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201.
Growth hiatuses in massive corals are usually indicative of past ecological or environmental stresses. Among 37 fossil Porites colonies surveyed from the reef flat of Dadonghai fringing reef at Sanya, Hainan Island, northern South China Sea, seven of them were found to show clear evidence of past mortality, representing a population of ~19%. Among these samples, two of them (SYO‐13 and SYO‐28) display clear growth hiatuses reflecting mortality followed by subsequent recruitment, and five others exhibit a well‐preserved mortality surface and no subsequent recruitment. The growth hiatuses were dated using high‐precision thermal ionisation mass spectrometry U‐series techniques. The age results suggest all the dated corals formed and died in the mid Holocene. Multiple dates below the growth hiatuses suggest that SYO‐13 and SYO‐28 died at 6298 ± 11 and 6929 ± 19 a BP (i.e. years before AD 1950), respectively. Multiple dates above the growth hiatuses indicate that growth in SYO‐13 and SYO‐28 resumed at 6257 ± 14 and 6898 ± 20 a BP, respectively. The calculated durations of growth hiatuses are therefore 41 ± 18 a for SYO‐13 and 31 ± 28 a for SYO‐28, respectively, implying growth resumed within decades after the mortality events. U‐series dating of four other samples with dead heads suggests that they died at 6035 ± 53, 6059 ± 23, 6127 ± 22 and 6474 ± 24 a BP, respectively. In addition, using solution inductively coupled plasma mass spectrometry (ICP‐MS), monthly resolution Sr/Ca and Mg/Ca ratios were determined for the annual growth bands below and above the growth hiatuses for three of the dated samples. The Sr/Ca and Mg/Ca profiles indicate that the three corals probably died in different seasons (from spring to autumn), and the mortality appears to be unrelated to anomalous sea surface temperature‐induced bleaching. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Lawrence Di Bartolo 《The Australian geographer》2001,32(3):321-341
Police call data and court data are used to map the incidence of reported domestic violence in Brisbane. These data are correlated with low family income, unemployment and a measure of multiple disadvantage (an Index of Relative Socio-Economic Disadvantage) for each Statistical Local Area (suburb) in Brisbane. Only the Index of Relative Socio-Economic Disadvantage is a statistically significant predictor of reported domestic violence. The finding of a significantly higher incidence of reported domestic violence among relatively worse-off families is investigated within a social justice context. A measure of multiple relative disadvantage is shown to better reflect the negative impacts of structural inequalities on families in explaining the reported occurrence of domestic violence . 相似文献
204.
We develop a simple dynamical system model of the Arctic Ocean and marginal seas by applying the Martinson, Killworth and Gordon box model of a high-latitude two-layer ocean to four regions connected together: the Greenland Sea, the Norwegian Sea, the Arctic Ocean, and the Greenland Gyre. The latter is a small convective region embedded in the northwest corner of the Norwegian Sea. The model for each region consists of a thermodynamic ice layer that covers two layers of saline water which can, under specific conditions, become statically unstable and hence create a state of active overturning. The system is forced by monthly mean atmospheric temperatures in the four regions, by continental runoffs and by inflows from adjacent oceans. The model predicts the ice thickness, and the temperature and salinity of the water in the upper layer of the four regions. Also determined are the water temperature and salinity of the lower layer in the Arctic Ocean box. The convective state of any given region, i.e. whether it is in an active overturning mode or not, is also determined as a continuous function of time. The different output variables of the model, which are the response to climatological forcing conditions, compare favourably with observed data. In the control run, the Arctic Ocean region is characterized by continuous ice cover, the Greenland Sea and Greenland Gyre have ice cover only during winter, and the Norwegian Sea region never forms an ice cover. Another feature of the control run is the winter time occurrence of convective overturning in the upper 200 m in the Greenland Gyre region. The model is also used for different anomaly experiments: a positive air temperature anomaly which represents a global warming of the earth, a negative salt anomaly in the Norwegian Sea which simulates the great salinity anomaly of the 1960s and 1970s, and an increase in the ice flux through Fram Strait which parameterizes anomalous ice production in the Arctic. 相似文献
205.
