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  • 1
    Publication Date: 2015-10-30
    Description: We conducted a series of experiments to explore the rate and state frictional properties of gabbro at conditions thought to be representative of slow slip events (SSEs) in subduction zones. The experiments were conducted using a heated direct shear apparatus. We tested both solid and simulated gouge samples at low effective normal stress (5-30 MPa) over a broad range of temperatures (20–600°C) under dry and hydrated conditions. In tests performed on dry solid samples we observed stable sliding at low temperatures (20–150°C), stick-slip at high temperatures (350–600°C) and a transitional “episodic slow slip” behavior at intermediate temperatures (200–300°C). In tests performed on dry gouge samples we observed stable sliding at all temperatures. Under hydrated conditions, the gouge samples exhibited episodic slow slip and stick-slip behavior at temperatures between 300–500°C. Our results show a decrease in the rate parameter (a– b) with temperature for both solid and gouge samples; friction transitions from velocity-strengthening to velocity-weakening at temperature of about 150°C for both solid and gouge samples. We do not observe transition to velocity-strengthening friction at the high end of the tested temperature range. Our results suggest that the occurrence of slow slip events and the downdip limit of the seismogenic zone on subduction megathrusts cannot be solely explained by the temperature dependence of frictional properties of gabbro. Further experimental studies are needed to evaluate the effects of water fugacity and compositional heterogeneity (e.g., the presence of phyllosilicates) on frictional stability of subduction megathrusts. This article is protected by copyright. All rights reserved.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Publication Date: 2014-09-19
    Description: Next-generation DNA sequencing (NGS) produces vast amounts of DNA sequence data, but it is not specifically designed to generate data suitable for genetic mapping. Recently developed DNA library preparation methods for NGS have helped solve this problem, however, by combining the use of reduced representation libraries with DNA sample barcoding to generate genome-wide genotype data from a common set of genetic markers across a large number of samples. Here we use such a method, called genotyping-by-sequencing (GBS), to produce a data set for genetic mapping in an F1 population of apples ( Malus x domestica ) segregating for skin color. We show that GBS produces a relatively large, but extremely sparse, genotype matrix: over 270,000 SNPs were discovered but most SNPs have too much missing data across samples to be useful for genetic mapping. After filtering for genotype quality and missing data, only 6% of the 85 million DNA sequence reads contributed to useful genotype calls. Despite this limitation, using existing software and a set of simple heuristics, we generated a final genotype matrix containing 3967 SNPs from 89 DNA samples from a single lane of Illumina HiSeq and used it to create a saturated genetic linkage map and to identify a known QTL underlying apple skin color. We therefore demonstrate that GBS is a cost-effective method for generating genome-wide SNP data suitable for genetic mapping in a highly diverse and heterozygous agricultural species. We anticipate future improvements to the GBS analysis pipeline presented here that will enhance the utility of next-generation DNA sequence data for the purposes of genetic mapping across diverse species.
    Electronic ISSN: 2160-1836
    Topics: Biology
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  • 3
    Publication Date: 2009-10-23
    Description: Millions of people regularly obtain insufficient sleep. Given the effect of sleep deprivation on our lives, understanding the cellular and molecular pathways affected by sleep deprivation is clearly of social and clinical importance. One of the major effects of sleep deprivation on the brain is to produce memory deficits in learning models that are dependent on the hippocampus. Here we have identified a molecular mechanism by which brief sleep deprivation alters hippocampal function. Sleep deprivation selectively impaired 3', 5'-cyclic AMP (cAMP)- and protein kinase A (PKA)-dependent forms of synaptic plasticity in the mouse hippocampus, reduced cAMP signalling, and increased activity and protein levels of phosphodiesterase 4 (PDE4), an enzyme that degrades cAMP. Treatment of mice with phosphodiesterase inhibitors rescued the sleep-deprivation-induced deficits in cAMP signalling, synaptic plasticity and hippocampus-dependent memory. These findings demonstrate that brief sleep deprivation disrupts hippocampal function by interfering with cAMP signalling through increased PDE4 activity. Thus, drugs that enhance cAMP signalling may provide a new therapeutic approach to counteract the cognitive effects of sleep deprivation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2783639/" 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/PMC2783639/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vecsey, Christopher G -- Baillie, George S -- Jaganath, Devan -- Havekes, Robbert -- Daniels, Andrew -- Wimmer, Mathieu -- Huang, Ted -- Brown, Kim M -- Li, Xiang-Yao -- Descalzi, Giannina -- Kim, Susan S -- Chen, Tao -- Shang, Yu-Ze -- Zhuo, Min -- Houslay, Miles D -- Abel, Ted -- 84256/Canadian Institutes of Health Research/Canada -- AG017628/AG/NIA NIH HHS/ -- G0600765/Medical Research Council/United Kingdom -- GM07517/GM/NIGMS NIH HHS/ -- HL060287/HL/NHLBI NIH HHS/ -- HL07953/HL/NHLBI NIH HHS/ -- P01 AG017628/AG/NIA NIH HHS/ -- P01 AG017628-080006/AG/NIA NIH HHS/ -- P50 HL060287/HL/NHLBI NIH HHS/ -- P50 HL060287-100006/HL/NHLBI NIH HHS/ -- England -- Nature. 