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   

Effect of four sedative and anesthetic protocols on quantitative thyroid scintigraphy in euthyroid cats     

Schaafsma IA  Pollak YW  Barthez PY 《American journal of veterinary research》2006,67(8):1362-1366

OBJECTIVES: To determine the effect of sedation and anesthesia on thyroid and salivary gland uptake of technetium Tc 99m pertechnetate ((99m)TcO(4)) in euthyroid cats. ANIMALS: 6 euthyroid cats. PROCEDURES: Thyroid scintigraphy was performed by use of a high-resolution low-energy parallel-hole collimator after IV injection of 117 to 133 MBq (3.16 to 3.59 mCi) of (99m)TcO(4)(-). The procedure was performed 4 times on each cat during different sedative and anesthetic protocols in a rotating schedule as follows: propofol, ketamine-midazolam-atropine, ketaminemidazolam, and medetomidine. Regions of interest were drawn around thyroid and salivary glands and counts corrected for background and decay. Percentage of (99m)TcO(4)(-) uptake in salivary and thyroid glands and thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio were calculated at 20 and 40 minutes. Relative effects of anesthesia and sedation on salivary and thyroid gland (99m)TcO(4)(-) uptake were compared. RESULTS: Significant differences among sedativeanesthetic protocols were found for thyroid gland (99m)TcO(4)(-) uptake, salivary gland (99m)TcO(4)(-) uptake, and thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio. Thyroid gland (99m)TcO(4)(-) uptake for the ketamine-midazolam protocol at 20 and 40 minutes after (99m)TcO(4)(-) administration was significantly higher than for the propofol protocol. A significant difference in salivary gland(99m) TcO(4)(-) uptake was found between ketamine-midazolam and ketamine-midazolam-atropine protocols at 40 minutes. The thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio for the ketamine-midazolam protocol was significantly higher at 40 minutes than for propofol or ketamine-midazolam-atropine protocols. CONCLUSIONS AND CLINICAL RELEVANCE: Sedation and anesthesia have a significant effect on thyroid and salivary gland (99m)TcO(4) uptake in euthyroid cats that may interfere with thyroid scintigraphic image interpretation.  相似文献   

Farm management factors associated with bulk tank somatic cell count in Irish dairy herds     

PT Kelly  K O'Sullivan  DP Berry  SJ More  WJ Meaney  EJ O'Callaghan  B O'Brien 《Irish veterinary journal》2009,62(Z4):S45

The relationship between bulk tank somatic cell count (SCC) and farm management and infrastructure was examined using data from 398 randomly selected, yet representative, Irish dairy farms where the basal diet is grazed grass. Median bulk tank SCC for the farms was 282,887 cells/ml ranging from 82,209 to 773,028 cells/ml. Two questionnaires were administered through face-to-face contact with each farmer. Herd-level factors associated with bulk tank SCC were determined using linear models with annual somatic cell score (i.e., arithmetic mean of the natural logarithm of bulk tank SCC) included as the dependent variable. All herd level factors were analysed individually in separate regression models, which included an adjustment for geographical location of the farm; a multiple regression model was subsequently developed. Management practices associated with low SCC included the use of dry cow therapy, participation in a milk recording scheme and the use of teat disinfection post-milking. There was an association between low SCC and an increased level of hygiene and frequency of cleaning of the holding yard, passageways and cubicles. Herd management factors associated with bulk tank SCC in Irish grazing herds are generally in agreement with most previous studies from confinement systems of milk production.  相似文献   

Y are you not pregnant: identification of Y chromosome segments in female cattle with decreased reproductive efficiency     

McDaneld TG  Kuehn LA  Thomas MG  Snelling WM  Sonstegard TS  Matukumalli LK  Smith TP  Pollak EJ  Keele JW 《Journal of animal science》2012,90(7):2142-2151

