Not all cows are epidemiologically equal: quantifying the risks of bovine viral diarrhoea virus (BVDV) transmission through cattle movements     

M Carolyn Gates  Roger W Humphry  George J Gunn  Mark E J Woolhouse 《Veterinary research》2014,45(1)

Many economically important cattle diseases spread between herds through livestock movements. Traditionally, most transmission models have assumed that all purchased cattle carry the same risk of generating outbreaks in the destination herd. Using data on bovine viral diarrhoea virus (BVDV) in Scotland as a case example, this study provides empirical and theoretical evidence that the risk of disease transmission varies substantially based on the animal and herd demographic characteristics at the time of purchase. Multivariable logistic regression analysis revealed that purchasing pregnant heifers and open cows sold with a calf at foot were associated with an increased risk of beef herds being seropositive for BVDV. Based on the results from a dynamic within-herd simulation model, these findings may be partly explained by the age-related probability of animals being persistently infected with BVDV as well as the herd demographic structure at the time of animal introductions. There was also evidence that an epidemiologically important network statistic, “betweenness centrality” (a measure frequently associated with the potential for herds to acquire and transmit disease), was significantly higher for herds that supplied these particular types of replacement beef cattle. The trends for dairy herds were not as clear, although there was some evidence that open heifers and open lactating cows were associated with an increased risk of BVDV. Overall, these findings have important implications for developing simulation models that more accurately reflect the industry-level transmission dynamics of infectious cattle diseases.  相似文献   

Changes in Bull Sperm Kinematics after Single Layer Centrifugation     

Y Yulnawati  MC Abraham  D Laskowski  A Johannisson  JM Morrell 《Reproduction in domestic animals》2014,49(6):954-956

The objective of this study was to evaluate bull sperm kinematics after centrifugation through a single layer of a colloid [Single Layer Centrifugation (SLC)]. Ejaculates from 20 bulls were extended and stored at 4–6°C for 24 h during transport to the laboratory for SLC through Androcoll‐B, followed by measurement of sperm kinematics in all samples. Total motility (86% and 88% for uncentrifuged and SLC samples, respectively) and progressive motility (84% for both the groups) were similar (p > 0.05). In contrast, straightness (STR) (0.65 vs 0.69), linearity (LIN) (0.32 vs 0.35) and beat cross frequency (BCF) (22.3 vs 23.6 Hz) were significantly higher in the SLC‐selected samples than in the uncentrifuged samples, whereas velocity of the average path (VAP) (95 vs 90 μm/s), curvilinear velocity (VCL) (192 vs 180 μm/s), amplitude of lateral head deviation (ALH) (7 μm vs 6.5 μm) and hypermotility (49% vs 38%) were significantly decreased. The kinematics of the samples with the poorest motility was improved most by SLC. In conclusion, even though SLC had no direct effect on total and progressive motility, it appeared to have a positive influence on several other kinematic parameters that may be important for fertilization after artificial insemination.  相似文献   

Clay Mineral Composition of Borate Deposits and Associated Strata at Boron,California     

Gates GR 《Science (New York, N.Y.)》1959,130(3367):102

X-ray analyses of samples from lacustrine deposits in the Kramer borate district of California show that montmorillonite is the dominant clay mineral, and that illite is abundant in red siltstones, common in green and gray borate-barren claystones, and sparse in borate-bearing rocks. Kaolinite is present only in red siltstones. The distribution of clay minerals is related to the geologic history of borate deposition.  相似文献   

THE GARGOYLE AS A SCIENTIFIC INSTRUMENT     

Gates FC 《Science (New York, N.Y.)》1929,70(1806):148-149

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IDENTICAL TWINS IN A MOUSE CROSS     

Castle WE  Gates WH  Reed SC  Snell GD 《Science (New York, N.Y.)》1936,84(2191):581-582

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Detection and Characterization of the Cumulene Carbenes H2C5 and H2C6     

MC McCarthy  MJ Travers  A Kovacs  W Chen  SE Novick  CA Gottlieb  P Thaddeus 《Science (New York, N.Y.)》1997,275(5299):518-520

Two cumulene carbenes, H2C5 and H2C6, were detected in a supersonic molecular beam by Fourier transform microwave spectroscopy. Their rotational and leading centrifugal distortion constants were determined with high accuracy, such that the entire radio spectrum can now be calculated. Like the known carbenes H2C3 and H2C4, both molecules have singlet electronic ground states and linear carbon-chain backbones. They can be produced in sufficiently high concentrations in the laboratory that their electronic spectra, expected to lie in the visible, should be readily detectable by laser spectroscopy. The microwave spectra of other, more exotic isomers may be detectable as well.  相似文献   

THE USE OF "NEMBUTAL" AS AN ANESTHETIC FOR MICE     

Gates WH 《Science (New York, N.Y.)》1932,76(1972):349-350

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Uncertainties in carbon dioxide radiative forcing in atmospheric general circulation models   总被引：1，自引：0，他引：1  

Cess RD  Zhang MH  Potter GL  Barker HW  Colman RA  Dazlich DA  Del Genio AD  Esch M  Fraser JR  Galin V  Gates WL  Hack JJ  Ingram WJ  Kiehl JT  Lacis AA  Le Treut H  Li ZX  Liang XZ  Mahfouf JF  McAvaney BJ  Meleshko VP  Morcrette JJ  Randall DA  Roeckner E  Royer JF  Sokolov AP  Sporyshev PV  Taylor KE  Wang WC  Wetherald RT 《Science (New York, N.Y.)》1993,262(5137):1252-1255

Global warming caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.  相似文献   

UNIVERSITY AND EDUCATIONAL NOTES     

Gates FL 《Science (New York, N.Y.)》1928,68(1768):479-480

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APOGAMY IN OEligNOTHERA     

Gates RR 《Science (New York, N.Y.)》1909,30(776):691-694

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