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  • 1
    Electronic Resource
    Electronic Resource
    High resolution observations of pellet emission on TFTR (abstract)a) : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 841-841 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High resolution, rapidly sampled measurements of the light emission from injected impurity pellets have recently been carried out on TFTR. Both wide and narrow views of the pellet light have been accomplished with a tightly collimated fanned array of fiber-optically coupled photomultipliers. Deep (≈100%), high frequency (40–90 kHz) modulation of the pellet emission has been observed in both neutral beam and rf heated discharges with as little as ≈1.5 MW of heating. This finding is consistent with recent work carried out on ASDEXb) with the exception that this modulation phenomenon is seen not only with hydrogenic pellets but also with lithium and boron pellets. This observation seems to point to an instability associated with the plasma surrounding the pellet rather than an instability which depends upon the atomic physics of the pellet. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146243
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  • 2
    Electronic Resource
    Electronic Resource
    Local transport barrier formation and relaxation in reverse-shear plasmas on the Tokamak Fusion Test Reactor : The 38th annual meeting of the Division of Plasma Physics (DPP) of the American Physical Society (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 1736-1744 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The roles of turbulence stabilization by sheared E×B flow and Shafranov shift gradients are examined for Tokamak Fusion Test Reactor [D. J. Grove and D. M. Meade, Nucl. Fusion 25, 1167 (1985)] enhanced reverse-shear (ERS) plasmas. Both effects in combination provide the basis of a positive-feedback model that predicts reinforced turbulence suppression with increasing pressure gradient. Local fluctuation behavior at the onset of ERS confinement is consistent with this framework. The power required for transitions into the ERS regime are lower when high power neutral beams are applied earlier in the current profile evolution, consistent with the suggestion that both effects play a role. Separation of the roles of E×B and Shafranov shift effects was performed by varying the E×B shear through changes in the toroidal velocity with nearly steady-state pressure profiles. Transport and fluctuation levels increase only when E×B shearing rates are driven below a critical value that is comparable to the fastest linear growth rates of the dominant instabilities. While a turbulence suppression criterion that involves the ratio of shearing to linear growth rates is in accord with many of these results, the existence of hidden dependencies of the criterion is suggested in experiments where the toroidal field was varied. The forward transition into the ERS regime has also been examined in strongly rotating plasmas. The power threshold is higher with unidirectional injection than with balance injection. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872275
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of elevated temperature on the photosynthetic efficiency of zooxanthellae in hospite from four different species of reef coral: a novel approach (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Bleaching of reef corals is a phenomenon linked to temperature stress which involves loss of the symbiotic algae of the coral, which are known as zooxanthellae, and/or loss of algal pigments. The photosynthetic efficiency of zooxanthellae within the corals Montastrea annularis, Agaricia lamarki, Agaricia agaricites and Siderastrea radians was examined by pulse-amplitude modulation fluorometry (PAM) during exposure to elevated temperatures (30–36°C). Zooxanthellae within M. annularis and A. lamarki were found to be more sensitive to elevated temperature, virtually complete disruption of photosynthesis being noted during exposure to temperatures of 32 and 34°C. The photosynthetic efficiency of zooxanthellae within S. radians and A. agaricites decreased to a lesser extent. Differences in the loss of algal cells on an aerial basis and in the cellular chlorophyll concentration were also found between these species. By combining the non-invasive PAM technique with whole-cell fluorescence of freshly isolated zooxanthellae, we have identified fundamental differences in the physiology of the symbionts within different species of coral. Zooxanthellae within M. annularis appear to be more susceptible to heat-induced damage at or near the reaction centre of Photosystem II, while zooxanthellae living in S. radians remain capable of dissipating excess excitation energy through non-photochemical pathways, thereby protecting the photosystem from damage during heat exposure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00251.x
