822 research outputs found

    Complexity reduction of astrochemical networks

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    We present a new computational scheme aimed at reducing the complexity of the chemical networks in astrophysical models, one which is shown to markedly improve their computational efficiency. It contains a flux-reduction scheme that permits to deal with both large and small systems. This procedure is shown to yield a large speed-up of the corresponding numerical codes and provides good accord with the full network results. We analyse and discuss two examples involving chemistry networks of the interstellar medium and show that the results from the present reduction technique reproduce very well the results from fuller calculations.Comment: 9 pages, 7 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa

    Reversible Fluorination of Graphene: towards a Two-Dimensional Wide Bandgap Semiconductor

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    We report the synthesis and evidence of graphene fluoride, a two-dimensional wide bandgap semiconductor derived from graphene. Graphene fluoride exhibits hexagonal crystalline order and strongly insulating behavior with resistance exceeding 10 GΩ\Omega at room temperature. Electron transport in graphene fluoride is well described by variable-range hopping in two dimensions due to the presence of localized states in the band gap. Graphene obtained through the reduction of graphene fluoride is highly conductive, exhibiting a resistivity of less than 100 kΩ\Omega at room temperature. Our approach provides a new path to reversibly engineer the band structure and conductivity of graphene for electronic and optical applications.Comment: 7 pages, 5 figures, revtex, to appear in PR

    Immunohistochemical expression of SKALP/elafin in squamous cell carcinoma of the oesophagus.

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    In this study, the immunohistochemical expression of a new inducible elastase inhibitor, SKALP (skin-derived anti-leucoproteinase)/elafin, in the tissue of squamous cell carcinoma and uninvolved oesophageal mucosa was studied using a polyclonal rabbit anti-serum against SKALP/elafin. The results were compared with the immunohistochemical staining of proliferating cell nuclear antigen (PCNA) and the TUNEL assay in serial sections. In non-malignant oesophageal mucosa, the expression of SKALP/elafin was localized in the cells of the stratified zone overlying the PCNA-positive basal zone. In oesophageal cancer, the incidence of the expression was significantly related to the degree of the differentiation of the tumour. Characteristically, the expression was almost limited in tumour cell nests that had a clear squamous phenotype. In tumour cell nests, the expression of SKALP/elafin was localized in the cells overlying PCNA-expressing cells and no expression was found in the cells that expressed PCNA; DNA fragmentation was often observed in the same cell layers as those in which SKALP/elafin immunoreactivity was found. This enzyme inhibitor is speculated to be involved in the induction of the cell differentiation and apoptosis of human squamous cell carcinoma cells of the oesophagus

    The Ursinus Weekly, February 27, 1956

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    Robin Blood elected May queen; Jody Myers is mgr. • Phila. Art Museum holds exhibition • Dr. Rice offers non-credit course in Esperanto • Dean\u27s list for Fall semester is released • Freshman dinner, buzz groups on marriage highlight Y activities • Lawhead, Stevenson editors for 1957 Ruby • MSGA plans new activities comm. • Pre-meds to hear Mr. Nevin Kressley • Work begins on charity drive • French Club meets Friday • Student day of prayer • Use your lost and found • Editorial: Other side of the coin • Live, love, and learn: A religious ethic for college men and women • Faculty places blame for dead weekends on students • He ran uneasily: A poem of wartime • Tired of the everyday grind; Want to get away from it all? Try flying • Bruins win tune-ups for MACs this week: Gettysburg, Lafayette picked to battle for MAC crown; Padula, Prutzman to win division titles • Cagers clobbered twice by Drexel, Haverford quintets • Gros tallies 41 as Belles beat Beaver • Badminton Belles win two, 5-0, 4-1 • Bryn Mawr edges Ursinus swimmers • Open letter to the student body • Operation car wash begins Mar. 5 • Fraternity row • March 6 is the date of Curtain Club production • Frosh plan activitieshttps://digitalcommons.ursinus.edu/weekly/1444/thumbnail.jp

    Observation of Magnon Polarization

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    We measure the mode-resolved direction of the precessional motion of the magnetic order, i.e., magnon polarization, via the chiral term of inelastic polarized neutron scattering spectra. The magnon polarization is a unique and unambiguous signature of magnets and is important in spintronics, affecting thermodynamic properties such as the magnitude and sign of the spin Seebeck effect. However, it has never been directly measured in any material until this work. The observation of both signs of magnon polarization in Y3Fe5O12 also gives direct proof of its ferrimagnetic nature. The experiments agree very well with atomistic simulations of the scattering cross section
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