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1.
Schwermer H Brülisauer F De Koeijer A Heim D 《Berliner und Münchener tier?rztliche Wochenschrift》2007,120(5-6):189-196
The effectiveness of two measures against Bovine Spongiform Encephalopathy (BSE), the compulsory processing of animal by products to meat and bone meal (MBM) at 133 degrees C under 3 bars of pressure for 20 minutes in February 1993 and the exclusion of fallen stock, heads with eyes and spinal cord of cattle older than 30 month from MBM production in April 1996, was evaluated in a process model. The transmission of BSE by calculation of the basic reproduction ratio R0 was modelled.The results were verified by use of a cohort model, based on observed surveillance data. Prior to 1990, before the ban of feeding MBM to ruminants, R0, as calculated in the process model, was above 1, coherent with a slowly progressing BSE epidemic. Since 1991, values of R0 were low at 0.06.The corresponding R0 values derived from the cohort model were higher, the lowest value 0.13 calculated for 1996. Given such low R0 values, the epidemic should have died out. Additionally, no influence of the two measures was obvious at that time given the low level of R0. The discrepancy between the results of the two models is evidence for a dependency of the BSE epidemic from an infection source not considered in the process model. This infection source is most likely importation of feed ingredients and MBM. 相似文献
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D. Craig Heim George G. Kennedy Fred L. Gould John W. Van Duyn 《Pest management science》1992,34(4):303-311
Progeny from reciprocal F1 crosses and F1 backcrosses between fenvalerate-resistant and fenvalerate-susceptible Colorado beetles, Leptinotarsa decemlineata (Say), and between carbofuran-resistant and carbofuran-susceptible Colorado beetles were bioassayed to investigate the mode of inheritance of resistance to these chemicals. Bioassays of progeny from these crosses indicate that resistance to fenvalerate is inherited in a semi-recessive, sex-linked manner and carbofuran resistance is inherited in a partially dominant autosomal fashion. Log concentration/probit mortality lines and chi-square tests, however, indicate that multiple genes may be involved in resistance to both insecticides. 相似文献
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A residual bioassay was used to determine insecticide susceptibility in populations of Colarado potato beetle, Leptinotarsa decemlineata (Say), in eastern North Carolina. Mean bioassay mortalities were subjected to correlation analysis to assess patterns of resistance among tested insecticides. Within insecticide classes, cross-resistance patterns were observed between carbaryl and carbofuran (carbamates), fenvalerate and permethrin (pyrethroids), and among azinphosmethyl, methamidophos, and phosmet (organophosphates). Significant associations between insecticides from different insecticide classes were concluded to be due to multiple resistance. Knowledge of multiple and cross-resistance patterns are discussed in relation to the bioassay as a tool for monitoring insecticide resistance. 相似文献
4.
Scrapie has been known to occur in sheep and goats for over 250 years. Sheep and goats can be experimentally infected orally with BSE, however BSE infection can only be distinguished from scrapie using costly and extensive laboratory procedures. An overview of both the current state of knowledge on Transmissible Spongiform Encephalopathies (TSE) in small ruminants as well as the TSE monitoring and control strategies in place in Switzerland is presented. 相似文献
5.
When the first BSE case in Switzerland became public in 1990, it precipitated a chain of events with many diverse consequences. During this time, we continued to gain knowledge, implement new measures, and make practical recommendations in order to attempt to control the disease. This was made possible by the establishment of a huge data base containing information on all cases of BSE that had been diagnosed in Switzerland, as well as by the use of information from experiences in other countries. Analysis of these data allowed the sequence of events to be described temporally and spatially and an epidemiological evaluation to be made. These data also allow predictions to be made regarding the future of BSE in Switzerland, although these predictions must be interpreted cautiously. 相似文献
6.