2009 Oct 22;461(7267):1122-5. doi: 10.1038/nature08488.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19847264" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Colforsin/pharmacology ; Cyclic AMP/*metabolism ; Cyclic AMP-Dependent Protein Kinases/metabolism ; Cyclic Nucleotide Phosphodiesterases, Type 4/metabolism ; Hippocampus/drug effects/enzymology/*metabolism/physiology ; Long-Term Potentiation/drug effects ; Male ; Memory/drug effects/physiology ; Mice ; Mice, Inbred C57BL ; Neuronal Plasticity ; Phosphodiesterase 4 Inhibitors ; Rolipram/pharmacology ; *Second Messenger Systems/drug effects ; Sleep Deprivation/*physiopathology ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2008-07-19
    Description: The West Antarctic Peninsula is one of the fastest warming regions on Earth, and, as a consequence, most maritime glaciers and ice shelves in the region have significantly retreated over the past few decades. We collected a multiyear data set on ice scouring frequency from Antarctica by using unique experimental markers and scuba diving surveys. We show that the annual intensity of ice scouring is negatively correlated with the duration of the winter fast ice season. Because fast ice extent and duration is currently in decline in the region after recent rapid warming, it is likely that marine benthic communities are set for even more scouring in the near future.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smale, Dan A -- Brown, Kirsty M -- Barnes, David K A -- Fraser, Keiron P P -- Clarke, Andrew -- New York, N.Y. -- Science. 2008 Jul 18;321(5887):371. doi: 10.1126/science.1158647.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉British Antarctic Survey (BAS), Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18635794" 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: 2012-08-31
    Description: Laboratory studies of frictional properties of rocks at slip velocities approaching the seismic range ( approximately 0.1-1 m s(-1)), and at moderate normal stresses (1-10 MPa), have revealed a complex evolution of the dynamic shear strength, with at least two phases of weakening separated by strengthening at the onset of wholesale melting. The second post-melting weakening phase is governed by viscous properties of the melt layer and is reasonably well understood. The initial phase of extreme weakening, however, remains a subject of much debate. Here we show that the initial weakening of gabbro is associated with the formation of hotspots and macroscopic streaks of melt ('melt welts'), which partially unload the rest of the slip interface. Melt welts begin to form when the average rate of frictional heating exceeds 0.1-0.4 MW m(-2), while the average temperature of the shear zone is well below the solidus (250-450 degrees C). Similar heterogeneities in stress and temperature are likely to occur on natural fault surfaces during rapid slip, and to be important for earthquake rupture dynamics.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brown, Kevin M -- Fialko, Yuri -- England -- Nature. 2012 Aug 30;488(7413):638-41. doi: 10.1038/nature11370.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA. kmbrown@ucsd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22932388" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2011-11-15
    Description: So far, two genes associated with familial melanoma have been identified, accounting for a minority of genetic risk in families. Mutations in CDKN2A account for approximately 40% of familial cases, and predisposing mutations in CDK4 have been reported in a very small number of melanoma kindreds. Here we report the whole-genome sequencing of probands from several melanoma families, which we performed in order to identify other genes associated with familial melanoma. We identify one individual carrying a novel germline variant (coding DNA sequence c.G1075A; protein sequence p.E318K; rs149617956) in the melanoma-lineage-specific oncogene microphthalmia-associated transcription factor (MITF). Although the variant co-segregated with melanoma in some but not all cases in the family, linkage analysis of 31 families subsequently identified to carry the variant generated a log of odds (lod) score of 2.7 under a dominant model, indicating E318K as a possible intermediate risk variant. Consistent with this, the E318K variant was significantly associated with melanoma in a large Australian case-control sample. Likewise, it was similarly associated in an independent case-control sample from the United Kingdom. In the Australian sample, the variant allele was significantly over-represented in cases with a family history of melanoma, multiple primary melanomas, or both. The variant allele was also associated with increased naevus count and non-blue eye colour. Functional analysis of E318K showed that MITF encoded by the variant allele had impaired sumoylation and differentially regulated several MITF targets. These data indicate that MITF is a melanoma-predisposition gene and highlight the utility of whole-genome sequencing to identify novel rare variants associated with disease susceptibility.