Effect of temperature on RNA silencing of a negative‐stranded RNA plant virus: Citrus psorosis virus

Citrus psorosis virus (CPsV), genus Ophiovirus, causes a bark scaling disease of citrus. CPsV virions are kinked filaments with three negative‐stranded RNA molecules (vRNA) and a 48 kDa coat protein. The effect of temperature on symptom expression, virus accumulation and RNA silencing was examined in sweet orange seedlings (Citrus sinensis) graft‐inoculated with three different CPsV isolates and grown in a glasshouse at 26/18°C or 32/26°C (day/night). Most plants kept in the cooler glasshouse showed a shock reaction in the first flush with shoot necrosis, and then moderate to intense chlorotic flecking and spotting in young leaves, whereas plants incubated at 32/26°C did not exhibit shoot necrosis, and young leaf symptoms were milder. Virus titre estimated by ELISA and by northern and dot blot hybridization paralleled symptom intensity, with significantly higher virus accumulation in plants incubated at 26/18°C. The amount of CPsV‐derived small RNAs (CPsV‐sRNAs) slightly increased at 32/26°C, with the ratio of CPsV‐sRNA/vRNA being higher at 32/26°C than at 26/18°C. These results suggest that (i) CPsV infection induces RNA silencing in citrus plants, (ii) symptom intensity is associated with virus accumulation, and (iii) temperature increase enhances the RNA silencing response of citrus plants and decreases virus accumulation.     

就近务工提升了农民工城镇化意愿吗——基于贵阳市的调查

"三个1亿人"提倡的就近城镇化已经上升为国家战略,但是否可行取决于农民工是否具备就近城镇化意愿。本文基于务工距离视角对此进行了研究,并以欠发达地区贵州省贵阳市1 026份农民工调查数据为依据,使用Oprobit模型和PSM模型,分析了务工距离对农民工留城意愿的影响。结果表明:务工距离显著影响个体的留城意愿,当务工距离越远时,农民工的留城意愿相应越低,这一结论在克服选择性偏差后依然成立。务工距离也对农民工的家庭迁移行为产生显著负向影响,务工距离越远农民工越不大可能实现家庭式迁移和城市稳定定居。研究阐明了支持就近城镇化发展的国家战略。在此基础之上,提出了尊重农民工主观留城意愿、重点关注原户籍地与打工城市较近的农民工和吸引劳动力就近务工的政策建议。     

Anaesthesia in the fourth dimension. Is biological scaling relevant to veterinary anaesthesia?

Fundamental laws, such as gravity and thermodynamics, are in common use in the physical sciences but are less applicable to biology. However, although there are fewer biological laws relative to other disciplines, the ones that exist are of great importance, e.g. natural selection. Another example may be a new law of biological network design which explains observations on how metabolic rate changes as organisms change size. It has been known for some time that as animal size increases its metabolic rate falls ( Rubner 1883 ; Kleiber 1932 ; Adolph 1949 ; Schmidt‐Nielsen 1984 ; Calabrese 1991 ). This has developed from a physiological curiosity to a tool that is used extensively to predict drug effects across species ( Lave et al. 1999 ). The function of this article is to review the development of this concept, and to examine its application in veterinary anaesthesia.     

土地资源禀赋对农业转移人口进城落户意愿的影响研究

提高农业转移人口的进城落户意愿是推动户籍人口城镇化发展的重要途径。然而,当下各地农业转移人口进城落户积极性不高,提升户籍人口城镇化率并不乐观。基于推拉理论,利用中国流动人口动态监测调查数据(CMDS),采用二元 Logit 模型与中介效应模型,分析土地资源禀赋对农业转移人口进城落户意愿的影响,探讨两者间的作用机制。结果表明,农业转移人口进城落户意愿总体较低,占比为48.91%,农业转移人口拥有承包地与宅基地的比例分别为61.40%和71.71%。土地资源禀赋显著抑制了农业转移人口的进城落户意愿,农业转移人口的身份认同、社会交往状况在土地资源禀赋影响进城落户意愿的过程中发挥着中介效应,社会保障状况发挥着显著的负向调节效应。进一步研究发现,土地流转将会提高农业转移人口的进城落户意愿。因此,一方面要加快农村土地制度改革与农民土地权益保障机制设计,消除阻碍农业转移人口进城落户的体制障碍;另一方面也要通过土地为农业转移人口留条退路,增强社会结构的弹性,维护社会稳定。     

Medetomidine immobilisation and atipamezole reversal in large estuarine crocodiles (Crocodylus porosus) using metabolically scaled dosages

Background Restraint of large estuarine crocodiles is potentially dangerous. Neuromuscular blockers and other immobilising drugs have been used with variable results. Medetomidine has been reported as a reliable, repeatable and reversible immobilisation agent in small estuarine crocodilians. Methods and Results Two wild and two farmed male animals, between 3.05 and 4.6 m long, were hand‐injected into a triceps muscle with a metabolically scaled medetomidine dosage. Immobilisation occurred within 30 min. At the conclusion of the procedures, 70 min after medetomidine administration, three animals were injected with atipamezole IM into the opposite triceps muscle at a dosage based on body surface area. Reversal occurred within 5 min. The fourth animal was intubated prior to reversal of medetomidine and maintained on isoflurane anaesthesia for a gastrotomy. All animals were monitored closely post recovery and then regularly for at least 1 week. Conclusions Medetomidine at a metabolically scaled dosage delivered IM into the forelimb was effective for immobilising large estuarine crocodiles for at least 40 min. Atipamezole administered at a dosage calculated as a function of surface area effectively reversed this immobilisation.     