Over one-third of the cases of BSE in Switzerland have been born after the feed ban of December 1, 1990. Evidence for the geographical clustering of these cases emerged in two distinct regions. All the 354 BSE cases recorded until June 30, 2000 (set A), and the 376 cases recorded up to May 14, 2001 (set B), were georeferenced to the centres of the communities in which the herds of origin were located, and control populations were georeferenced to the centres of the communities in which these herds were located at the time of the census. The latitudes and longitudes of these centres were used in the statistical analysis of the spatial clustering. The Cuzick-Edwards test and the spatial scan statistics were applied to assess the significance of the clusters, while controlling for the spatial distribution of the underlying cattle population. There was global clustering of the cases born after the ban, and distinct and significant (P<0.05) spatial clusters were repeatedly identified in the two case datasets, and in several control populations (all cases born before the feed ban on a random sample of control farms) in terms of cattle density by region or cow density by region. Differential reporting was excluded as the underlying reason for the observed clusters. 相似文献
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8.
Daniel Kohl C. von Boyneburgk M. Feldmann H.-P. Heim S. Böhm 《Wood material science & engineering》2020,15(3):130-139
ABSTRACTDue to its naturally grown properties, wood has played a rather subordinate role as a material for technical applications up to now. In this paper, multi-material systems based on veneers of beech (Fagus sylvatica) with different reinforcing variants were investigated. In addition to the influence of different adhesive systems (urea formaldehyde and polyurethane), the effect of reinforcing by aramid fiber fabric and stainless steel foil in different climates was examined. At the center of the investigations were dynamically sudden loads, in the form of impact bending and dart drop tests (penetration and impact mode). It has been shown that the use of the reinforcing materials leads to a significant improvement in material properties. The penetration energy of the composites reinforced with the aramid fiber fabric could be increased by 43%. The maximum force in the dart drop test (impact mode) could be increased by 29% with the stainless steel foil, the damping decreased by 48%. The aramid fiber reinforcement achieved an increase in impact resistance by 27% in impact bending test, the steel reinforced achieved an increase of 39%. A clear dependency on both, the climate and the adhesive within the composite, could be demonstrated. 相似文献
9.
Green roofs provide a number of valuable ecosystem services compared to conventional roofs, but may require yearly maintenance. Trees and other woody plants that persist on the roof may damage or overload shallow-substrate green roofs and their removal is a standard maintenance procedure. The germination potential of colonizing species may differ depending on the vegetation surrounding them. The aim of this study was to determine whether the germination of colonizing tree species (Picea glauca and Ulmus glabra) will vary depending on which plant species form the established vegetation seeds land in. To determine germination success, survival, and seed capture ability of the plant canopy, tree seeds were added either directly to the growing medium or atop the plant canopy, in replicated monocultures of 14 species native to Nova Scotia. When seeds were added directly to the soil, no significant difference was detected between the monocultures for germination success or survival for U. glabra or P. glauca. However, when the seeds were added atop the plant canopy, percent germination of U. glabra was significantly higher in Carex argyrantha green roof modules. Overall, sod forming graminoids showed higher germination of U. glabra. The number of seeds reaching the soil was typically lower in vegetation with a denser canopy. This study demonstrates that some vegetation repels colonizing tree species by reducing ground contact. Although these effects differed according to tree species, non-vegetated substrates enhanced seedling persistence. Additionally, the majority of tree seeds that germinated failed to survive a single growing-season on shallow-substrate green roofs. 相似文献
10.
Köfler M Seuberlich T Maurer E Heim D Doherr M Zurbriggen A Botteron C 《Schweizer Archiv für Tierheilkunde》2006,148(7):341-2, 344-8
Switzerland is controlling Transmissible Spongiform Encephalopathies (TSE) in cattle (BSE) and small ruminants (scrapie). Since BSE is potentially transmissible to sheep, goats or pigs through feeding of contaminated meat and bone meal, implementation of an active surveillance programme for TSE in these species is discussed. The aim of this pilot study was to obtain preliminary data on the prevalence ofTSE and other neurological disorders in these populations. For that purpose, a total of 398 perished and 825 slaughtered adult small ruminants and pigs was examined for the presence of neuropathological changes. None of these animals revealed positive for TSE. However, the investigations demonstrated that perished sheep and goats exhibited a higher prevalence of relevant neuropathological changes when compared with slaughtered animals. From these results, it is concluded that perished small ruminants are probably a risk population for TSE and should be considered as target populations for an active surveillance programme. 相似文献