Commuting distances to local non‐farm workplaces and out‐migration: The case of Northeast Thailand

The relationship between commuting distances and where people work has been studied for urban contexts in both developed countries and developing countries. However, few studies have examined the situation in rural areas, and none look at commuting distances to non‐farm workplaces in rural areas of developing countries. This paper investigates how commuting distance, and thus accessibility, to local non‐farm work influences non‐farm employment and out‐migration from rural villages in Northeast Thailand. The main issues examined are: (i) the distance that rural residents travel to work in local non‐farm jobs; and (ii) the influence that local non‐farm employment has on the number of outmigrants from rural villages. The study finds: (i) distance between villages and non‐farm work sites impact the number of villagers who are employed in regular wage work; (ii) beyond 20 km villagers are less likely to travel to non‐farm employment using their own means of transportation; and (iii) employment in regular wage work decreases outmigration. The findings from this study contribute to the debates over the drivers of rural out‐migration, rural livelihood changes, and agrarian changes that are taking place in Southeast Asia.     

Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non‐target species

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV‐3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV‐3 of a range of non‐target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100–1000 times the approximate minimum amount of CyHV‐3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post‐challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV‐3, and, in particular, all RT‐PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV‐3 as a potential biocontrol agent that is specific for carp.     

双斜盘多排式轴向柱塞马达转矩特性分析

为了实现多级转速和转矩的输出,轴向柱塞马达必须使用节流阀、减压阀等耗能元件来改变输入压力和流量,但同时降低了效率。新型双斜盘多排式轴向柱塞马达可以利用其结构的特殊性,实现输出转矩的多样性。本文基于双斜盘多排式轴向柱塞马达的结构特点及工作原理,推导了该马达在不同工作方式下的理论瞬时转矩和转矩不均匀系数,并通过Matlab分析了内外马达转矩系数比对转矩不均匀系数的影响,设计了马达的实验液压系统并搭建了实验平台,对马达进行了原理性实验,并进行了数据分析。实验结果表明,在额定压力和额定排量下,该马达能实现多种不同的转速与转矩输出,随着内外马达转矩系数比的增大,低速大转矩的转矩不均匀系数越小,高速低转矩不稳定系数越大,通过合理设计可以实现马达在不同工作状态下的稳定运行,验证了新型马达在结构原理上的可行性,为新型轴向柱塞马达的改进设计提供了实验依据。     

Development of a core set of KASP markers for assaying genetic diversity in Brassica rapa subsp. chinensis Makino

Single‐nucleotide polymorphisms (SNPs) are rapid, economical and reliable genotyping tools. Non‐heading Chinese cabbage (Brassica rapa L. subsp. chinensis Makino) is now an economically important vegetable crop worldwide. In this study, 1,167 SNPs were evaluated for 7polymorphism among 70 representative non‐heading Chinese cabbage inbred lines using a Kompetitive Allele Specific PCR (KASP) genotyping assay. On the basis of identified polymorphisms and the results of a principal component analysis, we selected 50 core SNPs that were balanced sufficiently to provide adequate information for genetic identification. The core SNPs were used for construction of a neighbour‐joining dendrogram that separated the 70 inbred lines into four main groups and several subgroups corresponding to Caixin, Heiyebaicai, Huangxinwu, Naibaicai, Taitsai, Pak‐choi, and Wutatsai. This categorization was superior to that achieved using a dataset of 479 polymorphic SNPs. To confirm the utility of the core SNP markers in genetic identification, we tested their stability and resolution using 162 commercial hybrid cultivars. The SNPs, which represent a cost‐effective, accurate marker set for germplasm analysis and cultivar identification, are suitable for molecular marker‐assisted breeding in non‐heading Chinese cabbage.     

Bacterial communities associated with natural and commercially grown rooibos (Aspalathus linearis)

Aspalathus linearis is a commercially important plant species endemic to the Cape Floristic Region of South Africa and is used to produce a herbal tea known as rooibos tea. Symbiotic interactions between A. linearis and soil bacteria play an important role in the survival of Aspalathus plants in the highly nutrient-poor, acidic fynbos soil. The aim of this study was to characterize and compare rhizosphere and bulk soil bacterial communities associated with natural and commercially grown A. linearis, as well as the effect of seasonal changes on these communities. Bacterial communities were characterized using high throughput amplicon sequencing, and their correlations with soil chemical properties were investigated. The N-fixing bacterial community was characterized using terminal restriction fragment length polymorphism and real time quantitative polymerase chain reaction. Actinobacteria, Proteobacteria, and Acidobacteria were the most dominant bacterial phyla detected in this study. Highly similar bacterial communities were associated with natural and commercially grown plants. Significant differences in the bacterial community were observed between rhizosphere and bulk soils collected in the dry season, while no significant differences were detected in the wet season. This study provides insights into bacterial community structure and potential factors shaping bacterial community structure with commercially important A. linearis.     

