M igrating cells move forward by harnessing the force of actin polymerization to form a protru-sive lamellipodium at the leading edge. A protein called Lamellipodin (Lpd) promotes lamellipodium formation, but how it does so is unclear. Law et al. reveal that Lpd generates membrane protrusions in association with a key regulator of actin branching called the Scar/WAVE complex and that this inter...

Migrating fi broblasts assemble a dendritic network of branched actin fi laments that drives the formation of a lamellipodial protrusion at their leading edge. Haynes et al. reveal that, like a topiarist guiding the growth of a tree, a protein called GMF␤ " prunes " this actin network in order to guide the cell's migration towards certain directional cues (1). Branched actin networks form when ...

We develop some useful techinques for integrating over Higgs branches in supersymmetric theories with 4 and 8 supercharges. In particular, we define a regularized volume for hyperkahler quotients. We evaluate this volume for certain ALE and ALF spaces in terms of the hyperkahler periods. We also reduce these volumes for a large class of hyperkahler quotients to simpler integrals. These quotient...

The politics of the Internet is a common theme in cybertheory, though commentators work with a variety of different notions of the political. Among the main issues are the question of whether the Internet may enhance or detract from the processes of deliberation traditionally seen as crucial to a strong civil society, along with that of whether online voting could usher in an era direct democra...

This study examined Leonardo da Vinci's rule (i.e., the sum of the cross-sectional area of all tree branches above a branching point at any height is equal to the cross-sectional area of the trunk or the branch immediately below the branching point) using simulations based on two biomechanical models: the uniform stress and elastic similarity models. Model calculations of the daughter/mother ra...

The authors observed in 60 human spleens the course of the splenic artery in the splenic hilus and branching of segmental branches in the spleen. Specimens of blood vessels and casts showed two extreme types of segmental branches entering the splenic parenchyma: 1. Vertical type and 2. subcapsular type. The authors also studied the occurrence of anastomoses between the individual branches of th...