Reproductive efficiency is of economic importance in commercial beef cattle production, since failure to achieve pregnancy reduces the number of calves marketed. Identification of genetic markers with predictive merit for reproductive success would facilitate early selection of females and avoid inefficiencies associated with sub-fertile cows. To identify regions of the genome harboring variation affecting reproductive success, we applied a genome-wide association approach based on the >700,000 SNP marker assay. To include the largest number of individuals possible under the available budget, cows from several populations were assigned to extremes for reproductive efficiency, and DNA was pooled within population and phenotype before genotyping. Surprisingly, pools prepared from DNA of low reproductive cattle returned fluorescence intensity data intermediate between fertile females and males for SNP mapped to the Y chromosome (i.e., male sex chromosome). The presence of Y-associated material in low reproductive heifers or cows was confirmed by Y-directed PCR, which revealed that 21 to 29% of females in the low reproductive category were positive by a Y chromosome PCR test normally used to sex embryos. The presence of the Y chromosome anomaly was further confirmed with application of additional Y-specific PCR amplicons, indicating the likelihood of the presence of some portion of male sex chromosome in female cattle in various beef cattle herds across the U.S. Discovery of this Y anomaly in low reproductive females may make an important contribution to management of reproductive failures in beef cattle operations.  相似文献   

Rank comparisons of maize germplasm evaluations repeated over locations and years     

Linda M. Pollak  Bryce C. Abel 《Genetic Resources and Crop Evolution》1992,39(3):141-147

Summary The availability of yield and combining ability data on germplasm bank accessions may increase their use, but collection of this type of data from a large number of accessions is difficult and expensive. This study was conducted to determine whether the members of the top 20% of evaluated accessions changed so extensively, when evaluations were repeated over locations and years, that initial evaluations conducted in one location were misleading. Thirty-four Yugoslavian maize (Zea mays L.) accessions were evaluated for yield per se and as test crosses to eight testers in three Iowa locations during three years. Overall best accessions were assumed to be those that performed best, as judged by all of the data. The highest yields occurred in Kanawha, Iowa, in 1987, which had favorable climatic conditions for maize production, whereas the lowest were in Kanawha in 1985, which had the least desirable conditions. In these two years, however, one testcross evaluation placed more of the actual overall best accessions in the top 20% of the highest yielding accessions for that particular evaluation. More overall best were ranked in the top 20% in the year with less desirable conditions. The efficiency of an environment in ranking the best accessions in the top 20%, while excluding the worst 20%, ranged from 16% in Nashua, Iowa, in 1985 to 48% in Nashua in 1986. Repeating evaluation trials over years was no more efficient than repeating them over locations, or vice versa. Initial germplasm evaluations should be repeated either over locations or years, to increase the probability of identifying the rare agronomically valuable accessions and eliminating poorer-yielding ones.  相似文献   

Differential Rotation and Dynamics of the Solar Interior     

MJ Thompson  J Toomre  ER Anderson  HM Antia  G Berthomieu  D Burtonclay  SM Chitre  J Christensen-Dalsgaard  T Corbard  M DeRosa  CR Genovese  DO Gough  DA Haber  JW Harvey  F Hill  R Howe  SG Korzennik  AG Kosovichev  JW Leibacher  FP Pijpers  J Provost  EJ Rhodes  J Schou  T Sekii  PB Stark  PR Wilson 《Science (New York, N.Y.)》1996,272(5266):1300-1305

Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.  相似文献   

Changes in serum proteins in amphibian metamorphosis     

FRIEDEN E  HERNER AE  FISH L  LEWIS EJ C 《Science (New York, N.Y.)》1957,126(3273):559-560

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Seasonal and spatial variation of extractable trace metal fractions in topsoils under mixed forest     

Walter W. Wenzel  Guntram Alge  Winfried E. H. Blum  Anton Brandstetter  Michael A. Pollak  Christian Riedler  Andreas Schulte 《植物养料与土壤学杂志》1996,159(4):333-336

