BACKGROUND Studies in unicellular systems have established that DNA damage by irradiation invokes a checkpoint that acts to stall cell division. During metazoan development, the modulation of cell division by checkpoints must occur in the context of gastrulation, differential gene expression and changes in cell cycle regulation. To understand the effects of checkpoint activation in a developmen...

We numerically investigate the application of steady blowing to three-dimensional stalled flows around low-aspect-ratio rectangular flat-plate wings at a Reynolds number of 300. The objective of this study is to explore techniques to enhance lift by directly modifying the dynamics of the wake vortices. Out of various combinations of forcing location and direction considered, we identify two con...

Bidirectional cargo transport by molecular motors in cells is a complex phenomenon in which the cargo (usually a vesicle) alternately moves in retrograde and anterograde directions. In this case, teams of oppositely pulling motors (e.g., kinesin and dynein) bind to the cargo, simultaneously, and 'coordinate' their activity such that the motion consists of spells of positively and negatively dir...

Wind tunnel experiments have shown that bumps on the leading edge of model humpback whale flippers cause them to "stall" (i.e., lose lift dramatically) more gradually and at a higher angle of attack. Here we develop an aerodynamic model which explains the observed increase in stall angle. The model predicts that as the amplitude of the bumps is increased, the lift curve flattens out, leading to...

Wind tunnel experiments were conducted to understand boundary layer separation control on airfoils. The objective of this research was to better implement flow control strategies with single dielectric barrier discharge (SDBD) plasma actuator designs for airfoils that exhibit both leading and trailing edge stall characteristics at realistic flight speeds and Reynolds numbers. The NASA energy ef...

Ribosome stalling on mRNAs can decrease protein expression. To decipher ribosome kinetics at stall sites, we induced ribosome stalling at specific codons by starving the bacterium Escherichia coli for the cognate amino acid. We measured protein synthesis rates from a reporter library of over 100 variants that encoded systematic perturbations of translation initiation rate, the number of stall s...

In this short paper we briefly describe the results of analyzing a large-scale data set of actual YouTube stall patterns collected world-wide as part of Columbia University’s YouSlow project, and how we used it to create a simple model for generating realistic stalling patterns with a given number of stalls, a given average stall duration, and a pattern structure (describing the relative length...

Based on a detailed analysis of recent loss-of-control events, the Aircraft State Awareness Joint Safety Analysis Team has identified the need to develop algorithms and display strategies to provide control guidance for recovery from approach-to-stall or stall. In order to be effective, such guidance should enhance the pilot’s ability to execute the Federal Aviation Administration’s recommended...