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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3127-3133 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: This article describes a novel preionization technique, negative ion assisted preionization (NIAP), in which electrons liberated from a reservoir of negative halide ions by photoionization are used to provide preionization for excimer lasers. The NIAP technique is shown to be capable of greatly reducing the technologically demanding requirements associated with conventional flash preionizers, a factor of particular importance for the high average power laser systems currently under development. The efficiency of the NIAP scheme is described with reference to both experimental measurements of the ion reservoir lifetime, which are found to agree with theoretical models, and to theoretical predictions of the electron liberation efficiency, which are found to differ significantly from some previous treatments. The wide range of possible implementations of the NIAP technique is split into three operational regimes that have quite different characteristics. The benefits of improved preionization control and reduced ionization source intensity requirements are described for each regime. The practical limitations of the technique are discussed, and two experimental demonstrations are presented.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 5242-5245 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: An analysis is made of the possible methods of liberation of electrons from atomic negative halide ions in the context of providing sufficient preionization for discharge-pumped rare-gas-halide excimer lasers. Some previous treatments of collisional detachment are shown to be in error by several orders of magnitude. Ion and electron impact detachment of electrons is found to produce a negligible preionization electron number density. Photodetachment is shown to be the dominant electron liberation mechanism, and to be capable of producing electron densities adequate for preionization of the excimer laser discharge.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 34 (1989), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The increasing exploitation of Atlantic salmon as a food source and sport fish demands a better understanding of salmon genetics and the dynamics of Atlantic salmon populations. Surveys of salmon populations for protein electrophoretic variation reveal that the average heterozygosity in Salmo salar is low and that four gene loci account for more than 95% of the total electrophoretically detectable variation. Populations that have been studied by this means fall into one of three groups: Western Atlantic, Eastern Atlantic or Baltic. However, biochemical genetics involving starch gel electrophoresis cannot be used routinely to identify the continent of origin of an Atlantic salmon, let alone its native river. The mitochondrial genome can be used to identify North American or European salmon with the aid of restriction endonucleases that have six base pair recognition sites. Restriction endonucleases that recognize four base pairs appear to be able to identify salmon from a particular river system. There has been a move from protein variation to mitochondrial DNA variation and this will inevitably lead to more extensive studies on the nuclear genome. Chromosomal studies suggest differences between salmon from Europe and North America but these have been hampered by lack of good banding procedures. Preliminary studies using cloned segments of salmonid genomes suggest that repeated sequences such as the genes for ribosomal RNA will be most useful for identifying specific stocks of Atlantic salmon. The need for continued genetic studies on the Atlantic salmon and the relevance and importance of the results of this research for stock identification, enhancement programmes, aquaculture and basic science are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 189 (1961), S. 581-582 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] In the upper example shown in Fig. 1 the subject is drowsy and snores are indicated. The mode of respiration is thoracic. Following a stimulus, the electroencephalograph shows arousal with a train of slow waves of high voltage. Accompanying this there is a change to abdominal breathing. In the ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 192 (1961), S. 1116-1121 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] RECENT advances in neurophysiological techniques have enabled objective evidence to be readily and reliably obtained during long recordings, and cortical and subcortical electrical events to be examined. Despite this there has been little increase in the understanding of the working of the human ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 191 (1961), S. 200-201 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The minimal clinical signs of petit mal attacks are usually accompanied by the most obvious and dramatic electroencephalographic evidence of surface electrical changes, yet no other evidence of pathology in the nervous system has so far been discovered. The clinical accounts of the condition ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 187 (1960), S. 952-953 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Fig. 1 In the case we are describing, the patient had been hypnotized several times. Suggestions were given to "Allow yourself to go deeper and deeper asleep . . ." with explanations to the effect that the word 'sleep' was here being used in a special sense, because the subject was told that he ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The diel distribution of feeding activity during the spawning season was compared for territorial male and female cunners Tautogolabrus adspersus in Conception Bay, Newfoundland, Canada between June and August, 1978. Territorial males feed significantly less often than females and concentrate their feeding activities in the morning, whereas females feed as frequently in the afternoon as in the morning. Based on the contents of alimentary tracts, territorial males, non-territorial males, and females have different diets. Since these three groups share the same habitat, the observed dietary differences probably reflect differences in their foraging behaviour. The relevance of these findings to the concept of ‘time minimizer’ and ‘energy maximizer’ is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Apoptosis 5 (2000), S. 459-471 
    ISSN: 1573-675X
    Schlagwort(e): airway immunity and inflammation ; Fas death receptor ; T helper type 1 and 2 cells ; TNFR-related molecules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Proliferative expansion of lymphoid cells is required for effective immune responses against invading microorganisms, but after the infection is controlled, the expanded effector cells must be eliminated to prevent non-adaptive accumulation of cells. Higher vertebrates have developed extensive networks of signal transduction pathways to ensure controlled activation and expansion of cells during immune responses and apoptotic deletion of lymphoid cells that are no longer needed at the end of immune responses. Extracellular signals received by cell surface receptors that trigger intracellular signaling cascades are essential elements that control both processes. These signal transduction pathways converge to regulate cell fate at both transcriptional and post-transcriptional levels. Here we review the role of pathways, especially those triggered by TNF receptor-related molecules, that determine the fate of T cells during development and activation. In addition, we introduce the possibility that these same pathways may be abnormally programmed and so lead to immune cell accumulation during inflammatory diseases such as asthma.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 1990-07-01
    Print ISSN: 0027-8424
    Digitale ISSN: 1091-6490
    Thema: Biologie , Medizin , Allgemeine Naturwissenschaft
    Standort Signatur Erwartet Verfügbarkeit
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