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  • 1
    Publication Date: 2015-02-18
    Description: Enhancers regulate spatiotemporal gene expression and impart cell-specific transcriptional outputs that drive cell identity. Super-enhancers (SEs), also known as stretch-enhancers, are a subset of enhancers especially important for genes associated with cell identity and genetic risk of disease. CD4(+) T cells are critical for host defence and autoimmunity. Here we analysed maps of mouse T-cell SEs as a non-biased means of identifying key regulatory nodes involved in cell specification. We found that cytokines and cytokine receptors were the dominant class of genes exhibiting SE architecture in T cells. Nonetheless, the locus encoding Bach2, a key negative regulator of effector differentiation, emerged as the most prominent T-cell SE, revealing a network in which SE-associated genes critical for T-cell biology are repressed by BACH2. Disease-associated single-nucleotide polymorphisms for immune-mediated disorders, including rheumatoid arthritis, were highly enriched for T-cell SEs versus typical enhancers or SEs in other cell lineages. Intriguingly, treatment of T cells with the Janus kinase (JAK) inhibitor tofacitinib disproportionately altered the expression of rheumatoid arthritis risk genes with SE structures. Together, these results indicate that genes with SE architecture in T cells encompass a variety of cytokines and cytokine receptors but are controlled by a 'guardian' transcription factor, itself endowed with an SE. Thus, enumeration of SEs allows the unbiased determination of key regulatory nodes in T cells, which are preferentially modulated by pharmacological intervention.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409450/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409450/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vahedi, Golnaz -- Kanno, Yuka -- Furumoto, Yasuko -- Jiang, Kan -- Parker, Stephen C J -- Erdos, Michael R -- Davis, Sean R -- Roychoudhuri, Rahul -- Restifo, Nicholas P -- Gadina, Massimo -- Tang, Zhonghui -- Ruan, Yijun -- Collins, Francis S -- Sartorelli, Vittorio -- O'Shea, John J -- 105663/Z/14/Z/Wellcome Trust/United Kingdom -- R01 CA186714/CA/NCI NIH HHS/ -- ZIA AR041159-07/Intramural NIH HHS/ -- England -- Nature. 2015 Apr 23;520(7548):558-62. doi: 10.1038/nature14154. Epub 2015 Feb 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Lymphocyte Cell Biology Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA. ; Translational Immunology Section, NIAMS, NIH, Bethesda, Maryland 20892, USA. ; Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland 20892, USA. ; Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA. ; The Jackson Laboratory for Genomic Medicine and Department of Genetic and Development Biology, University of Connecticut, Farmington, Connecticut 06030, USA. ; Laboratory of Muscle Stem Cells and Gene Regulation, NIAMS, NIH, Bethesda, Maryland 20892, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25686607" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arthritis, Rheumatoid/*genetics/immunology/pathology ; Basic-Leucine Zipper Transcription Factors/metabolism ; Cell Differentiation/genetics ; Cell Lineage/genetics ; Enhancer Elements, Genetic/*genetics ; Gene Expression Regulation/genetics ; Genetic Predisposition to Disease/genetics ; Janus Kinase 3/antagonists & inhibitors ; Mice ; Mice, Inbred C57BL ; Piperidines/pharmacology ; Pyrimidines/pharmacology ; Pyrroles/pharmacology ; RNA, Untranslated/genetics ; T-Lymphocytes, Helper-Inducer/immunology/*metabolism/*pathology ; Transcription, Genetic/genetics ; p300-CBP Transcription Factors/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2015-07-01
