Melanocytes and Langerhans Cells in Aged Versus Young Skin Before and After Transplantation onto Nude Mice

Previous studies have demonstrated decreased numbers of melanocytes and Langerhans cells (LC) in aged skin. In the present study, we employed dopa and indirect immunoperoxidase techniques in epidermal sheets to determine the fate of melanocytes and LC of aged versus young donors after skin transplantations onto nude mice. The detection of positive homologous leucocytic antibody reaction of degeneration (HLA-DR) of LC indicates an age-associated reduction in sun-protected thigh skin in aged versus young subjects (263 ± 63 versus 589.25 ± 142.643, p < 0.001). The mean number of LC four weeks after transplanation remained almost constant. Prior to skin engraftment, a decreased number of melanocytes was found in aged versus young epidermis (160.77 ± 51.7 versus 255.83 ± 81.2, respectively, p < 0.05). A significantly increased number of melanocytes was noted four weeks following engraftment in epidermis from aged (307.44 ± 174, p <0.05) and young human donors (402.16 ± l39,p < 0.02). The marked increase in density of dopa-positive melanocytes following engraftment onto nude mice may indicate the existence of circulating factors in nude mice that perhaps both stimulates and enhances proliferation and activity of these cells

A Method of Calculation of the Critical Energy for Direct Initiation of Unconfined Detonation

The article of record as published may be found at http://dx.doi.org/10.1080/00102208308923616A simple method is developed which allows the calculation of the minimum energy of direct initiation of unconfined detonations with cylindrical and spherical symmetry. The method uses the detonability limit data for planar detonations, and the data on reaction zone length for computation of the critical energy of initiation. The results are verified by comparison with available experimental data and by numerical simulation of the full governing equations

Development and evaluation of a numerical solution of the Euler equations using the Godunov method

A computer program developed to solve Euler Equations was applied to a variety of test cases, including turboraachinery cascades and analytical solutions for subsonic and transonic flow. With attention to boundary conditions and grid configuration, it was found the code had a robust capability to analyze unsteady, time dependent flow fields and shock patterns.The work reported herein was carried out for the Naval Postgraduate School by Exotech, Inc. under contract N00014-84-C-0677. The work was part of the Air-breathing Propulsion Research Program carried out at the Turbopropulsion Laboratory under the sponsorship of Naval Air Systems Command under the cognizance of G. Derderian (AIR310E).http://archive.org/details/developmentevalu00eideN0001984WR 41099N

Static and dynamic impulses generated by two‐phase detonations

The influence of the mixture density and the reaction zone length on the static and dynamic impulse of the detonations through wheat dust, RDX dust, and decane droplet air mixtures was studied. A numerical solution of the detailed model of the two‐phase detonation initiation and development in the medium, provided the basis for the study. Mixtures with a higher average density were found to produce a significantly greater static impulse, but a reduced dynamic impulse. The reasons for this behavior were discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70853/2/PFLDAS-25-1-38-1.pd