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  • SPACE SCIENCES  (1,204)
  • Life and Medical Sciences  (490)
  • Humans  (369)
  • Lunar and Planetary Science and Exploration
  • 1980-1984  (705)
  • 1970-1974  (1,302)
  • 1940-1944  (56)
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  • 1
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this study, the intracellular concentrations of six elements (mmole/kg dry weight) were directly measured in the muscle fibers of pectoralis major muscles of eight week old, genetically dystrophic and normal chickens by the X-ray microanalysis technique. The extent of muscle degeneration was evaluated by morphometric measurements of muscle fiber diameter and other histological changes. A significant increase in the concentration of intracellular sodium and chlorine was evident in dystrophic muscles. The concentration of intracellular sodium was 127.0 ± 35.0 in the muscle fibers of dystrophic chicks compared to 65.7 ± 16.5 in normal controls. The concentration of chlorine was 90.5 ± 27.5 and 54.1 ± 5.5 in the muscle fibers of dystrophic and normal chicks respectively. The intracellular concentrations of potassium, magnesium, phosphorous, and sulfur remained unchanged in the dystrophic condition. Morphometric studies revealed that the dystrophic pectoralis muscles contain fewer but thicker fibers per unit area compared to normal pectoralis muscles. The importance of these findings are discussed in relation to the results of earlier investigations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0197-8462
    Keywords: millimeter-wave radiation ; BHK-21/C13 cells in monolayer culture ; scanning electron microscopy ; transmission electron microscopy ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Both thermal and athermal effects of millimeter-wave radiation on BHK-21/C13 cells were sought using scanning and transmission electron microscopy in conjunction with an in vitro technique that allows direct exposure of monolayer cultures to high average power densities. Culture dishes were irradiated by placing them on the open end of an E- or U-band wave guide. This technique exposes different regions of the cell monolayer lying along the longer axis of the wave guide aperture to varying power densities ranging from zero at each edge to twice the average power density at the center.Cell ultrastructure was unaffected by microwave radiation for 1 hour (41.8 or 74.0 GHz, average power densitites = 320 or 450 mW/cm2, respectively) with or without cooling by rapid recirculation of the culture medium. Temperature in recirculated cultures was held at 37.2 °C, and that in noncooled cultures never exceeded 42 °C during irradiation at either power density. In contrast, cell morphology was affected by microwave exposure whenever irradiation conditions were altered so that the temperature of the monolayer reached or exceeded 44.5 °C. Ultrastructural alterations included breakage of cell processes, progressive detachment of cells from the substrate, increased clumping of heterochromatin in the nuclei, and the appearance of large empty vesicles in the cytoplasm. Such morphological changes resulted from either application of higher average power densities or irradiation at the power densities described above at a higher ambient temperature (〉38.5°C).
    Additional Material: 5 Ill.
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  • 3
    Publication Date: 1984-12-21
    Description: Smell identification ability was measured in 1955 persons ranging in age from 5 to 99 years. On the average, women outperformed men at all ages, and nonsmokers outperformed smokers. Peak performance occurred in the third through fifth decades and declined markedly after the seventh. More than half of those 65 to 80 years old evidenced major olfactory impairment. After 80 years, more than three-quarters evidenced major impairment. Given these findings, it is not surprising that many elderly persons complain that food lacks flavor and that the elderly account for a disproportionate number of accidental gas poisoning cases each year.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Doty, R L -- Shaman, P -- Applebaum, S L -- Giberson, R -- Siksorski, L -- Rosenberg, L -- NS 16265/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1984 Dec 21;226(4681):1441-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6505700" target="_blank"〉PubMed〈/a〉
    Keywords: Adolescent ; Adult ; Aged ; *Aging ; Child ; Child, Preschool ; Female ; Humans ; Male ; Middle Aged ; Sensory Thresholds ; Sex Factors ; Smell/*physiology ; Smoking
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2019-06-27
    Description: Performance of Mariner Mars 1969 mission by flight and Earth-based elements during launch and space flight phases - Vol. 2
    Keywords: SPACE SCIENCES
    Type: NASA-CR-117351 , JPL-TR-32-1460-VOL-2
    Format: application/pdf
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  • 5
    Publication Date: 2019-06-27
    Description: A rather broad survey is reported of the Venus radar orbiter possibilities within the period 1983-1990. Minimum mission imaging requirements have been set by comparison with the improving capabilities of earth based radar systems and an examination of earth airborne radar imaging. This has led to a requirement for 80 percent coverage at a resolution of 100 m. A first main conclusion is that only the Shuttle-Centaur launch system would be capable of establishing a circular orbit under all possible launch conditions. Thus, orbit eccentricity has been introduced as a parameter throughout this presentation. An examination of typical radar designs has led to upper and lower limits on swath width of 100 and 50 km. A lower eccentricity of 0.2 was set by considering the current Viking propulsion system. An examination of solar perturbations indicates that orbit maintenance problems increase rapidly above an eccentricity of 0.5.
