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1.
Zooplankton are an essential component of the marine and estuarine food chains. The ecotoxicological risk to zooplanktonic communities, estimated through the use of the biomarkers, can be used as an early warning signal of a potential alteration of the ecosystem health. The aim of this project was to evaluate the potential use of several biomarkers (esterases, mixed function oxidases, porphyrins) in zooplanktonic organisms. The acetylcholinesterase activity (AChE) was determined in homogenates of whole organisms of 10 different zooplanktonic crustaceans. Mean activity of AChE was 10.05 micromol/min/g for Acartia margalefi; 3.30 for Acartia latisetosa; 79.70 for Siriella clausi; 49.97 for Diamysis bahirensis; 7.48 for Siriella armata; 14.20 for Mysidopsis gibbosa; 4.49 for Euphausia crystallorophias; 1.66 for Euphausia superba; 2.74 for Streetsia challengeri; 13.26 for Meganycthiphanes norvegica. The species moreover showed a linear increase in enzyme activity in relation to the increase in sample concentration. The key result of this study concerns the different AChE activity basal values of the crustaceans' different species. 相似文献
2.
Low multipath antennas for GNSS-based attitude determination systems applied to high-altitude platforms 总被引：1，自引：1，他引：0
Luigi Boccia Pasquale Pace Giandomenico Amendola Giuseppe Di Massa 《GPS Solutions》2008,12(3):163-171
High-altitude platforms (HAPs) are a flexible and attractive technology for providing innovative wireless services. These
aerial platforms can be successfully employed for mobile or broadband communications and for disaster monitoring or response.
However, one of the open issues is whether HAP stations can provide reliable services without temporal outages owing to stratospheric
winds that can cause positional and attitude instabilities thus affecting the communication system operation. To counteract
this issue, one possible solution is to use reconfigurable antennas whose pointing direction can be adjusted depending on
the platform spatial orientation. However, this would require real-time three-axial attitude data. As a possible solution,
this paper will review the potential of GNSS-based attitude determination systems with reference to HAP stations. In particular,
it will be shown how the use of a particular class of low multipath and lightweight antennas can provide a high degree of
accuracy without altering the avionic ballast. 相似文献
3.
T. Le Berter N. Epchtein F. Guglielmo P. Le Sidaner 《Astrophysics and Space Science》1994,217(1-2):105-116
The goal of this article is to show that, if one avoids star forming regions, mass-losing AGB stars can generally be selected from the data that will be provided by the near-infrared surveys which are presently considered. Also, if IRAS data are available, the separation between carbon-rich and oxygen-rich stars can be operated by their positions in infrared colour diagrams. In extragalactic systems, red supergiants can be discriminated from AGB stars by their luminosities.based on observations obtained with the ESO 1-m telescope 相似文献
4.
Abstract. Zooplankton is an essential component of the marine and brackish food chains. The ecotoxicological risk of zooplanktonic communities, estimated by the modern methodological approach of biomarkers, can be used as an early warning signal of ecosystem health. The aim of this project is to estimate the potential use of several biomarkers (esterases, mixed function oxidases, porphyrins) in zooplanktonic organisms. Studies were carried out with different zooplanktonic crustaceans: the copepods Acartia margalefi and Acartia latisetosa collected in Ganzirri Lake (Messina); the mysid Siriella clausi collected in Faro Lake (Messina); the mysids Diamysis bahirensis, Siriella armata and Mysidopsis gibbosa collected in Stagnone di Marsala (Palermo); the Antarctic euphausiids Euphausia crystallorophias and Euphausia superba; the am-phipod Streetsia challengeri and the euphausiid Meganycthiphanes norvegica collected after a shore-stranding along Messina's Ionian coast. Moreover, experiments were carried out with the benthic decapods Eriphia verrucosa and Pachygrapsus marmoratus from a rocky shore of Messina's Ionian coast. Acetylcholinesterase activity (AChE) was determined in homogenates of whole organisms. The key result of this project concerns the different AChE activity basal values of different crustacean species. Particular attention should be paid to the difference in basal activity found between the Antarctic and the Mediterranean species. 相似文献
5.
