Modelling landscape effects on density-contact rate relationships of deer in eastern Alberta: Implications for chronic wasting disease

Managing wildlife diseases requires an understanding of disease transmission, which may be strongly affected by host population density and landscape features. Transmission models are typically fit from time-series disease prevalence data and modelled based on how the contact rate among hosts is affected by density, which is often assumed to be a linear (density-dependent transmission) or constant (frequency-dependent transmission) relationship. However, long-term time-series data is unavailable for emerging diseases, and this approach cannot account for independent effects of landscape. We developed a mechanistic model based on ecological data to empirically derive the contact rate-density relationship in white-tailed and mule deer in an enzootic region of chronic wasting disease (CWD) in Alberta, Canada and to determine whether it was affected by landscape. Using data collected from aerial surveys and GPS-telemetry, we developed empirical relationships predicting deer group size, home range size, and habitat selection to iteratively simulate deer distributions across a range of densities and landscapes. We calculated a relative measure of total per-capita contact rate, which is proportional to the number of other deer contacted per individual per unit time, for each distribution as the sum of pairwise contact rates between a target deer and all other individuals. Each pairwise contact rate was estimated from an empirical relationship developed from GPS-telemetry data predicting pairwise contact rates as a function of home range overlap and landscape structure. Total per-capita contact rates increased as a saturating function of density, supporting a transmission model intermediate between density- and frequency-dependent transmission. This pattern resulted from group sizes that reached an asymptote with increasing deer density, although this relationship was mediated by tree and shrub coverage in the landscape, such that in heavily wooded areas, the contact rate saturated at much lower densities. These results suggest that CWD management based on herd reductions, which require a density-dependent contact rate to be effective, may have variable effects on disease across a single management region. The novel mechanistic approach we employed for estimating effects of density and landscape on transmission is a powerful complement to typical data-fitting approaches for modelling disease transmission.     

The landscape epidemiology of foot-and-mouth disease in South Africa: A spatially explicit multi-agent simulation

This study aimed at understanding how landscape heterogeneity influences outbreaks of contagious diseases in southern Africa. Landscape attributes influence patterns of movement and behaviour of animal hosts, virus spread and survival, as well as land use practices. A multi-agent simulation was developed to represent the spatial and temporal dynamics of pathogens between human-livestock and wildlife interfaces at the fringe of large wildlife conservation areas. The model represents the three main elements associated with epidemics - populations, space, and time - to simulate direct contacts between wildlife and livestock. The dynamics of these populations emerge from interactions between agents and the landscape. The model was calibrated to represent the transmission of foot-and-mouth disease through direct contact at the border of the Kruger National Park in South Africa. In the region, African buffaloes (Syncerus caffer) act as reservoirs of the virus and spread the infection to domestic cattle bordering the park. We tested the sensitivity of various factors influencing contact rate between buffaloes and cattle, and thus the risk of foot-and-mouth disease transmission. Results show that cattle-buffalo contacts mostly depend on the range of displacements of cattle and buffaloes, as influenced by the landscape configuration, and on the number of fence breakages multiplied by the time between breakage and repair. Contacts take place not only close to water-points but also in grazing areas, within an area up to 6 km from the fence.     

Effects of bio-organic fertilizers on pineapple heart rot and bacterial community structure北大核心CSCD

Heart rot is a common soil-borne disease in the pineapple industry, but the situation can be alleviated by the application of bio-fertilizers with beneficial microbiomes. Clarifying the controlling mechanism of bio-organic fertilizer on the high incidence of heart rot is critical in monocultural pineapple cropping patterns. In our study, the soil of continuous cropping pineapple orchards was collected. Three types of carriers (rapeseed cake, peat soil, and coconut bran), biocontrol strains (Bacillus subtilis HL2 and Streptomyces strain HL3), and organic fertilizer (YJ) were composted into different bio-fertilizers (KC, KN, KY, LC, LN, and LY), which were used in pot experiments. The controlling effect of the bio-fertilizer was determined based on the response of pineapple heart rot and bacterial communities to different fertilizing methods. Our results revealed that the incidence of heart rot in bio-fertilizer KC was the lowest, which decreased by 20% and 13.3%, respectively, compared to HF (chemical fertilizer, 16-16-16) and YJ (organic fertilizer). The richness and diversity of soil bacterial communities in all biofertilized treatments (KC, KN, KY, LC, LN, and LY) were significantly higher than those in HF. However, the α-diversity indices of the bio-fertilizers (KC, KN, and KY) were higher than those of LC, LN, and LY, and the bacterial community composition was significantly different. The bacteria GP4, GP6, Bacillus, and Azohydromonas were enriched in KC, KN, and KY, while the relative abundance of Streptomyces increased significantly in LC, LN, and LY. Furthermore, Spearman correlation analysis showed that the relative abundance of these bacterial groups was significantly negatively correlated with the incidence of pineapple heart rot. In summary, the application of bio-organic fertilizers can decrease the incidence of pineapple heart rot by altering the soil bacterial community structure and stimulating beneficial soil microorganisms, which is important for reconstructing the ecological balance in continuous pineapple orchards. © 2022 Authors. All rights reserved.     

