[en] This work is an attempt to concentrate on the thermodynamic theory, the engineering solution and the quantities of water needed for the operation of a wet as well as a wet/dry cooling towers coupled to a nuclear turbine condenser,. About two hundred variables are needed for the design of a condenser - cooling tower system. In order to make the solution fast and handy, a computer model was developed. The amount of water evaporation from cooling towers is a function of the climate conditions prevailing around the site. To achieve an authentic analysis, the meteorological data of the northern Negev was used. The total amount of water necessary to add to the system in a year time of operation is large and is a function of both the blow-down rate and the evaporation. First estimations show that the use of a combined system, wet/dry cooling tower, is beneficial in the northern Negev area. Such a system can reduce significantly the amount of wasted fresh water. Lack of international experience is the major problem in the acceptability of wet/dry cooling towers. The technology of a wet cooling tower using sea water is also discussed where no technical or engineering limitations were found. This work is an attempt to give some handy tools for making the choice of cooling systems for nuclear power plants easier

[en] The N-Body plasma simulation consists in calculating the Coulomb interaction between N charged particles. We adapted an N-Body 'tree code' algorithm, successfully used in the gravitational case, for the simulation of plasma. So far, we have found two main applications which suits this technique particularly well. First, the expansion of a plasma into vacuum. In this kind of simulations, densities of very different order of magnitude have to interact. Some areas can have an hydrodynamic behavior whereas some others are filled by energetic particles following ballistic trajectories. Problems which take into account plasma-vacuum interface are almost impossible to study with common simulation techniques ( Vlasov, Fokker-Planck). The other application consists in simulating moderately or strongly coupled plasma. It deals with many laboratory plasmas as well as astrophysical plasmas such as the convective zone of the sun. In coupled plasmas, close collisions between charges can not be neglected as it is done in most of the other simulation techniques. The N-Body technique allows the accurate description of the trajectory of each single particle and thus to take into account the strong deviations due to the close collisions. (author)

[en] Using a three-dimensional global model with a height of 0-80 km, which is based on the primitive equations in flux form, a numeric sensitivity study is carried out in order to determine the role of the troposphere as lower boundary condition in the simulation of stratospheric heat-up. The tropospheric grid surfaces are left out of account in order to achieve a troposphere-less model version which is then used for simulation of stratosphere heat-up at its lower edge near the tropopause. All boundary values are based on geopotential values which were first determined in a model version comprising the troposphere. (orig./KW)

No abstract available

[en] The principle of the modular design of the beam lines is presented. Their operation and tuning mode are further explained. The GANIL beam lines, which were designed on this basis about 1975, are quoted as an example

No abstract available

[en] By chance, eight X-ray plates dating from 1899 were found in 1986. Each of these glass plates shows the patient's name and the date of the examinations, which were performed in Vienna by Prof. Franz Exner, who was a friend of W.C. Roentgen. The glass plates are 25x13 cm and 10x18 cm in area and 3 mm thick. One side is coated with silver bromide. Probably these are some of the earliest X-ray records in the history of radiology. Their quality is comparable with the quality that can be achieved today, even though the materials and the imaging method used were somewhat unsophisticated. (orig.)

[en] In dogs and 11 patients a new endoscopic method for arteries has been developed. The approach is transfemoral, and endoscopy is combined with angiography, percutaneous transluminal angioplasty (PTA), and local lysis. An ultrathin endoscope with a diameter of 2.4 mm is used, which also provides a working channel with a diameter of 0.4 mm. Guide wires, contrast media, and drugs for local lysis can be inserted through this channel. Under fluoroscopic control, the endoscope is placed in the region of interest, followed by a special method for decreasing blood flow. Endoscopy is documented by video or by a high-speed camera. No complications have occurred. In all patients, it was possible to demonstrate the results of dilatation, recanalization, or local lysis before and after the interventional procedure. (orig.)

No abstract available

[en] Drosophila melanogaster males carrying a ring-X-chromosome were X-rayed and crossed to virgin females of 7 stocks, which had their second and third chromosomes systematically substituted. In the same experiment dominant lethals, sex-chromosome losses, and reciprocal translocations were recorded. Maternal effects on mutation fixation were observable as differences in the mutation frequencies observed with the different types of females. With the set of substitution stocks studied it was found that the maternal genotype strongly influences the frequencies of chromosome losses. The influence on classical chromosome-breakage phenomena, such as dominant lethals and translocations, however, are weak. The differences in the chromosome-loss frequencies may result either from different time intervals between insemination and the beginning of chromosome replication, and/or the efficiency of a repair system. One or more strong genetic factors reponsible for such modifications could be located on the third chromosome. On the second chromosome, at best only weak factors are present. (Auth.)