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  • 4
    Electronic Resource
    Electronic Resource
    Repression of lipopolysaccharide biosynthesis in Escherichia coli by an antisense RNA of Acetobacter methanolicus phage Acm1 (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 15 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Lysogenic Acetobacter methanolicus strains carrying the prophage Acm1 were found to be unable to synthesize both the capsutar polysaccharide (CPS) and the O-specific side-chain of lipopolysaccharide (LPS) and to represent rough variants of the host bacterium. A 262 bp DNA fragment of phage Acm1, obviously required for interference with LPS biosynthesis, was cloned and expressed in Escherichia coli Independently of the O-type, transformation of various E. coli strains with the recombinant DNA resulted in a suppression of biosynthesis of the O-specific chains. The DNA fragment of phage Acm1 contained three very short open reading frames of 21, 24, and 36 bp. However, attempts to express phage-encoded peptides were not successful. Instead, the Acm1-derived DNA fragment was shown to code for the synthesis of a trans-acting RNA molecule of 97 nucleotides, designated lbi (LPS biosynthesis-interfering) RNA. This RNA contains sequence complementarity to E. coli target RNA sequences and appears to have the ability to form intracellularly RNA hybrid duplexes with mRNA. The data presented in this study support the hypothesis that the phenotypic effect of conversion to rough-type LPS is accompanied by the expression of an antisense RNA of phage Acm1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.tb02285.x
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  • 5
    Electronic Resource
    Electronic Resource
    Das periodische Gesetz (1893)
    Springer
    Monatshefte für Chemie 14 (1893), S. 8-23 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01517850
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of Heavy Metals (Hg2+, Cd2+, Pb2+) During the Embryonic Development of Acridid Grasshoppers (Insecta, Caelifera) (1999)
    Springer
    Archives of environmental contamination and toxicology 36 (1999), S. 405-414 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Heavy metals present in the soil get differently accumulated in organisms and show different rates of toxicity at different stages of the life cycle of any organism living there. To see whether such toxicants get accumulated during the embryonic development and/or change the normal developmental processes of organisms exposed to heavy metals, freshly laid eggs and egg pods of two acridids, Aiolopus thalassinus and Eyprepocnemis plorans, were tested against different concentrations of Hg2+, Cd2+, and Pb2+. At increasing Hg2+ concentration in the substrate, an increased egg mortality and reduced nymphal hatching in A. thalassinus were observed, yet no change in the normal duration for embryonic development was noticed. A higher hatching rate of E. plorans nymphs than that of A. thalassinus could possibly be due to the higher tolerance, contributed by larger egg volume and thicker foam around the egg pods of the former. Treated concentrations of Hg2+ could be of sublethal (0.121 μg Hg2+/g substrate) to lethal (0.605 μg and more Hg2+/g substrate) doses. The mortality of eggs did not always increase with increasing substrate concentration of Cd2+ and Pb2+, and the hatching rates of both grasshopper species in many cases were even higher than that in the control. Still, lower accumulation factors of Cd2+ and Pb2+ than that of Hg2+ were found coupled with not increased mortality. The tested concentrations of Cd2+ and Pb2+ in the substrates, thus, could be of subacute doses. The embryonic development was found prolonged due to Cd2+ and Pb2+. During parallel egg and egg pod treatments, higher metal concentrations were found in not developed eggs than that in fresh nymphs hatching from the same substrates. This indicated the role of foam around the egg pods as “protective filter” against the toxic substances in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006613
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  • 7
    Electronic Resource
    Electronic Resource
    Injection and detection of a spin-polarized current in a light-emitting diode (1999)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 402 (1999), S. 787-790 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The field of magnetoelectronics has been growing in practical importance in recent years. For example, devices that harness electronic spin—such as giant-magnetoresistive sensors and magnetoresistive memory cells—are now appearing on the market. In contrast, magnetoelectronic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/45502
