排序方式: 共有36条查询结果,搜索用时 15 毫秒
21.
Riccardo Cattaneo‐Vietti Valentina Cappanera Michela Castellano Paolo Povero 《Marine Ecology》2015,36(2):155-166
Since the 17th century, the Tonnarella of Camogli, a small tuna trap, has been used to catch pelagic fish along the western coast of the Portofino Promontory (Ligurian Sea, Northwestern Mediterranean). The availability of long‐term datasets on fish yields (1950–1974 and 1996–2011), with information related to the seawater temperatures and the North Atlantic Oscillation (NAO), has allowed us to study the qualitative and quantitative changes in fish yields in the last decade and the possible relationships with the seasonal anomalies of temperature that have occurred in the Ligurian Sea. In 1950–1974, yields remained relatively constant over time (average of 35.6 ± 8.7 t·year?1). From 1996 through 2011, yields were high (42.9 ± 15.9 t·year?1) but inconsistent with strong annual variability in catches. The primary catches are Seriola dumerili, Auxis rochei, Trachurus spp. and Sarda sarda. Changes in species composition have occurred as well: S. dumerili, Sardinella sp. and Belone belone have appeared recently. Moreover, a significant decrease in the boreal scombroid (Scomber scombrus) and an increase of warm‐temperate carangids and other typically Southern Mediterranean species such as Coryphaena hippurus and Sphyraena viridensis, appear to be linked to the warming of the surface water layer, particularly evident in the Ligurian Sea, for the last 10 years. The analysis of this kind of trend may be a powerful tool for assessing structural changes of the pelagic fish community in the Ligurian Sea (Northwestern Mediterranean). 相似文献
22.
Observations obtained in the last years challenged the widespread notion that rotation-powered neutron stars are steady X-ray emitters. Besides a few allegedly rotation-powered neutron stars that showed ‘magnetar-like’ variability, a particularly interesting case is that of PSR B0943+10. Recent observations have shown that this pulsar, well studied in the radio band where it alternates between a bright and a quiescent mode, displays significant X-ray variations, anticorrelated in flux with the radio emission. The study of such synchronous radio/X-ray mode switching opens a new window to investigate the processes responsible for the pulsar radio and high-energy emission. Here we review the main X-ray properties of PSR B0943+10 derived from recent coordinated X-ray and radio observations. 相似文献
23.
Anthony Stefanidis Peggy Agouris Charalambos Georgiadis Michela Bertolotto James D. Carswell 《International journal of geographical information science》2013,27(8):749-772
In this paper we extend our previous work on shape-based queries to support queries on configurations of image objects. Here we consider spatial reasoning, especially directional and metric object relationships. Existing models for spatial reasoning tend to rely on pre-identified cardinal directions and minimal scale variations, assumptions that cannot be considered as given in our image applications, where orientations and scale may vary substantially, and are often unknown. Accordingly, we have developed the method of varying baselines to identify similarities in direction and distance relations. Our method allows us to evaluate directional similarities without a priori knowledge of cardinal directions, and to compare distance relations even when query scene and database content differ in scale by unknown amounts. We use our method to evaluate similarity between a user-defined query scene and object configurations. Here we present this new method, and discuss its role within a broader image retrieval framework. 相似文献
24.
Hindcast of oil-spill pollution during the Lebanon crisis in the Eastern Mediterranean, July-August 2006 总被引:2,自引:0,他引:2
Coppini G De Dominicis M Zodiatis G Lardner R Pinardi N Santoleri R Colella S Bignami F Hayes DR Soloviev D Georgiou G Kallos G 《Marine pollution bulletin》2011,62(1):140-153
MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provides near-real-time information on oil-spill detection (ocean color and SAR) and predictions [ocean forecasts (MFS and CYCOFOS) and oil-spill predictions (MEDSLIK)]. We employ this system to study the Lebanese oil-pollution crisis in summer 2006 and thus to assist regional and local decision makers in Europe, regionally and locally. The MEDSLIK oil-spill predictions obtained using CYCOFOS high-resolution ocean fields are compared with those obtained using lower-resolution MFS hydrodynamics, and both are validated against satellite observations. The predicted beached oil distributions along the Lebanese and Syrian coasts are compared with in situ observations.The oil-spill predictions are able to simulate the northward movement of the oil spill, with the CYCOFOS predictions being in better agreement with satellite observations. Among the free MEDSLIK parameters tested in the sensitivity experiments, the drift factor appears to be the most relevant to improve the quality of the results. 相似文献
25.
Industrial accidents triggered by earthquakes,floods and lightning: lessons learned from a database analysis 总被引:2,自引:0,他引:2
Elisabeth Krausmann Elisabetta Renni Michela Campedel Valerio Cozzani 《Natural Hazards》2011,59(1):285-300
Natural hazards and disasters can cause major accidents in chemical and process installations. These so-called Natech accidents
can result in hazardous-materials releases due to damage to process and storage units, or pipes. In order to understand the
dynamics of Natech events, accidents triggered by earthquakes, floods and lightning recorded in industrial accident databases
were analysed. This allowed the identification of the most vulnerable equipment types, their modes of failure due to natural-event
impact and the final accident scenarios. Moreover, lessons learned for future accident prevention and mitigation were derived.