基于主成分与灰色关联分析的饲草小黑麦品种筛选与配套技术研究

为了筛选在山西省雁门关地区最适宜种植的小黑麦品种以及配套的高产优质栽培技术,利用主成分分析法和灰色关联度分析法综合评价不同小黑麦品种在不同密度和肥料条件下的产量和饲草品质。结果表明,小黑麦饲草品质指标中糖类和蛋白类指标变异较大,但是总的可消化养分以及能量品质变化较小。相关性分析表明,相对饲料价值（RFV）与粗蛋白含量、瘤胃降解蛋白含量、醇溶糖含量、总可消化养分、产奶净能、维持净能、增重净能和相对饲料质量（RFQ）均呈极显著正相关。RFV主要通过酸性和中性洗涤纤维计算而来,在单一指标中最能反映饲草品质。综合考虑灰色关联度和主成分分析方法,晋饲草1号（播种量150kg/hm²,复合肥750kg/hm²、尿素150kg/hm²）最适宜雁门关地区推广种植。     

Yersinia ruckeri—A threat not only to rainbow trout

Yersinia ruckeri (Y. ruckeri) can cause mortalities that are contributing to substantial economic losses in the rainbow trout (Oncorhynchus mykiss) aquaculture sector. Because of its most characteristic clinical signs, the disease in rainbow trout caused by this pathogen is called enteric redmouth disease. Although it is considered to affect mainly salmonids, there are reports in the available literature of isolating this bacterium from other fish species, both clinically healthy and diseased. The aim of this study was to analyse the available data concerning yersiniosis in non‐salmonid fish. The analysed data indicate that Y. ruckeri is a threat not only to rainbow trout. Some of the affected species have high commercial importance and mortalities may contribute to high economic losses. The disease symptoms may not be specific and can be different from those characteristic for enteric redmouth in trout, which may lead to misdiagnosis. Collected information indicates that infection with Y. ruckeri should be taken into account in the diagnostic procedures not only in salmonids.     

Developmental temperature affects phenotypic means and variability: A meta‐analysis of fish data

Fishes are sensitive to their thermal environment and face an uncertain future in a warming world. Theoretically, populations in novel environments might express greater levels of phenotypic variability to increase the chance of surviving—and eventually thriving—in the new conditions. Most research on the effect of the early thermal environment in fish species focuses on average phenotypic effects rather than phenotypic variability, but to understand how fishes will respond to rising temperatures we need to consider both the average response of the population, as well as the breadth of individual responses. Here we present the first meta‐analysis on the effects of developmental temperature in fishes. Using data from 43 species and over 6,000 individual fish, we show that a change in developmental temperature induces a significant change in phenotypic means and variability, but differently depending on whether the temperature is increased or decreased. Decreases in temperature (cool environments) showed a significant decrease in phenotypic means and no change in phenotypic variability. Increases in temperature (warm environments) showed a non‐significant increase in phenotypic means and a marginally significant increase in phenotypic variability. Larger increases in temperature saw greater increases in phenotypic variability, but no increase in the mean phenotypic response. Together, our results suggest that fishes exhibit both directed and stochastic developmental plasticity in response to warming temperatures, which could facilitate or accelerate adaptation to a changing environment.     

Asterosaponins: Structures,Taxonomic Distribution,Biogenesis and Biological Activities

Asterosaponins are a class of steroid oligoglycosides isolated from starfish with characteristic structures and diverse biological activities. In this review, we have attempted to combine the most important data concerning asterosaponins and give a list of these secondary metabolites with their structural peculiarities. The purpose of this review is to provide a brief but as complete as possible principal information about their chemical structures, taxonomic distribution in the marine environment, distribution in different geographical areas and depths, some properties, biological activities, and functions. Some other rare steroid metabolites from starfish, closely related in structures and probably biogenesis to asterosaponins, are also discussed.