基于Voronoi图的城市体系空间结构及吸引范围——以广东省为例

城市体系空间结构是城镇化的基本载体,构建科学合理的城市体系空间结构是推进新型城镇化的重要内容. 为准确把握广东省的城市体系空间结构特征,使用Voronoi图空间组织方法和加权Voronoi图空间分割方法,以城市综合实力为质量属性,统合考察城市的地理区位和空间关系,对广东省县级以上城市的城市体系空间结构及吸引范围进行研究,得出以下结论：（1）广东省城市发展空间极化现象明显,城市综合发展水平存在较大差距;（2）在城市体系空间结构上,广东省形成了全域性中心城市区域性中心城市地方性中心城市一般性城市4个层级的城市体系空间结构;（3）从城市吸引范围分析,广东省部分城市存在同城化发展现象,其中广佛和潮汕同城趋势明显;（4）广东省城市的综合实力与其空间结构等级间存在明显的错位现象,因此应该进一步明确实力强等级低的城市的区域定位和职能定位,同时加快综合实力较弱的中心城市的发展,缩小发展差距,实现区域协调.     

句法视角下城市道路交通的预测研究——以广州市人民路高架桥拆除问题为例

基于空间句法理论中较前沿的NAchoice算法,着眼于我国第一座城市高架桥广州市人民路高架桥拆除问题进行案例分析,为空间句法在中国城市交通预测中的应用提供实证,探寻一种较好拟合实际交通流的预测模型,为路网优化提供参考依据. 论证分析从广州人民南路段交通堵塞原因、拆桥与否对桥下路段车流的影响、人民路段周边主干道交通疏导能力评估等3个方面展开,研究发现：（1）车流量偏大是人民南路段交通堵塞问题频发的原因之一;（2）高架桥的拆除会小幅增加桥底路段车流,但不一定会造成车流量的叠加式剧增;（3）人民路段及其周围主干道分流能力受到质疑,建议等到有较强疏导能力路段建成后,再拆除人民路高架桥;（4）空间句法NAchoice模型与广州市交通流数据具有较好拟合程度,运用该模型进行城市道路交通预测具有可行性.     

Co-Ti共掺杂M型六角钡铁氧体磁电耦合研究

磁电多铁性材料兼具电极化及磁性,可用于构建新型传感器和高密度存储器件．但对于单相多铁性材料,大多工作温度低且所需磁场强度较高,无法满足实用化需求．近来发现六角铁氧体可明显提高这两方面特性,但还需提高其工作温度及电阻率．我们采用Co-Ti元素对M-型钡六角铁氧体进行大剂量共掺杂,制备一系列的铁氧体陶瓷BaFe12-2xCoxTixO19 (x=0~4)．同时利用物理性能综合测试仪（PPMS）及其他检测仪器搭建了一套磁电测试系统,并结合LabVIEW软件进行编程,对样品的磁性、电性、磁介电和磁电耦合特性进行系统表征．结果表明,Co-Ti共掺杂可显著改变M型钡六角铁氧体的矫顽场及饱和磁化强度．同时,这种掺杂可使漏电流降低到3个量级（掺杂量x=2）．值得一提的是,我们在掺杂量为x=2的样品中观测到室温下的磁介电效应,同时在100K以下观测到明显的磁致铁电极化,且其电极化方向可以被磁场反转．该结果在探索新型多铁六角铁氧体及推进其应用化进程具有一定的意义．     

Ce-MCM-41分子筛催化臭氧氧化水中腐殖酸

采用水热法合成铈掺杂MCM-41（Ce-MCM-41）介孔分子筛,并将其用于臭氧氧化水中腐殖酸.本文研究了催化剂投加量、铈掺杂量、反应温度和初始pH对腐殖酸降解及矿化的影响. 结果表明,腐殖酸在Ce-MCM-41/O3体系内可实现有效降解. 与单独臭氧氧化相比,Ce-MCM-41催化剂的加入可提高臭氧氧化腐殖酸的矿化效果. 催化剂投加量为100 mg/L时,催化剂具有较好的催化活性,反应60min,DOC去除率为70.58%（Si/Ce=80）;三种铈掺杂量催化剂的添加均能提高腐殖酸矿化效果. 在278 ~308 K实验范围内,腐殖酸溶液的DOC去除率和UV254去除率均随反应温度升高而提高.溶液初始pH为6.0~8.5时,DOC去除率随碱性增强而略微下降. 表明温度和溶液初始pH影响催化臭氧氧化去除腐殖酸的效果. 此外,还考察了添加Ce-MCM-41对含溴水臭氧氧化过程中溴酸盐生成的影响,与单独臭氧相比,1.00 g Ce-MCM-41分子筛的加入减少了46.94%溴酸盐生成. 结果表明添加Ce-MCM-41分子筛可抑制溴酸盐的生成. 因此Ce-MCM-41分子筛可用于提高臭氧氧化腐殖酸效果和减少含溴水臭氧氧化过程中溴酸盐的生成.     

Debunking material induction

In this paper, we present an explanatory objection to Norton's material theory of induction, as applied to predictive inferences. According to the objection we present, there is an explanatory disconnect between our beliefs about the future and the relevant future facts. We argue that if we recognize such a disconnect, we are no longer rationally entitled to our future beliefs.     

A new species and the phylogeny of the South American genus Gromphas Brullé, 1837 (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini)

Gromphas jardim Cupello & Vaz-de-Mello sp. nov. is described from Bolivia and Central Brazil and is endemic to the biogeographic province of Rondônia. It resembles Gromphas amazonica and Gromphas inermis, but is distinguished primarily by the pattern of pronotal granulation and the form of the apical tubercle of male protibiae, which is modified in a tapered spur. Based on 31 morphological characters, a phylogenetic analysis returned a single most parsimonious tree where Gromphas is monophyletic and has the following internal topology: ((G. aeruginosa + G. lemoinei) (G. dichroa (G. inermis (G. amazonica + G. jardim)))).     

Sperm viability in the reproductive tract of females in a population of Sceloporus mucronatus exhibiting asynchronous reproduction

Asynchronous reproduction is a common phenomenon in high-elevation populations of lizards from Central México. Sperm storage in the reproductive tract of females is the mechanism for making oocyte fertilization possible. Our study addresses questions related to functional oviductal sperm storage of females mating on different dates throughout the reproductive season. A population of Sceloporus mucronatus with copulation in the summer and ovulation in the fall was chosen for this experiment. Eleven females that copulated in the field during June and 13 females that copulated in captivity during August were maintained in the laboratory until parturition. The number of pregnant females and the litter sizes produced in each experimental group were indicative of the viability of the stored sperm. Sperm stored in the reproductive tract of females were able to fertilize eggs after 4 months. No significant differences were found in the number of pregnant females between the 2 experimental groups nor in the litter sizes that they produced. We found that the amount of time sperm were held in the female reproductive tract (ca. 3 months) had no effect on the capacity of sperm to fertilize eggs. Histological examination of 8 oviducts collected before the mating season eliminated the possibility of sperm storage from one year to the next. In this system, sperm retention could have evolved as a response mechanism to deal with the asynchrony between sexes in the reproductive cycles. However, we cannot rule out alternative hypotheses.     

Substances thioloprives

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