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61.
A brief account is given of the work leading up to the synthesis of epronaz (BTS 30 843), 1-(N-ethyl-N-propylcarbamoyl)-3-propylsulphonyl-1,2,4-triazole, a new pre- and early post-emergence herbicide for annual grasses. The synthesis is described, together with the occurrence and isolation of all three possible positional isomers in the final (carbamoylation) stage. The evidence for the structure assigned to epronaz is presented together with that for the other two isomers, and their interconversion is described. Some chemical properties of epronaz are described, with particular reference to its hydrolysis and its ability to function as a carbamoylating agent, in relation to persistence in the environment and to mode of action respectively. Some physical properties are also reported, including vapour pressure, solubility, and spectra. The mass spectral fragmentation pattern is also discussed.  相似文献   
62.

Objective

To evaluate the effect of Equivac® HeV Hendra virus vaccine on Thoroughbred racing performance.

Design

Retrospective pre‐post intervention study.

Methods

Thoroughbreds with at least one start at one of six major south‐eastern Queensland race tracks between 1 July 2012 and 31 December 2016 and with starts in the 3‐month periods before and after Hendra virus vaccinations were identified. Piecewise linear mixed models compared the trends in ‘Timeform rating’ and ‘margin to winner’ before and after initial Hendra virus vaccination. Generalised linear mixed models similarly compared the odds of ‘winning’, ‘placing’ (1st–3rd) and ‘winning any prize money’. Timeform rating trends were also compared before and after the second and subsequent vaccinations.

Results

Analysis of data from 4208 race starts by 755 horses revealed no significant difference in performance in the 3 months before versus 3 months after initial Hendra vaccination for Timeform rating (P = 0.32), ‘Margin to winner’ (P = 0.45), prize money won (P = 0.25), wins (P = 0.64) or placings (P = 0.77). Further analysis for Timeform rating for 7844 race starts by 928 horses failed to identify any significant change in Timeform rating trends before versus after the second and subsequent vaccinations (P = 0.16) or any evidence of a cumulative effect for the number of vaccines received (P = 0.22).

Conclusion

No evidence of an effect of Hendra virus vaccination on racing performance was found. The findings allow owners, trainers, industry regulators and animal health authorities to make informed decisions about vaccination.  相似文献   
63.
In August 2015, a rabies outbreak occurred in bovines in a Punjab village, India; subsequently, a farmer in the same village died of rabies in October 2015. We surveyed farmers to describe the outbreak, the demographics and rabies prophylaxis administered to householders on case farms, and farmers’ knowledge of rabies prevention and treatment. We used multiple correspondence analysis to guide investigation of associations between demographics, farm status and rabies knowledge, attitudes and practices. The number of affected bovines was unusually high; 15 cattle and buffalo died on 13 smallholder farms (attack rate 4%). Post‐exposure vaccinations were administered to 24 people (median 2 doses). Affected farms had significantly larger households and were more likely to keep their livestock outside (therefore, accessible by stray dogs), suggesting that the impact of the outbreak was disproportionally borne by households of lower socio‐economic status. Primary sources of rabies information were friends and neighbours, not health authorities or media. Women who had not received formal education were less likely to have heard of rabies. Although case farm participants were more likely to have heard about rabies from a veterinarian, their knowledge and practices to prevent rabies did not reflect the level expected considering their contact with a health professional; they were more likely to believe that traditional remedies prevent rabies and less likely to tell their children to avoid playing with stray dogs than participants from other farms. This study highlights knowledge dissemination disparities that, if typical of rural locations, could obstruct attempts to eliminate canine‐mediated human rabies in India. Therefore, understanding the pervasiveness and influence of traditional medical beliefs on treatment‐seeking behaviour, communication structures within villages and the impact of local practices such as carcass disposal on dog populations will be essential to ensure that rabies control strategies are effective in rural India.  相似文献   
64.

Context

Simulation models are increasingly used in both theoretical and applied studies to explore system responses to natural and anthropogenic forcing functions, develop defensible predictions of future conditions, challenge simplifying assumptions that facilitated past research, and to train students in scientific concepts and technology. Researcher’s increased use of simulation models has created a demand for new platforms that balance performance, utility, and flexibility.

Objectives

We describe HexSim, a powerful new spatially-explicit, individual-based modeling framework that will have applications spanning diverse landscape settings, species, stressors, and disciplines (e.g. ecology, conservation, genetics, epidemiology). We begin with a model overview and follow-up with a discussion of key formative studies that influenced HexSim’s development. We then describe specific model applications of relevance to readers of Landscape Ecology. Our goal is to introduce readers to this new modeling platform, and to provide examples characterizing its novelty and utility.