    Description: Patterns of amino acid conservation have served as a tool for understanding protein evolution. The same principles have also found broad application in human genomics, driven by the need to interpret the pathogenic potential of variants in patients. Here we performed a systematic comparative genomics analysis of human disease-causing missense variants. We found that an appreciable fraction of disease-causing alleles are fixed in the genomes of other species, suggesting a role for genomic context. We developed a model of genetic interactions that predicts most of these to be simple pairwise compensations. Functional testing of this model on two known human disease genes revealed discrete cis amino acid residues that, although benign on their own, could rescue the human mutations in vivo. This approach was also applied to ab initio gene discovery to support the identification of a de novo disease driver in BTG2 that is subject to protective cis-modification in more than 50 species. Finally, on the basis of our data and models, we developed a computational tool to predict candidate residues subject to compensation. Taken together, our data highlight the importance of cis-genomic context as a contributor to protein evolution; they provide an insight into the complexity of allele effect on phenotype; and they are likely to assist methods for predicting allele pathogenicity.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537371/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537371/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jordan, Daniel M -- Frangakis, Stephan G -- Golzio, Christelle -- Cassa, Christopher A -- Kurtzberg, Joanne -- Task Force for Neonatal Genomics -- Davis, Erica E -- Sunyaev, Shamil R -- Katsanis, Nicholas -- R01 DK072301/DK/NIDDK NIH HHS/ -- R01 DK075972/DK/NIDDK NIH HHS/ -- R01 DK095721/DK/NIDDK NIH HHS/ -- R01 EY021872/EY/NEI NIH HHS/ -- R01 GM078598/GM/NIGMS NIH HHS/ -- R01 HD042601/HD/NICHD NIH HHS/ -- R01 MH101244/MH/NIMH NIH HHS/ -- R01DK072301/DK/NIDDK NIH HHS/ -- R01DK075972/DK/NIDDK NIH HHS/ -- R01EY021872/EY/NEI NIH HHS/ -- R01HD04260/HD/NICHD NIH HHS/ -- U01 HG006500/HG/NHGRI NIH HHS/ -- England -- Nature. 2015 Aug 13;524(7564):225-9. doi: 10.1038/nature14497. Epub 2015 Jun 29.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. ; Center for Human Disease Modeling, Duke University, Durham, North Carolina 27701, USA. ; Department of Pediatrics, Division of Pediatric Blood and Marrow Transplantation, Duke University, Durham, North Carolina 27710, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26123021" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing/genetics ; Alleles ; Animals ; Disease/*genetics ; Evolution, Molecular ; Genome, Human/genetics ; *Genomics ; Humans ; Immediate-Early Proteins/genetics ; Microcephaly/genetics ; Mutation, Missense/*genetics ; Phenotype ; Proteins/genetics ; Sequence Alignment ; Suppression, Genetic/*genetics ; Tumor Suppressor Proteins/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2015-02-28
    Description: Global sustainability challenges, from maintaining biodiversity to providing clean air and water, are closely interconnected yet often separately studied and managed. Systems integration-holistic approaches to integrating various components of coupled human and natural systems-is critical to understand socioeconomic and environmental interconnections and to create sustainability solutions. Recent advances include the development and quantification of integrated frameworks that incorporate ecosystem services, environmental footprints, planetary boundaries, human-nature nexuses, and telecoupling. Although systems integration has led to fundamental discoveries and practical applications, further efforts are needed to incorporate more human and natural components simultaneously, quantify spillover systems and feedbacks, integrate multiple spatial and temporal scales, develop new tools, and translate findings into policy and practice. Such efforts can help address important knowledge gaps, link seemingly unconnected challenges, and inform policy and management decisions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, Jianguo -- Mooney, Harold -- Hull, Vanessa -- Davis, Steven J -- Gaskell, Joanne -- Hertel, Thomas -- Lubchenco, Jane -- Seto, Karen C -- Gleick, Peter -- Kremen, Claire -- Li, Shuxin -- New York, N.Y. -- Science. 2015 Feb 27;347(6225):1258832. doi: 10.1126/science.1258832.