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  • 1
    Publication Date: 2016-01-02
    Description: Eusocial insects organize themselves into behavioral castes whose regulation has been proposed to involve epigenetic processes, including histone modification. In the carpenter ant Camponotus floridanus, morphologically distinct worker castes called minors and majors exhibit pronounced differences in foraging and scouting behaviors. We found that these behaviors are regulated by histone acetylation likely catalyzed by the conserved acetyltransferase CBP. Transcriptome and chromatin analysis in brains of scouting minors fed pharmacological inhibitors of CBP and histone deacetylases (HDACs) revealed hundreds of genes linked to hyperacetylated regions targeted by CBP. Majors rarely forage, but injection of a HDAC inhibitor or small interfering RNAs against the HDAC Rpd3 into young major brains induced and sustained foraging in a CBP-dependent manner. Our results suggest that behavioral plasticity in animals may be regulated in an epigenetic manner via histone modification.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Simola, Daniel F -- Graham, Riley J -- Brady, Cristina M -- Enzmann, Brittany L -- Desplan, Claude -- Ray, Anandasankar -- Zwiebel, Laurence J -- Bonasio, Roberto -- Reinberg, Danny -- Liebig, Jurgen -- Berger, Shelley L -- 2009005/Howard Hughes Medical Institute/ -- DP2MH107055/DP/NCCDPHP CDC HHS/ -- T32HD083185/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 2016 Jan 1;351(6268):aac6633. doi: 10.1126/science.aac6633.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. Program in Epigenetics, University of Pennsylvania, Philadelphia, PA 19104, USA. simola@upenn.edu danny.reinberg@nyumc.org juergen.liebig@asu.edu bergers@upenn.edu. ; Program in Epigenetics, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA. ; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. Program in Epigenetics, University of Pennsylvania, Philadelphia, PA 19104, USA. ; School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA. ; Department of Biology, New York University, New York, NY 10003, USA. ; Department of Entomology, University of California, Riverside, CA 92521, USA. ; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA. ; Department of Molecular Pharmacology and Biochemistry, New York University School of Medicine, New York, NY 10016, USA. simola@upenn.edu danny.reinberg@nyumc.org juergen.liebig@asu.edu bergers@upenn.edu. ; School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA. simola@upenn.edu danny.reinberg@nyumc.org juergen.liebig@asu.edu bergers@upenn.edu. ; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. Program in Epigenetics, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. simola@upenn.edu danny.reinberg@nyumc.org juergen.liebig@asu.edu bergers@upenn.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26722000" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylation ; Animals ; Ants/drug effects/*genetics/*physiology ; *Behavior, Animal ; Chromatin/metabolism ; *Epigenesis, Genetic ; Histone Deacetylase 2/antagonists & inhibitors/genetics/*physiology ; Histone Deacetylase Inhibitors/pharmacology ; Protein Processing, Post-Translational ; *Social Behavior ; Social Class ; Transcriptome
    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: 2015-11-07
    Description: High-diversity mixtures of native tallgrass prairie vegetation should be effective biomass feedstocks because of their high productivity and low input requirements. These diverse mixtures should also enhance several of the ecosystem services provided by the traditional monoculture feedstocks used for bioenergy. In this study, we compared biomass production, year-to-year variation in biomass production, and resistance to weed invasion in four prairie biomass feedstocks with different diversity: 1 species - a switchgrass monoculture; 5 species - a mix of C 4 grasses; 16 species - a mix of grasses, forbs and legumes; and 32 species - a mix of grasses, forbs, legumes, and sedges. Each diversity treatment was replicated four times on three soil types for a total of 48 research plots (0.33 – 0.56 ha each). We measured biomass production by harvesting all plant material to ground level in ten randomly selected quadrats per plot. Weed biomass was measured as a subset of total biomass. We replicated this design over a five-year period (2010 – 2014). Across soil types, the 1-, 16-, and 32-species treatments produced the same amount of biomass, but the 1-species treatment produced significantly more biomass than the 5-species treatment. The rank order of our four diversity treatments differed between soil types suggesting that soil type influences treatment productivity. Year-to-year variation in biomass production did not differ between diversity treatments. Weed biomass was higher in the 1-species treatment than the 5-, 16-, and 32-species treatments. The high productivity and low susceptibility to weed invasion of our 16- and 32-species treatments supports the hypothesis that high-diversity prairie mixtures would be effective biomass feedstocks in the Midwestern United States. The influence of soil type on relative feedstock performance suggests that seed mixes used for biomass should be specifically tailored to site characteristics for maximum productivity and stand success. This article is protected by copyright. All rights reserved.
