Do arsenic interstitials really exist in As-rich GaAs?

To investigate the lattice distortion caused by point defects in As-rich GaAs, we make use of a self-consistent-charge density-functional based tight-binding method. Both relevant defects, the As antisite and the As interstitial, cause significant lattice distortion. In contrast to As interstitials, isolated As antisites lead to lattice strain as well as displacement of nearest neighbor As lattice atoms into the <110> channels, in excellent agreement with experiments. Therefore, our result gives powerful evidence for As antisites being the dominating defect in as-grown As-rich GaAs.

Sperm chromosome analysis of a man heterozygous for a pericentric inversion of chromosome 20

The sperm chromosomes of a man heterozygous for inv(20)(p13q11.2) were analyzed. Twenty-six sperm chromosome complements were examined, of which fourteen contained the normal chromosome, and twelve the inverted chromosome. None of the sperm complements contained a recombinant chromosome 20. The frequency of structural chromosomal aberrations unrelated to the inversion was 11.5% (3/26). Numerical aberrations were not observed. The percentages of X- and Y-bearing sperm were 56% and 44%, respectively, which was similar to the expected 1:1 ratio.

[The image of the public health office in the public consciousness of a small city]

130 inhabitants of a small town (12,500 inhabitants) in Baden-Württemberg, Germany, were asked by health office employees about their opinion on the public health office and their knowledge of its tasks. The results of the poll show that there is some knowledge regarding the tasks of the public health office in the population; however, this knowledge is confined to a few points. As a result of the poll, the population has a neutral or rather positive point of view of the public health office. An intensification of the public relations several scopes of duties e.g. the scope of the pollution control, seems necessary to achieve the proper position in the image of the population.

Case of cyclopia with an unbalanced karyotype attributable to a balanced 3/7 translocation

This report presents a case of cyclopia attributable to an unbalanced karyotype in a family with a balanced, reciprocal 3/7 translocation. This case was the fifth recorded in three generations of this family. From this report it is possible that the simultaneous action of partial trisomy 3p and partial monosomy 7q may be one cause of holoprosencephaly.

Correlation between the number of sex chromosomes and the H-Y antigen titer

H-Y antigen was studied serologically on blood cells and cultured fibroblasts of patients with numerical aberrations of the sex chromosomes. As compared with normal males, patients with the karyotypes 48,XXXY and 49,XXXXY have reduced H-Y antigen titers; a tendency toward reduced titers can also be detected in the 47,XXY Klinefelter syndrome. The existence of an intermediary titer was further substantiated by a quantitative absorption test applied to cells with the 49,XXXXY karyotype. It appears that in the presence of one Y chromosome, the H-Y antigen titer decreases with an increasing number of X chromosomes. In contrast, the H-Y antigen titer is increased if, at a given number of X chromosomes, the number of Y chromosomes is increased, as in the 47,XYY male. Consequently, patients with 48,XXYY chromosomes are in the male control range. The findings are interpreted under the hypothesis of a controlling or modifying influence of the sex chromosomes on the titer of H-Y antigen.

The dup(3q) syndrome: report of eight cases and review of the literature

Clinical and cytogenetic examinations were performed on eight unrelated infants with duplication of part of the long arm of chromosome 3. A review of published cases shows a clinical syndrome characterized by statomotoric retardation, shortened life span, and a multiple congenital anomalies (MCA) syndrome of abnormal head configuration, hypertrichosis, hypertelorism, ocular anomalies, anteverted nostrils, long philtrum, maxillary prognathia, down-turned corners of the mouth, highly arched or cleft plate, micrognathia, malformed auricles, short, webbed neck, clinodactyly, simian crease, talipes, and congenital heart disease. The dup(3q) syndrome is a clinically easily recognizable entity.

Cytological and histochemical studies on the mechanism of the selective silver staining of nucleolus organizer regions (NORs)

A new silver staining method is presented (Ag-II staining) providing a rapid and reproducible way to selective silver staining of nucleolus organizer regions (NORs). In comparison with other techniques, such as the Ag-AS method and the Ag-I method, factors influencing silver stainability are discussed. Histochemical studies on the nature of the NOR-specific silver precipitate were performed either by employing various pretreatments or by inhibiting the participation ("blocking") of the various proteins or protein compounds in the staining reaction. The results would seem to indicate that the interactions of silver-ions with the carboxyl groups of acidic proteins which are involved in the rRNA-transcription process are mainly responsible for the selective silver staining of NORs.