Photonic orbital angular momentum with controllable orientation

Vortices are whirling disturbances, commonly found in nature, ranging from tremendously small scales in Bose-Einstein condensations to cosmologically colossal scales in spiral galaxies. An optical vortex, generally associated with a spiral phase, can carry orbital angular momentum (OAM). The optical OAM can either be in the longitudinal direction if the spiral phase twists in the spatial domain or in the transverse direction if the phase rotates in the spatiotemporal domain. In this article, we demonstrate the intersection of spatiotemporal vortices and spatial vortices in a wave packet. As a result of this intersection, the wave packet hosts a tilted OAM that provides an additional degree of freedom to the applications that harness the OAM of photons.     

信息化水平测度指标体系理论研究述评

本文主要从信息经济和信息社会角度,对国内外主要的信息化水平测度指标体系的形成理论和指标设计进行评述,指出这些指标体系的合理性和不足之处,进而提出信息化水平测度指标体系构建的理论基础以及选取指标时需要注意的问题。     

我国科技期刊OA现状和发展策略研究

文章通过调研我国科技期刊开放存取（Open Access,简称OA）的发展现状,对我国科技期刊OA的数量、分布以及开放全文的特征进行了分析,找出目前我国科技期刊OA存在的主要问题,并对影响开放存取发展的各类因素进行了探析,最后从提升影响力、营造良好的宏观环境等方面对我国的科技期刊OA的发展提出有效的策略及建议。     

网络环境下信息过滤机制及其实现研究

论述了信息过滤研究的原理、模型以及目前的主要应用领域,并在此基础上设计了一个针对图书情报机构和特定学术用户的基于异构多代理的Web信息过滤推荐系统。     

Knee extensor and flexor torque development with concentric and eccentric isokinetic training

This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training increased ECC knee extension and flexion peak torque more than CON training. The ECC group improved acceleration time and time to peak torque with ECC movements versus the CON group. Slow-velocity ECC isokinetic training yielded greater ECC and similar CON torque development gains versus CON training over the course of 20 weeks in young women.     

The graph-theoretic field model— II. application of multi-terminal representations to field problems

This paper is a sequel to a paper entitled “The Graph-Theoretic Field Model—I: Modelling and Formulations” (1). Herein, the Theory of Multi-Terminal Representations is applied to the Graph-Theoretic Field Model to provide mathematical models of finite elements. The element models are obtained solely from the algebraic building blocks of the Graph-Theoretic Field Model, without recourse to any functional mathematics. The theory of Multi-Terminal Representations is developed for both linear and non-linear problems. Examples of the application of the theory to one- and two-dimensional field problems are presented from heat conduction and electrostatics.