In order to quantitatively analyse the spatial pattern of cacao swollen shoot disease, particularly in cases of re‐emergence, three experimental plots were installed in a diseased area of cacao cv. Amelonado in Togo. After thorough cleaning and grubbing, the three plots were planted with less susceptible, hybrid plant material. Twenty years after replanting, a survey of healthy, diseased and dead trees was carried out during 2 consecutive years. Data were analysed using Ripley’s functions and join counts analysis. The re‐emergence of the disease occurred in patches or foci: following analyses with the two statistical methods, diseased trees and dead trees were found to be clearly aggregated on the three observed plots for the 2 years. The observed progress of the disease was not the same on the three plots and seemed dependent on the disease state of the first year: the higher the attack rate of the first year, the faster the disease progression. The use of less susceptible plants helped keep the land productive for 15 years. In conclusion, uprooting of the first infection focus can extend the life of cacao plots. 相似文献
Neighborhood satisfaction and use patterns in public outdoor spaces are generally viewed as single entities, ignoring their multidimensionality as well as detailed associations between them. Such a general assessment raises questions of the kinds of neighborhood characteristics that accrue to satisfaction, and the variety of environmental affordances perceived by residents with respect to nearby outdoor settings. Given the significant role of these factors in people’s life satisfaction and wellbeing, a nuanced approach is needed to help us better understand people-environment relationships and examine practical solutions for creating more livable neighborhoods. This study investigated two-way associations between four aspects of neighborhood satisfaction and three forms of use, as well as the role played by perceived barriers to neighborhood use in these associations. A random sample of 434 Chicago residents participated in a survey (mailed and on-site) with a five-point rating scale. The three major findings through generalized linear modeling include; 1) multidimensionality of both neighborhood satisfaction and use patterns as important to consider in people-environment studies, 2) the significant roles as predictors and as outcomes played by both neighborhood satisfaction and use patterns, with only one factor from each set showing a two-way relationship, and 3) the main effect of perceived barriers on three of the neighborhood satisfactions, and their interactive effect with several of the use pattern and satisfaction factors. These findings contribute to our understanding of people-environment relationships in urban public spaces and provide insights for improving neighborhood satisfaction and frequency of use of public outdoor spaces. 相似文献
β‐carotene is a robust modulator of mucosal barriers, and it can amplify the immunoglobulin A (IgA) response via the retinoic acid (RA)–mediated pathway. We investigated the influence of β‐carotene on intestinal barriers in layer‐type cockerels. In this study, β‐carotene has a positive influence on growth performance and intestinal morphology. β‐carotene remarkably enhanced serum secretory immunoglobulin A (sIgA) levels, jejunal mucosal sIgA, and IgA concentrations. β‐Carotene significantly enhanced mRNA expression levels of IgA, CC chemokine receptor‐9 (CCR9), polymeric immunoglobulin receptor (pIgR), and retinoic acid receptor α (RARα) in the ileal tissues and pIgR in the jejunal tissues. β‐Carotene improves mRNA expression of intestinal barrier‐related proteins including: mucin‐2 (MUC‐2), zonula occludens‐2 (ZO‐2), occludins (OCLN), and zonula occludens‐1 (ZO‐1) in the ileal tissues. Moreover, β‐carotene decreased the levels of Escherichia coli and elevates the levels of Lactobacillus. The results indicate that β‐carotene can promote growth performance and contribute to the gradual development of intestinal barriers in Hyline Brown chicks. This study enriches our knowledge about the effects of β‐carotene on intestinal barrier and highlights a theoretical basis of β‐carotene application in the poultry industry. 相似文献
In previous studies, it has been demonstrated that, similar to general practitioners, veterinarians find it difficult to discuss overweight in dogs. This study aimed to provide insight in the barriers and motivators for veterinarians to discuss overweight in dogs and to compare the results with findings from human medicine. Sub-hypotheses were postulated based on existing literature to investigate if lack of time, fear of offending clients, or lack of skills were potential barriers, and if feeling responsible and feeling compassion were potential motivators for veterinarians to discuss overweight in dogs. To this end, an online survey (n = 59) was conducted. Furthermore, 15 small animal clinicians working in general practice were interviewed by semi-structured face-to-face interviews. Results from the online survey indicated that veterinarians find it sometimes difficult to discuss overweight in dogs. Veterinarians who responded to the online survey did not experience strong barriers but did make use of motivators (e.g. feeling responsible and feeling compassion) when discussing overweight in dogs. Interestingly, results from the semi-structured face-to-face interviews showed that the responding veterinarians did experience strong barriers, as well as motivators, when discussing overweight in dogs with their clients. The most prominent barrier was customer dissatisfaction, whereas lack of time and lack of skills were also experienced. The most prominent motivator was feeling responsible for animal health and preventive veterinary medicine. These findings were strikingly similar to previous research on discussing childhood overweight by general practitioners. To improve treatment and prevention of overweight in dogs, veterinarians need more communication skills and should be more aware of the motivators that drive their self-motivation. Improving awareness on overweight and its comorbidities should be a One Health issue. 相似文献
The effects of vegetation barriers and tillage on runoff and soil loss were evaluated in an alley crop system at a research station in central Burkina Faso. On a 2% slope of a sandy loam various local species (grasses, woody species and a succulent) were planted as conservation barriers in order to examine their influence on sediment transport. After each erosive storm, runoff and sediment yield was determined. The dense effective barriers (Andropogon gayanus and dense natural vegetation) slow down flow velocity, build up backwater and promote sedimentation uphill. The through flow in the less effective barriers with woody species and succulents (Ziziphus mauritania and Agave sisalana) was slightly hampered and flow velocity was not reduced enough, resulting in a higher soil transport. Under degraded conditions soil loss diminished 50% with less effective and 70–90% with effective barriers. During the initial cropping phase (light tillage; sowing) erosion was reduced 40–60% with effective barriers and showed an increase of 45% with less effective barriers. In the full tillage (weeding) period erosion decreased by 80–90% for effective and 70% for less effective barriers, aided by the development of the barrier and the crop on the alley. Barriers of natural vegetation and A. gayanus are preferred for diminishing soil loss.
Sediment yield could best be predicted by the erosivity index (AIm), second best by runoff amount (mm), closely followed by maximum peak intensity. All these parameters are related to the volume of overland flow needed to transport soil particles. Correlation of soil loss with small rain showers was poor and correlation with big showers was good. Sediment transport with no barrier had the highest correlation, closely followed by less effective barriers. Due to the heterogeneity in development of the effective barrier, correlations were much lower. The bulk of soil loss was only dependent on a few extreme events during the observation period. 相似文献
Abstract Immigration of catadromous anguillid eels into fresh water can be impeded by barriers such as barrages, weirs and dams. The uses of passes and trap-and-transport systems to enhance recruitment are reviewed. Pre-construction studies of the needs for passes and traps are discussed in relation to key biological and hydraulic management criteria. Recommendations for pass and trap designs and placement are made in the context of site-specific biotic and abiotic factors. Reference is made to experience gained from eel passes and trapping systems in use throughout the world, and to experimental and pre-and post-construction monitoring studies. Practical recommendations are made for the design and use of eel passes and traps for monitoring studies and for trap-and-transport stocking. 相似文献