排序方式: 共有46条查询结果,搜索用时 15 毫秒
1.
M. Cristina Fossi Silvia Casini Letizia Marsili Stefania Ancora Gabriele Mori Giovanni Neri Antonella Ausili Teresa Romeo Alessandra Moscatelli Giuseppe Notarbartolo Di Sciara 《Marine Ecology》2002,23(S1):184-189
Abstract. Endocrine Disrupting Chemicals (EDCs) have the potential to alter hormone pathways that regulate reproductive processes in wildlife and fisheries. In this research the unexplored hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs is investigated. In the Mediterranean environment, top predators accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, incurring high toxicological risk. Here we illustrate the need to develop sensitive biomarkers for evaluation of toxicological risk in top marine predators (Xiphias gladius, Thunnus thynnus thynnus) and non-lethal techniques, such as non-destructive biomarkers, for the hazard assessment of threatened species exposed to EDCs, such as marine mammals ( Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus ). 相似文献
2.
A. B. Pushkarev Yu. Yu. Kovalev I. E. Molotov M. B. Nechaeva Yu. N. Gorshenkov G. Tuccari C. Stanghellini X. Hong J. Quick S. Dougherty X. Liu 《Astronomy Reports》2004,48(11):900-908
VLBI observations of several quasars and BL Lacertae objects were carried out at 1.66 GHz in November–December 1999 using six antennas (Medvezh'i Ozera, Svetloe, Pushchino, Noto, HartRAO, and Shanghai). Maps of six sources (0420+022, 0420-014, 1308+326, 1345+125, 1803+784, and DA 193) obtained with milliarcsecond resolution are presented and discussed, together with their broad-band (1–22 GHz) spectra obtained on the RATAN-600 radio telescope at epochs close to those of the VLBI observations. Comparison of the VLBI maps with maps of these sources obtained on standard VLBI networks and with the RATAN-600 quasisimultaneous total-flux measurements indicates the reliability of the results obtained on this Low Frequency VLBI Network and the good efficiency of this network. 相似文献
3.
Marsili L Casini S Bucalossi D Porcelloni S Maltese S Fossi MC 《Marine environmental research》2008,66(1):151-153
The aim of the present study was to propose the immunofluorescence technique in cultured fibroblasts from Mediterranean cetaceans as a new "in vitro" tool to explore the susceptibility of these marine mammals to different xenobiotic compounds. The cell lines were cultured from integument biopsies of free-ranging and stranded cetaceans (dead within 12h). Using the indirect immunofluorescence assay, we detected endogenous proteins induced by different contaminants. Here we present the method used for qualitative and quantitative evaluation of cytochromes P450 (CYP1A1 and CYP2B) induced by some POPs (DDTs and PCBs) and emerging contaminants (PBDEs) in fibroblast cell cultures of striped dolphin (Stenella coeruleoalba) and bottlenose dolphin (Tursiops truncatus). Immunofluorescence was quantified with a specially designed Olympus macro, DetectIntZ. A major result was the possibility of using this "in vitro" assay to quantify induction of endogenous proteins. 相似文献
4.
Planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) offer the unique opportunity to study both the population and evolution of low- and intermediate-mass stars, by means of the morphological type of the nebula. Using observations from our LMC PN morphological survey, and including images available in the Hubble Space Telescope Data Archive and published chemical abundances, we find that asymmetry in PNe is strongly correlated with a younger stellar population, as indicated by the abundance of elements that are unaltered by stellar evolution (Ne, Ar, and S). While similar results have been obtained for Galactic PNe, this is the first demonstration of the relationship for extragalactic PNe. We also examine the relation between morphology and abundance of the products of stellar evolution. We found that asymmetric PNe have higher nitrogen and lower carbon abundances than symmetric PNe. Our two main results are broadly consistent with the predictions of stellar evolution if the progenitors of asymmetric PNe have on average larger masses than the progenitors of symmetric PNe. The results bear on the question of formation mechanisms for asymmetric PNe-specifically, that the genesis of PNe structure should relate strongly to the population type, and by inference the mass, of the progenitor star and less strongly on whether the central star is a member of a close binary system. 相似文献
5.
Giuseppe?Roberto?Tomasicchio Letizia?Lusito Felice?D’AlessandroEmail author Ferdinando?Frega Antonio?Francone Samuele?De?Bartolo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(12):3397-3408
The estimation of long-term sea level variability is of primary importance for a climate change assessment. Despite the value of the subject, no scientific consensus has yet been reached on the existing acceleration in observed values. The existence of this acceleration is crucial for coastal protection planning purposes. The absence of the acceleration would enhance the debate on the general validity of current future projections. Methodologically, the evaluation of the acceleration is a controversial and still open discussion, reported in a number of review articles, which illustrate the state-of-art in the field of sea level research. In the present paper, the well-proven direct scaling analysis approach is proposed in order to describe the long-term sea level variability at 12 worldwide-selected tide gauge stations. For each of the stations, it has been shown that the long-term sea level variability exhibits a trimodal scaling behaviour, which can be modelled by a power law with three different pairs of shape and scale parameters. Compared to alternative methods in literature, which take into account multiple correlated factors, this simple method allows to reduce the uncertainties on the sea level rise parameters estimation. 相似文献
6.
