Ion implantation in gallium arsenide MESFET technology

The authors emphasize controlled shallow doping of GaAs by ion implantation and its limitations to state-of-the-art GaAs IC technology. The authors discuss the electrical activation behavior of implanted silicon in GaAs upon subsequent capless or silicon nitride capped rapid thermal annealing (RTA). It is demonstrated that atomic H diffuses into the implanted region of GaAs from a plasma-enhanced chemical vapor deposition Si₃N₄ cap during the deposition as well as during subsequent annealing, and the H retards the electrical activation kinetics of the implanted Si. Thru-Si cap dopant implants into GaAs have been studied to enhance dopant concentration in the surface region of the GaAs by recoil-implanted Si from the cap. Application of ion implantation to achieve buried-p layers in GaAs is also briefly discussed     

Modulation of adrenal gap junction expression

To increase our knowledge of the role of peptide hormone stimulation in gap junction protein expression and adrenal cortical cell function, primary rat adrenal cortical cells were treated with adrenocorticotropin, and gap junction proteins were measured. Immunocytochemistry and western blot analysis were used to detect and characterize gap junction type and distribution. The gap junction protein, connexin 43 (alpha 1), was detected. Analysis of six connexin protein types did not reveal gap junction species other than alpha 1. Cells of the inner adrenal cortical zones, zonae fasciculata and reticularis, were demonstrated to have the highest number of gap junctions per cell in the adrenal gland. Adrenal cell cultures enriched for the two inner cortical adrenal zones were established and demonstrated also to express alpha 1 gap junction protein. Adrenocorticotropin (40 mUnits/ml) and dibutyryl cyclic adenosine monophosphate (1 mM) treatments increased alpha 1 gap junction protein levels and decreased cell proliferation rates in the cell cultures. The results are consistent with the hypothesis that gap junction expression can be regulated by adrenocorticotropin acting through the second messenger cyclic adenosine monophosphate. It can be suggested that gap junction expression in the adrenal gland may be under hormonal influence, and that gap junctions serve as passage for movement of molecules involved in control of cell proliferation.     

Are preventive measures against suicide efficient? A literature review

The increasing frequency of suicide in Norway from 1970 to 1990 has called attention. This paper raises the question of whether any controlled studies have been conducted on prevention of suicide. A search was made in Medline; the criteria for including articles were: controlled studies concerning the effects of suicide-preventive intervention by measuring the number of suicides, parasuicides or suicidal thoughts/ideation. The result of our search was 13 randomised controlled trials and two case-control studies. Most of the studies were unable to confirm any effect of suicide-preventive intervention. In most studies the experiment and control groups were far too small to arrive at significant conclusions. Prior to starting prevention programmes, it is necessary for the health service to know the potential effects. This systematic review revealed that few good controlled studies have been conducted on suicide prevention. For the time being we have to accept the suggestive evidence for certain types of intervention, and use these as a basis for action.     

Biochemical effects of retinoic acid on GTP-binding Protein/Transglutaminases in HeLa cells. Stimulation of GTP-binding and transglutaminase activity, membrane association, and phosphatidylinositol lipid turnover

Treatment of HeLa cells with retinoic acid (RA) gives rise to a marked stimulation in the incorporation of [alpha-32P]GTP into an approximately 87-kDa cytosolic protein that cross-reacts with a monoclonal antibody raised against tissue transglutaminases. In the absence of RA treatment, the transglutaminase immunoreactivity elutes from a gel filtration column with an apparent size of approximately 600 kDa (designated TGa), whereas following RA treatment, a second peak of transglutaminase immunoreactivity (designated TGb) is detected with an apparent size of approximately 150 kDa. The TGa fractions show little or no GTP-binding or GTP hydrolytic activity and very little transglutaminase activity. However, the TGb fractions show all three activities. Retinoic acid treatment also promotes the association of the GTP-binding protein/transglutaminase with membrane fractions, as detected by Western blotting and photoaffinity cross-linking with [alpha-32P]GTP. In addition, the TGb fraction shows a markedly enhanced ability (relative to TGa) to associate with membranes from control (non-RA-treated) cells. The ability of the GTP-binding protein/transglutaminase to bind to membranes is correlated with the stimulation of a membrane-associated phospholipase C activity. Thus, these findings indicate that RA treatment results in a number of changes in the biochemical properties of a GTP-binding protein/transglutaminase which strongly enhance its ability to bind GTP, associate with plasma membranes, and stimulate phosphoinositide lipid turnover.     

SEMANTICS OF COMPLEX STRUCTURAL SYSTEMS—PRESENTATION AND REPRESENTATION: A SYNCHRONIC VISION OF LANGUAGE L( M T )

Abstract

In this paper, the authors continue developing a Linguistic Theory of the Complex Structural Models, but in terms of the Semantics. Each symbol (transformed function) is syntactically a lexeme, carrying associate a sememe or atomic semantic unit. Each sememe can be decomposed in semes or quantic semantic unities. They are studied the semantic systems, associated with the syntactic, and that serve them as suprastruc-ture, in terms of two levels: the quantic and the atomic. Also, it is demonstrated that for all model of the complex reality, will exist always a most complex model from the syntactic and semantic point of view.     

全球“画”

<正>每一年我都要为许多在美国申请研究学位的学生评估他们的作品集。这些学生来自世界不同地方。不管这种现象是否普遍,我还是要说这些学生的作品看起来竟然会是如此惊人的相似。大部分的学生作品呈现出来相同的画图技术,这些技术描述了相同的景观类型,并且使用了相同的人物形象。欢迎来到全球"画"。对这种画图表现方式一致性的担心主要体现在两个方面。第一是学生们缺乏对当代景观美学批判的能力,第二是缺乏独创性和个性。整体上看来,几乎所有申请作品都在表