广义脉冲谱方法的一个新形式及其应用

构造了一种新的、有一定抗噪能力的广义脉冲谱方法(GPST)的计算格式。设计了选取正则参数过程中节省计算量的技巧.最后探讨了方法在地震勘探一维波方程反问题上的应用,进行了数值模拟。     

Multiple periodic solutions for a nonlinear suspension bridge equation

We investigate nonlinear oscillations in a fourth-order partialdifferential equation which models a suspension bridge. Previouswork establishes multiple periodic solutions when a parameterexceeds a certain eigenvalue. In this paper, we use Leray-Schauderdegree theory to prove that if the parameter is increased further,beyond a second eigenvalue, then additional solutions are created.     

Combined application of surface flow visualization and laser-Doppler anemometry to engine intake flows

Flow visualization using oil streak techniques and laser-Doppler anemometry were carried out to provide detailed information on the flow through the intake valve of a research (model) engine head under steady flow conditions. The work was partially undertaken to develop the techniques as useful tools for engine research. On the other hand, variations of the flow field with valve lift and with valve location were of interest. In the present paper it is shown that a symmetric geometry does not necessarily result in symmetric flow patterns inside the cylinder; the tendency to asymmetry increases with increasing valve lift. These characteristics of the flow should be taken into account when flow computations are performed necessitating the use of three dimensional codes in the entire flow field, not in a symmetrical half-geometry.     

Crystallite growth in magnesium oxide under applied electric fields

An electrolysis cell is described for use in conjunction with a high-temperature X-ray furnace, which permits X-ray diffraction studies to be made of solids during the course of their high temperature electrolysis. The technique is applied to an investigation of the effect of electric fields on crystallite growth in MgO at 600°C in air, argon and reducing atmospheres. In all cases crystallite growth is greatest at the positive electrode face, suggesting that the charge carriers are anions. The efficiency of the electrolysis process depends both on the concentration of charge carriers and on the concentration of anion vacancies by which the charge carriers migrate. The defect concentration is increased under reducing conditions. In MgO samples containing a high concentration of protons, the conduction is protonic, with the greatest crystallite growth occurring at the cathode due to the catalytic action of the water vapour formed in that region by recombination of protons with hydroxyl ions.     

Experiments with longitudinally polarized electrons in a storage ring using a siberian snake

We report on first measurements with polarized electrons stored in a medium-energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interaction point and polarization lifetime of the stored electrons were determined with laser backscattering. Spin observables were measured for electrodisintegration of polarized 3He, with simultaneous detection of scattered electrons, protons, neutrons, deuterons, and 3He nuclei, over a large phase space.     

DNA vaccine containing the mycobacterial hsp65 gene prevented insulitis in MLD-STZ diabetes

Background  

Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases.     

Enantioselective syntheses of trans-3,4-difluoropyrrolidines and investigation of their applications in catalytic asymmetric synthesis

[reaction: see text] Asymmetric syntheses of enantiopure trans-3,4-difluoropyrrolidines have been prepared by the introduction of fluorine at both centers in a single operation; asymmetric epoxidations and additions to benzaldehyde were conducted using catalysts whose chirality depends on organofluorine asymmetry.     

Three-dimensional morphological characterization of optic nerve fibers by atomic force microscopy and by scanning electron microscopy.

A comparative study of scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging of the healthy human optic nerve was carried out to determine the similarities and the differences. In this study we compared the fine optic nerve structures as observed by SEM and AFM. The fibers of the right optic nerve of a 61-year-old man show different arrangements in transverse sections taken from the same individual 5 mm central to the optic canal and 5 mm peripheral to the optic chiasma; this difference can be recognized by light microscopy (LM), SEM, and AFM. AFM revealed such typical optic nerve fibers (taken from a point 5 mm central to the optic canal) with annular and longitudinal orientations, which were not visible by SEM in this form. By contrast, LM and SEM visualized other structures, such as pia mater and optic nerve fibers loosely arranged in bundles, none of which was visualized by AFM. The images, however, taken 5 mm peripheral from the optic chiasma show shapeless nerve fibers having a wavy course. Our results reveal that more detailed information on optic nerve morphology is obtained by exploiting the advantages of both SEM and AFM. These are the first SEM and AFM images of healthy human optic nerve fibers, containing clear representations of the three dimensions of the optic nerve.