模拟SPO情境中的飞行员脑力负荷测量与分析*

为探究单一飞行员驾驶模式（SPO）下飞行员的脑力负荷水平,设计并实施模拟单人驾驶情境中的非正常任务场景处置实验。首先,基于准5级模拟驾驶舱,设计飞行任务场景;其次,招募20名航线飞行员被试,开展模拟飞行实验,记录被试的生理数据心率变异性指标及眼动数据;最后,结合客观生理数据以及主观量表进行脑力负荷分析,记录单发失效故障处置时间并进行任务绩效分析。研究结果表明:与双人制机组相比,单人驾驶情境中飞行员的脑力负荷增幅并不显著,处于可接受范围;单人制驾驶舱的任务设计及智能辅助系统使用对于降低飞行员工作负荷,提升飞行绩效至关重要。研究结果可为单一飞行员驾驶模式实施提供理论支持,并为未来单人制驾驶舱及机载自动化系统设计提供指标参考。     

隧道入口冰雪环境下驾驶员心生理特性研究*

为提高高速公路冰雪环境下隧道入口行车安全水平,探究隧道入口冰雪环境下驾驶员心生理反应特性,依据心生理理论,通过模拟驾驶试验采集驾驶员在冬季晴、雪天气下隧道入口行驶的心率增长率、速度等数据,分析照度变化率、路面摩擦系数、速度对驾驶员心生理的影响规律,明确不同影响因素下隧道入口驾驶员心率增长率变化特征,利用Matlab构建多因素耦合下隧道入口驾驶员心生理反应模型,并设计实车试验验证心生理反应模型有效性。研究结果表明:冰雪环境下隧道入口驾驶员心率增长率紧张阈值为28%,隧道入口冰雪环境下照度变化率安全阈值为51%,心生理反应模型误差小于10%,吻合程度较好。研究结果对提高山区高速公路隧道入口冰雪环境的行车安全性、降低隧道入口事故风险具有重要意义。     

内蒙高腐殖酸地下水中碘的分布特征与IDD病的关系

为探讨碘在高腐植酸地下水中的分布特征 ,研究内蒙古河套平原地区 51份水样 .分析结果显示 ,水质偏碱 (平均值 pH=7.91 ) ,水中腐植酸和 COD含量均高 ,地下水类型属于 HCO₃-Na和 HCO₃-Cl- Na型 .在这种高还原型盐水环境中水碘平均浓度达到 430 μg/L,超过了水碘安全浓度范围的上限 ( 5～ 200μg/L) .相关分析结果显示 ,水碘浓度与其它因素的相关顺序是 :COD>荧光强度 >电导率 >HCO^-₃>Cl^->Na⁺>pH>As>井深 .当地地下水中碘的分布呈现出碘浓度随腐植酸含量和盐渍化程度增加而增加的趋势 .由于这些因素的综合作用 ,当地没有发生高碘型碘缺乏病 ( IDD)的大面积流行 .     

