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  • 1
    Publication Date: 2012-03-23
    Description: Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 +/- 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 +/- 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, David E -- Zuber, Maria T -- Phillips, Roger J -- Solomon, Sean C -- Hauck, Steven A 2nd -- Lemoine, Frank G -- Mazarico, Erwan -- Neumann, Gregory A -- Peale, Stanton J -- Margot, Jean-Luc -- Johnson, Catherine L -- Torrence, Mark H -- Perry, Mark E -- Rowlands, David D -- Goossens, Sander -- Head, James W -- Taylor, Anthony H -- New York, N.Y. -- Science. 2012 Apr 13;336(6078):214-7. doi: 10.1126/science.1218809. Epub 2012 Mar 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22438509" target="_blank"〉PubMed〈/a〉
    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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  • 2
    Publication Date: 2012-03-23
    Description: Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zuber, Maria T -- Smith, David E -- Phillips, Roger J -- Solomon, Sean C -- Neumann, Gregory A -- Hauck, Steven A 2nd -- Peale, Stanton J -- Barnouin, Olivier S -- Head, James W -- Johnson, Catherine L -- Lemoine, Frank G -- Mazarico, Erwan -- Sun, Xiaoli -- Torrence, Mark H -- Freed, Andrew M -- Klimczak, Christian -- Margot, Jean-Luc -- Oberst, Jurgen -- Perry, Mark E -- McNutt, Ralph L Jr -- Balcerski, Jeffrey A -- Michel, Nathalie -- Talpe, Matthieu J -- Yang, Di -- New York, N.Y. -- Science. 2012 Apr 13;336(6078):217-20. doi: 10.1126/science.1218805. Epub 2012 Mar 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. zuber@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22438510" target="_blank"〉PubMed〈/a〉
    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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  • 3
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An immuno-electron microscopic analysis was undertaken to determine ICAM-1 expression on vascular endothelium in human tonsils and in synovia from patients with rheumatoid arthritis. ICAM-1 was preferentially expressed on high endothelial venules (HEV) located in the parafollicular regions of the tonsils and on HEV located in the villous processes of the synovia. On both tissues, these areas contained the greatest number of perivascular lymphocytes. In contrast, ICAM-1 was only weakly expressed on the low endothelium lining capillaries, venules and sinusoids. In both tonsils and synovia, ICAM-1 was confined to the luminal and lateral surfaces of the endothelial cells and absent from the abluminal surfaces adjacent to the basement membrane. We propose that in inflammatory tissues, ICAM-1 mediates the interaction of circulating lymphocytes with the high endothelial cells, but may not have a major role in promoting their migration through the whole thickness of the blood vessel wall.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study assessed the distribution and structural features of plasma cells in rheumatoid synovial tissue. Plasma cells were found to be the predominant infiltrating mononuclear cells (mean 40%) in relation to lymphocytes and monocytes, and there was a direct relationship between their number in the infiltrates and the total number of mononuclear leucocytes (P = 0.007). Plasma cells were also seen in intimate contact with macrophages intermixed with synovial lining cells, and closely associated with small blood vessels. They often surrounded these blood vessels and sometimes were seen lying within the vessel walls themselves. Ultrastructural analysis revealed that many synovial plasma cells were considerably larger than plasma cells of a normal size and possessed a marked distension of the cisternae of rough endoplasmic reticulum. Furthermore, plasma cells in close proximity to blood vessels often appeared to be undergoing migration. These observations imply that in rheumatoid synovium, plasma cells are metabolically very active and occupy a pivotal position for the secretion of antibodies into both the vascular and the extravascular compartments.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0878
