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1.
Turanoceratops tardabilis—the first ceratopsid dinosaur from Asia   总被引:2,自引:1,他引:1  
Turanoceratops tardabilis from the Upper Cretaceous (Turonian) Bissekty Formation of Dzharakuduk, Uzbekistan, represents the first definite ceratopsid dinosaur recorded from Asia. Reexamination of the original and study of newly collected material indicate that Turanoceratops has well-developed supraorbital horns and apparently lacks a nasal horn. Turanoceratops is more derived than the more or less coeval Zuniceratops from the Moreno Hill Formation of New Mexico in the presence of double-rooted teeth and of two or three teeth in each vertical dental file.  相似文献   

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Recent molecular data strongly support the monophyly of all extant Australian and New Guinean marsupials (Eomarsupialia) to the exclusion of extant South American marsupials. This, together with available geological and fossil evidence, has been used to argue that the presence of marsupials in Australia is simply the result of a single dispersal event from South America during the latest Cretaceous or Palaeocene, without subsequent dispersals between the two continents. Here, I describe an isolated ankle bone (calcaneus) of a metatherian from the early Eocene Tingamarra Local Fauna in northeastern Australia. Strikingly, this specimen, QM F30060, lacks the ‘continuous lower ankle joint pattern’ (CLAJP), presence of which is a highly distinctive apomorphy of the marsupial clade Australidelphia, which includes Eomarsupialia, the living South American microbiotherian Dromiciops and the Tingamarran fossil marsupial Djarthia. Comparisons with a range of marsupials and stem-metatherians strongly suggest that the absence of the CLAJP in QM F30060 is plesiomorphic, and that this specimen represents the first unequivocal non-australidelphian (‘ameridelphian’) metatherian known from Australia. This interpretation is confirmed by phylogenetic analyses that place QM F30060 within (crown-group) Marsupialia, but outside Australidelphia. Based on these results, the distribution of marsupials within Gondwana cannot be explained by simply a single dispersal event from South America and Australia. Either there were multiple dispersals by marsupials (and possibly also stem-metatherians) between South America and Australia, in one or both directions, or, alternatively, there was a broadly similar metatherian fauna stretching across southern South America, Antarctica and Australia during the Late Cretaceous–early Palaeogene.  相似文献   

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This paper analyses social, economic and ecological issues affecting sustainability of the four selected forestry clean development mechanism (CDM) projects from India. Data from the group discussions and stakeholder interviews suggest that three out of the four projects are economically unsustainable for local people because of high opportunity cost of land and labour, and delayed and low benefits. The average opportunity cost of the land is 20000, 12000 and 9000 INR/ha/year in case of Haryana, Himachal Pradesh and Tamil Nadu, India projects respectively, which is unlikely to be met through projected carbon revenues and other benefits. A significant number of farmers have already withdrawn their private lands in Haryana and Tamil Nadu projects. Very few of them have undertaken plantations on the private lands in the Himachal project. All the four projects have undertaken block plantations of predominantly fast growing species such as Eucalyptus (Eucalyptus hybrid), Casuarina (Casuarina equisettifolia) and Ailanthus (Ailanthus excelsa) for high growth and quick returns, which could have adverse social and ecological impacts over long term. There are social and institutional issues such as low participation of local communities, weak or non existing community institutions, inflexible design and rigid CDM rules, which affect sustainability of these projects. It has implications for other carbon forestry programmes such as Green India Mission and Reducing Emissions from Deforestation and Degradation (REDD+) being rolled out at a large scale in the country. The rationale and significance of these programmes needs to be objectively reexamined in context of the issues affecting CDM projects.  相似文献   