    Keywords: SPACE SCIENCES
    Type: NASA-TM-X-2868 , A-4834
    Format: application/pdf
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  • 6
    Publication Date: 2019-08-28
    Description: An evolutionary, gradual, and step-wise spacecraft systems technology development from those used on the Apollos and Skylab 1 to that required for the space station was considered. The four mission spacecraft were dry workshop versions of the Saturn 4-B stage, and each individually configured, outfitted and launched by INT-21 vehicles. These spacecraft were evaluated for crews of three, six and nine men and for mission lifetimes of one year. Two versions of the Apollo CSM, a three man and a four man crew, were considered as the logistic vehicle. The solar cell electrical power system of the first mission evolves into a light weight panel system supplemented by an operating isotope-Brayton system on the later missions. The open life support system of the first mission evolves to a system which recovers both water and oxygen on the last mission. The data handling, communications, radiation shielding, micrometeoroid protection, and orbit keeping systems were determined. The program costs were estimated and, excluding operational costs, the cost for each mission would average about $2 billion of which one-sixth would be for development, one-fourth for experiments, and the balance for vehicle acquisition.
    Keywords: SPACE SCIENCES
    Type: NASA-TM-X-69243 , MS-1
    Format: application/pdf
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 112 (1982), S. 307-315 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Ca2+ activation mechanism of the longitudinal body wall muscles of Parastichopus californicus (sea cucumber) was studied using skinned muscle fiber bundles. Reversible phosphorylation of the myosin light chains correlated with Ca2+-activated tension and relaxation. Pretreatment of the skinned fibers with ATPγS and high Ca2+ (10-5M) resulted in irreversible thiophosphorylation of the myosin light chains and activation of a Ca2+ insensitive tension. In contrast, pretreatment with low Ca2+ (10-8M) and ATPγS results in no thiophosphorylation of the myosin light chains or irreversible activation of tension. These results are consistent with a Ca2+-sensitive myosin light chain kinase/phosphatase system being responsible for the activation of the muscle. Other agents known to have an effect upon the Ca2+-activated tension in skinned vertebrate smooth muscle fibers (trifluoperazine, catalytic subunit of the cyclic AMP-dependent protein kinase, and calmodulin) did not have an effect on myosin light chain phosphorylation or Ca2+-activated tension. These results suggest a different type of myosin light chain kinase than is found in vertebrate smooth muscle is responsible for the activation of parastichopus longitudinal body wall muscle.
    Additional Material: 9 Ill.
