几种蒸散模型在玉米农田蒸散量计算中的应用比较

模拟蒸散的物理过程,计算农田蒸散量是进行生态系统水资源评价和管理的重要手段,同时也是气象部门进行土壤湿度预报的首要条件.本研究以玉米农田为研究对象,基于涡度相关法观测的蒸散实测资料,比较分析了基于常规气象数据的蒸散模型(Hargreaves法、Priestlev-Taylor法、FAO-Penman-Monteith法)和基于气象梯度数据的蒸散模型(波文比法、梯度法、生态系统过程模型模拟)的模拟精度.结果表明:①Hargreaves法、Priestley-Taylor法和FAO-Penman-Monteith法日蒸散的模拟结果较为一致,总体上高估20%～26%,其中Priestley-Taylor法模拟结果最优;②生态系统过程模型模拟的农田日蒸散精度较高,但模型中涉及的物理过程和参数较多,在实际应用中难于获取;③波文比法在波文比小于0.4且仪器精度较高时可以得到较准确的估算值.研究同时还指出,仪器的安装高度及高差设计对梯度法估算蒸散十分重要.     

Pressure driven spinning: A multifaceted approach for preparing nanoscaled functionalized fibers, scaffolds, and membranes with advanced materials

Electrospinning, a flexible jet-based fiber, scaffold, and membrane fabrication approach, has been elucidated as having significance to the heath sciences. Its capabilities have been most impressive as it possesses the ability to spin composite fibers ranging from the nanometer to the micrometer scale. Nonetheless, electrospinning has limitations and hazards, negating its wider exploration, for example, the inability to handle highly conducting suspensions, to its hazardous high voltage. Hence, to date electrospinning has undergone an exhaustive research regime to a point of cliché. Thus, in the work reported herein we unveil a competing technique to electrospinning, which has overcome the above limitations and hazards yet comparable in capabilities. The fiber preparation approach unearthed herein is referred to as “pressure driven spinning (PDS).” The driving mechanism exploited in this fiber spinning process is the pressurized by-pass flow. This mechanism allows the drawing of either micro- or nanosized fibers while processing polymeric suspensions containing a wide range of advanced materials spanning structural, functional, and biological entities. Similar to electrospinning if the collection time of these continuous formed fibers is varied, composite scaffolds and membranes are generated. In keeping with our interests, multicompositional structural entities such as these could have several applications in biology and medicine, for example, ranging from the development of three-dimensional cultures (including disease models) to the development of synthetic tissues and organ structures to advanced approaches for controlled and targeted therapeutics.     

How Does It Look? Level 2 Perspective‐Taking at 36 Months of Age

Previous research has found that children engage in Level 2 visual perspective-taking, that is, the understanding that others may see things in a different way, between 4 and 5 years of age (e.g., J. H. Flavell, B. A. Everett, K. Croft, & E. R. Flavell, 1981). This ability was reexamined in 36-month-olds using color filters. In Experiment 1 (N = 24), children had to recognize how an object looked to an adult when she saw it through a color filter. In Experiment 2 (N = 24), a novel production test was applied. Results of both studies show that 36-month-olds know how an object looks to another person. The discussion focuses on the psychological requirements of visual perspective-taking and its relation to other "theory of mind" abilities, such as the distinction between appearance and reality and understanding false belief.     

What makes a landmark effective? Sex differences in a navigation task

In Experiment 1, two groups of female rats were trained in a triangular pool to find a hidden platform whose location was defined in terms of a single a landmark, a cylinder outside the pool. For one group, the landmark had only a single pattern (i.e., it looked the same when approached from any direction), while for the other, the landmark contained four different patterns (i.e., it looked different when approached from different directions). The first group learned to swim to the platform more rapidly than the second. Experiment 2 confirmed this difference when female rats were trained in a circular pool but found that male rats learned equally rapidly (and as rapidly as females trained with the single-pattern landmark) with both landmarks. This second finding was confirmed in Experiment 3. Finally, in Experiment 4a and 4b, male and female rats were trained either with the same, single-pattern landmark on all trials or with a different landmark each day. Males learned equally rapidly (and as rapidly as females trained with the unchanged landmark) whether the landmark changed or not. We conclude that male and female rats learn rather different things about the landmark that signals the location of the platform.     