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Systems Integration and Sustainability, Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA. liuji@msu.edu. ; Department of Biology, Stanford University, Stanford, CA, USA. ; Center for Systems Integration and Sustainability, Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA. ; Department of Earth System Science, University of California, Irvine, CA, USA. ; World Bank, Washington, DC, USA. ; Department of Agricultural Economics, Purdue University, West Lafayette, IN, USA. ; Department of Integrative Biology, Oregon State University, Corvallis, OR, USA. ; School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA. ; The Pacific Institute, Oakland, CA, USA. ; Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25722418" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biodiversity ; Biofuels ; *Conservation of Natural Resources ; Earth (Planet) ; Endangered Species ; *Environmental Pollution ; Humans ; Socioeconomic Factors ; *Systems Integration ; Ursidae
    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: 2015-05-02
    Description: Centrioles are ancient organelles that build centrosomes, the major microtubule-organizing centers of animal cells. Extra centrosomes are a common feature of cancer cells. To investigate the importance of centrosomes in the proliferation of normal and cancer cells, we developed centrinone, a reversible inhibitor of Polo-like kinase 4 (Plk4), a serine-threonine protein kinase that initiates centriole assembly. Centrinone treatment caused centrosome depletion in human and other vertebrate cells. Centrosome loss irreversibly arrested normal cells in a senescence-like G1 state by a p53-dependent mechanism that was independent of DNA damage, stress, Hippo signaling, extended mitotic duration, or segregation errors. In contrast, cancer cell lines with normal or amplified centrosome numbers could proliferate indefinitely after centrosome loss. Upon centrinone washout, each cancer cell line returned to an intrinsic centrosome number "set point." Thus, cells with cancer-associated mutations fundamentally differ from normal cells in their response to centrosome loss.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4764081/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4764081/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wong, Yao Liang -- Anzola, John V -- Davis, Robert L -- Yoon, Michelle -- Motamedi, Amir -- Kroll, Ashley -- Seo, Chanmee P -- Hsia, Judy E -- Kim, Sun K -- Mitchell, Jennifer W -- Mitchell, Brian J -- Desai, Arshad -- Gahman, Timothy C -- Shiau, Andrew K -- Oegema, Karen -- GM074207/GM/NIGMS NIH HHS/ -- GM089970/GM/NIGMS NIH HHS/ -- GM103403/GM/NIGMS NIH HHS/ -- R01 GM089970/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2015 Jun 5;348(6239):1155-60. doi: 10.1126/science.aaa5111. Epub 2015 Apr 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Medicine, Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093, USA. ; Small Molecule Discovery Program, Ludwig Institute for Cancer Research, La Jolla, CA 92093, USA. ; Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA. ; Small Molecule Discovery Program, Ludwig Institute for Cancer Research, La Jolla, CA 92093, USA. koegema@ucsd.edu ashiau@ucsd.edu. ; Department of Cellular and Molecular Medicine, Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093, USA. koegema@ucsd.edu ashiau@ucsd.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25931445" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line, Tumor ; Cell Proliferation ; Centrioles/*drug effects ; Humans ; Mice ; Piperazines/pharmacology ; Protein Kinase Inhibitors/chemistry/*pharmacology ; Protein-Serine-Threonine Kinases/*antagonists & inhibitors ; Pyrimidines/chemistry/*pharmacology ; Sulfones/chemistry/*pharmacology
    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: 2015-02-14
    Description: Although it is generally accepted that cellular differentiation requires changes to transcriptional networks, dynamic regulation of promoters and enhancers at specific sets of genes has not been previously studied en masse. Exploiting the fact that active promoters and enhancers are transcribed, we simultaneously measured their activity in 19 human and 14 mouse time courses covering a wide range of cell types and biological stimuli. Enhancer RNAs, then messenger RNAs encoding transcription factors, dominated the earliest responses. Binding sites for key lineage transcription factors were simultaneously overrepresented in enhancers and promoters active in each cellular system. Our data support a highly