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Slight Rise (slight + rise)
Selected AbstractsReconstruction of the Ross Ice Drainage System, Antarctica, at the Last Glacial MaximumGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2-3 2000George H. Denton We present here a revised reconstruction of the Ross ice drainage system of Antarctica at the last glacial maximum (LGM) based on a recent convergence of terrestrial and marine data. The Ross drainage system includes all ice flowlines that enter the marine Ross Embayment. Today, it encompasses one-fourth of the ice-sheet surface, extending far inland into both East and West Antarctica. Grounding lines now situated in the inner Ross Embayment advanced seaward at the LGM (radiocarbon chronology in Denton and Marchant 2000 and in Hall and Denton 2000a, b), resulting in a thick grounded ice sheet across the Ross continental shelf. In response to this grounding in the Ross (and Weddell) Embayment, ice-surface elevations of the marine-based West Antarctic Ice Sheet were somewhat higher at the LGM than at present (Steig and White 1997; Borns et al. 1998; Ackert et al. 1999). At the same time, surface elevations of the East Antarctic Ice Sheet inland of the Transantarctic Mountains were slightly lower than now, except near outlet glaciers that were dammed by grounded ice in the Ross Embayment. The probable reason for this contrasting behavior is that lowered global sea level at the LGM, from growth of Northern Hemisphere ice sheets, caused widespread grounding of the marine portion of the Antarctic Ice Sheet, whereas decreased LGM accumulation led to slight surface lowering of the interior terrestrial ice sheet in East Antarctica. Rising sea level after the LGM tripped grounding-line recession in the Ross Embayment, which has probably continued to the present day (Conway et al. 1999). Hence, gravitational collapse of the grounded ice sheet from the Ross Embayment, accompanied by lowering of the interior West Antarctic ice surface and of outlet glaciers in the Transantarctic Mountains, occurred largely during the Holocene. At the same time, increased Holocene accumulation caused a slight rise of the inland East Antarctic ice surface. [source] Measles virus protein-specific IgM, IgA, and IgG subclass responses during the acute and convalescent phase of infectionJOURNAL OF MEDICAL VIROLOGY, Issue 2 2004H.S. El Mubarak Abstract The availability of new generation serological assays allowed re-evaluation of the antibody response to measles virus. IgM, IgA, total IgG, and IgG subclass responses were studied to the three major immunogenic measles virus proteins: the fusion protein (F), haemagglutinin (H), and nucleoprotein (N). Plasma samples were obtained from clinically diagnosed measles cases (n,=,146) in Khartoum (Sudan) within a week after onset of the rash. Convalescent phase samples were collected from 32 of 117 laboratory-confirmed measles cases at different time points after onset of rash. Glycoprotein-specific IgM, IgG, and IgA antibody levels correlated well to the N-specific response. For IgG and IgA, responses to F were higher than to H. IgA antibody levels were undetectable in about one third of the laboratory-confirmed cases during the acute phase, but positive in all patients tested 1,4 weeks after infection. IgM levels declined rapidly and were lost 3,6 months after infection. IgA levels declined slowly during the first year but did not return to background levels during the subsequent 2 years. IgG avidity maturation was detected during a 3,6 month period after infection. The predominant IgG subclasses during the acute phase were IgG1 and IgG3. The latter was lost in the convalescent phase, while the IgG4 isotype showed a slight rise afterwards. Interestingly, acute phase IgG3 and IgA responses were associated, and were only detected in samples with high IgG. This study provides a comprehensive perspective on the antibody response to wild-type measles virus infection. J. Med. Virol. 72:290,298, 2004. © 2004 Wiley-Liss, Inc. [source] Response of superoxide dismutase isoenzymes in tomato plants (Lycopersicon esculentum) during thermo-acclimation of the photosynthetic apparatusPHYSIOLOGIA PLANTARUM, Issue 3 2007Daymi Camejo Seedlings of Lycopersicon esculentum Mill. var. Amalia were grown in a growth chamber under a photoperiod of 16 h light at 25°C and 8 h dark at 20°C. Five different treatments were applied to 30-day-old plants: Control treatment (plants maintained in the normal growth conditions throughout the experimental time), heat acclimation (plants exposed to 35°C for 4 h in dark for 3 days), dark treatment (plants exposed to 25°C for 4 h in dark for 3 days), heat acclimation plus heat shock (plants that previously received the heat acclimation treatment were exposed to 45°C air temperature for 3 h in the light) and dark treatment plus heat shock (plants that previously received the dark treatment were exposed to 45°C air temperature for 3 h in the light). Only the heat acclimation treatment increased the thermotolerance of the photosynthesis apparatus when the heat shock (45°C) was imposed. In these plants, the CO2 assimilation rate was not affected by heat shock and there was a slight and non-significant reduction in maximum carboxylation velocity of Rubisco (Vcmax) and maximum electron transport rate contributing to Rubisco regeneration (Jmax). However, the plants exposed to dark treatment plus heat shock showed a significant reduction in the CO2 assimilation rate and also in the values of Vcmax and Jmax. Chlorophyll fluorescence measurements showed increased thermotolerance in heat-acclimated plants. The values of maximum chlorophyll fluorescence (Fm) were not modified by heat shock in these plants, while in the dark-treated plants that received the heat shock, the Fm values were reduced, which provoked a significant reduction in the efficiency of photosystem II. A slight rise in the total superoxide dismutase (SOD) activity was found in the plants that had been subjected to both heat acclimation and heat shock, and this SOD activity was significantly higher than that found in the plants subjected to dark treatment plus heat shock. The activity of Fe-SOD isoenzymes was most enhanced in heat-acclimated plants but was unaltered in the plants that received the dark treatment. Total CuZn-SOD activity was reduced in all treatments. Darkness had an inhibitory effect on the Mn-SOD isoenzyme activity, which was compensated by the effect of a rise in air temperature to 35°C. These results show that the heat tolerance of tomatoplants may be increased by the previous imposition of a moderately high temperature and could be related with the thermal stability in the photochemical reactions and a readjustment of Vcmax and Jmax. Some isoenzymes, such as the Fe-SODs, may also play a role in the development of heat-shock tolerance through heat acclimation. In fact, the pattern found for these isoenzymes in heat-acclimated Amalia plants was similar to that previously described in other heat-tolerant tomato genotypes. [source] Effects of the Cardiff Bay tidal barrage on the abundance, ecology and behaviour of shelducks Tadorna tadornaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2009Peter N. Ferns Abstract 1.Closure of the Taff/Ely Estuary by the Cardiff Bay barrage in 1999 resulted in the replacement of intertidal mudflats by a permanent freshwater lake. This led to an 89% reduction in the population of shelducks Tadorna tadorna. 2.The birds switched from foraging mainly for Nereis diversicolor and Hydrobia ulvae by scything with the bill as they walked across the mudflats at low tide, to feeding on benthic chironomid midge larvae while swimming in shallow water around the margins of the lake. 3.The population decline occurred as a consequence of a decrease in the area available for foraging,,,from about 1,km2 of mudflats to about 0.1,km2 of water shallow enough for shelducks to reach the bottom when dabbling, head dipping and upending. 4.Contrary to expectation, the amount of time shelducks spent feeding was similar pre- and post-barrage, and their body and plumage condition improved. 5.A tidal rhythm in activity persisted, with a reduced amount of feeding at high tide, probably because of the slight rise in water levels that sometimes occurred at this time. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||