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Mountain lakes are usually sensitive to the effects of global and regional environmental changes. Since the second half of the 20th century, surface-water acidification has become a significant ecological problem, and many lakes in Europe and North America have anthropogenically acidified. Additionally, following reduction in emissions of sulfur (S) and nitrogen (N) compounds, recovery from acidification has been observed in many lakes. In this study, we used changes in diatom communities to reconstruct the pH histories based on changes recorded in nine Tatra lakes (Western Carpathians, Poland) since approximately 1850 AD. Overall, results indicate that acidic precipitation had little influence on lake-water pH in the Tatra Mountain lakes. Changes in diatom-inferred pH (DI-pH) generally were small and showed little evidence of acidification during the time of the highest air pollution (since the 1960s), and have shown little change since the reduction of acidic deposition since the 1990s. Lakes that showed some evidence of acidification included dystrophic lakes with low acid neutralizing capacity. However, as illustrated by the PCA trajectories of the diatom assemblages, the majority of the lakes currently contain diatom assemblages that are unlike the diatom floras that existed ca. 1850.  相似文献   

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The World Year of Physics (2005) is an international celebration to commemorate the 100th anniversary of Einstein’s “Annus Mirabilis.” The United Nations has officially declared 2005 as the International Year of Physics. However, the impact of Einstein’s ideas was not restricted to physics. Among numerous other disciplines, Einstein also made significant and specific contributions to Earth Sciences. His geosciences-related letters, comments, and scientific articles are dispersed, not easily accessible, and are poorly known. The present review attempts to integrate them as a tribute to Einstein in commemoration of this centenary. These contributions can be classified into three basic areas: geodynamics, geological (planetary) catastrophism, and fluvial geomorphology. Regarding geodynamics, Einstein essentially supported Hapgood’s very controversial theory called Earth Crust Displacement. With respect to geological (planetary) catastrophism, it is shown how the ideas of Einstein about Velikovsky’s proposals evolved from 1946 to 1955. Finally, in relation to fluvial geodynamics, the review incorporates the elegant work in which Einstein explains the formation of meandering rivers. A general analysis of his contributions is also carried out from today’s perspective. Given the interdisciplinarity and implications of Einstein’s achievements to multiple fields of knowledge, we propose that the year 2005 serve, rather than to confine his universal figure within a specific scientific area, to broaden it for a better appreciation of this brilliant scientist in all of his dimensions.  相似文献   

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The Industrial Pollution Control Association of Japan (IPCAJ) has carried out a 3-year study in order to promote an understanding of the behavior of suspended particulate matter, to identify the contributing sources and to estimate their contributions. In this study many monitoring stations were set up around the Kashima industrial area. Atmospheric aerosols were collected for 2 weeks in each of the four seasons of 1983. The chemical compositions of the aerosols were analysed by instrumental neutron activation analysis and so on.The results of the study showed that soil particles comprise the highest component, while sulfate and other secondary particles are higher in the spring ans summer. In the spring and fall when sea breezes are dominant, sea salt has been found to have a higher concentration, especially at sites near the shore.Following the above-mentioned information a source apportionment study was conducted using the chemical mass balance method. Results have shown that the contributions of soil and sea salt are greater than the contributions from industrial sources for the Kashima area.  相似文献   

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The atmosphere of Santiago de Chile has been investigated by telephotometry in several parts of the city. Spectral extinction coefficients were measured during the time period between September 1988 and January 1989 (mid-spring to mid-summer) and again between February 1990 and June 1990 (autumn to mid-winter). The values measured show a distinct daily pattern with high values in the morning and a steady decrease in the afternoon. This pattern is attributed to a steady increase in the height of the mixing layer during daytime which allows an increasing dilution of the aerosol; unfortunately systematic measurements of vertical temperature profiles are not available for Santiago. In contrast to the urban area, measurements at an elevated site in the Andes Mountains showed a constant increase in light extinction during daytime. In the morning the extinction coefficients were similar to the background values off the coast on the Pacific. In the afternoon after expansion of the mixing layer extinction coefficients in the mountains were comparable to those in the urban area. Some sight paths were reached at later hours by the mixing layer and had a maximum of light extinction coefficient later in the morning hours. The transport of aerosols can cause dramatic changes in extinction coefficients within a short time; changes of up to a factor of five have been observed within an hour. In such cases the wavelength dependence of the aerosol underwent changes with the advection or production of a different aerosol. A comparison with the pollution of other large cities shows that the daily pattern of variation of the extinction coefficient in Santiago is different; the values of the extinction coefficients observed in Santiago de Chile are compared to those in European and Asian cities. With this study part of the complex behaviour of the Santiago atmosphere has been understood but much further work is needed. The optical technique used here has proven useful in investigating the atmosphere in real time with adequate time resolution and the possibility to make space-resolved measurements also.  相似文献   

