Fibroblast growth factor (FGF) 19 is an enterokine synthesized and released when bile acids are taken up into the ileum. We show that FGF19 stimulates hepatic protein and glycogen synthesis but does not induce lipogenesis. The effects of FGF19 are independent of the activity of either insulin or the protein kinase Akt and, instead, are mediated through a mitogen-activated protein kinase signaling pathway that activates components of the protein translation machinery and stimulates glycogen synthase activity. Mice lacking FGF15 (the mouse FGF19 ortholog) fail to properly maintain blood concentrations of glucose and normal postprandial amounts of liver glycogen. FGF19 treatment restored the loss of glycogen in diabetic animals lacking insulin. Thus, FGF19 activates a physiologically important, insulin-independent endocrine pathway that regulates hepatic protein and glycogen metabolism.

A mixing transition has been observed in a high-resolution large-eddy simulation of Rayleigh-Taylor instability. During the transition, an inertial range forms in the velocity spectrum and the rate of growth of the mixing zone is reduced. By measuring growth of the layer in units of dominant initial wavelength, criteria are established for reaching the hypothetical self-similar state of the mixing layer. A model including mixing effects is derived for the growth rate. The rate of growth of the mixing layer is determined by the net mass flux through the plane associated with the initial location of the interface. All of the information necessary for predicting the growth rate is contained in this plane. The model incorporates an effective Atwood number and provides a good match to the simulation data. The model suggests reduced growth for miscible fluids, compared to the immiscible case.

Abstract-When a heavy fluid is placed above a light fluid, tiny vertical perturbations in the interface create a characteristic structure of rising bubbles and falling spikes known as Rayleigh-Taylor instability. Rayleigh-Taylor instabilities have received much attention over the past half-century because of their importance in understanding many natural and man-made phenomena, ranging from the rate of formation of heavy elements in supernovae to the design of capsules for Inertial Confinement Fusion. We present a new approach to analyze Rayleigh-Taylor instabilities in which we extract a hierarchical segmentation of the mixing envelope surface to identify bubbles and analyze analogous segmentations of fields on the original interface plane. We compute meaningful statistical information that reveals the evolution of topological features and corroborates the observations made by scientists. We also use geometric tracking to follow the evolution of single bubbles and highlight merge/split events leading to the formation of the large and complex structures characteristic of the later stages. In particular we (i) Provide a formal definition of a bubble; (ii) Segment the envelope surface to identify bubbles; (iii) Provide a multi-scale analysis technique to produce statistical measures of bubble growth; (iv) Correlate bubble measurements with analysis of fields on the interface plane; (v) Track the evolution of individual bubbles over time. Our approach is based on the rigorous mathematical foundations of Morse theory and can be applied to a more general class of applications.

Experiments were conducted in which the behavior of scalar interfaces in turbulent jets was examined, using laser-induced fluorescence (LIF) techniques. The experiments were carried out in a high Schmidt number fluid (water), on the jet centerline, over a jet Reynolds number range of 1000

Hall effect, photoluminescence, and Schottky diode measurements were made on the Zn-polar and O-polar faces of undoped, bulk, single crystal, c-axis ZnO wafers. Significant polarity related differences were observed in the PL and Schottky diode characteristics of low carrier concentration, hydrothermally grown wafers. Increased emission from free exciton recombinations and from recombinations between 3.3725 and 3.3750eV was observed on the Zn-polar face. Conversely, emission between 3.3640 and 3.3680eV was more intense on the O-polar face. The barrier heights of silver oxide Schottky diodes were approximately 130meV larger on the Zn-polar face compared to the O-polar face.