Stretching of proteins in a uniform flow

Stretching of a protein by a fluid flow is compared to that in a force-clamp apparatus. The comparison is made within a simple topology-based dynamical model of a protein in which the effects of the flow are implemented using Langevin dynamics. We demonstrate that unfolding induced by a uniform flow shows a richer behavior than that in the force clamp. The dynamics of unfolding is found to depend strongly on the selection of the amino acid, usually one of the termini, which is anchored. These features offer potentially wider diagnostic tools to investigate structure of proteins compared to experiments based on the atomic force microscopy.Comment: J. Chem. Phys. (in press

Dual WDVV Equations in N=2 Supersymmetric Yang-Mills Theory

This paper studies the dual form of Witten-Dijkgraaf-Verlinde-Verlinde (WDVV) equations in N=2 supersymmetric Yang-Mills theory by applying a duality transformation to WDVV equations. The dual WDVV equations called in this paper are non-linear differential equations satisfied by dual prepotential and are found to have the same form with the original WDVV equations. However, in contrast with the case of weak coupling calculus, the perturbative part of dual prepotential itself does not satisfy the dual WDVV equations. Nevertheless, it is possible to show that the non-perturbative part of dual prepotential can be determined from dual WDVV equations, provided the perturbative part is given. As an example, the SU(4) case is presented. The non-perturbative dual prepotential derived in this way is consistent to the dual prepotential obtained by D'Hoker and Phong.Comment: misprints are corrected, revtex, 10 page

Folylpolyglutamate synthesis in a methionine auxotroph of Neurospora crassa

Folylpolyglutamate synthesis in a auxotroph of Neurospora crass

Glycine stimulates polyglutamyl folate synthesis in N. crassa

Glycine stimulates polyglutamyl folate synthesi

Advanced aeroservoelastic stabilization techniques for hypersonic flight vehicles

Advanced high performance vehicles, including Single-Stage-To-Orbit (SSTO) hypersonic flight vehicles, that are statically unstable, require higher bandwidth flight control systems to compensate for the instability resulting in interactions between the flight control system, the engine/propulsion dynamics, and the low frequency structural modes. Military specifications, such as MIL-F-9490D and MIL-F-87242, tend to limit treatment of structural modes to conventional gain stabilization techniques. The conventional gain stabilization techniques, however, introduce low frequency effective time delays which can be troublesome from a flying qualities standpoint. These time delays can be alleviated by appropriate blending of gain and phase stabilization techniques (referred to as Hybrid Phase Stabilization or HPS) for the low frequency structural modes. The potential of using HPS for compensating structural mode interaction was previously explored. It was shown that effective time delay was significantly reduced with the use of HPS; however, the HPS design was seen to have greater residual response than a conventional gain stablized design. Additional work performed to advance and refine the HPS design procedure, to further develop residual response metrics as a basis for alternative structural stability specifications, and to develop strategies for validating HPS design and specification concepts in manned simulation is presented. Stabilization design sensitivity to structural uncertainties and aircraft-centered requirements are also assessed

Faces and Eyes in Human Lateral Prefrontal Cortex

Much of the work on face-selective neural activity has focused on posterior, ventral areas of the human and non-human primate brain. However, electrophysiological and fMRI studies have identified face responses in the prefrontal cortex. Here we used fMRI to characterize these responses in the human prefrontal cortex compared with face selectivity in posterior ventral region. We examined a region at the junction of the right inferior frontal sulcus and the precentral sulcus (right inferior frontal junction or rIFJ) that responds more to faces than to several other object categories. We find that the rIFJ and the right fusiform face area (rFFA) are broadly similar in their responses to whole faces, headless bodies, tools, and scenes. Strikingly, however, while the rFFA preferentially responds to the whole face, the rIFJ response to faces appears to be driven primarily by the eyes. This dissociation provides clues to the functional role of the rIFJ face response. We speculate on this role with reference to emotion perception, gaze perception, and to behavioral relevance more generally