The viability of most analytical approaches developed to predict the inelastic response of Reinforced Concrete (RC) structures requires the load-deformation relationship to have a positive slope. In many realistic cases the slope is not positive. When this happens, most analytical approaches consider the maximum point as the failure point or use unrealistic material laws, e.g., the assumption of a positive slope when it really is negative. Hence, there is a need to develop a new analytical approach which recognizes load-deflection relationships which have ascending and descending branches. A method based on the impulse momentum principle and the resistance force (IMR) of an RC structure is developed. The resistance force vector { R (t)} is used in place of the stiffness approach. The material non-linearity of RC systems can be elegantly accounted for in the { R (t)} vector. An examination of numerical properties of the IMR method shows that stability and convergence are dependent on a time step length ratio. Applications of the IMR method which predict the inelastic seismic response of RC structures are performed. 相似文献
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207.
Drew Lawrence J. Karlinger Michael R. Armstrong Thomas R. Moore Richard B. 《Natural Resources Research》1999,8(2):137-152
Exploratory variography was used to examine the spatial continuity of water–well yields in the Pinardville 7
Minute Quadrangle in southern New Hampshire and to link the variography to the characteristics of the fractured igneous and metamorphic rocks within the aquifer system. In addition to the analyses of variograms computed by using data from 939 wells, analyses were performed on subsets of the data that were stratified according to the level of yield and to five rock types. The stratification according to yield was defined by using the industry standard of a high-yield well that produces 40 gallons per minute or more. The stratification of the low-yield wells by rock type was defined by using the classification on the bedrock map for the State of New Hampshire. Although the variability is high in the low-yield wells, as indicated by the large nugget value, overall continuity ranges to 6000 feet in the fracture zones in which these wells have been drilled. This continuity is dominant in the northwesterly direction, as indicated by the directional variography. This result is consistent with the general trend in the larger tectonic configuration of the region. A lack of spatial correlation for 81 high-yield wells is consistent with the geologic interpretation that these wells occur in locally determined configurations of sheeting and steeply dipping fractures. Yield data in only three of the five rock types were sufficient for variography. Within these three, the dominant direction of the correlation structure ranged from northwesterly for the Massabesic Gneiss Complex to northeasterly for the Rangeley Formation to northerly for the Spaulding Granite, where the signature of the continuity in the low-yield wells is predominately attributed to the fracture system. 相似文献
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210.
Abstract A nearly complete skeleton of a fossil sperm whale from the Middle Miocene age Bessho Formation at Shiga-mura, Nagano Prefecture, the most complete fossil physeterid skeleton found in Japan, is here named Scaldicetus shigensis, new species. Its abruptly tapered rostrum, deep supracranial basin, and high occipital crest are typical of physeterids. Large teeth with crenulate enamel on conical crowns, present in both the palate and mandible, are consistent with the genus Scaldicetus du Bus, 1867, a genus originally based on fossils discovered in the Antwerp Basin, Belgium. Scaldicetus shigensis is relatively primitive, having a relatively long, slender rostrum, large zygomatic arches, large tympanic bullae, prominent occipital condyles, low tooth count and a sloping occipital shield that is deeply emarginated laterally by large temporal fossae. The probable mandibular tooth count is 12, only one more than the primitive eutherian mammalian dentition. Despite its abundant primitive characters, Scaldicetus shigensis has very asymmetrical external nares, comparable to the living sperm whale, Physeter catodon, and is in this way more derived than most of the contemporaneous fossil physeterids. At a time when other sperm whales were more highly evolved, Scaldicetus shigensis retained a primitive occipital shield, large tympanic bullae, and low tooth count, as in primitive Oligocene odontocetes such as Agorophiidae. It was a relict form in Middle Miocene time, and provides an indication of a primitive stage of sperm whale evolution heretofore undocumented. Fossils from elsewhere previously referred to as Scaldicetus, largely on the basis of tooth characters, range in age from Early Miocene to Plio-Pleistocene time. Cranial material that would clarify relationships is lacking for most of these, and this time range seems too long for a cetacean genus. Because of this simplistic approach to identifications, Scaldicetus is probably a grade taxon, not a natural biological grouping. However, the tooth morphology of Scaldicetus shigensis is correct for the genus Scaldicetus, so we provisionally assign it to this genus. Redefinition of the genus Scaldicetus and revision of the Physeteridae are beyond the scope of the present study. 相似文献