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101.
The antimicrobial susceptibilities of 76 field isolates of Brachyspira hyodysenteriae from different states of Australia were tested in a newly developed broth dilution procedure. The antimicrobial agents used were tiamulin, valnemulin, tylosin, erythromycin, lincomycin and clindamycin. The results from the broth dilution susceptibility testing of 39 of the isolates were compared with results obtained for the same isolates using the agar dilution method. Amongst the isolates tested by broth dilution, 17 were from three farms and had been collected over a number of years. Their pulsed field gel electrophoresis pattern previously had been determined. The broth dilution technique was simple to use, less labor intensive than agar dilution, and gave clear end points. The results obtained using the two methods generally corresponded well, although in a few cases the MIC obtained by broth dilution were lower than those with agar dilution. For the 76 isolates tested by broth dilution, the MIC(90) (mg/l) was: tiamulin, 1; valnemulin, 0.5; tylosin>256; erythromycin>256; lincomycin, 64 and clindamycin, 16. Only minor differences in susceptibility patterns were found amongst isolates from different Australian states. Over all the isolates, and also amongst the isolates obtained from different years on the three farms, there was no trend for the susceptibility of the isolates to alter with time. 相似文献
102.
Elisabet Sonntag-Öström Maria Nordin Ylva Lundell Ann Dolling Urban Wiklund Marcus Karlsson Bo Carlberg Lisbeth Slunga Järvholm 《Urban Forestry & Urban Greening》2014,13(2):344-354
This experimental study investigated differences in perceived restorativeness, mood, attention capacity and physiological reactions when visiting city and forest environments. Twenty female patients diagnosed with exhaustion disorder visited three different forest environments and one city environment in randomized order. They performed a standardized 90-min test procedure in each of these environments. Evaluation of the environments and psychological effects in mood were studied with self-administered questionnaires. Attention capacity was studied with Necker Cube Pattern Control task. Physiological responses were measured with regularly scheduled controls of heart rate and blood pressure, and a single test of heart rate recovery. Visits to the forest environments were perceived as significantly more restorative, enhancing mood and attention capacity compared to the city. This also applies to the results of heart rate and to some extent to the results of the diastolic blood pressure. The results from this experimental study support our hypothesis that short visits to forest environments enhance both psychological and physiological recovery and that visits to forest environments are likely to be beneficial when suffering from exhaustion disorder. 相似文献
103.
Matts Lindbladh Anna-Lena Axelsson Tove Hultberg Jörg Brunet Adam Felton 《Scandinavian Journal of Forest Research》2014,29(7):686-696
Mixed or broadleaf forests were once common in many regions of Northern Europe, whereas today conifers often dominate. The aim of the study was to investigate the spatial and temporal patterns and processes which underlie this transition to Picea abies dominance in southern Sweden. We use recently developed paleoecological methods to determine long-term changes in the relative abundance of tree species, and digitalized National Forest Inventory (NFI) databases to assess more recent changes in the spatial coverage of Picea throughout the region. The novel combination of the two databases reveals that Picea became a widespread and abundant species in many parts of southern Sweden around 1000 years ago. After a brief decline in abundance starting around 500 years ago, NFI data indicate a rapid increase in the volume of Picea between 1920 and 1950, prior to the large-scale introduction of Picea-dominated plantation forests. The available evidence suggests that abandonment of forest grazing and slash-and-burn cultivation, as well as selection cutting benefited the natural establishment and growth of Picea during the first half of the twentieth century. Hence, prior to the impacts of industrialized forestry that began in the 1950s, other processes were already favouring increased Picea abundance. 相似文献
104.
105.
C. Lindholm L. Karlsson A. Johansson J. Altimiras 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(4):231-238
Organic chicken production is currently experiencing a boom in Sweden, but has only recently gained access to a commercial slow-growing broiler strain, the Rowan Ranger. While these chickens are reported to grow at rates better suited to organic production than previously available strains, anecdotal evidence suggested increased fearfulness in this strain and concerns were raised that this may deter the birds from accessing the range. We subjected Rowan Rangers and fast-growing Ross 308 raised on the same organic farm to a set of behavioural tests while also tracking activity and outdoor use. The results suggest that although Rowan Rangers indeed show longer durations of tonic immobility, an index of predator-related fear, both strains made an outdoor visit on average once every 1.5?h and typically spent around 5% of their days in the range. Overall however, our results support the transition to Rowan Rangers in organic chicken production in Sweden. 相似文献
106.
Hazard identification of contaminated sites—ranking potential toxicity of organic sediment extracts in crustacean and fish 总被引:1,自引:0,他引:1
Jenny Karlsson Henrik Sundberg Gun Åkerman Kerstin Grunder Britta Eklund Magnus Breitholtz 《Journal of Soils and Sediments》2008,8(4):263-274
Background, aim, and scope It is well known that contaminated sediments represent a potential long-term source of pollutants to the aquatic environment.
