Synchronous climate changes in antarctica and the north atlantic     

EJ Steig  EJ Brook  JWC White  CM Sucher  ML Bender  SJ Lehman  DL Morse  ED Waddington  GD Clow 《Science (New York, N.Y.)》1998,282(5386):92-95

Central Greenland ice cores provide evidence of abrupt changes in climate over the past 100,000 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic, confirming the link between millennial-scale climate variability and ocean thermohaline circulation. It is shown here that two of the most prominent North Atlantic events-the rapid warming that marks the end of the last glacial period and the Bolling/Allerod-Younger Dryas oscillation-are also recorded in an ice core from Taylor Dome, in the western Ross Sea sector of Antarctica. This result contrasts with evidence from ice cores in other regions of Antarctica, which show an asynchronous response between the Northern and Southern Hemispheres.  相似文献   

Promotion of the cycling of diet-enhancing nutrients by african grazers   总被引：2，自引：0，他引：2  

SJ McNaughton  FF Banyikwa  MM McNaughton 《Science (New York, N.Y.)》1997,278(5344):1798-1800

Experiments in Serengeti National Park, Tanzania, provide direct evidence that large, free-ranging mammalian grazers accelerate nutrient cycling in a natural ecosystem in a way that enhances their own carrying capacity. Both nitrogen and sodium were at considerably higher plant-available levels in soils of highly grazed sites than in soils of nearby areas where animal density is sparse. Fencing that uncoupled grazers and soils indicated that the animals promote nitrogen availability on soils of inherently similar fertility and select sites of higher sodium availability as well as enhancing that availability.  相似文献   

The Importance of Having Zinc During In Vitro Maturation of Cattle Cumulus–Oocyte Complex: Role of Cumulus Cells     

JM Anchordoquy  JP Anchordoquy  MA Sirini  SJ Picco  P Peral‐García  CC Furnus 《Reproduction in domestic animals》2014,49(5):865-874

The aim of this study was to investigate the influence of zinc (Zn) on the health of cumulus–oocyte complex (COC) during in vitro maturation (IVM). Experiments were designed to evaluate the effect of Zn added to IVM medium on: DNA integrity, apoptosis, cumulus expansion and superoxide dismutase (SOD) activity of cumulus cells (CC). Also, role of CC on Zn transport during IVM was evaluated on oocyte developmental capacity. DNA damage and early apoptosis were higher in CC matured with 0 μg/ml Zn compared with 0.7, 1.1 and 1.5 μg/ml Zn (p < 0.05). Cumulus expansion did not show differences in COC matured with or without Zn supplementation (p > 0.05). Superoxide dismutase activity was higher in COC matured with 1.5 μg/ml Zn than with 0 μg/ml Zn (p < 0.05). Cleavage and blastocyst rates were recorded after IVM in three maturation systems: intact COCs, denuded oocytes with cumulus cells monolayer (DO + CC) and denuded oocytes (DO). Cleavage rates were similar when COC, DO + CC or DO were matured with 1.5 μg/ml Zn compared with control group (p > 0.05). Blastocyst rates were significantly higher in COC than in DO + CC and DO with the addition of 1.5 μg/ml Zn during IVM (p < 0.01). Blastocyst quality was enhanced in COC and DO + CC compared with DO when Zn was added to IVM medium (p < 0.001). The results of this study indicate that Zn supplementation to IVM medium (i) decreased DNA damage and apoptosis in CC; (ii) increased SOD activity in CC; (iii) did not modify cumulus expansion and cleavage rates after in vitro fertilization; (iv) improved subsequent embryo development up to blastocyst stage; and (v) enhanced blastocyst quality when CC were present either in intact COC or in coculture during IVM.  相似文献   

Assessment of organoleptic postmortem inspection techniques for bovine offal     

FA UZAL  SJ MORE  B. DOBRENOV  WR KELLY 《Australian veterinary journal》2002,80(1):70-74

Objective To evaluate organoleptic postmortem inspection techniques for bovine livers and kidneys.
Study design At Australian export abattoirs, bovine liver and kidneys are assessed and graded by qualified meat inspectors during normal operations. Over a 12-month period at a large abattoir in eastern Australia during 1997 and 1998, a sample of these organs was reassessed independently using a range of pathological and microbiological methods. Agreement between routine inspection and independent assessment was evaluated using methods of inter-rater agreement.
Results A total of 944 livers and 1374 kidneys were included in the study. All of these organs had been classified during routine inspection. The authors examined 363 livers and 329 kidneys both grossly and histologically, including 36 livers and 14 kidneys that were also subjected to microbiological examination. All other organs were only examined grossly. There was only a moderate level of agreement between the routine and independent assessment methods. For livers, the percentage agreement was 80.2%, McNemar's test of symmetry 55.2 (3 degrees of freedom, P < 0.001) and kappa 0.63. For kidneys, the percentage agreement was 67.8%, McNemar's test of symmetry 9.9 (1df, P = 0.002) and kappa 0.35.
Conclusions The results reinforce concerns from a number of authors about organoleptic postmortem inspection. Risk assessment methodologies offer the opportunity to modify inspection techniques in a manner that is most relevant to current public health concerns.  相似文献   