The analysis showed that pipes and storage tanks are the most vulnerable equipment for earthquakes, floods and lightning,
calling for more research of equipment behaviour under natural-event loading. The damage modes and states are strongly dependent
on the characteristics of the impacting natural event. Toxic dispersion, fires and explosions were observed as a consequence
of all three types of analysed natural events. In the case of floods, two additional scenarios were identified. These are
water contamination and the formation of toxic and/or flammable vapours upon reaction of the released chemicals with the floodwaters.
The overall number of recorded Natech accidents was found to range from 2 to 5% of all reported accidents in the analysed
databases. 相似文献
26.
Acidification in European mountain lake districts: A regional assessment of critical load exceedance 总被引:1,自引:0,他引:1
27.
Emphasis has been given to a number of aspects which characterise technological development in today's economic systems and
which have an impact on the working environment and on gender differences. Technological change is leading to a strong divide
between knowledge “producers” and “users”. The possibility of access to one or both knowledge systems indicates the extent
of women's participation in the economic and spatial transformations brought about by the new technologies. This research
aims to analyse the development of new technologies and the presence of the female workforce in the field of new knowledge
generation, and also to verify gender-related conditions in learning and using new technologies. In particular, an analysis
has been carried out of the empirical case study of Pisa, a point of reference for comparisons with other Italian and European
cases. The research focuses on: the examination of women's capabilities in the field of new technologies through the analysis
of University training courses; the analysis of women's presence and status among the university staff, especially in science
and technology; a detailed survey of female employment in innovative sectors. The results of the research emphasise the gender
perspectives of inclusion — as regards the application of technologies — and exclusion — as regards the generation of knowledge
— of women in or from new technologies. At the same time, the research stresses the growth of women's roles in this sector
during recent years and, by reconstructing life histories, underlines the conditions and difficulties that have been met by
women entering these new types of employment.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
28.
Michela Garau Maria Grazia Badas Simone Ferrari Alessandro Seoni Giorgio Querzoli 《Boundary-Layer Meteorology》2018,167(1):123-143
We experimentally investigate the effect of a typical building covering: the gable roof, on the flow and air exchange in urban canyons. In general, the morphology of the urban canopy is very varied and complex, depending on a large number of factors, such as building arrangement, or the morphology of the terrain. Therefore we focus on a simple, prototypal shape, the two-dimensional canyon, with the aim of elucidating some fundamental phenomena driving the street-canyon ventilation. Experiments are performed in a water channel, over an array of identical prismatic obstacles representing an idealized urban canopy. The aspect ratio, i.e. canyon-width to building-height ratio, ranges from 1 to 6. Gable roof buildings with 1:1 pitch are compared with flat roofed buildings. Velocity is measured using a particle-image-velocimetry technique with flow dynamics discussed in terms of mean flow and second- and third-order statistical moments of the velocity. The ventilation is interpreted by means of a simple well-mixed box model and the outflow rate and mean residence time are computed. Results show that gable roofs tend to delay the transition from the skimming-flow to the wake-interference regime and promote the development of a deeper and more turbulent roughness layer. The presence of a gable roof significantly increases the momentum flux, especially for high packing density. The air exchange is improved compared to the flat roof buildings, and the beneficial effect is more significant for narrow canyons. Accordingly, for unit aspect ratio gable roofs reduce the mean residence time by a factor of 0.37 compared to flat roofs, whereas the decrease is only by a factor of 0.9 at the largest aspect ratio. Data analysis indicates that, for flat roof buildings, the mean residence time increases by 30% when the aspect ratio is decreased from 6 to 2, whereas this parameter is only weakly dependent on aspect ratio in the case of gable roofs. 相似文献
29.
In this essay, we explore the contribution of establishing off-grid community micro-hydropower systems in the Dominican Republic to climate change mitigation and adaptation. Forty-five micro-hydropower systems were set up over 16 years that are sustainably and autonomously managed by the local groups and provide access to electricity to communities in remote areas while reducing CO2 emissions and favoring carbon sequestration. In addition to mitigating climate change by avoiding emissions and reforestation of more than 28,000 t of CO2 per year, these initiatives have improved the adaptive capacity of the local communities through contributing to biodiversity protection, climate policy development, and governance; as well as enhancing the wellbeing of families through increased savings, improved education, and increased income generation opportunities. We elaborate the key factors for success and considerations for meeting future challenges. 相似文献
30.
Joaquín?Martínez-MinayaEmail authorView authors OrcID profile Michela?Cameletti David?Conesa Maria?Grazia?Pennino 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(11):3227-3244
The use of complex statistical models has recently increased substantially in the context of species distribution behavior. This complexity has made the inferential and predictive processes challenging to perform. The Bayesian approach has become a good option to deal with these models due to the ease with which prior information can be incorporated along with the fact that it provides a more realistic and accurate estimation of uncertainty. In this paper, we first review the sources of information and different approaches (frequentist and Bayesian) to model the distribution of a species. We also discuss the Integrated Nested Laplace approximation as a tool with which to obtain marginal posterior distributions of the parameters involved in these models. We finally discuss some important statistical issues that arise when researchers use species data: the presence of a temporal effect (presenting different spatial and spatio-temporal structures), preferential sampling, spatial misalignment, non-stationarity, imperfect detection, and the excess of zeros. 相似文献