[en] Weak gravitational lensing provides a unique method to map directly the distribution of dark matter in the universe. Several methods are generally used to derive the lensing shear from the shapes of background galaxies, but the shear map obtained is always noisy. In this report we have tested different methods of de-noising: the Gaussian filter, the Wiener filter and the multi-scale entropy method (MEM). We notice that the Wiener filter with an additional soft threshold is the one that gives the filtered mass map nearest to the real mass map according to the standard deviation estimator. The Gaussian filter is the one that gives the coarsest result: the main peaks are found but the edges remain vague. The Wiener filter gives good results in the Fourier space but is better when applied in the wavelet space. We can say that the MEM is the best method we have tested as it enables us to detect all the main structures of the mass map without doing too many false detections. (A.C.)

[en] We present the results of two observations of the bright Seyfert 1 galaxy NGC 3516, obtained with BeppoSAX in 1996 November and 1997 March. Useful signal is detected between 0.2 and 60 keV, allowing for the first time the simultaneous observation of all main spectral features. The source was brighter by a factor 2 at the second epoch of observation. Both spectra present a strong Fe Kα line, and a reflection hump at high energy. An absorption edge at 0.8 keV is visible in the later spectrum, but not in the earlier one, indicating that this feature is strongly variable

[en] The United States Department of Energy (DOE) conducts through its operating contractors major nuclear research, development, and production operations at nearly 30 installations. Emission and environmental monitoring programmes conducted at these sites are intended to ensure effective effluent controls and compliance with applicable radiation standards. Radionuclide emissions from DOE facilities are reported annually to a central computer-based effluent information system. This system enables DOE management to identify emission sources and observe trends in emission levels. Emissions to the environment from all DOE installations in 1981 totalled 1.9 million curies, predominantly short-lived activity, noble gases, and tritium. Significant trends in emissions and population exposures resulting from the emissions are discussed. Each DOE installation prepares an annual environmental monitoring report summarizing radionuclide emissions and computed radiation dose to the public within an 80 km radius. Actual measurements of radioactivity in human exposure pathways are used whenever possible to calculate dose to the public. Often it is necessary to calculate doses using effluent and meteorological data and appropriate dispersion equations. Calculations include the maximum individual dose and the 80 km population dose. Assessments of population dose at DOE installations in 1981 indicate that offsite exposure of the maximum individual did not exceed 10% of the 500 mrem limit at any site, and generally was less than 1% at most sites. For 1981, the calculated population whole-body dose within an 80 km radius of individual DOE sites ranged up to 120 man.rem and totalled about 230 man.rem. Calculated population doses from DOE operations are discussed, including radionuclide-specific contributions to public doses and year to year trends. A brief review is included of the DOE reporting systems for effluent releases and environmental doses. (author)

No abstract available

[en] Female Swiss albino mice were exposed at 1, 3 or 6 weeks of age respectively to sublethal doses (0.6, 1.2 and 2.4 Gy) of gamma radiation in the presence or absence of 2-mercaptopropionylglycine (MPG). Ovaries were histologically examined at different intervals after irradiation and the follicles were counted. Most follicular depletion had occurred already at postirradiation day 1 and the depletion then gradually continued. At day 35 after irradiation a few follicles could still be found in mice exposed at 1 week of age while all follicles were eliminated in mice exposed at 3 and 6 weeks of age. In MPG-treated animals the depletion of follicles was significantly less pronounced and obviously MPG to some degree protected the ovaries from radiation damage. (orig.)

No abstract available

[en] We present a statistical analysis of the Chandra observation of the source field around the 3C 295 galaxy cluster (z=0.46). The logN-logS of this field is in good agreement with that computed for the Chandra Deep Field South in this work and in previous ones. Nevertheless, the logN-logS computed separately for the four ACIS-I chips reveals that there is a significant excess of sources to the North-North East and a void to the South of the central cluster. Such an asymmetric distribution is confirmed by the two-dimensional Kolmogorov-Smirnov test, which excludes (P∼3%) a uniform distribution. In addition, a strong spatial correlation emerges from the study of the angular correlation function of the field: the angular correlation function is above that expected for X-ray sources on a few arcmin scales. In synthesis, the present analysis may indicate a filament of the large scale structure of the Universe toward 3C 295. This kind of study may open-up a new way to map (with high efficiency) high-density peaks of large scale structures at high redshift

[en] Interactions of 5 GeV p-bar with light nuclei in emulsion have been investigated here. The features studied are multiplicity, pseudo-rapidity and azimuthal angle distributions of the secondary particles. The results have been compared with p-nucleus interactions

[en] The preparation and properties of dysprosium and holmium derivatives of mono-, di- and tri-ethanolamine derivatives are described. Compounds of general formulae: Ln(OPrsup(i))₂(mea), Ln(OPrsup(i))(mea)₂, Ln(mea)₃, Ln(OPrsup(i))(dea), Ln₂(dea)₃, Ln(dea)(deaH) and Ln(tea) (where Ln = Dy or Ho and mea, dea and tea are the anions of respective ethanolamine) were obtained and characterized by elemental analysis and IR spectra. (author)

[en] Six week old male Swiss albino mice taken from an inbred colony were irradiated with 0.6 and 1.2 Gy of low ⁶⁰Co gamma rays in the presence and absence of MPG. Results indicated the infliction of radiation insult and subsequent repair in the testes to be dose dependent, that is higher the dose greater the damage and sluggish the reparative activity. A greater number of suviving germ cells in the experimental tests with fewer dead cells reflected the protective efficiency of the drug against radiation damage to the cell population. Thus MPG not only protects against radiation-induced cell death and depletion but also chances the mitotic rate of the stem cells by which an accelerated recovery was brought about. (author)