Spatial analysis of seroconversion of sentinel cattle to bluetongue viruses in Queensland     

MP WARD  TE CARPENTER  SJ JOHNSON 《Australian veterinary journal》1996,74(2):128-131

Objective To assess quantitatively the spatial distribution of seroconversion of Queensland cattle to bluetongue viruses.
Design A sentinel herd study. Sample population Sixty-nine sentinel herds at 30 locations.
Procedure Spatial clustering of seroconversion to blue-tongue viruses was investigated during the period from 1990 to 1994.
Results Seroconversion to only two bluetongue virus serotypes, 1 and 21, was observed. The 14 herds, in which seroconversion to bluetongue virus serotype 1 was detected, were located only along the eastern coastal and subcoastal region of Queensland, and were significantly (P < 0.05) clustered. Locations at which seroconversion to serotype 21 was detected, were not significantly clustered. The results generally agree with field observations, except for the failure to detect seroconversion to bluetongue viruses in north-western Queensland.
Conclusion Bluetongue infection of cattle in north-western Queensland may be temporally sporadic. The dominance of serotype 1 in the Queensland cattle population may be the result of differential transmission by potential vector species. Long-term surveillance programs are important for defining disease status of animal populations.  相似文献   

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SJ JOHNSON 《Australian veterinary journal》1992,69(3):70-70

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Large-scale molecular dynamics simulations of dislocation intersection in copper     

SJ Zhou  DL Preston  PS Lomdahl  DM Beazley 《Science (New York, N.Y.)》1998,279(5356):1525-1527

The results of massively parallel three-dimensional molecular dynamics simulations of the perpendicular intersection of extended dislocations in copper are reported. The intersection process, which involves three of the four possible 111 glide planes in the face-centered cubic lattice, begins with junction formation, followed by unzipping, partial dislocation bowing, cutting, and, finally, unit jog formation. The investigation provides insights into this complex atomistic process, which is currently not accessible to experimental investigation.  相似文献   

Past temperatures directly from the greenland ice sheet   总被引：3，自引：0，他引：3  

D Dahl-Jensen  K Mosegaard  N Gundestrup  GD Clow  SJ Johnsen  AW Hansen  N Balling 《Science (New York, N.Y.)》1998,282(5387):268-271

A Monte Carlo inverse method has been used on the temperature profiles measured down through the Greenland Ice Core Project (GRIP) borehole, at the summit of the Greenland Ice Sheet, and the Dye 3 borehole 865 kilometers farther south. The result is a 50, 000-year-long temperature history at GRIP and a 7000-year history at Dye 3. The Last Glacial Maximum, the Climatic Optimum, the Medieval Warmth, the Little Ice Age, and a warm period at 1930 A.D. are resolved from the GRIP reconstruction with the amplitudes -23 kelvin, +2.5 kelvin, +1 kelvin, -1 kelvin, and +0.5 kelvin, respectively. The Dye 3 temperature is similar to the GRIP history but has an amplitude 1.5 times larger, indicating higher climatic variability there. The calculated terrestrial heat flow density from the GRIP inversion is 51.3 milliwatts per square meter.  相似文献   

Alteration of oceanic volcanic glass: textural evidence of microbial activity     

MR Fisk  SJ Giovannoni  IH Thorseth 《Science (New York, N.Y.)》1998,281(5379):978-980

The subsurface biosphere may constitute as much as 50 percent of Earth's biomass. Direct and indirect evidence suggests that an extensive biosphere exists in the rocks below the sea floor. This survey of basalts of the Atlantic, Pacific, and Indian Oceans supports the hypothesis that bacteria have colonized much of the upper oceanic crust, which has a volume estimated at 10(18) cubic meters. Although this is the largest habitat on Earth, its low abundance of bacteria constitutes much less than 1 percent of Earth's biomass.  相似文献   

Global trends in milk quality: implications for the Irish dairy industry     

SJ More 《Irish veterinary journal》2009,62(Z4):S5

The quality of Irish agricultural product will become increasingly important with the ongoing liberalisation of international trade. This paper presents a review of the global and Irish dairy industries; considers the impact of milk quality on farm profitability, food processing and human health, examines global trends in quality; and explores several models that are successfully being used to tackle milk quality concerns. There is a growing global demand for dairy products, fuelled in part by growing consumer wealth in developing countries. Global dairy trade represents only 6.2% of global production and demand currently outstrips supply. Although the Irish dairy industry is small by global standards, approximately 85% of annual production is exported annually. It is also the world's largest producer of powdered infant formula. Milk quality has an impact on human health, milk processing and on-farm profitability. Somatic cell count (SCC) is a key measure of milk quality, with a SCC not exceeding 400,000 cells/ml (the EU milk quality standard) generally accepted as the international export standard. There have been ongoing improvements in milk quality among both established and emerging international suppliers. A number of countries have developed successful industry-led models to tackle milk quality concerns. Based on international experiences, it is likely that problems with effective translation of knowledge to practice, rather than incomplete knowledge per se, are the more important constraints to national progress towards improved milk quality.  相似文献