generalizable model in which enhancer transcription is the earliest event in successive waves of transcriptional change during cellular differentiation or activation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681433/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681433/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Arner, Erik -- Daub, Carsten O -- Vitting-Seerup, Kristoffer -- Andersson, Robin -- Lilje, Berit -- Drablos, Finn -- Lennartsson, Andreas -- Ronnerblad, Michelle -- Hrydziuszko, Olga -- Vitezic, Morana -- Freeman, Tom C -- Alhendi, Ahmad M N -- Arner, Peter -- Axton, Richard -- Baillie, J Kenneth -- Beckhouse, Anthony -- Bodega, Beatrice -- Briggs, James -- Brombacher, Frank -- Davis, Margaret -- Detmar, Michael -- Ehrlund, Anna -- Endoh, Mitsuhiro -- Eslami, Afsaneh -- Fagiolini, Michela -- Fairbairn, Lynsey -- Faulkner, Geoffrey J -- Ferrai, Carmelo -- Fisher, Malcolm E -- Forrester, Lesley -- Goldowitz, Daniel -- Guler, Reto -- Ha, Thomas -- Hara, Mitsuko -- Herlyn, Meenhard -- Ikawa, Tomokatsu -- Kai, Chieko -- Kawamoto, Hiroshi -- Khachigian, Levon M -- Klinken, S Peter -- Kojima, Soichi -- Koseki, Haruhiko -- Klein, Sarah -- Mejhert, Niklas -- Miyaguchi, Ken -- Mizuno, Yosuke -- Morimoto, Mitsuru -- Morris, Kelly J -- Mummery, Christine -- Nakachi, Yutaka -- Ogishima, Soichi -- Okada-Hatakeyama, Mariko -- Okazaki, Yasushi -- Orlando, Valerio -- Ovchinnikov, Dmitry -- Passier, Robert -- Patrikakis, Margaret -- Pombo, Ana -- Qin, Xian-Yang -- Roy, Sugata -- Sato, Hiroki -- Savvi, Suzana -- Saxena, Alka -- Schwegmann, Anita -- Sugiyama, Daisuke -- Swoboda, Rolf -- Tanaka, Hiroshi -- Tomoiu, Andru -- Winteringham, Louise N -- Wolvetang, Ernst -- Yanagi-Mizuochi, Chiyo -- Yoneda, Misako -- Zabierowski, Susan -- Zhang, Peter -- Abugessaisa, Imad -- Bertin, Nicolas -- Diehl, Alexander D -- Fukuda, Shiro -- Furuno, Masaaki -- Harshbarger, Jayson -- Hasegawa, Akira -- Hori, Fumi -- Ishikawa-Kato, Sachi -- Ishizu, Yuri -- Itoh, Masayoshi -- Kawashima, Tsugumi -- Kojima, Miki -- Kondo, Naoto -- Lizio, Marina -- Meehan, Terrence F -- Mungall, Christopher J -- Murata, Mitsuyoshi -- Nishiyori-Sueki, Hiromi -- Sahin, Serkan -- Nagao-Sato, Sayaka -- Severin, Jessica -- de Hoon, Michiel J L -- Kawai, Jun -- Kasukawa, Takeya -- Lassmann, Timo -- Suzuki, Harukazu -- Kawaji, Hideya -- Summers, Kim M -- Wells, Christine -- FANTOM Consortium -- Hume, David A -- Forrest, Alistair R R -- Sandelin, Albin -- Carninci, Piero -- Hayashizaki, Yoshihide -- P30 CA010815/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 2015 Feb 27;347(6225):1010-4. doi: 10.1126/science.1259418. Epub 2015 Feb 12.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25678556" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Cattle ; Cell Differentiation/*genetics ; Dogs ; *Enhancer Elements, Genetic ; *Gene Expression Regulation, Developmental ; Mice ; RNA, Messenger/genetics/metabolism ; Rats ; Stem Cells/*cytology/metabolism ; Transcription Factors/*metabolism ; *Transcription, Genetic
    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: 2015-12-18
    Description: Understanding how ecological communities are organized and how they change through time is critical to predicting the effects of climate change. Recent work documenting the co-occurrence structure of modern communities found that most significant species pairs co-occur less frequently than would be expected by chance. However, little is known about how co-occurrence structure changes through time. Here we evaluate changes in plant and animal community organization over geological time by quantifying the co-occurrence structure of 359,896 unique taxon pairs in 80 assemblages spanning the past 300 million years. Co-occurrences of most taxon pairs were statistically random, but a significant fraction were spatially aggregated or segregated. Aggregated pairs dominated from the Carboniferous period (307 million years ago) to the early Holocene epoch (11,700 years before present), when there was a pronounced shift to more segregated pairs, a trend that continues in modern assemblages. The shift began during the Holocene and coincided with increasing human population size and the spread of agriculture in North America. Before the shift, an average of 64% of significant