F. Fabio Fussi Letizia Fumagalli Francesco Fava Biagio Di Mauro Cheik Hamidou Kane Magatte Niang Souleye Wade Barry Hamidou Roberto Colombo Tullia Bonomi 《Hydrogeology Journal》2017,25(8):2263-2279
A method is proposed that uses analysis of borehole stratigraphic logs for the characterization of shallow aquifers and for the assessment of areas suitable for manual drilling. The model is based on available borehole-log parameters: depth to hard rock, depth to water, thickness of laterite and hydraulic transmissivity of the shallow aquifer. The model is applied to a study area in northwestern Senegal. A dataset of boreholes logs has been processed using a software package (TANGAFRIC) developed during the research. After a manual procedure to assign a standard category describing the lithological characteristics, the next step is the automated extraction of different textural parameters and the estimation of hydraulic conductivity using reference values available in the literature. The hydraulic conductivity values estimated from stratigraphic data have been partially validated, by comparing them with measured values from a series of pumping tests carried out in large-diameter wells. The results show that this method is able to produce a reliable interpretation of the shallow hydrogeological context using information generally available in the region. The research contributes to improving the identification of areas where conditions are suitable for manual drilling. This is achieved by applying the described method, based on a structured and semi-quantitative approach, to classify the zones of suitability for given manual drilling techniques using data available in most African countries. Ultimately, this work will support proposed international programs aimed at promoting low-cost water supply in Africa and enhancing access to safe drinking water for the population. 相似文献
7.
Andrew Harris Salvatore Alparone Alessandro Bonforte Jonathan Dehn Salvatore Gambino Luigi Lodato Letizia Spampinato 《Bulletin of Volcanology》2012,74(6):1293-1311
Between 1994 and 2010, we completed 16 thermal surveys of Vulcano’s Fossa fumarole field (Aeolian Islands, Italy). In each survey, between 400 and 1,200 vent temperatures were collected using a thermal infrared thermometer from distances of ~1?m. The results show a general decrease in average vent temperature during 1994–2003, with the average for the entire field falling from ~220°C in 1994 to ~150°C by 2003. However, between 2004 and 2010, we witnessed heating, with the average increasing to ~190°C by 2010. Alongside these annual-scale field-wide trends, we record a spatial re-organisation of the fumarole field, characterised by shut down of vent zones towards the crater floor, matched by rejuvenation of zones located towards the crater rim. Heating may be expected to be associated with deflation because increased amounts of vaporisation will remove volume from the hydrothermal system Gambino and Guglielmino (J Geophys Res 113:B07402, 2008). However, over the 2004–2010 heating period, no ground deformation was observed. Instead, the number of seismic events increased from a typical rate of 37 events per month during 1994–2000 to 195 events per month during 2004–2010. As part of this increase, we noticed a much greater number of high-frequency events associated with rock fracturing. We thus suggest that the heating event of 2004–2010 was the result of changed permeability conditions, rather than change in the heat supply from the deeper magmatic source. Within this scenario, cooling causes shut down of lower sectors and re-establishment of pathways located towards the crater rim, causing fracturing, increased seismicity and heat flow in these regions. This is consistent with the zone of rejuvenation (which lies towards and at the rim) being the most favourable location for fracturing given the stress field of the Fossa cone Sch?pa et al. (J Volcanol Geotherm Res 203:133–145, 2011); it is also the most established zone, having been active at least since the early twentieth century. Our data show the value of deploying multi-disciplinary geophysical campaigns at degassing (fumarolic) hydrothermal systems. This allows more complete and constrained understanding of the true heat loss dynamics of the system. In the case study presented here, it allows us to distinguish true heating from apparent heating phases. While the former are triggered from the bottom-up, i.e. they are driven by increases in heat supply from the magmatic source, the latter are triggered from the top-down, i.e. by changing permeability conditions in the uppermost portion of the system to allow more efficient heat flow over zones predisposed to fracturing. 相似文献
8.
Carmelo Cassisi Marco Aliotta Andrea Cannata Placido Montalto Domenico Patanè Alfredo Pulvirenti Letizia Spampinato 《Pure and Applied Geophysics》2013,170(4):529-545
Algorithms searching for similar patterns are widely used in seismology both when the waveforms of the events of interest are known and when there is no a priori-knowledge. Such methods usually make use of the cross-correlation coefficient as a measure of similarity; if there is no a-priori knowledge, they behave as brute-force searching algorithms. The disadvantage of these methods, preventing or limiting their application to very large datasets, is computational complexity. The Mueen–Keogh (MK) algorithm overcomes this limitation by means of two optimization techniques—the early abandoning concept and space indexing. Here, we apply the MK algorithm to amplitude time series retrieved from seismic signals recorded during episodic eruptive activity of Mt Etna in 2011. By adequately tuning the input to the MK algorithm we found eight motif groups characterized by distinct seismic amplitude trends, each related to a different phenomenon. In particular, we observed that earthquakes are accompanied by sharp increases and decreases in seismic amplitude whereas lava fountains are accompanied by slower changes. These results demonstrate that the MK algorithm, because of its particular features, may have wide applicability in seismology. 相似文献
9.
L. Stanghellini 《Astrophysics and Space Science》2000,272(1-3):181-188
Planetary nebulae (PNe) exist in a range of different morphologies, from very simple and symmetric round shells, to elliptical,
bipolar, and even quadrupolar shapes. They present extremely complex ensembles of filaments, knots, ansae, and shell multiplicity.
It is then overwhelmingly complicated to derive reasonable evolutionary paths to justify the observed shapes of PNe. The confrontation
between the evolution of the shells and that of the central stars is needed to understand the origin of the morphological
variety. We present some background and recent results on the correlations between PN morphology and PN nuclei (PNNi) evolution,
including a study on the Magellanic Cloud PNe.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Letizia Stanghellini 《Astrophysics and Space Science》1996,238(1):43-54
In this paper we review the evolutionary paths that lead to the different types of planetary nebulae nuclei, including hydrogen and helium-burning central stars. Starting from the empirical definition of WR central stars, based on stellar spectra, we examine the theoretical work produced to account for the observed configurations. Then we discuss the constraints provided by recent galactic and extragalactic observations, and finally state the possible developments in this field to achieve a better understanding of the subject. 相似文献