteoroid originated in the asteroid belt.  相似文献   
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