pairs were aggregated; after the shift, the average dropped to 37%. The organization of modern and late Holocene plant and animal assemblages differs fundamentally from that of assemblages over the past 300 million years that predate the large-scale impacts of humans. Our results suggest that the rules governing the assembly of communities have recently been changed by human activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lyons, S Kathleen -- Amatangelo, Kathryn L -- Behrensmeyer, Anna K -- Bercovici, Antoine -- Blois, Jessica L -- Davis, Matt -- DiMichele, William A -- Du, Andrew -- Eronen, Jussi T -- Faith, J Tyler -- Graves, Gary R -- Jud, Nathan -- Labandeira, Conrad -- Looy, Cindy V -- McGill, Brian -- Miller, Joshua H -- Patterson, David -- Pineda-Munoz, Silvia -- Potts, Richard -- Riddle, Brett -- Terry, Rebecca -- Toth, Aniko -- Ulrich, Werner -- Villasenor, Amelia -- Wing, Scott -- Anderson, Heidi -- Anderson, John -- Waller, Donald -- Gotelli, Nicholas J -- England -- Nature. 2016 Jan 7;529(7584):80-3. doi: 10.1038/nature16447. Epub 2015 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA. ; Department of Environmental Science and Biology, The College at Brockport - SUNY, Brockport, New York 14420, USA. ; School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA. ; Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA. ; Hominid Paleobiology Doctoral Program, Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, George Washington University, Washington DC 20052, USA. ; Department of Geosciences and Geography, University of Helsinki, PO Box 64, 00014 University of Helsinki, Finland. ; School of Social Science, The University of Queensland, Brisbane, Queensland 4072, Australia. ; Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA. ; Center for Macroecology, Evolution and Climate, University of Copenhagen, Copenhagen 2100, Denmark. ; Biological Sciences Graduate Program, University of Maryland, College Park, Maryland 20742, USA. ; Florida Museum of Natural History, University of Florida, Gainsville, Florida 32611, USA. ; Department of Entomology, University of Maryland College Park, College Park, Maryland 20742, USA. ; Key Lab of Insect Evolution and Environmental Changes, Capital Normal University, Beijing 100048, China. ; Department of Integrative Biology and Museum of Paleontology, University of California Berkeley, Berkeley, California 94720, USA. ; School Biology and Ecology &Sustainability Solutions Initiative, University of Maine, Orono, Maine 04469, USA. ; Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA. ; Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia. ; Department of Anthropology, Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington DC 20013, USA. ; School of Life Sciences, University of Nevada-Las Vegas, Las Vegas, Nevada 89154, USA. ; Department of Integrative Biology, Oregon State University, Corvallis, Oregon 97331, USA. ; Chair of Ecology and Biogeography, Nicolaus Copernicus University, Lwowska 1, 87-100 Torun, Poland. ; Evolutionary Studies Institute, University of the Witwatersrand, Jorissen Street, Braamfontein, Johannesburg 2001, South Africa. ; Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. ; Department of Biology, University of Vermont, Burlington, Vermont 05405, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26675730" target="_blank"〉PubMed〈/a〉
    Keywords: Agriculture/*history ; Animals ; *Ecosystem ; History, Ancient ; Human Activities/*history ; Humans ; North America ; *Plant Physiological Phenomena ; Population Dynamics ; Time Factors
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    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2019-07-13
    Description: Fused silica window systems are used heavily on crewed reentry vehicles, and they are currently being used on the next generation of US crewed spacecraft, Orion. These systems improve crew situational awareness and comfort, as well as, insulating the reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on a fused silica window system proposed for the Orion spacecraft. A ballistic limit equation that describes the threshold of perforation of a fuse silica pane over a broad range of impact velocities, obliquities and projectile materials is discussed here.
