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  • 1
    Publication Date: 2015-05-09
    Description: Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, Catherine L -- Phillips, Roger J -- Purucker, Michael E -- Anderson, Brian J -- Byrne, Paul K -- Denevi, Brett W -- Feinberg, Joshua M -- Hauck, Steven A 2nd -- Head, James W 3rd -- Korth, Haje -- James, Peter B -- Mazarico, Erwan -- Neumann, Gregory A -- Philpott, Lydia C -- Siegler, Matthew A -- Tsyganenko, Nikolai A -- Solomon, Sean C -- New York, N.Y. -- Science. 2015 May 22;348(6237):892-5. doi: 10.1126/science.aaa8720. Epub 2015 May 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada. Planetary Science Institute, Tucson, AZ 85719, USA. cjohnson@eos.ubc.ca. ; Planetary Science Directorate, Southwest Research Institute, Boulder, CO 80302, USA. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA. ; Lunar and Planetary Institute, Houston, TX 77058, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA. ; Institute for Rock Magnetism, Department of Earth Sciences, University of Minnesota, Minneapolis, MN, 55455, USA. ; Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA. ; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA. ; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. ; Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada. ; Planetary Science Institute, Tucson, AZ 85719, USA. Department of Earth Sciences, Southern Methodist University, Dallas, TX 75205, USA. ; Institute and Faculty of Physics, Saint Petersburg State University, Saint Petersburg, Russia. ; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25953822" 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: 2011-09-03
    Description: RNA can act as a regulator of gene expression with roles in transposon silencing, antiviral defense, and cell fate determination. Here, we show that in Caenorhabditis elegans a maternal transcript of the sex-determining gene fem-1 is required to license expression of a wild-type fem-1 allele in the zygotic germ line. Females homozygous for fem-1 deletions produce heterozygous offspring exhibiting germline feminization, reduced fem-1 activity, and transcript accumulation. Injection of fem-1 RNA incapable of encoding a protein into the maternal germ line rescues this defect in the progeny. The defect in zygotic fem-1 expression is heritable, suggesting that the gene is subject to epigenetic silencing that is prevented by maternal fem-1 transcripts. This mechanism may contribute to protecting the identity and integrity of the germ line.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, Cheryl L -- Spence, Andrew M -- Canadian Institutes of Health Research/Canada -- New York, N.Y. -- Science. 2011 Sep 2;333(6047):1311-4. doi: 10.1126/science.1208178.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics, Collaborative Program in Developmental Biology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21885785" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Caenorhabditis elegans/cytology/*genetics/physiology ; Caenorhabditis elegans Proteins/*genetics/metabolism ; Cell Cycle Proteins/*genetics/metabolism ; Crosses, Genetic ; *Epigenesis, Genetic ; Female ; Gene Deletion ; *Gene Silencing ; Germ Cells/*metabolism ; Heterozygote ; Homozygote ; Male ; Phenotype ; RNA, Helminth/*genetics ; RNA, Messenger/genetics ; Sex Determination Processes/*genetics ; Spermatogenesis
    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
    Publication Date: 2011-10-01
    Description: Magnetometer data acquired by the MESSENGER spacecraft in orbit about Mercury permit the separation of internal and external magnetic field contributions. The global planetary field is represented as a southward-directed, spin-aligned, offset dipole centered on the spin axis. Positions where the cylindrical radial magnetic field component vanishes were used to map the magnetic equator and reveal an offset of 484 +/- 11 kilometers northward of the geographic equator. The magnetic axis is tilted by less than 3 degrees from the rotation axis. A magnetopause and tail-current model was defined by using 332 magnetopause crossing locations. Residuals of the net external and offset-dipole fields from observations north of 30 degrees N yield a best-fit planetary moment of 195 +/- 10 nanotesla-R(M)(3), where R(M) is Mercury's mean radius.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anderson, Brian J -- Johnson, Catherine L -- Korth, Haje -- Purucker, Michael E -- Winslow, Reka M -- Slavin, James A -- Solomon, Sean C -- McNutt, Ralph L Jr -- Raines, Jim M -- Zurbuchen, Thomas H -- New York, N.Y. -- Science. 2011 Sep 30;333(6051):1859-62. doi: 10.1126/science.1211001.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA. brian.anderson@jhuapl.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21960627" 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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  • 4
    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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  • 5
    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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  • 6
    Publication Date: 2018-03-29
    Description: The spatial genetic structure of most species in the open marine environment remains largely unresolved. This information gap creates uncertainty in the sustainable management, recovery, and associated resilience of marine communities and our capacity to extrapolate beyond the few species for which such information exists. We document a previously unidentified multispecies biogeographic break aligned with a steep climatic gradient and driven by seasonal temperature minima in the northwest Atlantic. The coherence of this genetic break across our five study species with contrasting life histories suggests a pervasive macroecological phenomenon. The integration of this genetic structure with habitat suitability models and climate forecasts predicts significant variation in northward distributional shifts among populations and availability of suitable habitat in future oceans. The results of our integrated approach provide new perspective on how cryptic intraspecific diversity associated with climatic variation influences species and community response to climate change beyond simple poleward shifts.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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