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  • LUNAR AND PLANETARY EXPLORATION  (12)
  • SOCIAL SCIENCES (GENERAL)  (2)
  • COMPUTER SYSTEMS  (1)
  • Cell & Developmental Biology  (1)
  • 1985-1989  (16)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 132 (1987), S. 57-64 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Potassium and sodium fluxes believed to be important in the cellular response to serum and growth factors have not been widely investigated in cells which have undergone terminal differentiation. In this study we have analyzed two main K+ transport systems - the ouabain-sensitive Na+/K+ pump and the bumetanide-sensitive transporter - in human muscle in vitro at two developmental stages: proliferating myoblasts and differentiated myotubes. Myoblast differentiation to myotubes was accompanied by a marked decrease in both the ouabain-sensitive and the bumetanide-sensitive K+ (Rb+) influxes. The addition of serum to the terminally differentiated myotubes had no effect on these K+ transporters. However, serum addition to serum-deprived, undifferentiated myoblasts produced a marked stimulation of these K+ fluxes.The bumetanide-sensitive K+ transporter in human myoblasts and myotubes has the following properties: (1) It carries 30% and 40% of the total K+ influx in myoblasts and myotubes, respectively. (2) It performs net efflux of K+ in the undifferentiated myoblasts and zero net flux (self-exchange) in terminally differentiated myotubes. (3) It is dependent on extracellular Na+ and Cl- in addition to K+. (4) In myoblasts, the Km value for K+ is 1.36 mM, similar to the Km for K+ of the Na+/K+ pump. (5) It is resistant to ouabain (up to 2 mM) and sensitive to furosemide (K0.5 = 5 × 10-6 M) and bumetanide (K0.5 = 10-7 M). These data indicate that following terminal differentiation of proliferating myoblasts to mitotically inactive myotubes there is an irreversible reduction of K+ fluxes with a change in the net flux of K+ carried by the bumetanide-sensitive transporter.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2011-08-19
    Description: The orbital properties, surface compositions, opposition surges, masses, radii, and densities of the satellites of Uranus are presented. It is noted that the Uranian satellites are comparable in size to the largest of Saturn's icy satellites while density measurements suggest that the bulk compositions of Ariel and Umbriel might be different from those of Titania and Oberon. Consideration is given to the two satellites of Neptune and the question of a third satellite is addressed. The elements of Charon, determined from astrometric observations by photographic and speckle interferometric techniques, and then from eclipse observations, are given. The diurnal period of Pluto and its photometric lightcurve are discussed. The similarities and differences existing between the satellites of Uranus and Neptune and the Pluto-Charon pair are mentioned briefly.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 3
    Publication Date: 2011-08-19
    Description: Homogeneous and core-differentiated silicate/ice models of the Uranian satellites Miranda, Ariel, Umbriel, Titania, and Oberon are examined in the light of imaging observations and mass and density determinations obtained during the Voyager 2 encounter with Uranus in January 1986. The data and model predictions are compared in extensive tables and graphs and discussed in detail. The mass fractions of silicates in Oberon and Titania are found to be between 0.42 and 0.65, about the same as the average for the satellites of Jupiter and Saturn but significantly higher than that for the smaller Saturnian satellites or that predicted by current solar-nebula models. It is suggested that the satellites formed by accretion of material from their primary planets' outer envelopes. The observed rock/ice fractions are attributed to solar-nebula CO and solid-organics abundances and to preferential dissolution of H2O in outer-envelope planetesimals.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 14884-14
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  • 4
    Publication Date: 2011-08-19
    Description: The planetary surface thermal models used in the present study are composed of particles which, while bright and optically thin in the visual, are dark and opaque in the thermal IR. It is assumed that insolation is absorbed over a finite regolith distance whose scale length relative to diurnal skin depth for thermal diffusion can be substantial. Attention is given to the lower daytime and higher nighttime temperatures predicted by comparison with models assuming absorption only at the surface. It is noted that, with sufficiently deep penetration of insulation and high thermal IR particle opacity, a solid-state greenhouse can result.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 72; 84-94
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  • 5
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    In:  Other Sources
