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M. Rogerson T.J. Kouwenhoven G.J. van der Zwaan B.J. O'Neill C.J. van der Zwan G. Postma K. Kleverlaan H. Tijbosch 《Marine Micropaleontology》2006,60(4):295-318
We present benthic foraminiferal assemblage data from an exhumed Miocene canyon and fan system from the Tabernas Basin (SE Spain). The presence of good indicator taxa and unique assemblages occupying specific environments allows the distinction of slope, canyon and fan environments within the Tabernas Basin by foraminiferal assemblages alone. Five assemblages are defined on the basis of the occurrence of the indicator taxa. Primary control on the distribution of these assemblages is consistent with trends of physical disturbance and consequent defaunation. Barren samples, which are predominantly found in high-energy parts of the proximal canyon, are recognized as representing recently defaunated substrates (i.e. early successional assemblages). High diversity assemblages containing a high abundance of agglutinated taxa are recognised in the undisturbed slope sequences as being the regional equilibrium (“climax”) fauna. Intermediate between these end-members are assemblages with low diversity, dominated by calcareous taxa typically found in the relatively low-energy canyon and fan environments, which are recognized as representing the middle phases of the ecological succession. Two further assemblages, a low diversity assemblage typified by Cassidulina laevigata and Bulimina costata and a very low diversity assemblage dominated (> 10% of all benthic tests) by Globobulimina spp., are restricted to low-energy parts of the canyon and fan, and are absent from the proximal canyon and slope. The composition of these assemblages indicate that nutrient supply/oxygenation is a secondary control on the palaeoecology of the canyon system. A conceptual model for the recolonisation of defaunated substrates in El Buho Canyon is proposed, in which either an oligotrophic climax assemblage or a eutrophic climax assemblage can be achieved at the completion of recolonisation of defaunated substrates, depending on environmental conditions. 相似文献
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The respiratory sensation and some routine cardiorespiratory parameters were studied on native Highlanders from the Argentine
Andes and on Lowlanders from Europe, already tested during previous high altitude expeditions. The tests were performed at
various altitude levels from 2688m e.i., the village altitude for Highlanders, to 5600m during an expedition to Mt. Aconcagua
(6990m). At rest, the perception of 4 external inspiratory resistive loads (ranged between 2.5 and 13 cm.H2O.L-1.s) can allow
us to fix by discrimination the sensitivity index P(A) independently of response bias (B) according to Sensory Decision Theory
(SDT). The Andean highlanders did not experience the respiratory sensation at the same limits as the European lowlanders well
adaptated to high altitude. At higher altitudes than their village altitude, their respiratory sensation presented a lower
threshold of perception and a weaker discrimination which might be partly explained by the evolution of some parameters of
their cardio-respiratory function when altitude increased. Indeed, in response to high altitude hypoxia (5600m), they increased
their respiratory frequency and not their minuteventilation or mouth pressure. This chosen ventilatory pattern was opposite
to the one chosen by the Lowlanders and did not allow for sufficient adaptation to a more important altitude hypoxia than
that of their village altitude. In conclusion, the Andean highlanders wellbeing adapted to their village altitude, exhibited
a difficult acclimatization to higher altitudes which might be due to the characteristics of their respiratory sensation.
These results might explain their weak physical performances during ascent to the Mt. Aconcagua summit in spite of special
training. 相似文献
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Sérgio A Batista Gifone A Rocha Andreia MC Rocha Ivan EB Saraiva Mônica MDA Cabral Rodrigo C Oliveira Dulciene MM Queiroz 《BMC microbiology》2011,11(1):61
Background
Helicobacter pylori infection is one of the most common infections worldwide and is associated with gastric cancer and peptic ulcer. Bacterial virulence factors such as CagA have been shown to increase the risk of both diseases. Studies have suggested a causal role for CagA EPIYA polymorphisms in gastric carcinogenesis, and it has been shown to be geographically diverse. We studied associations between H. pylori CagA EPIYA patterns and gastric cancer and duodenal ulcer, in an ethnically admixed Western population from Brazil. CagA EPIYA was determined by PCR and confirmed by sequencing. A total of 436 patients were included, being 188 with gastric cancer, 112 with duodenal ulcer and 136 with gastritis. 相似文献48.
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