    Keywords: Space Transportation and Safety
    Type: JSC-CN-32614 , Hypervelocity Impact Symposium; Apr 26, 2015 - Apr 30, 2015; Boulder, CO; United States
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  • 8
    Publication Date: 2019-07-19
    Description: The Orion spacecraft's windows are exposed to the micrometeroid and orbital debris (MMOD) space environments while in space as well as the Earth entry environment at the mission's conclusion. The need for a low-mass spacecraft window design drives the need to reduce conservatism when assessing the design for loss of crew due to MMOD impact and subsequent Earth entry. Therefore, work is underway at NASA and Lockheed Martin to improve characterization of the complete penetration ballistic limit of an outer fused silica thermal pane. Hypervelocity impact tests of the window configuration at up to 10 km/s and hydrocode modeling have been performed with a variety of projectile materials to enable refinement of the fused silica ballistic limit equation.
    Keywords: Space Transportation and Safety
    Type: JSC-CN-31174 , Hypervelocity Impact Symposium (HVIS); Apr 27, 2015 - May 01, 2015; Boulder, CO; United States
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  • 9
    Publication Date: 2019-07-19
    Description: While orbital debris of ten centimeters or more are tracked and catalogued, the difficulty of finding and accurately accounting for forces acting on the objects near the ten centimeter threshold results in both uncertainty of their presence and location. These challenges result in difficult decisions for operators balancing potential costly operational approaches with system loss risk. In this paper, the assessment of the feasibility of protecting a spacecraft from this catalogued debris is described using numerical simulations and a test of a multi-shock shield system against a cylindrical projectile impacting normal to the surface with approximately 15 MJ of kinetic energy. The hypervelocity impact test has been conducted at the Arnold Engineering Development Complex (AEDC) with a 598 g projectile at 6.905 km/s on a NASA supplied multi-shock shield. The projectile used is a hollow aluminum and nylon cylinder with an outside diameter of 8.6 cm and length of 10.3 cm. Figure 1 illustrates the multi-shock shield test article, which consisted of five separate bumpers, four of which are fiberglass fabric and one of steel mesh, and two rear walls, each consisting of Kevlar fabric. The overall length of the test article was 2.65 m. The test article was a 5X scaled-up version of a smaller multi-shock shield previously tested using a 1.4 cm diameter aluminum projectile for an inflatable module project. The distances represented by S1 and S1/2 in the figure are 61 cm and 30.5 cm, respectively. Prior to the impact test, hydrodynamic simulations indicated that some enhancement to the standard multi-shock system is needed to address the effects of the cylindrical shape of the projectile. Based on the simulations, a steel mesh bumper has been added to the shield configuration to enhance the fragmentation of the projectile. The AEDC test occurred as planned, and the modified NASA multi-shock shield successfully stopped 598 g projectile using 85.6 kg/m(exp 2). The fifth bumper layer remained in tact, although it was torn free from its support structure and thrown into the first rear wall. The outer Kevlar layer of the first rear wall tore likely from the impact of the fifth bumper's support structure, but the back of the rear wall was intact. No damage occurred to the second rear wall, or to the witness plate behind the target.
    Keywords: Space Transportation and Safety
    Type: JSC-CN-31055 , Hypervelocity Impact Symposium; Apr 27, 2015 - May 01, 2015; Boulder, CO; United States
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