Metal extractability from soils may be affected by analytical errors, sample preparation, inaccurate sampling as well as by natural variation in space and time. During one year, we sampled the Ah horizons of a forested Luvi-Calcaric Cambisol from 43 subplots in a visually homogeneous area of 0.5 ha six times to determine the spatial and seasonal variation of pH, OC, and Fe, Mn, Cr, Cu, Ni, Pb and Zn extractable by 0.1 M BaCl₂ and 0.05 M Na₂ETDA. As indicated by a two-way ANOVA, the spatial and seasonal variations of all parameters were significant at p < 0.01. The metal-specific ranges of seasonal variation varied between 21% and 90% of the minima for Na₂EDTA, and 15% and 71% for 0.1 M BaCl₂. The error due to within-subplot variability and inaccurate sampling, tested by sampling twice in April 1992, was small compared to the natural seasonal and spatial variation. The relative differences between the means of the two samplings tended to increase with the coefficients of spatial variation, suggesting an increasing contribution of within-subplot variability to the sampling error. The study shows that both spatial and seasonal variation of extractable metal fractions may bias the analysis of mobile metal fractions in a rarely predictable way.  相似文献   

Histological changes to the skin of Merino sheep following deep dermal and subcutaneous injections of sodium lauryl sulfate     

EJ Lee  JT Rothwell 《Australian veterinary journal》2010,88(4):146-150

Objectives To characterise the changes caused to sheep skin by deep dermal and subcutaneous injections of sodium lauryl sulfate (SLS) and describe the subsequent healing process. Procedure On 6 sheep 20 small areas of skin were each given deep dermal and subcutaneous injections of 0.2 mL of 7% SLS. Biopsies were collected at intervals up to 28 days after treatment and the histological changes in each of the treated skin samples were assessed and graded. Results There was no evidence of alterations in behaviour, weight gain or appetite of the sheep following the injections. Initial swelling of the treated site subsided by day 14, leaving a firm, slightly raised crust. At day 21, the treated area was depressed and covered by a scab, which sloughed completely by day 28. There was necrosis of the subcutis and deep dermis 2 min after treatment, followed by inflammation, fibroplasia, angiogenesis and tissue remodelling. Conclusion Injection of SLS caused almost immediate local necrosis followed by eschar formation, sloughing and scarring of treated skin. Deep dermal and subcutaneous SLS is potentially useful as a chemical alternative to mulesing.  相似文献   

Canine mammary mixed tumours: immunohistochemical expressions of EGFR and HER‐2     

AC Bertagnolli  E Ferreira  EJ Dias  GD Cassali 《Australian veterinary journal》2011,89(8):312-317

Background Benign mixed tumours (BMTs) are frequently found in the mammary glands of female dogs, but the factors determining malignant transformation in these tumours are unknown. Objective To evaluate the expression of the oncoproteins, human epidermal growth factor receptor 2 (HER‐2) and epidermal growth factor receptor (EGFR), in 46 carcinomas in BMTs (CBMTs) and to verify their possible association with the malignancy of the tumours. Methods Immunohistochemical expression was analysed in benign and malignant components separately, and then compared with 74 cases of BMTs. Results Among the CBMTs, positivity for HER‐2 was found in the benign histological component of 4.3% (2/46), in the malignant epithelial non‐invasive component of 14.8% (4/27) and in the malignant invasive epithelial component of 13.6% (6/44) of cases. Two of the 24 (8.3%) BMTs were positive for HER‐2. There was no relationship between HER‐2 and the tumour components. There was no significant difference between BMTs and CBMTs. Positivity for EGFR was found in the benign component of 17.4% (8/46) of the CBMTs, in the malignant epithelial non‐invasive component of 40.7% (11/27%) and in the invasive epithelial malignant component of 45.4% (20/44). EGFR positivity was significantly associated with the invasive component of CBMTs. Conclusion EGFR may contribute to malignant epithelial transformation of BMTs. In contrast, HER‐2 overexpression may not be associated with the acquisition of a malignant epithelial phenotype.  相似文献