    Keywords: Palatine tonsil ; Immuno-electron microscopy ; High endothelial venules ; Adhesion molecules ; ICAM-1, LFA-1 ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunohistological analysis of sections prepared from human palatine tonsils revealed marked differences in the distribution of the adhesion molecule, leucocyte function antigen-1 (LFA-1) and its counter receptor, intercellular adhesion molecule-1 (ICAM-1). Light microscopy showed that LFA-1 was restricted to the leucocytes, particularly the lymphocytes. In contrast, staining of ICAM-1 was predominantly confined to the vascular endothelium with the greatest expression seen on the morphologically distinct high endothelial venules in the parafollicular areas; these are the sites that appear to support lymphocyte migration. Electron microscopy revealed that ICAM-1 was present on the luminal and lateral surfaces of the high endothelium and absent from the abluminal surface supported by basal lamina. The ICAM-1 was also absent from those surfaces of the endothelium that were in close contact with intravascular lymphocytes. Other cells stained by the anti-ICM-1 antibody included dendritic cells, plasma cells and epithelial cells in the reticulated crypt epithelium and in the upper strata of the non-keratinised stratified squamous epithelium. The high expression of LFA-1 was most prominent on lymphocytes, low on antigen-presenting cells and activated lymphoid cells, and not detectable on plasma cells, epithelial and endothelial cells. We propose that LFA-1/ICAM-1 binding participates in mediating the transendothelial migration of lymphocytes across the high endothelial venules of palatine tonsil.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1437-160X
    Keywords: Key words Multinucleated plasma cells ; Morphology ; Synovium ; Rheumatoid arthritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A morphological examination of synovial tissue from 25 patients with rheumatoid arthritis revealed that binucleated or multinucleated plasma cells were present in all samples and absent in synovia obtained from 16 control patients. Plasma cells containing two, three of four nuclei constitutet a mean 3% of the total plasma cell population. They were aways found amongst plasma cell infiltrates and in close association with small blood vessels. Ultrastructural analysis found no evidence of cellular membranes separating the individual nuclei in binucleated or multinucleated plasma cells, suggesting that the cells did not arise from fusion. Some of these plasma cells had a diameter approaching 100 µm, and many were in intimate contact with macrophages. The demonstration of a few cells with mitotic figures within the infiltrates suggests that the maintenance of plasma cell numbers in rheumatoid synovium may depend, in part, upon their local proliferation.
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  • 7
    Publication Date: 2018-10-05
    Description: The sizes of Saturn’s ring particles range from meters (boulders) to nanometers (dust). Determination of the rings’ ages depends on loss processes, including the transport of dust into Saturn’s atmosphere. During the Grand Finale orbits of the Cassini spacecraft, its instruments measured tiny dust grains that compose the innermost D-ring of Saturn. The nanometer-sized dust experiences collisions with exospheric (upper atmosphere) hydrogen and molecular hydrogen, which forces it to fall from the ring into the ionosphere and lower atmosphere. We used the Magnetospheric Imaging Instrument to detect and characterize this dust transport and also found that diffusion dominates above and near the altitude of peak ionospheric density. This mechanism results in a mass deposition into the equatorial atmosphere of ~5 kilograms per second, constraining the age of the D-ring.
    Keywords: Geochemistry, Geophysics, Online Only, Planetary Science
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2018-10-05
    Description: The Pioneer and Voyager spacecraft made close-up measurements of Saturn’s ionosphere and upper atmosphere in the 1970s and 1980s that suggested a chemical interaction between the rings and atmosphere. Exploring this interaction provides information on ring composition and the influence on Saturn’s atmosphere from infalling material. The Cassini Ion Neutral Mass Spectrometer sampled in situ the region between the D ring and Saturn during the spacecraft’s Grand Finale phase. We used these measurements to characterize the atmospheric structure and material influx from the rings. The atmospheric He/H 2 ratio is 10 to 16%. Volatile compounds from the rings (methane; carbon monoxide and/or molecular nitrogen), as well as larger organic-bearing grains, are flowing inward at a rate of 4800 to 45,000 kilograms per second.
    Keywords: Atmospheric Science, Online Only, Planetary Science
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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