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  • 8
    Electronic Resource
    Electronic Resource
    A fast interface solver for the biharmonic Dirichlet problem on polygonal domains (1998)
    Springer
    Numerische Mathematik 78 (1998), S. 577-596 
    Details
    ISSN: 0945-3245
    Keywords: Mathematics Subject Classification (1991): 31A30, 35J40, 65N30, 65N12
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary. In this paper we propose and analyze an efficient discretization scheme for the boundary reduction of the biharmonic Dirichlet problem on convex polygonal domains. We show that the biharmonic Dirichlet problem can be reduced to the solution of a harmonic Dirichlet problem and of an equation with a Poincaré-Steklov operator acting between subspaces of the trace spaces. We then propose a mixed FE discretization (by linear elements) of this equation which admits efficient preconditioning and matrix compression resulting in the complexity $\log \varepsilon^{-1} O ( N \log^qN)$ . Here $N$ is the number of degrees of freedom on the underlying boundary, $\varepsilon 〉 0$ is an error reduction factor, $q = 2$ or $q = 3$ for rectangular or polygonal boundaries, respectively. As a consequence an asymptotically optimal iterative interface solver for boundary reductions of the biharmonic Dirichlet problem on convex polygonal domains is derived. A numerical example confirms the theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002110050326
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of acute administration of ethanol and the μ-opiate agonist etonitazene on thyroid hormone metabolism in rat brain (1998)
    Springer
    Psychopharmacology 135 (1998), S. 63-69 
    Details
    ISSN: 1432-2072
    Keywords: Key wordsEthanol ; Etonitazene ; Deiodinases ; Thyroid hormones ; Rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of acute, low-dose administration of ethanol (1 g/kg bodyweight) and the μ-opioid receptor agonist etonitazene (30 μg/kg bodyweight) on the activities of the iodothyronine deiodinase isoenzymes were investigated in nine regions of the rat brain. The experiments were performed at three different times of the 24-h cycle (1300, 2100 and 0500 hours) and the rats were decapitated 30 and 120 min after administration of the respective drugs. Interest was focused on changes in the two enzymes that catalyze 1) 5′-deiodination of thyroxine (T4) to the biologically active triiodothyronine (T3), i.e. type II 5′-deiodinase (5′D-II) and 2) 5 (or inner-ring) deiodination of T3 to the biologically inactive 3′3-T2, i.e. type III deiodinase (5D-III). 120 min after administration of ethanol and etonitazene 5D-III activity was selectively inhibited in the frontal cortex (at 1300 and 1700 hours) and the amygdala (at all three measuring times). The 5′D-II activity was significantly enhanced 30 min after administration of etonitazene in the frontal cortex, amygdala and limbic forebrain, and after administration of ethanol in the amygdala alone. These effects on 5′D-II activity were seen at 2100 hours only. In conclusion, the two different addictive drugs both reduced the inactivation of the physiologically active thyroid hormone T3 and enhanced its production. These effects occurred almost exclusively in the brain regions which were most likely to be involved in the rewarding properties of addictive drugs. As thyroid hormones have stimulating and mood-elevating properties, an involvement of these hormones in the reinforcing effects of addictive drugs seems conceivable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050486
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  • 10
    Electronic Resource
    Electronic Resource
    Design Issues of a Semi-Autonomous Robotic Assistant for the Health Care Environment (1998)
    Springer
    Journal of intelligent and robotic systems 22 (1998), S. 191-209 
    Details
    ISSN: 1573-0409
    Keywords: robotic assistant ; mobile service robot ; health care ; fetch-and-carry task ; mobile manipulation ; human-robot interface ; augmented virtual workspace
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper discusses design issues of a mobile robotic assistant for health or home care applications with the objective of relieving hospital personnel or domestic users of time-consuming routine tasks. These tasks are delegated to the robot via natural language and in turn autonomously executed. With respect to the execution of typical fetch-and-carry tasks, key components are surveyed and a system architecture for integration of the individual hardware and software modules into a service robot is presented. A prototype implementation is described and used for demonstrating the performance of the proposed design approach in real-world service scenarios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008082024638
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