    Publication Date: 2011-08-19
    Description: Data on the Uranian satellites from the January 25, 1986 flyby of Voyager 2 are presented. Ten new satellites were discovered by Voyager 2; the features and orbits of these ten satellites are examined. The main geological characteristics for Oberon, Umbriel, Titania, Ariel, and Miranda discovered in the Voyager 2 images are described. Possible relationships between the Uranian satellites and Jovian and Saturnian satellites are being researched.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Planetary Report (ISSN 0736-3680); 6; 4-7
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  • 6
    Publication Date: 2011-08-19
    Description: Infrared observations of Io during the 1986 apparition of Jupiter indicate that a large eruptive event occurred on the leading side of Io on August 7, 1986, UT. Measurements made at 4.8, 8.7, and 20 micrometers suggest that the source of the event was about 15 kilometers in radius with a model temperature of about 900 K. These measurements indicate that high-temperature volcanic activity on the leading side of Io may be more frequent than previously thought. The inferred temperature is significantly above the boiling point of sulfur in a vacuum (715 K) and thus constitutes strong evidence for active silicate volcanism on the surface of Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 242; 1280-128
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  • 7
    Publication Date: 2011-08-19
    Description: The topographies of the major moons of Uranus are described, and reasons for the appearances of the surfaces are given. Oberon and Titania, the two outermost major moons, have similar bulk properties but different appearances. Oberon appears to have been a largely passive structure for incoming projectiles, while Titania's surface shows extensive resurfacing. Umbriel and Ariel also have similar bulk properties and contrasting appearances, the former being totally bland except for two unexplained bright spots and the latter having a extensive network of surface faults. Miranda, the smallest and innermost of the major moons, has three large, remarkable ovoid regions on its surface. It is suggested that these ovoids are due to an uncompleted differentiation process.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Scientific American (ISSN 0036-8733); 256; 48-60
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  • 8
    Publication Date: 2011-08-19
    Description: The 'solid-state greenhouse effect' model constituted by the subsurface solar heating of translucent, high-albedo materials is presently applied to the study of planetary surfaces, with attention to frost and ice surfaces of the solar system's outer satellites. Temperature is computed as a function of depth for an illustrative range of thermal variables, and it is discovered that the surfaces and interiors of such bodies can be warmer than otherwise suspected. Mechanisms are identified through which the modest alteration of surface properties can substantially change the solid-state greenhouse and force an interior temperature adjustment.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 77; 67-81
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  • 9
    Publication Date: 2011-08-19
    Description: NASA IRTF reflectance spectra of unprecedented precision, obtained for the leading and trailing sides of Europa, are presently noted to no longer show the apparent absorptions seen in 1980 and 1985. It is presently suggested that if the weak absorptions seen in the 1980 and 1985 data are real, they may indicate the transient spectroscopic presence of a molecular component on Europa's trailing side that differs from the water ice known to be the dominant constituent of the surface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 74; 262-271
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  • 10
    Publication Date: 2019-06-28
    Description: A workshop was held in an attempt to program real problems on the MIT Static Data Flow Machine. Most of the architecture of the machine was specified but some parts were incomplete. The main purpose for the workshop was to explore principles for the evaluation of computer systems employing new architectures. Principles explored were: (1) evaluation must be an integral, ongoing part of a project to develop a computer of radically new architecture; (2) the evaluation should seek to measure the usability of the system as well as its performance; (3) users from the application domains must be an integral part of the evaluation process; and (4) evaluation results should be fed back into the design process. It is concluded that the general organizational principles are achievable in practice from this workshop.
    Keywords: COMPUTER SYSTEMS
    Type: NASA-CR-185399 , NAS 1.26:185399 , RIACS-TR-85.3
    Format: application/pdf
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