Hedgehog and Wnt family proteins can act as classic developmental morphogens to pattern a field of nai;ve cells. Surprising new studies show that members of these same protein families also act as guidance cues for growing axons in the developing nervous system.

We study on finite unramified extensions of global function fields (function fields of one valuable over a finite field). We show two results. One is an extension of Perret’s result about the ideal class group problem. Another is a construction of a geometric Zp-extension which has a certain property.

This flash examines trends in market participation by smallholder farmers in rural central and northern Mozambique between 2008, when prices of many commodities rose to previously unseen levels, and 2011. Using panel data for 2008 and 2011, the analysis describes marketing dynamics – entry, exit, and persistence of participation, and the trends in marketing intensity associated with those dynam...

Most neuronal populations form on both the left and right sides of the brain. Their efferent axons appear to grow synchronously along similar pathways on each side, although the neurons or their environment often differ between the two hemispheres [1-4]. How this coordination is controlled has received little attention. Frequently, neurons establish interhemispheric connections, which can funct...

We present a design of a leaderless formation controller for networked vehicle systems, which uses concepts from sliding mode control and dynamic extension. A single gain varies the importance of the relative and absolute position terms, allowing for tight or loose formations. This approach is proven mesh stable. Applications include formation flying of Unmanned Air Vehicles as well as possible...

Convergent extension (CE), a kinematic motif associated with several important morphogenetic movements in embryos, entails narrowing of a tissue in one in-plane direction and elongation in the other. Although the cell elongation and intercalation which accompany this process have been investigated and relevant genes and biochemical pathways have been studied in multiple organisms, a fundamental...

Convergent extension behaviour is critical for the formation of the vertebrate body axis. In Xenopus, components of the Wnt signaling pathway have been shown to be required for convergent extension movements but the relationship between cell fate and morphogenesis is little understood. We show by loss of function analysis that Xnr3 activates Xbra expression through FGFR1. We show that eFGF acti...

Convergent extension movements occur ubiquitously in animal development. This special type of cell movement is controlled by the Wnt/planar cell polarity (PCP) pathway. Here we show that Xenopus paraxial protocadherin (XPAPC) functionally interacts with the Wnt/PCP pathway in the control of convergence and extension (CE) movements in Xenopus laevis. XPAPC functions as a signalling molecule that...