The cytochemical localization of adenyl cyclase activity in rat sublingual gland

Adenyl cyclase activity in mucous acinar cells and serous demilune cells of the rat sublingual gland was localized cytochemically. After incubation with adenylyl-imidodiphosphate (AMP-PNP) as substrate, deposits of reaction product are found along the cell membranes bordering the secretory surfaces of serous demilune cells. These are the membranes which participate directly in secretion by fusing with the granule membranes. The granule membranes of the demilune cells do not reveal reaction product, but the membranes of the granules which are fused with and become part of the cell membrane do show deposits. Thus, it appears that the cell membranes which fuse with granule membranes during secretion are associated with a high level of adenyl cyclase activity. In support of this, the luminal membranes of the mucous acinar cells which do not fuse with granule membranes during secretion are not associated with detectable amounts of adenyl cyclase activity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49675/1/1001440407_ftp.pd

Double-Well Potential : The WKB Approximation with Phase Loss and Anharmonicity Effect

We derive a general WKB energy splitting formula in a double-well potential by incorporating both phase loss and anharmonicity effect in the usual WKB approximation. A bare application of the phase loss approach to the usual WKB method gives better results only for large separation between two potential minima. In the range of substantial tunneling, however, the phase loss approach with anharmonicity effect considered leads to a great improvement on the accuracy of the WKB approximation.Comment: 14 pages, revtex, 1 figure, will appear at Phys. Rev.

A finite element simulation for orthogonal cutting of UD-CFRP incorporating a novel fibre - matrix interface model

AbstractThe rapid increase in industrial utilisation of carbon fibre reinforced plastic (CFRP) composites in recent years has led to growing interest in numerical modelling of material behaviour and defect formation when machining CFRP. The inhomogeneous/anisotropic nature of CFRP however presents considerable challenges in accurately modelling workpiece defects such as debonding between the matrix and fibre phase following cutting operations. Much of the published literature has involved the use of zero thickness cohesive elements to represent the fibre-matrix interface, despite the inability of such elements to model compressive stresses. This paper details a new approach for characterising the interface region in a two-dimensional explicit finite element simulation when orthogonal machining unidirectional (UD) CFRP laminates. A cohesive zone model based on a traction-separation law is applied to small thickness (0.25μm) interface elements in order to accommodate compressive failure, which is implemented via a bespoke user subroutine. Fibre fracture is based on a maximum principal stress criterion while elastic-plastic behaviour to failure is used to represent matrix damage. The influence of varying fibre orientations (45°, 90°, 135°) on predicted cutting and thrust forces were validated against published experimental data. While the former was generally within 5% of experimental data for workpieces with 90° and 135° fibre directions, predicted thrust forces were typically underestimated by ∼30-60%. The corresponding chip formation mechanisms and sub-surface damage due to the different material phases were also investigated. The proposed model was able to predict composite behaviour and defect formation that was comparable to experimental high speed camera images outlined in the literature

Instantonic approach to triple well potential

By using a usual instanton method we obtain the energy splitting due to quantum tunneling through the triple well barrier. It is shown that the term related to the midpoint of the energy splitting in propagator is quite different from that of double well case, in that it is proportional to the algebraic average of the frequencies of the left and central wells.Comment: Revtex, 11 pages, Included one eps figur

A Multi-dimensional Code for Isothermal Magnetohydrodynamic Flows in Astrophysics

We present a multi-dimensional numerical code to solve isothermal magnetohydrodynamic (IMHD) equations for use in modeling astrophysical flows. First, we have built a one-dimensional code which is based on an explicit finite-difference method on an Eulerian grid, called the total variation diminishing (TVD) scheme. Recipes for building the one-dimensional IMHD code, including the normalized right and left eigenvectors of the IMHD Jacobian matrix, are presented. Then, we have extended the one-dimensional code to a multi-dimensional IMHD code through a Strang-type dimensional splitting. In the multi-dimensional code, an explicit cleaning step has been included to eliminate non-zero $\nabla\cdot B$ at every time step. To estimate the proformance of the code, one- and two-dimensional IMHD shock tube tests, and the decay test of a two-dimensional Alfv\'{e}n wave have been done. As an example of astrophysical applications, we have simulated the nonlinear evolution of the two-dimensional Parker instability under a uniform gravity.Comment: Accepted for publication in ApJ, using aaspp4.sty, 22 text pages with 10 figure

Studies on Hypoxia: XI. Long-Term Effects on the Epiphyseal Plate—A Histomeric and Radioautographic Study

Rats were exposed to hypoxia for one week. The mean thickness of epiphyseal plates from control rats was 430 micrometers (μm) which was reduced to 313 μm in hypoxic rats. Radioautographic incorporation of 3H-phenylalanine by connective tissue cells in hypoxic rats was reduced up to 38% in control rats.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66916/2/10.1177_00220345760550031301.pd

Massive torsion modes, chiral gravity, and the Adler-Bell-Jackiw anomaly

Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-transverse vacuum polarization tensors, and become massive as a result. The underlying reasons are similar to those responsible for the Adler-Bell-Jackiw (ABJ) and scaling anomalies. Since these are the only torsion components that can couple minimally to spin 1/2 particles, the anomalous generation of masses for these modes, naturally of the order of the regulator scale, may help to explain why torsion and its associated effects, including CPT violation in chiral gravity, have so far escaped detection. As a simpler manifestation of the reasons underpinning the ABJ anomaly than triangle diagrams, the vacuum polarization demonstration is also pedagogically useful. In addition it is shown that the teleparallel limit of a Weyl fermion theory coupled only to the left-handed spin connection leads to a counter term which is the Samuel-Jacobson-Smolin action of chiral gravity in four dimensions.Comment: 7 pages, RevTeX fil