Conclusions

With this publication, we conclude a > 10 year development effort, and assert that our HexSim model is mature, robust, extremely well tested, and ready for adoption by the research community. The HexSim model, documentation, worked examples, and other materials can be freely obtained from the website www.hexsim.net.
  相似文献   
65.
土壤磷淋失机理初步研究   总被引:11,自引:2,他引:11  
用石膏标记的方法,研究了蝼土磷素淋移的机理。试验表明,(土娄)土中广泛存在的大孔隙,可能是磷素淋移的主要途径。石膏悬液可以达到的最大可见深度约为90.cm(距灌溉面约70cm)。用200mg/kg磷溶液浇灌,非常明显地提高了沿大孔隙壁深达80.cm土壤的OlsenP含量,但本体土样没有明显提高;试验还观察到石膏悬液可以通过根表到达距地表55cm深的土壤剖面。  相似文献   
66.
灌溉与旱作条件下长期施肥(土娄)土剖面磷的分布和移动   总被引:4,自引:1,他引:4  
利用12年长期定位试验研究了灌溉和旱作条件下不同施肥处理对(土娄)土土壤剖面全磷与有效磷(Olsen - P)分布和移动的影响.结果表明,(土娄)2土施磷后主要累积在耕层,极大地提高了0-20cm土层全磷与Olsen - P含量.旱作条件下,施用磷肥或化肥配施有机肥提高了100cm以上土体全磷与Olsen - P含量; 而化肥配合有机肥,Olsen - P含量在100-300cm土壤剖面中都高于对照(不施肥)和化肥处理.灌溉条件下,与旱作有相同趋势,但磷钾、有机肥配施氮磷钾处理,全磷和Olsen - P不仅在0-300cm剖面中高于对照和氮磷钾处理,而且也高于旱作条件下的相同处理.(土娄)土上存在磷素的淋失.  相似文献   
67.
Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga aenescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15?–?0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies >?90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides.  相似文献   
68.
Highly pathogenic porcine reproductive and respiratory syndrome (PRRS) has spread through parts of south-east Asia, posing a risk to Australia. The objective of this study was to assess the probability of infection of a feral or domestic pig in Australia with highly pathogenic PRRS following ingestion of illegally imported raw pork. A conservative scenario was considered in which 500 g of raw pork was imported from the Philippines into Australia without being detected by border security, then discarded from a household and potentially accessed by a pig. Monte Carlo simulation of a two-dimensional, stochastic model was used to estimate the probability of entry and exposure, and the probability of infection was assessed by incorporating a virus-decay and mechanistic dose–response model. Results indicated that the probability of infection of a feral pig after ingestion of raw meat was higher than the probability of infection of a domestic pig. Sensitivity analysis was used to assess the influence of input parameters on model output probability estimates, and extension of the virus-decay and dose–response model was used to explore the impact of different temperatures and time from slaughter to ingestion of the meat, different weights of meat, and the level of viraemia at slaughter on the infectivity of meat. Parameters with the highest influence on the model output were the level of viraemia of a pig prior to slaughter and the probability of access by a feral pig to food-waste discarded on property surrounding a household. Extension of the decay and dose–response model showed that small pieces of meat (10 g) from a highly pathogenic PRRS viraemic pig could contain enough virus to have a high probability of infection of a pig, and that routes to Australia by sea or air from all highly pathogenic PRRS virus endemic countries were of interest dependent on the temperature of the raw meat during transport. This study highlighted the importance of mitigation strategies such as disposal of food-waste from international traffic as quarantine waste, and the need for further research into the probability of access to food-waste on properties by feral pigs.  相似文献   
69.
The concept that superconductivity competes with other orders in cuprate superconductors has become increasingly apparent, but obtaining direct evidence with bulk-sensitive probes is challenging. We have used resonant soft x-ray scattering to identify two-dimensional charge fluctuations with an incommensurate periodicity of ~3.2 lattice units in the copper-oxide planes of the superconductors (Y,Nd)Ba(2)Cu(3)O(6+)(x), with hole concentrations of 0.09 to 0.13 per planar Cu ion. The intensity and correlation length of the fluctuation signal increase strongly upon cooling down to the superconducting transition temperature (T(c)); further cooling below T(c) abruptly reverses the divergence of the charge correlations. In combination with earlier observations of a large gap in the spin excitation spectrum, these data indicate an incipient charge density wave instability that competes with superconductivity.  相似文献   
70.
The influence of soil pH on the phospholipid fatty acid (PLFA) composition of the microbial community was investigated along the Hoosfield acid strip, Rothamsted Research, UK - a uniform pH gradient between pH 8.3 and 4.5. The influence of soil pH on the total concentration of PLFAs was not significant, while biomass estimated using substrate induced respiration decreased by about 25%. However, the PLFA composition clearly changed along the soil pH gradient. About 40% of the variation in PLFA composition along the gradient was explained by a first principal component, and the sample scores were highly correlated to pH (R2 = 0.97). Many PLFAs responded to pH similarly in the Hoosfield arable soil compared with previous assessments in forest soils, including, e.g. monounsaturated PLFAs 16:1ω5, 16:1ω7c and 18:1ω7, which increased in relative concentrations with pH, and i16:0 and cy19:0, both of which decreased with pH. Some PLFAs responded differently to pH between the soil types, e.g. br18:0. We conclude that soil pH has a profound influence on the microbial PLFA composition, which must be considered in all applications of this method to detect changes in the microbial community.  相似文献   
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