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  • 8
    ISSN: 0148-7280
    Keywords: spermatozoa ; flow cytometry ; DNA staining ; nuclear morphology ; ultrastructure ; mammals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The morphological and ultrastructural changes that occur during preparation of porcine, bovine, and murine spermatozoa for flow cytometric quantification of the relative DNA content of the X- and Y-chromosome-bearing sperm populations were examined. Ejaculated spermatozoa from the boar and bull were washed using a series of dimethyl sulfoxide (DMSO) solutions prior to fixation, whereas the epididymal mouse spermatozoa were washed only in phosphate-buffered saline (PBS). Spermatozoa from all three species were then fixed in ethanol and processed for fluorochrome staining by a treatment regimen consisting of sulfhydryl reduction and proteolysis. The processed sperm nuclei were stained for DNA with the fluorochrome, 4′-6-diamidino-2-phenylindole (DAPI) before quantification by flow cytometry. Scanning and transmission electron micrographs of sperm heads taken at various steps of the preparation and staining procedures show 1) that the rigorous washing procedure disrupted the plasma and outer acrosomal membranes, 2) that ethanol fixation resulted in removal of the outer membranes and disintegration of the nuclear envelope, and 3) that thiol and proteolysis treatment removed the remaining cellular organelles including the tail and rapidly induced partial decondensation of the tightly packed chromatin. Sequential micrographs showed that the nuclear matrix of all three species increased in thickness about twofold during the preparation and staining. Consequently, the harsh procedures currently used for quantitative staining of DNA for high-resolution flow cytometric analyses destroy most cellular organelles and thereby prevent simultaneous characterization of DNA content and other sperm cell constituents.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 0197-8462
    Keywords: millimeter-wave radiation ; BHK-21/C13 cells in monolayer culture ; quantitative autoradiography ; ribonucleic acid (RNA) synthesis ; protein synthesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A method has been devised whereby both the thermal and possible athermal biological effects resulting from microwave radiation can be assessed. Monolayer cultures of BHK-21/C13 cells were grown on microwave-transparent polystyrene coverslips, placed directly on the open end of a wave guide, and irradiated for 1 hour. In experiments seeking athermal biological effects of millimeter waves, culture medium was continuously recirculated over the cells to prevent temperature increases greater than 0.1 °C. Incorporation of 3H-uridine into RNA and of 3H-methionine into protein was quantified by measurement of optical densities of the autoradiographs in contiguous rectangular regions corresponding to portions of the cell monolayer immediately above the wave guide aperture and lying along its longer axis. Since power density was shown to vary with position along this axis according to a cosine2 relationship, it was possible to assess the extent of microwave effects on macromolecular synthesis at power densities ranging from zero at each edge to twice the average power density at the center of the waveguide.Monolayer cultures maintained at 37.2 °C by recirculation of the medium did not show microwave-induced changes in synthesis of RNA and protein (41.8 or 74.0 GHz at average power densities of 320 or 450 mW/cm2, respectively). Since macromolecular synthesis was examined both during and after irradiation, our results exclude both transient and persistent athermal biological effects of acute exposure to millimeter waves. In contrast, irradiation of cultures incubated in a small volume of nonrecirculated medium resulted in 1) marked heating of the monolayer, 2) a graded decline in macromolecular synthesis with increasing incident power, and 3), in some cases, destruction of the cell monolayer in the region immediately above the center of the waveguide aperture.
    Additional Material: 12 Ill.
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  • 10
    ISSN: 0197-8462
    Keywords: protein synthesis ; quantitative autoradiography ; BHK-21/C13 cells ; millimeter-wave radiation ; frequency-specific biological effects ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A method recently developed in this laboratory has been used to directly expose BHK-21/C13 cells to high levels of microwave radiation without significant microwave-induced heating (≤ 0.1 °C). Monolayer cultures were grown on microwave-transparent polystyrene coverslips, placed on the open end of a wave guide, and maintained at 37.2 °C during irradiation at frequencies in both the E- and U-bands (average power densities 292 and 177 mW/cm2, respectively). Effects of microwave radiation were assessed at 0.1 GHz increments in the ranges of 38-48 GHz and 65-75 GHz. Protein synthesis was measured in quadruplicate cultures that were allowed to incorporate labeled methionine during the 15-minute period of microwave irradiation. Autoradiographs of each monolayer culture were scanned along the region corresponding to the longer axis of the wave guide aperture using a microdensitometer to quantify incorporation. Since microwave power incident on the cells was previously shown to vary along this axis according to a cosine2 relationship from zero at each edge of the wave guide to twice the average power density at the center of the wave guide, this technique should reveal biological effects that might only be manifested in narrow amplitude domains or “power windows.” Observations of protein synthesis in monolayer cultures irradiated at 202 closely spaced frequencies in the E- and U-bands failed to reveal changes associated with microwave exposure. Thus no evidence was obtained in support of the existence of frequency-specific athermal biological effects of microwaves. In addition, no support was found for the existence of amplitude-specific “power windows”.
    Additional Material: 6 Ill.
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