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61.
Variations in the ratio of K(2)O to SiO(2) in andesitic rocks suggest early and middle Cenozoic subduction beneath the western United States along two subparallel imbricate zones dipping about 20 degrees eastward. The western zone emerged at the continental margin, but the eastern zone was entirely beneath the continental plate. Mesozoic subduction apparently occurred along a single steeper zone. 相似文献
62.
Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere 总被引:19,自引:0,他引:19
PJ Sellers RE Dickinson DA Randall AK Betts FG Hall JA Berry GJ Collatz AS Denning HA Mooney CA Nobre N Sato CB Field A Henderson-Sellers 《Science (New York, N.Y.)》1997,275(5299):502-509
Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide. 相似文献
63.
Since the introduction of the genus Arcobacter in 1991, the association of Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii with humans and animals has been clearly established. These bacteria have been detected world wide in products of animal origin and in healthy animals as well as in surface water. A fourth species Arcobacter cibarius was recently discovered on chicken carcasses. Although evidence was found for the connection of Arcobacter spp. with human and animal illness, Arcobacter spp. can be pathogens, opportunistic pathogens and commensals. Their potential as zoonotic foodborne and waterborne agents, the routes of transmission and the pathogenic mechanisms of these bacteria are largely unknown. Production of toxins or other virulence factors has not been demonstrated but adhesive and/or invasive properties were apparent. Antibiotic resistance is present in Arcobacter strains to significant levels. The tools to genetically access Arcobacter-like transformation of strains, construction of mutants are not yet available. Nor have genes (i.e. potential virulence factors) been cloned, expressed and characterized in other host organisms. Therefore those interested in the microbiology of these organisms eagerly await publication of the complete nucleotide sequence of the Arcobacter genome. The abundant presence of four Arcobacter species in foods of animal origin and the recovery of these bacteria from surface and drinking water suggest an important role of these bacteria as foodborne or waterborne agent and possibly as zoonotic agent. 相似文献
64.
The relation between farm specific factors and prevalence of Clostridium difficile in slaughter pigs
Keessen EC van den Berkt AJ Haasjes NH Hermanus C Kuijper EJ Lipman LJ 《Veterinary microbiology》2011,154(1-2):130-134
Foodborne ingestion through pork products of Clostridium difficile has been suggested a possible route of transmission of C difficile from pigs to humans. To determine whether C. difficile bacteria are present in the intestines of slaughter pigs, rectum contents of 677 slaughter pigs from 52 farms were collected at the slaughterhouse. Data on farm specific factors were collected and the association of these factors with the presence of C. difficile in pig herds from 39 farms was assessed. The prevalence of C. difficile and the ribotypical diversity that were found in this study were much higher than previously reported in literature, with an overall C. difficile prevalence of 8.6% (58/677). Sixteen distinct C. difficile ribotypes were identified, predominantly type 078 (31.0%, 18/58). This type is also commonly found in humans with C. difficile infection (CDI). Both on individual pig level and on herd level, no significant difference between the prevalence of C. difficile in pigs derived from conventional or organic farming types was detected. Farm system, size, and presence of other animal species on the farm did not result in significant different prevalences of C. difficile. 相似文献
65.
A fusion defect of the proximal and middle phalanges of both hindlimbs, osteochondrosis dissecans of the distal interphalangeal joints of the forelimbs, and subluxation of all 4 distal interphalangeal joints occurred in a Standardbred filly. Lameness was the first abnormality noted and was observed at one week of age in the left forelimb and progressed until all 4 limbs were affected by 5 weeks of age. On radiographs of both forelimbs, the distal interphalangeal joints were subluxated with irregularity and lucency of subchondral bone. On radiographs of the distal hindlimbs, there was a subluxation of both distal interphalangeal joints and loss of the proximal interphalangeal joint spaces with fusion of the proximal and middle phalanges. The foal was euthanised. On necropsy, there were focal areas of erosion of articular cartilage in the distal interphalangeal joint of both forelimbs. The proximal and middle phalanges of both hindlimbs were fused. Histopathological examination of the distal interphalangeal joint of the right foreleg showed loss of articular cartilage and degenerative changes in the exposed subchondral bone. 相似文献
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68.
It happens every summer: 'Swimming prohibited because of cyanobacteria'. Blooming of these toxine producing bacteria in warm summer months is a well known risk for swimming human beings. But how big is this risk for swimming dogs? And how big are other risks? In this article these risks are assessed for dogs that occasionally swim in surface water during the summer in the Netherlands. Based on these findings an advice will be given for dog owners to keep these risks for waterborne infections as small as possible. 相似文献
69.
Enterohaemorrhagic Escherichia coli (EHEC) has been detected in both wild and domesticated rabbits in other countries. The aim of this study was to determine whether the most pathogenic E. coli serotype, O157:H7, occurs in the Dutch domesticated rabbit population and thus could form a public health risk. To this end, faecal samples were collected from rabbits from two rabbit farms and 741 rabbits of different breeds and origin and analysed for E. coli O157:H7, using a combination of enrichment, immunomagnetic separation, selective culture, and PCR. E. coli O157:H7 was not detected in any of the samples. The results indicate that Dutch domesticated rabbits probably do not play a role in the infection of humans with E. coli O157:H7. 相似文献
70.
Jeffrey H. Gertsch Grant S. Lipman Peter S. Holck Andrew Merritt Allison Mulcahy Robert S. Fisher Buddha Basnyat Eric Allison Keeli Hanzelka Alberto Hazan Zachary Meyers Justin Odegaard Benjamin Pook Mark Thompson Brant Slomovic Henrik Wahlberg Vanessa Wilshaw Eric A. Weiss Ken Zafren 《The Forestry Chronicle》2010,21(3):236-243