不同藻密度下诺氟沙星对萼花臂尾轮虫生命表统计学参数的影响

诺氟沙星是一种被广泛使用的抗生素,但其对轮虫的毒性作用尚不清楚。为调查诺氟沙星对轮虫的毒性及其与藻密度之间的关系,以及各试验终点对诺氟沙星污染的相对敏感性,本文以萼花臂尾轮虫为受试生物,研究了不同斜生栅藻密度(1.0×10~6、2.0×10~6和4.0×10~6cells·m L~(-1))下不同浓度(0、5、20、35、50、65和80 mg·L~(-1))的诺氟沙星对其生命表统计学参数的影响。结果显示,与3个藻密度下的对照组相比,暴露于5～80 mg·L~(-1)诺氟沙星溶液中的轮虫生命期望和世代时间显著延长,净生殖率和种群内禀增长率显著提高。5 mg·L~(-1)的诺氟沙星使生命期望和世代时间的延长幅度随着藻密度的升高而增大,但6个处理组的平均提高幅度却随着藻密度的升高而减小; 5 mg·L~(-1)的诺氟沙星对净生殖率和种群内禀增长率的提高幅度随着藻密度的升高而增大,但6个处理组的平均提高幅度却在2.0×10~6cells·m L~(-1)的藻密度下最小,4.0×10~6cells·m L~(-1)的藻密度下最大。1.0×10~6cells·m L~(-1)的藻密度下,诺氟沙星浓度对轮虫后代混交率无显著性影响(P0.05); 2.0×10~6cells·m L~(-1)的藻密度下,暴露于5～35和80 mg·L~(-1)诺氟沙星溶液中的轮虫后代混交率显著降低; 4.0×10~6cells·m L~(-1)的藻密度下,暴露于5、35和80 mg·L~(-1)诺氟沙星溶液中的轮虫后代混交率显著降低。当藻密度为1.0×10~6和2.0×10~6cells·m L~(-1)时,诺氟沙星浓度与轮虫的生命期望、世代时间、净生殖率和种群内禀增长率之间具有显著的剂量-效应关系;当藻密度为4.0×10~6cells·m L~(-1)时,诺氟沙星浓度与轮虫的净生殖率和种群内禀增长率之间具有显著的剂量-效应关系。本研究表明,亚致死浓度的诺氟沙星促进轮虫的存活、发育、孤雌生殖和种群增长,促进作用的幅度受藻密度的显著影响。     

生物肥料对香蕉枯萎病及土壤微生物的影响

香蕉枯萎病是真菌引起的一种土传病害,它的蔓延已经严重影响到香蕉产业的正常发展.将腐熟的有机肥与3种生防细菌(枯草芽胞杆菌、胶质芽胞杆菌和巨大芽胞杆菌)结合,组合成生物复混肥和生物有机肥,将它们施用在香蕉上,研究其对枯萎病病害防治效果.盆栽香蕉试验结果显示,2种肥料不仅能抑制香蕉枯萎病(防病效果分别为61.5%和53.8%),同时也引起土壤微生物群落发生变化,真菌数量明显下降,放线菌明显升高,细菌变化较小.通过相关分析发现,生物肥料中3种生防细菌总数与土壤中枯萎菌和普通真菌呈显著负相关,而与防病效果呈极显著正相关,有机肥中细菌与土壤细菌和放线菌含量也呈显著正相关.     

稻鸭萍共作复合系统的主要生态效应

对稻鸭萍共作体系的主要生态效应研究结果表明,稻鸭萍共作有利于提高土壤肥力,水稻收获后的土壤有机质、碱解氮、速效磷、速效钾分别比对照增加7.95%、7.05%、6.47%和4.46%;稻鸭萍共作对杂草的控制效果达到98.94%,明显削弱了稻田优势杂草的发生与危害,稻田残存杂草为数甚少,P ielou均匀度指数显著提高;稻鸭萍共作对稻田飞虱有显著的控制效应,从而明显抑制主要由灰飞虱传毒危害的水稻条纹叶枯病的发病率;稻鸭萍共作虽然对水稻纹枯病也有明显防治效果,但不能阻止纹枯病的发生;由于绿萍吸附了稻田水体中部分有机物、腐殖质等,稻鸭萍共作区水体的化学需氧量比稻鸭共作区降低8.70%。     

Successful outcome of pregnancy after treatment of maternal anti-ro (SSA) antibodies with immunosuppressive therapy and plasmapheresis

In this short communication we describe a patient with anti-SSA and anti-SSB antibodies whose first child died of congenital complete heart block (CCHB). During her second pregnancy she was treated with prednisolone, azathioprine, and plasmapheresis, and levels of anti-SSA and anti-SSB antibodies fell significantly. The pregnancy evolved uneventfully and resulted in the birth of an unaffected male infant. This is the fourth reported case of a successful outcome of pregnancy after treatment with immunosuppressive drugs in a woman with a significant risk of recurrence of CCHB.