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Flood risk management is becoming increasingly important, because more people are settling in flood-prone areas, and flood risk is increasing in many regions due to extreme weather events associated with climate change. It has been proposed that appropriately designed flood risk communication campaigns can stimulate floodplain inhabitants to prepare for flooding, and encourage adaptation to climate change. However, such campaigns do not always result in the desired action, and the effectiveness of communication in raising flood risk awareness and improving flood preparedness has hardly been studied. We evaluate different flood risk communication strategies, using an agent-based modelling approach, which is especially suitable for examining the effect of communication on each individual, and how flood risk communication can propagate through an individual’s social network. Our modelling results show that tailored, people-centred, flood risk communication can be significantly more effective than the common approach of top-down government communication, even when tailored communication reaches fewer individuals. Furthermore, communication on how to protect against floods, in addition to providing information about flood risk, is much more effective than the traditional strategy of communicating only about flood risk. Another main finding is that a person’s social network can have a significant effect on whether or not individuals take protective action. This leads to the recommendation that flood risk communication should aim at exploiting this natural amplifying effect of social networks, for instance, through the use of social media.  相似文献   

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A yearlong monitoring program in the backwater area of Xiaojiang River (XBA) was launched in order to investigate the eutrophication of backwater areas in tributaries of the Yangtze River in the Three Gorges Reservoir (TGR) in China, starting after the impoundment water level of the TGR reached 156 m. From March 2007 to March 2008, the average concentration of total nitrogen (TN) and total phosphorus (TP) were (1553±484) μg·L−1 and (62±31) μg·L−1, respectively. The mean value of chlorophyll was (9.07±0.91) μg·L−1. The trophic level of XBA was meso-eutrophic, while the general nutrient limitation was phosphorus. The results indicated that XBA has a strong ability to purify itself and has non-point source pollution from terrestrial runoff. The variation of TN/TP ratio was caused by a variation in TN rather than in TP when TN/TP < 22. N-fixation from cyanobacteria occurred and became an important process in overcoming the nitrogen deficit under a low TN/TP ratio. When TN/TP ⩾ 22, the variation of TP affected the TN/TP ratio more significantly than TN. The increase of TP in XBA was caused mainly by particulate phosphorus, which could originate from a non-point source as adsorptive inorganic forms after heavy rainfall and surface runoff. An increase in the river’s flow could also contribute to an unstable environment for the growth of phytoplankton.  相似文献   

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As a contribution to the climatological characterization of the Izaña baseline observatory (Tenerife, Canary Islands, Spain), back-trajectories were calculated and an air mass climatology was developed for a 5-year period. On a daily basis, 5-day back-trajectories were computed for the 850- and 700-HPa levels from January 1983 to December 1987. Trajectories were separated into long- and short-range flows and classified into categories depending on the path followed by the air masses. Flows from the North Atlantic Ocean were much more frequent than flows from continental sectors. In addition, seasonal variations of the sector frequencies were studied and synoptic meteorological patterns were associated with each trajectory category.  相似文献   

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A new African species of hystricognathous rodent, Gaudeamus lavocati sp. nov., is described herein from the early Oligocene deposits of Zallah locality (Sirt basin, Central Libya). The dental morphology of this species is very close to that of some earliest South American caviomorphs. It allows a reinterpretation of molar crest homologies among earliest caviomorphs, pentalophodonty being confirmed as the plesiomorphic molar condition in Caviomorpha. This morphological resemblance argues for close affinities between Gaudeamus and earliest South American hystricognaths. Cladistic analysis supports Gaudeamus lavocati sp. nov. as the first known African representative of Caviomorpha, implying that its ancestors were part of the African phiomyid group that crossed the South Atlantic by a direct immigration route. Alternatively, the series of derived dental features of Gaudeamus could also be interpreted as evolutionary synchronous convergences of an African hystricognath lineage towards the specialized pattern of some caviomorphs. However, the high level of similarities concerning teeth morphology and enamel microstructure and the similar age of fossiliferous strata on both continents make this interpretation less probable. The phylogenetic position of this taxon is of considerable importance because it represents an enigmatic component of the phiomorph–caviomorph radiation in Africa and appears as a new clue toward the understanding of caviomorph origins.  相似文献   

