Analysis of the data processing strategies of spherical harmonic expansion model on global ionosphere mapping for moderate solar activity

Spherical harmonic (SH) expansion is widely used to model the global ionosphere map (GIM) of vertical total electron content (VTEC). According to the impact of different data processing methods of the SH expansion model on the VTEC maps, we specifically performed comprehensive analysis in terms of the data sampling rate, the time resolution, the spherical harmonic degree, and the relative constraint. One month of GPS data (January in 2016) from the International GNSS (Global Navigation Satellite System) Service (IGS) network in a moderate ionospheric activity period at the descending phase of Solar Cycle 24 was processed. To improve the computational efficiency of the daily GIM generation, the data sampling rate of 5?min was recommended allowing the GIM precision loss within 0.10 TECU (total electron content unit). The global VTEC map could be better represented in temporal and spatial domains with higher time resolution and higher spherical harmonic degree, especially at low latitude bands and in the southern hemisphere. The GIM precision improvement was about 10.91% for 1-h and about 15.15% for 0.5-h compared with the commonly used 2-h time resolution. The use of spherical harmonic degree 17 or 20 instead of 15 could improve the precision by 3.19% or 6.06%. We also found that an optimal relative constraint had to be found experimentally considering both the GIM precision and the GIM root mean square (RMS) map.     

内科临床教学中PBL教学法结合思维导图的应用

目的探讨内科临床教学中PBL教学法结合思维导图的应用价值。方法以大理大学2015级一个班级在医院见习的55名本科生作为研究对象,数据收集时间为2019年5月;按照授课方式的差异将学生分为实验班与对照班,实验班27名学生,对照班28名学生;对照班实施常规教学法,实验班PBL教学法结合实施思维导图,对比两种教学方法的效果。结果实验班医学生的客观题得分为(84.59±2.58)分,病例分析题得分为(90.26±2.61)分,上述指标得分均高于对照班医学生,差异具有统计学意义(P<0.05);实验班满意度评分高于对照班评分,差异具有统计学意义(P<0.05)。结论在内科临床教学中PBL教学法结合思维导图的应用,能够更好地提升医学生的理论知识与实践操作技能。     

GNSS-R DDM波形仿真的时延与多普勒间隔研究

DDM波形是GNSS-R技术用于反演地球物理参量的基本观测量,其仿真结果的可靠性直接影响GNSS-R的理论研究及项目工程参数设计。利用GREEPS仿真软件分析了时延间隔与多普勒间隔对DDM波形仿真结果可靠性的影响,得到了用于获取可靠DDM仿真波形的时延与多普勒间隔参数。研究表明,时延和多普勒间隔越小,DDM仿真波形与理论波形吻合度越高;当时延间隔取1/16个GPS L1 C/A码元、多普勒间隔取50 Hz时,DDM仿真波形与理论波形几乎完全吻合,二者的相关系数大于0.99;时延间隔对DDM仿真波形峰值位置的影响远大于对峰值信噪比的影响;而多普勒间隔对DDM仿真波形峰值位置与信噪比的影响相当。     

《经济地理》创刊以来的知识溢出特征与变化

基于引证关系,利用知识图谱、社会网络分析等方法,对1981—2019年《经济地理》创刊以来知识溢出的特征与变化规律进行分析。经济地理学研究的专业综合性、学科交叉性特点,在《经济地理》期刊知识溢出的特征与变化中得以充分诠释。期刊知识溢出的作用与变化,不仅体现在促进作者合作网络形成与机构合作关系的深化上,也体现在对城市化、区域经济发展、区域旅游发展等研究领域的推动作用与变化上。期刊知识溢出的特征与变化在其主题构成、作者贡献、机构力量与前沿引领等的探讨中进一步得以明确。具体地,城市化研究的知识溢出作用,从城市化和城镇化、土地利用、生态环境等方面,逐渐转向新型城镇化、城市网络、生态环境、协调发展等主题;区域经济发展研究的知识溢出作用,经历了从经济联系转向产业集群、再转向空间相互作用关系的主题变化;区域旅游发展研究的知识溢出作用,则从旅游资源、旅游业、生态旅游等方面,逐步转向乡村旅游、旅游经济与协调发展等主题。以国家战略与发展政策为主要导向,促进国内经济地理学的研究与发展,是《经济地理》期刊知识溢出的核心内容与集中反映。     

High resolution genetic mapping uncovers chitin synthase-1 as the target-site of the structurally diverse mite growth inhibitors clofentezine,hexythiazox and etoxazole in Tetranychus urticae

The acaricides clofentezine, hexythiazox and etoxazole are commonly referred to as ‘mite growth inhibitors’, and clofentezine and hexythiazox have been used successfully for the integrated control of plant mite pests for decades. Although they are still important today, their mode of action has remained elusive. Recently, a mutation in chitin synthase 1 (CHS1) was linked to etoxazole resistance. In this study, we identified and investigated a Tetranychus urticae strain (HexR) harboring recessive, monogenic resistance to each of hexythiazox, clofentezine, and etoxazole. To elucidate if there is a common genetic basis for the observed cross-resistance, we adapted a previously developed bulk segregant analysis method to map with high resolution a single, shared resistance locus for all three compounds. This finding indicates that the underlying molecular basis for resistance to all three compounds is identical. This locus is centered on the CHS1 gene, and as supported by additional genetic and biochemical studies, a non-synonymous variant (I1017F) in CHS1 associates with resistance to each of the tested acaricides in HexR. Our findings thus demonstrate a shared molecular mode of action for the chemically diverse mite growth inhibitors clofentezine, hexythiazox and etoxazole as inhibitors of an essential, non-catalytic activity of CHS1. Given the previously documented cross-resistance between clofentezine, hexythiazox and the benzyolphenylurea (BPU) compounds flufenoxuron and cycloxuron, CHS1 should be also considered as a potential target-site of insecticidal BPUs.     

Chromosomal assignment of porcine microsatellites by use of a somatic cell hybrid mapping panel

A well-established and characterized somatic cell hybrid panel was used to map three polymorphic microsatellites. Microsatellite S0072, representing the linkage group S0007-S0072, was assigned to porcine chromosome 14. Micro-satellite S0009, representing the unassigned linkage group EAM-S0009-S0071, was assigned tentatively to porcine chromosome 11. Finally, S0062 was tentatively mapped to chromosome 18. S0062 may represent the first marker for porcine chromosome 18.