A Model for Quantitatively Analyzing Representations of Social Class in Screen Media

Content analyses of prime-time television provide a picture of predominant cultural stereotypes and social trends. The present research is a quantitative content analysis of social class in popular broadcast and cable television in the United States. This research advances scholarship by systematically analyzing character class in addition to more commonly examined variables such as race and gender. A model for the operationalization of class for quantitative content analyses of mediated texts is offered. This proof of concept study demonstrates the viability of studying media representations of class quantitatively to systematically document patterns of portrayal.     

The neural correlates of working memory training in typically developing children

Working memory training improves children's cognitive performance on untrained tasks; however, little is known about the underlying neural mechanisms. This was investigated in 32 typically developing children aged 10–14 years (19 girls and 13 boys) using a randomized controlled design and multi-modal magnetic resonance imaging (Devon, UK; 2015–2016). Training improved working memory performance and increased intrinsic functional connectivity between the bilateral intraparietal sulci. Furthermore, improvements in working memory were associated with greater recruitment of the left middle frontal gyrus on a complex span task. Repeated engagement of fronto-parietal regions during training may increase their activity and functional connectivity over time, affording greater working memory performance. The plausibility of generalizable cognitive benefits from a neurobiological perspective and implications for neurodevelopmental theory are discussed.     

篮球战术基础配合定量评价方法研究

篮球战术基础配合的质量直接影响全队战术完成的效果和个人技术的发挥。长期以来对篮球战术基础配合运用效果的评价研究却很少见．且大多是定性分析。因此，力图研究一套定量评价与诊断篮球战术基础配合的方法，拟分析在比赛、训练、教学中篮球战术基础配合的运用效果。以定量化实现训练最佳的控制，为各级篮球教练员及教师服务。     

排名前10的与预防运动和体育活动猝死相关的关键问题

参加有组织的体育运动和休闲活动存在发生严重伤病甚至死亡的内在风险。虽然造成体育运动或体育活动中猝死的原因有很多,但运动医学和循证标准治疗方面的进展已使临床医生得以更有效地预防、发现和治疗可能致死的伤患。随着研究与技术不断发展进步,当前的治疗标准正在不断发展以更好地改善患者的治疗效果。本文提出了10个与运动和体育活动中猝死的主要原因及其治疗手段有关的关键问题,未来开展的研究将提高运动员和休闲运动爱好者参与运动的安全度。当前证据表明,如采取正确的预防策略或最佳治疗方案,绝大多数的死亡案例是可以避免的。     

A theory for decoupling lossless coupled tapered lines with applications to directional couplers

A simple theory is presented for decoupling a pair of lossless coupled nonuniform transmission lines (CNUTL), with a common return and supporting TEM waves, into two lossless nonuniform transmission lines (NUTL). This theory is independent of the port terminations, symmetry conditions, etc. The method directly relates the line parameters of the lossless CNUTL's to those of the decoupled lines and vice versa; further, the matrix parameters of the CNUTL's as a four-port are explicitly expressed in terms of those of the decoupled lines as two-ports. This theory is then utilized to study the applications of CNUTL's as directional couplers.It is shown that for CNUTL's to behave as a codirectional coupler, each of the decoupled lines should be a proportional line, while for contradirectional coupler action, the two decoupled lines have to be duals of each other. The coupling response of the codirectional coupler is found to be periodic, while the phase shift between coupled and transmitted signals varies linearly with frequency. The coupling response of various contradirectional couplers with smooth transition at one of the ends, for which the decoupled lines are “basic NUTL's with hyperbolic solutions”, are studied in detail. It is shown that all these couplers have a high-pass response and that the CNUTL's with “hyperbolic cosine squared lines” as decoupled lines have the best response of all the CNUTL's considered.