Перспективи мінімізації латентності оперативної пам’яті

Basic progress of technologies of main memory trends are analyzed. The features of the modules of memory of DDR3 are considered in relation to the increase of carrying capacity due to minimization of delays

Distribution of chromosome 18 and X centric heterochromatin in the interphase nucleus of cultured human cells

In situ hybridization of human chromosome 18 and X-specific alphoid DNA-probes was performed in combination with three dimensional (3D) and two dimensional (2D) image analysis to study the interphase distribution of the centric heterochromatin (18c and Xc) of these chromosomes in cultured human cells. 3D analyses of 18c targets using confocal laser scanning microscopy indicated a nonrandom disposition in 73 amniotic fluid cell nuclei. The shape of these nuclei resembled rather flat cylinders or ellipsoids targets were preferentially arranged in a domain around the nuclear center, but close to or associated with the nuclear envelope. Within this domain, however, positionings of the two targets occurred independently from each other, i.e., the two targets were observed with similar frequencies at the same (upper or lower) side of the nuclear envelope as those on opposite sides. This result strongly argues against any permanent homologous association of 18c. A 2D analytical approach was used for the rapid evaluation of 18c positions in over 4000 interphase nuclei from normal male and female individuals, as well as individuals with trisomy 18 and Bloom's syndrome. In addition to epithelially derived amniotic fluid cells, investigated cell types included in vitro cultivated fibroblastoid cells established from fetal lung tissue and skin-derived fibroblasts. In agreement with the above 3D observations 18c targets were found significantly closer (P < 0.01) to the center of the 2D nuclear image (CNI) and to each other in all these cultures compared to a random distribution derived from corresponding ellipsoid or cylinder model nuclei. For comparison, a chromosome X-specific alphoid DNA probe was used to investigate the 2D distribution of chromosome X centric heterochromatin in the same cell types. Two dimensional Xc-Xc and Xc-CNI distances fit a random distribution in diploid normal and Bloom's syndrome nuclei, as well as in nuclei with trisomy X. The different distributions of 18c and Xc targets were confirmed by the simultaneous staining of these targets in different colors within individual nuclei using a double in situ hybridization approach

Phase fluorometric method for determination of standard lifetimes

Rayleigh scatterers have long been used as standards for fluorescence lifetime determinations, but they have many drawbacks, including the well-known “color effect ’. To avoid these problems, various fiuorophores have been used as standards. Unfortunately, the lifetimes of these compounds are not agreed upon to better than 5%, and the compounds cited in the literature do not fully cover the 250–850 nm band of common fluorescence emission. We describe a multifrequency phase fluorometric method for accurately determining the lifetimes of monoexponential fluorophores (standards) without reference to another standard. Results are shown for some widely used standard fluorophores and some recently developed compounds. An Independent test of the accuracy of the method based on quenching experiments is presented. © 1988, American Chemical Society. All rights reserved

Determining the need for vocational counselling among different target groups of young people under 28 years of age in the european community : vocational guidance needs of homeless young people in the Netherlands : young drifters : national report /

Bibliogr.: p. 41-4