Distinction between artefactually shrunken and truly degenerated 'dark' neurons by in situ fixation with microwave irradiation

Dark, shrunken neurons frequently occur as artefacts in immersion fixed tissue. Perfusion fixation will prevent artefacts of this type. However, morphologically identical neurons have been described as truly degenerated cells in perfusion fixed brains in various pathological conditions. Since adequate perfusion is difficult to obtain in some pathological conditions, the question still remains whether the dark neurons found in some of these situations are true in vivo phenomena or artefacts caused by inadequate fixation. In the present study rat brains with cryogenic lesions were fixed in situ by microwave irradiation. With this method no artefactually changed dark neurons were observed in the normal parts of the brains. In the cryogenic lesions, however, a narrow rim of dark, shrunken neurons occurred adjacent to the normal cortex. This zone was identical to that observed in perfusion fixed tissue. Since inadequate fixation due to uneven perfusion of the damaged tissue is prevented with this method, we suggest that the neuronal changes represent true in vivo phenomena. Fixation with microwave irradiation can thus be used to differentiate between artefactually changed and truly degenerated dark neurons in various pathological conditions.     

A circular reflector interferometer for the far infrared

The construction of a Fourier transform spectrometer to study magnetic resonances in solids is described. The spectrometer operates in the Far Infrared (maximum frequency of 500 cm^?1) and is based on a wavefront dividing interferometer with circular geometry. To illustrate the performance, a water vapour spectrum is given.     

Development of a heart monitoring system with high-Tc DC-SQUID gradiometers

We investigated different types of high-T_c DC-SQUID gradiometers with the aim to develop an one-channel heart monitoring system for non-invasive measurements in unshielded environment. This system could be used to obtain information about the patients condition in serial examinations and in emergency cases fast and stable. Step-edge and bicrystal Josephson junctions were used to prepare planar galvanically coupled thin film gradiometers and magnetometers. These sensors were used to carry out measurements in well-shielded and non-shielded environment and we compared the different noise properties and field gradient resolutions. With different types and sizes of high-T_c DC-SQUID sensors magnetocardiograms were measured in a magnetically shielded room. The influence of antenna configurations, SQUID parameters, and cooling conditions on the measurement of magnetocardiograms will be discussed. We investigated possibilities to suppress the earth magnetic field (with pairs of Helmholtz coils) and for noise field compensation in unshielded environment.     

Psychometric considerations in the dimensional analysis of subjective picture quality

A discussion of the factors involved in the subjective perception of television picture quality is presented. Much of the work in this field is cited, and it is concluded that future work needs to consider a broader range of variables than has been looked at so far.     

Vergleich der Extrakte und des Lignins aus frischem und gelagertem Kiefernholz (Pinus sylvestris L.)

The degradation processes of the extractives of pine wood caused by aging are only noticeable in the heartwood. In seasoned sapwood the percentages of the water extracts and the cyclohexane-ethanol extract increase compared with the green sample; the alkali extracts, however, do not vary. The contents of acid lignin as well as the UV and IR spectra of MWL do not show differences. The amount of OCH₃/C₉ is in all samples 0.96, but the degree of oxidation is higher in the seasoned wood than in the green one.     

Computer-aided design in mechanisms

The man-machine dialog is very important for the design process. In this paper a program system, based on the minicomputer KRS 4201 (ROBOTRON), is demonstrated by using an interactive graphical screen. This program system provides the opportunity to analyze and synthesize mechanisms up to 16 links. The application is demonstrated by designing a front-loader-system for a truck. Real-time animation of seven-bar linkages and coupler curves, including velocity and acceleration, are shown.     

Formation of droplets on Si surfaces bombarded by In from a capillary type liquid metal ion source

Droplet formation on Si surfaces bombarded by 10 keV beams from a liquid metal indium ion source has been observed. It has been verified that excess indium is transported in the ion beam, probably in the form of charged droplets. SIMS, SEM and RBS techniques have been used to study the distribution of droplets at the surface. At the specified ion source operating conditions, equilibrium droplet coverage is of the order of 25%. Individual droplets have an average diameter of 0.35 ωm and an average height of 2.2 nm. At a bombardment current density of 0.1 mA cm^?2, equilibrium coverage is reached in about 1 s.