To protect human and ecosystem health, it is becoming common to remediate contaminated sites. However, the great cost associated
with, e.g., dredging in combination with the large numbers of contaminated sites makes it crucial to pinpoint those sites
that are in greatest need of remediation. In most European countries, this prioritization process has almost exclusively been
based on chemical analyses of known substances; only seldom toxicity data has been considered. The main objective of the current
study was therefore to develop a tool for hazard identification of sediment by ranking potential toxicity of organic sediment
extracts in a crustacean and a fish. A secondary objective was to investigate the difference in potential toxicity between
compounds with different polarities.
Materials and methods Early life stages of the crustacean Nitocra spinipes and the fish Oncorhynchus mykiss, which represent organisms from different trophic levels (primary and secondary consumer) and with different routes of exposure
(i.e., ingestion through food, diffusive uptake, and maternal transfer), were exposed to hexane and acetone fractions (semi-polar
compounds) of sediment from five locations, ranging from heavily to low contaminated. Preliminary tests showed that the extracts
were non-bioavailable to the crustacean when exposed via water, and the extracts were therefore loaded on silica gel. Rainbow
trout embryos were exposed using nano-injection technique.
Results and discussion Clear concentration–response relationships of both mortality and larval development were observed in all tests with N. spinipes. Also for rainbow trout, the observed effects (e.g., abnormality, hemorrhage, asymmetric yolk sac) followed a dose-related
pattern. Interestingly, our results indicate that some of the locations contained toxic semi-polar compounds, which are normally
not considered in risk assessment of sediment since they are focused on compounds isolated in the hexane fraction.
Conclusions The ranking of the five sediments followed the expected pattern of potential toxicity in both organisms, i.e., sediments with
known pollution history caused major effects while reference sediments caused minor effects in the two test systems. Silica
gel turned out to be an excellent carrier for exposure of N. spinipes to very hydrophobic and otherwise non-bioavailable sediment extracts.
Recommendations and perspectives Since both test systems demonstrated that a substantial part of the potential toxicity was caused by semi-polar compounds
in the acetone fractions, this study enlightens our poor understanding of which compounds are causing adverse effects in environmental
samples. Therefore, by investigating potential toxicity (i.e., hazard identification) as a first screening step in prioritizing
processes, these implications could be avoided. For proper sediment risk assessment, we however recommend whole sediment toxicity
tests to be used for selected sites at following tiers. 相似文献
107.
Using microcarrier cell culture for the production of virus antigen, a formalin-inactivated feline panleukopenia virus vaccine was evaluated for protection of mink against specific mink enteritis virus infection. The vaccine showed a good immunogenic effect in mink when used either alone or in combination with Clostridium botulinum type C-toxoid and/or Pseudomonas aeruginosa vaccine. A single vaccination induced persistent immune responses for periods of at least 1 year, as evaluated by ELISA and challenge tests. Neither immunological interference between vaccine constituents nor adverse reactions were observed. 相似文献
108.
Igor Drobyshev Mats Niklasson Hans Linderson Kerstin Sonesson Matts Karlsson Sven G. Nilsson Jan Lanner 《Annals of Forest Science》2008,65(4):401-401
109.
现在的仙客来品种不同于原生种,它们需要不断优化的栽培管理技术,包括温度和光照强度,尤其是对温度的需求。
速生性、以种子繁殖且花色丰富的仙客来品种的推广促进了种植技术的提高,而大部分传统的仙客来是以球茎力繁殖材料。 相似文献
110.
Anneli Lundkvist Lennart Salomonsson Lennart Karlsson Ann-Marie Dock Gustavsson 《European Journal of Agronomy》2008,28(4):570-578
In 1987, the Ekhaga Experimental Farm in Sweden was established on a site that previously had been subjected to conventional farming, and has been managed since then as an organic farm. To study the effects of organic farming on weed population development and crop yields, two different crop rotations were designed, one adapted for animals (six fields) and one without animals (six fields). Each field contained a fixed 1 m2 reference plot in which all the weed observations were done each year. During the period 1988–2002, number of weed plants in spring and weed biomass at harvest were recorded in the reference plots. No differences in these two parameters were observed between the crop rotations. Number of weed plants in spring did not differ between annual crops and did not increase over the 15-year period. Neither did weed biomass at harvest nor weed species diversity change over the 15 years. The two crop rotations kept weed pressure at the same level as under the previous conventional farming practice. General field observations suggest that invasion of Cirsium arvense (L.) Scop. is occurring along the field borders. Competitive ability of the crop showed to be important in weed regulation. Peas, a weak competitor, had significantly higher weed biomass at harvest compared with oats and winter wheat. Weather conditions during the period from April to September caused weed occurrence and development through the season to vary between years. To improve weed management in organic farming, advisors and farmers should recognise the importance of individual field and farm analyses to design location-specific, farm-adapted crop rotations. 相似文献