On the origin of microbial magnetoreception

A broad range of organisms, from prokaryotes to higher animals, have the ability to sense and utilize Earth''s geomagnetic field—a behavior known as magnetoreception. Although our knowledge of the physiological mechanisms of magnetoreception has increased substantially over recent decades, the origin of this behavior remains a fundamental question in evolutionary biology. Despite this, there is growing evidence that magnetic iron mineral biosynthesis by prokaryotes may represent the earliest form of biogenic magnetic sensors on Earth. Here, we integrate new data from microbiology, geology and nanotechnology, and propose that initial biomineralization of intracellular iron nanoparticles in early life evolved as a mechanism for mitigating the toxicity of reactive oxygen species (ROS), as ultraviolet radiation and free-iron-generated ROS would have been a major environmental challenge for life on early Earth. This iron-based system could have later been co-opted as a magnetic sensor for magnetoreception in microorganisms, suggesting an origin of microbial magnetoreception as the result of the evolutionary process of exaptation.     

Resolving dynamics of inertial migration in straight and curved microchannels by direct cross-sectional imaging

The explosive development of inertial microfluidic systems for label-free sorting and isolation of cells demands improved understanding of the underlying physics that dictate the intriguing phenomenon of size-dependent migration in microchannels. Despite recent advances in the physics underlying inertial migration, migration dynamics in 3D is not fully understood. These investigations are hampered by the lack of easy access to the channel cross section. In this work, we report on a simple method of direct imaging of the channel cross section that is orthogonal to the flow direction using a common inverted microscope, providing vital information on the 3D cross-sectional migration dynamics. We use this approach to revisit particle migration in both straight and curved microchannels. In the rectangular channel, the high-resolution cross-sectional images unambiguously confirm the two-stage migration model proposed earlier. In the curved channel, we found two vertical equilibrium positions and elucidate the size-dependent vertical and horizontal migration dynamics. Based on these results, we propose a critical ratio of blockage ratio (β) to Dean number (De) where no net lateral migration occurs (β/De ∼ 0.01). This dimensionless number (β/De) predicts the direction of lateral migration (inward or outward) in curved and spiral channels, and thus serves as a guideline in design of such channels for particle and cell separation applications. Ultimately, the new approach to direct imaging of the channel cross section enables a wealth of previously unavailable information on the dynamics of inertial migration, which serves to improve our understanding of the underlying physics.     

Historical review of sports policy in rural China (1949-2008)

The rural population in China remains in the majority, and has traditionally played a key role in the development of China. This paper outlines the rhetoric of, and the material changes in the development of rural sports policy in the period since 1949. In effect this represents the largest single programmatic attempt to develop a rural sports policy, and it is one which reflects and contributes to the changing ideology of the state in China. The article explores the historical context of the unfolding of rural sports policy, the rationales provided by state and party leaders and representatives, and the rhetoric employed in supporting such policy direction. The development of policy is described as falling into three periods. From 1949 to 1977 the emphasis was on developing policies to promote labour production and national defence. This was succeeded by a period from 1978 to 2001 in which the major focus was on promoting a culturally positive environment (the construction of a 'spiritual civilization'), while in the period 2002 -08 the concern was with promoting equity and reducing the gap between urban and rural life quality. These developing rationales have sought in a variety of ways to address the major imbalances that exist in Chinese society between urban and rural, Eastern and Western China, and sports policy has thus became a significant tool in China's modernization agenda in the rural context.     

Secondary Pupils' Experiences of Name-calling Behaviour

Studies carried out in Scandinavia and the UK have identified name-calling as highly problematic for young people. The research described in this paper, conducted by Peer and School Counsellors, examines name-calling behaviour through the personal accounts of first-year pupils in a secondary school. Moving on from anonymous questionnaires, discourse analysis of individual interviews is shown to reveal the dilemma for those most vulnerable. Parental advice and primary school experience affect the repertoire of pupils' responses adopted, with varying degrees of success, in secondary school.