Elastic scattering of 6.8-Mev protons on even-Z Ni, Cr, and Zn and odd-Z Co and Cu was investigated. An abnormal phenomenon was observed with Ni. Proton scattering is almost identical at 5.25 and 7.5 Mev, but the ratio of the differential scattering cross section to the differential Coulomb scattering cross section sigma /sub e/( THETA )/ sigma /sub R/ ( theta 0 differs considerably at large angles. The magnitude sigma /sub e/( theta ) / sigma /sub R/( theta ) for nuclei with even Z is larger than for nuclei with odd Z. (R.V.J.)
Abstract Axisymmetric free vibration of moderately thick polar orthotropic hemispherical shells are studied under the various boundary conditions of sliding, guided pin, clamped and hinged edges. Based on the improved linear elastic shell theory with the transverse shear strain and rotatory inertia taken into account, the dynamic equilibrium equations are formulated and transformed into the displacement form in terms of mid-surface meridian and radial displacements and parallel circle cross-section rotation. These partial differential equations are solved by the Galerkin method using proper Legendre polynomials as admissible displacement functions with the aid of the orthogonality and a number of special integral relations. Numerical results of the present theory compare well with existing data, which is available only in the isotropic theories. Good convergence is obtained for natural frequencies and mode shapes. Study of the effects of thickness and modulus ratio reveals higher frequencies for the thicker and/or stiffer shells with E\ oriented parallel to the meridians. Ranking of the natural frequencies descends in the order of guided pins, sliding, clamped and hinged edges in general. Also seen are the effects of transverse shear strain from the mode shapes with clamped and sliding edges on the slant. For the guided pin and sliding edges, frequencies increase fast as thickness increases so that new fundamental modes are generated in filling up the “frequency gap”. These are the new discoveries in the field of anisotropic shells, as a result of polar orthotropy of shell material and construction.
Summary Astrocytes play important roles in the central nervous system (CNS) physiology and pathology. Indeed, astrocyte subsets defined by specific transcriptional activation states contribute to the pathology of neurologic diseases, including multiple sclerosis (MS) and its pre-clinical model experimental autoimmune encephalomyelitis (EAE) 1–8 . However, little is known about the stability of these disease-associated astrocyte subsets, their regulation, and whether they integrate past stimulation events to respond to subsequent challenges. Here, we describe the identification of an epigenetically controlled memory astrocyte subset which exhibits exacerbated pro-inflammatory responses upon re-challenge. Specifically, using a combination of single-cell RNA sequencing (scRNA-seq), assay for transposase-accessible chromatin with sequencing (ATAC–seq), chromatin immunoprecipitation with sequencing (ChIP–seq), focused interrogation of cells by nucleic acid detection and sequencing (FIND-seq), and cell-specific in vivo CRISPR/Cas9-based genetic perturbation studies we established that astrocyte memory is controlled by the metabolic enzyme ATP citrate lyase (ACLY), which produces acetyl coenzyme A (acetyl-CoA) used by the histone acetyltransferase p300 to control chromatin accessibility. ACLY + p300 + memory astrocytes are increased in acute and chronic EAE models; the genetic targeting of ACLY + p300 + astrocytes using CRISPR/Cas9 ameliorated EAE. We also detected responses consistent with a pro-inflammatory memory phenotype in human astrocytes in vitro ; scRNA-seq and immunohistochemistry studies detected increased ACLY + p300 + astrocytes in chronic MS lesions. In summary, these studies define an epigenetically controlled memory astrocyte subset that promotes CNS pathology in EAE and, potentially, MS. These findings may guide novel therapeutic approaches for MS and other neurologic diseases.
Finite/Spectral Element Navier-Stokes Methods on Vector Hypercubes and Geometry-Defining Processor Recoufigurable Lattices.- A Comparative Study of TVB, TVD and ENO Schemes for the Euler Equations.- An Improved Upwind Scheme for the Euler Equations.- Front Tracking and The Interaction of Nonlinear Hyperbolic Waves.- Computational Test of the Renormalizatiou Group Theory of Turbulence.- Energy and Dissipation Range Spectra in the Range of Homogeneous Turbulence.- A Unified Pressure Correction Algorithm for Computing Complex Fluid Flows.- The Finite Element Method in Viscous Incompressible Flows.- Computations of Taylor Vortex Flows Using Multigrid Continuation Methods.- A Variational Finite Element Method for Compressible Navier-Stokes Flows.- Supercomputiug and the Finite Element Approximation of the Navier-Stokes Equations for Incompressible Viscous Fluids.- Recent Progress on Essentially Non-Oscillatory Shock Capturing Schemes.- Large-Eddy Simulations of Flows in a Ramjet Combustor.- Aerodynamic Design Via Control Theory.- The Application of Multiple One-Dimensional Adaptive Grid Method.- Numerical Solutions for Unsteady Aerofoil by Internal Singularity Method.- The Vertical Motion of Atmosphere Computed and Adjusted by Variational Method.- Study of Unsteady Flow in the Heat Exchanger by the Method of Characteristics.- Penalty Finite Element Applications to Flow Problems.- Resolution Requirements for Numerical Simulations of Transition.- Computation of Flow Past 3-D Hills.
The elastic scattering of 100 MeV protons from 14 N has been studied and results were analyzed by the optical model. The optical potential parameters obtained were compared to those from the same reaction at different bombarding energies and also to those obtained from elastic scattering data of 100 MeV protons from other 1p shell nuclei.
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