    Print ISSN: 1757-1693
    Electronic ISSN: 1757-1707
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley
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  • 3
    Publication Date: 2019
    Description: Abstract According to the Snowball Earth hypothesis, Earth has experienced periods of low‐latitude glaciation in its deep past. Prior studies have used general circulation models (GCMs) to examine the effects such an extreme climate state might have on the structure and dynamics of Earth's troposphere, but the behavior of the stratosphere has not been studied in detail. Understanding the snowball stratosphere is important for developing an accurate account of the Earth's radiative and chemical properties during these episodes. Here we conduct the first analysis of the stratospheric circulation of the Snowball Earth using ECHAM6 general circulation model simulations. In order to understand the factors contributing to the stratospheric circulation, we extend the Statistical Transformed Eulerian Mean framework. We find that the stratosphere during a snowball with prescribed modern ozone levels exhibits a weaker meridional overturning circulation, reduced wave activity, and stronger zonal jets and is extremely cold relative to modern conditions. Notably, the snowball stratosphere displays no sudden stratospheric warmings. Without ozone, the stratosphere displays a complete lack of polar vortex and even colder temperatures. We also explicitly quantify for the first time the cross‐tropopause mass exchange rate and stratospheric mixing efficiency during the snowball and show that our values do not change the constraints on CO2 inferred from geochemical proxies during the Marinoan glaciation (ca. 635 Ma), unless the O2 concentration during the snowball was orders of magnitude less than the CO2 concentration.
    Print ISSN: 2169-897X
    Electronic ISSN: 2169-8996
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 11 (1972), S. 160-164 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 11 (1972), S. 164-169 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4551-4556 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An asymmetric triangular quantum well was grown by molecular-beam epitaxy using a digital alloy composition grading method. A high-resolution electron micrograph (HREM), a computational model, and room-temperature photoluminescence were used to extract the spatial compositional dependence of the quantum well. The HREM micrograph intensity profile was used to determine the shape of the quantum well. A Fourier series method for solving the BenDaniel–Duke Hamiltonian [D. J. BenDaniel and C. B. Duke, Phys. Rev. 152, 683 (1966)] was then used to calculate the bound energy states within the envelope function scheme for the measured well shape. These calculations were compared to the E11h, E11l, and E22l transitions in the room-temperature photoluminescence and provided a self-consistent compositional profile for the quantum well. A comparison of energy levels with a linearly graded well is also presented.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4933-4943 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN films have been epitaxially grown onto (001) Si by electron cyclotron resonance microwave-plasma-assisted molecular-beam epitaxy, using a two-step growth process, in which a GaN buffer is grown at relatively low temperatures and the rest of the film is grown at higher temperatures. This method of film growth was shown to lead to good single-crystalline β-GaN and to promote lateral growth resulting in smooth surface morphology. The full width at half-maximum of the x-ray rocking curve in the best case was found to be 60 min. Optical-absorption measurements indicate that the band gap of β-GaN is 3.2 eV and the index of the refraction below the absorption edge is 2.5. Conductivity measurements indicate that the films may have a carrier concentration below 1017 cm−3.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3212-3218 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Defects and impurities in diamond films grown by chemical vapor deposition (CVD) were analyzed by high-resolution cathodoluminescence (CL) spectroscopy and imaging in transmission electron microscopy (TEM). The combination of CL and TEM makes it possible to correlate the film microstructure with the electronic structure due to defects. Broad CL bands observed at 428±1 nm (2.90±0.01 eV) and 551±1 nm (2.250±0.004 eV) are attributed to closely spaced and widely separated donor-acceptor (D-A) pairs, respectively. A narrow peak at 738.7±0.5 nm (1.679±0.001 eV) is attributed to interstitial silicon atom impurities. An additional wide band at 365±1 nm (3.40±0.01 eV) was not identified. The material was found to be type IIb (semiconducting) and varied in quality with the growth conditions. Impurities are evidently distributed nonuniformly on a submicrometer scale, and both highly faulted and defect-free grains were found to emit no visible CL. For the first time in CVD-grown diamond, band-A CL due to closely spaced D-A pairs was found to be directly correlated with dislocations. Widely spaced D-A pairs were more uniformly distributed throughout the film. The distribution of interstitial silicon impurities varied greatly from grain to grain, but was not correlated with any microstructure.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 4723-4727 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transient annealing of a sequentially deposited metallization scheme, Au/Ni/Au/Ge/Ni, was used to obtain low resistivity ohmic contacts to GaAs-AlGaAs based modulation-doped field-effect transistors. Cross-sectional transmission electron microscopy and energy dispersive x-ray analysis techniques were employed to determine the type and distribution of various phases formed. Three different phases, namely, Au rich, Ni-Ge, and Ni-As(Ge), were observed. The Ni-As(Ge) phase was found to be in contact with GaAs. The Ni-Ge phase was present in localized regions in the Au-rich phase. Also, the Ni-Ge phase was found to be in direct contact with either Ni-As(Ge) or with GaAs. The Au-rich region manifested itself as a layered structure and was observed above the Ni-As(Ge) phase. As a consequence of the anneal cycle, movement of contact material both parallel and perpendicular to the device surface occurred at the metallization edges.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 1311-1316 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cathodoluminescence (CL) has been used to investigate the nature of n-type InP directly underneath AuGeNi ohmic contacts subjected to various heat treatments. The study of this contact system by CL has shown directly that the quality of the underlying InP is significantly modified up to distances of several microns from the contact interface. These changes are brought about by the interaction of the contact components with the semiconductor. Contrary to the widely accepted view, no evidence of n+ doping of the InP by Ge was observed in any of the contacts examined. Possible explanations for the observed reduction in CL efficiency obtained from the InP close to the contact interface are discussed.
    Type of Medium: Electronic Resource
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