Search

Electron microscopy is advanced to attosecond resolution by modulating the beam with the field cycles of a continuous-wave laser., Electron microscopy can visualize the structure of complex materials with atomic and subatomic resolution, but investigations of reaction dynamics and light-matter interaction call for time resolution as well, ideally on a level below the oscillation period of light. Here, we report the use of the optical cycles of a continuous-wave laser to bunch the electron beam inside a transmission electron microscope into electron pulses that are shorter than half a cycle of light. The pulses arrive at the target at almost the full average brightness of the electron source and in synchrony to the optical cycles, providing attosecond time resolution of spectroscopic features. The necessary modifications are simple and can turn almost any electron microscope into an attosecond instrument that may be useful for visualizing the inner workings of light-matter interaction on the basis of the atoms and the cycles of light.

Kinesthesia as a process of transmission of sensation in the joints postulates the existence of receptors for different types of stimuli and apropriate pathways. These are described as briefly as possible, and attention is drawn also to multipolar ganglion cells at the outside of the ligamenta cruciata of human knee joints. Their possible functional importance is the subject of a hypothetic discussion assuming that they may represent the "switchboards" for regulating both quantity and quality of the synovia.

Summary Gastrin- and somatostatin-immunoreactive cells in biopsies taken from the prepyloric portion of the antrum from 15 patients with duodenal ulcer, 16 patients with gastric ulcer, and a control group of 19 patients without histopathological alterations of the antral mucosa were studied using peroxidase anti-peroxidase and immunogold-silver staining methods in combination with morphometry. Numerical densities and sizes (immunoreactive areas) of the cells demonstrated were measured and compared between all three groups. Gastrin- and somatostatin-immunoreactive cells were located most frequently in the lower midzone of the gastric crypts. None of the parameters measured showed a correlation with age or sex. The group with duodenal ulcer tended to exhibit gastrin- and somatostatin-cell-hyperplasia whereas the size of both cell types remained unchanged. In comparison with the control group, the numerical density of gastrin-immunoreactive cells was significantly increased in gastric ulcer patients, whereas the numerical density of somatostatin-immunoreactive cells was decreased in this group. Immunoreactive areas of both cell types were significantly increased in patients with gastric ulcer.