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3266855/" 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/PMC3266855/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yokoyama, Satoru -- Woods, Susan L -- Boyle, Glen M -- Aoude, Lauren G -- MacGregor, Stuart -- Zismann, Victoria -- Gartside, Michael -- Cust, Anne E -- Haq, Rizwan -- Harland, Mark -- Taylor, John C -- Duffy, David L -- Holohan, Kelly -- Dutton-Regester, Ken -- Palmer, Jane M -- Bonazzi, Vanessa -- Stark, Mitchell S -- Symmons, Judith -- Law, Matthew H -- Schmidt, Christopher -- Lanagan, Cathy -- O'Connor, Linda -- Holland, Elizabeth A -- Schmid, Helen -- Maskiell, Judith A -- Jetann, Jodie -- Ferguson, Megan -- Jenkins, Mark A -- Kefford, Richard F -- Giles, Graham G -- Armstrong, Bruce K -- Aitken, Joanne F -- Hopper, John L -- Whiteman, David C -- Pharoah, Paul D -- Easton, Douglas F -- Dunning, Alison M -- Newton-Bishop, Julia A -- Montgomery, Grant W -- Martin, Nicholas G -- Mann, Graham J -- Bishop, D Timothy -- Tsao, Hensin -- Trent, Jeffrey M -- Fisher, David E -- Hayward, Nicholas K -- Brown, Kevin M -- 10118/Cancer Research UK/United Kingdom -- 10589/Cancer Research UK/United Kingdom -- AR043369-14/AR/NIAMS NIH HHS/ -- C490/A11021/Cancer Research UK/United Kingdom -- C588/A10589/Cancer Research UK/United Kingdom -- C588/A4994/Cancer Research UK/United Kingdom -- C8197/A10123/Cancer Research UK/United Kingdom -- C8216/A6129/Cancer Research UK/United Kingdom -- CA88363/CA/NCI NIH HHS/ -- K24CA149202/CA/NCI NIH HHS/ -- P50CA9368/CA/NCI NIH HHS/ -- R01 AR043369/AR/NIAMS NIH HHS/ -- R01 CA-83115-01A2/CA/NCI NIH HHS/ -- R01 CA088363/CA/NCI NIH HHS/ -- R01 CA088363-09/CA/NCI NIH HHS/ -- R01 CA83115/CA/NCI NIH HHS/ -- England -- Nature. 2011 Nov 13;480(7375):99-103. doi: 10.1038/nature10630.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Dermatology, Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Massachusetts 02114, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22080950" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Aged ; Aged, 80 and over ; Female ; Gene Expression Regulation, Neoplastic ; *Genetic Predisposition to Disease ; Humans ; Male ; Melanoma/*genetics ; Microphthalmia-Associated Transcription Factor/*genetics ; Middle Aged ; *Mutation ; Sumoylation/genetics ; Young Adult
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2013-03-20
    Description: [1]  Temperature is believed to have an important control on frictional properties of rocks, yet the amount of experimental observations of time-dependent rock friction at high temperatures is rather limited. In this study, we investigated frictional healing of Westerly granite in a series of slide-hold-slide experiments using a direct shear apparatus at ambient temperatures between 20°C and 550°C. We observed that at room temperature coefficient of friction increases in proportion to the logarithm of hold time at a rate consistent with findings of previous studies. For a given hold time, the coefficient of friction linearly increases with temperature, but temperature has little effect on the rate of change in static friction with hold time. We used a numerical model to investigate whether time-dependent increases in real contact area between rough surfaces could account for the observed frictional healing. The model incorporates fractal geometry and temperature-dependent viscoelasoplastic rheology. We explored several candidate rheologies that have been proposed for steady state creep of rocks at high stresses and temperatures. None of the tested laws could provide an agreement between the observed and modeled healing behavior given material properties reported in the bulk creep experiments. An acceptable fit to the experimental data could be achieved with modified parameters. In particular, for the power-law rheology to provide a reasonable fit to the data, the stress exponent needs to be greater than 40. Alternative mechanisms include time-dependent gouge compaction and increases in bond strength between contacting asperities.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
    Publication Date: 2016-08-28
    Description: The deep limit to seismicity in continental crust is believed to be controlled by a transition from velocity-weakening to velocity-strengthening friction based on experimental measurements of the rate dependence of friction at different temperatures. Available experimental data on granite suggest a transition to stable creep at about 350 ° C (∼15 km depth). Here we present results from unconfined experiments on Westerly granite at both dry and hydrated conditions that show increasingly unstable slip (velocity-weakening behavior) at temperature up to 600 ° C. A comparison of previously published experimental results with those presented in this study suggests that the rate and state friction parameters strongly depend on normal stress and pore pressure at high (〉400 ° C) temperature, which may help explain regional variations in the depth distribution of earthquakes in continental crust. Temperature dependence of the rate and state friction parameters may also contribute to strong dynamic weakening observed in high-speed friction experiments on crystalline rocks such as granite and gabbro.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
    Publication Date: 1999-01-01
    Print ISSN: 0149-1423
    Electronic ISSN: 1943-2674
    Topics: Geosciences
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  • 10
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Equilibrium resonant tunneling between an array of quasi-one-dimensional wires and two-dimensional electron gas has been studied as a function of the Fermi energy of the tunneling electrons, which was varied by the bias voltage applied to an in-built back gate. The equilibrium resonant tunneling differential conductance, measured in the double quantum well system, reflects both the electron density and wave functions of the one-dimensional electron gas. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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