Improving basin scale shallow landslide modelling using reliable soil thickness maps 总被引：3，自引：0，他引：3
Soil thickness is a well-known factor controlling shallow landsliding. Notwithstanding, its spatial organisation over large
areas is poorly understood, and in basin scale slope analyses it is often established using simple methods. In this paper,
we apply five different soil thickness models in two test sites, and we use the obtained soil thickness maps to feed a slope
stability model. Validation quantifies how errors in soil thickness influence the resulting factor of safety and points out
which method grants the best results. In particular, in our cases, slope-derived soil thickness patterns produced the worst
slope stability assessment, while the use of reliable soil thickness maps obtained by means of a more complex geomorphologically
indexed model improved shallow landslides modelling. 相似文献
6.
Luca Amendola Joshua A. Frieman Ioav Waga 《Monthly notices of the Royal Astronomical Society》1999,309(2):465-473
We consider the prospects for detecting weak gravitational lensing by underdensities (voids) in the large-scale matter distribution. We derive the basic expressions for magnification and distortion by spherical voids. Clustering of the background sources and cosmic variance are the main factors that limit in principle the detection of lensing by voids. We conclude that only voids with radii larger than ∼100 h −1 Mpc have lensing signal-to-noise ratio larger than unity. 相似文献
7.
Luca Amendola Sandra Savaglio 《Monthly notices of the Royal Astronomical Society》1999,309(3):576-584
We investigate the clustering properties of 13 QSO lines of sight in flat space, with average redshifts from z ≈2 to 4. We estimate the 1D power spectrum and the integral density of neighbours, and discuss their variation with respect to redshift and column density. We compare the results with standard CDM models, and estimate the power spectrum of Lyman- α clustering as a function of both redshift and column density. We find that (a) there is no significant periodicity or characteristic scale; (b) the clustering depends on both column density and redshift; (c) the clustering increases linearly only if at the same time the H i column density decreases strongly with redshift. The results remain qualitatively the same, assuming an open cosmological model. 相似文献
8.
We calculate analytically and numerically the distance–redshift equation in perfect fluid quintessence models and give an accurate fit to the numerical solutions for all the values of the density parameter and the quintessence equation of state. Then we apply our solutions to the estimation of H 0 from multiple image time delays and find that the inclusion of quintessence modifies significantly the likelihood distribution of H 0 , generally reducing the best estimate with respect to a pure cosmological constant. Marginalizing over the other parameters (Ω m and the quintessence equation of state) we obtain H 0 =71±6 km s−1 Mpc−1 for an empty beam and H 0 =64±4 km s−1 Mpc−1 for a filled beam. These errors, however, do not take into account the uncertainty on the modelling of the lens. We also discuss the future prospects for distinguishing quintessence from a cosmological constant with time delays. 相似文献
9.
L. Amendola C. Quercellini E. Giallongo 《Monthly notices of the Royal Astronomical Society》2005,357(2):429-439
We discuss the constraints that future photometric and spectroscopic redshift surveys can put on dark energy through the baryon oscillations of the power spectrum. We model the dark energy either with a perfect fluid or a scalar field and take into account the information contained in the linear growth function. We show that the growth function helps to break the degeneracy in the dark energy parameters and reduce the errors on w 0 , w 1 roughly by 30 per cent, making more appealing multicolour surveys based on photometric redshifts. We find that a 200-deg2 spectroscopic survey reaching z ≈ 3 can constrain w 0 , w 1 to within Δ w 0 = 0.21, Δ w 1 = 0.26 , to Δ w 0 = 0.39, Δ w 1 = 0.54 using photometric redshifts with an absolute uncertainty of 0.02, and to Δ w 0 = 0.43, Δ w 1 = 0.66 with an uncertainty of 0.04. In the scalar field case, we show that the slope n of the inverse power-law potential for dark energy can be constrained to Δ n = 0.26 (spectroscopic redshifts) or Δ n = 0.40 (photometric redshifts), i.e. better than with future ground-based supernovae surveys or cosmic microwave background data. 相似文献
10.