Relationship between metabolic rate in vitro and body mass in a marine teleost,porgy Pagrus major

The rate of oxygen consumption of minced whole body was determined volumetrically, as an indication of metabolic rate in vitro (M _{in vitro} ), at 20°C in porgy Pagrus major ranging from 0.0002 g (just after hatch) to 2.9 g (67 days old) in body mass. A triphasic relationship was found between M _{in vitro} of individual fish (l.min^–1) and wet body mass W (g). During the prolarval stage accompanied with the transitional period to the postlarval stage (0.00020–0.00023 g, 0–6 days old), the mass-specific metabolic rate in vitro (M _{in vitro} /W in l.g^–1.min^–1) increased with age (D in days) as expressed by an equation M _{in vitro} /W = 3.88 + 0.74/D. During the postlarval stage (0.00031–0.003 g, 8–22 days old), M _{in vitro} /W remained almost constant, independent of body mass following an equation M _{in vitro} /W = 5.24 W^–0.085. During the juvenile and adolescent stages (0.0047–2.9 g, 30–67 days old), M _{in vitro} /W decreased with increasing body mass following an equation M _{in vitro} /W = 1.66 W^–0.235. These results correspond with the triphasic relationship between metabolism in vivo and body mass observed in intact porgy of 0.0002–270 g (Oikawa et al. 1991). It is concluded, therefore, that the dependence of mass-specific metabolic rate on body size exists in vitro as well as in vivo, during the early stages in the porgy. Based on these results, factors controlling the metabolism-size relationship are discussed.     

多维尺度配水模型研究

针对传统一维配水模型只能考虑1个变量的缺点,用多维尺度(MDS)模型构造了适应复杂流域的包含配水水量、用水区位置和用水区需水概率等变量的多维实时配水模型,并以黄河流域天然径流的配置为例,用MDS配水模型计算了黄河干流节点在一定区域需水概率情况下,天然径流量的配置情况。与传统一维配水模型计算结果相比,MDS配水模型可以分区域计算天然径流量的配置情况,并可以计算区域需水变化情况下各区域水量配置的调配情况。该模型的建立为区域的实时配水决策提供了方法上的参考。     

中原油田油井结垢分析与预测

为有效解决严重影响中原油田油井正常生产的结垢问题,对中原油田油井井筒结垢机理与结垢预测技术展开研究。采用Ryznar稳定指数法预测碳酸钙垢和经过校正温度、压力、离子强度的Oddo—Tomson饱和指数法预测硫酸盐结垢的数学模型和判据,在VisualBasic6．0环境下,使用VB语言,结合Access数据库以及基于面向对象的程序设计方法等编译了结垢趋势预测软件。通过现场水质资料进行碳酸钙和硫酸盐的结垢指数计算,以及油井垢样的组成分析,所得垢样成分与结垢趋势预测结果基本一致,说明该结垢趋势预测软件具有实际应用意义,能够快速、准确地预测结垢趋势,并能给出相应的解决方案和建议。（图3,表5,参13）     

Shifting trophic architecture of marine fisheries in New Zealand: Implications for guiding effective ecosystem‐based management

New Zealand has led the world in restoration of marine fisheries since the introduction of the Quota Management System in 1986, but challenges remain in minimizing the ecosystem‐level effects of industrialized fishing. We analysed existing long‐term fisheries data sets from 1931 to 2015 in New Zealand to resolve trends in important ecological properties of major exploited fish communities. Increases in community dissimilarities of catch composition in 1931 and 1972, followed by increasing total landings, highlight major expansions of fishing grounds and exploited species during these periods. Mirroring global patterns, the remarkable rise in fishing power, demand and generation of new markets in New Zealand have all contributed to this expansion. Marine Trophic Indices (MTIs) of landings have decreased together with total catch after the year 2000, reflecting smaller catches with a higher composition of lower trophic‐level species in recent years. Differences in relative abundance of species estimated between fisheries‐dependent and fisheries‐independent data were observed, where high‐value species displayed better agreement in relative abundance between data sets. Despite being under a Quota Management System, temporal development of MTI values relative to the timing of industrial expansion of fisheries was remarkably similar to those observed in the North Sea and Brazil, with a single expansion and decline. MTI values presented better long‐term stability in the US fisheries analysed. Analysis of long‐term data and the development of well‐resolved ecological baselines will be the first step towards applying EBM to New Zealand fisheries, in keeping with global trends in fisheries management.     

中国森林生态和野生植物类型自然保护区分布的均衡性

以中国森林生态和野生植物类型自然保护区为研究对象,以各省森林面积、自然保护区数量和面积为指标,利用基尼系数和均衡系数探讨我国森林生态和野生植物类型自然保护区分布的均衡性,利用多维标度法探讨各省两类自然保护区建设的相似性.结果表明,西部省份保护区面积占全国比例远高于保护区个数比例,而沿海省份保护区面积占全国比例远低于保护区个数比例;保护区级别越集中,各省保护区面积分布越不均衡,而数量分布越均衡.全国森林生态和野生植物类型自然保护区建设情况可分为4种类型,东南沿海省份设置的两类自然保护区面积远低于全国平均水平,而西部地区则高于全国平均水平.