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  • 1
    ISSN: 1573-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Fluorescein mercuric acetate (FMA) has been shown to be a potent inhibitor of energized processes in both beef heart mitochondria and ETPH particles. FMA reacts preferentially with a small number of specific sulfur atoms and inhibits the phosphate-dependent configurational transition. FMA enhances the anaerobic to aerobic pH changes observed in intact mitochondria and submitochondrial particles, and also enhances nonenergized swelling in 0·15 M sodium or potassium chloride. The results are interpreted in terms of a model whereby FMA, in reacting with the mitochondrion, modifies its conformation. The resulting conformational changes which occur upon energization are therefore different from those conformational changes which would occur in the absence of FMA. The net result of this process is the inhibition of some processes (e.g., oxidative phosphorylation, ATP-32Pi exchange, etc.) and the enhancement of other processes (the proton shift and nonenergized swelling in chloride salts).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0603
    Keywords: End-labeling ; GBS ; Mapping ; Restriction enzyme mapping ; Tn917
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two pieces of data are needed to fully map the location of a transposon inserted in a plasmid, the site of insertion and the transposon's orientation. Both of these parameters can be determined from a map of restriction sites, which can be derived by end-probing. Like restriction mapping, end-probing reveals the distance between restriction sites on a plasmid. In contrast to restriction mapping, end-probing unambiguously reveals the order of those restriction sites. End-probing is similar to end-labeling, except that the uncertainties inherent in the radiolabeling reaction (and the problems of working with radionucleotides) are avoided. In this paper we discuss the use of end-probing as a means to map insertions of transposon Tn917 into the Streptococcus agalactiae plasmid pGB354
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In space plasmas the phenomenon of mass loading is common. Comets are one of the most evident objects where mass loading controls to a large extent the structure and dynamics of its plasma environment. New charged material is implanted to the fast streaming solar wind by planets, moons, other solar system objects, and even by the interstellar neutral gas flowing through our solar system. In this review we summarize both the current observations and the relevant theoretical approaches. First we survey the MHD methods, starting with a discussion how mass loading affects subsonic and supersonic gasdynamics flows, continuing this with single and multi-fluid MHD approaches to describe the flow when mass, momentum and energy is added, and we finish this section by the description of mass loaded shocks. Next we consider the kinetic approach to the same problem, discussing wave excitations, pitch angle and energy scattering in linear and quasi-linear approximations. The different descriptions differ in assumptions and conclusions; we point out the differences, but it is beyond the scope of the paper to resolve all the conflicts. Applications of these techniques to comets, planets, artificial ion releases, and to the interplanetary neutrals are reviewed in the last section, where observations are also compared with models, including hybrid simulations as well. We conclude the paper with a summary of the most important open, yet unsolved questions.
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  • 4
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The interaction of interstellar pickup ions with the solar wind termination shock is reviewed and assessed. The pickup ions mass and momentum load the wind and increase its pressure, effects which decrease the strength of the shock and its distance from the Sun. The pickup hydrogen may contribute substantially to the "reflected" ion population, which should provide most of the dissipation at the supercritical quasi-perpendicular shock. A fraction of the pickup ions impinging on the shock is "injected" into the process of diffusive shock acceleration to form the anomalous cosmic ray component. An injection mechanism which accounts for the apparent absence of solar wind ions in the anomalous component is "shock surfing", in which pickup ions which approach the shock slowly may be trapped between the upstream Lorentz force and the shock potential and accelerated in the motional electric field beyond the energy threshold for diffusive shock acceleration. However, the simplest interpretation of shock surfing would favor less massive pickup ion species, in contradiction with Voyager observations of anomalous component composition. A possible extension of the shock surfing mechanism is considered, as well as other injection mechanisms. Finally, the pressure of the anomalous component may modify the structure of the termination shock, which in turn may influence injection rates.
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  • 5
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Since most Alfvén-waves in the solar wind are observed to come from the Sun, nonlinear wave-particle interactions can be expected to constitute their dominant dissipation process. The growth or damping of two circularly-polarized Alfvén-waves with wave vectors parallel to the ambient magnetic field is calculated using kinetic theory. If the waves are oppositely polarized they both damp proportional to their frequency. If the waves are of the same polarization, both the lower frequency wave and the plasma particles gain energy at the expense of the higher frequency wave. Thus, with increasing distance from the Sun, a steepening of the power spectrum is expected. For waves propagating in the same direction, the interaction is negligible for small β, while it becomes appreciable for β≥10−1. For conditions typical of the solar wind near 1 AU an observed half-hour linearly-polarized wave, for example, with δB=0(B 0) has a damping time of about 10 h.
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  • 6
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spatial dependence of the pitch-angle and associated spatial diffusion coefficients for cosmic ray particles in interplanetary space is calculated in the WKB approximation. The model considers only Alfven waves of solar origin to be responsible for scattering of moderate energy particles. After developing the general theory results are presented for the asymptotic case corresponding to radial distancesr greater than about 1 to 2 AU. The radial diffusion coefficientи r increases with energyE likeи r ∼E υ, wherev≈2/3. The radial mean free path turns out to increase proportional tor 3 at medium and low heliographic latitudes. This behaviour is consistent with a very small radial cosmic ray gradient and the existence of a ‘free boundary’ for particle diffusion. At equal radial distances the high latitude mean free path is not only much smaller than the one calculated at the lower latitudes but in addition increases only weakly with distance. Some conceivable dynamical implications for the outer solar system are indicated.
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  • 7
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a kinetic model of the heating and acceleration of coronal protons by outward-propagating ion-cyclotron waves on open, radial magnetic flux tubes. In contrast to fluid models which typically insist on bi-Maxwellian distributions and which spread the wave energy and momentum over the entire proton population, this model follows the kinetic evolution of the collisionless proton distribution function in response to the combination of the resonant wave-particle interaction and external forces. The approximation is made that pitch-angle scattering by the waves is faster than all other processes, resulting in proton distributions which are uniform over the resonant surfaces in velocity space. We further assume, in this preliminary version, that the waves are dispersionless so these resonant surfaces are portions of spheres centered on the radial sum of the Alfvén speed and the proton bulk speed. We incorporate the fact that only those protons with radial speeds less than the bulk speed will be resonant with outward-propagating waves, so this rapid interaction acts only on the sunward half of the distribution. Despite this limitation, we find that the strong perpendicular heating of the resonant particles, coupled with the mirror force, results in substantial outward acceleration of the entire distribution. The proton distribution evolves towards an incomplete shell in velocity space, and appears vastly different from the distributions assumed in fluid models. Evidence of these distinctive distributions should be observable by instruments on Solar Probe.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 72 (1995), S. 485-494 
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper reproduces the Symposium Summary presentation at the 28th ESLAB Symposium on The High Latitude Heliosphere. The summary is not comprehensive but with considerable latitude covers the highlights of the conference. Featured are the observations of the high-speed wind from the growing southern polar coronal hole, new measurements of the interstellar gas and pickup ions, new measurements of cosmic ray modulation at high latitude, and our growing awareness of the three-dimensional heliosphere.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 78 (1996), S. 109-116 
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An overview of the solar wind termination shock is presented including: its place in the heliosphere and its origin; its structure including the role of interstellar pickup ions and galactic and anomalous cosmic rays; its inferred location based on Lyman-α backscatter, Voyager radio signals, and anomalous cosmic rays; its shape and movement.
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 43 (1978), S. 518-518 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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