Tumor blood vessels deliver oxygen poorly, thereby contributing to tumor hypoxia and upregulation of proangiogenic cytokines in an escalating feedback loop. Mazzone et al. (2009) now show that reducing the amount of a protein involved in endothelial oxygen sensing leads to changes in endothelial cell shape that interrupt this feedback loop and reduce tumor metastasis.

Time-delays are important components of many dynamical systems that describe coupling or interconnection between dynamics, propagation or transport phenomena, and heredity and competition in population dynamics. The stabilization with time delay in observation or control represents difficult mathematical challenges in the control of distributed parameter systems. It is well-known that the stabi...

N egative feedback techniques are widely used in analog and RF design to improve circuit properties such as variation tolerance, bandwidth, impedance matching, and output waveform distortion. In practice, unwanted local return loops also exist around individual transistors through parasitic capacitance. As the size of transistors continues to shrink and the bandwidth of transistors continues to...