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The inter-conversion of nitrogen and sulfur species between the gas and particulate phases and their interaction with alkaline species influences the acidity of the aerosols and surface snow. To better understand these processes, a short field campaign was undertaken in Ny-Ålesund, Svalbard, during 13th April 2012 to 24th April 2012. Air measurements were carried out through a particulate sampler equipped with denuders and filter packs for simultaneous collection of trace gases (HNO3, NO2, SO2 and reactive nitrogen compounds) and aerosols, with daily collection of snow samples. Ionic composition of the samples was analyzed using ion chromatography technique. The results suggested that nitrate-rich aerosols are formed when PAN (peroxy acetyl nitrate) disassociates to form NO2 and HNO3 which further hydrolyzes to form pNO3? (particulate nitrate). This resulted in a high contribution of pNO3? (62%) to the total nitrogen budget over the study area. The acidity of the aerosols and snow evaluated through cation/anion ratio (C/A) indicated alkaline conditions with C/A > 2. The bicarbonates/carbonates of Mg2 + played an important role in neutralization processes of surface snow while the role of NH3 was dominant in aerosol neutralization processes. Such neutralization processes can increase the aerosol hygroscopicity causing warming. Chloride depletion in the snow was significant as compared to the aerosols, indicating two important processes, scavenging of coarse sea salt by the snow and gaseous adsorption of SO2 on the snow surface. However, a more systematic and long term study is required for a better understanding of the neutralization processes and chemical inter-conversions.  相似文献   

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One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30° to horizontal at the five NAPAP materials exposure sites range from ∼ 15 to ∼ 30 μm yr−1 for marble, and from ∼ 25 to ∼ 45 μm yr−1 for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ∼ 30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ∼ 70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide (“clean rain”). These results are for marble and limestone slabs exposed at an angle of 30° from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60° or 85°. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC, and Steubenville, OH.  相似文献   

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Gas-particle partitioning is examined using a partitioning constant Kp = (F/TSP)/A, where F (ng m−3) and A (ng m−3) are the particulate-assiociated and and concentrations, respectively, and TSP is the total suspended particulate matter level (μg m−3). At a given temperature and for a given sample of particulate matter, compound-dependent values of Kp tend to be correlated with the sub-cooled liquid vapor pressure (pL0, toor according to log Kp = mr log pL0+bm. Theory predicts that br values should be somewhat similar, and that mr values should be near −1. This is supported by field and laboratory work. However, there is still noticeable variability in reported mr and br values, even when obtained by the same researchers sampling in the same location. Three possible thermodynamic sources of variability include variability in the compound-to-compound differences in the thermodynamics of adsorption, event-to-event variability in the specific surface area of the aerosol and event-to-event variability in the ambient temperature. Non-thermodynamic sources of variability include sorption of gaseous analytes to the filters used in differentiating between F and A, the presence of non-exchangeable component in the measured F values, within-event adsorption/desorption kinetics, within-event changes in contaminant levels, and within-event changes in temperature. Each of these sources of variability operate in their own way to cause variability in mr and br. In general, one can expect there to be a correlation in the obseved mr and br of the form br = msmr+bs. For the study of Yamasaki et al. (1982, Envir. Sci. Technol. 16, 189–194), one obtains ms = 5.77 and bs = −2.18, with r2 = 0.91. In the presence of such a correlation, one can expect that all log (F/TSP)/A vs log pL0 plot will tend to intersect at the same (x,y) poitn given by (−ms, bs. Exisiting field and laboratory data show this tendency.  相似文献   

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