981 resultados para NEAR-INFRARED OBSERVATIONS
Resumo:
Mass spectrometric U-series dating of speleothems from Tangshan Cave, combined with ecological and paleoclimatic evidence, indicates that Nanjing Man, a typical Homo erectus morphologically correlated with Peking Man at Zhoukoudian, should be at least 580 k.y. old, or more likely lived during the glacial oxygen isotope stage 16 (similar to 620 ka). Such an age estimate, which is similar to 270 ka older than previous electron spin resonance and alpha counting U-series dates, has significant implications for the evolution of Asian H. erectus. Dentine and enamel samples from the coexisting fossil layer yield significantly younger apparent ages, that of the enamel sample being only less than one-fourth of the minimum age of Nanjing Man. This suggests that U uptake history is far more complex than existing models can handle. As a result, great care must be taken in the interpretation of electron spin resonance and U-series dates of fossil teeth.
Resumo:
Wistari Reef. within the southern Great Barrier Reef. is a shallow coral reef platform featuring a very clearly defined leeward accretionary wedge of carbonate sediments. The total global area of shallowly submerged coral reef has been quantified as 255 000 km(2). The question then becomes: What additional area of sediment of significant thickness is associated with the measured shallow reef areas T At Wistari Reef, the leeward sedimentary wedge has an area and a thickness that are roughly equal to the Holocene sediments that have accumulated on the platform. Several important observations can be made from these data. Firstly. the area of significant neritic carbonate sedimentation ( > 1 m/ka) associated with coral reefs is near 500000 km(2). Secondly, the production rate of neritic carbonates at Wistari Reef is almost 50%, less than the accumulation rate needed to obtain the volume of Holocene reef sediments observed. This implies that both production and accumulation neritic carbonate must have been more than a factor of two higher in the early to mid Holocene. (C) 2001 Elsevier Science B.V. All rights reserved.
Resumo:
The number of 1-factors (near 1-factors) that mu 1-factorizations (near 1-factorizations) of the complete graph K-v, v even (v odd), can have in common, is studied. The problem is completely settled for mu = 2 and mu = 3.
Resumo:
A new acanthocolpid, Tormopsolus attenuatus n. sp., is described from the carangid Seriola hippos from waters off the coast of SW Australia. A cladistic analysis of the genus using 31 morphological and metrical characters indicates that the closest species is T. asiatica Parukhin, 1976 status amend. (previously T. orientalis asiatica). T. attenuatus differs from T. asiatica in its smaller overall dimensions, more attenuated outline, relatively shorter post-testicular region, vitelline interruption at the level of the ovary, papillae on the oral sucker and, possibly, much longer genital atrium. Other similar species, T. orientalis Yamaguti, 1934 and T. medius Reimer, 1983, differ in having interruptions of the vitelline fields at the level of both testes and at the level of the ovary.
Resumo:
The prevalence of neoplasia in birds is generally low; however, in some species of companion and aviary birds, the incidence is high and neoplasia is a common cause of death. Surgical excision or limb amputation has been performed as the therapeutic plan. Chemotherapy in the treatment of avian neoplasia is largely empirical and poorly documented. For example, cisplatin has been used intralesionally in macaws (Ara species) with limited clinical success. Eight sulphur-crested cockatoos (Cacatua galerita), under general isoflurane anesthesia, were infused intravenously with cisplatin at 6.4 or 1.0 mg/kg over 1 hour and hydrated with lactated Ringer's solution for 1 hour before and 2 hours after cisplatin infusion. Birds were euthanatized 96 hours after infusion, except for 2 birds given the low cisplatin dose, which were euthanatized on day 35 after dosing. All birds tolerated the study procedure while under anesthesia. Blood pressure, heart rate, and respiratory rate did not change significantly. In the low-dose group, the mean cloacal temperature decreased significantly during the infusion period (P < .001) and then rose progressively to preinfusion values by 24 hours. Also in this group, the mean body weight tended to increase during the infusion period before significantly decreasing (P < .05) by 5% at 96 hours after dosing. At 24 hours after dosing, all birds were bright and eating. However, intermittent regurgitation and fecal changes (moist, dark green feces and yellow urates) occurred in 3 of 8 birds, especially those given the high dose. By 72 hours after dosing, droppings in the low-dose group were normal in appearance. One bird in the high-dose group died by 94 hours after dosing. Myelosuppression was not observed in any bird and at necropsy, no evidence of cisplatin toxicity was found except in 1 bird given the high cisplatin dose. On histology, this bird showed nephrotoxicity, and its serum uric acid levels and mean estimated white blood cell count increased significantly by 24 hours after dosing. This paper reports for the first time the effect of systemic cisplatin administration in birds and provides veterinarians data for formulating efficacious and safe protocols for platinum-containing compounds when treating neoplasia in parrots and other companion birds.